CN106590754B

CN106590754B - Method for preparing synthetic oil by taking coal and refinery dry gas as raw materials

Info

Publication number: CN106590754B
Application number: CN201510684060.4A
Authority: CN
Inventors: 晋超; 吴玉; 夏国富; 张荣俊; 孙霞; 侯朝鹏; 李明丰; 杨清河
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2015-10-20
Filing date: 2015-10-20
Publication date: 2020-03-24
Anticipated expiration: 2035-10-20
Also published as: CN106590754A

Abstract

The invention relates to a method for preparing synthetic oil by taking coal and refinery dry gas as raw materials, wherein the method comprises the following steps: 1) preparing coal powder and water into coal water slurry; 2) carrying out high-temperature gasification reaction on the coal water slurry and oxygen to prepare coal gasification crude synthesis gas; 3) purifying the coal gasification crude synthesis gas to obtain purified synthesis gas and carbon dioxide gas; 4) enabling the purified synthesis gas to undergo a Fischer-Tropsch synthesis reaction under the condition of mainly producing synthetic oil, and separating the obtained mixture to obtain a material flow containing the synthetic oil, carbon dioxide and methane; 5) separating refinery dry gas to separate out methane; 6) carrying out dry methane reforming reaction on the carbon dioxide obtained in the step 3) and/or the step 4) and the methane obtained in the step 5) or the methane obtained in the step 4) and the step 5). The method for preparing olefin by taking coal and refinery dry gas as raw materials can reduce the emission of greenhouse gas and obviously improve the resource and energy utilization rate of the whole process.

Description

Method for preparing synthetic oil by taking coal and refinery dry gas as raw materials

Technical Field

The invention relates to a method for preparing synthetic oil by taking coal and refinery dry gas as raw materials.

Background

The energy sources in China are in the resource distribution situation of rich coal, much natural gas and oil shortage, the indirect conversion of coal-based or natural gas into clean and efficient liquid fuel through Fischer-Tropsch (F-T) synthesis is an important aspect of reasonably utilizing resources, and a main technical approach for relieving the contradiction between supply and demand of petroleum in China. The process for directly preparing clean oil from coal by synthetic gas includes such steps as converting coal or natural gas to synthetic gas (CO and H)₂) And then directly preparing the liquid fuel through F-T synthesis. The most important advantage of the synthetic oil prepared by F-T synthesis is that the synthetic oil does not contain non-ideal components such as sulfur, nitrogen, aromatic hydrocarbon and the like, belongs to clean fuel, and completely conforms to the strict requirements and increasingly harsh environmental regulations of modern engines. Currently, iron-based catalysts are generally used in industry, and slurry bed or fixed bed processes are adopted and connected in series with hydrocracking units to crack the high-carbon hydrocarbon-wax product into related liquid fuels and chemicals such as gasoline, diesel oil or lubricating oil. The technological process for preparing the synthetic oil by the process is shown in a figure 1, and the main problems are that: 1. the energy consumption is high, and the utilization rate of carbon atoms is low; 2. the emission amount of carbon dioxide is 5-6 times of that of the traditional petroleum route; 3. the Fischer-Tropsch synthesis product distribution is limited by an Anderson-Schulz-Flory rule (the molar distribution of chain growth decreasing according to indexes), and is limited by the generation of a large amount of methane and carbon dioxide caused by strong exothermicity of reaction, so that the overall energy efficiency of the process is low, and the industrial process of the F-T synthesis process is seriously influenced. The F-T synthesis process uses a large amount of cooling water and external sewage to ensure that the water consumption is high. Therefore, there is a need to optimize the fischer-tropsch process and select a system that is energy efficient and reduces greenhouse gas emissions.

The by-product dry gas of refinery mainly comprises catalytic cracking dry gas, coking dry gas, reforming dry gas, hydrocracking dry gas, non-condensable gas of atmospheric and vacuum distillation unit, and mainly comprises H₂(30-50%), methane (20-40%), CO (C0.5-5％)、N₂(7-15％)、CO₂(1-7%), hydrocarbons (15-30%), etc. However, at present, the dry gas of the refinery is usually sent into a gas pipe network to be used as fuel gas, and some dry gas is even put into a torch to be burnt, which is waste of resources. At present, a coal chemical industry process based on coal gasification and a methane dry reforming process (DRM process) based on synthesis gas production and hydrogen production are mutually independent, and in consideration of the symbiotic relationship of products of Fischer-Tropsch synthesis and the methane dry reforming process and increasingly severe entrance threshold of coal chemical industry production, the coal chemical industry has to comprehensively consider the problems of reducing energy consumption, improving energy utilization rate, controlling pollution and the like. The F-T synthesis process and the DRM process can improve the overall energy efficiency from 36% to 52%, and reduce carbon dioxide discharged by one ton of synthetic oil from 6.0 tons to 1.6 tons, so that the problems of high energy consumption, low carbon utilization rate, serious environmental pollution and the like can be solved by combining the F-T synthesis process and the DRM process.

At present, the invention of combining methane dry reforming with Fischer-Tropsch synthesis to produce synthetic oil does not exist.

Disclosure of Invention

In order to overcome the defects, the invention provides a method for preparing synthetic oil by taking coal and refinery dry gas as raw materials.

In order to achieve the above object, the present invention provides a method for preparing synthetic oil from coal and refinery dry gas, comprising the steps of:

1) preparing coal powder and water into coal water slurry;

2) carrying out high-temperature gasification reaction on the coal water slurry and oxygen to prepare coal gasification crude synthesis gas;

3) purifying the coal gasification crude synthesis gas to obtain purified synthesis gas and carbon dioxide gas;

4) enabling the purified synthesis gas to undergo a Fischer-Tropsch synthesis reaction under the condition of mainly producing synthetic oil, and separating the obtained mixture to obtain a material flow containing the synthetic oil, carbon dioxide and methane;

5) separating refinery dry gas to separate out methane;

6) carrying out dry methane reforming reaction on the carbon dioxide obtained in the step 3) and/or the step 4) and the methane obtained in the step 5) or the methane obtained in the step 4) and the step 5).

The invention combines the coal-to-synthetic oil process, the refinery dry gas separation process and the methane dry reforming process to simultaneously utilize two greenhouse gases of carbon dioxide and methane, so that the greenhouse gases are converted into products with high added values, the greenhouse gas emission is reduced, and the resource and energy utilization rate of the whole process is obviously improved; in addition, the invention integrates the coal gasification process with strong heat release and the methane dry reforming reaction with strong heat absorption, so that the heat released by the former is provided for the latter. Specifically, the FTO process and the DRM process can improve the overall energy efficiency from 35% to 55%, reduce carbon dioxide discharged by synthetic oil from 6.2 tons to 1.4 tons and reduce the carbon dioxide by about 77%, so that the problems of high energy consumption, low carbon utilization rate, serious environmental pollution and the like can be solved by combining the FTO process and the DRM process; meanwhile, in the process of preparing synthetic oil by taking coal and refinery dry gas as raw materials, the supported catalyst for Fischer-Tropsch synthesis reaction is combined on the basis of the method provided by the invention, so that the obtained carbon monoxide has high conversion rate and the selectivity of the isomerized diesel oil is high, and the industrial popularization is facilitated.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic diagram of a conventional process for preparing synthetic oil from coal through synthetic gas;

FIG. 2 is a schematic diagram of a coal via syngas combined methane dry reforming system in accordance with a preferred embodiment of the present invention;

FIG. 3 is a schematic diagram of a coal via syngas combined methane dry reforming system in accordance with another preferred embodiment of the present invention;

FIG. 4 is a schematic diagram of a coal via syngas combined methane dry reforming system according to yet another preferred embodiment of the present invention;

FIG. 5 is a schematic diagram of a coal through syngas combined methane dry reforming system according to yet another preferred embodiment of the present invention.

Description of the reference numerals

I coal water slurry preparation unit A pulverized coal

II coal gasification unit B water

III Water gas shift Unit C coal Water slurry

IV Synthesis gas purification Unit D oxygen

E coal gasification crude synthesis gas of V Fischer-Tropsch synthesis unit

VI synthetic oil separation unit F-converted crude synthetic gas

VII methane Dry reforming Unit G methane

VIII refinery Dry gas separation Unit H carbon dioxide

J purified synthesis gas K synthetic oil

L refinery dry gas M sulfide

Methane separated from dry gas of N Fischer-Tropsch reaction product P refinery

Q refinery dry gas separated hydrogen U methane dry reforming reaction obtained synthesis gas

Y unreacted synthesis gas Z purge gas

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The invention provides a method for preparing synthetic oil by taking coal and refinery dry gas as raw materials, which is characterized by comprising the following steps of:

1) preparing coal powder A and water B into coal water slurry C;

2) carrying out high-temperature gasification reaction on the coal water slurry C and oxygen D to prepare coal gasification crude synthesis gas E;

3) purifying the coal gasification crude synthesis gas E to obtain purified synthesis gas J and carbon dioxide gas H;

4) carrying out Fischer-Tropsch synthesis reaction on the purified synthesis gas J, and separating the obtained mixture to obtain a material flow containing synthetic oil K, carbon dioxide H and methane G;

5) separating refinery dry gas L to separate out methane P;

6) carrying out dry methane reforming reaction on the carbon dioxide H obtained in the step 3) and/or the step 4) and the methane obtained in the step 4) and the step 5).

The equipment used in step 1) is not particularly limited in the present invention, as long as the pulverized coal a and the water B can be made into the coal water slurry C, and preferably, the operation can be performed in the coal water slurry preparation unit I in the system shown in fig. 2 to 5. The conditions for producing the coal-water slurry C are not particularly limited in the present invention, and for example, the pulverized coal A can be obtained by pulverizing and sieving solid raw material coal conventionally used in the art. The particle size of the pulverized coal A is preferably 5mm to 50 mm. The weight ratio of the pulverized coal A to the water B is preferably 1: 0.2-0.5. The pulverized coal A can be various pulverized coals suitable for the existing coal water slurry liquefaction process, and can be one or more of anthracite, lean smoke, lean coal, coking coal, fat coal, 1/3 coking coal, gas fat coal, gas coal, 1/2 medium-bonded coal, weak-bonded coal, non-bonded coal, long-flame coal and lignite. Preferably, the pulverized coal is high-quality power coal with low ash content, low sulfur content, high volatile matter content, high ash melting point and high heat value in the coal, and particularly preferably the coal with the heat value of more than or equal to 6000cal/kg, the ash content of less than or equal to 10 percent and the sulfur content of less than or equal to 1 percent in the coal.

The equipment used in step 2) of the present invention is not particularly limited as long as it can gasify the coal water slurry C and the oxygen D at high temperature to obtain the coal gasification raw synthesis gas E, and preferably, the gasification can be performed in the coal gasification unit II in the system shown in fig. 2 to 5, preferably, the reaction furnace temperature of the coal gasification unit II can be 1200-.

In the present invention, all the pressures used are absolute pressures.

The equipment used in step 3) of the present invention is not particularly limited, as long as the coal gasification raw synthesis gas E can be purified to remove acid gases and sulfides M in the raw synthesis gas E to obtain a purified synthesis gas J and a carbon dioxide gas H, wherein the synthesis gas is a mixed gas of carbon monoxide and hydrogen. This may preferably be carried out in the synthesis gas purification unit IV in a system as shown in fig. 2-5, and the resulting purified synthesis gas J may have a hydrogen to carbon monoxide molar ratio of 0.8-2.5:1, preferably 0.9-1.2: 1. Purification by removing CO, for example, by low-temperature methanol washing (Rectisol method)₂、H₂S, COS, HCN, and NH₃And the like. High concentration of H₂S gas enters a secondary Claus conversion process for sulfur recovery; CO is generated during methanol regeneration₂And desorbing the mixture to be used as dry reforming raw material of methane.

The apparatus used in step 4) is not particularly limited in the present invention, and may be any apparatus conventionally used in the art for Fischer-Tropsch synthesis reaction, for example, the step may be carried out in a Fischer-Tropsch synthesis unit V in a system as shown in FIGS. 2 to 5. The conditions of the Fischer-Tropsch reaction are not particularly limited in the present invention, and for example, the Fischer-Tropsch synthesis reaction conditions may be: the reaction temperature is 240-320 ℃, and preferably 280-300 ℃; the reaction pressure is 0.5-2.5MPa, preferably 0.8-1.8 MPa; the gas space velocity can be 2000-50000h^-1Preferably 2000-^-1More preferably 2000-^-1(ii) a In a preferred case, the Fischer-Tropsch synthesis reaction can be carried out in a fixed bed reactor. The catalyst for the Fischer-Tropsch reaction can be Fe/Al₂O₃A base catalyst.

The Fischer-Tropsch synthesis reaction is a production process for producing low-carbon synthetic oil, low-carbon alkane and oil phase products, and simultaneously by-products of methane and carbon dioxide are produced.

In the present invention, the synthetic oil is C₉-C₁₈A diesel component.

According to the method provided by the invention, in the step (4), the catalyst used in the Fischer-Tropsch synthesis reaction is not particularly limited, and can be selected conventionally in the field, for example, an iron-based catalyst or a cobalt-based catalyst can be used. In a preferred aspect, the present invention uses a supported catalyst comprising an alumina carrier containing a modifier and an active component supported on the alumina carrier containing the modifier, wherein the modifier is a group IVB metal component or a group IVB metal component and an alkali metal component and/or an alkaline earth metal component, and the active component is a group VIII metal component.

In the above supported catalyst, the carrier is a gamma-alumina containing a modifier, and the CO of the gamma-alumina containing a modifier is higher than that of a gamma-alumina not containing a modifier₂TPD desorption of CO at a temperature higher than that of gamma-alumina without modifier₂TPD desorption temperature. Thus, in the present invention, the properties of the gamma-alumina before and after modification may be expressed as CO₂TPD characterization, CO₂TPD represents gamma-alumina vs. CO₂The high desorption temperature of the catalyst indicates that the gamma-alumina has strong alkalinity, which is beneficial to the desorption of diesel components and isomeric diesel. In CO₂In the TPD spectrogram, the appearance position of peak temperature and the area size of the peak indicate the alkalinity of the gamma-alumina, and CO₂The high desorption peak temperature and the large peak area indicate that the gamma-alumina has strong alkalinity and is beneficial to the desorption of diesel components. According to a preferred embodiment of the invention, the CO of the support according to the invention₂TPD with CO at 80-110 deg.C₂Desorption peak. Preferably, the peak area of the desorption peak is 1 to 3a.u (arbitrary units). In case the modifier is one of Zr, K and Mg, the CO of the support₂The TPD removal diagram also has another CO at 300-500, preferably 350-450 DEG C₂Desorption peak. Preferably, the other CO₂The peak area of the desorption peak is 0.5 to 2a.u (arbitrary units). And the existing carriers do not have the desorption peak.

Carrier CO in the invention₂TPD and the following catalysts CO-TPD were measured on-line by using a Michelson chemisorption instrument and an OMistar mass spectrometer. Carrier CO₂TPD signals of nuclear-to-proton ratio 44, catalyst CO, recorded by mass spectrometerTPD signals of nuclear-to-cytoplasmic ratio 28 are recorded by the mass spectrometer.

In the above supported catalyst, the modifier-containing γ -alumina can be prepared by supporting a modifier on γ -alumina. The gamma-alumina is not particularly limited in the present invention, and may be, for example, commercially available gamma-alumina, and the parameters (such as specific surface area, pore volume, average pore diameter, particle size distribution, etc.) related to the commercially available gamma-alumina are not particularly limited in the present invention, and preferably, the commercially available gamma-alumina has a specific surface area of 110-250 m-²Per gram, preferably 120-200 m²Per gram; the pore volume is 0.65-0.9 ml/g, preferably 0.7-0.8 ml/g; the average pore diameter is 12 to 17.5 nm, preferably 13 to 17 nm. Preferably, the commercially available gamma-alumina has a particle size distribution of from 85 to 95%, preferably from 90 to 95%, of from 70 to 150 microns. In the present invention, the specific surface area, the pore volume and the average pore diameter are measured by a nitrogen adsorption method, specifically, by N₂The adsorption isotherm of the carrier was measured at a constant temperature of 77K, and then the specific surface area and pore volume were calculated according to the BET formula, and the average pore diameter was calculated according to the BJH method.

In the supported catalyst, the content of the active component is 5 to 70 wt%, preferably 8 to 50 wt%, and more preferably 10 to 30 wt%, in terms of metal element, based on the total amount of the catalyst; the content of the alumina carrier containing the modifier is 30-95 wt%, preferably 50-92 wt%, and more preferably 70-90 wt%.

Further, in the present invention, the content of the modifier is 1 to 10% by weight, preferably 2 to 8% by weight, in terms of metal element, based on the weight of the modifier-containing alumina support.

According to the supported catalyst provided by the invention, the modifier can be a group IVB metal component or a group IVB metal component and an alkali metal component and/or an alkaline earth metal component. The group IVB metal component is Zr and/or Ti, preferably Zr; the alkali metal component is one or more of Li, K and Na, preferably Li and/or K; the alkaline earth metal component is Mg and/or Ca, preferably Mg.

The method for supporting the modifier in the present invention is not particularly limited, and may be a method conventionally used in the art, and for example, an impregnation method or a coprecipitation method, preferably an impregnation method, may be used, and specifically includes immersing a γ -alumina support in an impregnation solution containing the modifier, followed by drying and calcination.

The impregnation method in the present invention is not particularly limited, and may be an equivalent-volume impregnation method or a saturation impregnation method. The conditions for impregnation are not particularly limited in the present invention, and for example, the conditions for impregnation generally include that the impregnation temperature may be 10 to 80 ℃, preferably 20 to 60 ℃; the impregnation time may be from 0.1 to 3h, preferably from 0.5 to 1 h.

In the process of supporting the modifier on the γ -alumina carrier, the drying method in the present invention is not particularly limited, and may be a method conventionally used in the art, for example, a method of drying by heating, and specific conditions include: the drying temperature may be 80-350 deg.C, preferably 100-300 deg.C, and the drying time may be 1-24 hours, preferably 2-12 hours.

In the process of supporting the modifier on the γ -alumina support, the method of calcination in the present invention is also not particularly limited as long as the modifier is converted into the corresponding oxide, and may be a method conventionally used in the art, for example, the method of calcination is a method of calcination in an air atmosphere, and the conditions of calcination include: the roasting temperature is 250-900 ℃, preferably 300-850 ℃, and more preferably 350-800 ℃; the calcination time is 0.5 to 12 hours, preferably 1 to 8 hours, and more preferably 2 to 6 hours.

In the above supported catalyst, wherein the active component may be a group VIII metal component, Fe and/or Co is preferred, and Fe is more preferred.

In the invention, the performance of the catalyst can be represented by CO-TPD (carbon monoxide-phosphorus detector), wherein the CO-TPD represents the desorption temperature of the reduced catalyst for CO at high temperature after adsorbing CO, and the higher the desorption temperature is, the higher the activity of the catalyst is, thus being beneficial to the generation of diesel components and isomerized diesel. In a CO-TPD spectrogram, the appearance position of peak temperature and the peak area indicate the strength of the CO dissociation capability of the catalyst, and the high CO desorption peak temperature and the large peak area indicate the strength of the CO dissociation capability of the catalyst, so that the selectivity of diesel components and isomerous diesel is favorably improved. The supported catalyst provided by the invention has a CO-TPD desorption temperature higher than that of the catalyst in the comparative example.

According to a preferred embodiment of the invention, the CO-TPD desorption diagram of the supported catalyst has a CO desorption peak at 490-560 ℃, preferably 500-555 ℃. Further preferably, the peak area of the CO desorption peak is 2.5-6a.u., preferably 3-5.5a.u. In the case that the modifier is one of Zr, K and Mg, the CO-TPD desorption diagram of the catalyst also has another CO desorption peak at 650 ℃ at 570-. Preferably, the peak area of the further CO desorption peak is from 0.9 to 2a.u. (arbitrary units).

According to a preferred embodiment of the present invention, the preparation method of the above supported catalyst provided by the present invention includes loading the active component on an alumina carrier containing a modifier, where the modifier is a group IVB metal component or a group IVB metal component and an alkali metal component and/or an alkaline earth metal component, and the active component is a group VIII metal component, and the loading method includes adsorbing an impregnation solution containing the active component on the alumina carrier containing the modifier, and drying and calcining sequentially after adsorption.

The method for supporting the active ingredient in the present invention is not particularly limited, and may be a method conventionally used in the art, and for example, an impregnation method or a coprecipitation method, preferably an impregnation method, may be an equivalent-volume impregnation method, may also be a saturated impregnation method, and preferably a saturated impregnation method, may be used.

The drying and baking methods are not particularly limited in the present invention, and the methods conventionally used in the art can be adopted, as described above, and are not described in detail herein.

The gamma-alumina containing modifier and the preparation method of the gamma-alumina are described above, and are not described in detail herein.

In the present invention, the impregnation solution can be prepared by dissolving soluble salts of the respective components in a solvent. The soluble salt may be, for example, a nitrate, a chloride, or the like.

The invention also provides the application of the supported catalyst in the reaction of preparing the heterogeneous diesel oil from the synthesis gas.

The supported catalyst provided by the invention is applied to the reaction for preparing the isomerous diesel oil from the synthesis gas, and the active component needs to be subjected to reduction activation in the presence of hydrogen, and the conditions of the reduction activation are not particularly limited in the invention, and can be, for example: the reduction temperature is 100-800 ℃, preferably 200-600 ℃, and more preferably 300-500 ℃; the reduction time is 0.5 to 72 hours, preferably 1 to 36 hours, more preferably 2 to 24 hours; the reduction activation may be carried out in a pure hydrogen atmosphere or in a mixed atmosphere of hydrogen and an inert gas, for example, in a mixed atmosphere of hydrogen and nitrogen and/or argon, and the hydrogen pressure is 0.1 to 4MPa, preferably 0.1 to 2 MPa.

The equipment used in step 5) of the present invention is not particularly limited, and may be equipment conventionally used in the art for refinery dry gas separation, for example, this step may be performed in the refinery dry gas separation unit VIII in the system shown in fig. 2 to 5. In the present invention, the conditions for separating the refinery dry gas are not particularly limited as long as the separation of hydrogen from methane can be achieved, and for example, the separation of the refinery dry gas is performed by a low-temperature condensation method. The conditions for the refinery dry gas separation may include: the temperature of the separation can be-150 ℃ to-200 ℃.

Further preferably, the hydrogen Q in the separated refinery dry gas is fed to step 3) and purified together with the coal gasification raw synthesis gas E.

The refinery dry gas L mainly contains catalytic cracking dry gas, coking dry gas, reforming dry gas, hydrocracking dry gas, non-condensable gas of an atmospheric and vacuum device and the like, and the main components of the refinery dry gas L comprise hydrogen (30-50%), methane (20-40%), carbon monoxide (0.5-5%), nitrogen (7-15%), carbon dioxide (1-7%), hydrocarbons (15-30%) and the like.

According to one embodiment of the invention, the flow ratio of the raw coal to the refinery dry gas L is 1:2 to 6, preferably 1:3 to 5. With the above proportions, the coal gasification raw synthesis gas E can be produced with a molar ratio of hydrogen to carbon monoxide suitable for the Fischer-Tropsch reaction and/or with a ratio of carbon dioxide to methane suitable for the dry reforming reaction of methane.

The apparatus used in step 6) of the present invention is not particularly limited, and may be an apparatus conventionally used in the art for carrying out a dry methane reforming reaction, for example, the step may be carried out in a dry methane reforming unit VII in a system as shown in fig. 2 to 5. The conditions of the dry methane reforming reaction are not particularly limited in the present invention, and for example, the conditions of the dry methane reforming reaction may include: the reaction temperature is 600 ℃ and 800 ℃, and the reaction pressure is 0.1-1.0 MPa. The catalyst can be a dry reforming catalyst for various methanes, such as Ni/Al₂O₃A supported catalyst. The molar ratio of the methane to the carbon dioxide can be 1:0.6-1.5, preferably 1:0.8-1.3, and the space velocity of the mixed gas can be 40000-^-1Preferably 60000-^-1。

In a preferable case, the carbon dioxide and the methane for performing the dry reforming reaction of the methane can be from the carbon dioxide H obtained in the step 3) and/or the step 4) and the methane obtained in the step 4) and the step 5), so that two greenhouse gases (carbon dioxide and methane) which seriously pollute the environment and are generated in the purification process of the coal gasification raw synthesis gas, the Fischer-Tropsch synthesis reaction process and the separation process of the refinery dry gas can be utilized, the environmental pollution is reduced, and the energy utilization rate of the whole process is improved.

According to the method provided by the invention, the synthesis gas U obtained by methane dry reforming reaction is preferably returned to the step 4) to carry out the Fischer-Tropsch synthesis reaction.

According to the method provided by the invention, the method preferably further comprises the steps of carrying out water gas shift on the raw synthesis gas E obtained in the step 2) to increase the molar ratio of hydrogen to carbon monoxide, and then carrying out purification on the obtained shifted raw synthesis gas E in the step 3). Preferably, the molar ratio of hydrogen to carbon monoxide of the raw synthesis gas E is 0.4-0.8:1, and the molar ratio of hydrogen to carbon monoxide of the synthesis gas J after water gas shift and synthesis gas purification is 0.9-1.2: 1. The apparatus used in the above-described water gas shift process of the present invention is not particularly limited, and may be an apparatus conventionally used in the art for performing water gas shift, for example, this step may be performed in the water gas shift unit III in a system as shown in fig. 3 or 5.

According to the method provided by the invention, in a preferable case, the method further comprises the step of enabling the raw synthesis gas E to serve as a heating medium to pass through a reactor preheating furnace of a methane dry reforming unit VII, then enter a water gas shift unit III to carry out water gas shift or directly carry out synthesis gas purification in a synthesis gas purification unit IV, so that the raw synthesis gas of a coal gasification unit with strong heat release is introduced into a methane dry reforming unit with strong heat absorption, and the heat energy utilization efficiency is improved.

According to the method provided by the invention, the method preferably further comprises separating the synthetic oil-containing stream obtained in the step 4) to obtain a synthetic oil K stream.

Preferably, the method provided by the invention further comprises returning a part of the unreacted synthesis gas Y to the Fischer-Tropsch synthesis unit V for Fischer-Tropsch synthesis reaction, and discharging the other part of the unreacted synthesis gas Y as purge gas Z obtained by separating the synthesis oil.

According to the method provided by the invention, the method preferably further comprises purifying the hydrogen Q obtained in the step 5) and the raw synthesis gas F obtained in the step 2) together to obtain a purified synthesis gas J.

According to a preferred embodiment of the invention, the method provided by the invention adopts the system and process shown in fig. 3, firstly, the pulverized coal A and the water B are conveyed into the water-coal slurry preparation unit I to prepare the water-coal slurry, then the prepared water-coal slurry C and the oxygen D are conveyed into the coal gasification unit II together to generate the coal gasification crude synthesis gas E, then the coal gasification crude synthesis gas E is taken as a heating medium to pass through a reactor preheating furnace of the methane dry reforming unit VII, after heat exchange, the coal gasification crude synthesis gas E is conveyed into the water-gas conversion unit III to adjust the molar ratio of hydrogen and carbon monoxide, and the synthesis gas purification unit IV removes acid gas and sulfide M to obtain purified synthesis gas J and carbon dioxide H, the purified synthesis gas J is conveyed into the Fischer-Tropsch synthesis unit V to carry out Fischer-Tropsch synthesis reaction to generate a material flow containing synthesis oil and carbon dioxide H and methane G, then the material flow containing synthesis oil generated by the Fischer-Tropsch synthesis reaction is, separating to obtain the synthetic oil K, the unreacted synthetic gas Y and the purge gas Z. And (3) taking the synthetic oil K as a product to enter a subsequent process, returning one part of the unreacted synthetic gas Y to the Fischer-Tropsch synthesis unit V for carrying out Fischer-Tropsch synthesis reaction, and discharging the other part of the unreacted synthetic gas Y serving as purge gas Z. The ratio of the return portion to the outward portion is preferably 95-98: 2-5. In addition, the system also comprises a refinery dry gas separation unit VIII and a methane dry reforming unit VII, wherein the refinery dry gas L is conveyed into the refinery dry gas separation unit VIII to generate methane P and hydrogen Q, carbon dioxide H generated by the Fischer-Tropsch synthesis unit V and the synthesis gas purification unit IV is conveyed into the methane dry reforming unit VII, the methane P generated by the refinery dry gas separation unit VIII and the methane G generated by the Fischer-Tropsch synthesis unit V are also conveyed into the methane dry reforming unit VII, so that the carbon dioxide and the methane react in the methane dry reforming unit VII to generate synthesis gas U, and the synthesis gas U generated by the methane dry reforming reaction and the purified synthesis gas J are conveyed to the Fischer-Tropsch synthesis unit V together to carry out Fischer-Tropsch synthesis reaction.

According to another preferred embodiment of the present invention, the present invention provides a process using the system and process shown in fig. 2, which differs from the system shown in fig. 3 in that the water gas shift unit is omitted and the molar ratio of synthesis gas hydrogen to carbon monoxide is adjusted by increasing the hydrogen separated in the refinery dry gas separation unit VIII.

According to another preferred embodiment of the invention, the method provided by the invention adopts the system and the process shown in fig. 5, and the system is different from the system shown in fig. 3 in that a hydrogen outlet is arranged on the refinery dry gas separation unit VIII, and hydrogen Q generated after the refinery dry gas L passes through the refinery dry gas separation unit VIII can be output through the hydrogen outlet, so that the hydrogen Q and the coal gasification crude synthesis gas E enter the water gas shift unit III together to adjust the molar ratio of hydrogen and carbon monoxide, so that the hydrogen Q meets the requirements of the fischer-tropsch synthesis reaction, and then enter the synthesis purification unit IV to be purified, thereby omitting the water gas shift process.

According to yet another preferred embodiment of the present invention, the present invention provides a process using the system and process shown in fig. 4, which differs from the system shown in fig. 5 in that the water gas shift unit is omitted and the molar ratio of synthesis gas hydrogen to carbon monoxide is adjusted by increasing the hydrogen separated in the refinery dry gas separation unit VIII.

By adopting the preferable mode and controlling the conditions of the steps within the preferable range, the weight flow ratio of the pulverized coal to the refinery dry gas is controlled to be 1: 1.5-4, the best comprehensive economic benefit can be obtained. For example, for a coal water slurry liquefaction device with the magnitude of 2000 tons/day, the flow rate of the raw material coal can be 200-.

The present invention will be described in detail below by way of examples.

In the following examples and comparative examples:

the specific surface area, pore volume and average pore diameter of the carrier were measured by nitrogen adsorption method, specifically by N₂The adsorption isotherm of the carrier was measured at a constant temperature of 77K, and then the specific surface area and pore volume were calculated according to the BET formula, and the average pore size distribution was calculated according to the BJH method.

The contents of the active component and the modifier were measured by X-ray fluorescence spectrometry RIPP 132-90 (petrochemical analysis (RIPP test method), Yanlegze, Kanjin, Wuvinui, science publishers, first edition 9 months 1990, p 371-.

In the following examples and comparative examples:

conversion of CO (X)_CO)、CH₄Selectivity of (2)

CO₂Selectivity (S) of_CO2) Selectivity of diesel oil component (S)_{Diesel fuel component}) Selectivity of isomerous diesel oil (S)_{Heterogeneous diesel oil}) And C₅Above (C)₅₊) Selectivity of hydrocarbons

Respectively calculated by the following formula:

wherein, V₁、V₂Respectively representing the volume of feed gas entering the reaction system and the volume of tail gas flowing out of the reaction system in a certain time period under a standard condition; c. C_1,CO、c_2,CORespectively representing the molar contents of CO in the raw material gas and the tail gas. n is_conIn terms of the number of moles of CO participating in the reaction,

to produce CO₂The number of moles of (a) to (b),

to generate CH₄Mole number of (2), n_{Diesel fuel component}In order to obtain the molar amount of the diesel fuel component, n_{Heterogeneous diesel oil}In order to obtain the mole number of the isomerate diesel oil,

to generate CH₄、C₂Hydrocarbons, C₃Hydrocarbons and C₄The sum of the moles of hydrocarbons.

In the following examples, the carrier CO₂And the-TPD and the catalyst CO-TPD are detected by a Michelia chemisorption instrument and an OMistar mass spectrum on line. Carrier CO₂TPD records the signal of the nuclear to cytoplasmic ratio 44 from the mass spectrometer and catalyst CO-TPD records the signal of the nuclear to cytoplasmic ratio 28 from the mass spectrometer. Carrier CO₂The appearance position of peak temperature and the peak area size in a TPD spectrogram indicate the alkalinity of the carrier, and CO₂The high desorption peak temperature and the large peak area indicate that the carrier is strong in alkalinity, which is beneficial to the desorption of diesel components and isomeric diesel; the performance of the catalyst is characterized by CO-TPD, the appearance position of peak temperature and the peak area in a spectrogram of the CO-TPD show that the CO dissociation capability of the catalyst is strong and weak, the CO desorption peak temperature is high, and the peak area is large, so that the CO dissociation capability of the catalyst is strong, and the selectivity of diesel components and heterogeneous diesel is favorably improved.

Example 1

This example illustrates the method of the present invention.

(1) Construction of the System

The coal water slurry preparation unit I, the coal gasification unit II, the water gas conversion unit III, the synthesis gas purification unit IV, the Fischer-Tropsch synthesis unit V and the synthesis oil separation unit VI are sequentially connected, a carbon dioxide outlet of the Fischer-Tropsch synthesis unit V and a carbon dioxide outlet of the synthesis gas purification unit IV are communicated with a carbon dioxide inlet of the methane dry reforming unit VII through conveying pipelines, a methane outlet of the refinery dry gas separation unit VIII and a methane outlet of the Fischer-Tropsch synthesis unit V are communicated with a methane inlet of the methane dry reforming unit VII, and a synthesis gas outlet of the methane dry reforming unit VII is communicated with a synthesis gas inlet of the Fischer-Tropsch synthesis unit V through conveying pipelines. The heat supply inlet of the reactor preheating furnace of the methane dry reforming unit VII is provided with two inlets which are respectively connected with the coal gasification crude synthesis gas outlet of the coal gasification unit II. The water gas shift reaction with strong heat release supplies heat for a preheating furnace of a methane dry reforming unit VII with strong heat absorption reaction; the high-temperature raw synthesis gas E of the water gas shift unit III firstly enters a preheating furnace of a methane dry reforming reactor and then enters a synthesis gas purification unit IV. Flow control valves (not shown) are provided in each of the transfer pipes to obtain a system as shown in fig. 3.

(2) Preparation of catalyst for Fischer-Tropsch synthesis reaction

a. Preparation of the support

28.3g of zirconium nitrate pentahydrate is weighed and dissolved in 120g of deionized waterPreparing modified zirconium solution, adding 100.0g of gamma-Al of 40-60 meshes₂O₃Uniformly stirring the carrier for 5min, standing for 2h, drying in an oven at 120 ℃ for 5h, and roasting at 400 ℃ for 3h to obtain a modified carrier Z1 with Zr content of 6 wt% based on the weight of the modified carrier and calculated on metal elements, wherein the modified carrier Z1 contains CO₂The desorption peak temperatures and peak areas are shown in Table 1.

b. Preparation of the catalyst

17.3g of ferric ammonium citrate is dissolved in 12.6ml of deionized water to obtain ferric ammonium citrate solution, and the ferric ammonium citrate solution is heated, stirred and mixed uniformly in a water bath at 50 ℃ to obtain impregnation liquid. Taking the modified gamma-Al₂O₃Dispersing 24g of carrier into the impregnation liquid, stirring at room temperature for 1h, placing in a 120 ℃ oven for drying for 5h, and then roasting at 400 ℃ for 3h to obtain a catalyst A1, wherein the composition of A1 is 20% Fe/6% Zr-Al₂O₃The CO desorption peak temperature and the desorption peak area are shown in Table 2.

(3) Preparation of synthetic oils

After being crushed and screened, solid raw material coal (brown coal produced by inner Mongolia) and water B of 360t/h are conveyed together with the water B of 360t/h at the flow rate of 360t/h into a water-coal-slurry preparation unit I to prepare water-coal-slurry C, and the water-coal-slurry C and oxygen D are generated into crude synthesis gas E mainly comprising carbon monoxide and hydrogen in a coal gasification unit II under the conditions of 1300 ℃ and 3.0 MPa; the crude synthesis gas E firstly passes through a reactor preheating furnace of a methane dry reforming unit VII, the reactor preheating furnace is enabled to reach 600 ℃ required by preheating, then the reactor preheating furnace enters a water gas conversion unit III to adjust the molar ratio of hydrogen to carbon monoxide to about 1, and a synthesis gas purification unit IV removes acid gas and sulfide M to obtain clean purified synthesis gas J, wherein the molar ratio of hydrogen to carbon monoxide is 0.99: 1; conveying the purified synthesis gas J into a fixed bed reactor of a Fischer-Tropsch synthesis unit V for carrying out Fischer-Tropsch synthesis reaction, wherein the reaction temperature is 290 ℃, the pressure is 1.0MPa, the catalyst is the catalyst A1 prepared in the step (2), and the gas space velocity is 4000h^-1Obtaining Fischer-Tropsch synthesis products, sending the products into a synthesis oil separation unit VI, firstly carrying out gas-liquid separation on the products in the synthesis oil separation unit VI to obtain oil products and product gas, purifying the product gas by acid gas to remove carbon dioxide,then the mixture enters cryogenic separation (-105 ℃) to obtain synthetic oil K, a methane product (-161 ℃) and unreacted synthetic gas Y. The unreacted synthesis gas Y enters a Fischer-Tropsch synthesis reactor for re-reaction according to the proportion of 98 percent after being separated, and 2 percent of the unreacted synthesis gas is used as purge gas Z. The composition of the product obtained after 50h of reaction was analyzed by on-line gas chromatography and the results are shown in table 4.

In addition, after impurities such as oxygen, hydrogen sulfide and the like are removed from the refinery dry gas L (the components are shown in Table 3), the refinery dry gas L is conveyed into a refinery dry gas separation unit VIII at a flow rate of 600t/h, wherein the components of the refinery dry gas L are shown in Table 3, the carbon dioxide is firstly separated from the refinery dry gas L at the temperature of minus 80 ℃ through cryogenic separation, the residual gas is continuously cooled to minus 200 ℃, and methane P (-170 ℃), carbon monoxide (-190 ℃), nitrogen (-196 ℃) and hydrogen Q are sequentially separated.

Conveying methane P generated in the refinery dry gas separation process, carbon dioxide H generated in the synthesis gas purification unit IV, and carbon dioxide H and methane G generated in the Fischer-Tropsch synthesis process to a methane dry reforming unit VII at the temperature of 750 ℃, the pressure of 0.1MPa and the catalyst of Ni/Al₂O₃And (2) generating a synthesis gas U under the condition of a supported catalyst (the supported amount of nickel is 8 wt%, based on the weight of the catalyst), wherein the molar ratio of hydrogen to carbon monoxide of the synthesis gas U is 0.99:1, and then conveying the synthesis gas U generated by dry reforming of methane and the purified synthesis gas J to a Fischer-Tropsch synthesis unit V for Fischer-Tropsch synthesis reaction.

The results are shown in Table 5.

Example 2

This example illustrates the method of the present invention.

(1) Construction of the System

The system was constructed in the same manner as in example 1.

(2) Preparation of catalyst for Fischer-Tropsch synthesis reaction

a. Preparation of the support

14.2g of pentahydrate zirconium nitrate is weighed and dissolved in 120g of deionized water to prepare modified zirconium solution, and 100.0g of gamma-Al of 40-60 meshes is added into the modified zirconium solution₂O₃Adding into carrier, stirring for 5min, standing for 2 hr, drying in oven at 200 deg.CDrying for 3h, and calcining at 800 deg.C for 1h to obtain modified carrier Z2 with Zr content of 3 wt% calculated by metal element and based on the weight of the modified carrier, and CO₂The desorption peak temperatures and peak areas are shown in Table 1.

b. Preparation of the catalyst

17.3g of ferric ammonium citrate is dissolved in 12.6ml of deionized water to obtain ferric ammonium citrate solution, and the ferric ammonium citrate solution is heated, stirred and mixed uniformly in a water bath at 50 ℃ to obtain impregnation liquid. Taking the modified gamma-Al₂O₃Dispersing 24g of carrier into the impregnation liquid, stirring at room temperature for 1h, drying in an oven at 200 ℃ for 3h, and then calcining at 800 ℃ for 1h to obtain a catalyst A2, wherein the composition of A2 is 20% Fe/3% Zr-Al₂O₃The CO desorption peak temperature and the desorption peak area are shown in Table 2.

(3) Preparation of synthetic oils

A synthetic oil was prepared in the same manner as in example 1, except that the catalyst used in the Fischer-Tropsch synthesis reaction was the catalyst A2 prepared in step (2).

The results are shown in tables 4 and 5.

Example 3

This example illustrates the method of the present invention.

(1) Construction of the System

The system was constructed in the same manner as in example 1.

(2) Preparation of catalyst for Fischer-Tropsch synthesis reaction

a. Preparation of the support

37.7g of pentahydrate zirconium nitrate is weighed and dissolved in 120g of deionized water to prepare modified zirconium solution, and the modified zirconium solution is added into 100.0g of gamma-Al of 40-60 meshes₂O₃Uniformly stirring the carrier for 5min, standing for 2h, drying in an oven at 300 ℃ for 2h, and roasting at 500 ℃ for 6h to obtain a modified carrier Z3 with Zr content of 8 wt% and CO content based on the weight of the modified carrier and calculated on metal elements₂The desorption peak temperatures and peak areas are shown in Table 1.

b. Preparation of the catalyst

Dissolving 17.3g ferric ammonium citrate in 12.6ml deionized water to obtain ferric ammonium citrate solution at 50 deg.CHeating in water bath, stirring, and mixing to obtain the soaking solution. Taking the modified gamma-Al₂O₃Dispersing 24g of carrier into the impregnation liquid, stirring at room temperature for 1h, placing in a 300 ℃ oven for drying for 2h, and then roasting at 500 ℃ for 6h to obtain a catalyst A3, wherein the composition of A3 is 20% Fe/8% Zr-Al₂O₃The CO desorption peak temperature and the desorption peak area are shown in Table 2.

(3) Preparation of synthetic oils

A synthetic oil was prepared in the same manner as in example 1, except that the catalyst used in the Fischer-Tropsch synthesis reaction was the catalyst A3 prepared in step (2).

The results are shown in tables 4 and 5.

Example 4

This example illustrates the method of the present invention.

(1) Construction of the System

The system was constructed in the same manner as in example 1.

(2) Preparation of catalyst for Fischer-Tropsch synthesis reaction

Adopts an immersion method to prepare 100-300 mesh gamma-Al which is sold in the market₂O₃Iron element is loaded on a carrier Z4(Sasol product) to obtain an iron-based catalyst A4. Catalyst A4 had a composition of 18% Fe/Al based on the metal element and based on the weight of the catalyst prepared₂O₃。

(3) Preparation of synthetic oils

α -olefins were prepared by the same method as in example 1, except that the catalyst used in the Fischer-Tropsch synthesis was catalyst A4 prepared in step (2).

The results are shown in tables 4 and 5.

Example 5

This example illustrates the method of the present invention.

(1) Construction of the System

The coal water slurry preparation unit I, the coal gasification unit II, the synthesis gas purification unit IV, the Fischer-Tropsch synthesis unit V and the synthesis oil separation unit VI are sequentially connected, a carbon dioxide outlet of the Fischer-Tropsch synthesis unit V and a carbon dioxide outlet of the synthesis gas purification unit IV are communicated with a carbon dioxide inlet of the methane dry reforming unit VII through conveying pipelines, a methane outlet of the refinery dry gas separation unit VIII and a methane outlet of the Fischer-Tropsch synthesis unit V are communicated with a methane inlet of the methane dry reforming unit VII through pipelines, and a synthesis gas outlet of the methane dry reforming unit VII and a synthesis gas inlet of the Fischer-Tropsch synthesis unit V are communicated through conveying pipelines. The heat supply inlet of the reactor preheating furnace of the methane dry reforming unit VII is provided with two inlets which are respectively connected with the coal gasification crude synthesis gas outlet of the coal gasification unit II. The water gas shift reaction with strong heat release supplies heat for a preheating furnace of a methane dry reforming unit VII with strong heat absorption reaction; the high-temperature raw synthesis gas E of the water gas shift unit III firstly enters a preheating furnace of a methane dry reforming reactor and then enters a synthesis gas purification unit IV. In addition, the refinery dry gas separation unit VIII is provided with a hydrogen outlet which is communicated with the crude synthesis gas inlet of the synthesis gas purification unit IV through a pipeline. Flow control valves (not shown) are provided in each of the transfer pipes to obtain a system as shown in fig. 4.

(2) Preparation of catalyst for Fischer-Tropsch synthesis reaction

Catalyst A1 was obtained by the same procedure as in example 1.

(3) Preparation of synthetic oils

After being crushed and sieved, solid raw material coal (anthracite produced by Shanxi university) and water B are conveyed into a coal water slurry preparation unit I together with the flow of 280t/h to prepare coal water slurry C, and the coal water slurry C and oxygen D generate crude synthesis gas E mainly comprising carbon monoxide and hydrogen in a coal gasification unit II under the conditions of 1200 ℃ and 2.8 MPa; the raw synthesis gas E firstly passes through a reactor preheating furnace of a methane dry reforming unit VII to reach the preheating temperature of 600 ℃, and then enters a synthesis gas purification unit IV (under the purification condition, the raw synthesis gas is subjected to CO removal by a low-temperature methanol washing method (Rectisol method)₂、H₂S, COS, HCN, and NH₃And the like. High concentration of H₂S gas enters a secondary Claus conversion process for sulfur recovery; CO is generated during methanol regeneration₂Resolved as dry methane reforming feedstock. ) After removing acid gas and sulfide M, obtaining clean purified synthesis gas J, wherein the molar ratio of hydrogen to carbon monoxide is 0.9: 1; will purify the mixtureConveying the formed gas J into a fixed bed reactor of a Fischer-Tropsch synthesis unit V for carrying out Fischer-Tropsch synthesis reaction, wherein the reaction temperature is 280 ℃, the pressure is 0.8Mpa, the catalyst is the catalyst A1 prepared in the step (2), and the gas space velocity is 2000h^-1And then the obtained product containing the synthetic oil is sent into a synthetic oil separation unit VI through a reactor preheating furnace of a methane dry reforming unit VII, the product in the synthetic oil separation unit VI is subjected to gas-liquid separation to obtain an oil product and a product gas, the product gas is purified by acid gas to remove carbon dioxide, and then the product gas is subjected to cryogenic separation (-105 ℃) to obtain synthetic oil K, a methane product (-161 ℃) and unreacted synthetic gas Y. And separating unreacted synthesis gas Y, then entering the Fischer-Tropsch synthesis reactor according to the proportion of 95% for re-reaction, and taking 5% of the unreacted synthesis gas as purge gas Z. The composition of the product obtained after 50h of reaction was analyzed by on-line gas chromatography and the results are shown in table 4.

In addition, after impurities such as oxygen, hydrogen sulfide and the like are removed from the refinery dry gas L (the components are shown in Table 3), the refinery dry gas L is conveyed into a refinery dry gas separation unit VIII at a flow rate of 800t/h, wherein the components of the refinery dry gas L are shown in Table 3, the carbon dioxide is firstly separated from the refinery dry gas L at the temperature of minus 80 ℃ through cryogenic separation, the residual gas is continuously cooled to minus 200 ℃, and methane P (-170 ℃), carbon monoxide (-190 ℃), nitrogen (-196 ℃) and hydrogen Q are sequentially separated.

Conveying methane P generated in the refinery dry gas separation process, carbon dioxide H generated in the synthesis gas purification unit IV, and carbon dioxide H and methane G generated in the Fischer-Tropsch synthesis process to a methane dry reforming unit VII at a temperature of 600 ℃, a pressure of 0.5Mpa and a catalyst of Ni/Al₂O₃And (2) generating a synthesis gas U under the condition of a supported catalyst (the supported amount of nickel is 8 wt%, based on the weight of the catalyst), wherein the molar ratio of hydrogen to carbon monoxide of the synthesis gas U is 1:1, and then conveying the synthesis gas U generated by methane dry reforming and the purified synthesis gas J to a Fischer-Tropsch synthesis unit V for Fischer-Tropsch synthesis reaction.

In addition, the hydrogen Q generated in the process of separating the refinery dry gas and the crude synthesis gas E are conveyed to a synthesis gas purification unit IV together, and the Fischer-Tropsch synthesis reaction is carried out after the purification.

The results are shown in Table 5.

Example 6

This example illustrates the method of the present invention.

(1) Construction of the System

The coal water slurry preparation unit I, the coal gasification unit II, the water gas conversion unit III, the synthesis gas purification unit IV, the Fischer-Tropsch synthesis unit V and the synthesis oil separation unit VI are sequentially connected, a carbon dioxide outlet of the Fischer-Tropsch synthesis unit V and a carbon dioxide outlet of the synthesis gas purification unit IV are communicated with a carbon dioxide inlet of the methane dry reforming unit VII through conveying pipelines, a methane outlet of the refinery dry gas separation unit VIII and a methane outlet of the Fischer-Tropsch synthesis unit V are communicated with a methane inlet of the methane dry reforming unit VII, and a synthesis gas outlet of the methane dry reforming unit VII is communicated with a synthesis gas inlet of the Fischer-Tropsch synthesis unit V through conveying pipelines. In addition, the refinery dry gas separation unit VIII is provided with a hydrogen outlet which is communicated with the crude synthesis gas inlet of the synthesis gas purification unit IV through a pipeline. The heat supply inlet of the reactor preheating furnace of the methane dry reforming unit is provided with two inlets which are respectively connected with the coal gasification raw synthesis gas outlet of the coal gasification unit. The water gas shift reaction with strong heat release supplies heat for a preheating furnace of a methane dry reforming unit with strong heat absorption reaction; the high-temperature crude synthesis gas of the water gas shift unit III firstly enters a methane dry reforming reactor preheating furnace and then enters a synthesis gas purification unit. Flow control valves (not shown) are provided in each of the transfer pipes to obtain a system as shown in fig. 5.

(2) Preparation of catalyst for Fischer-Tropsch synthesis reaction

Catalyst A1 was obtained by the same procedure as in example 1.

(3) Preparation of synthetic oils

Crushing and screening solid raw material coal (coking coal produced by Shanxi Dayu Co., Ltd.) and conveying the crushed and screened solid raw material coal (with the particle size of 10mm) and water B into a coal water slurry preparation unit I at the flow rate of 320t/h to prepare coal water slurry C, and generating crude synthesis gas E mainly comprising carbon monoxide and hydrogen in a coal gasification unit II at the temperature of 1500 ℃ and under the condition of 3.2Mpa by using the coal water slurry C and oxygen D; the raw synthesis gas E is firstly subjected to the reaction of a methane dry reforming unit VIIA reactor preheating furnace is used, the reactor preheating furnace is heated to 600 ℃ required by waste heat, and then the reactor preheating furnace enters a water gas shift unit III to adjust the molar ratio of hydrogen to carbon monoxide and a synthetic gas purification unit IV (the purification conditions are the same as those in example 1) to remove acid gas and sulfide M, so that clean purified synthetic gas J is obtained, wherein the molar ratio of hydrogen to carbon monoxide is 1.2: 1; conveying the purified synthesis gas J into a fixed bed reactor of a Fischer-Tropsch synthesis unit V for carrying out Fischer-Tropsch synthesis reaction, wherein the reaction temperature is 300 ℃, the pressure is 1.5Mpa, the catalyst is the catalyst A1 prepared in the step (2), and the gas space velocity is 5000h^-1To obtain a product containing synthetic oil, carbon dioxide H and methane G, and sending the product into a synthetic oil separation unit VI. And (3) performing gas-liquid separation on the product in the synthetic oil separation unit VI to obtain an oil product and a product gas, purifying the product gas by using acid gas to remove carbon dioxide, and performing cryogenic separation at (-105 ℃) to obtain synthetic oil K, a methane product at (-161 ℃) and unreacted synthetic gas Y. And separating unreacted synthesis gas Y, then entering a Fischer-Tropsch synthesis reactor according to the proportion of 96% for re-reaction, and taking 4% of the unreacted synthesis gas as purge gas Z. The composition of the product obtained after 50h of reaction was analyzed by on-line gas chromatography and the results are shown in table 4.

In addition, after impurities such as oxygen, hydrogen sulfide and the like are removed from the refinery dry gas L (the components are shown in Table 3), the refinery dry gas L is conveyed into a refinery dry gas separation unit VIII at a flow rate of 700t/h, wherein the components of the refinery dry gas L are shown in Table 3, the carbon dioxide is firstly separated from the refinery dry gas L at the temperature of minus 80 ℃ through cryogenic separation, the residual gas is continuously cooled to minus 200 ℃, and methane P (-170 ℃), carbon monoxide (-190 ℃), nitrogen (-196 ℃) and hydrogen Q are sequentially separated.

Conveying methane P generated in the refinery dry gas separation process, carbon dioxide H generated in the synthesis gas purification unit IV, and carbon dioxide H and methane G generated in the Fischer-Tropsch synthesis process to a methane dry reforming unit VII at the temperature of 800 ℃, the pressure of 1.0Mpa and the catalyst of Ni/Al₂O₃Generating synthesis gas U under the condition of a supported catalyst (the loading amount of nickel is 8 weight percent and is based on the weight of the catalyst), wherein the molar ratio of hydrogen to carbon monoxide of the synthesis gas U is 1.2:1, and then conveying the synthesis gas U generated by dry reforming of methane and purified synthesis gas J to the Fischer-Tropsch synthesis gasAnd the synthesis unit V performs Fischer-Tropsch synthesis reaction.

The results are shown in Table 5.

Comparative example 1

This comparative example is illustrative of the system and method of the F-TO process that is currently in common use.

A system was constructed in the same manner as in example 1, except that the system shown in fig. 1, i.e., the system excluding the methane dry reforming unit VII and the refinery dry gas separation unit VIII, was used, and the specific operations were as follows:

(1) construction of the System

The coal water slurry preparation unit I, the coal gasification unit II, the water gas shift unit III, the synthesis gas purification unit IV, the Fischer-Tropsch synthesis unit V and the synthesis oil separation unit VI are sequentially connected. Flow control valves (not shown) are provided in each of the transfer pipes to obtain a system as shown in fig. 1.

(2) Preparation of catalyst for Fischer-Tropsch synthesis reaction

Catalyst A1 was obtained by the same procedure as in example 1.

(3) Preparation of synthetic oils

After being crushed and screened, solid raw material coal (brown coal produced by inner Mongolia) and water B of 360t/h are conveyed together with the water B of 360t/h at the flow rate of 360t/h into a water-coal-slurry preparation unit I to prepare water-coal-slurry C, and the water-coal-slurry C and oxygen D are generated into crude synthesis gas E mainly comprising carbon monoxide and hydrogen in a coal gasification unit II under the conditions of 1300 ℃ and 3.0 Mpa; the raw synthesis gas E is sequentially subjected to water gas shift unit III to adjust the molar ratio of hydrogen to carbon monoxide (the molar ratio of the hydrogen to the carbon monoxide of the raw synthesis gas is about 0.5-0.8, and CO + H is subjected to water gas shift reaction₂O＝CO₂+H₂Partial conversion of CO to CO₂And hydrogen to increase the molar ratio of hydrogen to carbon monoxide to about 1) and a syngas cleanup unit IV (clean conditions the same as in example 1) to remove acid gases and sulfides M, a clean, cleaned syngas J is obtained with a hydrogen to carbon monoxide molar ratio of 0.99:1; conveying the purified synthesis gas J into a fixed bed reactor of a Fischer-Tropsch synthesis unit V for carrying out Fischer-Tropsch synthesis reaction, wherein the reaction temperature is 290 ℃, the pressure is 1.0Mpa, the catalyst is the catalyst A1 prepared in the step (2), and the gas space velocity is 4000h^-1And sending the obtained product containing the synthetic oil into a synthetic oil separation unit VI, separating out the synthetic oil K, discharging the carbon dioxide H and the methane G, separating unreacted synthetic gas Y, then entering a Fischer-Tropsch synthesis reactor according to the proportion of 98% for re-reaction, and taking 2% of the unreacted synthetic gas as purge gas Z. The composition of the product obtained after 50h of reaction was analyzed by on-line gas chromatography.

The results are shown in tables 4 and 5.

TABLE 1 Carrier CO₂-TPD

TABLE 2 catalyst CO-TPD

Note: in tables 1 and 2, "- -" indicates absence or no detection.

TABLE 3 Dry gas composition

Dry gas component	H₂	O₂	N₂	CH₄	Hydrocarbons	CO	CO₂	H₂S
									Composition of dry gas (%)	31.8	0.8	10.1	29.2	22.9	0.6	4.5	0.1

TABLE 4

The gas oil component comprises normal paraffin, isoalkane and olefin, and the isodiesel refers to isoalkane in the gas oil.

TABLE 5

	Water consumption (t/t)_{Synthetic oil})	Carbon dioxideDischarge (t/t)_{Synthetic oil})	Energy efficiency (%)
				Example 1	20	2.7	45
Example 2	20	2.9	42
				Example 3	20	3.1	40
Example 4	20	3.8	44
				Example 5	20	2.2	55
Example 6	20	2.0	53
				Comparative example 1	20	6	36

Note: the energy efficiency is the sum of the calorific value of the synthetic oil finally discharged from the device and the calorific value of raw materials such as the coal-electric steam catalyst solvent entering the device, namely the calorific value of the synthetic oil obtained/the comprehensive energy consumption required for producing the synthetic oil. Wherein, the comprehensive energy consumption comprises raw material heat value and public engineering energy consumption. The method mainly comprises the following steps: the heat value of fuel coal and raw material coal, the electric energy consumed by a motor pump for the device process, the indirect energy consumption of circulating cooling water, boiler make-up water, process air, instrument air, fresh water and the like.

Compared with the comparative example 1, the examples 1 to 6 show that the invention combines the coal-to-synthetic oil process, the refinery dry gas separation process and the methane dry reforming process to simultaneously utilize two greenhouse gases, namely carbon dioxide and methane, so that the two greenhouse gases are converted into products with high added values, the greenhouse gas emission is reduced, and the resource and energy utilization rate of the whole process is obviously improved; in addition, the coal gasification unit with strong heat release, the Fischer-Tropsch synthesis unit and the methane dry reforming unit with strong heat absorption are integrated, so that the heat released by the coal gasification unit and the Fischer-Tropsch synthesis unit is provided for the methane dry reforming unit; meanwhile, in the process of preparing synthetic oil by taking coal and refinery dry gas as raw materials, the supported catalyst for Fischer-Tropsch synthesis reaction is combined on the basis of the method provided by the invention, so that the obtained carbon monoxide has high conversion rate and the selectivity of the isomerized diesel oil is high, and the industrial popularization is facilitated.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

1. A method for preparing synthetic oil by taking coal and refinery dry gas as raw materials is characterized by comprising the following steps:

1) preparing coal powder and water into coal water slurry;

5) separating refinery dry gas to separate out methane;

6) carrying out methane dry reforming reaction on the carbon dioxide obtained in the step 3) and/or the step 4) and the methane obtained in the step 5) or the methane obtained in the step 4) and the step 5);

the catalyst used in the Fischer-Tropsch synthesis reaction is a supported catalyst, the supported catalyst comprises an alumina carrier containing a modifier and an active component loaded on the alumina carrier containing the modifier, the modifier is an IVB group metal component or an IVB group metal component and an alkali metal component and/or an alkaline earth metal component, and the active component is Fe;

in step (4), the conditions of the fischer-tropsch synthesis reaction include: the molar ratio of the hydrogen to the carbon monoxide of the purified synthesis gas is 0.8-2.5:1, the reaction temperature is 280-300 ℃, the reaction pressure is 0.8-1.8MPa, and the gas space velocity is 2000-50000h^-1The reaction is carried out in a fixed bed reactor.

2. The process of claim 1 further comprising returning the synthesis gas from the dry reforming of methane to step 4) for the fischer-tropsch synthesis reaction.

3. The method according to claim 1 or 2, further comprising separating hydrogen from the refinery dry gas and feeding the hydrogen to step 3) for purification together with the gasified raw syngas.

4. The method according to claim 1 or 2, further comprising subjecting the raw synthesis gas obtained in step 2) to water gas shift and subjecting the shifted raw synthesis gas obtained to the purification in step 3).

5. A process according to claim 1 or 2, further comprising separating the synthetic oil containing stream obtained in step 4) to obtain a synthetic oil stream.

6. The method as claimed in claim 1 or 2, wherein the conditions of the methane dry reforming reaction include a reaction temperature of 600 ℃ and 800 ℃ and a reaction pressure of 0.1 to 1.0 MPa.

7. The process according to claim 1 or 2, wherein the gasification reaction conditions are such that the molar ratio of hydrogen to carbon monoxide of the coal gasification raw synthesis gas is 0.4-0.8: 1.

8. The method of claim 1 or 2, wherein the conditions of the gasification reaction comprise: the reaction temperature is 1200 ℃ and 1500 ℃, and the reaction pressure is 2.8-3.2 MPa.

9. The method according to claim 1 or 2, further comprising using the coal gasified raw syngas as a preheating medium for the dry reforming reaction of methane.

10. The process according to claim 1, wherein the carrier is present in an amount of 30 to 95 wt.%, based on the total amount of the catalyst; the content of the active component is 5-70 wt% calculated by metal elements.

11. The method as claimed in claim 10, wherein the content of the alumina carrier containing the modifier is 50-92 wt% based on the total amount of the catalyst; the content of the active component is 8-50 wt% calculated by metal elements.

12. The method as claimed in claim 11, wherein the content of the alumina carrier containing the modifier is 70-90 wt% based on the total amount of the catalyst; the content of the active component is 10-30 wt% calculated by metal elements.

13. The method as claimed in claim 11 or 12, wherein the modifier is present in an amount of 1 to 10% by weight, calculated as the metallic element, based on the weight of the alumina support containing the modifier.

14. The method as claimed in claim 13, wherein the modifier is present in an amount of 2 to 8 wt.% as metal element, based on the weight of the modifier-containing alumina support.

15. The method of claim 1, wherein the group IVB metal component is Zr and/or Ti; the alkali metal component is one or more of Li, K and Na; the alkaline earth metal component is Mg and/or Ca.

16. The method of claim 15, wherein the alkali metal component is Li and/or K.

17. The method of claim 1, wherein the modifier-containing alumina support is a modifier-containing γ -alumina support.

18. The method of claim 1, wherein the supported catalyst is prepared by a preparation method comprising the steps of: the method comprises the steps of adsorbing impregnation liquid containing active components onto the alumina carrier containing the modifier, and sequentially drying and roasting after adsorption.