Using physical model and numerical simulation techniques, some technical problems were studied systemati- cally, including layout of power station, measures of sediment and floating debris discharging, types of intake...Using physical model and numerical simulation techniques, some technical problems were studied systemati- cally, including layout of power station, measures of sediment and floating debris discharging, types of intake, embed- ded types of spiral ease, layout of underground powerhouse tunnel group and block reinforcement. It was optimal in technique and economy with the arrangement of powerhouse at the dam-toe of both banks ＋ underground powerhouse in the right bank, as well as the intake with a single and small orifice. The sediment and debris problems could be solved with disperse sediment ejection and floating debris discharging holes. With the adoption of techniques for spiral cases such as heat and pressure preservation, cushion layer and combined embedding, the stable operation of generating units can be guaranteed. The arrangement of tailrace tunnel with sloping ceiling was better than that of tailrace surge tank. The technical requirements related to the embedding type of spiral case were proposed. The reinforcement of huge unfavorable blocks was discussed and the new idea for block reinforcement using anti-sliding piles and normal compressive stress of structural plane was put forward.展开更多
The idea of the transformation of coal in underground into synthetic gas so-called syngas is interested in world in many centuries. Underground Coal Gasification （UCG） is an in-situ technique to recover the fuel or ...The idea of the transformation of coal in underground into synthetic gas so-called syngas is interested in world in many centuries. Underground Coal Gasification （UCG） is an in-situ technique to recover the fuel or feedstock value of coal that is not economically available through conventional recovery technologies. Today, less than one sixth of the world＇s coal is economically accessible. Today, similarly to all other countries in the world also in Slovakia there is an interest in the revival and perfection of the UCG technology. From the viewpoint of content the research is directed toward to increasing heating capacity of syngas. From the standpoint of the methods used the research can be divided into 2 approaches： experiments in UCG laboratory and mathematical modeling, including simulation studies. Both approaches have helped to discover complicated relationships during UCG and they will be the subject of this paper. The most important factors are methods, the humidity of the coal, heat losses, temperatures in relevant zones, the composition of oxidation agents and the permeability of the coal. The calorific value of syngas was found generally to be 0.55-4.45 MJ.Nm^-3 with a maximum of 25.51 MJ.m^-3 if only air is used as the oxidation agent. Where a mixture of air and oxygen is used, calorific values in the range 0.43-6.38 MJ.m^-3 were generally obtained, with maximum 27.53 MJ·m^-3. Analysis was carried out on these big differences in order to improve UCG.展开更多
文摘Using physical model and numerical simulation techniques, some technical problems were studied systemati- cally, including layout of power station, measures of sediment and floating debris discharging, types of intake, embed- ded types of spiral ease, layout of underground powerhouse tunnel group and block reinforcement. It was optimal in technique and economy with the arrangement of powerhouse at the dam-toe of both banks ＋ underground powerhouse in the right bank, as well as the intake with a single and small orifice. The sediment and debris problems could be solved with disperse sediment ejection and floating debris discharging holes. With the adoption of techniques for spiral cases such as heat and pressure preservation, cushion layer and combined embedding, the stable operation of generating units can be guaranteed. The arrangement of tailrace tunnel with sloping ceiling was better than that of tailrace surge tank. The technical requirements related to the embedding type of spiral case were proposed. The reinforcement of huge unfavorable blocks was discussed and the new idea for block reinforcement using anti-sliding piles and normal compressive stress of structural plane was put forward.
文摘The idea of the transformation of coal in underground into synthetic gas so-called syngas is interested in world in many centuries. Underground Coal Gasification （UCG） is an in-situ technique to recover the fuel or feedstock value of coal that is not economically available through conventional recovery technologies. Today, less than one sixth of the world＇s coal is economically accessible. Today, similarly to all other countries in the world also in Slovakia there is an interest in the revival and perfection of the UCG technology. From the viewpoint of content the research is directed toward to increasing heating capacity of syngas. From the standpoint of the methods used the research can be divided into 2 approaches： experiments in UCG laboratory and mathematical modeling, including simulation studies. Both approaches have helped to discover complicated relationships during UCG and they will be the subject of this paper. The most important factors are methods, the humidity of the coal, heat losses, temperatures in relevant zones, the composition of oxidation agents and the permeability of the coal. The calorific value of syngas was found generally to be 0.55-4.45 MJ.Nm^-3 with a maximum of 25.51 MJ.m^-3 if only air is used as the oxidation agent. Where a mixture of air and oxygen is used, calorific values in the range 0.43-6.38 MJ.m^-3 were generally obtained, with maximum 27.53 MJ·m^-3. Analysis was carried out on these big differences in order to improve UCG.
