CN218146433U - Energy-saving process device for acrylic acid refining process - Google Patents
Energy-saving process device for acrylic acid refining process Download PDFInfo
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- CN218146433U CN218146433U CN202222706343.2U CN202222706343U CN218146433U CN 218146433 U CN218146433 U CN 218146433U CN 202222706343 U CN202222706343 U CN 202222706343U CN 218146433 U CN218146433 U CN 218146433U
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Abstract
The utility model provides an energy-conserving process units for acrylic acid refining process, the device mainly include in the middle of taking off the light tower reboiler and with absorption tower, absorption tower circulative cooling ware, take off the light tower, take off the connecting line between the acetic acid tower three towers. The utility model overcomes prior art's defect, applicable propylene oxidation reaction gas raw materials in different concentration has extremely apparent energy-conserving effect, accords with energy-conserving, the carbon reduction trend at present, has wide application prospect.
Description
Technical Field
The utility model relates to an energy-conserving process units for acrylic acid refining process can be used to obtain the process of crude acrylic acid product through continuous absorption, dehydration, acetic acid removal in following propylene oxidation reaction gas. The utility model discloses both can save heating steam, can save recirculated cooling water again, greatly reduced the operation energy consumption.
Background
Acrylic acid is an unsaturated fatty acid, is an important industrial derivative of propylene, and is also one of important organic chemical raw materials. Acrylic acid contains active double bonds and carboxyl functional groups, is particularly suitable for preparing high water absorption materials, dispersants, flocculants, thickeners and the like, and is widely applied to the fields of chemical fibers, textiles, coatings, water treatment, daily necessities and the like.
In the existing acrylic acid production process, a propylene gas phase oxidation method is widely used, which takes propylene and air as raw materials, and carries out oxidation reaction through a fixed bed catalyst bed layer in the presence of water vapor and other inert gases, the reaction is divided into two steps, wherein in the first step, the propylene is oxidized into acrolein, in the second step, the acrolein is oxidized into acrylic acid, an acrylic acid gas phase mixture is obtained at the outlet of a reactor, the acrylic acid gas phase mixture mainly comprises acrylic acid gas, nitrogen, aldehyde compounds, carboxylic acid compounds, carbon dioxide, carbon monoxide, oxygen and the like, and the acrylic acid gas phase mixture is subjected to a refining separation system to obtain an acrylic acid product.
At present, the commonly used processes for the gas-phase separation of acrylic acid mainly comprise three different technical routes: organic solvent absorption rectification technology, water absorption azeotropic rectification technology and water absorption extraction rectification technology. The organic solvent absorption rectification technology has the advantages of short flow and relatively low energy consumption; the defects that the acrylic acid needs to be absorbed by using a solvent, the operation temperature is high, the acrylic acid is easy to polymerize, and the operation period is short; the water absorption azeotropic distillation technology has the advantages of shorter flow, low investment cost and the defects of higher energy consumption and high operation cost because an azeotropic agent is required to be used; the water absorption extraction rectification technology has the advantages of low energy consumption and low operating cost; the disadvantages of longer process, high investment cost, use of extractant and high consumption of polymerization inhibitor.
Chinese patent CN1903738A provides an acrylic acid wastewater treatment process which is suitable for acrylic acid wastewater discharged by an acrylic acid device. The acrylic acid wastewater treatment adopts reverse osmosis membrane separation and rectification processes, the acrylic acid wastewater is subjected to membrane separation, purified water on a permeation side is discharged from a battery compartment, organic matters on a residual permeation side are sent into a rectification tower, acrylic acid and toluene are separated from acetic acid and water, and the acrylic acid, the toluene and the acetic acid are respectively recovered. The acrylic acid and the methylbenzene separated by the process method also need to enter a light component tower of an acrylic acid device to recover the acrylic acid and the methylbenzene, the acetic acid and the water obtained by separation also need to enter an acetic acid recovery system to recover the acetic acid, and products with higher concentration cannot be obtained; the operating pressure of the reverse osmosis membrane is high (1 to 10 MPa), the service life of the reverse osmosis membrane is limited, and the reverse osmosis membrane needs to be frequently replaced, so that the operating cost of the process method is high.
CN1865216A provides a process for azeotropic refining and recovering acetic acid from acrylic acid, which adopts ethyl cyclohexane and toluene, ethyl propionate and toluene as entrainer in acrylic acid azeotropic distillation, is provided with an acrylic acid azeotropic tower and an acetic acid removing tower to remove water and acetic acid in crude acrylic acid solution, is additionally provided with an organic membrane, a stripping tower and an acetic acid azeotropic tower to concentrate by-product acetic acid with the concentration of 2~8% (except special instructions, the mass percentage is referred to in the specification) to the concentration of more than or equal to 85%. Although the process method has higher dehydration rate and acetic acid removal rate, the azeotropic distillation energy consumption is higher, and the entrainer is a mixture of various materials, namely more components to be separated are introduced into the system, so that the separation difficulty is improved, and the separation energy consumption is increased; and the organic membrane is a three-stage reverse osmosis membrane, so that the equipment cost is high, the service life is limited, the organic membrane needs to be replaced periodically, and the equipment cost and the operation cost are increased.
CN102775295A discloses a method for purifying acrylic acid, which comprises two tower process flows of an absorption tower and a purification tower, wherein acrylic acid is recovered and refined by coupling the processes of cooling, absorption and purification of acrylic acid and using a device consisting of the two towers, and meanwhile, water is recycled as an absorbent and a coolant, and other solvents (an extraction agent and an entrainer) are not used, so that the pollution of the solvent to the environment is avoided. The method has relatively simple flow, and reduces the equipment investment cost and the running cost, but because the acetic acid aqueous solution at the top of the absorption tower is adopted as the absorbent in the method, the content of acrylic acid in the tail gas at the top of the tower is higher (about 0.3wt percent), the unit consumption of propylene is increased, and the production cost is increased more; meanwhile, because the device is not provided with a liquid phase extraction of acetic acid aqueous solution, the content of acrylic acid in the tail gas at the top of the tower is reduced, and the content of acetic acid in the tower kettle of the absorption tower is increased, so that the quality of an acrylic acid product extracted by the purification tower is influenced.
CN109232232A discloses a method for refining acrylic acid, which carries out quenching absorption of high-concentration gas, reabsorption of low-concentration gas, purification, extraction and stripping of acrylic acid process gas, couples the cooling process, the absorption process and the purification process of acrylic acid gas-phase mixture, carries out subsequent acid water treatment, improves the absorption process and does not use an entrainer in the refining process. The method has relatively simple flow and reduced operation cost, but because the desalted water needs to be added from the top of the lightness-removing column in the reabsorption process of the method, the desalted water is consumed, and the amount of acid water discharged from the system is increased; and the middle upper part of the light component removal tower is not provided with liquid phase extraction of acetic acid aqueous solution, which can also cause the increase of the acetic acid content in the tower kettle of the absorption tower, thereby influencing the quality of acrylic acid products extracted by the purification tower.
The technical methods provided by CN102775295A and CN109232232A have a common problem, and are forced to improve the temperature of tail gas to be incinerated in order to reduce the content of acetic acid in the system and meet the quality of acrylic acid products, so that a small amount of acrylic acid is removed from the tail gas incineration system along with the tail gas and the acetic acid, the material consumption of the device is increased, and the yield is reduced.
FIG. 1 is a process flow diagram of a three-tower (absorption tower T110, light component removal tower T120, and acetic acid removal tower T130) conventional process method for obtaining crude acrylic acid products by quenching absorption, azeotropic distillation, conventional distillation and acetic acid removal of raw material reaction gas, which are commonly adopted at present. The commonly adopted conventional three-tower process is relatively simple, has higher dehydration rate, but has higher energy consumption for azeotropic distillation.
Disclosure of Invention
The utility model aims at providing an energy-conserving process units for acrylic acid refining process can be used to obtain the process of crude acrylic acid product through continuous absorption, dehydration, acetic acid removal in following propylene oxidation reaction gas. The utility model discloses both can save heating steam, can save recirculated cooling water again, greatly reduced the operation energy consumption. The utility model overcomes prior art's defect, applicable propylene oxidation reaction gas raw materials in different concentration has extremely apparent energy-conserving effect, accords with energy-conserving, the carbon reduction trend at present, has wide application prospect.
The utility model provides an energy-saving process method for acrylic acid refining process, which obtains the process of crude acrylic acid products through continuous absorption, dehydration and acetic acid removal from propylene oxidation reaction gas. The heat brought by the circulating liquid in the bottom of the absorption tower T110 can be transferred to the lightness-removing tower T120 through the middle reboiler E1202 of the lightness-removing tower, and the method mainly comprises the following steps:
1) Leading out a high-temperature liquid phase from the bottom of an absorption tower T110, namely, leading a circulating liquid 6 into a hot side of a light component removal tower intermediate reboiler E1202 for cooling and providing a part of heat for a light component removal tower T120, leading a cooled circulating liquid 7 into an absorption tower circulating cooler E1101 for cooling, and returning a cooled circulating liquid 8 to the lower part of the absorption tower T110 to absorb acrylic acid in the reaction gas 1;
2) Liquid phase material 16 is extracted from the middle side of the light component removal tower T120 and enters the cold side of an intermediate reboiler E1202 of the light component removal tower, and heated material 17 returns to the light component removal tower T120;
3) The liquid phase material 22 from the top of the acetic acid removal tower T130 to the light component removal tower T120 enters the cold side inlet of the intermediate reboiler E1202 of the light component removal tower.
The process method provided by the utility model comprises the following steps:
1) The raw material reaction gas 1 enters the bottom of an absorption tower T110, and the fresh process water 2 enters the top of the absorption tower T110;
2) Tail gas 3 is discharged from the top of the absorption tower T110; the energy is saved, namely, the absorption tower T110 and the light component removal tower T120 are subjected to heat integration operation, a tower kettle liquid phase 4 of the absorption tower T110 is divided into two parts, a first part 5 enters a cold side of an intermediate reboiler E1202 of the light component removal tower, a second part 6 is circulating liquid and enters a hot side of the intermediate reboiler E1202 of the light component removal tower for cooling, the cooled circulating liquid 7 enters an absorption tower circulating cooler E1101 for cooling, and a cooled circulating liquid 8 returns to the lower part of the absorption tower T110;
3) The gas phase 9 at the top of the lightness-removing column T120 enters a lightness-removing column condenser E1203 for condensation, the cooled non-condensable gas 10 is connected with a vacuum system, the condensate 11 of the lightness-removing column condenser E1203 enters a lightness-removing column phase-splitting tank V1201 for phase splitting, the phase-split oil phase is taken as the reflux liquid 12 of the lightness-removing column T120 and directly returns to the top of the lightness-removing column T120, the phase-split water phase 13 is divided into two strands, the first strand is taken as the recycling absorption water 14 and enters the upper part of the absorption column T110, and the second strand is taken as the discharged wastewater 15 and is sent out of the device; a liquid phase material 16 extracted from the side line in the lightness-removing column T120 enters the cold side of an intermediate reboiler E1202 of the lightness-removing column after being boosted by a circulating pump, and a heated liquid phase material 17 returns to the position above the side line extraction of the lightness-removing column T120; the material 18 at the bottom of the light component removal tower T120 enters a acetic acid removal tower T130;
4) The gas phase 19 at the top of the acetic acid removing tower T130 enters a acetic acid removing tower condenser E1302 for condensation, the cooled non-condensable gas is connected with a vacuum system, the condensate 20 of the acetic acid removing tower condenser E1302 is divided into two parts, the first part is used as the reflux liquid 21 of the acetic acid removing tower T130 and directly returns to the top of the acetic acid removing tower T130, and the second part 22 enters the cold side 1202 of a middle reboiler E of a light-weight removing tower; the liquid phase material extracted from the tower bottom of the acetic acid removing tower T130 is taken as a crude acrylic acid product 23 and sent out of the device.
According to the utility model provides a process, reboiler E1202 and absorption tower circulative cooling ware E1101 can series operation in the middle of taking off the light tower, also can parallel operation.
According to the process provided by the utility model, the liquid phase material from the tower kettle of the absorption tower T110 to the lightness-removing tower T120 can directly enter the cold side inlet of the middle reboiler E1202 of the lightness-removing tower without being cooled by the middle reboiler E1202 of the lightness-removing tower; or directly enters the lightness-removing tower T120 without being cooled by an intermediate reboiler E1202 of the lightness-removing tower; or cooled by an intermediate reboiler E1202 of the light component removal tower and then enters the light component removal tower T120; the cooling liquid can also enter the cold side inlet of the intermediate reboiler E1202 of the light component removal tower after being cooled by the intermediate reboiler E1202 of the light component removal tower.
According to the utility model provides a process, take off reboiler E1202 cold side in the middle of the light tower and can adopt full liquid phase circulation type, the cold side also can adopt the type of cold side material part vaporization.
According to the utility model provides a process, the liquid phase material that takes off light tower T120 is arrived at the top of the tower of acetic acid removal tower T130, also can directly get into and take off light tower T120 not through taking off light tower middle reboiler E1202 heating.
According to the process method provided by the utility model, the adopted energy-saving method is selected as follows: the steam condensate can be used for preheating the feeding materials of the acetic acid removal tower T130 and the light component removal tower T120 sequentially or respectively.
Steam condensate can preheat for arbitrary tower or their permutation and combination in the system, above-mentioned various heat transfer mode and combination are just right the utility model provides a supply of an energy-conserving processing method for acrylic acid refining process, rather than right the utility model discloses any of spirit is injectd, personnel in the relevant field can be completely according to the utility model provides a method suitably changes or change and make up, realizes this technique. It is expressly stated that all such modifications or variations and rearrangements of the process flow provided by the present invention as would be obvious to one skilled in the art are deemed to be within the spirit, scope and content of the invention.
According to the utility model provides a process, take off light tower reboiler E1201, take off the used heat source of acetic acid tower reboiler E1301 can be live steam, conduction oil, perhaps the inside material steam that produces of system.
According to the process provided by the utility model, the absorption tower circulating cooler E1101, the lightness-removing tower condenser E1203 and the acetic acid removing tower condenser E1302 can be air coolers or water coolers; the cooling medium can be circulating water, low-temperature water, chilled water, or other cooling media such as low-temperature materials in the system.
According to the utility model provides a process, for reducing the noncondensable gas and bring the material loss that vacuum system caused into, lightness-removing tower condenser E1203, acetic acid removal tower condenser E1302 after can set up lightness-removing tower tail cooler E1204 and acetic acid removal tower tail cooler E1303 again, used coolant can be low-temperature water, refrigerated water, perhaps other cryogenic medium such as the inside low temperature material of system.
According to the utility model provides a process method, its characterized in that: typical operating conditions for each column are:
the operating pressure range of the top of the absorption tower (T110) is 50-350 kPa;
the operation pressure range of the top of the light component removal tower (T120) is 5-120 kPa;
the operation pressure range of the tower top of the acetic acid removing tower (T130) is 2-80 kPa.
The preferred operating conditions for each column are:
the operation pressure at the top of the absorption tower (T110) is 90-180 kpa, the operation temperature at the top of the absorption tower is 58-70 ℃, and the operation temperature at the bottom of the absorption tower is 68-79 ℃;
the operating pressure at the top of the light component removal tower (T120) is 8-18 kPa, the operating temperature at the top of the tower is 32-48 ℃, the operating temperature in the tower is 33-58 ℃, and the operating temperature at the bottom of the tower is 72-89 ℃;
the operation pressure at the top of the acetic acid removing tower (T130) is 3-10 kpa, the operation temperature at the top of the tower is 48-75 ℃, and the operation temperature at the bottom of the tower is 70-89 ℃.
According to the utility model provides a process, the position of drawing of lightness-removing column T120 side circulation liquid 16 and the position of returning to recycle liquid 17 also can be located the below of lightness-removing column T120 feeding 5 feed inlet.
According to the utility model provides a pair of energy-conserving process units for acrylic acid refining process, mainly include in the middle of the tower reboiler E1202 and with absorption tower T110, absorption tower circulative cooling ware E1101, take off light tower T120, take off the connecting line between the three towers of acetic acid tower T130.
The bottom of the absorption tower T110 is respectively connected with a hot side inlet of an intermediate reboiler E1202 of the light component removal tower and a cold side inlet of the intermediate reboiler E1202 of the light component removal tower; and a hot side outlet of the light component removal tower intermediate reboiler E1202 is connected with a hot side inlet of an absorption tower circulation cooler E1101, and the hot side outlet of the absorption tower circulation cooler E1101 is connected to the lower part of the absorption tower T110.
A side draw outlet at the middle part of the lightness-removing column T120 is connected with a cold side inlet of a middle reboiler E1202 of the lightness-removing column, and a cold side outlet of the middle reboiler E1202 of the lightness-removing column is connected with the lightness-removing column T120.
The discharging pipeline at the top of the acetic acid removal tower T130 is connected with the cold side inlet of the light component removal tower intermediate reboiler E1202.
In order to highlight the utility model provides an energy-saving process method for the acrylic acid refining process, which omits part of heat exchangers in the process.
According to the utility model provides a process, the technical personnel of relevant professional field can implement the inside commodity circulation heat transfer method of suitable system completely according to concrete device condition, and the various evolution process flows that form from this all should be regarded as in the spirit, scope and the content of the utility model discloses. The heat exchanger in the flow diagram is only an illustration, and the specific structure thereof does not form any limitation to the present invention.
The utility model provides an energy-conserving process units and various deformation process methods for acrylic acid refining process can be used to obtain the process of crude acrylic acid product through continuous absorption, dehydration, acetic acid removal in following propylene oxidation reaction gas. The utility model can save heating steam and circulating cooling water, and greatly reduce energy consumption. The utility model overcomes prior art's defect, applicable propylene oxidation reaction gas raw materials in different concentration has extremely apparent energy-conserving effect, accords with present energy-conservation, subtracts the carbon trend, has wide application prospect.
Drawings
FIG. 1 is a process flow diagram of a three-tower (absorption tower T110, light component removal tower T120, and acetic acid removal tower T130) conventional process method for obtaining crude acrylic acid products by quenching absorption, azeotropic distillation, conventional distillation and acetic acid removal of raw material reaction gas, which are commonly adopted at present.
FIG. 2 is a process flow diagram of an exemplary energy-saving process for an acrylic acid refining process provided by the present invention.
Fig. 3 is a process variation of fig. 2, namely a process variation one, and relative to the flow scheme provided in fig. 2, the light ends removal column inter-reboiler E1202 and the absorber column recycle cooler E1101 may also be operated in parallel. The circulating liquid at the bottom of the absorption tower T110 is divided into two parts 6 and 24, and the two parts are respectively cooled by a light component removal tower intermediate reboiler E1202 and an absorption tower circulating cooler E1101 to obtain cold circulating liquids 7 and 25, and the mixed cold circulating liquid 8 returns to the lower part of the absorption tower T110.
Fig. 4 is a modified process method, namely a modified process method two, of fig. 2, and with respect to the flow provided by fig. 2, the liquid-phase material 5 from the bottom of the absorption column T110 to the lightness-removing column T120 may enter the lightness-removing column T120 directly without being cooled by an intermediate reboiler E1202 of the lightness-removing column.
Fig. 5 is a modified process method, namely a modified process method three, of fig. 2, and with respect to the flow provided in fig. 2, the cold side of the intermediate reboiler E1202 of the light component removal column may also be in a form of partial vaporization of the material on the cold side, the liquid material 16 taken from the middle side of the intermediate reboiler E1202 of the light component removal column T120 automatically flows into the cold side of the intermediate reboiler E1202 of the light component removal column, and the heated material 17 is in a gas-liquid two-phase state and returns to the light component removal column T120.
Fig. 6 is a modified process method, namely modified process method four, of fig. 2, and with respect to the flow path provided in fig. 2, the liquid-phase material 22 from the top of the acetic acid removing column T130 to the light component removing column T120 may also directly enter the light component removing column T120 without being heated by the light component removing column intermediate reboiler E1202.
Fig. 7 shows a further development of the process according to fig. 4, namely a variant process five, in which the withdrawal point for the side circulation 16 and the return point for the return circulation 17 of the lightness-removing column T120 can also be located below the feed opening for the feed 5 of the lightness-removing column T120, in relation to the flow scheme provided in fig. 4.
Detailed Description
The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, which are provided for illustration purposes and are not intended to limit the invention.
Unless otherwise specified, the composition, structure, materials (connecting lines for connecting the tower members, etc.), reagents, etc. of the process equipment such as the tower members, etc. not specifically used in the examples are commercially available or known to those skilled in the art. The specific experimental procedures and operating conditions involved are generally in accordance with conventional process conditions and conditions as described in the manual or as recommended by the manufacturer.
FIG. 1 is a process flow diagram of a three-tower (absorption tower T110, light component removal tower T120, and acetic acid removal tower T130) conventional process method for obtaining crude acrylic acid products by quenching absorption, azeotropic distillation, conventional distillation and acetic acid removal of raw material reaction gas, which are commonly adopted at present.
The raw reaction gas enters the bottom of the absorption tower T110, and fresh process water enters the top of the absorption tower T110.
Tail gas is discharged from the top of the absorption tower T110; the liquid phase at the bottom of the absorption tower T110 is divided into two streams, the first stream enters a light component removal tower T120, and the second stream is circulating liquid which returns to the lower part of the absorption tower T110 after being cooled by a circulating cooler of the absorption tower.
Condensing the condensed liquid of the gas phase at the top of the lightness-removing column T120, carrying out phase splitting on the oil phase subjected to phase splitting, refluxing to the top of the lightness-removing column T120, dividing the water phase subjected to phase splitting into two streams, feeding the first stream serving as recycled absorption water into the upper part of the absorption column T110, and feeding the second stream serving as discharged wastewater out of the device; the material in the bottom of the light component removal tower T120 enters a acetic acid removal tower T130.
The condensed liquid of the gas phase at the top of the acetic acid removing tower T130 after condensation is divided into two streams, the first stream reflows to the top of the acetic acid removing tower T130, and the second stream enters a light component removing tower T120; a crude acrylic acid product taken out from the tower bottom of the acetic acid removing tower T130.
The commonly adopted conventional three-tower process is relatively simple, has higher dehydration rate, but has higher energy consumption for azeotropic distillation.
The utility model provides a concrete application example of an energy-saving process device for an acrylic acid refining process, which comprises the following steps.
Example 1:
as shown in fig. 2, the energy-saving process apparatus for acrylic acid refining process provided by the present invention mainly comprises a middle reboiler E1202 of the light component removal tower and the connecting pipelines between the middle reboiler E1202 and the three towers, i.e. the absorption tower T110, the absorption tower recycle cooler E1101, the light component removal tower T120 and the acetic acid removal tower T130. The bottom of the absorption tower T110 is respectively connected with a hot side inlet of an intermediate reboiler E1202 of the light component removal tower and a cold side inlet of the intermediate reboiler E1202 of the light component removal tower; and a hot side outlet of the light component removal tower intermediate reboiler E1202 is connected with a hot side inlet of an absorption tower circulation cooler E1101, and the hot side outlet of the absorption tower circulation cooler E1101 is connected to the lower part of the absorption tower T110. A side draw outlet at the middle part of the lightness-removing column T120 is connected with a cold side inlet of a middle reboiler E1202 of the lightness-removing column, and a cold side outlet of the middle reboiler E1202 of the lightness-removing column is connected with the lightness-removing column T120. The discharging pipeline at the top of the acetic acid removal tower T130 is connected with the cold side inlet of the light component removal tower intermediate reboiler E1202.
The utility model can be used for the acrylic acid dehydration and the acetic acid dehydration process of propylene oxidation reaction gas raw materials with different concentrations. The specific process is described as follows:
as shown in FIG. 2, the raw reaction gas 1 is introduced into the bottom of the absorption column T110, and the fresh process water 2 is introduced into the top of the absorption column T110.
Tail gas 3 is discharged from the top of the absorption tower T110; the energy is saved, namely, the absorption tower T110 and the light component removal tower T120 are subjected to heat integration operation, a tower kettle liquid phase 4 of the absorption tower T110 is divided into two streams, the first stream 5 enters a cold side of a middle reboiler E1202 of the light component removal tower, the second stream 6 is circulating liquid and enters a hot side of the middle reboiler E1202 of the light component removal tower for cooling, the cooled circulating liquid 7 enters a circulating cooler E1101 of the absorption tower again for cooling, and the cooled circulating liquid 8 returns to the lower part of the absorption tower T110.
The gas phase 9 at the top of the lightness-removing column T120 enters a lightness-removing column condenser E1203 for condensation, the cooled non-condensable gas 10 is connected with a vacuum system, the condensate 11 of the lightness-removing column condenser E1203 enters a lightness-removing column phase-splitting tank V1201 for phase splitting, the phase-split oil phase is taken as the reflux liquid 12 of the lightness-removing column T120 and directly returns to the top of the lightness-removing column T120, the phase-split water phase 13 is divided into two strands, the first strand is taken as the recycling absorption water 14 and enters the upper part of the absorption column T110, and the second strand is taken as the discharged wastewater 15 and is sent out of the device; a liquid phase material 16 extracted from the side line in the light component removal tower T120 enters the cold side of an intermediate reboiler E1202 of the light component removal tower after being boosted by a circulating pump, and a heated liquid phase material 17 returns to the side line extraction position of the light component removal tower T120; the bottom material 18 of the light component removal tower T120 enters a acetic acid removal tower T130.
The gas phase 19 at the top of the acetic acid removing tower T130 enters a acetic acid removing tower condenser E1302 for condensation, the cooled non-condensable gas is connected with a vacuum system, the condensate 20 of the acetic acid removing tower condenser E1302 is divided into two parts, the first part is used as the reflux liquid 21 of the acetic acid removing tower T130 and directly returns to the top of the acetic acid removing tower T130, and the second part 22 enters the cold side 1202 of a middle reboiler E of a light-weight removing tower; the liquid phase material extracted from the tower bottom of the acetic acid removing tower T130 is taken as a crude acrylic acid product 23 and sent out of the device.
The heat sources used by the reboiler E1201 of the light component removal tower and the reboiler E1301 of the acetic acid removal tower can be fresh steam, heat conducting oil or material steam generated in the system.
The condensate of the fresh steam added into the system can be used for feeding and preheating the materials for each tower respectively or successively.
The absorption tower circulating cooler E1101, the lightness-removing tower condenser E1203 and the acetic acid removing tower condenser E1302 can be air coolers or water coolers; the cooling medium can be circulating water, low-temperature water, chilled water, or other cooling media such as low-temperature materials in the system.
Typical operating conditions for each column in example 1 are given below:
the operating pressure range of the top of the absorption tower (T110) is 50-350 kPa.
The operation pressure range of the top of the light component removal tower (T120) is 5-120 kPa.
The operation pressure range of the tower top of the acetic acid removing tower (T130) is 2-80 kPa.
The preferred operating conditions for each column in example 1 are given below:
the operation pressure at the top of the absorption tower (T110) is 90-180 kpa, the operation temperature at the top of the absorption tower is 58-70 ℃, and the operation temperature at the bottom of the absorption tower is 68-79 ℃.
The operating pressure at the top of the light component removal tower (T120) is 8-18 kPa, the operating temperature at the top of the tower is 32-48 ℃, the operating temperature in the tower is 33-58 ℃, and the operating temperature at the bottom of the tower is 72-89 ℃;
the operation pressure at the top of the acetic acid removing tower (T130) is 3-10 kpa, the operation temperature at the top of the tower is 48-75 ℃, and the operation temperature at the bottom of the tower is 70-89 ℃.
The heat exchange between the low-temperature material, namely the liquid-phase material 16 extracted from the side line in the tower of the lightness-removing tower T120, and the high-temperature material, namely the circulating liquid 6 led out from the tower bottom of the absorption tower T110, is completed in the middle reboiler E1202 of the lightness-removing tower, the heat brought out from the circulating liquid at the tower bottom of the absorption tower T110 is transferred to the lightness-removing tower T120 through the middle reboiler E1202 of the lightness-removing tower, and is used as a heating source in the tower T120 of the lightness-removing tower to provide a part of heat for the lightness-removing tower T120, so that the heating steam required by the lightness-removing tower T120 is saved, the circulating water required by the cooling of the circulating liquid at the tower bottom of the absorption tower T110 is saved, and the operation energy consumption is greatly reduced.
Taking 10 ten thousand tons of acrylic acid as an example, the light ends removal column T120 can save about 7 tons/hour of steam, and the operating cost can be reduced every year by the unit price of the steam of 200 yuan/ton:
200 yuan/ton × 7 ton/hour × 8000 hour/year/10000= 1120 ten thousand yuan/year.
Correspondingly, the absorption tower T110 can save about 440m of circulating water 3 Per hour, the unit price of circulating water is 0.6 yuan/m 3 The operation cost is reduced every year by calculation:
0.6 yuan/m 3 ×440m 3 Hour × 8000 hours/year/10000 =211 ten thousand yuan/year.
The total annual operating cost can be reduced: 1120+211=1331 ten thousand yuan per year.
Example 2:
as shown in fig. 3, which is an evolution process of fig. 2, the light ends removal column inter-reboiler E1202 and the absorber column recycle cooler E1101 can also be operated in parallel with respect to the flow scheme provided in fig. 2. The circulating liquid at the bottom of the absorption tower T110 is divided into two streams 6 and 24, and is cooled by a light component removal tower intermediate reboiler E1202 and an absorption tower circulating cooler E1101 respectively to obtain cold circulating liquids 7 and 25, and the mixed cold circulating liquid 8 returns to the lower part of the absorption tower T110.
Example 3:
as shown in fig. 4, which is an evolution process of fig. 2, compared to the flow scheme provided in fig. 2, the liquid phase material 5 from the bottom of the absorption column T110 to the lightness-removing column T120 can also directly enter the lightness-removing column T120 without being cooled by the middle reboiler E1202 of the lightness-removing column.
Example 4:
as shown in fig. 5, which is an evolution process of fig. 2, with respect to the flow provided in fig. 2, the cold side of the middle reboiler E1202 of the light ends removal column adopts a partial vaporization type, the liquid phase material 16 taken out from the middle side of the light ends removal column T120 automatically flows into the cold side of the middle reboiler E1202 of the light ends removal column, and the heated material 17 is partially vaporized to form a gas-liquid two phase, and returns to the light ends removal column T120.
Example 5:
as shown in fig. 6, which is an evolution process of fig. 2, compared to the flow scheme provided in fig. 2, the liquid phase material 22 from the top of the acetic acid removing column T130 to the light component removing column T120 can also enter the light component removing column T120 directly without being heated by the light component removing column intermediate reboiler E1202.
Example 6:
referring to fig. 7, which is an alternate process to that of fig. 4, the withdrawal point for the side recycle 16 and the return point for the return recycle 17 of the lightness-removing column T120 may be located below the feed inlet 5 of the lightness-removing column T120, as opposed to the flow scheme provided in fig. 4.
The utility model provides an energy-conserving process units for acrylic acid refining process can be used to obtain the process of crude acrylic acid product through continuous absorption, dehydration, acetic acid removal in the follow propylene oxidation reaction gas. The utility model discloses both can save heating steam, can save recirculated cooling water again, greatly reduced the operation energy consumption. The utility model overcomes prior art's defect, applicable propylene oxidation reaction gas raw materials in different concentration has extremely apparent energy-conserving effect, accords with present energy-conservation, subtracts the carbon trend, has wide application prospect.
The above embodiments are described in detail, and those skilled in the relevant art can implement the technology by making appropriate changes, modifications and combinations according to the method provided by the present invention. It is specifically noted that all of these processes, which are similar to the process flow provided by the present invention, or the modifications and re-combinations thereof, and implement suitable methods for heat exchange of the internal streams of the system, etc., will be obvious to those skilled in the art, and are considered to be within the spirit, scope and content of the present invention.
Claims (3)
1. An energy-saving process device for an acrylic acid refining process is characterized in that: the device mainly comprises a light component removal tower middle reboiler (E1202) and connecting pipelines between the light component removal tower middle reboiler and three towers, namely an absorption tower (T110), an absorption tower circulating cooler (E1101), a light component removal tower (T120) and a acetic acid removal tower (T130);
the bottom of the absorption tower (T110) is respectively connected with a hot side inlet of an intermediate reboiler (E1202) of the light component removal tower and a cold side inlet of the intermediate reboiler (E1202) of the light component removal tower; a hot side outlet of the intermediate reboiler (E1202) of the light component removal tower is connected with a hot side inlet of an absorption tower circulating cooler (E1101), and the hot side outlet of the absorption tower circulating cooler (E1101) is connected to the lower part of the absorption tower (T110);
a side draw outlet at the middle part of the light component removal tower (T120) is connected with a cold side inlet of an intermediate reboiler (E1202) of the light component removal tower, and a cold side outlet of the intermediate reboiler (E1202) of the light component removal tower is connected with the light component removal tower (T120);
the discharge pipeline at the top of the acetic acid removal tower (T130) is connected with the cold side inlet of an intermediate reboiler (E1202) of the light component removal tower.
2. The energy saving process apparatus according to claim 1, wherein: the intermediate reboiler (E1202) of the light component removal tower and the circulating cooler (E1101) of the absorption tower are operated in series or in parallel.
3. The energy-saving process apparatus according to claim 1, wherein: the operating conditions of each column were:
the operation pressure at the top of the absorption tower (T110) is 90-180 kpa, the operation temperature at the top of the absorption tower is 58-70 ℃, and the operation temperature at the bottom of the absorption tower is 68-79 ℃;
the operation pressure at the top of the light component removal tower (T120) is 8-18 kPa, the operation temperature at the top of the tower is 32-48 ℃, the operation temperature in the tower is 33-58 ℃, and the operation temperature at the bottom of the tower is 72-89 ℃;
the operation pressure at the top of the acetic acid removing tower (T130) is 3-10 kpa, the operation temperature at the top of the tower is 48-75 ℃, and the operation temperature at the bottom of the tower is 70-89 ℃.
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| CN202222706343.2U CN218146433U (en) | 2022-10-14 | 2022-10-14 | Energy-saving process device for acrylic acid refining process |
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| CN202222706343.2U CN218146433U (en) | 2022-10-14 | 2022-10-14 | Energy-saving process device for acrylic acid refining process |
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