Anhydrous formic acid preparation process and preparation device

Abstract

The invention discloses an anhydrous formic acid preparation process and a preparation device, and relates to the technical field of anhydrous formic acid preparation, and the preparation device comprises a reboiler, a condenser, a liquid collection part, a cleaning part and a wire mesh demister. The invention further discloses an anhydrous formic acid preparation process which comprises the following steps: feeding raw materials, purifying, hydrolyzing, separating, dehydrating and collecting. The liquid is heated by arranging the reboiler, the heated liquid forms steam which rises upwards and passes through the cooler, one part of the steam continuously rises upwards and passes through the wire mesh demister, liquid drops in the steam are separated, the other part of the liquid is liquefied and flows back to the reboiler, and after the liquid drops in the steam are separated by the wire mesh demister, the liquid drops in the steam are separated by the wire mesh demister. The liquid drops flow into the liquid collecting tank; when the pipeline in the condenser is blocked, the cleaning part is utilized to dredge the pipeline of the condenser, the dredged impurities are cleaned into the liquid collecting part, and the pipeline in the condenser is cleaned in a non-stop state, so that the working efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical reaction and separation, and in particular relates to a process and a device for preparing anhydrous formic acid. Background Art

[0002] Anhydrous formic acid is a strongly acidic organic compound. It is a colorless liquid with a pungent odor and is often used as a raw material and solvent in industrial production. Anhydrous formic acid is usually obtained by hydrolysis of methyl formate during the manufacturing process. It is widely used in chemical synthesis, leather processing, food additives and drug production. Due to its strong acidity and reducing properties, anhydrous formic acid acts as an important reactant in many reactions.

[0003] The patent with publication number CN118439943A discloses a method for preparing industrial-grade formic acid by hydrolyzing methyl formate. The method adopts a reactive distillation bulkhead tower to carry out the hydrolysis reaction of methyl formate and the separation of formic acid and water; the reactive distillation bulkhead tower comprises a reactive distillation section, a common distillation section, a wastewater distillation section, and a crude acid stripping section. A pressurized reactive distillation bulkhead tower is used to carry out the hydrolysis of methyl formate to produce formic acid, and a solid acid catalyst filler is installed in the reactive distillation section. Under the reaction conditions, the problem of difficulty in separating the azeotropic mixture of water and formic acid can be effectively avoided, and the equipment cost and energy consumption are reduced. In the reactive distillation bulkhead tower, under the catalytic action of the solid acid catalyst, the conversion rate of methyl formate is greater than 99%; and the provided method can simultaneously complete the hydrolysis of methyl formate and the purification of formic acid solution under a pressurized environment, reducing the equipment cost, separation cost and energy consumption.

[0004] However, in actual production, it was found that the above technical solution still has problems: the above solution is prone to blockage in the condenser during use, and the impurities carried by the steam when passing through the pipeline will accumulate inside it, causing the pipeline to be blocked, resulting in the accumulation of rising steam in the distillation tower. As the steam continues to rise, the pressure in the distillation tower continues to increase, which reduces the purity of the product separation and causes the equipment pressure to exceed the standard, thereby causing damage.

[0005] Therefore, it is necessary to invent a process and device for preparing anhydrous formic acid to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to provide a process and device for preparing anhydrous formic acid in order to solve the problems mentioned above.

[0007] The present invention provides an anhydrous formic acid preparation device, comprising a distillation tower; a hydrolysis reactor, the top of which is connected to the bottom of the distillation tower through a pipeline; a gas-liquid separator, the bottom of which is connected to the bottom of the hydrolysis reactor through a pipeline; a reactor, the top of which is connected to the top of the gas-liquid separator through a pipeline; a dehydration device, the top of which is connected to the top of the distillation tower through a pipeline; a product collection tank, the top of which is connected to the bottom of the dehydration device through a pipeline; the distillation tower comprises: a tower body; a reboiler, which is fixedly arranged at the bottom of the tower body, and the reboiler can heat the liquid at the bottom of the tower body, so that the heated liquid The liquid evaporates and becomes steam that rises; a condenser, which is fixedly arranged at the top of the tower body and can cool the rising steam; a liquid collecting part, which is arranged at the top of the condenser and can collect liquid droplets, and the collected liquid droplets flow back to the reboiler through the liquid collecting part for heating; a cleaning part, which is arranged in the condenser and can move up and down in the condenser and dredge the components in the condenser; a wire mesh demister, which is fixedly arranged at the top of the tower body and fixedly arranged above the condenser, and can separate liquid droplets in the steam, and the separated liquid droplets are collected by the liquid collecting part.

[0008] Preferably, the reboiler includes: an annular cylinder, which is fixedly arranged at the bottom of the tower body; a heat exchange tube, which is fixedly arranged inside the annular cylinder and can heat the liquid; a high-temperature liquid inlet, which is connected to one end of the heat exchange tube, and the other end of the high-temperature liquid inlet is sealed to pass through the tower body and the annular cylinder and extend out of the outer wall of the tower body; a high-temperature liquid outlet, which is connected to one end of the heat exchange tube, and the other end of the high-temperature liquid outlet is sealed to pass through the tower body and the annular cylinder and extend out of the outer wall of the tower body, and the high-temperature liquid outlet is in a relative position to the high-temperature liquid inlet; a first air outlet, which is provided in multiple groups and opened at the top of the annular cylinder; an insulating cavity, which is opened inside the annular cylinder; a heating tube, which is provided in multiple groups and is located between the tubes of the heat exchange tube; a channel, which is provided in multiple groups and fixedly arranged at the top of the heating tube.

[0009] Preferably, the condenser includes: a condensation cylinder, which is arranged at the top of the tower body and has cooling water inside to cool the steam; an air outlet pipe, which is fixedly arranged at the top of the condensation cylinder; spiral tubes, which are arranged in multiple groups, and the tops of the multiple groups of spiral tubes are connected to the air outlet pipes; and the bottoms of the multiple groups of spiral tubes are fixedly arranged to the bottom of the condensation cylinder; a concave conical groove, which is fixedly arranged at the bottom of the condensation cylinder; and air inlet holes, which are arranged in multiple groups and opened between the concave conical grooves and the condensation cylinder, and the tops of the multiple groups of air inlet holes are connected to the bottoms of the corresponding spiral tubes.

[0010] Preferably, the condenser also includes: an annular cylinder, which is fixedly arranged on the top of the condensing cylinder; second air outlet holes, which are provided in multiple groups and opened on the top of the annular cylinder, and the multiple groups of second air outlet holes are staggered with the air outlet pipe; a sleeve, whose inner wall is fixedly arranged on the outer wall of the condensing cylinder, and whose outer wall is fixedly arranged on the top of the tower body.

[0011] Preferably, the condenser also includes: a liquid inlet pipe, which is connected to one end of the condensing cylinder, and the other end of which seals and passes through the sleeve and the tower body and extends out of the outer wall of the tower body; a liquid outlet pipe, which is connected to one end of the condensing cylinder, and the other end of which seals and passes through the sleeve and the tower body and extends out of the outer wall of the tower body, and the liquid outlet pipe is in a relative position to the liquid inlet pipe.

[0012] Preferably, the liquid collecting part also includes: a collecting chamber, which is opened between the outer wall of the condensing cylinder and the inner wall of the sleeve and is located at the top of both; a filter screen, which is arranged in the collecting chamber; leakage holes, which are arranged in multiple groups and are opened between the bottom of the annular cylinder and the top connection of the condensing cylinder; leakage pipes, which are arranged in multiple groups, and the tops of the multiple groups of leakage pipes are connected to the top of the collecting chamber.

[0013] Preferably, the cleaning part includes: a first annular cavity, which is opened between the outer wall of the condensation tube and the inner wall of the sleeve and is located in the middle of the two; a first annular plate, which is sealingly slidably arranged in the first annular cavity; a second annular cavity, which is opened between the outer wall of the condensation tube and the inner wall of the sleeve and is located at the bottom of the two; a second annular plate, which is sealingly slidably arranged in the second annular cavity; springs, which are arranged in multiple groups and fixedly arranged between the top of the second annular cavity and the top of the second annular plate; connecting columns, which are arranged in multiple groups and fixedly arranged at the bottom of the first annular plate.

[0014] Preferably, the cleaning part also includes: a circular tube, the bottom of which is embedded in the top of the condensation cylinder and the top of which is higher than the top of the condensation cylinder; nozzles, which are arranged in multiple groups and fixedly arranged on the top of the circular tube, and the jet directions of the multiple groups of nozzles are toward the leakage hole; airflow tubes, which are arranged in multiple groups, and the tops of the multiple groups of airflow tubes are connected to the bottom of the circular tube, and the bottoms are connected to the bottom of the first annular cavity.

[0015] Preferably, the cleaning part also includes: ventilation pipes, which are arranged in multiple groups and correspond to the spiral tubes, the tops of the multiple groups of ventilation pipes are connected to the tops of the first annular cavity, and the bottoms of the multiple groups of ventilation pipes are connected to the bottoms of the corresponding spiral tubes; solenoid valves, which are arranged in multiple groups and correspond to the spiral tubes, and the solenoid valves are fixedly arranged at the bottom of the spiral tubes and located below the ventilation pipes.

[0016] The present invention also discloses a process for preparing anhydrous formic acid, comprising the following steps: Step 1: adding raw materials, reacting the raw materials in a reactor to generate a methyl formate mixed solution; Step 2: Purification: purifying the generated methyl formate mixed liquid in a gas-liquid separator to obtain methyl formate; Step 3: hydrolysis, hydrolyzing methyl formate in a hydrolysis reactor to obtain a mixed solution containing formic acid; Step 4: separation, separating the water and formic acid in the mixed solution in a distillation tower to obtain relatively pure anhydrous formic acid; Step 5: Dehydration: anhydrous formic acid enters the dehydration equipment in the form of steam to remove water; Step six: collecting, collecting the anhydrous formic acid from which water has been removed into a product collection tank to obtain the final product.

[0017] The beneficial effects of the present invention are: 1. The present invention cooperates with the first annular cavity, the first annular plate, the connecting column and the second annular plate. When the air pressure below the condenser increases, the solenoid valve closes the air inlet at the bottom of the spiral tube. At this time, the increased pressure pushes the second annular plate to move upward, so that the second annular plate drives the first annular plate to slide in the first annular cavity through the connecting column and squeezes the gas in the upper cavity. The squeezed gas enters the spiral tube through the ventilation pipe for dredging, and the impurities inside it are discharged to the top of the condenser through the outlet pipe, thereby improving the purity of product separation and realizing self-cleaning without stopping the machine, thereby improving work efficiency.

[0018] 2. The present invention cooperates with the first annular cavity, the first annular plate, the connecting column, the second annular plate and the spring. When the spiral pipe is unblocked, the pressure between the condenser and the reboiler is restored, and the compressed spring drives the second annular plate to move downward. During the downward movement of the second annular plate, the connecting column drives the first annular plate to squeeze the gas in the lower cavity. The squeezed gas flows into the circular tube through the airflow tube and is sprayed out through the nozzle, thereby cleaning the impurities cleaned out of the spiral tube at the top of the condenser tube, avoiding the flow of droplets affected by the impurities adhering to the protruding conical surface of the top of the condenser tube, thereby improving the flow effect of the droplets. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of the anhydrous formic acid preparation device of the present invention.

[0020] Figure 2 It is a schematic cross-sectional view of a distillation tower according to the present invention.

[0021] Figure 3 It is a schematic diagram of the reboiler structure of the present invention.

[0022] Figure 4 It is a schematic diagram of the condenser structure of the present invention.

[0023] Figure 5It is a schematic diagram of the cross-sectional structure of the condenser of the present invention.

[0024] Figure 6 It is a schematic diagram of the cross-sectional structure of the liquid collecting part in the present invention.

[0025] Figure 7 It is a schematic diagram of the cross-sectional structure of the cleaning part of the present invention.

[0026] Figure 8 It is a schematic diagram of the state when the first annular plate of the present invention is located at a first height.

[0027] In the figure: 1, distillation tower; 2, hydrolysis reactor; 3, gas-liquid separator; 4, reactor; 5, dehydration equipment; 6, product collection tank; 7, reboiler; 8, condenser; 9, liquid collection part; 10, cleaning part; 11, wire mesh demister; 12, tower body; 7001, annular cylinder; 7002, heat exchange tube; 7003, high-temperature liquid inlet; 7004, high-temperature liquid outlet; 7005, first air outlet; 7006, insulation cavity; 7007, heating tube; 7008, channel; 8001, condensation cylinder; 8002, air outlet pipe; 8003, spiral tube; 8004, concave Conical groove; 8005, air inlet; 8006, annular cylinder; 8007, second air outlet; 8008, sleeve; 8009, liquid inlet pipe; 8010, liquid outlet pipe; 9001, collecting chamber; 9002, filter screen; 9003, leakage hole; 9004, leakage pipe; 1001, first annular chamber; 1002, first annular plate; 1003, second annular chamber; 1004, second annular plate; 1005, spring; 1006, connecting column; 1007, round tube; 1008, nozzle; 1009, air flow pipe; 1010, ventilation pipe; 1011, solenoid valve. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0029] Embodiment 1, the present invention provides as Figures 1 to 8 The anhydrous formic acid preparation device shown includes a distillation tower 1; a hydrolysis reactor 2, the top of which is connected to the bottom of the distillation tower 1 through a pipeline; a gas-liquid separator 3, the bottom of which is connected to the bottom of the hydrolysis reactor 2 through a pipeline; a reactor 4, the top of which is connected to the top of the gas-liquid separator 3 through a pipeline; a dehydration device 5, the top of which is connected to the top of the distillation tower 1 through a pipeline; and a product collecting tank 6, the top of which is connected to the bottom of the dehydration device 5 through a pipeline.

[0030] The raw materials are put into the reactor 4 for reaction. The raw materials after the reaction generate a methyl formate mixed liquid. The methyl formate mixed liquid after the reaction is then introduced into the gas-liquid separator 3 through a pipeline, so that the methyl formate mixed liquid after the reaction is purified by the gas-liquid separator 3. The purified methyl formate mixed liquid generates methyl formate. The methyl formate is introduced into the hydrolysis reactor 2 through a pipeline, and the purified methyl formate is hydrolyzed to obtain a mixed solution containing formic acid. The hydrolyzed formic acid mixed solution is introduced into the distillation tower 1 through a pipeline, and the formic acid mixed solution is separated to obtain relatively pure formic acid. The formic acid is introduced into the dehydration device 5 in the form of formic acid vapor through a pipeline, and water is removed in the dehydration device 5 to obtain anhydrous formic acid. The anhydrous formic acid flows to the product collecting tank 6 through a pipeline to finally form an anhydrous formic acid product.

[0031] The distillation tower 1 comprises: a tower body 12; a reboiler 7, which is fixedly arranged at the bottom of the tower body 12, and the reboiler 7 can heat the liquid at the bottom of the tower body 12, so that the heated liquid evaporates and turns into steam to rise; it comprises an annular cylinder 7001, and a plurality of inclined holes are arranged in the top of the annular cylinder 7001 for discharging the droplets falling from the top, which is fixedly arranged at the bottom of the tower body 12, and a gap is reserved between the outer wall of the annular cylinder 7001 and the inner wall of the tower body 12, so that the droplets falling from the top of the annular cylinder 7001 can flow to the bottom of the annular cylinder 7001 through the gap, and a plurality of groups of fixed blocks are fixedly arranged on the outer side wall of the bottom of the annular cylinder 7001, and the plurality of groups of fixed blocks are fixed on the tower body 1 2 corresponding position of the inner wall at the bottom to fix the annular tube 7001; the heat exchange tube 7002 is fixedly arranged inside the annular tube 7001, which can heat the liquid. The heat exchange tube 7002 is composed of multiple groups of straight tubes and annular tubes. The multiple groups of annular tubes are located at the top and bottom of the corresponding multiple groups of straight tubes, and the multiple groups of straight tubes are in a connected state with the multiple groups of annular tubes. The high-temperature liquid flows into the straight tubes through the annular tubes at the bottom, and then flows into the annular tubes at the top, which is convenient for heating the liquid; the high-temperature liquid inlet 7003 is connected to one end of the heat exchange tube 7002, and the high-temperature liquid inlet 7003 is connected to the annular tube at the bottom of the straight tube, and the high-temperature liquid inlet 7003 is connected to the annular tube at the bottom of the straight tube. The other end is sealed and passes through the tower body 12 and the annular tube 7001 and extends out of the outer wall of the tower body 12, which is connected to the external high-temperature liquid pipeline and is used to provide high-temperature liquid to the heat exchange tube 7002; the high-temperature liquid outlet 7004 is connected to one end of the heat exchange tube 7002, the high-temperature liquid outlet 7004 is connected to the annular tube at the top of the straight tube, and the other end of the high-temperature liquid outlet 7004 is sealed and passes through the tower body 12 and the annular tube 7001 and extends out of the outer wall of the tower body 12, and its external connection is connected with a pipeline for discharging the high-temperature liquid in the heat exchange tube 7002, and the high-temperature liquid outlet 7004 is in a relative position to the high-temperature liquid inlet 7003. The port 7004 is used to replace the high-temperature liquid in the heat exchange tube 7002, further improving the effect of the heat exchange tube 7002 on heating the liquid; the first air outlet 7005 is provided with multiple groups and opened at the top of the annular tube 7001, and the multiple groups of first air outlets 7005 are staggered with the heating tube 7007 to prevent the liquid droplets from flowing into the heating tube 7007; the liquid droplets at the top of the annular tube 7001 are discharged through the inclined groove opened on the outer wall of the annular tube 7001; the heat insulation cavity 7006 can prevent the reboiler 7 from exchanging heat with the liquid outside the annular tube 7001, thereby improving the heating effect of the heat exchange tube 7002, and it is opened inside the annular tube 7001;The heating tubes 7007 are provided in multiple groups and are located between the tubes of the heat exchange tubes 7002. The top of the heating tubes 7007 is higher than the top of the heat exchange tubes 7002, and the upper and lower ends of the heating tubes 7007 are in a through-state. The liquid at the bottom of the tower body 12 enters the heating tubes 7007 from the bottom of the heating tubes 7007; a collecting trough is formed between adjacent heating tubes 7007 and the top of the heat exchange tubes 7002, and the collecting trough is aligned with the first air outlet 7005 to guide the falling liquid droplets to be discharged; the channels 7008 are provided in multiple groups and are fixedly arranged on the heating tubes 700 7, the channel 7008 is connected to the collecting tank; when the liquid refluxed from above falls, part of the liquid flows through the top of the annular cylinder 7001 to the reserved gap between the outer wall of the annular cylinder 7001 and the inner wall of the tower body 12, and enters the bottom of the heating tube 7007 through the gap to be heated again; the other part of the falling liquid falls into the collecting tank through the first air outlet 7005, and is discharged into the reserved gap between the outer wall of the annular cylinder 7001 and the inner wall of the tower body 12 through the channel 7008 and the chute, and enters the bottom of the heating tube 7007 through the gap. ;

[0032] The condenser 8 is fixedly arranged at the top of the tower body 12, and the condenser 8 can cool the rising steam; it includes a condensation cylinder 8001, the top of which is arranged as a convex conical surface to facilitate the flow of droplets to both sides, which is arranged at the top of the tower body 12, and cooling water is arranged inside it to cool the steam; an outlet pipe 8002 is used for the discharge of steam, which is fixedly arranged at the top of the condensation cylinder 8001; a spiral tube 8003 has a spiral outer shape, which can increase the contact area of ​​the steam, so that the steam can obtain a better cooling effect, and is arranged in multiple groups, and the multiple groups of spiral tubes The top of 8003 is connected to the outlet pipe 8002; the bottom of the multiple groups of spiral tubes 8003 is fixedly arranged with the bottom of the condensation cylinder 8001; the concave conical groove 8004 is fixedly arranged at the bottom of the condensation cylinder 8001 for guiding the steam; the air inlet holes 8005 are arranged in multiple groups and opened between the concave conical grooves 8004 and the condensation cylinder 8001, and the tops of the multiple groups of air inlet holes 8005 are connected with the bottoms of the corresponding spiral tubes 8003, and the steam is guided into the air inlet holes 8005 through the concave conical grooves 8004, so that the steam in the air inlet holes 8005 enters the spiral tube 8003 ; annular cylinder 8006, which is fixedly arranged on the top of condensing cylinder 8001, second air outlet 8007, which is provided with multiple groups and opened on the top of annular cylinder 8006, and multiple groups of second air outlet 8007 are staggered with air outlet pipe 8002 to prevent liquid droplets from flowing into spiral tube 8003 through air outlet pipe 8002, thereby affecting the rise of steam; sleeve 8008, whose inner wall is fixedly arranged with the outer wall of condensing cylinder 8001, and whose outer wall is fixedly arranged at the top of tower body 12; liquid inlet pipe 8009, which is connected to the external cooling pipeline to provide cooling liquid for it, and is connected to the cooling One end of the condenser cylinder 8001, and the other end is sealed to pass through the sleeve 8008 and the tower body 12 and extend out of the outer wall of the tower body 12; a liquid outlet pipe 8010, which is connected to the external cooling pipe and is used to discharge the cooling liquid, is connected to one end of the condenser cylinder 8001, and the other end is sealed to pass through the sleeve 8008 and the tower body 12 and extend out of the outer wall of the tower body 12, the liquid outlet pipe 8010 and the liquid inlet pipe 8009 are in a relative position, through the arrangement of the liquid inlet pipe 8009 and the liquid outlet pipe 8010, it is convenient to replace the cooling liquid in the condenser cylinder 8001, so that the cooling liquid always maintains the effect of cooling the steam.

[0033] The liquid collecting part 9 is arranged in the top of the condenser 8, and can collect the liquid droplets separated by the wire mesh demister 11. The collected liquid droplets flow back to the reboiler 7 through the liquid collecting part 9 for heating; it includes a collecting chamber 9001, which is opened between the outer wall of the condenser cylinder 8001 and the inner wall of the sleeve 8008 and is located at the top of both; a filter screen 9002, which is arranged in the collecting chamber 9001 and is used to filter impurities; a leakage hole 9003, which is arranged in a plurality of groups and is opened between the bottom of the annular cylinder 8006 and the top connection of the condenser cylinder 8001, by The convex conical surface arranged at the top of the condensation cylinder 8001 facilitates the flow of liquid droplets falling from above and flows into the collecting chamber 9001 through the leakage hole 9003; there are multiple groups of leakage tubes 9004, and the tops of the multiple groups of leakage tubes 9004 are connected to the top of the collecting chamber 9001, and a one-way valve is arranged at the bottom of the leakage tube 9004. The liquid droplets in the collecting chamber 9001 flow into the leakage tube 9004, and the liquid opens the one-way valve and flows into the bottom of the tower body 12 through the gap reserved between the outer wall of the annular cylinder 7001 and the inner wall of the tower body 12 to be heated and evaporated again.

[0034] The wire mesh demister 11 is fixedly arranged at the top of the tower body 12 and above the condenser 8, and is capable of separating liquid droplets in the steam.

[0035] In summary, the formic acid mixed solution is introduced into the bottom of the tower body 12 through the pipeline and enters the heating tube 7007. The heat exchange tube 7002 heats the liquid in the heating tube 7007. The liquid is heated and boiled to form steam. The steam is discharged through the first air outlet 7005 on the annular cylinder 7001 and rises. During the rising process, the steam enters the air inlet 8005 along the concave conical groove 8004, and flows to the two groups of spiral tubes 8003 through the air inlet 8005, so that the steam is cooled. A part of the cooled steam becomes liquid and flows downward through the spiral tube 8003. The condensed liquid contacts the rising steam during the reflux process, so that the light components such as formic acid are transferred from the liquid phase to the gas phase, and the heavy components such as water are transferred from the gas phase to the liquid phase, so that the liquid falls into the annular cylinder 70 01 top; another part of the steam continues to rise from the spiral tube 8003 and flows out from the air outlet pipe 8002. The steam after flowing out enters the annular cylinder 8006, is discharged through the second air outlet 8007 above the annular cylinder 8006, and continues to rise to the wire mesh demister 11, and the wire mesh demister 11 removes the droplets in the steam. The removed droplets fall to the top of the annular cylinder 8006 or fall to the top of the condensation cylinder 8001 through the second air outlet 8007, and then flow into the collecting chamber 9001. The droplets in the collecting chamber 9001 flow into the bottom of the tower body 12 through the leakage pipe 9004 to be heated again; while removing the droplets in the steam, the steam flows through the outlet at the top of the tower body 12 to the dehydration equipment 5 to remove water and form the final anhydrous formic acid product.

[0036] Example 2. Based on the above example, due to the long-term use of spiral tube 8003, impurities carried in the steam will accumulate inside the spiral tube 8003 when passing through it, thereby causing the spiral tube 8003 to be blocked, resulting in the accumulation of rising steam below the condenser 8. As the steam continues to rise, the pressure in the tower body 12 continues to increase, causing the purity of the product separation to decrease, resulting in the equipment pressure exceeding the standard; the following improvements have been made for this purpose.

[0037] like Figures 5 to 8As shown, it also includes a cleaning part 10, which is arranged in the condenser 8, and the cleaning part 10 can move up and down in the condenser 8 and clear the components in the condenser 8; it includes a first annular cavity 1001, which is opened between the outer wall of the condenser cylinder 8001 and the inner wall of the sleeve 8008 and is located in the middle of the two. A plurality of one-way valves are arranged on the top of the first annular cavity 1001, and the plurality of one-way valves are higher than the top of the collecting cavity 9001 to prevent the one-way valves from sucking liquid in the collecting cavity 9001 when inhaling. The body is sucked into the first annular cavity 1001; the first annular plate 1002 is sealingly slidably disposed in the first annular cavity 1001, and the first annular plate 1002 divides the first annular cavity 1001 into two parts, namely the upper cavity and the lower cavity; the second annular cavity 1003 is opened between the outer wall of the condensing cylinder 8001 and the inner wall of the sleeve 8008 and is located at the bottom of both; the second annular plate 1004 is sealingly slidably disposed in the second annular cavity 1003; the spring 1005 The connecting column 1006 is arranged in multiple groups and fixedly arranged between the top of the second annular cavity 1003 and the top of the second annular plate 1004; the connecting column 1006 is arranged in multiple groups and fixedly arranged at the bottom of the first annular plate 1002, and passes through the first annular cavity 1001 to the second annular cavity 1003 and is fixedly arranged at the top of the second annular plate 1004, so that the first annular plate 1002 and the second annular plate 1004 move up and down synchronously; the circular tube 1007, the bottom of which is embedded in the condensation cylinder 8001 The top of the plurality of airflow tubes 1009 is higher than the top of the condensation cylinder 8001; the nozzles 1008 are arranged in a plurality of groups and are opened at the top of the circular tube 1007, and the spray direction of the plurality of groups of nozzles 1008 is toward the leakage hole 9003, so as to facilitate the cleaning of droplets or impurities; the airflow tubes 1009 are arranged in a plurality of groups, and the tops of the plurality of groups of airflow tubes 1009 are connected with the bottom of the circular tube 1007, and the bottoms thereof are connected with the bottom of the first annular cavity 1001, that is, they are connected with the lower cavity of the first annular cavity 1001. The ventilation tubes 1010 are arranged in multiple groups and correspond to the spiral tubes 8003. The tops of the multiple groups of ventilation tubes 1010 are connected to the tops of the first annular cavity 1001, and the bottoms of the multiple groups of ventilation tubes 1010 are connected to the bottoms of the corresponding spiral tubes 8003, and are located above the connection between the bottoms of the spiral tubes 8003 and the air inlet 8005; the solenoid valves 1011 are electrically connected to the control system, are arranged in multiple groups and correspond to the spiral tubes 8003, and the solenoid valves 1011 are fixedly arranged at the bottom of the spiral tubes 8003 and are located below the ventilation tubes 1010.

[0038] It should be noted that the first annular cavity 1001 , the first annular plate 1002 , the second annular cavity 1003 and the second annular plate 1004 are sealed and penetrated by the leakage tube 9004 , and the first annular plate 1002 and the second annular plate 1004 can be sealed and slid up and down along the multiple groups of leakage tubes 9004 .

[0039] In summary, when the two sets of spiral tubes 8003 are blocked, the liquid at the bottom of the tower body 12 forms steam under the action of the reboiler 7 and continues to rise. Due to the continuous rise of the steam, the gas pressure between the condenser 8 and the reboiler 7 increases, and the air inlet at the bottom of the spiral tube 8003 is closed through the solenoid valve 1011. As the pressure continues to increase, the increased pressure pushes the first annular plate 1002 and the second annular plate 1004 to move upward to the first height, as shown in FIG. Figure 8 As shown, in the process of moving to the first height, the increased pressure pushes the second annular plate 1004 to move upward in the second annular cavity 1003 and compresses the spring 1005. The moving second annular plate 1004 drives the first annular plate 1002 to move synchronously in the first annular cavity 1001 through the connecting column 1006. The first annular plate 1002 squeezes the gas in the upper cavity of the first annular cavity 1001 during the movement. The squeezed gas enters the spiral tube 8003 through the vent pipe 1010. Since the electromagnetic valve 1011 closes the bottom air inlet, the gas entering the spiral tube 8003 goes to the outlet pipe 80 02 direction, the gas clears the spiral tube 8003 during the flow. When clearing the spiral tube 8003, the gas pushes the impurities blocked in the spiral tube 8003 and pushes the impurities out through the air outlet pipe 8002. The pushed impurities move around along the arc surface of the inner wall of the annular cylinder 8006 and fall on the protruding conical surface of the top of the condensation cylinder 8001, and then move along the conical surface through the leakage hole 9003 to the collection chamber 9001, and the impurities are filtered by the filter screen 9002. The droplets carried by the impurities during the movement pass through the filter screen 9002 and flow into the bottom of the filter screen 9002 and are discharged through the leakage pipe 9004.

[0040] The second annular plate 1004 drives the first annular plate 1002 to slide upward in the first annular cavity 1001 through the connecting column 1006, and at the same time, negative pressure is generated in the lower cavity. Under the action of the negative pressure, the lower cavity draws air into the interior through the nozzle 1008, the circular tube 1007 and the air flow tube 1009. The nozzle 1008 will not draw impurities into the lower cavity during the suction process.

[0041] When the spiral tube 8003 is unblocked, the steam enters the air inlet 8005, and the solenoid valve 1011 opens the air inlet at the bottom of the spiral tube 8003. Then the steam flows normally from the spiral tube 8003. At this time, the pressure below the condenser 8 gradually decreases. When the pressure below the condenser 8 returns to normal, the compressed spring 1005 drives the second annular plate 1004, the connecting column 1006 and the first annular plate 1002 to return to the initial height from the first height. The first annular plate 1002 moves downward from the first height to the initial height. In the process of returning to the initial position, the first annular plate 1002 squeezes the gas in the lower cavity, causing the gas to flow into the circular tube 1007 through the airflow tube 1009, and the gas sprayed from the nozzle 1008 cleans the impurities on the protruding conical surface at the top of the condensation cylinder 8001, thereby preventing the impurities from adhering to the protruding conical surface at the top of the condensation cylinder 8001 and affecting the flow of droplets, thereby improving the flow effect of the droplets; at the same time, the gas sprayed from the nozzle 1008 can also accelerate the rapid flow of droplets at the top of the condensation cylinder 8001.

[0042] While the first annular plate 1002 moves from the first height to the initial height, the first annular plate 1002 moves downward to generate negative pressure in the upper cavity, opening the one-way valve so that air is sucked into the upper cavity under the action of the negative pressure.

[0043] Through the cooperation of the first annular cavity 1001, the first annular plate 1002, the connecting column 1006 and the second annular plate 1004, when the air pressure below the condenser 8 increases, the solenoid valve 1011 closes the air inlet at the bottom of the spiral tube 8003. At this time, the increased pressure pushes the second annular plate 1004 to move upward, so that the second annular plate 1004 drives the first annular plate 1002 to slide in the first annular cavity 1001 through the connecting column 1006, and squeezes the gas in the upper cavity. The squeezed gas enters the spiral tube 8003 through the ventilation pipe 1010 for dredging, and discharges the impurities inside it through the outlet pipe 8002 to the top of the condenser tube 8001, thereby improving the purity of product separation and realizing self-cleaning without stopping the machine, thereby improving work efficiency.

[0044] Through the cooperation of the first annular cavity 1001, the first annular plate 1002, the connecting column 1006, the second annular plate 1004 and the spring 1005, when the spiral tube 8003 is unblocked, the pressure between the condenser 8 and the reboiler 7 is restored, and the compressed spring 1005 drives the second annular plate 1004 to move downward. In the process of the second annular plate 1004 moving downward, it drives the first annular plate 1002 to squeeze the gas in the lower cavity through the connecting column 1006. The squeezed gas flows into the circular tube 1007 through the airflow tube 1009 and is sprayed out through the nozzle 1008, so as to clean the impurities cleaned out from the spiral tube 8003 at the top of the condenser tube 8001, thereby avoiding the impurities adhering to the protruding conical surface at the top of the condenser tube 8001 and affecting the flow of droplets, thereby improving the flow effect of droplets.

[0045] Embodiment 3, the present invention also provides a process for preparing anhydrous formic acid, comprising the following steps: Step 1: adding raw materials, the raw materials react in the reactor 4, and generate a methyl formate mixed solution; Step 2: Purification: purifying the generated methyl formate mixed liquid in a gas-liquid separator 3 to obtain methyl formate; Step 3: hydrolysis, hydrolyzing methyl formate in a hydrolysis reactor 2 to obtain a mixed solution containing formic acid; Step 4: separation, separating the water and formic acid in the mixed solution in a distillation tower 1, and obtaining relatively pure anhydrous formic acid; Step 5, dehydration, anhydrous formic acid enters the dehydration equipment 5 in the form of steam to remove water; Step six: collecting, collecting the anhydrous formic acid from which water has been removed into a product collecting tank 6 to obtain the final product.

[0046] The embodiments of the present application are described above in conjunction with the accompanying drawings. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A device for preparing anhydrous formic acid, comprising a distillation tower (1); A hydrolysis reactor (2), the top of which is connected to the bottom of the distillation tower (1) via a pipeline; A gas-liquid separator (3), the bottom of which is connected to the bottom of the hydrolysis reactor (2) via a pipeline; A reaction kettle (4), the top of which is connected to the top of the gas-liquid separator (3) through a pipeline; A dehydration device (5), the top of which is connected to the top of the distillation tower (1) via a pipeline; A product collection tank (6), the top of which is connected to the bottom of the dehydration device (5) through a pipeline; It is characterized in that The distillation tower (1) comprises: a tower body (12); A reboiler (7) is fixedly arranged at the bottom of the tower body (12), and the reboiler (7) is capable of heating the liquid at the bottom of the tower body (12), so that the heated liquid evaporates and turns into steam that rises; A condenser (8) is fixedly arranged at the top of the distillation tower (1), and the condenser (8) is capable of cooling the rising steam; A liquid collecting portion (9) is disposed in the top of the condenser (8) and is capable of collecting liquid droplets. The collected liquid droplets are refluxed through the liquid collecting portion (9) into the reboiler (7) for heating; A cleaning portion (10) is disposed in the condenser (8), and the cleaning portion (10) is capable of moving up and down in the condenser (8) and clearing components in the condenser (8); The wire mesh demister (11) is fixedly arranged at the top of the tower body (12) and fixedly arranged above the condenser (8), and is capable of separating liquid droplets in the steam, and the separated liquid droplets are collected by the liquid collecting part (9).

2. The anhydrous formic acid preparation device according to claim 1, characterized in that: The reboiler (7) comprises: An annular cylinder (7001) fixedly disposed at the bottom of the tower body (12); The heat exchange tubes (7002) are fixedly arranged inside the annular cylinder (7001) and are capable of heating the liquid; A high-temperature liquid inlet (7003) is connected to one end of the heat exchange tube (7002), and the other end of the high-temperature liquid inlet (7003) seals and penetrates the tower body (12) and the annular cylinder (7001) and extends out of the outer wall of the tower body (12); a high-temperature liquid outlet (7004) connected to one end of the heat exchange tube (7002), and the other end of the high-temperature liquid outlet (7004) seals and penetrates the tower body (12) and the annular cylinder (7001) and extends out of the outer wall of the tower body (12), and the high-temperature liquid outlet (7004) and the high-temperature liquid inlet (7003) are in a relative position; A plurality of first air outlet holes (7005) are provided and opened at the top of the annular cylinder (7001); A heat-insulating cavity (7006) is provided inside the annular cylinder (7001); A plurality of heating tubes (7007) are provided and are located between the tubes of the heat exchange tube array (7002); The channels (7008) are provided in multiple groups and are fixedly arranged on the top of the heating tube (7007).

3. The anhydrous formic acid preparation device according to claim 1, characterized in that: The condenser (8) comprises: A condensation cylinder (8001), which is arranged at the top of the tower body (12), and has cooling water inside, so as to cool the steam; An air outlet pipe (8002) is fixedly arranged on the top of the condensation cylinder (8001); The spiral tubes (8003) are arranged in multiple groups, and the tops of the multiple groups of spiral tubes (8003) are connected to the air outlet pipe (8002); and the bottoms of the multiple groups of spiral tubes (8003) are fixedly arranged with the bottom of the condensation cylinder (8001); A concave conical groove (8004) fixedly disposed at the bottom of the condensation cylinder (8001); The air inlet holes (8005) are arranged in a plurality of groups and are opened between the concave conical groove (8004) and the condensation cylinder (8001), and the tops of the plurality of groups of the air inlet holes (8005) are connected to the bottoms of the corresponding spiral tubes (8003).

4. The anhydrous formic acid preparation device according to claim 3, characterized in that: The condenser (8) further comprises: An annular cylinder (8006) is fixedly disposed on the top of the condensation cylinder (8001); Second air outlet holes (8007) are provided in multiple groups and are opened on the top of the annular cylinder (8006), and the multiple groups of second air outlet holes (8007) are staggered with the air outlet pipe (8002); The inner wall of the sleeve (8008) is fixedly arranged on the outer wall of the condensation cylinder (8001), and the outer wall of the sleeve (8008) is fixedly arranged on the top of the tower body (12).

5. The anhydrous formic acid preparation device according to claim 4, characterized in that: The condenser (8) further comprises: A liquid inlet pipe (8009), which is connected to one end of the condensation cylinder (8001), and the other end of which seals and penetrates the sleeve (8008) and the tower body (12) and extends out of the outer wall of the tower body (12); A liquid outlet pipe (8010) is connected to one end of the condensation cylinder (8001), and the other end sealably penetrates the sleeve (8008) and the tower body (12) and extends out of the outer wall of the tower body (12). The liquid outlet pipe (8010) and the liquid inlet pipe (8009) are in a relative position.

6. The anhydrous formic acid preparation device according to claim 5, characterized in that: The liquid collecting part (9) further comprises: A collecting chamber (9001) is provided between the outer wall of the condensing cylinder (8001) and the inner wall of the sleeve (8008) and is located at the top of both; A filter screen (9002) is disposed in the collection chamber (9001); Leakage holes (9003) are arranged in a plurality of groups and are opened between the bottom of the annular cylinder (8006) and the top connection of the condensation cylinder (8001); The liquid leakage tubes (9004) are provided in multiple groups, and the tops of the multiple groups of liquid leakage tubes (9004) are connected to the top of the collection chamber (9001).

7. The anhydrous formic acid preparation device according to claim 4, characterized in that: The cleaning unit (10) comprises: A first annular cavity (1001) is provided between the outer wall of the condensing cylinder (8001) and the inner wall of the sleeve (8008) and is located in the middle of the two; A first annular plate (1002) which is sealingly slidably disposed in the first annular cavity (1001); A second annular cavity (1003) is provided between the outer wall of the condensing cylinder (8001) and the inner wall of the sleeve (8008) and is located at the bottom of both; A second annular plate (1004) is sealingly and slidably disposed in the second annular cavity (1003); Springs (1005) are arranged in multiple groups and fixedly disposed between the top of the second annular cavity (1003) and the top of the second annular plate (1004); The connecting columns (1006) are arranged in multiple groups and fixedly disposed on the bottom of the first annular plate (1002).

8. The anhydrous formic acid preparation device according to claim 3, characterized in that: The cleaning unit (10) further comprises: The bottom of the round tube (1007) is embedded in the top of the condensation cylinder (8001), and the top of the round tube (1007) is higher than the top of the condensation cylinder (8001); Nozzles (1008) are arranged in multiple groups and fixedly arranged on the top of the circular tube (1007), and the jetting direction of the multiple groups of nozzles (1008) is toward the leakage hole (9003); The airflow tubes (1009) are arranged in multiple groups, and the tops of the multiple groups of airflow tubes (1009) are connected to the bottom of the circular tube (1007), and the bottoms thereof are connected to the bottom of the first annular cavity (1001).

9. The anhydrous formic acid preparation device according to claim 7, characterized in that: The cleaning unit (10) further comprises: Ventilation tubes (1010) are arranged in multiple groups and correspond to the spiral tubes (8003), the tops of the multiple groups of ventilating tubes (1010) are connected to the tops of the first annular cavity (1001), and the bottoms of the multiple groups of ventilating tubes (1010) are connected to the bottoms of the corresponding spiral tubes (8003); The solenoid valves (1011) are arranged in multiple groups and correspond to the spiral tubes (8003), and the solenoid valves (1011) are fixedly arranged at the bottom of the spiral tubes (8003) and are located below the ventilation tube (1010).

10. A process for preparing anhydrous formic acid, applied to the anhydrous formic acid preparation device according to claim 1, characterized in that: The following steps are involved: Step 1: adding raw materials, the raw materials react in the reactor (4) to generate a methyl formate mixed liquid; Step 2: purification, purifying the generated methyl formate mixed liquid in a gas-liquid separator (3) to obtain methyl formate; Step 3: hydrolysis, hydrolyzing methyl formate in a hydrolysis reactor (2) to obtain a mixed solution containing formic acid; Step 4: separation, separating the water and formic acid in the mixed solution in a distillation tower (1) to obtain relatively pure anhydrous formic acid; Step 5: dehydration: anhydrous formic acid enters the dehydration equipment (5) in the form of steam to remove water; Step 6: Collecting: collecting the anhydrous formic acid from which water has been removed into a product collection tank (6) to obtain the final product.

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