Do chlor-alkali companies still only focus on chlorine and alkali products? If so, you’re behind the times

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At present, many chlor-alkali enterprises in China focus only on chlorine and alkali products, often overlooking the value of the hydrogen gas produced as a by-product. Supported by new energy-saving technologies and equipment, the utilization of hydrogen could become an important direction for structural adjustment in the chlor-alkali industry during the 13th Five-Year Plan period, with hydrogen fuel cells potentially serving as a key approach. 　　Zhang Xinru, deputy secretary-general of the China Chlor-Alkali Industry Association, told a reporter from China Chemical Industry News that the first set of oxygen-cathode ion-exchange membrane electrolyzers and hydrogen fuel cells introduced into China’s chlor-alkali industry will come online at the beginning of the 13th Five-Year Plan period. This technology will be quite attractive to chlor-alkali manufacturers in the eastern regions, while hydrogen fuel cells will serve as an important means for making use of the hydrogen produced as a by-product of chlor-alkali production. 　　“At present, many chlor-alkali enterprises in China focus only on chlorine and alkali products, often overlooking the value of the by-product hydrogen. Hydrogen is not utilized sufficiently, with a large amount of it being wasted by being released into the atmosphere. According to statistics, China’s chlor-alkali enterprises waste up to 30% of hydrogen each year, and this figure does not take into account the current extreme situation of low PVC production rates. Given the extremely serious waste of hydrogen resources in China’s chlor-alkali industry, choosing a reasonable approach to hydrogen utilization not only helps to prevent the waste of hydrogen resources but also enhances its value, which in turn contributes to strengthening the overall competitiveness of enterprises as well as their efforts in energy conservation and emission reduction. Therefore, the search for new chlorine- and hydrogen-consuming products needs to be carried out simultaneously. ”Zhang Jiaxing, general manager of Yingchuang Sanzheng (Yingkou) Fine Chemicals Co., Ltd., told the reporter. 　　The reporter learned that the main options currently available for utilizing hydrogen produced as a by-product in the chlor-alkali industry are: using it as feed gas for the production of synthetic ammonia ； Used in petroleum processing industries such as hydrocracking ； Used in the synthesis of chemicals and organic fine chemicals ； High-purity compressed hydrogen can be produced for direct sale ； Used to produce steam for fuel generation ； Another approach is to use hydrogen fuel cell technology to build hydrogen power plants. Due to the large scale of production and high hydrogen consumption in the ammonia synthesis industry and the petroleum refining industry, the hydrogen produced as a by-product in chlor-alkali plants is not sufficient to meet the needs of such heavy hydrogen users. The gradual advancement of fuel cell technology and oxygen-cathode electrolysis technology provides a completely new solution for chlor-alkali companies that struggle to find uses for hydrogen. 　　Hydrogen fuel cells convert hydrogen into electrical energy, based on the reverse reaction of water electrolysis. This product not only features a pollution-free and noise-free production process, but also boasts high conversion efficiency; no harmful substances are generated throughout the cycle, with pure water as the by-product. Its power generation efficiency is over 80%, allowing it to convert chemical energy directly into electrical energy without the need for intermediate conversion through thermal or mechanical energy. Therefore, this technology became the main source of energy-saving potential for China’s chlor-alkali industry during the 13th Five-Year Plan period. 　　Zhang Jiaxing explained that hydrogen fuel cell technology has reached maturity on an international scale. This technology is not only used for powering new vehicles, but success has also been achieved in building large power plants using hydrogen fuel cell technology. Among them, the first 70kW power plant has been generating electricity using hydrogen produced as a by-product of chlor-alkali production at AkzoNobel’s chlor-alkali plant in the Netherlands since 2007, and has operated successfully for over 45,000 hours. By using this technology to build hydrogen fuel power plants integrated with chlor-alkali production, the hydrogen generated as a by-product of chlor-alkali processes can be utilized directly, without the need for purification. Hydrogen fuel power plants can recover 20% of the electrical energy and 10% of the thermal energy consumed by the electrolysis unit. In 2011, the Netherlands successfully developed MW-class hydrogen fuel cells, which were installed at Solvay’s factory in Belgium; these cells also generated electricity using hydrogen produced as a by-product of chlor-alkali production. The unique advantages of hydrogen fuel cells make them a preferred option for the utilization of hydrogen in chlor-alkali plants. 　　Compared to another hydrogen solution—the oxygen-cathode electrolysis technology—fuel cell technology makes use of the hydrogen already produced in chlor-alkali processes, recovering 20% of the electrical energy and 10% of the thermal energy consumed by the electrolysis unit through fuel cell stacks ； Oxygen cathode technology is designed for enterprises that do not require hydrogen but only alkali and chlorine; it reduces the voltage of the individual cells using an oxygen cathode, allowing the electrolyzer to produce only alkali and chlorine, without any hydrogen being generated. Furthermore, hydrogen fuel cells have a reliable structure and greater stability. The operating condition of the hydrogen fuel power plant does not affect the stable operation of the electrolyzer. China’s chlor-alkali industry possesses the largest production capacity in the world. However, due to a single product structure, the consumption of chlorine and hydrogen relies heavily on polyvinyl chloride (PVC), which results in a poor balance among alkali, chlorine, and hydrogen in this industry. The utilization rate of hydrogen is even lower; many chlor-alkali companies have been releasing hydrogen into the atmosphere for a long time, and the value of hydrogen has been underestimated for years. In the process of structural adjustment in China’s chlor-alkali industry, in addition to developing new chlorine-based products that can replace PVC, companies should pay sufficient attention to the utilization of hydrogen.