Improving the efficiency of CHP plants through the combined production of hydrogen, heat and electricity

A thermal circuit was developed for the conversion of a cogeneration power plant to trigeneration with the production of hydrogen as a new product. The Severnaya CHPP-21 of St. Petersburg, which has 5 power units with a steam turbine T-100/120-130-3, was chosen as the object for switching to a trigeneration mode of operation.
The purpose of the work is to evaluate the effect of switching a cogeneration power plant to trigeneration production of electricity, heat and hydrogen, taking into account the characteristic operating modes of the main equipment of
a power plant.
Research methods include simulation modeling of the thermal scheme of the steam power plant in the United Cycle program, modeling of the process of steam reforming of methane in the Aspen HYSYS program, as well as thermodynamic analysis of heat recovery units.
A new thermal circuit of a trigeneration power plant with a methane steam reforming unit (MSRU) integrated into its structure was developed. An assessment of the influence of the MSRU on the characteristic modes of operation of a combined heat and power plant (CHP) was carried out. In winter mode with low heating loads, fuel savings in the combined production of electricity, heat and hydrogen amounted to 2.5%. The coefficient of fuel heat utilization increased from 78.61% to 80.63%. In the summer mode of operation of the station, the most profitable mode turned out to be the mode with the operation of only one power unit. Fuel economy when integrating a steam-reforming unit into the CHPP was 13.8%. The coefficient of fuel heat utilization increased from 62.26% to 72.25%.
The proposed research algorithm is applicable to thermal power plants of any type. The developed schematic thermal circuit of a plant with combined production of hydrogen, heat and electricity is applicable for implementation at most thermal power plants, which have a sufficient number of typical cogeneration steam turbine units.
The study shows that during off-peak times of electricity and heat supply, thermal power plants can be used to produce additional technological products.

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