Modelling and Simulation of the Freezing Systems and Heat Pumps Using Unisim ® Design C
Abstract—The paper describes the modeling and simulation of the heat pumps domain processes. The main objective of the study is the use of the heat pump in propene–propane distillation processes. The modeling and simulation instrument is the Unisim® Design simulator. The paper is structured in three parts: An overview of the compressing gases, the modeling and simulation of the freezing systems, and the modeling and simulation of the heat pumps. For each of these systems, there are presented the Unisim® Design simulation diagrams, the input–output system structure and the numerical results. Future studies will consider modeling and simulation of the propene–propane distillation process with heat pump.
Specific Problems of Using Unisim Design ® in the Dynamic Simulation of the Propylene-Propane Distillation Column
The paper analyzes the principles and particularities of using Unisim Design® environment in the dynamic modelling and simulation of chemical processes. The paper presents the four stages of configuration and simulation of the distillation process: steady-state modelling and simulation of the process, particularities of dynamic model configuration for propylene-propane distillation column, configuration of control structure for separated products quality, and dynamic simulation of propylene-propane distillation column. There are also presented the results of dynamic simulation of propylene-propane separation process with L-B structure for separated products quality control. The obtained results validate Unisim Design® as a powerful tool in dynamic simulation of distillation processes control systems.
Economic application of heat pumps in integrated distillation systems
Abstract The influence of relevant parameters on the economics of distillation plants involving distinct heat pump cycles is scrutinised and the results are compared to conventional and integrated schemes. On the basis of the COP , energy costs and efficiencies, simple expressions are proposed for preliminary economic analysis and design of heat pump assisted distillation. The influence of heat pump type, purity requirement, column pressure drop, feed rate, energy cost, relative volatility etc. on the energetic aspects and economic range of application is presented. Heat pumps can be economical substitutes for conventional distillation process design whenever direct refrigeration or chilled water are required for condensation and for separating close boiling mixtures in columns of small pressure drop. A design strategy for selecting the most economical distillation system, considering different types of heat pump structures (vapour recompression, bottom flash, closed cycle, absorption cycle), is proposed, based on pinch technology, primary energy rate, energy cost factor and estimated payback time of excess capital. The strategy is demonstrated by industrial case studies.