千万吨级常减压装置抽真空系统的改造

Modification schemes of decompression system of ten million tons atmospheric and vacuum distillation unit

针对某千万吨级常减压装置减压塔顶抽真空系统存在蒸汽耗量大、自产蒸汽供给不足、真空度波动大等问题,提出2种减压塔塔顶抽真空系统改造方案:方案A按照现行运行工况,新增液环真空泵代替原三级抽空器;方案B通过调节蒸汽抽空器动力蒸汽压力,优化抽空系统压缩比,根据优化后操作参数新增液环真空泵代替原三级抽空器。通过对比2种方案的设备选型、公用工程消耗及经济效益,最终选定方案B;经核算,项目实施后,可减少蒸汽消耗量7.72 t/h,降低操作费用830.79万元/a,设备投资400万元,投资回收期2.08 a。

As the problems of large steam consumption,insufficient supply of self-produced steam and large fluctuation of vacuum degree in a ten-million tons atmospheric and vacuum distillation unit,two modification schemes were put forward.Scheme A was to add a liquid-ring vacuum pump to replace the original third steam vacuum jet in accordance with the current operating conditions.Scheme B was to optimize the compression ratio of the steam jet pumps by adjusting the steam pressure and to add a new liquid ring vacuum pump to replace the original third steam vacuum jet according to optimized operation parameters.After comparing the equipment investment,utility consumption and economic benefit of the two schemes,scheme B was selected.After the implementation of the modification,it was estimated that the steam consumption would be reduced by 7.72 t/h,the operation cost would be reduced by 8.307 9 million Yuan per year,and the payback period of investment would be 2.08 years.