铝电解槽低温烟气余热发电系统热力分析

Thermodynamic analysis of power generation system based on waste heat from aluminium reduction cell

采用R245fa为循环工质，以某铝业公司一个净化系统的低温烟气为研究对象，对该烟气余热发电系统进行热力分析。该净化系统的烟气流量为5．0×10^5m^3·h^-1，温度为150℃。结果表明：当传热窄点一定时，系统存在一个最佳蒸发压力，此时系统的输出净功最大。针对所研究的烟气，系统的最佳蒸发压力为1．0MPa，此时该净化系统的最大输出净功为1055kw，相当于吨铝能耗降低1．6％。最佳蒸发压力下，系统的热效率和炯效率分别为10．3％和40．5％。系统各部件中，蒸发器的炯损失最大。为增加系统的最大输出功率，应重点降低蒸发器的炯损失。当烟气温度从100℃增加到180℃时，系统的输出净功从335kW增大至1843kW，相当于吨铝能耗降低0．5％-2．8％。

The thermodynamic analysis of a power generation system using R245fa was performed for recovering the waste heat from a purification system in a given aluminium company. The mass flow rate of exhaust gas is 5.0×10^5m^3·h^-1 and temperature is 150℃. The results show that as the evaporating pressure increases, there is an optimal pressure where the net work of ORC system is maximized. For the given condition, the optimal pressure is 1.0MPa and the corresponding net work is 1055kW. It is equivalent to energy consumption of one ton aluminium reducing 1.5%. Under the optimal pressure, the thermal efficiency and exergy efficiency are 10.3% and 40.5%, respectively. Among the several components of system, the evaporator has the highest exergy loss. It is important to reduce the exergy loss in evaporator for improving the maximal net output. The system net output increase from 335kW at 100℃ to 1843kW at 180℃. It can reduce the rate of energy consumption for one ton aluminium from 0.5% to 2.8%.