CN106946637A - The device and technique of a kind of skid-mounted type lower carbon number hydrocarbons production methane - Google Patents

Abstract

The invention provides a skid-mounted device and process for producing methane from low-carbon hydrocarbons. The skid-mounted device for producing methane from low-carbon hydrocarbons includes a first feed pump, a second feed pump, a fine desulfurization reactor, a heating furnace, a hydrocarbon-water conversion reactor, a deep methanation reactor, a gas-liquid separator and membrane separator. The skid-mounted device for producing methane from low-carbon hydrocarbons provided by the present invention has the characteristics of easy storage of raw materials, small device volume, and convenient movement. It is easy to be modularized, suitable for skid-mounted design, easy to design, manufacture and commercial application; The process of producing methane from low-carbon hydrocarbons in the device has high production efficiency, high methane conversion rate, as high as 97%, high calorific value of the product, can be produced on demand, flexible and convenient to use, suitable for distributed energy and peak shaving, both Complementary to methane production by biological fermentation, it can also be used in places that are not convenient for pipeline transportation but need to use clean energy.

Description

A skid-mounted device and process for producing methane from low-carbon hydrocarbons

technical field

The invention belongs to the field of methane production technology, and in particular relates to a skid-mounted low-carbon hydrocarbon production methane device and technology.

Background technique

China is severely smoggy, and replacing coal with natural gas is an important solution. However, China lacks a natural gas pipeline network. In the absence of a pipeline network, the problems of natural gas supply and peak regulation need to be solved urgently, especially in remote towns.

Methane is a clean energy source and a high-quality chemical raw material, which is widely used in the fields of energy and chemical industry. In 2015, my country's methane-based natural gas consumption has reached 197.3 billion cubic meters, and it has maintained steady growth for many years. The demand for methane-based clean fuels is large.

There are many methods and ways to produce methane. Industrial methane production mainly includes: (1) Natural resources such as natural gas, shale gas, oilfield associated gas and other natural resources formed based on traditional fossil fuels formed by the long-term evolution of nature, usually large in scale, high in investment, Pipeline transportation is required, which is inconvenient for storage and transportation; (2) Coal-based natural gas, based on large-scale coal gasification and methanation, produces a large amount of methane-based substitute natural gas. Due to the high investment in coal gasification and environmental protection, and in order to reduce costs, the scale is usually as high as billions of cubic meters per year. Its storage and transportation are also inconvenient and rely on pipeline transportation; Using biological fermentation technology, its gas production speed and efficiency are usually not high, it needs to occupy a large space, and the cost of raw material collection is high, and the product gas is inconvenient to use. Large-scale methanation-based natural gas production and use are limited by pipeline transportation, and are also challenged by peak shaving caused by the huge difference in gas consumption in winter and summer. The production of biological methane is limited by raw material collection, gas production efficiency, site occupation, and use radius.

As far as methane production is concerned, in recent years, with the continuous and steady growth of demand for clean energy and the development of large-scale coal-to-natural gas industrialization in China, many companies and research and development units have applied for the relevant syngas-to-methane production technology: application Patent application No. 201080040515.4 discloses a method of producing methane, a feed gas containing carbon monoxide and hydrogen is produced in an internal water-cooled methanation reactor containing nickel methanation catalyst to produce a product gas containing methane; patent application No. 200810226891.7 Disclosed is a process for synthesizing methane by using purge gas from methanol or coal-based synthesis gas, and using a heat-exchanging reactor with internal heating and cooling tubes through a deep methane catalyst; the patent application with application number 201310226488.5 discloses a A method for producing methane co-production liquid fuel from carbonaceous materials, purifying the crude synthesis gas obtained after gasification of carbonaceous materials, mixing with water, generating gas and liquid products on the catalyst, and separating methane; the patent application publication number is 201310226609.6 A method for producing methane co-production of low-carbon alcohols from carbonaceous material gasification synthesis gas, and separating and obtaining methane; the patent application with application number 201310226488.5 discloses a method for producing methane co-production liquid from carbonaceous material gasification synthesis gas Fuel method; Patent Application No. 200910074977.7 discloses a methane production process based on coke oven gas, using purified coke oven gas to react carbon monoxide and carbon dioxide with hydrogen methanation to produce methane.

In addition, there are many methods for producing methane based on biological fermentation: the patent application with application number 201380024947.X discloses a solid-state fermentation method and its bioreactor and solid support for methane production; A method for producing methane by anaerobic fermentation of sludge is disclosed; the patent application with application number 201310572573.7 discloses a method for producing methane by mixed anaerobic fermentation of domestic garbage and livestock.

The above methods are mainly based on the direct production or co-production of methane from syngas or bio-fermentation. Either it needs to be produced on a large enough scale, mainly using a mixed gas rich in carbon monoxide and hydrogen such as syngas from carbonaceous raw material gasification or coke oven gas from pyrolysis as raw material, so the adjustment brought by seasonal effects must be considered at the same time. Peak problem; or based on the anaerobic fermentation of biomass, the production radius and large site occupation need to be considered, the production efficiency is low, and the application range is limited.

Contents of the invention

In order to solve the problems of high methane production cost, low production efficiency, and peak regulation in the prior art, the object of the present invention is to provide a skid-mounted device and process for producing methane from low-carbon hydrocarbons. Small size, easy to move, etc. At the same time, the process of the present invention has high production efficiency, high methane conversion rate, flexible and convenient use, and is suitable for use as a distributed energy source, or complementary to other methane production processes, and used in cities and towns that do not have natural gas pipelines , or complement with biological fermentation to solve scattered urban energy problems, etc.

The purpose of the present invention is achieved through the following technical solutions:

The invention provides a skid-mounted device for producing methane from low-carbon hydrocarbons. The device for producing methane from skid-mounted low-carbon hydrocarbons includes a first feed pump, a second feed pump, a fine desulfurization reactor, a heating furnace, and a hydrocarbon- Water conversion reactors, deep methanation reactors, gas-liquid separators and membrane separators;

The first feed pump communicates with the fine desulfurization reactor, the fine desulfurization reactor communicates with the heating furnace, the second feed pump communicates with the heating furnace, and the heating furnace , the hydrocarbon-water conversion reactor, the deep methanation reactor and the gas-liquid separator are connected in sequence, the gas outlet end of the gas-liquid separator is connected with the membrane separator, and the membrane separator The methane outlet end of the separator produces methane, and the tail gas outlet end of the membrane separator communicates with the heating furnace.

In the above-mentioned device for producing methane from skid-mounted low-carbon hydrocarbons, preferably, the device for producing methane from skid-mounted low-carbon hydrocarbons also includes a first heat exchanger and a second heat exchanger, and the hydrocarbon-water conversion reactor The outlet end communicates with the first heat exchanger, the first heat exchanger communicates with the deep methanation reactor, and the deep methanation reactor communicates with the second heat exchanger, so The second heat exchanger communicates with the gas-liquid separator.

In the above-mentioned device for producing methane from skid-mounted low-carbon hydrocarbons, preferably, the device for producing methane from skid-mounted low-carbon hydrocarbons also includes a methane storage tank, and the methane outlet end of the membrane separator communicates with the methane storage tank .

In the above-mentioned device for producing methane from skid-mounted low-carbon hydrocarbons, preferably, the fine desulfurization reactor is provided with a desulfurizer bed inside, and the desulfurizer bed is loaded with Cu/molecular sieve desulfurizer, and the Cu/molecular sieve desulfurizer The trademark of the agent is SQ-108.

In the above-mentioned skid-mounted low-carbon hydrocarbon production methane device, preferably, the hydrocarbon-water conversion reactor is provided with a conversion catalyst bed, and the conversion catalyst bed is loaded with unreduced Ni/Al ₂ O ₃ Catalyst, the unreduced Ni/Al ₂ O ₃ catalyst can be purchased from the market or prepared in a laboratory.

In the skid-mounted device for producing methane from low-carbon hydrocarbons, preferably, the content of nickel oxide in the unreduced Ni/Al ₂ O ₃ catalyst is greater than or equal to 60%, and the rest is alumina.

In the above-mentioned device for producing methane from skid-mounted low _- carbon hydrocarbons, preferably, the unreduced Ni/ _Al2O3 catalyst is prepared by the following preparation method:

Weigh nickel nitrate and aluminum nitrate, add asparagus powder and desalted water to prepare mixed solution A; add urea to mixed solution A, stir to dissolve, then place in a reflux device with heating, heat while stirring, so that Slowly decompose urea and precipitate nickel ions and aluminum ions into a uniform mixture B; after sufficient precipitation, stop heating, and after the solution is cooled, use a plate and frame filter press to filter and wash the precipitate with water to obtain a filter cake; dry the filter cake Obtain the catalyst precursor of Ni/Al ₂ O ₃ ; add graphite powder and safflower powder to the dried Ni/Al ₂ O ₃ catalyst precursor, extrude, granulate, and then form pellets into pellets and roast at elevated temperature , the temperature is naturally lowered to obtain an unreduced Ni/Al ₂ O ₃ catalyst.

In the above-mentioned device for producing methane from skid-mounted low _- carbon hydrocarbons, preferably, the unreduced Ni/ _Al2O3 catalyst is prepared by the following preparation method:

Weigh nickel nitrate and aluminum nitrate according to the Ni:Al atomic ratio of 1:1, and add 2% of the total mass of nickel nitrate and aluminum nitrate and desalinated water to prepare a mixture with a metal ion concentration of 1-2mol/L. Solution A1;

Add urea to the mixed solution A1, the amount of urea added is measured in moles as: n(CO(NH ₂ ) ₂ )=1.2×[n(Ni)+1.5n(Al)], stir to dissolve, and then set In a reflux device with heating, heat to 100°C while stirring, and keep it for 24 hours to slowly decompose urea and precipitate nickel ions and aluminum ions into a homogeneous mixture B1;

After sufficient precipitation, stop heating, and after the solution is cooled, use a plate and frame filter press to filter and wash the precipitate with deionized water equal to the volume of mixture B1 three times to obtain a filter cake;

Put the filter cake in an oven, raise the temperature from room temperature to 80°C at a rate of 1°C/min, and keep it dry in circulating hot air for 12 hours to obtain a catalyst precursor of Ni/Al ₂ O ₃ ;

Add its mass 1% graphite powder and ₂ % kale powder to the dried Ni/ _Al2O3 catalyst precursor, extrude, granulate, and then slice into 6 × 6mm cylindrical particles, Then the temperature was raised to 650° C. at a rate of 5° C./min, and the temperature was maintained for 12 hours for calcination, and the temperature was naturally lowered to obtain an unreduced Ni/Al ₂ O ₃ catalyst.

When carrying out the catalytic reaction, the unreduced Ni/Al ₂ O ₃ catalyst is loaded on the conversion catalyst bed and reduced to Ni/Al ₂ O ₃ catalyst by conventional methods.

In the above-mentioned skid-mounted low-carbon hydrocarbon production methane device, preferably, a methanation catalyst bed is arranged inside the deep methanation reactor, and the methanation catalyst bed is loaded with unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst, the unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst can be purchased commercially or prepared in a laboratory.

In the above skid-mounted low-carbon hydrocarbon production methane device, preferably, the content of nickel oxide in the unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst is greater than or equal to 50%, and the content of lanthanum oxide is 3 %, the rest is alumina.

In the above-mentioned skid-mounted device for producing methane from low-carbon hydrocarbons, preferably, the unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst is prepared by the following preparation method:

Roast pseudo-boehmite as raw material, and naturally cool down to obtain alumina prepared at high temperature; use nickel nitrate and lanthanum nitrate to prepare a solution, use ammonium carbonate to precipitate, filter, heat up, and then naturally cool down to obtain nickel-lanthanum oxide; Mix alumina prepared at high temperature with nickel-lanthanum oxide to obtain mixture C, then add graphite powder and safflower powder, and put it into a ball mill for ball milling, after mixing thoroughly, flake and form particles; roast the formed particles, and then naturally The temperature was lowered to obtain an unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst.

In the above-mentioned skid-mounted device for producing methane from low-carbon hydrocarbons, preferably, the unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst is prepared by the following preparation method:

Use pseudo-boehmite as raw material, heat up to 950°C at a rate of 5°C/min and roast for 6 hours, then cool down naturally to obtain alumina prepared at high temperature;

Use nickel nitrate and lanthanum nitrate to prepare a 2mol/L solution according to the Ni:La atomic ratio of 36:1, use ammonium carbonate to precipitate, filter and heat up to 350°C at a speed of 5°C/min, keep it for 6 hours, and then cool down naturally Obtain nickel lanthanum oxide;

Mix aluminum oxide prepared at high temperature with nickel-lanthanum oxide at a mass ratio of 50:50 to obtain a mixture C1, then add 1% graphite powder and 2% scallop powder according to the mass of the mixture C1, and put them into a ball mill for ball milling for 2 hours, After fully mixing, tablet forming into 6×6mm cylindrical particles;

The shaped cylindrical pellets were heated up to 550°C at a rate of 5°C/min, kept at the temperature and calcined for 12 hours, and then cooled down naturally to obtain an unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst.

During the catalytic reaction, the unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst is loaded on the methanation catalyst bed and reduced to Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst by conventional methods.

In the skid-mounted device for producing methane from low-carbon hydrocarbons, preferably, the membrane used in the membrane separator is a polyimide hollow fiber membrane.

The present invention also provides a process for producing methane from low-carbon hydrocarbons, which adopts the above-mentioned skid-mounted device for producing methane from low-carbon hydrocarbons, including the following steps:

Step 1, transporting low-carbon hydrocarbons to the desulfurizer bed inside the fine desulfurization reactor through the first feed pump for desulfurization treatment, so that the total sulfur content is less than 1ppm;

Step 2: The desulfurized low-carbon hydrocarbons are mixed with the water delivered by the second feed pump and sent to the heating furnace for heating, and the heated mixture is sent to the conversion catalyst bed in the hydrocarbon-water conversion reactor The catalytic reaction is carried out on the layer, and the reaction is carried out under adiabatic conditions to obtain synthesis gas containing methane, carbon monoxide, carbon dioxide and hydrogen;

In step 3, the synthesis gas is cooled by the first heat exchanger and transported to the methanation catalyst bed in the deep methanation reactor for catalytic reaction, and further catalytic conversion of carbon monoxide, carbon dioxide and hydrogen in the synthesis gas into methane is obtained. A mixture of methane and tail gas;

Step 4, transporting the mixed gas to the gas-liquid separator for dehydration after being cooled by the second heat exchanger;

Step 5, the dehydrated mixed gas is sent to the membrane separator for further separation of methane gas and tail gas, the methane gas is sent to the methane storage tank, and the tail gas is sent to the heating furnace to burn and recover heat.

In the above process for producing methane from low-carbon hydrocarbons, preferably, the temperature of the catalytic reaction in the hydrocarbon-water conversion reactor is 350-550°C, the pressure is normal pressure to 6MPa, the carbon space velocity is 300-3000h ^-1 , the water The carbon ratio is (1-4):1.

In the above process for producing methane from low-carbon hydrocarbons, preferably, the temperature of the catalytic reaction in the deep methanation reactor is 240-650°C, the pressure is normal pressure to 6MPa, the carbon space velocity is 1000-3000h ^-1 , the water carbon The ratio is (1-4):1.

In the above process for producing methane from low-carbon hydrocarbons, preferably, the temperature of the synthesis gas is 250-300° C. after the first heat exchanger is cooled.

In the above process for producing methane from low-carbon hydrocarbons, preferably, the low-carbon hydrocarbons are _C4 - _C10 light saturated hydrocarbons; more preferably, the low-carbon hydrocarbons may include oilfield gas, liquefied petroleum gas and naphtha One or more combinations of oils. The low-carbon hydrocarbon raw materials used in the present invention are all light low-carbon hydrocarbons, which are easy to liquefy, store and transport, have high energy density, are small in volume, and are convenient for skid-mounting.

In the process of producing methane from low-carbon hydrocarbons mentioned above, the desulfurization and purification treatment of low-carbon hydrocarbon raw materials is to use a pump to pressurize into the Cu/molecular sieve desulfurizer bed, and directly adsorb and remove the sulfide in it, so that the raw materials are purified. After purification The total sulfur content of sulfides harmful to subsequent processing in raw materials is controlled below 1ppm, thus ensuring the smooth progress of the subsequent conversion process.

In the process of producing methane from the above-mentioned low-carbon hydrocarbons, the heated mixture is transported to the hydrocarbon-water conversion reactor (adiabatic fixed _- bed reactor filled with unreduced Ni/ _Al2O3 catalyst) for catalytic reaction, and the reaction The temperature is 350-550°C, the pressure is from normal pressure to 6MPa, and the carbon space velocity is 300-3000h ^-1 . The series of complex reactions shown in Table 1 below occur on the catalyst for light hydrocarbons. Here, all low-carbon hydrocarbons are converted into carbon-one compounds such as CH ₄ , CO ₂ , CO, and H ₂ . Usually these reactions will cause the temperature of the outlet gas to rise because the heat release is greater than the heat absorption, and the CH ₄ content in the product gas can be as high as 50%, and the specific content is closely related to the raw materials and process conditions.

Table 1

In the above process of producing methane from low-carbon hydrocarbons, the synthesis gas generated through the hydrocarbon-water conversion reactor usually contains more CO ₂ , H ₂ and a small amount of CO. Generally speaking, the temperature of this stream is also relatively high, because the adiabatic temperature rise can usually reach more than 500°C. For this reason, the stream needs to be cooled to about 300°C through the second heat exchanger, and sent to the deep methanation reactor (packed with highly efficient CO ₂ methanation and CO methanation unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst fixed-bed reactor), convert part of CO ₂ , almost all CO and H ₂ into CH ₄ , and obtain a methanation gas mixture mainly containing CH ₄ , a small amount of CO ₂ and trace amounts of CO and H ₂ . Using low-carbon light saturated hydrocarbons, the mass yield of _CH4 can reach more than 85%.

In the process of producing methane from the above-mentioned low-carbon hydrocarbons, polyimide hollow fiber membranes are used in the membrane separator, and in the preferred case, two-stage membrane separation and purification are used to obtain product gas with a CH content of up to 97% _. CH ₄ The recovery rate reaches more than 95%. The separated tail gas is used as the combustion furnace fuel to heat the raw material, and the high-concentration CH ₄ product gas enters the buffer storage tank for users to use.

The skid-mounted device for producing methane from low-carbon hydrocarbons provided by the present invention has the characteristics of easy storage of raw materials, small device volume, and convenient movement. It is easy to be modularized, suitable for skid-mounted design, easy to design, manufacture and commercial application; The process of producing methane from low-carbon hydrocarbons in the device has high production efficiency, high methane conversion rate, as high as 97%, high calorific value of the product, can be produced on demand, flexible and convenient to use, suitable for distributed energy and peak shaving, both Complementary to methane production by biological fermentation, it can also be used in places that are not convenient for pipeline transportation but need to use clean energy.

Description of drawings

Fig. 1 is the device schematic diagram of the skid-mounted low-carbon hydrocarbon production methane of embodiment 1 of the present invention;

Explanation of reference symbols:

1 first feed pump, 2 second feed pump, 3 fine desulfurization reactor, 4 heating furnace, 5 hydrocarbon-water conversion reactor, 6 first heat exchanger, 7 deep methanation reactor, 8 second exchanger Heater, 9 gas-liquid separators, 10 membrane separators, 11 methane storage tanks.

detailed description

In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

Example 1

This embodiment provides a device for producing methane from skid-mounted low-carbon hydrocarbons. As shown in Figure 1, the device for producing methane from skid-mounted low-carbon hydrocarbons includes a first feed pump 1, a second feed pump 2, a refining Desulfurization reactor 3, heating furnace 4, hydrocarbon-water conversion reactor 5, first heat exchanger 6, deep methanation reactor 7, second heat exchanger 8, gas-liquid separator 9, membrane separator 10 and methane storage tank 11;

The first feed pump 1 is connected with the fine desulfurization reactor 3, the fine desulfurization reactor 3 is connected with the heating furnace 4, the second feed pump 2 is connected with the heating furnace 4, and the heating furnace 4 is connected with the hydrocarbon-water conversion reactor 5 are connected, the hydrocarbon-water conversion reactor 5 is connected with the first heat exchanger 6, the first heat exchanger 6 is connected with the deep methanation reactor 7, and the deep methanation reactor 7 is connected with the second heat exchanger 8 The second heat exchanger 8 communicates with the gas-liquid separator 9, the gas outlet end of the gas-liquid separator 9 communicates with the membrane separator 10, and the methane outlet end of the membrane separator 10 communicates with the methane storage tank 11 , The tail gas outlet end of the membrane separator 10 communicates with the heating furnace 4 .

The fine desulfurization reactor 3 is provided with a desulfurizer bed, and the desulfurizer bed is loaded with a Cu/molecular sieve desulfurizer, and the brand name of the Cu/molecular sieve desulfurizer is SQ-108; the hydrocarbon-water conversion reactor 5 is equipped with There is a conversion catalyst bed layer, and the conversion catalyst bed layer is loaded with an unreduced Ni/Al ₂ O ₃ catalyst, and the content of nickel oxide in the unreduced Ni/Al ₂ O ₃ catalyst is greater than or equal to 60%, and the rest is Alumina; deep methanation reactor 7 is provided with a methanation catalyst bed, the methanation catalyst bed is loaded with unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst, the unreduced Ni The content of nickel oxide in the /La ₂ O ₃ /Al ₂ O ₃ catalyst is greater than or equal to 50%, the content of lanthanum oxide is 3%, and the rest is aluminum oxide; the membrane used in the membrane separator 10 is a polyimide hollow fiber membrane .

_In this embodiment, the preparation method of the unreduced Ni/ _Al2O3 catalyst is:

Weigh nickel nitrate and aluminum nitrate according to the Ni:Al atomic ratio of 1:1, and add 2% of the total mass of nickel nitrate and aluminum nitrate and water to prepare a mixed solution with a metal ion concentration of 1-2mol/L A;

Add urea to the mixed solution, the amount of urea added is measured in moles as: n(CO(NH ₂ ) ₂ )=1.2×[n(Ni)+1.5n(Al)], stir to dissolve, and then place In a reflux device with heating, heat to 100°C while stirring, and keep it for 24 hours to slowly decompose urea and precipitate nickel ions and aluminum ions into a homogeneous mixture B;

After sufficient precipitation, stop heating, and after the solution is cooled, use a plate and frame filter press to filter and wash the precipitate with deionized water equal to the volume of mixture B three times to obtain a filter cake;

Put the filter cake in an oven, raise the temperature from room temperature to 80°C at a rate of 1°C/min, and keep it dry in circulating hot air for 12 hours to obtain a catalyst precursor of Ni/Al ₂ O ₃ ;

Add its quality 1% graphite powder and ₂ % scallop powder to the catalyst precursor of the dried Ni/ _Al2O3 , extrude, granulate, and then slice into 6 × 6mm cylindrical particles, Then, the temperature was raised to 650° C. at a rate of 5° C./min, kept at the temperature for calcination for 12 hours, and the temperature was naturally lowered to prepare a non-reduced Ni/Al ₂ O ₃ catalyst. When catalyzed, it is loaded on the conversion catalyst bed and reduced to Ni/Al ₂ O ₃ catalyst by conventional methods.

In this example, the preparation method of the unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst is as follows:

Use pseudo-boehmite as raw material, heat up to 950°C at a rate of 5°C/min and roast for 6 hours, then cool down naturally to obtain alumina prepared at high temperature;

Use nickel nitrate and lanthanum nitrate to prepare a 2mol/L solution according to the Ni:La atomic ratio of 36:1, use ammonium carbonate to precipitate, filter and heat up to 350°C at a speed of 5°C/min, keep it for 6 hours, and then cool down naturally Obtain nickel lanthanum oxide;

Mix the aluminum oxide prepared at high temperature with nickel-lanthanum oxide at a mass ratio of 50:50 to obtain a mixed solution C, then add 1% graphite powder and 2% scallop powder according to the quality of the mixed solution C, and put them into a ball mill for ball milling 2 Hours, after fully mixing, tablet molding into 6 × 6mm cylindrical particles;

The shaped cylindrical pellets were heated up to 550°C at a rate of 5°C/min, kept at the temperature and calcined for 12 hours, and then cooled down naturally to obtain an unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst. When performing catalysis, it is loaded on a methanation catalyst bed and reduced to Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst by conventional methods.

Example 2

This embodiment provides a process for producing methane from low-carbon hydrocarbons, which is carried out by using the skid-mounted device for producing methane from low-carbon hydrocarbons provided in Example 1. In this embodiment, the low-carbon hydrocarbons are liquefied petroleum gas. The process includes the following step:

Step 1, the liquefied petroleum gas is transported to the desulfurizer bed inside the fine desulfurization reactor 3 through the first feed pump 1 according to the mass flow rate of 820kg/h for desulfurization treatment. After the desulfurization treatment, the total sulfur content in the liquefied petroleum gas From 55.9ppm to 0.8ppm;

Step 2, the desulfurized liquefied petroleum gas is mixed with the water delivered by the second feed pump 2 and sent to the heating furnace 4 for heating. The feed flow rate of water is 1000kg/h, and the feed pressure of the mixture is controlled. It is 1MPa, and the mixture heated to 370°C is transported to the conversion catalyst bed in the hydrocarbon-water conversion reactor 5 for catalytic reaction. The reaction is carried out under adiabatic conditions, and the CH ₄ in the dry gas component of the obtained syngas is 69.1%. , CO ₂ 19%, CO 0.6%, H ₂ 11.3%, the synthesis gas also contains a lot of water vapor, and the temperature of the synthesis gas is 455°C;

Step 3, the temperature of the synthesis gas is lowered to 250°C through the first heat exchanger 6, and then transported to the methanation catalyst bed in the deep methanation reactor 7 for catalytic reaction, further catalyzing the carbon monoxide, carbon dioxide and hydrogen in the synthesis gas Converted to methane to obtain a mixture of methane and tail gas, in which CH ₄ 78.5%, CO ₂ 18.8%, CO 0.2%, H ₂ 2.4%, water content 36.7%, and temperature 320°C in the dry gas composition at the outlet;

Step 4, after cooling the mixed gas through the second heat exchanger 8, transport it to the gas-liquid separator 9 for dehydration treatment, the dehydration amount is 600kg/h;

Step 5, the dehydrated mixed gas is sent to the membrane separator 10 to further separate about 950Nm ³ /h of methane gas and the remaining tail gas, the methane gas is sent to the methane storage tank, and the tail gas is sent to the heating furnace for combustion and recovery heat.

Example 3

This embodiment provides a process for producing methane from low-carbon hydrocarbons, which is carried out by using the skid-mounted device for producing methane from low-carbon hydrocarbons provided in Example 1. The low-carbon hydrocarbons in this embodiment are oilfield gas, and the process includes the following steps :

Step 1, a certain oilfield gas is transported to the desulfurizer bed inside the fine desulfurization reactor 3 through the first feed pump 1 according to the mass flow rate of 1000kg/h for desulfurization treatment. After the desulfurization treatment, the total sulfur content in the oilfield gas is from 30ppm down to 0.7ppm;

Step 2, the desulfurized oilfield gas is mixed with the water delivered by the second feed pump 2 and sent to the heating furnace 4 for heating. The feed flow rate of water is 2000kg/h, and the feed pressure of the mixture is controlled as 3MPa, the mixture heated to 350°C is transported to the conversion catalyst bed in the hydrocarbon-water conversion reactor 5 for catalytic reaction, the reaction is carried out under adiabatic conditions, and the CH ₄ in the dry gas component of the obtained syngas is 71.4%. CO ₂ 20.3%, CO 0.2%, H ₂ 8.1%, the synthesis gas also contains more water vapor, and the temperature of the synthesis gas is 430°C;

Step 3, the temperature of the synthesis gas is lowered to 300°C through the first heat exchanger 6, and then transported to the methanation catalyst bed in the deep methanation reactor 7 for catalytic reaction, further catalyzing the carbon monoxide, carbon dioxide and hydrogen in the synthesis gas Converted to methane to obtain a mixture of methane and tail gas, in which CH ₄ 77.4%, CO ₂ 20.1%, CO 0.02%, H ₂ 2.4%, water content 53.7%, and temperature 330°C in the dry gas composition at the outlet;

Step 4, after cooling the mixed gas through the second heat exchanger 8, transport it to the gas-liquid separator 9 for dehydration treatment, and the dehydration amount is 1400kg/h;

Step 5, the dehydrated mixed gas is sent to the membrane separator 10 to further separate about 1170Nm ³ /h of methane gas and the remaining tail gas, the methane gas is sent to the methane storage tank, and the tail gas is sent to the heating furnace for combustion and recovery heat.

Example 4

This embodiment provides a process for producing methane from low-carbon hydrocarbons, which is carried out by using the skid-mounted methane production device from low-carbon hydrocarbons provided in Example 1. In this embodiment, low-carbon hydrocarbons are naphtha, and the process includes the following step:

Step 1, the liquefied petroleum gas is transported to the desulfurizer bed inside the fine desulfurization reactor 3 through the first feed pump 1 according to the mass flow rate of 1200kg/h for desulfurization treatment. After the desulfurization treatment, the total sulfur content in naphtha From 70ppm to 0.9ppm;

Step 2, the desulfurized naphtha is mixed with the water delivered by the second feed pump 2 and sent to the heating furnace 4 for heating, the feed flow rate of water is 2000kg/h, and the feed pressure of the mixture is controlled 5MPa, the mixture heated to 360°C is transported to the conversion catalyst bed in the hydrocarbon-water conversion reactor 5 for catalytic reaction, the reaction is carried out under adiabatic conditions, and the CH ₄ in the dry gas component of the obtained syngas is 71.8% , CO ₂ 21.9%, CO 0.2%, H ₂ 6.1%, the synthesis gas also contains a lot of water vapor, and the temperature of the synthesis gas is 440°C;

Step 3, the temperature of the synthesis gas is lowered to 280°C through the first heat exchanger 6, and then transported to the methanation catalyst bed in the deep methanation reactor 7 for catalytic reaction, further catalyzing the carbon monoxide, carbon dioxide and hydrogen in the synthesis gas Converted to methane to obtain a mixture of methane and tail gas, in which CH ₄ 77%, CO ₂ 21.9%, CO 0.01%, H ₂ 1.1%, water content 49.7%, and temperature 310°C in the dry gas composition at the outlet;

Step 4, after cooling the mixed gas through the second heat exchanger 8, transport it to the gas-liquid separator 9 for dehydration treatment, and the dehydration amount is 1300kg/h;

Step 5, the dehydrated mixed gas is sent to the membrane separator 10 to further separate about 1250Nm ³ /h methane gas and tail gas, the methane gas is sent to the methane storage tank, and the tail gas is sent to the heating furnace for combustion and recovery of heat.

In summary, the skid-mounted device for producing methane from low-carbon hydrocarbons provided by the present invention has the characteristics of easy storage of raw materials, small device volume, convenient movement, etc., and is easy to be modularized, suitable for skid-mounted design, easy to design, manufacture and commercial application; At the same time, the present invention uses the device to produce methane from low-carbon hydrocarbons, which has high production efficiency, high methane conversion rate of over 97%, high calorific value of products, on-demand production, flexible and convenient use, and is suitable for distributed energy sources and Peak shaving can not only complement methane production by biological fermentation, but also be used in places where pipeline transportation is not convenient but clean energy is needed.

Claims (10)

1. A device for producing methane from skid-mounted low-carbon hydrocarbons, characterized in that: the device for producing methane from skid-mounted low-carbon hydrocarbons includes a first feed pump, a second feed pump, a fine desulfurization reactor, and a heating furnace , hydrocarbon-water conversion reactor, deep methanation reactor, gas-liquid separator and membrane separator; The first feed pump communicates with the fine desulfurization reactor, the fine desulfurization reactor communicates with the heating furnace, the second feed pump communicates with the heating furnace, and the heating furnace , the hydrocarbon-water conversion reactor, the deep methanation reactor and the gas-liquid separator are connected in sequence, the gas outlet end of the gas-liquid separator is connected with the membrane separator, and the membrane separator The methane outlet end of the separator produces methane, and the tail gas outlet end of the membrane separator communicates with the heating furnace; Preferably, the device for producing methane from skid-mounted low-carbon hydrocarbons also includes a first heat exchanger and a second heat exchanger, and the outlet end of the hydrocarbon-water conversion reactor is communicated with the first heat exchanger , the first heat exchanger is communicated with the deep methanation reactor, the deep methanation reactor is communicated with the second heat exchanger, and the second heat exchanger is separated from the gas-liquid device connected; Preferably, the skid-mounted device for producing methane from low-carbon hydrocarbons further includes a methane storage tank, and the methane outlet port of the membrane separator is connected to the methane storage tank. 2. The device for producing methane from skid-mounted low-carbon hydrocarbons according to claim 1, characterized in that: a desulfurizer bed is arranged inside the fine desulfurization reactor, and Cu/molecular sieve is loaded on the desulfurizer bed Desulfurizer. 3. The device for producing methane from skid-mounted low-carbon hydrocarbons according to claim 1, characterized in that: the inside of the hydrocarbon-water conversion reactor is provided with a conversion catalyst bed, and the conversion catalyst bed is loaded with untreated Reduced Ni/Al ₂ O ₃ catalyst. 4. The device for producing methane from skid-mounted low-carbon hydrocarbons according to claim 3, characterized in that: the content of nickel oxide in the unreduced Ni/Al ₂ O ₃ catalyst is greater than or equal to 60%, and the rest is oxidized aluminum; Preferably, the unreduced Ni/Al ₂ O ₃ catalyst is prepared by the following preparation method: Weigh nickel nitrate and aluminum nitrate, add asparagus powder and desalted water to prepare mixed solution A; add urea to mixed solution A, stir to dissolve, then place in a reflux device with heating, heat while stirring, so that Slowly decompose urea and precipitate nickel ions and aluminum ions into a uniform mixture B; after sufficient precipitation, stop heating, and after the solution is cooled, use a plate and frame filter press to filter and wash the precipitate with water to obtain a filter cake; dry the filter cake Obtain the catalyst precursor of Ni/Al ₂ O ₃ ; add graphite powder and safflower powder to the dried Ni/Al ₂ O ₃ catalyst precursor, extrude, granulate, and then form pellets into pellets and roast at elevated temperature , natural cooling to obtain unreduced Ni/Al ₂ O ₃ catalyst; Preferably, the unreduced Ni/Al ₂ O ₃ catalyst is prepared by the following preparation method: Weigh nickel nitrate and aluminum nitrate according to the Ni:Al atomic ratio of 1:1, and add 2% of the total mass of nickel nitrate and aluminum nitrate and desalinated water to mix and prepare a metal ion concentration of 1-2mol/L. Mixed solution A1; Add urea to the mixed solution A1, the amount of urea added is measured in moles as: n(CO(NH ₂ ) ₂ )=1.2×[n(Ni)+1.5n(Al)], stir to dissolve, and then set In a reflux device with heating, heat to 100°C while stirring, and keep it for 24 hours to slowly decompose urea and precipitate nickel ions and aluminum ions into a homogeneous mixture B1; After sufficient precipitation, stop heating, and after the solution is cooled, use a plate and frame filter press to filter and wash the precipitate with deionized water equal to the volume of mixture B1 three times to obtain a filter cake; Put the filter cake in an oven, raise the temperature from room temperature to 80°C at a rate of 1°C/min, and keep it dry in circulating hot air for 12 hours to obtain a catalyst precursor of Ni/Al ₂ O ₃ ; Add its mass 1% graphite powder and ₂ % kale powder to the dried Ni/ _Al2O3 catalyst precursor, extrude, granulate, and then slice into 6 × 6mm cylindrical particles, Then the temperature was raised to 650° C. at a rate of 5° C./min, and the temperature was maintained for 12 hours for calcination, and the temperature was naturally lowered to obtain an unreduced Ni/Al ₂ O ₃ catalyst. 5. The device for producing methane from skid-mounted low-carbon hydrocarbons according to claim 1, characterized in that: the inside of the deep methanation reactor is provided with a methanation catalyst bed, and the methanation catalyst bed is loaded with Reduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst. 6. The device for producing methane from skid-mounted low-carbon hydrocarbons according to claim 5, characterized in that: the content of nickel oxide in the unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst is greater than or equal to 50 %, the content of lanthanum oxide is 3%, and the rest is aluminum oxide; Preferably, the unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst is prepared by the following preparation method: Roast pseudo-boehmite as raw material, and naturally cool down to obtain alumina prepared at high temperature; use nickel nitrate and lanthanum nitrate to prepare a solution, use ammonium carbonate to precipitate, filter, heat up, and then naturally cool down to obtain nickel-lanthanum oxide; Mix alumina prepared at high temperature with nickel-lanthanum oxide to obtain mixture C, then add graphite powder and safflower powder, and put it into a ball mill for ball milling, after mixing thoroughly, flake and form particles; roast the formed particle balls, and then Natural cooling to obtain unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst; Preferably, the unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst is prepared by the following preparation method: Use pseudo-boehmite as raw material, heat up to 950°C at a rate of 5°C/min and roast for 6 hours, then cool down naturally to obtain alumina prepared at high temperature; Use nickel nitrate and lanthanum nitrate to prepare a 2mol/L solution according to the Ni:La atomic ratio of 36:1, use ammonium carbonate to precipitate, filter and heat up to 350°C at a speed of 5°C/min, keep it for 6 hours, and then cool down naturally Obtain nickel lanthanum oxide; Mix aluminum oxide prepared at high temperature with nickel-lanthanum oxide at a mass ratio of 50:50 to obtain a mixture C1, then add 1% graphite powder and 2% scallop powder according to the mass of the mixture C1, and put them into a ball mill for ball milling for 2 hours, After fully mixing, tablet forming into 6×6mm cylindrical particles; The formed cylindrical particles were heated up to 550°C at a rate of 5°C/min, kept at the temperature and calcined for 12 hours, and then cooled down naturally to obtain an unreduced Ni/La ₂ O ₃ /Al ₂ O ₃ catalyst. 7. The device for producing methane from skid-mounted low-carbon hydrocarbons according to claim 1, characterized in that: the membrane used in the membrane separator is a polyimide hollow fiber membrane. 8. A process for producing methane from low-carbon hydrocarbons, which adopts the device for producing methane from skid-mounted low-carbon hydrocarbons described in any one of claims 1-7, comprising the following steps: Step 1, transporting low-carbon hydrocarbons to the desulfurizer bed inside the fine desulfurization reactor through the first feed pump for desulfurization treatment, so that the total sulfur content is less than 1ppm; Step 2: The desulfurized low-carbon hydrocarbons are mixed with the water delivered by the second feed pump and sent to the heating furnace for heating, and the heated mixture is sent to the conversion catalyst bed in the hydrocarbon-water conversion reactor The catalytic reaction is carried out on the layer, and the reaction is carried out under adiabatic conditions to obtain synthesis gas containing methane, carbon monoxide, carbon dioxide and hydrogen; In step 3, the synthesis gas is cooled by the first heat exchanger and transported to the methanation catalyst bed in the deep methanation reactor for catalytic reaction, and further catalytic conversion of carbon monoxide, carbon dioxide and hydrogen in the synthesis gas into methane is obtained. A mixture of methane and tail gas; Step 4, transporting the mixed gas to the gas-liquid separator for dehydration after being cooled by the second heat exchanger; Step 5, the dehydrated mixed gas is sent to the membrane separator for further separation of methane gas and tail gas, the methane gas is sent to the methane storage tank, and the tail gas is sent to the heating furnace to burn and recover heat. 9. The process for producing methane from low-carbon hydrocarbons according to claim 8, characterized in that: the temperature of the catalytic reaction in the hydrocarbon-water conversion reactor is 350-550°C, the pressure is from normal pressure to 6MPa, and the carbon space velocity 300-3000h ^-1 , the water-carbon ratio is (1-4):1; Preferably, the temperature of the catalytic reaction in the deep methanation reactor is 240-650°C, the pressure is normal pressure to 6MPa, the carbon space velocity is 1000-3000h ^-1 , and the water-to-carbon ratio is (1-4):1; Preferably, the temperature of the synthesis gas is 250-300° C. after the first heat exchanger lowers the temperature. 10. The process for producing methane from low-carbon hydrocarbons according to claim 8, characterized in that: the low-carbon hydrocarbons are C ₄ -C ₁₀ light saturated hydrocarbons; preferably, the low-carbon hydrocarbons include oilfield gas, A combination of one or more of liquefied petroleum gas and naphtha.