CN112592251A

CN112592251A - Process and apparatus for separating a light hydrocarbon-containing stream

Info

Publication number: CN112592251A
Application number: CN202011538929.1A
Authority: CN
Inventors: 刘平飞; 汪丹峰; 唐志永
Original assignee: Shanghai Ruicheng Carbon Energy Technology Co ltd
Current assignee: Shanghai Ruicheng Carbon Energy Technology Co ltd
Priority date: 2020-12-23
Filing date: 2020-12-23
Publication date: 2021-04-02

Abstract

A process for separating a light hydrocarbon-containing stream, the process comprising (1) providing a light hydrocarbon-containing stream; (2) the light hydrocarbon-containing stream is cut to separate the light hydrocarbon-containing stream into a stream below C2 and a stream above C3. The method further comprises the following steps of carrying out the following steps on the C2: (3) first-stage hydration; (4) separating out the first solid hydrate; (5) resolving a hydrate; (6) drying and complexing; (7) and (4) resolving the complex. The method also comprises the following steps of carrying out on the stream above C3: (8) separating the stream above C3 resulting from step (2) to separate the stream above C3 into a C3 stream and a C4 stream; (9): separating the stream of C3 obtained from step (8) to obtain a propylene product; (10): separating the stream of C4 obtained from step (8) to obtain a butene product. An apparatus for separating a light hydrocarbon-containing stream is also provided.

Description

Process and apparatus for separating a light hydrocarbon-containing stream

Technical Field

The present application relates generally to methods and apparatus for separating light hydrocarbon-containing streams, and more particularly to methods and apparatus for separating light hydrocarbon-containing product gases, such as catalytic cracking dry gas, fischer-tropsch synthesis tail gas, methanol to olefins, and the like.

Background

The olefin plays an extremely important role in national economic production, wherein the low-carbon olefin mainly comprising ethylene, propylene and butylene is particularly important and is the most important basic raw material in the industries of chemical engineering, textile and the like. The low-carbon olefin is mainly obtained by petroleum catalytic cracking at present, and is prepared by Methanol To Olefin (MTO), Fischer-Tropsch synthesis, direct olefin preparation by synthesis gas and the like. Most of the separation technologies for separating low-carbon olefins from tail gas generated by catalytic cracking of dry gas, production of olefins from methanol, Fischer-Tropsch tail gas and direct production of olefins from synthesis gas are mastered by European and American countries, and in addition, the products are different due to different synthesis processes of the low-carbon olefins, which further causes the low applicability of the separation technologies.

The process for separating and recovering the low-carbon light hydrocarbon which is successfully developed at present comprises the following steps: cryogenic separation, partial cryogenic separation, medium cooling oil washing, membrane separation, pressure swing adsorption separation and other technologies. However, cryogenic and partial cryogenic processes are only suitable for recovering olefin from catalytic cracking dry gas in petroleum routes, and have the defects of high cost, high energy consumption and the like. The intermediate cooling oil washing process cannot obtain high-purity ethylene products. Although the membrane separation process is simple, the membrane is greatly influenced by raw materials, the raw materials need to be specially pretreated, and the investment is high. The pressure swing adsorption process does not allow high purity polymer grade ethylene products to be obtained.

Aiming at the defects of the various processes, the method for separating the light hydrocarbon which has strong applicability and low energy consumption and gives consideration to higher recovery rate and high purity of the olefin is very necessary.

Disclosure of Invention

The present inventors have conducted extensive and intensive studies to achieve the above-mentioned object in a low-cost and convenient manner by improving process conditions and purification equipment, thereby completing the present invention. In one aspect of the invention, the invention provides a process for separating a light hydrocarbon-containing stream, the process comprising:

step (1): providing a light hydrocarbon-containing stream;

step (2): cutting the light hydrocarbon-containing stream to separate the light hydrocarbon-containing stream into a stream below C2 and a stream above C3;

and (3): performing primary hydration on the stream below C2 obtained in the step (2) to enable C1-C2 hydrocarbons to react in the presence of a first hydration reaction auxiliary agent to generate a first solid hydrate floating on the liquid surface, so that the first solid hydrate is separated from tail gas of the primary hydration reaction;

and (4): separating the solid from the liquid of step (3) to obtain the first solid hydrate;

and (5): resolving the first solid hydrate to obtain a C1-C2 hydrocarbon material flow;

and (6): drying the C1-C2 hydrocarbon stream obtained in step (5), and subsequently contacting the dried C1-C2 hydrocarbon stream with a complexing agent to react ethylene therein with the complexing agent to obtain an ethylene complex;

and (7): resolving the ethylene complex obtained from step (6) to release ethylene product;

and (8): separating the stream above C3 resulting from step (2) to separate the stream above C3 into a C3 stream and a C4 stream;

and (9): separating the C3 stream obtained from step (8) to obtain a propylene product and propane;

step (10): the C4 stream resulting from step (8) is separated to yield a butene product and butane.

According to one embodiment of this first aspect, the light hydrocarbon-containing stream of step (1) is (a) a hydrocarbon-containing stream directly from catalytic cracking dry gas, fischer-tropsch synthesis tail gas, methanol to olefins product gas; or (b) a product gas from a synthesis reactor, and the product gas is subjected to a pretreatment comprising one or more of condensation, water washing, decarbonation, drying, pressure swing adsorption, membrane separation, or oil washing. In another embodiment, the light hydrocarbon-containing stream has a feed temperature of from 30 to 50 ℃.

According to one embodiment of the first aspect, the cutting of step (2) is carried out in a deethanizer, wherein the deethanizer is operated at a pressure of 2.0 to 2.2MPaG, the number of theoretical plates is 35 to 60, the light hydrocarbon-containing stream is fed at a position of 10 to 35 plates from the top, the overhead temperature is-75 to-40 ℃, the still temperature is 50 to 90 ℃, the stream below C2 is taken as a gas from the top, and the stream above C3 is taken as a still liquid from the bottom.

According to one embodiment of this first aspect, step (3) is carried out in a primary hydration reactor operating at a pressure of 5.2 to 6.2MPaG and at a temperature of 0 to 5 ℃, the sub-C2 stream from step (2) entering at the inlet of the primary hydration reactor, the primary hydration reaction aid being present in the reactor. The first-stage hydration reaction auxiliary agent is selected from one of dodecyl benzene sulfonic acid or salt thereof (such as sodium salt, potassium salt or ammonium salt), tween 60, tween 80, dodecyl sulfonic acid or salt thereof (such as sodium salt, potassium salt or ammonium salt) or any combination thereof.

According to one embodiment of this first aspect, step (4) is carried out by means of a mechanical separator placed internally in the primary hydration reactor or downstream of the outlet of the primary hydration reactor.

According to an embodiment of this first aspect, the method further comprises step (3-1): performing secondary hydration on the tail gas of the primary hydration reaction in the step (3) so that the C1-C2 hydrocarbon in the tail gas reacts in the presence of a second hydration reaction auxiliary agent to generate a second solid hydrate floating on the liquid surface, and the second solid hydrate is separated from the tail gas of the secondary hydration reaction; and step (4-1): separating the liquid from the solid of step (3-1) to obtain the second solid hydrate and combining with the first solid hydrate of step (4).

According to one embodiment of this first aspect, step (3-1) is carried out in a secondary hydration reactor operating at a pressure of 5.2 to 6.2MPaG and at a temperature of 0 to 5 ℃, the tail gas from the primary hydration reaction of step (3) entering at the inlet of the secondary hydration reactor, in which secondary hydration reaction promoter is present. The secondary hydration reaction auxiliary agent is selected from one or any combination of dodecylbenzene sulfonic acid or salt thereof (such as sodium salt, potassium salt or ammonium salt), tween 60, tween 80, dodecylbenzene sulfonic acid or salt thereof (such as sodium salt, potassium salt or ammonium salt). The primary hydration reaction aid may be the same as or different from the secondary hydration reaction aid.

According to one embodiment of this first aspect, the method further comprises performing N hydration stages, where N is an integer equal to or greater than 3, and performing a separation step after each hydration stage.

According to an embodiment of this first aspect, the method further comprises the step (11): after step (4) or optional step (4-1) or N-stage hydration and corresponding separation, the gas resulting from step (4) or optional step (4-1) or separation corresponding to N-stage hydration is dried and refrigerated to recover cold.

According to one embodiment of this first aspect, step (5) is carried out in a hydrate resolver operating at a pressure of 1.5-2.0MPaG and at a temperature of 15-20 ℃, all solid hydrates resulting from hydration and corresponding separation of step (4) or optional step (4-1) or group N entering from an inlet of the hydrate resolver, a resolved C1-C2 hydrocarbon stream leaving from an outlet of the resolver, and resolved hydration aid may be retained in the resolver or withdrawn from the resolver in a continuous or intermittent manner.

According to an embodiment of this first aspect, the method further comprises step (5-1): and (5) recovering the desorbed water and the auxiliary agent.

According to one embodiment of this first aspect, the drying of step (6) is carried out in a dryer operating at a temperature of 30 to 75 ℃ and an operating pressure of 1.5 to 2.0MPaG, the dryer having therein a desiccant selected from one of molecular sieves, silica gel or any combination thereof, the C1-C2 hydrocarbon stream from step (5) entering from an inlet of the dryer and exiting from an outlet of the dryer.

In one embodiment, the complexing of step (6) is carried out in a complexing reactor located downstream of the dryer and operating at a pressure of 1.5 to 1.8MPaG and at a temperature ofAnd at the temperature of 20-40 ℃, a complexing agent is arranged in the complexing reactor, and the complexing agent is one of Ag (I) or Cu (I) systems. The dried C1-C2 hydrocarbon material flow enters the complexation reactor from the inlet of the complexation reactor, ethylene reacts with the complexing agent and enters the liquid phase, and the tail gas of the complexation reaction is sent out from the top of the complexation reactor. Ag (i) system complexing agent is selected from one or more of the following: AgNO₃、AgBF₄、AgCF₃CO₂. Cu (i) complexing agent is selected from one or more of: CuAlCl₄、CuCF₃CO₂And CuAl (CN) Cl₃。

According to one embodiment of the first aspect, the step (7) is performed in a complex resolving tower, the operating pressure of the complex resolving tower is 0.1-0.8MPaG, the operating temperature is 50-60 ℃, the ethylene complex product from the step (6) enters from the inlet of the complex resolving tower, the resolved polymerization-grade ethylene product is obtained at the top of the tower, and the complexing agent is extracted from the bottom of the tower.

According to an embodiment of this first aspect, the method further comprises step (7-1): after step (7), the complexing agent is recovered.

According to one embodiment of the first aspect, step (8) is carried out in a depropanizer having a theoretical plate number of 30 to 55, an operating pressure of 1.5 to 2.0MPaG, a feed point of the C3 plus stream from step (2) is at 10 to 30 plates from above, an overhead temperature is 40 to 60 ℃, a column bottom temperature is 90 to 110 ℃, a C3 stream is withdrawn as a gas from the top of the column, and a C4 stream is withdrawn from the bottom of the column.

According to one embodiment of this first aspect, step (9) is carried out in a propylene column having a theoretical plate number of 90 to 130, an operating pressure of 1.5 to 2.0MPaG, a C3 stream from step (8) being fed at a position of 20 to 60 plates from above, an overhead temperature of 40 to 50 ℃, a column bottom temperature of 50 to 60 ℃, a propylene product being obtained from the overhead and propane being obtained from the bottom.

According to one embodiment of the first aspect, the step (10) is performed in a polybutene tower, the number of theoretical plates of the polybutene tower is 70-100, the operating pressure is 0.3-1.0 MPaG, the feeding position of the C4 material flow from the step (8) is at the 30-60 th tower plate from the top, the tower top temperature is 45-55 ℃, the tower bottom temperature is 55-65 ℃, butene products are obtained from the tower top, and butane is obtained from the tower bottom.

A second aspect of the invention provides an apparatus for separating a light hydrocarbon-containing stream, the apparatus comprising: a deethanizer, a first-stage hydration reactor, a first-stage mechanical solid-liquid separator, a hydrate analyzer, a hydrate analysis gas dryer, a complex reactor, a complex analyzer, a depropanizer, a propylene tower and a butylene tower. According to one embodiment of this second aspect, the primary hydration reactor is located downstream of and independent of the deethanizer; the first-stage mechanical solid-liquid separator is arranged in the first-stage hydration reactor; the hydrate resolver is positioned at the downstream of the first-stage hydration reactor; the hydrate desorption gas dryer is positioned at the downstream of the hydrate desorption device; the complex reactor is positioned at the downstream of the hydrate gas analysis dryer; the complex resolver is positioned at the downstream of the complex reactor; a depropanizer is downstream of the deethanizer and upstream of the propylene column and the polybutene column; a propylene column is located downstream of the depropanizer and is independent of the butene column; the butene column is located downstream of the depropanizer and is independent of the propylene column.

According to an embodiment of this second aspect, the apparatus further comprises: a first compressor upstream of the deethanizer; a second compressor downstream of the deethanizer and upstream of the first-stage hydration reactor; a hydration reaction feed cooler downstream of the second compressor and upstream of the primary hydration reactor; a first-stage hydration reactor built-in heat exchanger built-in the first-stage hydration reactor; a primary hydration tail gas dryer downstream of the primary hydration reactor and independent of the hydrate desorber; an expander downstream of the primary hydration reaction tail gas dryer; a complexing agent heat exchanger downstream of the complexing reactor and upstream of the complex resolving tower.

According to an embodiment of this second aspect, the apparatus further comprises: a secondary hydration reactor, at least one inlet of which is connected with at least one outlet of the primary hydration reactor, and a secondary mechanical solid-liquid separator arranged in the secondary hydration reactor.

According to one embodiment of this second aspect, the apparatus further comprises an N-stage hydration reactor having at least one inlet connected to at least one outlet of the N-1 stage hydration reactor, and an N-stage mechanical solid-liquid separator built into the N-stage hydration reactor, wherein N is an integer of 3 or more.

According to an embodiment of this second aspect, the first and second compressors may be integrated into a single multi-stage compressor, in which case the multi-stage compressor has an interstage outlet connected to the deethanizer inlet, a compressor interstage inlet connected to the deethanizer overhead, and a compressor final stage outlet connected to the one-stage hydration reactor cooler inlet.

Some embodiments of the present application will be described below with reference to the accompanying drawings.

Drawings

An illustration of the method and apparatus of the present invention is shown in the drawings, in which:

fig. 1 shows a schematic diagram of an apparatus for separating a light hydrocarbon-containing stream of the present invention.

In the drawings, the names of the components corresponding to the respective reference numerals are as follows:

k201-1 is a first compressor, K201-2 is a second compressor, KT201 is an expander, T201 is a deethanizer, T202 is a hydrate analyzer, T203 is a complex analysis tower, T204 is a depropanizer, T205 is a propylene tower, T206 is a butylene tower, R201 is a primary hydration reactor, R202 is a secondary hydration reactor, R203 is a complexing reactor, D201 is a hydrate analysis gas dryer, D202 is a hydration reaction tail gas dryer, E201 is a hydration reaction feed cooler, E202 is a primary hydration reactor built-in heat exchanger, E203 is a secondary hydration reactor built-in heat exchanger, E204 is a complexing agent heat exchanger, S201 is a primary mechanical solid-liquid separator, S202 is a secondary mechanical solid-liquid separator, V201 is a water and auxiliary agent storage tank, and P201 is a water and auxiliary agent delivery pump;

100 is light hydrocarbon-containing material flow, 201 is material flow below C2, 202 is material flow above C3, 203 is fresh water and auxiliary agent, 204 is hydration reaction tail gas, 205 is complexation reaction tail gas, 206 is ethylene product, 207 is propylene product, 208 is propane, 209 is butylene product, 210 is butane, 211 is fresh complexing agent, and 212 is circulating synthesis gas.

Detailed Description

The "ranges" disclosed herein are expressed in terms of lower and upper limits. There may be one or more lower limits, and one or more upper limits, respectively. The given range is defined by the selection of a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges that can be defined in this manner are inclusive and combinable with each other, i.e., any lower limit can be combined with any upper limit to form a range. For example, ranges of 60-120 and 80-110 are listed for particular parameters, with the understanding that ranges of 60-110 and 80-120 are also contemplated. Further, if the minimum range values listed are 1 and 2, and the maximum range values are 3, 4, and 5, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5.

In this application, unless otherwise stated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0 to 5" indicates that all real numbers between "0 to 5" have been listed herein, and "0 to 5" is only a shorthand representation of the combination of these numbers.

In this application, the word "above" or "below" following a number includes the word. For example, "5 or less" means 5 or less, and "7 or more" means 7 or more.

In the present application, all embodiments and preferred embodiments mentioned herein may be combined with each other to form new solutions, if not specifically stated.

In the present application, all the technical features mentioned herein as well as preferred features may be combined with each other to form new technical solutions, if not specifically stated.

In the present application, all steps mentioned herein may be performed sequentially or randomly, if not specifically stated, but preferably sequentially. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, and may also comprise steps (b) and (a) performed sequentially. For example, reference to the process further comprising step (c) means that step (c) may be added to the process in any order, for example, the process may comprise steps (a), (b) and (c), may also comprise steps (a), (c) and (b), may also comprise steps (c), (a) and (b), etc.

In the present application, the term "comprising" as used herein means open or closed unless otherwise specified. For example, the term "comprising" may mean that other components not listed may also be included, or that only listed components may be included.

In this application, the terms "upstream" and "downstream" describe the relative positions of various components with respect to the flow of material, i.e., the flow of material passes "upstream" and then "downstream".

In the present application, the term "stream" means any flowable material fluid used or processed in the methods and apparatus of the present application, having objectively present material properties and flowable properties, which may include a gas, a liquid, a mixture of a gas and a liquid, a mixture of a liquid and a liquid, a solution of a gas in a liquid, a solution of a liquid in a liquid, a solution or suspension of a solid in a liquid, or a combination of one or more of the foregoing. For example, a light hydrocarbon-containing stream that is the initial feedstock (e.g., directly from catalytic cracking dry gas, Fischer-Tropsch tail gas, methanol to olefins product gas; or product gas from a synthesis reactor, and which has been subjected to pretreatment including condensation, water washing, decarbonization, drying, pressure swing adsorption, membrane separation, or oil washing), any portion separated from the initial feedstock, and any reagents added to or recovered from the process can be referred to herein as a "stream".

The term "light hydrocarbon-containing stream" is a stream comprising predominantly C1-C4 hydrocarbon compounds and H₂The mixture of CO, depending on the specific source of the light hydrocarbon-containing stream, the preparation process and the separation technique, may also contain other unavoidable impurities in relatively low proportions, but in very low amounts, and as such, is used in this applicationThe separation and purification processes of the present application are substantially simultaneously removed and their content in the final product stream is at an acceptable level, and therefore the separation of these impurities is not of particular concern in the present application. According to one embodiment of the invention, the process and apparatus of the present application are used to treat "light hydrocarbon-containing streams". For example, the "light hydrocarbon-containing stream" may be a hydrocarbon-containing stream directly from catalytic cracking dry gas, fischer-tropsch synthesis tail gas, methanol to olefin product gas, or may be a product gas from a synthesis reactor, and the product gas is subjected to pretreatment such as condensation, water washing, decarbonization, drying, pressure swing adsorption, membrane separation, or oil washing.

Catalytic cracking is a process in which heavy oil undergoes a cracking reaction under the action of heat and a catalyst to convert into cracked gas, gasoline, diesel oil and the like. The catalytic cracking dry gas is a non-condensable gas recovered in the catalytic cracking process. The process for directly preparing olefin (FTO) from Fischer-Tropsch synthesis gas or synthesis gas is a process for synthesizing hydrocarbon mixtures with various carbon numbers by using synthesis gas (mixed gas of carbon monoxide and hydrogen) as a raw material under a catalyst and proper conditions, wherein the olefin content in products of the FTO process is far greater than that of alkane. Methanol To Olefin (MTO) is a chemical technology for producing low-carbon olefins by taking methanol synthesized by coal or natural gas as a raw material and using a fluidized bed reaction form similar to a catalytic cracking device. The corresponding gas of the above process can be used as the light hydrocarbon-containing stream of the present invention.

In one embodiment of the invention, the light hydrocarbon-containing stream comprises predominantly H₂CO, methane, ethane, ethylene, propane, propylene, butylene.

In one embodiment of the invention, the light hydrocarbon-containing stream comprises 1 to 70% H₂10-40% of CO, 1-20% of methane, 0.1-10% of ethane, 1-25% of ethylene, 0.1-10% of propane, 1-15% of propylene and 1-10% of butylene, wherein the percentages are volume percentages. According to one embodiment of the invention, the content of other components in the light hydrocarbon-containing stream is 15 vol% or less, alternatively 12 vol% or less, alternatively 10 vol% or less, alternatively 8 vol% or less, alternatively 6 vol% or less, alternatively 5 vol% or less,or less than or equal to 4 volume percent, or less than or equal to 3 volume percent, or less than or equal to 2 volume percent, or less than or equal to 1 volume percent.

According to a preferred embodiment of the invention, the light hydrocarbon-containing stream as initial feedstock is dry gas from catalytic cracking. According to another preferred embodiment of the invention, the light hydrocarbon-containing stream as initial feedstock is a tail gas of the fischer-tropsch synthesis. According to another preferred embodiment of the present invention, the light hydrocarbon-containing stream as the initial feedstock is a hydrocarbon-containing stream of methanol to olefins product gas. According to another preferred embodiment of the invention, the light hydrocarbon-containing stream as initial feedstock is the product gas of a synthesis reactor. According to another preferred embodiment of the present invention, the product gas is subjected to a pretreatment comprising one or more of condensation, water washing, decarbonation, drying, pressure swing adsorption, membrane separation or oil washing. The oxygenates in the feed are removed in the pretreatment.

Additionally, in the present application, using Cn hydrocarbons (or Cn streams) to refer to a collection or mixture of hydrocarbons having n carbon atoms, for example C2 hydrocarbons to refer to a collection or mixture of hydrocarbons having 2 carbon atoms, in one embodiment of the present application, C2 hydrocarbons may include alkanes having two carbon atoms, i.e., ethane, and alkenes having two carbon atoms, i.e., ethylene. By a hydrocarbon stream above Cn is meant herein a collection or mixture of hydrocarbons having n or more carbon atoms, for example a hydrocarbon stream above C3 means a collection or mixture of hydrocarbons having 3 or more carbon atoms. By sub-Cn hydrocarbon stream is meant herein a collection or mixture of hydrocarbons having n carbon atoms or less, for example, sub-C2 hydrocarbon streams refer to a collection or mixture of hydrocarbons having 2 carbon atoms or less. Similarly, throughout this application a collective or mixture of materials having n or fewer carbon atoms is referred to by a sub-Cn stream, for example, a sub-C2 stream refers to a collective or mixture of alkanes, alkenes, having 2 or more carbon atoms.

It is emphasized here that the embodiments shown in the figures and described below are merely exemplary embodiments of the invention, to which the scope of protection of the invention is not limited. The scope of the invention is defined by the claims and may include any embodiments within the scope of the claims, including but not limited to further modifications and alterations to these embodiments.

The method and apparatus of the present invention will now be described in detail with reference to figure 1. In one embodiment, the present invention provides a process for separating a light hydrocarbon-containing stream, the separation process being carried out using the apparatus shown in fig. 1. The method includes steps (1) to (8) described below.

Step (1): a stream 100 comprising light hydrocarbons is provided. The stream 100 may have various different compositions depending on the source of the stream 100. For example, the stream 100 may comprise, in addition to ethylene, propylene, butylene, the following components: h₂CO, n-alkanes below C4, isoparaffins, cycloalkanes, 1-alkenes other than ethylene, propylene, butene. In one embodiment, the light hydrocarbon-containing stream 100 is directly from catalytic cracking dry gas, fischer-tropsch synthesis tail gas, and methanol to olefin product gas. In another embodiment, the light hydrocarbon-containing stream 100 is derived from a product gas from a synthesis reactor, and the product gas is pretreated. Such pretreatments include, for example, condensation, water washing, decarbonization, drying, pressure swing adsorption, membrane separation, oil washing, or any pretreatment that can increase the light hydrocarbon content, particularly the ethylene, propylene, butene content. According to a preferred embodiment, the ethylene mole percent content in light hydrocarbon-containing stream 100 can be 30% or greater, or 50% or greater; the mol percentage of the propylene can be more than or equal to 30 percent or more than or equal to 50 percent; the content of the butylene in mole percent can be more than or equal to 20 percent or more than or equal to 30 percent.

In one embodiment, in this step (1), the light hydrocarbon-containing stream 100 is sent to a first compressor K201-1 for compression to pressurize the light hydrocarbon-containing stream 100 to 2.0 to 2.2MPaG, and then the pressurized light hydrocarbon-containing stream is sent to a deethanizer T201 for performing step (2). In one embodiment, the light hydrocarbon-containing stream 100 entering the deethanizer T201 has a feed temperature of 30 to 50 ℃.

Step (2): the light hydrocarbon containing stream 100 is cut in deethanizer T201. In this step, at least the light hydrocarbon-containing stream 100 is divided into a stream 201 below C2 and a stream 202 above C3. In one embodiment, the deethanizer is operated at a pressure of 2.0 to 2.2MPaG and a theoretical plate number of 35 to 60. The feeding position of the light hydrocarbon-containing material flow 100 is at the 10 th to 35 th tower plates from the top, the temperature at the top of the tower is-75 ℃ to-40 ℃, the temperature at the bottom of the tower is 50 ℃ to 90 ℃, the material flow 201 below C2 is taken as gas and taken out from the top of the tower, and the material flow 202 above C3 is taken as tower bottom liquid and taken out from the bottom of the tower.

And (3): and (3) carrying out primary hydration on the stream 201 below the C2 obtained in the step (2) so as to enable the C1-C2 hydrocarbon to react in the presence of a first hydration reaction auxiliary agent to generate a first solid hydrate floating on the liquid surface, thereby separating the first solid hydrate from the tail gas of the primary hydration reaction. Step (3) is carried out in a primary hydration reactor R201, the operating pressure of the primary hydration reactor R201 is 5.2-6.2MPaG, the operating temperature is 0-5 ℃, a stream 201 below C2 from step (2) enters from the inlet of the primary hydration reactor R201, and a primary hydration reaction auxiliary agent exists in the reactor R201.

According to an embodiment of the present invention, the primary hydration reaction assistant is selected from one or any group of dodecylbenzene sulfonic acid or a salt thereof (e.g., sodium salt, potassium salt or ammonium salt), tween 60, tween 80, dodecylbenzene sulfonic acid or a salt thereof (e.g., sodium salt, potassium salt or ammonium salt).

According to one embodiment of the present invention, the concentration of the primary hydration reaction assistant is 300 to 1000ppm, preferably 400 to 600ppm, based on the mass concentration.

And (4): separating the first solid hydrate from the reaction liquid of step (3). Step (4) is performed by a mechanical separator S201 built in the primary hydration reactor R201 or located downstream of the outlet of the primary hydration reactor R201. The mechanical separator S201 may be any mechanical separator known in the art, for example, a centrifugal separation device, a suction filtration device, or a belt separation device.

Optionally, the tail gas exiting from one outlet of the primary hydration reactor may be further sent to a secondary hydration reactor R202 to further hydrate the unreacted C1-C2 hydrocarbons in the tail gas to form a second solid hydrate, i.e., step (3-1). The yield of C1-C2 hydrocarbons can be further improved in the step (3-1). The secondary hydration reactor R202 may be the same as or different from the primary hydration reactor R201. In one embodiment, the secondary hydration reactor R202 is operated at a pressure of 5.2 to 6.2mpa g and at a temperature of 0 to 5 ℃, the off-gas from step (3) enters from the inlet of the secondary hydration reactor R202, and secondary hydration reaction aid is present in the reactor R202.

According to an embodiment of the present invention, the secondary hydration reaction assistant is selected from one or any group of dodecylbenzene sulfonic acid or a salt thereof (e.g., sodium salt, potassium salt or ammonium salt), sodium dodecylbenzene sulfonate, tween 60, tween 80, dodecylbenzene sulfonic acid or a salt thereof (e.g., sodium salt, potassium salt or ammonium salt). In one embodiment, the secondary hydration reaction aid is the same as the primary hydration reaction aid. In another embodiment, the secondary hydration reaction aid is different from the primary hydration reaction aid.

According to one embodiment of the present invention, the concentration of the secondary hydration reaction assistant is 300 to 1000ppm, preferably 400 to 600ppm, based on the mass concentration.

After the step (3-1), a step (4-1) may be further performed to isolate a second solid hydrate. The step (4-1) is performed by a mechanical separator S202 built in the secondary hydration reactor R202 or located downstream of the outlet of the secondary hydration reactor R202. The mechanical separator S202 may be any mechanical separator known in the art, for example, a centrifugal separation device, a suction filtration device, or a belt separation device. In one embodiment, the mechanical separator S202 is the same as the mechanical separator S201. In another embodiment, the mechanical separator S202 is different from the mechanical separator S201.

According to one embodiment of the application, the method can further comprise the step of carrying out further hydration and corresponding mechanical separation on the reaction tail gas of the N-1 stage hydration reactor by using an N stage hydration reactor, so as to further improve the yield of the C1-C2 hydrocarbon, wherein N is an integer which is greater than or equal to 3.

The method further comprises a step (11): after step (4) or optional step (4-1) or N-stage hydration and corresponding separation, the gas resulting from step (4) or optional step (4-1) or separation corresponding to N-stage hydration is dried and refrigerated to recover cold. Specifically, the gas enters a hydration reaction tail gas dryer D202 for dehydration, and then is sent to an expander KT201 for refrigeration, and the pressure after expansion is 0.30-0.85 MPaG. The resulting cold is used to remove the exothermic heat of the hydration reactor and to control the temperature of the hydration reactor. When a second-stage hydration reactor R202 exists, an outlet of a hydration reaction tail gas dryer D202 is connected to an inlet of an expander KT201, an outlet of the expander KT201 is divided into two paths, one path is connected to an inlet of a first-stage hydration reactor heat exchanger E202, the other path is connected to an inlet of a second-stage hydration reactor heat exchanger E203, and outlets of the heat exchangers E202 and E203 are connected to an inlet of a synthesis reactor after being converged.

And (5): resolving the primary and/or secondary solid hydrate from step (4) or step (4-1) to resolve a C1-C2 hydrocarbon stream. When a secondary solid hydrate exists, the secondary hydrate and the primary hydrate can be combined and then resolved. This step (5) is carried out in a hydrate resolver T202, said hydrate resolver T202 operating at a pressure of 1.5-2.0MPaG and at a temperature of 15-20 ℃. The primary solid hydrate from step (4) or step (4-1) enters from the inlet of the hydrate resolver T202, the resolved C1-C2 hydrocarbon stream exits from an outlet of the resolver T202 as hydrate resolving gas, and the resolved hydration aid remains in the resolver T202.

In one embodiment, the method further comprises step (5-1): and (5) recovering the desorbed water and the auxiliary agent. The recovered hydration aid may be stored in the hydration aid storage tank V201 along with fresh hydration aid make-up. At least one inlet of the hydration aid storage tank V201 is connected with at least one outlet of the hydrate resolver T202, and at least one outlet of the hydration aid storage tank V201 is connected with at least one inlet of the primary hydration reactor R201 to add the hydration aid to the primary hydration reactor R201 by the hydration aid transfer pump P201. When the primary hydration aid and the secondary hydration aid are the same, the hydration aid can be respectively conveyed to the primary hydration reactor R201 and the secondary hydration reactor R202 from the same hydration aid storage tank V201 by the hydration aid conveying pump P201. When the primary hydration aid and the secondary hydration aid are different, each hydration reactor R201 or R202 may have a separate hydration aid storage tank and a hydration aid transfer pump to transfer the corresponding hydration aid to the corresponding hydration reactor, respectively.

And (6): drying the C1-C2 hydrocarbon stream obtained in step (5), and subsequently contacting the dried C1-C2 hydrocarbon stream with a complexing agent to react ethylene therein with the complexing agent to obtain an ethylene complex. The drying in the step (6) is carried out in a hydrate gas-resolving dryer D201, the operating temperature of the dryer D201 is 30-75 ℃, the operating pressure is 1.5-2.0MPaG, a drying agent is arranged in the dryer, and the drying agent is selected from one or any combination of a molecular sieve and silica gel. A C1-C2 hydrocarbon stream from step (5) entering from the inlet of the dryer and exiting from the outlet of the dryer.

The molecular sieve is zeolite or natural zeolite. Specifically, the type of molecular sieve used is selected from any one of 3A, 4A, 5A, 10Z, 13X, Y type, mordenite type or a combination thereof.

The silica gel may be selected from any one or a combination of fine, coarse and blue silica gels.

And (3) carrying out complexation in a complexation reactor R203, wherein the complexation reactor R203 is positioned at the downstream of the dryer, the operating pressure is 1.5-1.8MPaG, the operating temperature is 20-40 ℃, and a complexing agent is arranged in the complexation reactor and is one of Ag (I) or Cu (I) systems. Ag (i) complexing agent is selected from one or more of: AgNO₃、AgBF₄、AgCF₃CO₂The cu (i) complexing agent is selected from one or more of the following: CuAlCl₄、CuCF₃CO₂And CuAl (CN) Cl₃. The dried C1-C2 hydrocarbon material flow enters a complexing reactor R203 from the inlet of the complexing reactor, ethylene of the C1-C2 hydrocarbon material flow reacts with a complexing agent and enters a liquid phase, and tail gas of the complexing reaction is sent out from the top of the complexing reactor R203.

The concentration of the complexing agent is 300 to 1000ppm, preferably 400 to 600 ppm.

And (7): resolving the ethylene complex obtained from step (6) to liberate ethylene product. The step (7) is carried out in a complex analysis column T203, wherein the operating pressure of the complex analysis column T203 is 0.1-0.8MPaG, and the operating temperature is 50-60 ℃. And (3) the ethylene complexing product from the step (6) enters from a T203 inlet of a complex analysis tower, a polymer-grade ethylene product 206 obtained by analysis is obtained at the top of the tower, and a complexing agent is extracted from the bottom of the tower.

In one embodiment, the method further comprises step (7-1): after step (7), the complexing agent is recovered.

And (8): separating the stream 202 above C3 resulting from step (2) to separate the stream 202 above C3 into a C3 stream and a C4 stream. And (3) the step (8) is carried out in a depropanizer T204, the theoretical plate number of the depropanizer T204 is 30-55, the operation pressure is 1.5-2.0MPaG, the feeding position of the material flow 202 above C3 from the step (2) is at the 10 th-30 th plate from the top, the tower top temperature is 40-60 ℃, the tower kettle temperature is 90-110 ℃, the C3 material flow is taken as gas and taken out from the tower top, and the C4 material flow is taken out from the tower bottom.

And (9): the C3 stream resulting from step (8) is separated to yield propylene product 207 and propane 208. And (3) the step (9) is carried out in a propylene tower T205, the theoretical plate number of the propylene tower T205 is 90-130, the operation pressure is 1.5-2.0MPaG, the feeding position of the C3 material flow from the step (8) is at the 30 th-65 th plate from the top, the tower top temperature is 40-50 ℃, the tower bottom temperature is 50-60 ℃, a propylene product is obtained from the tower top, and propane is obtained from the tower bottom.

Step (10): the C4 stream resulting from step (8) is separated to yield a butene product and butane. And (10) performing in a decamethylene tower, wherein the theoretical plate number of the decamethylene tower is 70-100, the operation pressure is 0.3-1.0 MPaG, the feeding position of the C4 material flow from the step (8) is at the 30-60 tower plates from top, the tower top temperature is 45-55 ℃, the tower bottom temperature is 55-65 ℃, a butene product 209 is obtained from the tower top, and butane 210 is obtained from the tower bottom.

The resulting propylene product 207, propane 208, butene product 209, butane 210 may be further separated and purified, if desired, to obtain a product that meets practical requirements. The separation and purification can use any method step known in the art, for example, distillation, rectification, azeotropic rectification, extraction, and the like.

According to the operation, the recovery rate of ethylene can reach more than 85.0 percent, the recovery rate of propylene can reach more than 99.0 percent, and the recovery rate of butylene can reach more than 99.5 percent. And the purity of ethylene, propylene and butylene can reach more than 99.5 percent.

Without wishing to be bound by any particular theory, the present invention has the following advantages over the prior art:

(1) the invention adopts hydration reaction to react the hydrocarbon with H₂And the CO synthetic gas is separated, the hydration reaction and the desorption temperature are both above 0 ℃, and the energy consumption is obviously reduced compared with the conventional cryogenic separation.

(2) The hydrocarbon mixed gas realizes high-purity separation of ethylene in the hydrocarbon mixed gas through a complex reaction, and avoids the adoption of high-energy-consumption high-investment ethylene precision rectification.

(3) The whole separation process adopts a specific separation sequence of hydration and complexation, so that the high recovery rate of the low-carbon hydrocarbons can be realized, and the influence on the quality of ethylene products caused by the active reaction of CO and a complexing agent can be avoided.

(4) In addition, the hydration reaction can also improve the recovery rate of methane by adjusting the reaction pressure and temperature, and avoid the accumulation of non-synthesis gas components to increase the circulation volume of the system and even influence the synthesis reaction. If the cryogenic separation technology is adopted to improve the methane recovery rate, the energy consumption is obviously increased, meanwhile, effective synthesis gas components are lost, and the utilization rate of the synthesis gas is reduced.

Examples

Preferred embodiments of the present invention are specifically exemplified in the following examples, but it should be understood that the scope of the present invention is not limited thereto. In the following embodiments of the present application, the catalytic cracking dry gas, the tail gas of the fischer-tropsch device, and the tail gas of the device for directly producing olefins from synthesis gas are used as raw materials. In the following examples, the stream composition measurements obtained by calculation are listed in tables 1-3.

Example 1:

the starting material used in this example was an industrially obtained catalytic cracking dry gas having a composition of H₂-47.4％、CO-1％、N₂-9.9％、CH₄-17.2％、C₂H₄-8％、C₂H₆-9.4％、C₃H₆-3.5％、C₃H₈-0.5％、C₄H₈-1.1% and C₄H₁₀1.9 percent, the percentages are volume percentages, the molar flow of the catalytic cracking dry gas is 1635.351kmol/h, and the feeding temperature is 40 ℃.

As shown in fig. 1, a light hydrocarbon-containing material stream 100 is pressurized to 2.2MPaG by a first-stage compressor K201-1 and cooled, and then sent to a deethanizer T201 to perform clear cutting of a material stream below C2 and a material stream above C3, the operating pressure of the deethanizer T201 is 2.1MPaG, a material stream 202 above C3 is extracted from a liquid phase in a tower bottom and sent to a depropanizer T204 to perform cutting of C3 and C4 components, a gas phase component at the top of the depropanizer T204 is continuously sent to a propylene tower T205 to perform separation of propylene products, the product propylene 207 is obtained at the top of the propylene tower T205, propane 208 is obtained at the bottom of the tower, a material at the bottom of the depropanizer T204 is sent to a butene tower T206 to perform separation of butene, a butene product 209 is obtained at the top of the butene tower T206, and butane 210 is obtained at the. The depropanizer T204, propene column T205 and butene column T206 operating pressures were 1.77MPaG, 1.72MPaG and 0.5MPaG, respectively.

The gas phase material flow 201 at the top of the deethanizer T201, namely the material flow 201 below C2, is pressurized to 5.8MPaG by a secondary compressor K201-2, is cooled to 4 ℃ by a hydration reaction feeding cooler E201 and enters a first-stage hydration reactor R201, the operation pressure of the hydration reactor is 5.8MPaG, the temperature is 3 ℃, the hydrocarbon in the material flow 201 below C2 reacts with water under the action of a hydration assistant sodium dodecyl sulfate to form a solid phase hydrate and floats on the liquid level of the reactor, and the solid phase hydrate is separated by a mechanical solid-liquid separator S201 and is sent to a hydrate analyzer T202. The reacted tail gas is continuously sent to a secondary hydration reactor R202 for hydration reaction to improve the recovery rate of the hydrocarbon in the stream 201 below C2, the operating pressure of the secondary hydration reactor is 5.7MPaG, and the temperature is 3 ℃. And (3) dehydrating reaction tail gas 204 from the second-stage hydration reactor R202 by using a hydration reaction tail gas dryer D202, and then sending the dehydrated reaction tail gas to an expander KT201 for refrigeration, wherein the pressure after expansion is 0.55MPaG, the obtained cold energy is used for removing the heat release heat of the hydration reactor and controlling the temperature of the hydration reactor to 3.5 ℃, and the synthesis gas 212 after cold energy recovery can be circularly used in the synthesis reactor.

Solid phase hydrate in the first-stage hydration reactor and the second-stage hydration reactor is conveyed to a hydrate analyzer T202 through a mechanical solid-liquid separator, and C is released by analyzing after the temperature is raised to 18 DEG C₂H₄、C₂H₆And part of CH₄Wherein the pressure of the hydrate resolver T202 is controlled at 1.8 MPaG. The desorbed water and the auxiliary agent are sent to a water and auxiliary agent storage tank V201, and are returned to the first-stage hydration reactor R201 and the second-stage hydration reactor R202 together with a small amount of supplemented fresh water and the auxiliary agent 203 through a delivery pump P201. The desorbed gas-phase hydrocarbons are dehydrated to ppm level by a hydrate desorption gas dryer D201 and then sent to a complexing reactor R203, and the reaction pressure of the complexing reactor R203 is 1.6 MPaG. The mixed hydrocarbons are separated with high purity from ethylene in a complexation reactor R203 through the reaction of CuAlCl4 complexing agent and olefin, and unreacted alkane CH₄And C₂H₆Sent from the top of the complexing reactor R203 to be used as fuel gas 205 or to be reprocessed C₂H₄The liquid phase complex enters into a liquid phase complex, is subjected to heat exchange through a complexing agent heat exchanger E204 and then is sent to a complex analysis tower T203 for analysis, the operating pressure of the analysis tower is 0.6MPaG, the temperature is 55 ℃, a product ethylene 206 is analyzed out from the top of the tower, the complexing agent extracted from the bottom of the tower is subjected to heat exchange through the complex heat exchanger E204 and then is sent to a complexing reactor R203 for recycling, and the consumed complexing agent is completed by supplementing fresh complexing agent 211.

TABLE 1 catalytic cracking Dry gas separation results

As can be seen from the data in the material flow table 1, the ethylene recovery rate reaches 90.54%, the propylene recovery rate reaches 99.58%, and the butene recovery rate reaches 99.64%. In addition, the purity of ethylene, propylene and butylene products can exceed 99.5 percent.

Example 2:

the starting material used in this example was an industrially obtained tail gas from a Fischer-Tropsch plant, having a composition H₂-43.5％、CO-17.1％、N₂-4.9％、CH₄-18.5％、C₂H₄-1.9％、C₂H₆-4.1％、C₃H₆-5.3％、C₃H₈-1.6％、C₄H₈-2.6% and C₄H₁₀-0.7% by volume, a molar flow of 1514.579kmol/h and a feed temperature of 40 ℃.

The gas phase material flow 201 at the top of the deethanizer T201, namely the material flow 201 below C2, is pressurized to 5.7MPaG by a secondary compressor K201-2, is cooled to 2 ℃ by a hydration reaction feeding cooler E201 and enters a first-stage hydration reactor R201, the operation pressure of the hydration reactor is 5.7MPaG, the temperature is 2 ℃, the hydrocarbon in the material flow 201 below C2 reacts with water under the action of a hydration assistant sodium dodecyl sulfate to form a solid phase hydrate and floats on the liquid level of the reactor, and the solid phase hydrate is separated by a mechanical solid-liquid separator S201 and is sent to a hydrate analyzer T202. The reacted tail gas is continuously sent to a secondary hydration reactor R202 for hydration reaction to improve the recovery rate of the hydrocarbon in the stream 201 below C2, the operating pressure of the secondary hydration reactor is 5.6MPaG, and the temperature is 2 ℃. And (3) dehydrating reaction tail gas 204 from the second-stage hydration reactor R202 by using a hydration reaction tail gas dryer D202, then sending the dehydrated reaction tail gas to an expander KT201 for refrigeration, wherein the pressure after expansion is 0.55MPaG, the obtained cold energy is used for removing the heat release heat of the hydration reactor and controlling the temperature of the hydration reactor to 2 ℃, and the synthesis gas 212 after cold energy recovery can be recycled for use in the synthesis reactor.

Solid phase hydrate in the first-stage hydration reactor and the second-stage hydration reactor is conveyed to a hydrate analyzer T202 through a mechanical solid-liquid separator, and C is released by analyzing after the temperature is raised to 17 DEG C₂H4、C₂H₆And part of CH₄Wherein the pressure of hydrate resolver T202 is controlled at 1.6 MPaG. The desorbed water and the auxiliary agent are sent to a water and auxiliary agent storage tank V201, and are returned to the first-stage hydration reactor R201 and the second-stage hydration reactor R202 together with a small amount of supplemented fresh water and the auxiliary agent 203 through a delivery pump P201. The desorbed gas-phase hydrocarbons are dehydrated to ppm level by a hydrate desorption gas dryer D201 and then sent to a complexing reactor R203, and the reaction pressure of the complexing reactor R203 is 1.5 MPaG. The mixed hydrocarbons are separated with high purity from ethylene in a complexation reactor R203 through the reaction of CuAlCl4 complexing agent and olefin, and unreacted alkane CH₄And C₂H₆Sent from the top of the complexing reactor R203 to be used as fuel gas 205 or to be reprocessed C₂H₄The liquid phase complex enters into a liquid phase complex, is subjected to heat exchange through a complexing agent heat exchanger E204 and then is sent to a complex analysis tower T203 for analysis, the operating pressure of the analysis tower is 0.4MPaG, the temperature is 56 ℃, a product ethylene 206 is analyzed out from the top of the tower, the complexing agent extracted from the bottom of the tower is subjected to heat exchange through the complex heat exchanger E204 and then is sent to a complexing reactor R203 for recycling, and the consumed complexing agent is completed by supplementing fresh complexing agent 211.

TABLE 2 Fischer-Tropsch Tail gas separation results

As can be seen from the data in the material flow table 2, the ethylene recovery rate reaches 87.47%, the propylene recovery rate reaches 99.47%, and the butene recovery rate reaches 99.74%. In addition, the purity of ethylene, propylene and butylene products can exceed 99.5 percent.

Example 3:

the starting material used in this example was the tail gas from a commercially available synthesis gas direct olefin plant, which had a composition of H₂-7.2％、CO-53.7％、N₂-0.6％、CH₄-1.5％、C₂H₄-7.4％、C₂H₆-0.8％、C₃H₆-17.4％、C₃H₈-0.8％、C₄H₈-10.2% and C₄H₁₀-0.6% by volume, a molar flow of 791.261kmol/h, and a feed temperature of 40 ℃.

The gas phase material flow 201 at the top of the deethanizer T201, namely the material flow 201 below C2, is pressurized to 5.9MPaG by a secondary compressor K201-2, is cooled to 1 ℃ by a hydration reaction feeding cooler E201 and enters a first-stage hydration reactor R201, the operation pressure of the hydration reactor is 5.9MPaG, the temperature is 4 ℃, the hydrocarbon in the material flow 201 below C2 reacts with water under the action of a hydration assistant sodium dodecyl sulfate to form a solid phase hydrate and floats on the liquid level of the reactor, and the solid phase hydrate is separated by a mechanical solid-liquid separator S201 and is sent to a hydrate analyzer T202. The reacted tail gas is continuously sent to a secondary hydration reactor R202 for hydration reaction to improve the recovery rate of the hydrocarbon in the stream 201 below C2, the operating pressure of the secondary hydration reactor is 5.8MPaG, and the temperature is 2 ℃. Reaction tail gas 204 from the second-stage hydration reactor R202 is dehydrated by a hydration reaction tail gas dryer D202 and then is sent to an expander KT201 for refrigeration, the pressure after expansion is 0.55MPaG, the obtained cold energy is used for removing the heat release heat of the hydration reactor and controlling the temperature of the hydration reactor to be stable, and the synthesis gas 212 after cold energy recovery can be circularly used for the synthesis reactor.

Solid phase hydrate in the first-stage hydration reactor and the second-stage hydration reactor is conveyed to a hydrate analyzer T202 through a mechanical solid-liquid separator, and C is released by analyzing after the temperature is raised to 19 DEG C₂H4、C₂H₆And part of CH₄Wherein the pressure of hydrate resolver T202 is controlled at 1.9 MPaG. The desorbed water and the auxiliary agent are sent to a water and auxiliary agent storage tank V201, and are returned to the first-stage hydration reactor R201 and the second-stage hydration reactor R202 together with a small amount of supplemented fresh water and the auxiliary agent 203 through a delivery pump P201. The desorbed gas-phase hydrocarbons are dehydrated to ppm level by a hydrate desorption gas dryer D201 and then sent to a complexing reactor R203, and the reaction pressure of the complexing reactor R203 is 1.6 MPaG. The mixed hydrocarbons are separated with high purity from ethylene in a complexation reactor R203 through the reaction of CuAlCl4 complexing agent and olefin, and unreacted alkane CH₄And C₂H₆Sent from the top of the complexing reactor R203 to be used as fuel gas 205 or to be reprocessed C₂H₄The liquid phase complex enters into a liquid phase complex, is subjected to heat exchange through a complexing agent heat exchanger E204 and then is sent to a complex analysis tower T203 for analysis, the operating pressure of the analysis tower is 0.5MPaG, the temperature is 55 ℃, a product ethylene 206 is analyzed out from the top of the tower, the complexing agent extracted from the bottom of the tower is subjected to heat exchange through the complex heat exchanger E204 and then is sent to a complexing reactor R203 for recycling, and the consumed complexing agent is completed by supplementing fresh complexing agent 211.

TABLE 3 separation results of tail gas from direct olefin production from syngas

As can be seen from the data in the flow chart 3, the ethylene recovery rate reaches 90.51%, the propylene recovery rate reaches 99.52%, and the butene recovery rate reaches 99.72%. In addition, the purity of ethylene, propylene and butylene products can exceed 99.5 percent.

Claims

1. A process for separating a light hydrocarbon-containing stream, the process comprising:

step (1): providing a light hydrocarbon-containing stream;

and (3): subjecting the stream below C2 obtained from step (2) to primary hydration to react the C1-C2 hydrocarbons with the first hydration reaction promoter to form a first solid hydrate in the reaction liquid, thereby separating the first solid hydrate from the tail gas of the primary hydration reaction;

and (4): separating the first solid hydrate from the liquid of step (3);

and (5): resolving the first solid hydrate to resolve a C1-C2 hydrocarbon stream;

2. The process of claim 1, wherein the light hydrocarbon-containing stream of step (1) is (a) a hydrocarbon-containing stream directly from catalytic cracking dry gas, fischer-tropsch synthesis tail gas, methanol to olefins product gas; or (b) a product gas from a synthesis reactor, and the product gas is subjected to a pretreatment comprising one or more of condensation, water washing, decarbonation, drying, pressure swing adsorption, membrane separation, or oil washing;

wherein the feeding temperature of the light hydrocarbon-containing material flow is 30-50 ℃.

3. The process of claim 1 or 2, wherein the cutting in step (2) is carried out in a deethanizer, wherein the deethanizer is operated at a pressure of 2.0 to 2.2MPaG and a theoretical plate number of 35 to 60, the light hydrocarbon-containing stream is fed at a position of 15 to 35 plates from the top, the overhead temperature is-90 to-40 ℃, the bottom temperature of the tower is 50 to 90 ℃, the stream below C2 is taken as a gas from the top of the tower, and the stream above C3 is taken as a liquid from the bottom of the tower.

4. The method of any one of claims 1-3, wherein:

step (3) is carried out in a first-stage hydration reactor, the operating pressure of the first-stage hydration reactor is 5.2-6.2MPaG, the operating temperature is 0-5 ℃, the material flow which is lower than C2 and is from the step (2) enters from the inlet of the first-stage hydration reactor, a first-stage hydration reaction auxiliary agent exists in the reactor,

wherein, the first-stage hydration reaction auxiliary agent is one or any combination of dodecylbenzene sulfonic acid or salt thereof, tween 60, tween 80, dodecylbenzene sulfonic acid or salt thereof; and/or

The step (4) is carried out by a mechanical separator which is arranged in the first-stage hydration reactor or is positioned at the downstream of the outlet of the first-stage hydration reactor; and/or

The method further comprises the following steps:

step (3-1): performing secondary hydration on the tail gas of the primary hydration reaction in the step (3) so that the C1-C2 hydrocarbon in the tail gas reacts in the presence of a second hydration reaction auxiliary agent to generate a second solid hydrate floating on the liquid surface, so as to be separated from the tail gas of the secondary hydration reaction, preferably, the step (3-1) is performed in a secondary hydration reactor, the operating pressure of the secondary hydration reactor is 5.2-6.2MPaG, the operating temperature is 0-5 ℃, the tail gas of the primary hydration reaction in the step (3) enters from the inlet of the secondary hydration reactor, and the secondary hydration reaction auxiliary agent is present in the secondary hydration reactor, wherein the secondary hydration reaction auxiliary agent is selected from one or any combination of dodecyl benzene sulfonic acid or salt thereof, Tween 60, Tween 80, dodecyl sulfonic acid or salt thereof; and/or

Step (4-1): separating the liquid from the solid of step (3-1) to obtain a second solid hydrate and combining with the first solid hydrate of step (4); (ii) a And/or

Carrying out N-stage hydration and carrying out a separation step after each hydration, wherein N is an integer greater than or equal to 3 and/or

The method further comprises a step (11): after step (4) or optional step (4-1) or N-stage hydration and corresponding separation, the gas resulting from step (4) or optional step (4-1) or separation corresponding to N-stage hydration is dried and refrigerated to recover cold.

5. The process of any one of claims 1 to 4, wherein step (5) is carried out in a hydrate resolver operating at a pressure of from 1.5 to 2.0MPaG and at a temperature of from 15 to 20 ℃, wherein all solid hydrates separated enter from the inlet of the hydrate resolver, a resolved C1-C2 hydrocarbon stream exits from the outlet of the resolver, and resolved hydration aid remains in the resolver or is withdrawn from the resolver in a continuous or intermittent manner, and/or

The method further optionally comprises step (5-1): recovering the resolved hydration aid after step (5).

6. The method of any one of claims 1 to 5, wherein the drying of step (6) is carried out in a dryer, the dryer being operated at a temperature of 30 to 75 ℃ and at a pressure of 1.5 to 2.0MPaG, the dryer being packed with a desiccant selected from one of molecular sieves, silica gel or any combination thereof, the C1-C2 hydrocarbon stream from step (5) entering at the inlet of the dryer and exiting at the outlet of the dryer;

the complexing in the step (6) is carried out in a complexing reactor, the complexing reactor is positioned at the downstream of a dryer, the operating pressure of the complexing reactor is 1.5-1.8MPaG, the operating temperature is 20-40 ℃, the complexing reactor is filled with a complexing agent, the complexing agent is selected from one of Ag (I) or Cu (I) systems, a dried C1-C2 hydrocarbon material flow enters the complexing reactor from an inlet of the complexing reactor, ethylene reacts with the complexing agent and enters a liquid phase, and tail gas of the complexing reaction is sent out from the top of the complexing reactor;

wherein, the preferred Ag (I) complexing agent is selected from one or more of the following: AgNO₃、AgBF₄、AgCF₃CO₂；

Preferred cu (i) complexing agents are selected from one or more of the following: CuAlCl₄、CuCF₃CO₂And CuAl (CN) Cl₃。

The step (7) is carried out in a complex analysis tower, the operating pressure of the complex analysis tower is 0.1-0.8MPaG, the operating temperature is 50-60 ℃, the ethylene complex product from the step (6) enters from the inlet of the complex analysis tower, the analyzed polymer-grade ethylene product is obtained at the top of the tower, and the complexing agent is extracted from the bottom of the tower; and/or

The method further comprises the step (7-1): after step (7), the complexing agent is recovered.

7. The process according to any one of claims 1 to 6, wherein the step (8) is carried out in a depropanizer having a theoretical plate number of 30 to 55 and an operating pressure of 1.5 to 2.0MPaG, the feed point of the C3-plus stream from the step (2) is at 10 to 30 plates from the top, the overhead temperature is 40 to 60 ℃, the still temperature is 90 to 110 ℃, the C3 stream is withdrawn as a gas from the top of the tower, and the C4 stream is withdrawn from the bottom of the tower.

8. The process according to any one of claims 1 to 7, wherein step (9) is carried out in a propylene column having a theoretical plate number of 90 to 130, an operating pressure of 1.5 to 2.0MPaG, a C3 stream from step (8) being fed at a position of 20 to 65 plates from the top, an overhead temperature of 40 to 50 ℃, a bottom temperature of 50 to 60 ℃, a propylene product being obtained from the top and propane being obtained from the bottom; and/or

And (10) performing in a decamethylene tower, wherein the theoretical plate number of the decamethylene tower is 70-100, the operation pressure is 0.3-1.0 MPaG, the feeding position of the C4 material flow from the step (8) is at the 30-60 tower plates from top, the tower top temperature is 45-55 ℃, the tower bottom temperature is 55-65 ℃, a butene product is obtained from the tower top, and butane is obtained from the tower bottom.

9. An apparatus for separating a light hydrocarbon-containing stream, the apparatus comprising: a deethanizer, a first-stage hydration reactor, a first-stage mechanical solid-liquid separator, a hydrate analyzer, a hydrate analysis gas dryer, a complex reactor, a complex analyzer, a depropanizer, a propylene tower and a butylene tower, wherein,

the primary hydration reactor is located downstream of and independent of the deethanizer;

the first-stage mechanical solid-liquid separator is arranged in the first-stage hydration reactor;

the hydrate resolver is positioned at the downstream of the first-stage hydration reactor;

a hydrate stripper gas dryer downstream of the hydrate stripper

The complex reactor is positioned at the downstream of the hydrate gas analysis dryer;

the complex resolver is positioned at the downstream of the complex reactor;

a depropanizer is downstream of the deethanizer and upstream of the propylene column and the polybutene column;

a propylene column is located downstream of the depropanizer and is independent of the butene column;

the butene column is located downstream of the depropanizer and is independent of the propylene column.

10. The apparatus of claim 9, further comprising at least one of:

1 st to 3 rd stages of a first compressor upstream of the deethanizer;

a second compressor downstream of the deethanizer and upstream of the first-stage hydration reactor;

a hydration reaction feed cooler downstream of the second compressor and upstream of the primary hydration reactor;

a first-stage hydration reactor built-in heat exchanger built-in the first-stage hydration reactor;

a primary hydration tail gas dryer downstream of the primary hydration reactor and independent of the hydrate desorber;

an expander downstream of the primary hydration reaction tail gas dryer;

a complexing agent heat exchanger downstream of the complexing reactor and upstream of the complex desorption tower;

and/or

The apparatus further comprises:

a secondary hydration reactor having at least one inlet connected to at least one outlet of the primary hydration reactor, and

a secondary mechanical solid-liquid separator built into the secondary hydration reactor, and/or

An N-stage hydration reactor having at least one inlet connected to at least one outlet of the N-1 stage hydration reactor, and

an N-stage mechanical solid-liquid separator arranged in the N-stage hydration reactor,

wherein N is an integer of 3 or more.