Аннотация
The main scope of this paper is to estimate the long-term impact of multiple-fuel use and plant renovation on a DH system water performance. The originality of this work is the application of this method for the complicated, branched CHP plant with a large heat output and high capacity, widespread in Russia. Suggested configuration for a renovation of a CHP plant supplied with steam includes main DH network feedwater line, a heat pump, low-temperature water conduit, electric boiler, and low-temperature conduit feedwater line. The heat pump and electric boiler need approximately 15% less electricity from the national grid for supplying the same amount of heat to the network. The fuel amount is reduced on average by 7% and a further reduction of 9% occurs if after-deaerator extraction is fully disabled. The drop in the costs is therefore on average 18% taking into account fuel costs of coal set to be half of the price of electricity. The steam alternative replaces flow-intensive water option, that is why it leads to a lower makeup, and this replaces more heat totally, that is why it is better than the existing case. The concept presented in this work is valid for any cold-climate region where alternative makeup methods are sought. Based on the idea proposed, a novel model of makeup system for central plant design and stability analysis was derived. The results presented in this paper may be used as input for future analysis.