CN103160331A - System and process for preparing PTA/PET (Pure Terephthalic Acid/Polyethylene Terephthalate) based on pyrolysis and gasification devices - Google Patents

Abstract

The invention provides a system and process for preparing PTA/PET based on a pyrolysis gasification device, including a pyrolysis gasification system A and a coal-based PTA/PET system B; the coal-based PTA/PET system B includes a coal tar hydrorefining unit , naphtha refining unit, methanol synthesis unit, methanol-naphtha reforming/coupling unit, ethylene glycol synthesis unit, PTA synthesis unit, PET synthesis unit; purified tar and synthesis gas prepared by coal pyrolysis gasification system Synthesize naphtha, methanol, and ethylene glycol as raw materials, and then carry out reforming and coupling reactions of methanol and naphtha to obtain PX, which is sent to the PTA synthesis unit for reaction to obtain PTA; at the same time, ethylene glycol and the obtained PTA It is fed into a PET synthesis unit and undergoes polycondensation to obtain PET; the present invention provides a novel preparation system and process for coal-based polyester, which can alleviate oil pressure and reduce process production costs.

Description

A system and process for preparing PTA/PET based on a pyrolysis gasification device

technical field

The invention relates to the technical field of coal chemical industry, in particular to a system and process for preparing PTA/PET based on a pyrolysis gasification device.

Background technique

PTA (terephthalic acid) is an important chemical raw material, mainly used in the synthesis of PET (polyethylene terephthalate). PET is a thermoplastic polyester with excellent performance. It is mainly used in polyester resin, beverage packaging bottles, films and other industries. It is recognized as a key high-tech engineering material in the world. The future market is mainly aircraft structural materials, wind power blades, automotive leaf springs and drive shafts wait. At present, the main raw materials involved in the preparation of PTA/PET are PX (xylene) and ethylene glycol. The traditional supply route of these two materials comes from crude oil refining, and the domestic gap has always been large. In 2012, my country's net import of PX was 6.09 million tons, and the dependence on foreign countries exceeded 50%. There may still be a long-term shortage in the future. The traditional PX production route mainly comes from the subsidiary of large-scale refineries, with high investment threshold and limited material balance. The decline in the proportion of crude oil in global energy consumption in the future will increase the shortage of aromatics and PX. In 2012, my country's net import of ethylene glycol hit a record high of 7.95 million tons, and its dependence on foreign countries exceeded 70%. In the next two years, domestic ethylene glycol consumption will grow by more than 10%. It is estimated that by 2015, my country's ethylene glycol production capacity will reach 5.5 million tons, and the demand will reach about 11 million tons. At that time, my country's ethylene glycol gap will still be about 5.5 million tons, and it will need to rely on imports, and use petroleum to produce ethylene glycol The cost is high.

Therefore, most of the PX and ethylene glycol raw materials involved in the preparation of PTA/PET in my country currently rely on imports, and most of the technical routes are based on crude oil refining, resulting in higher costs and increased pressure on the utilization of petroleum resources. my country's coal resources are not fully utilized.

Contents of the invention

The purpose of the present invention is to overcome the defects of the prior art, to provide a system and process for preparing PTA/PET based on a pyrolysis gasification device, to prepare coal-based PTA/PET with coal pyrolysis and gasification as the core, and to provide a coal-based polyester A new type of preparation scheme can relieve oil pressure and reduce process production costs.

To achieve the above object, the present invention adopts the following technical solutions:

A system for preparing PTA/PET based on pyrolysis gasification device, including pyrolysis gasification system A and coal-based PTA/PET system B; coal-based PTA/PET system B includes coal tar hydrorefining unit, naphtha refining unit unit, methanol synthesis unit, methanol-naphtha reforming/coupling unit, ethylene glycol synthesis unit, PTA synthesis unit, PET synthesis unit; the input port of coal tar hydrotreating unit is connected to the tar outlet of pyrolysis gasification system A The output port of the coal tar hydrorefining unit is connected with the input port of the naphtha refining unit; the synthesis gas outlet of the pyrolysis gasification system A is divided into two routes, one is connected with the input port of the methanol synthesis unit, and the other is connected with the ethylene glycol The input port of the synthesis unit is connected, the output port of the naphtha refining unit and the output port of the methanol synthesis unit are respectively connected with the input port of the methanol-naphtha reforming/coupling unit, and the output port of the methanol-naphtha reforming/coupling unit is connected with the PTA synthesis unit The input port of the unit is connected, and the output port of the ethylene glycol synthesis unit and the output port of the PTA synthesis unit are respectively connected with the input port of the PET synthesis unit.

The tar outlet of the pyrolysis gasification system A is divided into two paths, one path is connected to the input port of the coal tar hydrofining unit, and the other path is connected to the input port of the aromatics extraction unit; the output port of the methanol-naphtha reforming/coupling unit is The port is connected to a PX refining unit, the output port of the PX refining unit is connected to the input port of the PTA synthesis unit, the output port of the aromatics extraction unit and the output port of the methanol-naphtha reforming/coupling unit are respectively connected to the input port of the PX refining unit.

The pyrolysis gasification system A includes a pyrolysis unit and a gasification unit; the pyrolysis unit includes a pyrolysis furnace, and the gas outlet of the pyrolysis furnace is sequentially connected with a first gas-solid separator, a gas-liquid separator, an electric tar catcher and a second A gas purifier; the liquid outlet of the gas-liquid separator is connected to an oil-water separator and a tar purifier in sequence, and the outlet of the tar purifier is connected to the input port of the coal tar hydrotreating unit; the solid outlet of the pyrolysis furnace is connected to a semi-coke splitter; The gasification unit includes a gasification furnace, the gasification gas outlet of the gasification furnace is connected with a second gas-solid separator and a second gas purifier in sequence, and the outlet of the second gas purifier and the outlet of the first gas purifier are separated from the syngas respectively The outlet of the syngas separator is connected with the input port of the methanol synthesis unit, the ethylene glycol synthesis unit and the input port of the _H2 separation unit respectively; The inlet of the gasifier is connected.

The gas outlet of the first gas purifier is divided into two paths, one path communicates with the inlet of the synthesis gas separator, and the other path communicates with the heat carrier gas inlet of the pyrolysis furnace.

The gas outlet of the second gas-solid separator is divided into two paths, one path communicates with the inlet of the second gas purifier, and the other path communicates with the heat carrier gas inlet of the pyrolysis furnace;

The solid outlet of the first gas-solid separator communicates with the inlet of the semi-coke splitter.

The outlet of the synthesis gas separator is divided into two paths, one path is respectively connected with the input port of the methanol synthesis unit and the input port of the ethylene glycol synthesis unit, and the other path is connected with the _H2 separation unit, and the _H2 separation unit outlet is connected with the coal tar hydrorefining unit. The unit hydrogen inlet is connected.

A coal preparation unit is included, the gasifier is provided with a raw coal inlet, and the raw coal inlet of the gasifier is connected with the coal preparation unit.

A kind of technology that prepares PTA/PET based on pyrolysis gasification device, comprises the following steps:

(1) Feed the raw coal into the pyrolysis furnace for pyrolysis at 500°C-800°C to produce raw coal gas and semi-coke;

(2) The raw coal gas generated by pyrolysis in step (1) is sent to the gas-solid separator for dedusting of the raw gas, and the powder coke and dedusting gas are separated through the gas-solid separator, and the separated dedusting gas is sent into the gas-liquid separator , through which the gaseous products and liquid products are separated, and the gaseous products are sent to the electric tar catcher to remove the remaining tar, and then sent to the gas purifier for treatment to obtain purified gas, and the liquid products are sent to the oil-water separator for oil-water separation. Separation, the separated tar is sent to the tar purifier, and purified to obtain purified tar;

Part of the semi-coke produced by pyrolysis in step (1) is discharged as a product, and part of the semi-coke is sent to the gasification furnace for semi-coke gasification reaction at 800°C-1300°C, and the gasification gas generated by gasification is sent to gas-solid separation The dedusting gasification gas is obtained after dedusting and purification by the gas-solid separator, and the dedusting gasification gas is sent to the gas purifier for purification to obtain purified gasification gas;

(3) Mix the purified gasification gas obtained by the gas purifier in step (2) with the purified coal gas obtained by the gas purifier, and then send it to the synthesis gas separator to obtain synthesis gas;

(4) Part of the purified tar obtained in step (2) is sent to the aromatics extraction unit to extract light aromatics BTX, and the remaining part of the purified tar is sent to the coal tar hydrorefining unit for hydrorefining and treatment of coal tar. The naphtha obtained after the coal tar hydrorefining unit is sent to the naphtha refining unit to obtain the naphtha raw material required by the methanol-naphtha reforming/coupling unit;

Part of the synthesis gas obtained in step (3) is sent to the methanol synthesis unit to obtain a methanol mixture and sent to the methanol refining unit to obtain methanol, and the methanol and naphtha output from the naphtha refining unit are sent to the methanol-naphtha reforming/ Coupling unit, reforming and coupling reaction of methanol and naphtha to obtain PX mixture; the remaining synthesis gas obtained in step (3) is sent to the ethylene glycol synthesis unit, and the ethylene glycol mixture is sent to the ethylene glycol refining unit , to get ethylene glycol;

(5) Send the PX mixture obtained in step (4) and the light aromatics BTX obtained by the aromatics extraction unit to the PX refining unit, and PX is obtained after refining, and the PX is sent to the PTA synthesis unit, and the PTA mixture obtained by the reaction, the PTA mixture Send to PTA refining unit to get PTA;

(6) The ethylene glycol obtained in step (4) and the PTA obtained in step (5) are sent to the PET synthesis unit for polycondensation to obtain PET.

Synthesis gas is obtained through the synthesis gas separator in step (3), part of which is sent to the methanol synthesis unit and ethylene glycol synthesis unit for the production of methanol and ethylene glycol, and the other part of the synthesis gas is sent to the H ₂ separation unit to separate H ₂ Send into the coal tar hydrorefining unit, as the coal tar hydrorefining unit in the step (4) carries out the hydrorefining of coal tar and the source of part H ₂ source.

The present invention is based on the system and method for preparing PTA/PET by a pyrolysis gasification device. The coal pyrolysis gasification system is the core, and the purified tar and synthesis gas prepared by the coal pyrolysis gasification system are used as raw materials to synthesize naphtha and methanol respectively. And ethylene glycol, then carry out the reforming and coupling reaction of methanol and naphtha to obtain PX, PX is sent to the PTA synthesis unit, and the reaction is to obtain PTA; at the same time, ethylene glycol and the obtained PTA are sent to the PET synthesis unit, after polycondensation, Obtain PET; prepare coal-based PTA/PET with coal pyrolysis and gasification as the core, and provide a new preparation system and process for coal-to-polyester, which can relieve oil pressure and reduce process production costs.

Further, pyrolysis-gasification coupling technology uses pyrolysis semi-coke as gasification raw material, gasification gas or pyrolysis coal gas is used as heat carrier to provide heat for pyrolysis furnace, no need to add gas, energy is recycled, and self-balancing is achieved in terms of heat and efficient use of energy.

Furthermore, in the pyrolysis-gasification coupling technology, the pyrolysis process uses the gasification gas produced by semi-coke gasification as the gas heat carrier, without the intervention of other gases, and the main components of the generated pyrolysis gas are CO, CH ₄ and H ₂ . Contains a small amount of N ₂ , has high calorific value and good quality. At the same time, the gasification gas contains H ₂ , CH ₄ and other active components that are beneficial to hydropyrolysis, so the yield of coal tar can be increased and more PTA raw material PX can be obtained.

Furthermore, PX was directly prepared from the primary products of methanol and naphtha obtained through coal pyrolysis-gasification coupling, realizing the coupling between products.

Description of drawings

FIG. 1 is a system structure block diagram of Embodiment 1 of the present invention.

Fig. 2 is a structural block diagram of the pyrolysis gasification system A in Fig. 1 .

Fig. 3 is a system structure block diagram of Embodiment 2 of the present invention.

Fig. 4 is a structural block diagram of the pyrolysis-gasification coupling unit in Fig. 3 .

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Embodiment one: as shown in Figure 1, the present invention comprises coal preparation unit 1, pyrolysis gasification system A and coal-based PTA-PET system B.

The pyrolysis gasification system A includes a pyrolysis unit 2 and a gasification unit 6 coupled together, wherein the pyrolysis unit, as shown in Figure 2, includes a pyrolysis furnace 15, a first gas-solid separator 16, and a gas-liquid separator 17 , an electric tar catcher 18, a first gas purifier 19, an oil-water separator 20, a tar purifier 21 and a semi-coke splitter 22; the gasification unit includes a gasifier 23, a second gas-solid separator 24, a second gas Purifier 25, syngas separator 26 and _H2 separation unit 27. The components are connected through pipelines as shown in Figure 2, and the two output ends of the specific pyrolysis furnace 15 are respectively connected to the input end of the first gas-solid separator 16 and the semi-coke splitter 22 through pipelines The input end of the first gas-solid separator 16 is connected to the input end of the semi-coke splitter 22 through a pipeline, and the output end of the gaseous separation of the first gas-solid separator 16 is connected through a pipeline At the input end of the gas-liquid separator 17, the output end of the gaseous separation of the gas-liquid separator 17 is connected to the input end of the electric tar catcher 18 through a pipeline, and the output end of the electric tar catcher 18 is connected to the first tar catcher through a pipeline. The input end of a gas purifier 19, the output end of the liquid separation of the gas-liquid separator 17 is connected to the input end of the oil-water separator 20 through a pipeline, and the tar output end of the oil-water separator 20 is connected to the tar purifier through a pipeline 21, the output end of the semi-coke splitter 22 is connected to the input end of the gasifier 23 through a pipeline, and the output end of the gasifier 23 is connected to the input end of the second gas-solid separator 24 through a pipeline. The output end of the second gas-solid separator 24 is respectively connected to the input end of the pyrolysis furnace 15 and the input end of the second gas purifier 25 through pipelines, and the input end of the synthesis gas separator 26 is respectively connected to the first gas through pipelines. The output end of the purifier 19, the output end of the second gas purifier 25, and the output end of the synthesis gas separator 26 are connected to the H ₂ separation unit 27 through pipelines.

Process flow of pyrolysis gasification system A: raw coal in coal preparation unit 1 is washed and screened, dried or undergoes a series of pretreatments, such as different atmospheres, swelling treatment, etc., to obtain raw coal a that can meet the process requirements. The raw coal a is sent into the pyrolysis furnace 15, and the raw coal a undergoes a pyrolysis reaction under the condition of 500°C-800°C. Raw coal gas (containing CO, H ₂ , CH ₄ , CO ₂ , O ₂ , H ₂ S, tar, powder coke and other components) is produced from the upper part of the pyrolysis furnace 15, and pyrolysis semi-coke is produced at the bottom of the pyrolysis furnace . The raw coal gas generated by the pyrolysis furnace 15 is sent to the first gas-solid separator 16 for dust removal of the raw coal gas. The coke powder is separated through the first gas-solid separator 16 and returned to the semi-coke splitter 22 . The dedusted coal gas separated by the first gas-solid separator 16 is sent to the gas-liquid separator 17, through which the gaseous products and liquid products are separated, and the gaseous products are sent to the electric tar catcher 18 to further remove the remaining tar therein , sent to the first gas purifier 19 to remove gas impurities containing nitrogen, sulfur and other components, to obtain purified gas, wherein the liquid product is sent to the oil-water separator 20 for oil-water separation, and the separated tar is sent to the tar purifier 21. Further purification to obtain purified tar b. The water separated by the oil-water separator 20 can be recycled for industrial water use after treatment, basically realizing zero sewage discharge. Purified tar b is sent to coal-based PTA-PET system B.

After the pyrolysis semi-coke obtained from the bottom of the pyrolysis furnace 15 is sent to the semi-coke splitter 22 through the pipeline, part of the split pyrolysis semi-coke is sent to the semi-coke comprehensive utilization industry, and the part after being split by the semi-coke splitter 22 The pyrolysis semi-coke is sent into the gasification furnace 23 together with the gasification agent d (O ₂ , air or water vapor, etc.), and the semi-coke gasification reaction is carried out in the range of 800-1300°C, and the gasification gas coming out of the gasification furnace 23 (including CO, H ₂ , CO ₂ , CH ₄ , O ₂ , H ₂ S, ash, etc.) is sent to the second gas-solid separator 24, and the dust-removed gasification gas after dedusting and purification by the second gas-solid separator 24 , a small part is sent to the pyrolysis furnace 15 to provide the heat required for pyrolysis, and the rest is sent to the second gas purifier 25 to remove gases containing sulfur, nitrogen and other components to obtain purified gasification gas after purification. The purified gasification gas obtained by the second gas purifier 25 is mixed with the purified coal gas obtained by the first gas purifier 19, and then sent to the syngas separator 26 to obtain syngas c (CO and H ₂ ), the syngas c part The H ₂ is sent to the H 2 separation unit 27 for pressure swing adsorption or membrane separation, and the obtained H ₂ is used as the source of the H ₂ in the hydrorefining of coal tar.

In order to further improve the recycling rate of heat in the system, the present invention introduces part of the dedusted gasification gas separated by the second gas-solid separator 24 into the pyrolysis furnace 15 through pipelines, so as to circulate and supply the heat required for pyrolysis.

In addition, the purified coal gas obtained by the first gas purifier 19 can be sent to the pyrolysis furnace 15 to solve the problem of insufficient heat supply of the pyrolysis furnace due to insufficient gasification or the gasification gas is mainly used for polygeneration.

In order to further broaden the scope of application of coal types, the gasifier is equipped with a raw coal inlet, which is connected to the coal preparation unit. The raw coal can be processed by the coal preparation unit 1 to obtain qualified raw materials for gasification. into the gasification furnace 23 to be used as a raw material for gasification alone or to participate in the gasification of semi-coke. The present invention can simultaneously take into account the flexibility of raw materials and product schemes. The advantage of the present invention is that, because the gasification gas contains _H2 , _CH4 and other activated components that are conducive to pyrolysis, providing a reducing atmosphere can realize the co-pyrolysis of raw coal and activated components such as hydrogen, and increase the yield of tar , Improve semi-focus quality. Because the semi-coke gasification gas or purified coal gas is used as the heat carrier of the pyrolysis furnace, the pyrolysis gas hardly contains N ₂ , and the pyrolysis gas has high calorific value and good quality. At the same time, the pyrolysis process of the present invention is flexible, and hydrogenation or catalysts can be added in a pyrolysis furnace to realize hydropyrolysis or hydrogenation catalytic pyrolysis.

Coal-based PTA-PET system B mainly includes aromatics extraction unit 3, coal tar hydrorefining unit 4, naphtha refining unit 5, methanol synthesis unit 7, methanol refining unit 8, methanol-naphtha reforming/coupling unit 9. Ethylene glycol synthesis unit 10, ethylene glycol refining unit 11, PX refining unit 12, PTA synthesis unit 13, PTA refining unit 14, PET synthesis unit 30, etc. Each component is connected by pipeline as shown in accompanying drawing 1, and the input end of the aromatics extraction unit 3 of coal-based PTA-PET system B and the input end of coal tar hydrorefining unit 4 are respectively connected to The output end of the purified tar b of the pyrolysis gasification unit A is specifically the output end of the tar purifier 21 connected therein. The output end of the coal tar hydrorefining unit 4 is connected to the naphtha refining unit 5 through a pipeline. The input end of the methanol synthesis unit 7 and the input end of the ethylene glycol synthesis unit 10 are respectively connected to the synthesis gas output end of the pyrolysis gasification unit A through pipelines, specifically the synthesis gas c of the synthesis gas separator 26 connected therein. The output end of the methanol synthesis unit 7 is connected to the methanol refining unit 8 through a pipeline, and the output end of the methanol refining unit 8 and the output end of the naphtha refining unit 5 are respectively connected to the methanol-naphtha heavy oil through a pipeline. The input end of the reforming/coupling unit 9 and the input end of the PX refining unit 12 are respectively connected to the output end of the aromatics extraction unit 3 and the output end of the methanol-naphtha reforming/coupling unit 9 through pipelines, and the PX refining unit 12 The output end of the PTA synthesis unit 13 is connected to the input end of the PTA synthesis unit 13 through a pipeline, and the output end of the PTA synthesis unit 13 is connected to the PTA refining unit 14 through a pipeline. The output end of the ethylene glycol synthesis unit 10 is connected to the ethylene glycol refining unit 11 through a pipeline.

Coal-based PTA-PET system B process flow: the purified tar b output from the pyrolysis gasification system A, specifically the output end of the tar purifier 21, is sent to the aromatics extraction unit 3 through the pipeline to extract light aromatics BTX etc. Part b of the purified tar is sent to the coal tar hydrofining unit 4 for hydrofining and treatment of the coal tar, wherein part of the _H2 used in the coal tar hydrofining unit 4 is derived from the synthesis gas through pressure swing adsorption or membrane separation, etc. _H2 separation unit 27. The naphtha obtained after the coal tar hydrorefining unit 4 is sent to the naphtha refining unit 5 to obtain the naphtha raw material required by the methanol-naphtha reforming/coupling unit 9 .

The synthesis gas c at the output end of the gasification unit 6 of the pyrolysis gasification system A, specifically the output end c of the synthesis gas separator 26 of the gasification unit, is partly used for synthesizing methanol and partly used for synthesizing ethylene glycol. The synthesis gas c is sent to the methanol synthesis unit 7 to obtain a methanol mixture and then sent to the methanol refining unit 8 to obtain methanol. The naphtha output from the methanol and naphtha refining unit is sent to the methanol-naphtha reforming/coupling unit 9 for reforming and coupling reactions of methanol and naphtha to obtain a PX mixture,

The PX mixture and the light aromatic hydrocarbons BTX obtained by the extraction of the aromatics extraction unit 3 are sent to the PX refining unit 12, and PX is obtained through refining, and the PX is sent to the PTA synthesis unit 13, and the PTA mixture obtained by the reaction is sent to the PTA refining unit 14 to obtain PTA realizes the basic purpose of the present invention, and the prepared PTA can be used as a raw material for the preparation of polyesters such as PET and PBT.

Further the route that the present invention prepares PET based on PTA is:

The synthesis gas c obtained through the aforementioned process is sent to the ethylene glycol synthesis unit 10 to obtain the ethylene glycol mixture and then sent to the ethylene glycol refining unit 11 to obtain ethylene glycol, and then ethylene glycol and PTA undergo polycondensation to obtain PET.

Embodiment two: as shown in Figure 3, it is a system structure block diagram of another embodiment of the present invention, in order to make the device simpler, easier to deploy and control, the present invention combines the pyrolysis furnace 15 and gasification of pyrolysis unit 2 in the accompanying drawing 1 The gasifier 23 and semi-coke splitter 22 of unit 6 are integrated in one device to realize the coupling of raw coal pyrolysis and gasification. It includes coal preparation unit 1, pyrolysis gasification coupling unit 28 and coal-based PTA-PET system B.

As shown in Figure 4, the pyrolysis gasification coupling unit 28 includes a pyrolysis gasification furnace 29, a first gas-solid separator 16, a gas-liquid separator 17, an electric tar catcher 18, a first gas purifier 19, an oil-water Separator 20, tar purifier 21, second gas-solid separator 24, second gas purifier 25, syngas separator 26 and _H2 separator 27. Each component is connected by pipeline as shown in accompanying drawing 4, and the output end of the pyrolysis section top of concrete pyrolysis gasification furnace 29 is connected to the input end of the first gas-solid separator 16 by pipeline, the second The output end of the solid separation of a gas-solid separator 16 is connected to the input end of the pyrolysis gasification furnace 29 gasification sections through a pipeline, and the output end of the gaseous separation of the first gas-solid separator 16 is connected to the gasification section through a pipeline. The input end of the gas-liquid separator 17, the output end of the gaseous separation of the gas-liquid separator 17 is connected to the input end of the electric tar catcher 18 through a pipeline, and the electric tar catcher 18 is connected to the first gas purifier 19 through a pipeline The input end of the gas-liquid separator 17 is connected to the input end of the oil-water separator 20 through a pipeline, and the tar output end of the oil-water separator 20 is connected to the input end of the tar purifier 21 through a pipeline. The output end of the top of the gasification section of the pyrolysis gasification furnace 29 is connected to the input end of the second gas-solid separator 24 through a pipeline, and the output end of the second gas-solid separator 24 is connected to the second gas purifier 25 through a pipeline The input end of the synthesis gas separator 26 is respectively connected to the output end of the first gas purifier 19 and the output end of the second gas purifier 25 through pipelines, and the output end of the synthesis gas separator 26 is connected through pipelines At the input of the H ₂ separator 27 and the coal-based PTA-PET system.

Process flow of pyrolysis gasification coupling unit 28: raw coal in coal preparation unit 1 is washed, screened, dried or undergoes a series of pretreatments (different atmosphere, swelling treatment, etc.) to obtain raw coal a that can meet the process requirements. The raw coal a is sent to the pyrolysis section of the pyrolysis gasifier 29, and the pyrolysis reaction is carried out under the condition of 500°C-800°C, and the raw coal gas (containing CO, H ₂ , CH ₄ , CO ₂ , O ₂ , H ₂ S, tar, coke powder, etc.) are sent to the first gas-solid separator 16, and impurities mixed with powder coke are separated, and the powder coke is separated by the first gas-solid separator 16 and returned to transport To the gasification section of the pyrolysis gasification furnace 29, gasification is carried out at 800-1300°C. The dedusted coal gas separated by the first gas-solid separator 16 is sent to the gas-liquid separator 17, through which the gaseous products and liquid products are separated, and the gaseous products are sent to the electric tar catcher 18 to further remove the remaining tar therein , sent to the first gas purifier 19 to remove gas impurities containing nitrogen, sulfur and other components to obtain purified coal gas, which is sent to the synthesis gas separator 26 together with the purified gasification gas output by the second gas purifier 25, wherein The liquid product is sent to the oil-water separator 20 for oil-water separation, and the separated tar is sent to the tar purifier 21 for further purification to obtain purified tar b. The water separated by the oil-water separator 20 can be recycled for industrial water use after treatment, basically realizing zero sewage discharge. Purified tar b is sent to coal-based PTA-PET preparation system B.

The gasification section of pyrolysis gasification furnace 29 conducts semi-coke gasification reaction under the condition of 800-1300°C, and the gasification gas (including CO, H ₂ , CO ₂ , CH ₄ , O ₂ , H ₂ S, ash, etc.) are sent to the second gas-solid separator 24, and the dedusted gasification gas after dedusting by the second gas-solid separator 24 is sent to the second gas purifier 25 to remove nitrogen, sulfur and other components. After the gas impurities are removed, the obtained purified gasification gas and the purified coal gas output from the first gas purifier 19 are sent to the synthesis gas separator 26 together to obtain synthesis gas c (CO and H ₂ ). Syngas c part is sent to _H2 separation unit 27 (pressure swing or membrane separation), and the obtained _H2 is used as the source of coal tar hydrorefining part _H2 .

The connection mode and process flow of the coal-based PTA-PET system B are the same as those of the coal-based PTA-PET system B in Figure 1.

In the system of this embodiment, the pyrolysis and gasification of raw coal is completed in a pyrolysis gasifier 29, and the pyrolysis and gasification of coal is realized in stages, reducing equipment and saving energy.

The present invention can flexibly select raw materials and system processes according to the needs of enterprises and users. The raw coal can be raw coal or pretreated coal. The pyrolysis technology of this process system can choose one of various forms such as drum type, fixed bed, fluidized bed, settled bed, entrained bed, and moving bed. The process can be hydropyrolysis, catalytic hydropyrolysis, co-pyrolysis with other hydrogen-containing substances, etc. Gasification technology can be selected from mature technologies such as Lurgi gasification technology, ash fusion gasification technology and U-GAS gasification technology.

In combination with the foregoing embodiments and process flow, the present invention also provides a process for preparing PTA/PET based on a pyrolysis gasification device, comprising the following steps:

(1) Feed the raw coal into the pyrolysis furnace for pyrolysis at 500°C-800°C to produce raw coal gas and semi-coke;

(2) The raw coal gas generated by pyrolysis in step (1) is sent to the gas-solid separator for dedusting of the raw gas, and the powder coke and dedusting gas are separated through the gas-solid separator, and the separated dedusting gas is sent into the gas-liquid separator , to separate the gaseous products and liquid products, and the gaseous products are sent to the electric tar catcher to remove the remaining tar, and then sent to the gas purifier for treatment to obtain purified gas, and the liquid products are sent to the oil-water separator for oil-water separation. The separated tar is sent to the tar purifier, and purified to obtain purified tar;

Part of the semi-coke produced by pyrolysis in step (1) is discharged as a product, and part of the semi-coke is sent to the gasification furnace for semi-coke gasification reaction at 800°C-1300°C, and the gasification gas generated by gasification is sent to gas-solid separation The dedusting gasification gas is obtained after dedusting and purification by the gas-solid separator, and the dedusting gasification gas is sent to the gas purifier for purification to obtain purified gasification gas;

(3) Mix the purified gasification gas obtained by the gas purifier in step (2) with the purified coal gas obtained by the gas purifier, and then send it to the synthesis gas separator to obtain synthesis gas;

(4) Part of the purified tar obtained in step (2) is sent to the aromatics extraction unit to extract light aromatics BTX, and the remaining part of the purified tar is sent to the coal tar hydrorefining unit for hydrorefining and treatment of coal tar. The naphtha obtained after the coal tar hydrorefining unit is sent to the naphtha refining unit to obtain the naphtha raw material required by the methanol-naphtha reforming/coupling unit;

Part of the synthesis gas obtained in step (3) is sent to the methanol synthesis unit to obtain a methanol mixture and sent to the methanol refining unit to obtain methanol, and the methanol and naphtha output from the naphtha refining unit are sent to the methanol-naphtha reforming/ Coupling unit, reforming and coupling reaction of methanol and naphtha to obtain PX mixture; the remaining synthesis gas obtained in step (3) is sent to the ethylene glycol synthesis unit, and the ethylene glycol mixture is sent to the ethylene glycol refining unit , to get ethylene glycol;

(5) Send the PX mixture obtained in step (4) and the light aromatics BTX obtained by the aromatics extraction unit to the PX refining unit, and PX is obtained after refining, and the PX is sent to the PTA synthesis unit, and the PTA mixture obtained by the reaction, the PTA mixture Send to PTA refining unit to get PTA;

(6) Polycondensate the ethylene glycol obtained in step (4) and the PTA obtained in step (5) to obtain PET.

As a further optimization scheme of the method of the present invention, the synthesis gas is obtained through the synthesis gas separator in step (3), part of which is sent to the methanol synthesis unit and the ethylene glycol synthesis unit for the production of methanol and ethylene glycol, and the other part of the synthesis gas is sent to The H ₂ separation unit separates H ₂ and sends it to the coal tar hydrorefining unit as the source of part of H ₂ when the coal tar hydrorefining unit performs coal tar hydrorefining and treatment in step (4).

The present invention takes the medium and low temperature pyrolysis-gasification coupling of coal as the core to prepare coal-based PTA (terephthalic acid) and PET (polyethylene terephthalate). The new process of high-efficiency gasification coupling of semi-coke to prepare PTA and PET is an optimized integration and integration of coal-based energy and chemical processes that efficiently utilize materials and energy.

Claims (10)

1. A system for preparing PTA/PET based on a pyrolysis gasification device, characterized in that: comprising a pyrolysis gasification system A and a coal-based PTA/PET system B; Coal-based PTA/PET system B includes coal tar hydrorefining unit (4), naphtha refining unit (5), methanol synthesis unit (7), methanol-naphtha reforming/coupling unit (9), ethylene glycol Alcohol synthesis unit (10), PTA synthesis unit (13), PET synthesis unit (30); The input port of the coal tar hydrofining unit (4) is connected with the tar outlet of the pyrolysis gasification system A, and the output port of the coal tar hydrofining unit (4) is connected with the input port of the naphtha refining unit (5); The synthesis gas outlet of degasification system A is divided into two paths, one path is connected with the input port of methanol synthesis unit (7), the other path is connected with the input port of ethylene glycol synthesis unit (10), and the output port of naphtha refining unit (5) and the output port of the methanol synthesis unit (7) are respectively connected to the input port of the methanol-naphtha reforming/coupling unit (9), and the output port of the methanol-naphtha reforming/coupling unit (9) is connected to the PTA synthesis unit (13) The input port is connected, and the output port of the ethylene glycol synthesis unit (10) and the output port of the PTA synthesis unit (13) are respectively communicated with the input port of the PET synthesis unit (30). 2. The system for preparing PTA/PET based on the pyrolysis gasification device according to claim 1, characterized in that: the tar outlet of the pyrolysis gasification system A is divided into two paths, one path is connected with the coal tar hydrorefining unit (4) The input port is connected, and the other is connected to the input port of the aromatics extraction unit (3); the output port of the methanol-naphtha reforming/coupling unit (9) is connected to the PX refining unit (12), and the PX refining unit (12 ) output port is connected with the input port of the PTA synthesis unit (13), the output port of the aromatics extraction unit (3) and the output port of the methanol-naphtha reforming/coupling unit (9) are respectively connected with the input port of the PX refining unit (12) . 3. The system for preparing PTA/PET based on the pyrolysis gasification device according to claim 1 or 2, characterized in that: the pyrolysis gasification system A comprises a pyrolysis unit and a gasification unit; The pyrolysis unit includes a pyrolysis furnace (15), and the gas outlet of the pyrolysis furnace (15) is sequentially connected with a first gas-solid separator (16), a gas-liquid separator (17), an electric tar catcher (18) and a first The gas purifier (19); the liquid outlet of the gas-liquid separator (17) is sequentially connected to the oil-water separator (20), the tar purifier (21), and the outlet of the tar purifier (21) is connected to the coal tar hydrorefining unit (4) The input port is connected; the solid outlet of the pyrolysis furnace (15) is connected with a semi-coke splitter (22); The gasification unit includes a gasification furnace (23), the gasification gas outlet of the gasification furnace (23) is sequentially connected with a second gas-solid separator (24), a second gas purifier (25), and a second gas purifier The outlet of (25) and the outlet of the first gas purifier (19) are respectively connected with the inlet of the synthesis gas separator (26), and the outlet of the synthesis gas separator (26) is respectively connected with the input port of the methanol synthesis unit (7) and the ethylene glycol synthesis unit (10) The input port is connected; The outlet of the semi-coke splitter (22) is divided into two paths, one is used as the semi-coke outlet, and the other is connected with the gasifier (23) inlet. 4. The system for preparing PTA/PET based on a pyrolysis gasification device according to claim 3, characterized in that: the gas outlet of the first gas purifier (19) is divided into two paths, and one path is connected with the synthesis gas separator ( 26) The inlet is connected, and the other is connected with the heat carrier gas inlet of the pyrolysis furnace (15). 5. The system for preparing PTA/PET based on pyrolysis gasification device according to claim 3, characterized in that: the gas outlet of the second gas-solid separator (24) is divided into two paths, one path is connected with the second gas purification The inlet of the device (25) is communicated, and the other is communicated with the heat carrier gas inlet of the pyrolysis furnace (15). 6. The system for preparing PTA/PET based on a pyrolysis gasification device according to claim 3, characterized in that: the solid outlet of the first gas-solid separator (16) communicates with the inlet of the semi-coke splitter (22). 7. The system for preparing PTA/PET based on a pyrolysis gasification device according to claim 3, characterized in that: the outlet of the synthesis gas separator (26) is divided into two paths, and one path is connected with the methanol synthesis unit (7) respectively The input port is connected to the input port of the ethylene glycol synthesis unit (10), the other is connected to the _H2 separation unit (27), and the outlet of the _H2 separation unit (27) is connected to the hydrogen inlet of the coal tar hydrorefining unit (4). 8. The system for preparing PTA/PET based on a pyrolysis gasification device according to claim 3, characterized in that: it includes a coal preparation unit (1), the outlet of the coal preparation unit is divided into two routes, and one route is connected to the pyrolysis furnace (15 ) is connected to the raw material inlet, and the other is connected to the gasifier (23) raw material inlet. 9. A process for preparing PTA/PET based on a pyrolysis gasification device, characterized in that it comprises the following steps: (1) Feed the raw coal into the pyrolysis furnace for pyrolysis at 500°C-800°C to produce raw coal gas and semi-coke; (2) The raw coal gas generated by pyrolysis in step (1) is sent to the gas-solid separator for dedusting of the raw gas, and the powder coke and dedusting gas are separated through the gas-solid separator, and the separated dedusting gas is sent into the gas-liquid separator , to separate the gaseous products and liquid products, and the gaseous products are sent to the electric tar catcher to remove the remaining tar, and then sent to the gas purifier for treatment to obtain purified gas, and the liquid products are sent to the oil-water separator for oil-water separation. The separated tar is sent to the tar purifier, and purified to obtain purified tar; Part of the semi-coke produced by pyrolysis in step (1) is discharged as a product, and part of the semi-coke is sent to the gasification furnace for semi-coke gasification reaction at 800°C-1300°C, and the gasification gas generated by gasification is sent to gas-solid separation The dedusting gasification gas is obtained after dedusting and purification by the gas-solid separator, and the dedusting gasification gas is sent to the gas purifier for purification to obtain purified gasification gas; (3) Mix the purified gasification gas obtained by the gas purifier in step (2) with the purified coal gas obtained by the gas purifier, and then send it to the synthesis gas separator to obtain synthesis gas; (4) Part of the purified tar obtained in step (2) is sent to the aromatics extraction unit to extract light aromatics BTX, and the remaining part of the purified tar is sent to the coal tar hydrorefining unit for hydrorefining and treatment of coal tar. The naphtha obtained after the coal tar hydrorefining unit is sent to the naphtha refining unit to obtain the naphtha raw material required by the methanol-naphtha reforming/coupling unit; Part of the synthesis gas obtained in step (3) is sent to the methanol synthesis unit to obtain a methanol mixture and sent to the methanol refining unit to obtain methanol, and the methanol and naphtha output from the naphtha refining unit are sent to the methanol-naphtha reforming/ Coupling unit, reforming and coupling reaction of methanol and naphtha to obtain PX mixture; the remaining synthesis gas obtained in step (3) is sent to the ethylene glycol synthesis unit, and the ethylene glycol mixture is sent to the ethylene glycol refining unit , to get ethylene glycol; (5) Send the PX mixture obtained in step (4) and the light aromatics BTX obtained by the aromatics extraction unit to the PX refining unit, and PX is obtained after refining, and the PX is sent to the PTA synthesis unit, and the PTA mixture obtained by the reaction, the PTA mixture Send to PTA refining unit to get PTA; (6) The ethylene glycol obtained in step (4) and the PTA obtained in step (5) are sent to the PET synthesis unit for polycondensation to obtain PET. 10. The process for preparing PTA/PET based on a pyrolysis gasification device according to claim 9, characterized in that: the synthesis gas is obtained through the step (3) synthesis gas separator, and a part is sent to the methanol synthesis unit and ethylene glycol respectively The synthesis unit is used to produce methanol and ethylene glycol, and another part of the synthesis gas is sent to the _H2 separation unit, and the separated _H2 is sent to the coal tar hydrorefining unit, which is used as the coal tar hydrorefining unit in step (4) to process coal tar Part of the source of _H2 during hydrofinishing and processing.

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