CN115121083A - Device and method for purification and separation of ammonia-containing tail gas in the production process of carbonylation intermediate - Google Patents

Abstract

The invention provides a device and method for purifying and separating ammonia-containing tail gas in the production process of carbonylation intermediates. The device sequentially includes a gas-liquid separation unit, an ammonium bicarbonate capture unit, a compression separation unit and an ammonia separation unit. The unit includes a condenser and a first gas-liquid separator, the ammonium bicarbonate capture unit includes an ammonium bicarbonate trap, the compression separation unit includes a compressor and a second gas-liquid separator, and the ammonia separation unit includes an ammonia separation tower and a third gas-liquid separator Separator, the liquid phase outlets of the first, second and third gas-liquid separators are connected to the same pipeline for reuse. In the present invention, most of the organic components are separated through the gas-liquid separation unit through the setting of the ammonium bicarbonate capture unit and the multi-stage separation unit, and then the ammonium bicarbonate is separated out through the ammonium bicarbonate trap, and then the method of compression separation and tower separation is carried out. Separating organic matter, realizing the purification of ammonia-containing tail gas and efficient recovery of ammonia, ammonium bicarbonate and organic components, at the same time, it can effectively solve the problem of tube blockage, and run continuously and stably for a long time.

Description

Device and method for purification and separation of ammonia-containing tail gas in the production process of carbonylation intermediate

technical field

The invention belongs to the technical field of organic synthesis and separation, and relates to a device and a method for purifying and separating ammonia-containing tail gas in the production process of a carbonylation intermediate.

Background technique

As a common product in the chemical industry, urea can be used to prepare important chemicals such as carbamate, carbonate, and diphenylurea. Because urea contains carbonyl groups, it is generally used in oxo synthesis reactions. It will release small molecular ammonia gas, and the generated ammonia-containing tail gas needs to be separated and recovered. However, due to the characteristics of urea, such as easy moisture absorption and poor thermal stability, ammonium bicarbonate will also be entrained in the ammonia gas. Block the exhaust pipe, affecting the continuous production of the device.

At present, the industrial methods for treating and recovering ammonia-containing tail gas mainly include water absorption method and compression separation method to obtain ammonia water and liquid ammonia respectively. Among them, the water absorption method usually adopts the method of water spraying after heating the tail gas, which can avoid the spraying process. Medium ammonium bicarbonate blocks the pipeline, but the process consumes a lot of water, and when the ammonia-containing gas phase contains organic solvents, it will cause problems such as unqualified ammonia water or substandard exhaust pollutants; the compression separation method usually liquefies the ammonia gas to form a liquid However, in this method, the compressor inlet temperature requirement is relatively low, the problem of ammonium bicarbonate clogging the pipeline is prone to occur, and the energy consumption of this method is relatively high.

For the application of urea in organic synthesis, for example, non-phosgene method to produce isocyanate, specifically adopt steps such as urea carbonylation, alcoholysis, condensation and pyrolysis, wherein, N,N-diphenylurea (DPU) is in the method The important intermediate of urea carbonylation is the product after urea carbonylation. This process will generate a large amount of ammonia gas, and entrain the solvent and ammonium bicarbonate. The effective components in the ammonia-containing tail gas are separated and recovered, which has an important impact on the stable production of this product. .

CN 102001970A discloses a method for preparing diphenylurea by direct reaction of urea and aniline by nitrogen gas stripping. In the method, urea and aniline are added into a reaction kettle in a certain molar ratio, stirred, and aerated with nitrogen gas to extract ammonia gas, a reaction by-product, and heated. The temperature is raised to a reaction temperature of 145 to 180 ° C, and the reaction is carried out at normal pressure. The reaction time is 2 to 6 h. After the reaction is completed, the stirring is stopped to naturally cool down and crystallize, and the crystalline product of the reaction is subjected to suction filtration to obtain a crystalline diphenylurea product; The method mainly involves the control of the preparation process of diphenylurea, and the subsequent treatment and recovery of the ammonia-containing gas is not explicitly mentioned.

CN 110817900A discloses a separation device and method for ammonia gas containing carbon dioxide and organic matter, the device includes a primary scrubber, a primary scrubber cooler, a secondary scrubber, a secondary scrubber cooler, a compressor, a gas Liquid separation tank, ammonia purification column and its top condenser, reflux tank and reboiler, heat exchanger, organic matter separation column and its top condenser, reflux tank and reboiler, carbonization kettle, filter; First-level washing, second-level washing, pressurization, ammonia refining, organic matter separation, carbonization and filtration steps to obtain liquid ammonia products and ammonium carbonate products; the structure of the device is relatively complex, the operation steps are numerous, and it is not clear that the compression process may produce The treatment of ammonium bicarbonate, and the operation process is greatly affected by organic components.

To sum up, in the process of non-phosgene production of carbonylation intermediates, for the treatment of ammonia-containing tail gas, it is also necessary to select appropriate equipment and operations according to the composition of the tail gas, so as to achieve high efficiency of ammonia and organic components. Recycling can avoid the problem of pipeline blockage.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, the object of the present invention is to provide a device and method for the purification and separation of ammonia-containing tail gas in the production process of a carbonylation intermediate. The ammonia-containing organic tail gas is first condensed to separate most of the organic components, and then the ammonium bicarbonate is separated out, and then the remaining organic components are removed by compression separation and tower separation to realize the ammonia and organic components in the carbonylation intermediate synthesis tail gas. And the separation and recovery of ammonium bicarbonate can effectively solve the problem of easy blockage of pipelines.

For this purpose, the present invention adopts the following technical solutions:

On the one hand, the present invention provides a device for purification and separation of ammonia-containing tail gas in the production process of carbonylation intermediates, the device sequentially comprises a gas-liquid separation unit, an ammonium bicarbonate capture unit, a compression separation unit and an ammonia separation unit, The gas-liquid separation unit includes a condenser and a first gas-liquid separator, the ammonium bicarbonate capture unit includes an ammonium bicarbonate trap, the compression separation unit includes a compressor and a second gas-liquid separator, and the ammonia separation unit It includes an ammonia separation tower and a third gas-liquid separator, and the liquid-phase outlets of the first gas-liquid separator, the second gas-liquid separator and the third gas-liquid separator are connected to the same pipeline for reuse.

In the present invention, for the production process of carbonylation intermediates, especially for the production of isocyanate intermediates, such as diphenylurea, nitrogen-containing organic raw materials are usually used, and ammonia-containing tail gas is generated after the carbonylation reaction. It will also contain ammonium bicarbonate and organic components, so the device of the present invention is provided with an ammonium bicarbonate capture unit and a multi-stage separation unit, wherein the ammonium bicarbonate capture unit is arranged between the multi-stage separation units, that is, first through gas-liquid separation unit, most of the organic components are condensed and separated, and then the ammonium bicarbonate is separated out through the structural design of the ammonium bicarbonate trap, and the remaining ammonia-containing gas is further separated by compression separation and tower separation. Effective purification of carbonylation intermediate synthesis tail gas and efficient recovery of ammonia, ammonium bicarbonate and organic components, while solving the problem that ammonium bicarbonate easily causes pipeline blockage; the device has a simple structure, can operate continuously and stably for a long time, and costs low and high production efficiency.

The following are the preferred technical solutions of the present invention, but not as limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical purpose and beneficial effects of the present invention can be better achieved and realized.

As a preferred technical solution of the present invention, the ammonia-containing tail gas comes from a carbonylation intermediate synthesis unit, preferably an N,N-diphenylurea synthesis unit.

Preferably, the condenser includes a first condenser and a second condenser, the gas phase outlet of the first condenser is connected to the second condenser, and the liquid phase outlet of the first condenser is connected to the carbonylation intermediate synthetic unit.

Preferably, the first condenser is a vertical condenser, and the second condenser is a horizontal condenser, both of which are shell-and-tube heat exchangers, and the ammonia-containing gas goes through the tubes.

In the present invention, the first condenser and the second condenser cool the ammonia-containing gas at different temperature sections, so different heat exchange media can be selected, for example, heat transfer oil is selected for the first condenser, and circulation is selected for the second condenser water.

Preferably, the first gas-liquid separator is a vertical tank, the top outlet of the first gas-liquid separator is connected to the inlet of the ammonium bicarbonate trap, and the bottom liquid-phase outlet of the first gas-liquid separator is Linked to the oxo intermediate synthesis unit.

In the present invention, the top gas-phase pipeline of the first gas-liquid separator can be provided with heat tracing, for example, low-pressure steam is selected, so as to avoid the precipitation of ammonium bicarbonate in the pipeline in advance due to the temperature drop.

As a preferred technical solution of the present invention, the ammonium bicarbonate trap is a vertical heat exchanger with a U-shaped tube inside as the tube pass, the heat exchange medium passes through the tube pass, and the inlet and outlet of the heat exchange medium are set in the The top of the ammonium bicarbonate trap.

Preferably, the middle part of the ammonium bicarbonate trap is provided with a partition along the longitudinal direction, and the partition extends to the bottom of the U-shaped pipe.

Preferably, an ammonia-containing gas inlet and an ammonia-containing gas outlet are respectively provided on the upper portions of the sides of the ammonium bicarbonate trap on both sides of the separator.

Preferably, a baffle is provided in the shell layer of the ammonium bicarbonate trap, and the baffle is arranged horizontally or inclined downward.

In the present invention, horizontal or slightly inclined downward baffles are arranged in the shell layer of the ammonium bicarbonate trap, which is beneficial for the ammonia-containing gas to fully contact the U-shaped tube for heat exchange and disturb the crystallization.

Preferably, an interlayer is provided at the bottom of the upper head tube sheet of the ammonium bicarbonate trap, a spray heat medium inlet is provided on the side of the interlayer, and a spray port is provided at the bottom of the interlayer.

In the present invention, the bottom of the ammonium bicarbonate trap is provided with a discharge port for discharging the cleaning liquid after spraying and flushing, and a liquid level port is also provided on the lower side of the ammonium bicarbonate trap to control the cleaning liquid the liquid level.

Preferably, the number of the ammonium bicarbonate traps is at least one, such as one, two, three, or four, etc. When the ammonium bicarbonate traps include more than two, they are arranged in parallel and run alternately.

In the present invention, the ammonium bicarbonate collector is used to capture ammonium bicarbonate during operation, and after the operation is completed, the device is cut out to clean the ammonium bicarbonate. On the heat pipe, the out-of-bounds area of the cleaning residue is used for sewage treatment and ammonium bicarbonate recovery.

As a preferred technical solution of the present invention, the compressor includes a screw compressor.

Preferably, the compression separation unit further includes a cooler, and the cooler is arranged between the compressor and the second gas-liquid separator.

Preferably, the cooler and the second gas-liquid separator are both vertical tanks, and the compressed ammonia-containing gas passes through the shell side of the cooler.

Preferably, the liquid phase outlet of the second gas-liquid separator is connected to the oxo intermediate synthesis unit.

As a preferred technical solution of the present invention, the ammonia separation column includes a packed column, and the packing includes a Pall ring and/or a wire mesh corrugated packing.

Preferably, the top outlet of the ammonia separation tower is also connected with a tower top condenser, and the bottom outlet is also connected with a tower kettle reboiler, both of which are vertical heat exchangers.

Preferably, the overhead condenser obtains a liquid ammonia product, and the liquid ammonia product enters a liquid ammonia storage tank.

Preferably, the third gas-liquid separator is a vertical tank, the top outlet of the third gas-liquid separator is connected to the lower inlet of the ammonia separation tower, and the bottom liquid-phase outlet of the third gas-liquid separator is connected to The oxo intermediate synthesis unit is connected.

Preferably, the first gas-liquid separator, the second gas-liquid separator and the third gas-liquid separator are connected to the confluence pipeline of the oxo intermediate synthesis unit with a circulating pump.

On the other hand, the present invention provides a method for purifying and separating ammonia-containing tail gas in the production process of carbonylation intermediate using the above-mentioned device, and the method comprises the following steps:

(1) gas-liquid separation of ammonia-containing tail gas through condensation, obtaining a separation of ammonia-containing tail gas and liquid-phase organic matter;

(2) carrying out ammonium bicarbonate trapping with the primary separation ammonia-containing tail gas obtained in step (1) to obtain secondary separation ammonia-containing tail gas and ammonium bicarbonate product, and the ammonium bicarbonate product is removed through thermal spraying;

(3) carry out compression and gas-liquid separation with the secondary separation ammonia-containing tail gas obtained in step (2), obtain three separation ammonia-containing tail gas and liquid-phase organic matter;

(4) carrying out packing separation and gas-liquid separation of the three-separated ammonia-containing tail gas obtained in step (3) to obtain purified gas and liquid-phase organic matter, and the purified gas is cooled to obtain a liquid ammonia product.

As a preferred technical solution of the present invention, the source of the ammonia-containing tail gas in step (1) includes the production process of carbonylation intermediates, preferably the process of producing N,N-diphenylurea using urea and aniline as raw materials.

Preferably, the composition of the ammonia-containing tail gas in step (1) includes ammonia, ammonium bicarbonate, aniline, carbon dioxide and N-methylaniline.

Preferably, the temperature of the ammonia-containing tail gas in step (1) is 200-240°C, such as 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C or 240°C, etc., but Not limited to the recited values, other non-recited values within the range of values apply equally.

Preferably, the condensation in step (1) includes primary condensation and secondary condensation.

Preferably, the temperature of the ammonia-containing tail gas after the primary condensation is reduced to 100-140°C, such as 100°C, 110°C, 120°C, 130°C or 140°C, etc., and the condensed liquid-phase organic matter is returned to the production of the carbonylation intermediate process.

Preferably, after the secondary condensation, the temperature of the ammonia-containing tail gas drops to 60-80°C, such as 60°C, 65°C, 70°C, 75°C, or 80°C, etc., and the liquid-phase organic matter continues to condense, and returns to the gas-liquid separation Production process of carbonylation intermediates.

Preferably, after the condensation and gas-liquid separation in step (1), the separated liquid-phase organic matter accounts for 90-95% of the total liquid-phase organic matter, such as 90%, 91%, 92%, 93%, 94% or 95% %, etc., but are not limited to the listed numerical values, and other unlisted numerical values within the numerical range are also applicable.

In the present invention, since the condensation process includes primary condensation and secondary condensation, the liquid-phase organic matter obtained through the primary condensation accounts for 80-90% of the total liquid-phase organic matter, such as 80%, 82%, 85%, 88% Or 90%, etc., and after secondary condensation and gas-liquid separation, part of it is liquefied again, and the liquid-phase organic matter separated after the secondary condensation accounts for 90-95% of the total organic matter.

As a preferred technical solution of the present invention, the ammonium bicarbonate trapping described in step (2) is carried out in an ammonium bicarbonate trap.

Preferably, when the ammonium bicarbonate is captured, the ammonia-containing tail gas is separated and cooled down to below 40°C, such as 40°C, 38°C, 35°C, 32°C, 30°C or 25°C, etc., and the ammonium bicarbonate is precipitated in the ammonium bicarbonate capture on the U-tube in the collector.

Preferably, when the number of the ammonium bicarbonate traps is more than two, they operate alternately.

Preferably, the thermal spray in step (2) is to use a heat medium for spray flushing to dissolve and remove the precipitated ammonium bicarbonate.

Preferably, the heat medium includes steam or hot water, and the removal time is not more than 0.5h, such as 0.5h, 0.45h, 0.4h, 0.35h, 0.3h, 0.25h or 0.2h, etc., but not limited to those listed value, other non-recited values within this value range also apply.

In the present invention, the top of the ammonium bicarbonate trap is provided with a heat medium spray, and the heat medium is hot water or low-pressure steam, such as 80°C hot water or 0.2MPaG steam. The system stage quickly decarbonates ammonium and takes a short time.

As a preferred technical solution of the present invention, the pressure of the secondary separation of ammonia-containing tail gas in step (3) is 0.05-0.2 MPaG, such as 0.05 MPaG, 0.08 MPaG, 0.1 MPaG, 0.12 MPaG, 0.15 MPaG, 0.18 MPaG or 0.2 MPaG, etc. , but not limited to the recited values, and other unrecited values within this range of values are equally applicable.

Preferably, after the compression, the temperature of the ammonia-containing tail gas is increased for the second time, and the gas-liquid separation is performed again after cooling.

Preferably, after the gas-liquid separation in step (3), the liquid-phase organic matter is returned to the production process of the carbonylation intermediate.

Preferably, after the gas-liquid separation in step (3), the pressure for the third separation of ammonia-containing tail gas is 2.6-3.2 MPaG, such as 2.6 MPaG, 2.7 MPaG, 2.8 MPaG, 2.9 MPaG, 3.0 MPaG, 3.1 MPaG or 3.2 MPaG, etc., but Not limited to the recited values, other non-recited values within the range of values apply equally.

As a preferred technical solution of the present invention, the packing separation described in step (4) is carried out in an ammonia separation tower.

Preferably, the packing in the ammonia separation tower includes Pall rings and/or wire mesh corrugated packing.

Preferably, the pressure at which the packing is separated in step (4) is 2.6-3.2 MPaG, such as 2.6 MPaG, 2.7 MPaG, 2.8 MPaG, 2.9 MPaG, 3.0 MPaG, 3.1 MPaG or 3.2 MPaG, etc., and the temperature is 60-70 °C, for example 60°C, 62°C, 64°C, 66°C, 68°C, or 70°C, etc., but are not limited to the recited numerical values, and other unrecited values within the respective numerical ranges are also applicable.

Preferably, when the packing is separated in step (4), the ammonia-containing tail gas is partially liquefied after three separations, the unliquefied gas phase is separated from the top of the tower, and the liquefied organic matter is heated by the tower still for gas-liquid separation again.

Preferably, the purified gas in step (4) is cooled to 40-60°C to obtain a liquid ammonia product, such as 40°C, 45°C, 50°C, 55°C or 60°C, etc., but not limited to the listed values, the value The same applies to other non-recited values in the range.

Preferably, after the gas-liquid separation in step (4), the gas phase is returned to the ammonia separation tower, and the liquid-phase organic matter is returned to the production process of the carbonylation intermediate.

Preferably, after step (3) and step (4) separated liquid-phase organic matter is decompressed to 0-0.5MPaG, for example, 0MPaG, 0.1MPaG, 0.2MPaG, 0.3MPaG, 0.4MPaG or 0.5MPaG, etc., and step (1) The separated liquid phase organics are mixed and sent to the oxo intermediate synthesis unit.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The device of the present invention passes through the setting of the ammonium bicarbonate trap unit and the multi-stage separation unit, first passes through the gas-liquid separation unit, condenses and separates most of the organic components, and then passes through the structural design of the ammonium bicarbonate trap The ammonium bicarbonate is separated out, and the remaining ammonia-containing gas is further separated from the organic matter by means of compression separation and tower separation, which realizes the effective purification of the carbonylation intermediate synthesis tail gas and the efficient recovery of ammonia, ammonium bicarbonate and organic components. The removal rate of ammonium bicarbonate is over 99.5%, the recovery rate of organic components is over 99.9%, and the purity of liquid ammonia product is over 99.9%;

(2) The device of the present invention can effectively solve the problem that ammonium bicarbonate easily causes pipeline blockage, the continuous and stable operation can reach more than 3000h, the equipment cost is low, and the production efficiency is high.

Description of drawings

Fig. 1 is the structural representation of the device for the purification and separation of ammonia-containing tail gas in the carbonylation intermediate production process provided by the embodiment of the present invention;

Fig. 2 is the structural representation of the ammonium bicarbonate trap provided by the embodiment of the present invention 1;

Among them, 1-first condenser, 2-second condenser, 3-first gas-liquid separator, 4-ammonium bicarbonate trap, 41-U-shaped pipe, 42-partition plate, 43-baffle plate, 44-interlayer, 45-spray port, 5-compressor, 6-cooler, 7-second gas-liquid separator, 8-ammonia separation tower, 9-third gas-liquid separator, 10-carbonylation intermediate synthetic unit.

Detailed ways

In order to better illustrate the present invention and facilitate understanding of the technical solutions of the present invention, the present invention is further described in detail below. However, the following embodiments are only simple examples of the present invention, and do not represent or limit the protection scope of the present invention, and the protection scope of the present invention is subject to the claims.

The following are typical but non-limiting examples of the present invention:

Example 1:

This embodiment provides a device for purification and separation of ammonia-containing tail gas in the production process of carbonylation intermediates. The schematic structural diagram of the device is shown in Figure 1, which sequentially includes a gas-liquid separation unit, an ammonium bicarbonate capture unit, and a compression separation unit. and ammonia separation unit, the gas-liquid separation unit includes a condenser and a first gas-liquid separator 3, the ammonium bicarbonate capture unit includes an ammonium bicarbonate trap 4, and the compression separation unit includes a compressor 5 and a second Gas-liquid separator 7, the ammonia separation unit includes an ammonia separation tower 8 and a third gas-liquid separator 9, the first gas-liquid separator 3, the second gas-liquid separator 7 and the third gas-liquid separator 9 The liquid phase outlet is connected to the same pipeline for reuse.

The ammonia-containing tail gas comes from the carbonylation intermediate synthesis unit 10, specifically the N,N-diphenylurea synthesis unit.

The condenser includes a first condenser 1 and a second condenser 2, the gas phase outlet of the first condenser 1 is connected to the second condenser 2, and the liquid phase outlet of the first condenser 1 is connected to the carbonylation Intermediate synthesis unit 10.

The first condenser 1 is a vertical condenser, and the second condenser 2 is a horizontal condenser, both of which are shell-and-tube heat exchangers, and the ammonia-containing gas goes through the tubes.

The first gas-liquid separator 3 is a vertical tank, the top outlet of the first gas-liquid separator 3 is connected to the inlet of the ammonium bicarbonate trap 4, and the liquid phase at the bottom of the first gas-liquid separator 3 is connected. The outlet is connected to the oxo intermediate synthesis unit 10.

The schematic structural diagram of the ammonium bicarbonate trap 4 is shown in FIG. 2 , the ammonium bicarbonate trap 4 is a vertical heat exchanger, and a U-shaped tube 41 is provided inside as the tube pass, and the heat exchange medium passes through the tube pass, and the The inlet and outlet of the heat exchange medium are both arranged on the top of the ammonium bicarbonate trap 4 .

The middle part of the ammonium bicarbonate trap 4 is provided with a partition plate 42 along the longitudinal direction, and the partition plate 42 extends to the bottom of the U-shaped pipe 41; Ammonia-containing gas inlet and ammonia-containing gas outlet.

A baffle 43 is provided in the shell layer of the ammonium bicarbonate trap 4, and the baffle 43 is arranged horizontally.

The bottom of the upper head tube plate of the ammonium bicarbonate trap 4 is provided with an interlayer 44, the side of the interlayer 44 is provided with a spray heat medium inlet, and the bottom of the interlayer 44 is provided with a spray port 45; medium steam.

The number of the ammonium bicarbonate traps 4 is two, and the two are arranged side by side and run alternately.

The compressor 4 is a screw compressor.

The compression and separation unit further includes a cooler 6 , which is arranged between the compressor 5 and the second gas-liquid separator 7 .

The cooler 6 and the second gas-liquid separator 7 are both vertical tanks, and the compressed ammonia-containing gas passes through the shell side of the cooler 6 .

The liquid phase outlet of the second gas-liquid separator 7 is connected to the carbonylation intermediate synthesis unit 10 .

The ammonia separation column 8 includes a packed column, and the packing includes a Pall ring.

The top outlet of the ammonia separation tower 8 is also connected with a tower top condenser, and the bottom outlet is also connected with a tower kettle reboiler, both of which are vertical heat exchangers; the tower top condenser obtains liquid ammonia products, so The liquid ammonia product described above enters the liquid ammonia storage tank.

The third gas-liquid separator 9 is a vertical tank, the top outlet of the third gas-liquid separator 9 is connected to the lower inlet of the ammonia separation tower 8, and the bottom liquid phase outlet of the third gas-liquid separator 9 Linked to oxo intermediate synthesis unit 10.

The first gas-liquid separator 3 , the second gas-liquid separator 7 and the third gas-liquid separator 9 are connected to the confluence pipeline of the oxo intermediate synthesis unit 10 with a circulating pump.

Example 2:

This embodiment provides a device for purification and separation of ammonia-containing tail gas in the production process of carbonylation intermediates. The device sequentially includes a gas-liquid separation unit, an ammonium bicarbonate capture unit, a compression separation unit, and an ammonia separation unit. The separation unit includes a condenser and a first gas-liquid separator 3, the ammonium bicarbonate capture unit includes an ammonium bicarbonate trap 4, the compression separation unit includes a compressor 5 and a second gas-liquid separator 7, the ammonia The separation unit includes an ammonia separation tower 8 and a third gas-liquid separator 9, and the liquid-phase outlets of the first gas-liquid separator 3, the second gas-liquid separator 7 and the third gas-liquid separator 9 are connected to the same pipe Road reuse.

The ammonia-containing tail gas comes from the carbonylation intermediate synthesis unit 10, specifically the N,N-diphenylurea synthesis unit.

The condenser includes a first condenser 1 and a second condenser 2, the gas phase outlet of the first condenser 1 is connected to the second condenser 2, and the liquid phase outlet of the first condenser 1 is connected to the carbonylation Intermediate synthesis unit 10.

The first condenser 1 is a vertical condenser, and the second condenser 2 is a horizontal condenser, both of which are shell-and-tube heat exchangers, and the ammonia-containing gas goes through the tubes.

The first gas-liquid separator 3 is a vertical tank, the top outlet of the first gas-liquid separator 3 is connected to the inlet of the ammonium bicarbonate trap 4, and the liquid phase at the bottom of the first gas-liquid separator 3 is connected. The outlet is connected to the oxo intermediate synthesis unit 10.

The ammonium bicarbonate trap 4 is a vertical heat exchanger with a U-shaped tube 41 as the tube pass, the heat exchange medium passes through the tube pass, and the inlet and outlet of the heat exchange medium are set in the ammonium bicarbonate trap. 4 tops.

The middle part of the ammonium bicarbonate trap 4 is provided with a partition plate 42 along the longitudinal direction, and the partition plate 42 extends to the bottom of the U-shaped pipe 41; Ammonia-containing gas inlet and ammonia-containing gas outlet.

A baffle 43 is provided in the shell layer of the ammonium bicarbonate trap 4, and the baffle 43 is inclined downward.

The bottom of the upper head tube plate of the ammonium bicarbonate trap 4 is provided with an interlayer 44, the side of the interlayer 44 is provided with a spray heat medium inlet, and the bottom of the interlayer 44 is provided with a spray port 45; The medium is hot water.

The number of the ammonium bicarbonate traps 4 is three, which are arranged in parallel and operate alternately.

The compressor 4 is a centrifugal compressor.

The compression and separation unit further includes a cooler 6 , and the cooler 6 is arranged between the compressor 5 and the second gas-liquid separator 7 .

The cooler 6 and the second gas-liquid separator 7 are both vertical tanks, and the compressed ammonia-containing gas passes through the shell side of the cooler 6 .

The liquid phase outlet of the second gas-liquid separator 7 is connected to the carbonylation intermediate synthesis unit 10 .

The ammonia separation tower 8 includes a packed tower, and the packing includes a wire mesh corrugated packing.

The top outlet of the ammonia separation tower 8 is also connected with a tower top condenser, and the bottom outlet is also connected with a tower kettle reboiler, both of which are vertical heat exchangers; the tower top condenser obtains liquid ammonia products, so The liquid ammonia product described above enters the liquid ammonia storage tank.

The third gas-liquid separator 9 is a vertical tank, the top outlet of the third gas-liquid separator 9 is connected to the lower inlet of the ammonia separation tower 8, and the bottom liquid phase outlet of the third gas-liquid separator 9 Linked to oxo intermediate synthesis unit 10.

Example 3:

The present embodiment provides a method for purification and separation of ammonia-containing tail gas in the production process of carbonylation intermediates, and the method adopts the device in embodiment 1 to carry out, and comprises the following steps:

(1) gas-liquid separation of the ammonia-containing tail gas after condensation, the source of the ammonia-containing tail gas is the process of using urea and aniline as raw materials to produce N,N-diphenylurea, and the composition of the ammonia-containing tail gas includes 30wt% of ammonia, 67wt% aniline, ammonium bicarbonate with a content of 100g/ ^m3 , the temperature of the ammonia-containing tail gas is 235°C, the condensation includes primary condensation and secondary condensation, after the primary condensation, the temperature of the ammonia-containing tail gas drops to 235°C. 120°C, the temperature of the ammonia-containing tail gas dropped to 60°C after the secondary condensation, and after gas-liquid separation, the condensed aniline accounted for 95% of the total aniline, and returned to the production process of N,N-diphenylurea, and obtained a primary separation containing aniline. Ammonia tail gas;

(2) the one-time separation ammonia-containing tail gas obtained in step (1) enters the ammonium bicarbonate trap 4 to carry out ammonium bicarbonate trapping, and the one-time separation ammonia-containing tail gas continues to be cooled to 38 ° C, and the ammonium bicarbonate is separated out in the ammonium bicarbonate trap 4 on the U-shaped pipe 41, and obtain secondary separation ammonia-containing tail gas; the ammonium bicarbonate product is sprayed and washed with steam, and the precipitated ammonium bicarbonate is dissolved and removed, and the removal time is 0.4h;

(3) the secondary separation ammonia-containing tail gas obtained in step (2) is compressed, the pressure before compression is 0.1MPaG, the temperature of the secondary separation ammonia-containing tail gas after the compression is increased, and the gas-liquid separation after cooling is performed again, Obtain three separations of ammonia-containing tail gas and liquid-phase aniline, the pressure of three-time separation of ammonia-containing tail gas is 2.6MPaG, and the aniline is decompressed to 0.3MPaG and then returned to the N,N-diphenylurea production process;

(4) the tertiary separation ammonia-containing tail gas obtained in step (3) adopts the ammonia separation tower 8 to carry out packing separation, the packing in the ammonia separation tower 8 is a Pall ring, the pressure of the packing separation is 2.9 MPaG, and the temperature is At 66°C, the ammonia-containing tail gas is separated for three times and partially liquefied, and the unliquefied gas phase is separated from the top of the tower. The purified gas obtained is cooled to 40°C to obtain a liquid ammonia product. The liquefied aniline is heated by the tower kettle for gas-liquid separation again, and the gas phase is returned to the ammonia separation tower. 8. The liquid phase aniline is decompressed to 0.3MPaG and returned to the production process of N,N-diphenylurea.

In this embodiment, the device and method are used to purify and separate ammonia-containing tail gas. According to the content of ammonium bicarbonate in the remaining tail gas in step (2) and the recovery amount of aniline, the removal rate of ammonium bicarbonate reaches 99.97%, and the recovery rate of aniline reaches 99.92%. %, the purity of the liquid ammonia product can reach 99.95%, and the continuous and stable operation time of the device can reach 3000h.

Example 4:

The present embodiment provides a method for purification and separation of ammonia-containing tail gas in the production process of carbonylation intermediates, and the method adopts the device in embodiment 1 to carry out, and comprises the following steps:

(1) gas-liquid separation of the ammonia-containing tail gas after condensation, the source of the ammonia-containing tail gas is the process of using urea and aniline as raw materials to produce N,N-diphenylurea, and the composition of the ammonia-containing tail gas comprises 35wt% of ammonia, 60wt% aniline, ammonium bicarbonate with a content of 80g/ ^m3 , the temperature of the ammonia-containing tail gas is 240°C, the condensation includes primary condensation and secondary condensation, and the temperature of the ammonia-containing tail gas after the primary condensation drops to 140°C, the temperature of the ammonia-containing tail gas dropped to 80°C after the secondary condensation, after gas-liquid separation, the condensed aniline accounted for 90% of the total aniline, and returned to the production process of N,N-diphenylurea, and obtained a primary separation containing aniline. Ammonia tail gas;

(2) the one-time separation ammonia-containing tail gas obtained in step (1) enters the ammonium bicarbonate trap 4 to carry out ammonium bicarbonate trapping, the one-time separation ammonia-containing tail gas continues to be cooled to 40 ° C, and the ammonium bicarbonate is separated out in the ammonium bicarbonate trap 4 on the U-shaped pipe 41, and obtain secondary separation ammonia-containing tail gas; the ammonium bicarbonate product is sprayed and washed with steam, and the precipitated ammonium bicarbonate is dissolved and removed, and the removal time is 0.5h;

(3) the secondary separation ammonia-containing tail gas obtained in step (2) is compressed, the pressure before compression is 0.05MPaG, the temperature of the secondary separation ammonia-containing tail gas after the compression is increased, and the gas-liquid separation after cooling is carried out again, Obtain three separations of ammonia-containing tail gas and liquid-phase aniline, the pressure of three-time separation of ammonia-containing tail gas is 3.0MPaG, and the aniline is decompressed to 0.5MPaG and then returned to the N,N-diphenylurea production process;

(4) the tertiary separation ammonia-containing tail gas obtained in step (3) adopts the ammonia separation tower 8 to carry out packing separation, the packing in the ammonia separation tower 8 is a Pall ring, the pressure of the packing separation is 3.0 MPaG, and the temperature is At 70°C, the ammonia-containing tail gas is separated for three times and partially liquefied, and the unliquefied gas phase is separated from the top of the tower. The purified gas obtained is cooled to 50°C to obtain liquid ammonia product. The liquefied aniline is heated by the tower kettle for gas-liquid separation again, and the gas phase is returned to the ammonia separation tower. 8. The liquid phase aniline is decompressed to 0.5MPaG and then returned to the production process of N,N-diphenylurea.

In this embodiment, the device and method are used to purify and separate ammonia-containing tail gas. According to the content of ammonium bicarbonate in the remaining tail gas in step (2) and the recovery amount of aniline, the removal rate of ammonium bicarbonate reaches 99.92%, and the recovery rate of aniline reaches 99.94%. %, the purity of the liquid ammonia product can reach 99.93%, and the continuous and stable operation time of the device reaches 3100h.

Example 5:

The present embodiment provides a method for purifying and separating ammonia-containing tail gas in the production process of carbonylation intermediates. The method is carried out using the device in embodiment 2, and includes the following steps:

(1) gas-liquid separation of the ammonia-containing tail gas after condensation, the source of the ammonia-containing tail gas is the process of using urea and aniline as raw materials to produce N,N-diphenylurea, and the composition of the ammonia-containing tail gas includes 40wt% The ammonia gas, 57.5wt% aniline, and ammonium bicarbonate with a content of 90g/ ^m3 , the temperature of the ammonia-containing tail gas is 200 ° C, and the condensation includes primary condensation and secondary condensation. After the primary condensation, the temperature of the ammonia-containing tail gas drops. When the temperature reaches 100 °C, the temperature of the ammonia-containing tail gas drops to 70 °C after the secondary condensation. After gas-liquid separation, the condensed aniline accounts for 92% of the total aniline, which is returned to the production process of N,N-diphenylurea, and a primary separation is obtained. Ammonia-containing tail gas;

(2) the one-time separation ammonia-containing tail gas obtained in step (1) enters the ammonium bicarbonate trap 4 to carry out ammonium bicarbonate trapping, the one-time separation ammonia-containing tail gas continues to be cooled to 35 ° C, and the ammonium bicarbonate is separated out in the ammonium bicarbonate trap 4 On the U-shaped pipe 41, and obtain secondary separation ammonia-containing tail gas; the ammonium bicarbonate product is sprayed and washed with 80 ℃ hot water, and the precipitated ammonium bicarbonate is dissolved and removed, and the removal time is 0.3h;

(3) the secondary separation ammonia-containing tail gas obtained in step (2) is compressed, the pressure before the compression is 0.2MPaG, and the temperature of the secondary separation ammonia-containing tail gas after the compression is increased, and the gas-liquid separation after cooling is performed again, Obtain three separations of ammonia-containing tail gas and liquid-phase aniline, and the pressure of three-time separation of ammonia-containing tail gas is 3.2 MPaG, and the aniline is decompressed to 0.1 MPaG and then returned to the N,N-diphenylurea production process;

(4) the tertiary separation ammonia-containing tail gas obtained in step (3) adopts the ammonia separation tower 8 to carry out packing separation, the packing in the ammonia separation tower 8 is a wire mesh corrugated packing, and the pressure of the packing separation is 3.2 MPaG, and the temperature is 3.2 MPaG. The temperature is 60°C, the ammonia-containing tail gas is separated for three times and partially liquefied, the unliquefied gas phase is separated from the top of the tower, the purified gas obtained is cooled to 60°C to obtain liquid ammonia product, the liquefied aniline is heated by the tower kettle for gas-liquid separation again, and the gas phase is returned to ammonia separation In column 8, the liquid phase aniline is decompressed to 0.1MPaG and returned to the N,N-diphenylurea production process.

In this embodiment, the device and method are used to purify and separate ammonia-containing tail gas. According to the content of ammonium bicarbonate in the remaining tail gas in step (2) and the recovery amount of aniline, the removal rate of ammonium bicarbonate reaches 99.9%, and the recovery rate of aniline reaches 99.91%. %, the purity of the liquid ammonia product can reach 99.92%, and the continuous and stable operation time of the device reaches 3200h.

Comparative Example 1:

This comparative example provides a device and method for the purification and separation of ammonia-containing tail gas in the production process of carbonylation intermediates. The device refers to the device in Example 1, and the only difference is that the ammonium bicarbonate trap 4 is replaced with a conventional one. Shell and tube heat exchanger.

The method refers to the method in Example 3, and the difference is only that: in step (2), a shell-and-tube heat exchanger is used to separate the ammonia-containing tail gas for heat exchange and cooling, and ammonium bicarbonate is precipitated.

In this comparative example, since ammonium bicarbonate is not provided with an ammonium bicarbonate trap, ammonium bicarbonate is precipitated in the conventional heat exchanger, which is likely to cause accumulation and blockage inside the heat exchanger, and it is difficult to carry out leaching directly. It runs stably over time, and with the passage of time, the heat exchange effect decreases, and it is difficult to achieve sufficient separation of ammonium bicarbonate, which affects the subsequent separation process.

Combining the above examples and comparative examples, it can be seen that the device of the present invention passes through the setting of the ammonium bicarbonate capture unit and the multi-stage separation unit, first passes through the gas-liquid separation unit, and condenses and separates most of the organic components, and then passes through the gas-liquid separation unit. The structural design of the ammonium bicarbonate trap separates out ammonium bicarbonate, and the remaining ammonia-containing gas is further separated from the organic matter by means of compression separation and tower separation, which realizes effective purification of carbonylation intermediate synthesis tail gas and ammonia and ammonium bicarbonate. And the efficient recovery of organic components, the removal rate of ammonium bicarbonate reaches more than 99.5%, the recovery rate of organic components reaches more than 99.9%, and the purity of liquid ammonia products reaches more than 99.9%; the device can effectively solve the problem that ammonium bicarbonate easily causes pipelines. The problem of clogging, the continuous and stable operation can reach more than 3000h, the equipment cost is low, and the production efficiency is high.

The present invention illustrates the detailed apparatus and method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed apparatus and method, that is, it does not mean that the present invention must rely on the above-mentioned detailed apparatus and method to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the device of the present invention, the addition of auxiliary devices, the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims (10)

1. The device for purifying and separating the tail gas containing ammonia in the production process of the carbonylation intermediate is characterized by sequentially comprising a gas-liquid separation unit, an ammonium bicarbonate collecting unit, a compression separation unit and an ammonia separation unit; the gas-liquid separation unit comprises a condenser and a first gas-liquid separator, the ammonium bicarbonate trapping unit comprises an ammonium bicarbonate trap, the compression separation unit comprises a compressor and a second gas-liquid separator, the ammonia separation unit comprises an ammonia separation tower and a third gas-liquid separator, and liquid phase outlets of the first gas-liquid separator, the second gas-liquid separator and the third gas-liquid separator are connected to the same pipeline for recycling.

2. The device according to claim 1, wherein the ammonia-containing tail gas is from a carbonylation intermediate synthesis unit, preferably an N, N-diphenylurea synthesis unit;

preferably, the condenser comprises a first condenser and a second condenser, wherein a gas phase outlet of the first condenser is connected to the second condenser, and a liquid phase outlet of the first condenser is connected to the carbonylation intermediate synthesis unit;

preferably, the first condenser is a vertical condenser, the second condenser is a horizontal condenser, both the first condenser and the second condenser are shell-and-tube heat exchangers, and the ammonia-containing gas passes through a tube pass;

preferably, the first gas-liquid separator is a vertical tank, an outlet at the top of the first gas-liquid separator is connected with an inlet of the ammonium bicarbonate catcher, and an outlet at the bottom of the first gas-liquid separator is connected with the carbonylation intermediate synthesis unit.

3. The device according to claim 1 or 2, wherein the ammonium bicarbonate catcher is a vertical heat exchanger, a U-shaped pipe is arranged in the ammonium bicarbonate catcher and serves as a pipe pass, and a heat exchange medium passes through the pipe pass;

preferably, a partition plate is arranged in the middle of the ammonium bicarbonate catcher along the longitudinal direction and extends to the bottom of the U-shaped pipe;

preferably, the upper parts of the side surfaces of the ammonium bicarbonate catcher on the two sides of the partition plate are respectively provided with an ammonia-containing gas inlet and an ammonia-containing gas outlet;

preferably, a baffle plate is arranged in a shell layer of the ammonium bicarbonate catcher, and the baffle plate is horizontally arranged or inclined downwards;

preferably, an interlayer is arranged at the bottom of an upper end socket tube plate of the ammonium bicarbonate trap, a spraying heat medium inlet is arranged on the side surface of the interlayer, and a spraying port is arranged at the bottom of the interlayer;

preferably, the number of the ammonium bicarbonate catcher is at least one, and when the number of the ammonium bicarbonate catchers is more than two, the ammonium bicarbonate catchers are arranged in parallel and run alternately.

4. The apparatus of any one of claims 1-3, wherein the compressor comprises a screw-type compressor;

preferably, the compression separation unit further comprises a cooler disposed between the compressor and the second gas-liquid separator;

preferably, the cooler and the second gas-liquid separator are both vertical tanks, and the compressed ammonia-containing gas passes through the shell side of the cooler;

preferably, the liquid phase outlet of the second gas-liquid separator is connected to a carbonylation intermediate synthesis unit.

5. The apparatus of any one of claims 1-4, wherein the ammonia separation column comprises a packed column, the packing comprising pall rings and/or wire mesh corrugated packing;

preferably, the top outlet of the ammonia separation tower is also connected with a tower top condenser, the bottom outlet of the ammonia separation tower is also connected with a tower kettle reboiler, and both the tower top condenser and the tower kettle reboiler are vertical heat exchangers;

preferably, the overhead condenser obtains a liquid ammonia product, and the liquid ammonia product enters a liquid ammonia storage tank;

preferably, the third gas-liquid separator is a vertical tank, an outlet at the top of the third gas-liquid separator is connected with an inlet at the lower part of the ammonia separation tower, and an outlet at the bottom of the third gas-liquid separator is connected with the carbonylation intermediate synthesis unit;

preferably, the first gas-liquid separator, the second gas-liquid separator and the third gas-liquid separator are connected to a confluence pipeline of the carbonylation intermediate synthesis unit, and a circulation pump is arranged on the confluence pipeline.

6. A method for purifying and separating ammonia-containing tail gas in the production process of an oxo intermediate by using the device of any one of claims 1 to 5, which is characterized by comprising the following steps:

(1) condensing the ammonia-containing tail gas, and then carrying out gas-liquid separation to obtain primary separated ammonia-containing tail gas and liquid-phase organic matters;

(2) carrying out ammonium carbonate capture on the primary separated ammonia-containing tail gas obtained in the step (1) to obtain secondary separated ammonia-containing tail gas and an ammonium carbonate product, wherein the ammonium carbonate product is removed by thermal spraying;

(3) compressing and gas-liquid separating the secondary separated ammonia-containing tail gas obtained in the step (2) to obtain tertiary separated ammonia-containing tail gas and liquid-phase organic matters;

(4) and (4) carrying out filler separation and gas-liquid separation on the tertiary ammonia-containing tail gas obtained in the step (3) to obtain purified gas and liquid-phase organic matter, and cooling the purified gas to obtain a liquid ammonia product.

7. The method according to claim 6, wherein the source of the ammonia-containing tail gas in step (1) comprises a carbonylation intermediate production process, preferably a process for producing N, N-diphenylurea by using urea and aniline as raw materials;

preferably, the composition of the ammonia-containing tail gas in the step (1) comprises ammonia gas, ammonium bicarbonate, aniline, carbon dioxide and N-methylaniline;

preferably, the temperature of the ammonia-containing tail gas in the step (1) is 200-240 ℃;

preferably, the condensing of step (1) comprises a primary condensing and a secondary condensing;

preferably, the temperature of the ammonia-containing tail gas after primary condensation is reduced to 100-140 ℃, and the condensed liquid phase organic matter is returned to the production process of the carbonylation intermediate;

preferably, the temperature of the ammonia-containing tail gas after secondary condensation is reduced to 60-80 ℃, liquid phase organic matters are continuously condensed, and the liquid phase organic matters are returned to the production process of the carbonylation intermediate after gas-liquid separation;

preferably, after the condensation and the gas-liquid separation in the step (1), the separated liquid-phase organic matters account for 90-95% of the total amount of the liquid-phase organic matters.

8. The method according to claim 6 or 7, wherein the ammonium bicarbonate capture of step (2) is performed in an ammonium bicarbonate trap;

preferably, during ammonium bicarbonate capture, the primary separated ammonia-containing tail gas is continuously cooled to below 40 ℃, and ammonium bicarbonate is precipitated on a U-shaped pipe in the ammonium bicarbonate trap;

preferably, when the number of the ammonium bicarbonate traps comprises more than two, the ammonium bicarbonate traps alternately operate;

preferably, the thermal spraying in the step (2) is to perform spray rinsing by adopting a thermal medium to dissolve and remove precipitated ammonium bicarbonate;

preferably, the heat medium comprises steam or hot water, and the removal time is not more than 0.5 h.

9. The method according to any one of claims 6 to 8, wherein the pressure of the secondary separation ammonia-containing tail gas in the step (3) is 0.05 to 0.2 MPaG;

preferably, the temperature of the ammonia-containing tail gas subjected to secondary separation after compression is increased, and gas-liquid separation is performed after cooling is performed again;

preferably, after the gas-liquid separation in the step (3), the liquid phase organic matter returns to the production process of the carbonylation intermediate;

preferably, the pressure of the ammonia-containing tail gas subjected to the third separation after the gas-liquid separation in the step (3) is 2.6-3.2 MPaG.

10. The process of any one of claims 6-9, wherein the packing separation of step (4) is performed in an ammonia separation column;

preferably, the packing in the ammonia separation column comprises pall rings and/or wire mesh corrugated packing;

preferably, the pressure for separating the filler in the step (4) is 2.6-3.2 MPaG, and the temperature is 60-70 ℃;

preferably, when the filler is separated in the step (4), the ammonia-containing tail gas separated for the third time is partially liquefied, the unliquefied gas phase leaves from the top of the tower, and the liquefied organic matter is heated in the tower kettle to be subjected to gas-liquid separation again;

preferably, the purified gas in the step (4) is cooled to 40-60 ℃ to obtain a liquid ammonia product;

preferably, after the gas-liquid separation in the step (4), the gas phase returns to the ammonia separation tower, and the liquid phase organic matter returns to the production process of the carbonylation intermediate;

preferably, the liquid phase organic matters separated in the steps (3) and (4) are decompressed to 0-0.5 MPaG, mixed with the liquid phase organic matters separated in the step (1), and conveyed to the carbonylation intermediate synthesis unit.

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