阅读说明：本技术 一种利用双头气化得到煤基合成油并联产lng的方法和系统 (Method and system for obtaining coal-based synthetic oil and co-producing LNG (liquefied Natural gas) by double-head gasification ) 是由 陈林峰 董根全 郝栩 刘利军 李永旺 杨勇 曹立仁 于 2020-12-11 设计创作，主要内容包括：本发明涉及一种利用双头气化来得到煤基合成油并联产LNG的方法以及用于实施该方法的系统。其中,所述方法包括对原料粉煤、焦炭等进行水煤浆气化并同时对块煤进行加压气化,将由此得到的产物经过净化、费托合成、天然气及甲醇装置处理、油品加工和油品合成等处理,得到汽油、柴油和LNG以及其它具有商业价值的副产物。本发明通过可使用副产的焦炭或生化污泥等代替部分原料粉煤并在碎煤气化中使用CO-2代替部分水蒸汽,减少了原料的消耗和气化废水的产量,并通过对中间产生的重油、合格蜡以及尾气等进行合理处理；从而在降低原料用量的同时提高了油品的产量,而且还减少了污染物的产生,带来了更高的经济效益及环保效益。(The invention relates to a method for obtaining coal-based synthetic oil and co-producing LNG by double-head gasification and a system for implementing the method. The method comprises the steps of gasifying coal water slurry of raw materials such as pulverized coal and coke, pressurizing and gasifying lump coal, purifying the obtained product, performing Fischer-Tropsch synthesis, treating natural gas and methanol devices, processing oil products, synthesizing oil products and the like to obtain gasoline, diesel oil, LNG and other products with commercial valuesBy-products of (a). The invention can use the by-product coke or biochemical sludge to replace part of the raw material pulverized coal and use CO in the crushed coal gasification 2 Partial water vapor is replaced, the consumption of raw materials and the yield of gasified wastewater are reduced, and heavy oil, qualified wax, tail gas and the like generated in the middle are reasonably treated; thereby improving the yield of oil products while reducing the consumption of raw materials, reducing the generation of pollutants and bringing higher economic benefit and environmental protection benefit.)

1. A method for obtaining coal-based synthetic oil and co-producing LNG using dual-head gasification, wherein the method comprises:

1) carrying out coal water slurry gasification treatment on a raw material and oxygen to obtain crude synthesis gas, acid gas, wastewater, waste residue and a filter cake, wherein the raw material comprises pulverized coal and optionally comprises coke, dust-containing tar, green coke, biochemical sludge or any combination thereof;

2) purifying the crude synthesis gas to obtain purified synthesis gas, process condensate, carbon dioxide, acid gas and exhaust gas;

3) carrying out crushed coal gasification on raw material lump coal, oxygen, medium-pressure steam and part of the carbon dioxide in the step 2) to obtain crushed coal purified gas, naphtha, liquefied petroleum gas, diesel oil, acid gas, expansion gas, polyphenol, ammonia water, waste residue and wastewater;

4) sending the crushed coal purified gas and the rest part of the carbon dioxide in the step 2) into a natural gas and methanol device for treatment to obtain purified gas, liquefied natural gas, liquefied petroleum gas, methanol, hydrogen, naphtha and tail gas;

5) carrying out Fischer-Tropsch synthesis reaction on the purified gas in the step 4) and the purified synthesis gas in the step 2) to obtain light oil, heavy oil, qualified wax, synthetic water and decarbonized tail gas;

6) feeding the light oil, heavy oil, qualified wax and synthetic water, the naphtha obtained in the step 4) and part of methanol into an oil product processing device for processing to obtain blended diesel oil, gasoline, heavy diesel oil, naphtha, liquefied petroleum gas, liquid paraffin, processing dry gas, mixed alcohol and synthetic wastewater;

7) feeding the naphtha and the liquefied petroleum gas in the step 6), the naphtha and the liquefied petroleum gas in the step 3) and the liquefied petroleum gas in the step 4) and the rest part of methanol into a gasoline device for treatment to obtain gasoline, polypropylene, reformed dry gas and hydrogen;

8) returning the decarbonized tail gas, the processing dry gas and the reforming dry gas to the natural gas and methanol device in the step 4) for treatment; and

9) and (3) returning the hydrogen to the gasoline device in the step 7), the oil product processing device in the step 6) and the Fischer-Tropsch synthesis reaction in the step 5) for reaction.

2. The method of claim 1, wherein the method further comprises the steps of: returning the process condensate in the step 2) to the step 1) to participate in the gasification of the coal water slurry;

preferably, the method further comprises the steps of: treating oxygen, the acid gas obtained in the step 1) and the step 2) and the acid gas and the expansion gas obtained in the step 3) by a sulfur recovery and sulfuric acid device to obtain a sulfur product and concentrated sulfuric acid;

preferably, the method further comprises the steps of: returning the heavy diesel oil obtained in the step 6) to the step 5) to participate in the Fischer-Tropsch synthesis reaction.

3. The method according to claim 1 or 2, wherein the coal-water slurry gasification treatment is performed in the step 1) under the following conditions: the temperature is 1250-1400 ℃, and the pressure is 5-8 MpaG.

4. The method according to any one of claims 1 to 3, wherein the temperature of the crushed coal gasification in the step 3) is 1000 to 1300 ℃, and the pressure is 2 to 5 MpaG;

preferably, the mole percentage of methane in the crushed coal purified gas in the step 3) is 5-50%;

preferably, in step 3), the mass ratio of the carbon dioxide to the medium-pressure steam is 1:1 or less; preferably, the mass ratio of the carbon dioxide to the medium-pressure steam is (3-4): 7-6.

5. The method according to any one of claims 1 to 4, wherein in step 4) the following is performed in the natural gas and methanol plant: the deep cooling separation is carried out at the pressure of 1.0-5.0 MpaG and the temperature of-200-150 ℃, and the methanol synthesis is carried out at the pressure of 2.5-10.0 MpaG and the temperature of 200-400 ℃.

6. The process of any one of claims 1 to 5, wherein in step 5) the Fischer-Tropsch synthesis reaction is carried out using an Fe-based catalyst and/or a Co-based catalyst;

preferably, the Fe-based catalyst comprises an active ingredient and an electron assistant, wherein the active ingredient is alpha-Fe₂O₃And/or Fe₃O₄The electronic assistant is at least one of alkali metal, transition metal and/or rare earth metal; more preferably, the Fe-based catalyst may further include a structural assistant, and the structural assistant is SiO₂、Al₂O₃、MgO、TiO₂And activated carbon;

or preferably, the Co-based catalyst consists of an active component Co, a carrier and an auxiliary agent, wherein the carrier is SiO₂、γ-Al₂O₃Activated carbon and TiO₂The auxiliary agent is at least one of Ni, Zr, Mg, Mn, Ru, Pt, Re, Ce, La and Th;

preferably, in the step 5), the temperature of the Fischer-Tropsch synthesis reaction is 180-380 ℃, and the pressure is 0.5-6.0 MpaG;

preferably, in the step 5), the temperature of the decarbonized tail gas is 20-100 ℃, and the pressure is 1.5-5.0 MpaG.

7. The method according to any of claims 1-6, wherein in step 6) the following is performed in the oil processing plant: hydrorefining at 220-350 ℃ and 7.0-8.5 MpaG, hydroupgrading at 300-400 ℃ and 7.1-8.5 MPG, and catalytic cracking at 300-750 ℃ and 0.1-0.5 MpaG.

8. The method according to any one of claims 1 to 7, wherein in step 7), the following is carried out in the gasoline device: isomerization reaction is carried out at the temperature of 80-150 ℃ under the condition of 2.0-6.0 MpaG, and polymerization reaction is carried out at the temperature of 50-90 ℃ under the condition of 2.0-5.5 MpaG.

9. A system for implementing the method of any one of claims 1-8, wherein the system comprises:

the coal water slurry gasification device and the crushed coal gasification device are arranged in parallel;

a purification device fluidly connected to the coal-water slurry gasification device;

an oil synthesis device fluidly connected to the purification device;

a natural gas and methanol unit fluidly connected to the crushed coal gasification unit, the purification unit, and the oil synthesis unit;

an oil processing plant connected in fluid communication to the oil synthesis plant and the natural gas and methanol plant; and

a gasoline device fluidly connected to the oil processing device, the crushed coal gasification device, and the natural gas and methanol device.

10. The system of claim 9, further comprising a sulfur recovery and sulfuric acid unit fluidly connected to the coal-water slurry gasification unit, the purification unit, and the crushed coal gasification unit.

Technical Field

The invention belongs to the field of coal chemical industry, and particularly relates to a method for obtaining coal-based synthetic oil and co-producing LNG (liquefied natural gas) from coal raw materials by using a double-head gasification technology, and a system for implementing the method.

Background

China has relatively rich coal resources, and is a few countries in the world which take coal as a main energy source. "lack of oil, gas and rich coal" (coal accounts for 96% of the total energy, and oil and gas account for 4% of the total energy) is the basic national situation in China, and coal resources are important energy resources that can be relied on in the long-term development of China. At present, the dependence degree of the petroleum demand of China on import is increasingly deepened, and the external dependence degree of the petroleum of China is close to 60 percent by 2014, so that the petroleum shortage becomes a main structural contradiction in the energy supply and demand of China and a bottleneck for restricting the rapid development of national economy. Factors such as unstable factors, fluctuation of political situation of main oil production areas, abnormal fluctuation of oil price and the like in the supply and demand relationship of the international oil market have great influence and impact on the supply of Chinese oil and energy and the development of social economy, so that the energy and economic safety problems in China are increasingly obvious. Therefore, from the perspective of energy safety, developing petroleum alternative fuels based on Chinese resource characteristics, and replacing a part of petroleum product demands by coal with relatively abundant Chinese resource reserves have profound strategic significance.

The coal-produced oil accords with the energy structure of China, the coal resource of China is relatively rich, the coal-produced oil is the most reliable source for guaranteeing the safe supply of energy in the future of China, and is the cheapest available energy at present, the coal-produced oil essentially realizes the comprehensive clean utilization of the coal chemical industry, and simultaneously can extend the industrial chain of coal enterprises, optimize the energy structure and drive the sustainable development of the related heavy chemical industry. Based on relatively abundant coal resources in China, industrialization is realized by utilizing an independently developed indirect coal liquefaction technology, a dynamic strategic oil reserve library which can be regulated and controlled at any time according to requirements is provided for oil reserves in China, and the specific implementation of the measure undoubtedly has profound significance for guaranteeing the energy safety of China.

In recent years, many studies have been made on synthetic oils such as gasoline obtained by gasification using coal as a raw material, however, the conventional gasification technology (for example, coal water slurry gasification) has the following disadvantages: the gasification equipment has small diameter, low pressure, more equipment sets and large investment; the discharge amount of three wastes is large, and the sewage treatment cost is high. For example, patent application CN105176566A discloses a method for co-producing LNG from coal-based synthetic oil, which relates to the production of a methane-containing synthetic gas by using single-gasification or double-head gasification technology, then the methane is separated by cryogenic technology to produce an LNG product, and the rest of the synthetic gas is processed by F-T synthesis technology to produce an oil product. Patent applications CN104004557A and CN105462638A disclose a method for producing natural gas by combining crushed coal pressure gasification and water coal slurry gasification, but the water coal slurry gasification pressure is lower, the number of sets of gasification devices is too large, the investment is larger, and a large amount of steam is input into the crushed coal pressure gasification device, so that the subsequent wastewater treatment capacity is large, and the biochemical sludge is not considered to be utilized, so that the raw material coal consumption is increased, and the waste residue discharge is large.

Therefore, there is a need in the art to develop a more optimized method for coal gasification, which can reduce the investment of a gasification device, recycle waste, reduce the consumption of raw coal, and reduce the discharge of three wastes.

Disclosure of Invention

In order to solve the above technical problems, the present invention aims to provide a method for producing coal-based synthetic oil and co-producing LNG (liquefied natural gas) by using double-head gasification, which has advantages of economic investment, low operating cost and optimized process flow, and a system for implementing the method.

In one aspect, the present invention relates to a method for obtaining coal-based synthetic oil and co-producing LNG using dual-head gasification, wherein the method comprises:

1) carrying out coal water slurry gasification treatment on a raw material and oxygen to obtain crude synthesis gas, acid gas, wastewater, waste residue and a filter cake, wherein the raw material comprises pulverized coal and optionally comprises coke, dust-containing tar, green coke, biochemical sludge or any combination thereof;

2) purifying the crude synthesis gas to obtain purified synthesis gas, process condensate, carbon dioxide, acid gas and exhaust gas;

3) carrying out crushed coal gasification on raw material lump coal, oxygen, medium-pressure steam and part of the carbon dioxide in the step 2) to obtain crushed coal purified gas, naphtha, liquefied petroleum gas, diesel oil, acid gas, expansion gas, polyphenol, ammonia water, waste residue and wastewater;

4) sending the crushed coal purified gas and the rest part of the carbon dioxide in the step 2) into a natural gas and methanol device for treatment to obtain purified gas, liquefied natural gas, liquefied petroleum gas, methanol, hydrogen, naphtha and tail gas;

5) carrying out Fischer-Tropsch synthesis reaction on the purified gas in the step 4) and the purified synthesis gas in the step 2) to obtain light oil, heavy oil, qualified wax, synthetic water and decarbonized tail gas;

6) feeding the light oil, heavy oil, qualified wax and synthetic water, the naphtha obtained in the step 4) and part of methanol into an oil product processing device for processing to obtain blended diesel oil, gasoline, heavy diesel oil, naphtha, liquefied petroleum gas, liquid paraffin, processing dry gas, mixed alcohol and synthetic wastewater;

7) feeding the naphtha and the liquefied petroleum gas in the step 6), the naphtha and the liquefied petroleum gas in the step 3) and the liquefied petroleum gas in the step 4) and the rest part of methanol into a gasoline device for treatment to obtain gasoline, polypropylene, reformed dry gas and hydrogen;

8) returning the decarbonized tail gas, the processing dry gas and the reforming dry gas to the natural gas and methanol device in the step 4) for treatment; and

9) and (3) returning the hydrogen to the gasoline device in the step 7), the oil product processing device in the step 6) and the Fischer-Tropsch synthesis reaction in the step 5) for reaction.

In another aspect, the invention relates to a system for implementing the above method, wherein the system comprises:

the coal water slurry gasification device and the crushed coal gasification device are arranged in parallel;

a purification device fluidly connected to the coal-water slurry gasification device and the crushed coal gasification device;

an oil synthesis device fluidly connected to the purification device;

a natural gas and methanol unit fluidly connected to the crushed coal gasification unit, the purification unit, and the oil synthesis unit;

an oil processing plant connected in fluid communication to the oil synthesis plant and the natural gas and methanol plant; and

a gasoline device fluidly connected to the oil processing device, the crushed coal gasification device, and the natural gas and methanol device.

The method of the invention reduces the investment of the device and the consumption of raw material coal by performing high-pressure water coal slurry gasification and crushed coal gasification in parallel, and simultaneously, the invention also reduces the consumption of raw material coalThe discharge amount of three wastes is reduced. The scheme of the invention can realize the following effects: in the step of gasifying the coal water slurry, coke, dust-containing tar, green coke, biochemical sludge and the like can be used for replacing part of raw material pulverized coal, so that the consumption of the raw material pulverized coal is reduced, the waste treatment capacity of the device is reduced, and meanwhile, the step can be suitable for high coal slurry concentration and reduces the water consumption for blending the coal slurry; by using CO in the step of gasification of crushed coal₂Replacing part of the steam, so that the charging amount of the steam can be reduced by more than 35 wt%, and the waste water amount of the gasification step is reduced by more than 30 wt%; the heavy oil and the qualified wax are catalytically cracked in an oil processing device to generate oil, and low-value products are utilized to produce high-value products, so that the economic benefit of a project can be improved; the Fischer-Tropsch synthesis reaction can generate decarbonized tail gas containing a certain amount of methane, and the part of methane in the decarbonized tail gas is further recovered, so that the Fischer-Tropsch synthesis yield can be improved, and the energy consumption of a system can be greatly reduced; the coal is used for producing oil products and simultaneously coproducing liquefied natural gas and polypropylene byproducts, so that the economic benefit of the project can be increased; in addition, the coal water slurry gasification can be carried out under high pressure (such as 5-8 MPaG, preferably 6.5MPaG), so that the number of sets of gasification devices is further reduced, and the total investment is reduced.

Drawings

FIG. 1 is a schematic diagram of an exemplary process for producing coal-based synthetic oil and simultaneously producing liquefied natural gas using dual-head gasification according to the present invention.

Wherein, each mark in the drawings respectively represents the following content:

101 a water-coal-slurry gasification device; 102 a purification device; 103 crushed coal gasification device; 104 sulfur recovery and sulfuric acid unit; 105 oil synthesizing device; 106 natural gas and methanol plants; 107 oil processing equipment; 108 gasoline engine unit.

Detailed Description

The technical solutions of the present invention will be described below by way of exemplary embodiments, but the scope of the present invention is not limited thereto.

In the present invention, unless otherwise specified, the term "coal-based synthetic oil" refers to a liquid fuel obtained by processing with coal as a raw material, and includes, for example, gasoline, diesel oil, and the like.

In the present invention, unless otherwise specified, the term "biochemical sludge" refers to a sludge subjected to dehydration treatment discharged from a secondary sedimentation tank, a biological reaction tank (sedimentation zone or sedimentation sludge discharge period) in a biochemical treatment process of sewage.

In the present invention, the term "pulverized coal" means coal having a particle size of less than 5mm, unless otherwise specified.

In the present invention, the term "lump coal" means coal having a particle size of more than 5mm, unless otherwise specified.

In the present invention, unless otherwise specified, the term "syngas" is meant to comprise mainly CO and H₂The mixed gas of (1).

In the present invention, unless otherwise specified, the term "process condensate" refers to a liquid obtained by separating water vapor contained in raw gas by condensation in a purification device.

In the present invention, unless otherwise specified, the term "light oil" means a mixture of hydrocarbons having predominantly a boiling range of less than 300 ℃.

In the present invention, unless otherwise specified, the term "heavy oil" means a hydrocarbon mixture having a distillation range of 175 to 450 ℃.

In the present invention, unless otherwise specified, the term "part" or "a portion" means some of the whole, that is, it may be any value ranging from more than 0% to less than 100% with respect to the whole amount of the subject modified by the term.

In the present invention, unless otherwise indicated, the term "blended diesel" refers to a diesel product that can be directly used to fuel a diesel engine.

In the present invention, unless otherwise indicated, the term "heavy diesel" refers to hydrocarbon products having a distillation range in the range of 300 ℃ to 450 ℃.

In the present invention, unless otherwise specified, the term "purified synthesis gas" refers to a purified gas obtained by subjecting a raw synthesis gas obtained from a coal water slurry gasification apparatus to CO shift conversion and low-temperature methanol washing, and contains H₂、CO、CO₂、N₂Ar and CH₄。

In the present invention, unless otherwise specified, the term "medium pressure steam" means steam of 2.5MPa < P.ltoreq.6 MPa, 400 ℃ < T.ltoreq.450 ℃.

In the present invention, the terms "coal water slurry gasification unit" and "pulverized coal gasification unit" are used interchangeably. The terms "sulfur recovery and sulfur plant" and "sulfur recovery and sulfuric acid plant" are used interchangeably.

In one embodiment, the present invention relates to a method for obtaining coal-based synthetic oil and co-producing LNG using dual-head gasification, wherein the method comprises:

1) carrying out coal water slurry gasification treatment on a raw material and oxygen to obtain crude synthesis gas, acid gas, wastewater, waste residue and a filter cake, wherein the raw material comprises pulverized coal and optionally comprises coke, dust-containing tar, green coke, biochemical sludge or any combination thereof;

2) purifying the crude synthesis gas to obtain purified synthesis gas, process condensate, carbon dioxide, acid gas and exhaust gas;

3) carrying out crushed coal gasification on raw material lump coal, oxygen, medium-pressure steam and part of the carbon dioxide in the step 2) to obtain crushed coal purified gas, naphtha, liquefied petroleum gas, diesel oil, acid gas, expansion gas, polyphenol, ammonia water, waste residue and wastewater;

4) sending the crushed coal purified gas and the rest part of the carbon dioxide in the step 2) into a natural gas and methanol device for treatment to obtain purified gas, liquefied natural gas, liquefied petroleum gas, methanol, hydrogen, naphtha and tail gas;

5) carrying out Fischer-Tropsch synthesis reaction on the purified gas in the step 4) and the purified synthesis gas in the step 2) to obtain light oil, heavy oil, qualified wax, synthetic water and decarbonized tail gas;

6) feeding the light oil, heavy oil, qualified wax and synthetic water, the naphtha obtained in the step 4) and part of methanol into an oil product processing device for processing to obtain blended diesel oil, gasoline, heavy diesel oil, naphtha, liquefied petroleum gas, liquid paraffin, processing dry gas, mixed alcohol and synthetic wastewater;

7) feeding the naphtha and the liquefied petroleum gas in the step 6), the naphtha and the liquefied petroleum gas in the step 3) and the liquefied petroleum gas in the step 4) and the rest part of methanol into a gasoline device for treatment to obtain gasoline, polypropylene, reformed dry gas and hydrogen;

8) returning the decarbonized tail gas, the processing dry gas and the reforming dry gas to the natural gas and methanol device in the step 4) for treatment; and

9) and (3) returning the hydrogen to the gasoline device in the step 7), the oil product processing device in the step 6) and the Fischer-Tropsch synthesis reaction in the step 5) for reaction.

In a preferred embodiment, the above method of the present invention further comprises the steps of: and (3) returning the process condensate in the step 2) to the step 1) to participate in the gasification of the coal water slurry.

In a preferred embodiment, the above method of the present invention further comprises the steps of: and (3) treating the oxygen, the acid gas obtained in the step 1) and the step 2) and the acid gas and the expansion gas obtained in the step 3) by a sulfur recovery and sulfuric acid device to obtain a sulfur product and concentrated sulfuric acid.

In a preferred embodiment, the above method of the present invention further comprises the steps of: returning the heavy diesel oil obtained in the step 6) to the step 5) to participate in the Fischer-Tropsch synthesis reaction.

In this context, the use of recycled waste selected from the group consisting of coke, dust-containing tar, green coke, biochemical sludge, and any combination thereof as a raw material can further reduce the consumption of raw coal and, at the same time, further reduce the discharge of three wastes.

In a preferred embodiment, in the step 1), the coal-water slurry gasification treatment is performed under the following conditions: the temperature is 1250-1400 deg.C (such as 1280 deg.C), and the pressure is 5-8 MpaG (such as 6.5 MPaG).

In this context, the acid gas and the expanded gas described in step 1), step 2) and step 3) comprise essentially H₂S, COS and carbon dioxide.

Herein, in step 2), the raw synthesis gas is subjected to a shift unit in the purification unit under conventional conditions to adjust the H/C ratio and to a low temperature methanol wash to obtain a purified synthesis gas.

In this context, the purified synthesis gas of step 2) and the cleaned gas of crushed coal of step 3) have a water content of 1ppm or less and CO₂The content is less than 0.5 percent, and the sulfur content is less than 0.1 ppm.

In a preferred embodiment, the temperature of the crushed coal gasification in step 3) may be 1000 to 1300 ℃ (e.g., 1200 ℃), and the pressure may be 2 to 5MpaG (e.g., 4.2 MpaG).

In a preferred embodiment, the mole percentage of methane in the crushed coal purge gas of step 3) is 5% to 50%, for example 18.89%.

In step 3), by introducing part of the CO₂The replacement of water vapor can bring the following advantages: the amount of water vapour (e.g. medium pressure steam) is reduced, thereby reducing the amount of waste water and increasing the amount of CO, thereby facilitating the production of the synthesis gas required in the fischer-tropsch synthesis reaction. In a preferred embodiment, in the step 3), the mass ratio of the carbon dioxide to the medium-pressure steam is 1:1 or less, preferably (3-4): 7-6.

In a preferred embodiment, in step 4), the following treatments are carried out in the natural gas and methanol plant: the cryogenic separation is carried out at a pressure of 1.0 to 5.0MpaG (e.g., 3.0MPaG) and a temperature of-200 to-150 ℃ (e.g., -170 ℃), and the methanol synthesis is carried out at a pressure of 2.5 to 10.0MpaG (e.g., 4.5MPaG) and a temperature of 200 to 400 ℃ (e.g., 380 ℃).

In the present invention, the fischer-tropsch synthesis reaction is a conventional fischer-tropsch synthesis reaction in the art, for example, the fischer-tropsch synthesis reaction can be carried out using fixed bed fischer-tropsch synthesis technology, fluidized bed fischer-tropsch synthesis technology or slurry bed fischer-tropsch synthesis technology as known in the art.

In a preferred embodiment, in step 5), the fischer-tropsch synthesis reaction is carried out using an Fe-based catalyst and/or a Co-based catalyst.

The Fe-based catalyst described herein may be any Fe-based catalyst known in the art for use in fischer-tropsch synthesis reactions; preferably, the Fe-based catalyst may include an active ingredient and an electron adjuvant, the active ingredient being alpha-Fe₂O₃And/or Fe₃O₄The electron auxiliary agent is alkali metal, transition metal and/or rare earth metal, and can be at least one of K, Cu, Mn, V, Ce, La and Eu, for example; the Fe-based catalyst may also include a structural promoter, such as SiO₂、Al₂O₃、MgO、TiO₂And Activated Carbon (AC). More preferably, the Fe-based catalyst consists of alpha-Fe in a mass ratio of 95:4.8:0.5:0.5:20₂O₃、Fe₃O₄、La₂O₃CuO and K₂And (C) O.

The Co-based catalyst described herein may be any Co-based catalyst known in the art for use in fischer-tropsch synthesis reactions; preferably, the Co-based catalyst consists of an active component Co, a carrier and an auxiliary agent, wherein the carrier can be SiO₂、γ-Al₂O₃Activated carbon and TiO₂The auxiliary agent can be at least one of Ni, Zr, Mg, Mn, Ru, Pt, Re, Ce, La and Th.

In a preferred embodiment, in step 5), the temperature of the Fischer-Tropsch synthesis reaction is from 180 to 380 ℃, for example 270 ℃.

In a preferred embodiment, in step 5), the pressure of the Fischer-Tropsch synthesis reaction is in the range of from 0.5 to 6.0MPaG, for example 3.3 MPaG.

In a preferred embodiment, in the step 5), the temperature of the decarbonized tail gas is 20 to 100 ℃ (for example, 76 ℃) and the pressure is 1.5 to 5.0MpaG (for example, 3.3 MPaG).

In a preferred embodiment, in step 6), the following treatments are carried out in the oil processing plant: hydrorefining at a temperature of 220 to 350 ℃ and a pressure of 7.0 to 8.5MpaG (e.g., at 260 ℃ and at 8.0MPaG), hydroupgrading at a temperature of 300 to 400 ℃ and at a pressure of 7.1 to 8.5MPG (e.g., at 340 ℃ and at 8.0MPaG), and catalytic cracking at a temperature of 300 to 750 ℃ and at a pressure of 0.1 to 0.5MPaG (e.g., at 500 ℃ and at 0.1 MPaG).

In a preferred embodiment, in step 7), the following treatment is carried out in the gasoline engine: the isomerization reaction is carried out at 2.0 to 6.0MpaG (e.g., 3.6MPaG) and 80 to 150 ℃ (e.g., 120 ℃), and the polymerization reaction is carried out at 2.0 to 5.5MpaG (e.g., 3.4MPaG) and 50 to 90 ℃ (e.g., 70 ℃).

In one embodiment, the present invention relates to a system for implementing the above method, wherein the system comprises:

the coal water slurry gasification device and the crushed coal gasification device are arranged in parallel;

a purification device fluidly connected to the coal-water slurry gasification device;

an oil synthesis device fluidly connected to the purification device;

a natural gas and methanol unit fluidly connected to the crushed coal gasification unit, the purification unit, and the oil synthesis unit;

an oil processing plant connected in fluid communication to the oil synthesis plant and the natural gas and methanol plant; and

a gasoline device fluidly connected to the oil processing device, the crushed coal gasification device, and the natural gas and methanol device.

In a preferred embodiment, the system further comprises a sulfur recovery and sulfuric acid unit fluidly connected to the coal-water slurry gasification unit, the purification unit, and the crushed coal gasification unit.

Herein, the oil processing unit includes a hydrorefining unit, a hydroupgrading unit, and a catalytic cracking unit.

FIG. 1 is a flow diagram of an exemplary process for producing coal-based synthetic oil and simultaneously producing liquefied natural gas using a dual-head gasification process according to the present invention. For illustrative purposes only, the method of the present invention will now be described with reference to the illustration shown in fig. 1 as follows:

as shown in fig. 1, in a pulverized coal gasification apparatus 101, raw pulverized coal, coke, dust-containing tar, green coke, biochemical sludge, and oxygen are treated to generate a raw synthesis gas, and acid gas, wastewater, waste residues, and filter cakes are simultaneously generated.

The purification device 102 is connected to the pulverized coal gasification device 101, and in the purification device 102, impurities such as carbon dioxide and acid gas are removed from the raw synthesis gas to obtain a purified synthesis gas, a process condensate, carbon dioxide, acid gas, and an exhaust gas.

The crushed coal gasification device 103 is connected with the purification device 102, and in the crushed coal gasification device 103, raw lump coal, oxygen, medium-pressure steam and carbon dioxide from the purification device 102 are used for obtaining crushed coal purified gas by a pressure gasification technology, and diesel oil, acid gas, expansion gas, naphtha, liquefied petroleum gas, polyphenol, ammonia water, waste residues and wastewater are simultaneously generated.

The sulfur recovery and sulfur unit 104 is connected to the pulverized coal gasification unit 101, the purification unit 102, and the pulverized coal gasification unit 103, and in the sulfur recovery and sulfur unit 104, acid gas and expanded gas from the pulverized coal gasification unit 101, the purification unit 102, and the pulverized coal gasification unit 103 are recovered to produce a sulfur product and concentrated sulfuric acid.

The natural gas and methanol device 106 is connected to the purification device 102 and the crushed coal gasification device 103, and the carbon dioxide from the purification device 102 and the crushed coal purified gas from the crushed coal gasification device 103 are processed by the natural gas and methanol device 106 to generate purified gas, naphtha, methanol, liquefied petroleum gas, liquefied natural gas, tail gas and hydrogen.

The oil product synthesizing device 105 is connected to the purifying device 102 and the natural gas and methanol device 106, and in the oil product synthesizing device 105, the purified synthesis gas and the purified gas generate light oil, heavy oil, qualified wax, synthetic water and decarbonized tail gas through a Fischer-Tropsch synthesis reaction.

The oil processing device 107 is connected to the oil synthesizing device 105 and the natural gas and methanol device 106, and in the oil processing device 107, the light oil, the heavy oil, the qualified wax, and the synthetic water from the oil synthesizing device 105 are treated with the naphtha and the methanol from the natural gas and methanol device 106 to generate blended diesel oil, gasoline, heavy diesel oil, naphtha, liquefied petroleum gas, liquid paraffin, processing dry gas, mixed alcohol, and synthetic wastewater.

The gasoline device 108 is connected with the crushed coal gasification device 103, the natural gas and methanol device 106 and the oil product processing device 107, and naphtha and liquefied petroleum gas from the crushed coal gasification device 103, methanol and liquefied petroleum gas from the natural gas and methanol device 106 and naphtha and liquefied petroleum gas from the oil product processing device 107 are processed by the gasoline device 108 to generate gasoline, polypropylene, reformed dry gas and hydrogen. The decarbonized tail gas, the process dry gas, and the reformed dry gas are returned to the natural gas and methanol plant 106 for processing.

Exemplary aspects of the present invention may be illustrated by the following numbered paragraphs, but the scope of the present invention is not limited thereto:

1. a method for obtaining coal-based synthetic oil and co-producing LNG using dual-head gasification, wherein the method comprises:

1) carrying out coal water slurry gasification treatment on a raw material and oxygen to obtain crude synthesis gas, acid gas, wastewater, waste residue and a filter cake, wherein the raw material comprises pulverized coal and optionally comprises coke, dust-containing tar, green coke, biochemical sludge or any combination thereof;

2) purifying the crude synthesis gas to obtain purified synthesis gas, process condensate, carbon dioxide, acid gas and exhaust gas;

3) carrying out crushed coal gasification on raw material lump coal, oxygen, medium-pressure steam and part of the carbon dioxide in the step 2) to obtain crushed coal purified gas, naphtha, liquefied petroleum gas, diesel oil, acid gas, expansion gas, polyphenol, ammonia water, waste residue and wastewater;

4) sending the crushed coal purified gas and the rest part of the carbon dioxide in the step 2) into a natural gas and methanol device for treatment to obtain purified gas, liquefied natural gas, liquefied petroleum gas, methanol, hydrogen, naphtha and tail gas;

5) carrying out Fischer-Tropsch synthesis reaction on the purified gas in the step 4) and the purified synthesis gas in the step 2) to obtain light oil, heavy oil, qualified wax, synthetic water and decarbonized tail gas;

6) feeding the light oil, heavy oil, qualified wax and synthetic water, the naphtha obtained in the step 4) and part of methanol into an oil product processing device for processing to obtain blended diesel oil, gasoline, heavy diesel oil, naphtha, liquefied petroleum gas, liquid paraffin, processing dry gas, mixed alcohol and synthetic wastewater;

7) feeding the naphtha and the liquefied petroleum gas in the step 6), the naphtha and the liquefied petroleum gas in the step 3) and the liquefied petroleum gas in the step 4) and the rest part of methanol into a gasoline device for treatment to obtain gasoline, polypropylene, reformed dry gas and hydrogen;

8) returning the decarbonized tail gas, the processing dry gas and the reforming dry gas to the natural gas and methanol device in the step 4) for treatment; and

9) and (3) returning the hydrogen to the gasoline device in the step 7), the oil product processing device in the step 6) and the Fischer-Tropsch synthesis reaction in the step 5) for reaction.

2. The method of paragraph 1 wherein the method further comprises the steps of: and (3) returning the process condensate in the step 2) to the step 1) to participate in the gasification of the coal water slurry.

3. The method of paragraph 1 or 2, wherein the method further comprises the steps of: and (3) treating the oxygen, the acid gas obtained in the step 1) and the step 2) and the acid gas and the expansion gas obtained in the step 3) by a sulfur recovery and sulfuric acid device to obtain a sulfur product and concentrated sulfuric acid.

4. The method of any of paragraphs 1-3, wherein the method further comprises the steps of: returning the heavy diesel oil obtained in the step 6) to the step 5) to participate in the Fischer-Tropsch synthesis reaction.

5. The method as described in any of paragraphs 1 to 4, wherein, in step 1), the coal-water slurry gasification treatment is performed under the following conditions: the temperature is 1250-1400 ℃, and the pressure is 5-8 MpaG.

6. The method as in any one of paragraphs 1 to 5, wherein the temperature of the crushed coal gasification in step 3) is 1000 to 1300 ℃ and the pressure is 2 to 5 MpaG.

7. The method as recited in any one of paragraphs 1 to 6, wherein the crushed coal purge gas of step 3) has a methane content of 5 to 50 mole%.

8. The method of any of paragraphs 1-7, wherein in step 3) the mass ratio of the carbon dioxide to the medium pressure steam is 1:1 or less.

9. The method of paragraph 8, wherein the mass ratio of the carbon dioxide to the medium pressure steam is (3-4): (7-6).

10. The method of any of paragraphs 1-9, wherein in step 4), the natural gas and methanol plant is treated as follows: the deep cooling separation is carried out at the pressure of 1.0-5.0 MpaG and the temperature of-200-150 ℃, and the methanol synthesis is carried out at the pressure of 2.5-10.0 MpaG and the temperature of 200-400 ℃.

11. The method of any of paragraphs 1-10, wherein in step 5) the fischer-tropsch synthesis reaction is carried out using an Fe-based catalyst and/or a Co-based catalyst.

12. The method of paragraph 11 wherein the Fe-based catalyst comprises an active ingredient that is alpha-Fe and an electron adjuvant₂O₃And/or Fe₃O₄The electronic assistant is at least one of alkali metal, transition metal and/or rare earth metal.

13. The method of paragraph 12, wherein the Fe-based catalyst further comprises a structural promoter, the structural promoter being SiO₂、Al₂O₃、MgO、TiO₂And activated carbon.

14. The method of paragraph 11 wherein the Co-based catalyst is comprised of an active component Co, a support and an adjunct, the support being SiO₂、γ-Al₂O₃Activated carbon and TiO₂The auxiliary agent is at least one of Ni, Zr, Mg, Mn, Ru, Pt, Re, Ce, La and Th.

15. The process of any of paragraphs 1 to 14, wherein in step 5) the fischer-tropsch synthesis reaction is carried out at a temperature of from 180 to 380 ℃ and a pressure of from 0.5 to 6.0 MPaG.

16. The method as set forth in any one of paragraphs 1 to 15, wherein, in step 5), the temperature of the decarbonized tail gas is 20 to 100 ℃, and the pressure is 1.5 to 5.0 MpaG.

17. The method of any of paragraphs 1-16, wherein in step 6), the following is performed in the oil processing plant: hydrorefining at 220-350 ℃ and 7.0-8.5 MpaG, hydroupgrading at 300-400 ℃ and 7.1-8.5 MPG, and catalytic cracking at 300-750 ℃ and 0.1-0.5 MpaG.

18. The method as recited in any of paragraphs 1-17, wherein in step 7), the following is performed in the gasoline plant: isomerization reaction is carried out at the temperature of 80-150 ℃ under the condition of 2.0-6.0 MpaG, and polymerization reaction is carried out at the temperature of 50-90 ℃ under the condition of 2.0-5.5 MpaG.

19. A system for implementing the method of any of paragraphs 1-18, wherein the system comprises:

the coal water slurry gasification device and the crushed coal gasification device are arranged in parallel;

a purification device fluidly connected to the coal-water slurry gasification device;

an oil synthesis device fluidly connected to the purification device;

a natural gas and methanol unit fluidly connected to the crushed coal gasification unit, the purification unit, and the oil synthesis unit;

an oil processing plant connected in fluid communication to the oil synthesis plant and the natural gas and methanol plant; and

a gasoline device fluidly connected to the oil processing device, the crushed coal gasification device, and the natural gas and methanol device.

20. The system of paragraph 19 wherein the system further comprises a sulfur recovery and sulfuric acid unit, the sulfur recovery and sulfuric acid unit being fluidly connected to the coal-water slurry gasification unit, the purification unit, and the crushed coal gasification unit.

The following examples are merely illustrative of the aspects of the present invention and are not intended to limit the scope of the invention in any way.

Examples

Example 1

Raw material powder coal 1830.9t/hr, biochemical sludge 24.49t/hr and oxygen 98.1 ten thousand Nm³The coal water slurry is gasified in a powder coal gasification device at 6.5MPaG and 1280 deg.C to obtain 701.5 ten thousand Nm³The pressure of the raw synthesis gas is 6.35MPaG, the temperature is 217 ℃, the waste water is 16t/hr, the waste residue is 201t/h, the filter cake is 117.4t/hr and the acid gas; through detection, the main components of the crude synthesis gas are CO and H₂、CH₄And also contains H₂S、CO₂Organic sulfur and the like. The crude synthesis gas was subjected to CO shift at 260 ℃ and low temperature methanol wash at-40 ℃ in a purification unit to yield 287.2 ten thousand Nm³Purifying synthesis gas (pressure of 3.3 MPaG; temperature of 40 deg.C; H/C ratio of 1.4) 2867.7t/hr₂And 105 ten thousand Nm³The exhaust gas was/hr (pressure 0.01 MPaG; temperature 15 ℃); the main component of the exhaust gas is CO through detection₂、N₂While also containing a small amount of H₂CO, Ar, etc.

Raw material lump coal 700t/hr and oxygen 17.6 ten thousand Nm³/hr, medium pressure steam 566.3t/hr and 19 ten thousand Nm from the purification plant³CO/hr₂(Medium pressure steam reduced by about 35%) was subjected to pressure gasification at 1200 ℃ in a crushed coal gasification apparatus at 4.2MPaG to obtain 82.6 ten thousand Nm³The method comprises the steps of (1) purifying/hr crushed coal gas (the pressure is 3.7 MPaG; the temperature is 40 ℃, the mole percentage content of methane is 18.89%), 7.2t/hr naphtha, 2.8t/hr liquefied petroleum gas, 8.3t/hr polyphenol, 17.1t/hr diesel oil, 29.2t/hr ammonia water, 94.2t/hr waste residue, 631.7t/hr waste water, acid gas and expansion gas.

Acid gas from pulverized coal gasification apparatus and purification apparatus, and crushed coal gasification apparatusAcid gas and expanding gas of 0.6 ten thousand Nm³The oxygen per hr is treated by sulfur recovery and sulfur device to obtain 14.6t/hr sulfur and 3.7t/hr concentrated sulfuric acid.

Cleaning the crushed coal from the crushed coal gasification unit with a clean gas and CO from the remainder of the cleaning unit₂Cryogenic separation at 3.0MPaG and-170 deg.C in natural gas and methanol plant and methanol synthesis at 4.5MPaG and 380 deg.C to obtain 45.2 ten thousand Nm³Purified gas/hr, naphtha 25.8t/hr, methanol 95.6t/hr, liquefied natural gas 161.5t/hr, liquefied petroleum gas 30t/hr, and 32.1 ten thousand Nm³The hydrogen gas and tail gas, wherein the tail gas is used as fuel and is merged into a fuel gas pipe network.

The purified synthesis gas from the purification device, the purified gas from the natural gas and methanol device and the hydrogen from the pipe network adopt an Fe-based catalyst (composed of alpha-Fe with the mass ratio of 95:4.8:0.5:0.5: 20) under the conditions of 3.3MPa and 270 ℃ in the oil product synthesis device₂O₃、Fe₃O₄、La₂O₃CuO and K₂O) to produce 163.6t/hr light oil, 219t/hr heavy oil, 208.7t/hr qualified wax, 755.1t/hr synthetic water and 225.4t/hr decarbonized tail gas (the pressure is 3.3 MPaG; temperature 76 ℃); through detection, the main component of the decarbonization tail gas is H₂、CO₂、CO、N₂、CH₄And also includes small amounts of hydrocarbons. And sending the decarbonized tail gas into a natural gas and methanol device for treatment.

Naphtha and partial methanol from a natural gas and methanol device and light oil, heavy oil, qualified wax, synthetic water from an oil product synthesis device and hydrogen from a pipe network are subjected to hydrofining in an oil product processing device at the temperature of 8.0MPaG and 260 ℃, hydrogenation modification is carried out at the temperature of 8.0MPaG and 340 ℃, and catalytic cracking is carried out at the temperature of 0.1MPaG and 500 ℃, so as to obtain 55.2t/hr blended diesel oil product, 227.1t/hr gasoline product, 136.8t/hr naphtha, 137.6t/hr liquefied petroleum gas, 22.1t/h heavy diesel oil, 68.5t/h liquid paraffin, processing dry gas, mixed alcohol and synthetic wastewater.

Liquefied petroleum gas and residual methanol from natural gas and methanol plant, from crushed coal gasificationNaphtha and liquefied petroleum gas of the device, naphtha and liquefied petroleum gas from an oil product processing device are subjected to isomerization reaction at 120 ℃ and polymerization reaction at 70 ℃ under 3.4MPa in a gasoline device to obtain 244.5t/hr gasoline, 64.6t/hr polypropylene and 3.4 ten thousand Nm & lt/EN & gt³Hydrogen/hr and reformed dry gas. And sending the processing dry gas and the reforming dry gas into a natural gas and methanol device for treatment.

The obtained hydrogen returns to a pipe network and is supplied to a gasoline device, an oil product synthesizing device and an oil product processing device to participate in reaction.

Comparative example 1

Raw material powder coal 1830.9t/hr, biochemical sludge 24.49t/hr and oxygen 98.1 ten thousand Nm³The coal water slurry is gasified in a powder coal gasification device at 6.5MPaG and 1280 deg.C to obtain 701.5 ten thousand Nm³The pressure of the raw synthesis gas is 6.35MPaG, the temperature is 217 ℃, the waste water is 16t/hr, the waste residue is 201t/h, the filter cake is 117.4t/hr and the acid gas; through detection, the main components of the crude synthesis gas are CO and H₂、CH₄And also includes H₂S、CO₂Organic sulfur and the like. The crude synthesis gas was subjected to CO shift at 260 ℃ and low temperature methanol wash at-40 ℃ in a purification unit to yield 287.2 ten thousand Nm³Purifying synthesis gas (pressure of 3.3 MPaG; temperature of 40 deg.C; H/C ratio of 1.4) 2867.7t/hr₂And 105 ten thousand Nm³The exhaust gas was/hr (pressure 0.01 MPaG; temperature 15 ℃); the main component of the exhaust gas is CO through detection₂、N₂While also containing a small amount of H₂CO, Ar, etc.

Raw material lump coal 736.4t/hr and oxygen 17.6 ten thousand Nm³Pressure gasification is carried out on/hr and medium pressure steam 870.8t/hr in a crushed coal gasification device under the conditions of 4.2MPaG and 1200 ℃, and 82.6 ten thousand Nm is obtained after purification³The method comprises the steps of (1) purifying gas of/hr crushed coal (the pressure is 3.7MPa, the temperature is 40 ℃, the mole percentage content of methane is 18.89 percent), naphtha of 7.6t/hr, liquefied petroleum gas of 2.9t/hr, polyphenol of 8.7t/hr, diesel oil of 18t/hr, ammonia water of 30.7t/hr, waste residue of 99.1t/hr, 905.4t/hr waste water, acid gas and expansion gas.

Acid gas from pulverized coal gasification apparatus and cleaning apparatus, acid gas and expanded gas from crushed coal gasification apparatus, and 0.6 ten thousand Nm³The oxygen gas of/hr is processed by sulfur recovery and sulfur device to obtain sulfur of 14.6t/hr and concentrated sulfuric acid of 3.7 t/hr.

Cleaning the crushed coal from the crushed coal gasification unit with a clean gas and CO from the remainder of the cleaning unit₂Cryogenic separation at 3.0MPaG and-170 deg.C in natural gas and methanol plant and methanol synthesis at 4.5MPaG and 380 deg.C to obtain 45.2 ten thousand Nm³Purified gas/hr, naphtha 26.2t/hr, methanol 95.6t/hr, liquefied natural gas 161.5t/hr, liquefied petroleum gas 30.2t/hr, and 32.1 ten thousand Nm³The hydrogen gas and tail gas, wherein the tail gas is used as fuel and is merged into a fuel gas pipe network.

The purified synthesis gas from the purification device, the purified gas from the natural gas and methanol device, and the hydrogen gas from the pipe network in the oil product synthesis device are processed by using Fe-based catalyst (composed of alpha-Fe with the mass ratio of 95:4.8:0.5:0.5: 20) at 3.3MPaG and 270 DEG C₂O₃、Fe₃O₄、La₂O₃CuO and K₂O) to produce 163.6t/hr light oil, 219t/hr heavy oil, 208.7t/hr qualified wax, 755.1t/hr synthetic water and 225.4t/hr decarbonized tail gas (the pressure is 3.3 MPaG; temperature 76 ℃); through detection, the main component of the decarbonization tail gas is H₂、CO₂、CO、N₂、CH₄And also includes small amounts of hydrocarbons. And sending the decarbonized tail gas into a natural gas and methanol device for treatment.

Naphtha and partial methanol from a natural gas and methanol device and light oil, heavy oil, qualified wax, synthetic water from an oil product synthesis device and hydrogen from a pipe network are subjected to hydrofining in an oil product processing device at the temperature of 8.0MPaG and 260 ℃, hydrogenation modification is carried out at the temperature of 8.0MPaG and 340 ℃, and catalytic cracking is carried out at the temperature of 0.1MPaG and 500 ℃, so as to obtain 55.2t/hr blended diesel oil product, 227.1t/hr gasoline product, 136.8t/hr naphtha, 137.2t/hr liquefied petroleum gas, 22.1t/h heavy diesel oil, 68.5t/h liquid paraffin, processing dry gas, mixed alcohol and synthetic wastewater.

The liquefied petroleum gas and residual methanol from the natural gas and methanol plant, naphtha and liquefied petroleum gas from the crushed coal gasification plant, naphtha and liquefied petroleum gas from the oil product processing plant are subjected to isomerization reaction at 120 ℃ and polymerization reaction at 70 ℃ and 3.4MPa in the gasoline plant to obtain 245t/hr gasoline, 64.6t/hr polypropylene and 3.4 ten thousand Nm³Hydrogen/hr and reformed dry gas. And sending the processing dry gas and the reforming dry gas into a natural gas and methanol device for treatment.

The obtained hydrogen returns to a pipe network and is supplied to a gasoline device, an oil product synthesizing device and an oil product processing device to participate in reaction.

Comparative example 2

Coal-based synthetic oil was prepared and LNG was co-produced according to the method shown in example 3 of CN105176566A, the relevant parameters of which were compared with example 1 of the present invention and are shown in table 1 below.

Table 1: comparison of example 1 and comparative example 2

Table 2: comparison of example 1 and comparative example 1

Note: table 1 and table 2 are compared to the same gas production data.

As can be seen by comparison of the above tables, CO is added during the crushed coal gasification step₂The amount of externally supplied steam required by the raw materials can be reduced by about 35 percent, and the amount of wastewater produced per ton of coal is reduced by about 30 percent. Calculated according to the steam price of 100 yuan/ton and the pretreatment cost of 30 yuan/ton of wastewater, 38662 yuan can be saved per hour, and about 3.1 yuan can be saved per 8000 hours per year.

There are, of course, many other embodiments of the invention and modifications and variations which will be apparent to those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.