CN110631318A - Power plant circulating water cooling system - Google Patents

Abstract

The invention discloses a circulating water cooling system of a power plant, comprising: a circulating water system and an ammonia refrigeration system, the former includes a condenser, a water collection tank, a circulating water pump, a cooling tower, a water distribution tank and pipes connecting them, and the latter includes an evaporator , compressor, condenser, liquid storage tank, expansion valve and pipes connecting them (the pipes are filled with liquid ammonia), wherein the evaporator is set on the outlet pipe of the cooling tower, and the outlet of the compressor and the ammonia inlet of the evaporator The ammonia outlet of the evaporator is connected to the inlet of the compressor, and the condenser, liquid storage tank and expansion valve are sequentially arranged on the ammonia inlet pipe of the evaporator along the flow direction of liquid ammonia. The benefit of the present invention is that an ammonia refrigeration system is added on the basis of the circulating water system, and the cooling circulating water flowing out of the cooling tower is further cooled by the ammonia refrigeration system, so that the temperature of the cooling water coming out of the tower is lowered, In turn, the efficiency of medium and high pressure units can be improved.

Description

Power plant circulating water cooling system

technical field

The invention relates to a cooling system, in particular to a power plant circulating water cooling system, and belongs to the technical field of power plant cooling.

Background technique

In the construction of thermal power plants, circulating water cooling system is essential. The existing circulating water cooling system of the power plant is mainly composed of a condenser, a water header tank, a circulating water pump, a cooling tower, a water distribution tank and the pipes connecting them. The structure is shown in Figure 1. Among them, the cooling tower is the key structure of the circulating water cooling system.

The cooling performance of the cooling tower directly affects the economy of thermal power plant operation. The improvement of the thermal efficiency of the power plant is proportional to the decrease of the temperature of the cooling water exiting the tower. When the temperature of the cooling water exiting the tower drops by 1°C, the efficiency of the medium and high pressure units can be increased respectively. 0.47%, 0.35%.

Therefore, how to lower the outlet temperature of cooling water is very important for thermal power plants.

And existing cooling tower adopts natural ventilation to cool down, and in hot summer, air temperature is high, and cooling effect is difficult to guarantee.

In addition, the current power plant circulation cooling tower adopts an open structure. On the one hand, it causes evaporation loss of fresh cooling water. On the other hand, the cooling water of the open cooling tower is directly in contact with the atmosphere, which easily brings a large amount of impurities in the air into the circulation system. As a result, pipeline corrosion and scaling are serious, and a large amount of scale inhibitors, corrosion inhibitors and other chemical agents have to be added, which is not economical and will cause secondary pollution.

Contents of the invention

The first object of the present invention is to provide a power plant circulating water cooling system capable of lowering the tower temperature of the cooling water.

The second object of the present invention is to provide a fully enclosed circulating water cooling system, which can not only ensure the efficient operation of circulating water, but also reduce the consumption of water resources.

In order to achieve the above object, the present invention adopts the following technical solutions:

A circulating water cooling system for a power plant, comprising: a circulating water system, the aforementioned circulating water system comprising: a condenser, a water header tank, a circulating water pump, a cooling tower, a water distribution tank and pipes connecting them, wherein the condenser is used to cool the steam turbine to perform work After exhaust steam, the circulating water outlet of the condenser is connected to the circulating water inlet of the cooling tower, and the circulating water outlet of the cooling tower is connected to the circulating water inlet of the condenser. On the water inlet pipe, the water distribution tank is arranged on the outlet pipe of the cooling tower. It is characterized in that the circulating water cooling system of the power plant also includes an ammonia refrigeration system. The ammonia refrigeration system includes: an evaporator, a compressor, a condenser, a liquid storage tank, an expansion Valves and pipes connecting them filled with liquid ammonia, wherein:

The aforementioned evaporator is arranged on the outlet pipe of the cooling tower;

The outlet of the aforementioned compressor is connected with the ammonia inlet of the evaporator, and the ammonia outlet of the evaporator is connected with the inlet of the compressor;

The aforementioned condenser, liquid storage tank and expansion valve are sequentially arranged on the ammonia inlet pipe of the evaporator along the flow direction of liquid ammonia.

The aforementioned power plant circulating water cooling system is characterized in that the aforementioned power plant circulating water cooling system also includes a temperature monitoring and control system, and the aforementioned temperature monitoring and control system is arranged on the outlet pipe of the cooling tower, between the evaporator and the cooling tower, and Signal connection to compressor and expansion valve.

The aforementioned circulating water cooling system of the power plant is characterized in that, the aforementioned cooling tower is provided with a water eliminator, a spray device, a filler and a sump sequentially from top to bottom, wherein the water inlet of the aforementioned spray device and the water inlet pipe of the cooling tower The end of the pool is connected, and the water outlet of the sump is connected to the head end of the outlet pipe of the cooling tower; or, the aforementioned cooling tower is provided with multiple coils and multiple grooves with plate fins, wherein each groove with plate fins Set vertically, all slotted plate fins are arranged evenly along the horizontal direction, each coil is formed by connecting multiple S-shaped bends end to end, and these S-shaped bends are located in the same vertical plane, all coils The tubes are evenly arranged in the horizontal direction and connected through branch pipes. The vertical plane where the coil is located is perpendicular to the vertical plane where the slotted plate fins are located. There are holes for the coil to pass through the slotted plate fins. Embedded in the slotted plate fins, the water inlet and outlet of the coil are respectively connected to the end of the cooling tower water inlet pipe and the head end of the cooling tower water outlet pipe.

The aforementioned circulating water cooling system of the power plant is characterized in that the aforementioned evaporator is a semi-welded plate evaporator.

The aforementioned power plant circulating water cooling system is characterized in that the cooling water outlet of the aforementioned compressor is connected to the water header tank.

The aforementioned power plant circulating water cooling system is characterized in that the cooling water inlet of the aforementioned condenser is connected to the water distribution tank, and the cooling water outlet is connected to the water collection tank.

The aforementioned power plant circulating water cooling system is characterized in that the aforementioned water collection tank is provided with other water inlets.

The aforementioned power plant circulating water cooling system is characterized in that regulating valves are provided between the aforementioned condenser and the header tank, and between the aforementioned condenser and the water distribution tank.

The benefits of the present invention are:

(1) An ammonia refrigeration system is added on the basis of the circulating water system, and the ammonia refrigeration system further cools the cooling circulating water flowing out of the cooling tower, so that the temperature of the cooling water coming out of the tower can be lowered, thereby improving the medium and high temperature. Efficiency of the high pressure unit;

(2) A temperature monitoring and control system is installed on the outlet pipe of the cooling tower. The temperature monitoring and control system can monitor the outlet water temperature of the cooling tower and regulate the ammonia refrigeration system according to the monitoring results, which can effectively save costs and maximize benefits;

(3) The closed cooling tower is adopted, so that the circulating water system forms a completely closed circulating loop, which not only avoids the evaporation loss of fresh water, reduces the loss of circulating water, but also prevents impurities in the atmosphere from being brought into the circulating water In the system, the input of chemical agents such as scale inhibitors and corrosion inhibitors is further reduced, thereby saving costs and reducing secondary pollution, which has extensive economic and practical values.

Description of drawings

Figure 1 is a schematic diagram of the composition and structure of the existing circulating water cooling system of the power plant;

Fig. 2 is the composition structure schematic diagram of the first specific embodiment of the power plant circulating water cooling system provided by the present invention;

Fig. 3 is the composition structure schematic diagram of the second specific embodiment of the power plant circulating water cooling system provided by the present invention;

Fig. 4 is a partially enlarged schematic diagram of the slotted plate fin and the coiled pipe in Fig. 3;

FIG. 5 is a right side view of the slotted plate fin and coil in FIG. 4 .

Meanings of reference signs in the figure:

1-steam turbine, 2-condenser, 3-collection tank, 4-circulating water pump, 5-cooling tower, 6-water distribution tank, 7-evaporator, 8-compressor, 9-condenser, 10-liquid storage tank , 11-expansion valve, 12-temperature monitoring and control system;

501-water eliminator, 502-spray device, 503-filler, 504-collection tank;

511-coil, 512-slot with plate fins.

Detailed ways

The present invention will be specifically introduced below in conjunction with the accompanying drawings and specific embodiments.

Example 1

The power plant circulating water cooling system provided by the invention includes: a circulating water system, an ammonia refrigeration system and a temperature monitoring and control system.

Referring to Fig. 2, the circulating water system includes: a condenser 2, a water collecting tank 3, a circulating water pump 4, a cooling tower 5, a water distribution tank 6 and pipes connecting them. Among them, the condenser 2 is used to cool the exhaust steam after the work of the steam turbine 1, the circulating water outlet of the condenser 2 is connected with the circulating water inlet of the cooling tower 5, and the circulating water outlet of the cooling tower 5 is connected with the circulating water of the condenser 2 The inlet is connected, the water collection tank 3 and the circulating water pump 4 are sequentially arranged on the water inlet pipe of the cooling tower along the water flow direction, and the water distribution tank 6 is arranged on the outlet pipe of the cooling tower.

The cooling tower 5 adopts an open cooling tower, and the cooling tower 5 is provided with a water collector 501, a spray device 502, a filler 503 and a sump 504 in order from top to bottom, wherein the water inlet of the spray device 502 is connected with the cooling tower. The ends of the water pipes are connected, and the water outlet of the sump 504 is connected with the head end of the water outlet pipe of the cooling tower.

As a preferred solution, regulating valves are provided between the condenser 2 and the header tank 3 and between the condenser 2 and the water distribution tank 6 .

Referring to Fig. 2, the ammonia refrigeration system includes: an evaporator 7, a compressor 8, a condenser 9, a liquid storage tank 10, an expansion valve 11 and pipes connecting them, and the pipes are filled with liquid ammonia. Wherein, the evaporator 7 is arranged on the water outlet pipe of the cooling tower, the outlet of the compressor 8 is connected with the ammonia inlet of the evaporator 7, the ammonia outlet of the evaporator 7 is connected with the inlet of the compressor 8, the condenser 9, the liquid storage tank 10 and expansion valve 11 are sequentially arranged on the ammonia inlet pipe of the evaporator along the flow direction of liquid ammonia. The evaporator 7 provides a place for the cold and heat exchange of circulating water and liquid ammonia.

As a preferred solution, the evaporator 7 is a semi-welded plate evaporator, which can effectively use liquid ammonia to absorb the heat in the circulating water into the ammonia refrigeration system.

As a preferred solution, the cooling water outlet of the compressor 8 is connected to the water collection tank 3 .

The cooling of the overheated gas ammonia after compression in the condenser 9 adopts a water cooling method. As a preferred solution, the cooling water inlet of the condenser 9 is connected with the water distribution tank 6, and the cooling water outlet is connected with the water collection tank 3, that is, the condenser 9 The cooling water source is the water distribution tank 6, and the cooling water flows into the water collection tank 3 after exchanging heat with superheated gas ammonia in the condenser 9 and waits for cooling.

As a preferred solution, other water inlets are also arranged on the water collection tank 3 . The hot water to be cooled in the header tank 3 comes from the cooling water of the steam turbine 1 , the compressor 8 , the condenser 9 and other cooling water flowing in through other water inlets.

Referring to FIG. 2 , the temperature monitoring and control system 12 is set on the outlet pipe of the cooling tower, between the evaporator 7 and the cooling tower 5 , and is connected with the compressor 8 and the expansion valve 11 for signals. The temperature monitoring and control system 12 monitors the outlet water temperature of the cooling tower, and regulates the ammonia refrigeration system according to the monitoring results, specifically:

(1) When the outlet water temperature of the cooling tower is higher than the inlet water temperature requirement of the condenser 2, the temperature monitoring and control system 12 automatically turns on the ammonia refrigeration system by controlling the compressor 8 (open) and the expansion valve 11 (open) of the ammonia refrigeration system In the process, the circulating water in the outlet pipe of the cooling tower is further cooled by the ammonia refrigeration system, so that the outlet water temperature of the cooling tower reaches the water inlet temperature requirement of the condenser 2;

(2) When the outlet water temperature of the cooling tower reaches the water inlet temperature requirement of the condenser 2, the temperature monitoring and control system 12 automatically shuts down the ammonia refrigeration process by controlling the compressor 8 (closed) and the expansion valve 11 (closed) of the ammonia refrigeration system , to reduce losses.

It can be seen that adding the temperature monitoring and control system 12 can effectively save costs and maximize benefits.

When in use, the cooling water exchanges heat with the exhaust steam that drives the steam turbine 1 to perform work in the condenser 2. After the heat exchange, the water temperature rises and flows into the water collection tank 3. After being pressurized by the circulating water pump 4, it enters the cooling tower 5. , use the natural convection of air for the first cooling, the cooling water enters the sump 504 under the action of gravity, and the circulating water cooled by the cooling tower 5 exchanges heat with liquid ammonia in the evaporator 7 to realize the second cooling, which is The cooled water enters the water distribution tank 6, and then enters the condenser 2 to exchange heat with the exhaust steam, and then flows into the water collection tank 3, so that the circulation ensures the normal operation of the condenser 2; the liquid ammonia exchanges with the circulating water in the evaporator 7 After heating, it evaporates into gas ammonia due to temperature rise and pressure reduction, and gas ammonia is compressed into superheated gas ammonia through compressor 8, and superheated gas ammonia becomes saturated liquid ammonia after being cooled and condensed in condenser 9, and the cooled gas ammonia is The liquefied ammonia enters the liquid storage tank 10 for storage for later use. The pressure and temperature of the liquefied ammonia in the liquid storage tank 10 are reduced after the expansion valve 11 is adiabatically throttled and expanded, and the liquefied ammonia that is both lowered in pressure and temperature enters the evaporator 7 again to meet the needs. The cooled water performs heat exchange, and the ammonia evaporated from the heat exchange enters the reciprocating cycle in the compressor 8 again, thereby realizing the purpose of cooling the cooling water by using the ammonia refrigeration cycle; at the same time, the temperature monitoring and control system installed on the outlet pipe of the cooling tower 12 Monitor the outlet water temperature of the cooling tower, and adjust the ammonia refrigeration system according to the monitoring results. If the outlet water temperature of the cooling tower reaches the water inlet temperature requirement of the condenser 2, the ammonia refrigeration process will be automatically closed to reduce losses, otherwise, the ammonia refrigeration system will be automatically regulated The cooling capacity of the process is to make the outlet water temperature of the cooling tower meet the inlet water temperature requirement of condenser 2.

Example 2

The power plant circulating water cooling system provided by the invention includes: a circulating water system, an ammonia refrigeration system and a temperature monitoring and control system.

Referring to Fig. 3, the circulating water system includes: a condenser 2, a water collection tank 3, a circulating water pump 4, a cooling tower 5, a water distribution tank 6 and pipes connecting them. Among them, the condenser 2 is used to cool the exhaust steam after the work of the steam turbine 1, the circulating water outlet of the condenser 2 is connected with the circulating water inlet of the cooling tower 5, and the circulating water outlet of the cooling tower 5 is connected with the circulating water of the condenser 2 The inlet is connected, the water collection tank 3 and the circulating water pump 4 are sequentially arranged on the water inlet pipe of the cooling tower along the water flow direction, and the water distribution tank 6 is arranged on the outlet pipe of the cooling tower.

The cooling tower 5 adopts a closed cooling tower, and the cooling tower 5 is provided with a plurality of coil pipes 511 and a plurality of grooves with plate fins 512, wherein each groove with plate fins 512 is vertically arranged, and all grooves with plate fins The slices 512 are arranged evenly along the horizontal direction. Each coil 511 is formed by connecting multiple S-shaped bends end to end and these S-shaped bends are located in the same vertical plane. All the coils 511 are evenly arranged horizontally. The vertical plane where the coiled tube 511 is located is perpendicular to the vertical plane where the slotted plate fin 512 is located, and the slotted plated fin 512 has a hole for the coiled tube 511 to pass through, and the coiled tube 511 Embedded in the slotted plate fins 512, the water inlet and outlet of the coil pipe 511 are respectively connected with the end of the water inlet pipe of the cooling tower and the head end of the water outlet pipe of the cooling tower. See Fig. 4 and Fig. 5 for partial enlarged schematic diagrams of the slotted plate fin 512 and the coiled tube 511 . The hot circulating water from the condenser 2 enters the header tank 3, and the circulating water that needs to be cooled enters the cooling tower 5 under the action of the circulating water pump 4. When the circulating water flows through the coil 511 in the cooling tower 5, it passes through the tank with plate type The fins 512 accelerate heat transfer and use the air entering from the bottom of the tower to take away part of the heat.

The circulating water cooling system of existing power plants mostly adopts the open cooling tower shown in Figure 2. On the one hand, the open cooling tower will cause evaporation loss of fresh water, and on the other hand, the cooling water is directly in contact with the atmosphere, and a large number of impurities in the atmosphere are easily It is brought into the circulating water system, resulting in serious corrosion and scaling of the pipeline, and a large amount of chemical agents such as scale inhibitors and corrosion inhibitors have to be added, which is not economical and will cause secondary pollution. In this specific example, we improved the structure of the open cooling tower and designed a closed cooling tower, so that the circulating water system forms a completely closed circulation loop, which avoids the evaporation loss of fresh water , reducing the loss of circulating water, and avoiding the impurities in the atmosphere from being brought into the circulating water system, thereby reducing the input of chemical agents such as scale inhibitors and corrosion inhibitors, thereby saving costs and reducing secondary pollution , has extensive economic value and practical value. Taking a power plant as an example, the circulating water system retains 10,000m ³ of water, 5,000m ³ /h of circulating water, and 150m ³ /h of supplementary water. The operating cost of the displacement is: chemical fee (coagulant, scale inhibitor) 0.029 yuan/t of water, The water fee is 2.8 yuan/t; the ammonia refrigeration process of the present invention takes the JZLG series screw ammonia refrigeration compressor unit as an example, the motor unit is calculated with a maximum power of 450kW under standard working conditions, and the industrial electricity fee is 0.9 yuan/kWh. Electricity is the electricity inside the power plant, and the price is at least 30% lower than the market; therefore, the annual cost savings of the circulating water system of the power plant are as follows: (1) Water fee: 150×24×365×2.8=3.679 million yuan; (2 ) Pharmacy fee: 5000×0.029×24×365=1.27 million yuan; and the electricity cost generated by the circulating water system is: 450×24×365×0.9×0.7=2.484 million yuan; Saving 2.465 million yuan, for areas with severe water shortage, the potential economic value is far greater than the value calculated above.

Referring to FIG. 3 , the ammonia refrigeration system includes: an evaporator 7 , a compressor 8 , a condenser 9 , a liquid storage tank 10 , an expansion valve 11 and pipes connecting them, and the pipes are filled with liquid ammonia. Wherein, the evaporator 7 is arranged on the water outlet pipe of the cooling tower, the outlet of the compressor 8 is connected with the ammonia inlet of the evaporator 7, the ammonia outlet of the evaporator 7 is connected with the inlet of the compressor 8, the condenser 9, the liquid storage tank 10 and expansion valve 11 are sequentially arranged on the ammonia inlet pipe of the evaporator along the flow direction of liquid ammonia. The circulating water flowing out of the coil 511 undergoes secondary heat exchange with liquid ammonia in the evaporator 7, and then flows into the water distribution tank 6 for heat exchange with exhaust steam in the condenser 2, thus forming a cycle.

As a preferred solution, the evaporator 7 is a semi-welded plate evaporator.

As a preferred solution, the cooling water outlet of the compressor 8 is connected to the water collection tank 3 .

As a preferred solution, the cooling water inlet of the condenser 9 is connected to the water distribution tank 6 , and the cooling water outlet is connected to the water collection tank 3 .

As a preferred solution, other water inlets are arranged on the water collection tank 3 .

Referring to FIG. 3 , the temperature monitoring and control system 12 is set on the outlet pipe of the cooling tower, between the evaporator 7 and the cooling tower 5 , and is connected with the compressor 8 and the expansion valve 11 for signals.

It should be noted that the above embodiments do not limit the present invention in any form, and all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (9)

1. A power plant circulating water cooling system comprising: a circulating water system, the circulating water system comprising: condenser (2), header tank (3), circulating water pump (4), cooling tower (5), knockout drum (6) and connect their pipeline, wherein, condenser (2) are used for cooling the exhaust steam behind turbine (1) acting, the circulating water export of condenser (2) and the circulating water access connection of cooling tower (5), the circulating water export of cooling tower (5) and the circulating water access connection of condenser (2), header tank (3) and circulating water pump (4) set gradually on the cooling tower inlet tube along rivers direction, knockout drum (6) set up on the cooling tower outlet pipe, a serial communication port, power plant's circulating water cooling system still includes ammonia refrigerating system, ammonia refrigerating system includes: evaporimeter (7), compressor (8), condenser (9), liquid storage pot (10), expansion valve (11) and the pipeline of connecting them fill liquid ammonia in the pipeline, wherein:

the evaporator (7) is arranged on a water outlet pipe of the cooling tower;

the outlet of the compressor (8) is connected with the ammonia inlet of the evaporator (7), and the ammonia outlet of the evaporator (7) is connected with the inlet of the compressor (8);

the condenser (9), the liquid storage tank (10) and the expansion valve (11) are sequentially arranged on the ammonia inlet pipe of the evaporator along the flow direction of liquid ammonia.

2. The circulating water cooling system of a power plant according to claim 1, characterized in that the circulating water cooling system of a power plant further comprises a temperature monitoring and control system (12), and the temperature monitoring and control system (12) is arranged on the water outlet pipe of the cooling tower, is positioned between the evaporator (7) and the cooling tower (5), and is in signal connection with the compressor (8) and the expansion valve (11).

3. The circulating water cooling system for the power plant according to claim 1, characterized in that a water collector (501), a spraying device (502), a filler (503) and a water collecting tank (504) are sequentially arranged in the cooling tower (5) from top to bottom, wherein a water inlet of the spraying device (502) is connected with a tail end of a water inlet pipe of the cooling tower, and a water outlet of the water collecting tank (504) is connected with a head end of a water outlet pipe of the cooling tower.

4. The power plant circulating water cooling system according to claim 1, wherein a plurality of coils (511) and a plurality of groove-strip-plate-type fins (512) are arranged in the cooling tower (5), each groove-strip-plate-type fin (512) is vertically arranged, all the groove-strip-plate-type fins (512) are uniformly arranged along the horizontal direction, each coil (511) is formed by connecting a plurality of S-shaped bent pipes end to end, the S-shaped bent pipes are located in the same vertical plane, all the coils (511) are uniformly arranged along the horizontal direction and are communicated through branch pipelines, the vertical plane where the coil (511) is located is perpendicular to the vertical plane where the groove-strip-plate-type fins (512) are located, holes for the coil (511) to pass through are reserved in the groove-strip-plate-type fins (512), the coil (511) is embedded in the groove-strip-plate-type fins (512), and a water inlet and a water outlet of the coil (511) are respectively connected, The head end of the water outlet pipe of the cooling tower is connected.

5. The circulating water cooling system of a power plant according to claim 1, characterized in that the evaporator (7) is a semi-welded plate evaporator.

6. The circulating water cooling system of a power plant according to claim 1, characterized in that the cooling water outlet of the compressor (8) is connected to a header tank (3).

7. The circulating water cooling system of a power plant according to claim 1, characterized in that the cooling water inlet of the condenser (9) is connected with the water diversion tank (6) and the cooling water outlet is connected with the water collection tank (3).

8. The circulating water cooling system of a power plant according to claim 1, characterized in that the header tank (3) is provided with other water inlets.

9. The circulating water cooling system for the power plant according to claim 1, characterized in that regulating valves are arranged between the condenser (2) and the water collection tank (3) and between the condenser (2) and the water distribution tank (6).

Images