阅读说明：本技术 背压式热电厂耦合型供水系统 (Back pressure type thermal power plant coupling type water supply system ) 是由 蔡兴初 朱一鸣 梁涛 陈彬 郭悦 于 2021-05-28 设计创作，主要内容包括：本发明公开了背压式热电厂耦合型供水系统,在开式水供水系统的回水母管上增设支管,支管通过第一阀门与化学水箱的工业水进水主管联通,化学水箱的工业水进水主管分别通过化学水箱的工业水支路进水管与各化学水箱连接；工业水进水管通过第二阀门与化学水箱的工业水主进水管联通,第一机力塔水池补水管通过第四阀门与工业水进水管联通；增设第二机力塔水池补水管,其通过第三阀门与工业水主进水管联通,化学水箱设溢流管至机力塔水池。本发明将开式水供水系统和化学生水供水系统耦合,梯级使用冷热水,对工业水来水的余压储能利用,实现了节能的技术目的；对系统设备布设方式的改进,利用工业水来水的余压,产生较大的节能收益。(The invention discloses a back pressure type thermal power plant coupling type water supply system.A branch pipe is additionally arranged on a return water main pipe of an open water supply system, the branch pipe is communicated with an industrial water inlet main pipe of a chemical water tank through a first valve, and the industrial water inlet main pipe of the chemical water tank is respectively connected with each chemical water tank through an industrial water branch inlet pipe of the chemical water tank; the industrial water inlet pipe is communicated with an industrial water main inlet pipe of the chemical water tank through a second valve, and the water replenishing pipe of the first mechanical tower water tank is communicated with the industrial water inlet pipe through a fourth valve; and a second power tower water tank water supplementing pipe is additionally arranged and is communicated with the industrial water main water inlet pipe through a third valve, and the chemical water tank is provided with an overflow pipe to the power tower water tank. The open water supply system is coupled with the chemical raw water supply system, cold water and hot water are used in a gradient manner, and the excess pressure of the industrial water is stored and utilized, so that the technical purpose of energy conservation is realized; the improvement of the arrangement mode of system equipment utilizes the excess pressure of the industrial water to generate greater energy-saving benefit.)

1. The back pressure type thermal power plant coupling type water supply system is characterized by comprising an open water supply system and a chemical raw water supply system, wherein a branch pipe is additionally arranged on a return water main pipe of the open water supply system and is communicated with an industrial water inlet pipe of a chemical water tank through a first valve; an industrial water inlet pipe of the chemical water tank is communicated with a main industrial water inlet pipe through a second valve, and a water replenishing pipe of a first mechanical tower water tank is communicated with the main industrial water inlet pipe through a fourth valve; and a second power tower water tank water replenishing pipe is additionally arranged, the second power tower water tank water replenishing pipe is communicated with the industrial water main water inlet pipe through a third valve, and the chemical water tank is provided with an overflow pipe to the power tower water tank.

2. The back-pressure thermal power plant coupled water supply system of claim 1, wherein the system is operated as follows: when the temperature of the industrial water is lower than a set threshold value, the open water system adopts the direct current supply of the industrial water, the open water after heat exchange is used for supplying chemical raw water, the second valve and the water inlet valve of the mechanical tower are closed at the moment, and other valves are fully opened.

3. The back-pressure thermal power plant coupled water supply system of claim 1, wherein the system is operated as follows: when the temperature of the industrial water is higher than a set threshold value, the open water system adopts a circulating water supply mode with a mechanical tower, the industrial water directly supplies chemical raw water, the first valve and the fourth valve are closed at the moment, and other valves are fully opened.

4. The back-pressure thermal power plant coupled water supply system of claim 1, wherein the system is operated as follows: when industry water temperature is less than the settlement threshold value, if chemical raw water demand is little than open water supply volume to when the difference is greater than the settlement threshold value between, open water system adopts the circulation water supply mode of taking the mechanical tower, and through the open circulating water system moisturizing volume of increase, with the open water after the heat transfer is supplemented to chemical water tank to the mode of bypass, concrete operation is: the balance between the water volume of the students and the water volume of the mechanical power returning tower is adjusted to maintain the stable operation of the system by adjusting the opening of the industrial water inlet valve of the chemical water tank, at the moment, the second valve is closed, and other valves are fully opened.

5. The back-pressure thermal power plant coupled water supply system as claimed in claim 1, wherein the added second power tower basin make-up water pipe has a pipe diameter larger than that of the first power tower basin make-up water pipe.

6. The back-pressure thermal power plant coupled water supply system of claim 1, wherein a power tower basin is elevated a set height.

7. The back-pressure thermal power plant coupled water supply system of claim 1, wherein a capacity-increasing pylon pond.

8. The back-pressure thermal power plant coupled water supply system of claim 1, wherein the open water supply system circulating water intake forebay and the semi-underground circulating pump house are eliminated, and the auxiliary cooling circulating water pump is disposed below the power tower water bay.

9. The back-pressure thermal power plant coupled water supply system as claimed in claim 1, wherein the added tower basin make-up water pipe is increased in pipe diameter to be able to deliver the water for direct flow water supply.

10. The back-pressure thermal power plant coupled water supply system of claim 1, wherein an industrial water backup lift pump is added to the industrial water intake bypass.

Technical Field

The invention relates to a back pressure type thermal power plant coupling type water supply system, and belongs to the field of design of thermal power plant water supply systems.

Background

Due to the huge difference in water amount and different requirements on water quality, a cooling water system and a chemical raw water supply system of a thermal power plant are generally two sets of independent systems. The back pressure type thermal power plant is not provided with a main engine cooling water system, and is only provided with an auxiliary engine cooling water system. The large-scale backpressure unit heat supply is great, and its chemical student's water demand is similar with the auxiliary engine cooling water yield, but both have different requirements to the temperature: (1) the open water inlet of the auxiliary machine needs low-temperature water, and the outlet water is hot (warm) water after heat exchange; (2) when the ultrafiltration-reverse osmosis membrane method is adopted for desalting water, the chemical raw water needs to have certain water temperature: the water temperature has influence on both the water yield and the water quality of the reverse osmosis device, and the water yield flux is approximately increased by 3% when the water temperature rises by 1 ℃ under the condition that the system condition is not changed; when the temperature is lowered, the water production needs to be increased by increasing the operating pressure. Considering the temperature bearing capacity and the service life of the membrane material, the maximum designed water temperature of the chemical raw water is not more than 30 ℃, and the optimal designed water temperature is about 25 ℃. Reverse osmosis processes generally consider feedwater heating measures. The water supply flow before the ultrafiltration reverse osmosis device is as follows: chemical raw water → raw water heater → hyperfiltration reverse osmosis device.

A certain project A is located in a large petrochemical industry base in Jiangsu province, and in order to meet the heat supply requirement of the industry base, a 9 x 800t/h circulating fluidized bed boiler is planned to be built, and a 9 x 35 MW-grade back pressure type steam turbine generator unit is configured. A steam turbine (main engine) -free circulating cooling water system for a whole plant is provided with an auxiliary engine cooling open water (hereinafter referred to as open water) system for cooling closed cooling water (see figure 3) of auxiliary engines of the whole plant, and the open water amount designed for the whole plant is 7500m³The temperature difference between inlet and outlet water is designed to be 5 ℃. The number of hours of unit design year operation is 8000h, the rated working condition heat supply is 4200t/h, and the chemical raw water requirement is about 5600m³And h, desalting water by adopting an ultrafiltration-reverse osmosis membrane method.

The project A water supply system has the following characteristics: the water quality of the open water and the chemical raw water is the same, and the open water and the chemical raw water are both purified industrial water provided by a park. Secondly, the chemical raw water amount under the rated heat supply working condition is equal to 75% of the open water amount, the chemical raw water amount and the open water amount are relatively close, and the 75% of the open water amount can meet the cooling requirement of the auxiliary machine under the working condition of cold seasons. And thirdly, the open water needs low-temperature water, while the temperature of the chemical raw water is not too low. Fourthly, the water pressure of the incoming industrial water is not less than 0.18MPa in the factory, and considerable residual pressure can be used.

Therefore, how to couple the open water supply system and the chemical raw water supply system to realize energy conservation and further how to realize the utilization of the excess pressure of the industrial water is a technical problem to be solved.

Disclosure of Invention

The invention aims to couple the open water supply system and the chemical raw water supply system to realize energy conservation. In order to achieve the technical purpose, the invention provides a back pressure type thermal power plant coupling type water supply system which comprises an open water supply system and a chemical raw water supply system, wherein a branch pipe is additionally arranged on a return water main pipe of the open water supply system and is communicated with an industrial water inlet pipe of a chemical water tank through a first valve; a water replenishing pipe (small caliber) of the first power tower water tank is communicated with a main industrial water inlet pipe through a fourth valve; and a second power tower water tank water replenishing pipe with a large diameter is additionally arranged, the second power tower water tank water replenishing pipe is communicated with the industrial water main water inlet pipe through a third valve, and the chemical water tank is provided with an overflow pipe to the power tower water tank.

Further, the operation method of the system is as follows: when the temperature of the industrial water is lower than a set threshold value, the open water system adopts the direct current supply of the industrial water, the open water after heat exchange is used for supplying chemical raw water, the second valve and the water inlet valve of the mechanical tower are closed at the moment, and other valves are fully opened.

Further, the operation method of the system is as follows: when the temperature of the industrial water is higher than a set threshold value, the open water system adopts a circulating water supply mode with a mechanical tower, the industrial water directly supplies chemical raw water, the first valve and the third valve are closed at the moment, and other valves are fully opened.

Further, the operation method of the system is as follows: if the chemical raw water requirement is smaller than the open water supply quantity and the difference value is larger than a set threshold value, the open water system adopts a circulating water supply mode with a mechanical tower. In cold seasons, open water after heat exchange is supplemented to the chemical water tank in a bypass flow mode by increasing the water supplementing amount of the open circulating water system. The specific operation can maintain the stable operation of the system by adjusting the opening of an industrial water inlet valve of the chemical water tank and adjusting the balance of the water volume of the students and the water volume of the mechanical power tower.

Further, the power tower water pool is lifted to a set height.

And further, increasing the capacity of the power tower water pool.

Furthermore, an open water supply system circulating water inlet forebay and a semi-underground circulating pump room are eliminated, and an auxiliary machine cooling circulating water pump is arranged below the power tower water pool.

Further, the chemical water tank is set as a steel water tank.

The invention has the following beneficial technical effects:

the invention couples the open water supply system with the chemical raw water supply system, uses cold and hot water in a gradient way, and stores and utilizes the residual pressure of the industrial water. The energy-saving open water supply system with direct current and circulation functions is designed, and the technical purpose of energy conservation is achieved.

Through the cascade use of cold and hot water and the improvement of the arrangement mode of system equipment, the excess pressure of the industrial water is utilized to generate greater energy-saving benefit.

Drawings

FIG. 1 is a schematic of a conventional open water supply system;

FIG. 2 is an elevation schematic view of a conventional open water supply system;

FIG. 3 is a schematic diagram of auxiliary cooling water-water heat exchange;

FIG. 4 is a schematic view of a conventional chemical raw water supply system;

FIG. 5 is a schematic elevation view of a conventional chemical raw water supply system;

FIG. 6 is a schematic diagram of a coupled water supply system according to an embodiment of the present invention;

FIG. 7 is an elevation view of a coupled water supply system according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of a mechanical tower and pump arrangement of a coupled water supply system according to an embodiment of the present invention;

FIG. 9 is a schematic flow chart of an open water DC water supply system for delivery period according to an embodiment of the present invention;

FIG. 10 is a schematic view of the process of the open water circulation system for delivery of an embodiment of the present invention;

FIG. 11 is a schematic flow diagram of an open-cycle water supply system during a transition period of production according to an embodiment of the present invention; the labels in the figure are: 1: a backwater main pipe; 2: a branch pipe; 3, overflow pipe; 4: an industrial water branch inlet pipe of the chemical water tank; 5: an industrial water inlet pipe of the chemical water tank; 6: a main water inlet pipe for industrial water; 7: a second power tower water pool water replenishing pipe; 8: a first valve; 9: a second valve; 10: a third valve; 11: a chemical water tank; 12: a water inlet valve of the mechanical tower; 13: an industrial water inlet valve of the chemical water tank; 14: a fourth valve; 15: the first power tower water pool water replenishing pipe.

Detailed Description

The invention is further described below with reference to the figures and the specific examples.

Example 1: as shown in fig. 6, the back pressure type thermal power plant coupling water supply system comprises an open water supply system and a chemical raw water supply system, wherein a branch pipe 2 is additionally arranged on a return water main pipe 1 of the open water supply system, the branch pipe 2 is communicated 5 with an industrial water inlet pipe of a chemical water tank through a first valve 8, the industrial water inlet pipe 5 of the chemical water tank is respectively connected with each chemical water tank through an industrial water branch inlet pipe 4 of the chemical water tank, and the industrial water branch inlet pipe 4 of the chemical water tank is provided with an industrial water inlet valve 13 of the chemical water tank; the industrial water inlet pipe 5 of the chemical water tank is communicated with the main industrial water inlet pipe 6 through a second valve 9, and the water replenishing pipe 15 of the first power tower water tank is communicated with the main industrial water inlet pipe 6 through a fourth valve 14; and a second power tower water tank water supplementing pipe 7 is additionally arranged, the second power tower water tank water supplementing pipe 7 is communicated with a main industrial water inlet pipe 6 through a third valve 10, and an overflow pipe 3 is arranged on the chemical water tank 11 to reach the power tower water tank.

In this embodiment, the open water supply system and the chemical raw water supply system are independently provided. The open water supply system flow is as follows:

industrial water → power tower water pool → circulating water pump → auxiliary machine heat exchanger → power tower

The chemical raw water supply system comprises the following processes:

industrial water supply → chemical water pool → chemical raw water pump → raw water heater →

Ultrafiltration reverse osmosis device

The open water system is provided with a 4 multiplied by 33.3 percent auxiliary machine cooling circulating water pump (hereinafter referred to as a circulating pump), a 3 multiplied by 40 percent mechanical ventilation cooling tower (hereinafter referred to as a mechanical tower), a water supply and return main pipe, a water inlet forebay and a semi-underground circulating water pump room, wherein the pipe diameter of the water supply and return main pipe is DN 1200.

Chemical water supply system configuration 2 seats 5000m³The chemical water pool is of a reinforced concrete structure, the height of the chemical water pool is 4m, the chemical water pool is arranged semi-underground, and a semi-underground type raw water pump house is arranged. A power tower, a chemical water basin, etc. are arranged adjacently.

The mechanical tower, the circulating pump, the chemical water pool, the raw water pump and the like are all arranged in the water service area. The open water supply system and the elevation schematic diagram are shown in a figure 1 and a figure 2, the chemical raw water supply system and the elevation schematic diagram are shown in a figure 4 and a figure 5, and the main equipment parameters are shown in a table 1.

Table 1 independent water supply system main equipment parameter table

In this embodiment, the pipe diameter of the water replenishing pipe 7 of the second power tower water tank is DN1000, and by enlarging the pipe diameter of the water replenishing pipe entering the power tower water tank, a large amount of industrial water can enter the power tower water tank, and the amount of the industrial water is equal to the amount of the cooling open type cooling water of the auxiliary machine. And a bypass pipeline and a valve are arranged on the open water return pipeline of the auxiliary machine. The open water after heat exchange can enter the water melting tank before entering the mechanical tower.

The industrial water branch inlet pipe 4 of the water melting tank 11 is low-level inlet water, and a return valve, namely an industrial water inlet valve 13 of the water melting tank, is arranged. The water melting tank is provided with an overflow pipe 3 to the mechanical tower. By providing the overflow pipe 3, the imbalance between the supply amount of the circulating water and the chemical water demand is prevented, if the circulating water amount is larger than the chemical water demand.

By arranging the bypass pipeline and the valve on the auxiliary machine cooling open type water return pipeline, namely the return main pipe 1, the auxiliary machine cooling open type water after heat exchange can enter the chemical water tank before entering the mechanical tower.

Example 2: the operation method of the back-pressure thermal power plant coupling type water supply system provided in embodiment 1 includes:

firstly, when the temperature of industrial water is lower (lower than a set threshold), an open water system adopts a direct-current water supply mode, and the open water after heat exchange is used for supplying chemical raw water; at this time, the second valve Vb (i.e. the second valve 9) and the water inlet valve 12 of the mechanical tower (i.e. the valve of the return water main pipe of the open water supply system connected to the mechanical tower) are closed (see fig. 6, the same below), and the other valves are fully opened. The flow of the open water direct-current water supply system in term of delivery is shown in fig. 9:

when the temperature of the industrial water is higher (higher than a set threshold), the water supply system is switched to an independent water supply system, namely: the open water system adopts a circulating water supply mode with a mechanical tower, and industrial water is directly supplied to the chemical water tank; at this time, the first valve Va (i.e., the first valve 8) and the third valve Vc (i.e., the third valve 10) are closed, and the other valves are fully opened. The flow of the open water circulation water supply system in term of delivery is shown in figure 10:

and thirdly, if the chemical raw water demand is far less than the open water supply amount, and the matching is difficult, the open water system adopts a circulating water supply mode with a mechanical tower. At this point, valve Vb (i.e., second valve 9) is closed and the other valves are fully open. In cold seasons, open water after heat exchange can be supplemented to the chemical water tank in a bypass flow mode by increasing the water supplementing amount of the circulating water system. The specific operation can maintain the stable operation of the system by adjusting the opening degree of a water inlet valve of the chemical water tank and adjusting the balance of the water quantity of the chemical students and the water quantity of the mechanical power tower. The flow of the open-cycle water supply system in the transition period of production reaching is shown in fig. 11:

because the water temperature at the inlet of the ultrafiltration reverse osmosis device is not more than 30 ℃, a circulating cooling water system with a mechanical tower is adopted in hot seasons (such as summer), and a direct-current water supply system can be switched in other seasons.

Implementation 3: on the basis of the above embodiment, in order to realize the utilization of the excess pressure of the industrial water, the coupling type water supply system of the back pressure type thermal power plant can be optionally modified by at least one of the following improvements:

the excess pressure of the industrial water is converted into potential energy by means of lifting a water storage structure and the like, and is optionally used for 15m in a specific embodiment.

The water level of the elevating power tower water pool is optionally designed to be 15m in the specific embodiment. The excess pressure of the industrial water is converted into potential energy for energy storage by raising the designed water level in the water storage structure and matching with the high water level of the steel chemical water tank, so that the excess pressure of the industrial water is utilized.

The water pool of the capacity increasing power tower, optionally in the specific embodiment, under the condition of plane size determination (L multiplied by B =48m multiplied by 19 m), the effective water depth is properly increased to 4m, and the effective volume is about 3600m³The power tower water tank has the function of regulating and storing industrial water outside the plant;

the circulating water inlet forebay and the semi-underground circulating pump room are eliminated, and the circulating pump is arranged in the water of the mechanical tower

Below the cell (as shown in fig. 8).

The chemical water tank with the reinforced concrete structure is changed into a steel water tank, namely a chemical water tank, optionally, in the specific embodiment, the diameter of the chemical water tank is 21m, the designed water level of the water tank is 15m, the height of the water tank is 19m, the ground is arranged, the corresponding chemical water pump room is also changed into the ground from the semi-underground arrangement, namely, the chemical raw water pump is arranged on the ground, and the pump room has no substructure.

Alternatively, the chemical water tank is a steel water tank, and the effective volume of the chemical water tank is about 2 hours of the water demand of the students. Short-term fluctuations in the chemical raw water demand may occur during operation, which will not match the open water supply and the excess open water needs to be spilled from the chemical water tank back to the power tower sump. Considering the requirement of the overflow water head difference, the overflow water level is set to be 18m, the actual height of the water tank is determined to be 19m, and the diameter of the water tank is determined to be 21 m.

The chemical water tank adopts the steel water tank, and the chemical raw water demand fluctuation in short time probably appears in the operation, will not match with open water supply volume, and excessive open water need overflow from the chemical water tank and return to the power tower pond.

Considering the possible working condition that the pressure of the incoming industrial water is insufficient, a bypass is arranged on a water pipeline of the industrial water entering the mechanical tower (chemical water tank), and a 2 multiplied by 50% lifting water pump is installed as a standby measure.

When the pressure of the incoming water of the off-site industrial water is less than 15m, the standby lifting water pump is automatically started through a pressure switch arranged on the pipeline and runs in a constant-pressure variable-frequency mode according to the pressure of 16m at the outlet of the pump; when the pressure of the incoming water of the off-plant industrial water is more than 15m, the lifting water pump automatically stops pumping.

In this embodiment, both the auxiliary cooling circulating water pump and the lifting water pump are arranged in the lower space of the power tower water tank, and an enclosure structure is arranged. The arrangement scheme saves a circulating water pump room forebay and corresponding equipment in the common design while reducing the occupied area.

The power tower pool also has the function of regulating and storing industrial water outside the plant, and the effective volume is properly increased.

The invention/utility model achieves the following beneficial effects:

taking project A as an example, according to the calculated working condition of the up-to-date, the energy-saving benefit is greater through the gradient use of cold and hot water and the excess pressure of the water coming from the industrial water.

(1) Energy storage (utilization of excess pressure of industrial water)

The water consumption of industrial water is about 5600m³And h, designing and utilizing the residual pressure of industrial water to be 15 m. The power of a motor matched with the raw water pump is reduced by about 290kW, the electricity consumption is saved by about 232 ten thousand kWh all the year (12 months), and the electricity cost is saved by 110 ten thousand yuan every year according to the power price of 0.475 yuan/kWh on the internet.

(2) Power saving

The mechanical tower does not operate under the working condition of direct-current water supply. The power consumption of the fan is saved by about 141 ten thousand kWh (according to the power of a fan nameplate) all the year by operating 2 power towers and operating 5333h all the year (8 months).

Secondly, the open water does not run on the mechanical tower under the direct current working condition, the pump lift is reduced by 10m, and the power consumption is saved by about 103 thousands kWh under the direct current working condition (8 months).

(3) Saving steam

The chemical raw water is supplied after the auxiliary machine circulating water is backwashed, the heating steam consumption of the chemical raw water can be reduced by 68t/h (steam parameters for heating are P =0.6MPa and t =180 ℃), the steam quantity is saved by about 363 ten thousand t in the whole year (8 months), the standard coal is reduced by 37.4 ten thousand t, and the annual fuel cost is saved by 2992 thousand yuan according to the standard coal price of 800 yuan/t.

(4) Water saving

The direct current supplies water the operating mode, the open water does not go on the mechanical tower, there is no evaporation of mechanical tower, wind blows and blowdown water loss. The water saving amount is about 60m according to the calculation working condition of the average dry bulb temperature of 9 ℃ under the direct current working condition (8 months)³H, water saving of about 32 ten thousand meters all year round³And the annual water cost is saved by about 64 ten thousand yuan in terms of the industrial water price of 2 yuan.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, many modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.