Operation And Optimization Of 600MW High Back Pressure Cogeneration Unit With Integrated Solar Assistde Heating

Under the vision of"carbon peaking and carbon neutrality",the technology of combining solar energy with coal-fired units has been born,which can give play to the flexible peak shaving ability of coal-fired units.At the same time,the coal consumption of coal-fired units has also been reduced after the integration of solar energy,and the two are naturally complementary.In the integration method,solar energy is mostly used to replace heat return extraction or heat supply extraction to heat boiler feed water or heat network return water of coal-fired units.Therefore,a 600MW coal-fired generating unit is used as an example to build a solar-assisted coal-fired generating unit and a solar-assisted heat pumping and heating unit by combining a solar collector system.The numerical analysis reveals that the integration of solar collector system reduces the amount of heat extraction and heat supply extraction on the coal-fired unit side,which causes more steam to do work in the turbine of the coal-fired unit,which in turn leads to more spent steam in the unit and generates excess cold source losses.The high-back pressure heating unit can greatly utilize the spent steam for heating by increasing the back pressure of the unit;and the combination of solar energy and high-back pressure heating technology can reduce the influence of weather on solar resources.Based on the 600MW combustion generator set,the solar-assisted high-backpressure heating unit system is built,and the operation mechanism of the solar-assisted high-backpressure heating unit system is revealed quantitatively and qualitatively based on the first and second laws of thermodynamics,combined with energy flow diagrams and wiring flow diagrams.The results show that the coal consumption of both coal-fired generating units and vapor extraction heating units decreases and the cold source loss increases after the integration of solar collector system,and the cold source loss of both coal-fired generating units and vapor extraction heating units increases by 22.281 MW,53.072 MW and 18.879 MW respectively after the integration of solar energy.Its heating capacity is increased by 38.505MW,and its coal consumption for power generation is reduced by 129,472.8t/year.The solar-assisted high-back-pressure heating unit has the highest total radiation conversion efficiency and performs best in the comparison study.An in-depth analysis was conducted on the impact of changes in parameters such as unit power generation,unit back pressure,and supply and return water temperature on the operating economy of solar assisted high back pressure heating units.Through calculations,it was found that when the unit power generation increases,the revenue of solar assisted high back pressure heating units decreases;When the back pressure of the unit increases,the heating revenue of the solar assisted high back pressure heating unit decreases,and the revenue in terms of coal saving and energy efficiency increases;When the temperature of the supply and return water in the heating network increases,the heating benefits of the solar assisted high back pressure heating unit increase,while the benefits in terms of coal saving and energy efficiency decrease.Quantitative analysis of the investment cost and project recovery cycle for the transformation of solar assisted high back pressure heating units shows that the investment cost for the transformation of solar assisted high back pressure heating units is about 756131581 yuan,which can save a total of 106416 tons of fuel per year,reduce276681.6 tons of CO₂ emissions per year,reduce 904.536 tons of SO₂ emissions,and reduce 787.48 tons of NOx emissions.After the introduction of carbon trading price,the static investment return period of the solar assisted high back pressure heating system is6.09 years,and its dynamic investment return period is 7.65 years,which has higher economic and environmental benefits and can effectively promote the realization of the"dual carbon"goal.