阅读说明：本技术 一种烃类蒸汽裂解顺序分离工艺与丙烷脱氢工艺耦合方法 (Coupling method of hydrocarbon steam cracking sequential separation process and propane dehydrogenation process ) 是由 卫涛 张仲利 李网章 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顺序分离工艺与丙烷脱氢工艺耦合的方法,针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 hydrocarbon steam cracking sequential separation process and a propane dehydrogenation process in the technical field of petrochemical industry, aiming at the characteristics of cracking gas of a hydrocarbon steam cracking device and reaction gas of a propane dehydrogenation device, the purposes of reducing equipment investment, reducing device energy consumption, reducing construction land and prolonging the service life of an alkyne hydrogenation catalyst are realized by coupling the two processes, and the method is favorable for long-period stable production of a coupling device.)

1. A coupling method of a hydrocarbon steam cracking sequential separation process and a propane dehydrogenation process 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, alkali washing and drying the quenched high-temperature cracking gas, and then feeding the high-temperature cracking gas into a demethanizer;

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 depropanizing tower; the gasified gas-phase propane enters a dehydrogenation reaction unit to carry out dehydrogenation reaction to generate high-temperature reaction gas, the 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) the pyrolysis gas in the step 1) and the non-condensable gas at the top of the light component removal tower in the step 2) are compressed, washed with alkali and dried, and then sequentially enter a pyrolysis gas cooling box unit, a demethanizer and a deethanizer for separation;

4) separating out a C2 component from the top of the deethanizer, treating the C2 component in an acetylene hydrogenation reactor, separating the C2 component in an ethylene rectifying tower, returning the circulating ethane in the ethylene rectifying tower to a cracking unit, and sending other products out of a battery limit; the liquid phase at the bottom of the deethanizer and the liquid phase at the bottom of the propane gasification unit from the step 2) respectively enter a depropanizer for separation;

5) separating a C3 component from the top of the depropanizing tower, treating the C3 component in a propiolic hydrogenation reactor and the liquid phase in the bottom of the light component removal tower from the step 2) respectively in a propylene rectifying tower for separation, and returning the circulating propane in the bottom of the propylene rectifying tower to a propane gasification unit; the liquid phase of the depropanization tower enters a debutanization tower.

2. The method of coupling a steam cracking sequential separation process with a propane dehydrogenation process of claim 1, wherein: and hydrogen and methane products are separated from the top of the demethanizer, and C2 and heavier components in the bottom of the demethanizer enter a deethanizer for separation.

3. The method of coupling a steam cracking sequential separation process with a propane dehydrogenation process of claim 1, wherein: and 5) separating the propylene rectifying tower to obtain the propylene at the top of the tower and the circulating propane at the bottom of the tower, returning the circulating propane to the propane gasification unit, and sending the propylene product out of the battery limits.

4. The method of coupling a steam cracking sequential separation process with a propane dehydrogenation process of claim 1, wherein: and the liquid phase of the depropanizing tower enters a debutanizing tower to obtain C4, C5 and heavier products, which are respectively sent out of the battery limits.

5. The method of coupling a steam cracking sequential separation process with a propane dehydrogenation process of 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 ℃.

6. The method of coupling a steam cracking sequential separation process with a propane dehydrogenation process of 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 ℃.

7. The method of coupling a steam cracking sequential separation process with a propane dehydrogenation process of claim 1, wherein: the operation pressure of the cold box unit is 0.50-4.0 MPaA, and the operation temperature is-165-30 ℃.

8. The method of coupling a steam cracking sequential separation process with a propane dehydrogenation process of claim 7, wherein: the operating pressure of the cracking gas cooling box unit is 0.50-4.0 MPaA, and the operating temperature is-165-30 ℃.

9. The method of coupling a steam cracking sequential separation process with a propane dehydrogenation process of claim 1, wherein: the operating pressure of the reaction gas cooling box unit is 0.50-1.3 MPaA, and the operating temperature is-101-30 ℃.

10. The method of coupling a steam cracking sequential separation process with a propane dehydrogenation process of claim 1, wherein: the raw materials of the hydrocarbon steam cracking device comprise light hydrocarbon, naphtha, diesel oil and hydrogenated tail oil.

Technical Field

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

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 former contents are lower, and the contents of hydrogen and carbon monoxide are higher. According to the characteristics of reaction products of the two processes, the hydrocarbon steam cracking sequential separation process and the propane dehydrogenation process are coupled, so that the purposes of reducing equipment investment, reducing device energy consumption and reducing construction land are achieved, and the long-period stable production of the coupling device is facilitated.

Chinese patents CN109761736A, CN109734549A, CN109809958A and CN109851460A disclose methods for coupling different hydrocarbon feedstock steam cracking sequential separation processes with propane dehydrogenation processes, respectively. The methods couple the newly-built propane dehydrogenation unit by modifying the existing steam cracking unit and increasing part of the load of the equipment. The cracking gas and the reaction gas are directly mixed, then compressed, washed by alkali, dried and sent to a sequential separation system for cryogenic separation, the characteristic of high hydrogen in the propane dehydrogenation reaction gas is not considered, and the cold load of the temperature of minus 101 ℃ and below required by hydrogen/methane separation and methane/ethylene separation is increased.

Chinese patent CN110914225A discloses a process and apparatus for the combined production of propylene by propane dehydrogenation and steam cracking, which recycle propane back to the steam cracking process instead of propane dehydrogenation, although increasing ethylene yield, also increases methane content, resulting in increased energy consumption for subsequent separation and a decrease in propylene yield. At the same time, the patent does not consider that the reaction gas contains a small amount of carbon dioxide, and if the reaction gas is not removed by alkaline washing, the risk of blocking the cold box exists.

However, none of the above-mentioned patents optimally applies the deoiling tower of the propane dehydrogenation unit, and the deoiling tower can share the depropanizer of the hydrocarbon steam cracking unit to remove heavy components, so as to realize further coupling.

Disclosure of Invention

The invention discloses a method for coupling a hydrocarbon steam cracking sequential separation process and a propane dehydrogenation process, 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 hydrocarbon steam cracking sequential separation process and a propane dehydrogenation process, which comprises the following steps of:

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, alkali washing and drying the quenched high-temperature cracking gas, and then feeding the high-temperature cracking gas into a demethanizer;

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 depropanizing tower; the gasified gas-phase propane enters a dehydrogenation reaction unit to carry out dehydrogenation reaction to generate high-temperature reaction gas, the 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) the pyrolysis gas in the step 1) and the non-condensable gas at the top of the light component removal tower in the step 2) are compressed, washed with alkali and dried, and then sequentially enter a pyrolysis gas cooling box unit, a demethanizer and a deethanizer for separation;

4) separating out a C2 component from the top of the deethanizer, treating the C2 component in an acetylene hydrogenation reactor, separating the C2 component in an ethylene rectifying tower, returning the circulating ethane in the ethylene rectifying tower to a cracking unit, and sending other products out of a battery limit; the liquid phase at the bottom of the deethanizer and the liquid phase at the bottom of the propane gasification unit from the step 2) respectively enter a depropanizer for separation;

5) separating a C3 component from the top of the depropanizing tower, treating the C3 component in a propiolic hydrogenation reactor and the liquid phase in the bottom of the light component removal tower from the step 2) respectively in a propylene rectifying tower for separation, and returning the circulating propane in the bottom of the propylene rectifying tower to a propane gasification unit; the liquid phase of the depropanization tower enters a debutanization tower.

The method for coupling the hydrocarbon steam cracking sequential separation process and the propane dehydrogenation process is further characterized by comprising the following steps: and hydrogen and methane products are separated from the top of the demethanizer, and C2 and heavier components in the bottom of the demethanizer enter a deethanizer for separation.

The method for coupling the hydrocarbon steam cracking sequential separation process and the propane dehydrogenation process is further characterized by comprising the following steps: step 5) separating the propylene rectifying tower to obtain the propylene at the top of the tower and the circulating propane at the bottom of the tower, returning the circulating propane to the propane gasification unit, and sending the propylene product out of the battery limit; and the liquid phase of the depropanizing tower enters a debutanizing tower to obtain C4, C5 and heavier products, which are respectively sent out of the battery limits.

The method for coupling the hydrocarbon steam cracking sequential separation process and the propane dehydrogenation process is further characterized by comprising the following steps: the nominal capacity of the hydrocarbon steam cracking device is 30-150 ten thousand tons/year.

The method for coupling the hydrocarbon steam cracking sequential separation process and the propane dehydrogenation process is further characterized by comprising the following steps: the nominal capacity of the propane dehydrogenation device is 15-90 ten thousand tons/year.

The method for coupling the hydrocarbon steam cracking sequential separation process and the propane dehydrogenation process is further characterized by comprising the following steps: the operating conditions of the cracking furnace of the hydrocarbon steam cracking unit are that the reaction pressure is 0.10-0.25 MPaA and the reaction temperature is 780-870 ℃.

The method for coupling the hydrocarbon steam cracking sequential separation process and the propane dehydrogenation process is further characterized by comprising the following steps: 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 method for coupling the hydrocarbon steam cracking sequential separation process and the propane dehydrogenation process is further characterized by comprising the following steps: the raw materials of the hydrocarbon steam cracking device comprise light hydrocarbon, naphtha, diesel oil and hydrogenated tail oil.

The method for coupling the hydrocarbon steam cracking sequential separation process and the propane dehydrogenation process is further characterized by comprising the following steps: the operation pressure of the cold box unit is 0.50-4.0 MPaA, and the operation temperature is-165-30 ℃.

The method for coupling the hydrocarbon steam cracking sequential separation process and the propane dehydrogenation process is further characterized by comprising the following steps: the operating pressure of the pyrolysis gas cooling box unit is 0.50-4.0 MPaA, and the operating temperature is-165-30 ℃.

The method for coupling the hydrocarbon steam cracking sequential separation process and the propane dehydrogenation process is further characterized by comprising the following steps: the operating pressure of the reaction gas cooling box unit is 0.50-1.3 MPaA, and the operating temperature is-101-30 ℃.

The method for coupling the hydrocarbon steam cracking sequential separation process and the propane dehydrogenation process is further characterized by comprising the following steps: the cracking gas of the hydrocarbon steam cracking device and the reaction gas of the propane dehydrogenation device are respectively subjected to reaction, quenching, compression and drying. The reaction gas of the propane dehydrogenation device is subjected to reaction, compression and drying treatment, then is subjected to deep cooling to remove hydrogen-containing tail gas, is separated by a light component removal tower, and then is coupled with a hydrocarbon steam cracking device. The coupling device shares a set of alkaline washing tower, a propylene rectifying tower, a depropanizing tower, an ethylene refrigeration compressor and a propylene refrigeration compressor.

The method for coupling the hydrocarbon steam cracking sequential separation process and the propane dehydrogenation process is further characterized by comprising the following steps: the separated circulating ethane returns to a cracking unit of a hydrocarbon steam cracking device, and the separated circulating propane returns to a propane gasification unit of a 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 cooling to remove most hydrogen, so that the cold load of the temperature of-101 ℃ and below required by hydrogen/methane separation and methane/ethylene separation of a coupling device is reduced.

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 depropanization tower, 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 hydrocarbon steam cracking sequential separation process coupled with a propane dehydrogenation process in accordance with 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-hydrogen gas, 8-demethanizer feed, 9-methane, 10-C2 and lighter components, 11-C2 components, 12-acetylene hydrogenation product, 13-ethylene product, 14-recycled ethane, 15-C3 and heavier components, 16-C3 component I, 17-propyne hydrogenation product, 18-propylene product, 19-recycled propane, 20-C4 and heavier components, 21-C4 components, 22-C5 and heavier components, 23-propane raw material, 24-gas phase propane, 25-reaction gas, 26-compressed gas, 27-dehydrogenation product, 28-hydrogen-containing tail gas, 29-light component removal tower feeding, 30-noncondensable gas, 31-C3 component II, 32-heavy component removal, 101-cracking unit, 102-quenching unit, 103-cracking gas compression unit, 104-alkaline washing unit, 105-cracking gas drying unit, 106-cracking gas cooling box unit, 107-demethanizer, 108-deethanizer, 109-acetylene hydrogenation reactor, 110-ethylene rectifying tower, 111-depropanizer, 112-propyne hydrogenation reactor, 113-propylene rectifying tower and 114-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 invention is described in further detail below with reference to the figures and the specific examples, which do not limit the scope of the invention as claimed.

As shown in fig. 1, a hydrocarbon cracking raw material 1 and circulating ethane 14 from the bottom of an ethylene rectifying tower 110 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 30 from the top of the light component removal tower 206 and then enters the cracked gas compression unit 103, the boosted mixed gas 4 is subjected to acid gas removal through the alkaline washing unit 104 to be refined gas 5, and then the refined gas is compressed and then enters the cracked gas drying unit 105 to remove water and be mixed hydrocarbons 6. The mixed hydrocarbon 6 enters a cracked gas cold box unit 106, hydrogen 7 is separated out, the condensed multiple demethanizer feeds 8 respectively enter a demethanizer 107, the top of the demethanizer is methane 9, and the bottom of the demethanizer is C2 and heavier components 10. The C2 and heavier components 10 enter a deethanizer 108 to separate C2 and C3, the top of the tower is a C2 component 11, and the bottom of the tower is a C3 and heavier components 15. The C2 component 11 enters an acetylene hydrogenation reactor 109, the acetylene hydrogenation product 12 at the outlet of the reactor enters an ethylene rectifying tower 110 to separate ethylene and ethane, the top of the tower is an ethylene product 13, and the circulating ethane 14 at the bottom of the tower returns to the cracking unit 101. The C3 at the tower bottom of the deethanizer 108 and the heavier components 15 are sent to a depropanizer 111 to separate C3, C4 and the heavier components, the C3 component I16 at the tower top and C4 and the heavier components 20 at the tower bottom. The C3 component I16 enters a propyne hydrogenation reactor 112, a propyne hydrogenation product 17 at the outlet of the reactor enters a propylene rectifying tower 113 to separate propylene and propane, the top of the propylene rectifying tower is a propylene product 18, and the circulating propane 19 at the bottom of the propylene rectifying tower returns to a propane gasification unit 201. The C4 at the tower bottom of the depropanizing tower 111 and the heavier components 20 are sent to a debutanizing tower 114 to separate C4, C5 and the heavier components, the top of the debutanizing tower is a C4 component 21, and the bottom of the debutanizing tower is a C5 component 22.

The propane raw material 23 and the circulating propane 19 from the bottom of the propylene rectifying tower 113 are mixed and then enter a propane gasification unit 201 for gasification, the gas-phase propane 24 is heated and then enters a dehydrogenation reaction unit 202 for propane dehydrogenation reaction, the reaction gas 25 after the reaction enters a reaction gas compression unit 203 after being cooled, the compressed gas 26 after being boosted enters a reaction gas drying unit 204 for moisture removal, the dehydrogenation product 27 after being dried is sent to a reaction gas cooling box unit 205, and the hydrogen-containing tail gas 28 is obtained through cryogenic separation. The condensed multi-strand light component removal tower feed 29 respectively enters a light component removal tower 206, the tower top non-condensable gas 30 is sent to a cracking gas compression unit 103, and the tower bottom C3 component II 31 is sent to a propylene rectifying tower 113 to separate propylene and propane. The dehydrogenation heavy component 32 at the bottom of the propane gasification unit 201 is sent to a depropanizer 111 to separate the heavy component.

The technical solution of the present invention is described in detail with reference to the attached drawings, which are only drawn for illustrating the basic contents of the invention, and it does not limit the contents and usage forms of the invention, and in fact, some pipes need to be provided with conventional equipments or pipe elements such as pumps, heat exchangers, etc. according to the specific operation conditions.