Simple Methods For Targeting Water And Hydrogen Networks Involing Regeneration

Recently,it has been an urgent problem to utilize water resource efficiently and reasonably,with the aggravation of water scarcity and water pollution.Water system integration,one of important techniques for reducing freshwater consumption and wastewater discharge,has attracted more and more attention.Since crude oil is getting heavier and environmental regulations are becoming stricter,large amounts of hydrogen resources are required for hydro-treating processes.Now,more than half of the refineries are facing with hydrogen shortage problem.Therefore,it is very important to make full use of hydrogen resource and reduce utility consumption.One of the methods is the synthesis of hydrogen networks,which considers hydrogen-procedures,hydrogen-consumers and regeneration unit as a whole system.In this thesis,the researches about water-using/hydrogen networks are as follows:Firstly,an effective method is presented for targeting single contaminant water-using networks involving regeneration reuse/recycle.Targeting of water-using networks involving regeneration unit is often more difficult than that of water-using networks involving reuse only,especially for the regeneration unit with fixed removed ratio(RR)model.An effective method is presented for targeting single contaminant water-using networks involving regeneration unit with fixed RR model in this paper.The targeting procedure is based on the analysis of the features of the network,and a few relationships developed from flow rate and mass load balances.The results of a few literature examples show that the targets of single contaminant water-using networks involving regeneration reuse/recycling can be obtained easily with the proposed method.Secondly,a simple method is presented for targeting the single contaminant hydrogen networks involving purification unit.Hydrogen utility consumption can be reduced significantly when purification unit is introduced in a hydrogen network.In this paper,a simple method is presented for targeting the single contaminant hydrogen networks involving purification unit with fixed purified concentration model,based on the characteristics of the hydrogen networks.In the targeting procedure,the initial flow rate of the purified stream is first assumed as sufficient,and then the initial purification pinch is identified.Finally,the purification target can be obtained with a few relationships developed from material balances.If the initial purification pinch is estimated correctly,the purification target can be obtained by only one step simple calculation.If the initial purification pinch is not estimated correctly,the correct pinch point can be determined based on the results of the first step calculation.The target can be obtained by an additional step of simple calculation.The results of a few literature examples show that the purification stream consumption target of single-contaminant hydrogen networks involving purification unit can be obtained easily with the proposed method.The method proposed provides an effective tool for the targeting of hydrogen networks involving purification unit.Thirdly,a simple method is presented for targeting the multiple contaminant water-using networks involving regeneration unit.The multi-contaminant water networks involving regeneration recycling are classified into simple ones and complex ones.Simple networks are similar to single-contaminant ones,in which only the key contaminant limits the usage of regenerated water.In this paper,a simple method is presented for simple networks involving regeneration unit.In the targeting procedure,the initial regenerated concentration is first estimated according to the features of water-using processes and regeneration unit.The regeneration pinch,performing order and allocation of sources to the demands corresponding to the initial regenerated concentration is then identified.Finally,the regeneration target is calculated with a few relationships developed from flow rate and mass load balances.The results of a few literature examples show that the targets of multiple contaminant water-using networks involving regeneration reuse/recycling can be obtained easily with the proposed method.