Optimal Design Of Multi-plant Hvdrogen Network

In recent years,due to increasing refinery processing capacity and depth of crude oil,the sharp increase of fresh hydrogen,resulting in huge hydrogen deficiency that more and more seriously impeded the development of refineries.Efficient usage of hydrogen makes great sense to the reduction of cost.energy consumption and waste discharge for refineries.Many researchers have proposed different ways to optimize the hydrogen networks.The most effective,cost-efficient and most widely used in industry method is the integrated optimization of hydrogen networks.On the basis of the predecessors,a mixed integer linear model is presented to optimize and design the hydrogen network with purification reuse/recycle based on the necessary conditions of optimal purifier position and the pinch location method,and then we extend the object to inter-plant hydrogen network,and propose a two-step optimization method based on the transshipment model.Then,considering the stability of hydrogen network,the WCVaR model of inter-plant hydrogen network is proposed,which provides theoretical support for the design and transformation of hydrogen system in refineries.The main contents of the work are as follows:(1)At present,when integrating hydrogen networks with purification reuse/recycle,mathematical programming models adopted by most of the researchers belong to the non-convex and non-linear models,not guaranteeing global optimal solution.Based on the previous studies,this paper proposes a mixed integer linear programming model to obtain the minimum hydrogen utility consumption.The method can obtain the inlet flow rate of the purifier while optimizing the hydrogen utility.The case study shows that the mathematical model is effective in both hydrogen network and water network.(2)There are few studies on the integration of inter-plant hydrogen networks.The Inter-plant integration of inter-plant hydrogen network can further save hydrogen resources and improve the profit of refinery.Therefore,it is of great significance to study the hydrogen system of multi-refinery.In this paper,a novel two-step method that combines pinch insight with mathematical programming is developed to optimize the inter-plant hydrogen network with purification reuse/recycle.In Step 1,a new transshipment model for targeting inter-plant hydrogen network is built.After the hydrogen consumption is determined by Step 1,individual plant hydrogen networks are designed separately with the number of connections in the plant as the objective function in Step 2.Furthermore,the model can also optimize the number of inter-plant connections of the hydrogen network.To illustrate the application of the proposed model,three case studies are presented before the conclusion of the work.(3)For hydrogen network optimization problem of the refineries which are provided hydrogen by coal gasification hydrogen plant and natural gas hydrogen plant,the paper introduces the Worst-Case Condition Value-at-Risk(WCVaR)concept to indicate possible minimum value of total pure hydrogen flowrate in hydrogen networks.By establishing the WCVaR mathematical model to study the influence of the fluctuation of hydrogen source flowrate on the inter-plant hydrogen network,the hydrogen network satisfying the hydrogen sinks under certain confidence level and uncertainty distribution can be obtained.Monte Carlo simulations results shown the disturbance resistance ability of the hydrogen network obtained by proposed method is better than the traditional deterministic optimization method.