CN112457159A

CN112457159A - Device for preparing methanol based on coal and methanol preparation process

Info

Publication number: CN112457159A
Application number: CN201910856860.8A
Authority: CN
Inventors: 李�灿; 王集杰; 姚婷婷; 李军
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2019-09-09
Filing date: 2019-09-09
Publication date: 2021-03-09

Abstract

The present application discloses a device for preparing methanol based on coal and a methanol preparation process using the device. The device includes: (1) an electrolysis water unit; (2) a coal gasification unit, including a pulverized coal preparation device, a pulverized coal gasification device and a purification device; (3) a gas adjustment unit, including a detection unit, a mixing container and a regulating valve , wherein the detection unit is connected with the mixing container and the purification device of the coal gasification unit; the regulating valve is connected with the mixing container and the hydrogen pipeline of the water electrolysis unit; (4) methanol synthesis reaction zone, with The mixing vessels are connected. By using the device and process of the invention, the energy consumption of the coal chemical process can be reduced to the greatest extent, the utilization efficiency of coal resources can be greatly improved, and the low-carbon or even zero-carbon emission process in the coal chemical process can be realized. To achieve the dual benefits of energy saving and environmental protection, to achieve sustainable development and ecological civilization construction.

Description

Device for preparing methanol based on coal and methanol preparation process

Technical Field

The application relates to a device for preparing methanol based on coal and a methanol preparation process, and belongs to the field of preparing liquid fuel by carbon dioxide hydrogenation.

Background

The general structure of Chinese energy is the current situation of more coal, poor oil and less gas. At present, the main body of energy consumption in China is still fossil energy. Coal is used as basic energy for supporting the development of the economic society of China, the proportion of the coal occupying primary energy consumption is maintained at about 60%, and the proportion is estimated to be reduced to about 40% in 2050. Therefore, how to effectively and scientifically utilize the coal resources of China and reduce the carbon dioxide emission to the maximum extent is a key problem in realizing sustainable development and building ecological civilization, and is not only related to the safety of the energy strategy of the people.

At present, the important approach for clean and efficient utilization of coal is coal chemical industry, and the main mode is coal gasification for preparing synthesis gas. The basic reaction principle is shown in chemical formulas (1) and (2): coal, steam and oxygen are first gasified at a certain temperature and then the carbon-hydrogen ratio is adjusted by reaction with steam, the so-called synthesis gas. Depending on the hydrocarbon ratio of the synthesis gas, it can be used in a series of bulk chemical syntheses, such as coal-to-synthesis gas for the synthesis of methane, methanol, ethanol, and synthetic oils, among others.

3C+3/2O₂→3CO (1)

2CO+2H₂O→2H₂+2CO₂ (2)

The coal-to-synthesis gas is used as a core link of coal chemical industry, and due to the inherent thermodynamic principle limitation, the problem of low utilization efficiency of carbon resources exists, the total packet reaction of the coal-to-methanol is shown in chemical formula (3), taking 60 ten thousand tons of methanol produced every year as an example, about 30 ten thousand tons of coal are needed, and actually 90 ten thousand tons of coal are needed, wherein about 60 ten thousand of coal are used for producing hydrogen by water gas shift, and are finally converted into CO₂And discharging.

3C+3/2O₂+H₂O＝CH₃OH+2CO₂ (3)

The gasification of coal (chemical formula 1) requires the establishment of a corresponding air separation unit to separate oxygen for the gasification of coal. The air separation device has large investment and high energy consumption, and approximately accounts for 10-12% of the overall investment of the coal-to-methanol process. The water gas change (chemical formula 2) is usually completed under the harsh (5MPa, 320-550 ℃) condition, and the energy consumption is very high. Therefore, the coal chemical industry is taken as an important way for clean and efficient utilization of coal resources, the pertinence of low utilization rate of the carbon resources of the coal chemical industry cannot be overcome, and meanwhile, the whole process is high in energy consumption and large in water consumption.

At present, the coal resources of China are mainly distributed in the areas of North China, northwest China and southwest, most areas with rich coal resources are just the dominant areas of renewable energy development of China, for example, the areas in the northwest have rich wind power and solar energy resources, and the areas in the southwest have rich hydraulic resources. The alternative complementation of renewable energy and traditional fossil energy, especially the combination of new energy and coal chemical industry, will be the future direction. One important way is to use renewable energy sources to electrolyze water and decompose water to generate hydrogen to adjust the carbon-hydrogen ratio in the coal chemical industry process, thereby avoiding the water gas change process and reducing CO₂(ii) a problem of emissions; on the other hand, the high-purity oxygen generated by electrolyzing water realizes the coal gasification process and replaces the air separation process in the traditional coal chemical industry.

At present, hydrogen production scale of thousands of cubes per hour can be realized by industrial alkaline electrolysis of water, and the requirement of large-scale catalytic hydrogenation reaction can be met, but the technology also faces the problem of high energy consumption of unit hydrogen production, and the economy of hydrogen utilization and deep conversion is directly limited. Cheap and efficient water decomposition catalysts are introduced into the current industrial alkaline water electrolysis equipment to reduce reaction overpotential, directly reduce unit hydrogen production energy consumption and cost, and are beneficial to promoting the wide utilization of water electrolysis for preparing hydrogen. The energy efficiency of the electrolyzed water is improved to more than 80 percent from about 50 percent in the past recently, and a solid technical foundation is provided for realizing the combination of the new energy and the old energy.

Therefore, the renewable energy is combined with the traditional coal resources, and the coal chemical industry capacity with low carbon and even zero carbon emission can be realized. The method provides high-efficiency utilization of carbon resources, and has important significance for economic sustainable development and social ecological construction in China.

Disclosure of Invention

In order to solve the problems of the prior art, an aspect of the present invention provides an apparatus for preparing methanol based on coal, the apparatus comprising:

(1) an electrolytic water unit;

(2) the coal gasification unit comprises a coal powder preparation device, a coal powder gasification device and a purification device;

(3) the gas regulating unit comprises a detection unit, a mixing container and a regulating valve,

wherein the detection unit is connected with the mixing container and a purification device of the coal gasification unit;

the regulating valve is connected with the mixing container and a hydrogen pipeline of the water electrolysis unit;

(4) and the methanol synthesis reaction zone is connected with the mixing container.

In a preferred embodiment, the electrolytic water unit electrolyzes water to generate hydrogen and oxygen.

In a preferred embodiment, the electrolyzed water unit comprises an electrolyzed water device, an oxygen compressor and a hydrogen compressor, wherein the oxygen compressor is connected with the coal gasification unit, and the hydrogen compressor is connected with the gas regulating unit through a hydrogen pipeline.

The detection unit is used for detecting the carbon-hydrogen ratio of the crude gas.

The regulating valve is used to supply hydrogen gas at a specific hydrocarbon ratio.

In a preferred embodiment, the electricity of the electrolytic water unit is generated by renewable energy, preferably, the renewable energy comprises at least one of wind power generation, hydroelectric power generation and photovoltaic power generation.

Another aspect of the present invention provides a methanol preparation process using the above coal-based methanol preparation apparatus, the process at least comprising the steps of:

(1) producing hydrogen and oxygen by electrolyzing water in an electrolytic water unit;

(2) supplying oxygen to the coal gasification unit for providing oxygen for coal gasification;

(3) detecting the carbon-hydrogen ratio of the raw gas by using a detection unit, and adjusting the carbon-hydrogen ratio of the raw gas by using an adjusting valve to control the supply of hydrogen;

(4) and (4) in a methanol synthesis reaction zone, synthesizing methanol according to the carbon-hydrogen ratio adjusted in the step (3).

In a preferred embodiment, the hydrogen-carbon ratio after adjustment is 2.0-2.5, the carbon is a mixture of carbon monoxide and carbon dioxide, and the volume of the carbon monoxide accounts for more than 85% v/v of the mixture.

In a preferred embodiment, the electrolyzed water is catalyzed with a nickel-iron catalytic material comprising a nickel metal substrate and a catalytically active layer containing iron and nickel elements.

In a preferred embodiment, the catalytically active layer is attached to the surface of the nickel metal substrate.

In a preferred embodiment, the nickel substrate is selected from at least one of a nickel sheet, a nickel wire mesh, a nickel foam, or a nickel powder.

In a preferred embodiment, the nickel iron catalytic material is prepared by the steps of:

immersing a nickel metal substrate in a solution containing iron ions and standing;

and (3) washing, drying and treating at the temperature of 100-400 ℃ in a hydrogen atmosphere to obtain the ferronickel catalytic material.

In a preferred embodiment, the catalyst for methanol synthesis is selected from the group consisting of CuOZnOAl₂O₃、ZnOZrO₂、In₂O₃ZrO₂、CdOZrO₂、ZnOCr₂O₃、In₂O₃Cr₂O₃And CdCor₂O₃At least one of them, the synthesis temperature is 200-400 ℃.

The beneficial effects that this application can produce include:

1. the water electrolysis catalyst used in the invention can ensure that the energy conversion efficiency exceeds 80 percent and is far higher than the efficiency of 50 to 60 percent of the traditional industrial water electrolysis, thereby reducing the energy consumption of the coal chemical process to the maximum extent.

2. The electrolyzed water generates hydrogen and oxygen, the high-purity oxygen (> 99.9%) generated by the electrolyzed water is used for the coal gasification process, an air separation device in the traditional coal gasification process is saved, the hydrogen is used for adjusting the carbon-hydrogen ratio of the raw coal gas, and the water gas conversion process with high energy consumption can be saved.

3. The carbon-hydrogen ratio is not adjusted in the water gas conversion process, so that the utilization efficiency of coal resources is greatly improved, and the low-carbon and even zero-carbon emission process in the coal chemical industry process is realized. The double benefits of energy saving and environmental protection are achieved, and sustainable development and ecological civilization construction are realized.

Drawings

Fig. 1 is a schematic diagram of a coal-based methanol plant in one embodiment of the present application.

Description of the reference numerals

1. An electrolytic water unit 2, an oxygen storage tank 3, a hydrogen storage tank 4, an oxygen compressor 5, a hydrogen compressor 6, a coal gasification unit 7, a purification device 8, a detection unit 9, a regulating valve 10, a mixing container 11, a compressor 12 and a methanol synthesis reaction area

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

Example 1

A photovoltaic power station with the electric quantity of 15MW/h is used as an electrolyzed water unit for electrolyzing water to produce hydrogen and oxygen, and compared with the energy consumption of the traditional industrial electrolyzed water catalyst process, the results are shown in Table 1. As can be seen from Table 1, under the condition close to industrial operation, compared with the traditional nickel mesh catalyst, the energy efficiency of the nickel-iron mesh catalyst is increased from 60% to 83%, and the energy consumption of water electrolysis is greatly reduced.

TABLE 1

^x: the energy efficiency is obtained according to the following method: the enthalpy of combustion of hydrogen per cubic meter is the energy of hydrogen, and is about 1.28 x 10⁴kJ, the energy efficiency is 1.28 × 10 [ ]⁴X 100/(per cubic hydrogen power consumption X3600)

Example 2

The productivity is 60 ten thousand tons/year methanolFor example, the crude gas yield is 18.8 km³The hydrogen-carbon ratio after traditional coal gasification is generally 0.2-0.6, the hydrogen-carbon ratio is calculated as 0.45, and the carbon-hydrogen ratio of the synthesis gas for synthesizing the methanol is calculated as 2.1. By comparing the two processes, it can be seen that hydrogen production in the coal chemical process is carried out by the water gas shift process as shown in Table 2, and in this example, it can be seen that there is CO produced by the water gas shift₂Is 608 ten thousand Nm³At the same time, about 196Nm is generated in the coal gasification process³/h CO₂Total 804Nm³/h CO₂. While the CO actually used for methanol synthesis is 546Nm³The utilization rate of the carbon resource is about 40.4 percent.

TABLE 2

Methanol was synthesized using a coal-based methanol plant as shown in fig. 1.

First, oxygen gas and hydrogen gas are produced in the electrolytic water unit 1, and the produced oxygen gas and hydrogen gas are stored in the oxygen storage tank 2 and the hydrogen storage tank 3, respectively. The oxygen compressor 4 is connected to the coal gasification unit 6 for supplying oxygen during coal gasification. The purification unit 7 may be provided outside the coal gasification unit 6 or may be provided therein (not shown). The purification unit 7 is used for purifying the gas discharged from the coal gasification unit 6. The detection unit 8, the regulating valve 9 and the mixing container 10 together constitute a gas regulating unit. Wherein, the detection unit 8 is connected with the purification device 7 and the mixing container 10 and is used for detecting the carbon-hydrogen ratio of the crude gas. The hydrogen compressor 5 is connected with the regulating valve 9, and the regulating valve 9 is used for regulating the carbon-hydrogen ratio in the raw gas. The synthesis gas in the mixing vessel 10 is sent to a methanol synthesis reaction zone by a compressor 11 to synthesize methanol.

The hydrogen to carbon ratio was adjusted by electrolysis of water as a renewable energy source as shown in table 3, since hydrogen comes from renewable energyEnergy electrolytic water production without water gas shift process, thus 608Nm corresponding to water gas shift of coal chemical process³CO of/h₂It will not occur. Meanwhile, due to the hydrogen production by the electrolysis of water, 196.6Nm is produced in the coal gasification process by properly adjusting the proper hydrogen-carbon ratio³CO of/h₂Used as a feedstock for methanol. Therefore, the process is low-carbon and even zero-carbon emission, and the utilization rate of carbon resources is close to 100%.

TABLE 3

Example 3

It can be seen from example 3 that, through the comparison of the investment and energy consumption under different process conditions, the total investment of the traditional coal chemical industry route is 60.95 hundred million RMB, and when the electricity price of the electrolyzed water matching process is 1 yuan/degree, the total investment cost and the energy consumption are still saved by 3.3 hundred million compared with the traditional coal chemical industry process, and the price is already the price of the current industrial electricity. Considering that the renewable energy is utilized on the spot in partial areas to generate electricity, the electricity price is expected to be further reduced without a grid-connected approach, and when the electricity price is 0.6 yuan/degree, the whole investment and energy consumption can save 14 hundred million RMB. While taking into account the fact that₂The obvious effect of emission reduction shows that the route has important economic value and important social significance.

TABLE 4

Remarking: a. coal price is calculated according to 500 yuan/ton

b. Considering partial hydrogen in the gasification of the raw gas, the hydrogen supply of the electrolyzed water is calculated according to 80 percent of the total required hydrogen amount, and the energy consumption of the hydrogen of the electrolyzed water is calculated according to 4.2 degrees of electricity/m³H₂Estimating

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Claims

1. a device for preparing methanol based on coal, is characterized in that, described device comprises:

(1) Electrolyzed water unit;

(2) Coal gasification unit, including pulverized coal preparation device, pulverized coal gasification device and purification device;

(3) Gas regulating unit, including detection unit, mixing container and regulating valve,

Wherein, the detection unit is connected with the mixing container and the purification device of the coal gasification unit;

The regulating valve is connected with the mixing container and the hydrogen pipeline of the water electrolysis unit;

(4) methanol synthesis reaction zone, which is connected with the mixing vessel.

2. The device for preparing methanol based on coal according to claim 1, wherein the water electrolysis unit comprises a water electrolysis device, an oxygen compressor and a hydrogen compressor, and the oxygen compressor is connected with the coal gasification unit, so that the The hydrogen compressor is connected to the gas adjustment unit through a hydrogen pipeline.

3. The device for preparing methanol based on coal according to claim 1, wherein the electricity of the water electrolysis unit comes from renewable energy power generation;

Preferably, the renewable energy power generation includes at least one of wind power generation, hydropower generation, and photovoltaic power generation.

4. A methanol preparation process using the device for preparing methanol based on coal according to any one of claims 1 to 3, wherein the process at least comprises the following steps:

(1) Hydrogen and oxygen are prepared by electrolyzing water in the water electrolysis unit;

(2) supplying oxygen to the coal gasification unit for providing oxygen during coal gasification;

(3) use the detection unit to detect the carbon-hydrogen ratio of the crude gas, and use the regulating valve to adjust the carbon-hydrogen ratio in the crude gas to control the supply of hydrogen;

(4) In the methanol synthesis reaction zone, methanol is synthesized with the proportion of carbon and hydrogen adjusted in step (3).

5. The methanol preparation process according to claim 4, wherein the adjusted hydrogen-to-carbon ratio is 2.0 to 2.5, and the carbon is a mixture of carbon monoxide and carbon dioxide, wherein the volume of carbon monoxide accounts for 85% v/ v above.

6 . The methanol preparation process according to claim 4 , wherein the electrolyzed water is catalyzed by a nickel-iron catalytic material, and the nickel-iron catalytic material comprises a nickel metal base and a catalytically active layer containing iron and nickel. 7 .

7 . The methanol preparation process according to claim 6 , wherein the catalytically active layer is attached to the surface of the nickel metal substrate. 8 .

8. The methanol preparation process according to claim 7, wherein the nickel substrate is selected from at least one of nickel sheet, nickel wire mesh, foamed nickel or nickel powder.

9. methanol preparation technology according to claim 6, is characterized in that, described nickel-iron catalytic material is prepared by following steps:

Immerse the nickel metal substrate in a solution containing iron ions and let it stand;

The nickel-iron catalytic material is obtained by washing, drying, and treating at a temperature of 100-400° C. in a hydrogen atmosphere.

10. The methanol preparation process according to claim 4, wherein the catalyst for methanol synthesis is selected from CuOZnOAl ₂ O ₃ , ZnOZrO ₂ , In ₂ O ₃ ZrO ₂ , CdOZrO ₂ , ZnOCr ₂ O ₃ , In ₂ O ₃ At least one of Cr ₂ O ₃ and CdOCr ₂ O ₃ , and the synthesis temperature is 200-400°C.