Ammonium sulfate mother liquor acidity control system

Abstract

The ammonium sulfate mother liquor acidity control system comprises a sulfuric acid overhead tank, a spray type saturator, a full flow tank, a large mother liquor circulating pump, a small mother liquor circulating pump, a crystallization pump and a crystallization tank, an inlet and an outlet of the mother liquor circulating pump are communicated between a large circulation outlet and a large circulation inlet of the spray type saturator; an outlet of the sulfuric acid overhead tank is respectively communicated with an inlet of the large mother liquor circulating pump and an inlet of the full flow tank; an overflow port of the spray-type saturator is communicated with an inlet of the full-flow tank, and an outlet of the full-flow tank is communicated with a reflux port of the spray-type saturator through the small mother liquor circulating pump; a saturated liquid outlet of the spraying type saturator is communicated with an inlet of the crystallization tank through the crystallization pump, and a liquid outlet of the crystallization tank is communicated with a liquid return opening of the spraying type saturator. The mother liquor acidity detection result of the system is closer to the true value, the acid adding amount can be accurately adjusted, the production requirement can be better met, the labor intensity of workers is relieved, and the working efficiency is greatly improved.

Description

Technical Field

[0001] This utility model relates to an ammonium sulfate production system, and more particularly to an acidity control system for ammonium sulfate mother liquor. Background Technology

[0002] Ammonium sulfate, also known as ammonium trisulfide, is a major product of the nitrogen fertilizer industry and one of the products for purifying coke oven gas in coking plants. The traditional production method in coking plants involves recovering ammonia from coke oven gas using the saturator method to produce ammonium sulfate. When producing ammonium sulfate using the saturator method, according to the crystallization principle of ammonium sulfate, the acidity of the mother liquor plays a crucial role in the quality of ammonium sulfate crystals. In actual operation, it is necessary to maintain a stable mother liquor acidity, controlling it between 3% and 5%. Fluctuations in mother liquor acidity are very detrimental to the production of large-particle ammonium sulfate; intermittent crystallization and rapid crystallization will generate a large number of crystal nuclei, making it impossible to obtain large-particle ammonium sulfate.

[0003] To maintain stable mother liquor acidity, ammonium sulfate operators must manually check the acidity of the saturator mother liquor every hour. However, manually checking the mother liquor acidity is complex, requiring one hand to shake the reagent bottle, the other to add neutralizing solution, and the eyes to observe color changes to determine if the titration endpoint has been reached. Slight carelessness can easily lead to over-titering and errors. The mother liquor acidity is determined by a sudden color change—the instant the sample changes from red to yellow—as the titration endpoint. This change relies on the naked eye, making misjudgment easy. Repeatability and reproducibility tests performed by the same operator and different operators on the same sample show significant differences in results, indicating poor repeatability. Furthermore, uneven manual stirring affects the complete neutralization of the mother liquor acidity and leads to incorrect judgment of the titration endpoint.

[0004] On the other hand, staff need to adjust the amount of acid added by manually controlling the regulating valve based on the acidity test results of the mother liquor. However, manual adjustment of the acid amount has a large margin of error, and staff often rely on their operating experience, which can easily cause large fluctuations in the acidity of the mother liquor, even exceeding the range required by the process. These fluctuations in the acidity of the mother liquor caused by human operation will have an adverse effect on the formation and growth process of crystals in the mother liquor, thereby affecting the quality and yield of ammonium sulfate. Utility Model Content

[0005] The technical problem to be solved by this invention is to provide a control system for the acidity of ammonium sulfate mother liquor that can accurately adjust the amount of acid added.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: It includes a high-level sulfuric acid tank, a spray-type saturator, a full-flow tank, a large mother liquor circulation pump, a small mother liquor circulation pump, a crystallization pump, and a crystallization tank; the inlet and outlet of the mother liquor circulation pump are connected between the large circulation outlet and the large circulation inlet of the spray-type saturator; the outlet of the high-level sulfuric acid tank is connected to the inlet of the large mother liquor circulation pump and the inlet of the full-flow tank; the overflow port of the spray-type saturator is connected to the inlet of the full-flow tank, and the outlet of the full-flow tank is connected to the return port of the spray-type saturator through the small mother liquor circulation pump; the saturated liquid outlet of the spray-type saturator is connected to the inlet of the crystallization tank through the crystallization pump, and the outlet of the crystallization tank is the return port of the spray-type saturator.

[0007] Furthermore, a regulating valve and a sulfuric acid flow meter are also provided; the regulating valve and the sulfuric acid flow meter are located at the outlet of the sulfuric acid high-pressure tank.

[0008] Furthermore, a mother liquor acidity analyzer is also provided; the mother liquor acidity analyzer is located inside the crystallization tank.

[0009] Furthermore, a control system is also provided; the control system is connected to the mother liquor acidity analyzer, the regulating valve and the sulfuric acid flow meter; the control system controls the opening degree of the regulating valve through the acidity signal from the mother liquor acidity analyzer.

[0010] The beneficial effects of adopting the above technical solution are as follows: The sulfuric acid described in this utility model enters the inlet pipe of the large mother liquor circulation pump and the full-flow tank through two branch pipes respectively to mix with the ammonium sulfate mother liquor. The ammonium sulfate mother liquor is circulated in the spray saturator to absorb ammonia in the coal gas. During the circulation process, the acidity of the ammonium sulfate mother liquor is controlled. The acidity detection result of the mother liquor is closer to the true value, which can accurately adjust the amount of acid added, better meet the needs of production, reduce the labor intensity of the staff, and greatly improve work efficiency. Attached Figure Description

[0011] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0012] Figure 1 This is a schematic diagram of the structure of this utility model.

[0013] In the diagram: 1. High-level sulfuric acid tank; 11. Regulating valve; 12. Sulfuric acid flow meter; 2. Spray saturator; 3. Full-flow tank; 4. Large mother liquor circulation pump; 41. Large mother liquor circulation pipe; 5. Small mother liquor circulation pump; 6. Crystallization pump; 7. Crystallization tank; 71. Mother liquor acidity analyzer; 8. Control system. Detailed Implementation

[0014] Figure 1As shown, this ammonium sulfate mother liquor acidity control system includes a sulfuric acid high-level tank 1, a spray-type saturator 2, a full-flow tank 3, a large mother liquor circulation pump 4, a small mother liquor circulation pump 5, a crystallization pump 6, and a crystallization tank 7. The spray-type saturator 2 has an absorption chamber at the top and a crystallization chamber at the bottom, and is also equipped with a downcomer that connects to the middle of the absorption chamber at the top and extends into the lower part of the crystallization chamber at the bottom. Thus, coke oven gas enters from the absorption chamber and comes into contact with the sprayed ammonium sulfate mother liquor. The ammonia in the gas reacts with the sulfuric acid in the mother liquor and is absorbed. The mother liquor from the absorption chamber enters the crystallization chamber through the downcomer. The crystallization chamber at the bottom of the spray-type saturator 2 has a large circulation outlet, and the absorption chamber at the top has a large circulation inlet. The crystallization chamber of the spray-type saturator 2 has an overflow port at the top, and the absorption chamber has a return port at the top. The crystallization chamber of the spray-type saturator 2 has a saturated liquid outlet at the bottom, and the crystallization chamber has a return liquid port in the middle. The mother liquor circulation pump 4 is connected between the large circulation outlet and the large circulation inlet of the spray saturator 2 via a large mother liquor circulation pipe 41; thus, the mother liquor in the spray saturator 2 can be circulated by the large mother liquor circulation pipe 41. The outlet of the sulfuric acid high-level tank 1 is connected to the inlet of the large mother liquor circulation pump 4 via the large mother liquor circulation pipe 41, so that the sulfuric acid in the sulfuric acid high-level tank 1 can enter the inlet of the large mother liquor circulation pump 4 through the large mother liquor circulation pipe 41 and be sent into the spray saturator 2 by the large mother liquor circulation pump 4.

[0015] Figure 1 As shown, in this ammonium sulfate mother liquor acidity control system, the outlet of the elevated sulfuric acid tank 1 is also connected to the inlet of the full-flow tank 3; thus, the sulfuric acid in the elevated sulfuric acid tank 1 can be sent into the full-flow tank 3. The overflow port of the spray saturator 2 is connected to the inlet of the full-flow tank 3, and the outlet of the full-flow tank 3 is connected to the return port of the spray saturator 2 through a small mother liquor circulation pump 5; the full-flow port of the full-flow tank 3 is connected to the mother liquor storage tank; thus, the overflow liquid of the spray saturator 2 is circulated through the small mother liquor circulation pump 5, and during the circulation process, the sulfuric acid entering the full-flow tank 3 is sent into the spray saturator 2.

[0016] Figure 1 As shown, in this ammonium sulfate mother liquor acidity control system, the saturated liquid outlet of the spray saturator 2 is connected to the inlet of the crystallization tank 7 via the crystallization pump 6, and the outlet of the crystallization tank 7 is connected to the return port of the spray saturator 2. In this way, after the ammonium sulfate mother liquor circulates in the spray saturator 2 to absorb ammonia from the coal gas, it enters the crystallization tank 7 to crystallize into ammonium sulfate. The resulting lean ammonium sulfate solution is then re-input into the spray saturator 2 for reuse.

[0017] Figure 1As shown, this ammonium sulfate mother liquor acidity control system also includes a regulating valve 11 and a sulfuric acid flow meter 12; the regulating valve 11 is preferably an automatic regulating valve. The regulating valve 11 and the sulfuric acid flow meter 12 are located on the pipeline at the outlet of the sulfuric acid high-level tank 1; thus, the flow rate of sulfuric acid supplied from the sulfuric acid high-level tank 1 to the full-flow tank 3 and the large mother liquor circulation pump 4 is adjusted by controlling the opening of the regulating valve 11. A mother liquor acidity analyzer 71 is also provided, preferably an online mother liquor acidity analyzer; the mother liquor acidity analyzer 71 is located in the crystallization tank 7 and is used to detect the acidity of the ammonium sulfate mother liquor in the crystallization tank 7.

[0018] Figure 1 As shown, this ammonium sulfate mother liquor acidity control system also includes a control system 8. The control system 8 is connected to the mother liquor acidity analyzer 71, the regulating valve 11, and the sulfuric acid flow meter 12. The control system 8 controls the opening of the regulating valve 11 based on the acidity signal from the mother liquor acidity analyzer 71. Thus, the ammonium sulfate mother liquor circulates in the spray saturator 2 to absorb ammonia from the coal gas. During the circulation process, the acidity of the ammonium sulfate mother liquor is analyzed and displayed by the mother liquor acidity analyzer 71, and the result is fed back to the control system 8. The control system 8 compares the analysis result with the set value, calculates the sulfuric acid output through PID parameter control, and automatically controls the opening of the regulating valve 11 to output sulfuric acid at the given flow rate. This automatically adjusts the flow rate of sulfuric acid supplied from the high-level sulfuric acid tank 1 to the full-flow tank 3 and the large mother liquor circulation pump 4, thereby achieving automatic control of the acidity of the ammonium sulfate mother liquor in the crystallization tank 7.

[0019] With the above structure, the ammonium sulfate mother liquor acidity control system adopts a dual circulation system: a large mother liquor circulation system and a small mother liquor circulation system. The large mother liquor circulation system is the main circulation system for the spray saturator 2. The spray saturator 2 needs to be replenished with mother liquor periodically. During this replenishment process, excess mother liquor in the spray saturator 2 needs to be discharged through the overflow port into the full flow tank 3. Once the full flow tank 3 is full, it is sent to the mother liquor storage tank for storage. As the mother liquor in the spray saturator 2 is gradually consumed, the small mother liquor circulation pump 5 is used to gradually send the mother liquor from the full flow tank 3 back into the spray saturator 2 to spray the coal gas. During operation, the liquid circulated by the large mother liquor circulation pump 4 and the small mother liquor circulation pump 5 is the same, and both the large and small mother liquor circulation pumps operate continuously.

[0020] Figure 1As shown, the operation process of this ammonium sulfate mother liquor acidity control system is as follows: Coke oven gas enters from the absorption chamber at the top of the spray saturator 2 and comes into contact with the sprayed ammonium sulfate mother liquor. The ammonia in the gas reacts with the sulfuric acid in the mother liquor and is absorbed. The mother liquor in the absorption chamber enters the crystallization chamber at the bottom of the spray saturator 2 through the downcomer, and is then continuously pumped out by the large mother liquor circulation pump 4 and sent to the upper part of the absorption chamber for spraying the gas. In order to stabilize the liquid level in the absorption chamber, mother liquor is periodically sent into the spray saturator 2. Excess mother liquor overflows through the overflow port and then flows into the mother liquor storage tank through the full flow tank 3. As the mother liquor is consumed, the mother liquor in the full flow tank 3 is pumped out by the small mother liquor circulation pump 5 and sent to the upper part of the absorption chamber for spraying to further remove ammonia from the gas. The continuously generated ammonium sulfate crystal nuclei are continuously circulated and stirred in the crystallization chamber. Small crystal particles move upward, while large crystal particles left at the bottom of the crystallization chamber are pumped to the crystallization tank 7 by the crystallization pump 6. During the production process, in order to stabilize the acidity of the ammonium sulfate mother liquor, sulfuric acid from the high-level sulfuric acid tank 1 needs to be added to the mother liquor. The sulfuric acid flow rate is controlled by the regulating valve 11, and the sulfuric acid flow meter 12 transmits the sulfuric acid flow rate information to the control system 8 in real time. The sulfuric acid enters the large mother liquor circulation pipe 41 and the full-flow tank 3 at the bottom of the spray saturator 2 through two branch pipes to mix with the ammonium sulfate mother liquor. The ammonium sulfate mother liquor absorbs ammonia from the coal gas through circulation in the spray saturator 2. During the circulation process, the acidity of the ammonium sulfate mother liquor is analyzed and displayed by the online mother liquor acidity analyzer, and the result is fed back to the control system 8. Based on the comparison between the analysis result and the set value, the sulfuric acid output is calculated through PID parameter control. The control system 8 controls the opening of the regulating valve 11 to output sulfuric acid at the given flow rate.

Claims

1. An acidity control system for ammonium sulfate mother liquor, characterized in that: The system includes a high-level sulfuric acid tank (1), a spray-type saturator (2), a full-flow tank (3), a large mother liquor circulation pump (4), a small mother liquor circulation pump (5), a crystallization pump (6), and a crystallization tank (7). The inlet and outlet of the mother liquor circulation pump (4) are connected between the large circulation outlet and the large circulation inlet of the spray-type saturator (2). The outlet of the high-level sulfuric acid tank (1) is connected to the inlet of the large mother liquor circulation pump (4) and the inlet of the full-flow tank (3). The overflow port of the spray-type saturator (2) is connected to the inlet of the full-flow tank (3), and the outlet of the full-flow tank (3) is connected to the return port of the spray-type saturator (2) through the small mother liquor circulation pump (5). The saturated liquid outlet of the spray-type saturator (2) is connected to the inlet of the crystallization tank (7) through the crystallization pump (6), and the outlet of the crystallization tank (7) is the return port of the spray-type saturator (2).

2. The ammonium sulfate mother liquor acidity control system according to claim 1, characterized in that: It is also equipped with a regulating valve (11) and a sulfuric acid flow meter (12); the regulating valve (11) and the sulfuric acid flow meter (12) are located at the outlet of the sulfuric acid high-pressure tank (1).

3. The ammonium sulfate mother liquor acidity control system according to claim 1 or 2, characterized in that: A mother liquor acidity analyzer (71) is also provided; the mother liquor acidity analyzer (71) is located in the crystallization tank (7).

4. The ammonium sulfate mother liquor acidity control system according to claim 3, characterized in that: A control system (8) is also provided; the control system (8) is connected to the mother liquor acidity analyzer (71), the regulating valve (11) and the sulfuric acid flow meter (12) by signal connection; the control system (8) controls the opening degree of the regulating valve (11) by the acidity signal of the mother liquor acidity analyzer (71).

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