Chlor-alkali industry: Three strategies to achieve sustainable development
Since the “Eleventh Five-Year Plan†policy orientation, in order to promote the energy conservation and emission reduction work of the chlor-alkali industry, the China Chlor-Alkali Industry Association has integrated policies issued by the state, guided by national policies, and actively guided the formulation of policies and measures for energy saving and emission reduction in the chlor-alkali industry. To standardize the energy conservation and emission reduction work of the chlor-alkali industry.
In April 2007, the "Calkaline/PVC Cleaner Production Evaluation Index System" was issued and implemented. This index system makes decisions on resource and energy consumption indicators, pollutant generation indicators, and comprehensive resource utilization indicators for the caustic soda and polyvinyl chloride industries. Clearly defined.
In December 2007, the chlor-alkali (caustic soda, polyvinyl chloride) industry access conditions were implemented, which defined clear entry values ​​for energy consumption and environmental protection, and set a high initial scale for newly-built, rebuilt and expanded installations.
In June 2008, the national mandatory energy consumption standard for "energy saving law of the People's Republic of China" was applied to "the energy consumption limit of caustic soda unit product". The standard stipulates the scope, basic requirements, accounting methods and management requirements of the energy consumption limit for the caustic soda unit product of electrolysis (diaphragm method, ion membrane method). The introduction of a series of industry energy-saving and emission reduction policy regulations has effectively promoted the process of energy-saving and emission reduction in the chlor-alkali industry.
Structural Adjustment Backward production capacity is an important cause of waste of resources, energy, and environmental pollution. Adjusting the structure is the main way to achieve energy-saving emission reduction targets. From the perspective of the caustic soda industry, the focus of industrial restructuring is the upgrading of production processes. Energy consumption differs greatly between different production processes. For example, the overall energy consumption per ton of caustic soda is lower by one-third than that of membrane caustic soda, and the energy-saving separator Caustic soda can save 100 to 140 kWh compared to ordinary metal anode membrane caustic soda.
During the “Eleventh Five-Year Plan†period, the chlor-alkali industry actively promoted the advanced ion-exchange membrane caustic soda production process, and the new installation was prohibited from using common metal anode electrolyzers, and the common membrane method was adopted through the expansion anode, active cathode, small polar distance, modified membrane technology. The device is modified. The caustic soda production process has been significantly optimized, and the comprehensive energy consumption of the chlor-alkali industry has dropped significantly. In 2007, China's ion-exchange membrane caustic soda production capacity exceeds that of the diaphragm caustic soda production capacity, accounting for more than 55%. It is estimated that in 2008, with the continuous elimination of membrane caustic soda equipment, the production capacity of ion-exchange membrane caustic soda will increase to more than 60%. While the proportion of caustic soda by the ion-exchange membrane method has increased, the proportion of energy-saving membrane caustic soda has also increased significantly, from the original one-third to more than one-half. The optimization of the production process has laid a solid foundation for the caustic soda industry to achieve energy-saving emission reduction targets.
Technology promotion Advanced technology is a powerful tool for energy conservation and emission reduction. In recent years, China Chlor-Alkali Industry Association has actively promoted advanced energy-saving and emission-reduction technologies to the whole industry through various forms and achieved good results. For example, the dry acetylene technology uses slightly more than the theoretical amount of water to spray on the calcium carbide powder in a mist state to decompose it. The calcium carbide slag produced has a moisture content of 4% to 10% dry lime powder, and the calcium carbide hydrolysis rate is greater than 99%. It can reach about 90%. The calcium carbide slag produced by the original wet technology still has 30% moisture after pressure filtration, and it is necessary to use a lot of steam to evaporate water before it can be used as a cement raw material. The low mercury catalyst technology is a major breakthrough in the reduction of emissions in the chlor-alkali industry. Currently, four companies have collaborated to reduce the mercury chloride content of the catalyst from more than 10% to less than 6%, and the consumption of mercury in heavy metal pollutants. Both emissions and emissions have dropped significantly. Particularly worthy of surprise is that the mercury-free catalyst has also been successfully developed, and the next step will be industrialization. In addition, hydrochloric acid synthesis furnace exhaust gas recovery technology can utilize tail gas heat to produce steam; chlorine resource secondary utilization technology can re-use hydrogen chloride produced from chlorine products such as diphenylmethane diisocyanate, toluene diisocyanate, and trichloroethylene to produce poly Vinyl chloride; oxygen cathode technology under development replaces hydrogen with oxygen electrode reduction reaction to precipitate reduction reaction, which greatly reduces the common cathode's tank voltage, saving about 35% of electricity. Through a series of technological innovations, both the energy consumption and pollutant emissions of the chlor-alkali industry have dropped significantly, which has promoted the sustained and stable development of the chlor-alkali industry.