阅读说明：本技术 一种二氧化碳与低碳烷烃反应制烯烃的装置、系统及工艺方法 (Device, system and process method for preparing olefin through reaction of carbon dioxide and low-carbon alkane ) 是由 王涛 江南 徐龙伢 孙海兵 林毓勇 朱向学 肖镱 陈福存 黄敏 江起培 严正芳 于 2019-10-24 设计创作，主要内容包括：本发明提供一种二氧化碳与低碳烷烃反应制烯烃的装置、系统及工艺方法,二氧化碳与低碳烷烃反应制烯烃的装置,包括进料口、进料预热炉和反应炉,进料口与进料预热炉的进口连接,进料预热炉的出口与反应炉的进口连接,反应炉的进口设有第一气体分布器；反应炉包括反应炉壳体,反应炉壳体中设置多层加热区域,加热区域由第一加热壁围成；每层加热区域内平行设置多排反应管,反应管的一端与第一气体分布器连接,另一端与反应炉的出口连接；反应管之间设置多个第一加热喷嘴。该二氧化碳与低碳烷烃反应制烯烃的装置、系统及工艺方法中反应装置温度分布均一,温度易控制,反应系统及工艺方法有效的利用了每一步产生的废热和废料,减少能源、原料浪费。(The invention provides a device, a system and a process method for preparing olefin by reacting carbon dioxide and low-carbon alkane, wherein the device for preparing olefin by reacting carbon dioxide and low-carbon alkane comprises a feed inlet, a feed preheating furnace and a reaction furnace, the feed inlet is connected with an inlet of the feed preheating furnace, an outlet of the feed preheating furnace is connected with an inlet of the reaction furnace, and an inlet of the reaction furnace is provided with a first gas distributor; the reaction furnace comprises a reaction furnace shell, wherein a plurality of layers of heating areas are arranged in the reaction furnace shell, and the heating areas are surrounded by a first heating wall; a plurality of rows of reaction tubes are arranged in each heating area in parallel, one end of each reaction tube is connected with the first gas distributor, and the other end of each reaction tube is connected with an outlet of the reaction furnace; a plurality of first heating nozzles are arranged between the reaction tubes. The device, the system and the process method for preparing the olefin by the reaction of the carbon dioxide and the low-carbon alkane have the advantages that the temperature distribution of the reaction device is uniform, the temperature is easy to control, the waste heat and the waste materials generated in each step are effectively utilized by the reaction system and the process method, and the energy and raw material waste is reduced.)

1. A device for preparing olefin by reacting carbon dioxide with low-carbon alkane is characterized in that: the device comprises a feed inlet, a feed preheating furnace and a reaction furnace, wherein the feed inlet is connected with an inlet of the feed preheating furnace, an outlet of the feed preheating furnace is connected with an inlet of the reaction furnace, and an inlet of the reaction furnace is provided with a first gas distributor; the reaction furnace comprises a reaction furnace shell, wherein a plurality of layers of heating areas are arranged in the reaction furnace shell, and the heating areas are surrounded by a first heating wall; a plurality of rows of reaction tubes are arranged in each layer of heating area in parallel, one end of each reaction tube is connected with the first gas distributor, and the other end of each reaction tube is connected with an outlet of the reaction furnace; a plurality of first heating nozzles are arranged between the reaction tubes.

2. The apparatus of claim 1, wherein the carbon dioxide is reacted with a light alkane to produce an olefin, the apparatus comprising: the waste heat recovery device comprises a first waste heat exchange device and a second waste heat exchange device, wherein the first waste heat exchange device comprises a tube side and a shell side; an outlet of the reaction furnace is connected with a tube pass inlet of the first waste heat exchange device, and a tube pass outlet of the first waste heat exchange device is connected with a discharge hole; the feeding hole is connected with a shell pass inlet of the first waste heat exchange device, and a shell pass outlet of the first waste heat exchange device is connected with an inlet of the feeding preheating furnace.

3. The apparatus of claim 1, wherein the carbon dioxide is reacted with a light alkane to produce an olefin, the apparatus comprising: the feed preheating furnace comprises a preheating furnace shell; a second heating wall is arranged on the inner wall of the preheating furnace shell; a second gas distributor is arranged at the inlet of the feeding preheating furnace; a plurality of rows of preheating pipes are arranged in the preheating furnace shell in parallel, one end of each preheating pipe is connected with the second gas distributor, and the other end of each preheating pipe is connected with an outlet of the feeding preheating furnace; and a plurality of second heating nozzles are arranged between the preheating pipes.

4. The apparatus of claim 1, wherein the carbon dioxide is reacted with a light alkane to produce an olefin, the apparatus comprising: the feeding device is characterized by also comprising a feeding mixer suitable for mixing carbon dioxide, low-carbon alkane and steam, wherein the feeding mixer is provided with a steam inlet, the inlet of the feeding mixer is connected with the outlet of the feeding preheating furnace, and the outlet of the feeding mixer is connected with the inlet of the reaction furnace.

5. A system for preparing olefin by reacting carbon dioxide with low-carbon alkane is characterized in that: the device for preparing the olefin by the reaction of the carbon dioxide and the light alkane according to any one of claims 1 to 4, further comprising a first waste heat exchange device, a second waste heat exchange device and a quenching device; the hot medium inlet of the first waste heat exchange device is connected with the outlet of the reaction furnace, the hot medium outlet of the first waste heat exchange device is connected with the hot medium inlet of the second waste heat exchange device, the cold medium inlet of the first waste heat exchange device is connected with the feed inlet, and the cold medium outlet of the first waste heat exchange device is connected with the inlet of the feed preheating furnace; and a heat medium outlet of the second waste heat exchange device is connected with a heat medium inlet of the quenching device, and a heat medium outlet of the quenching device is connected with a discharge hole.

6. The system for producing olefin hydrocarbon by the reaction of carbon dioxide and light alkane according to claim 5, wherein: the system also comprises a coarse separation unit, wherein the coarse separation unit comprises a decarburization absorption tower, an alkaline washing tower, a first cooler, a first gas-liquid separator, a regeneration tower, a benzene washing tower and a dryer; a hot medium outlet of the quenching device is connected with a gas phase inlet of the decarburization absorption tower, a gas phase outlet of the decarburization absorption tower is connected with a gas phase inlet of the alkaline washing tower, a gas phase outlet of the alkaline washing tower is connected with the first cooler, the first cooler is connected with the first gas-liquid separator, a gas phase outlet of the first gas-liquid separator is connected with a gas phase inlet of the benzene washing tower, a gas phase outlet of the benzene washing tower is connected with an inlet of the dryer, and an outlet of the dryer is connected with the discharge hole; and a liquid phase outlet of the decarburization absorption tower is connected with a liquid phase inlet of the regeneration tower, a gas phase outlet of the regeneration tower is connected with the feed inlet, and a liquid phase outlet of the regeneration tower is connected with a liquid phase inlet of the decarburization absorption tower.

7. The system for producing olefin hydrocarbon by the reaction of carbon dioxide and light alkane according to claim 6, wherein: the system also comprises a fine separation unit, wherein the fine separation unit comprises a second cooler, a second gas-liquid separator, a third cooler, a third gas-liquid separator, a first dealkylation tower, a hydrogenation device, an olefin separation tower, an olefin collection device and a second dealkylation tower; an outlet of the dryer is connected with the second cooler, the second cooler is connected with the second gas-liquid separator, a gas-phase outlet of the second gas-liquid separator is connected with the third cooler, the third cooler is connected with the third gas-liquid separator, a liquid-phase outlet of the third gas-liquid separator is connected with a liquid-phase inlet of the first dealkylation tower, a gas-phase outlet of the third gas-liquid separator is connected with a synthesis gas separation unit, a gas-phase outlet of the first dealkylation tower is connected with the synthesis gas separation unit, a liquid-phase outlet of the first dealkylation tower is connected with an inlet of the hydrogenation device, an outlet of the hydrogenation device is connected with a liquid-phase inlet of the olefin separation tower, a gas-phase outlet of the olefin separation tower is connected with the olefin collection device, and a liquid-phase outlet of the olefin separation tower is connected with a liquid-phase inlet of the second dealkylation tower, and a gas phase outlet of the second dealkylation tower is connected with the feed inlet, and a liquid phase outlet of the second dealkylation tower is connected with a liquid phase inlet of the benzene washing tower.

8. The system for producing olefin hydrocarbon by the reaction of carbon dioxide and light alkane according to claim 7, wherein: the synthesis gas separation unit comprises a pressure swing adsorption device and a hydrogen collection device, a gas phase outlet of the third gas-liquid separator and a gas phase outlet of the first dealkylation tower are connected with an inlet of the pressure swing adsorption device, the pressure swing adsorption device is connected with the hydrogen collection device, and the hydrogen collection device is connected with an inlet of the hydrogenation device.

9. A process method for preparing olefin by reacting carbon dioxide with low-carbon alkane is characterized by comprising the following steps:

s1, mixing carbon dioxide and low-carbon alkane according to a selected ratio to obtain a raw material gas, preheating the raw material gas, mixing the preheated raw material gas with water vapor in a selected ratio, and reacting at the temperature of 600-900 ℃ under the catalysis of an alkane dehydrogenation catalyst to obtain a product gas;

and S2, before preheating the raw material gas, exchanging heat between the product gas and the raw material gas, and utilizing the waste heat in the product gas.

10. The process method for preparing olefin hydrocarbon by the reaction of carbon dioxide and light alkane according to claim 9, further comprising:

s3, introducing the product gas into a decarburization absorption tower to remove carbon dioxide in the product gas;

s4, introducing the gas obtained in the step S3 into an alkaline washing tower to remove trace carbon dioxide in the gas;

s5, cooling the gas obtained in the step S4 to 15-20 ℃, and then carrying out gas-liquid separation;

s6, introducing the gas obtained by gas-liquid separation in the step S5 into a benzene washing tower to remove benzene therein;

s7, introducing the gas obtained in the step S6 into a dryer for drying to obtain a product gas which is roughly separated.

Technical Field

The invention belongs to the technical field of conversion and utilization of carbon dioxide, and particularly relates to a device, a system and a process method for preparing olefin through reaction of carbon dioxide and low-carbon alkane.

Background

With the development of modern industry, the global energy consumption is increasing dramatically, the emission of carbon dioxide is from 0.4 million tons before the industrial revolution to 60.4 million tons in 1996, and the total emission of carbon dioxide is estimated to increase to 360 million tons in 2100 years. The increasing amount of carbon dioxide with the development of industry has increased the deterioration of human living environment, and the gradual reduction of greenhouse gas emission has become a consensus of most scientists and government agencies.

Carbon dioxide is used as an important chemical raw material, and can be converted into products with higher economic value, such as white carbon black, borax, light magnesium oxide, propylene carbonate, salicylic acid, cyano-muscle and the like through chemical processing. The application can provide important industrial raw material olefin, can eliminate carbon dioxide causing greenhouse effect, and is a catalytic reaction with industrial application prospect. At present, most of the structures of the constant-temperature reaction furnaces applied to the industry are integral cylindrical reaction tubes, the heating furnace heats the outer wall of the reaction tubes, reaction gas enters the reaction tubes to perform constant-temperature reaction, but the yield is high for industrial production, the tube diameters of the reaction tubes are large, the reaction tubes are limited by heat transfer conditions, the temperatures of different positions in the reaction tubes are not uniform, and the reaction temperature is not easy to control. For the process of preparing products such as olefin by the reaction of carbon dioxide and low-carbon alkane, the process only involves the simple separation of the reaction and the products in the industry, the purity of the obtained olefin is not high, and waste heat and waste materials generated in each step of treatment are not effectively utilized, so that the waste of energy and raw materials is caused.

Disclosure of Invention

The invention solves the technical problem of providing a device, a system and a process method for preparing olefin by reacting carbon dioxide and low-carbon alkane, wherein the temperature distribution in the reaction device is uniform, the temperature is easy to control, and the reaction system and the method effectively utilize waste heat and waste materials generated in each step, thereby reducing the waste of energy and raw materials.

In order to solve the problems, the invention provides a device for preparing olefin by reacting carbon dioxide and low-carbon alkane, which comprises a feeding hole, a feeding preheating furnace and a reaction furnace, wherein the feeding hole is connected with an inlet of the feeding preheating furnace; the reaction furnace comprises a reaction furnace shell, wherein a plurality of layers of heating areas are arranged in the reaction furnace shell, and the heating areas are surrounded by a first heating wall; a plurality of rows of reaction tubes are arranged in each heating area in parallel, one end of each reaction tube is connected with the first gas distributor, and the other end of each reaction tube is connected with an outlet of the reaction furnace; a first heating nozzle is arranged between the reaction tubes.

Preferably, the system also comprises a first waste heat exchange device, wherein the first waste heat exchange device comprises a tube side and a shell side; an outlet of the reaction furnace is connected with a tube pass inlet of the first waste heat exchange device, and a tube pass outlet of the first waste heat exchange device is connected with a discharge hole; the feed inlet is connected with a shell pass inlet of the first waste heat exchange device, and a shell pass outlet of the first waste heat exchange device is connected with an inlet of the feed preheating furnace.

Preferably, the feed preheater comprises a preheater housing; a second heating wall is arranged on the inner wall of the preheating furnace shell; a second gas distributor is arranged at the inlet of the feeding preheating furnace; a plurality of rows of preheating pipes are arranged in parallel in the preheating furnace shell, one end of each preheating pipe is connected with the second gas distributor, and the other end of each preheating pipe is connected with an outlet of the feeding preheating furnace; a plurality of second heating nozzles are arranged between the preheating pipes.

Preferably, the waste heat recovery device further comprises a feeding buffer tank, the feeding port comprises a carbon dioxide feeding port and a low-carbon alkane feeding port, the carbon dioxide feeding port and the low-carbon alkane feeding port are respectively connected with an inlet of the feeding buffer tank, and an outlet of the feeding buffer tank is connected with a shell pass inlet of the first waste heat exchange device.

Preferably, the system also comprises a feeding mixer suitable for mixing carbon dioxide, low-carbon alkane and water vapor, wherein the feeding mixer is provided with a water vapor inlet, the inlet of the feeding mixer is connected with the outlet of the feeding preheating furnace, and the outlet of the feeding mixer is connected with the inlet of the reaction furnace.

The invention also aims to provide a system for preparing olefin by reacting carbon dioxide with low-carbon alkane, which comprises the device for preparing olefin by reacting carbon dioxide with low-carbon alkane, wherein the device for preparing olefin by reacting carbon dioxide with low-carbon alkane further comprises a first waste heat exchange device, a second waste heat exchange device and a quenching device; a hot medium inlet of the first waste heat exchange device is connected with an outlet of the reaction furnace, a hot medium outlet of the first waste heat exchange device is connected with a hot medium inlet of the second waste heat exchange device, a cold medium inlet of the first waste heat exchange device is connected with the feed inlet, and a cold medium outlet of the first waste heat exchange device is connected with an inlet of the feeding preheating furnace; and a heat medium outlet of the second waste heat exchange device is connected with a heat medium inlet of the quenching device, and a heat medium outlet of the quenching device is connected with a discharge hole.

Preferably, the device for preparing olefin by reacting carbon dioxide with low-carbon alkane further comprises a fourth gas-liquid separator and a filter, wherein the outlet of the heat medium of the quenching device is connected with the fourth gas-liquid separator, the gas-phase outlet of the fourth gas-liquid separator is connected with the discharge hole, and the liquid-phase outlet of the fourth gas-liquid separator is connected with the filter.

Preferably, the system also comprises a crude separation unit, wherein the crude separation unit comprises a decarburization absorption tower, an alkaline washing tower, a first cooler, a first gas-liquid separator, a regeneration tower, a benzene washing tower and a dryer; a hot medium outlet of the quenching device is connected with a gas phase inlet of the decarburization absorption tower, a gas phase outlet of the decarburization absorption tower is connected with a gas phase inlet of the alkaline washing tower, a gas phase outlet of the alkaline washing tower is connected with a first cooler, the first cooler is connected with a first gas-liquid separator, a gas phase outlet of the first gas-liquid separator is connected with a gas phase inlet of the benzene washing tower, a gas phase outlet of the benzene washing tower is connected with an inlet of a dryer, and an outlet of the dryer is connected with a discharge hole; the liquid phase outlet of the decarburization absorption tower is connected with the liquid phase inlet of the regeneration tower, the gas phase outlet of the regeneration tower is connected with the feed inlet, and the liquid phase outlet of the regeneration tower is connected with the liquid phase inlet of the decarburization absorption tower.

Preferably, the coarse separation unit further comprises a first gas compressor, the gas-phase outlet of the fourth gas-liquid separator is connected to the inlet of the first gas compressor, and the outlet of the first gas compressor is connected to the gas-phase inlet of the decarburization absorption tower.

Preferably, the coarse separation unit further comprises a first reflux tank, an air cooler and an aftercooler, the gas-phase outlet of the regeneration tower is connected with the inlet of the air cooler, the outlet of the air cooler is connected with the inlet of the aftercooler, the outlet of the aftercooler is connected with the inlet of the first reflux tank, the liquid-phase outlet of the first reflux tank is connected with the reflux inlet of the regeneration tower, and the gas-phase outlet of the first reflux tank is connected with the feed inlet.

Preferably, the rough separation unit further comprises a first heat exchange device, a heat medium inlet of the first heat exchange device is connected with the liquid phase outlet of the regeneration tower, a heat medium outlet of the first heat exchange device is connected with the liquid phase inlet of the decarburization absorption tower, a cold medium inlet of the first heat exchange device is connected with the liquid phase outlet of the decarburization absorption tower, and a cold medium outlet of the first heat exchange device is connected with the liquid phase inlet of the regeneration tower.

Preferably, the dryer includes first desicator and second desicator, and the gaseous phase export of washing the benzene tower is connected with first desicator and second desicator respectively through first pipeline and second pipeline, and the nitrogen supply device is connected with first desicator and second desicator respectively through third pipeline and fourth pipeline, all is equipped with the control valve on first pipeline, second pipeline, third pipeline, the fourth pipeline.

Preferably, the system also comprises a fine separation unit, wherein the fine separation unit comprises a second cooler, a second gas-liquid separator, a third cooler, a third gas-liquid separator, a first paraffin removal tower, a hydrogenation device, an olefin separation tower, an olefin collection device and a second paraffin removal tower; an outlet of the dryer is connected with the second cooler, the second cooler is connected with the second gas-liquid separator, a gas-phase outlet of the second gas-liquid separator is connected with the third cooler, the third cooler is connected with the third gas-liquid separator, a liquid-phase outlet of the third gas-liquid separator is connected with a liquid-phase inlet of the first dealkylation tower, a gas-phase outlet of the third gas-liquid separator is connected with the synthesis gas separation unit, a gas-phase outlet of the first dealkylation tower is connected with the synthesis gas separation unit, a liquid-phase outlet of the first dealkylation tower is connected with an inlet of the hydrogenation device, an outlet of the hydrogenation device is connected with a liquid-phase inlet of the olefin separation tower, a gas-phase outlet of the olefin separation tower is connected with the olefin collection device, a liquid-phase outlet of the olefin separation tower is connected with a liquid-phase inlet of the second dealkylation tower, a gas-phase outlet of the second dealkylation tower is connected with the feed inlet, and.

Preferably, the fine separation unit further comprises a second gas compressor, the outlet of the dryer is connected with the inlet of the second gas compressor, and the outlet of the second gas compressor is connected with the second cooler.

Preferably, the fine separation unit further comprises a second heat exchange device, a heat medium inlet of the second heat exchange device is connected with an outlet of the second gas compressor, and a heat medium outlet of the second heat exchange device is connected with the second cooler; the cold medium inlet of the second heat exchange device is connected with the liquid phase outlet of the first dealkylation tower, and the cold medium outlet of the second heat exchange device is connected with the inlet of the hydrogenation device.

Preferably, the fine separation unit further comprises a fifth cooler and a fifth gas-liquid separator, the gas phase outlet of the first paraffin removal tower is connected with the fifth cooler, the fifth cooler is connected with the fifth gas-liquid separator, the liquid phase outlet of the fifth gas-liquid separator is connected with the reflux inlet of the first paraffin removal tower, and the gas phase outlet of the fifth gas-liquid separator is connected with the synthesis gas separation unit.

Preferably, the synthesis gas separation unit comprises a pressure swing adsorption device and a hydrogen collection device, a gas phase outlet of the third gas-liquid separator and a gas phase outlet of the first dealkylation tower are connected with an inlet of the pressure swing adsorption device, the pressure swing adsorption device is connected with the hydrogen collection device, and the hydrogen collection device is connected with an inlet of the hydrogenation device.

The invention also aims to provide a process method for preparing olefin by reacting carbon dioxide with low-carbon alkane, which comprises the following steps:

s1, mixing carbon dioxide and low-carbon alkane according to a selected ratio to obtain a raw material gas, preheating the raw material gas, mixing the preheated raw material gas with water vapor in a selected ratio, and reacting at the temperature of 600-900 ℃ under the catalysis of an alkane dehydrogenation catalyst to obtain an over-product gas;

and S2, before preheating the raw material gas, exchanging heat between the product gas and the raw material gas, and utilizing the waste heat in the product gas.

Preferably, in the step S1, in the reaction of the carbon dioxide, the water and the lower alkane, the space velocity of the lower alkane is 500-2000h^-1。

Preferably, in step S1, the molar ratio of carbon dioxide to light alkane in the raw material gas is 0.8-2.0.

Preferably, in step S1, the feed gas is preheated to 100-300 ℃.

Preferably, in step S1, the pressure of the water vapor is 0.25-0.45 Mpag.

Preferably, the method further comprises, after step S2:

s2a, cooling the product gas obtained in the step S2 to 30-45 ℃, and then carrying out gas-liquid separation.

Preferably, the method further comprises the following steps:

s3, introducing the product gas into a decarburization absorption tower to remove carbon dioxide in the product gas;

s4, introducing the gas obtained in the step S3 into an alkaline washing tower to remove trace carbon dioxide in the gas;

s5, cooling the gas obtained in the step S4 to 15-20 ℃, and then carrying out gas-liquid separation;

s6, introducing the gas obtained by gas-liquid separation in the step S5 into a benzene washing tower to remove benzene therein;

s7, introducing the gas obtained in the step S6 into a dryer for drying to obtain a product gas which is roughly separated.

Preferably, the method further comprises, before step S3:

s3a, compressing the gas obtained by gas-liquid separation to 4-5Mpag, and then introducing into a decarburization absorption tower.

Preferably, the decarbonization absorption tower in the step S3 uses 20% -40% of MDEA solution as an absorbent.

Preferably, the method further comprises, after step S3:

and S3b, regenerating the MDEA rich solution in the decarburization absorption tower in a regeneration tower by using a gas stripping method, cooling the gas at the top of the regeneration tower to perform gas-liquid separation, refluxing the liquid obtained after the gas-liquid separation to the regeneration tower, and mixing the gas with the carbon dioxide in the raw material gas for feeding.

Preferably, the method further comprises the step of exchanging heat between the MDEA rich solution and the decarbonized MDEA poor solution before the step S3b.

Preferably, the method further comprises the following steps:

s8, cooling the product gas dried in the step S7, and then carrying out gas-liquid separation;

s9, introducing the liquid obtained by gas-liquid separation in the step S8 into a first dealkylation tower, and sending the gas obtained by gas-liquid separation to a synthesis gas separation unit;

s10, sending the liquid phase product at the bottom of the tower after the alkane is removed in the step S9 to a hydrogenation device, and sending the gas phase product at the top of the tower to a synthetic gas separation unit;

s11, sending a product subjected to C2+ hydrogenation treatment by a hydrogenation device to an olefin separation tower for separation, sending a gas-phase product at the top of the tower to an olefin collection device, and sending a liquid-phase product at the bottom of the tower to a second dealkylation tower;

s12, mixing and feeding the gas phase product at the top of the second dealkylation tower and the low-carbon alkane in the raw material gas, and taking the liquid phase product at the bottom of the second dealkylation tower as a washing liquid of a benzene washing tower or as a fuel of any one or more devices in the system.

Preferably, the method further comprises, before step S8:

s8a, compressing the dried gas to a pressure of 3.5-4.5MPag, and then cooling.

Preferably, the method further comprises, after step S8 a:

and S8b, exchanging heat between the compressed gas and the liquid phase product at the bottom of the first dealkanizing tower.

Preferably, step S9 further includes condensing the overhead vapor product to reflux, with the uncondensed vapor phase of the overhead vapor product being sent to a syngas separation unit.

Preferably, step S11 further comprises condensing the overhead vapor product of the olefin separation column to reflux, and sending the uncondensed vapor of the overhead vapor product to the olefin collection means.

Further preferably, the overhead gas phase product of the olefin separation column is condensed using a refrigerant at-50 to-40 ℃.

Preferably, the method further comprises, before step S12:

s12a, exchanging heat between the bottom liquid phase product of the olefin separation tower and the bottom liquid phase product of the second dealkylation tower.

Preferably, step S12 further comprises condensing the overhead vapor product of the second de-alkane tower to reflux, wherein the non-condensable vapor phase of the overhead vapor product is mixed with the lower alkane in the feed gas.

Preferably, the method further comprises the following steps:

s13, sending the gas sent to the synthesis gas separation unit to a pressure swing adsorption device for pressure swing adsorption separation to obtain hydrogen.

Preferably, in step S13, the gas is sent to a pressure swing adsorption unit at 2-3MPag, 11-15 deg.C, hydrogen is separated, and the desorbed gas is sent to the pressure swing adsorption unit at 0.015-0.03 MPag.

The lower alkane means an alkane having 4 or less carbon atoms and includes methane, ethane, propane and butane.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the device for preparing the olefin by the reaction of the carbon dioxide and the low-carbon alkane, the raw material gas in the reaction furnace is divided into a plurality of strands and is respectively sent to each reaction tube, the reaction area is divided into a plurality of reaction tubes, the heating nozzle is arranged between the adjacent reaction tubes, fuel oil or fuel gas is sprayed into the heating nozzle, and the reaction tubes are heated by combustion, so that the heat transfer of the raw material gas in the reaction area is changed from non-uniform heat transfer from outside to inside into heat transfer which is carried out simultaneously from inside to outside, the heat transfer of the raw material gas is more uniform and stable, the reaction temperature of the raw material gas is easier to control, and the temperature control; in addition, the reaction temperature in different heating areas can be controlled according to requirements, and reaction process parameters in different heating areas can be regulated and controlled, so that the product distribution can be regulated and the energy consumption can be reduced;

2. according to the device for preparing the olefin by the reaction of the carbon dioxide and the low-carbon alkane, the first waste heat exchange device is arranged, and the high-temperature process gas generated by the reaction furnace exchanges heat with the low-temperature raw material gas in the shell pass of the first waste heat exchange device in the tube pass of the first waste heat exchange device, so that the temperature of the raw material gas is preliminarily increased, the energy consumption of the feeding preheating furnace can be saved, the waste heat of the product gas is effectively utilized, and the energy waste is avoided;

3. according to the device for preparing the olefin by the reaction of the carbon dioxide and the low-carbon alkane, the feeding preheating furnace is provided with the gas distributor, the feeding preheating furnace is provided with the plurality of rows of preheating pipes, the entering mixed raw material gas is uniformly divided into a plurality of strands by the gas distributor, enters the independent preheating pipes and then enters the corresponding reaction pipes, so that on one hand, the raw material gas can be uniformly distributed in advance, and the raw material gas is guaranteed to be uniformly and equivalently distributed into different reaction pipes; on the other hand, by arranging a plurality of preheating pipes, the raw material gas heating area is divided into a plurality of preheating pipes, a heating nozzle is arranged between the adjacent preheating pipes, fuel oil or fuel gas is sprayed into the heating nozzle, and the reaction pipes are heated by combustion, so that the heat transfer of the raw material gas in the preheating area is changed from inhomogeneous heat transfer from outside to inside into heat transfer which is carried out simultaneously from inside to outside, the preheating of the raw material gas is more uniform and stable, the preheating temperature is easier to control, and the temperature control is more accurate;

4. according to the system and the process method for preparing the olefin by the reaction of the carbon dioxide and the low-carbon alkane, after the carbon dioxide, the water and the low-carbon alkane react, an olefin product and synthesis gas are finally obtained by cooling, decarbonizing, debenzolizing, drying, primary dealkylating, hydrogenation, olefin separation and secondary dealkylating, wherein waste heat in the process steps is effectively utilized, and byproducts generated in each step are also used as an absorbent, a detergent or a heat source, so that raw materials and energy are greatly saved; the separated unreacted low-carbon alkane and carbon dioxide are sent to the feeding hole for recycling, so that the consumption of raw materials is reduced, the utilization rate of energy is improved, the air pollution caused by redundant low-carbon alkane and carbon dioxide is avoided, and the recycling of the raw materials and the energy is realized;

5. the system and the process method for preparing the olefin by the reaction of the carbon dioxide and the low-carbon alkane can adjust and control the distribution of the product by adjusting the proportion of the carbon dioxide, the water and the low-carbon alkane according to the raw material components required by the downstream production process so as to meet the requirement of the downstream process on the proportion of the raw material.

Drawings

FIG. 1 is a front view of an apparatus for producing olefins by reacting carbon dioxide with light alkanes according to a first embodiment of the present invention;

FIG. 2 is a top view of an apparatus for producing olefins by reacting carbon dioxide with light alkanes according to a first embodiment of the present invention;

fig. 3 is a schematic structural diagram of a system for producing olefins by reacting carbon dioxide with light alkanes according to the second embodiment of the present invention.

Wherein: 1-a feed inlet; 2-a feed preheater; 3-a reaction furnace; 4-a first waste heat exchange device; 5-a feed buffer tank; 6-a feeding mixer; 7-a second waste heat exchange device; 8-a quenching device; 9-a fourth gas-liquid separator; 10-a filter; 11-carbon dioxide feed inlet; 12-lower alkane feed inlet; 13-a decarbonization absorption tower; 14-an alkaline washing tower; 15-a first cooler; 16-a first gas-liquid separator; 17-a regeneration column; 18-a benzene washing tower; 19-a dryer; 20-a first gas compressor; 21-preheating a furnace shell; 22-a second heating wall; 23-a preheating pipe; 24-a second heating nozzle; 25-a first reflux drum; 26-an air cooler; 27-aftercooler; 28-first heat exchange means; 29-a second cooler; 30-a second gas-liquid separator; 31-a reactor shell; 32-a first heating wall; 33-a reaction tube; 34-a first heating nozzle; 35-a third cooler; 36-a third gas-liquid separator; 37-a first dealkylation column; 38-a hydrogenation unit; a 39-olefin separation column; a 40-olefin collection device; 41-tube pass; 42-shell side; 43-a second dealkylation column; 44-a second gas compressor; 45-second heat exchange means; 46-a fifth cooler; 47-fifth gas-liquid separator; 48-pressure swing adsorption device.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.