Chlor-alkali industry: Three strategies to achieve sustainable development

The petroleum and chemical industry plays a crucial role in the nation's efforts toward energy conservation and emission reduction. Within this sector, the chlor-alkali industry stands out as one of the most significant areas for improving efficiency and reducing environmental impact. As a highly energy-intensive industry, it consumes a substantial amount of electricity, with energy costs accounting for over 50% of the production expenses for caustic soda and around 40%-45% for PVC. This makes energy-saving and emission reduction not just a priority, but a vital factor for the survival and long-term development of chlor-alkali enterprises. According to Zhang Guomin, Secretary-General of the China National Chlor-alkali Industry Association, energy conservation and emission reduction have always been central to the industry’s growth. Over the years, the association has actively supported and implemented various policies aimed at promoting sustainable practices. These efforts have led to measurable progress in reducing energy use and pollution. Since the "Eleventh Five-Year Plan," the Chinese government has emphasized energy efficiency and environmental protection, prompting the chlor-alkali industry to align with national goals. The China Chlor-Alkali Industry Association has played a key role in developing and enforcing energy-saving regulations. For instance, in April 2007, the "Calkaline/PVC Cleaner Production Evaluation Index System" was introduced, setting clear benchmarks for resource use, energy consumption, and pollution control. In December 2007, new access conditions were established for the industry, defining strict energy and environmental standards for new and expanded facilities. In June 2008, the national mandatory energy consumption standard under the Energy Conservation Law was applied specifically to the caustic soda industry, establishing limits on energy use per unit of product. These measures have significantly advanced the industry’s energy-saving initiatives. Structural adjustments have also been essential in achieving these goals. Outdated production capacities often lead to resource waste and pollution. By upgrading production processes, the industry has made great strides. For example, the ion-exchange membrane process for producing caustic soda is far more energy-efficient than traditional methods. It reduces overall energy consumption by about one-third compared to diaphragm technology, while energy-saving separators can save up to 140 kWh per ton of caustic soda. During the "Eleventh Five-Year Plan" period, the industry actively promoted advanced technologies. New installations no longer used conventional metal anode electrolyzers, and existing ones were upgraded with innovations like active cathodes, small electrode spacing, and modified membranes. By 2007, the capacity for ion-exchange membrane caustic soda exceeded that of diaphragm caustic soda, reaching over 55%, and by 2008, it surpassed 60%. This shift has greatly improved energy efficiency and reduced emissions. Technological innovation has also played a critical role. The dry acetylene technology, for instance, uses less water and produces drier calcium carbide slag, making it more suitable for cement production. Low-mercury catalysts have significantly cut mercury emissions, and mercury-free catalysts are now being developed for future industrial use. Additionally, technologies such as oxygen cathode systems and chlorine reuse have further contributed to energy savings and pollution reduction. Through continuous improvements in both process and technology, the chlor-alkali industry has achieved remarkable results in energy conservation and emission control, ensuring its sustainable and stable development.

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