阅读说明：本技术 一种烃类蒸汽裂解前脱丙烷工艺与丙烷脱氢工艺耦合方法 (Coupling method of depropanization process and propane dehydrogenation process before hydrocarbon steam cracking ) 是由 张仲利 李网章 卫涛 要洁 娄俊毅 顾炯炯 李志禹 宋强波 蔺伟 于 2020-07-08 设计创作，主要内容包括：本发明公开了石油化工技术领域一种烃类蒸汽裂解前脱丙烷工艺与丙烷脱氢工艺耦合的方法,对烃类蒸汽裂解装置裂解气和丙烷脱氢装置反应气的特点,通过这两种工艺的耦合,实现降低设备投资、降低装置能耗、减少建设用地、延长炔烃加氢催化剂寿命的目的,并且有利于耦合装置长周期稳定生产。(The invention discloses a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking in the technical field of petrochemical industry, which realizes the purposes of reducing equipment investment, reducing device energy consumption, reducing construction land and prolonging the service life of an alkyne hydrogenation catalyst by coupling the characteristics of cracking gas of a hydrocarbon steam cracking device and reaction gas of a propane dehydrogenation device and is beneficial to long-period stable production of the coupling device.)

1. A coupling method of a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking is characterized by comprising the following steps:

1) heating a hydrocarbon raw material and circulating ethane from the bottom of an ethylene rectifying tower, then feeding the heated hydrocarbon raw material and the circulating ethane into a cracking unit for steam thermal cracking reaction to generate high-temperature cracking gas, quenching the high-temperature cracking gas, compressing, carrying out alkali washing and drying, and then feeding the high-temperature cracking gas to a front depropanization separation system;

2) the propane raw material is mixed with circulating propane from the bottom of the propylene rectifying tower, the mixture enters a propane gasification unit for gasification, and a liquid phase at the bottom of the propane gasification unit enters a low-pressure depropanizing tower; the gasified gas-phase propane enters a dehydrogenation reaction unit to perform propane dehydrogenation reaction to generate high-temperature reaction gas, the high-temperature reaction gas is condensed and flashed by a reaction gas cooling box unit after being compressed and dried, the condensed liquid phase enters a light component removal tower for separation, the non-condensed gas phase at the top of the light component removal tower enters a pyrolysis gas compression unit, and the liquid phase at the bottom of the light component removal tower enters a propylene rectifying tower;

3) after the non-condensable gas at the top of the light component removal tower from the step 2) enters a pyrolysis gas compression unit, the non-condensable gas and the pyrolysis gas in the step 1) are compressed, alkali washed and dried, then enter a high-pressure depropanizer for separation, C3 and lighter components are separated from the top of the high-pressure depropanizer, and after being treated by an acetylene hydrogenation reactor, the non-condensable gas sequentially enters a pyrolysis gas cooling box unit, a demethanizer, a deethanizer and an ethylene rectifying tower for further separation; returning the ethylene circulating in the ethylene rectifying tower to the cracking unit;

4) and (3) feeding the high-pressure depropanizing tower bottom liquid phase from the step 3) and the propane gasification unit bottom liquid phase from the step 2) into a low-pressure depropanizing tower for separation, mixing the low-pressure depropanizing tower top component with the deethanizing tower bottom component from the step 3), feeding the mixture into a propiolic hydrogenation reactor for treatment, feeding the treated component and the light component removing tower bottom liquid phase in the step 2) into a propylene rectifying tower respectively, and feeding the circulating propane in the propylene rectifying tower bottom into the propane gasification unit.

2. The method for coupling a depropanization process before steam cracking with a propane dehydrogenation process according to claim 1, wherein: the front-end depropanization separation system comprises a high-pressure depropanization tower and a low-pressure depropanization tower.

3. The method for coupling a depropanization process before steam cracking with a propane dehydrogenation process according to claim 1, wherein: the operation conditions of the cracking furnace in the hydrocarbon steam cracking unit are that the reaction pressure is 0.10-0.25 MPaA and the reaction temperature is 780-870 ℃.

4. The method for coupling a depropanization process before steam cracking with a propane dehydrogenation process according to claim 1, wherein: the operation conditions of the reactor in the propane dehydrogenation reaction unit are that the reaction pressure is 0.10-0.35 MPaA and the reaction temperature is 450-700 ℃.

5. The method for coupling a depropanization process before steam cracking with a propane dehydrogenation process according to claim 1, wherein: the operation pressure of the cold box unit is 0.50-4.0 MPaA, and the operation temperature is-165-30 ℃.

6. The method for coupling a depropanization process before steam cracking with a propane dehydrogenation process according to claim 5, wherein: the operating pressure of the cracking gas cooling box unit is 0.50-4.0 MPaA, and the operating temperature is-165-30 ℃.

7. The method for coupling a depropanization process before steam cracking with a propane dehydrogenation process according to claim 5, wherein: the operating pressure of the reaction gas cooling box unit is 0.50-1.3 MPaA, and the operating temperature is-101-30 ℃.

8. The method for coupling a depropanization process before steam cracking with a propane dehydrogenation process according to claim 1, wherein: the raw materials of the hydrocarbon steam cracking device comprise light hydrocarbon, naphtha, diesel oil and hydrogenated tail oil.

9. The method for coupling a depropanization process before steam cracking with a propane dehydrogenation process according to claim 1, wherein: and obtaining propylene and propane products from the propylene rectifying tower, recycling the propane to the propane gasification unit, and sending the propylene products out of the battery limits.

10. The method for coupling a depropanization process before steam cracking with a propane dehydrogenation process according to claim 1, wherein: and the liquid phase of the low-pressure depropanizing tower enters a debutanizing tower to obtain C4, C5 and heavier products, and the products are respectively sent out of the battery limits.

Technical Field

The invention belongs to the field of petrochemical industry, and particularly relates to a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking.

Background

Ethylene is one of the most important basic raw materials in the petrochemical industry, and the yield of ethylene is a mark for measuring the overall development level of the petrochemical industry in a country. The ethylene production technology comprises hydrocarbon steam cracking, methanol-to-olefin, olefin conversion and the like, wherein the hydrocarbon steam cracking is dominant. At present, the hydrocarbon steam cracking technical patenters in the world mainly have: KBR, Linde, Germany, Lummus, and Technip, USA. These techniques all employ cryogenic separation processes to obtain ethylene products. The separation process may be divided into a sequential separation process, a pre-deethanization process, and a pre-depropanization process for different cracking feedstocks.

Propylene is also one of the most important base stocks in the petrochemical industry, and conventional sources of propylene rely primarily on hydrocarbon steam cracking for co-production and refinery FCC by-products. In recent years, techniques for producing propylene exclusively, such as dehydrogenation of propane and production of propylene from methanol, have been developed. At present, the propane dehydrogenation patent technologies in the world are as follows: camofin Process from Lummus, Oleflex Process from UOP, Star Process from Uhde, PDH Process from Linde, and FBD Process from Snamprogetti/Yarsintz. These processes generally employ cryogenic separation processes to separate the reaction product of propane dehydrogenation to propylene.

The hydrocarbon steam cracking and the propane dehydrogenation are both used for producing low-carbon olefin and adopt cryogenic separation process technology. The steam cracking raw materials are wide, and the product types are more; the propane dehydrogenation has single raw material and single product. The reaction products of steam cracking and propane dehydrogenation, i.e. the cracked gas and the reaction gas, are similar in composition: mainly comprises hydrogen, methane, ethane, ethylene, propane, propylene, carbon four and aromatic hydrocarbon. The contents are obviously different: the cracking gas has high contents of methane, ethane, ethylene, acetylene and propyne, and low contents of hydrogen and carbon monoxide; the reaction gases are opposite, the contents of the former few are lower, and the contents of the latter two are higher. According to the characteristics of reaction products of the two processes, the depropanization process before hydrocarbon steam cracking and the propane dehydrogenation process are coupled, so that the purposes of reducing equipment investment, reducing device energy consumption, reducing construction land and prolonging the service life of an alkyne hydrogenation catalyst are achieved, and the long-period stable production of a coupling device is facilitated.

Disclosure of Invention

The invention discloses a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking, which aims at the characteristics of cracking gas of a hydrocarbon steam cracking device and reaction gas of a propane dehydrogenation device, realizes the purposes of reducing equipment investment, reducing device energy consumption, reducing construction land and prolonging the service life of an alkyne hydrogenation catalyst by coupling the two processes, and is beneficial to long-period stable production of a coupling device.

The invention relates to a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking, which comprises the following steps:

1) heating a hydrocarbon raw material and circulating ethane from the bottom of an ethylene rectifying tower, then feeding the heated hydrocarbon raw material and the circulating ethane into a cracking unit for steam thermal cracking reaction to generate high-temperature cracking gas, quenching the high-temperature cracking gas, compressing, carrying out alkali washing and drying, and then feeding the high-temperature cracking gas to a front depropanization separation system;

2) the propane raw material is mixed with circulating propane from the bottom of the propylene rectifying tower, the mixture enters a propane gasification unit for gasification, and a liquid phase at the bottom of the propane gasification unit enters a low-pressure depropanizing tower; the gasified gas-phase propane enters a dehydrogenation reaction unit to perform propane dehydrogenation reaction to generate high-temperature reaction gas, the high-temperature reaction gas is condensed and flashed by a reaction gas cooling box unit after being compressed and dried, the condensed liquid phase enters a light component removal tower for separation, the non-condensed gas phase at the top of the light component removal tower enters a pyrolysis gas compression unit, and the liquid phase at the bottom of the light component removal tower enters a propylene rectifying tower;

3) after the non-condensable gas at the top of the light component removal tower from the step 2) enters a pyrolysis gas compression unit, the non-condensable gas and the pyrolysis gas in the step 1) are compressed, alkali washed and dried, then enter a high-pressure depropanizer for separation, C3 and lighter components are separated from the top of the high-pressure depropanizer, and after being treated by an acetylene hydrogenation reactor, the non-condensable gas sequentially enters a pyrolysis gas cooling box unit, a demethanizer, a deethanizer and an ethylene rectifying tower for further separation; returning the ethylene circulating in the ethylene rectifying tower to the cracking unit;

4) and (3) feeding the high-pressure depropanizing tower bottom liquid phase from the step 3) and the propane gasification unit bottom liquid phase from the step 2) into a low-pressure depropanizing tower for separation, mixing the low-pressure depropanizing tower top component with the deethanizing tower bottom component from the step 3), feeding the mixture into a propiolic hydrogenation reactor for treatment, feeding the treated component and the light component removing tower bottom liquid phase in the step 2) into a propylene rectifying tower respectively, and feeding the circulating propane in the propylene rectifying tower bottom into the propane gasification unit.

The invention relates to a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking, which is further characterized in that: the front-end depropanization separation system comprises a high-pressure depropanization tower and a low-pressure depropanization tower.

The invention relates to a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking, which is further characterized in that: obtaining propylene and propane products from the propylene rectifying tower, recycling the propane to the propane gasification unit, and sending the propylene products out of the battery limits;

the invention relates to a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking, which is further characterized in that: and the liquid phase of the low-pressure depropanizing tower enters a debutanizing tower to obtain C4, C5 and heavier products, and the products are respectively sent out of the battery limits.

The invention relates to a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking, which is further characterized in that: the nominal capacity of the hydrocarbon steam cracking device is 30-150 ten thousand tons/year. The nominal capacity of the propane dehydrogenation device is 15-90 ten thousand tons/year.

The invention relates to a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking, which is further characterized in that: the operation conditions of the cracking furnace in the hydrocarbon steam cracking unit are that the reaction pressure is 0.10-0.25 MPaA and the reaction temperature is 780-870 ℃.

The invention relates to a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking, which is further characterized in that: the operation conditions of the reactor in the propane dehydrogenation reaction unit are that the reaction pressure is 0.10-0.35 MPaA and the reaction temperature is 450-700 ℃.

The invention relates to a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking, which is further characterized in that: the operation pressure of the cold box unit is 0.50-4.0 MPaA, and the operation temperature is-165-30 ℃.

The invention relates to a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking, which is further characterized in that: the operating pressure of the pyrolysis gas cooling box unit is 0.50-4.0 MPaA, and the operating temperature is-165-30 ℃.

The invention relates to a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking, which is further characterized in that: the operating pressure of the reaction gas cooling box unit is 0.50-1.3 MPaA, and the operating temperature is-101-30 ℃.

The invention relates to a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking, which is further characterized in that: the raw materials of the hydrocarbon steam cracking device comprise light hydrocarbon, naphtha, diesel oil and hydrogenated tail oil.

The invention relates to a method for coupling a depropanization process and a propane dehydrogenation process before hydrocarbon steam cracking. The coupling device shares a set of alkaline washing tower, a propylene rectifying tower, a low-pressure depropanizer, an ethylene refrigeration compressor and a propylene refrigeration compressor. The separated ethane returns to the cracking unit of the hydrocarbon steam cracking device, and the separated propane returns to the propane gasification unit of the propane dehydrogenation device.

The coupling method provided by the invention has the following beneficial effects:

1) the pyrolysis gas and the reaction gas are respectively compressed and dried, which is beneficial to the long-period stable production of the coupling device. The steam cracking and the propane dehydrogenation are high-temperature reactions, the conditions are harsh, coking is easy to occur, and the steam cracking and the propane dehydrogenation are respectively compressed to avoid mutual interference.

2) The reaction gas is subjected to cryogenic removal to remove most of hydrogen and carbon monoxide, so that the cold load of the coupling device at the temperature of-101 ℃ and below for hydrogen/methane separation and methane/ethylene separation is reduced; the content of carbon monoxide is reduced, and the service life of the acetylene hydrogenation catalyst is prolonged.

3) The separated propane is circularly returned to the propane dehydrogenation device, so that the yield of the propylene is improved, the methane content is reduced, the economic benefit of the coupling device is better, and the energy consumption is lower.

4) The coupling device recovers the ethylene in the propane dehydrogenation reaction gas, and the economic benefit of the device is improved.

5) The coupling device shares a set of alkaline washing tower, a propylene rectifying tower, a low-pressure depropanizer, an ethylene refrigeration compressor and a propylene refrigeration compressor, so that the equipment investment is reduced, and the construction land is reduced.

Drawings

FIG. 1 is a schematic flow diagram of a depropanization process before hydrocarbon steam cracking and a propane dehydrogenation process coupled according to the present invention.

The reference symbols shown in the figures are:

1-hydrocarbon cracking raw material, 2-cracking product, 3-cracking gas, 4-mixed gas, 5-refined gas, 6-mixed hydrocarbon, 7-C3 and lighter components, 8-acetylene hydrogenation feed, 9-acetylene hydrogenation product, 10-hydrogen, 11-demethanizer feed, 12-methane, 13-C2/C3 components, 14-C2 components, 15-C3 components I, 16-ethylene product, 17-recycle ethane, 18-C3 and heavier components, 19-C3 components II, 20-propyne hydrogenation product, 21-propylene product, 22-recycle propane, 23-C4 and heavier components, 24-C4 components, 25-C5 and heavier components, 26-propane raw material, 27-gas phase propane, 28-reaction gas, 29-compressed gas, 30-dehydrogenation product, 31-hydrogen-containing tail gas, 32-light component removal tower feeding, 33-noncondensable gas, 34-C3 component III, 35-dehydrogenation heavy component, 101-cracking unit, 102-quenching unit, 103-cracking gas compression unit, 104-alkaline washing unit, 105-cracking gas drying unit, 106-high-pressure depropanizer, 107-acetylene hydrogenation reactor, 108-cracking gas cooling box unit, 109-demethanizer, 110-deethanizer, 111-ethylene rectifying tower, 112-low-pressure depropanizer, 113-propyne hydrogenation reactor, 114-propylene rectifying tower and 115-debutanizer; 201-propane gasification unit, 202-dehydrogenation reaction unit, 203-reaction gas compression unit, 204-reaction gas drying unit, 205-reaction gas cooling box unit and 206-light component removal tower.

Detailed Description

The present invention is described in further detail below with reference to fig. 1 and the specific examples, which do not limit the scope of the claimed invention.

As shown in fig. 1, a hydrocarbon cracking raw material 1 and circulating ethane 17 from the bottom of an ethylene rectifying tower 111 are heated and then enter a cracking unit 101 for steam thermal cracking reaction, a generated cracking product 2 is sent to a quenching unit 102, and heavy hydrocarbons are separated through oil cooling and water cooling to obtain a cracking gas 3. The cracked gas 3 is mixed with the non-condensable gas 33 from the top of the light component removal tower 206 and then enters the cracked gas compression unit 103, the acid gas of the boosted mixed gas 4 is removed by the alkali washing unit 104 to form refined gas 5, and the water is removed by the cracked gas drying unit 105 to form mixed hydrocarbon 6. The mixed hydrocarbon 6 enters a high-pressure depropanizing tower 106, C3 and lighter components 7 are separated from the top of the high-pressure depropanizing tower, the pressure of the mixed hydrocarbon is increased by a cracked gas compression unit 103, the increased acetylene hydrogenation feed 8 enters an acetylene hydrogenation reactor 107, an acetylene hydrogenation product 9 at the outlet of the reactor is sent to a cracked gas cold box unit 108, and hydrogen 10 is obtained by cryogenic separation. The condensed multiple demethanizer feeds 11 respectively enter a demethanizer 109, the top of the demethanizer is methane 12, and the bottom of the demethanizer is C2/C3 component 13. The C2/C3 component 13 enters a deethanizer 110 to separate C2 and C3, the top of the deethanizer is a C2 component 14, and the bottom of the deethanizer is a C3 component I15. The C2 component 14 enters an ethylene rectifying tower 111 to separate ethylene and ethane, the top of the ethylene rectifying tower is an ethylene product 16, and the circulating ethane 17 in the bottom of the ethylene rectifying tower returns to the cracking unit 101. The C3 in the tower bottom of the high-pressure depropanizing tower 106 and the heavier components 18 are sent to a low-pressure depropanizing tower 112 to separate C3, C4 and the heavier components, the C3 component II 19 is arranged at the top of the low-pressure depropanizing tower, and the C4 and the heavier components 23 are arranged at the tower bottom of the low-pressure depropanizing tower. The C3 component II 19 and the C3 component I15 from the bottom of the deethanizer 110 are mixed and then enter a propyne hydrogenation reactor 113, a propyne hydrogenation product 20 at the outlet of the reactor is sent to a propylene rectifying tower 114 for separating propylene and propane, a propylene product 21 is at the top of the propylene rectifying tower, and the circulating propane 22 at the bottom of the propylene rectifying tower returns to a propane gasification unit 201. The C4 and heavier components 23 in the tower bottom of the low-pressure depropanizing tower 112 are sent to a debutanizing tower 115 to separate C4, C5 and heavier components, the top of the debutanizing tower is a C4 component 24, and the bottom of the debutanizing tower is a C5 component 25.

The propane raw material 26 and the circulating propane 22 from the bottom of the propylene rectifying tower 114 are mixed and then enter a propane gasification unit 201 for gasification, the gas-phase propane 27 is heated and then enters a dehydrogenation reaction unit 202 for propane dehydrogenation reaction, the reaction gas 28 after the reaction is cooled and then enters a reaction gas compression unit 203, the compressed gas 29 after the pressure increase enters a reaction gas drying unit 204 for moisture removal, the dehydrogenation product 30 after the drying is sent to a reaction gas cooling box unit 205, and the hydrogen-containing tail gas 31 is obtained through cryogenic separation. The condensed multi-strand light component removal tower feeding 32 respectively enters a light component removal tower 206, the light component removal tower top non-condensable gas 33 is sent to a cracking gas compression unit 103, and the light component removal tower kettle C3 component III 34 is sent to a propylene rectifying tower 114 for separating propylene and propane. The dehydrogenation heavy component 35 at the bottom of the propane gasification unit 201 is sent to a low-pressure depropanizer 112 to separate the heavy component.