Material lifting system of ammonium sulfate saturator and control method

Abstract

The system comprises a saturator, a crystallization pump, a crystallization tank, a centrifugal machine, a crystallization pump inlet pipe, a crystallization pump outlet pipe, a mother liquor overflow pipe, a mother liquor bypass pipe, a centrifugal machine inlet pipe, a centrifugal machine filtrate pipe, the control system, a differential pressure transmitter, a material lifting valve and a bypass valve. The control method comprises the following steps: continuously operating the crystallization pump, measuring the pressure difference of the ammonium sulfate mother liquor in the crystallization tank by adopting the differential pressure transmitter, transmitting the pressure difference information to the control system in real time by adopting the differential pressure transmitter, calculating the liquid crystal ratio of the ammonium sulfate mother liquor by the control system, and controlling the material lifting valve and the bypass valve by the control system through pid parameter control according to comparison between an analysis result and a set numerical value. Therefore, starting or ending of material lifting is controlled. The ammonium sulfate mother liquid crystal is more timely and continuous than a detection result, starting and ending of material lifting of the ammonium sulfate saturator can be timely and accurately controlled, the system operation efficiency is improved, and the ammonium sulfate yield is increased.

Description

Technical Field

[0001] This patent application belongs to the technical field of recovery of chemical products from coke oven gas, and more specifically, relates to a feeding system and control method for an ammonium sulfate saturator. Background Art

[0002] In the original ammonium sulfate extraction system, the crystallization pump is turned on only when the ammonium sulfate mother liquor ratio rises to about 25%, and the ammonium sulfate mother liquor is pumped from the saturator crystallization chamber to the crystallization tank. The crystallization pump is shut down after the extraction is completed. For a long time, due to the discontinuity and hysteresis of the manual measurement of the ammonium sulfate mother liquor ratio, the extraction is often started only when the ammonium sulfate mother liquor ratio is ≥30%. This delayed operation leads to the accumulation of materials in the pipeline of the extraction system, affecting the progress of the extraction. The failure to extract materials on time leads to different degrees of increase in the resistance of the saturator. In severe cases, the ammonium sulfate crystals block the pipeline of the extraction system. At this time, manpower needs to be organized to deal with it, affecting the normal cycle operation of the ammonium sulfate process.

[0003] After the material extraction is completed, a certain amount of crystals must remain in the ammonium sulfate mother liquor of the saturator, which is conducive to the rapid reaction and the growth of materials. In the original actual production, when the crystal ratio of the ammonium sulfate mother liquor is about 5%, the material extraction is stopped. Due to the discontinuity and hysteresis of the manual measurement of the crystal ratio of the ammonium sulfate mother liquor, the material extraction is often stopped when the crystal ratio of the ammonium sulfate mother liquor is less than 5% or even without crystals. In this way, due to the excessive discharge of the material, the liquid level of the saturator is supplemented too much, which breaks the balance of the reaction, reduces the reaction speed, and reduces the ammonium sulfate production. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an ammonium sulfate saturator feeding system and a control method. The ammonium sulfate mother liquid crystal ratio detection result is more timely and continuous, and the start and end of the ammonium sulfate saturator feeding can be controlled in a timely and accurate manner, which can better meet the production needs, reduce the labor intensity of the staff, improve the system operation efficiency, and increase the ammonium sulfate output.

[0005] In order to solve the above problems, the technical solution adopted by the present invention is:

[0006] The invention discloses an ammonium sulfate saturator material extraction system, comprising a saturator, a crystallization pump, a crystallization tank, a centrifuge, a crystallization pump inlet pipe, a crystallization pump outlet pipe, a mother liquor overflow pipe, a mother liquor bypass pipe, a centrifuge inlet pipe, a centrifuge filtrate pipe, a control system, a differential pressure transmitter, a material extraction valve and a bypass valve. The saturator is connected to the crystallization pump through the crystallization pump inlet pipe, the crystallization pump is connected to the crystallization tank through the crystallization pump outlet pipe, the crystallization tank is connected to the saturator through the mother liquor overflow pipe and the centrifuge filtrate pipe in turn, the output end of the crystallization tank is connected to the saturator through the mother liquor bypass pipe and the centrifuge filtrate pipe in turn, the crystallization tank is connected to the centrifuge through the centrifuge inlet pipe, and the centrifuge is connected to the saturator through the centrifuge filtrate pipe.

[0007] The centrifuge inlet pipe is provided with a feed valve, the mother liquor bypass pipe is provided with a bypass valve, and the feed valve and the bypass valve are respectively connected to the control system.

[0008] The crystallization tank is provided with a differential pressure transmitter, which is connected to the control system and transmits information to the control system in real time.

[0009] In addition, a method for controlling the extraction of ammonium sulfate saturator is also provided:

[0010] The crystallization pump runs continuously, and the ammonium sulfate mother liquor in the saturator is sent to the crystallization tank through the crystallization pump inlet pipe and the crystallization pump outlet pipe in turn.

[0011] The differential pressure transmitter is used to measure the pressure difference of the ammonium sulfate mother liquor in the crystallization tank. The differential pressure transmitter transmits the pressure difference information to the control system in real time. The control system calculates the crystal ratio of the ammonium sulfate mother liquor and controls it through the pid parameters. The analysis results are compared with the set values:

[0012] When the crystal ratio of ammonium sulfate mother liquor is ≥25%, the control system opens the feed valve and closes the bypass valve. The ammonium sulfate mother liquor in the crystallization tank enters the centrifuge through the centrifuge inlet pipe, and the feed begins. The centrifuge performs solid-liquid separation on the ammonium sulfate mother liquor. The separated filtrate enters the saturator through the centrifuge filtrate pipe, and the crystal ratio of ammonium sulfate mother liquor gradually decreases.

[0013] When the feed valve is in an open state and the ammonium sulfate mother liquor ratio is 5% < 25%, the control system controls the feed valve to continue to be opened, and the bypass valve is still closed. The ammonium sulfate mother liquor in the crystallization tank enters the centrifuge through the centrifuge inlet pipe, and the feed continues to be fed. The centrifuge performs solid-liquid separation on the ammonium sulfate mother liquor, and the separated filtrate enters the saturator through the centrifuge filtrate pipe, and the ammonium sulfate mother liquor ratio gradually decreases;

[0014] When the ammonium sulfate mother liquor crystal ratio is ≤5%, the control system opens the bypass valve and closes the feed valve. The ammonium sulfate mother liquor in the crystallization tank enters the saturator through the mother liquor bypass pipe and the centrifuge filtrate pipe in turn, and the feed is stopped. The ammonium sulfate mother liquor crystal ratio gradually increases.

[0015] When the feed valve is in a closed state and the ammonium sulfate mother liquor ratio is 5% < 25%, the control system controls the bypass valve to continue to open, and the feed valve is still closed. The ammonium sulfate mother liquor in the crystallization tank enters the saturator through the mother liquor bypass pipe and the centrifuge filtrate pipe in turn, and the feed is continued to stop, and the ammonium sulfate mother liquor ratio gradually increases;

[0016] In the above steps, it is necessary to take anti-overflow measures for the crystallization tank, that is: when the liquid level in the crystallization tank is higher than the setting height of the mother liquor overflow pipe at the top of the crystallization tank, the ammonium sulfate mother liquor above the setting height of the mother liquor overflow pipe at the top of the crystallization tank passes through the mother liquor overflow pipe and the centrifuge filtrate pipe in sequence and then enters the saturator to ensure that the ammonium sulfate mother liquor in the crystallization tank will not overflow the crystallization tank due to excessively high liquid level.

[0017] Due to the adoption of the above technical solution, the beneficial effects achieved by the present invention are:

[0018] 1) The present invention can continuously operate the crystallization pump, so that the ammonium sulfate mother liquor circulates in the pipeline of the material extraction system, thereby preventing the residual ammonium sulfate crystals from adhering to the inner wall of the pipeline and clogging the pipeline after the crystallization pump stops, ensuring the material extraction progress, stabilizing the saturator resistance at a low level, and ensuring the normal cycle operation of the ammonium sulfate process.

[0019] 2) The feeding system of the ammonium sulfate saturator can timely and accurately control the start of feeding, avoiding the phenomenon of material accumulation in the feeding system pipeline when the feeding is started when the ammonium sulfate mother liquor is relatively high, and preventing the ammonium sulfate crystals from blocking the feeding system pipeline, thereby improving the system operation efficiency and reducing the labor intensity of workers; the feeding system of the ammonium sulfate saturator can timely and accurately control the end of feeding, keeping a certain amount of crystals in the ammonium sulfate mother liquor, which is conducive to the rapid reaction, the growth of materials, and the increase of ammonium sulfate production.

[0020] 3) The detection result of the ammonium sulfate mother liquid crystal ratio of the present invention is more timely and continuous, and can timely and accurately control the start and end of the ammonium sulfate saturator feeding, thereby improving the system operation efficiency and increasing the ammonium sulfate output. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the equipment flow chart of the system in the present invention.

[0022] Among them: saturator 1, crystallization pump 2, crystallization tank 3, centrifuge 4, crystallization pump inlet pipe 5, crystallization pump outlet pipe 6, mother liquor overflow pipe 7, mother liquor bypass pipe 8, centrifuge inlet pipe 9, centrifuge filtrate pipe 10, control system 11, differential pressure transmitter 12, feed valve 13, bypass valve 14. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the embodiments.

[0024] A system for extracting ammonium sulfate saturator, such as Figure 1 As shown, it includes a saturator 1, a crystallization pump 2, a crystallization tank 3, a centrifuge 4, a crystallization pump inlet pipe 5, a crystallization pump outlet pipe 6, a mother liquor overflow pipe 7, a mother liquor bypass pipe 8, a centrifuge inlet pipe 9, a centrifuge filtrate pipe 10, a control system 11, a differential pressure transmitter 12, a feed valve 13 and a bypass valve 14, the saturator 1 is connected to the crystallization pump 2 through the crystallization pump inlet pipe 5, the crystallization pump 2 is connected to the crystallization tank 3 through the crystallization pump outlet pipe 6, the crystallization tank 3 is connected to the saturator 1 through the mother liquor overflow pipe 7 and the centrifuge filtrate pipe 10 in turn, the output end of the crystallization tank 3 is connected to the saturator 1 through the mother liquor bypass pipe 8 and the centrifuge filtrate pipe 10 in turn, the crystallization tank 3 is connected to the centrifuge 4 through the centrifuge inlet pipe 9, and the centrifuge 4 is connected to the saturator 1 through the centrifuge filtrate pipe 10.

[0025] The centrifuge inlet pipe 9 is provided with a feed valve 13 , and the mother liquor bypass pipe 8 is provided with a bypass valve 14 . The feed valve 13 and the bypass valve 14 are respectively connected to the control system 11 .

[0026] The crystallization tank 3 is provided with a differential pressure transmitter 12 , which is connected to the control system 11 and transmits information to the control system 11 in real time.

[0027] Based on the above-mentioned material extraction system, the present invention also provides a material extraction control method for an ammonium sulfate saturator, specifically:

[0028] The crystallization pump 2 operates continuously, and the ammonium sulfate mother liquor in the saturator 1 is sent to the crystallization tank 3 through the crystallization pump inlet pipe 5 and the crystallization pump outlet pipe 6 in turn.

[0029] The differential pressure transmitter 12 is used to measure the pressure difference of the ammonium sulfate mother liquor in the crystallization tank 3. The differential pressure transmitter 12 transmits the pressure difference information to the control system 11 in real time. The control system 11 calculates the ammonium sulfate mother liquor liquid ratio and controls it through the pid parameter. The analysis result is compared with the set value:

[0030] When the ammonium sulfate mother liquid crystal ratio is ≥25%, the control system 11 controls the opening of the feed valve 13 and the closing of the bypass valve 14, and the ammonium sulfate mother liquor in the crystallization tank 3 enters the centrifuge 4 through the centrifuge inlet pipe 9, and the feed is started. The centrifuge 4 performs solid-liquid separation on the ammonium sulfate mother liquor, and the separated filtrate enters the saturator 1 through the centrifuge filtrate pipe 10, and the ammonium sulfate mother liquid crystal ratio gradually decreases;

[0031] When the feed valve 13 is in an open state and the ammonium sulfate mother liquid crystal ratio is 5%<25%, the control system 11 controls the feed valve 13 to continue to be opened, and the bypass valve 14 is still closed. The ammonium sulfate mother liquor in the crystallization tank 3 enters the centrifuge 4 through the centrifuge inlet pipe 9, and the feed is continued. The centrifuge 4 performs solid-liquid separation on the ammonium sulfate mother liquor, and the separated filtrate enters the saturator 1 through the centrifuge filtrate pipe 10, and the ammonium sulfate mother liquid crystal ratio gradually decreases.

[0032] When the ammonium sulfate mother liquid crystal ratio is ≤5%, the control system 11 controls the bypass valve 14 to be opened, the feed valve 13 to be closed, and the ammonium sulfate mother liquor in the crystallization tank 3 enters the saturator 1 through the mother liquor bypass pipe 8 and the centrifuge filtrate pipe 10 in turn, the feed is stopped, and the ammonium sulfate mother liquid crystal ratio gradually increases.

[0033] The gradual increase of the ammonium sulfate mother liquid crystal ratio is continuously observed. When the feed valve 13 is in a closed state and the ammonium sulfate mother liquid crystal ratio is 5%<ammonium sulfate mother liquid crystal ratio<25%, the control system 11 controls the bypass valve 14 to continue to be opened, and the feed valve 13 is still closed. The ammonium sulfate mother liquor in the crystallization tank 3 enters the saturator 1 through the mother liquor bypass pipe 8 and the centrifuge filtrate pipe 10 in turn, and the feed is continuously stopped, and the ammonium sulfate mother liquid crystal ratio gradually increases.

[0034] In the above steps, anti-overflow measures are taken for the crystallization tank 3 to ensure that the ammonium sulfate mother liquor in the crystallization tank 3 will not overflow the tank. The specific measures are: when the liquid level of the crystallization tank 3 is higher than the setting height of the mother liquor overflow pipe 7 at the top of the crystallization tank 3, the ammonium sulfate mother liquor above the setting height of the mother liquor overflow pipe 7 at the top of the crystallization tank 3 passes through the mother liquor overflow pipe 7 and the centrifuge filtrate pipe 10 in sequence and then enters the saturator 1, thereby ensuring that the ammonium sulfate mother liquor in the crystallization tank 3 will not overflow the crystallization tank 3 due to the excessively high liquid level.

[0035] In practical application, the process control method is as follows: the coal gas from desulfurization enters the saturator 1, which is a spray-type ammonium sulfate saturator. The coal gas enters the annular chamber in two streams in the upper section of the saturator 1, and countercurrently contacts with the circulating mother liquor heated by the mother liquor heater, wherein ammonia is absorbed by sulfuric acid in the mother liquor to generate ammonium sulfate. The mother liquor in the upper part of the lower section of the saturator 1 is continuously pumped out by a large mother liquor circulation pump and sent to the upper section of the saturator for circulation spraying. The circulating mother liquor after spraying flows to the lower section of the saturator through the central downcomer. In the lower section of the saturator 1, the crystal nucleus moves upward through the saturated medium, causing the crystal nucleus to grow, and causing grain classification, and the ammonium sulfate mother liquid crystal ratio gradually increases.

[0036] When the composition of ammonium sulfate mother liquor changes, its density will inevitably change. As P=ρ×g×h shows, the change in density causes the change in pressure. In order to eliminate the influence of the change in height, we convert the measured pressure into the measured pressure difference, that is, △P=ρ×g×△h, where △P is the pressure difference of ammonium sulfate mother liquor; ρ is the density of ammonium sulfate mother liquor, which needs to be obtained based on sampling and testing; g is a constant, and △h is the height difference of the pressure point of the differential pressure transmitter 12. If △h=1 meter, then △P=ρ×g. This is the principle of the differential pressure transmitter 12.

[0037] Take the ammonium sulfate mother liquor and prepare solutions with the same volume but different solid-liquid ratios, weigh them, and then test them to obtain their densities. Then, the pressure difference corresponding to the density is calculated by the formula △P=ρ×g, and the relationship between the solid-liquid ratio of the ammonium sulfate mother liquor and the pressure difference is established, B=k×△P+c, and it is concluded that the solid-liquid ratio of the ammonium sulfate mother liquor and the pressure difference are in a linear relationship, wherein B is the solid-liquid ratio of the ammonium sulfate mother liquor (i.e., the crystal ratio); △P is the pressure difference of the ammonium sulfate mother liquor; k and c are constants.

[0038] Several embodiments are listed below for illustration.

[0039] Embodiment 1: The ammonium sulfate saturator material extraction control method of the present system is specifically described as follows: when the differential pressure transmitter 12 measures a pressure difference of 1.266 Pa, the ammonium sulfate mother liquor ratio is automatically calculated by the PLC to be 25%, the control system 11 controls the opening of the material extraction valve 13, the closing of the bypass valve 14, and the ammonium sulfate mother liquor in the crystallization tank 3 enters the centrifuge 4 through the centrifuge inlet pipe 9 to start material extraction.

[0040] Embodiment 2: The ammonium sulfate saturator material extraction control method of the present system is specifically described as follows: when the differential pressure transmitter 12 measures a pressure difference of 1.230 Pa, the ammonium sulfate mother liquor ratio is automatically calculated by the PLC to be 15%, the control system 11 controls the material extraction valve 13 to continue to be opened, and the bypass valve 14 is still closed, and the ammonium sulfate mother liquor in the crystallization tank 3 enters the centrifuge 4 through the centrifuge inlet pipe 9 to continue to extract the material.

[0041] Embodiment 3: The material extraction control method of the ammonium sulfate saturator of the present system is specifically described as follows: when the differential pressure transmitter 12 measures a pressure difference of 1.194 Pa, the ammonium sulfate mother liquor ratio is automatically calculated by the PLC to be 5%, the control system 11 controls the opening of the bypass valve 14, closes the material extraction valve 13, and the ammonium sulfate mother liquor in the crystallization tank 3 enters the saturator 1 through the mother liquor bypass pipe 8 and the centrifuge filtrate pipe 10 in turn, and stops extracting the material to ensure that the ammonium sulfate mother liquor ratio gradually increases.

[0042] Embodiment 4: The material extraction control method of the ammonium sulfate saturator of the present system is specifically described as follows: when the pressure difference measured by the differential pressure transmitter 12 is 1.212 Pa, the ammonium sulfate mother liquor ratio is automatically calculated by the PLC to be 10%, the control system 11 controls the bypass valve 14 to continue to be opened, and the material extraction valve 13 is still closed, and the ammonium sulfate mother liquor in the crystallization tank 3 enters the saturator 1 through the mother liquor bypass pipe 8 and the centrifuge filtrate pipe 10 in turn, and the material extraction continues to stop.

Claims

1. A system for extracting ammonium sulfate saturator, characterized in that: The invention comprises a saturator (1), a crystallization pump (2) connected to the saturator (1), a crystallization tank (3) connected to the crystallization pump (2), a mother liquor overflow pipe (7) arranged at the top of the crystallization tank (3), a mother liquor bypass pipe (8) and a centrifuge inlet pipe (9) connected to the output end of the crystallization tank (3), a centrifuge (4) connected to the centrifuge inlet pipe (9), a centrifuge filtrate pipe (10) connected to the centrifuge (4), a feed valve (13) arranged on the centrifuge inlet pipe (9), a bypass valve (14) arranged on the mother liquor bypass pipe (8), and a control system (11) connected to both the feed valve (13) and the bypass valve (14), wherein the mother liquor overflow pipe (7) and the mother liquor bypass pipe (8) are both connected to the centrifuge filtrate pipe (10), and the centrifuge (4) is connected to the saturator (1) via the centrifuge filtrate pipe (10); A differential pressure transmitter (12) is also provided in the middle of the crystallization tank (3); the differential pressure transmitter (12) is connected to the control system (11) and transmits information to the control system (11) in real time.

2. The ammonium sulfate saturator feeding system according to claim 1, characterized in that: The saturator (1) is connected to the crystallization pump (2) via a crystallization pump inlet pipe (5), and the crystallization pump (2) is connected to the crystallization tank (3) via a crystallization pump outlet pipe (6).

3. The ammonium sulfate saturator feeding system according to claim 1, characterized in that: The crystallization pump inlet pipe (5) and the crystallization pump outlet pipe (6) are both hoses.

4. The ammonium sulfate saturator feeding system according to claim 1, characterized in that: The accuracy of the differential pressure transmitter (12) is ±0.05%.

5. A method for controlling the extraction of ammonium sulfate saturator, characterized in that: The material lifting control system according to any one of claims 1 to 4 is used, and specifically comprises the following steps: S1 and the crystallization pump (2) are in continuous operation, and the ammonium sulfate mother liquor in the saturator (1) is sent to the crystallization tank (3) through the crystallization pump (2); S2. A differential pressure transmitter (12) is used to measure the pressure difference of the ammonium sulfate mother liquor in the crystallization tank (3). The differential pressure transmitter (12) transmits the pressure difference information to the control system (11) in real time. The control system (11) calculates the crystal ratio of the ammonium sulfate mother liquor and compares the analysis result with the set value through control. The control system (11) controls the feed valve (13) and the bypass valve (14), thereby controlling the start or end of the feed.

6. A method for controlling the extraction of ammonium sulfate saturator according to claim 5, characterized in that: In S2, the analysis results are compared with the set values ​​through the pid parameter control.

7. The method for controlling the material extraction of an ammonium sulfate saturator according to claim 5, characterized in that: The control system (11) controls the feed valve (13) and the bypass valve (14), specifically including: S21, when the ammonium sulfate mother liquor crystal ratio is ≥25%, the control system (11) controls the opening of the feed valve (13), closing the bypass valve (14), and the ammonium sulfate mother liquor in the crystallization tank (3) enters the centrifuge (4) through the centrifuge inlet pipe (9), and the feed begins. The centrifuge (4) performs solid-liquid separation on the ammonium sulfate mother liquor, and the separated filtrate enters the saturator (1) through the centrifuge filtrate pipe (10), and the ammonium sulfate mother liquor crystal ratio gradually decreases; S22, when the feed valve (13) is in an open state and the ammonium sulfate mother liquor ratio is 5% < 25%, the control system (11) controls the feed valve (13) to continue to be opened, and the bypass valve (14) is still closed, and the ammonium sulfate mother liquor in the crystallization tank (3) enters the centrifuge (4) through the centrifuge inlet pipe (9), and the feed continues to be fed. The centrifuge (4) performs solid-liquid separation on the ammonium sulfate mother liquor, and the separated filtrate enters the saturator (1) through the centrifuge filtrate pipe (10), and the ammonium sulfate mother liquor ratio continues to gradually decrease; S23, when the ammonium sulfate mother liquor ratio is ≤5%, the control system (11) controls the bypass valve (14) to be opened, the feed valve (13) to be closed, the ammonium sulfate mother liquor in the crystallization tank (3) to enter the saturator (1) through the mother liquor bypass pipe (8) and the centrifuge filtrate pipe (10) in sequence, the feed is stopped, and the ammonium sulfate mother liquor ratio gradually increases; S24, real-time observation of the gradual increase of the ammonium sulfate mother liquid crystal ratio. When the feed valve (13) is in a closed state and the ammonium sulfate mother liquid crystal ratio is 5% < 25%, the control system (11) controls the bypass valve (14) to continue to be opened, and the feed valve (13) is still closed. The ammonium sulfate mother liquor in the crystallization tank (3) enters the saturator (1) through the mother liquor bypass pipe (8) and the centrifuge filtrate pipe (10) in turn, and the feed is stopped. The ammonium sulfate mother liquid crystal ratio gradually increases.

8. The method for controlling the material extraction of an ammonium sulfate saturator according to claim 5, characterized in that: In step S1 and step S2, anti-overflow measures are taken for the crystallization tank (3) to ensure that the ammonium sulfate mother liquor in the crystallization tank (3) does not overflow. The specific measures are: When the liquid level of the crystallization tank (3) is higher than the height at which the mother liquor overflow pipe (7) is set at the top of the crystallization tank (3), the ammonium sulfate mother liquor above the height at which the mother liquor overflow pipe (7) is set at the top of the crystallization tank (3) passes through the mother liquor overflow pipe (7) and the centrifuge filtrate pipe (10) in sequence and then enters the saturator (1), thereby ensuring that the ammonium sulfate mother liquor in the crystallization tank (3) will not bubble out of the crystallization tank (3) due to an excessively high liquid level.

Images