CN108949230B

CN108949230B - Liquefied gas desulfurization system and method

Info

Publication number: CN108949230B
Application number: CN201810557580.2A
Authority: CN
Inventors: 舒心; 董亭波; 刘行平; 何超超
Original assignee: Jinao Hubei Science & Technology Chemical Industry Co ltd
Current assignee: Jinao Hubei Science & Technology Chemical Industry Co ltd
Priority date: 2018-06-01
Filing date: 2018-06-01
Publication date: 2020-09-25
Anticipated expiration: 2038-06-01
Also published as: CN108949230A

Abstract

The invention discloses a liquefied gas desulfurization system and a method, which relate to the technical field of chemical production, wherein the liquefied gas desulfurization system comprises an online mixer, a preceding-stage separation device, a middle-stage separation device and a rear-stage separation device which are sequentially connected; respectively introducing the liquefied gas and the MTBE into the online mixer for mixing, transferring sulfur components in the liquefied gas into the MTBE, introducing the mixed mixture into the front-stage separation device for separation, introducing the MTBE into the middle-stage separation device for de-heavy treatment, separating heavy components containing high sulfur at the bottom of the tower and intermittently delivering the heavy components out of the middle-stage separation device, introducing the MTBE at the top of the tower into the rear-stage separation device for carbon five separation, and mixing the MTBE with the separated carbon five as a feed of the online mixer with the liquefied gas for recycling. The process is relatively simple, the operation is easy, the desulfurization effect is obvious, the obtained attached carbon five components can be used as production raw materials of other products, and the benefit is improved.

Description

Liquefied gas desulfurization system and method

Technical Field

The invention relates to the technical field of chemical production, in particular to a liquefied gas desulfurization system and a liquefied gas desulfurization method.

Background

With the development of the petrochemical industry, the liquefied petroleum gas has been paid more and more attention as a chemical basic material and a novel fuel. The liquefied petroleum gas is used as fuel, and has high heat value, no smoke dust and carbon residue, and convenient operation and use, and has widely entered the living field of people. In the aspect of chemical production, the liquefied petroleum gas is a byproduct obtained when an oil refinery carries out catalytic cracking and thermal cracking on crude oil, and the catalytic cracking gas comprises the following main components (%): ethane and ethylene 2-3, propane 10-15, propylene 30-35, butane 42-46, butylene 5-6, and hydrocarbon 2-3 containing more than 5 carbon atoms, and is used for producing synthetic plastics, synthetic rubber, synthetic fiber, and products such as medicine, explosive, dye, etc.

Liquefied petroleum gas is one of the products in petroleum processing and is also an important raw material for further processing into other products. The refined liquefied petroleum gas is mainly liquefied gas obtained by removing hydrogen sulfide by an alcohol amine method, and the liquefied gas from an alcohol amine method desulfurization unit mainly comprises C3 and C4 components and contains a small amount of hydrogen sulfide and organic sulfur (mainly mercaptan, carbonyl sulfide and carbon disulfide). The catalysts required by the conversion of liquefied gas in the current market mainly comprise sulfonated cobalt phthalocyanine and/or poly cobalt phthalocyanine catalysts, but the two catalysts only have good conversion effect on sodium mercaptan, have single function, need to add air and/or an activating agent additionally, have complex process and high cost.

Disclosure of Invention

In order to overcome the defects of related products in the prior art, the invention provides a liquefied gas desulfurization system and a liquefied gas desulfurization method, and solves the problems of complex process and high cost of the conventional liquefied gas desulfurization process.

The invention provides a liquefied gas desulfurization system, comprising: the online mixer, the preceding stage separation device, the middle stage separation device and the rear stage separation device are sequentially connected; respectively introducing the liquefied gas and the MTBE into the online mixer for mixing, transferring sulfur components in the liquefied gas into the MTBE, introducing the mixed mixture into the front-stage separation device for separation, sending the separated liquefied gas to the gas separation device, introducing the MTBE into the middle-stage separation device for heavy component removal treatment, separating heavy components containing high sulfur at the bottom of the tower and intermittently sending the heavy components out of the middle-stage separation device, mixing part of the MTBE positioned at the top of the tower with the liquefied gas as a feed of the online mixer for recycling, sending the rest part of the MTBE to the MTBE storage tank for storage, introducing the MTBE in the MTBE storage tank into the rear-stage separation device for five-carbon separation when the content of the five-carbon in the MTBE storage tank reaches a preset value, and mixing the MTBE after the five-carbon is separated with the liquefied gas as a feed of the online mixer for recycling.

In some embodiments of the invention, the pre-separation device comprises a heat exchanger, a desulfurization tower, a pre-reboiling furnace, a pre-tower bottom pump, a pre-air cooler, a pre-upper water cooler, a pre-tower top reflux tank, a pre-tower top reflux pump, and a pre-lower water cooler; the heat exchanger is respectively connected with the online mixer, the desulfurizing tower and the preceding-stage lower water cooler; the desulfurizing tower, the preceding-stage air cooler, the preceding-stage upper water cooler, the preceding-stage tower top reflux tank and the preceding-stage tower top reflux pump are sequentially and circularly connected; the fore-stage tower bottom pump is respectively connected with the heat exchanger and the desulfurizing tower; the desulfurizing tower is connected with the front stage reboiling furnace; respectively introducing liquefied gas and MTBE into the online mixer for mixing, allowing the mixed mixture to enter a heat exchanger, heating to a reaction temperature, conveying to a desulfurization tower for separation, allowing the separated gas-liquid mixture to sequentially pass through a front-stage air cooler and a front-stage upper water cooler and then enter a front-stage tower top reflux tank, allowing the front-stage air cooler and the front-stage upper water cooler to respectively perform air cooling and water cooling on the gas-liquid mixture at the top of the desulfurization tower to condense acidic water therein, separating the acidic water in the front-stage tower top reflux tank, allowing the front-stage tower top reflux tank to store tower top materials, returning the rest products to the desulfurization tower through a front-stage tower top reflux pump for cyclic separation, and allowing the liquefied gas to be separated by the front-stage tower top reflux pump before returning to the desulfurization tower and conveying the liquefied; and the separated MTBE is pressurized by the front-stage tower bottom pump, sequentially subjected to heat exchange by the heat exchanger and cooled by the front-stage water cooler and then output to the intermediate-stage separation device.

In certain embodiments of the invention, the intermediate separation unit comprises a de-heaving column, an intermediate reboiling furnace, an intermediate upper water cooler, an intermediate overhead reflux drum, an intermediate overhead reflux pump, an intermediate bottom pump, and an intermediate lower water cooler; the heavy component removal tower is respectively connected with the preceding stage separation device and the intermediate stage reboiling furnace, the heavy component removal tower, the intermediate stage upper water cooler, the intermediate stage tower top reflux tank and the intermediate stage tower top reflux pump are sequentially and circularly connected, and the heavy component removal tower, the intermediate stage tower bottom pump and the intermediate stage lower water cooler are sequentially connected; MTBE is subjected to heavy component separation through the de-weighting tower, the separated gas-liquid mixture is cooled through a middle-level upper water cooler and then enters a middle-level tower top reflux tank for standing, then the gas-liquid mixture is sent to a middle-level tower top reflux pump to be pressurized and then returns to the de-weighting tower for cyclic separation, the MTBE is separated before returning to the de-weighting tower, one part of the MTBE is used as the feed of an on-line mixer to be mixed with the liquefied gas for cyclic use, and the rest of the MTBE is sent to an MTBE storage tank for storage; and the rest heavy components enter a de-weighting tower, are pressurized by a middle-stage tower bottom pump at the bottom of the tower and are cooled by a middle-stage water cooler and then are recovered.

In certain embodiments of the invention, when the MTBE content in the MTBE storage tank is greater than 20% carbon five, the MTBE in the MTBE storage tank is passed to a back-end separation unit for carbon five separation.

In some embodiments of the invention, the back-stage separation device comprises a light component removal tower, a back-stage reboiling furnace, a back-stage upper water cooler, a back-stage tower top reflux tank, a back-stage tower top reflux pump, a back-stage tower bottom pump and a back-stage lower water cooler; the light component removal tower is connected with a middle-stage lower water cooler and a rear-stage reboiling furnace of a middle-stage separation device respectively, the light component removal tower, a rear-stage upper water cooler, a rear-stage tower top reflux tank and a rear-stage tower top reflux pump are sequentially and circularly connected, and the light component removal tower, a rear-stage tower bottom pump and the rear-stage lower water cooler are sequentially connected; and MTBE is subjected to carbon five separation through the light component removal tower, the separated gas-liquid mixture is cooled through a rear-stage upper water cooler and then enters a rear-stage overhead reflux tank for standing, then the gas-liquid mixture is sent to a rear-stage overhead reflux pump for pressurization and then returns to the light component removal tower for cyclic separation, the carbon five components are separated before returning to the light component removal tower, the MTBE after the carbon five separation is subjected to pressurization through a rear-stage tower bottom pump and cooling through a rear-stage lower water cooler and then is recovered, and the MTBE is used as a feed of an on-line mixer and is mixed with the liquefied gas for cyclic use.

The invention also provides a liquefied gas desulfurization method, which is applied to any one of the liquefied gas desulfurization systems and comprises the following steps:

respectively introducing the liquefied gas and MTBE into the in-line mixer for mixing, so that sulfur components in the liquefied gas are transferred into the MTBE;

the mixed mixture enters the front-stage separation device to separate liquefied gas from MTBE, and the separated liquefied gas is sent to a gas separation device;

the MTBE is fed into a middle-stage separation device for carrying out de-heavy treatment, heavy components containing high sulfur and located at the bottom of the tower are separated and intermittently fed out of the middle-stage separation device, one part of the MTBE located at the top of the tower is used as a feed of an on-line mixer to be mixed with the liquefied gas for recycling, and the redundant part of the MTBE is fed into an MTBE storage tank for storage;

when the content of the five carbon atoms in the MTBE storage tank reaches a preset value, the MTBE in the MTBE storage tank is introduced into a rear-stage separation device for five carbon atoms separation, and the MTBE after the five carbon atoms separation is used as a feed of an on-line mixer to be mixed with the liquefied gas for recycling.

In certain embodiments of the invention, the separation of liquefied gas and MTBE is in particular:

respectively introducing liquefied gas and MTBE into an online mixer for mixing, heating the mixed mixture into a heat exchanger to a reaction temperature, conveying the heated mixture to a desulfurizing tower for separation, sequentially passing the separated gas-liquid mixture through a front-stage air cooler and a front-stage upper water cooler, then entering a front-stage tower top reflux tank, respectively carrying out air cooling and water cooling on the gas-liquid mixture at the top of the desulfurizing tower by the front-stage air cooler and the front-stage upper water cooler to condense acidic water therein, separating the acidic water in the front-stage tower top reflux tank, storing tower top materials by the front-stage tower top reflux tank, returning the rest products to the desulfurizing tower through a front-stage tower top reflux pump for cyclic separation, and separating the liquefied gas through the front-stage tower top reflux pump before returning to the desulfurizing tower and conveying the liquefied; the separated MTBE is pressurized by a front-stage tower bottom pump, then sequentially subjected to heat exchange by a heat exchanger and cooling by a front-stage water cooler and then output to a middle-stage separation device.

In some embodiments of the present invention, the step of passing the MTBE into the medium-grade separation device for heavy removal is specifically:

the MTBE is subjected to heavy component separation through a de-weighting tower, a separated gas-liquid mixture is cooled through a middle-level upper water cooler and then is placed in a middle-level tower top reflux tank for standing, then the gas-liquid mixture is sent to a middle-level tower top reflux pump for pressurization and then is returned to the de-weighting tower for cyclic separation, the MTBE is separated before being returned to the de-weighting tower, one part of the MTBE is used as the feed of an on-line mixer to be mixed with the liquefied gas for cyclic use, and the rest of the MTBE is sent to an MTBE storage tank for storage; and the rest heavy components enter a de-weighting tower, are pressurized by a middle-stage tower bottom pump at the bottom of the tower and are cooled by a middle-stage water cooler and then are recovered.

In certain embodiments of the invention, the method further comprises: when the content of the five carbon in the MTBE storage tank is more than 20%, the MTBE in the MTBE storage tank is fed to a rear-stage separation device for five carbon separation.

In certain embodiments of the invention, the MTBE in the MTBE storage tank is passed to a post separation unit for carbon five separation specifically:

and MTBE is subjected to carbon five separation through a light component removal tower, a separated gas-liquid mixture is cooled through a rear-stage upper water cooler and then is placed in a rear-stage tower top reflux tank for standing, then the gas-liquid mixture is sent to a rear-stage tower top reflux pump for pressurization and then is returned to the light component removal tower for cyclic separation, the carbon five components are separated before returning to the light component removal tower, the MTBE after the carbon five is separated is subjected to pressurization through a rear-stage tower bottom pump and cooling through a rear-stage lower water cooler and then is recovered, and the MTBE is used as a feed of an on-line mixer and is mixed with the liquefied gas for cyclic use.

Compared with the prior art, the invention has the following advantages:

the liquefied gas desulfurization system disclosed by the embodiment of the invention mixes the liquefied gas and the MTBE through the online mixer, so that sulfur components in the liquefied gas are transferred into the MTBE, then the liquefied gas and the MTBE are separated through the front-stage separation device, the MTBE and heavy components are separated through the middle-stage separation device, the MTBE and the five-carbon components are separated through the rear-stage separation device, and the MTBE can be recycled.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic diagram of the principle structure of a liquefied gas desulfurization system according to the present invention;

FIG. 2 is a schematic structural diagram of an in-line mixer and a preceding stage separation apparatus according to the present invention;

FIG. 3 is a schematic diagram of the principle structure of the intermediate separation apparatus according to the present invention;

FIG. 4 is a schematic structural diagram of a rear separation device according to the present invention;

fig. 5 is a schematic flow diagram of a liquefied gas desulfurization method according to the present invention.

Description of reference numerals:

100-an in-line mixer;

200-a preceding stage separation device, 201-a heat exchanger, 202-a desulfurizing tower, 203-a preceding stage reboiling furnace, 204-a preceding stage tower bottom pump, 205-a preceding stage air cooler, 206-a preceding stage upper water cooler, 207-a preceding stage tower top reflux tank, 208-a preceding stage tower top reflux pump and 209-a preceding stage lower water cooler;

300-middle-stage separation device, 301-heavy component removal tower, 302-middle-stage reboiling furnace, 303-middle-stage upper water cooler, 304-middle-stage tower top reflux tank, 305-middle-stage tower top reflux pump, 306-middle-stage tower bottom pump and 307-middle-stage lower water cooler;

400-rear-stage separation device, 401-light component removal tower, 402-rear-stage reboiling furnace, 403-rear-stage upper water cooler, 404-rear-stage tower top reflux tank, 405-rear-stage tower top reflux pump, 406-rear-stage tower bottom pump and 407-rear-stage lower water cooler.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely illustrative of some, but not all, of the embodiments of the invention, and that the preferred embodiments of the invention are shown in the drawings. This invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present disclosure is set forth in order to provide a more thorough understanding thereof. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The terms "including" and "having," and any variations thereof, in the description and claims of this invention and the above-described drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

Fig. 1 is a schematic diagram of a principle structure of a liquefied gas desulfurization system according to the present invention, and referring to fig. 1, the liquefied gas desulfurization system includes an in-line mixer 100, a front-stage separation device 200, a middle-stage separation device 300, and a rear-stage separation device 400, which are sequentially connected, the liquefied gas and MTBE (methyl tert-butyl ether) are respectively introduced into the in-line mixer 100 to be mixed, sulfur components in the liquefied gas are transferred into the MTBE due to the fact that the sulfur components are more soluble with each other, the mixed mixture is introduced into the front-stage separation device 200 to be separated, the separated liquefied gas is sent to the gas separation device, the MTBE is introduced into the middle-stage separation device 300 to be subjected to a de-heavy treatment, heavy components containing high sulfur at the bottom of the column are separated and intermittently sent out of the middle-stage separation device 300, a part of the MTBE located at the top of the column is recycled as a feed of the in-line mixer 100 and mixed with the liquefied gas, and (3) sending the redundant part to an MTBE storage tank for storage, when the content of the five carbon atoms in the MTBE storage tank reaches a preset value, introducing the MTBE in the MTBE storage tank into a rear-stage separation device 400 for separating the five carbon atoms, and mixing the MTBE with the separated five carbon atoms as a feed of the on-line mixer 100 with the liquefied gas for recycling.

Fig. 2 is a schematic structural diagram of the online mixer 100 and the preceding stage separation device 200 according to the present invention, and referring to fig. 2, the preceding stage separation device 200 includes a heat exchanger 201, a desulfurization tower 202, a preceding stage reboiling furnace 203, a preceding stage tower bottom pump 204, a preceding stage air cooler 205, a preceding stage upper water cooler 206, a preceding stage tower top reflux tank 207, a preceding stage tower top reflux pump 208, and a preceding stage lower water cooler 209; the heat exchanger 201 is respectively connected with the online mixer 100, the desulfurizing tower 202 and the front-stage water cooler 209; the desulfurization tower 202, the preceding stage air cooler 205, the preceding stage upper water cooler 206, the preceding stage overhead reflux tank 207 and the preceding stage overhead reflux pump 208 are sequentially and circularly connected; the fore-stage tower bottom pump 204 is respectively connected with the heat exchanger 201 and the desulfurizing tower 202; the desulfurizing tower 202 is connected with the front stage reboiling furnace 203; liquefied gas and MTBE are respectively introduced into the online mixer 100 to be mixed, sulfur components in the liquefied gas are transferred into the MTBE, the mixed mixture enters the heat exchanger 201 to be heated to a reaction temperature and is conveyed to the desulfurizing tower 202 to be separated, the separated gas-liquid mixture sequentially passes through a front-stage air cooler 205 and a front-stage upper water cooler 206 and then enters a front-stage overhead reflux tank 207, the front-stage air cooler 205 and the front-stage upper water cooler 206 respectively perform air cooling and water cooling on the gas-liquid mixture positioned at the top of the desulfurizing tower 202 to condense acidic water (water containing hydrogen sulfide) therein, acidic water is separated in the front-stage overhead reflux tank 207, the front-stage overhead reflux tank 207 is used for storing overhead materials and achieving the purpose of standing and separating the acidic water and the MTBE, and the rest products return to the desulfurizing tower 202 through the front-stage overhead reflux pump 208 to be circularly separated, and the liquefied gas before being mixed contains about 2000ppm of total sulfur, the total sulfur of MTBE is less than 50ppm, the MTBE is separated from the liquefied gas, the sulfur content of the separated MTBE is about 2000ppm, and the liquefied gas is separated by the front-stage overhead reflux pump 208 and sent to a gas separation device before returning to the desulfurization tower 202; the front-stage reboiling furnace 203 heats the mixture in the desulfurizing tower 202 by steam, and the heated condensed water is used as a heat source of the catalytic desulfurizing tower 202, so that the steam consumption can be further reduced; the separated MTBE is pressurized by the front-stage tower bottom pump 204, then sequentially passes through the heat exchanger 201 for heat exchange and the front-stage lower water cooler 209 for cooling, and then is output to the intermediate-stage separation device 300.

Fig. 3 is a schematic structural diagram of a medium-stage separation device 300 according to the present invention, and referring to fig. 3, the medium-stage separation device 300 includes a de-heavy tower 301, a medium-stage reboiling furnace 302, a medium-stage upper water cooler 303, a medium-stage overhead reflux tank 304, a medium-stage overhead reflux pump 305, a medium-stage bottom tower pump 306, and a medium-stage lower water cooler 307; the heavy component removal tower 301 is respectively connected with a front-stage lower water cooler 209 and an intermediate-stage reboiling furnace 302 of the front-stage separation device 200, the heavy component removal tower 301, an intermediate-stage upper water cooler 303, an intermediate-stage tower top reflux tank 304 and an intermediate-stage tower top reflux pump 305 are sequentially and circularly connected, and the heavy component removal tower 301, an intermediate-stage tower bottom pump 306 and an intermediate-stage lower water cooler 307 are sequentially connected; the MTBE is subjected to heavy component separation through the de-heavy tower 301, the separated gas-liquid mixture is cooled through the intermediate upper water cooler 303, then is sent to the intermediate tower top reflux tank 304 for standing, then is sent to the intermediate tower top reflux pump 305 for pressurization and then is returned to the de-heavy tower 301 for circular separation, the MTBE is separated before being returned to the de-heavy tower 301, one part of the MTBE is used as the feed of the on-line mixer 100 to be mixed with the liquefied gas for circular use, and the rest part of the MTBE is sent to the MTBE storage tank for storage; the rest heavy components enter a de-weighting tower 301, are pressurized by a middle-stage tower bottom pump 306 at the bottom of the tower, and are cooled by a middle-stage water cooler 307 and then are recovered; the intermediate-stage reboiling furnace 302 heats the mixture in the de-heavy tower 301 by steam, and the heated condensed water is used as a heat source of the catalytic de-heavy tower 301, so that the steam consumption can be further reduced.

When the content of five carbon in the MTBE storage tank reaches a preset value, for example, when the content of five carbon is greater than 20%, the MTBE in the MTBE storage tank is introduced into a rear separation device 400 for five carbon separation, fig. 4 is a schematic structural diagram of the rear separation device 400 according to the present invention, and referring to fig. 4, the rear separation device 400 includes a light component removal column 401, a rear reboiling furnace 402, a rear upper water cooler 403, a rear overhead reflux tank 404, a rear overhead reflux pump 405, a rear bottom pump 406, and a rear lower water cooler 407; the light component removal tower 401 is connected with a middle-stage lower water cooler 307 and a rear-stage heavy boiling furnace 402 of the middle-stage separation device 300 respectively, the light component removal tower 401, a rear-stage upper water cooler 403, a rear-stage tower top reflux tank 404 and a rear-stage tower top reflux pump 405 are sequentially and circularly connected, and the light component removal tower 401, the rear-stage tower bottom pump 406 and the rear-stage lower water cooler 407 are sequentially connected; the MTBE is subjected to carbon five separation through the light component removal tower 401, the separated gas-liquid mixture is cooled through a rear-stage upper water cooler 403, then is placed in a rear-stage overhead reflux tank 404 and is sent to a rear-stage overhead reflux pump 405 to be pressurized and then is returned to the light component removal tower 401 for circular separation, the carbon five components are separated before returning to the light component removal tower 401, the MTBE after carbon five separation is pressurized through a rear-stage bottom pump 406 and is cooled through a rear-stage lower water cooler 407 and then is recovered, and the MTBE is used as a feed of the on-line mixer 100 to be mixed with the liquefied gas for circular use; the subsequent stage reboiling furnace 402 heats the mixture in the light component removal tower 401 by steam, and the heated condensed water is used as a heat source of the catalytic light component removal tower 401, so that the steam consumption can be further reduced.

Compared with the mode of desulfurizing by adopting alkali liquor in the prior art, the liquefied gas desulfurization system disclosed by the embodiment of the invention has the advantages that the flow is relatively simple, the operation is easy, the desulfurization effect is obvious, the attached carbon five-component can be obtained and used as a production raw material of other products, and the benefit is improved.

Based on the above embodiments, the present invention further provides a liquefied gas desulfurization method, which is applied to the liquefied gas desulfurization system described in any of the above embodiments, referring to fig. 5, fig. 5 is a schematic flow diagram of the liquefied gas desulfurization method described in the present invention, and the liquefied gas desulfurization method includes the following steps:

s101: and respectively introducing the liquefied gas and the MTBE into the in-line mixer for mixing, so that the sulfur content in the liquefied gas is transferred into the MTBE.

S102: and the mixed mixture enters the front-stage separation device to separate liquefied gas from MTBE, and the separated liquefied gas is sent to a gas separation device.

In the embodiment of the present invention, the separation of the liquefied gas and the MTBE specifically: respectively introducing liquefied gas and MTBE into an online mixer for mixing, heating the mixed mixture into a heat exchanger to a reaction temperature, conveying the heated mixture to a desulfurizing tower for separation, sequentially passing the separated gas-liquid mixture through a front-stage air cooler and a front-stage upper water cooler, then entering a front-stage tower top reflux tank, respectively carrying out air cooling and water cooling on the gas-liquid mixture at the top of the desulfurizing tower by the front-stage air cooler and the front-stage upper water cooler to condense acidic water therein, separating the acidic water in the front-stage tower top reflux tank, storing tower top materials by the front-stage tower top reflux tank, returning the rest products to the desulfurizing tower through a front-stage tower top reflux pump for cyclic separation, and separating the liquefied gas through the front-stage tower top reflux pump before returning to the desulfurizing tower and conveying the liquefied; the separated MTBE is pressurized by a front-stage tower bottom pump, then sequentially subjected to heat exchange by a heat exchanger and cooling by a front-stage water cooler and then output to a middle-stage separation device.

S103: and (3) introducing the MTBE into a middle-stage separation device for carrying out de-heavy treatment, separating heavy components containing high sulfur at the bottom of the tower and intermittently sending the heavy components out of the middle-stage separation device, wherein a part of the MTBE at the top of the tower is used as a feed of an on-line mixer to be mixed with the liquefied gas for recycling, and the redundant part of the MTBE is sent to an MTBE storage tank for storage.

In the embodiment of the invention, the step of introducing the MTBE into the intermediate-grade separation device for de-weighting treatment specifically comprises the following steps: the MTBE is subjected to heavy component separation through a de-weighting tower, a separated gas-liquid mixture is cooled through a middle-level upper water cooler and then is placed in a middle-level tower top reflux tank for standing, then the gas-liquid mixture is sent to a middle-level tower top reflux pump for pressurization and then is returned to the de-weighting tower for cyclic separation, the MTBE is separated before being returned to the de-weighting tower, one part of the MTBE is used as the feed of an on-line mixer to be mixed with the liquefied gas for cyclic use, and the rest of the MTBE is sent to an MTBE storage tank for storage; and the rest heavy components enter a de-weighting tower, are pressurized by a middle-stage tower bottom pump at the bottom of the tower and are cooled by a middle-stage water cooler and then are recovered.

S104: when the content of the five carbon atoms in the MTBE storage tank reaches a preset value, the MTBE in the MTBE storage tank is introduced into a rear-stage separation device for five carbon atoms separation, and the MTBE after the five carbon atoms separation is used as a feed of an on-line mixer to be mixed with the liquefied gas for recycling.

In the embodiment of the invention, when the content of the five carbon atoms in the MTBE storage tank is more than 20%, the MTBE in the MTBE storage tank is passed to a back-stage separation device for separating the five carbon atoms.

The method is characterized in that the MTBE in the MTBE storage tank is introduced into a rear-stage separation device for carbon five separation, and specifically comprises the following steps: and MTBE is subjected to carbon five separation through a light component removal tower, a separated gas-liquid mixture is cooled through a rear-stage upper water cooler and then is placed in a rear-stage tower top reflux tank for standing, then the gas-liquid mixture is sent to a rear-stage tower top reflux pump for pressurization and then is returned to the light component removal tower for cyclic separation, the carbon five components are separated before returning to the light component removal tower, the MTBE after the carbon five is separated is subjected to pressurization through a rear-stage tower bottom pump and cooling through a rear-stage lower water cooler and then is recovered, and the MTBE is used as a feed of an on-line mixer and is mixed with the liquefied gas for cyclic use.

The liquefied gas desulfurization system described in the above embodiment may execute the liquefied gas desulfurization method provided in the embodiments of the present invention, and the liquefied gas desulfurization method has corresponding functional components and beneficial effects of the liquefied gas desulfurization system described in the above embodiments.

In the above embodiments provided by the present invention, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the modules is merely a logical division, and other divisions may be realized in practice, for example, a plurality of modules or components may be combined or integrated into another system, or some features may be omitted, or not executed.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the foregoing detailed description, or equivalent changes may be made in some of the features of the embodiments. All equivalent structures made by using the contents of the specification and the attached drawings of the invention can be directly or indirectly applied to other related technical fields, and are also within the protection scope of the patent of the invention.

Claims

1. A liquefied gas desulfurization system, comprising: the online mixer, the preceding stage separation device, the middle stage separation device and the rear stage separation device are sequentially connected; respectively introducing the liquefied gas and the MTBE into the online mixer for mixing, transferring sulfur components in the liquefied gas into the MTBE, introducing the mixed mixture into the front-stage separation device for separation, sending the separated liquefied gas to the gas separation device, introducing the MTBE into the middle-stage separation device for heavy component removal treatment, separating heavy components containing high sulfur at the bottom of the tower and intermittently sending the heavy components out of the middle-stage separation device, mixing part of the MTBE positioned at the top of the tower with the liquefied gas as a feed of the online mixer for recycling, sending the rest part of the MTBE to the MTBE storage tank for storage, introducing the MTBE in the MTBE storage tank into the rear-stage separation device for five-carbon separation when the content of the five-carbon in the MTBE storage tank reaches a preset value, and mixing the MTBE after the five-carbon is separated with the liquefied gas as a feed of the online mixer for recycling.

2. A liquefied gas desulfurization system according to claim 1, characterized in that: the pre-stage separation device comprises a heat exchanger, a desulfurizing tower, a pre-stage reboiling furnace, a pre-stage tower bottom pump, a pre-stage air cooler, a pre-stage upper water cooler, a pre-stage tower top reflux tank, a pre-stage tower top reflux pump and a pre-stage lower water cooler; the heat exchanger is respectively connected with the online mixer, the desulfurizing tower and the preceding-stage lower water cooler; the desulfurizing tower, the preceding-stage air cooler, the preceding-stage upper water cooler, the preceding-stage tower top reflux tank and the preceding-stage tower top reflux pump are sequentially and circularly connected; the fore-stage tower bottom pump is respectively connected with the heat exchanger and the desulfurizing tower; the desulfurizing tower is connected with the front stage reboiling furnace; respectively introducing liquefied gas and MTBE into the online mixer for mixing, allowing the mixed mixture to enter a heat exchanger, heating to a reaction temperature, conveying to a desulfurization tower for separation, allowing the separated gas-liquid mixture to sequentially pass through a front-stage air cooler and a front-stage upper water cooler and then enter a front-stage tower top reflux tank, allowing the front-stage air cooler and the front-stage upper water cooler to respectively perform air cooling and water cooling on the gas-liquid mixture at the top of the desulfurization tower to condense acidic water therein, separating the acidic water in the front-stage tower top reflux tank, allowing the front-stage tower top reflux tank to store tower top materials, returning the rest products to the desulfurization tower through a front-stage tower top reflux pump for cyclic separation, and allowing the liquefied gas to be separated by the front-stage tower top reflux pump before returning to the desulfurization tower and conveying the liquefied; and the separated MTBE is pressurized by the front-stage tower bottom pump, sequentially subjected to heat exchange by the heat exchanger and cooled by the front-stage water cooler and then output to the intermediate-stage separation device.

3. A liquefied gas desulfurization system according to claim 1, characterized in that: the middle-stage separation device comprises a heavy component removal tower, a middle-stage heavy boiling furnace, a middle-stage upper water cooler, a middle-stage tower top reflux tank, a middle-stage tower top reflux pump, a middle-stage tower bottom pump and a middle-stage lower water cooler; the heavy component removal tower is respectively connected with the preceding stage separation device and the intermediate stage reboiling furnace, the heavy component removal tower, the intermediate stage upper water cooler, the intermediate stage tower top reflux tank and the intermediate stage tower top reflux pump are sequentially and circularly connected, and the heavy component removal tower, the intermediate stage tower bottom pump and the intermediate stage lower water cooler are sequentially connected; MTBE is subjected to heavy component separation through the de-weighting tower, the separated gas-liquid mixture is cooled through a middle-level upper water cooler and then enters a middle-level tower top reflux tank for standing, then the gas-liquid mixture is sent to a middle-level tower top reflux pump to be pressurized and then returns to the de-weighting tower for cyclic separation, the MTBE is separated before returning to the de-weighting tower, one part of the MTBE is used as the feed of an on-line mixer to be mixed with the liquefied gas for cyclic use, and the rest of the MTBE is sent to an MTBE storage tank for storage; and the rest heavy components enter a de-weighting tower, are pressurized by a middle-stage tower bottom pump at the bottom of the tower and are cooled by a middle-stage water cooler and then are recovered.

4. The liquefied gas desulfurization system according to claim 3, wherein when the content of MTBE in the MTBE storage tank is more than 20%, the MTBE in the MTBE storage tank is passed to a back-stage separation device to be subjected to carbon five separation.

5. A liquefied gas desulfurization system according to claim 4, characterized in that: the rear-stage separation device comprises a light component removal tower, a rear-stage reboiling furnace, a rear-stage upper water cooler, a rear-stage tower top reflux tank, a rear-stage tower top reflux pump, a rear-stage tower bottom pump and a rear-stage lower water cooler; the light component removal tower is connected with a middle-stage lower water cooler and a rear-stage reboiling furnace of a middle-stage separation device respectively, the light component removal tower, a rear-stage upper water cooler, a rear-stage tower top reflux tank and a rear-stage tower top reflux pump are sequentially and circularly connected, and the light component removal tower, a rear-stage tower bottom pump and the rear-stage lower water cooler are sequentially connected; and MTBE is subjected to carbon five separation through the light component removal tower, the separated gas-liquid mixture is cooled through a rear-stage upper water cooler and then enters a rear-stage overhead reflux tank for standing, then the gas-liquid mixture is sent to a rear-stage overhead reflux pump for pressurization and then returns to the light component removal tower for cyclic separation, the carbon five components are separated before returning to the light component removal tower, the MTBE after the carbon five separation is subjected to pressurization through a rear-stage tower bottom pump and cooling through a rear-stage lower water cooler and then is recovered, and the MTBE is used as a feed of an on-line mixer and is mixed with the liquefied gas for cyclic use.

6. A liquefied gas desulfurization method applied to a liquefied gas desulfurization system as set forth in any one of claims 1 to 5, comprising:

7. A liquefied gas desulfurization method according to claim 6, characterized in that the separation of the liquefied gas and MTBE is specifically:

8. The liquefied gas desulfurization method according to claim 6, wherein the MTBE is introduced into the intermediate separation device for heavy removal treatment, specifically:

9. A method for sweetening a liquefied gas according to claim 8, wherein the method further comprises: when the content of the five carbon in the MTBE storage tank is more than 20%, the MTBE in the MTBE storage tank is fed to a rear-stage separation device for five carbon separation.

10. The liquefied gas desulfurization method according to claim 9, wherein the step of passing the MTBE in the MTBE storage tank to a back-stage separation device for separation of five carbons comprises: