Seawater desulfurization system based on seawater desulfurization bypass regulation

Abstract

The utility model relates to a seawater desulfurization system based on seawater desulfurization bypass adjustment. The seawater desulfurization system comprises a desulfurization absorption tower, a flue gas system, a seawater supply system and a seawater recovery system, the desulfurization absorption tower is connected with the flue gas system, the seawater supply system and the seawater recovery system. The utility model has the beneficial effects that the bypass pipeline is introduced, the desulfurization efficiency is high, the design requirement is met, circulating water with lower temperature can be introduced through the pipeline to further reduce the water temperature when high-sulfur coal is burnt, and if the circulating water is introduced through the drainage box culvert, the circulating water quantity required by the condenser in winter is small, so that the water temperature is reduced. Through the structure, the amount of circulating water passing through the condenser can be greatly reduced, the resistance of the whole circulating water system is reduced, and auxiliary power is saved.

Description

TECHNICAL FIELD

[0001] The utility model relates to desulfurization technical field, more exactly, it relates to a seawater desulfurization system based on seawater desulfurization bypass adjustment. BACKGROUND

[0002] The seawater flue gas desulfurization process of power plant is a kind of desulfurization process using the natural alkalinity of seawater to absorb SO2 in flue gas. Because rainwater carries alkaline substances (carbonate) of rock layer on land to sea, natural seawater is usually alkaline, and the natural alkalinity is about 1.5-2.5 mmol / L, which makes seawater have natural acid-base buffering capacity and SO2 absorption capacity. At the same time, the main components of seawater salt are sodium chloride and sulfate, so when SO2 is absorbed by seawater and oxidized into sulfate, the natural composition of seawater is not destroyed.

[0003] The design principle of seawater supply system is to provide enough water for desulfurization system and seawater recovery system. Therefore, the total water supply of seawater supply system should meet the requirements of the two systems. The water source comes from the warm drain of circulating cooling water system of main body engineering unit.

[0004] The seawater desulfurization system water source is directly taken from the condenser discharge pipe of each unit. The circulating water volume for desulfurization of two units is respectively pumped into the respective absorption tower by the respective seawater booster pump to wash flue gas. The seawater desulfurization water source is supplied by the circulating water drainage system. The desulfurization water source is considered to be connected in the circulating water drainage box culvert. The absorption tower water supply system is sent to the desulfurization absorption tower by seawater booster pump, and the seawater absorbs SO2 in flue gas, and then flows to the aeration tank from the bottom of the absorption tower by gravity. A large amount of seawater not involved in desulfurization directly flows to the aeration tank and the acidic seawater discharged from the desulfurization absorption tower for further mixing and aeration, so as to achieve the purpose of recovering seawater quality. The process flow of flue gas seawater desulfurization supply and drainage system is: circulating water drainage box culvert→seawater raw water booster pump station→flue gas seawater desulfurization tower→aeration tank→circulating water drainage box culvert→circulating water drainage connecting well→circulating water drainage outlet.

[0005] The power plant adopts seawater direct current water supply system, and each unit is conventionally equipped with three circulating water pumps, and each has one inlet and outlet pipe ditch. The conventional coal-fired generating unit without seawater desulfurization technology needs a large amount of water in summer due to high seawater temperature, and needs less water in winter, which is about 60% of that in summer.

[0006] After adopting a seawater desulfurization system, the circulating water volume of the generator unit must not only meet the unit's cooling water needs but also the water volume required for seawater desulfurization. The amount of seawater required for desulfurization is large. If the power plant burns high-sulfur coal, the flue gas will have a high sulfur content, correspondingly requiring a large amount of desulfurization seawater. The output and number of circulating water pumps in the circulating water system are affected by the required water volume for seawater desulfurization. The required water volume for seawater desulfurization is significantly affected by temperature and sulfur content. When the power plant burns high-sulfur coal, the required seawater volume is significantly higher than that required for conventional projects.

[0007] The efficiency of seawater desulfurization is affected by many factors, among which the flow rate of seawater entering the desulfurization tower and the temperature of the desulfurized seawater have the greatest impact. The larger the flow rate of desulfurized seawater, the greater the desulfurization capacity; the lower the temperature of the desulfurized seawater, the greater the desulfurization capacity. Therefore, to burn high-sulfur coal, it is necessary to increase the flow rate and temperature of the desulfurized seawater.

[0008] The temperature of desulfurized seawater is mainly affected by seasonality and is not adjusted. Currently, due to technological limitations, the desulfurization efficiency is conventionally improved by increasing the volume of desulfurized seawater and configuring circulating water pumps with higher output. However, this approach has the problem of high power consumption. Utility Model Content

[0009] The purpose of this invention is to address the shortcomings of existing technologies by proposing a seawater desulfurization system based on seawater desulfurization bypass regulation, comprising: a desulfurization absorption tower, a flue gas system, a seawater supply system, and a seawater recovery system; the desulfurization absorption tower is connected to the flue gas system, the seawater supply system, and the seawater recovery system.

[0010] The seawater supply system includes circulating water pumps, a circulating water main pipe, a circulating water inlet pipe, a circulating water return pipe, branch bypass pipes, a forebay, and a seawater booster pump. Several circulating water pumps are connected to the condenser via the circulating water main pipe, which is also connected to the circulating water inlet pipe via several branch pipes. Each branch pipe is equipped with a first isolation valve and a hemispherical valve. Both the circulating water inlet pipe and the circulating water return pipe are connected to the forebay, and the circulating water inlet pipe is also connected to the circulating water return pipe via several branch bypass pipes. A second isolation valve is installed on each branch bypass pipe. The forebay is connected to the seawater inlet of the desulfurization absorption tower via the seawater booster pump.

[0011] Preferably, the seawater restoration system includes an aeration tank and an aeration blower; the aeration blower is used to blow air into the aeration tank; the seawater outlet of the desulfurization absorption tower is connected to the aeration tank, and the aeration tank is also connected to the condenser through the circulating water return pipe; the aeration tank is provided with a seawater discharge outlet.

[0012] Preferably, the flue gas system includes a chimney and an induced draft fan, the induced draft fan being connected to the flue gas inlet at the bottom of the desulfurization absorption tower, and the chimney being connected to the flue gas outlet at the top of the desulfurization absorption tower.

[0013] Preferably, a desulfurization cooler is also provided between the induced draft fan and the desulfurization absorption tower.

[0014] Preferably, the desulfurization absorption tower is also connected to a demister.

[0015] The beneficial effects of this utility model are:

[0016] 1. This utility model introduces a bypass pipeline, which has high desulfurization efficiency and meets design requirements. When burning high-sulfur coal, low-temperature circulating water can be introduced through this pipeline to further reduce the water temperature. If circulating water is introduced through a drainage culvert, the amount of circulating water required by the condenser in winter is also small. This structure can significantly reduce the amount of circulating water passing through the condenser, reduce the resistance of the entire circulating water system, and save plant power.

[0017] 2. In summer, after circulating water enters the desulfurization system through the drainage culvert, the desulfurization efficiency is low due to the high temperature of the desulfurization water. This can easily lead to low desulfurization efficiency in the desulfurization tower caused by the high temperature of the seawater. When burning high-sulfur coal, the desulfurization process may fail to meet emission standards. Therefore, this invention uses a desulfurization hemispherical valve to rapidly reduce the temperature of the desulfurization water, thereby improving the desulfurization efficiency and preventing the emission standards from being exceeded due to changes in coal quality when burning high-sulfur coal.

[0018] 3. This utility model interlocks the desulfurization tower outlet emission index with the circulating water bypass. When the desulfurization index at the desulfurization tower outlet rises, the desulfurization bypass valve is opened to improve desulfurization efficiency.

[0019] 4. This utility model adds a heat exchanger and an emergency spray water system that serves as both a heat exchanger and a flue gas cooling system before the seawater desulfurization tower, thereby reducing the temperature of the incoming flue gas and improving the desulfurization efficiency. Attached Figure Description

[0020] Figure 1 A schematic diagram of a seawater desulfurization system based on seawater desulfurization bypass regulation provided by this utility model;

[0021] Figure 2 A flowchart of a seawater desulfurization method based on seawater desulfurization bypass regulation provided by this utility model;

[0022] Explanation of reference numerals in the attached diagram: 1. Desulfurization absorption tower; 2. Circulating water pump; 3. Circulating water main pipe; 4. Circulating water inlet pipe; 5. Circulating water return pipe; 6. Branch bypass pipe; 7. Forebay; 8. Aeration tank; 9. Aeration blower; 10. Seawater booster pump; 11. Chimney; 12. Demister; 13. Exhaust fan; 14. First isolation valve; 15. Hemispherical valve; 16. Second isolation valve; 17. Condenser; 18. Desulfurization cooler. Detailed Implementation

[0023] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that, for those skilled in the art, several modifications can be made to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0024] Example 1:

[0025] like Figure 1 As shown in Embodiment 1 of this application, a seawater desulfurization system based on seawater desulfurization bypass regulation is provided. A circulating water supply pipeline is introduced into three branches, each branch connecting to a drainage culvert and the desulfurized seawater from the circulating water supply main pipe. Each branch is equipped with a hemispherical valve, which has a small opening torque, reducing the opening torque of the seawater bypass. This valve is used to quickly regulate the amount of water entering the desulfurized seawater from the circulating water supply main pipe. Flow meters and isolation valves are also installed on the bypass pipelines of the three branches. The desulfurization tower outlet discharge indicators are interlocked with the circulating water bypass.

[0026] Specifically, the system includes: a desulfurization absorption tower 1, a flue gas system, a seawater supply system, and a seawater recovery system; the desulfurization absorption tower 1 is connected to the flue gas system, the seawater supply system, and the seawater recovery system.

[0027] The seawater supply system includes circulating water pumps 2, circulating water main pipes 3, circulating water inlet pipes 4, circulating water return pipes 5, branch bypass pipes 6, a forebay 7, and a seawater booster pump 10. Several circulating water pumps 2 are connected to the condenser 17 via the circulating water main pipes 3. The circulating water main pipes 3 are also connected to the circulating water inlet pipes 4 via several branch pipes, each equipped with a first isolation valve 14 and a hemispherical valve 15. The circulating water inlet pipes 4 and 5 are both connected to the forebay 7, and the circulating water inlet pipes 4 are also connected to the circulating water return pipes 5 via several branch bypass pipes 6. A second isolation valve 16 is installed on each branch bypass pipe 6. The forebay 7 is connected to the seawater inlet of the desulfurization absorption tower 1 via the seawater booster pump 10.

[0028] For example, this application installs a bypass pipe between the circulating water supply pipeline (DN3800) and the drainage culvert (3.9m×3.1m). The bypass pipe is located near the seawater desulfurization zone. When the seawater desulfurization demand exceeds the circulating water demand, the excess water enters the circulating water return culvert through the bypass pipe, reducing the head required by the circulating water pump and achieving energy saving. The maximum bypass water volume for a single unit is designed at approximately 41,160 m³ / h (winter coal type verification). To accommodate bypass water volumes under different operating conditions, each unit is planned to have three DN1200 bypass pipes entering the drainage culvert, with one electric maintenance butterfly valve and one electric regulating butterfly valve installed on each pipe. When used for seawater desulfurization, the seawater exceeding the unit's required circulating water volume can bypass the condenser, reducing the resistance of the entire circulating water system and saving plant power.

[0029] Example 2:

[0030] Based on Example 1, Example 2 of this application provides a more specific seawater desulfurization system with bypass regulation, including: a desulfurization absorption tower 1, a flue gas system, a seawater supply system, and a seawater recovery system; the desulfurization absorption tower 1 is connected to the flue gas system, the seawater supply system, and the seawater recovery system.

[0031] The seawater restoration system includes an aeration tank 8 and an aeration blower 9; the aeration blower 9 is used to blow air into the aeration tank 8; the seawater outlet of the desulfurization absorption tower 1 is connected to the aeration tank 8, and the aeration tank 8 is also connected to the condenser 17 through the circulating water return pipe 5; the aeration tank 8 is provided with a seawater discharge outlet.

[0032] The flue gas system includes a chimney 11 and an induced draft fan 13. The induced draft fan 13 is connected to the flue gas inlet at the bottom of the desulfurization absorption tower 1, and the chimney 11 is connected to the flue gas outlet at the top of the desulfurization absorption tower 1.

[0033] A desulfurization cooler 18 is also installed between the induced draft fan 13 and the desulfurization absorption tower 1. The lower the seawater desulfurization temperature, the higher the desulfurization efficiency. Adding a desulfurization cooler 18 and an emergency spray water system that combines heat exchanger surface flushing and flue gas cooling before the seawater desulfurization tower reduces the temperature of the incoming flue gas and improves desulfurization efficiency. The emergency spray water system is activated quickly when desulfurization emission indicators exceed the time limit. The heat exchanger before the desulfurization tower is used to heat the power plant condensate or boiler secondary air.

[0034] The desulfurization absorption tower 1 is also connected to the demister 12.

[0035] It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiment 2 can be referred to each other, and will not be repeated in this application.

[0036] Example 3:

[0037] Based on Example 2, Example 3 of this application provides a seawater desulfurization method based on seawater desulfurization bypass regulation, comprising:

[0038] Step 1: The seawater is transported to the forebay 7 in two streams by the circulating water pump 2. The first stream of seawater enters the forebay 7 through the circulating water main pipe 3, several branch pipes and the circulating water inlet pipe 4 in sequence. The second stream of seawater enters the forebay 7 through the circulating water main pipe 3, the condenser 17 and the circulating water return pipe bypass 6 (three branches).

[0039] Step 2: The seawater in the forebay 7 is transported to the seawater inlet of the desulfurization absorption tower 1 by the seawater booster pump 10; the flue gas from the induced draft fan 13 is transported to the flue gas inlet of the desulfurization absorption tower 1.

[0040] Step 3: In the desulfurization absorption tower 1, the flue gas is brought into countercurrent contact with seawater, and the SO2 in the flue gas is absorbed by the alkaline components in the seawater to generate acidic seawater.

[0041] Step 4: The desulfurized acidic seawater is transported to the aeration tank 8, and air is blown into the aeration tank 8 by the aeration blower 9 to oxidize sulfite ions to sulfate ions and neutralize the acidic seawater to restore the pH value; the desulfurized flue gas is discharged through the chimney 11.

[0042] Step 5: The restored seawater is sent back to the aeration tank 8 for recycling through the circulating water return pipe 5, or discharged through the seawater discharge outlet in compliance with standards.

[0043] In step 1, the bypass water volume of the branch bypass pipe 6 is dynamically adjusted through the second isolation valve 16 according to the sulfur content of the coal and the seawater temperature.

[0044] In step 2, before the flue gas is introduced into the desulfurization absorption tower 1 by the induced draft fan 13, it is first cooled by the desulfurization cooler 18.

[0045] Step 4 also includes: removing water mist from the flue gas using a demister 12 before discharging it.

[0046] It should be noted that the method provided in this embodiment is the method corresponding to the device provided in embodiment 1. Therefore, the parts in this embodiment that are the same as or similar to those in embodiment 1 can be referred to each other, and will not be repeated in this application.

Claims

1. A seawater desulfurization system based on seawater desulfurization bypass regulation, characterized in that, The application relates to a seawater desulfurization system. The seawater supply system comprises circulating water pumps (2), a circulating water mother pipe (3), a circulating water inlet pipe (4), a circulating water return pipe (5), branch bypass pipelines (6), a front pool (7) and a seawater booster pump (10); the circulating water pumps (2) are connected with a condenser (17) through the circulating water mother pipe (3), the circulating water mother pipe (3) is also connected with the circulating water inlet pipe (4) through a plurality of branches, first isolation valves (14) and half-ball valves (15) are arranged on the branches; the circulating water inlet pipe (4) and the circulating water return pipe (5) are both connected with the front pool (7), and the circulating water inlet pipe (4) is also connected with the circulating water return pipe (5) through a plurality of branch bypass pipelines (6); second isolation valves (16) are arranged on the branch bypass pipelines (6); the front pool (7) is connected with a seawater inlet of the desulfurization absorption tower (1) through the seawater booster pump (10). The seawater recovery system comprises an aeration tank (8) and an aeration fan (9); the aeration fan (9) is used for blowing air into the aeration tank (8); a seawater outlet of the desulfurization absorption tower (1) is connected with the aeration tank (8), and the aeration tank (8) is also connected with the condenser (17) through the circulating water return pipe (5); the aeration tank (8) is provided with a seawater discharge port.

2. The seawater desulphurization system based on seawater desulphurization bypass regulation according to claim 1, characterized in that, The flue gas system comprises a chimney (11) and an induced draft fan (13); the induced draft fan (13) is connected with a flue gas inlet at a lower part of the desulfurization absorption tower (1), and the chimney (11) is connected with a flue gas outlet at an upper part of the desulfurization absorption tower (1).

3. The seawater desulphurization system based on seawater desulphurization bypass regulation according to claim 2, characterized in that, A desulfurization cooler (18) is further arranged between the induced draft fan (13) and the desulfurization absorption tower (1).

4. The seawater desulphurization system based on seawater desulphurization bypass regulation according to claim 3, characterized in that, The desulfurization absorption tower (1) is also connected with a demister (12).

5. The seawater desulphurization system based on seawater desulphurization bypass regulation according to claim 4, characterized in that, ​

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