Ammonium sulfate wastewater treatment system

Abstract

The utility model discloses an ammonium sulfate wastewater treatment system which comprises an ammonium sulfate wastewater storage pool used for collecting ammonium sulfate wastewater, the calcium hydroxide preparation system is used for preparing a calcium hydroxide solution, an evaporator and a first circulating heater and is used for reacting ammonium sulfate wastewater and calcium hydroxide and heating and evaporating; the first crystallizer and the second circulating heater as well as the second crystallizer and the third circulating heater are used for two times of evaporative crystallization, a final concentrated solution is filtered by the filter and then flows into the mother liquor collecting tank to facilitate wastewater treatment, and evaporated ammonia gas is absorbed by the cooling absorption tower and the condensate collecting tank to form ammonia water; and condensate water of the second heat exchanger, the first circulating heater, the second circulating heater and the third circulating heater also flows back to the condensate collecting pool. According to the wastewater treatment system, ammonium sulfate wastewater and a calcium hydroxide solution are distilled and crystallized, so that calcium sulfate and ammonia water can be recovered, and waste utilization is realized.

Description

TECHNICAL FIELD

[0001] The utility model relates to wastewater treatment technical field especially relates to a kind of ammonium sulfate wastewater treatment system and method thereof. BACKGROUND

[0002] When industrial production and using ammonium sulfate, a large amount of ammonium sulfate wastewater will be generated, and ammonium sulfate wastewater can easily cause water environment deterioration, therefore, the discharge of ammonium sulfate wastewater is strictly limited, so how to treat ammonium sulfate wastewater is a technical problem that the skilled in the art urgently needs to solve. At present, ammonium sulfate wastewater is generally mixed with other wastewater, and then treated by activated sludge method or biochemical method, but this can cause ammonia nitrogen in wastewater to exceed the standard, thereby increasing the difficulty of wastewater treatment. SUMMARY

[0003] The technical problem to be solved by the utility model is to provide an ammonium sulfate wastewater treatment system, which distills and crystallizes ammonium sulfate wastewater and calcium hydroxide solution, so that calcium sulfate and ammonia water can be recovered, thereby realizing waste utilization.

[0004] To solve the above technical problems, the technical scheme of the utility model is as follows: an ammonium sulfate wastewater treatment system, comprising

[0005] An ammonium sulfate wastewater storage tank is used to collect ammonium sulfate wastewater, and the ammonium sulfate wastewater storage tank is communicated with the wastewater inlet of a first heat exchanger through a first wastewater conveying pipeline, the wastewater outlet of the first heat exchanger is communicated with the wastewater inlet of a second heat exchanger, the wastewater outlet on the second heat exchanger is communicated with the wastewater inlet of an evaporator through a first liquid inlet pipeline, and the second heat exchanger is further provided with a steam inlet, a steam outlet and a condensate outlet; the bottom of the evaporator is provided with a first bottom circulating pipeline, the first bottom circulating pipeline is communicated with the bottom of the tube side of a first circulating heater, the top of the evaporator is communicated with the steam inlet of the second heat exchanger through a steam recycling pipeline, and the steam outlet of the second heat exchanger is communicated with a steam return main pipe; the top of the tube side of the first circulating heater is communicated with the top of the evaporator through a first top circulating pipeline, and the shell side inlet of the first circulating heater is communicated with a steam supply system; and the shell side outlet of the first circulating heater is communicated with the steam return main pipe.

[0006] a first crystallizer and a second circulation heater, a bottom of the first crystallizer is communicated with a bottom tube passage of the second circulation heater through a second bottom circulation pipeline, a concentrated liquid outlet on the evaporator is communicated with the second bottom circulation pipeline through a first concentrated liquid outflow pipeline, a top of the first crystallizer is communicated with a tube passage top of the second circulation heater through a second top circulation pipeline, and a shell passage inlet of the second circulation heater is communicated with a steam supply system; a shell passage outlet of the second circulation heater is communicated with a steam return main pipeline;

[0007] a second crystallizer and a third circulation heater, a bottom of the second crystallizer is communicated with a bottom tube passage of the third circulation heater through a third bottom circulation pipeline, a concentrated liquid outlet of the first crystallizer is communicated with the third bottom circulation pipeline through a second concentrated liquid outflow pipeline, a top of the second crystallizer is communicated with a tube passage top of the third circulation heater through a third top circulation pipeline, and a shell passage inlet of the third circulation heater is communicated with a steam outlet at the top of the first crystallizer; a shell passage outlet of the third circulation heater and a top steam outlet of the second crystallizer are both communicated with the steam return main pipeline; the steam return main pipeline is communicated with a steam inlet of the first heat exchanger, and an outlet of the first heat exchanger is communicated with a negative pressure system; the third bottom circulation pipeline is connected with a concentrated liquid discharge pipeline, and the concentrated liquid discharge pipeline is connected with a filter and a mother liquor collecting pool;

[0008] a cooling absorption tower and a condensed liquid collecting pool, the steam return main pipeline is communicated with the cooling absorption tower, a bottom of the cooling absorption tower is communicated with the condensed liquid collecting pool through a condensed liquid outflow pipeline, and the condensed liquid collecting pool is communicated with a top spraying port of the cooling absorption tower through a condensed liquid circulation pipeline;

[0009] a condensed water outlet of the second heat exchanger is communicated with an inlet of the third circulation circulation heater through a condensed water outflow pipeline, an outlet of the first circulation heater is communicated with an inlet of the second circulation heater through a first outflow pipeline, an outlet of the second circulation heater is communicated with an inlet of the third circulation heater through a second outflow pipeline, and an outlet of the third circulation heater is communicated with the cooling pool through a third outflow pipeline;

[0010] a calcium hydroxide configuration system for configuring a calcium hydroxide solution, the calcium hydroxide configuration system being communicated with the evaporator, the first crystallizer and the second crystallizer respectively.

[0011] Preferably, the treatment system further comprises a third heat exchanger, a wastewater inlet of the third heat exchanger is communicated with a wastewater outlet of the first heat exchanger, a wastewater outlet of the third heat exchanger is communicated with a wastewater inlet of the second heat exchanger, and an inlet and an outlet of the third heat exchanger are communicated on the third outflow pipeline, so that the third heat exchanger can fully utilize the heat energy in the condensed liquid, further enhance the heat exchange of the ammonium sulfate wastewater, and improve the utilization efficiency of the heat energy.

[0012] Preferably, the wastewater outlet on the second heat exchanger is communicated with the top of the first crystallizer through a second liquid inlet pipeline, so that the wastewater after heat exchange in the second heat exchanger can also partially enter the first crystallizer to perform evaporation crystallization, thereby improving the evaporation crystallization efficiency.

[0013] Preferably, the top of the evaporator is further communicated with the shell side inlet of the first circulating heater through a steam recycling pipeline, so that the energy in the steam evaporated by the evaporator is recycled again, thereby further improving the energy utilization rate.

[0014] Preferably, the calcium hydroxide configuration system comprises a calcium hydroxide preparation tank, wherein a stirring device is arranged in the calcium hydroxide preparation tank, the outlet of the calcium hydroxide preparation tank is communicated with a calcium hydroxide solution storage tank through a calcium hydroxide conveying pipeline, an aeration device is arranged in the calcium hydroxide solution storage tank, and the calcium hydroxide solution storage tank is communicated with the evaporator, the first crystallizer and the second crystallizer through calcium hydroxide solution supply branch pipelines respectively, and a flow meter is arranged on each calcium hydroxide solution supply branch pipeline. The calcium hydroxide is sent into the calcium hydroxide solution storage tank after stirring, and the aeration stirring in the calcium hydroxide solution storage tank avoids precipitation, and then the saturated calcium hydroxide solution can be conveniently sent into the evaporator, the first crystallizer and the second crystallizer, and the flow rate entering the calcium hydroxide solution supply branch pipelines can be accurately controlled, thereby accurately controlling the PH value.

[0015] After the above technical scheme is adopted, the effect of the present application is that: in the treatment system, the wastewater and the calcium hydroxide solution enter the evaporator according to the proportioning, the evaporator and the first circulating heater are circularly heated and evaporated, so that the hot ammonia gas is discharged, the calcium sulfate obtained by the reaction flows into the first crystallizer with the concentrated liquid, and the condensed water flows into the condensate collection tank for collection and is used for circularly absorbing the ammonia gas to form ammonia water, and the concentrated liquid is concentrated and crystallized again in the first crystallizer and the second crystallizer; the P value during the evaporation crystallization is accurately controlled, the generation of the ammonia gas is facilitated, the ammonia gas is formed into ammonia water through spraying absorption, and can be used for power plant desulfurization and denitrification; and the calcium sulfate in the concentrated liquid can be used for gypsum production after filtration, and the liquid can re-enter the conventional sewage treatment system, so that the ammonia in the ammonium sulfate is separated, the difficulty of subsequent sewage treatment is reduced, and the calcium sulfate and the ammonia water can be recovered.

[0016] In addition, the present application also discloses an ammonium sulfate wastewater treatment method, which uses the above-mentioned ammonium sulfate wastewater treatment system and comprises the following steps:

[0017] S1, collecting the sodium sulfate wastewater into an ammonium sulfate wastewater storage tank; and configuring a calcium hydroxide solution by a calcium hydroxide configuration system;

[0018] S2, the ammonium sulfate wastewater is firstly subjected to first heat exchange with steam in the steam return main pipe, and then subjected to second heat exchange with steam discharged from the top of the evaporator in the second heat exchanger, and finally quantitatively enters the evaporator; the calcium hydroxide solution is quantitatively introduced into the evaporator to react with the ammonium sulfate wastewater, and the PH value in the evaporator is monitored to control the PH value between 9-10; the concentrated liquid after reaction circulates between the tube side of the first circulating heater and the evaporator; the steam evaporated from the evaporator enters the shell side of the second circulating heater in part, and enters the second heat exchanger in another part;

[0019] S3, the concentrated liquid after concentration of the evaporator enters the circulating evaporation crystallization process between the first crystallizer and the second circulating heater through the second bottom circulating pipeline, the calcium hydroxide solution is added to the first crystallizer as needed to control the PH value between 9-10, and the shell side of the second circulating heater is also heated by the steam supply system; the concentrated liquid in the tube side of the second circulating heater is fed into the first crystallizer; the condensed liquid of the first circulating heater enters the second circulating heater through the first liquid outlet pipe;

[0020] S4, the steam at the top of the first crystallizer is supplied to the shell side of the third circulating heater; the concentrated liquid after concentration of the first crystallizer enters the circulating evaporation crystallization process between the second crystallizer and the third circulating heater through the third bottom circulating pipeline, and the calcium hydroxide solution is added to the second crystallizer as needed to control the PH value between 9-10; the condensed liquid of the second circulating heater enters the third circulating heater through the second liquid outlet pipe, and the condensed water of the second heat exchanger also enters the third circulating heater through the condensed water outlet pipe;

[0021] S5, the steam at the top of the second crystallizer, the steam of the first circulating heater, the second circulating heater and the third circulating heater are introduced into the steam return main pipe and finally enter the cooling absorption tower after cooling and are collected by the condensed liquid collection pool; the concentrated liquid at the bottom of the second crystallizer is filtered by the filter, and the liquid is collected by the mother liquor collection pool; the liquid outlet of the third circulating heater is communicated with the cooling pool through the third liquid outlet pipe.

[0022] Preferably, the ammonium sulfate wastewater is subjected to enhanced heat exchange after first heat exchange and before second heat exchange, and the ammonium sulfate wastewater after first heat exchange enters the third heat exchanger and is subjected to enhanced heat exchange with the condensed water discharged from the third circulating heater; the cooled water after heat exchange of the third heat exchanger flows into the cooling pool; the condensed water of the first heat exchanger also flows into the third heat exchanger.

[0023] The utility model discloses the effect is: this processing method uses the processing system, and the ammonium sulfate wastewater is reacted with calcium hydroxide, and the ammonia gas and calcium sulfate are separated and recovered through the heating evaporation crystallization mode, and the heat energy is fully utilized while controlling the evaporation crystallization PH of reaction, more conducive to the generation of ammonia gas, also conducive to the crystallization dehydration of calcium sulfate, the ammonia content in the concentrated liquid of final processing is little, thereby not influencing the subsequent sewage treatment. BRIEF DESCRIPTION OF DRAWINGS

[0024] The utility model will be further explained in connection with the drawings and examples.

[0025] Figure 1 It is a part of system diagram in the system of the utility model embodiment;

[0026] Figure 2 It is the system diagram of the remaining part in the system of the utility model embodiment;

[0027] In the drawings: 1, calcium hydroxide preparation jar;2, stirring device;3, calcium hydroxide solution storage tank;4, aeration device;5, ammonium sulfate wastewater storage pool;6, first wastewater delivery pipeline;7, wastewater delivery pump;8, first heat exchanger;9, second heat exchanger;10, first liquid inlet pipeline;11, evaporator;12, first bottom circulation pipeline;13, first circulating heater;14, first top circulation pipeline;15, steam supply system;16, steam reuse pipeline;17, steam return main pipe;18, second liquid inlet pipeline;19, first crystallizer;20, second circulating heater;21, second bottom circulation pipeline;22, first concentrated liquid outflow pipeline;23, second top circulation pipeline;24, second concentrated liquid outflow pipeline;25, third bottom circulation pipeline;26, third top circulation pipeline;27, vacuum pump;28, concentrated liquid discharge pipe;29, filter;30, mother liquor collection pool;31, condensate collection pool;32, third heat exchanger;33, cooling absorption tower;34, condensed water outlet pipe;35, first liquid outlet pipe;36, second liquid outlet pipe;37, third liquid outlet pipe;38, wastewater flow meter;39, calcium hydroxide supply main pipe;40, second crystallizer;41, third circulating heater;42, condensate outlet pipe;43, condensate circulation pipeline. DETAILED DESCRIPTION

[0028] The utility model will be further explained in connection with the drawings and examples.

[0029] As Figure 1 And Figure 2 Indicated, Figure 1 And Figure 2 Indicated a kind of ammonium sulfate wastewater treatment system,

[0030] Wherein, since the system is relatively complex, the system is divided into Figure 1 and Figure 2 Wherein Figure 1 and Figure 2 The same letter in a1, a2, b1, b2, c1, c2, d1, d21, e1, e2, f1, f2, g1, g2, h1, h2, i1, i2 is a pipe, and a1, a2, b1, b2, c1, c2, d1, d21, e1, e2, f1, f2, g1, g2, h1, h2, i1, i2 are two ends of a pipe after cutting, and the actual system is connected to each other.

[0031] The ammonium sulfate wastewater storage tank 5 is used to collect the ammonium sulfate wastewater storage tank 5, the ammonium sulfate wastewater storage tank 5 is communicated with the wastewater inlet of the first heat exchanger 8 through the first wastewater conveying pipe 6, the first wastewater conveying pipe 6 is provided with a wastewater flow meter 38 and a wastewater conveying pump 7, the wastewater outlet of the first heat exchanger 8 is communicated with the wastewater inlet of the second heat exchanger 9, the wastewater outlet of the second heat exchanger 9 is communicated with the wastewater inlet of the evaporator 11 through the first liquid inlet pipe 10, and the second heat exchanger 9 is also provided with a steam inlet, a steam outlet and a condensate outlet; The first heat exchanger 8 and the second heat exchanger 9 are currently conventional tube type heat exchangers.

[0032] The bottom of the evaporator 11 is provided with a first bottom circulating pipe 12, the first bottom circulating pipe 12 is communicated with the tube side bottom of the first circulating heater 13, the top of the evaporator 11 is communicated with the steam inlet of the second heat exchanger 9 through the steam reuse pipe 16, and the steam outlet of the second heat exchanger 9 is communicated with the steam return main pipe 17; The top of the tube side of the first circulating heater 13 is communicated with the top of the evaporator 11 through the first top circulating pipe 14, and the shell side inlet of the first circulating heater 13 is communicated with the steam supply system 15; The shell side outlet of the first circulating heater 13 is communicated with the steam return main pipe 17;

[0033] The first crystallizer 19 and the second circulating heater 20, the bottom of the first crystallizer 19 is communicated with the bottom tube side of the second circulating heater 20 through the second bottom circulating pipe 21, the concentrated liquid outlet on the evaporator 11 is communicated with the second bottom circulating pipe 21 through the first concentrated liquid outlet pipe 22, the top of the tube side of the second circulating heater 20 is communicated with the top of the first crystallizer 19 through the second top circulating pipe 23, and the shell side inlet of the second circulating heater 20 is communicated with the steam supply system 15; The shell side outlet of the second circulating heater 20 is communicated with the steam return main pipe 17;

[0034] A second crystallizer 40 and a third circulation heater 41, the bottom of the second crystallizer 40 is communicated with the bottom tube passage of the third circulation heater 41 through a third bottom circulation pipeline 25, the concentrated liquid outlet of the first crystallizer 19 is communicated with the third bottom circulation pipeline 25 through a second concentrated liquid outflow pipeline 24, the top of the tube passage of the third circulation heater 41 is communicated with the top of the second crystallizer 40 through a third top circulation pipeline 26, the shell passage inlet of the third circulation heater 41 is communicated with the steam outlet of the top of the first crystallizer 19; the shell passage outlet of the third circulation heater 41 and the top steam outlet of the second crystallizer 40 are both communicated with a steam reflux main pipeline 17; the steam reflux main pipeline 17 is communicated with the steam inlet of the first heat exchanger 8, the gas outlet of the first heat exchanger 8 is communicated with a negative pressure system; the third bottom circulation pipeline 25 is connected with a concentrated liquid discharge pipeline 28, the concentrated liquid discharge pipeline 28 is connected with a filter 29 and a mother liquor collecting pool 30;

[0035] A cooling absorption tower 33 and a condensed liquid collecting pool 31, the steam reflux main pipeline 17 is communicated with the cooling absorption tower 33, the bottom of the cooling absorption tower 33 is communicated with the condensed liquid collecting pool 31 through a condensed liquid outflow pipeline 42, the condensed liquid collecting pool 31 is communicated with the top spraying port of the cooling absorption tower 33 through a condensed liquid circulation pipeline 43; the negative pressure system comprises a vacuum pump 27, and a gas-liquid separator is further connected to the negative pressure absorption tower, the gas phase pipe port of the gas-liquid separator is communicated with the vacuum pump 27, and the liquid phase pipe port is communicated with the condensed liquid outflow pipeline 42.

[0036] The condensed water outlet of the second heat exchanger 9 is communicated with the liquid inlet of the third circulation circulation heater through a condensed outflow pipeline 34, the liquid outlet of the first circulation heater 13 is communicated with the liquid inlet of the second circulation heater 20 through a first outflow pipeline 35, the liquid outlet of the second circulation heater 20 is communicated with the liquid inlet of the third circulation heater 41 through a second outflow pipeline 36, and the liquid outlet of the third circulation heater 41 is communicated with the cooling pool through a third outflow pipeline 37;

[0037] A calcium hydroxide preparation system is used to prepare calcium hydroxide solution. The system is connected to an evaporator 11, a first crystallizer 19, and a second crystallizer 40. The system includes a calcium hydroxide preparation tank 1, which is equipped with a stirring device 2. The outlet of the preparation tank 1 is connected to a calcium hydroxide solution storage tank 3 via a calcium hydroxide delivery pipeline. The storage tank 3 is equipped with an aeration device 4. The storage tank 3 is connected to the evaporator 11, the first crystallizer 19, and the second crystallizer 40 via a main calcium hydroxide supply pipeline 39 and branch calcium hydroxide solution supply pipelines. Each branch pipeline is equipped with a flow meter. The calcium hydroxide, after being prepared and stirred, is fed into the storage tank 3. Aeration and stirring in the storage tank 3 prevent sedimentation. The saturated solution can then be easily fed into the evaporator 11, the first crystallizer 19, and the second crystallizer 40. The flow meters allow for precise control of the incoming flow rate and thus the pH value.

[0038] Among them, such as Figure 2 As shown, the treatment system also includes a third heat exchanger 32. The wastewater inlet of the third heat exchanger 32 is connected to the wastewater outlet of the first heat exchanger 8, and the wastewater outlet of the third heat exchanger 32 is connected to the wastewater inlet of the second heat exchanger 9. The liquid inlet and liquid outlet of the third heat exchanger 32 are connected to the third liquid outlet pipe 37. Therefore, the heat energy in the condensate in the third liquid outlet pipe 37 can be fully utilized by the third heat exchanger 32 to further enhance the heat exchange of ammonium sulfate wastewater and improve the heat energy utilization efficiency.

[0039] The wastewater outlet on the second heat exchanger 9 is connected to the top of the first crystallizer 19 via the second inlet pipe 18. In this way, after the ammonium sulfate wastewater is heated by the second heat exchanger 9, a portion of it can flow into the first crystallizer 19, thereby sharing the evaporation and crystallization pressure of the evaporator 11.

[0040] The top of the evaporator 11 is also connected to the shell-side inlet of the first circulating heater 13 via a steam reuse pipeline 16, thus reusing the energy in the steam evaporated by the evaporator 11 and further improving the energy utilization rate.

[0041] In addition, this utility model also discloses a method for treating ammonium sulfate wastewater, which uses the aforementioned ammonium sulfate wastewater treatment system and includes the following steps:

[0042] S1. Collect sodium sulfate wastewater into ammonium sulfate wastewater storage tank 5; prepare calcium hydroxide solution using calcium hydroxide preparation system;

[0043] S2, the ammonium sulfate wastewater is first subjected to first heat exchange with steam in the steam return main pipe 17 in the first heat exchanger 8, then subjected to second heat exchange with steam discharged from the top of the evaporator 11 in the second heat exchanger 9, and finally quantitatively fed into the evaporator 11; the calcium hydroxide solution is quantitatively fed into the evaporator 11 to react with the ammonium sulfate wastewater, and the PH value in the evaporator 11 is monitored to control the PH value between 9 and 10; the concentrated liquid after reaction circulates between the tube side of the first circulating heater 13 and the evaporator 11; the steam evaporated from the evaporator 11 enters the shell side of the second circulating heater 20 in part, and enters the second heat exchanger 9 in another part;

[0044] S3, the concentrated liquid after concentration of the evaporator 11 enters the circulating evaporation crystallization process between the first crystallizer 19 and the second circulating heater 20 through the second bottom circulating pipe 21; the calcium hydroxide solution is added to the first crystallizer 19 as needed to control the PH value between 9 and 10, and the shell side of the second circulating heater 20 is also supplemented with steam from the steam supply system 15 for heating; the concentrated liquid in the tube side of the second circulating heater 20 is fed into the first crystallizer 19; the condensed liquid of the first circulating heater 13 enters the second circulating heater 20 through the first liquid outlet pipe 35;

[0045] S4, the steam at the top of the first crystallizer 19 is supplied to the shell side of the third circulating heater 41; the concentrated liquid after concentration of the first crystallizer 19 enters the circulating evaporation crystallization process between the second crystallizer 40 and the third circulating heater 41 through the third bottom circulating pipe 25, and the calcium hydroxide solution is added to the second crystallizer 40 as needed to control the PH value between 9 and 10; the condensed liquid of the second circulating heater 20 enters the shell side of the third circulating heater 41 through the second liquid outlet pipe 36, and the condensed water of the second heat exchanger 9 also enters the shell side of the third circulating heater 41 through the condensed water outlet pipe 34;

[0046] S5, the steam at the top of the second crystallizer 40, the steam of the first circulating heater 13, the second circulating heater 20 and the third circulating heater 41 are fed into the steam return main pipe 17 and finally enter the cooling absorption tower 33 after cooling, and are collected by the condensed liquid collection pool 31; the concentrated liquid at the bottom of the second crystallizer 40 is filtered by the filter 29, and the liquid is collected by the mother liquor collection pool 30; the liquid outlet of the third circulating heater 41 is communicated with the cooling pool through the third liquid outlet pipe 37. The ammonium sulfate wastewater is subjected to enhanced heat exchange after first heat exchange and before second heat exchange, and is subjected to enhanced heat exchange between the third heat exchanger 32 and the condensed water discharged from the third circulating heater 41; the cooling water after heat exchange of the third heat exchanger 32 flows into the cooling pool; the condensed water of the first heat exchanger 8 also flows into the third heat exchanger 32.

[0047] The above-described embodiments are only preferred embodiments of the present application, and are not intended to limit the scope of the present application. Various modifications and improvements can be made to the technical solutions of the present application without departing from the design spirit of the present application, and all such modifications and improvements shall fall within the protection scope of the present application as defined by the claims.

Claims

1. An ammonium sulfate wastewater treatment system, characterized by: comprising an ammonium sulfate wastewater storage tank for collecting ammonium sulfate wastewater, the ammonium sulfate wastewater storage tank being in communication with a wastewater inlet of a first heat exchanger through a first wastewater conveying pipeline, a wastewater outlet of the first heat exchanger being in communication with a wastewater inlet of a second heat exchanger, a wastewater outlet on the second heat exchanger being in communication with a wastewater inlet of an evaporator through a first liquid inlet pipeline, the second heat exchanger further being provided with a steam inlet, a steam outlet and a condensate outlet; the evaporator being provided with a first bottom circulating pipeline at the bottom, the first bottom circulating pipeline being in communication with a bottom tube side of a first circulating heater, the evaporator being provided with a steam reuse pipeline at the top, the steam reuse pipeline being in communication with the steam inlet of the second heat exchanger, the steam outlet of the second heat exchanger being in communication with a steam return main pipeline; the top tube side of the first circulating heater being in communication with the top of the evaporator through a first top circulating pipeline, an inlet of the shell side of the first circulating heater being in communication with a steam supply system; an outlet of the shell side of the first circulating heater being in communication with the steam return main pipeline; a first crystallizer and a second circulating heater, the bottom of the first crystallizer being in communication with the bottom tube side of the second circulating heater through a second bottom circulating pipeline, a concentrated liquid outlet on the evaporator being in communication with the second bottom circulating pipeline through a first concentrated liquid outlet pipeline, the top tube side of the second circulating heater being in communication with the top of the first crystallizer through a second top circulating pipeline, an inlet of the shell side of the second circulating heater being in communication with the steam supply system; an outlet of the shell side of the second circulating heater being in communication with the steam return main pipeline; a second crystallizer and a third circulating heater, the bottom of the second crystallizer being in communication with the bottom tube side of the third circulating heater through a third bottom circulating pipeline, a concentrated liquid outlet of the first crystallizer being in communication with the third bottom circulating pipeline through a second concentrated liquid outlet pipeline, the top tube side of the third circulating heater being in communication with the top of the second crystallizer through a third top circulating pipeline, an inlet of the shell side of the third circulating heater being in communication with the steam outlet of the top of the first crystallizer; the outlet of the shell side of the third circulating heater and the top steam outlet of the second crystallizer being in communication with the steam return main pipeline; the steam return main pipeline being in communication with the steam inlet of the first heat exchanger, the gas outlet of the first heat exchanger being in communication with a negative pressure system; the third bottom circulating pipeline being connected with a concentrated liquid discharge pipeline, the concentrated liquid discharge pipeline being connected with a filter and a mother liquor collecting tank; a cooling absorption tower and a condensate collecting tank, the steam return main pipeline being in communication with the cooling absorption tower, the bottom of the cooling absorption tower being in communication with the condensate collecting tank through a condensate outlet pipeline, the condensate collecting tank being in communication with a top spraying port of the cooling absorption tower through a condensate circulating pipeline; the condensate outlet of the second heat exchanger being in communication with the liquid inlet of the third circulating heater through a condensate outlet pipeline, the liquid outlet of the first circulating heater being in communication with the liquid inlet of the second circulating heater through a first liquid outlet pipeline, the liquid outlet of the second circulating heater being in communication with the liquid inlet of the third circulating heater through a second liquid outlet pipeline, the liquid outlet of the third circulating heater being in communication with the cooling tank through a third liquid outlet pipeline; A calcium hydroxide preparation system for preparing a calcium hydroxide solution, the calcium hydroxide preparation system being in communication with an evaporator, a first crystallizer and a second crystallizer respectively.

2. An ammonium sulfate wastewater treatment system as claimed in claim 1, characterized by: The treatment system further comprises a third heat exchanger, a wastewater inlet of the third heat exchanger being in communication with a wastewater outlet of the first heat exchanger, a wastewater outlet of the third heat exchanger being in communication with a wastewater inlet of the second heat exchanger, and a liquid inlet and a liquid outlet of the third heat exchanger being in communication on the third liquid outlet pipe.

3. An ammonium sulfate wastewater treatment system as defined in claim 2, wherein: A wastewater outlet on the second heat exchanger is in communication with the top of the first crystallizer through a second liquid inlet pipe.

4. An ammonium sulfate wastewater treatment system as claimed in claim 3, characterized by: The top of the evaporator is further in communication with the shell side inlet of the first circulating heater through a steam reuse pipe.

5. An ammonium sulfate wastewater treatment system as claimed in claim 4, characterized by: The calcium hydroxide preparation system comprises a calcium hydroxide preparation tank, a stirring device being arranged in the calcium hydroxide preparation tank, an outlet of the calcium hydroxide preparation tank being in communication with a calcium hydroxide solution storage tank through a calcium hydroxide delivery pipe, an aeration device being arranged in the calcium hydroxide solution storage tank, and the calcium hydroxide solution storage tank being in communication with the evaporator, the first crystallizer and the second crystallizer respectively through calcium hydroxide solution supply sub-pipes, and a flow meter being arranged on each calcium hydroxide solution supply sub-pipe.

Images