Simulation of Carbon Dioxide Capture from Reformate Gas Using 30 wt.% Monoethanolamine (MEA).

摘要

Hydrogen is usually produced by steam reforming of natural gas in large-scale processes. The growing demand for H2 production also means the increasing release of large amounts of CO2. Because of its greenhouse effect, it becomes very essential to remove CO2 from such plants. Also, the removal of CO2 is a very essential step in purifying the hydrogen produced. Carbon dioxide absorption using monoethanolamine (MEA) is considered as a promising technology to remove CO2. However, the major drawback of this system is the energy used during the solvent regeneration step. Therefore, reducing the energy consumption in the regeneration unit (re-boiler heat duty) of the capture process becomes very important in order to improve the process performance and make this process more economically feasible.;This work presents modified process strategies to capture CO2 from reformate gas by using 30 wt.% MEA in order to obtain the minimum energy requirement. The approach is to simulate and optimize the base line conventional CO2 capture process, and then modify the conventional process to minimize the energy used. The modified processes of this work include the reformate gas heat utilization and a split flow process configuration. The models were applied to three different CO2 recovery efficiencies; 90%, 95% and 99% from the reformate gas. The optimum thermal energy requirement for the base case at 90% CO2 recovery was found to be 3.139 GJ/ton CO2, 95% and 99% CO2 recovery were 3.202 and 3.815 GJ/ton CO2, respectively. The process simulation results showed that the external energy requirement for the re-boiler can be saved by using the reformate gas heat utilization process by supplying the heat directly to the re-boiler. Energy savings were 56.8% with 90% CO2 recovery, 52.9% and 42.59% with 95% and 99% of CO2 recovery, respectively as compared to the base case schemes. The external energy requirement for the re-boiler can also be minimized by using a comprehensive process integration configuration by 13.98% (90% CO2 recovery) and 12.2% (95% CO2 recovery) compared to the base case. However, the result from 99% CO2 recovery showed a higher energy requirement than the base case by 2.67%. This is due to the fact that the lean amine temperature of the split flow process is higher than the base line process. With a combination of the two strategies, the reformate gas heat utilization and the split flow process configuration, the external energy requirement for CO2 capture from reformate gas process was reduced by 70.78% for 90% CO2 recovery, 64.9% and 39.97% for 95% and 99% CO2 recovery, respectively, compared to the base line process.