Ammonium chloride concentration method and device for producing agricultural monopotassium phosphate by extraction method

Abstract

The invention discloses an ammonium chloride concentration method and device for producing agricultural monopotassium phosphate through an extraction method, and relates to the technical field of monopotassium phosphate production. Ammonium chloride in an ammonium chloride liquid storage tank is pumped into an ammonium chloride liquid preheater through an ammonium chloride delivery pump to be preheated, heated through a first-stage heater after preheating is completed and then enters a first-stage separation chamber to be evaporated, and a liquid phase is circularly concentrated to index concentration through a first-stage circulating pump, added into a second-stage heater through a regulating valve to be heated and concentrated and fed into a second-stage separation chamber to be evaporated; and the concentration density reaches the index through a secondary circulating pump, and is cooled and crystallized through a concentrated discharging pump. Ammonium chloride is preheated, heated, separated, evaporated and subjected to liquid phase circulation concentration, secondary heating, separated, evaporated and concentrated to reach the high concentration, cooling, crystallization and drying are conducted, outer pipe steam is subjected to heat exchange and cooling in primary heating to become condensate water, the condensate water enters the preheating process again, waste heat is recycled, and waste heat recycling is achieved. The utilization rate of steam is greatly improved, and meanwhile, the concentration efficiency of ammonium chloride is improved.

Description

Technical Field

[0001] The invention relates to the technical field of potassium dihydrogen phosphate production, and in particular to an ammonium chloride concentration method and a device for producing agricultural potassium dihydrogen phosphate by an extraction method. Background Art

[0002] In agricultural applications, potassium dihydrogen phosphate has stable chemical properties, is odorless, tasteless, non-toxic, easily soluble in water, has low hygroscopicity, does not clump, and does not contain non-nutritional ions that can accumulate in the soil and are harmful to crops. It is suitable for various soils and crops. Potassium dihydrogen phosphate is a high-concentration phosphorus-potassium compound fertilizer, a high-quality chlorine-free potassium fertilizer, and an important plant growth regulator. Potassium dihydrogen phosphate has an extremely low salt value and is an ideal foliar fertilizer. It can be widely used for spreading, root soaking, seed dressing, irrigation, and foliar spraying. It has significant effects on accelerating grain filling, promoting metabolism, resisting dry hot winds, and preventing lodging. It is used as a base fertilizer for crops and a foliar spray fertilizer for crops in the middle and late stages. When used for foliar spraying, the absorption and utilization rate is as high as 80-90%, and it is widely used in various grains and cash crops. It has a very good effect on increasing the sweetness and improving the taste of fruits, especially for chlorine-sensitive crops such as tobacco, bridges, tea, and flowers. With the development of facility agriculture and water-saving agriculture, the application of potassium dihydrogen phosphate in agriculture will develop rapidly. It is the most in-demand high-purity phosphorus and potassium fertilizer product in the current modern facility agriculture production market.

[0003] Currently, dipotassium phosphate is produced by organic extraction. The extraction method is a method of selectively using a certain solvent for preparation through a phase transfer process based on the different solubility characteristics of a substance in different solvents.

[0004] In the presence of an organic phase (M), CL- in a mixed solution of potassium chloride and phosphoric acid is extracted into the organic phase (M), and the potassium dihydrogen phosphate solution and M·CL are separated and crystallized from the aqueous phase. The product potassium dihydrogen phosphate is obtained through washing, concentration and drying, and the mother liquor is recycled after separation; M·CL is stripped from the organic phase by a stripping agent (S), the extracting agent (M) is recycled in the process, and S·CL is processed into an ammonium chloride product.

[0005] The main reaction of extraction is (M is the extractant):

[0006] H3PO4+KCL+H20+M (有机相) =M·CL (有机相) +KH2PO4+H2O

[0007] The main reaction of stripping is (S is stripping agent):

[0008] M·CL+S+H2O=S·CL+M (有机相) +H20

[0009] The commonly used stripping agent is gaseous ammonia, so the organic phase containing the extractant overflows into the stripping reaction tank, reacts with the stripping agent to generate ammonium chloride liquid and the extractant, and the generated ammonium chloride liquid is sent to the ammonium chloride liquid storage tank of the ammonium chloride concentrator. The ammonium chloride in the mixed solution is sent to the ammonium chloride liquid storage tank of the ammonium chloride concentrator through an underflow pump, and the ammonium chloride concentrator concentrates and crystallizes it to obtain an ammonium chloride product.

[0010] In the actual production process, steam is used for evaporation and concentration, but there is a problem of low evaporation efficiency and waste of steam. Therefore, there is an urgent need for an ammonium chloride concentration method and device for producing agricultural potassium dihydrogen phosphate by extraction to solve the problems of high production cost, low production efficiency and high energy consumption. Summary of the invention

[0011] The object of the present invention is to provide an ammonium chloride concentration method and a device for producing agricultural potassium dihydrogen phosphate by extraction method.

[0012] The scheme of the present invention is:

[0013] A method for concentrating ammonium chloride for producing agricultural potassium dihydrogen phosphate by extraction method comprises the following steps:

[0014] In the production process of potassium dihydrogen phosphate, the organic phase containing the extraction phase overflows into the stripping reaction tank, reacts with the stripping agent to generate ammonium chloride liquid and the extraction agent, the ammonium chloride in the generated mixed solution has a large density, and is sent to the ammonium chloride liquid storage tank of the ammonium chloride concentration device through an underflow pump, and the extraction agent has a small density and overflows into the extraction agent storage tank for reuse; the ammonium chloride concentration device heats the ammonium chloride in a vacuum concentration and cools and crystallizes it;

[0015] The ammonium chloride in the ammonium chloride liquid storage tank is pumped into the ammonium chloride liquid preheater for preheating through the ammonium chloride delivery pump. After the preheating is completed, it is heated by the first-level heater and then enters the first-level separation chamber for vacuum evaporation. The liquid phase is circulated and concentrated to the target concentration by the first-level circulation pump, and then added to the second-level heater through the regulating valve for further heating, and then sent to the second-level separation chamber for vacuum evaporation. After the second-level circulation pump circulates and concentrates, the density reaches the target, and is sent to the cooling crystallization and centrifuge for liquid-solid separation and drying to obtain the ammonium chloride product for sale.

[0016] As a preferred technical solution, the concentration density achieved by the secondary circulation pump is 1.4 kg / cm 3 .

[0017] As a preferred technical solution, the steam connected to the outer tube enters the shell layer of the first-level heater and exchanges heat with the ammonium chloride liquid entering the tube layer. After the heat exchange is completed, the steam is cooled to condensed water, and the condensed water enters the ammonium chloride liquid preheater through a pipeline for waste heat exchange. The condensed water after the heat exchange is sent to the steam condensate tank, and the steam condensate pump pumps the condensed water in the steam condensate tank into the boiler room for reuse in producing steam.

[0018] As a preferred technical solution, the steam evaporated from the primary separation chamber is separated into gas and liquid through a primary cyclone separator, the separated liquid enters the primary separation chamber through a pipeline, the separated gas enters the shell layer of the secondary heater and exchanges heat with the ammonium chloride in the tube layer of the secondary heater, the gas after heat exchange in the secondary heater is condensed into condensed water, the condensed water is sent to the ammonium chloride liquid preheater through a pipeline for heat exchange and then enters the steam condensate tank.

[0019] As a preferred technical solution, the ammonium chloride in the tube layer of the secondary heater is sent to the secondary circulation pump for circulation and concentration through the secondary separation chamber; the steam evaporated from the secondary separation chamber is separated into gas and liquid through the secondary cyclone separator, the separated liquid enters the secondary separation chamber, the separated gas is sent to the water spray condenser through the pipeline, cooled into liquid to form a vacuum, the non-condensable gas is discharged through the vacuum pump, and the liquid of the water spray condenser is condensed into cooling water and overflows through the liquid seal tank to the circulating water station for cooling and repeated utilization.

[0020] As a preferred technical solution, the stripping agent is gaseous ammonia.

[0021] The invention also discloses a device for an ammonium chloride concentration method for producing agricultural potassium dihydrogen phosphate by an extraction method, comprising an ammonium chloride storage tank, wherein the ammonium chloride storage tank is connected to a heat exchange cold liquid inlet of an ammonium chloride liquid preheater through an ammonium chloride delivery pump, and a heat exchange hot water outlet of the ammonium chloride preheater is connected to a primary separation chamber through a primary heater; a liquid outlet of the primary separation chamber is connected to a primary circulation pump through a pipeline, the primary circulation pump is connected to a secondary heater through a regulating valve, the secondary heater is connected to a secondary separation chamber, the liquid outlet of the secondary separation chamber is connected to a secondary circulation pump, and a discharge outlet of the secondary circulation pump is connected to a feed inlet of a concentrated discharge pump through a pipeline.

[0022] As a preferred technical solution, the condensate outlet of the primary heater is connected to the heat exchange hot liquid inlet of the ammonium chloride preheater through a pipeline, the heat exchange cold liquid outlet of the ammonium chloride preheater is connected to the steam condensate tank, and the steam condensate tank is connected to the boiler room water pipe through a condensate pump;

[0023] The steam outlet of the primary separation chamber is connected to the primary hydrocyclone, the liquid outlet of the primary hydrocyclone is connected to the primary separation chamber through a pipeline, the exhaust port of the primary hydrocyclone is connected to the heat exchange hot gas inlet of the secondary heater through a pipeline, and the heat exchange condensation outlet of the secondary heater is connected to the heat exchange hot liquid inlet of the ammonium chloride preheater through a pipeline;

[0024] The ammonia chloride outlet of the secondary heater is connected to the feed port of the secondary circulation pump through the secondary separation chamber, the steam outlet of the secondary separation chamber is connected to the secondary hydrocyclone, the liquid outlet of the secondary hydrocyclone is connected to the secondary separation chamber, the exhaust port of the secondary hydrocyclone is connected to the water spray condenser through a pipeline, and the cooling water outlet of the water spray condenser is connected to the liquid seal groove.

[0025] Advantages of the present invention:

[0026] In the present invention, the ammonium chloride is preheated and then heated before being separated and evaporated, the liquid phase is circulated and concentrated, and then heated again and separated and evaporated and concentrated to reach a high concentration density for easy sales. The steam in the outer tube is heat-exchanged in the first heating to become condensed water, and the condensed water enters the preheating process again to be recycled and reused, and the steam in the separated evaporation can enter the heater for heat exchange again and then be recycled and reused, thereby greatly improving the utilization rate of the steam and simultaneously improving the concentration efficiency of the ammonium chloride. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0028] Figure 2 It is a framework diagram of the liquid phase process and the gas phase process of an embodiment of the present invention;

[0029] 1-ammonium chloride storage tank; 2-ammonium chloride delivery pump; 3-ammonium chloride liquid preheater; 4-first-stage heater; 5-first-stage separation chamber; 6-first-stage circulation pump; 7-first-stage suspension separator; 8-second-stage heater; 9-second-stage separation chamber; 10-second-stage circulation pump; 11-second-stage suspension separator; 12-water spray condenser; 13-liquid seal tank; 14-concentrated discharge pump; 15-vacuum pump; 16-steam condensate tank; 17-steam condensate pump; 18-regulating valve. DETAILED DESCRIPTION

[0030] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments.

[0031] The following examples are only used to further illustrate the present invention in detail, but do not constitute any limitation to the present invention; the materials used in the following examples, unless otherwise specified, were purchased from conventional chemical reagent companies and raw material suppliers.

[0032] Embodiment 1:

[0033] A method and device for concentrating ammonium chloride for producing agricultural potassium dihydrogen phosphate by extraction method, comprising the following steps:

[0034] 1) The potassium chloride solution is fully mixed with phosphoric acid and the extractant to undergo a chemical reaction to generate a mixed liquid;

[0035] 2) The mixed liquid is pressurized by a pump and enters an extraction phase separation tank, and KH2PO4 in the mixed solution is taken out by an underflow pump and concentrated, and then recrystallized and dried to obtain agricultural potassium dihydrogen phosphate;

[0036] 3) The organic phase containing the extractant in the mixed solution overflows into the stripping reaction tank, reacts with the stripping agent to generate ammonium chloride liquid and the extractant, the generated ammonium chloride liquid is sent to the ammonium chloride liquid storage tank of the ammonium chloride concentrator, the ammonium chloride in the mixed solution is sent to the ammonium chloride liquid storage tank of the ammonium chloride concentrator through an underflow pump, the ammonium chloride concentrator concentrates, crystallizes and dries the mixed solution to obtain a finished fertilizer, which is packaged and sold.

[0037] Liquid phase process:

[0038] 3) the ammonium chloride in the ammonium chloride liquid storage tank 1 is pumped into the ammonium chloride liquid preheater 3 for preheating by the ammonium chloride delivery pump 2, and after the preheating is completed, the ammonium chloride is heated to 100° C. by the primary heater 4 and then enters the primary separation chamber 5 for evaporation, the liquid phase is circulated and concentrated to the index depth by the primary circulation pump 6, and is added to the secondary heater 8 for heating through the regulating valve 18, and is sent to the secondary separation chamber 9 for evaporation, and the concentration density reaches the index by the secondary circulation pump 10, and is sent to crystallization by the concentration discharge pump 14.

[0039] The concentration density after the secondary circulation pump 10 reaches the index of 1.4kg / cm 3 .

[0040] Gas phase process:

[0041] The steam connected to the outer tube enters the primary heater 4, and the shell layer of the steam entering the primary heater 4 exchanges heat with the tube layer entering the ammonium chloride liquid. After the heat exchange in the shell layer of the steam is completed, the steam is cooled to condensed water, and the condensed water enters the ammonium chloride liquid preheater through the pipeline for heat exchange. The condensed water after the heat exchange is sent to the steam condensate tank 16, and the steam condensate pump 17 pumps the condensed water in the steam condensate tank into the boiler room to produce steam.

[0042] The steam evaporated from the primary separation chamber 5 is separated into gas and liquid by the primary cyclone separator 7, and the separated liquid enters the primary separation chamber 5 through a pipeline, and the separated gas enters the shell layer of the secondary heater 8 to exchange heat with the ammonium chloride in the tube layer of the secondary heater 8. The gas after heat exchange in the secondary heater 8 is condensed into condensed water, which is sent to the ammonium chloride liquid preheater 3 through a pipeline for heat exchange and then enters the steam condensate tank 16.

[0043] The ammonium chloride in the tube layer of the secondary heater 8 is sent to the secondary circulation pump 10 for circulation and concentration through the secondary separation chamber 11; the steam evaporated from the secondary separation chamber 9 is separated into gas and liquid through the secondary cyclone separator 11, and the separated liquid enters the secondary separation chamber 11, and the separated condensable gas is sent to the water spray condenser 12 through the pipeline, cooled into liquid to form a vacuum, and the non-condensable gas is discharged through the vacuum pump 15, and the liquid in the water spray condenser 12 is condensed into cooling water and overflows to the circulating water station through the liquid seal tank 13 for cooling and repeated use.

[0044] The stripping agent is gaseous ammonia.

[0045] Embodiment 2:

[0046] The invention discloses an ammonium chloride concentration method for producing agricultural potassium dihydrogen phosphate by extraction method and a device for the device, comprising an ammonium chloride storage tank 1, wherein the ammonium chloride storage tank 1 is connected to the heat exchange cold liquid inlet of an ammonium chloride liquid preheater 3 through an ammonium chloride delivery pump 2, and the heat exchange hot liquid outlet of the ammonium chloride preheater 3 is connected to a primary separation chamber 5 through a primary heater 4; the liquid outlet of the primary separation chamber 5 is connected to a primary circulation pump 6 through a pipeline, the primary circulation pump 6 is connected to a secondary heater 8 through a regulating valve 18, the secondary heater 8 is connected to a secondary separation chamber 9, the liquid outlet of the secondary separation chamber 9 is connected to a secondary circulation pump 10, and the discharge outlet of the secondary circulation pump 10 is connected to the feed inlet of a concentrated discharge pump 14 through a pipeline.

[0047] The condensate outlet of the primary heater 4 is connected to the heat exchange hot liquid inlet of the ammonium chloride preheater 3 through a pipeline, and the heat exchange cold liquid outlet of the ammonium chloride preheater 3 is connected to the steam condensate tank 16, and the steam condensate tank 16 is connected to the boiler room water pipe through the condensate pump;

[0048] The steam outlet of the primary separation chamber 5 is communicated with the primary hydrocyclone 7, the liquid outlet of the primary hydrocyclone 7 is communicated with the primary separation chamber 5 through a pipeline, the exhaust port of the primary hydrocyclone 7 is communicated with the heat exchange hot gas inlet of the secondary heater 8 through a pipeline, and the heat exchange condensation outlet of the secondary heater 8 is communicated with the heat exchange hot liquid inlet of the ammonium chloride preheater 3 through a pipeline;

[0049] The ammonia chloride outlet of the secondary heater 8 is connected to the feed port of the secondary circulation pump 10 through the secondary separation chamber 8, the steam outlet of the secondary separation chamber 8 is connected to the secondary hydrocyclone 11, the liquid outlet of the secondary hydrocyclone 11 is connected to the secondary separation chamber 8, the exhaust port of the secondary hydrocyclone 11 is connected to the water spray condenser 12 through a pipeline, and the cooling water outlet of the water spray condenser 12 is connected to the liquid seal groove 13.

[0050] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for concentrating ammonium chloride for producing agricultural potassium dihydrogen phosphate by extraction, characterized in that: The following steps are involved: In the production process of potassium dihydrogen phosphate, the organic phase containing the extraction phase overflows into the stripping reaction tank, reacts with the stripping agent to generate ammonium chloride liquid and the extraction agent, the ammonium chloride in the generated mixed solution has a large density, and is sent to the ammonium chloride liquid storage tank of the ammonium chloride concentration device through an underflow pump, and the extraction agent has a small density and overflows into the extraction agent storage tank for reuse; the ammonium chloride concentration device heats the ammonium chloride in a vacuum concentration and cools and crystallizes it; The ammonium chloride in the ammonium chloride liquid storage tank is pumped into the ammonium chloride liquid preheater for preheating through the ammonium chloride delivery pump. After the preheating is completed, it is heated by the first-level heater and then enters the first-level separation chamber for vacuum evaporation. The liquid phase is circulated and concentrated to the target concentration by the first-level circulation pump, and then added to the second-level heater through the regulating valve for further heating, and then sent to the second-level separation chamber for vacuum evaporation. After the second-level circulation pump circulates and concentrates, the density reaches the target, and is sent to the cooling crystallization and centrifuge for liquid-solid separation and drying to obtain the ammonium chloride product for sale.

2. The method for concentrating ammonium chloride for producing agricultural potassium dihydrogen phosphate by an extraction method as claimed in claim 1, characterized in that: The concentration density after the secondary circulation pump reaches the target of 1.4kg / cm 3 .

3. The method for concentrating ammonium chloride for producing agricultural potassium dihydrogen phosphate by an extraction method as claimed in claim 1, characterized in that: The steam connected to the outer tube enters the shell layer of the first-level heater and exchanges heat with the ammonium chloride liquid entering the tube layer. After the heat exchange is completed, the steam is cooled to condensed water. The condensed water enters the ammonium chloride liquid preheater through the pipeline for waste heat exchange. The condensed water after the heat exchange is sent to the steam condensate tank. The steam condensate pump pumps the condensed water in the steam condensate tank into the boiler room for reuse in producing steam.

4. The method for concentrating ammonium chloride for producing agricultural potassium dihydrogen phosphate by an extraction method as claimed in claim 1, characterized in that: The steam evaporated from the primary separation chamber is separated into gas and liquid by a primary cyclone separator, the separated liquid enters the primary separation chamber through a pipeline, the separated gas enters the shell layer of the secondary heater and exchanges heat with the ammonium chloride in the tube layer of the secondary heater, the gas after heat exchange in the secondary heater is condensed into condensed water, the condensed water is sent to the ammonium chloride liquid preheater through a pipeline for heat exchange and then enters the steam condensate tank.

5. The method for concentrating ammonium chloride for producing agricultural potassium dihydrogen phosphate by extraction as claimed in claim 1, characterized in that: The ammonium chloride in the tube layer of the secondary heater is sent to the secondary circulation pump for circulation and concentration through the secondary separation chamber; the steam evaporated from the secondary separation chamber is separated into gas and liquid through the secondary cyclone separator, the separated liquid enters the secondary separation chamber, the separated gas is sent to the water spray condenser through the pipeline, cooled into liquid to form a vacuum, the non-condensable gas is discharged through the vacuum pump, the liquid of the water spray condenser is condensed into cooling water, overflows through the liquid seal tank to the circulating water station for cooling and repeated utilization.

6. The method for concentrating ammonium chloride for producing agricultural potassium dihydrogen phosphate by extraction as claimed in claim 1, characterized in that: The stripping agent is gaseous ammonia.

7. An apparatus for ammonium chloride concentration method for producing agricultural potassium dihydrogen phosphate by extraction method as claimed in claim 1, characterized in that: The invention comprises an ammonium chloride storage tank, which is connected with the heat exchange cold liquid inlet of the ammonium chloride liquid preheater through an ammonium chloride delivery pump, and the heat exchange hot water outlet of the ammonium chloride preheater is connected with the primary separation chamber through a primary heater; the liquid outlet of the primary separation chamber is connected with the primary circulation pump through a pipeline, the primary circulation pump is connected with the secondary heater through a regulating valve, the secondary heater is connected with the secondary separation chamber, the liquid outlet of the secondary separation chamber is connected with the secondary circulation pump, and the discharge port of the secondary circulation pump is connected with the feed port of the concentrated discharge pump through a pipeline.

8. The device for ammonium chloride concentration method for producing agricultural potassium dihydrogen phosphate by extraction method as claimed in claim 7, characterized in that: The condensate discharge outlet of the primary heater is connected to the heat exchange hot liquid inlet of the ammonium chloride preheater through a pipeline, the heat exchange cold liquid outlet of the ammonium chloride preheater is connected to the steam condensate tank, and the steam condensate tank is connected to the boiler room water pipe through a condensate pump; The steam outlet of the primary separation chamber is connected to the primary hydrocyclone, the liquid outlet of the primary hydrocyclone is connected to the primary separation chamber through a pipeline, the exhaust port of the primary hydrocyclone is connected to the heat exchange hot gas inlet of the secondary heater through a pipeline, and the heat exchange condensation outlet of the secondary heater is connected to the heat exchange hot liquid inlet of the ammonium chloride preheater through a pipeline; The ammonia chloride outlet of the secondary heater is connected to the feed port of the secondary circulation pump through the secondary separation chamber, the steam outlet of the secondary separation chamber is connected to the secondary hydrocyclone, the liquid outlet of the secondary hydrocyclone is connected to the secondary separation chamber, the exhaust port of the secondary hydrocyclone is connected to the water spray condenser through a pipeline, and the cooling water outlet of the water spray condenser is connected to the liquid seal groove.

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