New Integrated Process for the Efficient Production of Methanol, Electrical Power, and Heating

Abstract

In this paper, a novel process is developed to cogenerate 4741 kg/h of methanol, 297.7 kW of electricity, and 35.73 ton/h of hot water, including a hydrogen purification system, an absorption–compression refrigeration cycle (ACRC), a regenerative Organic Rankine Cycle (ORC), and parabolic solar troughs. The heat produced in the methanol reactor is recovered in the ORC and ACRC. Parabolic solar troughs provide thermal power to the methanol distillation tower. Thermal efficiencies of the integrated structure and the liquid methanol production cycle are 78.14% and 60.91%, respectively. The process’s total exergy efficiency and irreversibility are 89.45% and 16.89 MW. The solar thermal collectors take the largest share of exergy destruction (34%), followed by heat exchangers (30%) and mixers (19%). Based on the sensitivity analysis, D17 (mixture of H2 and low-pressure fuel gas before separation) was the most influential stream affecting the performance of the process. With the temperature decline of stream D17 from −139 to −149 °C, the methanol production rate and the total thermal efficiency rose to 4741.2 kg/h and 61.02%, respectively. Moreover, the growth in the hydrogen content from 55% to 80% molar of the feed gas, the flow rate of liquid methanol, and the total exergy efficiency declined to 4487 kg/h and 86.05%.