CN115322067B - Separation method of light component mixture in 1, 4-butanediol production waste liquid - Google Patents
Separation method of light component mixture in 1, 4-butanediol production waste liquid Download PDFInfo
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- CN115322067B CN115322067B CN202210881132.4A CN202210881132A CN115322067B CN 115322067 B CN115322067 B CN 115322067B CN 202210881132 A CN202210881132 A CN 202210881132A CN 115322067 B CN115322067 B CN 115322067B
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- WERYXYBDKMZEQL-UHFFFAOYSA-N butane-1,4-diol Chemical compound OCCCCO WERYXYBDKMZEQL-UHFFFAOYSA-N 0.000 title claims abstract description 60
- 239000000203 mixture Substances 0.000 title claims abstract description 59
- 239000007788 liquid Substances 0.000 title claims abstract description 50
- 239000002699 waste material Substances 0.000 title claims abstract description 41
- 238000000926 separation method Methods 0.000 title claims abstract description 37
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 26
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims abstract description 243
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims abstract description 158
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 80
- ZXEKIIBDNHEJCQ-UHFFFAOYSA-N isobutanol Chemical compound CC(C)CO ZXEKIIBDNHEJCQ-UHFFFAOYSA-N 0.000 claims abstract description 73
- 238000000034 method Methods 0.000 claims abstract description 31
- 238000010992 reflux Methods 0.000 claims abstract description 16
- 238000005191 phase separation Methods 0.000 claims abstract description 8
- 238000001816 cooling Methods 0.000 claims description 2
- 238000005265 energy consumption Methods 0.000 abstract description 5
- 238000010533 azeotropic distillation Methods 0.000 abstract description 3
- 238000004821 distillation Methods 0.000 abstract description 2
- 239000012071 phase Substances 0.000 description 24
- 239000002994 raw material Substances 0.000 description 11
- 239000000126 substance Substances 0.000 description 7
- XXROGKLTLUQVRX-UHFFFAOYSA-N allyl alcohol Chemical compound OCC=C XXROGKLTLUQVRX-UHFFFAOYSA-N 0.000 description 4
- 238000000605 extraction Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 239000008346 aqueous phase Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000001502 supplementing effect Effects 0.000 description 2
- CMQCNTNASCDNGR-UHFFFAOYSA-N toluene;hydrate Chemical compound O.CC1=CC=CC=C1 CMQCNTNASCDNGR-UHFFFAOYSA-N 0.000 description 2
- UIKQNMXWCYQNCS-UHFFFAOYSA-N 2-hydroxybutanal Chemical compound CCC(O)C=O UIKQNMXWCYQNCS-UHFFFAOYSA-N 0.000 description 1
- MVFSWZGHXYZHPP-UHFFFAOYSA-N 2-methylpropan-1-ol;toluene Chemical compound CC(C)CO.CC1=CC=CC=C1 MVFSWZGHXYZHPP-UHFFFAOYSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- JEGUKCSWCFPDGT-UHFFFAOYSA-N h2o hydrate Chemical compound O.O JEGUKCSWCFPDGT-UHFFFAOYSA-N 0.000 description 1
- 238000007037 hydroformylation reaction Methods 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229920001896 polybutyrate Polymers 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- KIDBBTHHMJOMAU-UHFFFAOYSA-N propan-1-ol;hydrate Chemical compound O.CCCO KIDBBTHHMJOMAU-UHFFFAOYSA-N 0.000 description 1
- OKDOZOFJAUITTD-UHFFFAOYSA-N propan-1-ol;toluene Chemical compound CCCO.CC1=CC=CC=C1 OKDOZOFJAUITTD-UHFFFAOYSA-N 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000011550 stock solution Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/04—Purification; Separation; Use of additives by distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
Abstract
The invention discloses a separation method of a light component mixture in a 1, 4-butanediol production waste liquid, which comprises the steps of carrying out ternary azeotropic distillation on toluene-water-n-propanol in the light component mixture, enabling an overhead fraction to enter an oil-water separator for phase separation, returning an upper oil phase containing n-propanol and toluene to a first rectifying tower C1 for reflux, enabling a lower water phase containing water to enter a stripping tower C2 for stripping separation, and respectively recovering isobutanol, toluene and n-propanol from a fraction extracted from a first rectifying tower C1 kettle through secondary variable pressure distillation. The method creatively solves the problem of separating light components from the 1, 4-butanediol production waste liquid, can completely recover organic components and reduces the energy consumption of the system to the greatest extent.
Description
Technical Field
The invention relates to a separation method, in particular to a separation method of a light component mixture in 1, 4-butanediol production waste liquid, and belongs to the technical field of rectification separation.
Background
1, 4-Butanediol (BDO) is one of high-added-value chemicals downstream of propylene, has wide application in the chemical field, is also a key raw material of a degradable material PBAT and PBS, and has huge market potential in the future along with the implementation of plastic inhibition.
Technology for producing 1, 4-butanediol from allyl alcohol was originally developed by Japanese colali chemical company and Daxillon chemical company, and later developed by Lyonder chemical company, U.S. and its technology is described in detail in book Bai Gengxin.1, 4-butanediol, tetrahydrofuran and its industrial derivatives [ M ]. Chemical industry Press, 2013. In the process of producing 1, 4-butanediol by the method, in the hydroformylation of allyl alcohol and the hydrogenation of hydroxybutanal, side reactions are mainly n-propanol and isobutanol, and after primary separation by toluene extraction, a light component waste liquid containing Toluene (TOL), water, n-propanol (NPA) and Isobutanol (IBA) is produced. The light component waste liquid has a very complex azeotropic system, wherein water-toluene-n-propanol and water-toluene-isobutanol can form ternary azeotropes, water-toluene, water-n-propanol and water-isobutanol respectively form binary azeotropes, and toluene-n-propanol and toluene-isobutanol respectively form binary azeotropes, so that the separation and purification of the light component waste liquid are very difficult.
The applicant conducted extensive work to investigate the azeotropic system present in this light component waste liquid and arrange it as shown in table 1.
TABLE 1 azeotropic systems present in light component waste streams
No economical and effective process is found in the prior literature to realize the separation and recovery of toluene, water, n-propanol and isobutanol in the light component waste liquid, and the light component waste liquid is generally treated as three wastes in industry for combustion treatment. However, with the annual increase of the 1, 4-butanediol productivity, the direct combustion of the light component waste material can bring huge environmental pressure and a great amount of resource waste. Thus, there is a need to develop a separation process for light component mixtures of toluene, water, n-propanol and isobutanol with complex azeotropic systems.
Disclosure of Invention
In order to solve the technical problems, the invention provides a separation method of a light component mixture in 1, 4-butanediol production waste liquid. For the extremely complex mixture of the azeotropic system, the prior art does not have a clear and efficient method for separating substances, even a specially-customized environmental protection technology company does not provide a reasonable solution, the inventor finally provides a solution for separating a ternary azeotrope consisting of toluene, water and n-propanol in a separation system by rectification and then separating water from the ternary azeotrope, returning an oil phase to a first rectifying tower for stable and continuous separation, and separating n-propanol, toluene and isobutanol from a bottom component containing trace water only by conventional rectification, thereby creatively solving the problem of separating light components in the 1, 4-butanediol production waste liquid, completely recovering organic components and reducing the energy consumption of the system to the greatest extent.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a separation method of a light component mixture in 1, 4-butanediol production waste liquid comprises the following process flows:
the light component waste liquid containing water, n-propanol, toluene and isobutanol enters a first rectifying tower C1, azeotropic fractions containing toluene, water and n-propanol are obtained at the top of the tower, and fractions containing toluene, n-propanol and isobutanol are obtained at the bottom of the tower;
enabling the overhead fraction to enter an oil-water separator D1 for phase separation, returning an upper oil phase mainly containing n-propanol and toluene to a first rectifying tower C1 for reflux, enabling a lower water phase mainly containing water to enter a stripping tower C2 for stripping separation, further recovering the residual n-propanol and toluene in the water phase, and returning the recovered overhead component to the oil-water separator D1 or the first rectifying tower C1 after cooling;
and (3) respectively recovering the fraction extracted from the first rectifying tower C1 tower kettle through secondary variable pressure rectification to obtain isobutanol, toluene and n-propanol.
In the invention, a heterogeneous azeotropic distillation system is formed by a first rectifying tower C1, an oil-water phase separator D1 and a stripping tower C2 so as to separate water preferentially, the oil phase separated by the oil-water phase separator D1 is returned to the first rectifying tower C1 so as to continuously carry out water in the system, and finally, the dehydrated n-propanol, toluene and isobutanol are separated by pressure swing distillation. The scheme can effectively separate the light components in the 1, 4-butanediol production waste liquid on the basis of minimum energy consumption, is beneficial to improving the value of byproducts and reducing the pressure of environment-friendly treatment.
In a preferred embodiment of the present invention, the light fraction waste liquid comprises 5-30wt% of water, 5-50wt% of n-propanol, 4-46wt% of toluene, and 3-50wt% of isobutanol.
In a preferred embodiment of the present invention, the first rectifying column C1 is operated at a pressure of 1atm, a column top temperature of 82-85℃and a column bottom temperature of 94-96 ℃;
preferably, the theoretical plate number of the first rectifying tower C1 is 25-50, and the light component waste liquid enters the tower from the top to the bottom at the 10 th-20 th theoretical plate.
After separation treatment in a first rectifying tower C1, a mixture of toluene, n-propanol and isobutanol with water content not higher than 0.1wt% is obtained at the tower bottom, and a ternary azeotropic mixture close to toluene-n-propanol-water is obtained at the tower top, wherein the ternary azeotropic mixture contains 52-58wt% of toluene, 20-38wt% of n-propanol and 9-24wt% of water.
In a preferred embodiment of the invention, the oil phase separated by the oil-water separator D1 enters the first rectifying tower C1 from the top to the bottom at the positions of 1 st to 3 rd theoretical plates;
preferably, the oil phase comprises 2-5wt% of water, 20-42wt% of n-propanol and 55-75wt% of toluene. The water phase comprises 79-89wt% of water, 10-20wt% of n-propanol and 0.1-1wt% of toluene.
In a preferred embodiment of the present invention, the stripper operates at a pressure of 1atm, a top temperature of 93-97 ℃, and a bottom temperature of 98-100 ℃;
preferably, the theoretical plate number of the stripping column C2 is 15-45, and the water phase separated from the oil-water separator D1 enters the column from the 1 st to the 3 rd theoretical plates of the stripping column C2 from top to bottom.
After separation treatment by a gas stripping tower C2, water with the content of more than or equal to 99.5 weight percent is obtained at the tower bottom, a mixture of toluene, n-propanol and water is obtained at the tower top, and the mixture components can flow back to an oil-water separator D1 for continuous phase separation or flow back to a first rectifying tower C1 for azeotropic rectification again.
In a preferred embodiment of the present invention, the overhead components recovered from the stripping column C2 enter the column at the 10 th to 45 th theoretical plates from top to bottom of the first rectifying column C1 for the purpose of reducing energy consumption and ensuring long-term stable operation of the system.
In a preferred embodiment of the invention, the fraction extracted from the bottom of the first rectifying tower C1 is subjected to rectifying separation through a third rectifying tower C3 and a fourth rectifying tower C4 in sequence; and the mixture of toluene and n-propanol is extracted from the top of the third rectifying tower C3 tower kettle and enters a fourth rectifying tower C4, the toluene is extracted from the tower kettle of the fourth rectifying tower C4, and the n-propanol is extracted from the top of the tower. The stillage of the first rectifying column C1, which mainly comprises toluene, n-propanol and isobutanol, is purified and separated by conventional pressure swing rectification.
In a preferred embodiment of the present invention, the third rectifying column C3 has an operating pressure of 1atm, a reflux ratio of more than 0.5, a column top temperature of 90-94℃and a column bottom temperature of 105-109 ℃;
the theoretical plate number of the third rectifying tower C3 is 40-75, and the fraction extracted from the first rectifying tower C1 tower bottom enters the tower from the 10 th to 35 th theoretical plates of the third rectifying tower C3 from top to bottom.
In a preferred embodiment of the invention, the ratio of the mass flow of n-propanol to toluene in the fraction from the bottom of the first rectification column C1 to the third rectification column C3 is not less than 1.08. The inventor finds that the preferable control of the mass flow ratio of the n-propanol to the toluene is more than or equal to 1.08 in the research process can prevent toluene and isobutanol from forming azeotropy in a three rectifying tower C3 to influence the next rectifying separation. If the mass flow rate of the n-propanol/toluene does not meet the requirements, the mass flow rate of the n-propanol can be more than or equal to 1.08 in a mode of supplementing the n-propanol, and the supplementing time can be selected before the tower bottom fraction of the first rectifying tower C1 enters the third rectifying tower C3 or before the light component waste liquid enters the first rectifying tower C1 according to the requirements.
And (3) separating in a third rectifying tower C3 to obtain isobutanol with the content of more than or equal to 99.0wt% at the tower bottom and a mixture of toluene and n-propanol at the tower top.
In a preferred embodiment of the invention, the operating pressure of the fourth rectifying tower C4 is more than or equal to 6atm, the reflux ratio is more than 0.5, the tower top temperature is 165-167 ℃, and the tower bottom temperature is 201-205 ℃;
preferably, the theoretical plate number of the fourth rectifying tower C4 is 45-80, and the fraction extracted from the top of the third rectifying tower C3 enters the tower from 20 th to 50 th theoretical plates of the fourth rectifying tower C4 from top to bottom.
And (3) separating in a fourth rectifying tower C4 to obtain toluene with the content of more than or equal to 99.0wt% at the tower bottom and n-propanol with the content of more than or equal to 99.0wt% at the tower top.
In a preferred embodiment of the invention, the tower kettle pipelines of the first rectifying tower C1, the gas stripping tower C2, the third rectifying tower C3 and the fourth rectifying tower C4 are respectively provided with a reboiler for returning part of the tower kettle discharge materials into the tower so as to provide enough energy for separation in the tower; condensers are arranged on the tower top pipelines of the first rectifying tower C1, the third rectifying tower C3 and the fourth rectifying tower C4, so that the tower top discharge is ensured to enter a subsequent operation unit after being condensed, wherein the tower top discharge of the fourth rectifying tower C4 can be recycled after being condensed, and can be coupled with the reboilers of the first rectifying tower C1, the stripping tower C2 and the third rectifying tower C3 to be used as a heating source of the reboilers.
The invention has the beneficial effects that:
1) According to the invention, by utilizing the property that toluene can be used as an entrainer in an azeotropic component, water is completely carried out by a ternary azeotropic distillation mode, most of n-propanol and toluene in the ternary azeotropic component can be separated from water by virtue of the property of generating phase separation with water, and an oil phase is creatively recycled to a first rectifying tower to supplement the consumption of toluene and continuously carry out water discharge, so that the technical problem that light components in a complex azeotropic system are difficult to effectively separate is solved, separation difficulty and energy consumption are reduced, a separation process is greatly simplified compared with a separation mode consisting of traditional azeotropes, the production cost of a device is reduced, and higher economic benefits can be brought.
2) The separation process adopted by the invention realizes the complete separation of toluene, n-propanol, isobutanol and water, obtains a product with higher quality, can recycle a light component mixture in a 1, 4-butanediol production system, and has good economic benefit.
Drawings
FIG. 1 is an overall process flow diagram of the separation process of the present invention.
Detailed Description
The invention will now be further illustrated by means of specific examples which are given solely by way of illustration of the invention and do not limit the scope thereof.
Unless defined otherwise, technical terms used in the following examples have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. The experimental reagents used in the following examples are all conventional biochemical reagents unless otherwise specified; the experimental methods are conventional methods unless otherwise specified.
The light component mixture feed stock solution used in the following examples and comparative examples of the present invention comprises the following components:
raw material liquid 1:14.34wt% water, 17.42wt% toluene, 50.82wt% n-propanol, 17.42wt% isobutanol.
Raw material liquid 2: comprises 6.15wt% water, 39.26wt% toluene, 47.22wt% n-propanol, 7.37wt% isobutanol.
Raw material liquid 3: comprises 26.23wt% water, 20.17wt% toluene, 44.10wt% n-propanol, 9.50wt% isobutanol.
[ example 1 ]
The separation method of the light component mixture in the 1, 4-butanediol production waste liquid comprises the following process flows, wherein the process flows are shown in figure 1:
the first rectifying column C1 has 30 theoretical plates, the flow rate of the raw material liquid 1 is 1033kg/hr, the raw material liquid 1 enters the first rectifying column C1 from 15 th theoretical plate from top to bottom, the operating pressure of the first rectifying column C1 is 1atm, the top temperature is 83.4 ℃, the bottom temperature is 95.1 ℃, the mixture of toluene, propanol and isobutanol (containing 20.3wt% toluene, 59.3wt% n-propanol and 20.3wt% isobutanol) with the water content lower than 0.1wt% is obtained in the bottom, and the discharge flow rate is 885kg/hr; a fraction having a composition of 52.8wt% toluene, 38.0wt% n-propanol and 9.2wt% water was obtained at the top of the column, and the discharge flow rate was 2087.8kg/hr.
The temperature of the oil-water phase separator D1 is 40 ℃, the tower top fraction of the first rectifying tower C1 is condensed and enters the oil-water phase separator D1 for phase separation, wherein an oil phase with the composition of 56.8wt% of toluene, 40.9wt% of n-propanol and 2.3wt% of water enters the tower from the position of a 2 nd theoretical plate of the first rectifying tower C1 from top to bottom, the flow rate is 1939.5kg/hr, and a water phase with the composition of 0.3wt% of toluene, 17.7wt% of n-propanol and 82.0wt% of water enters the tower from the position of the 1 st theoretical plate of the stripping tower C2 from top to bottom, and the flow rate is 351.9kg/hr.
The stripping column C2 has 25 theoretical plates, the operating pressure is 1atm, the temperature of the top of the column is 96.4 ℃, the temperature of the column bottom is 100 ℃, water with the content of more than or equal to 99.9wt% is obtained in the column bottom, the discharge flow is 148kg/hr, a fraction with the composition of 0.5wt% toluene, 68.8wt% n-propanol and 30.7wt% water is obtained at the top of the column, and the fraction at the top of the column is cooled to 40 ℃ and then sent into a phase separator, and the flow is 203.7kg/hr.
The third rectifying column C3 has 50 theoretical plates, the liquid extracted from the bottom of the first rectifying column C1 enters the column from the 23 rd theoretical plate of the third rectifying column C3 from top to bottom, wherein the ratio of n-propanol to toluene is 2.92, the operating pressure of the third rectifying column C3 is 1atm, the reflux ratio is 3, the temperature of the top of the column is 92.7 ℃, the temperature of the bottom of the column is 107.3 ℃, the isobutanol with the content of more than or equal to 99.5wt% is obtained at the bottom of the column, the flow rate is 180kg/hr, and the mixture with the composition comprising 22.3wt% toluene and 77.6wt% of n-propanol is obtained at the top of the column, and the flow rate is 705kg/hr.
The fourth rectifying tower C4 is provided with 55 theoretical plates, the top fraction of the third rectifying tower C3 enters the tower from the position of the 30 th theoretical plate of the fourth rectifying tower C4 from top to bottom, the operating pressure of the fourth rectifying tower C4 is 8atm, the reflux ratio is 3.5, the tower top temperature is 165 ℃, the tower bottom temperature is 203 ℃, toluene with the content of more than or equal to 99.5 weight percent is obtained at the tower bottom, and the flow is 180kg/hr; the n-propanol with the content of more than or equal to 99.5 weight percent is obtained at the top of the tower, the flow is 525kg/hr, and the n-propanol steam at the top of the tower enters a reboiler of the first rectifying tower C1 to provide partial heating source.
The separation apparatus and process in this example, after 170 hours of continuous operation, yielded water having a purity of 99.9wt% or more, toluene having a purity of 99.5wt% or more, n-propanol having a purity of 99.5wt% and isobutanol having a purity of 99.5wt% or more, respectively.
[ example 2 ]
The separation method of the light component mixture in the 1, 4-butanediol production waste liquid comprises the following process flows, wherein the process flows are shown in figure 1:
the first rectifying tower C1 is provided with 40 theoretical plates, the flow rate of the raw material liquid 2 is 1045kg/hr, the raw material liquid 2 enters the first rectifying tower C1 from the 17 th theoretical plate from top to bottom, the operating pressure of the first rectifying tower C1 is 1atm, the tower top temperature is 83.7 ℃, the tower kettle temperature is 95.0 ℃, the mixture of toluene, n-propanol and isobutanol (containing 41.8wt% toluene, 50.3wt% n-propanol and 7.8wt% isobutanol) with the water content lower than 0.1wt% is obtained in the tower kettle, and the discharge flow rate is 981kg/hr; a fraction having a composition of 55.8wt% toluene, 27.6wt% n-propanol and 16.6wt% water was obtained at the top of the column, and the discharge flow rate was 474.4kg/hr.
The temperature of the oil-water phase separator D1 is 43 ℃, the overhead fraction of the first rectifying tower C1 enters the oil-water phase separator D1 for phase separation after being condensed, wherein an oil phase with the composition of 67.8 weight percent of toluene, 30.2 weight percent of n-propanol and 2.0 weight percent of water enters the tower from the theoretical plate of the first rectifying tower C1 from top to bottom, and the flow rate is 390kg/hr; an aqueous phase having a composition of 0.2wt% toluene, 15.7wt% n-propanol, 84.1wt% water was fed into the stripping column C2 from the 1 st theoretical plate from above, and the flow rate was 84.5kg/hr.
The stripping column C2 has 30 theoretical plates, the operating pressure is 1atm, the temperature of the top of the column is 96.4 ℃, the temperature of the column bottom is 100 ℃, water with the content of more than or equal to 99.9wt% is obtained in the column bottom, the discharge flow rate is 64.3kg/hr, a fraction with the composition of 0.8wt% toluene, 65.7wt% n-propanol and 33.5wt% water is obtained in the column top, and the fraction of the top of the column enters the column from the 22 th theoretical plate of the first rectifying column C1 from top to bottom, and the flow rate is 20.2kg/hr.
The third rectifying tower C3 is provided with 60 theoretical plates, the produced liquid of the first rectifying tower C1 tower bottom enters the tower from the position of the 27 th theoretical plate from top to bottom of the third rectifying tower C3, wherein the ratio of normal propyl alcohol to toluene is 1.20, the operating pressure of the third rectifying tower C3 is 1atm, the reflux ratio is 3.5, the tower top temperature is 92.9 ℃, the tower bottom temperature is 107.1 ℃, the isobutanol with the content of more than or equal to 99.5 weight percent is obtained at the tower bottom, the flow rate is 77kg/hr, the mixture of toluene and normal propyl alcohol is obtained at the tower top, the flow rate is 904kg/hr, and the composition is 45.3 weight percent toluene and 54.6 weight percent normal propyl alcohol.
The fourth rectifying tower C4 is provided with 60 theoretical plates, the top fraction of the third rectifying tower C3 enters the tower from the 32 th theoretical plate of the fourth rectifying tower C4 from top to bottom, the operating pressure of the fourth rectifying tower C4 is 6atm, the reflux ratio is 4, the tower top temperature is 165.5 ℃, the tower bottom temperature is 203.3 ℃, toluene with the content of more than or equal to 99.5 weight percent is obtained in the tower bottom, and the flow is 410.3kg/hr; the n-propanol with the content of more than or equal to 99.5 weight percent is obtained at the top of the tower, the flow is 493.5kg/hr, and the n-propanol steam at the top of the tower enters a reboiler of the first rectifying tower C1 to provide partial heating source.
The separation apparatus and process in this example gave water having a purity of approximately 1, 99.7wt% toluene, 99.8wt% n-propanol, 99.5wt% isobutanol, respectively, after 170 hours of continuous operation.
[ example 3 ]
The separation method of the light component mixture in the 1, 4-butanediol production waste liquid comprises the following process flows, wherein the process flows are shown in figure 1:
the first rectifying tower C1 is provided with 30 theoretical plates, the flow rate of the raw material liquid 3 is 1020kg/hr, the raw material liquid 3 enters the first rectifying tower C1 from the 13 th theoretical plate from top to bottom, the operating pressure of the first rectifying tower C1 is 1atm, the tower top temperature is 83.4 ℃, the tower kettle temperature is 95.2 ℃, the mixture of toluene, n-propanol and isobutanol with the water content lower than 0.1wt percent (comprising 27.3wt percent of toluene, 59.8wt percent of n-propanol and 12.8wt percent of isobutanol) is obtained in the tower kettle, and the discharge flow rate is 752.5kg/hr; a fraction having a composition of 53.9wt% toluene, 30.6wt% n-propanol and 15.5wt% water was obtained at the top of the column, and the discharge flow rate was 2172.2kg/hr.
The temperature of the oil-water phase separator D1 is 42 ℃, the overhead fraction of the first rectifying tower C1 enters the oil-water phase separator D1 for phase separation after being condensed, wherein an oil phase consisting of 64.2 weight percent of toluene, 33.4 weight percent of n-propanol and 2.4 weight percent of water enters the tower from the 1 st theoretical plate of the first rectifying tower C1 from top to bottom, and the flow rate is 1822kg/hr; an aqueous phase having a composition of 0.2wt% toluene, 15.8wt% n-propanol, 84.0wt% water was fed into the stripping column C2 from the 1 st theoretical plate from above, and the flow rate was 349.7kg/hr.
The stripping column C2 has 25 theoretical plates, the operating pressure is 1atm, the temperature of the top of the column is 96.5 ℃, the temperature of the column bottom is 100 ℃, water with the content of more than or equal to 99.9wt% is obtained in the column bottom, the discharge flow is 268kg/hr, a fraction with the composition of 0.8wt% toluene, 65.7wt% n-propanol and 31.9wt% water is obtained at the top of the column, and the fraction at the top of the column enters the column from the 20 th theoretical plate from the top to the bottom of the first rectifying column C1, and the flow is 82kg/hr.
The third rectifying tower C3 is provided with 55 theoretical plates, the produced liquid of the first rectifying tower C1 tower bottom enters the tower from the position of the 24 th theoretical plate from top to bottom of the third rectifying tower C3, wherein the ratio of normal propyl alcohol to toluene is 2.20, the operating pressure of the third rectifying tower C3 is 1atm, the reflux ratio is 4, the tower top temperature is 92.9 ℃, the tower bottom temperature is 107.3 ℃, the isobutanol with the content of more than or equal to 99.5 weight percent is obtained at the tower bottom, the flow rate is 97kg/hr, the mixture of toluene and normal propyl alcohol is obtained at the tower top, the flow rate is 655.4kg/hr, and the composition is 31.4 weight percent toluene and 68.5 weight percent normal propyl alcohol.
The fourth rectifying tower C4 is provided with 60 theoretical plates, the top fraction of the third rectifying tower C3 enters the tower from the position of the 30 th theoretical plate of the fourth rectifying tower C4 from top to bottom, the operating pressure of the fourth rectifying tower C4 is 7atm, the reflux ratio is 5, the tower top temperature is 165.5 ℃, the tower bottom temperature is 203.3 ℃, toluene with the content of more than or equal to 99.5 weight percent is obtained in the tower bottom, and the flow is 206kg/hr; the n-propanol with the content of more than or equal to 99.5 weight percent is obtained at the top of the tower, the flow is 450kg/hr, and the n-propanol steam at the top of the tower enters a reboiler of the first rectifying tower C1 to provide partial heating source.
The separation apparatus and process in this example, after 170 hours of continuous operation, yielded water having a purity of approximately 1, 99.5wt% toluene, 99.7wt% n-propanol, and 99.3wt% isobutanol, respectively.
Comparative example 1
The first rectifying column C1 has 30 theoretical plates, the raw material liquid 1 with the flow rate of 1033kg/hr enters the first rectifying column C1 from 15 th theoretical plate from top to bottom, the operating pressure of the first rectifying column C1 is 1atm, the extraction from the top of the column does not enter a phase separator, and the reflux and the extraction are carried out after direct condensation, and the reflux ratio is 5. According to the monitoring results in table 2, it can be seen that under different rectification conditions and extraction amounts, although the composition of the top of the column and the composition of the bottom of the column are changed, a mixture with the same kind as the composition of the feed still appears at the top or at the bottom of the column, which indicates that the effective separation of the mixture cannot be achieved by the direct condensation reflux method.
TABLE 2 example 2 monitoring results
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and additions may be made to those skilled in the art without departing from the method of the present invention, which modifications and additions are also to be considered as within the scope of the present invention.
Claims (12)
1. The separation method of the light component mixture in the 1, 4-butanediol production waste liquid is characterized by comprising the following process flows:
the light component waste liquid containing water, n-propanol, toluene and isobutanol enters a first rectifying tower C1, azeotropic fractions containing toluene, water and n-propanol are obtained at the top of the tower, and fractions containing toluene, n-propanol and isobutanol are obtained at the bottom of the tower; the operating pressure of the first rectifying tower C1 is 1atm, the tower top temperature is 82-85 ℃, and the tower bottom temperature is 94-96 ℃; the theoretical plate number of the first rectifying tower C1 is 25-50, and the light component waste liquid enters the tower from the 10 th to the 20 th theoretical plates from top to bottom;
enabling the overhead fraction to enter an oil-water separator D1 for phase separation, returning an upper oil phase mainly containing n-propanol and toluene to a first rectifying tower C1 for reflux, enabling a lower water phase mainly containing water to enter a stripping tower C2 for stripping separation, further recovering the residual n-propanol and toluene in the water phase, and returning the recovered overhead component to the oil-water separator D1 or the first rectifying tower C1 after cooling;
and (3) respectively recovering the fraction extracted from the first rectifying tower C1 tower kettle through secondary variable pressure rectification to obtain isobutanol, toluene and n-propanol.
2. The method for separating a light component mixture from a 1, 4-butanediol production waste liquid according to claim 1, wherein the light component waste liquid comprises 5-30wt% of water, 5-50wt% of n-propanol, 4-46wt% of toluene and 3-50wt% of isobutanol.
3. The method for separating a light component mixture from a waste liquid from the production of 1, 4-butanediol according to claim 1, wherein the oil phase separated by the oil-water separator D1 enters the first rectifying tower C1 from the 1 st to the 3 rd theoretical plates from the top.
4. The method for separating a mixture of light components from a waste liquid from the production of 1, 4-butanediol according to claim 1, wherein the oil phase comprises 2-5wt% of water, 20-42wt% of n-propanol, and 55-75wt% of toluene.
5. A method for separating a mixture of light components from a waste liquid from 1, 4-butanediol production according to any one of claims 1 to 3, wherein the operation pressure of the stripping tower is 1atm, the tower top temperature is 93 to 97 ℃, and the tower bottom temperature is 98 to 100 ℃.
6. The method for separating a light component mixture from a waste liquid from 1, 4-butanediol production according to claim 5, wherein the theoretical plate number of the stripping column C2 is 15-45, and the water phase separated from the oil-water separator D1 enters the stripping column C2 from 1 st to 3 rd theoretical plates from top to bottom.
7. The method for separating a mixture of light components from a waste liquid from 1, 4-butanediol production according to claim 5, wherein the top component recovered from the stripping column C2 enters the column from the 10 th to 45 th theoretical plates from the top of the first rectifying column C1.
8. A method for separating a light component mixture in a 1, 4-butanediol production waste liquid according to any one of claims 1 to 3, wherein the fraction extracted from the bottom of the first rectifying tower C1 is subjected to rectifying separation sequentially through a third rectifying tower C3 and a fourth rectifying tower C4; and the mixture of toluene and n-propanol is extracted from the top of the third rectifying tower C3 tower kettle and enters a fourth rectifying tower C4, the toluene is extracted from the tower kettle of the fourth rectifying tower C4, and the n-propanol is extracted from the top of the tower.
9. The method for separating a light component mixture from a waste liquid from the production of 1, 4-butanediol according to claim 8, wherein the operation pressure of the third rectifying column C3 is 1atm, the reflux ratio is more than 0.5, the temperature at the top of the column is 90-94 ℃, and the temperature at the bottom of the column is 105-109 ℃;
the theoretical plate number of the third rectifying tower C3 is 40-75, and the fraction extracted from the first rectifying tower C1 tower bottom enters the tower from the 10 th to 35 th theoretical plates of the third rectifying tower C3 from top to bottom.
10. The method for separating a light component mixture from a waste liquid from the production of 1, 4-butanediol according to claim 9, wherein the ratio of the mass flow rate of n-propanol to toluene in the fraction entering the third rectifying column C3 from the bottom of the first rectifying column C1 is not less than 1.08.
11. The method for separating a mixture of light components from a waste liquid from 1, 4-butanediol production according to any one of claims 1 to 3, wherein the operating pressure of the fourth rectifying column C4 is not less than 6atm, the reflux ratio is more than 0.5, the temperature at the top of the column is 165 to 167 ℃, and the temperature at the bottom of the column is 201 to 205 ℃.
12. The method for separating a light component mixture from a waste liquid from 1, 4-butanediol production according to claim 11, wherein the theoretical plate number of the fourth rectifying column C4 is 45-80, and the fraction extracted from the top of the third rectifying column C3 enters the column from 20 th to 50 th theoretical plates of the fourth rectifying column C4 from top to bottom.
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