CN216419325U - Chloro-o-xylene continuous oxidation device, system and bubbling reactor - Google Patents
Chloro-o-xylene continuous oxidation device, system and bubbling reactor Download PDFInfo
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- CN216419325U CN216419325U CN202122635051.XU CN202122635051U CN216419325U CN 216419325 U CN216419325 U CN 216419325U CN 202122635051 U CN202122635051 U CN 202122635051U CN 216419325 U CN216419325 U CN 216419325U
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Abstract
A chloro-o-xylene continuous oxidation reaction device with a dehydration filler section bubbling reactor comprises a batching kettle (R2), a feeding pump (P1), a bubbling reactor (R1) with a dehydration filler section (T1), an oxidation condenser (E1), a flash tank (V1), a flash material condenser (E2), an acetic acid storage tank (V2), a tail gas alkali absorption tower (T2) and a circulating pump (P2). The bubble reactor with a dehydration filling section and other matched equipment are used as a chloro-o-xylene liquid-phase air continuous reaction device, so that water generated in the reaction process can be continuously discharged out of a reaction system, the inhibition effect of water on the reaction is greatly reduced, and the product yield is improved; meanwhile, the device adopts a production mode of continuous feeding and continuous discharging to greatly improve the utilization efficiency of the reaction device and avoid the fatigue damage of the equipment caused by frequent pressure rise, pressure reduction, temperature rise and temperature drop of the reaction equipment brought by an intermittent process.
Description
Technical Field
The utility model relates to a chemical production technology field, concretely relates to chloro-o-xylene continuous oxidation device, system and tympanic bulla reactor.
Background
The monochlorophthalic anhydride is a key raw material for synthesizing some polyimide monomers with higher values, such as biphenyl dianhydride (BPDA), triphenyl diether dianhydride, bisphenol A dianhydride (BPADA), triphenyl diether dianhydride (HQDPA) and diphenyl ether dianhydride (OPDA), and is also an ideal raw material for synthesizing low-cost thermoplastic polyimide Polyetherimide (PEI) and Polythioetherimide (PTEI).
At present, the preparation method of monochlorophthalic anhydride comprises the following steps: the method comprises a phthalic anhydride melting or gas phase chlorination method, a mononitrophthalic anhydride chlorination method, a monochloro-o-xylene gas phase air catalytic oxidation method, a monochloro-o-xylene liquid phase air catalytic oxidation method and the like, wherein in the oxidation step, because the yield of a continuous oxidation method is low, reaction byproducts are more and difficult to separate, batch oxidation methods are adopted in many industrial devices at present, but the utilization efficiency of batch oxidation methods is low, the effective utilization rate is less than half, the equipment is continuously in the circulation of temperature rise and temperature reduction, the influence on the service life of the equipment is large, in addition, the fluctuation of the batch reaction temperature is large, the materials and solvents are burnt too much when the reaction peak is generated, the reaction is insufficient due to the excessively low temperature in the later stage of the reaction, the material loss is large, and the yield is low.
In summary, the existing synthesis method of chlorophthalic anhydride requires urgent improvement of the equipment, has low utilization rate of the equipment, causes fatigue damage of the equipment, reduces the service life, needs continuous production equipment to improve the production efficiency, and has the defects of low product yield, high purification cost and the like in the processes depending on the existing equipment.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem, the utility model provides a chloro-o-xylene continuous oxidation device, which particularly adopts a bubble reactor with a dehydration filling section and other matched equipment as a chloro-o-xylene liquid phase air continuous reaction device, and the device is combined with the oxidation process of the utility model, so that water generated in the reaction process can be continuously discharged out of a reaction system, the inhibition effect of the water on the reaction is greatly reduced, and the product yield is improved; meanwhile, the device adopts a production mode of continuous feeding and continuous discharging to greatly improve the utilization efficiency of the reaction device, and avoid the fatigue damage of equipment caused by frequent pressure rise, pressure reduction, temperature rise and temperature drop of reaction equipment brought by an intermittent process.
Adopt the utility model discloses chloro o-xylene continuous oxidation unit has solved multistage stirred tank and has established ties the problem that the equipment investment that realizes chloro o-xylene liquid phase air continuous oxidation and bring is many, fault rate is high, the security is poor, has also solved the problem that among the prior art microchannel reactor realizes that equipment investment is big, production efficiency is low that chloro o-xylene oxidation liquid phase air continuous oxidation brings simultaneously. The utility model relates to a safe, reliable and high-efficient production method for monochlorophthalic anhydride.
Particularly, the utility model provides a reaction unit of chloro-o-xylene continuous oxidation and oxidation process thereof, make it can prepare chloro-phthalic acid safely, stably, high-efficiently.
The utility model provides a bubble reactor, which is divided into three sections from top to bottom, wherein the first section is a dehydration filling section, the second section is a free space section, and the third section is a reaction section; the length-diameter ratio of the bubbling reactor is 3-22, the dehydration filler section accounts for 20-60% of the total height of the bubbling reactor (R1), the free space section accounts for 20-50% of the total height of the bubbling reactor (R1), and the reaction section accounts for 20-80% of the total height of the bubbling reactor (R1). The top of the reactor is provided with a condenser, and the condenser is provided with a condensate liquid extraction port.
A liquid distributor, a filler and a filler support grid are arranged in the dehydration filler section; the lower part of the reaction section is provided with a gas distributor and a bubbling column plate, the gas distributor is arranged below the bubbling column plate, and the gas distributor is connected with a gas inlet of the bubbling reactor; a raw material feeding pipe is arranged above the reaction section; a discharge pipe is arranged at the bottom of the tower; the top of the tower is provided with a tail gas pipe and a return pipe.
The utility model also provides a continuous oxidation reaction unit of chloro-o-xylene, including batching cauldron (R2), material loading pump (P1), tympanic bulla reactor (R1) that has dehydration filler section (T1), oxidation condenser (E1), flash tank (V1), flash distillation material condenser (E2), acetic acid storage tank (V2), tail gas alkali absorption tower (T2), circulating pump (P2).
The bubble reactor (R1) is divided into three sections from top to bottom, wherein the first section is a dehydration filler section, the second section is a free space section, and the third section is a reaction section. The dehydration filling section accounts for 20-60% of the total height of the bubbling reactor (R1), the free space section accounts for 20-50% of the total height of the bubbling reactor (R1), and the reaction section accounts for 20-80% of the total height of the bubbling reactor (R1).
A liquid distributor, a filler and a filler support grid are arranged in the dehydration filler section; a gas distributor and a bubbling column plate are horizontally arranged at the lower part of the reaction section, the gas distributor is arranged below the bubbling column plate, and the gas distributor is connected with a gas inlet of a bubbling reactor (R1); a raw material feeding pipe is arranged above the reaction section and is connected with a feeding pump; the tower bottom is provided with a discharge pipe which is connected with a flash tank; the tower top is provided with a tail gas pipe and a return pipe, the tail gas pipe is connected with a gas phase inlet of the condenser, and the return pipe is connected with a liquid outlet of the condenser; the air inlet of the bubbling reactor (R1) is connected with an air compressor (M1).
The bubbling reactor is made of corrosion-resistant materials: the shell of the tower is one of a titanium/steel composite plate, a titanium palladium/steel composite plate, a zirconium/titanium/steel composite plate and a tantalum/steel composite plate; the material of the gas distributors of the dehydration filling section and the reaction section is one of titanium, titanium palladium alloy and zirconium; the filler of the dehydration filler section is titanium or zirconium wire mesh regular filler or ceramic orifice plate ripple regular filler.
The oxidation condenser (E1) is a fin condenser, a tube array condenser, a floating head condenser or a U-shaped tube condenser with a liquid storage tank at the lower part, wherein the volume of the liquid storage section is more than 0.2m3The material is titaniumOne of titanium palladium alloy and zirconium.
A flash tank (V1) is internally provided with a coil pipe for heating and an external jacket for heating; the shell of the flash tank is made of one of titanium/steel composite plates, titanium palladium/steel composite plates, zirconium/titanium/steel composite plates, tantalum/steel composite plates and the like, and the inner coil is made of one of titanium, zirconium and tantalum.
The utility model provides a continuous oxidation reaction system of chloro-o-xylene specifically includes:
the device comprises a batching unit, a continuous oxidation unit, a tail gas condensation unit, a flash evaporation unit, an acetic acid collection unit, a tail gas absorption unit and a crude anhydride rectification unit.
Wherein the batching unit comprises a batching kettle, a feeding pump and an air compressor;
the continuous oxidation unit comprises a bubble reactor (R1) with a section of dehydrated packing (T1);
the tail gas condensation unit comprises an oxidation condenser (E1) and a flash material condenser (E2);
the flash unit comprises a flash tank (V1);
the acetic acid collection unit comprises an acetic acid storage tank (V2) and a flash condenser (E2);
the tail gas absorption unit comprises a tail gas alkali absorption tower (T2) and a circulating pump (P2);
the crude anhydride rectifying unit comprises a rectifying tower; the number of the plates of the rectifying tower is 50-200.
And further, the acetic anhydride rectifying unit also comprises an acetic anhydride buffer tank, and the crude anhydride after the flash evaporation enters the crude anhydride buffer tank and then is sent to the crude anhydride rectifying unit for refining.
The batching kettle is sequentially connected with a feeding pump and a bubbling reactor (R1), raw materials prepared in the batching kettle enter the bubbling reactor (R1) through a raw material feeding pipe and the feeding pump, and gas enters the bubbling reactor (R1) through an air compressor to realize liquid-phase continuous reaction;
a tail gas pipe is arranged at the top of the bubbling reactor (R1) and is connected with a gas phase inlet of a tail gas condenser (E1), the top of the tail gas condenser is connected with a tail gas alkali absorption tower, a liquid phase outlet of the tail gas condenser (E1) is connected with the bubbling reactor (R1) and an acetic acid collecting unit, one part of the tail gas condenser reflows to the bubbling reactor (R1), and the other part of the tail gas condenser performs acetic acid recovery;
the bottom product of the bubbling reactor (R1) is connected with a flash tank (V1) through a pipeline;
the top outlet of the flash tank (V1) is connected with the inlet of a flash condenser (E2), and the bottom outlet of the flash condenser is respectively connected with the inlet of an acetic acid storage tank (V2) and a tail gas alkali absorption tower (T2); the non-condensable gas is absorbed by a tail gas alkali absorption tower (T2) for tail gas treatment;
the bottom of the tail gas alkali absorption tower (T2) is connected with a circulating pump (P2).
The flash drum (V1) bottom flash product enters a crude anhydride rectification unit.
The utility model discloses at least one embodiment provides a continuous oxidation reaction process of chloro o-xylene and device, including batching cauldron (R2), material loading pump (P1), air compressor machine (M), have bubbling reactor (R1), oxidation condenser (E1), flash tank (V1), flash distillation material condenser (E2), acetic acid storage tank (V2), tail gas alkali absorption tower (T2), circulating pump (P2) of dehydration filler section (T1).
The bubble reactor (R1) is divided into three sections from top to bottom, wherein the first section is a dehydration filler section, the second section is a free space section, and the third section is a reaction section. The dehydration filling section accounts for 20-50% of the total height of the bubbling reactor (R1), the free space section accounts for 20-50% of the total height of the bubbling reactor (R1), and the reaction section accounts for 20-80% of the total height of the bubbling reactor (R1).
The method specifically comprises the following units:
1. a batching unit:
according to the mass of the chloro-o-xylene: the quality of acetic acid is as follows: quality of acetate catalyst: mass of bromide accelerator 100: 300-500: 0.5-3: 0.5-4; preferred quality of chloro-o-xylene: the quality of acetic acid is as follows: the mass of the catalyst is as follows: the mass of the accelerator is 100: 400-500: preparing materials according to the ratio of 0.5-2: 0.5-2, stirring, heating to 80-120 ℃, and keeping for 1-2 hours to finish the batching.
2. Continuous oxidation unit
Continuously adding the prepared materials (raw materials, catalyst and accelerant) into a continuous bubbling reactor (R1), introducing compressed oxygen-enriched gas or air (the oxygen content is more than 20% v/v) into the lower part of the reactor, and controlling the water content of a reaction system to be 0-8% under the pressure of 1.3-3 Mpa and at the temperature of 160-260 ℃; preferably, the liquid-phase continuous oxidation reaction is carried out under the pressure of 1.8-2.5 Mpa and the reaction temperature of 180-250 ℃ and the water content of the reaction system is 3-6%.
Wherein the flow rate of the material (kg/min) is the flow rate of air (m) under standard state3Min) ratio 1: 1.1 to 1.8, preferably 1:1.2 to 1.7; the oxygen content of the tail gas is controlled within 7 percent (volume ratio).
The catalyst is acetate, and is selected from one or more of cobalt acetate, manganese acetate, zirconium acetate, nickel acetate, hafnium acetate, sodium acetate and the like.
The promoter is bromide selected from one or more of tetrabromoethane, hydrogen bromide and sodium bromide.
After the reaction is finished, the vaporized acetic acid, the water vapor and the reaction tail gas at the upper part of the bubble column are rectified in a dehydration filling section (T1) to concentrate the water vapor and then come out from the top of the column.
The utility model discloses set up the backwash valve and adopt the valve in condenser (E1) below, adjust the reaction system moisture content that the reflux ratio made through DCS and be a invariable value between 0 ~ 8% and make it reach dynamic balance, realize continuous oxidation.
3. Tail gas condensation unit
The water vapor at the top of the bubbling reactor (R1) is subjected to heat exchange condensation by a reaction tail gas condenser (E1), uncondensed tail gas is treated by a tail gas alkali absorption tower (T2), most of condensate flows back to a dehydration filler section (T1) at the upper part of the bubbling reactor, and part of condensate is extracted and sent to acetic acid recovery.
4. Flash evaporation unit
The chlorophthalic acid formed after the reaction is dissolved in acetic acid, and continuously enters a flash tank (V1) from a bubbling reactor (R1) and then enters a crude anhydride rectification unit.
5. Acetic acid collecting unit
The flashed acetic acid and other steam enter a dilute acetic acid storage tank (V2) after being condensed by a condenser (E2) to realize acetic acid recovery.
6. Tail gas absorption unit
The non-condensable gas passing through the condensers (E1, E2) is absorbed by a tail gas alkali absorption tower (T2) for tail gas treatment.
7. Crude anhydride rectification unit
The crude anhydride product is rectified to obtain a crude anhydride product, and the pressure in the rectifying tower is 0-4000Pa and the temperature is 170-.
Sampling the distilled crude anhydride product, testing the purity and yield, and calculating the consumption of acetic acid according to the yield of the rectified acetic acid.
The beneficial effects of the utility model include several aspects below:
1. the utility model discloses a what chloro ortho-xylene oxidation unit and oxidation technology adopted is continuous oxidation technology, and the mode of production is continuous feeding, continuous ejection of compact promptly, and this kind of mode of production has increased substantially reaction unit's utilization efficiency, and the reaction unit of having avoided intermittent type technology to bring moreover is because of frequently stepping up the step-down, the fatigue damage that the cooling that heaies up caused.
2. The utility model discloses a continuous oxidation unit of chloro o-xylene and oxidation technology adopt the tympanic bulla reactor that has dehydration filler section and other supporting equipment as chloro o-xylene liquid phase air continuous reaction unit, the device combines the utility model discloses a continuous oxidation technology can be with the water of reaction in-process production constantly discharge reaction system, keeps reaction system water content to be less than 8%, reduces the inhibitory action of water to the reaction by a wide margin, has guaranteed reaction rate and conversion, improves the product yield.
3. The utility model discloses a continuous oxidation process makes oxidation system can be through the flow of control material, makes the reaction be in a invariable and the temperature that is fit for the oxidation reaction to go on always, has improved greatly that intermittent reaction temperature fluctuation makes material and solvent burning too much when leading to the reaction peak greatly, the reaction later stage again because of the temperature crosses lowly causes the insufficient condition of reaction to take place, reducible loss, improvement yield.
4. The utility model discloses a continuous oxidation unit of chloro ortho-xylene and oxidation technology adopt the tympanic bulla reactor, do not have any rotating member in the reactor, and equipment investment is few, the fault rate is low, the reliability is high, especially adapted large-scale industrial production. The method solves the problems of high equipment investment, high failure rate and poor safety caused by the fact that a plurality of stages of stirred tanks are connected in series to realize the continuous oxidation of the chloro-o-xylene liquid phase air, and also solves the problems of high equipment investment and low production efficiency caused by the fact that a microchannel reactor realizes the continuous oxidation of the chloro-o-xylene oxidation liquid phase air.
5. The utility model discloses realized full automatic control to reaction system, reduced on-the-spot operation workman's quantity, in addition the utility model discloses a continuous oxidation process than the intermittent type technology of coproduction ability has reduced the volume of holding the material of reactor, makes the security of system increase substantially, is a production method of high-efficient production monochlorophthalic anhydride.
6. The utility model discloses a set up the dehydration section and carry out the gathering to vapor to set up the condenser at the top of the tower and carry out the comdenstion water and discharge, and then control entire system's water content within 8%, effectively restrain system water content, guaranteed reaction rate and yield.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the disclosure and together with the description serve to explain the principles of the disclosure.
FIG. 1 is a flow chart of the continuous oxidation reaction process of example 1 of the present invention
Wherein, the system comprises an R1-bubbling reactor, a T1-dehydrating filler section, an R2-batching kettle, an E1-tail gas condenser, an E2-flash condenser, a T2-tail gas alkali absorption tower, a V1-flash tank, a V2-acetic acid storage tank, an M-air compressor, a P1-charging pump and a P2-lye pump;
1-mixed material, 2-compressed air, 3-reacted material, 4-reacted tail gas, 5-condensed tail gas, 6, 7-cooling water, 8-reflux condensate, 9-extracted condensate, 10-acetic acid steam, anhydride steam, 11-acetic acid, 12-flash-evaporated tail gas, 13-crude anhydride, 14-acetic acid and 15-alkaline water.
Detailed Description
The present application will be described in further detail with reference to the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are for purposes of illustration only and are not to be construed as limitations of the present application. It should be noted that, for convenience of description, only the portions related to the present application are shown in the drawings.
Example 1 (Low temperature Oxidation)
1) Ingredients
The method comprises the following steps of (1) mixing chloro-o-xylene, acetic acid, an acetate catalyst and a bromide cocatalyst according to the mass of the chloro-o-xylene: the quality of acetic acid is as follows: quality of acetate catalyst: mass of bromide accelerator 100: 450: 1.5: 2, wherein the ratio of acetate catalyst is as follows: cobalt acetate: manganese acetate: zirconium acetate 1:1.2: 0.005; bromide is tetrabromoethane: sodium bromide ═ 3: 1, adding 7000kg of prepared materials into a batching kettle R2, heating, stirring to 80 ℃, and maintaining for 1 hour to finish the material preparation.
2) Continuous oxidation
1.2m by feeding pump P1 under the kettle3The flow rate of the solution/h is added into a continuous bubbling reactor R1, and the addition is stopped when the material liquid level in the bubbling reactor reaches the height of 1.5 m; then compressed air was introduced to 1.3 MPa. And (3) starting heat conduction oil for heating, starting cooling water of a tail gas condenser E1 and a flash condenser E2, and starting a tail gas alkali absorption tower T2 circulating pump. When the temperature in the bubble reactor R1 reached 160 ℃, observation of the magnetic oxygen meter in the reactor tail gas indicated that the oxidation reaction started to initiate when the oxygen content in the vented tail gas began to change, and the feed pump P1 was turned on again at 1.2m3Adding materials into a bubbling reactor R1 at a flow rate of/h, adjusting the introduction amount of compressed air to control the oxygen content in the reaction emptying tail gas to be about 7% (volume ratio), when the liquid level of a reflux tank of a condenser reaches 0.3m, opening a reflux valve and a production valve below the condenser E1, and adjusting the reflux ratio through DCS to enable the water content of a reaction system to be a constant value of 3% and enable the water content to reach dynamic balance. The pressure in the reactor R1 was maintained at 1.9MPa and the temperature at 200 ℃.
3) Condensation of tail gas
R1 tower top vapor is condensed through reaction tail gas condenser E1 heat exchange, uncondensed tail gas is treated by a tail gas absorption unit, most of condensate liquid flows back to a dehydration filling section at the upper part of the bubbling reactor, and the extracted acetic acid water solution is sent to an acetic acid collection unit.
4) Flash evaporation
The chlorophthalic acid material generated by the oxidation reaction enters a continuous flash tank V1 from a bubbling reactor R1 for flash evaporation, enters a crude anhydride buffer tank after the flash evaporation is finished, and then is sent to a crude anhydride rectifying unit.
5) Acetic acid collecting unit
The flashed acetic acid and other steam enter a dilute acetic acid storage tank V2 after being condensed by a condenser E2, so that the acetic acid is recovered.
6) Tail gas absorption unit
The non-condensable gas passing through the condensers E1 and E2 is absorbed by a tail gas alkali absorption tower T2, and is subjected to alkali washing to carry out tail gas treatment.
7) Crude anhydride rectification unit
The crude anhydride from the flash drum V1 can be sent to a rectifying tower for refining to obtain the chlorophthalic anhydride product.
The crude anhydride from flash tank V1 was sampled for purity and yield, and the acetic acid consumption was calculated from the acetic acid yield after rectification.
Example 2 (Medium temperature Oxidation)
1) The ingredients were the same as in example 1
2) Continuous oxidation
1.2m by feeding pump P1 under the kettle3The flow rate of the solution/h is added into a continuous bubbling reactor R1, and the addition is stopped when the material liquid level in the bubbling reactor reaches the height of 1.5 m; then compressed air was introduced to 1.3 MPa. And (3) starting heat conduction oil for heating, starting cooling water of an off-gas condenser E1 and a flash condenser E2, and starting a circulating pump of an off-gas absorption tower T2. When the temperature in the bubble reactor R1 reached 160 ℃, observation of the magnetic oxygen meter in the reactor tail gas indicated that the oxidation reaction started to initiate when the oxygen content in the vented tail gas began to change, and the feed pump P1 was turned on again at 1.2m3The flow of the/h is that materials are added into a bubbling reactor R1, the introduction amount of compressed air is adjusted, the oxygen content in the reaction emptying tail gas is controlled to be about 7 percent (volume ratio), when the liquid level of a reflux tank of a condenser reaches 0.3m, a reflux valve and a production valve below the condenser E1 are opened, and the mixture passes throughDCS adjusts the reflux ratio to make the water content of the reaction system be a constant value of 4% and make the water content reach dynamic balance. The pressure in the reactor R1 was maintained at 2.1MPa and the temperature at 215 ℃.
3) Condensation of tail gas
R1 tower top vapor is condensed through reaction tail gas condenser E1 heat exchange, uncondensed tail gas is treated by a tail gas absorption unit, most of condensate liquid flows back to a dehydration filling section at the upper part of the bubbling reactor, and the extracted acetic acid water solution is sent to an acetic acid collection unit.
4) Flash evaporation unit
The chlorophthalic acid material generated by the oxidation reaction enters a continuous flash tank V1 from a bubbling reactor R1 for flash evaporation, enters a crude anhydride buffer tank after the flash evaporation is finished, and then is sent to a crude anhydride rectifying unit.
5) Acetic acid collecting unit
The flashed acetic acid and other steam enter a dilute acetic acid storage tank V2 after being condensed by a condenser E2, so that the acetic acid is recovered.
6) Tail gas absorption unit
The non-condensable gas passing through the condensers E1 and E2 is absorbed by a tail gas alkali absorption tower T2, and is subjected to alkali washing to carry out tail gas treatment.
7) Crude anhydride rectification unit
Sampling the distilled crude anhydride, testing the purity and yield, and calculating the consumption of acetic acid according to the yield of the rectified acetic acid.
Example 3 (high temperature Oxidation)
1) Preparing materials: same as example 1
2) Continuous oxidation
1.2m by feeding pump P1 under the kettle3The flow rate of the solution/h is added into a continuous bubbling reactor R1, and the addition is stopped when the material liquid level in the bubbling reactor reaches the height of 1.5 m; then introducing compressed air to 1.3-1.7 MPa. And (3) starting heat conduction oil for heating, starting cooling water of an off-gas condenser E1 and a flash condenser E2, and starting a circulating pump of an off-gas absorption tower T2. When the temperature in the bubble reactor R1 reached 170 ℃, observation of the magnetic oxygen meter in the reactor tail gas indicated that the oxidation reaction started to initiate when the oxygen content in the vented tail gas began to change, and the feed pump P1 was turned on again at 1.2m3Adding materials into a bubbling reactor R1 at a flow rate of/h, adjusting the introduction amount of compressed air to control the oxygen content in the reaction emptying tail gas to be about 7% (volume ratio), when the liquid level of a reflux tank of a condenser reaches 0.3m, opening a reflux valve and a withdrawal valve below the condenser E1, and adjusting the reflux ratio through DCS to enable the water content of a reaction system to be a constant value of 8% and to achieve dynamic balance. The pressure in the reactor R1 was maintained at 2.3MPa and the temperature at 238 ℃.
3) Condensation of tail gas
R1 tower top vapor is condensed through reaction tail gas condenser E1 heat exchange, uncondensed tail gas is treated by a tail gas absorption unit, most of condensate liquid flows back to a dehydration filling section at the upper part of the bubbling reactor, and the extracted acetic acid water solution is sent to an acetic acid collection unit.
4) Flash evaporation unit
The chlorophthalic acid material generated by the oxidation reaction enters a continuous flash tank V1 from a bubbling reactor R1 for flash evaporation, enters a crude anhydride buffer tank after the flash evaporation is finished, and then is sent to a crude anhydride rectifying unit.
5) Acetic acid collecting unit
The flashed acetic acid and other steam enter a dilute acetic acid storage tank V2 after being condensed by a condenser E2, so that the acetic acid is recovered.
6) Tail gas absorption unit
The non-condensable gas passing through the condensers E1 and E2 is absorbed by a tail gas alkali absorption tower T2, and is subjected to alkali washing to carry out tail gas treatment.
7) Crude anhydride detection unit
And (3) distilling and sampling the flash-evaporated crude anhydride, testing the purity and yield, and calculating the consumption of acetic acid according to the yield of the rectified acetic acid.
Comparative example 1 (batch Oxidation)
The preparation of the materials is completed according to the mixture ratio of the raw materials in the example 1.
1.2m by feeding pump P1 under the kettle3Flow rate/h 200kg of the batch vessel were introduced into the bubble reactor R1 in its entirety and compressed air was introduced to 1.3 MPa. And (3) starting heat conduction oil for heating, starting cooling water of an off-gas condenser E1 and a flash condenser E2, and starting a circulating pump of an off-gas absorption tower T2.When the temperature in the bubbling reactor R1 reaches 160 ℃, observing a magnetic oxygen meter of a reactor tail gas to show that the oxygen content in the vented tail gas is initiated from the beginning of oxidation reaction when the oxygen content in the vented tail gas begins to change, adjusting the introduction amount of compressed air to control the oxygen content in the vented tail gas in the reaction to be about 7% (volume ratio), and when the liquid level of a reflux tank of a condenser reaches 0.3m, opening a reflux valve below the condenser E1 to carry out total reflux. The pressure in the reactor was maintained at 2.1MPa and the temperature was maintained at 215 ℃. When the oxygen content of the tail gas reaches more than 18 percent, or the reaction temperature is reduced to below 170 ℃. The reaction was terminated by stopping the introduction of compressed air.
The reacted material from the bubble reactor R1 enters a continuous flash drum V1 and then enters a crude anhydride rectification unit.
The flashed acetic acid and other steam enter a dilute acetic acid storage tank V2 after being condensed by a condenser E2, then enter an acetic acid collection unit, and the non-condensable gas is absorbed by an absorption tower and then enters a tail gas absorption unit.
Sampling the flash-evaporated crude anhydride, testing the purity and yield, and calculating the consumption of acetic acid according to the yield of the rectified acetic acid.
Comparative example 2 (batch Oxidation + non-dehydration)
According to the raw material proportion of the embodiment 1, the material preparation is completed, and a common bubbling reaction kettle is adopted to replace the bubbling reactor with the dehydration filling section.
1.1m by feeding pump P1 under the kettle3Flow/h 200kg of the batch vessel were charged in their entirety to a conventional bubble reactor (without degassing section) and compressed air was then introduced to 1.2 MPa. And (3) starting heat conduction oil for heating, starting cooling water of an off-gas condenser E1 and a flash condenser E2, and starting a circulating pump of an off-gas absorption tower T2. When the temperature in the bubbling reaction kettle reaches 180 ℃, observing a magnetic oxygen meter of a reactor tail end to display that the oxidation reaction starts to initiate when the oxygen content in the vented tail gas starts to change, and adjusting the introduction amount of compressed air to control the oxygen content in the reaction vented tail gas to be about 7 percent (volume ratio). The pressure in the reactor was maintained at 2.0MPa and the temperature at 210 ℃. When the oxygen content of the tail gas reaches above 18 percent or the reaction temperature is reduced to below 170 ℃, the compressed air is stopped to finish the reaction.
The reacted materials enter a continuous flash tank V1 from a bubbling reaction kettle to be flashed, and then the crude anhydride coming out from the bottom enters a crude anhydride rectifying unit.
The flashed acetic acid and other steam enter a dilute acetic acid storage tank V2 after being condensed by a condenser E2, then enter an acetic acid collection unit, and the non-condensable gas is absorbed by an absorption tower and then enters a tail gas absorption unit.
Sampling the crude anhydride obtained after flash evaporation, testing the purity and yield, and calculating the consumption of acetic acid according to the yield of the acetic acid after rectification.
The utility model discloses equipment specification is as shown in Table 1.
TABLE 1
The experimental data of the test of the embodiment of the present invention and the comparative example are shown in table 2.
TABLE 2
Table 1 shows the reactant compositions and the chlorine gas utilization rates in examples 1 to 3 and comparative examples 1 to 2. The samples tested were the oxidation products of the examples, which were distilled under reduced pressure to give crude anhydride analysis, and some of the impurities were removed by vacuum pumping, so the purity was comparable, which also indicates that the chloro-o-xylene liquid phase air oxidation product was much less contaminated than other process impurities.
The material ratios of examples 1-3 and comparative example were the same, and the test and calculation data showed that:
(1) for the liquid-phase air oxidation reaction of chloro-o-xylene, acetic acid is consumed more and more along with the increase of the reaction temperature, and the content of phthalic anhydride in the product is also increased more and more due to dechlorination. Wherein, the yield of the medium-temperature oxidation product is the highest.
(2) By using the continuous oxidation process, the yield of monochlorobenzene anhydride is significantly higher than that of the batch oxidation process, especially the intermediate temperature oxidation process of example 2 has the best result.
It will be understood by those skilled in the art that the foregoing embodiments are provided merely for clarity of disclosure and are not intended to limit the scope of the invention. Other variations or modifications will occur to those skilled in the art based on the foregoing disclosure and are still within the scope of the present application.
Claims (10)
1. The bubble reactor is characterized by being divided into three sections from top to bottom, wherein the first section is a dehydration filler section, the second section is a free space section, and the third section is a reaction section; the length-diameter ratio of the bubbling reactor is 3-22, the height of the dehydration filler section accounts for 20-60% of the total height of the bubbling reactor (R1), the height of the free space section accounts for 20-50% of the total height of the bubbling reactor (R1), and the height of the reaction section accounts for 20-80% of the total height of the bubbling reactor (R1); the top of the reactor is provided with a condenser, and the condenser is provided with a condensate liquid extraction port.
2. The bubble reactor according to claim 1, characterized in that; the lower part of the reaction section is provided with a gas distributor and a bubbling column plate, the gas distributor is arranged below the bubbling column plate, and the gas distributor is connected with the gas inlet of the bubbling reactor.
3. The bubble reactor according to claim 2, wherein a feed of raw material is provided above the reaction section; a discharge pipe is arranged at the bottom of the tower; the top of the tower is provided with a tail gas pipe and a return pipe.
4. A chloro-o-xylene continuous oxidation reaction device is characterized by comprising a batching kettle (R2), a feeding pump (P1), a bubble reactor (R1) with a dehydration filler section (T1), an oxidation condenser (E1), a flash tank (V1), a flash material condenser (E2), an acetic acid storage tank (V2), a tail gas alkali absorption tower (T2) and a circulating pump (P2);
the bubbling reactor is divided into three sections from top to bottom, the first section is a dehydration filling section, the second section is a free space section, the third section is a reaction section, and the dehydration filling section (T1) accounts for 20-60% of the total height of the bubbling reactor (R1).
5. The reactor according to claim 4, characterized in that a gas distributor and a bubbling tray are horizontally installed at the lower part of the reaction section, the gas distributor is arranged below the bubbling tray, and the gas distributor is connected with the gas inlet of the bubbling reactor (R1); a raw material feeding pipe is arranged above the reaction section and is connected with a feeding pump; the tower bottom is provided with a discharge pipe which is connected with a flash tank; the tower top is provided with a tail gas pipe and a return pipe, the tail gas pipe is connected with a gas phase inlet of the condenser, and the return pipe is connected with a liquid outlet of the condenser; the air inlet of the bubbling reactor (R1) is connected with an air compressor (M1).
6. The reaction device of claim 5, wherein the gas distributor is made of one of titanium, titanium palladium alloy and zirconium; the filler of the dehydration filler section is titanium or zirconium wire mesh regular filler or ceramic orifice plate ripple regular filler.
7. The reactor apparatus as claimed in claim 4, characterized in that the oxidation condenser (E1) is a finned condenser, a tube-in-tube condenser, a floating head condenser or a U-tube condenser with a liquid storage tank at the lower part.
8. The reactor apparatus as claimed in claim 4, wherein the flash tank (V1) is internally provided with coil heating and externally provided with jacket heating.
9. A chloro-o-xylene continuous oxidation reaction system is characterized by comprising: the system comprises a material preparation unit, a continuous oxidation unit, a tail gas condensation unit, a flash evaporation unit, an acetic acid collection unit, a tail gas absorption unit and a crude anhydride rectification unit;
wherein the batching unit comprises a batching kettle, a feeding pump and an air compressor;
the continuous oxidation unit comprises a bubble reactor (R1) with a section of dehydrated packing (T1);
the tail gas condensation unit comprises an oxidation condenser (E1) and a flash material condenser (E2);
the flash unit comprises a flash tank (V1);
the acetic acid collection unit comprises an acetic acid storage tank (V2);
the tail gas absorption unit comprises a tail gas alkali absorption tower (T2) and a circulating pump (P2);
the crude anhydride rectifying unit comprises a crude anhydride buffer tank and a rectifying tower.
10. The reaction system according to claim 9,
the batching kettle is sequentially connected with a feeding pump and a bubbling reactor (R1), raw materials prepared in the batching kettle enter the bubbling reactor (R1) through a raw material feeding pipe and the feeding pump, and gas enters the bubbling reactor (R1) through an air compressor to realize liquid-phase continuous reaction;
the top of the bubbling reactor (R1) is provided with a tail gas pipe which is connected with a gas phase inlet of an oxidation condenser (E1), the top of the oxidation condenser is connected with a tail gas alkali absorption tower, a liquid phase outlet of the oxidation condenser (E1) is connected with the bubbling reactor (R1) and an acetic acid collecting unit, one part of the liquid phase outlet flows back to the bubbling reactor (R1), and the other part of the liquid phase outlet is used for recovering acetic acid;
the bottom product of the bubbling reactor (R1) is connected with a flash tank (V1) through a pipeline;
the top outlet of the flash tank (V1) is connected with the inlet of a flash material condenser (E2), and the bottom outlet of the flash material condenser is respectively connected with the inlet of an acetic acid storage tank (V2) and a tail gas alkali absorption tower (T2); the non-condensable gas is absorbed by a tail gas alkali absorption tower (T2) for tail gas treatment;
the bottom of the tail gas alkali absorption tower (T2) is connected with a circulating pump (P2).
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| CN115155467A (en) * | 2022-08-09 | 2022-10-11 | 宁夏瑞泰科技股份有限公司 | System and method for synthesizing hexamethylene diisocyanate by adopting liquid phase phosgenation |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115155467A (en) * | 2022-08-09 | 2022-10-11 | 宁夏瑞泰科技股份有限公司 | System and method for synthesizing hexamethylene diisocyanate by adopting liquid phase phosgenation |
| CN115155467B (en) * | 2022-08-09 | 2023-10-10 | 宁夏瑞泰科技股份有限公司 | System and method for synthesizing hexamethylene diisocyanate by liquid-phase phosgenation |
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