Since the goal of "carbon peak and carbon neutralization" was put forward, the new energy industry centered on renewable energy has stepped up its layout, which has contributed to the transformation and upgrading of China's energy structure. The goal of double carbon urges China to speed up the construction of new energy system, and also urges hydrogen energy enterprises to step up the pace of horse race enclosure.
In terms of hydrogenation, the construction of domestic hydrogenation stations has entered the stage of "rolling up sleeves and refueling dry". According to the special plan for the development of hydrogen energy industry in various provinces and cities, by 2025, the number of hydrogenation stations in China will exceed 700.
Overall planning of hydrogenation network adheres to demand-oriented, overall layout and construction of hydrogenation stations, and orderly promotion of hydrogenation network system construction. Adhere to the principle of safety first, save and intensively use land resources, and support the reconstruction and expansion of hydrogen stations by using the site facilities of existing gas stations in accordance with the law and regulations. To explore new modes of hydrogen production, hydrogen storage and hydrogenation integration in the station. -Medium and Long-term Plan for
the Development of National Hydrogen Energy Industry (2021-2035)
Hydrogen station is an important hydrogen energy infrastructure, and its construction plays a vital role in the large-scale development of China's hydrogen energy industry. However, after the completion of the hydrogenation station, it is difficult to put into operation, difficult to operate, and the problem of "station without car" is common. Many practitioners in the industry said that although China has the largest number of hydrogen stations, they are still not enough for the demand of hydrogen fuel cell vehicles. Many hydrogen stations are "hydrogen free" and can not be used at all, which makes the builders not only spend high construction costs, but also have almost no income. How difficult is the construction of
hydrogen refueling stations? When will the double pressure of cost and technology be broken? Can imbalance between "having a station without a car" and "having a car without a station" be solved? Composition of
hydrogen station equipment There are various forms of hydrogen station construction. According to the hydrogen storage mode, it can be divided into gas hydrogen station and liquid hydrogen station. In China, it is mainly gas hydrogen station. According to the construction mode, there are fixed, skid-mounted and temporary hydrogen stations. In China, it is mainly fixed hydrogen station. In addition, in order to reduce the pressure of hydrogen transportation, some hydrogenation stations are also equipped with hydrogen production systems, that is, integrated hydrogen production and hydrogenation stations. Similar to the existing mature compressed natural gas (CNG) filling station, the
hydrogen filling station is mainly composed of hydrogen production system, compression system, storage system, filling system and control system. Its main equipment includes gas unloading column (hydrogen production and filling station outside the station), compressor, hydrogen storage tank, hydrogen filling machine, pipeline, control system, nitrogen purging device, bleeding device and safety monitoring device, etc. Among these equipments, hydrogen compressor, high-pressure hydrogen storage system, hydrogenation machine and hydrogenation station control system belong to the core equipment and system. After the hydrogen
station obtains hydrogen through external hydrogen supply, it enters the high-pressure hydrogen storage container for storage under the transmission of the hydrogen compressor, and finally fills the fuel cell vehicle through the hydrogenation machine. In this process, the process control system of the hydrogen refueling station plays a vital role, which determines the coordination between the above equipment and the opening and switching of the hydrogen pipeline valves.
Hydrogen compressor
, as the core equipment in the hydrogen station, plays an important role in hydrogen pressurization. At present, hydrogen compressor accounts for 30% of the total construction cost, which is the key to reduce the cost of hydrogen station construction. At present, the hydrogen compressors commonly used in domestic hydrogenation stations are mainly diaphragm compressors, liquid-driven compressors and ionic liquid compressors. Diaphragm compressors and liquid drive compressors are mainly used in hydrogen stations with hydrogen storage pressure not more than 45 MPa, and the related technologies of many domestic manufacturers have become more mature; ionic liquid compressors are mainly used in hydrogen stations with hydrogen storage pressure of 90 MPa, and the domestic compressors with this pressure level are still in the process of development, and at present, they mainly rely on imports.
Due to the thin metal diaphragm, which is extremely sensitive to gas impurities, diaphragm compressors have a high demand on the process gas, which must be free of any solid particle impurities and have a low dew point for trouble-free operation. For the diaphragm compressor, the service life of the metal diaphragm is directly related to the overall maintenance frequency and service life of the compressor. In view of the working characteristics of the diaphragm compressor that it is easy to start and stop frequently, the general diaphragm compressor is not suitable for the working conditions of frequent start and stop of the mobile hydrogen station.
Hydraulically driven oil-free hydrogen reciprocating piston compressor (also known as high-purity oil-free booster hydrogen compressor) uses a large piston to drive a small piston, and amplifies the driving pressure in the same proportion according to the area ratio of the large piston to the small piston, so as to pressurize the pressurized medium.
Liquid drive compressor manufacturing technical barriers are high, for domestic enterprises, there is still a large breakthrough space. It is understood that there is no domestic enterprise that can independently produce liquid drive compressor, but some enterprises have begun to try, and there may be results in the future. The
ionic liquid compressor uses a near-zero vapor pressure liquid as the working medium and lubricating medium to realize the pollution-free compression of hydrogen. The ionic liquid compressor can achieve a reasonable compression ratio and a wide compression range by setting a multi-stage cylinder. The hydraulic drive also improves the overall safety of the system, and the compression efficiency of the entire compression system is about 25% higher than that of a conventional compressor.
Because the manufacturing standards are different from those in China, the import procedures are more complicated, and there are fewer hydrogenation stations using ion compressors in China. Although the advantages of ion compressor are high, its high cost price is also difficult to apply in the current hydrogen station construction. The
high-pressure hydrogen storage system
is equipped with a high-pressure and large-capacity fixed hydrogen storage device in the hydrogen station, which can fill up the vehicle with hydrogen in a short time. In addition, as a buffer device, the hydrogen storage cylinder group can also avoid the frequent startup of the compressor and optimize the operation of the hydrogen filling station. Hydrogen storage pressure, hydrogen storage volume and grading pressure of hydrogen storage device in hydrogen refueling station are its main technical indicators. In order to meet the pressure requirements of 35 MPa and 70 MPa on-board hydrogen storage cylinders, the pressures of high-pressure hydrogen storage devices in hydrogen refueling stations are usually 45 MPa and 87 MPa, respectively.
The design of high-pressure hydrogen storage devices should consider not only the strength of materials to meet the needs of use and safety, but also the fatigue performance and hydrogen embrittlement resistance of materials. Fixed hydrogen storage vessels commonly used in
China are divided into two structural forms, namely, single-layer hydrogen storage pressure vessels (including large volume seamless hydrogen storage vessels, single-layer integral forging hydrogen storage pressure vessels, etc.) And multi-layer hydrogen storage pressure vessels (including steel strip staggered hydrogen storage vessels, laminated hydrogen storage pressure vessels, etc.). There are two types of seamless steel hydrogen storage containers: fixed (such as hydrogen storage tanks in hydrogen refueling stations) and mobile (such as hydrogen long tube trailer cylinders). The seamless
steel hydrogen storage vessel is constructed according to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code. The seamless steel tube is made by forging and closing at both ends, which belongs to the integral weldless structure. Steel seamless containers have been developed for a long time, and the production line equipment technology of gas cylinders is very mature, which has the advantages of low cost and fast delivery. The
steel belt cross-wound pressure vessel was initiated in 1964, and its vessel structure was completely independently developed by China. Its main products include high-pressure air storage tank, high-pressure helium storage tank and high-pressure hydrogen storage tank. After nearly 60 years of research and verification, China has a solid theoretical basis and rich practical experience. Zheng Jinyang et al. Proposed a multi-functional multi-layer high-pressure hydrogen storage vessel based on the traditional steel strip cross-wound pressure vessel and under the condition that the main structure remains unchanged (flat steel strip angle cross-wound vessel structure). Hydrogen
filling
machine is the core equipment for filling hydrogen fuel for fuel cell vehicles. The hydrogen filling machine is equipped with hydrogen filling gun, temperature and pressure sensor, ambient temperature sensor, metering device, filling controller, hose, etc. If the communication function is realized between the hydrogen refueling machine and the fuel cell vehicle, the hydrogen refueling gun also needs to be equipped with an infrared data receiving module.
hydrogenation machines: 35MPa and 70MPa. The main technical requirements are to ensure that the filling process does not exceed the temperature and pressure, and the time is as short as possible. In 2014, the
National Standardization Management Committee first issued the national standard of GB/T 31138-2014 Compressed Hydrogen Dispenser for Vehicles, which provides support for the manufacture, testing and application of hydrogenation equipment.
In recent years, with the rapid development of hydrogen energy industry in China, there are new requirements for the performance requirements and control methods of hydrogenation machines.
In 2020, the National Standardization Management Committee issued the revision plan of GB/T 31138-2014 "Compressed Hydrogen Dispenser for Vehicles", and the National Hydrogen Energy Standardization Technical Committee organized relevant units to complete the revision and review of the technical content of the standard by the end of 2021. In order to meet the needs of industrial development and coordinate with GB 50516, GB50156 and other standards, the standard name was revised to "Hydrogenator". GB/T 31138-2022 "Hydrogenator" was issued and implemented on October 12, 2022, which stipulates the requirements of technical requirements, test methods, marking, packaging, transportation, storage, installation and maintenance of hydrogenators, and is applicable to hydrogenators with nominal working pressure not greater than 70 MPa for hydrogen vehicle hydrogenation facilities. Hydrogenation facilities of hydrogen energy ships, trams, aircraft, engineering vehicles, power generation units, etc., can also refer to this document.
As of April this year, China has built more than 350 hydrogen stations, accounting for about 40% of the global total, ranking first in the world.
Despite the large number of hydrogen stations in China, under the basic national conditions of vast territory and dense population, hydrogen stations are still unable to escape the fate of "not enough" and "not usable". The equipment composition of hydrogenation station is more, the cost is higher, and the cost of safety maintenance is not low, whether the hydrogenation station can really achieve smooth and stable operation is still a major challenge in the industry.
First, the technology and cost of hydrogenation station equipment are both high. The high cost of hydrogen station construction and the low space for cost reduction need to be paid attention to in the industry. It is estimated that the construction cost of a hydrogenation station is at least 2 million US dollars (plus construction, design, maintenance, management and other costs), which is equivalent to about 15 million RMB. If the daily hydrogenation capacity is 1000 kg and the hydrogenation system is 70Mpa, it will reach about 20 million RMB. Among them, the hydrogen compressor accounts for about 30% of the total cost of the hydrogenation station. From the current situation of hydrogen compressor market in China, domestic hydrogen compressor enterprises still need to work hard.
Second, the approval policy for the construction of hydrogenation stations needs to be relaxed. In the first half of this year, Guangdong and Hebei provinces issued the latest management measures for hydrogenation stations, making it clear that hydrogen is no longer listed as dangerous chemicals, and that hydrogenation stations can be built in non-chemical industrial parks and other places. The strict approval process for the construction of hydrogen stations is a major "threshold" that hinders the construction of hydrogen stations. At present, the vast majority of regions in China have not yet relaxed the policy on the construction of hydrogen stations and the land approval process for hydrogen stations. For first-tier and second-tier cities, the improvement of hydrogen energy infrastructure such as hydrogen refueling stations is an important prerequisite for the large-scale application of hydrogen fuel cell vehicles, but the efficiency of hydrogen refueling stations in most areas is still difficult. In view of this, oil-hydrogen co-construction stations or integrated energy stations have begun to emerge, adding hydrogenation supply facilities on the basis of existing gas stations or filling stations, which not only ensures the normal operation of the stations, but also realizes hydrogenation.
Third, the hydrogen supply demand of the hydrogen station is difficult to guarantee. "One step at a time", whether the hydrogenation station can operate normally after completion is a major problem for the suppliers or operators of the hydrogenation station at present. On the one hand, most of the hydrogenation stations are external supply hydrogenation stations, which need long tube trailers to transport hydrogen to the hydrogenation station and then enter the hydrogen storage system, and then fill when there is a demand for hydrogenation. However, many hydrogen stations are facing the problem of insufficient hydrogen supply and storage. Hydrogen transportation is not timely and there is no hydrogen supply source, which directly leads to the hydrogen supply demand of the hydrogenation station can not be guaranteed. On the other hand, although some cities have built one or two hydrogen stations, there are fewer hydrogen fuel cell vehicles, even if there is sufficient hydrogen supply, but the problem of "adding hydrogen only once a few days" is also common. The "egg or chicken" debate has become the main contradiction between hydrogen stations and hydrogen fuel cell vehicles. Many cities have built hydrogen stations in high-speed service areas. For hydrogen vehicles in cities, hydrogenation is undoubtedly a challenge.
From the current situation of hydrogen energy infrastructure construction in China, the construction of hydrogen stations is increasingly put on the agenda. Hebei Province has incorporated the construction of hydrogen stations into local construction indicators, and Beijing, Shanghai, Guangdong and other Yangtze River Delta regions are also actively subsidizing the construction and operation of hydrogen stations, and the development of hydrogen energy industry has been growing. Entering this year, the upstream hydrogen production end of the hydrogen energy industry has begun to step up its construction, and the leading hydrogen energy enterprises in Kuqa, Xinjiang < a href = "https://www.databm." have also made continuous moves in the downstream application end. Automobile enterprises have begun to lay out the hydrogen energy business in China, and the cross-border hydrogen energy of the leaders has created multi-faceted hydrogen energy application scenarios. On this basis, the hydrogen energy storage and transportation terminal will also play a good role in connecting the preceding and the following, and the problem of "sticking neck" of the hydrogenation station will be gradually solved under the coordinated promotion of all parties.
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