Analysis and Optimization of Operating Modes of Mini-CHP on Local Fuels in Conditions of Surplus Electric Power Capacities in the Unified Energy System of Belarus. Part 2

The modern development of power engineering is accompanied by a number of trends, among which one can note the decarbonization of energy production processes; an increase in the share of electricity in the balance of energy consumption due to the deep electrification of industry, transport and heat supply; decentralization of energy sources; an increase in the share of renewable energy sources, including the involvement in the turnover of secondary energy resources and energy from the disposal of organic waste; the development of practice active consumption and prosumerism. For the Republic of Belarus, in which forests are one of the main renewable natural resources and the most important national wealth that ensure the sustainable socio-economic development of the country, its economic, energy, environmental and food security, in the context of decarbonization of the power engineering sector, it is relevant to determine the importance and location of energy generating equipment using local fuels (LF), especially for heating capacities and polygeneration plants. The paper presents the results of a study conducted to evaluate the effectiveness of using mini-CHP plants on LF. The analysis of the archived data of the automated process control system of an operating mini-CHP with a heating ORC unit (Turboden 14 CHP) made it possible to evaluate its maneuverable characteristics with reference to the operating modes of the centralized heat supply system with a predominance of municipal and household heat load in it. It has been shown that the average rate of change in power is 1.5...3.0 % min; respectively, the time to reach rated power under normal conditions exceeds 40 minutes; the time to start the unit from a “cold state” varies from 20 minutes to 2 hours. Therefore the assumption has been confirmed that the studied ORC unit in particular and mini-CHP plants of a similar type as a whole cannot be considered and used as a maneuverable energy source without additional modernization. The conducted numerical study made it possible to show the opportunity of planning effective operating modes of a heating ORC unit in the configuration of the basic thermal circuit of a mini-CHP on LF with the integration of a hydrogen production module into it based on the forecast of the daily schedule of thermal energy consumption and taking into account the dynamics of changes in outdoor air temperature. Conceptual block diagrams of integrated polygeneration systems are also presented; they stand out for the use of hydrogen generation equipment from over-produced electricity during the operation of mini-CHP plants according to a thermal schedule and participation in the coverage of the electric load schedule of the Unified Energy System of Belarus. The use of thermal circuits with thermochemical hydrogen production technology and the operating mode of the ORC unit at rated power is shown to be promising for newly designed mini-CHPs on LF.