Ammonium sulfate crystallization system based on utilization of waste heat of distilled ammonia steam

Abstract

The invention discloses an ammonium sulfate crystallization system based on waste heat utilization of distilled ammonia vapor, and belongs to the technical field of ammonium sulfate crystallization. Ammonia vapor generated when an ammonia still works enters a mother liquor heat exchanger through a pipeline for heat exchange, and mother liquor input by a mother liquor circulating pump and / or a supply pump is received in the mother liquor heat exchanger; the mother liquor subjected to heat exchange in the mother liquor heat exchanger is guided into the crystallizer; ammonia gas heat of the ammonia water distillation system exchanges heat with mother liquor of the crystallizer of the ammonium sulfate device, and steam consumption in the production process of the crystallizer is effectively reduced through the heat. The purposes of reducing cost, increasing efficiency and improving quality are achieved; the temperature change and flow of each phase before and after heat exchange are monitored, when the difference value between the mother liquor temperature after heat exchange and the expected mother liquor temperature is large, a flow value is calculated, the flow is rapidly adjusted through an adjusting valve B, rapid reaction is achieved, the heat exchange adjusting period is shortened, and the heat exchange efficiency is improved. The temperature of the mother liquor can quickly meet the requirement, and the crystallization efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of ammonium sulfate crystallization, and specifically relates to an ammonium sulfate crystallization system based on utilization of waste heat of ammonia vapor from ammonia evaporation. Background Art

[0002] In recent years, with the increasing requirements for energy conservation and emission reduction, it is more important to reasonably and effectively utilize waste heat in the production process and reduce production costs. The raw gas in the coking process is pumped by the gas blower to the purification and recovery system for treatment, and the residual ammonia water produced needs to be distilled. The gas phase temperature of the ammonia after distillation is about 100°C. The mother liquor of the ammonium sulfate crystallizer is generally around 45°C. During the crystallization and concentration process, the mother liquor needs to be continuously heated to meet the needs of continuous production. When producing ammonium sulfate products, steam is required as a heat source for evaporation and concentration to obtain large-particle crystalline products. This leads to a waste of heat and increases energy consumption, which does not meet the needs of energy conservation and emission reduction.

[0003] In order to solve the above problems, an ammonium sulfate crystallization system is provided which can fully utilize the waste heat of ammonia vapor from ammonia evaporation, and the present invention provides the following technical solutions. Summary of the invention

[0004] The purpose of the present invention is to provide an ammonium sulfate crystallization system based on the utilization of waste heat of ammonia vapor from ammonia evaporation, so as to fully utilize the waste heat of ammonia vapor from ammonia evaporation and realize full utilization of energy.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] An ammonium sulfate crystallization system based on the utilization of waste heat of ammonia vapor during ammonia evaporation, wherein the ammonia vapor generated during the operation of the ammonia evaporation tower enters the mother liquid heat exchanger through a pipeline for heat exchange, and the ammonia vapor after heat exchange is sent to the acid washing tower, and the condensed ammonia water generated after heat exchange in the mother liquid heat exchanger is transmitted through a pipeline into a condensate tank, and the condensed ammonia water in the condensate tank is pumped into a crystallizer or a mother liquid circulation tank by a condensate pump;

[0007] The mother liquid heat exchanger receives the mother liquid input by the mother liquid circulation pump and / or the supply pump, and the mother liquid that completes the heat exchange in the mother liquid heat exchanger is introduced into the crystallizer;

[0008] A regulating valve A is provided on the mother liquid pipeline before entering the mother liquid heat exchanger;

[0009] A regulating valve B is provided on the ammonia vapor pipeline before entering the mother liquid heat exchanger.

[0010] Furthermore, a baffle is provided in the condensate tank, which divides the condensate tank into two parts. The condensed ammonia water produced after heat exchange in the mother liquid heat exchanger is transmitted through a pipeline into one part of the condensate tank, and the condensed ammonia water enters the other part through overflow. The other part is connected to the inlet of the condensate pump, and the condensate pump is turned on according to the liquid level.

[0011] Furthermore, the regulating method of the regulating valve B comprises the following steps:

[0012] S1, using temperature sensors to detect the temperature T1 of ammonia vapor entering the mother liquid heat exchanger, the temperature T2 of ammonia vapor discharged from the mother liquid heat exchanger, the temperature T3 of condensed ammonia water discharged from the mother liquid heat exchanger, the temperature T4 of mother liquid entering the mother liquid heat exchanger, and the temperature T5 of mother liquid discharged from the mother liquid heat exchanger;

[0013] The flow rate Q1 of the condensed ammonia water discharged from the mother liquid heat exchanger and the flow rate Q2 of the mother liquid entering the mother liquid heat exchanger are detected by the flow sensor;

[0014] The flow rate Q3 of ammonia vapor entering the mother liquid heat exchanger and the flow rate Q4 of ammonia vapor exiting the mother liquid heat exchanger are detected by flow sensors;

[0015] S2. When |T6-T5|>Ty1, a flow value Q3y is calculated according to |T6-T5|*C1*Q2=Q3y*C3*T1*β, and step S3 is executed;

[0016] Where C1 is the specific heat capacity of the mother liquid; Where C2 is the specific heat capacity of the condensed ammonia water; C3 is the specific heat capacity of the ammonia vapor; Ty1 is the preset temperature value;

[0017] Where T6 is the desired mother liquor temperature exiting the mother liquor heat exchanger;

[0018] S3, correspondingly increase or decrease the opening of the regulating valve B, so that the ammonia vapor flow entering the mother liquid heat exchanger increases or decreases by Q3y;

[0019] S4. Complete the opening adjustment of the regulating valve B. After the preset time t2, continue with steps S2-S3.

[0020] Furthermore, when |T6-T5|≤Ty1 is satisfied, the opening of the regulating valve B is increased or decreased accordingly at every preset time ty until |T6-T5|≤Ty2 is satisfied, where Ty2 is a preset temperature value less than Ty1; ty is a preset time value.

[0021] Furthermore, the calculation method of β is:

[0022] When the ammonium sulfate crystallization system is running, the (Q1*T3*C2+Q4*T2*C3) / Q3*T1*C3 value is collected once every preset time, and the value is marked as a. After obtaining a group of several a values ​​in sequence, the typical value of this group of several a values ​​is calculated, and the typical value is β.

[0023] Further, the instantaneous heat change R1 of the mother liquid entering and leaving the mother liquid heat exchanger is calculated according to the formula R1=Q2*(T5-T4)*C1;

[0024] The instantaneous heat change R2 of ammonia vapor entering and leaving the mother liquid heat exchanger is calculated according to the formula Q1*T3*C2+Q4*T2*C3+R2=Q3*T1*C3;

[0025] The instantaneous heat change R1 and the instantaneous heat change R2 are continuously monitored, and after integrating R1 and R2 respectively, the mother liquid heat change R11 and the ammonia vapor heat change R21 within the continuous time range t1 are obtained;

[0026] When |R21-R11| / min(R21, R11)>α, it is considered that there may be a situation of condensed ammonia backflow, and screening and maintenance should be carried out in time;

[0027] Where α is the preset proportionality coefficient.

[0028] Beneficial effects of the present invention:

[0029] 1. The present invention utilizes the heat of ammonia gas in the ammonia distillation system to exchange heat with the mother liquor of the crystallizer of the ammonium sulfate device, and utilizes this heat to effectively reduce the steam consumption in the crystallizer production process. Ammonia gas condensate is also utilized to control the acidity of the crystallizer mother liquor, thereby reducing the free acid content of the ammonium sulfate product, thereby achieving the purpose of reducing costs, increasing efficiency, and improving quality.

[0030] 2. The present invention monitors the temperature changes and flow rates of each phase before and after heat exchange. When the temperature difference between the mother liquor after heat exchange and the expected mother liquor temperature is large, a flow value is calculated and the flow rate is quickly adjusted through the regulating valve B. This can achieve rapid response, shorten the heat exchange adjustment cycle, improve the adjustment efficiency, enable the mother liquor temperature to quickly reach the requirements, and improve the crystallization efficiency.

[0031] 3. The present invention determines whether the discharge amount of condensed ammonia water is normal by analyzing the heat changes of each phase and the conservation of energy during the heat exchange process. When the condensed ammonia water flows back, it can be discovered in time, so that maintenance can be carried out in time to prevent further expansion of faults and losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below in conjunction with the accompanying drawings.

[0033] Figure 1The present invention is a simplified structural schematic diagram of an ammonium sulfate crystallization system based on the utilization of waste heat of ammonia vapor from ammonia evaporation. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] An ammonium sulfate crystallization system based on the utilization of waste heat from ammonia evaporation, such as Figure 1 As shown, it includes an ammonia still tower. The high-temperature ammonia vapor generated when the ammonia still tower is working enters the mother liquid heat exchanger 1 through a pipeline for heat exchange. The ammonia vapor after heat exchange is sent to the acid washing tower. The condensed ammonia water generated after heat exchange in the mother liquid heat exchanger 1 is transmitted through a pipeline into the condensate tank 2. The condensed ammonia water in the condensate tank 2 is pumped into the crystallizer or the mother liquid circulation tank by the condensate pump 3;

[0037] In one embodiment of the present invention, a baffle is provided in the condensate tank 2, which divides the condensate tank 2 into two parts, wherein the condensed ammonia water produced after heat exchange in the mother liquid heat exchanger 1 is transmitted through a pipeline into one part of the condensate tank 2, and the condensed ammonia water enters the other part through overflow, and the other part is connected to the inlet of the condensate pump 3. The condensate pump 3 can be turned on according to the liquid level to send the ammonia water to the crystallizer or the mother liquid circulation tank to produce ammonium sulfate;

[0038] The mother liquid heat exchanger 1 receives the mother liquid input by the mother liquid circulation pump and / or the supply pump, and the mother liquid that completes the heat exchange in the mother liquid heat exchanger 1 is introduced into the crystallizer;

[0039] The mother liquid circulation pump is used to pump the mother liquid in the mother liquid circulation tank into the mother liquid heat exchanger 1;

[0040] The supply pump is used to pump the mother liquor in the crystallizer into the mother liquor heat exchanger 1;

[0041] A regulating valve A is provided on the mother liquid pipeline before entering the mother liquid heat exchanger 1, which can adjust the amount of mother liquid entering the mother liquid heat exchanger 1 according to production needs;

[0042] A regulating valve B is provided on the ammonia vapor pipeline before entering the mother liquid heat exchanger 1, which can adjust the amount of ammonia vapor entering the mother liquid heat exchanger 1 according to the temperature of the mother liquid after heat exchange.

[0043] Example 2

[0044] In this embodiment, based on the embodiment 1, a method for adjusting the amount of ammonia vapor and the amount of mother liquid entering the mother liquid heat exchanger 1 is further disclosed, which specifically includes the following steps:

[0045] S1, detecting the temperature T1 of ammonia vapor entering the mother liquid heat exchanger 1, the temperature T2 of ammonia vapor discharged from the mother liquid heat exchanger 1, the temperature T3 of condensed ammonia water discharged from the mother liquid heat exchanger 1, the temperature T4 of mother liquid entering the mother liquid heat exchanger 1, and the temperature T5 of mother liquid discharged from the mother liquid heat exchanger 1 by temperature sensors;

[0046] The flow rate Q1 of the condensed ammonia water discharged from the mother liquid heat exchanger 1 and the flow rate Q2 of the mother liquid entering the mother liquid heat exchanger 1 are detected by the flow sensor;

[0047] The flow rate Q3 of ammonia gas entering the mother liquid heat exchanger 1 and the flow rate Q4 of ammonia gas discharged from the mother liquid heat exchanger 1 are detected by flow sensors;

[0048] S2. When |T6-T5|≤Ty1 is established, the opening of the regulating valve B is increased or decreased correspondingly at every preset time ty until |T6-T5|≤Ty2 is established, where Ty2 is a preset temperature value less than Ty1. Specifically, when T6 is greater than T5, the opening of the regulating valve B needs to be increased. Conversely, when T6 is less than T5, the opening of the regulating valve B needs to be decreased; where ty is a preset time value, and Ty1 is a preset temperature value;

[0049] Wherein T6 is the desired temperature of the mother liquid discharged from the mother liquid heat exchanger 1;

[0050] When |T6-T5|>Ty1, a flow value Q3y is calculated according to |T6-T5|*C1*Q2=Q3y*C3*T1*β, and step S3 is executed;

[0051] Where C1 is the specific heat capacity of the mother liquor; Where C2 is the specific heat capacity of the condensed ammonia water; C3 is the specific heat capacity of the ammonia vapor;

[0052] S3, correspondingly increase or decrease the opening of the regulating valve B, so that the ammonia vapor flow entering the mother liquid heat exchanger 1 increases or decreases Q3y accordingly;

[0053] Specifically, when T6 is greater than T5, the opening of the regulating valve B needs to be increased, and conversely, when T6 is less than T5, the opening of the regulating valve B needs to be reduced;

[0054] S4. Complete the opening adjustment of the regulating valve B. After the preset time t2, continue with steps S2-S3.

[0055] The calculation method of β is:

[0056] When the ammonium sulfate crystallization system is running, the (Q1*T3*C2+Q4*T2*C3) / Q3*T1*C3 value is collected every preset time. For the convenience of expression, the value is marked as a. After obtaining a group of a values ​​in sequence, the typical value of this group of a values ​​is calculated, and the typical value is β;

[0057] The typical value may be the average or median of a group of several a values.

[0058] The present invention monitors the temperature change and flow rate of each phase before and after heat exchange. When the difference between the mother liquor temperature after heat exchange and the expected mother liquor temperature is large, a flow value is calculated and the flow rate is quickly adjusted through the regulating valve B. This can achieve rapid response, shorten the heat exchange adjustment cycle, improve the adjustment efficiency, enable the mother liquor temperature to quickly reach the requirement, and improve the crystallization efficiency.

[0059] Example 3

[0060] Based on Example 2, this example further discloses a method for identifying the backflow of condensed ammonia water, which is as follows:

[0061] The instantaneous heat change R1 of the mother liquid entering and leaving the mother liquid heat exchanger 1 is calculated according to the formula R1=Q2*(T5-T4)*C1;

[0062] The instantaneous heat change R2 of the ammonia vapor entering and leaving the mother liquid heat exchanger 1 is calculated according to the formula Q1*T3*C2+Q4*T2*C3+R2=Q3*T1*C3;

[0063] The instantaneous heat change R1 and the instantaneous heat change R2 are continuously monitored, and after integrating R1 and R2 respectively, the mother liquid heat change R11 and the ammonia vapor heat change R21 within the continuous time range t1 are obtained;

[0064] When |R21-R11| / min(R21, R11)>α, it is considered that there may be a situation of condensed ammonia backflow, and screening and maintenance should be carried out in time;

[0065] Wherein α is a preset proportional coefficient, and specifically, the specific value of α is related to the heat exchange efficiency of the mother liquid heat exchanger 1;

[0066] This embodiment determines whether the discharge amount of condensed ammonia water is normal by analyzing the heat changes of each phase and the conservation of energy during the heat exchange process. When the condensed ammonia water flows back, the present invention can discover it in time, so as to carry out maintenance in time and prevent further expansion of faults and losses.

[0067] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. An ammonium sulfate crystallization system based on the utilization of waste heat from ammonia vapor, characterized in that: Ammonia vapor generated when the ammonia evaporation tower is working enters the mother liquid heat exchanger (1) through a pipeline for heat exchange, and the ammonia vapor after heat exchange is sent to the acid washing tower. Condensed ammonia water generated after heat exchange in the mother liquid heat exchanger (1) is transmitted through a pipeline into the condensate tank (2), and the condensed ammonia water in the condensate tank (2) is pumped into the crystallizer or the mother liquid circulation tank by the condensate pump (3); The mother liquid heat exchanger (1) receives the mother liquid input by the mother liquid circulation pump and / or the supply pump, and the mother liquid that has completed heat exchange in the mother liquid heat exchanger (1) is introduced into the crystallizer; A regulating valve A is provided on the mother liquid pipeline before entering the mother liquid heat exchanger (1); A regulating valve B is provided on the ammonia vapor pipeline before entering the mother liquid heat exchanger (1).

2. The ammonium sulfate crystallization system based on the utilization of waste heat of ammonia vapor according to claim 1, characterized in that: The condensate tank (2) is provided with a baffle plate, which divides the condensate tank (2) into two parts. The condensed ammonia water generated after heat exchange in the mother liquid heat exchanger (1) is transmitted through a pipeline into one part of the condensate tank (2), and the condensed ammonia water enters the other part through overflow. The other part is connected to the inlet of the condensate pump (3), and the condensate pump (3) is turned on according to the liquid level.

3. The ammonium sulfate crystallization system based on the utilization of waste heat of ammonia vapor according to claim 1, characterized in that: The regulating method of the regulating valve B comprises the following steps: S1, detecting, by means of temperature sensors, the temperature T1 of ammonia vapor entering the mother liquid heat exchanger (1), the temperature T2 of ammonia vapor discharged from the mother liquid heat exchanger (1), the temperature T3 of condensed ammonia water discharged from the mother liquid heat exchanger (1), the temperature T4 of mother liquid entering the mother liquid heat exchanger (1), and the temperature T5 of mother liquid discharged from the mother liquid heat exchanger (1); The flow rate Q1 of the condensed ammonia water discharged from the mother liquid heat exchanger (1) and the flow rate Q2 of the mother liquid entering the mother liquid heat exchanger (1) are detected by means of flow sensors; The flow rate Q3 of the ammonia gas entering the mother liquid heat exchanger (1) and the flow rate Q4 of the ammonia gas leaving the mother liquid heat exchanger (1) are detected by means of flow sensors; S2. When |T6-T5|>Ty1, a flow value Q3y is calculated according to |T6-T5|*C1*Q2=Q3y*C3*T1*β, and step S3 is executed; Where C1 is the specific heat capacity of the mother liquid; Where C2 is the specific heat capacity of the condensed ammonia water; C3 is the specific heat capacity of the ammonia vapor; Ty1 is the preset temperature value; Wherein T6 is the desired temperature of the mother liquid discharged from the mother liquid heat exchanger (1); S3, correspondingly increase or decrease the opening of the regulating valve B, so that the ammonia vapor flow entering the mother liquid heat exchanger (1) increases or decreases Q3y accordingly; S4. Complete the opening adjustment of the regulating valve B. After the preset time t2, continue with steps S2-S3.

4. The ammonium sulfate crystallization system based on the utilization of waste heat of ammonia vapor according to claim 3 is characterized in that: When |T6-T5|≤Ty1 is established, the opening of the regulating valve B is increased or decreased accordingly at preset time intervals ty until |T6-T5|≤Ty2 is established, where Ty2 is a preset temperature value less than Ty1; ty is a preset time value.

5. The ammonium sulfate crystallization system based on the utilization of waste heat of ammonia vapor according to claim 3, characterized in that: The calculation method of β is: When the ammonium sulfate crystallization system is running, the (Q1*T3*C2+Q4*T2*C3) / Q3*T1*C3 value is collected once every preset time, and the value is marked as a. After obtaining a group of several a values ​​in sequence, the typical value of this group of several a values ​​is calculated, and the typical value is β.

6. The ammonium sulfate crystallization system based on the utilization of waste heat from ammonia vapor according to claim 1, characterized in that: The instantaneous heat change R1 of the mother liquid entering and leaving the mother liquid heat exchanger (1) is calculated according to the formula R1=Q2*(T5-T4)*C1; The instantaneous heat change R2 of the ammonia vapor entering and leaving the mother liquid heat exchanger (1) is calculated according to the formula Q1*T3*C2+Q4*T2*C3+R2=Q3*T1*C3; The instantaneous heat change R1 and the instantaneous heat change R2 are continuously monitored, and after integrating R1 and R2 respectively, the mother liquid heat change R11 and the ammonia vapor heat change R21 within the continuous time range t1 are obtained; When |R21-R11| / min(R21, R11)>α, it is considered that there may be a situation of condensed ammonia backflow, and screening and maintenance should be carried out in time; Where α is the preset proportionality factor.

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