The Experience in Operation and an Efficiency Analysis for the Use of a Backpressure Steam Turbine Generator Unit in a Boiler House

Abstract

Turbine generators can be used for utilization of the potential of steam lost in pressure-reducing and cooling units of operating boiler houses. This approach brings about an independent source of power the price of which can be much lower than the established tariff. The features in reconstruction of a boiler house in the city of Bratsk, Irkutsk oblast, carried out in 2012 are examined. Steam generated in a KE-50-14-225 boiler is routed to a 0.3–0.5 MPa common header for use in deaerators and steam-water heaters. Considering an increase in the electricity tariffs, a decision was made to install a 500-kW backpressure turbine generator in the boiler house in parallel with the pressure-reducing unit to generate auxiliary power. The criteria for selecting the number and power of turbine generator units depending on the required steam generation, operating conditions of the consumer, the level of electric loads of the boiler house, and the existing heat supply system are shown. The specifics in operation of the turbine generator unit are examined. To ensure safe and reliable operation of the unit, it is advisable to increase the number of monitored parameters through extension of the normal instrumentation system. The discounted payback period for the reconstruction cost and additional costs for installation of a second turbine generator unit are estimated. The boiler house regimes, a change in the prices for fuel and electricity, and the operator’s labor cost are considered. After installation of the turbine generator, the specific fuel consumption for electricity generation amounts to 180 g.c.e /(kW h). In 2017, the electricity generation cost was 1.23 rubles/(kW h) with the average tariff of 2.13 rubles/(kW h). The discounted payback period for the performed reconstruction does not exceed 6 years, and that for further reconstruction is 8 years.