Energy Efficiency Optimization Of Coal To Methanol Process Based On Temperature Difference Contribution Δ_Tcon

Development of coal chemical industry in China is prosperous, since China is acountry who is rich in coal, oil-poor, less gas and whose coal reserves are third in theword. Coal to methanol as one of coal chemical important applications is a processwhose energy-consuming and equipment investment are high. The energy efficiencyoptimization of coal to methanol process plays an important role in reducing energyconsuming and improving the core competitiveness of enterprises.The pinch technology based on temperature difference contributionΔTconforeach stream is different from the traditional one based on minimum approachtemperature for all streams. The stream property differences which are concernd withheat transfer capability are considered in the heat exchanger network (HEN)optimization, and the influences of factory equipment parameters and stream flowstates are also took into account. Each stream temperature difference is morereasonable and the optimized solutions are more practical. This paper is based on a600kt/a coal to methanol device, specific work as follows:(1) The calculation method and steps of temperature difference contribution wereelaborated, and the differences between pinch technology and diverse pinchtechnology based on temperature difference contribution were reviewed. Both theirarea targets were calculated with pseudo-Bath Formula method. With the same energyconsumption, the heat exchange area of diverse pinch technology based ontemperature difference contribution was less than the one of pinch technology, and aexample was offered. Diverse pinch technology based on temperature differencecontribution was superior to pinch technology in HEN design and current HENoptimization.(2) The computer models of coal to methanol were built through Aspen Plus, andthe simulation results were agreed well with the site data.(3) The energy efficiency of a600kt/a coal to methanol device was studiedthrough diverse pinch technology based on temperature difference contributionΔTcon.Coal gasification and shift conversion, rectisol, methanol synthesis and distillationwere used as three separate subsystems for HEN optimization.(4) For coal gasification and shift conversion subsystem, solution1: reducing 0.3MPag steam by45.1%which is overproduction in current factory; increasing1.2MPag steam by2.59%and newly producing2.5MPag steam19.03MW. Solution2:reducing0.3MPag steam by51.3%and increasing1.2MPag steam by22.3%. Forrectisol subsystem: saving refrigerant ammonia by32.98%. For methanol synthesisand distillation subsystem: saving hot utility39.34%, cold utility25%.