CN113149802A

CN113149802A - Method and device for improving dehydrogenation conversion efficiency of fixed bed

Info

Publication number: CN113149802A
Application number: CN202110358359.6A
Authority: CN
Inventors: 卓润生; 谢进宁; 汪石发
Original assignee: Chengdu Runhe Shengjian Petrochemical Engineering Technology Co ltd
Current assignee: Chengdu Runhe Shengjian Petrochemical Engineering Technology Co ltd
Priority date: 2021-04-01
Filing date: 2021-04-01
Publication date: 2021-07-23
Anticipated expiration: 2041-04-01

Abstract

The invention relates to a method and a device for improving the dehydrogenation conversion efficiency of a fixed bed, in particular to an improved method and a device for producing olefin by dehydrogenation of a low-carbon alkane fixed bed, belonging to the technical field of petrochemical production. In the invention, the fixed bed reactor is provided with a high temperature resistant and thermal shock resistant nano ceramic coating protective lining; under the conditions of high temperature and micro-positive pressure, a reaction bed layer formed by a gamma-alumina catalyst loaded with VIB and IIIB elements and an alumina auxiliary agent loaded with IB and IIA elements is adopted to store heat and supply heat in an intermittent mode of alternate reaction-regeneration; heat coupling in the dehydrogenation-hydrogenation reaction process is adopted, and a heat supply pipe is arranged in a bed layer of gas, molten salt and caustic alkali high-temperature heat medium, so that heat balance in the conversion process and temperature balance of a reaction bed layer are realized; the severity, temperature difference, thermal cracking and coking side reactions, investment and operation cost in the reaction process are reduced; the conversion activity, selectivity, one-way reaction time, operation stability and maintainability are improved.

Description

Method and device for improving dehydrogenation conversion efficiency of fixed bed

Technical Field

The invention relates to a dehydrogenation conversion method and a dehydrogenation conversion device for a low-carbon alkane fixed bed, in particular to an improved process method and a reaction device for producing olefin by dehydrogenation of the low-carbon alkane fixed bed, belonging to the technical field of petrochemical production.

Background

The low-carbon olefin is a basic organic raw material with larger demand and wide application in the petrochemical industry, for example, propylene is widely used for producing chemical products such as polypropylene, propylene oxide, acrylic acid, acrylonitrile, isopropyl benzene and the like. With the development requirement of clean fuels, the derived products can be used for producing high-octane gasoline components, and the butylene is developed and utilized, and meanwhile, the butylene can also be used for producing chemical products such as polybutene, sec-butyl alcohol and the like.

At present, the refining capacity of China is relatively surplus, but the demand of low-carbon olefin resources is still increased. Therefore, measures such as conversion of oil refining into chemical industry and integration of refining are proposed, and production of low-carbon olefin serving as a basic organic raw material in petrochemical industry and an intermediate product link in conversion of oil refining into chemical industry gradually draws attention.

Propylene, an important member of the light olefins, is supplied mainly from byproducts of a catalytic cracking process for producing ethylene and heavy oil by naphtha cracking. Since the original propylene source cannot fully satisfy the actual demand due to the increase of the demand of propylene, the technology for producing propylene by dehydrogenation of propane, which is an important production process for expanding the propylene source, has been drawing attention and rapidly developed.

The demand of butene, another important member of low-carbon olefin, is also rapidly increasing, and the process route for preparing isobutene by adopting isobutane dehydrogenation is also an important preparation method, and the process route is also emphasized and rapidly developed in recent years.

China has abundant light hydrocarbon resources such as liquefied petroleum gas, condensate liquid and the like, contains a large amount of low-carbon alkanes such as propane, butane and the like, and has good basic conditions for developing a technology for producing olefins by dehydrogenation of the low-carbon alkanes.

Various low-carbon alkane dehydrogenation processes have been developed by domestic and foreign research and development institutions, and very representative processes include a Catofin process of ABB Lummus company, an Oleflex process of UOP company and the like. The technical information of the prior art can be summarized by referring to the Xiujin Tang for producing C by catalytic dehydrogenation of alkane₃～C₄Olefin Process (one to four) [ (J)]Natural gas industry, 1994, 14(2) - (4), (6).

The Catofin Process from Lummus is one of the widely used low carbon alkane Dehydrogenation processes, as described in Graig R G, Delaney T J, Duffalo J M. "Catalytic Dehydrogenation Performance of Catofin Process". Petrochemical review. Houston. Dewitt.1990, and Feldman R J, Lee E. "Commercial Performance of the feedstock Process" 1992, NPRA. and is a very typical HOUDRY circulating fixed bed Process technology.

The core unit of the Catofin process is several fixed bed reactors, similar to the traditional HOUDRY cyclic fixed bed process route disclosed in the earlier document USP 2419997. The temperature in the reaction process is about 600 ℃, under the conditions of high temperature, negative pressure or low pressure, propane absorbs a large amount of heat through a bed catalyst to complete dehydrogenation reaction to prepare propylene, and simultaneously, the catalyst needs to be regenerated every more than ten minutes along with some side reactions such as thermal cracking and the like, and the temperature of a catalyst bed is increased at intervals.

Cheap and efficient Cr is adopted in the Catofin process₂O₃/A1₂O₃Chromium-based catalysts as described in USP6486370, USP 6756515. The non-noble metal chromium catalyst has high selectivity, high alkane conversion rate and less circulation amount. In recent years, along with the enhancement of environmental protection, nontoxic Mo₂O₃/A1₂O₃Molybdenum-based catalysts have also begun to gain attention and use, but further improvements in conversion activity and selectivity have been desired.

The Catofin process has the advantages of high alkane conversion rate, good product selectivity, strong raw material adaptability, high online rate of devices and the like; because of adopting the circulation multi-reactor system, more products can be obtained by less raw materials, more reactors can be easily added into the device, the capacity is easily expanded, and the scale economy is improved.

However, the Catofin process has the obvious disadvantage that the reaction device is operated intermittently, and the product recovery part needs to be operated under pressure, so that the energy consumption of the whole process is large. Since the dehydrogenation reaction of hydrocarbons is a strongly endothermic reaction, sufficient heat utilization, heat balance and heat supplement are very important factors for improving the conversion efficiency and reducing the energy consumption.

A more common method of heat balance and reuse is to fully utilize the heat generated during catalyst regeneration, such as CN105120997A, by performing an exothermic catalyst regeneration reaction, transferring heat to an integrated fluidized bed reactor, and performing an endothermic reaction by at least a portion of the transferred heat to dehydrogenate alkanes.

CN103003221A uses a reaction in which inert heat exchange particles and catalyst particles are mixed, the heat exchange particles are heated in a heating zone and returned to the reaction zone to provide the required heat of reaction, and the catalyst is regenerated under a non-oxidizing atmosphere, but it is difficult to use under the condition of a fixed bed reaction apparatus.

In order to improve the thermal efficiency of the discontinuous regenerative-reaction mode in the conventional fixed bed reactor, some recent technical reports disclose that a heat generating material is used as an auxiliary in a catalyst reaction bed layer. For example, USP0259265a1, CN106029612A, USP7973207B2, USP7622623B, USP5108973, etc. all disclose methods of using exothermic materials in the endothermic dehydrogenation of alkanes, using exothermic materials having metallic elements such as copper, manganese, etc. supported on alumina in addition to catalyst and inert alpha-alumina, including reacting hydrocarbons with a multi-component catalyst bed and regenerating the catalyst bed using air, wherein the air and hydrocarbons used in the regeneration step are low air/hydrocarbon ratio and near atmospheric pressure, which improves efficiency.

The utilization of the heat in the exothermic reaction is undoubtedly a good way of heat reuse, for example, CN101061084A completely hydrogenates all unsaturated hydrocarbons contained in the whole hydrocarbon stream before introducing them into the dehydrogenation reactor during the catalytic dehydrogenation of light alkanes to produce olefins, so that the energy released in the exothermic hydrogenation is substantially completely retained in the hydrocarbon stream, thus reducing the energy consumption for preheating the reactant stream to the reaction temperature and significantly reducing the formation of coke in the dehydrogenation reactor.

CN103772093A is that alcohol dehydrogenation and low carbon olefin hydrogenation are arranged in parallel in a tubular reactor, the heat released by olefin hydrogenation is supplied to the heat absorption of alcohol dehydrogenation, the heat absorption and heat release of the two reactions are well matched to reach balance, the heating and cooling processes are omitted, the process flow is simplified, the device investment and operation cost are saved, the coke formation is reduced, the service life of the catalyst is prolonged, the heat exchange technology of the two simultaneous reaction processes is well utilized, the efficiency is improved, and the process and the device are simplified.

Furthermore, CN106365936A discloses a tubular membrane module reactor with selective hydrogen permeability, wherein alcohol liquid-phase dehydrogenation reaction and hydrogen gas-phase oxidation reaction are respectively performed on two sides of the membrane, i.e. the dehydrogenation reaction product hydrogen permeates out of the reaction system in time, which not only improves the reaction rate, but also improves the equilibrium conversion rate of the reaction, and the permeation side can provide heat for dehydrogenation by controlling the rate of the oxidation reaction, thereby further improving the heat exchange efficiency and achieving the purpose of in-situ heat supply.

CN101165031A discloses a process for the dehydrogenation of alkanes by a zoned reaction, wherein a portion of the alkane is exothermically converted to an alkene by oxidative dehydrogenation in an exothermic reaction zone in the presence of oxygen and a catalyst, and wherein the product of the exothermic reaction zone is then passed to an endothermic reaction zone of a reactor, wherein at least a portion of the remaining unconverted alkane is endothermically dehydrogenated in the presence of carbon dioxide and other catalyst. Similarly, CN106986736A also used a similar method of zoned heat coupling during the oxidative coupling of methane.

However, the method of heat coupling by zone reaction fundamentally reduces the efficiency of heat utilization, and thus, the prior art center also discloses in-situ heat recycling by time zonesThe patent application, for example, CN107074683A discloses a process for catalytic dehydrogenation of alkanes to alkenes using Cr₂O₃As a catalyst, during the reduction process, CO is introduced to serve as a reducing gas to reduce the catalyst, and the CO reduces the CuO component in the catalyst to form Cu and CO₂And releasing heat to reduce CO generated₂Or with H produced by dehydrogenation₂React to form CO and H₂And O. The in situ time-phased heat reuse is certainly similar to intermittent heat storage in nature.

The use of the difference in the thermal effects of the two reactions, in situ and in real time, is clearly the most desirable way to couple heat, as CN107223119A discloses the reaction of paraffins, especially light paraffins, such as C₃～C₈A process for converting paraffins to higher boiling range liquid paraffins includes the endothermic dehydrogenation of light paraffins in combination with an exothermic reaction such as olefin oligomerization to provide heat for the endothermic conversion reaction.

In addition, in addition to the report that the load of the heating furnace is reduced by the preposed electric heating tube disclosed in the prior art, the preposed electric heating tube is arranged in the catalyst bed layer and is also mentioned in the prior art, and CN104072325A discloses a method for improving the dehydrogenation reaction performance of the low-carbon alkane.

In other industries and fields, the application of high-temperature molten salt heat media is reported, for example, CN107177348A discloses a high-heat-conductivity metal-carbonic acid molten salt material, and the high-heat-conductivity metal-carbonic acid molten salt material is considered to have good application prospects in the fields of renewable energy sources, high-temperature industrial waste heat recovery and the like; CN107034386A discloses a molten salt corrosion resistant high-temperature composite material and a molten salt reactor core structural member, and has good application prospect; CN103911126A, CN101289612A and CN101508888A all disclose molten carbonate heat transfer and storage media, which can meet the working temperature range required by a solar thermochemical reactor, and have good thermal stability and large phase change latent heat. However, similar prior art reports are not found in the technical field of alkane dehydrogenation process and device.

Although various improved processes and catalysts are reported continuously in the prior art, inevitable factors such as pressure drop difference caused by catalyst loading and material bias flow caused by process piping exist, when low-carbon alkane is subjected to dehydrogenation reaction on a catalyst surface active site, the temperature distribution and temperature drop of a catalyst bed layer cannot be uniform along with a strong endothermic process, the service life of the catalyst and the product yield of low-carbon olefin are seriously affected, the requirements on the aspects of process severity, stability, operability, operation period and the like cannot be met, and further continuous improvement and improvement are needed.

Disclosure of Invention

In the catalytic dehydrogenation reaction process, the process of converting low-carbon alkanes such as propane, butane and the like into olefins is an endothermic reaction with an increased molecular number, and high temperature and low pressure are favorable for the reaction from the chemical thermodynamic viewpoint. In the dehydrogenation process of the light alkane, the catalyst needs to be frequently regenerated, and simultaneously, the required heat is provided.

Therefore, the fixed bed low carbon alkane dehydrogenation process adopts a circulation mode, in a full circulation period, hydrocarbon material dehydrogenation is carried out, the reactor is cleaned by steam, purged by air, preheated by catalyst, burnt off a small amount of coke deposited on the catalyst, and then vacuumized and restored, and another circulation is started.

However, the too high and uneven reaction and regeneration temperature of the reactor bed and the too strong cracking reaction of the reaction system can cause the selectivity of the dehydrogenation reaction products to be reduced, and simultaneously, the carbon deposition speed of the catalyst bed can be accelerated, so that the conversion performance of the whole reaction system is reduced and even inactivated.

Therefore, in the fixed bed low carbon alkane dehydrogenation conversion process, the catalyst bed layer can realize heat balance during reaction and regeneration as much as possible, the temperature of the bed layer is kept uniform, and the reaction severity is reduced as much as possible, which are all key factors for keeping high efficiency and stability in the reaction process of preparing low carbon alkene by alkane dehydrogenation.

The invention aims to overcome the defects in the prior art, improve the temperature distribution of a catalyst bed layer of a fixed bed reactor, reduce the reaction and regeneration severity, inhibit the occurrence of side reactions and improve the product yield, and provides an improved fixed bed low-carbon alkane dehydrogenation process method which comprises a conversion method comprising reaction and heat coupling, an improved conversion catalyst and an improved auxiliary agent.

The invention aims to solve another technical problem of providing a low-carbon alkane dehydrogenation device which can meet the requirements of the reaction and the regeneration in the dehydrogenation reaction process, and comprises an improved dehydrogenation conversion reactor.

The invention solves the problems and provides a dehydrogenation and conversion reaction system of low-carbon alkane, which comprises a reactor, a process device, reaction materials, a catalyst, an auxiliary agent and a bed heat supply pipe.

Accordingly, in view of the above circumstances, the present invention provides a fixed bed dehydrogenation process for lower alkanes with improved conversion efficiency, specifically comprising:

the invention relates to a dehydrogenation conversion method of a low-carbon alkane fixed bed, which is characterized in that in a high-temperature and micro-positive pressure fixed bed reactor, a reaction bed layer formed by a gamma-alumina catalyst loaded with VIB and IIIB elements and an alumina auxiliary agent loaded with IB and IIA elements is adopted to store heat and supply heat in an intermittent mode of alternate reaction-regeneration; the heat coupling in the dehydrogenation-hydrogenation reaction process and the heating pipe in the high-temperature heat medium bed layer of the external heat source are used for realizing the heat balance in the conversion process and the temperature balance of the reaction bed layer; c is to be₃～C₅The low-carbon alkane is dehydrogenated and converted into low-carbon olefin.

The invention relates to a dehydrogenation conversion method of a low-carbon alkane fixed bed, which comprises the following specific steps:

(1)C₃～C₅low carbon alkane raw material gas, CO and/or CO₂Preheating gas at 200-500 ℃;

(2) the reaction solution enters a reactor to be contacted with a VIB and IIIB group element gamma-alumina dehydrogenation catalyst, an IB and IIA group element loaded alumina auxiliary agent and a heat storage/support body inert alumina ball, and the reaction temperature is 550-700 ℃, the reaction pressure is 0.1-0.15 MPa, the reaction time is 10-30 minutes, and the mass space velocity (WHSV) is 0.1-5 hours^-1Dehydrogenation conversion under the reaction conditions of (1);

(3) the low-carbon olefin and the by-product generated by the reaction conversion enter a subsequent washing and separating device to obtain the low-carbon olefin, hydrogen-rich gas and fuel gas, and the unconverted low-carbon alkane returns to the reactor;

(4) the conversion process comprises a periodic regeneration process of a catalyst bed layer, after steam purging, hot air with the temperature of 560-730 ℃ and the pressure of 0.01-1 MPa is introduced for regeneration and heating of the bed layer, evacuation and reduction are carried out, and the cycle time of each period is 15-70 minutes; the reduction process comprises treating the catalyst bed with a hydrogen-rich gas, and the reduction treatment is carried out with the separated hydrogen-rich gas, which can also be conveniently provided by commercially available hydrogen.

The invention discloses a dehydrogenation conversion method of a low-carbon alkane fixed bed, which is characterized in that the preferable reaction process is carried out at the temperature of 560-620 ℃ and the micro positive pressure range of 0.103-0.105 MPa, and raw materials and CO and/or CO are subjected to dehydrogenation conversion₂The preheating temperature of the gas is 300-450 ℃, the reaction time is 18-25 minutes, and the mass space velocity (WHSV) is 0.3-2 hours^-1The dehydrogenation reaction is carried out under the conditions of (1). The preferable regeneration condition is that hot air with the temperature of 600-700 ℃ and the pressure of 0.05-0.5 MPa is introduced during regeneration, and the cycle time of each period is 30-40 minutes.

The invention relates to a dehydrogenation conversion method of a low-carbon alkane fixed bed, which is characterized in that CO and/or CO accounting for 1-20 m% of the total amount of raw materials is used in a heat coupling process in a reaction process₂The gas and hydrogen generated in the reaction process are subjected to exothermic reaction, and the preferable proportion is 1.5-5 m% of CO and/or CO₂A gas; by which the dehydrogenation product H is reacted with₂To facilitate the process; the feed gas for the thermal coupling can be passed through the process itselfThe flue gas is supplied by separating and returning to the reactor, or can be conveniently supplied by commercial CO and CO₂And (4) obtaining.

The invention relates to a dehydrogenation conversion method of a low-carbon alkane fixed bed, which is characterized in that a catalyst contains 15-30 m% of Cr₂O₃0.1-5 m% of rare earth element and 65-80 m% of gamma-Al₂O₃(ii) a The chromium-based catalyst has good conversion activity and product selectivity.

The invention discloses a dehydrogenation conversion method of a low-carbon alkane fixed bed, which is characterized by also providing a chromium-free catalyst containing 15-30 m% of Mo₂O₃0.1-5 m% of rare earth element and 65-80 m% of gamma-Al₂O₃(ii) a The molybdenum-based catalyst is inferior to the chromium-based catalyst in dehydrogenation conversion performance, but is superior to the chromium-based catalyst in terms of environmental protection and safety because of its non-toxicity.

The invention relates to a dehydrogenation conversion method of a low-carbon alkane fixed bed, which is characterized in that an auxiliary agent contains 5-30 m% of CuO, 10-35 m% of CaO and 50-80 m% of Al₂O₃The catalyst bed is placed in the bed layer in an amount accounting for 1-25 v% of the total volume of the catalyst bed, and is selectively arranged in a bed layer area with insufficient heat.

The invention provides a dehydrogenation process method of low-carbon alkane, which is characterized in that in a single reaction-regeneration cycle period, the time ratio of dehydrogenation reaction, steam purging, catalyst bed layer heating and vacuumizing/reduction reaction is (20-22.5): 3:9: 3.

In the dehydrogenation process method of the low-carbon alkane provided by the invention, the low-carbon alkane refers to C₂～C₅Small molecule alkanes, also known as paraffins; preferably means C₃～C₄Low carbon number alkanes of (a); more preferred are one or more of propane, isobutane and n-butane, which are commercially available.

In the dehydrogenation process method of the low-carbon alkane, the dehydrogenation catalyst, the auxiliary agent and the inert oxidation used as a heat accumulatorThe filling volume ratio of the aluminum balls to the inert alumina porcelain balls used as the support is 1 (0.1-0.2): (0.4-0.7): 0.4-0.6); the preferred loading volume ratio is 1 (0.15-0.18): (0.5-0.6): 0.45-0.55). Inert alumina ball as heat accumulator and inert alumina ceramic ball as support with Al₂O₃More than or equal to 99.5m percent, the heat capacity is 0.2-0.35cal/g ℃, the preferred heat capacity is 0.25-0.32 cal/g ℃, the highest using temperature is more than or equal to 1400 ℃, and the heat-insulating material can be conveniently obtained by commercial purchase.

In the dehydrogenation process method of the light alkane provided by the invention, the filling and arrangement of the catalyst and the auxiliary agent, the steam purging, the evacuation and the reduction process are conventional operations in the field and are well known and routinely used by a person skilled in the art.

The invention relates to a dehydrogenation conversion method and a device of a low-carbon alkane fixed bed, which are characterized in that a high-temperature heat medium of a heating pipe in a high-temperature heat medium bed layer of an external heat source is selected from gas, molten salt and caustic alkali; preferably a molten salt; the difficulty in molten salt selection is that it must be able to meet and match the heat balance requirements of the reaction process, as well as be able to adapt to the requirements of the reaction apparatus.

The invention also provides a low-carbon alkane fixed bed dehydrogenation conversion device which is characterized by comprising a raw material preheating furnace and an air preheating/heating furnace, wherein the raw material preheating furnace and the air preheating/heating furnace are connected to a reactor through pipelines; alternately keeping 3-6 parallel fixed bed reactors in reaction, regeneration and purging states; a series of separation devices connected to the reactor outlet for washing and separation of the reaction products; the compression and gasification equipment connected in the pipeline is respectively used for compressing, circulating and gasifying the hydrocarbon and the air; heat exchange and condensation equipment and a waste heat boiler in the process pipeline are respectively used for heat exchange, condensation and heat recovery of raw materials, reaction coupling gas, products and exhaust gas which enter and exit the reactor.

The invention provides a dehydrogenation conversion method and a dehydrogenation conversion device for a low-carbon alkane fixed bed, which are characterized in that a fixed bed reactor comprises a shell and a catalyst reaction bed layer arranged in the shell; the shell is of a hollow metal structure and is connected with the end cover and the steel cylinder body through a flange; and is provided with an outer insulating layer and a high-temperature-resistant and thermal shock-resistant nano ceramic coating protective lining; a catalyst bed layer formed by a catalyst and an auxiliary agent is filled above the supporting space in the cylinder body; a multi-point thermocouple and a high-temperature heat medium heat supply pipe are arranged in the bed layer, and the heat supply pipe is connected to a heating furnace outside the reactor through an inlet pipeline and an outlet pipeline after being gathered in an end cover area; the material inlet is connected with the reactor from the upper part, and the material outlet is connected with the reactor from the lower part.

The invention also provides a low-carbon alkane dehydrogenation reaction system which is characterized by comprising heating equipment, a reactor, separation equipment, reaction raw materials, gas for reaction coupling, a catalyst, an auxiliary agent, heat accumulator inert alumina balls and inert alumina ceramic balls for supporting; in the dehydrogenation reaction stage, the low-carbon alkane and the reaction coupling gas enter the reactor from the top of the reactor after being preheated, contact with a dehydrogenation catalyst, a heat supply auxiliary agent, heat accumulator inert alumina balls and support inert alumina ceramic balls, perform dehydrogenation conversion reaction and heat coupling reaction under the reaction conditions of high temperature and slight positive pressure, and realize heat balance in the conversion process and temperature balance of a reaction bed layer by a high-temperature heat medium heat supply pipe; discharging the converted product from the bottom of the reactor to a connected back-stage washing and separating device to separate low-carbon olefin, hydrogen-rich gas and fuel gas; returning unconverted low-carbon alkane to the reactor; in the regeneration stage, the feeding is stopped and steam purging is carried out, heated hot air enters the reactor from the top of the reactor to regenerate the catalyst bed, and the temperature of the bed is increased to store heat.

It is well known to those skilled in the art that the processes, apparatuses and reaction systems comprising catalysts and promoters constitute the subject matter, system and features of the present invention and are the most important factors affecting the catalytic conversion of hydrocarbons, unlike the prior art, and because of the uncertainty of the mutual influence, it is difficult to obtain direct teaching from the prior art and to obtain the desired results through simple permutation and combination experiments on the basis of the prior art, and it is necessary to systematically study and explore them to obtain valuable results.

The alkane dehydrogenation reaction process method, the alkane dehydrogenation reaction device and the alkane dehydrogenation reaction system have higher heat and reaction coupling conversion performance, and can ensure that the temperature distribution of the reaction process and the catalyst bed layer is more balanced and uniform, so that the severe temperature difference of the bed layer caused by factors such as bed pressure drop difference, material bias flow, strong heat absorption and the like is relieved, local hot spots are reduced and eliminated, and the generation of side reactions and coking is inhibited.

The invention reduces the inlet temperature of the regeneration air or the flow rate of the regeneration air, thereby reducing the energy consumption of the device; the inlet temperature of the reactor is reduced, side reactions of thermal cracking which may occur in the pipeline from the outlet of the heating furnace to the bed layer of the reactor are reduced, the heat dissipation loss is reduced, the material consumption is reduced, and the investment requirement on equipment is reduced.

The invention reduces the highest temperature of the bed layer and the probability of catalyst deactivation at the top of the bed layer on the premise of keeping the total heat unchanged, reduces the temperature drop in a reaction period, and can improve the selectivity under the condition of ensuring the conversion rate to be unchanged, thereby synergistically improving the stability of the alkane dehydrogenation reaction process and the product yield of the low-carbon olefin, prolonging the service life of the catalyst and being beneficial to the long-period operation and operation of the dehydrogenation process. In addition, the present invention also improves investment, operating costs and maintainability through the above improved method and apparatus.

Drawings

FIG. 1 is a flow chart of a process of dehydrogenation reaction of light alkane.

In fig. 1: 1-a reactor; 2-raw material heating furnace; 3-a washing tower; 4-a flash column; 5-a reaction gas compressor; 6, recovering waste heat; 7-light alkane feedstock; 8-recycle low carbon alkane; 9-CO/CO₂Gas; 10-product gas; 11-fuel gas; 12-water vapor; 13. reducing gas; 14-regeneration gas; 15-softened water; 16-oily sewage.

FIG. 2 is a schematic structural diagram of a fixed bed reactor for dehydrogenation of low-carbon alkane.

In fig. 2: 17-catalyst bed layer; 18-a heating pipe; 19-high temperature hot air inlet; 20-multipoint thermocouples; 21-steam-CO/CO₂A gas-reducing gas inlet; 22-low carbon alkane feed inlet; 23-a hydrocarbon product outlet; 24-a waste heat air outlet;25-evacuation-emergency exit; 26-a reactor steel shell; 27-reactor end cap; 28-high temperature heat medium inlet/outlet; 29-a connecting flange; 30-high temperature resistant reactor lining; 31-a heat-insulating coating layer outside the reactor; 32-support space inside the reactor.

Detailed Description

The following description will be made with reference to the accompanying drawings, in which the embodiments of a low-carbon alkane fixed bed dehydrogenation conversion method, a low-carbon alkane fixed bed dehydrogenation conversion device, and a low-carbon alkane dehydrogenation reaction system including a reaction device, reaction materials, a catalyst, and an auxiliary agent are provided.

FIG. 1 is a schematic flow diagram of a fixed bed dehydrogenation conversion method for low-carbon alkane provided by the invention, and is also a schematic diagram of a fixed bed dehydrogenation conversion device and a reaction system for low-carbon alkane.

FIG. 2 is a schematic structural diagram of a fixed bed dehydrogenation conversion reactor for low-carbon alkane.

As shown in the attached figure 1, in a low-carbon alkane fixed bed dehydrogenation conversion device, the device comprises: the raw material preheating furnace and the air preheating and heating furnace are connected to the reactor by a process pipeline; alternately keeping 3-6 parallel fixed bed reactors in reaction, regeneration and purging states; a series of separation devices connected to the reactor outlet for washing and separation of the products; the compression and gasification equipment connected in the pipeline is respectively used for compressing, circulating and gasifying air, products, process gas and fuel gas; in addition, the system also comprises heat exchange and condensation equipment and a waste heat boiler which are connected in the pipeline and are respectively used for heat exchange, condensation and heat recovery of the raw materials, the products and the circulating materials.

In the alkane dehydrogenation process, the reaction conversion process comprises the following steps: 7 parts of low-carbon alkane raw material gas and 1-20 m% of CO/CO in the low-carbon alkane raw material₂Gas 9 is heated to 200-500 ℃ through a process pipeline system, a heat exchange and preheating device 4 and a heating furnace 2, and then enters the reactor 1 in a reaction state from the

top parts

21 and 22 of the reactor; unconverted low-carbon alkane 8 also enters the reactor 1 together with the fresh raw material 7; with chromium alumina dehydrogenation catalyst, auxiliaries in a fixed bed reactor 1, and as heat storageThe inert alumina ball is contacted with the inert alumina porcelain ball used as a support.

At the reaction temperature of 500-700 ℃, the reaction pressure of 0.1-0.15 MPa and the mass space velocity (WHSV) of 0.1-5 hours^-1The reaction is carried out for 15-30 minutes; the multipoint thermocouples 20 are used for detecting the temperature distribution condition of the reaction bed, and the heat supply pipe 18 participates in heat supply and heat balance in the reaction process and balance control of local bed temperature by controlling the flow of a flow-through external heat source; in the single circulation period, the time ratio of dehydrogenation reaction, steam purging, catalyst bed layer heating and vacuumizing/reduction reaction is (20-22.5): 3:9: 3.

The low-carbon olefin and the byproduct 10 generated by the reaction conversion are discharged from the lower part 23 of the fixed bed reactor, steam is generated by a heat exchanger 6, enters a subsequent washing 3 and a compression 5, enters a subsequent separation device to obtain the low-carbon olefin, hydrogen-rich gas and byproduct fuel gas 11 serving as part of the fuel gas, and the unconverted low-carbon alkane 8 and the fresh raw material 7 are subjected to sufficient heat exchange and heating and then circularly returned to the reactor 1 for secondary conversion.

The conversion process comprises a periodic regeneration process of a catalyst bed layer (17 in the attached figure 2), and 3-6 fixed bed reactors are alternately in different states (reaction, purging and regeneration); and (3) stopping feeding the catalyst bed layer 17 after the reaction conversion is finished, blowing hot air 14 with the temperature of 560-730 ℃ and the pressure of 0.01-1 MPa into the catalyst bed layer for regeneration after steam blowing by 12, and discharging waste gas out of the reactor 1 or entering a subsequent separation device through 24.

After the regeneration process of the catalyst bed layer 17 is finished, after the processes of evacuation and reduction, the dehydrogenation and coupling reaction processes are repeated again; the cycle time of each period is 30-40 minutes; the reduction process comprises the step of reducing a catalyst bed layer 17 in a regeneration state by using hydrogen-rich gas 13 obtained by separation equipment, wherein the catalyst bed layer is filled by the dehydrogenation catalyst and the auxiliary agent in a volume ratio of 100: 1-25 and is supported by a heat accumulator inert alumina ball and/or an inner member.

In the method and the reaction system for dehydrogenation and conversion of the low-carbon alkane fixed bed provided by the invention, the catalyst is usedThe preparation steps of the gamma-alumina catalyst loaded with VIB and IIIB elements in the catalyst bed layer can be partially prepared by referring to the steps and the content in the patent ZL200910210905.0 issued by the inventor; in the present invention, the preferred chromium/gamma-alumina dehydrogenation catalyst composition contains 15 m% to 30 m% of Cr₂O₃0.1-5 m% of rare earth element and 65-80 m% of gamma-Al₂O₃。

Under the condition of increasing environmental protection requirements, a non-chromium dehydrogenation catalyst can be selected, and a preferable molybdenum/gamma-alumina dehydrogenation catalyst composition contains 15 m-30 m% of Mo₂O₃0.1-5 m% of rare earth element and 65-80 m% of gamma-Al₂O₃。

In the above-mentioned fixed bed dehydrogenation conversion method and reaction system for light alkanes provided by the present invention, the alumina auxiliary agent loaded with group IB and group IIA elements in the catalyst bed can be prepared by referring to the contents of documents 201711457256.5 and 201810119334.9 of the inventor's earlier application. In the invention, the auxiliary agent contains 5-30 m% of CuO, 10-35 m% of CaO and 50-80 m% of Al₂O₃The catalyst is placed in the catalyst bed layer in an amount accounting for 1-25 v% of the total volume of the catalyst bed layer; and, according to the obtained operation data, the reaction bed layer is preferably arranged in a local area with insufficient heat and low conversion temperature in the conversion process.

In the dehydrogenation conversion method, the dehydrogenation conversion device and the reaction system of the low-carbon alkane fixed bed, inert alumina balls used as a heat accumulator and inert alumina ceramic balls used as a support in a catalyst bed layer consist of Al₂O₃Not less than 99.5 m%, heat capacity of 0.2-0.35cal/g deg.C, and maximum service temperature of over 1400 deg.C, and can be used as effective heat storage body and stable service in harsh service environment.

The invention provides a dehydrogenation conversion method of a low-carbon alkane fixed bed, which is characterized in that a high-temperature heat medium of a heating pipe in a high-temperature heat medium bed layer of an external heat source is selected from gas, molten salt and caustic alkali.

The following examples are provided to further illustrate the low carbon alkane dehydrogenation process, apparatus and reaction system of the present invention and the effects thereof, and are intended to be illustrative of the present invention and are not to be construed as limiting the invention to other broad aspects set forth in the claims.

In an embodiment, catalyst bed temperature changes are detected by a multi-point thermocouple in the bed; analysis of the composition of the starting materials and the reaction products was carried out using an Agilent 6890N gas chromatograph.

Other analytical tests can be found in the relevant analytical methods in (national Standard of methods for testing Petroleum and Petroleum products, published in 1989 by Chinese standards Press) and in (analytical methods for petrochemical engineering (RIPP test), published in 1990 by scientific Press).

Example 1

Example 1a chromium/gamma-alumina dehydrogenation conversion catalyst and a copper-calcium alumina promoter as required by the present invention were prepared. The preparation of Cr containing 23 m% of Cr is carried out by referring to the procedures in the patent granted by the inventor ZL200910210905.0₂O₃1 m% of La₂O₃And>75 m% of gamma-Al₂O₃A chromium/alumina dehydrogenation catalyst.

Referring to the steps in the applicants' 201711457256.5 and 201810119334.9 application documents, a catalyst containing 15 m% of CuO, 17 m% of CaO and>67 m% of Al₂O₃The auxiliary (2) of (1).

Example 2

EXAMPLE 2 preparation of the molybdenum/gamma-alumina dehydrogenation catalyst required by the present invention, a catalyst containing 23 m% of Mo was prepared by following a procedure similar to that of example 1₂O₃1 m% of La₂O₃And>75 m% of gamma-Al₂O₃A catalyst.

Example 3

Example 3 illustrates the application effect of the method, the device and the reaction system for converting low-carbon alkane into propane by fixed bed dehydrogenation in the process of dehydrogenation of chromium-based catalyst propane.

The test flow of the dehydrogenation reaction of the light alkane is shown in the attached figures 1 and 2, and the dehydrogenation catalyst and the auxiliary agent prepared in the example 1 are arranged in bed layers of 4 industrial fixed bed reactors; lithium carbonate molten salt is selected as a high-temperature heat medium in the heat supply pipe in the bed layer.

According to the process described in the present invention, 4 fixed-bed reactors were put into operation in succession at 3 minute intervals, with 1 reactor being in the dehydrogenation process at any one time and the other 3 reactors being in the regeneration and reheating, steam purging or evacuation/reduction processes, respectively. The single cycle period is about 35 to 40 minutes, wherein the dehydrogenation reaction is carried out for 20 to 22.5 minutes, the steam purging is carried out for about 3 minutes, the catalyst bed is regenerated and heated again for about 9 minutes, and the time for about 3 minutes is used for vacuumizing and reduction reaction.

Table 1, composition of the feedstock for propane dehydrogenation reaction:

item	Composition/m%
		Propane	≥95
Other Components	≤5

TABLE 2 propane dehydrogenation and regeneration procedure

Item	Data of
		Reaction feed temperature/. degree.C	591
Reactor pressure/MPa (absolute pressure)	0.105
		Feed space velocity/(WHSV) hr^-1	0.5
The CO accounts for v/v percent of the volume proportion of the raw material gas	5
		Single pass reaction time/min	20～22.5
Regeneration air feed temperature/° c	670

Table 1 shows the properties of a technical grade propane feedstock for propane dehydrogenation reaction, and table 2 shows the operating conditions of dehydrogenation reaction and regeneration process for propane dehydrogenation reaction according to the present invention, and using CO gas for heat coupling reaction.

Comparative example 1

Comparative example 1 illustrates the application effect of the prior art low-carbon alkane fixed bed dehydrogenation conversion method, device and reaction system in the process of dehydrogenating propane with chromium-based catalyst.

With reference to the contents of USP2419997, the same technical grade propane feedstock as in example 1, commercial Cr/Al obtained by commercial purchase, was used₂O₃The industrial dehydrogenation catalyst, a commercial industrial exothermic material auxiliary agent, was reacted under the typical HOUDRY type circulating fixed bed dehydrogenation process conditions, with the same reaction and regeneration temperature, feed space velocity as in example 3, reaction pressure of 0.045MPa, single stage reaction time of 9 minutes.

Example 4

Example 4 illustrates the application effect of the method, the device and the reaction system for dehydrogenation and conversion of the light alkane by the fixed bed in the process of dehydrogenation of propane by the molybdenum catalyst.

A propane dehydrogenation conversion run was run using the molybdenum/gamma-alumina dehydrogenation catalyst of example 2 and the adjunct of example 1 and following the feed, process conditions and procedures of example 3.

Comparative example 2

Comparative example 2 illustrates the application effect of the low-carbon alkane fixed bed dehydrogenation conversion method, device and reaction system in the molybdenum-based catalyst propane dehydrogenation process.

With reference to the contents of USP2419997, the same technical grade propane feedstock as in example 1, commercially available Mo/Al obtained by commercial purchase was used₂O₃The industrial dehydrogenation catalyst, a commercial industrial exothermic material auxiliary agent, was subjected to reaction operation under the cyclic fixed bed dehydrogenation process conditions of comparative example 1.

Example 5

Example 5 illustrates the effect of the low-carbon alkane dehydrogenation process, apparatus and reaction system of the present invention in dehydrogenation reaction when applied to mixed propane and isobutane feedstock for chromium-based catalysts.

The dehydrogenation catalysts and the auxiliary agents of examples 1 and 2 were charged in the fixed bed reactor according to the same procedure as in example 3, and the dehydrogenation reaction of the mixed raw material of propane and isobutane was carried out according to the process flow of the present invention and the raw materials and operating conditions of tables 3 and 4 below; potassium hydroxide is selected as a high-temperature heat medium in the heat supply pipe in the bed layer.

Table 3, propane and isobutane feed mix composition:

item	Composition/m%
		Propane	≥56
Isobutane	≥37
		Other Components	≤7

The data listed in table 3 are properties of industrial mixed feeds of propane and isobutane, and CO gas was obtained by separation from the regeneration vent gas of the inventive apparatus using a separation device.

TABLE 4 dehydrogenation and regeneration operating conditions for propane and isobutane mixed feed

Item	Data of
		Reaction feed temperature/. degree.C	591
Reactor pressure/MPa (absolute pressure)	0.105
		Feed space velocity/(WHSV) hr^-1	0.5
The CO accounts for v/v percent of the volume proportion of the raw material gas	5
		One wayReaction time/min	20～22.5
Regeneration air feed temperature/° c	670

Table 4 shows the dehydrogenation reaction and regeneration conditions of the low-carbon alkane dehydrogenation process applied to the dehydrogenation reaction of the propane and isobutane mixed raw material.

Example 6

Example 6 illustrates the application effect of the method, the device and the reaction system for dehydrogenation and conversion of the low-carbon alkane fixed bed in the dehydrogenation process of the molybdenum-based catalyst propane and butane mixed raw material.

The dehydrogenation conversion run of a mixed feed of propane and isobutane was carried out using the molybdenum/gamma-alumina dehydrogenation catalyst of example 2 and the adjunct of example 1 and following the feed, process conditions and procedures of example 5.

A high-temperature heat medium in a heat supply pipe is arranged in a reaction bed layer formed by the catalyst and the auxiliary agent, and high-temperature-resistant compressed carbon dioxide gas is used as the high-temperature gas heat medium.

Comparative example 3

Comparative example 3 illustrates the application effect of the low-carbon alkane fixed bed dehydrogenation conversion method, device and reaction system in the dehydrogenation process of the mixed raw material of the chromium catalyst propane and the isobutane.

With reference to the contents of USP2419997, the same technical grade propane and isobutane mixed feedstock as in example 5 was used, and commercially available Cr/Al was obtained by commercial means₂O₃Commercial dehydrogenation catalyst and heat-generating material assistant the dehydrogenation operation was carried out in the same operation mode as in comparative example 1 except that the reaction and regeneration temperatures and the space velocity of the feed were the same as in example 5, the reaction pressure was 0.045MPa and the single-stage reaction time was 9 minutes.

Comparative example 4

Comparative example 4 illustrates the application effect of the low-carbon alkane fixed bed dehydrogenation conversion method, device and reaction system in the dehydrogenation process of the molybdenum catalyst propane and isobutane mixed raw material in the prior art.

With reference to the contents of USP2419997, commercial Mo/Al obtained by commercial purchase using the same technical grade propane and isobutane mixed feedstock as in example 5₂O₃Commercial dehydrogenation catalysts, commercial heat generating material promoters, were run in the cyclic fixed bed dehydrogenation mode and operating conditions of comparative example 3.

Example 7

Example 7 illustrates the comparison of the operation conditions and the implementation effects of examples 3 to 4 of the present invention and comparative examples 1 to 2 in the dehydrogenation conversion of propane feedstock, as shown in tables 5 and 6.

TABLE 5 comparison of operating conditions for propane dehydrogenation reaction

Item	Example 3	Comparative example 1	Example 4	Comparative example 2
					Catalyst case	Example 1	Commercial purchase	Example 2	Commercial purchase
Catalyst composition	Cr/γ-Al₂O₃	Cr/Al₂O₃	Mo/γ-Al₂O₃	Mo/Al₂O₃
					Adjuvant situation	Example 1	Commercial purchase	Example 1	Commercial purchase
Adjuvant composition	Cu-Ca/Al₂O₃	-	Cu-Ca/Al₂O₃	-
					Coupling of heat of reaction	CO hydrogenation	Is free of	CO hydrogenation	Is free of
High temperature thermal medium	Lithium carbonate	Is free of	Sodium chloride	Is free of

In table 6 below, the overall conversion of propane is calculated as the product yield for the unconverted lower alkane return mode of operation.

TABLE 6 comparison of propane dehydrogenation run results

Item	Example 3	Comparative example 1	Example 4	Comparative example 2
					Per pass conversion of propane/%)	46	45	40	40
Total conversion of propane/%)	≥86	≥85	≥82	≥80
					Propylene selectivity/%)	88	85	83	82
Raw coke	Benchmark-20%	Datum	Benchmark-20%	Datum
					The reaction time is in percentage	63	41	62	40
Operating costs	Benchmark-11%	Datum	Reference-10%	Datum
					Amount of investment	Benchmark-40%	Datum	Benchmark-40%	Datum

Compared with the operation condition of a typical fixed bed dehydrogenation process in the prior art and comprising the application of the existing exothermic material, the invention has better implementation effect and better conversion efficiency and selectivity in the dehydrogenation reaction of the raw material in the propane industry.

On the aspect of the operation result of the dehydrogenation reaction, the invention more effectively improves the reaction process in the catalyst bed layer, improves the dehydrogenation conversion effect and reduces various losses of the process.

These operational results are advantageous over the performance results obtained in reducing the requirements of the process equipment and equipment, and the reaction system in terms of materials, design and operational operation.

Example 8

Example 8 illustrates the comparison of the implementation effect of examples 5 to 6 of the present invention and comparative examples 3 to 4 in the dehydrogenation conversion of the mixed raw material of propane and butane, so as to examine the dehydrogenation conversion effect of the present invention in the dehydrogenation conversion of the mixed raw material of butane and butane, and table 7 shows the comparison of the operation conditions of the dehydrogenation reaction of the mixed raw material of propane and butane.

TABLE 7 comparison of the operating conditions of dehydrogenation reactions for propane and butane mixed feedstocks

Item	Example 5	Comparative example 3	Example 6	Comparative example 4
					Catalyst case	Example 1	Commercial purchase	Example 2	Commercial purchase
Catalyst composition	Cr/γ-Al₂O₃	Cr/Al₂O₃	Mo/γ-Al₂O₃	Mo/Al₂O₃
					Adjuvant situation	Example 1	Commercial purchase	Example 1	Commercial purchase
Adjuvant composition	Cu-Ca/Al₂O₃	-	Cu-Ca/Al₂O₃	-
					Coupling of heat of reaction	CO hydrogenation	Is free of	CO hydrogenation	Is free of
High temperature thermal medium	Potassium hydroxide	Is free of	Carbon dioxide	Is free of

Table 8 shows the comparison of the operation results of dehydrogenation reaction of propane and butane mixed raw materials, and the two types of low-carbon alkanes have good conversion effect under the condition that the unconverted low-carbon alkane returns to the operation mode.

TABLE 8 comparison of run results for dehydrogenation of propane and butane mixed feeds

Item	Practice ofExample	5	Comparative example 3	Example 6	Comparative example 4
						Per pass conversion of propane/%)	49％	45％	40	39
Propylene selectivity/%)	88％	85％	82	80
					Conversion per pass of butane/%)	48％	45％	42	40
Butene selectivity/%)	87％	85％	83	80
					Raw coke	Benchmark-20%	Datum	Benchmark-20%	Datum
The reaction time is in percentage	63	41	62	41
					Operating costs	Reference-10%	Datum	Reference-10%	Datum
Amount of investment	Benchmark-40%	Datum	Benchmark-40%	Datum

Compared with the operation condition of a typical fixed bed dehydrogenation process in the prior art, the method comprises the application of the existing heating material, and has better conversion rate and selectivity of propane and isobutane in the dehydrogenation reaction of mixed industrial raw materials of propane and isobutane, so that better implementation effect is obtained. The method, the device and the reaction system provided by the invention have good raw material and process adaptability for the mixed low-carbon hydrocarbon with more complex composition.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A dehydrogenation conversion method of a low-carbon alkane fixed bed is characterized in that VIB and III loads are adopted in a high-temperature micro-positive pressure fixed bed reactorThe reaction bed layer formed by the gamma-alumina catalyst of B group element and alumina auxiliary agent loading IB and IIA group element stores heat and supplies heat in an intermittent mode of alternate reaction-regeneration; the heat coupling in the dehydrogenation-hydrogenation reaction process and the heating pipe in the high-temperature heat medium bed layer of the external heat source are used for realizing the heat balance in the conversion process and the temperature balance of the reaction bed layer; c is to be₃～C₅The low-carbon alkane is dehydrogenated and converted into low-carbon olefin.

2. The fixed bed dehydrogenation conversion method for light alkanes according to claim 1, wherein the reaction is carried out at 560-620 ℃ under a slight positive pressure of 0.103-0.105 MPa.

3. The fixed bed dehydrogenation conversion method for light alkanes according to claim 1, wherein the heat coupling in the reaction process is CO and/or CO accounting for 1-20 m% of the total amount of raw materials₂The gas reacts exothermically with the hydrogen produced during the reaction.

4. The fixed bed dehydrogenation conversion method for light alkanes of claim 1, wherein the catalyst contains 15-30 m% of Cr₂O₃0.1-5 m% of rare earth element and 65-80 m% of gamma-Al₂O₃。

5. The fixed bed dehydrogenation conversion method of light alkanes of claim 1, wherein the catalyst contains 15 m% -30 m% of Mo₂O₃0.1-5 m% of rare earth element and 65-80 m% of gamma-Al₂O₃。

6. The method of claim 1, wherein the auxiliary comprises 5-30 m% of CuO, 10-35 m% of CaO, and 50-80 m% of Al₂O₃The catalyst is placed in the catalyst bed layer in an amount of 1-25 v% of the total volume of the catalyst bed layerAnd (4) the following steps.

7. The fixed bed dehydrogenation conversion method for light alkanes according to claim 1, wherein the high temperature heat medium of the heating tube in the high temperature heat medium bed layer of the external heat source is selected from gas, molten salt and caustic alkali.

8. The fixed bed dehydrogenation conversion method for light alkanes of claim 1, wherein the fixed bed reactor comprises a housing and a catalyst reaction bed layer disposed in the housing; the shell is of a hollow metal structure and is connected with the end cover and the steel cylinder body through a flange; and is provided with an outer insulating layer and a high-temperature-resistant and thermal shock-resistant nano ceramic coating protective lining; a catalyst bed layer formed by a catalyst and an auxiliary agent is filled above the supporting space in the cylinder body; a multi-point thermocouple and a high-temperature heat medium heat supply pipe are arranged in the bed layer, and the heat supply pipe is connected to a heating furnace outside the reactor through an inlet pipeline and an outlet pipeline after being gathered in an end cover area; the material inlet is connected with the reactor from the upper part, and the material outlet is connected with the reactor from the lower part.

9. A low-carbon alkane dehydrogenation reaction system is characterized by comprising heating equipment, a reactor, separation equipment, reaction raw materials, gas for reaction coupling, a catalyst, an auxiliary agent, heat accumulator inert alumina balls and inert alumina ceramic balls for supporting; in the dehydrogenation reaction stage, the low-carbon alkane and the reaction coupling gas enter the reactor from the top of the reactor after being preheated, contact with a dehydrogenation catalyst, an auxiliary agent, a heat accumulator inert alumina ball and a support inert alumina ceramic ball, perform dehydrogenation conversion reaction and heat coupling reaction under the dehydrogenation reaction condition of high temperature and slight positive pressure, and locally control the temperature by a high-temperature heat medium heat supply pipe; discharging the converted product from the bottom of the reactor to a connected back-stage washing and separating device to separate low-carbon olefin, hydrogen-rich gas and fuel gas; returning unconverted low-carbon alkane to the reactor; in the regeneration stage, the feeding is stopped and steam purging is carried out, heated hot air enters the reactor from the top of the reactor to regenerate the catalyst bed, and the temperature of the reaction bed consisting of the catalyst and the auxiliary agent is increased to store heat.

10. A low-carbon alkane fixed bed dehydrogenation conversion device is characterized by comprising a raw material preheating furnace and an air preheating/heating furnace, wherein the raw material preheating furnace and the air preheating/heating furnace are connected to a reactor through a process pipeline; alternately keeping 3-6 parallel fixed bed reactors in reaction, regeneration and purging states; a series of separation devices connected to the reactor outlet for washing and separation of the reaction products; the compression and gasification equipment connected in the process pipeline is respectively used for compressing, circulating and gasifying the hydrocarbon and the air; heat exchange and condensation equipment and a waste heat boiler in the process pipeline are respectively used for heat exchange, condensation and heat recovery of raw materials, reaction coupling gas, products and exhaust gas which enter and exit the reactor.