Research On The Process Of Coal/natural Gas Complementary Co-production Of Oil-electricity

As the most important energy and chemical raw material,petroleum is related to national economic development and strategic security.China is suffering from large oil consumption and high dependence on foreign countries.The development of synthetic oil conversion technology using coal or natural gas as raw material is an effective way to alleviate the oil shortage and promote the overall adjustment of the energy structure.China is rich in coal resources,and the traditional coal-based F-T synthesis technology and thermal power generation are short of energy efficiency and environmental friendliness.Therefore,seeking efficient and clean conversion of coal has always been the goal of researchers.Based on this,technologies such as the cascading utilization of coal,multi-energy complementation and coal poly-generation are increasingly favored by the researchers.It has important significance in reducing barriers in the process of coal single thermal conversion and improving energy utilization and economy.Combining the characteristics of coal and natural gas in their conversion processes,the paper proposes a new process of oil and power co-production from coal and natural gas(CN-T-OP).The new process is modeled and simulated by ASPEN PLUS software,then analyzed its feasibility from the aspects of thermodynamic and technical economic.Low-temperature cryogenic of oxygen generation,coal partial gasification,dual fuel steam methane reforming,rectisol,low-temperature slurry bed of F-T synthesis,gas-steam turbine combined cycle power generation process units are adopted in the CN-T-OP based on ASPEN PLUS software,realizing the complementary utilization of coal and natural gas in a system and the integration of chemical and power systems with different characteristics.In view of the partial gasification characteristic of Yulin bituminous coal and the optimization of poly-generation system's energy flow distribution.The key parameters,oxygen-carbon ratio(O/C),steam-carbon ratio(S/C),coal input of coal gasification unit and F-T gas cycle ratio(R)of F-T synthesis unit are studied and discussed.The results show that when O/C=0.2,S/C=0.1 and coal input of 5 kg/s,the gasification temperature and carbon conversion are 959? and 53.8%,respectively.The reforming temperature and methane conversion are 950? and 92.6%by the means of coal char combustion providing heat for reforming unit,respectively.The total hydrogen-carbon ratio of syngas from coal gasification and natural gas reforming is around to 2.2,which means that the syngas produced is suitable for F-T synthesis without further adjustment of its hydrogen-carbon ratio.The circulation of F-T gas enhances the yield of synthetic oil,but when R is higher than 0.9,the F-T synthesis unit has a sharp increase in the exergy loss,resulting in a decrease in system energy efficiency.Therefore,10%of the F-T gas is matched with the gas turbine for power generation.With the optimal operating conditions of process,the system's synthetic oil production efficiency and energy efficiency are 34.4%and 52.4%,respectively.The synthetic oil output is 1.87 kg/s and the net power output is 38.35 MW.The CTL process is established as a reference system.The energy efficiency of CTL is 33.3%,indicating that the energy utilization of the cascading utilization of coal with natural gas complementary poly-generation technology proposed by the new process is more efficient.In the actual market situation,the economic performance analysis results show that the total investment of the CN-T-OP project is 232.13 M$,which is 14.11 M$ higher than that of the CTL project.However,the total operating cost of the CN-T-OP project is 16.74 M$/a,which is 59.64%lower than that of the CTL project.From the perspective of technical economy,the CN-T-OP project has market application prospect.