Phosphorus trichloride hydrolysis process and equipment

Abstract

The invention belongs to the technical field of phosphorus trichloride hydrolysis, and particularly relates to a phosphorus trichloride hydrolysis process and equipment, the phosphorus trichloride hydrolysis process comprises a phosphorous acid and hydrochloric acid storage tank, the phosphorous acid and hydrochloric acid storage tank is fixedly connected with a reaction liquid circulation system, and on one hand, the reaction liquid circulation system is fixedly connected with a phosphorus trichloride mixing system; and on the other hand, the reaction liquid circulating system is fixedly connected with the reactor. The phosphorus trichloride mixing effect is good, rapid reaction of phosphorus trichloride is facilitated, and full mixing of phosphorus trichloride and reaction liquid is guaranteed through a series of steps of atomization, jet mixing, diffusion mixing, rotary mixing and the like; the temperature of a reaction system is balanced, and disproportionation reaction of phosphorus trichloride is avoided. The system adopts the mixing mode, so that the generation of a large phosphorus trichloride liquid drop interface is effectively avoided, and a microscopic local high-temperature region is reduced, thereby effectively inhibiting the occurrence of high-temperature disproportionation reaction.

Description

Technical Field

[0001] The invention relates to the technical field of phosphorus trichloride hydrolysis, in particular to a phosphorus trichloride hydrolysis process and equipment. Background Art

[0002] Phosphite-hydrochloric acid mixture is an intermediate raw material often used in the production of water treatment agents or chemical production. It is usually prepared by hydrolysis of phosphorus trichloride. Its preparation process is basically the same as the principle of hydrolysis of phosphorus trichloride to produce phosphorous acid. Hydrolysis of phosphorus trichloride to produce phosphorous acid is a conventional process for the production of phosphorous acid. It is usually a mixture of phosphorus trichloride and water, and hydrochloric acid is evaporated after hydrolysis to obtain phosphorous acid. The biggest difficulty of this process is that phosphorus trichloride and water react very easily. The reaction process is accompanied by heat release and the production of hydrogen chloride. Hydrogen chloride gas dissolves in water and releases a large amount of heat. Therefore, a local high-temperature zone is formed at the interface where the phosphorus trichloride liquid mass and water contact. On the one hand, the materials in contact with the high-temperature zone (such as phosphorus trichloride, hydrochloric acid, etc.) are partially vaporized and overflow the reaction system with hydrogen chloride gas. On the other hand, when the temperature exceeds 80°C, phosphorus trichloride undergoes a disproportionation reaction to form orthophosphoric acid and phosphorus or phosphine. Therefore, the conversion rate of preparing phosphorous acid by direct hydrolysis of phosphorus trichloride is usually 70% to 80%, and the yield is not high. On the one hand, it causes the loss of raw materials and the increase of product cost. On the other hand, it also causes the product to be yellow and the product quality is not high.

[0003] In order to solve the above problems, the industry has adopted many methods, such as: CN101993051B discloses a method for preparing phosphorous acid and hydrogen chloride, and proposes a method for preparing phosphorous acid and hydrogen chloride in an inner circulation tower using phosphorus trichloride. A diversion barrel is installed in the reactor, phosphorus trichloride enters the tower from the feed port, and the reaction liquid rises from the diversion barrel along with the generated hydrogen chloride, and the liquid circulates inside and outside the barrel to extract hydrogen chloride gas and heat.

[0004] CN103350990 discloses a process for preparing phosphorous acid by hydrolyzing phosphorus trichloride, wherein phosphorus trichloride and hydrogen chloride solution are sequentially hydrolyzed in 4-6 series-connected reaction vessels at 65-85°C and a pressure of no more than 0.1 MPa to generate phosphorous acid solution and gaseous hydrogen chloride. This scheme uses hydrogen chloride solution instead of water as a reactant, effectively reducing the amount of hydrogen chloride dissolved in water, thereby reducing the heat released by the reaction, and through a multi-stage series reaction, the volatilized phosphorus trichloride in the gas phase is washed and absorbed.

[0005] CN115285953A discloses a process for preparing phosphorus trichloride by hydrolysis. In this process, a large amount of atomized pure water is blown into a reactor through an atomizer, and the mist water reacts with the phosphorus trichloride in the reactor to undergo a hydrolysis reaction, without producing a soaking effect and with a gentle reaction.

[0006] CN118206085A discloses a process for preparing phosphorous acid by hydrolyzing phosphorus trichloride. Phosphorus trichloride and hydrochloric acid are respectively added into a hydrolysis kettle for hydrolysis reaction to obtain a feed liquid, and the gas phase in the hydrolysis kettle enters a phosphorus washing tower for washing. Compared with CN103350990, the reaction equipment is somewhat streamlined.

[0007] CN117699757A discloses a method and system for continuously preparing phosphorous acid. Phosphorus trichloride and hydrochloric acid are introduced into a two-stage tubular reactor for reaction according to a certain ratio, and the pressure in the tubular reactor is 1-5 MPa. This solution effectively prevents the escape of phosphorus trichloride through a high-temperature and high-pressure closed system, and improves the conversion rate of phosphorus trichloride.

[0008] In the above methods, either the equipment is too complex and the utilization rate of the reactor is not high, or the reaction efficiency of the equipment is not high and it is difficult to produce in batches, or the equipment requires high temperature and high pressure, which requires higher requirements for the equipment material, and under high temperature and high pressure, it is difficult to avoid the occurrence of disproportionation reaction. Summary of the Invention

[0009] Aiming at the deficiencies of the prior art, the present invention provides a process and equipment for hydrolyzing phosphorus trichloride, which solves the problems of...

[0010] To achieve the above object, the present invention provides the following technical solution: A phosphorus trichloride hydrolysis equipment, including a phosphorous acid hydrochloric acid storage tank, the phosphorous acid hydrochloric acid storage tank is fixedly connected to a reaction liquid circulation system, on the one hand, the reaction liquid circulation system is fixedly connected to a phosphorus trichloride mixing system, on the other hand, the reaction liquid circulation system is fixedly connected to a reactor, the phosphorus trichloride mixing system is also fixedly connected to the reactor, on the one hand, the reactor is fixedly connected to a condensation and demisting device, on the other hand, the reactor is fixedly connected to a metering pump, the metering pump is also fixedly connected to a hydrochloric acid storage tank, the condensation and demisting device and the hydrochloric acid storage tank are respectively connected to a hydrogen chloride absorption system, and the hydrogen chloride absorption system is fixedly connected to a tail gas washing system.

[0011] As a preferred technical solution of the present invention, the reaction liquid circulation system includes a metering valve fixedly connected to the phosphorous acid hydrochloric acid storage tank, the other end of the metering valve is divided into two branches, one of the branches is fixedly connected to the metering valve, the other end of the metering valve is fixedly connected to a phosphorus trichloride mixing system, and the other branch is fixedly connected to an acid-resistant pump, the other end of the acid-resistant pump is fixedly installed with a heat exchanger, and the other end of the heat exchanger is fixedly connected to the reactor.

[0012] As a preferred technical solution of the present invention, the phosphorus trichloride mixing system includes a conduit fixedly installed with the reactor, and the other end of the conduit is fixedly installed with a large jet pump; The large jet pump is divided into two branches, one of which is fixedly connected to a metering valve, and the other is fixedly connected to a small jet pump. One end of the small jet pump is also fixedly connected to a phosphorus trichloride metering pump, and phosphorus trichloride is fixedly installed at the other end of the phosphorus trichloride metering pump.

[0013] As a preferred technical solution of the present invention, the reactor includes a reaction liquid inlet for fixedly installing a conduit. A hydrogen chloride outlet and a foam-trapping liquid reflux port are provided at the top of the reactor. The reactor is fixedly connected to a condensation foam-trapping device through the hydrogen chloride outlet and the foam-trapping liquid reflux port. A hydrochloric acid inlet is also provided on the side of the reactor. The reactor is fixedly connected to a metering pump through the hydrochloric acid inlet. A reaction liquid outlet is provided at the lower end face of the reactor. The reactor is fixedly connected to a heat exchanger through the reaction liquid outlet. A spray head is fixedly installed on the upper side inside the reactor. A packing layer is fixedly installed in the middle side inside the reactor. A rotary separation chamber is provided below the packing layer.

[0014] As a preferred technical solution of the present invention, a condenser and a foam-trapping device are fixedly installed inside the condensation foam-trapping device. The foam-trapping device is installed above the condenser. A condensate outlet is provided at the bottom side of the condensation foam-trapping device. The condensate outlet is fixedly connected to the foam-trapping liquid reflux port. An air flow inlet is also fixedly installed on the side of the condensation foam-trapping device. The air flow inlet is fixedly connected to the hydrogen chloride outlet. An air flow outlet and a pressure relief port are provided on the upper side of the condensation foam-trapping device. The air flow outlet is fixedly connected to a hydrogen chloride absorption system.

[0015] As a preferred technical solution of the present invention, the hydrogen chloride absorption system includes a first-stage absorption tank, a second-stage absorption tank, and a third-stage absorption tank that are fixedly connected to a hydrochloric acid storage tank and the air flow outlet. The second-stage absorption tank is fixedly connected to the first-stage absorption tank and the third-stage absorption tank at the same time. The third-stage absorption tank is fixedly connected to a tail gas scrubbing system and an acid-resistant pump at the same time. The other end of the acid-resistant pump is fixedly installed with a washing liquid storage tank. The washing liquid storage tank is also fixedly connected to the tail gas scrubbing system.

[0016] As a preferred technical solution of the present invention, the tail gas scrubbing system includes a falling film scrubber fixedly connected to the third-stage absorption tank. The falling film scrubber is divided into four branches. The first branch is fixedly connected to water. The second branch is fixedly connected to a circulation pump. The circulation pump is divided into two branches. One of the branches is fixedly connected to a valve. The valve is fixedly connected to the third branch of the falling film scrubber. The other branch of the circulation pump is fixedly connected to the valve. The valve is fixedly connected to the washing liquid storage tank. The fourth branch of the falling film scrubber is fixedly connected to an air induction system.

[0017] As a preferred technical solution of the present invention, S1: Start the reaction system. Hydrochloric acid in the hydrochloric acid storage tank enters the spray head in the reactor through a metering pump and a hydrochloric acid inlet, and performs gas-liquid countercurrent washing in the packing layer. The washing liquid converges in the rotary separation chamber and is mixed with the phosphorous acid hydrochloric acid solution from the ejector pump. Among them, the concentration of hydrochloric acid is 30% - 31%. The amount of hydrochloric acid entering the system is controlled by a metering pump. The amount of hydrochloric acid is measured by water, and the number of moles of water is 4 - 6 times the number of moles of phosphorus trichloride neutralized in S2, preferably 4.8 - 5.0 times.

[0018] S2: Driven by the phosphorus trichloride metering pump, phosphorus trichloride enters the small ejector pump and is mixed with a part of hydrogen chloride from the hydrogen chloride outlet to form a gas-liquid mixture. Under the negative pressure suction of the large ejector pump, it enters the throat area of the large ejector pump through a conduit. Among them, the amount of phosphorus trichloride entering the system is controlled by the phosphorus trichloride metering pump. The molar ratio of phosphorus trichloride to the number of moles of water in hydrochloric acid entering the system in S1 is 1:4 - 6, preferably 1:4.8 - 5.0.

[0019] S3: The phosphorous acid hydrochloric acid mixture from S1 enters the heat exchanger through the reaction liquid outlet to be cooled, and then is driven by an acid-resistant pump. Under the control of metering valve 1 and metering valve 2, the part entering the large ejector pump through metering valve 2. Inside the large ejector pump, through the formed negative pressure area, the phosphorus trichloride hydrogen chloride gas-liquid mixture from S2 is brought into the main fluid, and enters the phosphorous acid hydrochloric acid storage tank as the finished product of this process through metering valve 1. Among them, as a continuous process, the molar flow rate of phosphorous acid through metering valve 1 is equal to the number of moles of phosphorus trichloride entering the system.

[0020] S4: The phosphorous acid hydrochloric acid mixture from S3 and the phosphorus trichloride hydrogen chloride gas-liquid mixture from S2 are fully mixed in the diffusion area of the large ejector pump, and a partial reaction occurs quickly to generate a hydrogen chloride - phosphorous acid - hydrochloric acid mixture with a certain pressure, which enters the rotary separation chamber through a conduit and a reaction liquid inlet.

[0021] S5: The reaction liquid from S4 enters the rotary separation chamber at a certain angle to form a swirling liquid flow. On the one hand, this swirling liquid flow continues to disperse a small amount of unreacted phosphorus trichloride liquid droplets and reacts with the water in them. On the other hand, the generated hydrogen chloride gas overflows the liquid surface through swirling separation. Thus, the generated phosphorous acid dissolves in the reaction liquid to form a phosphorous acid - hydrochloric acid solution at the bottom of the swirl, and the generated hydrogen chloride gas overflows the liquid surface through swirling separation.

[0022] S6: At the same time, in the rotary reaction chamber, driven by the liquid flow swirl, the generated gas flow also forms a swirl in the same direction, and part of the liquid droplets entrained by the aerosol are separated by the rotary separator, and the separated liquid droplets flow back to the reaction liquid through the wall of the separator.

[0023] S7: The rising gas stream passes through the scrubbing tower and undergoes mass exchange with saturated hydrochloric acid from the spray heads in the packing layer, further leaching and reacting the small amount of unreacted phosphorus trichloride in the gas stream. The leaching liquid flows back into the reactor.

[0024] S8: The leached hydrogen chloride gas stream is discharged through the hydrogen chloride outlet and is divided into two branches through a T-shaped pipe. One branch enters the small ejector pump to form the source of the hydrogen chloride gas stream in S2, and the other branch mostly enters the condensation and demisting device.

[0025] S9: Through the condensation and demisting device system, a very small amount of phosphorus trichloride in the gas phase is further condensed and demisted and recovered. The recovered liquid flows to the bottom of the demister and flows back into the reaction system through a U-shaped pipe via the demisting liquid return port.

[0026] S10: The hydrogen chloride gas purified by the demister enters the hydrogen chloride absorption system under the guidance of the induced draft fan and is successively recovered through the first-stage absorption tank, the second-stage absorption tank, and the third-stage absorption tank to form concentrated hydrochloric acid, which is stored in the hydrochloric acid storage tank. Part of the hydrochloric acid is metered by a metering pump to form the leaching liquid in S1.

[0027] S11: The residual tail gas from the third-stage absorption tank enters the tail gas scrubbing system under the guidance of the induced draft system: This system uses pure water as the leaching liquid. The leaching liquid is stored at the bottom of the falling film scrubber and, driven by a circulating pump, forms the leaching liquid of the falling film scrubber through a valve, flows from the top of the tower to the bottom of the tower, washes the residual hydrogen chloride gas in the tail gas, and the purified tail gas enters the induced draft system.

[0028] S12: When the leaching liquid of the falling film scrubber reaches a certain concentration, it flows to the washing liquid storage tank through a valve under the drive of a circulating pump and is pumped into the hydrochloric acid absorption tank by an acid-resistant pump for the step-by-step recovery of hydrochloric acid in the third-stage absorption tank in S10.

[0029] Compared with the prior art, the present invention has the following beneficial effects: 1. The effect of the phosphorus trichloride mixture is good, which is conducive to the rapid reaction of phosphorus trichloride. Through a series of steps such as atomization, jet mixing, diffusion mixing, and rotary mixing, the full mixing of phosphorus trichloride and the reaction liquid is ensured.

[0030] 2. The temperature of the reaction system is balanced, avoiding the occurrence of the disproportionation reaction of phosphorus trichloride. The system adopts the mixing method as described above, effectively avoiding the generation of large droplets of phosphorus trichloride at the interface, reducing the microscopic local high-temperature area, and thus effectively suppressing the occurrence of the high-temperature disproportionation reaction.

[0031] 3. Effectively reduces the entrainment of air and avoids the occurrence of the oxidation reaction of phosphorous acid. Since hydrogen chloride generated within the system is used as the atomizing gas source, the entrainment of air is avoided. Hydrochloric acid in the reaction system is used instead of water as the eluent, preventing the entry of dissolved oxygen in water. These measures play a role in isolating air, avoiding the oxidation reaction of phosphorous acid and phosphorus trichloride, and reducing the source of orthophosphoric acid in the product.

[0032] 4. The gas-liquid separation effect of the reaction system is better compared to a conventional stirred reactor. Through the rotary injection of the diffuser tube, a rotary gas flow is formed by the liquid and gas. In the conical rotary separator, the bubbles formed by the reaction quickly burst and are rapidly separated under the action of centrifugal force.

[0033] 5. The residual phosphorus trichloride in the gas phase is low, and the reaction yield is significantly improved. Through the aforementioned high-speed mixing of the phosphorus trichloride raw material, the generation of a high-temperature zone at the interface of the phosphorus trichloride droplets is avoided, and the volatilization amount of phosphorus trichloride is also reduced. Through cyclone separation, hydrochloric acid rinsing, deep condensation, and the foam trap, the content of phosphorus trichloride in the gas phase is further reduced.

[0034] 6. The generation of reaction heat is reduced in principle, and the reaction is more gentle. Using a phosphorous acid solution saturated with hydrochloric acid instead of water as the reaction medium, the hydrogen chloride generated by the reaction directly overflows as a gas, avoiding the generation of the heat of solution of hydrogen chloride. At the same time, phosphorous acid as a reaction product also has a certain inhibitory effect on the hydrolysis intensity of phosphorus trichloride. Description of the Drawings

[0035] Figure 1 is the process flow chart; Figure 2 is the equipment flow chart; Figure 3 is the phosphorus trichloride mixing system; Figure 4 is the structure diagram of the reactor; Figure 5 is the condensation foam trap; Figure 6 is the hydrogen chloride absorption system.

[0036] In the figure: 1. Phosphorous acid hydrochloric acid storage tank; 2. Reaction liquid circulation system: 21. Heat exchanger; 22. Acid-resistant pump; 23. Metering valve 1; 24. Metering valve 2; 3. Phosphorus trichloride mixing system: 31. Small injection pump 1; 32. Large injection pump 2; 33. Phosphorus trichloride metering pump; 34. Conduit; 4. Reactor: 41. Reaction liquid inlet; 42. Reaction liquid outlet; 43. Rotary separation chamber; 44. Packing layer; 45. Spray head; 46. Hydrochloric acid inlet; 47. Hydrogen chloride outlet; 48. Foam trap liquid return port; 5. Condensation foam catcher: 51. Condenser; 52. Foam catcher; 53. Air flow inlet; 54. Air flow outlet; 55. Condensate outlet; 56. Pressure relief port; 6. Hydrochloric acid storage tank; 7. Hydrogen chloride absorption system: 71. Primary absorption tank; 72. Secondary absorption tank; 73. Tertiary absorption tank; 74. Acid-resistant pump; 75. Wash liquor storage tank; 8. Tail gas washing system: 81. Falling film scrubber; 82. Circulation pump; 9. Metering pump. Specific implementation manner

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Embodiment

[0038] Please refer to Figure 1-6 , the present invention provides the following technical solutions: A phosphorus trichloride hydrolysis device includes a phosphorous acid hydrochloric acid storage tank 1, the phosphorous acid hydrochloric acid storage tank 1 is fixedly connected to a reaction liquid circulation system 2. On the one hand, the reaction liquid circulation system 2 is fixedly connected to a phosphorus trichloride mixing system 3. On the other hand, the reaction liquid circulation system 2 is fixedly connected to a reactor 4. The phosphorus trichloride mixing system 3 is also fixedly connected to the reactor 4. On the one hand, the reactor 4 is fixedly connected to a condensation foam catcher 5. On the other hand, the reactor 4 is fixedly connected to a metering pump 9. The metering pump 9 is also fixedly connected to a hydrochloric acid storage tank 6. The condensation foam catcher 5 and the hydrochloric acid storage tank 6 are respectively connected to a hydrogen chloride absorption system 7. The hydrogen chloride absorption system 7 is fixedly connected to a tail gas washing system 8.

[0039] The reaction liquid circulation system 2 includes a metering valve 123 fixedly connected to the phosphorous acid hydrochloric acid storage tank 1. The other end of the metering valve 123 is divided into two branches. One of the branches is fixedly connected to a metering valve 224. The other end of the metering valve 224 is fixedly connected to a phosphorus trichloride mixing system 3. The other branch is fixedly connected to an acid-resistant pump 22. The other end of the acid-resistant pump 22 is fixedly installed with a heat exchanger 21. The other end of the heat exchanger 21 is fixedly connected to a reactor 4.

[0040] The phosphorus trichloride mixing system 3 includes a conduit 34 fixedly installed with the reactor 4. The other end of the conduit 34 is fixedly installed with a large jet pump 232; The large jet pump 232 is divided into two branches. One branch is fixedly connected to the metering valve 224, and the other branch is fixedly connected to the small jet pump 131. One end of the small jet pump 131 is also fixedly connected to the phosphorus trichloride metering pump 33, and phosphorus trichloride is fixedly installed at the other end of the phosphorus trichloride metering pump 33.

[0041] The reactor 4 includes a reaction liquid inlet 41 for fixedly installing the conduit 34. At the top of the reactor 4, there are arranged a hydrogen chloride outlet 47 and a foam-trapping liquid reflux port 48. The reactor 4 is fixedly connected to the condensation foam-trapping device 5 through the hydrogen chloride outlet 47 and the foam-trapping liquid reflux port 48. On the side of the reactor 4, there is also arranged a hydrochloric acid inlet 46. The reactor 4 is fixedly connected to a metering pump 9 through the hydrochloric acid inlet 46. At the lower end face of the reactor 4, there is arranged a reaction liquid outlet 42. The reactor 4 is fixedly connected to a heat exchanger 21 through the reaction liquid outlet 42. Inside the reactor 4, a spray head 45 is fixedly installed on the upper side, and a packing layer 44 is fixedly installed in the middle side. A rotary separation chamber 43 is arranged below the packing layer 44.

[0042] Inside the condensation foam-trapping device 5, a condenser 51 and a foam-trapping device 52 are fixedly installed. The foam-trapping device 52 is installed above the condenser 51. At the bottom side of the condensation foam-trapping device 5, there is arranged a condensate outlet 55, and the condensate outlet 55 is fixedly connected to the foam-trapping liquid reflux port 48. On the side of the condensation foam-trapping device 5, an air flow inlet 53 is also fixedly installed, and the air flow inlet 53 is fixedly connected to the hydrogen chloride outlet 47. On the upper side of the condensation foam-trapping device 5, there are arranged an air flow outlet 54 and a pressure relief port 56, and the air flow outlet 54 is fixedly connected to the hydrogen chloride absorption system 7.

[0043] The hydrogen chloride absorption system 7 includes a primary absorption tank 71, a secondary absorption tank 72, and a tertiary absorption tank 73 that are fixedly connected to the hydrochloric acid storage tank 6 and the air flow outlet 54. The secondary absorption tank 72 is simultaneously fixedly connected to the primary absorption tank 71 and the tertiary absorption tank 73. The tertiary absorption tank 73 is simultaneously fixedly connected to the tail gas washing system 8 and an acid-resistant pump 74. The other end of the acid-resistant pump 74 is fixedly installed with a washing liquid storage tank 75, and the washing liquid storage tank 75 is also fixedly connected to the tail gas washing system 8.

[0044] The tail gas washing system 8 includes a falling film washer 81 that is fixedly connected to the tertiary absorption tank 73. The falling film washer 81 is divided into four branches. The first branch is fixedly connected to water, the second branch is fixedly connected to a circulation pump 82. The circulation pump 82 is divided into two branches. One of the branches is fixedly connected to a valve 83, and the valve 83 is fixedly connected to the third branch of the falling film washer 81. The other branch of the circulation pump 82 is fixedly connected to a valve 84, and the valve 84 is fixedly connected to the washing liquid storage tank 75. The fourth branch of the falling film washer 81 is fixedly connected to the air induction system.

[0045] S1: Start the reaction system. The hydrochloric acid in hydrochloric acid storage tank 6 enters the spray head 45 in reactor 4 through metering pump 9 and hydrochloric acid inlet 46, and performs gas-liquid countercurrent washing in packing layer 44. The washing liquid collects in the rotary separation chamber and mixes with the phosphorous acid hydrochloric acid solution from ejector pump 33. Among them, the concentration of hydrochloric acid is 30% - 31%. The amount of hydrochloric acid entering the system is controlled by metering pump 9. The amount of hydrochloric acid is measured by water, and the number of moles of water is 4 - 6 times the number of moles of phosphorus trichloride neutralized in S2, preferably 4.8 - 5.0 times. S2: Driven by phosphorous acid metering pump 33, phosphorus trichloride enters small ejector pump 31, mixes with part of the hydrogen chloride from hydrogen chloride outlet 47 to form a gas-liquid mixture, and enters the throat area of large ejector pump 32 under the negative pressure suction of large ejector pump 32 through conduit 34. Among them, the amount of phosphorus trichloride entering the system is controlled by phosphorous acid metering pump 33. The number of moles of phosphorus trichloride and the number of moles of water in the hydrochloric acid entering the system in S1 are 1:4 - 6, preferably 1:4.8 - 5.0. S3: The phosphorous acid hydrochloric acid mixture from S1 enters heat exchanger 21 through reaction liquid outlet 42 to be cooled down, and then is driven by acid-resistant pump 22. Under the control of metering valve 123 and metering valve 224, the part entering large ejector pump 32 through metering valve 224. Inside the large ejector pump, through the formed negative pressure area, the phosphorus trichloride hydrogen chloride gas-liquid mixture from S2 is brought into the main fluid, and enters phosphorous acid hydrochloric acid storage tank 1 as the finished product of this process through metering valve 123. Among them, as a continuous process, the molar flow rate of phosphorous acid through metering valve 123 is equal to the number of moles of phosphorus trichloride entering the system. S4: The phosphorous acid hydrochloric acid mixture from S3 and the phosphorus trichloride hydrogen chloride gas-liquid mixture from S2 are fully mixed in the diffusion area of large ejector pump 32, and a partial reaction occurs quickly to generate a hydrogen chloride - phosphorous acid - hydrochloric acid mixture with a certain pressure, which enters rotary separation chamber 43 through conduit 34 and reaction liquid inlet 41. S5: The reaction liquid from S4 enters rotary separation chamber 43 at a certain angle to form a swirling liquid flow. On the one hand, this swirling liquid flow continues to disperse a small amount of unreacted phosphorus trichloride liquid droplets and reacts with the water in them. On the other hand, the generated hydrogen chloride gas overflows from the liquid surface through swirling separation. Thus, the generated phosphorous acid dissolves in the reaction liquid to form a phosphorous acid - hydrochloric acid solution at the bottom of the swirl, and the generated hydrogen chloride gas overflows from the liquid surface through swirling separation. S6: At the same time, in rotary reaction chamber 43, driven by the liquid flow swirl, the generated gas flow also forms a swirl in the same direction, separating some of the liquid droplets entrained by the aerosol through the rotary separator, and the separated liquid droplets flow back to the reaction liquid through the wall of the device. S7: The rising air flow passes through the scrubbing tower, where it undergoes mass exchange with the saturated hydrochloric acid from the spray head 45 in the packing layer 44, further leaching and reacting the small amount of unreacted phosphorus trichloride in the air flow. The leaching solution flows back into the reactor 43; S8: The leached hydrogen chloride air flow is discharged through the hydrogen chloride outlet 47 and is divided into two branches through a T-shaped pipe. One branch enters the small ejector pump 31, constituting the source of the hydrogen chloride air flow in S2, and the other branch mostly enters the condensation and demisting device 5; S9: Through the condensation and demisting device 5 system, a very small amount of phosphorus trichloride in the gas phase is further condensed and demisted and recovered. The recovered liquid flows to the bottom of the demister 52 and returns to the reaction system through a U-shaped pipe via the demisting liquid return port 48; S10: The hydrogen chloride gas purified by the demister enters the hydrogen chloride absorption system 7 under the guidance of the induced draft fan. It is successively recovered through the first-stage absorption tank 71, the second-stage absorption tank 72, and the third-stage absorption tank 73, and concentrated hydrochloric acid is stored in the hydrochloric acid storage tank 6. Part of the hydrochloric acid is metered by the metering pump 9 and constitutes the leaching solution in S1; S11: The residual tail gas from the third-stage absorption tank 73 enters the tail gas scrubbing system 8 under the guidance of the induced draft system. This system uses pure water as the leaching solution, which is stored at the bottom of the falling film scrubber 81. Driven by the circulating pump 82, it forms the leaching solution of the falling film scrubber 81 through the valve 83, flows from the top of the tower to the bottom of the tower, and washes the residual hydrogen chloride gas in the tail gas. The purified tail gas enters the induced draft system; S12: When the leaching solution of the falling film scrubber 81 reaches a certain concentration, it flows through the valve 84 to the scrubbing liquid storage tank 75 under the drive of the circulating pump 82 and is pumped into the hydrochloric acid absorption tank by the acid-resistant pump 74 for the step-by-step recovery of hydrochloric acid in the third-stage absorption tank in S10.

[0046] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A phosphorus trichloride hydrolysis device, comprising a phosphite hydrochloric acid storage tank (1), characterized in that: The phosphite hydrochloric acid storage tank (1) is fixedly connected to a reaction liquid circulation system (2). The reaction liquid circulation system (2) is fixedly connected to a phosphorus trichloride mixing system (3) on one hand. The reaction liquid circulation system (2) is fixedly connected to a reactor (4) on the other hand. The phosphorus trichloride mixing system (3) is also fixedly connected to the reactor (4). The reactor (4) is fixedly connected to a condenser and foam collector (5) on one hand and to a metering pump (9) on the other hand. The metering pump (9) is also fixedly connected to a hydrochloric acid storage tank (6). The condenser and foam collector (5) and the hydrochloric acid storage tank (6) are respectively connected to a hydrogen chloride absorption system (7). The hydrogen chloride absorption system (7) is fixedly connected to an exhaust gas scrubbing system (8).

2. A phosphorus trichloride hydrolysis device according to claim 1, characterized in that: The reaction liquid circulation system (2) comprises a metering valve 1 (23) fixedly connected to a phosphite hydrochloric acid storage tank (1); the other end of the metering valve 1 (23) is divided into two branches, one of which is fixedly connected to a metering valve 2 (24); the other end of the metering valve 2 (24) is fixedly connected to a phosphorus trichloride mixing system (3); the other branch is fixedly connected to an acid-resistant pump (22); the other end of the acid-resistant pump (22) is fixedly mounted with a heat exchanger (21); the other end of the heat exchanger (21) is fixedly connected to a reactor (4).

3. A phosphorus trichloride hydrolysis device according to claim 1, characterized in that: The phosphorus trichloride mixing system (3) comprises a conduit (34) fixedly mounted on the reactor (4), and a large jet pump 2 (32) is fixedly mounted on the other end of the conduit (34); The large jet pump 2 (32) is divided into two branches, one of which is fixedly connected to the metering valve 2 (24), and the other is fixedly connected to the small jet pump 1 (31). One end of the small jet pump 1 (31) is also fixedly connected to a phosphorus trichloride metering pump (33), and phosphorus trichloride is fixedly installed on the other end of the phosphorus trichloride metering pump (33).

4. A phosphorus trichloride hydrolysis device according to claim 1, characterized in that: The reactor (4) comprises a reaction liquid inlet (41) for fixing a guide tube (34). A hydrogen chloride outlet (47) and a foaming liquid reflux port (48) are arranged at the top of the reactor (4). The reactor (4) is fixedly connected to a condensing foaming trap (5) via the hydrogen chloride outlet (47) and the foaming liquid reflux port (48). A hydrochloric acid inlet (46) is also arranged at the side of the reactor (4). The reactor (4) is fixedly connected to a metering pump (9) via the hydrochloric acid inlet (46). A reaction liquid outlet (42) is arranged at the lower end surface of the reactor (4). The reactor (4) is fixedly connected to a heat exchanger (21) via the reaction liquid outlet (42). A spray head (45) is fixedly installed at the upper side of the reactor (4). A packing layer (44) is fixedly installed at the middle side of the reactor (4). A rotating separation chamber (43) is arranged at the lower side of the packing layer (44).

5. A phosphorus trichloride hydrolysis device according to claim 1 or 4, characterized in that: A condenser (51) and a foam trap (52) are fixedly mounted inside the condenser foam trap (5); the foam trap (52) is mounted on the upper side of the condenser (51); a condensate outlet (55) is arranged on the bottom side of the condenser foam trap (5); the condensate outlet (55) is fixedly connected to a foam trap return port (48); an airflow inlet (53) is also fixedly mounted on the side of the condenser foam trap (5); the airflow inlet (53) is fixedly connected to a hydrogen chloride outlet (47); an airflow outlet (54) and a pressure relief port (56) are arranged on the upper side of the condenser foam trap (5); the airflow outlet (54) is fixedly connected to a hydrogen chloride absorption system (7).

6. A phosphorus trichloride hydrolysis device according to claim 1, characterized in that: The hydrogen chloride absorption system (7) comprises a primary absorption tank (71), a secondary absorption tank (72), and a tertiary absorption tank (73) which are fixedly connected to the hydrochloric acid storage tank (6) and the gas flow outlet (54); the secondary absorption tank (72) is fixedly connected to the primary absorption tank (71) and the tertiary absorption tank (73); the tertiary absorption tank (73) is fixedly connected to the tail gas scrubbing system (8) and the acid-resistant pump (74); a scrubbing liquid storage tank (75) is fixedly installed at the other end of the acid-resistant pump (74); and the scrubbing liquid storage tank (75) is also fixedly connected to the tail gas scrubbing system (8).

7. A phosphorus trichloride hydrolysis device according to claim 1, characterized in that: The tail gas scrubbing system (8) comprises a falling film scrubber (81) fixedly connected to a tertiary absorption tank (73), the falling film scrubber (81) being divided into four branches, the first branch being fixedly connected to water, the second branch being fixedly connected to a circulation pump (82), the circulation pump (82) being divided into two branches, one of the branches being fixedly connected to a valve (83), the valve (83) being fixedly connected to a third branch of the falling film scrubber (81), the other branch of the circulation pump (82) being fixedly connected to a valve (84), the valve (84) being fixedly connected to a scrubbing liquid storage tank (75), and the fourth branch of the falling film scrubber (81) being fixedly connected to an induced draft system.

8. A phosphorus trichloride hydrolysis process, characterized in that: S1: Start the reaction system, the hydrochloric acid in the hydrochloric acid storage tank (6) enters the spray head (45) in the reactor (4) through the hydrochloric acid inlet (46) of the metering pump (9), and is eluted in gas-liquid countercurrent in the packing layer (44). The elution liquid is collected in the rotary separation chamber and mixed with the phosphorous acid hydrochloric acid solution from the injection pump (33); S2: Driven by the phosphorus trichloride metering pump (33), the phosphorus trichloride enters the small jet pump (31), mixes with part of the hydrogen chloride from the hydrogen chloride outlet (47), forms a gas-liquid mixture, and enters the throat area of ​​the large jet pump (32) through the conduit (34) under the negative pressure suction of the large jet pump (32); S3: The phosphite-hydrochloric acid mixed liquid from S1 enters the heat exchanger (21) through the reaction liquid outlet (42) to cool down, and then is driven by the acid-resistant pump (22). Under the control of the metering valve 1 (23) and the metering valve 2 (24), the liquid enters the large jet pump (32) through the metering valve 2 (24). Inside the large jet pump, the phosphorus trichloride-hydrochloride gas-liquid mixture from S2 is brought into the main fluid through the negative pressure zone formed, and then enters the phosphite-hydrochloric acid storage tank (1) as the finished product of this process through the metering valve 1 (23); S4: The phosphorous acid-hydrochloric acid mixture from S3 and the phosphorus trichloride-hydrochloric acid gas-liquid mixture from S2 are fully mixed in the diffusion zone of the large jet pump (32), and a partial reaction occurs quickly to generate a hydrogen chloride-phosphorous acid-hydrochloric acid mixture with a certain pressure, which enters the rotating separation chamber (43) through the conduit (34) and the reaction liquid inlet (41); S5: The reaction liquid from S4 enters the rotating separation chamber (43) at a certain angle to form a vortex liquid flow. On the one hand, the vortex liquid flow continues to disperse a small amount of unreacted phosphorus trichloride droplets and reacts with the water therein. On the other hand, the generated hydrogen chloride gas overflows the liquid surface through vortex separation. As a result, the phosphorous acid generated by the reaction dissolves in the reaction liquid to form a phosphorous acid-hydrochloric acid solution at the bottom of the vortex, and the generated hydrogen chloride gas overflows the liquid surface through vortex separation. S6: At the same time, in the rotating reaction chamber (43), driven by the liquid flow vortex, the generated airflow also forms a vortex in the same direction, and some liquid droplets entrained by the aerosol are separated through the rotating separator, and the separated liquid droplets flow back to the reaction liquid through the wall of the device; S7: The rising gas flow passes through the scrubbing tower and exchanges substances with saturated hydrochloric acid from the shower head (45) in the packing layer (44), further eluting the small amount of unreacted phosphorus trichloride in the gas flow, and the elution liquid flows back into the reactor (43); S8: The hydrogen chloride gas flow after elution is discharged through the hydrogen chloride outlet (47), and is divided into two branches through a T-shaped pipe. One branch enters the small jet pump (31) to form the hydrogen chloride gas flow source of S2, and the other branch enters the condenser (5); S9: The very small amount of phosphorus trichloride in the gas phase is further condensed and foamed and recovered through the condensation and foaming device (5) system, and the recovered liquid flows to the bottom of the foaming device (52), and then flows back into the reaction system through the foaming liquid reflux port (48) through the U-shaped tube; S10: The hydrogen chloride gas purified by the foam collector enters the hydrogen chloride absorption system (7) under the guidance of the induced draft fan, and is recovered step by step through the primary absorption tank (71), the secondary absorption tank (72), and the tertiary absorption tank (73) to form concentrated hydrochloric acid which is stored in the hydrochloric acid storage tank (6). Part of the hydrochloric acid is metered by the metering pump (9) to form the eluent of S1; S11: The residual tail gas from the tertiary absorption tank (73) enters the tail gas washing system (8) under the guidance of the induced draft system: the system uses pure water as the eluent, and the eluent is stored at the bottom of the falling film scrubber (81). Driven by the circulation pump (82), the eluent of the falling film scrubber (81) is formed through the valve (83), flows from the top of the tower to the bottom of the tower, and washes the residual hydrogen chloride gas in the tail gas. The purified tail gas enters the induced draft system; S12: After the eluent of the falling film scrubber (81) reaches a certain concentration, it is driven by the circulation pump (82) and flows through the valve (84) to the scrubbing liquid storage tank (75), and is pumped into the hydrochloric acid absorption tank by the acid-resistant pump (74) to be used for the step-by-step recovery of the hydrochloric acid in the tertiary absorption tank of S10.

Images