subject: Green energy manufacturing polysilicon industry representation - Electrical industry [print this page] Green energy manufacturing polysilicon industry representation - Electrical industry
Currently facing polysilicon production to reduce energy consumption, reduce pollution, improve quality, expand four production problems. Currently most of our solar silicon materials industry dependent on imports, technological change must be controlled by others to improve the situation.
Solar PV industry chain including raw materials to produce crystalline silicon, silicon rods and wafer production, solar Battery Manufacturing, component packaging, solar photovoltaic power generation system production and other sectors. In which silicon is the most important production processes in the industry had "a king who owned silicon itself." Currently, the world's solar PV Battery 90% yes for the raw material silicon or polycrystalline silicon production. Currently placed in polysilicon production has four main problems to be solved: to reduce energy consumption, reduce pollution, improve quality and expand production. China solar silicon materials industry is most dependent on imports, technological change must be controlled by others to improve the situation.
Technology still lacking in China mainly relied on imports of solar silicon material
In the global PV industry chain, high-purity silicon material requires not only the purity of silicon up to 7 ~ 9 9, and one of boron, phosphorus and other impurities limited to tens of ppt (one trillion), it photovoltaic solar cell production is required for the core material. Therefore, the synthesis of high-purity silicon material, refining, purification, production of photovoltaic industry has become the most upstream industry clusters. At present, although the silicon raw material mineral reserves in China account for 25% of the world's total reserves, but the domestic solar cell manufacturers (such as Suntech, Yingli, etc.) most of the necessary raw materials need to be imported from abroad. This is because the production of silicon for solar cell material is mainly extracted by different methods to extract from the silicon raw material made of silicon and polysilicon. In China, the existing production technology of high purity silicon material compared with Western developed countries, energy consumption in production and there was still inadequate. Thus, not only greatly increased production costs, but also restricted the PV industry in our country to the upstream development of insurmountable "bottleneck", so that we can sell with a very low price with high energy consumption, high pollution, crude materials the same time, with a high price to buy back high-purity silicon material.
It is understood that although the silicon materials industry in China started earlier (50 years of the 20th century), but because of small production scale, backward technology, environmental pollution, consumption, high cost, most companies have stopped due to loss production or conversions. By 2004 only Emei in China Semiconductor materials Luoyang Monocrystalline Silicon Co., Ltd. plant and two production companies, their production capacity is only 100 tons / year, and can meet the needs of the silicon solar cell production output of only 80 tons of material reality. Experts predict that by 2010 China's production of silicon for solar cell materials demand will reach 4365 tons in 2015 to 16,200 tons. Without the intellectual property rights change the status of domestic polysilicon production, silicon materials industry in China subject to international market conditions will not change, this will endanger the further development of PV industry in China.
Distillation utilization energy-saving technology to reduce energy consumption reducing pollution
Modern chemical process on the energy conservation very seriously, putting in a lot of foreign resources to the development of energy-saving technologies, energy technologies, new processes, new initiatives, new methods are emerging. China's polysilicon production, the use of chemicals on mature advanced technologies, it will no longer be "high energy consumption, high pollution," industry, but the "green light cause." Distillation of the polysilicon to study the use of distillation in an analysis of its energy-saving technology, from the following aspects to achieve energy:
First, the implementation of multi-effect distillation, and energy is fully utilized. Multi-effect distillation is divided into roughly equal the raw material feed N shares, respectively, in turn increasing the pressure into a distillation tower in N, N a tower operating temperature has gradually increased. Pressure and high temperature steam to the lower tower tower tower tower kettle reboiler heat, while itself being condensed, and so on, so save the low-pressure column reboiler energy consumption and high-voltage tower condenser water consumption. In this system, only the maximum pressure of the first tower to the heat, the system can work, the energy required for single-tower energy consumption is about 1 / N, such as the three towers strung together a three-effect distillation technology power consumption is only to 1 / 3, energy-saving rate of 67% energy saving effect is very obvious.
Polysilicon production, many towers are set up for purification of silicon and can be energy and temperature based on reasonable match, the multiple effect distillation, to achieve significant energy reduction.
Second, increase the separation efficiency, reduce the reflux ratio, and further to achieve energy saving. Separation process, the separation efficiency can largely reduce the energy consumption, improve product quality, reduce emissions, improve recovery, improve enterprise efficiency. In the polysilicon distillation process, the use of high-guided sieve tray, the new packing and other new separation equipment, separation efficiency can be improved to reduce operating distillation reflux ratio, due to the energy consumption of distillation and reflux ratio showed a linear relationship This proportional reduction in energy consumption. Increase the separation efficiency is also improving product quality and reduce polysilicon silicon tetrachloride emissions the most effective way.
Third, a comprehensive optimization process to achieve energy efficiency. Polysilicon production of various materials to conduct a comprehensive material balance and energy balance, examine the reasonableness of its energy consumption by using heat integration technology, process optimization, the maximum energy saving. Throughout the production line through energy conservation and clean production, and closed-loop in the production process to achieve clean production, to reduce energy consumption and Si (silicon), H2 (hydrogen), Cl2 (chlorine) and other raw material consumption, lowering the cost to make products international competitiveness, quality, meet current and future large scale IC And solar cells.
Addition, the polysilicon production process produces a large number of SiCl4 (silicon tetrachloride), SiH2Cl2 (dichloro-dihydro-silicon), SiHCl3 (trichlorosilane) and other chlorine by-product of silane to the high cost of production, some chlorosilanes and hydrogen chloride into the exhaust system, not only increasing the exhaust gas processing costs, and increased pollutant emissions, waste water chloride concentration of 1700 ~ 2500mg / L. How to effectively solve the chlorosilane by-product of the way out is to reduce the production cost of polysilicon, the key to achieving energy saving is now the major polysilicon manufacturers face technical difficulties.
