Butanol plant by-product heavies processing system and recovery method

Abstract

A recovery method of a heavy component treatment system of a butanol device by-product, comprising the following steps: the heavy component by-product of the butanol device enters the lower part of a rectifying tower, the heavy component is separated by the rectifying tower, a gas phase is extracted from the lower part of the rectifying tower; the gas phase extracted from the rectifying tower is mixed with fresh hydrogen and circulating gas and then enters a hydrogenation reactor, a stream is selectively hydrogenated into butanol and water, a fixed bed reactor is filled with a hydrogenation catalyst; the reaction product after the reaction is returned to the rectifying tower, butanol and water are separated to the top of the tower in the rectifying tower; the gas phase at the top of the rectifying tower is condensed in one stage, then gas-liquid enters a coalescer, the non-condensable gas phase in the coalescer is further deep-cooled, the liquid phase is returned to the coalescer, the gas phase is compressed by a compressor and then returned to the hydrogenation reactor, a circulating gas is discharged; and the coalescer separates the condensed liquid phase into oil and water, part of the oil phase is returned to the rectifying tower as reflux, part of the oil phase enters a butanol product tower of the device to purify butanol product, and the water phase is discharged to a wastewater system.

Description

TECHNICAL FIELD

[0001] The present application relates to the chemical industry field, and in particular to a butanol device by-product heavy component treatment system and a recovery method. BACKGROUND

[0002] There are two main process technologies for existing industrialized butanol devices, homogeneous hydroformylation reaction technology and aqueous hydroformylation reaction technology. The homogeneous hydroformylation reaction technology is more widely used, which uses rhodium metal complex as a catalyst to make synthesis gas and propylene undergo carbonylation reaction to generate butyraldehyde, and butyraldehyde is further hydrogenated to generate butanol.

[0003] The heavy components by-produced by the butyraldehyde device come from the carbonylation reaction and butyraldehyde hydrogenation reaction process, which contain 5-15% butyraldehyde, 0.5-1% butyric acid, 5-8% butanol, 40-60% butyl butyrate, 10-30% carbon octanol and carbon twelve and above substances. Since the heavy components are mixed and difficult to recover, most devices basically use incineration, which has poor atom economy, high butyraldehyde consumption, and is not conducive to carbon emission reduction.

[0004] Patent CN101973846B discloses a method for producing mixed butanol and crude octanol using butanol device waste liquid as raw material. First, butyraldehyde, butanol, carbon eight components, etc. are separated by a fractionation device, then aldehyde substances are hydrogenated to generate butanol, and then high-purity butanol is obtained through a complex rectification system. The process flow is relatively long, the number of rectification towers used for raw material fractionation and product refining is relatively large, and the investment is huge.

[0005] Patent CN112321386A discloses a method for hydrogenation treatment of butanol device waste liquid. Organic alkali is used as an alkaline additive, and then catalytic hydrogenation conversion is carried out at 230-280℃ to separate alcohol products. The alkaline additive is complex in the separation process, and the heavy components affect the activity of the hydrogenation catalyst

[0006] Patent CN113735688A discloses a recycling method for butanol device waste liquid. Metal ions are treated by ion exchange resin, the material is mixed with hydrogen and then enters the hydrogenation reactor for reaction, the reaction liquid is degassed, the gas phase is returned to the butanol device, and the liquid phase enters the butanol product tower.

[0007] The existing technology mainly has the following problems,

[0008] 1. The heavy components are refined by physical separation method, which has long process flow, large equipment investment, and very low product yield and economic efficiency.

[0009] 2、Although it enters the hydrogenation reactor after treatment by alkaline additives or resin adsorption, etc., due to the high content of heavy components such as octanol and dodecanol in the heavy components, coking is easy to occur on the surface of the catalyst in the hydrogenation reactor, affecting the conversion effect and service life of the catalyst, and the remaining hydrogen gas after hydrogenation is treated by external discharge, which is poor in economy;

[0010] 3、In patent CN113735688A, the heavy components are hydrogenated after adsorption, and the catalyst surface is covered by a large amount of polymers in the heavy components, the catalyst is quickly deactivated, the reaction liquid directly enters the butanol product tower, the butanol product is separated, the water generated by hydrogenation is produced with the butanol product, the butanol quality is poor, and the process is not high in feasibility;

[0011] 4、The traditional hydrogenation reaction feed needs to be heated, and the reaction liquid after hydrogenation needs to be cooled, causing energy waste. SUMMARY

[0012] One of the purposes of the present application is to provide a butanol device by-product heavy component treatment system and recovery method, which is short in process flow, convenient to operate, low in equipment investment, and small in device occupation.

[0013] One of the purposes of the present application is to provide a butanol device by-product heavy component treatment system and recovery method, which is reasonable in process flow, and the heavy components are treated by gas phase hydrogenation after rectification, the catalyst active sites are not covered by heavy components in the reactor feed, and the catalyst has a long service life.

[0014] One of the purposes of the present application is to provide a butanol device by-product heavy component treatment system and recovery method, the product after reaction returns to the rectification tower, butanol and water are separated at the top of the tower, the butanol product is high in quality, and the heavy components are discharged outside the rectification tower kettle to avoid accumulation of the heavy components in the system.

[0015] One of the purposes of the present application is to provide a butanol device by-product heavy component treatment system and recovery method, which directly enters the reactor by using the gas phase taken out by the rectification tower, and the gas phase after hydrogenation returns to the rectification tower, so that all the heat is used in the rectification tower, the tower kettle steam can be saved, and the entire system is low in energy consumption.

[0016] One of the purposes of the present application is to provide a butanol device by-product heavy component treatment system and recovery method, the reaction liquid after hydrogenation is separated into oil and water phases by a coalescer at the top of the tower after rectification, the water phase is prevented from entering the butanol product tower to affect the butanol product quality, the gas phase at the top of the tower is recycled back to the reactor by a compressor, hydrogen gas is saved, and the economy is improved.

[0017] In order to achieve at least one of the purposes of the present application, the present application provides a recovery method of a butanol device by-product heavy component treatment system, which comprises the following steps:

[0018] The heavy components from the butanol unit are introduced into the lower part of the rectification tower, and the heavy components are separated by the rectification tower. A gas phase is extracted from the lower part of the rectification tower;

[0019] The gas phase extracted from the rectification tower is mixed with fresh hydrogen and recycled gas, and then introduced into the hydrogenation reactor to selectively hydrogenate the stream into butanol and water. The fixed bed reactor is filled with a hydrogenation catalyst.

[0020] The reaction product after the reaction is returned to the rectification tower, and butanol and water are separated in the rectification tower and discharged to the top of the tower.

[0021] The gas phase at the top of the rectification tower is condensed by a primary condenser, and then the gas-liquid phase enters the coalescer. The non-condensable gas phase in the coalescer is further cooled by deep cooling, and the liquid phase is returned to the coalescer. The gas phase is compressed by a compressor and returned to the hydrogenation reactor, and a stream of recycled gas is discharged.

[0022] The coalescer separates the condensed liquid phase into oil and water phases. Part of the oil phase is returned to the rectification tower as reflux, and the other part is introduced into the butanol product tower of the unit to purify the butanol product. The water phase is discharged to the wastewater system.

[0023] In some embodiments, the rectification tower is operated at positive pressure, with a pressure of 0.1-2.0 MPaG and a number of theoretical plates of 35-80.

[0024] In some embodiments, the stream of heavy components from the butanol unit is introduced into the rectification tower at a position from 5 to 10 theoretical plates from the bottom. The gas phase is extracted from the 15th to 18th theoretical plate of the rectification tower and introduced into the hydrogenation reactor.

[0025] In some embodiments, the fresh hydrogen and recycled gas are mixed with the gas phase extracted from the rectification tower and introduced into the hydrogenation reactor. The molar ratio of hydrogen to the gas phase extracted from the side is 6-15. The hydrogenation reactor uses a fixed bed, the reaction temperature of the hydrogenation reactor is 160-250°C, the reaction pressure is 0.5-1 MPaG, and the space velocity of the hydrogenation reaction is 0.5-3 h-1.

[0026] In some embodiments, the gas phase at the outlet of the hydrogenation reactor is introduced into the 20th to 30th theoretical plate of the rectification tower, and the butanol and water generated by the hydrogenation reaction are vaporized into the gas phase at the top of the tower.

[0027] In some embodiments, the gas phase at the top of the rectification tower is condensed by a circulating water cooler, and then the gas-liquid phase enters the coalescer. The non-condensable gas phase is cooled by deep cooling, and the liquid phase is returned to the front compartment of the coalescer. The gas phase is compressed by a compressor and returned to the hydrogenation reactor, and a stream of gas is discharged. The mass ratio of the amount of the discharged gas phase to the amount of the recycled gas is 0.01-1%.

[0028] In some embodiments, the internals of the coalescer use wire mesh and / or metal folded plates, the residence time of the coalescer is 30-60 min, the coalescer separates the oil phase and the water phase, and the water phase is sent to the wastewater system.

[0029] In some embodiments, wherein a portion of the oil phase in the coalescer is returned to the rectifier column and another portion is withdrawn as butanol product, the reflux ratio of the rectifier column is 0.5 to 5.

[0030] In some embodiments, wherein the heavy components byproduct from the butanol plant are produced from the carbonylation reaction and the butyraldehyde hydrogenation reaction, including butyraldehyde 5 to 15%, butyric acid 0.5 to 1%, butanol 5 to 8%, butyraldehyde dimers 1 to 5%, butyl butyrate 40 to 60%, octaols 10 to 20%, and dodecaols and higher 10 to 20%.

[0031] In some embodiments, wherein the heavy components separated by the rectifier column include octaols, dodecaols, and metal ions, wherein the metal ions include rhodium catalyst and corrosive metals, the gas phase withdrawn from the lower portion of the rectifier column includes butyl butyrate, butyraldehyde, butyraldehyde dimers, and butyric acid; wherein the hydrogenation reactor is packed with one or more of nickel-based, copper-based, and palladium-based catalysts.

[0032] According to another aspect of the present application, there is also provided a system for processing heavy components byproduct from a butanol plant, wherein the system is recovered by the method for recovering heavy components byproduct from a butanol plant, the system for processing heavy components byproduct from a butanol plant includes a rectifier column, a hydrogenation reactor, a hydrogen compressor, a cooler, a coalescer, and a condenser, a line for heavy components byproduct from the butanol plant is connected to the lower portion of the rectifier column, a gas phase is withdrawn from the side line of the rectifier column and is connected to the hydrogenation reactor, fresh hydrogen gas and hydrogen gas compressed by the hydrogen compressor are connected to the hydrogenation reactor, the outlet line of the hydrogenation reactor is connected to the rectifier column, the gas phase line at the top of the rectifier column is connected to the cooler, the condensed material is connected to the coalescer, the non-condensed gas phase at the top of the coalescer is connected to the condenser, the stream after deep cooling is returned to the coalescer, the gas phase is returned to the hydrogen compressor, a portion of the oil phase of the coalescer is returned to the rectifier column, another portion is withdrawn as butanol product, and the water phase at the top of the rectifier column is connected to a wastewater system. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a process flow diagram of a system for processing heavy components byproduct from a butanol plant according to an embodiment of the present application.

[0034] Figure 2 is a process flow diagram of a comparative example. DETAILED DESCRIPTION

[0035] The following description is presented to enable any person skilled in the art to practice the present application as claimed. Preferred embodiments are presented in the following description only as examples and modifications can be made by persons skilled in the art having the benefit of this disclosure without departing from the spirit and scope of the present application. The present application is defined only by the appended claims and equivalents thereto.

[0036] It is understood that the term "a" or "an" is understood to mean "at least one" or "one or more", that is, there is at least one of the specified elements, or one or more of the specified elements, in one embodiment, and that the term "one" or "a" or "an" is not limited to the meaning of the singular noun "one" or "a" or "an" but can also mean "at least one" or "one or more".

[0037] As shown in Figure 1 The process flow diagram of a butanol device by-product heavy component treatment system based on the preferred embodiment of the present application is shown. The process flow of the butanol device by-product heavy component treatment system of the present application is short, the equipment investment is small, the investment and device land occupation are small, the process flow is reasonable, the heavy component is treated by gas phase hydrogenation after rectification, there is no heavy component in the reactor feed, the catalyst life is long, the product after reaction returns to the rectification tower, the butanol and water are separated at the top, the crude butanol returns to the butanol product tower, the heavy component is discharged outside the rectification tower, the accumulation of the heavy component in the system is avoided, the gas phase is directly taken out from the rectification tower and enters the reactor, the gas phase after hydrogenation returns to the rectification tower, the heat is all used in the rectification tower, the tower kettle steam can be saved, the energy consumption of the whole system is reduced, the reaction liquid after hydrogenation passes through the coalescer to separate the oil and water phases at the top after rectification, the water phase is avoided to enter the butanol product tower, the butanol product quality is affected, at the same time, the gas phase at the top is recycled to the reactor through the compressor, the hydrogen gas is saved, and the economy is improved.

[0038] The gas phase analysis conditions of the butanol device by-product heavy component treatment system of the present application are as follows: Agilent 7890B is used, the chromatographic column is HP-5ms, the vaporization chamber temperature is 290 DEG C, the detector temperature is 280 DEG C; the temperature is programmed: 50 DEG C is kept for 2 min; 40 DEG C / min to 100 DEG C is kept for 1 min; 10 DEG C / min to 150 DEG C is kept for 2 min; 40 DEG C / min to 230 DEG C is kept for 6 min. The sample inlet temperature is 250 DEG C.

[0039] Specifically, in the butanol device by-product heavy component treatment system, the butanol device by-product heavy component treatment system comprises a rectification tower, a hydrogenation reactor, a hydrogen compressor, a cooler, a coalescer and a condenser. The rectification tower and the cooler, the coalescer, the hydrogenation reactor and the hydrogen compressor are connected, and the coalescer is connected with the cooler and the condenser. The condenser is connected with the hydrogen compressor.

[0040] Specifically, the heavy components from the butanol plant by-product pipeline enter the lower part of the rectifying tower, the rectifying tower side line extracts the gas phase to the hydrogenation reactor, while the fresh hydrogen gas, the gas after being compressed by the hydrogen compressor, and the hydrogenation reactor are connected by the outlet pipeline of the hydrogenation reactor, the gas phase pipeline at the top of the rectifying tower is connected with the condenser, the condensed material is connected with the coalescer, the non-condensable gas phase at the top of the coalescer is connected with the condenser, the stream after being deeply cooled returns to the coalescer, the gas phase returns to the hydrogenation compressor, part of the oil phase of the coalescer returns to the rectifying tower, part of the butanol product is extracted, and the water phase at the top of the rectifying tower enters the wastewater system.

[0041] Specifically, (1) the heavy components from the butanol plant by-product pass through the rectifying tower, the heavy components are separated at the tower bottom, the gas phase stream containing butyraldehyde, butyric acid, butyl butyrate, etc. is mixed with fresh hydrogen and recycled gas and then enters the hydrogenation reactor; (2) the mixed stream returns to the rectifying tower after the gas phase hydrogenation reaction; (3) the gas phase at the top of the rectifying tower is condensed in two stages, and three-phase separation of gas phase-oil phase-water phase is realized in the coalescer; (4) part of the oil phase of the coalescer returns to the rectifying tower, and part of the butanol product is extracted; (5) the gas phase after being deeply cooled is compressed by the hydrogen compressor and returned to the hydrogenation reactor, and a stream of exhaust gas is extracted to avoid the accumulation of small molecular impurities in the recycled gas.

[0042] In order to better embody the technical effects of the butanol plant by-product heavy component treatment system of the present application, the following Figure 2 structure is used as a comparison. As Figure 2 shown, the heavy components from the butanol plant by-product are connected with the 01 buffer tank, the buffer tank outlet pipeline is connected with the 02 pump, the pump outlet pipeline is connected with the hydrogen pipeline and then goes to the 03 hydrogenation reactor, the hydrogenation reactor outlet pipeline is connected with the 04 degassing tank, the degassing tank top gas phase pipeline is connected with the 05 rectifying tower top gas phase pipeline to exhaust gas, the degassing tank bottom outlet pipeline is connected with the 05 butanol product tower, the butanol product tower side line extracts butanol product, and the tower bottom outlet pipeline goes to the heavy component pipeline.

[0043] Specifically, the following examples 1 to 4 use the butanol plant by-product heavy component treatment system of the present application, and the comparative examples 1 to 4 use the structure and process flow shown in Figure 2 .

[0044] More specifically, examples 1 to 4 using the butanol plant by-product heavy component treatment system of the present application are as follows:

[0045] Example 1

[0046] According to Figure 1The heavy component from the butyraldehyde plant is produced from the carbonylation reaction and the butyraldehyde hydrogenation reaction process, which contains 5-15% butyraldehyde, 0.5-1% butyric acid, 5-8% butanol, 1-5% butyraldehyde dimer, 40-60% butyl butyrate, 10-20% carbon octanol and carbon twelve and above substances.

[0047] The distillation column is operated under positive pressure with a pressure of 1.0 MPaG, and the number of plates of the distillation column is 50 theoretical plates. The heavy component stream from the butanol plant is introduced into the distillation column at the 9th plate (from bottom to top) position, and the gas phase is extracted from the 16th plate of the distillation column to the hydrogenation reactor. Fresh hydrogen gas, recycled hydrogen gas and the gas phase extracted from the side of the distillation column are mixed and then introduced into the hydrogenation reactor, and the molar ratio of hydrogen gas to the gas phase extracted from the side is 10. The hydrogenation reactor adopts a fixed bed, the reaction temperature of the hydrogenation reactor is 230°C, the reaction pressure is 0.8 MPaG, the space velocity of the hydrogenation reaction is 1 h-1, and the hydrogenation reactor is filled with palladium-carbon catalyst. The gas phase at the outlet of the hydrogenation reactor is introduced into the 20th plate of the distillation column, and the butanol and water generated by the hydrogenation reaction are vaporized into the gas phase at the top of the column. The gas phase at the top of the distillation column is condensed after passing through the circulating water cooler, and the gas-liquid two-phase enters the coalescer. The non-condensable gas phase is deeply cooled by refrigerated water, and the liquid phase returns to the front compartment of the coalescer. The gas phase is compressed by the hydrogen compressor and returned to the hydrogenation reactor. To avoid the accumulation of impurities in the circulating gas, a portion of the gas phase is discharged, and the mass ratio of the discharged gas phase to the circulating gas is 0.5%. The inner part of the coalescer adopts a wire mesh inner part, and the residence time is 30 min. The coalescer separates the oil phase and the water phase, and the water phase is sent to the wastewater system. The reflux ratio of the distillation column is 1.

[0048] Example 2

[0049] According to the process flow connection device as Figure 1 The heavy component from the butyraldehyde plant is produced from the carbonylation reaction and the butyraldehyde hydrogenation reaction process, which contains 5-15% butyraldehyde, 0.5-1% butyric acid, 5-8% butanol, 1-5% butyraldehyde dimer, 40-60% butyl butyrate, 10-20% carbon octanol and carbon twelve and above substances.

[0050] The rectification tower is operated under positive pressure with a pressure of 0.8 MPaG, and the number of plates of the rectification tower is 60 theoretical plates. The by-product heavy component stream from the butanol device enters the rectification tower at 5 plates (from bottom to top) position, and the gas phase is extracted from the side of the 18th plate of the rectification tower to the hydrogenation reactor. Fresh hydrogen gas, recycled hydrogen gas and the gas phase extracted from the side of the rectification tower are mixed and then enter the hydrogenation reactor, and the molar ratio of hydrogen gas to the gas phase extracted from the side is 8. The hydrogenation reactor adopts a fixed bed, the reaction temperature of the hydrogenation reactor is 250°C, the reaction pressure is 0.6 MPaG, the space velocity of the hydrogenation reaction is 3h-1, and the hydrogenation reactor is filled with palladium-carbon catalyst. The gas phase at the outlet of the hydrogenation reactor goes to the 25th plate of the rectification tower, and the butanol and water generated by the hydrogenation reaction are vaporized in the gas phase at the top of the tower. The gas phase at the top of the rectification tower is condensed after passing through the circulating water cooler, and the gas-liquid two-phase enters the coalescer. The non-condensable gas phase is deeply cooled by refrigerated water, and the liquid phase returns to the front compartment of the coalescer. The gas phase is compressed by the hydrogen compressor and returned to the hydrogenation reactor. In order to avoid the accumulation of impurities in the circulating gas, a gas phase is discharged, and the mass ratio of the discharged gas phase to the circulating gas is 0.1%. The inner part of the coalescer adopts a wire mesh inner part, and the residence time is 60 min. The coalescer separates the oil phase and the water phase, and the water phase is sent to the wastewater system. The reflux ratio of the rectification tower is 3.

[0051] Example 3

[0052] According to the process flow connection device as Figure 1 The heavy components by-product from the butyraldehyde device come from the carbonylation reaction and the butyraldehyde hydrogenation reaction process, which contains 5-15% butyraldehyde, 0.5-1% butyric acid, 5-8% butanol, 1-5% butyraldehyde dimer, 40-60% butyl butyrate, 10-20% carbon octanol and carbon twelve and above substances.

[0053] The distillation column operates under positive pressure at 0.9 MPaG and has 60 theoretical plates. A recombinant fraction of the butanol byproduct enters the distillation column at plate 5 (from bottom to top). A gaseous phase is drawn from the side stream of plate 15 and sent to the hydrogenation reactor. Fresh hydrogen, recycled hydrogen, and the gaseous phase drawn from the side stream are mixed and then fed into the hydrogenation reactor at a molar ratio of 15. The hydrogenation reactor is a fixed-bed reactor with a reaction temperature of 180°C, a reaction pressure of 0.6 MPaG, and a space velocity of 3 h⁻¹. The reactor is packed with a palladium-on-carbon catalyst. The gaseous phase exiting the hydrogenation reactor goes to plate 30 of the distillation column, where the butanol and water produced in the hydrogenation reaction are distilled to the top vapor phase. The vapor phase at the top of the distillation column is condensed by the circulating water cooler, and the gas and liquid phases enter the coalescer. The non-condensable vapor phase is further cooled by chilled water, and the liquid phase returns to the front compartment of the coalescer. The vapor phase is compressed by the hydrogen compressor and returned to the hydrogenation reactor. To avoid the accumulation of impurities in the circulating gas, one vapor phase is discharged, and the mass ratio of the discharged vapor phase to the circulating gas is 0.5%. The internal components of the coalescer are made of wire mesh, and the residence time is 45 minutes. The coalescer separates the oil phase and the water phase. The water phase is sent to the wastewater system. The reflux ratio of the distillation column is 2.

[0054] Example 4

[0055] According to such Figure 1 The process flow connection device, the heavy components of the butyraldehyde unit by-product are produced from the carbonylation reaction and the butyraldehyde hydrogenation reaction process, which contain 5-15% butyraldehyde, 0.5-1% butyric acid, 5-8% butanol, 1-5% butyraldehyde dimer, 40-60% butyrate esters, C8 alcohol and C12 and above substances 10-20%.

[0056] The rectification tower is operated under positive pressure with a pressure of 1.0 MPaG, and the number of plates of the rectification tower is 60 theoretical plates. The by-product heavy component stream from the butanol device enters the rectification tower at 7 plates (from bottom to top) position, and the gas phase is extracted from the side of the 18th plate of the rectification tower to the hydrogenation reactor. Fresh hydrogen, recycled hydrogen and the gas phase extracted from the side of the rectification tower are mixed and then enter the hydrogenation reactor, and the molar ratio of hydrogen to the gas phase extracted from the side is 6. The hydrogenation reactor adopts a fixed bed, the reaction temperature of the hydrogenation reactor is 240°C, the reaction pressure is 0.7 MPaG, the space velocity of the hydrogenation reaction is 0.5 h-1, and the hydrogenation reactor is filled with palladium-carbon catalyst. The gas phase at the outlet of the hydrogenation reactor goes to the 30th plate of the rectification tower, and the butanol and water generated by the hydrogenation reaction are vaporized into the gas phase at the top of the tower. The gas phase at the top of the rectification tower is condensed after passing through the circulating water cooler, and the gas-liquid two-phase enters the coalescer. The non-condensable gas phase is deeply cooled by refrigerated water, and the liquid phase returns to the front compartment of the coalescer. The gas phase is compressed by the hydrogen compressor and returned to the hydrogenation reactor. To avoid the accumulation of impurities in the circulating gas, a gas phase is discharged, and the mass ratio of the discharged gas phase to the circulating gas is 0.1%. The inner part of the coalescer adopts a wire mesh inner part, and the residence time is 60 min. The coalescer separates the oil phase and the water phase, and the water phase is sent to the wastewater system. The reflux ratio of the rectification tower is 1.

[0057] By contrast, the following comparative examples 1 to 4 are used Figure 2 The structure and process flow of comparative examples 1 to 4 are as follows:

[0058] Comparative Example 1

[0059] According to the process flow of the device as shown in Figure 1 The heavy components by-produced from the butyraldehyde device are generated from the carbonylation reaction and the butyraldehyde hydrogenation reaction process, and contain 5-15% butyraldehyde, 0.5-1% butyric acid, 5-8% butanol, 1-5% butyraldehyde dimer, 40-60% butyl butyrate, 10-20% carbon octanol and carbon twelve and above substances.

[0060] The rectification tower is operated under positive pressure with a pressure of 1.0 MPaG and 50 theoretical plates. The by-product heavy component stream from the butanol unit is introduced into the 9th plate (from bottom to top) of the rectification tower, and the gas phase is drawn from the 16th plate of the rectification tower to the hydrogenation reactor. Fresh hydrogen and recycled hydrogen are mixed with the gas phase drawn from the rectification tower and then introduced into the hydrogenation reactor, and the molar ratio of hydrogen to the gas phase drawn from the rectification tower is 10. The hydrogenation reactor is a fixed bed, and the reaction temperature of the hydrogenation reactor is 230°C, the reaction pressure is 0.8 MPaG, the space velocity of the hydrogenation reaction is 1 h-1, and the hydrogenation reactor is filled with a copper-based catalyst. The gas phase at the outlet of the hydrogenation reactor is introduced into the 20th plate of the rectification tower, and the butanol and water generated by the hydrogenation reaction are vaporized in the gas phase at the top of the rectification tower. After the gas phase at the top of the rectification tower is condensed by a circulating water cooler, the gas-liquid two-phase is introduced into a coalescer, the non-condensable gas phase is deep-cooled by a refrigeration water, and then the liquid phase is returned to the front compartment of the coalescer, and the gas phase is compressed by a compressor and then returned to the hydrogenation reactor. In order to avoid the accumulation of impurities in the circulating gas, a gas phase is discharged, and the mass ratio of the discharged gas phase to the circulating gas is 4.3%. The inner part of the coalescer is a wire mesh inner part, and the residence time is 30 min. The coalescer separates the oil phase and the water phase, the water phase is sent to a wastewater system, and the reflux ratio of the rectification tower is 1.

[0061] Comparative Example 2

[0062] According to the process flow of the connecting device as shown in Figure 1 The heavy component by-product from the butyraldehyde unit is generated from the carbonylation reaction and the butyraldehyde hydrogenation reaction process, and contains 5-15% butyraldehyde, 0.5-1% butyric acid, 5-8% butanol, 1-5% butyraldehyde dimer, 40-60% butyl butyrate, 10-20% octacosanol and dodecane and above.

[0063] The distillation column operates under positive pressure at 0.8 MPaG and has 50 theoretical plates. A recombinant fraction of the butanol byproduct enters the 7th plate (from bottom to top) of the distillation column, and a vapor phase is drawn from the 18th plate side stream and sent to the hydrogenation reactor. Fresh hydrogen, recycled hydrogen, and the vapor phase drawn from the distillation column side stream are mixed and then fed into the hydrogenation reactor at a hydrogen-to-vapor molar ratio of 12. The hydrogenation reactor is a fixed-bed reactor with a reaction temperature of 250°C, a reaction pressure of 0.8 MPaG, and a space velocity of 1 h⁻¹. The reactor is packed with a nickel-based catalyst. The vapor phase exiting the hydrogenation reactor goes to the 20th plate of the distillation column, where the butanol and water produced in the hydrogenation reaction are distilled to the top vapor phase. After the vapor phase at the top of the distillation column is condensed by the circulating water cooler, the gas and liquid phases enter the coalescer. The non-condensable vapor phase is further cooled by chilled water, and the liquid phase returns to the pre-coalescing compartment of the coalescer. The vapor phase is compressed by the compressor and returned to the hydrogenation reactor. To avoid the accumulation of impurities in the circulating gas, one vapor phase is discharged, and the discharged vapor phase accounts for 4.5% of the circulating gas volume by mass. The coalescer internals use wire mesh internals, with a residence time of 30 minutes. The coalescer separates the oil phase and the water phase. The water phase is sent to the wastewater system. The reflux ratio of the distillation column is 1.

[0064] Comparative Example 3

[0065] According to Figure 1 The process flow connection device, the heavy components of the butyraldehyde unit by-product are produced from the carbonylation reaction and the butyraldehyde hydrogenation reaction process, which contain 5-15% butyraldehyde, 0.5-1% butyric acid, 5-8% butanol, 1-5% butyraldehyde dimer, 40-60% butyrate esters, C8 alcohol and C12 and above substances 10-20%.

[0066] The distillation column operates under positive pressure at 0.6 MPaG and has 50 theoretical plates. A recombinant fraction of the butanol byproduct enters plate 10 (from bottom to top) of the distillation column. A vapor stream from plate 18 is drawn off and sent to the hydrogenation reactor. Fresh hydrogen, recycled hydrogen, and the vapor stream from the distillation column are mixed and fed into the hydrogenation reactor at a molar ratio of 8:1. The hydrogenation reactor is a fixed-bed reactor operating at a reaction temperature of 230°C, a reaction pressure of 0.7 MPaG, and a space velocity of 1 h⁻¹. The reactor is packed with a copper-based catalyst. The vapor stream from the hydrogenation reactor exits to plate 20 of the distillation column, where the butanol and water produced in the hydrogenation reaction are distilled off to the top vapor phase. After the vapor phase at the top of the distillation column is condensed by the circulating water cooler, the gas and liquid phases enter the coalescer. The non-condensable vapor phase is further cooled by chilled water, and the liquid phase returns to the pre-coalescing compartment of the coalescer. The vapor phase is compressed by the compressor and returned to the hydrogenation reactor. To avoid the accumulation of impurities in the circulating gas, one vapor phase is discharged, accounting for 5% of the circulating gas volume by mass. The coalescer internals use wire mesh internals, with a residence time of 60 minutes. The coalescer separates the oil and water phases, with the water phase sent to the wastewater system. The reflux ratio of the distillation column is 2.

[0067] Comparative Example 4

[0068] According to Figure 1 The process flow connects to the equipment. The heavy components, byproducts of the butyraldehyde unit, originate from the carbonylation and hydrogenation reactions of butyraldehyde. These components contain 5-15% butyraldehyde, 0.5-1% butyric acid, 5-8% butanol, 1-5% butyraldehyde dimer, 40-60% butyl butyrate, and 10-20% C8 alcohols and C12 or higher compounds. The heavy components are sent to a buffer tank, then pumped to the feed line. After mixing with hydrogen, they enter the hydrogenation reactor at a pressure of 3 MPaG, a reaction temperature of 280℃, a hydrogen-to-heavy component molar ratio of 8, and a space velocity of 2 h⁻¹. After hydrogenation, the material goes to a degassing tank at a pressure of 50 kPaG. The top gas phase is returned to the butanol unit to recover hydrogen, while the bottom phase is collected and sent to the butanol product tower. The butanol product tower has 35 theoretical plates and a pressure of 0.8 MPaG. The top gas phase is condensed and the liquid phase is completely refluxed at a rate of 3 times the feed rate. The non-condensable gas phase is sent to the waste gas network. Butanol was collected from the 28th tray of the distillation column, and heavy components were collected from the bottom of the column. The residual butanol content in the heavy components was 10%.

[0069] In a further comparative analysis, the conversion rate of the hydrogenation reaction, the yield of butanol, and the hydrogen consumption in the examples and comparative examples were evaluated by comparing the operating cycles of the examples and comparative examples (based on an 80% reduction in the yield of butanol) as follows:

[0070]

[0071] Therefore, the butanol device by-product heavy component treatment system has the following effects: short process flow, less equipment investment, less investment and device area; reasonable process flow, the heavy component is treated by gas phase hydrogenation after rectification, no heavy component in the reactor feed, long catalyst life; the product after reaction returns to the rectification tower, butanol and water are separated at the top of the tower, butanol is collected at the top, and the heavy component is discharged outside the rectification tower kettle, avoiding accumulation of the heavy component in the system; the traditional hydrogenation reaction feed needs to be heated, and the reaction liquid after hydrogenation needs to be cooled, causing energy waste, and the butanol device by-product heavy component treatment system adopts a rectification tower gas phase collection directly into a reactor, and the gas phase after hydrogenation returns to the rectification tower, so that all the heat is used in the rectification tower, the kettle steam can be saved, and the energy consumption of the whole system is reduced; the reaction liquid after hydrogenation passes through the rectification tower, and the oil and water are separated by the coalescer at the top of the tower, avoiding the water phase into the butanol product and affecting the butanol product quality, and the gas phase at the top of the tower is recycled to the reactor by the compressor, saving hydrogen and improving economic efficiency.

[0072] Corresponding to the embodiment of the butanol device by-product heavy component treatment system, according to another aspect of the present application, a recovery method of the butanol device by-product heavy component treatment system is also provided, in which the heavy component from the butanol device enters the rectification tower, the carbon eight alcohol, the carbon twelve alcohol and the heavy component containing metal are removed from the kettle of the tower, the gas phase stream containing butyl butyrate, butyric acid, butyraldehyde and butyraldehyde dimer is extracted from the lower part of the tower and mixed with fresh hydrogen and circulating gas to enter the hydrogenation reactor, the gas phase stream at the outlet of the reaction is returned to the middle part of the rectification tower, the gas phase at the top of the rectification tower is condensed by the condenser and then enters the coalescer, the separated gas phase is condensed by the cryogenic unit and then the liquid phase is returned to the coalescer, the gas phase is returned to the hydrogenation reactor by the hydrogen compressor, a small amount of the circulating gas is discharged to prevent accumulation of light components, the liquid phase after condensation is separated into oil and water in the coalescer, the water phase is removed to the waste water system, and part of the oil phase is returned to the tower and part of the oil phase is collected as butanol product.

[0073] Specifically, the recovery method of the butanol device by-product heavy component treatment system includes the following steps:

[0074] S100: the heavy component by-product of the butanol device enters the middle and lower part of the rectification tower, the heavy components such as carbon eight alcohol, carbon twelve alcohol and metal ions are separated by the rectification tower, and a gas phase is extracted from the middle and lower part of the rectification tower, which mainly contains butyl butyrate, butyraldehyde, butyraldehyde polymer and butyric acid;

[0075] S200: the gas phase extracted from the rectification tower is mixed with fresh hydrogen and circulating gas and then enters the hydrogenation reactor, the stream is selectively hydrogenated into butanol and water, and the fixed bed reactor is filled with a hydrogenation catalyst;

[0076] S300: the reaction product after reaction returns to the rectification tower, and butanol and water are separated to the top of the tower in the rectification tower;

[0077] S400: The gas phase at the top of the rectification tower is condensed in one stage, and then the gas-liquid enters the coalescer. The non-condensable gas phase in the coalescer is further cooled, and the liquid phase returns to the coalescer. The gas phase is compressed by a compressor and then returns to the hydrogenation reactor. To avoid the accumulation of impurities, a circulating gas is discharged;

[0078] S500: The coalescer separates the condensed liquid phase into oil and water. Part of the oil phase returns to the rectification tower as reflux, and part of the oil phase goes to the butanol product tower of the device to purify butanol products. The water phase is discharged to the wastewater system.

[0079] In the step S100, the heavy components separated by the rectification tower include carbon octanol, carbon dodecanol, and metal ions, wherein the metal ions include rhodium catalysts and corrosive metals. The gas phase extracted from the lower part of the rectification tower includes butyl butyrate, butyl aldehyde, butyl aldehyde polymer, and butyric acid.

[0080] It is worth mentioning that the heavy components of the butanol device are separated by the rectification tower. The gas phase stream extracted from the middle part of the rectification tower is mainly enriched with aldehydes, acids, and esters. The hydrogenation catalyst palladium / carbon catalyst is used to generate butanol by hydrogenation. The gas phase hydrogenation can recover butanol with high selectivity. There is no heavy component in the hydrogenation gas phase feed, the catalyst has a long service life, the product quality is stable, the long-term stable operation of the device is ensured, the amount of heavy components discharged from the device is reduced, the butyl aldehyde consumption is reduced, and the economic efficiency of the device is greatly improved.

[0081] Corresponding to the embodiment of the butanol device by-product heavy component treatment system of the application, the recovery method of the butanol device by-product heavy component treatment system of the application has good technical effects on butyl aldehyde conversion rate, butyl acid conversion rate, butyl butyrate conversion rate, butyl alcohol recovery rate, hydrogen loss amount, and operation period.

[0082] In the recovery method of the butanol device by-product heavy component treatment system of the application, the heavy components by-produced by the butyl aldehyde device come from the carbonylation reaction and the butyl aldehyde hydrogenation reaction process. The heavy components contain 5-15% butyl aldehyde, 0.5-1% butyl acid, 5-8% butyl alcohol, 1-5% butyl aldehyde dimer, 40-60% butyl butyrate, 10-20% carbon octanol, and carbon dodecanol and above substances.

[0083] Preferably, the rectification tower is operated at positive pressure, the pressure is 0.1-2.0 MPaG, the number of plates of the rectification tower is 35-80 theoretical plates; preferably, the by-product heavy component stream from the butanol device enters the rectification tower at 5-10 plates (from bottom to top) position, the gas phase is extracted from the side line of the 15th-18th plate of the rectification tower and enters the hydrogenation reactor; preferably, the fresh hydrogen, the circulating gas and the gas phase extracted from the side line of the rectification tower are mixed and then enter the hydrogenation reactor, the molar ratio of hydrogen to the gas phase extracted from the side line is 6-15, more preferably, the molar ratio is 8-10; preferably, the hydrogenation reactor adopts a fixed bed, the reaction temperature of the hydrogenation reactor is 160-250°C, more preferably, the reaction temperature is 180-230°C, the reaction pressure is 0.5-1 MPaG, the space velocity of the hydrogenation reaction is 0.5-3 h -1 , preferably 1-1.5 h -1 ; preferably, the hydrogenation reactor is filled with one or more of nickel-based, copper-based and palladium-based catalysts, preferably palladium-carbon catalyst, the reaction temperature is low, the impurities are few and the selectivity is high when the palladium-carbon catalyst is used, and butanol and water are generated by the reaction; preferably, the gas phase at the outlet of the hydrogenation reactor enters the 20th-30th plate of the rectification tower, and the butanol and water generated by the hydrogenation reaction are vaporized into the gas phase at the top of the tower; preferably, after the gas phase at the top of the rectification tower is condensed by a circulating water cooler, the gas-liquid two-phase enters a coalescer, the non-condensable gas phase is deeply cooled by refrigerated water and then the liquid phase returns to the front compartment of the coalescer, and the gas phase is compressed by a compressor and then returns to the hydrogenation reactor; in order to avoid the accumulation of impurities in the circulating gas, a part of the gas phase is discharged, and the mass ratio of the amount of the discharged gas phase to the amount of the circulating gas is 0.01-1%, which can save hydrogen; preferably, the internal parts of the coalescer adopt a wire mesh and / or a metal folded plate, the residence time of the coalescer is 30-60 min, the coalescer separates the oil phase and the water phase, and the water phase is sent to a wastewater system; preferably, a part of the oil phase in the coalescer returns to the rectification tower, and the other part is collected as butanol product, and the reflux ratio of the rectification tower is 0.5-5, more preferably, the reflux ratio is 1-3.

[0084] Therefore, by the recovery method of the butanol device by-product heavy component treatment system of the present application, not only the material consumption of the butanol device can be reduced, but also the butanol yield is high, the process flow is short, the equipment investment is saved, the device occupation area is saved, and the economic efficiency of the butanol device is greatly improved compared with other methods.

[0085] Those skilled in the art should understand that the embodiments of the present application shown in the above description and the accompanying drawings are only examples and do not limit the present application. The purpose of the present application has been completely and effectively achieved. The function and structural principle of the present application have been shown and described in the embodiments, and the embodiments of the present application can be any modification or change without departing from the principle.

Claims

1. A recovery process for a butanol plant off-gas byproduct processing system, comprising: The recovery method of the heavy component treatment system of the butanol plant comprises the following steps: The heavy component produced by the butanol plant enters the lower part of the rectifying tower, the heavy component is separated by the rectifying tower, and a gas phase is extracted from the lower part of the rectifying tower; The gas phase extracted from the rectifying tower is mixed with fresh hydrogen and recycled gas and then enters the hydrogenation reactor, and the stream is selectively hydrogenated into butanol and water, and the fixed bed reactor is filled with a hydrogenation catalyst; and The reaction product after the reaction is returned to the rectifying tower, and butanol and water are separated to the top of the tower in the rectifying tower; The gas phase at the top of the rectifying tower is condensed after passing through a circulating water cooler, and the gas-liquid two-phase enters the coalescer, the liquid phase returns to the front compartment of the coalescer after being deeply cooled by chilled water, the gas phase is compressed by a compressor and then returned to the hydrogenation reactor, and a gas phase is discharged, and the mass ratio of the amount of the discharged gas phase to the amount of the recycled gas is 0.01-1%; The inner part of the coalescer uses a wire mesh and / or a metal folded plate, the residence time of the coalescer is 30-60 min, the coalescer separates an oil phase and a water phase, and the water phase is sent to a wastewater system; Part of the oil phase in the coalescer is returned to the rectifying tower, and the other part is butanol product, and the reflux ratio of the rectifying tower is 0.5-5; The gas phase stream extracted from the lower part of the rectifying tower is enriched with aldehydes, acids, and esters, and then hydrogenated into butanol by a hydrogenation catalyst such as palladium or carbon, the butanol is recovered by gas-phase hydrogenation with high selectivity, and there is no heavy component in the hydrogenation gas phase feed.

2. The recovery method of the heavy component treatment system of the butanol plant according to claim 1, wherein the rectifying tower is operated at positive pressure, and the pressure is 0.1-2.0 MPaG, and the number of plates of the rectifying tower is 35-80 theoretical plates.

3. The recovery method of the heavy component treatment system of the butanol plant according to claim 1, wherein the heavy component stream produced by the butanol plant enters the rectifying tower from the bottom to the position of 5-10 theoretical plates, and the gas phase is extracted from the side of the 15th-18th theoretical plate of the rectifying tower to the hydrogenation reactor.

4. The recovery method of butanol device by-product heavy component treatment system according to claim 1, wherein the fresh hydrogen, the circulating gas and the gas phase extracted from the side line of the rectifying tower are mixed and then fed into the hydrogenation reactor, the molar ratio of hydrogen to the gas phase extracted from the side line is 6-15, the hydrogenation reactor adopts a fixed bed, the reaction temperature of the hydrogenation reactor is 160-250 DEG C, the reaction pressure is 0.5-1 MpaG, the space velocity of the hydrogenation reaction is 0.5-3 h -1 .

5. The recovery method of the heavy component treatment system of the butanol plant according to claim 1, wherein the gas phase at the outlet of the hydrogenation reactor is sent to the rectifying tower at 20-30 theoretical plates, and the butanol and water generated by the hydrogenation reaction are sent to the gas phase at the top of the tower.

6. The recovery method of the heavy component treatment system of the butanol plant according to any one of claims 1-5, wherein the heavy component produced by the butanol plant is produced in the processes of the carbonylation reaction and the butyraldehyde hydrogenation reaction, and includes 5-15% butyraldehyde, 0.5-1% butyric acid, 5-8% butanol, 1-5% butyraldehyde dimer, 40-60% butyl butyrate, 10-20% octa-alcohol, and 10-20% dodeca-alcohol.

7. The recovery method of the heavy component treatment system of the butanol plant according to any one of claims 1-5, wherein the heavy component separated by the rectifying tower includes octa-alcohol, dodeca-alcohol, and metal ions, the metal ions include rhodium catalysts and corrosive metals, the gas phase extracted from the lower part of the rectifying tower includes butyl butyrate, butyraldehyde, butyraldehyde polymer, and butyric acid, and the hydrogenation reactor is filled with one or more of a nickel-based catalyst, a copper-based catalyst, and a palladium-based catalyst.

8. A butanol plant off-gas heavy component processing system characterized by, The butanol device byproduct heavy component processing system is recovered by the recovery method of any one of claims 1 to 7, the butanol device byproduct heavy component processing system comprising a rectifying tower, a hydrogenation reactor, a hydrogen compressor, a cooler, a coalescer, and a condenser, a heavy component pipeline from a butanol device byproduct entering a lower portion of the rectifying tower, the rectifying tower side-drawing a gas phase to enter the hydrogenation reactor, while fresh hydrogen gas, and gas after compression by the hydrogen compressor going to the hydrogenation reactor, an outlet pipeline of the hydrogenation reactor connecting with the rectifying tower, a gas phase pipeline at a top of the rectifying tower connecting with the cooler, condensed material connecting with the coalescer, a non-condensed gas phase at a top of the coalescer connecting with the condenser, a stream after deep cooling returning to the coalescer, a gas phase returning to the hydrogenation reactor, a part of an oil phase of the coalescer returning to the rectifying tower, a part of butanol product being extracted, an aqueous phase at a top of the rectifying tower entering a wastewater system; wherein the gas phase analysis condition of the butanol device byproduct heavy component processing system is: using Agilent 7890B, a chromatographic column HP-5ms, a vaporization chamber temperature of 290 DEG C, a detector temperature of 280 DEG C; programmed temperature rising: 50 DEG C for 2 min; 40 DEG C / min to 100 DEG C for 1 min; rising to 150 DEG C at 10 DEG C / min, keeping for 2 min; rising to 230 DEG C at 40 DEG C / min, keeping for 6 min; a sample inlet temperature of 250 DEG C; wherein the rectifying tower is operated under positive pressure, the pressure being 0.1-2.0 MPaG, the number of rectifying tower plates being 35-80 theoretical plates; a heavy component stream from a butanol device byproduct entering 5-10 plates of the rectifying tower, a gas phase side-drawn from the 15th-18th plate of the rectifying tower going to the hydrogenation reactor; fresh hydrogen gas, circulating gas, and the gas phase side-drawn from the rectifying tower mixing to go to the hydrogenation reactor, the molar ratio of hydrogen to the gas phase side-drawn being 6-15; the hydrogenation reactor using a fixed bed, the reaction temperature of the hydrogenation reactor being 160 DEG C-250 DEG C, the reaction pressure being 0.5-1 MPaG, the space velocity of the hydrogenation reaction being 0.5-3 h -1 ; the hydrogenation reactor being filled with one or more of a nickel system, a copper system, and a palladium system catalyst; the gas phase at the outlet of the hydrogenation reactor going to 20-30 plates of the rectifying tower, butanol and water generated by the hydrogenation reaction being vaporized to the top gas phase of the rectifying tower; the top gas phase of the rectifying tower being condensed after passing through a circulating water cooler, the gas-liquid two-phase entering the coalescer, the non-condensed gas phase being deep-cooled after passing through a refrigerated water, the liquid phase returning to a front compartment of the coalescer, the gas phase being compressed after passing through a compressor to return to the hydrogenation reactor, a part of the circulating gas being discharged to avoid impurity accumulation, the mass ratio of the discharged gas phase to the circulating gas being 0.01-1%; the coalescer internals using a wire mesh and / or a metal folded plate, the residence time of the coalescer being 30-60 min, the coalescer separating out an oil phase and an aqueous phase, the aqueous phase being sent to a wastewater system; a part of the oil phase in the coalescer returning to the rectifying tower, a part of butanol product being extracted, the reflux ratio of the rectifying tower being 0.5-5.

Images