考虑压力约束的多杂质氢系统集成

Optimization of hydrogen systems with multiple impurities and pressure constraints

由于原油的劣质化和重质化以及环保法规对油品质量的要求不断提高,使得炼油厂对氢气的需求在不断增加,合理利用炼厂氢气资源,优化配置氢气网络,对于节能减排意义重大。在氢气网络中,压力是一个重要约束,特别是氢气压缩机的投资很大,在氢气网络集成中,必须从经济性的角度满足压力的要求。为了在多杂质氢网络系统设计中同时考虑压力的影响,本文在多杂质赤字率夹点法的基础上,提出了考虑压力约束的多杂质氢系统的集成方法,在进行氢源和氢阱匹配时同时满足氢气浓度、杂质浓度和压力需求。通过引入系统最小压力降的概念,对氢源和氢阱按照杂质浓度进行排序后,构造氢源和氢阱的平均压力一流量图,从而可以判断各区域压力是否足够。当压力不足时,可通过改变公用工程用量或设置压缩机来满足压力需求。建立了费用公式来决定是改变公用工程用量还是设置压缩机,以最终确定经济合理的网络匹配。实例计算表明,所提出的方法是有效的。

In recent years, increasingly strict environmental constraints to gasoline and diesel quality, and the change of crude oil to high-sulfur and/or heavier oil are forcing refineries to increase their hydrotreating and hydrocracking processes, which consume a large amount of hydrogen. Optimization of the hydrogen network and rationally utilization of hydrogen resources are very important for energy conservation and cost reduction. In hydrogen networks, pressure is an important constraint. Because a hydrogen compressor is one of the most expensive devices in a refinery, economy should be an objective in considering pressure constraints. In order to consider the constraints on hydrogen purity, contaminant concentration and pressure for integrating a hydrogen network, in this paper, a new method for hydrogen network design is proposed based on the improved multiple impurities deficit diagram. The average pressure profiles of hydrogen sources and sinks are constructed through the introduction of a system＇s minimum pressure drop △pmin, according to the order of contaminant concentrations of sources and sinks. Combined with the hydrogen impurity profiles, whether the hydrogen purity, impurities and pressure of sources can meet sinks is determined intuitively. When the pressure in a certain region cannot meet the demand, there are two strategies to meet the demand, that is, increasing hydrogen utility consumption, or using a compressor. A cost equation is proposed to decide which strategy is more economic, and the final network is synthesized by economic consideration. A case study is used to validate the method.