Popular science of the hottest fuel cell series

2022-08-17
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Fuel cell series popular science

China's fuel cell infrastructure construction has entered an accelerated period, making full preparations for the commercialization of fuel cell vehicles. Hydrogenation infrastructure is an important guarantee for the development of fuel cells. The low-cost transportation of hydrogen is also a problem that needs to be solved. The source of high-purity hydrogen suitable for fuel cell vehicles is also an important problem

this paper will mainly introduce the preparation process of hydrogen, the necessary material of fuel cell, and analyze and compare the advantages and disadvantages of different methods

thinking questions:

1. What are the methods of industrial hydrogen production, and what are their principles

2. What are the advantages and disadvantages of each method? What is the optimal adaptation

important conclusion

industrial hydrogen production includes many methods, but they all have their own advantages and limitations. Considering the advantages, disadvantages and costs of current industrial hydrogen production methods, if there are abundant coke oven gas resources near hydrogen plants, coke oven gas hydrogen production technology is the preferred process technology scheme. In the current practice of hydrogen for fuel cell vehicles in China, the technology of hydrogen production from coke oven gas is also the first choice. However, hydrogen production from coke oven gas is seriously limited by coke oven gas resources. In the future energy structure adjustment, the output of coke oven gas will decline and the demand for hydrogen will soar. At that time, it will be difficult for coke oven gas to produce hydrogen. Therefore, at present, there is no best scheme for industrial hydrogen production, which still needs to be developed

1. There are many industrial hydrogen production methods

hydrogen is not only an important industrial raw material and reductant, but also a necessary fuel for fuel cells. With the promotion and popularization of fuel cells, fuel cell vehicles have entered the mature market, and the consumption of hydrogen will also increase at an alarming rate. At present, there are mainly several methods for industrial hydrogen production: one is to use fossil fuels to produce hydrogen; The second is to extract hydrogen from chemical by-products; The third is to use methanol and methane from biology to produce hydrogen, and the fourth is to use natural energy such as solar energy and wind energy for water electrolysis

1.1 hydrogen production from fossil fuels

hydrogen production from fossil fuels is a traditional method of hydrogen production and an old process of hydrogen production, but it is still inseparable from the dependence on fossil fuels, and it will emit greenhouse gases such as carbon dioxide, which will reduce the environmental protection value of fuel cells. The fossil fuel commonly used for hydrogen production is natural gas. The process of hydrogen production from natural gas is: under certain pressure, high temperature and catalyst, alkanes in natural gas react with water vapor. After heat exchange in the boiling pot, the converted gas enters the shift furnace to convert C0 into H2 and CO2. After heat exchange, condensation and steam water separation, the gas is sequentially passed through the adsorption tower equipped with three specific adsorbents through program control, and N2, Co, CH4 and CO2 are pressurized and adsorbed by pressure swing adsorption (PSA) to extract product hydrogen

1.2 hydrogen production from industrial by-products

coke oven gas hydrogen production technology uses a pressure swing adsorption process to extract pure hydrogen from coke oven gas, a by-product of the coking industry. Its basic principle is to realize the separation and absorption of gas mixture by using the selective adsorption of solid adsorbent on gas and the characteristic that the adsorption amount of gas on adsorbent decreases with the decrease of its partial pressure. Versalis and Pirelli tire signed a memorandum of understanding (MOU) on March 19, 2013 to regenerate the adsorbent, so as to achieve the purpose of hydrogen purification and production

1.3 hydrogen production from biological raw materials

the process of hydrogen production from methanol cracking is that methanol and demineralized water are mixed in a certain proportion, and the mixture steam is heated to about 270 ℃. Under the action of catalyst (Cu Zn Al) or (Cu Zn CR), catalytic cracking and conversion reactions occur

1.4 hydrogen production from electrolytic water

hydrogen can also be obtained by the traditional electrolytic water method, but due to the high energy consumption of this method, there are few new units except the built units

2. The advantages and disadvantages of each method are different, meeting different needs

it can be seen from the above methods that there are many ways to produce hydrogen in industry. However, at present, these methods have their own advantages and limitations

both natural gas hydrogen production and coke oven gas hydrogen production are suitable for large-scale hydrogen production, but they are also limited by the supply of raw materials and are polluting. In terms of environmental protection, although the hydrogen production from coke oven gas is a by-product of coking, it cannot remove the pollutants therein, and the hydrogen production from natural gas still requires fossil fuels as raw materials. In contrast, methanol cracking for hydrogen production has the characteristics of low investment, fast construction and no pollution, and methanol can be more flexible as raw material, but it is difficult to produce hydrogen on a large scale

once fuel cells become the main force of energy in the future, the requirements for hydrogen production capacity will increase day by day. Therefore, hydrogen production from natural gas and coke oven gas is difficult to get rid of the dependence on fossil raw materials, and the scale of hydrogen production from methanol is likely to be difficult to meet the growing demand

from the perspective of economy, the cost of hydrogen production largely depends on the cost of raw materials, which fluctuates significantly with the price of raw materials. In terms of the current raw material price level, the cost of hydrogen production from coke oven gas and natural gas is lower. At present, the price of non civil natural gas is gradually marketized. On November 18, 2015, the national development and Reform Commission announced to reduce the price of natural gas valve stations for non residents by 0.7 yuan per cubic meter. At present, the price of non civil natural gas is about 2.7 to 3.0 yuan/m3, and the cost of hydrogen production is about 1 7 yuan/km3. Coke oven gas is a by-product produced in the coking process of coking enterprises. Originally, it was discharged at high altitude after being burned as fuel. Now when it is used as chemical raw materials, the price is generally lower than 0.4 yuan/m3. Therefore, the cost of hydrogen production from coke oven gas can be lower than 1.39 yuan/km3, which is lower than that from natural gas. In June 2016, the average price of methanol was 1860 yuan/t, so the cost of hydrogen production will exceed 1.37 yuan/km3. Due to the high price fluctuation of methanol, its economy has no absolute advantage over hydrogen production from natural gas. In terms of the current prices of various raw materials, the economy of hydrogen production from coke oven gas is relatively significant

considering the advantages, disadvantages and costs of current industrial hydrogen production methods, if there are abundant coke oven gas resources near hydrogen plants, coke oven gas hydrogen production technology is the preferred process technology scheme. Considering the requirements of hydrogen production scale, natural gas hydrogen production technology is also the preferred scheme when natural gas resources can be obtained. The cost of hydrogen production from methanol cracking fluctuates greatly, and the scale of hydrogen production is small, but the unit cost is low, so it is suitable for intermittent and supplementary hydrogen production

from the current practice of hydrogen for fuel cell vehicles in China, hydrogen production from coke oven gas is also the first choice. The "863" electric vehicle undertaken by Tongji University and others will consolidate and improve the share of enterprises in the western market. The fuel hydrogen used in the junior college fuel cell car project is all purified from coke oven gas

however, hydrogen production from coke oven gas is seriously limited by coke oven gas resources. In the future energy structure adjustment, the output of coke oven gas will decline and the demand for hydrogen will soar. At that time, it will be difficult to continue to use coke oven gas to produce hydrogen. Therefore, at present, there is no best plan for industrial hydrogen production in the fields of metallurgy, textiles, automobiles, colleges and universities, and it still needs to be developed

3. Summary

according to the current situation, the cost of hydrogen production is relatively low, and the relatively mature technology is coal coke oven hydrogen production. However, with the advancement of technology and the further promotion of new energy power generation, hydrogen production from electrolytic water will be a lower cost technology in the future

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