一、前言小氮肥厂锅炉车间的锅炉,其液面目前大都用人工调节,有些厂虽然研制了液面自控装置、但都有一个共同的不足处,那就是结构复杂、执行机构大都使用压缩空气或锅炉本身的蒸汽。由于结构复杂,成本必然高、维修也较困难,另外需要庞大的压缩空气系统、投资大、消耗动力多,有的厂本来蒸汽就紧张,当蒸汽压力过低时,气动薄膜阀拒绝动 I. INTRODUCTION Boilers in the small nitrogenous fertilizer boiler workshop are mostly manually adjusted at present. Although some plants have developed liquid level automatic control devices, they all have a common deficiency. That is, the structure is complicated, and the implementing agencies mostly use compressed air Or the steam of the boiler itself. Due to the complex structure, the cost is bound to be high, and the maintenance is also difficult. In addition, a huge compressed air system is required, which requires large investment and consumes more power. Some steam turbines are already nervous. When the steam pressure is too low,