Improvement of the control system for operating modes of centralized hot water supply from a central heating point
Abstract
Improvement of the control system for operating modes of centralized hot water supply from a central heating point
Incoming article date: 07.02.2021The paper provides an overview of the applications in central heating points (CHP) of technologies and equipment to improve energy efficiency and quality of heat supply from district heating systems. The main equipment and characteristics of the hot water supply system taken as an example of the central heating station "MGU" are given. Described is the method of choosing the heating circuit of the central heating station from the ratio of the maximum loads of hot water supply and heating. For the adopted example of a central heating station, based on the above characteristics, the main indicator of energy efficiency is the specific consumption of electrical energy for the transport of thermal energy. Factors that have the greatest impact on this indicator: coefficient of uneven consumption of "hot water"; quality of regulation of hot water supplied to the hot water supply network; precise control of the productivity of the boosting and circulation pumping stations. The standard total power of the pump drives has been determined to be 13.58 kW and the range of actual power is from 10.79 kW to 22.04 kW.To reduce the influence of factors in the control scheme, it is proposed to use flow (pressure) regulators to maintain a constant direct-acting pressure drop. Use the pressure (pressure difference) of hot water discharged to the DHW system and returned from the system as balancing forces for this regulator. The parameters of hot water of rational modes of operation of the hot water supply system from the central heating station "MGU" were determined: temperature of hot water at the outlet of the heat exchange equipment 75 ° С; hot water pressure at the outlet of the heat exchange equipment 45 m; hot water pressure at the inlet of the circulation pump 25 m. The implementation of the proposed option without the inertial control scheme for the temperature of "hot water" and the developed rational modes of operation of the hot water supply system, according to the assessment of efficiency indicators, will reduce the specific consumption of electrical energy in the central heating station by 28.4% from 0.631 kW * h / m3 to 0.452 kW * h / m3.
Keywords: central heating station, hydraulic mode, flow regulator, pump characteristic