Complex Assessment of Cogeneration Installations on Biofuel at Work Basic and Variable from Basic Loading Mode

Abstract

The efficiency of cogeneration plants on biofuel in the base and distinct from the basic operating modes is estimated. Cogeneration plants with piston and gas turbine engines and with heat exchangers for water heating with exhaust gases have a fuel efficiency of more than 90%. The engines of these units operate on liquid and gaseous fuels, which are problematic for Ukraine, and therefore, the volumes of biodiesel and biogas use for them are increasing. The existing heat and power supply systems (HPSS) operate both in the basic mode and in variable load schedules.

The effectiveness evaluation has been carried out using the system analysis method.

There has been considered a district water heating boiler with a constant load of hot water supply during the year, which is 20 MW. Electricity for the own needs of the boiler is taken from the power grid. In the boiler room it is proposed to install a heat pump plant (HPP) with a compressor drive from cogeneration piston or gas turbine engines. The method of system analysis showed that the use of cogeneration engines in a water-heating boiler with a constant heat load is reasonable.

Also, the efficiency of cogeneration plants under the variable operating conditions is considered on the example of the enterprise HPSS. The thermal load of the enterprise (3 MW) is provided by a water-heating boiler house with gas fuel. Electricity needs are provided by the electrical network. The maximum consumed electric capacity of the enterprise is 4.3 MW. The enterprise operates 6500 hours a year under relative electric loads. In this case, the performed calculations showed the inexpediency of replacing the existing HPSS with cogeneration engines. The reasons for this are: additional operating costs, a decrease in the efficiency of engines with reduced load, high cost of engines.