阅读说明：本技术 一种lng动力船碳减排系统和方法 (Carbon emission reduction system and method for LNG power ship ) 是由 武彦峰 胡国强 于 2021-08-23 设计创作，主要内容包括：本申请公开一种LNG动力船碳减排系统和方法,其中所述LNG动力船碳减排系统包括LNG燃料供应系统和碳回收系统；其中所述LNG燃料供应系统包括依次连接的LNG储罐、LNG气化器、天然气加热器、船舶用气设备和烟气排放设备,其中所述LNG储罐储存有LNG燃料；其中所述碳回收系统包括依次连接的第一海水冷却器、水分脱除装置、CO-(2)分离装置和CO-(2)液化和存储装置。LNG燃料供应系统提供天然气给船舶用气设备燃烧；燃烧产生的烟气通过碳回收系统将其中大部分CO-(2)收集、液化并存储起来,满足环保政策对碳排放的要求；存储在液态CO-(2)储罐中的液态CO-(2),可定期卸放给液态CO-(2)储运设施或储运船舶,并最终排入海洋底部由废气油气井改造而成的CO-(2)储藏库中,实现减排CO-(2)的最终目的。(The application discloses a carbon emission reduction system and method for an LNG power ship, wherein the carbon emission reduction system for the LNG power ship comprises an LNG fuel supply system and a carbon recovery system; the LNG fuel supply system comprises an LNG storage tank, an LNG vaporizer, a natural gas heater, a marine gas device and a flue gas emission device which are sequentially connected, wherein the LNG storage tank stores LNG fuel; wherein the carbon recovery system comprises a first seawater cooler, a moisture removal device and CO which are connected in sequence 2 Separation device andCO 2 a liquefaction and storage unit. The LNG fuel supply system provides natural gas for the ship gas-using equipment to burn; most of CO in flue gas generated by combustion is recycled through a carbon recovery system 2 The carbon is collected, liquefied and stored, so that the requirement of environmental protection policy on carbon emission is met; stored in liquid CO 2 Liquid CO in storage tank 2 Can be discharged to liquid CO periodically 2 Storage and transportation facilities or ships, and finally discharging into the ocean bottom CO reformed by a waste gas oil-gas well 2 In a storage to reduce CO emission 2 The final object of (1).)

1. The LNG power ship carbon emission reduction system is characterized by comprising:

an LNG fuel supply system, wherein the LNG fuel supply system comprises an LNG storage tank, CO connected in sequence₂The system comprises a condenser, a natural gas heater, a marine gas device and a flue gas emission device, wherein the LNG storage tank stores LNG fuel; and

a carbon recovery system, wherein the carbon recovery system comprises a first seawater cooler, a moisture removal device and CO which are connected in sequence₂Separation apparatus and CO₂The inlet of the first seawater cooler is communicated with the smoke discharge equipment to reduce the temperature of smoke generated by combustion.

2. The LNG-powered vessel carbon emission reduction system of claim 1, wherein the natural gas heater is provided with a heating medium inlet and a heating medium outlet communicating with the marine gas plant to supply heat to the natural gas heater through a heat exchange medium using waste heat generated by the marine gas plant.

3. The LNG-powered vessel carbon abatement system of claim 1, wherein the CO is₂The separation devices are embodied as a first PSA separation device provided with a first vent and a second PSA separation device provided with a second vent, wherein the second PSA separation device is located downstream of the first PSA separation device, the outlet of the second PSA separation device being in communication with the CO₂Liquefaction and storage means, the operating pressure of said first PSA separation means being less than the operating pressure of said second PSA separation means.

4. The LNG-powered vessel carbon emission reduction system of claim 3, wherein the first PSA separation device operates at a pressure of 0.2MPa to 0.6 MPa; the working pressure of the second PSA separation device is 0.3 MPa-1.5 MPa.

5. The LNG-powered vessel carbon abatement system of claim 4, wherein the adsorbent in the first PSA separation device is implemented as coarse-pore microspheroidal silica gel coated with a 30% -50% strength MDEA solution.

6. The LNG-powered vessel carbon abatement system of claim 1, wherein the CO is₂The separation device is embodied as a one-stage membrane separation device, or as a two-stage membrane separation device, wherein the membrane separation devices are each provided with a gas outlet, the membrane separation devices being formed from CO₂/N₂Separation membrane, said CO₂/N₂The selectivity of the separation membrane is greater than 80.

7. The LNG-powered vessel carbon abatement system of claim 1, wherein the CO is₂The separation device is implemented as a composite of a membrane separation device and a PSA separation device, wherein the membrane separation device and the PSA separation device are respectively provided with a gas outlet, the PSA separation device is positioned at the downstream of the membrane separation device, and the membrane separation device is composed of CO₂/N₂Separation membrane, said CO₂/N₂The selectivity of the separation membrane is greater than 80.

8. The LNG-powered vessel carbon emission reduction system of any one of claims 3 to 7, wherein the CO is present in a gas phase in the gas phase₂The liquefaction and storage device comprises a compressor, a second seawater cooler and the CO which are connected in sequence₂Condenser and liquid CO₂A storage tank, wherein the air inlet of the compressor is communicated with the CO₂The gas outlet of the compressor is communicated with the inlet of the second seawater cooler and is used for reducing the temperature of the compressed gas;

the CO is₂A condenser is located downstream of the second seawater cooler to utilize cold energy released by the LNG fuel to convert gaseous CO₂Condensed to a liquid state and flowed into the liquid CO₂Storing in a storage tank;

the CO is₂The condenser is also provided with an exhaust port for exhausting uncondensed gas;

the liquid CO₂The storage tank is also provided with a liquid outlet for discharging liquid CO₂And (4) refuting to other storage and transportation containers.

9. The LNG-powered ship carbon emission reduction system of claim 8, wherein the compressor has a working pressure of 0.6Mpa to 1 Mpa; the CO is₂Liquid CO at the outlet of the condenser₂The temperature range of the temperature is-65 ℃ to-60 ℃.

10. An LNG powered vessel carbon emission reduction method using the LNG powered vessel carbon emission reduction system of any one of claims 1 to 9, the LNG powered vessel carbon emission reduction method comprising the steps of:

(a) by said CO₂The condenser and the natural gas heater heat the LNG fuel in a grading manner so as to meet the temperature required by combustion of the marine gas equipment;

(b) cooling the flue gas generated after the LNG fuel is combusted to the temperature of seawater;

(c) removing moisture in the cooled flue gas through the moisture removal device;

(d) separating CO in the flue gas by a two-stage PSA separation device, a one-stage or two-stage membrane separation device or a combination of the membrane separation device and the PSA separation device₂；

(e) Compressing the CO₂Separating the treated gas from the device;

(f) cooling the compressed gas to a seawater temperature;

(g) by said CO₂A condenser for cooling the compressed gas by using the cold energy released from the LNG fuel to convert the gaseous CO into a gas₂Condensing into liquid state;

(h) by liquid CO₂Storage tank for storing liquid CO₂；

(i) After the liquid CO2 storage tank reaches a volume limit, the liquid CO is introduced₂Lightens to liquid CO₂Transporting the ship and transferring the liquid CO₂Transporting and finally discharging CO transformed from waste gas oil and gas well into ocean bottom₂In a storage.

11. The LNG-powered ship carbon emission reduction method of claim 10, wherein in the two-stage PSA separation apparatus, the operating pressure of the first-stage PSA separation is controlled to 0.2Mpa to 0.6Mpa, and the operating pressure of the second-stage PSA separation is controlled to 0.3Mpa to 1.5 Mpa.

12. The LNG-powered ship carbon abatement method of claim 11, wherein the CO in the gas separated by the first stage PSA is controlled₂The component ratio of (A) is 40-60%, and CO in the gas discharged after the first-stage PSA separation is controlled₂In an amount corresponding to the amount of CO in said flue gas₂Not higher than 20% in total;

controlling CO in gas separated by second stage PSA₂The component ratio of (A) is 90-95%, and CO in the gas discharged after the second-stage PSA separation is controlled₂In an amount corresponding to the amount of CO in said flue gas₂Not higher than 12% in total;

controlling the CO from₂CO in gas discharged from gas outlet of condenser and not condensed₂In an amount corresponding to the amount of CO in said flue gas₂The total amount of (A) is not higher than 3%.

13. The LNG-powered ship carbon emission reduction method as set forth in claim 10, wherein the pressure of the gas compressed in the step (e) is controlled to be 0.6Mpa to 1 Mpa; controlling the liquid CO in step (g)₂The temperature of the reaction is-65 ℃ to-60 ℃.

Technical Field

The invention relates to the technical field of LNG power ships, in particular to a carbon emission reduction system and method for an LNG power ship.

Background

LNG (liquefied natural gas) is an important power fuel for reducing pollution of ships due to its advantages of safety, cleanliness and economy. In recent years, LNG powered ships are gradually popularized in international ocean transportation, and fleets grow fast and tend to be large-scaled in batch. Under the impetus of policies such as international maritime organization sulfur restriction and national pollution control, global LNG powered ships are entering a rapid development phase.

However, LNG can only partially meet the requirements for carbon emissions in addition to the requirements for sulfur and nitrogen emissions; if some fuels which can completely meet the carbon emission requirement, such as hydrogen fuels, are used, a series of problems of high cost, great safety difficulty and the like are faced.

At present, some ships have technical schemes for solving the carbon emission requirement, but because the actual conditions and scheme cost of the ships are not considered in place, the real implementation and operation cost is very high, so that the scheme per se only has theoretical possibility, and the feasibility of real implementation on the ships is basically unavailable.

The invention makes full use of the cold energy contained in the LNG fuel to reduce the CO content to the greatest extent on the basis of using the LNG fuel by the ship₂The energy consumed in the process is collected. On the premise that the ship meets the carbon emission requirement, the invention has great attention on the applicability and the actual energy consumption of the system on the ship, has mature theory, is convenient for system implementation and has strong practicability. The invention can enable the ship using the LNG fuel to meet all the carbon emission requirements at present and in the future for a long time, makes up the defects of the LNG fuel in the problem of carbon emission, and has important application value.

Disclosure of Invention

One advantage of the present invention is to provide a carbon emission reduction system for LNG-powered ships, which utilizes the cold energy contained in the LNG fuel of the ships to produce CO in the flue gas through combustion by a carbon recovery system₂Collected, and a large amount of energy required in the carbon recovery process is saved.

The inventionOne advantage of (a) is to provide a carbon emission reduction system for LNG-powered ships, which makes it possible to treat, separate and liquefy CO by fully considering the energy consumption of a carbon recovery system and the realizability of equipment application on ships based on a ship LNG fuel supply system₂The energy consumption is the lowest, and the equipment is the simplest.

One advantage of the invention is that the carbon emission reduction system for the LNG power ship is provided, the system is simple and clear in structure, easy to arrange, mature in technology and easy to popularize on a large scale, and a set of complete and feasible scheme for carbon emission reduction of the LNG power ship is formed. Finally, CO is liquefied and recovered for emission reduction₂To achieve total CO produced by combustion₂More than 65 percent of the total carbon emission requirements of the LNG power ship are finally met, the defects of the LNG fuel on the carbon emission problem are effectively overcome, and the LNG power ship has important application value.

One advantage of the present invention is to provide a carbon emission reduction system for an LNG-powered ship, which utilizes seawater to cool a gas to be cooled, and utilizes waste heat of a ship engine to provide additional heat for natural gas, thereby saving energy as much as possible and reducing the operation cost of the system.

One advantage of the present invention is to provide a carbon emission reduction system for LNG-powered vessels via CO₂The separation device can separate CO in the waste gas₂Separated out of CO₂The separation device can be composed of two successive PSA separation devices, or one or two membrane separation devices, or one membrane separation device and one PSA separation device. By using two-stage separation device, each stage can select relatively proper method and working parameters according to the components and characteristics of the gas to be treated, thereby fully exerting the equipment capacity, reducing the energy consumption and finally leading CO to pass through₂CO in gas of separation device₂The component proportion of (A) is more than 95%.

An advantage of the present invention is to provide a carbon emission reduction system for LNG-powered vessels, the CO₂If the separation device consists of two stages of PSA separation devices, the first stage separation device works under lower working pressure, so that a large amount of energy can be saved, and the second stage separation device works under relatively higher working pressure, so that the separation effect can be ensured. First stage separation deviceThe adsorbent used, which is an adsorbent that still has a good adsorptive separation at lower pressures, can be implemented as a macroporous microspherical silica gel coated with a solution of MDEA of a specific concentration.

An advantage of the present invention is to provide a carbon emission reduction system for LNG-powered vessels, the CO₂If the separation device consists of a membrane separation device, the membrane separation device consists of a membrane with higher CO₂Permeability and CO₂/N₂Selective membrane materials, such as microporous polymer membranes.

To achieve at least one of the above advantages, the present invention provides a carbon emission reduction system for an LNG-powered vessel. The LNG power ship carbon emission reduction system includes:

an LNG fuel supply system, wherein the LNG fuel supply system comprises an LNG storage tank, CO connected in sequence₂The system comprises a condenser, a natural gas heater, a marine gas device and a flue gas emission device, wherein the LNG storage tank stores LNG fuel;

and

a carbon recovery system, wherein the carbon recovery system comprises a first seawater cooler, a moisture removal device and CO which are connected in sequence₂Separation apparatus and CO₂The inlet of the first seawater cooler is communicated with the smoke discharge equipment to reduce the temperature of smoke generated by combustion.

According to an embodiment of the invention, the natural gas heater is provided with a heating medium inlet and a heating medium outlet which are communicated with the marine gas equipment, so that waste heat generated by the marine gas equipment is utilized to supply heat to the natural gas heater through a heat exchange medium.

According to an embodiment of the invention, the CO is₂The separation devices are embodied as a first PSA separation device provided with a first vent and a second PSA separation device provided with a second vent, wherein the second PSA separation device is located downstream of the first PSA separation device, the outlet of the second PSA separation device being in communication with the CO₂The liquefaction and storage unit is connected, and the working pressure of the first PSA separation unit is less thanThe operating pressure of the second PSA separation device.

According to one embodiment of the invention, the working pressure of the first PSA separation device is 0.2 MPa-0.6 MPa; the working pressure of the second PSA separation device is 0.3 MPa-1.5 MPa.

According to an embodiment of the invention, the adsorbent in the first PSA separation unit is implemented as a silica gel with coarse-pored microspheres coated with a 30% to 50% strength MDEA solution.

According to an embodiment of the invention, the CO is₂The separation device is embodied as a one-stage membrane separation device, or as a two-stage membrane separation device, wherein the membrane separation devices are each provided with a gas outlet, the membrane separation devices being formed from CO₂/N₂Separation membrane, said CO₂/N₂The selectivity of the separation membrane is greater than 80.

According to an embodiment of the invention, the CO is₂The separation device is implemented as a composite of a membrane separation device and a PSA separation device, wherein the membrane separation device and the PSA separation device are provided with a gas discharge port, respectively, and the PSA separation device is located downstream of the membrane separation device.

According to an embodiment of the invention, the CO is₂The liquefaction and storage device comprises a compressor, a second seawater cooler and the CO which are connected in sequence₂Condenser and liquid CO₂A storage tank, wherein the air inlet of the compressor is communicated with the CO₂The gas outlet of the compressor is communicated with the inlet of the second seawater cooler and is used for reducing the temperature of the compressed gas;

the CO is₂A condenser is located downstream of the second seawater cooler to utilize cold energy released by the LNG fuel to convert gaseous CO₂Condensed to a liquid state and flowed into the liquid CO₂Storing in a storage tank;

the CO is₂The condenser is also provided with an exhaust port for exhausting uncondensed gas;

the liquid CO₂The storage tank is also provided with a liquid outlet for discharging liquid CO₂And (4) refuting to other storage and transportation containers.

According to the bookIn one embodiment of the invention, the working pressure of the compressor is 0.6-1 Mpa; the CO is₂Liquid CO at the outlet of the condenser₂The temperature range of the temperature is-65 ℃ to-60 ℃.

The invention also provides an LNG power ship carbon emission reduction method using the LNG power ship carbon emission reduction system, wherein the LNG power ship carbon emission reduction method comprises the following steps:

(a) by said CO₂The condenser and the natural gas heater heat the LNG fuel in a grading manner so as to meet the temperature required by combustion of the marine gas equipment;

(b) cooling the flue gas generated after the LNG fuel is combusted to the temperature of seawater;

(c) removing moisture in the cooled flue gas through the moisture removal device;

(d) separating CO in the flue gas by a two-stage PSA separation device, a one-stage or two-stage membrane separation device or a combination of the membrane separation device and the PSA separation device₂；

(e) Compressing the CO₂Separating the treated gas from the device;

(f) cooling the compressed gas to a seawater temperature;

(g) by said CO₂A condenser for cooling the compressed gas by using the cold energy released from the LNG fuel to convert the gaseous CO into a gas₂Condensing into liquid state;

(h) by liquid CO₂Storage tank for storing liquid CO₂；

(i) After the liquid CO2 storage tank reaches a volume limit, the liquid CO is introduced₂Lightens to liquid CO₂Transporting the ship and transferring the liquid CO₂Transporting and finally discharging CO transformed from waste gas oil and gas well into ocean bottom₂In a storage.

According to an embodiment of the invention, in the two-stage PSA separation device, the working pressure of the first-stage PSA separation is controlled to be 0.2 MPa-0.6 MPa, and the working pressure of the second-stage PSA separation is controlled to be 0.3 MPa-1.5 MPa.

According to one embodiment of the invention, the control of the gas after the first stage PSA separationCO₂The component ratio of (A) is 40-60%, and CO in the gas discharged after the first-stage PSA separation is controlled₂In an amount corresponding to the amount of CO in said flue gas₂Not higher than 20% in total;

controlling CO in gas separated by second stage PSA₂The component ratio of (A) is 90-95%, and CO in the gas discharged after the second-stage PSA separation is controlled₂In an amount corresponding to the amount of CO in said flue gas₂Not higher than 12% in total;

controlling the CO from₂CO in gas discharged from gas outlet of condenser and not condensed₂In an amount corresponding to the amount of CO in said flue gas₂The total amount of (A) is not higher than 3%.

According to an embodiment of the present invention, the pressure of the gas compressed in the step (e) is controlled to be 0.6Mpa to 1 Mpa; controlling the liquid CO in step (g)₂The temperature of the reaction is-65 ℃ to-60 ℃.

Drawings

Fig. 1 shows a schematic flow diagram of the carbon emission reduction system of the LNG-powered vessel according to the present application.

Fig. 2 shows a second schematic flow diagram of the LNG-powered vessel carbon abatement system of the present application.

Fig. 3 shows a third schematic flow diagram of the LNG-powered vessel carbon abatement system of the present application.

Detailed Description

The following description is presented to disclose the invention so as to enable any person skilled in the art to practice the invention. The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art. The basic principles of the invention, as defined in the following description, may be applied to other embodiments, variations, modifications, equivalents, and other technical solutions without departing from the spirit and scope of the invention.

It will be understood by those skilled in the art that in the disclosure of the specification, the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those illustrated in the drawings, which are merely for convenience in describing the invention and to simplify the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and, therefore, the terms should not be construed as limiting the invention.

It is understood that the terms "a" and "an" should be interpreted as meaning that a number of one element or element is one in one embodiment, while a number of other elements is one in another embodiment, and the terms "a" and "an" should not be interpreted as limiting the number.

Referring to fig. 1, 2 and 3, a carbon emission reduction system for an LNG-powered ship according to a preferred embodiment of the present invention will be described in detail below, wherein the carbon emission reduction system for an LNG-powered ship comprises an LNG fuel supply system and a carbon recovery system, so as to collect CO in flue gas generated by burning LNG fuel through the carbon recovery system based on the LNG fuel supply system₂. On the premise of ensuring the simplest equipment and the lowest energy consumption, the carbon emission reduction rate can reach more than 65 percent, so that the carbon emission requirements of the near term and the long term are met, the defect of the LNG fuel on the carbon emission problem is overcome, and the LNG fuel has important application value.

The LNG fuel supply system comprises an LNG storage tank 100 and CO which are connected in sequence₂A condenser 11, a natural gas heater 12, and a marine gas appliance (e.g., an engine) 13 and a flue gas discharge device 14, wherein the LNG storage tank 100 stores LNG fuel, in which CO is contained₂The condenser comprises an LNG inlet 111 and a natural gas outlet 112, and additionally comprises gaseous CO₂Inlet 113 and liquid CO₂An outlet 114;

in particular, the LNG fuel is at the discharge P of the LNG storage tank 100₁The temperature of (a) is about-162 ℃. Passing LNG fuel through the CO₂LNG inlet 111 of condenser 11 enters, becomes natural gas with certain temperature after heat exchange, and passes through CO₂The natural gas flows out from the natural gas outlet 112 of the condenser 11, and then is continuously heated by the natural gas heater 12, and finally reaches a temperature suitable for the marine gas equipment (such as an engine) 13. The natural gas heater 12 is provided with heatingA medium inlet 121 and a heating medium outlet 122. The heating medium supplies heat to the natural gas heater 12 through a heat exchange cycle formed by the heating medium inlet 121 and the heating medium outlet 122. The heat source of the heating medium can be waste heat of the marine gas equipment (such as an engine) 13, so that energy is saved and cost is reduced.

When the natural gas is combusted in the marine plant 13, the marine plant 13 draws in sufficient air through the air inlet 131 to ensure that the natural gas can be oxygen-enriched. The flue gas resulting from the combustion is discharged through a flue gas discharge device 14. Temperature of exhaust fumes, i.e. P₂The temperature of the spot is around 350 ℃. The volume ratio of the smoke components is as follows: n is a radical of₂At about 75%, CO₂About 14.5%, about 9.5% moisture, and the balance other gases.

The carbon recovery system comprises a first seawater cooler 21, a moisture removal device 22 and CO which are connected in sequence₂Separation device 30 and CO₂A liquefaction and storage unit.

The inlet of the first seawater cooler 21 is communicated with the flue gas discharge device 14, and is provided with a seawater inlet 211 and a seawater outlet 212, so that the temperature of the flue gas generated by combustion is reduced to the temperature of the seawater, namely about 35 ℃ through the circulating heat exchange of the seawater.

The cooled flue gas enters the moisture removal device 22 to remove moisture contained in the flue gas. The removed moisture is discharged through a moisture outlet 221 at the bottom of the moisture removing device 22. The main component of the flue gas after moisture removal is N₂And CO₂. At the outlet of the moisture removal device 22, i.e. P₃The component ratio is as follows: n is a radical of₂About 83% of CO₂About 16 percent, and the rest is other gases.

The flue gas after moisture removal enters CO₂A separation device 30 for separating CO contained therein₂Separating out CO in the gas after the separation process is finished₂The content of the nitrogen-containing gas reaches more than 95 percent, and all the gas which is not needed in the separation process is discharged.

For effectively separating N in flue gas₂And CO₂To doIn a preferred embodiment of the present invention, with reference to FIG. 1, the CO is described₂The separation device 30 is implemented as a first PSA separation device 31 and a second PSA separation device 32. Wherein the first PSA separating device is provided with a first exhaust 311 and the second PSA separating device is provided with a second exhaust 321, wherein the second PSA separating device 32 is located downstream of the first PSA separating device 31 and the operating pressure of the first PSA separating device 31 is less than the operating pressure of the second PSA separating device 32. The outlet of the second PSA separation device 32 and the CO₂The liquefaction and storage devices are connected.

Specifically, the first PSA separator 31 is responsible for directly treating the flue gas treated by the moisture remover 22, and at this time, CO in the flue gas₂Has low content of (A), low working pressure of a treatment device, and CO in the treated gas₂The content of the active carbon is improved to about 60 percent; the second PSA separation device 32 is used for treating the gas treated by the first PSA separation device 31, the working pressure of the treatment device is higher, and CO in the treated gas is₂The content is improved to about 95 percent.

Considering that the dehydrated smoke contains more N₂If operating at higher operating pressures, a large amount of energy is expended at N₂This is a useless component. Therefore, the first PSA separator 31 is energy-saving, and the working pressure is preferably 0.2Mpa to 0.6Mpa, such as 0.3Mpa, 0.4Mpa or 0.5 Mpa. The treatment process comprises the following steps: the dehumidified flue gas enters the first PSA separator 31, where the remaining undesired gases are discharged at the first exhaust 311 by the adsorption and separation action of the adsorbent therein. The main component in the exhaust gas is N₂. In the pursuit of equipment simplification and lower energy consumption, it is inevitable that the exhaust gas contains a part of CO₂As long as CO is present in the treated gas₂The content can reach about 60 percent, and CO in the exhaust gas₂The amount of the carbon dioxide accounts for the total CO in the smoke₂The total amount does not exceed 20%, so that the treatment method is very worthwhile. This discharge of a small portion of CO₂And does not discharge any CO at all₂Compared with the prior art, the energy consumption can be greatly reducedAnd the method is easier to realize in engineering, so that the popularization value of the carbon emission reduction system of the LNG power ship is improved. The adsorbent in the first PSA separator 31 is preferably implemented as an adsorbent that still performs a good adsorptive separation at lower pressures and may be implemented as a silica gel with coarse-pore microspheres coated with a 30% to 50% strength MDEA solution.

The gas after passing through the first PSA separation device 31 is treated with CO₂The content is already high and therefore the second PSA separation unit 32 can use a higher working pressure, which wastes relatively less energy. Preferably, the operating pressure of the second PSA separating device 32 is 0.3Mpa to 1.5 Mpa. The adsorbent in the second PSA separator 32 may be of a more conventional type such as zeolite, silica gel, activated carbon and activated alumina, with fine pore silica gel and 13X zeolite being preferred. The effluent gas is treated by the second PSA separation device 32 at P₅The component ratio of the point can reach more than 95%, and the rest of the unnecessary gas is discharged from the second gas outlet 321, and the main component in the discharged gas is still N₂Mainly comprises the following steps. Similarly, it is unavoidable that a part of CO is contained in the exhaust gas for the purpose of facility simplification and lower energy consumption₂As long as CO is present in the treated gas₂The content can reach about 95 percent, and CO in the exhaust gas₂The amount of the carbon dioxide accounts for the total CO in the smoke₂The total amount does not exceed 12%, such a treatment method is still worthwhile.

As another preferred embodiment of the present invention, in conjunction with FIG. 2, the CO is described₂The separation device 30 is implemented as a membrane separation device. Wherein the membrane separation device may be constituted by one-stage membrane separation device 33, or by two-stage membrane separation devices 33 and 34. Wherein each stage of the membrane separation device is provided with gas vents 331 and 341. The membrane separation unit consists of CO₂/N₂Separation membrane, said CO₂/N₂The selectivity of the separation membrane is more than 80, so that CO can be selected and separated out to a greater extent₂. Preferably, the membrane separation device consists of a membrane with a high CO content₂Permeability and CO₂/N₂Selective membrane materials, such as microporous polymer membranes. By using CO₂And N₂The difference in the permeability of the membrane structure achieves the purpose of better separation. The gas unnecessary for the separation process is entirely discharged through the gas discharge ports 331 and 341. The gas (i.e. P) treated by the one-stage or two-stage membrane separation device₅CO at a point₂Concentration) of the sodium hydroxide can reach about 95%. It is worth mentioning that when the membrane separation device is implemented as two membrane separation devices 33 and 34 connected in series, by means of a fractionation process, for example, CO is introduced in the first membrane separation device 33₂The ratio is raised to 40% -60% and then the CO is separated in a membrane separation unit 34₂The component ratio is further increased to about 95%, and unnecessary N is removed₂The components are discharged in time and the total energy consumption is lower and more convenient than possible by performing the separation by only one of the membrane separation devices 33.

Due to the existence of the membrane separation device to CO₂And N₂Problem of low separation accuracy, as another preferred embodiment of the present invention, with reference to FIG. 3, the CO is described₂The separation device 30 may also be implemented as a composite of a membrane separation device 33 and a PSA separation device 32. Wherein the membrane separation device 33 is provided with a gas outlet 331 and the PSA separation device is provided with a gas outlet 321. The membrane separation unit 33 is made of CO₂/N₂A separation membrane, and the CO₂/N₂The selectivity of the separation membrane is more than 80, so that CO can be selected and separated out to a greater extent₂. The membrane separation device 33 is responsible for directly treating the flue gas treated by the moisture removal device, and CO in the treated gas₂The content of the active carbon is improved to about 60 percent; the PSA separation device 32 is responsible for treating the gas treated by the membrane separation device 33, and CO in the treated gas₂The content is improved to about 95 percent.

In addition, it should be noted that in some cases, one skilled in the art would also readily conceive of passing the CO through more stages₂Separation apparatus 30, or various combinations of one or more of PSA separation apparatus 32 and membrane separation apparatus 33, for CO in flue gas₂Performing separation treatment to obtain CO with predetermined component ratio₂. As long as the classification processing idea of the invention is provided and the main point is in the processing processThe energy saving and feasibility of implementation are sought, and the equivalent alternative principles are also within the protection scope of the invention.

According to an embodiment of the invention, the CO is₂The liquefaction and storage device comprises a compressor 23, a second seawater cooler 24 and the CO which are connected in sequence₂Condenser 11 and liquid CO₂A storage tank 200. The CO is₂The separation device 30 is directly connected to said compressor 23, said compressor 23 being capable of passing said CO through₂The gas treated by the separator 30 is compressed to a pressure of about 1MPa (gauge pressure) and then discharged, and among them, 0.6MPa to 1MPa is preferable. This is a relatively low operating pressure and can save a lot of energy used on the compressor.

According to an embodiment of the invention, the compressor 23 is directly connected to the second seawater cooler 24. The second seawater cooler 24 is provided with a seawater inlet 241 and a seawater outlet 242 so as to lower the temperature of the gas compressed by the compressor 23 to a seawater temperature, i.e., about 35 c, by circulating heat exchange of seawater.

According to an embodiment of the present invention, the second seawater cooler 24 is cooled to enrich CO₂Into CO₂A condenser 11. The CO is₂Liquid CO of condenser 11₂An exhaust port 115 is also provided outside the outlet 114. For the CO₂The LNG fuel enters from an LNG inlet 111 and is rich in CO₂From gaseous CO₂Inlet 113 inflow of LNG fuel and rich CO₂The gas is fully exchanged with heat and is rich in CO₂The gas is only required to be cooled to about minus 60 ℃, wherein most CO₂Has been condensed to liquid CO₂Then through liquid CO₂The outlet 114 discharges the uncondensed gas through the discharge port 115, and the LNG is heated to become natural gas having a certain temperature and discharged through the natural gas outlet 112. In addition, CO₂The LNG fuel can also utilize an intermediate heat exchange medium for indirect heat exchange, the significance of the LNG fuel is consistent with that of the invention, and the LNG fuel and the intermediate heat exchange medium are also within the protection scope of the invention.

According to an embodiment of the invention, the condensed liquid CO₂Discharging the liquid CO₂A storage tank 200. Through theoretical calculations and system simulations, at P₆Dotted CO₂The recovery ratio of (A) can reach more than 65%, taking 500kgLNG as an example, the CO can be theoretically generated₂1375kg CO finally liquefied according to the above system and method₂Can reach about 900kg, which means that the carbon emission reduction ratio can further reach more than 65 percent on the basis of using the LNG fuel, and completely reaches the requirements of short-term and long-term carbon emission.

According to an embodiment of the invention, the liquid CO₂The storage tank 200 has heat insulation and cold insulation capability and can store liquid CO for a long time₂. The new liquid CO is continuously generated during the navigation process of the ship₂. These liquid CO₂Can be stored in liquid CO₂In the storage tank 200, after reaching a certain volume, the liquid CO is discharged through the discharge port 201 to the dedicated liquid CO₂Transport ship or shore-based liquid CO₂In a storage tank, and passing CO₂The transport ship is used for finally transporting and discharging CO transformed from the waste gas oil-gas well at the bottom of the ocean₂In a storage to reduce CO emission₂The final object of (1).

The invention also provides an LNG power ship carbon emission reduction method using the LNG power ship carbon emission reduction system, wherein the LNG power ship carbon emission reduction method comprises the following steps:

(a) by said CO₂The condenser 11 and the natural gas heater 12 heat the LNG fuel in a graded manner to meet the temperature required for combustion of the marine gas plant 13;

(b) cooling the flue gas generated after the combustion of the LNG fuel to the temperature of seawater, generally about 35 ℃;

(c) moisture in the cooled flue gas is removed by the moisture removal device 22;

(d) separating CO in the flue gas by a two-stage PSA separation device, a one-stage or two-stage membrane separation device or a combination of the membrane separation device and the PSA separation device₂。

(e) Compressing the CO₂Separating the gas treated by the device 30, wherein the pressure of the compressed gas is preferably 0.6 MPa-1 MPa;

(f) cooling the compressed gas to a seawater temperature, typically about 35 ℃;

(g) by said CO₂A condenser 11 for cooling the compressed gas by using the cold energy released from the LNG fuel to convert the gaseous CO into a gas₂Condensed into liquid, CO₂The vast majority of CO can be condensed to-65 ℃ to-60 DEG C₂Condensing into liquid state, and finally condensing into liquid CO₂The amount of the carbon dioxide accounts for the total CO in the smoke₂The total amount can reach more than 65 percent, so that the cold energy contained in the LNG fuel is fully utilized, a large amount of energy required in the carbon collection process is saved, and the uncondensed gas can be discharged through the exhaust port;

(h) by liquid CO₂Storage tank for storing liquid CO₂；

(i) After the liquid CO2 storage tank reaches a volume limit, the liquid CO is introduced₂Lightens to liquid CO₂Transporting the ship and transferring the liquid CO₂Transporting and finally discharging CO transformed from waste gas oil and gas well into ocean bottom₂In a storage.

Preferably, in the two-stage PSA separation device, the working pressure of the first-stage PSA separation is controlled to be 0.2MPa to 0.6MPa, and the working pressure of the second-stage PSA separation is controlled to be 0.3MPa to 1.5 MPa. The first-stage separation device adopts a method with lower working pressure, so that the waste in N can be effectively reduced₂Energy is supplied, and the energy consumption of the system is reduced; the second stage separation device is used for separating CO₂The content of the adsorbent is quite high, the working pressure is properly increased, a more common adsorbent can be used, the system cost is reduced, and the separation effect is improved.

Further preferably, the CO in the gas after the first stage PSA separation is controlled₂The component ratio of (A) is 40-60%, and CO in the gas discharged after the first-stage PSA separation is controlled₂In an amount corresponding to the amount of CO in said flue gas₂Not higher than 20% in total;

controlling CO in gas separated by second stage PSA₂The component ratio of (A) is 90-95%, and CO in the gas discharged after the second-stage PSA separation is controlled₂In an amount corresponding to the amount of CO in said flue gas₂Not higher than 12% in total;

during the separation process, the whole CO in the gas to be treated is not required to be pursued₂Are all separated out by CO relaxation₂Content standard, so that the discharged gas still can contain a small amount of CO₂By setting proper working parameters of the separation device, CO in the treated gas can be accurately controlled₂The content of (a) reduces the energy consumption in the separation process as much as possible; on the contrary, the processing method can save a large amount of energy by avoiding overhigh system working pressure and complicated separation flow caused by pursuing high separation rate.

Controlling the CO from₂CO in gas discharged from gas outlet of condenser and not condensed₂In an amount corresponding to the amount of CO in said flue gas₂The total amount of (A) is not higher than 3%. The absolute 100% liquefaction rate is not required to be obtained in the condensation process, and when the temperature is reduced to a proper temperature range of-65 ℃ to-60 ℃, most of CO gas is generated₂Condensing into liquid state can make full use of cold energy of LNG fuel to make more CO₂The LNG fuel is liquefied, and through calculation, the parameter setting can fully ensure that 65% of carbon in the LNG fuel is liquefied and recovered.

It should be noted that the terms "first, second and third" in the present invention are used for descriptive purposes only, do not denote any order, are not to be construed as indicating or implying any relative importance, and are to be interpreted as names.

It will be appreciated by persons skilled in the art that the embodiments of the invention described above and shown in the drawings are given by way of example only and are not limiting of the invention. The advantages of the present invention have been fully and effectively realized. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.