A system for recovering ammonium sulfate waste liquid produced by an enzyme preparation

Abstract

The application discloses an ammonium sulfate waste liquid recovery treatment system generated by an enzyme preparation, which comprises an ammonium sulfate waste liquid tank, wherein the ammonium sulfate waste liquid tank is connected with an evaporator, the evaporator is connected with a reaction kettle, the top end of the reaction kettle is provided with an ammonia gas collecting pipe, the ammonia gas collecting pipe is connected with a liquid collector, the liquid collector is connected with an ammonia gas buffer tank, the ammonia gas buffer tank is connected with an ammonium sulfate reactor through an ammonia gas valve, the ammonium sulfate reactor is designed in two sections, a first reaction tower is connected with a vacuum evaporation kettle, the liquid outlet pipe of the vacuum evaporation kettle is connected with a crystal growing tank and a salting-out process, the reaction kettle is connected with a filter press, the filter press is connected with an evaporator inlet, the solid of the filter press enters a drying system for drying, then enters a high-temperature anaerobic pyrolysis furnace through a feeding system, and the pyrolysis gas outlet of the high-temperature anaerobic pyrolysis furnace is connected with a combustion furnace. The ammonium sulfate waste liquid of the enzyme preparation can be recovered and treated, ammonium sulfate and calcium sulfate can be by-produced, and the equipment investment is small. The waste liquid can be truly zero-emission and recycled.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of enzyme preparation wastewater recovery treatment, and particularly relates to an ammonium sulfate waste liquid recovery treatment system generated by enzyme preparation. BACKGROUND

[0002] In the preparation process of enzymes, ammonium sulfate salting process is widely used to produce various enzyme protein products (ammonium sulfate is used to precipitate proteins), and a large amount of waste liquid containing ammonium sulfate salt is generated. The ammonium sulfate in the waste liquid is generally 18-30%, and there are also 15-25% of proteins, sugars and colloidal substances. At present, the main disposal method is to send the concentrated waste liquid to a hazardous waste disposal plant for disposal. Since the ammonium sulfate waste liquid contains a large amount of nitrogen and sulfur, it is not suitable for incineration disposal, but only for conversion landfill disposal, which has high disposal cost and expense, is difficult to handle, and wastes resources.

[0003] CN 104891724 A discloses a salt-containing wastewater recovery treatment process in the enzyme preparation industry, which comprises the following steps: (1) adding a filter aid to the salt-containing wastewater after extracting enzyme preparation, stirring and heating until boiling, and then filtering with filter cloth after cooling; (2) sending the filter residue to a fertilizer preparation system, and concentrating and crystallizing the filtrate twice, wherein the crystallization product is a salt product, and the secondary mother liquor is concentrated and dried and sent to the fertilizer preparation system or recycled to the process for removing insoluble impurities in step (1); and (3) using the salt product in the above step for salting-out of enzyme preparation. The total recovery rate of salt in the wastewater can reach about 65%, and the use of the recovered product for salting-out can reach the level of using industrial ammonium sulfate for salting-out in terms of the salting-out yield of saccharifying enzyme and the filtration speed.

[0004] The patent document has the following problems: 1. The salt-containing waste liquid after extracting enzyme preparation contains not only ammonium sulfate but also organic matters such as impure proteins and sugars. The addition of a filter aid, stirring and heating until boiling, and then filtering with filter cloth after cooling cannot make the organic matters in it precipitate or flocculate. After heating, it shows high viscosity, difficulty in filtration, inability to centrifuge, many impurities and dark color, which brings great difficulty to production. 2. The ammonium sulfate in the filtrate still contains a large amount of impurities, and the concentration and crystallization effect is very poor due to the high content of sugars and metal ions. Directly using it for fertilizer has too low added value. 3. The recovery rate is low, which cannot meet the current demand.

[0005] The applicant develops a new process route to adapt to the current policy, enterprise and market demand, and pursue high-quality resource regeneration and zero emission. The present application provides a recovery treatment system for the process SUMMARY

[0006] The purpose of this invention is to address the aforementioned technical problems by providing a system for recovering and treating ammonium sulfate waste liquid generated from enzyme preparations. This system can recover and treat ammonium sulfate waste liquid from enzyme preparations, while simultaneously producing ammonium sulfate and calcium sulfate as byproducts. The equipment investment is minimal. It truly achieves zero waste liquid discharge and resource reuse.

[0007] In view of this, the present invention provides a system for recovering and treating ammonium sulfate waste liquid generated from enzyme preparations, including an ammonium sulfate waste liquid tank, which is connected to an evaporator. The bottom outlet of the evaporator is connected to a reaction vessel. A lime feeding hopper is provided on the reaction vessel, and an ammonia collection pipe is provided at the top of the reaction vessel. The ammonia collection pipe is connected to a liquid trap, which is connected to an ammonia buffer tank. The ammonia buffer tank is connected to an ammonia inlet pipe at the bottom of the ammonium sulfate reactor via an ammonia valve. The ammonium sulfate reactor is a two-stage design, the first stage including a first reaction tower. The first reaction tower is filled with packing material. A first dilute sulfuric acid distributor is located at the top of the first reaction tower, connected to the bottom dilute sulfuric acid outlet pipeline of the second reaction tower via a first dilute sulfuric acid pump. The distributor is situated above the packing material. An ammonia gas pipe is located at the top of the first reaction tower, connected to the ammonia gas inlet at the bottom of the second reaction tower. The second reaction tower also contains packing material, and a second dilute sulfuric acid distributor is located at its top, connected to a dilute sulfuric acid tank via a second dilute sulfuric acid pump.

[0008] The bottom discharge pipe of the first reaction tower is connected to the vacuum evaporator, the liquid outlet pipe of the vacuum evaporator is connected to the crystal growth tank and the salting-out process, the liquid outlet pipe of the crystal growth tank is connected to the centrifuge, and the centrifuged material is dried by the drying system to obtain ammonium sulfate product.

[0009] The bottom liquid outlet pipe of the reactor is connected to a filter press, the liquid phase outlet of the filter press is connected to the evaporator inlet, the solids from the filter press enter the drying system for drying, and then enter the high-temperature anaerobic pyrolysis furnace through the feeding system. The pyrolysis gas outlet of the high-temperature anaerobic pyrolysis furnace is connected to a combustion furnace, and the heat energy generated by the combustion furnace is used to heat the high-temperature anaerobic pyrolysis furnace and the drying system. Valves are installed on all connecting pipes.

[0010] In the above scheme, a vacuum tube is installed at the top of the second reaction tower, and the vacuum tube is connected to a vacuum assembly. The vacuum assembly maintains the vacuum state of the entire system.

[0011] In the above scheme, an automatic control valve is installed below the lime feeding hopper.

[0012] In the above scheme, the ammonium sulfate waste liquid tank is connected to the evaporator via a waste liquid pump.

[0013] In the above scheme, the filter press is a plate and frame filter press.

[0014] In the above scheme, the evaporator is a wiped-film evaporator. The evaporation efficiency is higher.

[0015] In the above scheme, the reaction kettle and the crystal growing tank are each provided with a stirring device.

[0016] The ammonium sulfate waste liquid in the waste liquid tank is sent to a wiped-film evaporator for concentration and dehydration to remove most of the water (the water content after dehydration is 40-50%), and the concentrated ammonium sulfate waste liquid is introduced into the reaction kettle from the bottom of the wiped-film evaporator. The lime is slowly and uniformly added into the reaction kettle through a feeding hopper, the stirring speed of the reaction kettle is 45-80 r / min, a liquid trap is provided to ensure the purity of ammonia gas, and the reaction process of the reaction kettle is set to negative pressure, the pressure is controlled at 80-90 KPa (A), and the temperature is controlled at 50-80°C.

[0017] The reacted ammonia gas is directly introduced into the ammonium sulfate reactor after passing through a buffer tank, and the ammonia gas reacts with dilute sulfuric acid (5-30%) to generate ammonium sulfate in the ammonium sulfate reactor. Specifically, the reactor is designed in two stages, the size and packing of the reaction towers of the two-stage reactor are the same, the ammonia gas enters from the bottom of the first reaction tower and reacts with the dilute sulfuric acid pumped from the top of the reactor on the packing from bottom to top. Part of the unreacted ammonia gas enters the second stage of the reactor and continues to react with dilute sulfuric acid. The sulfuric acid in the first and second stages of the reactor is independently worked by using different circulating pumps. After the ammonium sulfate in the first reaction tower is completely reacted, the ammonium sulfate is concentrated to the required concentration in a vacuum evaporation kettle. At this time, the dilute sulfuric acid in the second stage of the reactor is pumped into the first stage for continuous reaction, and new dilute sulfuric acid is supplemented in the second stage, and the cycle is repeated.

[0018] The concentrated ammonium sulfate solution (about 70%) can be directly returned to the salting-out process for direct use. At the same time, ammonium sulfate products can also be generated. Specifically, the concentrated ammonium sulfate solution is introduced into a crystal growing tank for crystallization, the crystal growing time is 1-3 h, and the crystal growing tank is provided with stirring. After the crystal growing meets the requirements, it is introduced into a centrifuge, which can be horizontal or vertical, and the rotating speed is 600-1200 r / min. After the centrifuge is discharged, it is introduced into a drying system, the heat source of which utilizes the waste heat of a combustion furnace, and after drying, it is packaged into ammonium sulfate products for sale.

[0019] The residual liquid in the reaction kettle is introduced into a plate-and-frame filter press to be filtered into a solid, and the liquid phase part is returned to the evaporator wiped-film evaporator for evaporation and concentration. The solid part in the plate-and-frame filter press mainly contains calcium sulfate and organic matter, which is dried and then introduced into a high-temperature cracking and anaerobic decomposition furnace through a feeding system. The heat source of the cracking furnace comes from a combustion furnace, which is indirectly heated, and the heating temperature is 400-700°C, preferably 500°C. The fuel of the combustion furnace is natural gas or waste solvent, etc. The organic gas generated by cracking is sent into the combustion furnace for combustion and to generate heat for the high-temperature cracking furnace and other drying systems.

[0020] After removing organic impurities by cracking furnace, calcium sulfate is obtained, which is cooled and then enters the bunker, and is packed for sale.

[0021] The ammonium sulfate product obtained by the system of the application has the following properties: white crystal appearance, ammonium sulfate content w% of 99.53%, moisture of 0.3%, and no heavy metals such as chromium and lead detected. The ammonium sulfate recovery rate is 95.8%. The product quality meets the relevant standards.

[0022] The calcium sulfate product has the following properties: white granular appearance, ammonium sulfate content w% of 99.12%, moisture of 0.05%, chromium content of 2 ppm, lead content of 2 ppm, and arsenic content of 1 ppm. The calcium sulfate recovery rate is 96.1%. The product quality meets the relevant standards. The application converts the difficult-to-handle ammonium sulfate waste liquid into high-quality ammonium sulfate product and calcium sulfate product. The ammonium sulfate reaches the salting-out standard of the enterprise and can be directly recycled and used in the enterprise, truly realizing resource regeneration and zero discharge. The process equipment is not complex, is conducive to popularization, has a high recovery rate of more than 95%, solves the problem of disposal of hazardous waste of the enterprise, reduces the production and operation cost of the enterprise, and improves the efficiency of the enterprise. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The figure is a process flow diagram of the application.

[0024] Figure 2 The figure is a schematic diagram of the connection structure of the reaction kettle and the ammonium sulfate reactor. DETAILED DESCRIPTION

[0025] The application will be further described below in combination with the drawings and examples.

[0026] Example 1

[0027] The ammonium sulfate waste liquid recovery treatment system produced by the enzyme preparation comprises an ammonium sulfate waste liquid tank 1, the ammonium sulfate waste liquid tank 1 is connected with an evaporator 2 through a waste liquid pump, and the evaporator 2 is preferably a wiped film evaporator. The bottom outlet of the evaporator 2 is connected with a reaction kettle 3, the reaction kettle 3 is provided with a lime feeding hopper 301, an automatic control valve is arranged below the lime feeding hopper 301, the opening degree of the automatic control valve is controlled, so as to control the feeding speed of the lime, and the valve is a prior art and will not be described here. A stirring device is arranged in the reaction kettle, and a heating jacket is arranged outside the reaction kettle.

[0028] The top end of the reaction kettle 3 is provided with an ammonia gas collecting pipe, which is connected with a liquid trap 4 for absorbing liquid in the ammonia gas. The liquid trap 4 is connected with an ammonia gas buffer tank 5, which is connected with an ammonia gas inlet pipe at the bottom of the ammonium sulfate reactor through an ammonia gas valve 6. The ammonium sulfate reactor is designed in two sections. The first section includes a first reaction tower 7, in which a filler 8 is arranged. The filler 8 is arranged in the first reaction tower 7 and a second reaction tower through a filler support. A first dilute sulfuric acid distributor 9 is arranged at the top of the first reaction tower 7. The first dilute sulfuric acid distributor 9 is connected with a dilute sulfuric acid outlet pipe line at the bottom of the second reaction tower 11 of the second section through a first dilute sulfuric acid pump 10. The first dilute sulfuric acid distributor 9 is located above the filler. An ammonia gas pipe at the top end of the first reaction tower 7 is connected with an ammonia gas inlet at the bottom end of the second reaction tower 11 of the second section. The second reaction tower 11 is also provided with the filler 8. A second dilute sulfuric acid distributor 12 is arranged at the top of the second reaction tower 11. The second dilute sulfuric acid distributor 12 is located above the filler 8, and the ammonia gas inlet is located below the filler 8. The second dilute sulfuric acid distributor 12 is connected with a dilute sulfuric acid tank 14 through a second dilute sulfuric acid pump 13. A vacuum pipe is arranged at the top end of the second reaction tower 11, which is connected with a vacuum assembly 19.

[0029] A bottom discharge pipe of the first reaction tower 7 is connected with a reduced pressure evaporation kettle 15. A liquid outlet pipe of the reduced pressure evaporation kettle 15 is connected with a crystal growing tank 16 and a salting process. A liquid outlet pipe of the crystal growing tank 16 is connected with a centrifuge 17. The material after centrifugation is dried by a drying system 18 to obtain an ammonium sulfate product. A stirring device is arranged in the crystal growing tank.

[0030] A kettle bottom liquid discharge pipe of the reaction kettle 3 is connected with a filter press 22, which is preferably a plate and frame filter press. A liquid phase outlet of the filter press is connected with an inlet of the evaporator 2. The solid of the filter press 22 is dried by a drying system 22, and then enters a high-temperature anaerobic pyrolysis furnace 20 through a feeding system. A pyrolysis gas outlet of the high-temperature anaerobic pyrolysis furnace 20 is connected with a combustion furnace 21. The heat energy generated by the combustion furnace 21 is used for heating the high-temperature anaerobic pyrolysis furnace and the drying system. Valves should be correspondingly arranged on all the connecting pipes.

[0031] Application example

[0032] According to the system, the feeding is 1000 kg of ammonium sulfate waste liquid. The analysis and detection show that the ammonium sulfate content in the waste liquid is 25%, and the waste liquid contains protein, sugar and colloidal substance 20%, and the rest is water.

[0033] The enzyme preparation ammonium sulfate waste liquid is concentrated to remove most of the water. The water content of the concentrated waste water is 40%.

[0034] The lime 110 kg is slowly added (the molar ratio of the amount of lime added to the ammonium sulfate in the ammonium sulfate waste liquid is 1-1.1:1). The reaction equation is as follows:

[0035] CaO + (NH4)2SO4 = CaSO4 + 2NH3↑ + H2O

[0036] The lime is added while stirring at a speed of 60 r / min, and the reaction kettle is set to negative pressure during the reaction process, with the pressure controlled at 90 KPa (A) and the temperature controlled at 60°C. The ammonia gas after the reaction is directly introduced into the ammonium sulfate reactor after passing through a buffer tank, and in the ammonium sulfate reaction, the ammonia gas reacts with 20% dilute sulfuric acid to generate ammonium sulfate. The ammonium sulfate is introduced into a concentration crystallizer to be concentrated to a concentration of 70%. At this time, the dilute sulfuric acid at the bottom of the second reactor is pumped into the first stage for continuous reaction, and new dilute sulfuric acid is supplemented to the second stage, so as to circulate.

[0037] The 70% ammonium sulfate solution after concentration can be directly returned to the salting-out process for direct use. If ammonium sulfate products are to be produced, the ammonium sulfate solution after concentration is introduced into a crystal growing tank for crystallization, and the crystal growing time is 2 h. After crystal growing, the solution is introduced into a centrifuge, which is a horizontal chamber with a rotation speed of 800 r / min. After discharge, the solution is introduced into a drying system, which uses the waste heat of a combustion furnace as a heat source. After drying, the ammonium sulfate product is packaged and sold. 239.5 kg of ammonium sulfate product is obtained, which is white crystals, with an ammonium sulfate content of 99.53%, a moisture content of 0.3%, and no chromium, lead and other heavy metals detected. The ammonium sulfate recovery rate is 95.8%.

[0038] The cracking furnace is indirectly heated, and the heating temperature is 500°C. The organic gas generated by cracking is sent to a combustion furnace for combustion to generate heat for heating the high-temperature cracking furnace and other drying systems.

[0039] After removing the organic impurities by the cracking furnace, calcium sulfate is obtained, which is cooled and then introduced into a silo for packaging and sale. 247.52 kg of calcium sulfate product is obtained, which is white particles, with an ammonium sulfate content of 99.12%, a moisture content of 0.05%, a chromium content of 2 ppm, a lead content of 2 ppm, and an arsenic content of 1 ppm. The calcium sulfate recovery rate is 96.7%. The product meets the relevant product quality standards.

[0040] The above only describes the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent replacements or changes to the technical solutions and inventive concepts of the present application within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. An ammonium sulfate waste liquid recovery treatment system produced by an enzyme preparation, comprising an ammonium sulfate waste liquid tank connected with an evaporator, a bottom outlet of the evaporator connected with a reaction kettle, the reaction kettle provided with a lime feeding hopper, an ammonia gas collecting pipe arranged at the top end of the reaction kettle, the ammonia gas collecting pipe connected with a liquid trap, the liquid trap connected with an ammonia gas buffer tank, the ammonia gas buffer tank connected with an ammonia gas inlet pipe at the bottom of an ammonium sulfate reactor, the ammonium sulfate reactor designed in two sections, the first section comprising a first reaction tower provided with a filler, a first dilute sulfuric acid distributor arranged at the top of the first reaction tower, the first dilute sulfuric acid distributor connected with a dilute sulfuric acid outlet pipe line at the bottom of a second reaction tower of the second section through a first dilute sulfuric acid pump, the dilute sulfuric acid distributor arranged above the filler, an ammonia gas pipe arranged at the top end of the first reaction tower connected with an ammonia gas inlet at the bottom end of the second reaction tower, the second reaction tower also provided with a filler, a second dilute sulfuric acid distributor arranged at the top of the second reaction tower, the second dilute sulfuric acid distributor connected with a dilute sulfuric acid tank through a second dilute sulfuric acid pump; a bottom discharge pipe of the first reaction tower connected with a reduced pressure evaporation kettle, a liquid outlet pipe of the reduced pressure evaporation kettle connected with a crystal growing tank and a salting-out process, a liquid outlet pipe of the crystal growing tank connected with a centrifuge, the material after centrifugation dried through a drying system to obtain an ammonium sulfate product; a kettle bottom liquid discharge pipe of the reaction kettle connected with a filter press, a liquid phase outlet of the filter press connected with an evaporator inlet, the solid of the filter press entering a drying system for drying, then entering a high-temperature anaerobic pyrolysis furnace through a feeding system, a pyrolysis gas outlet of the high-temperature anaerobic pyrolysis furnace connected with a combustion furnace, the heat energy generated by the combustion furnace used for heating of the high-temperature anaerobic pyrolysis furnace and the drying system; a vacuum pipe arranged at the top end of the second reaction tower, the vacuum pipe connected with a vacuum assembly, the evaporator being a wiped film evaporator.

2. The system for recovering ammonium sulfate waste liquor produced by the enzyme preparation according to claim 1, characterized by: An automatic control valve is arranged below the lime feeding hopper.

3. The system for recovering ammonium sulfate waste liquor produced by the enzyme preparation according to claim 2, characterized by: The ammonium sulfate waste liquid tank is connected with the evaporator through a waste liquid pump.

4. The system for recovering ammonium sulfate waste liquor produced by the enzyme preparation according to claim 3, characterized by: The filter press is a plate and frame filter press.

5. The system for recovering ammonium sulfate waste liquor produced by the enzyme preparation according to claim 4, characterized by: Stirring devices are arranged in the reaction kettle and the crystal growing tank.

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