污水沼气送烧聚酯热媒炉技术改造

Modification to Send Sewage Methane into PET HTM Furnace as Fuel

2007年之前,仪征化纤污水处理装置将污水厌氧反应产生的沼气通过火炬系统燃烧。2007年投资建设了4套小型发电机,有效回收了部分热能(约为22%),因沼气发电设备故障较多,年维修保养费用需85万元。针对沼气发电装置存在效率低、运营成本高等问题,仪征化纤公司提出污水沼气送聚酯热媒炉燃烧回收热能的改造方案,保留原有的天然气点火及燃气系统不变,点火程序不变,天然气是主燃料,沼气作为辅助燃料。考虑到沼气压力有波动,在正常运行中,烟气中的残氧含量设定值要比目前运行值高(建议在2.5%以上)。改造后投运效果表明,系统运行稳定,安全可控。可实现年节约天然气511万m^3(标准状态),净经济效益789万元。该项目约半年就可收回投资。

Before 2007, the sewage methane generated from the sewage treatment unit in Yizheng Chemical Fibre was burned off in the flare. In 2007 the company added four small electrical generators to recover some 22 percent of the heat energy, but only with equipment faults and high maintenance cost. Therefore the company proposed a modification to send the sewage methane into its PET HTM furnace as additional fuel for heat recovery, while still using natural gas as main fuel and the fuel gas system remaining intact. Considering the unstable pressure of the sewage methane, it is recommended that the residual oxygen content in flue gas be set above 2.5%, higher than in original operation. The modification has proven effective with steady operation and controlled safety, saved natural gas of 5.11 million cubic meter/year, and achieved net profit of 7.89 million yuan with payback period of only 6 months.