Optimisation of Operational Parameter and Economic Analysis of Amine Based Acid Gas Capture Unit

Abstract

Electricity demand in Malaysia has been projected to escalate and this has led to additional coal-fired power plants being built. Combustion of coal has released greenhouse gases such as CO2 into the atmosphere. It is predicted that CO2 emission from coal fired power plants will grow 4.1 % annually to reach 98 Mt by 2020. Greenhouse gases like CO2 is claimed to be the root of global warming, closely related to the verdict of 2 °C increase in global temperature. To resolve this issue, amine unit has been integrated into the power plant for acid gas removal. Amine is highly preferred due to its characteristic of high selectivity. The drawbacks of this technology are costly operation, energy intensive and exhibits process dynamic. Detailed process simulation utilising Aspen Plus is able to optimise the process and overcome these limitations. In steady state simulation, the optimal operating conditions of absorber and stripper are found. Absorber should be operated at 30 °C (1 atm), while stripper at 120 °C (2 atm). The MDEA to MEA ratio is fixed at 3 : 7 with 40 wt% of amine in the solvent. By comparing the optimised parameters to TNBR’s result, acid gas removal rate showed an increment of 5.5 % which resulted in 91.27 % of CO2 removal rate. 300 % reduction in energy penalty and heat duty cost are achieved when MEA/MDEA is used instead of MEA. A more economical and feasible acid gas removal process with optimum operation is achieved. This has provided better insight for large scale implementation of amine unit in industries with low energy penalty.