阅读说明：本技术 烃类蒸汽裂解前脱乙烷工艺与丙烷脱氢工艺耦合的方法 (Method for coupling deethanization process before hydrocarbon steam cracking and propane dehydrogenation process ) 是由 李志禹 张仲利 李网章 要洁 顾炯炯 卫涛 宋强波 娄俊毅 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乙烷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 deethanization process before hydrocarbon steam cracking and a propane dehydrogenation process in the technical field of petrochemical industry, 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.)

1. The method for coupling the deethanization process before hydrocarbon steam cracking with the propane dehydrogenation process is characterized by comprising 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, carrying out alkali washing and drying, and then feeding the high-temperature cracking gas to a front deethanizing separation system;

2) the propane raw material is mixed with circulating propane from the bottom of a propylene rectifying tower, the mixture enters a propane gasification unit for gasification, gasified gas-phase propane enters a dehydrogenation reaction unit for 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, a condensed liquid phase enters a light component removal tower for separation, a non-condensed gas phase at the top of the light component removal tower enters a pyrolysis gas compression unit, a C3 component is extracted from the lateral line at the lower part of the light component removal tower and sent to the propylene rectifying tower, and a heavy component of dehydrogenation from the bottom of the light component removal tower is sent to a depropanizer;

3) the pyrolysis gas in the step 1) and the non-condensable gas at the top of the light component removal tower from the step 2) are compressed, alkali washed and dried, then enter a deethanizer for separation, C2 and lighter components are separated from the top of the deethanizer, and after being treated by an acetylene hydrogenation reactor, the pyrolysis gas sequentially enters a pyrolysis gas cold box unit, a demethanizer and an ethylene rectifying tower for further separation, the separated circulating ethane returns to a pyrolysis unit, and other products are sent out of a battery limit;

4) and (3) respectively feeding the deethanizer bottoms from the step 3) and the light component removal tower bottom dehydrogenation heavy components from the step 2) into a depropanizer for separation, separating C3 components from the tower top, treating the C3 components by a propyne hydrogenation reactor, respectively feeding the C3 components and the light component removal tower bottom liquid phase from the step 2) into a propylene rectifying tower for separation, and returning the circulating propane in the propylene rectifying tower bottom to a propane gasification unit.

2. The method of claim 1 for coupling a steam cracking pre-deethanization process with a propane dehydrogenation process, wherein: and 4) separating the product in the step 4) in a propylene rectifying tower to obtain propylene and a propane product, recycling the propane to the propane gasification unit, and sending the propylene product out of the battery limits.

3. The method of claim 1 for coupling a steam cracking pre-deethanization process with a propane dehydrogenation process, 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.

4. The method of claim 1 for coupling a steam cracking pre-deethanization process with a propane dehydrogenation process, 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 ℃.

5. The method of claim 1 for coupling a steam cracking pre-deethanization process with a propane dehydrogenation process, 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 ℃.

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

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

8. The method of claim 6 for coupling a steam cracking pre-deethanization process with a propane dehydrogenation process, wherein: the operating pressure of the reaction gas cooling box unit is 0.50-1.3 MPaA, and the operating temperature is-101-30 ℃.

9. The method of claim 1 for coupling a steam cracking pre-deethanization process with a propane dehydrogenation process, 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 deethanization and propane dehydrogenation processes 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 deethanization 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 the alkyne hydrogenation catalyst are achieved, and the long-period stable production of a coupling device is facilitated.

Chinese patent CN109761734A discloses a method for coupling a deethanization process before cracking naphtha and ethane with a propane dehydrogenation process, and chinese patent CN107673947A discloses a method for coupling a deethanization process before cracking naphtha with a propane dehydrogenation process. The two methods directly mix the cracking gas and the reaction gas, then compress, wash with alkali, dry, and send to a front deethanizing separation system for cryogenic separation. None of them takes into account the high hydrogen and carbon monoxide content of the propane dehydrogenation reaction gas, which leads to an increased cold load at the-101 ℃ and below temperatures required for hydrogen/methane separation and methane/ethylene separation. In addition, the carbon monoxide content in the mixed gas is higher, and the service life of the acetylene hydrogenation catalyst is also greatly influenced.

Chinese patent CN109809957A discloses a method for coupling a light hydrocarbon cracking front deethanization process and a propane dehydrogenation process, and CN109851461A discloses a method for coupling a naphtha and propane cracking front deethanization process and a propane dehydrogenation process. The two methods respectively compress and dry the cracking gas and the reaction gas, and then send the cracking gas and the reaction gas to a front deethanizing separation system for cryogenic separation. The reaction gas is not treated with a base wash and, since it contains a certain amount of carbon dioxide, there is a risk of blocking the cold box if it is not removed with a base wash. In addition, the direction of the hydrogen-containing tail gas is not determined in both methods, and the influence on the low-temperature load and the service life of the acetylene hydrogenation catalyst is unknown.

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. Also, the patent does not consider the adverse effect of the reaction gas containing a small amount of carbon dioxide.

The above patents do not optimize the deoiling tower of the propane dehydrogenation device, and the deoiling tower can be used for removing heavy components by using the depropanizer of the hydrocarbon steam cracking device, so that further coupling is realized.

Disclosure of Invention

The invention discloses a method for coupling a deethanization process before hydrocarbon steam cracking 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 provides a method for coupling a deethanization 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 deethanizing separation system;

2) the propane raw material is mixed with circulating propane from the bottom of a propylene rectifying tower, the mixture enters a propane gasification unit for gasification, gasified gas-phase propane enters a dehydrogenation reaction unit for 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, a condensed liquid phase enters a light component removal tower for separation, a non-condensed gas phase at the top of the light component removal tower enters a pyrolysis gas compression unit, a C3 component is extracted from the lateral line at the lower part of the light component removal tower and sent to the propylene rectifying tower, and a heavy component of dehydrogenation from the bottom of the light component removal tower is sent to a depropanizer;

3) the pyrolysis gas in the step 1) and the non-condensable gas at the top of the light component removal tower from the step 2) are compressed, alkali washed and dried, then enter a deethanizer for separation, C2 and lighter components are separated from the top of the deethanizer, and after being treated by an acetylene hydrogenation reactor, the pyrolysis gas sequentially enters a pyrolysis gas cold box unit, a demethanizer and an ethylene rectifying tower for further separation, the separated circulating ethane returns to a pyrolysis unit, and other products are sent out of a battery limit;

4) and (3) respectively feeding the deethanizer bottoms from the step 3) and the light component removal tower bottom dehydrogenation heavy components from the step 2) into a depropanizer for separation, separating C3 components from the tower top, treating the C3 components by a propyne hydrogenation reactor, respectively feeding the C3 components and the light component removal tower bottom liquid phase from the step 2) into a propylene rectifying tower for separation, and returning the circulating propane in the propylene rectifying tower bottom to a propane gasification unit.

The method for coupling the deethanization process before hydrocarbon steam cracking with the propane dehydrogenation process is further characterized by comprising the following steps of: and 4) separating the propylene product and the circulating propane product in the propylene rectifying tower, returning the circulating propane to the propane gasification unit, and sending the propylene product out of the battery limits.

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 deethanization process before hydrocarbon steam cracking with the propane dehydrogenation process is further characterized by comprising the following steps of: the nominal capacity of the hydrocarbon steam cracking device is 30-150 ten thousand tons/year.

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

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

The method for coupling the deethanization process before hydrocarbon steam cracking with the propane dehydrogenation process is further characterized by comprising the following steps of: 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 hydrogen-containing tail gas of the treated reaction gas is removed by deep cooling, and the treated reaction gas is coupled with the hydrocarbon steam cracking device after being separated by a light component removing tower. 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 deethanization process before hydrocarbon steam cracking with the propane dehydrogenation process is further characterized by comprising the following steps of: 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 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 process of the present invention in which a deethanization process is coupled to a propane dehydrogenation process prior to steam cracking of hydrocarbons.

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-C2 and lighter components, 8-acetylene hydrogenation product, 9-hydrogen, 10-demethanizer feed, 11-methane, 12-C2 component, 13-ethylene product, 14-recycle ethane, 15-C3 and heavier components, 16-C3 component I, 17-propyne hydrogenation product, 18-propylene product, 19-recycle propane, 20-C4 and heavier components, 21-C4 component, 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-deethanizer, 107-acetylene hydrogenation reactor, 108-cracking gas cooling box unit, 109-demethanizer, 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.

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 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 is further compressed and then enters a deethanizer 106, C2 and lighter components 7 separated from the tower top enter an acetylene hydrogenation reactor 107, an acetylene hydrogenation product 8 at the reactor outlet is sent to a pyrolysis gas cold box unit 108, and hydrogen 9 is obtained through cryogenic separation. The condensed multiple demethanizer feed 10 enters the demethanizer 109 with methane 11 at the top and C2 component 12 at the bottom. The C2 component 12 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 in the tower bottom returns to the cracking unit 101. The C3 at the tower bottom of the deethanizer 106 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 is sent to a propylene rectifying tower 113 to separate propylene and propane, a propylene product 18 is obtained at the top of the tower, and the circulating propane 19 at the bottom of the tower returns to a propane gasification unit 201. The bottom C4 of the depropanizer 111 and the heavier components 20 are sent to a debutanizer 114 to separate C4, C5 and the heavier components, the top of the tower is C4 components 21, and the bottom of the tower is C5 and the heavier components 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 multiple light component removal tower feeding materials 29 respectively enter a light component removal tower 206, non-condensable gas 30 at the top of the light component removal tower is sent to a pyrolysis gas compression unit 103, a component II 31 of C3 extracted from the lower side line of the light component removal tower 206 is sent to a propylene rectifying tower 113 to separate propylene and propane, and a heavy component 32 of the light component removal tower bottom is sent to a depropanizer 111 to separate a 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.