Guilian Liu

Synthesis of distillation sequences for separating multicomponent azeotropic mixtures

Abstract An automatic procedure for the synthesis of sequences of distillation columns for separating homogeneous multicomponent azeotropic mixtures is developed. Key to the approach is the use of sets of compositions, or ‘product regions’, to specify product compositions. The synthesis procedure is implemented in two stages. The first stage consists of identifying classes of splits. Each class of split may be characterised as either feasible or potentially feasible. The synthesis procedure systematically combines these classes of splits to generate column sequences that satisfy a pre-determined separation requirement. The second stage of the synthesis procedure assesses the feasibility of a proposed flowsheet once the recycle options have been defined. Preliminary design of each column in the sequence can be performed. The feasibility assessment procedure will form the basis for systematic flowsheet generation and optimisation.

Pinch Location of the Hydrogen Network with Purification Reuse

In the hydrogen network with the minimum hydrogen utility flow rate, the pinch appears at the point with zero hydrogen surplus, while the hydrogen surpluses of all the other points are positive. In the hydrogen purity profiles, the pinch can only lie at the sink-tie-line intersecting the source purity profile. According to the alternative distribution of the negative and positive regions, the effect of the purification to the hydrogen surplus is analyzed. The results show that when the purification is applied, the pinch point will appear neither above the purification feed nor between the initial pinch point and the purification feed, no matter the purification feed lies above or below the initial pinch point. This is validated by two case studies.

Optimization of IGCC gasification unit based on the novel simplified equilibrium model

The increasing pollutant emissions due to the development of science and technology creates tough challenges for the whole world. As one of the main causes, the utilization of solid fuels, like coal and biomass, has attracted the attentions of researchers. To alleviate this pollution, gasification technology is widely promoted in many fields of modern industry, especially in its application for Integrated Gasification Combined Cycle (IGCC) plant. Improving the simulation of gasifier is one of the most effective and essential ways to mature gasification technology. In this paper, a novel simplified equilibrium model is proposed for IGCC gasification unit. Through the analysis of gasification mechanism, Water Gas Shift Reaction (WGSR) is verified as the control step to determine the compositions of syngas. The simplified model based on the equilibrium of WGSR is proposed, developed and validated with experimental data. Furthermore, the sensitivity analysis is completed to demonstrate the influences of key factors on syngas compositions, such as reaction temperature, oxygen feed ratio and water feed ratio. Finally, the IGCC gasification unit operation conditions are optimized and the Cold Gas Efficiency is improved approximately 10% after optimization.

The Hydrogen Network Optimization of a Complex Refinery

In this paper, the hydrogen distribution network of a complex refinery is optimized by the hydrogen surplus pinch method. By plotting the hydrogen purity profiles and hydrogen surplus diagrams, the hydrogen pinch with hydrogen purity of 87% is identified. The corresponding minimum hydrogen utility consumption is 17730.5 Nm3/h. Moreover, the optimal hydrogen distribution network with minimum utility consumption is designed. Compared with the current hydrogen network, the hydrogen utility consumption can be reduced by 10.45%.

Simultaneous Optimization and Integration of Gas Turbine and Air Separation Unit Using Novel Simplified Model

Abstract As a promising green technology, Integrated Gasification Combined Cycle (IGCC) technology holds an urgent requirement to be upgraded by process optimization and integration. Directly power related Gas Turbine (GT) and energy intensive Air Separation Unit (ASU) in IGCC plant are selected as the target. A novel mathematical simplified ASU model is proposed to decrease the simulation complexity. It is built with GT model together using Microsoft Excel 2010. What’s more, in this paper the optimization and integration are taken simultaneously instead of sequentially to get a more efficient configuration further closing the global optimal solution. Operation conditions optimization, especially considering the pressure matching between GT combustor and ASU columns, and heat and mass integrations are considered to decrease work consumption and enhance the environmental performance. The specific performances can be demonstrated by case study results. The conclusion shows that the methodology we developed can achieve more effective operation of GT and ASU with about 3 % more power generation.

Targeting the hydrogen network and optimal feed using rigorous simulation

Abstract A novel optimization method is developed with the purification cost determined by rigorous simulation. The mathematical model of Pressure Swing Adsorption is established considering the operating conditions, and is solved by MATLAB. According to the model, the quantitative relation between the energy consumption and the purification feed is obtained. Based on this, the optimization model of the hydrogen network is built. The objective is to target the minimum energy consumption and the optimal variable is purification feed, including PFFR and PFP. As this model solved by GAMS, the minimum fresh hydrogen consumption and the optimal purification with the optimal purification feed, and optimal operating conditions can be identified.

A Graphical Method for Hydrogen Network Integration with Purification Reuse

Abstract Hydrogen is an expensive secondary resource and energy, especially for refineries. In recent years, due to increasing processing capacity, composition variation and quality deterioration of crude oil, as well as stricter environmental regulations, hydrogen consumption has been increasing sharply to satisfy various hydroprocessing operations to produce eligible product oil. As a result, hydrogen production relies more and more seriously on nonrenewable resources, such as natural gas and coal. Furthermore, the accompanying emissions to the environment caused by hydrogen production are also undesirable. Hydrogen network integration can effectively utilize and conserve hydrogen for refineries, relieving both their budget on hydrogen production and environmental impact, and thus became a hot research topic since approximately two decades ago. This chapter will focus on hydrogen network integration with purification reuse, which is performed by a graphical approach in pinch diagram. Two cases are employed to demonstrate the visual solution for hydrogen networks.

Study on the volatility order of systems with two maximum azeotropes

In systems with two maximum azeotropes, different volatility orders can be obtained according to different isovolatility line. In this paper, the volatility orders of systems with two maximum azeotropes are identified according to the rigorous simulation of Aspen Plus, and are compared with that identified according to the isovolatility lines. The results show that, there are two distillation regions in systems with two maximum azeotropes and two isovolatility lines, the volatility order in them can be identified according to the isovolatility line lying in them. Based on this, the rule for identifying the volatility order is proposed. And, it is applied to two different cases, and the results shows that this rule is accurate, simple and can be applied convienently.

Study on the Volatility Order of Systems with Two Minimum Azeotropes

In systems with two minimum binary azeotropes, there are two isovolatility lines. Different volatility order can be obtained according to different isovolatility lines. The volatility orders of components are identified according to the isovolatility lines and are compared with that identified based on the rigorous simulation using Aspen Plus. The results show that, in the system with two minimum binary azeotropes and two isovolatility lines, the volatility order of components is determined by the isovolatility line passing through the unstable node. Based on this, the rule for identifying the volatility order is proposed. The case studies show that this rule is simple and feasible.This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.