Synthesis of heat exchanger network with complex phase transition based on pinch technology and carbon tax

The aim of this paper is to integrate carbon emissions into the synthesis of heat exchanger network for an industrial process with a four-stage pyrolysis gas compression cycle and depropanizers. Problem table is used to determine the pinch point for the design of heat exchanger network. Due to the complex phase transition of the mixture in the system, the phase transition is considered as a pseudo-stream with constant heat capacity flow rate according to its thermal load and material characteristics within several individual temperature intervals. The contribution of carbon tax is also introduced to the total annual cost to determine the suitable minimum approach temperature(???T-min). Compared with traditional pinch point method, ???T-min is determined as 8 degrees C instead of 9 degrees C due to the consideration of carbon emission. The pinch point is obtained at 80.15 degrees C for hot streams and 72.15 degrees C for cold streams, under which the minimum hot and cold utilities required by the heat exchanger network are 28046.89 kW and 69324.05kW respectively. The total annual cost is saved by 4,446,559 USD.a(-1) and the carbon emission is reduced by 96689.31t/a. Results indicate that the consideration of carbon emissions based on carbon tax is helpful to obtain a better heat exchanger network in terms of total annual cost and energy efficiency on the way to carbon neutrality. Copyright (c) 2022 The Authors. This is an open access article under the CC BY-NC-ND license(https://creativecommons.org/licenses/by-nc-nd/4.0/)