Suggestions on the promotion of closed calcium carbide furnace in raw material

More and more calcium carbide enterprises are building or planning to build large-scale closed calcium carbide furnaces due to the increasing pressure of environmental protection and energy conservation and emission reduction, as well as the possible implementation of closed calcium carbide furnaces by the state after 2010. Not long ago, sun Weishan, Secretary General of China calcium carbide industry association, predicted that by 2010, the capacity of closed calcium carbide furnace in China will increase from the current 1.5 million tons / year to 4.5 million tons. However, the poor raw materials of white ash and orchid charcoal have become the key factors that restrict the popularization and advantage of closed calcium carbide furnace. Qinghai Dongsheng Chemical Co., Ltd. is one of the earliest domestic enterprises to adopt sealed calcium carbide furnace.

Sun Wanjun, general manager of the company, said frankly: because the quality of the raw materials for producing calcium carbide is not guaranteed, the biggest advantage of sealed calcium carbide furnace - energy saving advantage cannot be reflected. Taking their company as an example, although the technology independently researched and developed is used to clean and dust the tail gas of calcium carbide furnace for self burning white ash, which ensures the quality of white ash, but the quality is difficult to guarantee due to the outsourcing of all the orchid carbon, resulting in the electricity consumption of calcium carbide exceeding 3300kwh / T, and the comprehensive energy consumption is similar to that of the internal combustion furnace. After more than 20 years of exploration, a series of technical problems have been basically solved, such as the difficulty of gas enrichment and automatic control, which once perplexed the safety production of the closed calcium carbide furnace. Even the tail gas purification and comprehensive utilization technology has a number of patented technologies, some of which have also realized industrial production. Therefore, Zhang Yuyi, chairman of Inner Mongolia baiyanhu Chemical Co., Ltd., said: the most critical and urgent problem to be solved now is how to improve the quality of China's white ash and orchid charcoal, so as to ensure that the "good horse" of the closed calcium carbide furnace can eat "fine materials" and play the "Qianlima" specialty.

Zhang Yu pointed out that due to the short supply of Lancan and white ash in recent two years, the production enterprises also "don't wash the mud when the radish is fast", and the product quality can't be guaranteed at all. At present, the moisture content of the orchid charcoal is generally as high as 15% - 20%, the volatile content is more than 5%, and the fixed carbon content is only 50% - 60%, which is far from the requirements of the closed calcium carbide furnace that the fixed carbon content is more than 80%, and the moisture content is less than 3%. Not only does the calcium oxide content of white ash not meet the quality requirements of more than 92%, but even the most taboo metal oxide content of closed calcium carbide furnace, such as magnesium and iron, also exceeds the standard seriously. There are a lot of water and impurities in raw materials, which will not only increase the power consumption, keep the power consumption per unit product and comprehensive energy consumption high, but also make the material panel knot, the furnace wall is partially overheated, which will cause the furnace wall to be burned out, even lead to explosion and other safety accidents.

It is understood that the investment of closed calcium carbide furnace is relatively large, and the capital construction investment of closed calcium carbide furnace of the same scale is 2.5-3 times that of internal combustion furnace. In recent years, with the guidance of the state and industry, and the pressure of energy and environment, the closed calcium carbide furnace has finally broken through many obstacles, and is favored by calcium carbide enterprises. However, unexpectedly, the promotion of closed calcium carbide furnace is stuck in the raw material. In this regard, Ma Zhanyu, chief engineer of Shaanxi Yudian sunshine Chemical Co., Ltd., has a deep feeling. He said that in order to ensure the quality of raw materials, Yudian sunshine had to abandon the rich and cheap white ash resources in Yulin, and went to Wuhai area of Inner Mongolia to purchase high-quality raw materials. They also mounted raw material drying devices and raw material screening facilities.

Through these measures, although the safe operation of calcium carbide furnace is guaranteed and the comprehensive energy consumption per ton of product is greatly reduced compared with that of internal combustion furnace, the cost of raw materials is increased by more than 150 CNY/ton, and the economic benefit is not obvious. According to the problems reflected by the enterprises, sun Weishan, Secretary General of China calcium carbide industry association, put forward three suggestions: first, the relevant departments of the state should plan the production capacity of lime, Lancan, calcium carbide and PVC as a whole, ensure that all industries in the chain have enough raw materials and coordinated development, so that the calcium carbide enterprises can choose between lime and Lancan, and let the lime and Lancan enterprises have competitive pressure Force it to improve product quality and service level. The second is to issue the tilting policy as soon as possible, encourage enterprises to adopt closed calcium carbide furnace and reduce the scale of internal combustion furnace. When the scale of closed calcium carbide furnace is growing and the "climate" is formed, the quality requirements of the market for Lancan and lime will be greatly improved, and the market for poor raw materials will be lost. Third, it is better for powerful enterprises to build their own production lines of lime and charcoal, like Qinghai Dongsheng Chemical Co., Ltd., Inner Mongolia baiyanhu Chemical Co., Ltd. and Ningxia Dadi metallurgical Co., Ltd., which can not only ensure the quality of raw materials, but also recycle the tail gas and residual pressure of calcium carbide furnace, greatly reduce the comprehensive energy consumption and cost of products, and improve the enterprise Competitive power.