Preparation system and method of potassium hydrogen sulfate-containing mixed acid

Abstract

The invention discloses a preparation system and method of mixed acid containing potassium hydrogen sulfate, and belongs to the technical field of chemical engineering. The system comprises a phosphoric acid storage tank, a phosphoric acid delivery pump, a sulfuric acid storage tank, a sulfuric acid delivery pump, a potassium chloride storage hopper, a potassium chloride feeder, a potassium chloride metering scale, a potassium chloride conveyor, a potassium hydrogen sulfate preparation tank, an acid mixing tank and a mixed acid delivery pump. With the adoption of the system and the method, potassium hydrogen sulfate can be produced from potassium chloride at a lower reaction temperature to replace potassium sulfate with high energy consumption, pollution and selling price, the potassium hydrogen sulfate and phosphoric acid are mixed to prepare mixed acid, and the mixed acid is fed into ammonia to be neutralized to prepare a low-chlorine or chlorine-free compound fertilizer; the byproduct hydrogen chloride is used for producing PVC or hydrochloric acid. The device has the advantages that the square four-area potassium hydrogen sulfate preparation tank is adopted, so that the conversion rate of potassium chloride is increased, the construction land occupation is reduced, the production operation is convenient, the process flow is simplified, and the heat loss in the production is reduced.

Description

Technical Field

[0001] The present invention relates to the field of chemical industry, and in particular to a system and method for preparing a mixed acid containing potassium hydrogen sulfate. Specifically, it is a new process for preparing potassium hydrogen sulfate by using a square four-zone potassium hydrogen sulfate preparation tank, fully mixing potassium hydrogen sulfate with phosphoric acid to prepare a mixed acid containing potassium hydrogen sulfate, and using the mixed acid to produce a chlorine-free sulfur-based compound fertilizer. Background Art

[0002] In the production of compound fertilizers containing potassium, potassium chloride or potassium sulfate is often used. Chlorine is harmful to crops and can cause soil acidification and hardening, produce salt damage, activate toxic ions, induce nutrient deficiency, affect crop growth and development, and reduce crop quality. The role of sulfur on crops is as follows: sulfur is an important component of cystine, cysteine ​​and methionine. About 90% of sulfur in plants exists in sulfur-containing amino acids; sulfur participates in the formation of chlorophyll; sulfur plays an important role in the formation and activation of certain enzymes in plants; sulfur participates in the synthesis of vitamins B and H; forms glycoside oils of cruciferous plants; sulfur is related to the protein structure that affects the cold and drought resistance of plants, and sulfur can increase the cold and drought resistance of certain crops; sulfur is related to the nitrogen fixation of rhizobia and self-generated nitrogen-fixing bacteria. Sulfur deficiency in crops will affect their normal growth, resulting in a decrease in yield and quality.

[0003] The national standard stipulates that when the chloride ion content in compound fertilizer is greater than 3.0%, it should be marked "Contains chlorine" on the packaging to avoid damage to chlorine-sensitive crops such as vegetables, tobacco, tea, forestry and fruit. If it is not marked "Contains chlorine" on the packaging container, the chloride ion content shall not exceed 3.0%, and it can be sold as chlorine-free fertilizer. The chlorine marking on the fertilizer bag refers to the chloride ion content. Low chlorine contains 3-15% of chloride ion by mass, medium chlorine contains 15-30% of chloride ion by mass, and high chlorine contains more than 30% of chloride ion by mass. Chlorine-free compound fertilizer cannot be produced directly with potassium chloride.

[0004] Potassium sulfate can be used to produce chlorine-free compound fertilizers, but when using the Mannheim process to produce potassium sulfate, the temperature of the reactor is close to 1000°C and the reaction temperature exceeds 500°C, resulting in high energy consumption and serious equipment corrosion, which leads to high prices for potassium sulfate and compound fertilizers produced with potassium sulfate. Therefore, it is necessary to use a low-priced potassium salt that does not contain chloride ions or has a low chloride ion content to replace potassium sulfate to produce a low-cost chlorine-free compound fertilizer containing potassium, sulfur, and no chloride or containing no more than 3.0% chloride. Summary of the invention

[0005] The object of the present invention is to provide a system and method for preparing a mixed acid containing potassium hydrogen sulfate. The potassium hydrogen sulfate preparation tank adopts a square four-zone tank, which can produce a potassium hydrogen sulfate solution from low-priced potassium chloride at a relatively low reaction temperature. The prepared potassium hydrogen sulfate is mixed with phosphoric acid to produce a mixed acid containing sulfur, potassium and phosphorus effective components beneficial to crops. The mixed acid contains very low chlorine harmful to crops. The mixed acid is then deammonified and neutralized to prepare a low-chlorine or chlorine-free compound fertilizer, so as to replace the production of compound fertilizer using potassium sulfate with high energy consumption, pollution and high price.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A system for preparing a mixed acid containing potassium hydrogen sulfate, the system comprising a potassium hydrogen sulfate preparation tank, the potassium hydrogen sulfate preparation tank comprising N reaction tanks connected in series, adjacent reaction tanks being communicated with each other, and the reaction tanks being named a first reaction tank, a second reaction tank, ... and an Nth reaction tank in sequence; an output pipeline of potassium chloride and an output pipeline of concentrated sulfuric acid are both connected to the first reaction tank.

[0008] In the above system: the system also includes a mixed acid tank, the output end of the Nth reaction tank is connected to the mixed acid tank, and the output pipeline of phosphoric acid is also connected to the mixed acid tank.

[0009] In the above system: the potassium bisulfate preparation tank includes 4 reaction tanks connected in series.

[0010] In the above system: a stirrer is provided in each reaction tank.

[0011] A method for preparing a mixed acid containing potassium hydrogen sulfate using the above system is provided. The method comprises the following steps: potassium chloride and concentrated sulfuric acid are transported to a first reaction tank. After the reaction is completed, the materials sequentially enter a second reaction tank, ..., and an Nth reaction tank to continue the reaction. After the reaction of the materials in the Nth reaction tank is completed, the materials are transported to a mixed acid tank and phosphoric acid is added to the mixed acid tank for mixing, thereby obtaining a target product.

[0012] In the above method: the reaction temperature of each reaction tank in the N series-connected reaction tanks is 115-125° C., and the reaction time is 0.5-1.5 hours.

[0013] In the above method, the mass concentration of phosphoric acid entering the mixed acid tank is 10-40wt%.

[0014] In the above method, the concentration of the potassium hydrogen sulfate solution entering the mixed acid tank is 80-90wt%.

[0015] In the above method: the molar ratio of potassium chloride to sulfuric acid in the first reaction tank is 1:1-1.2, and the mass concentration of sulfuric acid is 98%.

[0016] In some specific technical solutions, the technical solutions of the present invention are as follows:

[0017] A system for preparing mixed acid containing potassium hydrogen sulfate, the system comprises a phosphoric acid storage tank, a phosphoric acid agitator, a phosphoric acid delivery pump, a sulfuric acid storage tank, a sulfuric acid delivery pump, a potassium chloride storage hopper, a potassium chloride feeder, a potassium chloride weighing scale, a potassium chloride conveyor, a potassium hydrogen sulfate preparation tank, a potassium hydrogen sulfate agitator, a mixed acid tank, a mixed acid agitator, and a mixed acid delivery pump. The potassium hydrogen sulfate preparation tank adopts a square four-zone tank, named No.1 to No.4 zones. The upper ends of No.1 and No.2 zones are connected through a gas phase channel D, and the lower ends of No.1 and No.2 zones are connected through a liquid phase channel E; the upper ends of No.2 and No.3 zones are connected through a gas-liquid phase channel H; the upper ends of No.3 and No.4 zones are connected through a gas phase channel K, and the lower ends of No.3 and No.4 zones are connected through a liquid phase channel L; the upper end of No.4 zone is connected to No.1 zone through a gas phase channel P, and is connected to the top inlet A of the mixed acid tank through a potassium hydrogen sulfate outlet N.

[0018] In the above system: the concentrated sulfuric acid pipeline from the boundary area is connected to the top inlet A of the sulfuric acid storage tank, and the lower side outlet B of the sulfuric acid storage tank is connected to the top inlet A of the potassium hydrogen sulfate preparation tank through a sulfuric acid delivery pump.

[0019] In the above system: the phosphoric acid pipeline from the boundary area is connected to the top inlet A of the phosphoric acid storage tank, the lower side outlet B of the phosphoric acid storage tank is connected to the top inlet B of the mixed acid tank through a phosphoric acid delivery pump, and the lower side outlet C of the mixed acid tank is connected to the target product to the boundary area - the potassium hydrogen sulfate mixed acid pipeline through a mixed acid delivery pump.

[0020] In the above system: the potassium chloride pipeline from the boundary area is connected to the top inlet of the potassium chloride storage hopper, the bottom outlet of the potassium chloride storage hopper is connected to the inlet of the potassium chloride weighing scale through a potassium chloride feeder, and the outlet of the potassium chloride weighing scale is connected to the top inlet B of the potassium bisulfate preparation tank through a potassium chloride conveyor.

[0021] In the above system, the steam pipeline from the boundary zone is connected to the top inlets C, F, J, and M of the potassium bisulfate preparation tank; and the top outlet G of the potassium bisulfate preparation tank is connected to the HCl-containing gas pipeline to the boundary zone.

[0022] In the above system: the phosphoric acid storage tank is provided with a phosphoric acid agitator, the potassium hydrogen sulfate preparation tank is provided with a potassium hydrogen sulfate agitator, and the mixed acid tank is provided with a mixed acid agitator.

[0023] A method for preparing a mixed acid containing potassium hydrogen sulfate using the above system comprises the following steps:

[0024] (1) Raw material feeding section: Potassium chloride (containing KCl mass concentration ≤ 96%) from the boundary area enters the potassium chloride storage hopper, and the potassium chloride in the potassium chloride storage hopper enters the potassium chloride weighing scale through the potassium chloride feeder, and the measured potassium chloride enters the potassium hydrogen sulfate preparation tank No. 1 area through the potassium chloride conveyor from the top inlet B of the potassium hydrogen sulfate preparation tank. Sulfuric acid (containing H2SO4 mass concentration ≤ 98%) from the boundary area enters the sulfuric acid storage tank, and the sulfuric acid in the sulfuric acid storage tank enters the potassium hydrogen sulfate preparation tank No. 1 area through the sulfuric acid delivery pump from the top inlet A of the potassium hydrogen sulfate preparation tank.

[0025] (2) Potassium hydrogen sulfate preparation section: The molar ratio of potassium chloride to sulfuric acid is approximately 1:1. The two materials are fully mixed and reacted under the action of the potassium hydrogen sulfate agitator in the No. 1 zone. The material temperature is controlled to be ≤125°C and the residence time is ≤1.5 hours. The evenly mixed materials continuously flow into the No. 2 zone through the liquid phase channel E at the lower end of the No. 1 zone and the No. 2 zone.

[0026] The material from No.1 zone continues to mix and react under the action of potassium bisulfate agitator in No.2 zone, and the material temperature is controlled to be ≤125°C and the residence time is ≤1.5 hours. The reaction material continuously flows into No.3 zone through the gas-liquid phase channel H at the upper end of No.2 zone and No.3 zone.

[0027] The material from No.2 zone continues to mix and react under the action of potassium bisulfate agitator in No.3 zone, and the material temperature is controlled to be ≤125°C and the residence time is ≤1.5 hours. The reaction material continuously flows into No.4 zone through the liquid phase channel L at the lower end of No.3 zone and No.4 zone.

[0028] The materials from No. 3 zone continue to mix and react under the action of the agitator in No. 4 zone, and the material temperature is controlled to be ≤125°C and the residence time is ≤1.5 hours. The prepared potassium bisulfate solution (containing KHSO4 mass concentration of 80% ≤) continuously flows into the mixed acid tank from the potassium bisulfate outlet N at the upper end of No. 4 zone through the top inlet A of the mixed acid tank.

[0029] During the preparation process of potassium bisulfate, the hydrogen chloride gas produced in the potassium bisulfate preparation tank is continuously collected to the No. 2 area through the gas phase channels D, K, P and the gas-liquid phase channel H, and goes to the boundary area from the top outlet G of the No. 2 area to produce PVC or hydrochloric acid.

[0030] The steam required for the potassium bisulfate preparation tank is provided through inlets C, F, J, and M at the top of the tank.

[0031] (3) Mixed acid preparation section: Phosphoric acid (containing P2O5 mass concentration ≤40%) from the boundary area enters the phosphoric acid storage tank, and the phosphoric acid in the phosphoric acid storage tank enters the mixed acid tank from the top inlet B of the mixed acid tank through the phosphoric acid delivery pump. Potassium hydrogen sulfate solution and phosphoric acid are added to the mixed acid tank according to the requirements of the compound fertilizer components. Under the action of the agitator, the potassium hydrogen sulfate solution and phosphoric acid are fully mixed to obtain the target product - potassium hydrogen sulfate mixed acid. The mixed acid in the mixed acid tank is delivered from the lower side outlet C of the mixed acid tank to the boundary area through the mixed acid delivery pump to produce chlorine-free sulfur-based compound fertilizer with Cl mass content ≤3%.

[0032] In some more specific technical solutions, the technical solutions of the present invention are as follows:

[0033] A method for preparing a mixed acid containing potassium hydrogen sulfate, comprising raw material feeding, adding and mixing, potassium chloride reacting with sulfuric acid to prepare potassium hydrogen sulfate as a by-product of hydrogen chloride, mixing potassium hydrogen sulfate with phosphoric acid to prepare mixed acid and conveying the mixed acid, characterized in that the production process comprises: a raw material feeding section, a potassium hydrogen sulfate preparation section, and a mixed acid preparation section, and the steps are as follows:

[0034] (1) Raw material feeding section: Potassium chloride (90%≤KCl mass concentration≤96%) from the boundary area enters the potassium chloride storage hopper, and the potassium chloride in the potassium chloride storage hopper enters the potassium chloride weighing scale through the potassium chloride feeder for measurement, and the measured potassium chloride enters the potassium hydrogen sulfate preparation tank No. 1 area through the potassium chloride conveyor from the top inlet B of the potassium hydrogen sulfate preparation tank. Sulfuric acid (93%≤H2SO4 mass concentration≤98%) from the boundary area enters the sulfuric acid storage tank, and the sulfuric acid in the sulfuric acid storage tank enters the potassium hydrogen sulfate preparation tank No. 1 area through the sulfuric acid delivery pump from the top inlet A of the potassium hydrogen sulfate preparation tank.

[0035] (2) Potassium hydrogen sulfate preparation section: The molar ratio of potassium chloride to sulfuric acid is 1:1-1.2. The two materials are fully mixed and reacted under the action of the potassium hydrogen sulfate agitator in the No. 1 zone. The material temperature is controlled at 115-125° C. and the residence time is 0.5-1.5 hours. The uniformly mixed materials continuously flow into the No. 2 zone through the liquid phase channel E at the lower end of the No. 1 zone and the No. 2 zone.

[0036] The material from No.1 zone continues to mix and react under the action of potassium bisulfate agitator in No.2 zone, and the material temperature is controlled at 115-125°C, with a residence time of 0.5-1.5 hours. The reaction material continuously flows into No.3 zone through the gas-liquid phase channel H at the upper end of No.2 zone and No.3 zone.

[0037] The material from No.2 zone continues to mix and react under the action of potassium bisulfate agitator in No.3 zone, and the material temperature is controlled at 115-125°C, with a residence time of 0.5-1.5 hours. The reaction material continuously flows into No.4 zone through the liquid phase channel L at the lower end of No.3 zone and No.4 zone.

[0038] The material from No. 3 zone continues to mix and react under the action of the agitator in No. 4 zone, and the material temperature is controlled at 115-125° C. The residence time is 0.5-1.5 hours. The prepared potassium bisulfate solution (80% ≤ KHSO4 mass concentration ≤ 90%) flows continuously into the mixed acid tank from the potassium bisulfate outlet N at the upper end of No. 4 zone through the top inlet A of the mixed acid tank.

[0039] During the preparation process of potassium bisulfate, the hydrogen chloride gas produced in the potassium bisulfate preparation tank is continuously collected to the No. 2 area through the gas phase channels D, K, P and the gas-liquid phase channel H, and goes to the boundary area from the top outlet G of the No. 2 area to produce PVC or hydrochloric acid.

[0040] The steam required for the potassium bisulfate preparation tank is provided through inlets C, F, J, and M at the top of the tank.

[0041] (3) Mixed acid preparation section: Phosphoric acid (10%≤P2O5 mass concentration≤40%) from the boundary area enters the phosphoric acid storage tank, and the phosphoric acid in the phosphoric acid storage tank enters the mixed acid tank from the top inlet B of the mixed acid tank through the phosphoric acid delivery pump. Potassium hydrogen sulfate solution and phosphoric acid are added to the mixed acid tank according to the requirements of the compound fertilizer components. Under the action of the agitator, the potassium hydrogen sulfate solution and phosphoric acid are fully mixed to obtain the target product - potassium hydrogen sulfate mixed acid. The mixed acid in the mixed acid tank is delivered from the lower side outlet C of the mixed acid tank to the boundary area through the mixed acid delivery pump to produce chlorine-free sulfur-based compound fertilizer with Cl mass content ≤3%.

[0042] Beneficial effects of the present invention:

[0043] The preparation of potassium sulfate with potassium chloride and concentrated sulfuric acid is an endothermic reaction. 700 kg of standard coal is consumed for each ton of potassium sulfate produced. The preparation of potassium bisulfate with potassium chloride and concentrated sulfuric acid is an exothermic reaction. The steam in the potassium bisulfate preparation tank is used to keep warm and accelerate the reaction rate. 260 kg of saturated steam with a temperature of 133°C and an absolute pressure of 0.3 MPa is consumed for each ton of potassium bisulfate (pure), which is equivalent to 20 kg of standard coal. Both of the above potassium salts can produce high-concentration chlorine-free compound fertilizers, and have the same fertilizer effect on crops. Potassium sulfate contains 54% by mass of potassium oxide, an effective ingredient in fertilizers, and potassium bisulfate contains 35% by mass of potassium oxide, an effective ingredient in fertilizers. Therefore, the energy consumed to obtain the same mass of potassium oxide and potassium sulfate is about 23 times the energy consumed by potassium bisulfate. The preparation of potassium bisulfate from potassium chloride and concentrated sulfuric acid is not an instantaneous reaction and requires a long reaction time. The square four-zone potassium bisulfate preparation tank increases the concentration gradient and reduces the specific surface area per unit volume of the tank compared to the double circular tank and the double square tank, which is beneficial to the chemical reaction and has low heat loss. The square four-zone potassium bisulfate preparation tank does not require a baffle and the tank is not easily damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the process flow in the present invention.

[0045] Figure 2 It is a top view of the potassium bisulfate preparation tank.

[0046] Figure 3 yes Figure 2 Schematic diagram of the middle QQ section.

[0047] Figure 4 yes Figure 2 Schematic diagram of the RR section.

[0048] Figure 5 yes Figure 2 Schematic diagram of the SS section.

[0049] Figure 6 yes Figure 2 Schematic diagram of the middle TT section.

[0050] Among them, there are a phosphoric acid storage tank 1, a phosphoric acid agitator 2, a phosphoric acid delivery pump 3, a sulfuric acid storage tank 4, a sulfuric acid delivery pump 5, a potassium chloride storage hopper 6, a potassium chloride feeder 7, a potassium chloride weighing scale 8, a potassium chloride conveyor 9, a potassium hydrogen sulfate preparation tank 10, a potassium hydrogen sulfate agitator 11, a mixed acid tank 12, a mixed acid agitator 13, and a mixed acid delivery pump 14. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the embodiments of the present patent clearer, the technical solution in the embodiments of the present patent will be clearly and completely described below in conjunction with the drawings in the embodiments of the present patent. Obviously, the described embodiments are part of the embodiments of the present patent, not all of the embodiments. The components of the embodiments of the present patent generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present patent provided in the drawings is not intended to limit the scope of the claimed patent, but only represents the selected embodiments of the present patent. Based on the embodiments in this patent, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this patent. The embodiments of the present patent are described in detail below, and examples of the embodiments are shown in the drawings, where the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below by reference to the drawings are exemplary and are intended to be used to explain the present patent, and cannot be understood as limitations on the present patent.

[0052] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0053] like Figures 1 to 6As shown, a system for preparing mixed acid containing potassium hydrogen sulfate comprises a phosphoric acid storage tank 1, a phosphoric acid stirrer 2, a phosphoric acid delivery pump 3, a sulfuric acid storage tank 4, a sulfuric acid delivery pump 5, a potassium chloride storage hopper 6, a potassium chloride feeder 7, a potassium chloride weighing scale 8, a potassium chloride conveyor 9, a potassium hydrogen sulfate preparation tank 10, a potassium hydrogen sulfate stirrer 11, a mixed acid tank 12, a mixed acid stirrer 13, and a mixed acid delivery pump 14. The potassium hydrogen sulfate preparation tank 10 adopts a square four-zone tank, named No. 1 to No. 4 zones. The upper ends of No.1 and No.2 zones are connected through a gas phase channel D, and the lower ends of No.1 and No.2 zones are connected through a liquid phase channel E; the upper ends of No.2 and No.3 zones are connected through a gas-liquid phase channel H; the upper ends of No.3 and No.4 zones are connected through a gas phase channel K, and the lower ends of No.3 and No.4 zones are connected through a liquid phase channel L; the upper end of No.4 zone is connected to No.1 zone through a gas phase channel P, and is connected to the top inlet A of the mixed acid tank 12 through a potassium bisulfate outlet N.

[0054] The concentrated sulfuric acid pipeline from the boundary area is connected to the top inlet A of the sulfuric acid storage tank 4, and the lower side outlet B of the sulfuric acid storage tank 4 is connected to the top inlet A of the potassium hydrogen sulfate preparation tank 10 through the sulfuric acid delivery pump 5.

[0055] The phosphoric acid pipeline from the boundary area is connected to the top inlet A of the phosphoric acid storage tank 1, the lower side outlet B of the phosphoric acid storage tank 1 is connected to the top inlet B of the mixed acid tank 12 through the phosphoric acid delivery pump 3, and the lower side outlet C of the mixed acid tank 12 is connected to the target product of the de-boundary area - the potassium bisulfate mixed acid pipeline through the mixed acid delivery pump 14.

[0056] The potassium chloride pipeline from the boundary area is connected to the top inlet of the potassium chloride storage hopper 6, the bottom outlet of the potassium chloride storage hopper 6 is connected to the inlet of the potassium chloride metering scale 8 through the potassium chloride feeder 7, and the outlet of the potassium chloride metering scale 8 is connected to the top inlet B of the potassium bisulfate preparation tank 10 through the potassium chloride conveyor 9.

[0057] The steam pipeline from the boundary zone is connected to the top inlets C, F, J, and M of the potassium bisulfate preparation tank 10; the top outlet G of the potassium bisulfate preparation tank 10 is connected to the HCl-containing gas pipeline to the boundary zone.

[0058] The phosphoric acid storage tank 1 is provided with a phosphoric acid stirrer 2 , the potassium hydrogen sulfate preparation tank 10 is provided with a potassium hydrogen sulfate stirrer 11 , and the mixed acid tank 12 is provided with a mixed acid stirrer 13 .

[0059] The method for preparing a mixed acid containing potassium hydrogen sulfate using the above system comprises the following steps:

[0060] (1) Raw material feeding section: Potassium chloride (containing KCl mass concentration of 95%) from the boundary area enters potassium chloride storage hopper 6, and the potassium chloride in potassium chloride storage hopper 6 enters potassium chloride weighing scale 8 for measurement through potassium chloride feeder 7, and the measured potassium chloride enters No. 1 zone of potassium hydrogen sulfate preparation tank 10 from inlet B at the top of potassium hydrogen sulfate preparation tank 10 through potassium chloride conveyor 9. Sulfuric acid (containing H2SO4 mass concentration of 98%) from the boundary area enters sulfuric acid storage tank 4, and the sulfuric acid in sulfuric acid storage tank 4 enters No. 1 zone of potassium hydrogen sulfate preparation tank 10 from inlet A at the top of potassium hydrogen sulfate preparation tank 10 through sulfuric acid conveying pump 5.

[0061] (2) Potassium hydrogen sulfate preparation section: The molar ratio of potassium chloride to sulfuric acid is 1:1.1. The two materials are fully mixed and reacted under the action of the potassium hydrogen sulfate stirrer 11 in the No. 1 zone. The material temperature is controlled at 120° C. and the residence time is 1 hour. The mixed materials continuously flow into the No. 2 zone through the liquid phase channel E at the lower end of the No. 1 zone and the No. 2 zone.

[0062] The material from No. 1 zone continues to mix and react under the action of potassium bisulfate agitator 11 in No. 2 zone, and the material temperature is controlled at 120° C. The residence time is 1 hour, and the reaction material continuously flows into No. 3 zone through the gas-liquid phase channel H at the upper end of No. 2 zone and No. 3 zone.

[0063] The material from No.2 zone continues to mix and react under the action of potassium bisulfate agitator 11 in No.3 zone, and the material temperature is controlled at 120°C. The residence time is 1 hour. The reaction material continuously flows into No.4 zone through the liquid phase channel L at the lower end of No.3 zone and No.4 zone.

[0064] The materials from zone No. 3 continue to mix and react under the action of the agitator in zone No. 4, and the material temperature is controlled at 120° C. The residence time is 1 hour. The prepared potassium bisulfate solution (containing 85% by mass concentration of KHSO4, 31% by mass concentration of K2O, 23.1% by mass concentration of S, and 2.3% by mass concentration of Cl) flows continuously into the mixed acid tank 12 from the potassium bisulfate outlet N at the upper end of zone No. 4 through the top inlet A of the mixed acid tank 12.

[0065] During the preparation of potassium bisulfate, the hydrogen chloride gas produced by the potassium bisulfate preparation tank 10 is continuously collected to the No. 2 zone through the gas phase channels D, K, P and the gas-liquid phase channel H, and goes to the boundary zone to produce PVC or hydrochloric acid from the top outlet G of the No. 2 zone.

[0066] The steam required for the potassium bisulfate preparation tank 10 is provided through inlets C, F, J, and M at the top of the tank.

[0067] (3) Mixed acid preparation section: Phosphoric acid (containing P2O5 mass concentration of 22%) from the boundary area enters the phosphoric acid storage tank 1, and the phosphoric acid in the phosphoric acid storage tank 1 enters the mixed acid tank 12 from the top inlet B of the mixed acid tank 12 through the phosphoric acid delivery pump 3. Potassium hydrogen sulfate solution and phosphoric acid are added to the mixed acid tank 12 at a mass ratio of 22:31, and the potassium hydrogen sulfate solution and phosphoric acid are fully mixed and uniformly prepared under the action of the stirrer 13 to obtain the target product - potassium hydrogen sulfate mixed acid (containing P2O5 mass concentration of 12.87%, K2O mass concentration of 12.87%, S mass concentration of 9.59%, Cl mass concentration of 0.95%), and the mixed acid in the mixed acid tank 12 is sent from the lower side outlet C of the mixed acid tank 12 to the boundary area through the mixed acid delivery pump 14 to produce chlorine-free sulfur-based compound fertilizer, and after ammonia neutralization and nitrogen supplementation, a chlorine-free sulfur-containing ternary compound fertilizer with a mass ratio of N:P2O5:K2O of 15:15:15 and a Cl mass content of less than 1.2% can be produced.

[0068] The results of using this patent are shown in Table 1.

[0069] Table 1 Performance evaluation results of 120,000 tons / year potassium bisulfate mixed acid unit

[0070] Table 1 Performance evaluation results of 120,000 tons / year potassium bisulfate mixed acid unit

[0071]

[0072]

Claims

1. A system for preparing a mixed acid containing potassium hydrogen sulfate, characterized in that: The system comprises a potassium hydrogen sulfate preparation tank (10), wherein the potassium hydrogen sulfate preparation tank (10) comprises N reaction tanks connected in series, and adjacent reaction tanks are connected, and the reaction tanks are sequentially named as a first reaction tank, a second reaction tank, ... and an Nth reaction tank; an output pipeline of potassium chloride and an output pipeline of concentrated sulfuric acid are both connected to the first reaction tank.

2. The system for preparing a mixed acid containing potassium hydrogen sulfate according to claim 1, characterized in that: The system also includes a mixed acid tank (12), the output end of the Nth reaction tank is connected to the mixed acid tank (12), and the output pipeline of phosphoric acid is also connected to the mixed acid tank (12).

3. The system for preparing a mixed acid containing potassium hydrogen sulfate according to claim 1, characterized in that: The potassium bisulfate preparation tank (10) comprises four reaction tanks connected in series.

4. The system for preparing a mixed acid containing potassium hydrogen sulfate according to claim 1, characterized in that: The reaction tank is equipped with a stirrer.

5. A method for preparing a mixed acid containing potassium hydrogen sulfate using the system of claim 1, characterized in that: The method is that potassium chloride and concentrated sulfuric acid are transported to a first reaction tank, and after the reaction is completed, the materials enter the second reaction tank, ..., and the Nth reaction tank in sequence to continue the reaction, and after the reaction of the materials in the Nth reaction tank is completed, the materials are transported to a mixed acid tank and phosphoric acid is added to the mixed acid tank for mixing, so as to obtain a target product.

6. The method according to claim 5, characterized in that: The reaction temperature in each of the N series-connected reaction tanks is 115-125° C., and the reaction time is 0.5-1.5 hours.

7. The method according to claim 5, characterized in that: The mass concentration of phosphoric acid entering the mixed acid tank is 10-40wt%.

8. The method according to claim 5, characterized in that: The concentration of the potassium hydrogen sulfate solution entering the mixed acid tank is 80-90 wt%.

9. The method according to claim 5, characterized in that: The molar ratio of potassium chloride to sulfuric acid in the first reaction tank is 1:1-1.2, and the mass concentration of sulfuric acid is 98%.

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