Use of booster fans in underground coal mining to advantage

A booster fan is an underground main fan which is installed in series with a main surface fan and used to boost the air pressure of the ventilation to overcome mine resistance.Currently booster fans are used in several major coal mining countries including the United Kingdom,Australia,Poland and China.In the United States booster fans are prohibited in coal mines although they are used in several metal and non-metal mines.A study has been undertaken to examine alternatives for ventilating an underground room and pillar coal mine system.A feasibility study of a hypothetical situation has shown that current ventilation facilities are incapable of fulfilling mine air requirements in the future due to increased seam methane levels.A current ventilation network model has been prepared and projected to a mine five years plan."Ventsim visual" software simulations of different possible ventilation options have been conducted in which varying methane levels are found at working faces.The software can also undertake financial simulations and project present value total costs for the options under study.Several scenarios for improving the ventilation situation such as improving main surface fans,adding intake shafts,adding exhaust shafts and utilizing booster fans have been examined.After taking into account the total capital and operating costs for the five years mine plan the booster fan scenarios are recommended as being the best alternatives for further serious consideration by the mine.The optimum option is a properly sized and installed booster fan system that can be used to create safe work conditions,maintain adequate air quantity with lowest cost,generate a reduction in energy consumption and decrease mine system air leakage.

镰状细胞病患者肺高压的血流动力学研究

肺动脉高压以存在毛细血管前肺高压,无左侧心脏疾病、肺部疾病、慢性血栓栓塞疾病为特征。在组织病理学方面,肺动脉高压则以肺小动脉内层平滑肌细胞和内皮细胞增殖为特征。肺动脉高压可以是原发性、遗传性或与其他疾病相关,如结缔组织疾病和先天性心脏病等。以往的研究发现,肺高压特别是肺动脉高压是镰状细胞病较常见的并发症[1]。