A frozen brine denitration system

Abstract

The application discloses a frozen salt water denitration system, and relates to the technical field of frozen denitration.The technical scheme is that the frozen salt water denitration system comprises a refrigerant tank and a heat exchanger, the outlet of the refrigerant tank is connected with a mounting pipe, the first outlet of the mounting pipe is connected with a second connecting pipe, and the first outlet of the second connecting pipe is connected with the first inlet of the heat exchanger through a first connecting pipe.The beneficial effects of the technical scheme are as follows: the calcium chloride frozen salt water device is used to replace a freezing unit to provide cold energy for a denitration device, the freezing unit is used as a standby device, the problems of insufficient cold energy supply of a single freezing unit, high operation energy consumption of the denitration device and high operation and maintenance cost of the freezing unit can be solved, and the denitration can be continuously carried out during cleaning and maintenance of the heat exchanger. Low-temperature crystallization is realized through indirect heat exchange of the frozen salt water, sulfate is efficiently removed, and the energy consumption of the system is reduced.

Description

Technical Field

[0001] This utility model relates to the field of cryogenic denitrification technology, and in particular to a cryogenic brine denitrification system. Background Technology

[0002] During electrolysis, the sulfate content in the brine significantly affects the operating voltage of the electrolyzer; high sulfate content leads to increased voltage and power consumption. Reducing the sulfate content in the brine through a denitrification device lowers production costs. Currently, membrane denitrification is a widely used process in the chlor-alkali industry due to its low operating cost and energy consumption. One specific method, cryogenic denitrification, uses a refrigeration unit to provide cooling, with ethylene glycol as a medium to exchange heat with the nitrate-rich brine filtered through a nanofiltration membrane. This lowers the brine temperature to -5 to 5°C before it enters a settling tank for crystallization, and then a centrifuge removes sodium sulfate decahydrate. In current industrial production processes, a single refrigeration unit is typically used as the core refrigeration equipment. This unit is equipped with a large 180kW motor, which is mainly used to lower the temperature of ethylene glycol, and then use ethylene glycol to lower the temperature of brine, in order to meet the process requirements for a low-temperature environment.

[0003] However, this single-unit operation mode has many problems, seriously affecting the stability and operating efficiency of the system. First, the refrigeration unit consumes a lot of energy during long-term continuous operation, resulting in high overall operating costs. Especially under high-load conditions, the motor runs at full load continuously, significantly increasing power consumption, which is not conducive to achieving the company's energy-saving and consumption-reduction goals. Furthermore, because it adopts a single-unit configuration, the system lacks backup redundancy design. Once the refrigeration unit fails and needs repair or maintenance, the entire refrigeration system will be shut down. The maintenance cycle is usually long, during which normal refrigeration demand cannot be guaranteed, which in turn affects the stable operation of downstream key processes, causing sulfate accumulation in brine, seriously affecting the operating conditions of the electrolyzer. The single-unit operation mode also increases the risks and pressures of production management. Equipment maintenance must rely strictly on planned maintenance, making it difficult to deal with sudden failures and reducing the reliability and flexibility of the entire production system. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of current refrigeration systems, such as high energy consumption of the refrigeration unit when cooling ethylene glycol and the inability to cool the brine during maintenance, which affects subsequent production. Therefore, a refrigerated brine denitrification system is proposed.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A chilled brine denitrification system includes a refrigerant tank and a heat exchanger. The outlet of the refrigerant tank is connected to an installation pipe. The first outlet of the installation pipe is connected to a second connecting pipe. The first outlet of the second connecting pipe is connected to the first inlet of the heat exchanger through the first connecting pipe. A feed pipe is connected to the second inlet of the heat exchanger. The inlet of the feed pipe is connected to a refrigeration station. The first outlet of the heat exchanger is connected to the second connecting pipe. The second outlet of the second connecting pipe is connected to a cooler.

[0006] Since the refrigeration station always has -26°C frozen brine, using the -26°C frozen brine as the cooling medium and lowering the ethylene glycol temperature from -10°C to -15°C improves the cooling effect and reduces energy consumption.

[0007] Preferably, it also includes a refrigeration unit, with a second outlet of the installation pipe connected to a fourth connecting pipe, a first valve connected to the fourth connecting pipe, the outlet of the fourth connecting pipe connected to the inlet of the refrigeration unit, and the outlet of the refrigeration unit connected to the refrigerant tank.

[0008] The chiller is used as a backup device so that it can continue to be used when the heat exchanger is under maintenance, ensuring the normal operation of the denitrification process.

[0009] Preferably, a third valve is provided on the second connecting pipe, and the first outlet of the heat exchanger and the first outlet of the second connecting pipe are located on both sides of the third valve.

[0010] When the refrigeration unit is in standby mode, open the third valve and close the fourth valve to directly supply the cooled ethylene glycol to the cooler.

[0011] Preferably, a third connecting pipe is connected to the third outlet of the installation pipe, the outlet of the third connecting pipe is connected to the refrigerant tank, and a second valve is provided on the third connecting pipe.

[0012] Preferably, a circulation pump is installed on the installation pipe.

[0013] Preferably, a self-regulating valve is installed on the feed pipe.

[0014] Preferably, a temperature sensor is installed on the refrigerant tank.

[0015] Preferably, a fourth valve is provided on the first connecting pipe.

[0016] Compared with existing technologies, the beneficial effects of this utility model are: by using a calcium chloride chilled brine device to replace the refrigeration unit in providing cooling for the denitrification unit, with the refrigeration unit serving as a backup, it solves the problems of insufficient cooling supply from a single refrigeration unit, high energy consumption during denitrification unit operation, and high maintenance costs for the refrigeration unit. Denitrification can be carried out uninterrupted during heat exchanger cleaning and maintenance. Low-temperature crystallization is achieved through indirect heat exchange with chilled brine, efficiently removing sulfate ions and reducing system energy consumption. Attached Figure Description To more clearly illustrate the technical solution of this utility model, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a structural schematic diagram of a specific embodiment of the present utility model.

[0018] In the diagram: 1. Refrigerant tank; 2. Circulating pump; 3. Heat exchanger; 4. Installation pipe; 5. Feed pipe; 6. Conveying pipe; 7. First connecting pipe; 8. Second connecting pipe; 9. Third connecting pipe; 10. Fourth connecting pipe; 11. Refrigeration unit. Detailed Implementation

[0019] To make the objectives, features, and advantages of this utility model more apparent and understandable, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent.

[0020] Reference Figure 1 A chilled brine denitrification system includes a refrigerant tank 1 and a heat exchanger 3. The heat exchanger 3 is a plate heat exchanger. An installation pipe 4 is connected to the outlet of the refrigerant tank 1. A circulation pump 2 is installed on the installation pipe 4, controlling the delivery of ethylene glycol. A second connecting pipe 8 is connected to the first outlet of the installation pipe 4. The first outlet of the second connecting pipe 8 is connected to the first inlet of the heat exchanger 3 via a first connecting pipe 7. The first outlet of the heat exchanger 3 and the first outlet of the second connecting pipe 8 are located on opposite sides of a third valve. A feed pipe 5 is connected to the second inlet of the heat exchanger 3. An automatic regulating valve is installed on the feed pipe 5, regulating the flow rate of -26℃ chilled brine delivered in the feed pipe 5. The inlet of the feed pipe 5 is connected to... There is a refrigeration station that supplies -26°C chilled brine to heat exchanger 3. The -26°C chilled brine in the refrigeration station is for chlor-alkali production, so it needs to be continuously cooled in the refrigeration station. The first outlet of heat exchanger 3 is connected to the second connecting pipe 8, and the second outlet of the second connecting pipe 8 is connected to the cooler. The second connecting pipe 8 supplies ethylene glycol that needs to be cooled to heat exchanger 3. The -26°C chilled brine cools the ethylene glycol in heat exchanger 3, and after cooling, it is supplied to the second connecting pipe 8 again. The second connecting pipe 8 supplies the ethylene glycol to the cooler, where the ethylene glycol cools the brine. After cooling, the brine is supplied to the crystallizer, where it crystallizes and separates sulfate ions.

[0021] Reference Figure 1 It also includes a chiller 11. The second outlet of the mounting pipe 4 is connected to a fourth connecting pipe 10. A first valve is connected to the fourth connecting pipe 10. The outlet of the fourth connecting pipe 10 is connected to the inlet of the chiller 11. The outlet of the chiller 11 is connected to the refrigerant tank 1. A temperature sensor is installed on the refrigerant tank 1. A fourth valve is installed on the first connecting pipe 7. A third valve is installed on the second connecting pipe 8. When the heat exchanger 3 needs maintenance, the fourth valve is closed, the third valve is closed, and the first valve is opened. At this time, the ethylene glycol that needs to be cooled is transported to the chiller 11 through the third connecting pipe 9. The chiller 11 transports the cooled ethylene glycol back to the refrigerant tank 1. After multiple cycles, the temperature of the ethylene glycol is detected by the stabilization sensor. When the temperature is suitable, the third valve is opened. At this time, some of the ethylene glycol is transported to the cooler for cooling.

[0022] Reference Figure 1 A third connecting pipe 9 is connected to the third outlet of the installation pipe 4. The outlet of the third connecting pipe 9 is connected to the refrigerant tank 1. A second valve is installed on the third connecting pipe 9. The third connecting pipe 9 can transfer excess ethylene glycol back to the refrigerant tank 1.

[0023] During normal operation of heat exchanger 3, the first, second, and third valves are closed, and the fourth valve is opened. Ethylene glycol in refrigerant tank 1 is pumped to installation pipe 4 via circulation pump 2. Then, ethylene glycol is pumped to heat exchanger 3 via first connecting pipe 7. The refrigeration station pumps chilled brine into heat exchanger 3 via feed pipe 5 to cool the ethylene glycol. Simultaneously, the chilled brine is discharged through the second outlet. The cooled ethylene glycol is then pumped to conveying pipe 6 via the first outlet, and conveying pipe 6 pumps it again to the second connecting pipe 8. The second connecting pipe 8 pumps the cooled ethylene glycol to the cooler, where it cools the brine. When heat exchanger 3 requires maintenance, the fourth, third, and second valves are closed, and the first valve is opened. Ethylene glycol in refrigerant tank 1 is pumped to refrigeration unit 11 via fourth connecting pipe 10. The temperature sensor in refrigerant tank 1 detects the temperature of the ethylene glycol. When the temperature is suitable, the third valve is opened, at which point some ethylene glycol is pumped to the cooler to cool the brine.

[0024] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A chilled brine denitrification system, characterized in that: The device includes a refrigerant tank (1) and a heat exchanger (3). The outlet of the refrigerant tank (1) is connected to an installation pipe (4). The first outlet of the installation pipe (4) is connected to a second connecting pipe (8). The first outlet of the second connecting pipe (8) is connected to the first inlet of the heat exchanger (3) through a first connecting pipe (7). The second inlet of the heat exchanger (3) is connected to a feed pipe (5). The inlet of the feed pipe (5) is connected to a refrigeration station. The first outlet of the heat exchanger (3) is connected to the second connecting pipe (8). The second outlet of the second connecting pipe (8) is connected to a cooler.

2. The chilled brine denitrification system according to claim 1, characterized in that: It also includes a refrigeration unit (11), the second outlet of the installation pipe (4) is connected to a fourth connecting pipe (10), the fourth connecting pipe (10) is connected to a first valve, the outlet of the fourth connecting pipe (10) is connected to the inlet of the refrigeration unit (11), and the outlet of the refrigeration unit (11) is connected to the refrigerant tank (1).

3. The chilled brine denitrification system according to claim 2, characterized in that: A third valve is provided on the second connecting pipe (8), and the first outlet of the heat exchanger (3) and the first outlet of the second connecting pipe (8) are located on both sides of the third valve.

4. The chilled brine denitrification system according to claim 1, characterized in that: A third connecting pipe (9) is connected to the third outlet of the installation pipe (4). The outlet of the third connecting pipe (9) is connected to the refrigerant tank (1). A second valve is installed on the third connecting pipe (9).

5. The chilled brine denitrification system according to claim 1, characterized in that: A circulation pump (2) is installed on the installation pipe (4).

6. The chilled brine denitrification system according to claim 1, characterized in that: An automatic regulating valve is installed on the feed pipe (5).

7. The chilled brine denitrification system according to claim 1, characterized in that: A temperature sensor is installed on the refrigerant tank (1).

8. The chilled brine denitrification system according to claim 1, characterized in that: A fourth valve is installed on the first connecting pipe (7).

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