阅读说明：本技术 通过增压渗透和协同效应产生大型可再生能源的方法和装置 (Method and device for generating large renewable energy sources by means of pressurized osmosis and synergistic effects ) 是由 吕正雄 于 2020-12-11 设计创作，主要内容包括：本发明涉及一种通过增压渗透(Pressure-Enhanced Osmosis,简称PEO)和协同效应(Synergistic Effects)的技术用以最大程度地产生大规模可再生能源的方法和装置。本法通过稀释系数(Dilution Factor)β值的增大来增加最大发电量用以设计PEO模块,从而将功率输出提高到传统阻尼渗透(Pressure-Retarded Osmosis,简称PRO)方法的十倍以上,并且通过结合协同效应以形成两种类型的PEO系统,以进一步产生更多的功率：(1)PEO地表系统,其中协同效应通过正渗透(FO)和纳滤(NF)或超滤(UF)的综合效果,以及应用能量交换和流体回收装置以重新浓缩驱动液(draw solution)的方法来实现上述效果,(2)PEO地下系统,其中协同效应通过施加重力,以及施加来自发电的废热及施加流体升力来实现上述效果。(The present invention relates to a method and apparatus for maximizing the generation of large-scale renewable energy sources through the technologies of Pressure-Enhanced osmoses (PEO) and Synergistic Effects (Synergistic Effects). The method increases the maximum power generation amount by increasing the beta value of the Dilution Factor (Dilution Factor) to design a PEO module, thereby improving the power output to more than ten times of the traditional damping-infiltration (PRO) method, and forms two types of PEO systems by combining the synergistic effect to further generate more power: (1) PEO surface systems, where synergistic effects are achieved through the combined effects of Forward Osmosis (FO) and Nanofiltration (NF) or Ultrafiltration (UF), and methods of applying energy exchange and fluid recovery devices to re-concentrate the draw solution (2) PEO subsurface systems, where synergistic effects are achieved by the application of gravity, as well as the application of waste heat from power generation and the application of fluid lift.)

1. A method for maximizing the production of large-scale renewable energy sources by pressurized-Enhanced osmoses (PEO) and Synergistic Effects (Synergistic Effects), wherein the pressurized-osmotic energy production method comprises the following steps:

(1) a PEO module is used as a Forward Osmosis (FO) module and is controlled in a steady state and continuous flow state to input a driving liquid (draw solution) and a feed liquid (feed solution) to generate an osmotic flux (permeate flux),

(2) the PEO module is selected to have a dilution factor β in the range of 0.85 to 0.95, more preferably in the range of 0.9 to 0.95, where β ═ Q₂/(Q₁+Q₂)，Q₁Is the osmotic flux, Q₂Is the input of the flow rate of the driving liquid,

(3) selecting Q according to the practical range₁Or Q₂When Q is selected₁Then, another Q can be estimated according to the formula listed in the above step (2)₂And vice versa,

(4) at a fluid pressure p₂The draw solution was introduced into the draw solution compartment of the PEO module, where p₂＝1/2αβΔπ_oAnd α is the membrane efficiency coefficient of the PEO module, representing the percentage of pressure loss across the semi-permeable membrane of the PEO module, Δ π_oIs the theoretical maximum osmotic pressure differential for the PEO module,

(5) designing the total membrane area A, wherein A ═ Q₁/(1/2βJ_e)，J_eIs at Δ π_eUnit permeation flux of the membrane, J_eCan be obtained by data provided by the film supplier or by experiments, while Δ π_eRepresenting the maximum effective osmotic pressure difference Δ π_e＝αΔπ_o，

(6) The energy produced by the PEO module has a theoretical maximum power output of W_maxWherein W is_max＝p₂(Q₁+Q₂)。

2. The PEO module of claim 1 being a pressure vessel comprising:

(1) a plurality of tubular membrane forward osmosis modules comprising a plurality of porous housings to accommodate a plurality of forward osmosis tubular membrane tubes to flow feed liquid inside the osmotic membrane tubes and to generate an osmotic flux,

(2) a plurality of agitators comprising a plurality of combined propellers and turbine blades for homogenizing a driving liquid within the pressure vessel and reducing the effect of external concentration polarization of the tubular membrane module,

(3) stainless steel housing for holding beta and Q selected by the driving liquid₂Value generated pressure p₂And houses a plurality of tubular forward osmosis modules and agitators,

(4) a drive liquid inflow control valve and a pump for controlling the inflow rate of the drive liquid,

(5) the drive liquid flows into and out of the check valve to prevent backflow,

(6) feed liquid flows into and out of the check valve to prevent backflow,

(7) a pressure gauge and a control valve and a control pump therefor for regulating the pressure of the pressure vessel, an

(8) Pressure reducing valve for preventing pressure of pressure vessel from exceeding p₂To help maintain a steady state continuous flow condition of the PEO module.

3. An apparatus for applying a synergistic effect to further maximize the production of osmotic energy and simultaneously cooperating with the PEO module of claim 1 to form a PEO energy generation system (PEO energy generation system), wherein the PEO energy generation system is installed on the ground to form a PEO surface system (PEO subsurface system), the synergistic effect of the PEO surface system comprising a synergistic forward osmosis module and a Nanofiltration (NF) or Ultrafiltration (UF) module, and a combined energy exchange and fluid recovery apparatus (PEO) module, wherein the PEO energy generation system is also installed underground adjacent to a bay or large salt lake area to form a PEO subsurface system (PEO subsurface system), the synergistic effect of the PEO subsurface system comprising using the gravity of seawater or salt lake water to provide driving fluid pressure and using heat generated by a power generation facility, and using a lifter to heat the PEO energy generation system by heating, Sparging, and dilution to dissipate the pressure stream released after power generation, while using the feed solution from the introduction of surface fresh water into the PEO underground system for hydroelectric power generation.

4. The PEO surface system of claim 3, wherein the PEO surface system is located adjacent to a bay or large saltwater lake and has a sufficient source of fresh water, and the energy production process comprises:

(1) using PEO module, using seawater or salt lake water as driving liquid, and passing through the energy generated in step (2) and the energy exchange in step (3), and using the selected beta value to provide flux Q₂And hydraulic pressure is p₂And providing river water or treated wastewater asFresh water feed to produce permeate flux Q₁For generating p₂(Q₁+Q₂) The amount of power that is to be supplied,

(2) using a combination of a synergistic FO module and NF or UF module units, wherein the synergistic FO module uses a formulated high concentration of a driving liquid to generate a hydraulic pressure p₃And driving liquid flow rate Q₃And a fresh water source is used as a feed liquid to generate a permeation flux Q₄For generating p in a cooperative FO module₃(Q₃+Q₄) Power, and after energy exchange by the following step (3), applying the remaining energy to NF or UF to re-concentrate and recover a high concentration draw solution,

(3) using energy exchange and fluid recovery means for converting p in step (2) above₃(Q₃+Q₄) Energy exchange into p required for driving the liquid in the step (1)₂Q₂And the energy required for recovering the driving liquid of high concentration in the above step (2), and

(4) application of Power Generation System, including Water turbine and Generator, located after PEO Module to transfer energy p₂(Q₁+Q₂) Into electrical energy.

5. The PEO surface system of claim 3, wherein the energy production process comprises, if no seawater or salt lake water is supplied as the drive fluid and no sufficient fresh water is supplied as the feed fluid:

(1) using a PEO module, the high concentration draw solution recovered using step (3) below, and a value of β selected to provide a flow rate Q₂And hydraulic pressure is p₂And applying the feed liquid recovered in the following step (5) to produce a permeate flux Q₁And Q₂Producing a flow Q of the mixed liquid₁+Q₂To form p₂(Q₁+Q₂) The amount of power of (a) is,

(2) applying one or more NF or UF modules in series to the Q generated in step (1)₁+Q₂The mixed liquid flow is subjected to reverse osmosis operation to generate p₂And Q₂A high concentration of a driving liquid of, and p₅And Q₁The filtrate of (1), wherein p₅＝γp₂γ is the membrane efficiency coefficient of the NF or UF module, representing the percentage after pressure loss across the semipermeable membrane of the NF or UF module,

(3) p produced by the above step (2) is applied₂Q₂The high-concentration driving liquid is used as the high-concentration driving liquid required by the step (1),

(4) p produced by the above step (2) is applied₅Q₁A filter liquid and a power generation system comprising a water turbine and a generator positioned after the NF or UF module to supply energy p₅Q₁Is converted into electrical energy, and

(5) and (3) recovering and applying the filtrate generated in the step (4) as the feed liquid required by the step (1).

6. The high-concentration draw solution of claim 4 and claim 5, wherein the solute required for the high-concentration draw solution is a soluble inorganic salt such as metal chloride, metal oxide, metal sulfate or nitrate, or a nanoparticle, wherein the more suitable inorganic salt is a chloride or sulfate of magnesium and calcium, or a combination thereof, wherein the nanoparticle comprises silica, titania, nano-silicon crystals, nano-titanium particles, nano-clay minerals, or a combination thereof, and wherein if a soluble inorganic salt solution is selected to formulate the high-concentration draw solution, the NF module can be selected as a reverse osmosis unit, if a nanoparticle is selected to formulate the high-concentration draw solution, wherein the nanoparticle is selected to be in a size range of 1nm to 1000nm, and wherein if a particle size less than 5nm is selected, and the NF module is used as a reverse osmosis operation unit, and when the particle size is larger than 5nm, the UF module is used as a reverse osmosis operation unit to concentrate high-concentration driving liquid and recover filtrate.

7. The PEO surface system of claim 3, wherein the energy exchange and fluid recovery device comprises:

the pressure exchanger is provided with a pressure sensor,

a low-pressure driving liquid input flow port of the pressure exchanger is used for inputting low-pressure driving liquid,

high-pressure drive liquid outlet of pressure exchanger for forming hydraulic pressure p₂Sum flow rate Q₂The driving liquid of (2) is added,

a high-pressure high-concentration fluid input flow port of the pressure exchanger is used for introducing fluid with higher energy content into the pressure exchanger,

a venturi ejector unit comprising a connection pipe to the pressure exchanger for bringing back a low-pressure high-concentration fluid,

a low pressure fluid input port of the venturi ejector for inputting a low pressure high concentration fluid from the pressure exchanger,

a high pressure high concentration fluid input port of a venturi ejector for ejecting a high pressure high concentration fluid, an

The mixing high pressure outflow port of the venturi ejector is used to form a mixed high pressure effluent for reconcentration by the NF or UF unit.

8. The PEO subterranean system of claim 3, wherein the system comprises:

(1) the depth of the ground or water bottom system is not less than p₂To accommodate all of the facilities of the associated PEO underground system,

(2) an intake and purification unit for above ground river water or treated wastewater for removing suspended solids to provide a feed liquid,

(3) an additional underground hydroelectric power plant utilizing p between the water purification unit of step (2) and the associated underground turbine/generator₂The head difference and the incoming feed liquid generate additional energy,

(4) one or more PEO modules using a selected depth p₂The created hydraulic head extraction flux is Q₂Using the seawater or the salt lake water as a driving liquid, and using the river water or the treated wastewater as described in the above item (2) as a feed liquid to produce a permeation flux Q₁To generate electricity through the subsequent turbine and generator,

(5) a power generation system comprising a hydro turbine and a generator for converting p of the above step (4)₂(Q₁+Q₂) Energy is converted into electric energy, an

(6) The lifter is used for releasing low-pressure fluid generated after power generation into high-pressure fluid in the sea or the lake.

9. The riser apparatus of claim 8, comprising:

(1) a vertical cylindrical stainless steel or titanium (titanium) shell, which includes a narrow vertical tubular fluid passageway in the center, resembling a venturi structure, for generating a fast-flowing stream of relatively low pressure water,

(2) a low pressure fluid injection port located in the middle of the narrow vertical tubular fluid passage for vertically injecting a low pressure fluid without a pump to be mixed with the rapidly flowing fluid,

(3) a high pressure fluid inlet port at the lower end of said vertical cylindrical structure, a fluid inlet chamber below the opening of said narrow vertical tubular fluid passageway for allowing automatic input of high pressure fluid to the bottom of the riser,

(4) an injection port for injecting air at the lower opening of the narrow vertical tubular fluid passage to generate a fast flow of lift gas to assist in the lift of the fluid in the lifter, and

(5) and a mixed solution outflow port, which is located at the upper end of the vertical cylindrical structure, for dissipating the formed mixed solution having a relatively low density and rapidly flowing upward.

Technical Field

The present invention relates to renewable energy technology, and more particularly to a method and apparatus for generating large renewable energy through Forward Osmosis (FO) and pressurized Osmosis (PEO for short), and related synergistic effects.

Background

According to IEA and Wikipedia reports, 2016 (International patent publication for information on the understanding of the United states of America and Japan) shows that Renewable energy accounts for 24.3% of the global power generation, 16.3% of which is derived from hydroelectric power and the remaining 8% of which is derived from other Renewable energy sources, such as wind, solar, geothermal, biomass and tidal energy (IEA: 2019, summary of Renewable information; Wikipedia: htps:// en. The use of renewable energy sources has many advantages, including large-scale availability, continuous replenishment via natural processes, prevention or reduction of potential environmental pollution (e.g., air pollution), and the high energy costs associated with non-renewable energy sources such as fossil fuels or nuclear energy sources. For this reason, the use of renewable energy sources is rapidly spreading and their share in the total energy consumption is increasing. The use of renewable energy sources is further driven by global warming considerations as well as other ecological and economic concerns. By 2019, more than two thirds of the installed capacity of newly added power generation in the world is reported to be from renewable energy sources, and accounts for 25.8% of the power generation amount in the world. The renewable energy market is expected to grow faster in the next decade and beyond. A goal has been set by many countries to achieve 100% renewable power generation.

The osmotic pressure power generation is a relatively novel renewable energy source, and if the osmotic pressure power generation can be popularized, the osmotic pressure power generation even can surpass the hydroelectric power generation to become a large-scale renewable energy source. However, it has not received attention for practical use so far. Although the history of human studies on osmotic phenomena dates back to 1748, norlet (Jean-Antoine Nollet) discovered this phenomenon. However, Van't Hoff was not developed in 1901 until approximately 150 years later and introduced the use of semi-permeable membranes for osmotic and quantitative osmotic pressures. In 1954, R.E.Pattern suggested that a large amount of available energy could be produced when rivers were mixed with seawater (Achilli, A.E.Childress: desalinization 261, 205-. According to the calculation of the Van't Hoff osmosis equation, when fresh water and seawater are contacted through a semi-permeable membrane, the hydraulic head generated by osmosis will greatly exceed the hydraulic head applied by any existing hydroelectric power plant in the world. In addition to the large-scale energy supply available as described above, osmotic energy sources have the advantage of being stable and controllable, unlike other renewable energy sources (e.g., wind, solar and tidal).

Although osmotic energy can become one of the major renewable energy sources, how to economically and efficiently extract and utilize osmotic energy from osmotic modules (osmotic modules) becomes one of the major problems. Until 1975, Sidney Loeb disclosed an efficient and practical method and apparatus for extracting energy from a permeation module for the first time in U.S. patent No. 3,906,250. S. the method developed by loeb is called "Pressure-Retarded osmoses (PRO for short)". The method is based on the following design: when two compartments separated by a semi-permeable membrane in a permeation module are respectively filled with solutions with different concentrations, osmotic pressure difference can be generated, so that the solvent of the liquid with lower concentration permeates to the side with higher concentration, and the pressure in the compartment with higher concentration is increased. In other words, PRO is a method for generating electricity by using a high concentration Solution (also called driving liquid) compartment of a Forward Osmosis (FO) module to Draw a solvent of a lower concentration Solution (also called Feed liquid) compartment to increase hydraulic pressure and volume of a mixed Solution. The main criterion is to keep the hydraulic pressure on the drive liquid side less than the osmotic pressure difference generated by the osmotic membrane in order to generate osmotic pressure and mixed solution volume. Loeb takes 1 cubic meter of seawater, 0.6 cubic meter of permeate and 10 atmospheres of osmotic pressure as examples, giving a theoretical energy output of 0.168 kilowatt-hour, or producing a 0.28 kilowatt-hour/cubic meter of permeate. The patent shows that the theoretical mean maximum equilibrium osmotic pressure in the drive fluid compartment is 15.63atm (i.e. 25atm x 1/(1+0.6) ═ 15.63atm), which is greater than the 10 atmospheres chosen above (i.e. PRO pressure), so that permeate can continue to occur and its energy can be derived for use. However, this patent does not address optimal PRO conditions, nor does it disclose how to increase PRO pressure to increase energy output.

In 1976, s.loeb further published two papers explaining the technical and economic relevance of PRO and evaluating the experimental results and energy costs of PRO (Loeb, S, j.membrane Science 1, 49-63 and 249-. His work goal was to determine whether PRO could produce energy economically. Assessment of mechanical efficiency and related considerations based on net power output and various feed and discharge conditionsAnd assumptions on the efficiency and cost units of the system components. These two papers conclude that PRO cost depends to a large extent on estimated mechanical efficiency. The mechanical efficiency is mainly influenced by the ratio of the flow pumped into the drive liquid compartment and the permeate flux permeating to the drive liquid compartment. Loeb suggests that the value of this ratio cannot be greater than 2. Another interesting result was from his testing, which found and verified that the permeate flux exhibited was essentially the same as the slope of the PRO pressure differential line (both at 0.0011 to 0.0013 m), regardless of the concentrations of the draw and feed liquids used³/m²Between the amount of day atm). Although the PRO methods and formulas developed in these two papers have made a significant contribution to the development of the use of osmotic energy, the assumed data may be far from the reality and thus may greatly influence the conclusions. For example, assuming generator and turbine efficiencies of 98% and 92%, respectively, this is typically only about 70% and 80% for most reported actual hydroelectric power plant data, respectively, and therefore, conclusions regarding power generation are overestimated about 60% (i.e., (98% x 92%)/(70% x 80%) /) to 1.61 based on these two assumptions only. Most other hypothesis data are also overestimated, which further affects the conclusions. Another problem is that the two papers do not evaluate the optimal pressure of PRO under different osmotic pressure conditions. This may lead to unbalanced and unstable test modules due to the slow flow of permeate through the semi-permeable membrane, combined with the fact that the drive fluid compartment of the osmosis module is narrow and does not maintain a uniform mixed liquor concentration. If no means for controlling the equilibrium and stability between the draw solution and the feed solution is provided during the permeation operation, a non-equilibrium and unstable mixture may be produced based on the brownian effect and the bernoulli principle, which will be discussed in the later part of this document.

An improvement in PRO design is disclosed in U.S. patent No. 4,193,267 issued to s.loeb in 1980. Unlike the PRO design of us patent No. 3,906,250, this patent applies an additional equivalent PRO pressure to the flushing fluid (flushing solution) flowing from the feed fluid compartment in addition to the PRO pressure applied to the drive fluid compartment to combine with the mixed liquor flowing from the drive fluid compartment, and recovers the drive fluid for reuse via a thermal concentration process, while the remaining and pressurized feed fluid is separated from the mixed liquor for power generation. The improved patented method states that the power generation output can be increased. In this invention, additional energy is required compared to previous PRO designs due to the additional pressure required to re-concentrate and pump the rinse. However, no quantitative assessment of net energy output is given in this invention. Thus, the advantages of using the improved PRO method are not known. Also, the optimum hydraulic pressure required for PRO is not discussed in this invention. Nor does it discuss how to increase the hydraulic pressure to increase the amount of electricity generation.

In 1990, S.Loeb, et al published a paper on J.of Membrane Science 51, 323-: (1) a continuous flow above ground PRO power plant, (2) a continuous flow below ground PRO power plant, and (3) an alternating flow above ground PRO power plant. Fresh water and 3.5% NaCl brine were used as feed and driving fluids for osmotic pressure power generation. The results of the calculations of the total power generation mechanical efficiency (including the osmotic and turbine/generator combinations) for the three PRO plants described above were 28%, 59% and 74% for PRO plants (1), (2) and (3), respectively. The article suggests that only PRO power plants of types (2) and (3) operate effectively, but that building a PRO power plant requires a significant capital investment. From a search of an assessment of the paper's assumptions and conclusions, we again found that most of the assumed data was quite optimistic, possibly leading to an overestimation of efficiency. The paper also does not use the optimal hydraulic pressure required for PRO for calculation. All of the above may affect the calculation result.

Loeb, 2002, published in the Desalination 143, 115-122, assessed the economic feasibility of generating electricity by osmotic pressure by contacting medium scale river water flow (300 million cubic meters per day) with seawater. The ratio of seawater drive flux to permeate flux (permate flux) used in this paper was chosen to be 5 to 2. The PRO hydraulic pressure selected for evaluation was 12 atmospheres. This paper also introduced a pressure exchange method (pressure exchange method) for pressure exchange to simplify the design and eliminate a large amount of power consumption. His calculations show that even with a K value of 10d/m, the cost of power generation is not economical, by optimistic assumptions on mechanical efficiency and the K term (K-term, defined as the resistance to solute diffusion in membrane filtration). However, as river flow increases, it becomes more economical, as exemplified by the mississippi river (15 billionth of cubic meters per day of flow). Therefore, the paper considers the production of renewable osmotic energy on a large scale to be worth further investigation.

Based on the PRO method, Stakraft, Norway, developed the first penetrating power plants in the world in Wauter, Norway in 2009 (see Skramesto, O.S., S.E.Skihagen, W.K.Nielsen: https:// www.statkraft.com/waterpower xvi; and Wikipedia: https:// en.wikipedia.org/wiki/Stakraft _ ecological _ power _ promoter _ in _ Hurum). The power plant was selected to use seawater at a drive flow of 20l/sec, fresh water at a feed flow of 10l/sec, and a PRO pressure of 11 to 14 bars. The design power output of the PRO power plant is expected to be 10kw, but the actual power is 2-4kw as a result of the test, and the power density of the membrane is about 3w/m². Although this technique has been proven "feasible" by Statkraft, unfortunately, the plant has been shut down in 2013 due to economic considerations (Patel, s.: Power Magazine, 2014, month 2 and day 28). It is reported that for a favorable proc power plant, the power density of the membrane should be at least 4-6w/m²Within the range of (1).

Achilli, et al (see Achilli, A., T.Y. Cath, A.E. Children: J of Membrane Science 343, 42-52) developed a PRO model in 2009 to predict permeate flux and power density for specific experimental conditions. The experiment was tested using a small test model of the PRO system. The test parameters included the selection of modified Cellulose Triacetate (CTA) FO membranes, and the selection of various NaCl solution concentrations for testing, including feed solution concentrations of 0, 2.5 and 5g/l, draw solution concentrations of 35 and 60g/l, and hydraulic pressure differences of 0, 310, 650 and 970 kPa. Both the experimental results and the derived PRO mathematical model confirm that the power density reaches a maximum when the hydraulic pressure difference is equal to half the osmotic pressure difference. Under a pressure experiment of 970kPa (or 9.57atm), the permeation flux achieved for a concentration of 35g/l NaCl draw solution is 1.8x10^-6To 2.8x10^-6m/s, power density up to 2.8w/m². While the permeate flux achieved for a concentration of 60g/l NaCl draw-solution was 3.6X10^-6To 5.2x10^-6m/s, power density up to 5.1w/m². The experimental results also show that the amount of Internal Concentration Polarization (ICP) increases with increasing feed solution concentration, while the amount of External Concentration Polarization (ECP) increases with increasing drive solution concentration. It is reported that the power density is greatly reduced by increased ICP and the degree of reverse salt dilution is reduced due to the use of asymmetric membranes. ECP was also found to show a relatively small effect in reducing the osmotic driving force.

Methods of extracting energy from fresh water/seawater systems using osmotic pressure in addition to the PRO method are also disclosed in various patents. U.S. patent No. 3,978,344 discloses a method of generating electricity by using a nozzle to spray a mixed solution of a driving liquid and a permeate from a permeate container to propel a water wheel or a turbine. However, in this method, the energy required to pump seawater into the permeation vessel is not considered. The feasibility of applying this method is not possible because the energy required to pump seawater into the permeation vessel is more than the vessel can be designed to produce, as will be discussed further later in this invention.

Three U.S. patent nos. 6,313,545; 6,559,554, respectively; 7,329,962 discloses a method and device for generating electricity by osmosis without using semipermeable membrane, which is called as "hydraulic generator". The method states that the osmotic pressure can be released by mixing relatively low salinity water (e.g., fresh water) and relatively high salinity water (e.g., seawater) in the bottom of a vertical tubular housing, thereby producing osmotic energy. The process also states that the lower salinity water produced in this vertical tubular housing can cause "upwash" kinetic energy of the mixed liquor due to its lower density than seawater. The process further states that the above effect is more pronounced when the ratio of brine to fresh water is greater than 8: 1, or more preferably 30: 1, and most preferably 43: 1 or higher. However, this discussion may have theory of osmosis, i.e., the generation of osmotic forces requires the presence of a semi-permeable membrane to generate an osmotic pressure differential via brownian motion phenomena. Mixing only two different salinity waters at the bottom of the tube does not allow for the creation of osmotic pressure. The energy gained by the "hydraulic generator" proposed by these patents may come primarily from the hydraulic head of the low brine in the tube. The effect of the "upwash" in the tubular housing caused by the difference in water density will be very small, in which case the ratio of brine to fresh water as required above is very high.

U.S. patent No. 8,099,958 also relates to a method of generating osmotic energy by contacting two fluids, a lower osmotic potential liquid and a higher osmotic potential solution, in a semi-permeable membrane device. The device utilizes the solution that produces the higher osmotic potential to drive a turbine generator for power generation. The diluted solution is then concentrated by pressure to the original solution concentration level for recovery and re-injection into the semipermeable membrane unit. The claimed re-concentration process is a thermal or membrane separation process involving evaporation, distillation, wind energy crystallization, solar energy, geothermal energy or energy from fuel combustion and/or excess heat from power plants and other industrial processes. The system discussed in this patent was studied and found not to take into account the energy (or pressure) required to inject the recovery solution into the semipermeable membrane device. The present invention may result in negative power generation if the energy required to inject the recovery solution is higher than the energy required for re-concentration.

Us patent No. 8,545,701 discloses a method called "Induced Sympathologic Osmosis (ISO)" which is based on maximizing the power generation by a series of osmotic cells. Each of the permeate cells forms a closed hydraulic circuit having a water pumping means, a power generating turbine means and a common semi-permeable membrane. The driving liquid is selected from chlorides of sodium, magnesium and calcium. In the ISO process, a series of permeation cell units are connected in series to gradually reduce the concentration of the draw solution to generate energy. In each step of the permeation cell unit, the dilution ratio of the draw solution used is in the range of 2 to 5. However, this patent does not disclose a specific re-concentration method and the energy required for re-concentration. In this invention, too, there is no consideration nor suggestion on how to optimize the pressure required for injecting a higher concentration of liquid into the drive liquid compartment. The ISO process, which selects multiple permeate cells in series, requires a separate turbine generator system for each cell. However, if all of the permeate cells in series can be combined into one system or a parallel system and only one set of turbine generator units is applied, more energy should be generated.

Us patent No. 8,568,588 discloses a plant for power generation and desalination that employs a series of forward osmosis and reverse osmosis methods by being based on an arrangement of three brines at different salt concentrations. Basically, the invention also adopts a PRO power generation scheme, but no optimization method for evaluating net power generation and PRO is available.

U.S. patent No. 9,023,210 provides a system for recovering the hydraulic energy of the permeate stream to maximize the efficiency of the process. The process shares the rotational energy generated by the turbine shaft to directly pump the feed liquid, drive liquid, recycle fluid, and rotate the generator. However, this invention does not disclose the evaluation of energy saving or efficiency improvement. It should be found by evaluation that PRO design by Loeb will be more energy efficient. Furthermore, since each of the pumps described above is designed to function differently, and requires mechanical modifications to be used, the proposed universal shaft design may be inefficient, which may lose more energy than the conventional pressure exchanger used with PRO.

From the above discussion, it is clear that the PRO system is still by far the only best method available for extracting energy from the osmosis module. Methods such as the "hydraulic generator" described above, ISO, or any method that does not consider the energy required to inject the concentrated draw solution may not be feasible or cost effective to produce large scale renewable energy sources from osmotic engines.

In many of the above publications and prior related patents, it is well documented that Large-Scale Renewable Energy (LSRE) can be generated using osmotic pressure. Related patents have proposed methods and apparatus to obtain permeate energy from a permeate module for use in power generation. However, in the past half century, most of the proposed methods and devices have either not been cost effective or have not been feasible. Especially when using a combination of fresh water/sea water for power generation, the energy required for pumping into the osmosis module may consume more energy than the generated electricity without a reasonable design. Therefore, a method of spraying a mixed solution of salt water and fresh water from the osmosis module using a nozzle to propel a waterwheel or turbine to generate electricity as described above may not be feasible. In another example, the "hydraulic generator" disclosed in the prior patent is contrary to the brownian principle of motion, and thus it is obviously not feasible to use a semi-permeable membrane. Several osmotic energy generation methods discussed in the prior patents have somewhat ignored the energy required to inject the draw solution into the osmotic module. Some patents suggest the use of high salinity liquids as the drive liquid rather than seawater. If the energy required to inject such high salt drive fluid into the osmotic module or the energy required to re-concentrate is higher than the energy produced by the osmotic power generation system, a negative energy output will be produced. Negative energy output conditions may also occur for certain positive osmosis processes by recycling FO modules in series at high dilution ratios (such as the ISO process described above) or by certain types of high concentration reflux solutions.

To date, the s.loeb inventive damping infiltration (PRO) system is still the best method available to date in all of the discussed background. The process can be applied by extracting energy from the osmosis module. However, both the low mechanical efficiency of the overall PRO device and the low power density of the membrane affect the application of the PRO process. Loeb concluded that PRO mechanical efficiency is primarily affected by the ratio of flow pumped into the drive liquid compartment to permeate flux. Loeb suggests that the value of this ratio cannot be greater than 2 to improve mechanical efficiency. It is also recommended that the membrane power density for PRO to be economically efficient should be at least 4-6w/m²Within the range of (1). To date, the first PRO penetration power plant only achieved about 3w/m²The membrane power density of (a). In addition to low mechanical efficiency and low membrane power density, which affect osmotic force output, PRO systems may also involve other problems, such as: (1) only a flow equal to the pressurized permeate flux is used for power generation, thereby greatly reducing the net power output. Even with the optimal PRO hydraulic pressure, the net power produced is greatly reduced; (2) the low flow ratio of input draw solution to selected permeate flux (i.e., ≦ 2) results in the inability to use the optimum or highest permeate pressure differential, and therefore, greatly reduces the amount of power generated. (3) In PRO systems operating for long periodsUnbalanced and unstable pressure or flow conditions may occur, especially in the case of non-uniform concentrations in the drive liquid compartment, which may lead to system failure. Currently, no methods and means for preventing this situation are provided by PRO infiltration modules.

Summary of the invention and detailed description

It is an object of the present invention to provide a method and apparatus for improving PRO to maximize the osmotic power generation of conventional PRO modules by FO process technology and with innovative methods of PEO modules. Further exploitation of the synergistic effect maximizes power generation, especially when using seawater-river water or any other draw liquid-feed liquid combination for osmotic power generation. The basic principles, methods and apparatus, problems and solutions presented, and exemplary cases of specific embodiments are described below.

1. Basic principle of osmotic power generation and method for maintaining steady state equilibrium operation

Traditionally, the primary method of energy generation by osmotic pressure has been based on FO operation. When the FO module is divided into two compartments by a semi-permeable membrane, one osmotic pressure is pi_DAnother osmotic pressure of pi_FThe feed liquid compartment of (a) forms a difference in osmotic pressure Δ pi as shown in figure 2. Pressure difference Δ π in the FO module under theoretical maximum osmotic pressure static equilibrium conditions_oCan be calculated as:

Δπ_o＝π_D-π_F……………………………………………………………(1)

wherein pi_DAnd pi_FCan be estimated by the osmotic pressure formula of Van't Hoff:

π＝RT ∑M_i……………………………………………………………………(2)

where π is the osmotic pressure, R is the ideal gas constant, T is the absolute temperature, ∑ M_iIs the sum of the molar concentrations of all i-type solutes in the osmotic system. Table 1 gives the theoretical maximum osmotic pressure difference Δ π between fresh water and typical seawater_oExamples of (2). And also provides temperature vs. maxOsmotic pressure difference Δ π_oThe influence of (c). The table shows the temperature of seawater as increasing from 10 ℃ to 35 ℃, where Δ π_oThe difference is 22.58m, which is very obvious.

TABLE 1 examples of osmotic pressure differences between fresh water and seawater

In the physical phenomenon, osmotic pressure occurs when the temperature is higher than the absolute temperature and the particles in all solutions produce continuous and irregular brownian motion, and when two solutions using the same solvent but different solute concentrations are separated into two osmotic module compartments by a semipermeable membrane, an osmotic pressure difference is formed. For example, in the case of power generation from river water (feed liquid) and sea water (draw liquid) in an osmosis module, a higher osmotic pressure is created in the draw liquid compartment, as the brownian motion of more water molecule particles in the feed liquid is subject to less solute dried and there is a higher chance that the draw liquid compartment water pressure will be increased by the semi-permeable membrane entering the draw liquid compartment with higher solute dried . The semi-permeable membrane used in the brownian motion example has a pore size that theoretically prevents the permeation of the solute particles, but is effective without affecting the permeation of water molecule particles. As shown in table 1, the osmotic pressure in the drive liquid compartment was built up at a hydrohead pressure of 25 ℃, with an osmotic pressure of 269.15m, which is high enough to be recovered for power generation. For example, the largest hydroelectric power plant in the world that has been built to date is the three gorges power plant in the Yangtze river, which has a maximum head of only 113m, less than half the osmotic pressure 269.15m of seawater as shown above. With respect to selection of the semi-permeable membrane, it must be certain that most solute salt species can be screened out but that it is permeable to water molecules, so that more water molecules can diffuse through the membrane from the feed liquid side to the drive liquid side compartment. This phenomenon results in the drive liquid compartment gradually changing into a pressure vessel until the theoretical maximum pressure difference at static equilibrium condition Δ π is reached_o. The pressure in the drive liquid compartment is so great that it would be more efficient than the three gorges for power generation if it could be efficiently recovered for power generationThe hydraulic pressure of the plant is much greater. As described above, the PRO method may be the only feasible method to capture the osmotic pressure for power generation in actual practice so far. The formation of the osmotic pressure described above would not occur without the semi-permeable membrane. This can also be used to explain why methods such as the aforementioned "hydraulic generator" cannot be used to generate electricity because they cannot generate a pressure difference by the brownian motion phenomenon without a semi-permeable membrane.

As shown in fig. 2, in order to continuously obtain osmotic pressure from the osmotic module for application, the osmotic module should have a hydraulic pressure p₂And flow rate Q₂Is continuously fed into the drive liquid compartment. At the same time, the feed flow Q also needs to be at a pressure p₁Make up into the feed liquid compartment. If the solution in the feed liquid compartment is clean fresh water, then pi_FClose to zero, thus p as shown in FIG. 2₁The hydraulic pressure is close to zero. However, if it is desired to maintain the flushing liquid flow Q' to avoid accumulation of salt from the drive liquid compartment in the feed liquid compartment, a certain p is required₁The hydraulic pressure, the required hydraulic head is mainly determined by the flow rate of the produced Q'. When the osmotic pressure difference is generated in the osmosis module, a unit osmotic flux J (flow rate per unit membrane area) is formed, and at this time, an osmotic flux Q as shown in fig. 2 can be calculated by the following formula₁：

Q₁＝JA………………………………………………………………………(3)

Where a is the total area of the semi-permeable membranes in the permeate module. In FO operation, the J value is primarily affected by membrane characteristics, the osmotic pressure differential, and the effective maximum osmotic pressure in the osmotic module. As shown in FIG. 2, Q₁Also the difference between Q and Q', i.e. Q₁＝Q-Q’。

Theoretically, if p is selected₂Is less than the effective Δ π_oAnd when the input and output flow rates of the drive liquid compartment are not in steady state equilibrium conditions, then the pressure in the drive liquid compartment may become progressively higher or smaller than p₂. If the pressure in the drive liquid compartment increases gradually above a selected p₂Then Q is₂The input will be forced to stopAnd (4) stopping. If the pressure in the drive liquid compartment is gradually reduced, the design liquid head required for subsequent power generation will also fail. Thus, the pressure in the drive liquid compartment and Q₁+Q₂The steady balance of the flow capacity of the mixed liquid is important for successfully realizing osmotic power generation. So far, there is no discussion in the prior art literature of how to control the steady state equilibrium in the drive liquid compartment.

Under dynamic conditions, when the compositions and concentrations of the driving liquid and the feeding liquid are determined, the delta pi_oTheoretical value can be represented by Q₁And Q₂And (6) estimating. Due to a number of factors affecting the pressure loss of the driving liquid compartment, e.g. concentration polarization and diffusion friction losses associated with membrane properties, p₂And Q₁Variation of (2) and Q₂And Q₁The ratio of the two changes is such that Δ π_oThe values are also difficult to control. This phenomenon will be discussed further below. To simplify the engineering design, the membrane efficiency coefficient α was chosen in this document to represent the percentage efficiency after total pressure loss across the membrane. According to the membrane efficiency coefficient alpha, the maximum effective osmotic pressure difference delta pi_eThe following can be calculated:

Δπ_e＝αΔπ_o……………………………………………………………(4)

if FO is used, the above alpha value can typically be in the range of 85 to 97% and mostly in the range of 90 to 95%, depending on the general membrane properties currently produced. When Q is₂And Q₁After being selected, based on the above equation, Δ π can be calculated_e. In actual FO operation, Q is generally selected according to the practical range₁Or Q₂. Due to effective osmotic pressure difference of Q₁And Q₂The effect of the size ratio, the dilution factor β is chosen in this document to simplify the calculation of the effective osmotic pressure difference, as follows:

β＝Q₂/(Q₁+Q₂)…………………………………………………………(5)

the value of the above formula beta may range from 0 to 1. If beta is 0.9 means that the flow rate injected into the drive liquid compartment is diluted to 90% of the original,i.e., the effective osmotic pressure difference that the draw solution can create is diluted (or reduced) by 10%. When beta equals 1, it is theoretically meant that the flow pumped into the driving-liquid compartment is undiluted, so that the effective osmotic pressure difference in the driving-liquid compartment equals the maximum effective osmotic pressure difference Δ π_e. When β is equal to 0, it means that there is no driving liquid flow rate Q₂Is pumped into the osmosis module, also meaning p₂Is 0, or means p₂Less than the osmotic pressure difference in the drive liquid compartment, and thus the drive liquid flow rate Q₂And cannot be pumped into the osmotic module. The application of the dilution factor β can simply indicate any effective osmotic pressure difference in the osmotic module under dynamic conditions, as shown in equation (6) below:

Δπ_β＝βΔπ_e＝αβΔπ_o……………………………………………………(6)

an example of the effective osmotic pressure difference as a function of α and β is shown in FIG. 7. Therefore, Q can be determined by selecting different beta values in engineering design₂According to the above equation (5), Q₁Also move along with it. To maximize the design osmotic power output, the PEO module is selected to have a beta value in the range of 0.85 to 0.95, which is much higher than the beta value of a typical PRO module, as will be discussed later.

For the design of osmotic systems for power generation, as long as p₂Less than corresponding Δ π_βAnd Q₁If greater than zero, then Q can be selected at any value₂And p₂. However, to obtain maximum power output from the osmosis module, as shown in the background discussed above, the optimum p₂The value should be chosen to be each corresponding Δ π_β1/2 of (1). At the optimum p₂Under the conditions, Q can be estimated by the following equation₁(refer to fig. 4A and 4B):

Q₁)_{optimum conditions}＝1/2J_βA＝1/2(Δπ_β·tanθ)A＝1/2Δπ_β(J_e/Δπ_e)A………(7)

Can be based on the film properties and the desired Q₁The data were obtained by engineering to select the membrane area "A" value. Merging equations (6)And (7), Q can also be found₁)_{Optimum conditions}＝1/2βJ_eA。

As will be discussed further in the following section, Δ π_βThe higher or higher β, the higher the power output from the osmosis module can be generated. When selecting Δ π for the permeation module_βAt steady state equilibrium conditions, the potential power W generated by the permeation module can be estimated by the following equation:

W＝p₂(Q₁+Q₂)……………………………………………………………(8)

when p is optimized₂The values are selected to correspond to Δ π_β1/2, the maximum power W that the infiltration module can produce_maxAs follows:

W_max＝1/2Δπ_β(Q₁+Q₂)……………………………………………………(9)

relative to hydroelectric power generation in the above formula, 1/2 delta pi_βEquivalent to head height, (Q)₁+Q₂) Corresponding to the total water flow, when the water head height is in m, the flow rate is in l/sec, and the gravity acceleration g is 9.81m/sec²Then the theoretical maximum power W is generated_maxCalculated as watt-head height mx flow l/sec x 9.81m/sec²。

2. Comparison of Power Generation of osmosis modules between pressure boost osmosis (PEO) and damped osmosis (PRO)

As mentioned above, the energy producible by the drive liquid compartment of the osmosis module is influenced by p₂And the influence of beta selection. As described above, conventional PRO power generation systems typically select Q₂/Q₁The ratio of (beta) is less than or equal to 2 (i.e. equivalent to beta is less than or equal to 0.667), and p₂Not necessarily at 1/2 Δ π as described above_β. In order to be able to increase the osmotic power generation, conventional PRO power generation systems can be further modified. A typical conventional PRO power generation system is shown in fig. 3A. In FO module 3101, feed liquid (e.g., fresh water) 3105 having a flow rate Q is pumped into feed liquid compartment 3103 by pump 3106 and has a flow rate Q₂Is fed into the drive liquid compartment 3102. Tong (Chinese character of 'tong')Overpressure exchanger 3111 and hydraulic system with hydraulic pressure p₂Pump 3110 pumps it into the drive liquid compartment 3102. Formation of flux Q through the FO semi-permeable membrane 3104₁The permeate flux 3107. The driving liquor 3109 is extracted from the driving liquor cleaning system (not shown in the figure) and the washing liquor output 3108 is discharged to a drain or recycled to a storage tank (not shown) for use as the feed liquor 3105. In this PRO design, the permeate flux Q can be obtained₁+ driving liquid flow rate Q₂To pressurize the mixed liquor 3113 to generate energy. To provide pressure for pumping the driving liquid 3112, pressurized solution 3114 is separated from pressurized mixed liquid 3113 for pressure exchange. A pump 3116 may be required to compensate for any energy loss in the pressure exchange operation. The remaining pressurized solution 3115 is used to generate electricity. In PRO designs, the flow rate of pressurized solution 3115 for power generation is typically selected to be equal to Q₁The flux of (c). The pressurized solution 3115 is used to rotate the turbine 3118 and then electricity is generated using the generator 3119. The pressure-released release stream 3117 is mixed 3120 with the effluent for power generation for discharge as a mixed liquor. In this PRO design, p₂And beta is most critical for maximum power output. As previously mentioned, s.loeb selects β for PRO design based on Q₂/Q₁Not more than 2, namely not more than 0.667. After the alpha data is experimentally determined and the beta value is selected, Δ π can be calculated according to equation (6)_β. To obtain the corresponding Δ π_βW of (2)_maxHydraulic pressure p₂Should be selected based on Δ π_β1/2 of (1). However, the existing PRO-related documents show that the hydraulic pressure p is applied before the development of the Statkraft osmosis plant₂Is selected to be mostly higher than Δ π_βValue 1/2.

A large number of tests show that the unit permeation flux J and delta pi_βProportional ratio, e.g. J in FIG. 4B_β＝Δπ_βtan θ. When beta is equal to 1, delta pi_βEqual to the maximum effective osmotic pressure difference DeltaPi_eAs shown in equation (6) and fig. 4A and 4B. When plotted as curve 401 (i.e. drive liquid input pressure p)₂Curve with unit permeate flux J), previous test results show a nearly linear relationship with a slope tan θ, where tan θ is J_e/Δπ_e，J_eIs corresponding to Δ π_eMaximum unit permeate flux. Curve 402 when β is less than 1, e.g., when β is 0.667 (i.e., Δ π_0.667Is fed with drive liquid pressure p₂And 0.667J_eA curve of the relationship between the unit permeation fluxes J) of the two phases, the curve also approaches a straight line having the same slope tan θ, as shown in fig. 4A. Experiments have shown that the J vs p can be determined by using the same permeate module (or more specifically, the same semipermeable membrane having the same surface area) for different values of β₂Will have a similar slope tan θ J_e/Δπ_e. J vs p shown in FIG. 4A₂All curves of (b) are parallel straight lines, such as curve 403 at β ═ 0.334 or curve 406 at β ═ 0.9. These curves also show that higher p is selected₂Will produce a higher permeate flux Q₁Wherein Q is₁JA, as shown in equation (3). It is also shown from equation (6) that the higher the beta chosen, the higher Δ π will be obtained_βAnd (4) pressure. Based on equation (5), a higher value of β also means a higher Q₂/Q₁By contrast, based on FIG. 4A, higher p is meant₂. These relationships can also be seen by comparing the corresponding data of 404 with 405, 407 with 408 in fig. 4A. I.e. when the hydraulic pressure p is applied₂An increase in value will eventually result in all Q₁，Q₂And Δ π_βThe value is increased. Based on equation (9), when all Q's are increased simultaneously₁，Q₂And Δ π_βAt value, its maximum power W via a combined effect_maxThe output will be greatly improved. Thus, a PEO module as described above can greatly increase power production as compared to a PRO module using the same type of semi-permeable membrane and the same area.

The importance of the PEO concept in osmotic power generation can be further evaluated in the following examples. The maximum osmotic pressure difference delta pi between the fresh water and the seawater_oAs an example of 26atm, the same type and the same semi-permeable membrane area (i.e., the same Je/Δ pi) in the permeation module_eSlope), and assuming that the film efficiency α is 95% the same, the electrical power that can be generated between PEO and PRO is compared as follows: (1) maximum electrical power that can be generated in a PRO module:

as shown in fig. 4A, it is assumed that β is selected to be 0.667 (the highest β value that s.loeb allows for PRO use) for evaluation. Under the above conditions, the effective osmotic pressure difference, i.e. Δ π_0.667＝αβΔπ_o0.95 × 0.667 × 26atm ═ 16.47 atm. To obtain W_maxSelecting p₂16.47atm/2 8.24 atm. In this evaluation, the permeate flux was selected to be Q₁10l/sec (this is the Statkraft penetration plant design data described above). The corresponding Q when β is 0.667 can be calculated according to equation (5), i.e., Q₂20 l/sec. From these data, equation (9) can be applied to calculate the theoretical W generated by the PRO infiltration module_maxI.e. W_max＝8.24atm x 10.33m x(10l/sec+20l/sec)x 9.81m/sec²＝25kw。

(2) Maximum electrical power that can be generated in the PEO module:

using the same assumptions as above, but for Δ π in the PEO module_βFor example, β ═ 0.95 can be selected for the comparison. Under this condition,. DELTA.pi_0.95＝αβΔπ_o0.95x0.95x26 atm ═ 23.47 atm. To obtain W_maxSelecting p of PEO₂23.47atm/2 11.74 atm. J value (i.e., 0.334J) that can be based on the upper PRO from FIG. 4A_e) Relationship to the same tan θ the J value (i.e., (0.95/2) J for the effective osmotic pressure differential for the present PEO was estimated_e) Thus Q of PEO₁＝(0.95/2)J_eAnd/0.334 Je x10 l/sec is 14.22 l/sec. Based on equation (5), Q₂(0.95 × 14.22)/(1-0.95) ═ 270.18 l/sec. Theory W_max＝11.74atm x 10.33x(14.22l/sec+270.18l/sec)x 9.81m/sec²＝338.35kw。

(3) W generated between PRO and PEO modules_maxComparison of (1):

the above evaluation proves that when the hydraulic pressure p is increased₂The theoretical maximum power production of the osmosis module can be greatly increased when, or when higher values of beta are selected by the PEO process. According to the PRO design parameters used by the Staktraft osmosis power plant, the theoretical W generated in its osmosis module as described above_maxOnly 25kw, but using the same operating parameters for PEO the theoretical W produced in the permeation module_maxIs greatly increased to 33835kw, about 13.5 times the power! If the PEO concept is used in a Statkraft penetration power plant, it is possible to turn the originally unprofitable power plant into a considerable profit.

(4) Design of PEO modules:

in PEO modules, the solvent in the driving and feed solutions may be selected from stable soluble substances (e.g., inorganic dissolved salts) or suspended particles (e.g., nano-or micro-particles typically less than 1 μm). If river water and/or treated wastewater is used with seawater for power generation, their sources are relatively stable and can be provided for free. When determining the type and available amount (Q) of the driving and feeding liquid₂And Q) and selecting a semipermeable membrane module, J can be determined experimentally_eAnd Δ π_eAs shown in fig. 4A and 4B. Delta pi_oThe membrane efficiency α can then be estimated experimentally or obtained from the membrane supplier, calculated from equations (1) and (2) above. Based on these data, β can be selected for Δ π_βAnd (4) calculating. The PEO process requires the selection of as high a beta as possible to enhance power generation. A suitable range for the value of β is from 0.85 to 0.95, more preferably from 0.9 to 0.95. Equations (1) to (4) for Δ π_eAnd (4) calculating. Based on selected beta and delta pi_eThe effective osmotic pressure difference Δ π can be obtained by equation (6)_β. Based on selected Q₂And the selected beta, and the membrane area and the permeation flux Q can be calculated through the membrane unit permeation flux data obtained by a membrane supplier or experiments₁. The theoretical maximum power W of the PEO module can then be estimated_max. The steps for PEO module design are described in further detail below and include:

(a) a PEO module is used as a Forward Osmosis (FO) module and is controlled in a steady state and continuous flow state to input a driving liquid (draw solution) and a feed liquid (feed solution) to generate an osmotic flux (permeate flux),

(b) the PEO module is selected to have a dilution factor β in the range of 0.85 to 0.95, more preferably in the range of 0.9 to 0.95, where β ═ Q₂/(Q₁+Q₂)，Q₁Is the osmotic flux, Q₂Is fed with a driving liquid streamThe amount of the compound (A) is,

(c) selecting Q according to the practical range₁Or Q₂When Q is selected₁Then, another Q can be estimated according to the formula listed in the above step (2)₂And vice versa,

(d) at a fluid pressure p₂The draw solution was introduced into the draw solution compartment of the PEO module, where p₂＝1/2αβΔπ_oAnd α is the membrane efficiency coefficient of the PEO module, representing the percentage of pressure loss across the semi-permeable membrane of the PEO module, Δ π_oIs the theoretical maximum osmotic pressure differential for the PEO module,

(e) designing the total membrane area A, wherein A ═ Q₁/(1/2βJ_e)，J_eIs at Δ π_eUnit permeation flux of the membrane, J_eCan be obtained by data provided by the film supplier or by experiments, while Δ π_eRepresenting the maximum effective osmotic pressure difference Δ π_e＝αΔπ_o，

(f) The energy produced by the PEO module has a theoretical maximum power output of W_maxWherein W is_max＝p₂(Q₁+Q₂)。

Comparison of PEO Power Generation System and PRO Power Generation System

PRO power generation system As shown in FIG. 3A, it is necessary to provide a stable and continuous flow rate Q of the drive liquid₂And pressure p₂The conventional typical design requires that a portion of the pressurized mixed solution (shown in 3113A) exiting the osmosis module be applied to the drive liquid pressurization using a pressure exchanger (shown in 3111 in fig. 3A). Thus, the available flow rate for power generation is generally selected to be equal to or less than the permeate flux Q₁(as shown in 3115 in fig. 3A). W with the Staktraft osmosis module described above_maxFor example, the portion of the PRO power generation system available for power generation can be greatly reduced below W_max. If the flow for power generation selects Q₁The theoretical generating capacity of the PRO generating system is p₂(Q₁+Q₂) Is reduced to p₂Q₁. Another potential problem with PRO power generation systems is controlling steady-state continuous flow in the drive fluid compartment. When the pressure in the drive liquid compartment exceeds a selected p₂When it is in value, Q₂The flow will be forced to stop and the pressure will be lower than the selected p₂Value of Q₁And also relatively decreases, thereby causing instability or failure of the entire power generation system.

To address the large energy losses noted above through the PRO pressure exchange operation, a separate pressure stream is proposed in a PEO power generation system that does not consume the power produced by the permeation module. In a PEO power generation system, two types of natural pressure flows are proposed as a source of pressure for p2 through a synergistic effect, as discussed below.

The present invention provides two types of PEO power generation systems, or PEO energy generation systems: PEO surface systems (as shown in figure 3C) and PEO subsurface systems. The PEO subsurface system is further divided into a PEO water bottom system (shown in FIG. 3B) and a PEO subsurface system (shown in FIG. 3D). Both the PEO surface system and the PEO subsurface system of the present invention can utilize all of the pressurized mixed solution flow (i.e., Q) generated in the PEO drive-fluid compartment₁+Q₂) To generate electricity. PRO power generation systems generally can only utilize Q₁To generate electricity.

As shown in FIG. 3C, the PEO surface system of the present invention can locate the PEO module 3301 on the surface to produce a pressurized mixed solution output stream 3311 (flow rate Q) through the drive liquid compartment 3302₁+Q₂) All for generating electricity. Source of inlet flow 3326 (with flow rate Q) to the drive liquid compartment₂And pressure p₂) May be from natural sources 3323 of seawater or high strength brine (e.g., from a sufficiently high salt lake supply). These driving liquids 3323 of natural origin can be pumped by a pump 3324 and regulated by a pressure exchanger 3325 to the designed pressure p₂. Pressurized stream 3354 in pressure exchanger 3325 is provided by an additional energy generation unit. This additional energy generation unit consists of a synergistic FO module 3330, a nanofiltration unit (NF) or ultrafiltration Unit (UF)3329, and an energy exchange and fluid recovery unit 3349. The energy exchange and fluid recovery device 3349 will be discussed later in this document in fig. 6B. Inlet flow 3326 to drive fluid compartment 3302 is regulated by control valve 3327 to design flow Q of inlet flow 3326₂. Drive liquid compartment 3302 is provided with a checkValve 3328 to prevent back flow from the drive liquid compartment 3302. Feed liquid inlet stream 3306 is pumped by pump 3307 into feed liquid compartment 3303 and a control valve 3308 is provided to adjust the inlet flow rate to design flow rate Q. And a check valve 3309 is provided to prevent backflow. The source of feed liquid input stream 3322 may be from river water or treated wastewater, introduced through pump 3320 and control valve 3321. A water purification unit 3319 is provided for removing insoluble solids. FO membrane 3305 is provided in PEO module 3301 to produce a membrane with flux Q₁Permeate stream 3304. The rinse outlet flow 3310 may be eliminated. To control the PEO module 3301 as a steady state, continuous flow unit, a pressure relief valve 3313 and a check valve 3312 are provided. A pressure relief stream 3314 may be provided or a pressure relief stream 3315 may be injected into the pressurized mixed solution output stream 3311 to generate power. The PEO module 3301 then provides a turbine 3316 and generator 3317 for generating electricity. The mixed solution 3318 is discharged after power generation.

In the above-described PEO surface system of the invention, the NF or UF unit 3329 is used in conjunction with the FO module 3330 to produce a pressurized mixed solution output stream 3346 for two purposes: one is to provide a pressurized stream 3354 (flow rate Q)₄Representative) for pressure exchange operation, to cause the drive fluid compartment input flow 3326 to produce p₂And the other is to provide a pressurized stream 3353 (flow is selected as Q)₃) The high concentration driving liquid 3335 (flow rate selected as Q) is concentrated and recycled by reverse osmosis through a membrane 3334 in a permeation unit NF or UF 3329₃). Wherein the NF or UF of the osmosis unit 3329 is selected based on the particle size of the recycled high concentration draw solution 3335 solute used. The type of high concentration draw solution 3335 is selected based on solute stability, solubility/suspension, and avoidance of secondary pollution that may occur during discharge. In the present invention, the high concentration driving liquid 3335 according to the above standard may be selected from soluble inorganic salts such as metal chloride, metal oxide, metal sulfate and nitrate. Suitable inorganic salts are magnesium and calcium chlorides and sulphates. If a soluble inorganic salt solution is selected, the NF unit may be selected to be the osmosis unit 3329. The solute of the high concentration draw solution 3335 may also be selected from nanoparticles, and in combination with any of the inorganic salts described above. Wherein the nanoparticles comprise twoSilica, titania, nano-silicon crystals, nano-titanium particles, nano-clay minerals, non-toxic metal oxides, or combinations thereof, and the nano-particles are in a particle size range of 1nm to 1000nm, and wherein when the particle size is selected to be less than 5nm, the NF module is used as a reverse osmosis operation unit, and when the particle size is greater than 5nm, the UF module is used as a reverse osmosis operation unit, to concentrate the high concentration draw solution and to recover the filtrate. A suitable range of nanoparticles is 5 to 500nm, the most suitable range is 10 to 50 nm. The choice of nanoparticles is easier to handle than soluble salts and can save the energy required for re-concentration by the osmosis unit 3329. After the re-concentration operation, a permeate stream 3333 (selected at flux Q) is produced in the filtrate compartment 3331₄The flow of the concentrated driving liquid 3335 can be returned to Q₃). The filtered output stream 3351 may be recycled or eliminated. Pressurized stream 3354 is depressurized by a pressure exchange operation, but may meet pressurized stream 3353 via an energy exchange and fluid recovery device 3349 to recover solutes. The configuration of the synergistic FO module 3330 is similar to the PEO module 3301 and includes a drive fluid compartment 3338, a feed fluid compartment 3339 and an FO membrane 3340 to produce a permeate stream 3341 flux Q₄. Similar to the PEO module 3301, pumps 3336 and 3343, check valves 3337, 3345 and 3348, and control valves 3344 and 3347 are provided in conjunction with the FO module 3330. The feed liquid input stream 3342 is provided by the same water purification unit 3319 and the rinse liquid output stream 3350 may be reused as feed liquid or may be mixed with the filtered output stream 3351 to form a mixed solution 3352 for discharge or recycle. In the coordinated FO module 3330, a higher concentration of drive fluid 3335 is used to generate enough energy to provide energy p of the drive fluid compartment input stream 3326₂ x Q₂And the energy required for driving the re-concentration in the osmosis unit 3329, which will be discussed further later herein.

If the PEO surface system does not have a supply of seawater or salt lake water as the drive fluid, or sufficient supply of fresh water as the feed fluid, the process flow referred to above in FIG. 3C can also be simplified to a series combination of two modules, PEO 3301 and NF or UF 3329, to generate energy by a method comprising:

(1) using a PEO module, using the following steps (3) Recovered high concentration of the draw solution, and a value of beta selected to provide a flow rate of Q₂And hydraulic pressure is p₂And applying the feed liquid recovered in the following step (5) to produce a permeate flux Q₁And Q₂Producing a flow Q of the mixed liquid₁+Q₂To form p₂(Q₁+Q₂) The amount of power of (a) is,

(2) applying one or more NF or UF modules in series to the Q generated in step (1)₁+Q₂The mixed liquid flow is subjected to reverse osmosis operation to generate p₂And Q₂A high concentration of a driving liquid of, and p₅And Q₁The filtrate of (1), wherein p₅＝γp₂γ is the membrane efficiency coefficient of the NF or UF module, representing the percentage after pressure loss across the semipermeable membrane of the NF or UF module,

(3) p produced by the above step (2) is applied₂Q₂The high-concentration driving liquid is used as the high-concentration driving liquid required by the step (1),

(4) p produced by the above step (2) is applied₅Q₁A filter liquid and a power generation system comprising a water turbine and a generator positioned after the NF or UF module to supply energy p₅Q₁Is converted into electrical energy, and

(5) and (3) recovering and applying the filtrate generated in the step (4) as the feed liquid required by the step (1).

In the PEO water bottom system of the invention (fig. 3B), a PEO module 3202 is located in the PEO water bottom system 3201. A feed liquid input stream 3205 (e.g., river water or treated wastewater) having a flux Q is pumped through a pump 3206, a control valve 3229, and a check valve 3228 into the feed liquid compartment 3204. With flux Q₂Hydraulic pressure of p₂Is fed to a drive liquid inlet stream 3212 (e.g., seawater or salt lake water) through pump 3231, control valve 3211 into drive liquid compartment 3203. Wherein the hydraulic pressure p₂Is the synergistic effect of the hydraulic head 3225 created by the sea or salt lake water surface 3224. In order to control the steady continuous flow rate in the driving liquid chamber, check valves 3210 and 3216, a pressure gauge 3226, and a pressure reducing valve 3230 are used. Formed through the FO semi-permeable membrane 3227 with flux Q₁Permeate stream 3207. Benefit toA driving liquid input stream 3212 is drawn from the seawater or salt lake water intake with a filter 3209 and a flushing liquid output stream 3208 is discharged to a riser 3219 for discharge or to a storage tank for recovery (not shown). In this PEO subsea system design, flux Q can be obtained by a combination of turbine 3217 and generator 3218₁+Q₂To output a 3213 stream of pressurized mixed solution for power generation. The pressure relief stream 3215 is discharged to a riser 3219 by a pump 3214. The riser 3219 (details discussed in fig. 6A) provides a synergistic effect by utilizing the high pressure seawater input flow 3220, the jet air flow 3222 through the air pump 3223, and through heat exchange (not shown) to produce the release of the lower density mixed solution output flow 3221.

In the PEO sub-floor system of the present invention (FIG. 3D), a PEO module 3401 is located in the PEO sub-floor system 3400 at a depth no less than p₂The hydraulic head of (2). A feed liquid input stream 3406 with a PEO bottoming system flow rate Q is pumped into the feed liquid compartment 3403 by a pump 3407, a control valve 3408, and a check valve 3409. With flux Q₂Is maintained at p by a pump (not shown) and a driving liquid input stream 3424 (e.g., seawater or salt lake water)₂Is fed into the drive liquid compartment 3402 under the control of the control valve 3425 under hydraulic pressure. Hydraulic pressure p₂Is naturally produced by the synergistic effect of the hydraulic head 3433 below the water level 3432 of a sea or salt lake. To control the steady state continuous flow in drive liquid compartment 3402, check valves 3412, 3426, and pressure relief valve 3413 are used. Flux Q formed through FO semi-permeable membrane 3405₁And permeate stream 3404. A drive liquid input stream 3424 is drawn from the seawater or salt lake water inlet using a filter 3423 and the sluicing liquid output stream 3410 is discharged to a riser 3439 (details discussed in fig. 6A) for discharge or to a storage tank (not shown) for recovery. In the PEO bottoming system of the present invention, a combination of turbine 3416 and generator 3417 may be utilized to obtain flux Q₁+Q₂To output a stream 3411 of pressurized mixed solution for power generation. The pressure-released stream 3418 of the mixed solution is discharged to the riser 3439. If necessary, a pump 3434 is used to assist in the discharge. The risers 3439 have a synergistic effect by utilizing pressurized seawater or salt lake water input flow 3438, from gasA jet air stream 3437 is generated by pump 3436 to effect dilution (lower density) and heat exchange (not shown) for release. The pressurized pressure relief stream 3435 is passed through a riser 3439 to discharge a mixed solution output stream 3440. A source of feed liquid input stream 3422 (e.g., river water or treated wastewater) is introduced into water purification unit 2419 through pump 3420 and control valve 3421. To control the PEO module 3401 to steady state continuous flow, a pressure relief valve 3413 and a check valve 3412 are provided. A pressure let down stream 3414 may be provided or the pressure let down stream 3415 may be injected into the pressurized mixed solution output stream 3411 to generate electricity. Both bottom-of-water and bottom-of-ground PEO systems typically require the subsurface to be constructed deep enough to naturally provide p₂Without the need for additional energy. The depth required by the bottom of the water and the PEO system of the ground is sufficient to constitute another fresh water hydroelectric power plant of the present invention (not shown in FIG. 3B or 3D, but shown in FIGS. 1A and 1B). The head of the freshwater hydropower plant in both systems may be greater than the head of the Yangtze three gorges power plant!

Pressure conduit 3427, shown in fig. 3D, may provide a source of water to install water purification unit 2419 from the surface 3431, utilizing additional turbine 3428 and generator 3429 for power generation. The pressure relief stream may be vented to surge tank 3430 to meet the feed solution requirements of PEO module 3401.

In the present invention, one of the main differences between a PRO power generation system and a PEO power generation system is how to utilize the energy produced by the osmosis module for power generation. In PRO power generation systems, only p₂ x Q₁Is used to generate electricity, while in a PEO power generation system, all of the energy generated by the osmosis module (i.e., p)₂ x(Q₁+Q₂) May be used to generate electricity. Theoretical maximum power W generated from PRO power generation system_maxThe following were used:

W_max)_PRO＝(1/2Δπ_β)x(1/2J_βA)

＝(1/2βΔπ_e)x(1/2J_βA).............................(10)

however, the theoretical maximum power W that can be generated from a PEO power generation system_maxThe following were used:

W_max)_PEO＝(1/2βΔπ_e)x(1/2J_βA+Q₂)

＝(1/2βΔπ_e)x{1/2J_βA+[β/(1-β)x Q₁]}

＝(1/2βΔπ_e)x{1/2J_βA+[β/(1-β)x1/2J_βA]}

＝(1/2βΔπ_e)x{1/2J_βA x[1/(1-β)]}……………………(11)

the beta values for the PRO power generation systems described above are less than 0.667, while the beta values for the PEO systems are typically selected to be greater than 0.85. If the same data as in the permeate module example above is chosen (i.e., alpha 95%, beta 0.667vs 0.95, Q for Statkraft power plant)₁And Q₂) By comparison, one can compare the theoretical W obtained for PRO and PEO power generation systems_maxComprises the following steps:

W_max)_PRO＝(1/2x 0.95x 0.667x 26atm)x(1/2J_βA)

＝8.24atm x 10.33m x 10l/sec x 9.81m/sec²＝8.35kw。

W_max)_PEO＝11.74atm x 10.33m x(14.22l/sec+270.18l/sec)x 9.81m/sec²＝338.35kw。

the above data show that, under the assumption of the above conditions, W_max)_PEORatio W_max)_PROThe height 338.35/8.35 is 40.5 times higher. This situation means that approximately 40 equivalent Statkraft osmotic power plants can be produced using the PEO process compared to using the PRO process. Thus, the increase in maximum power production by the PEO system is enormous compared to the PRO system. Some PRO systems shown in the prior art were selected below for comparison with the power generation of the PEO system, as shown in table 2 below:

TABLE 2 comparison of Power Generation for PEO and PRO Power Generation systems

Table 2 comparison is based on the following assumptions: case 1 α is 93%, all other cases α are 95%; Δ π for cases 1, 4 and 5_o26atm, 28atm case 2, 25atm case 3; power generation efficiency (turbine + generator) of 55%; the energy required for pressure exchange in all PRO cases is not deducted; q₁，Q₂And β is from the relevant PRO system discussed in the literature; for all PEO systems, β ═ 0.9 was chosen.

PEO systems and their synergistic effects

In response to the deficiencies of PRO power generation systems, the PEO power generation system of the present invention is improved by the selection and synergy of β. The main synergistic effects in the present invention include: (1) is stably and continuously p₂And Q₂Supplying additional energy naturally available to avoid consuming the energy generated by the PEO system of the present invention, (2) utilizing the heat generated by the turbine and generator to increase osmotic pressure and assist in the waste brine discharge; (3) utilizing a lifter and an energy exchange and fluid recovery device to avoid energy waste and assist in the recovery or discharge of low-pressure water flow; (4) utilizing a synergy between an additional hydroelectric power plant and an osmotic power plant to increase energy production; and (5) maintaining steady-state continuous flow and controlling the synergy of devices such as backflow prevention, pressure relief flow and the like. The synergistic effect described above is further explained below.

(1)p₂And Q₂The natural available energy of (a):

in the present invention, two systems are proposed to harness naturally available energy, one being a PEO surface system using a combination of synergistic FO modules and NF units or FO and UF units as shown in FIG. 3C. The other is a PEO underground system using a hydraulic head generated by the gravitational force as shown in FIGS. 3B and 3D or FIGS. 1A and 1B. Comparing the two naturally available additional energies, the PEO surface system has the advantage that it can be placed on the ground wherever drive and feed fluids are available and also can reduce the cost of building a PEO infiltration unit on the ground. Use in PEO surface systems for Q generation₃The driving liquid can also automatically weighRe-concentrated and reused. However, an advantage of the PEO subsurface system of the present invention is that no additional above-ground system need be constructed and operated to produce p₃And introducing a driving liquid Q₃. In this case, if seawater or lake brine is used as the driving liquid Q for the PEO underground system₂In combination with the use of fresh water (i.e., river water or treated wastewater) as the feed liquid, the drive liquid itself maintains Q as the power generation system is constructed underground₂P of (a)₂And (4) pressure. In addition to using osmotic power generation in an underground environment, PEO underground systems can also utilize the pressure differential of fresh water introduced into the ground to build an additional hydroelectric power plant to generate more additional energy.

For the PEO surface system of the present invention, a drive liquid Q in a coordinated FO module 3330 is used₃Concentration ratio of (2) for the driving liquid Q of the PEO module 3301₂The concentration is much higher and therefore additional energy is available for the PEO module 3301. As shown in FIG. 3C, energy p generated by the collaborative FO module 3330₃Q₃Can be used to provide additional energy p to the PEO module 3301₂Q₂. Selected Q₃The higher the concentration, the maximum pressure difference that can be provided (using the notation Δ π)_o' expression) is also higher, the hydraulic pressure p generated₃The calculation can be as follows:

p₃＝1/2Δπ_β3'＝1/2α₃β₃Δπ_o'…………………………………………………(12)

wherein alpha is₃Represents the membrane efficiency, dilution factor β, of the cooperative FO module 3330₃Can be prepared from₃＝Q₃/(Q₃+Q₄) And (4) calculating. If η represents the combined efficiency of the pressure exchanger 3325, the energy exchange and fluid recovery device 3349, and the friction pressure losses of other associated pumps and pipes, p represents the flow rate for pumping Q₂Pressure of driving liquid 3323, alpha₂Expressing the membrane efficiency of the osmosis unit 3329, and applying the correlation equations discussed above, the following equation can be derived to express the minimum Q required₃And Q₄：

Q₃≥{[1/2αβ(1+η)Δπ_o-p]β₃Q₂}/{α₃β₃(1-β₃)[1/2-1/2(1-α₂+η)]Δπ_o’}…………………………………………………………………………(13)

Q₄＝[(1-β₃)/β₃]Q₃……………………………………………………(14)

For example, when selecting Δ π_o'＝2Δπ_oTo provide p to the PEO module 3301₂Q₂Energy, based on the above equations (12), (13) and (14), when α is 95%, β is 0.9, α₂＝97％，α₃＝95％，β₃＝0.95，p＝1atm，Δπ_o26atm, and 5% η, a minimum of p is required₃，Q₃And Q₄The following data can be calculated: q₃≥9.39Q₂，p₃＝23.47atm，Q₄≥0.49Q₂. If the above data is selected, the modular units 3329 and 3330 of the PEO surface system may be operated continuously under steady state conditions. As another example, if a higher Δ π is selected_o' (e.g., Δ π_o'＝4Δπ_o) And under the same assumption as above, the following data can be calculated: q₃≥4.70Q₂，p₃＝46.93atm，Q₄≥0.25Q₂. The above data show that when selecting higher Δ π_oWhen Q is₃And Q₄The flow requirements will be reduced and the size of the permeate modules 3329 and 3330 will be reduced. This may reduce the cost of building the PEO surface system.

For the PEO underground system of the present invention, the naturally available additional energy source may come from the hydraulic head of seawater (or salt lake water), such as hydraulic head 3225 in FIG. 3B, and 3433 in FIG. 3D. As discussed above, PEO subterranean systems do not require the construction of additional permeate cells to supply p₃And Q₃. In this case, the minimum depth of the underground power plant should be at least equal to p₂The depth of the hydraulic head. As shown in Table 2, if a shallower PEO subsurface system is to be constructed, a smaller value of β may be selected.

(2) Synergistic effect of waste heat recycling:

the hydro or osmotic power plant of the present invention will generate waste heat due to the relatively low power conversion efficiency of the turbine and generator in the power generation system (typically only 50% to 60% of the combined power). The turbine and generator may use the waste heat recovery for a variety of purposes such as increasing the osmotic pressure generated in the osmotic module (i.e., increasing T in equation (2) above) and decreasing the density of the discharged waste fluid by heat exchange to facilitate the discharge of the waste fluid in a high pressure environment through the risers (i.e., 3219 in fig. 3B and 3439 in fig. 3D) in the PEO underground system of the present invention. These synergistic effects on the osmotic power plant can be used not only to increase the energy produced by the osmotic unit, but more importantly, they can also facilitate the function of the riser to allow the discharge of waste fluids from the PEO underground system.

(3) The synergistic effect of injecting the low-pressure flow into the high-pressure flow and exchanging energy and recovering the fluid is realized:

in the PEO system of the present invention, it may be necessary to reinject some of the low pressure stream into the high pressure stream for recycle or venting. The present invention provides a combination of a specially designed riser (fig. 6A) and an energy exchange and fluid recovery device (fig. 6B) to assist in the above conditions. As will be described in more detail later herein.

(4) Synergistic effects between hydroelectric and osmotic power plants:

conventional hydroelectric power plants require several critical conditions to be fulfilled, such as drainage facilities that require high head, relatively high water flow, and relatively low water pressure after power generation. The PEO subterranean system of the present invention can provide all of the above conditions, and thus additional hydroelectric power plants can be installed with the osmotic power plant. The hydraulic head of this additional hydroelectric power plant may be very high (approaching or exceeding the head of the world's largest three gorges Yangtze river hydroelectric power plant). As shown in fig. 1A, 1B and 3D, the PEO underground system of the present invention may also provide underground surge tanks 15 and 3430 to store the depressurized water in preparation for use as a feed solution for a subsequent osmotic power plant.

As shown in fig. 1A and 1B, in the underground junctionIn configuration E, a hydroelectric power plant A and a plurality of osmotic power plants (only two power plants B and C are shown) may be constructed, located near the estuary. The river water 51 is pumped out from the intake structure 10 to generate power. A fresh water purification apparatus 11 may be installed to remove suspended solids. Then, the purified water is flowed through the pressure water pipe 12 using the turbine 13 and the generator 14 to generate water power. As shown in power plants B and C of fig. 1A and 1B, a surge tank 15 was provided to use the stored water as a feed for the next several PEO infiltration units to generate more power. Because of the high beta values selected in the PEO system, multiple osmotic power plants can be built. For example, when β is 0.9, Q is based on equation (5)₂(the flow of drive liquid, in this case seawater) will be Q₁Nine (9) times (fresh water feed solution permeation flux). This means that if the flow rate of the fresh water source used in the hydroelectric power generation is chosen to be 0.9, this flow rate is sufficient for use as feed solution for up to 9 osmotic power plants. This phenomenon suggests an incredibly significant synergistic effect, which also means that if the PEO process is used, the use of fresh water-seawater for osmotic power generation can generate a huge renewable energy source. When fresh water with the equivalent generating capacity of the three gorges hydropower station flows to the estuary, the generated osmotic generating power is nine times of the power of the original upstream hydropower station. Installation of a hydroelectric power plant would be very easy in the underground PEO system of the present invention compared to conventional hydroelectric power plants, which would be economically cost effective to build in comparable manner to or more, since they require costly dams and reservoirs to be constructed in deep mountainous areas.

As shown in fig. 1A and 1B, all underground power plants can deliver power to substations 17, 27, 37 and 57 via power lines 16, 26 and 36 and transmit power via transmission towers 18, 28, 38 and 58. The turbines 23 and 33 and generators 24 and 34 may be followed by a plurality of fresh water (feed fluid) inlet streams 20 and 30, a plurality of osmosis units 21 and 31 and a plurality of surge tanks 25 and 35. A pipe with a filter 50 is located below the sea surface 52 to introduce the sea water by the synergistic effect of the naturally occurring hydraulic head of gravitational potential energy. Seawater is used as the drive liquid and the intake seawater is distributed through the distribution chamber 45. The diluted pressure-relieved brine 40 from osmotic power generation is discharged into a relatively high pressure seawater environment by the cooperation of an air pump 43, a relatively high temperature and relatively low density assist, and the automatic intake of seawater 42, and a riser 41.

(5) The synergistic effect of maintaining steady state continuous flow and preventing backflow from preventing overpressure:

maintaining steady state continuous flow is important to the function of the drive liquid compartment. In the present invention, a check valve and a pressure reducing valve are provided for this purpose. The check valve prevents back flow and the pressure relief valve prevents pressure from exceeding p if the pressure in the drive fluid compartment changes due to flow and hydraulic imbalance₂。

5. The invention relates to a permeation module, a riser and an energy exchange and fluid recovery device

Many basic types of FO permeate membrane modules are commercially available, such as flat plate tangential flow permeate membrane modules, hollow fiber permeate membrane modules, spiral permeate membrane modules and tubular permeate membrane modules. While all of the membrane modules described above can be applied in the PEO system of the present invention, the PEO system of the present invention develops a specific design of the PEO module 511 for ease of control of concentration polarization and steady state flow, as shown in FIG. 5B. The PEO module 511 is formed from a plurality of substantially tubular membrane modules 501 as shown in FIG. 5A. The basic tubular membrane module 501 is modified from a commercially available module and consists of a number of capillary type FO membrane tubes 503 located within a porous tube housing 502. Feed liquid 504 enters the tube from one end of the basic tubular membrane module 501 as shown in fig. 5A and 5C. In the tubular membrane module 501, a feed effluent (also referred to herein as a sweep liquid) 505 exits from the other side of the basic tubular membrane module 501. Permeate and drive liquid 506 enters and exits through the perforated tube housing 502.

As shown in fig. 5B, a plurality of elementary tubular membrane modules 501 are installed in a PEO module 511. The PEO module 511 is a pressure vessel with a stainless steel shell, the pressure p within the pressure vessel₂Is generated by the selected beta value of the drive liquid. May be based on the Q generated by a plurality of elementary tubular membrane modules 501₁Flux to calculate what is in each PEO module 511The total film area required, the Q shown in the equation discussed above₁Flux is selected again by beta, delta pi_βAnd Q₂The impact of the data. The flow rate of the driving liquid 512 is controlled by a control valve 513 via a pump 514, if necessary. Through check valve 515 to avoid backflow of pressurized mixed solution 519. A propeller mixer 516 and a turbine mixer 517 are provided to homogenize the mixed solution and reduce the effect of External Concentration Polarization (ECP). As shown in fig. 5B and 5D, propeller mixer 516 is capable of producing vertical convection, while turbine mixer 517 is capable of producing radial mixing flow, so that the homogeneous draw solution and permeate flux producing filtrate can enter and permeate out through perforated tube housing 502. The pressurized mixed solution 519 through the pressurized mixed solution output line 518 may be drained and combined with the effluent from other parallel PEO permeation modules to generate electricity. The PEO module 511 provides a pressure relief valve 523 to avoid any excess over a selected p₂Pressure to help maintain steady state conditions of the PEO module. Pressurized stream 524 (if any) may be added to the effluent 519 to generate power. A pressure gauge 520, control valve 521 and control pump 522 are used for the necessary regulation of the vessel pressure. A more detailed schematic cross-sectional view of fig. 5B is provided in fig. 5C and 5D.

A schematic of a riser 601 of the present invention is shown in fig. 6A. The primary purpose of riser 601 is to dissipate the pressure stream 602 released after power generation into a relatively high pressure seawater or salt lake water environment. Riser 601 has a cylindrical stainless steel or titanium (titanium) shell and a narrow fluid passage in the center, which is provided with an air jet 603 to create a lower density fluid to assist in the rapid lift flow of the pressure stream 602 released after power generation. A stream 604 of relatively high pressure and high density seawater (or salt lake water) is automatically input into the bottom region of riser 601 to help relieve pressure stream 602. The air jets and the aforementioned heat exchange effect may assist in the dissipation of the mixed solution 605. The use of this riser 601 makes possible the release flow of PEO underground power plants, avoiding the need for high pressure and high energy when discharging waste liquids.

The energy exchange and fluid recovery device is shown in fig. 6B. The design of the energy exchange and fluid recovery device is that the energy exchange and fluid recovery device is composed of an energy exchange device and a fluid recovery deviceThe combination of the displacer 611 and the modified venturi ejector device 621. Such a combined apparatus can provide for the introduction of a low pressure drive liquid (e.g., seawater or other salt lake water) 612 influent while producing a high pressure drive liquid 613 effluent, and can also recover a pressurized stream 622 for the PEO surface system after energy exchange. As shown in FIG. 6B, the high pressure drive liquid 613 can provide the p required by the PEO module 3301 (shown in FIG. 3C)₂And Q₂The driving liquid of (1). To recover solutes and/or nanoparticles in the energy exchanged low pressure high concentration stream 623, a fluid recovery device of the modified venturi ejector 621 is provided. As shown in fig. 3C, the pressurized high-strength output stream 3346 is split into two pressurized fluids 3353 and 3354, which in fig. 6B are pressurized high-strength input streams 624 and 622, respectively. The resulting mixed high pressure stream 625 is injected into NF or UF unit 3329 for re-concentration. The combined energy exchange and fluid recovery device may provide additional natural energy available, as previously described, to enable a PEO surface system to utilize all of the energy in the pressurized mixed output stream 3311 to generate electricity as compared to a PRO system.

The above-described principles, methods, embodiments and main devices are used to explain the objects, technical solutions and effects of the present invention in detail. It should be understood that the above-described specific embodiments are not intended to limit the invention. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.