Automation of heating points. Thermal point - this is a kind of technological unit through which two circuits pass - heating and hot water supply. Heating circuit closed, all the water circulating in it returns back, from hot water circuit hot water is taken by consumers, and unused water is returned to the heating unit, where it is mixed with cold water from the water supply.
Water heating in both circuits is carried out in heat exchangers using a heat carrier circulating in the heating network. Heat exchangers can consist of several stages. Appropriate pumps are used to ensure the movement of water through the DHW and heating circuits, while the pumps can also supply cold water and make up the heating circuit.
An example of a functional diagram for controlling a heat point is shown in the figure. The lines indicate the readings of which sensors affect the actuators and individual circuit devices:
Automation of heating points
The automatic control system for an individual heating point is designed for:
- maintaining the temperature of the coolant supplied to the heating circuit (or the temperature in the heated room) at the level set by the operator. To improve the energy efficiency of the system, it is provided weather control. In this case, the system itself determines which temperature in the circuit will be optimal by analyzing the air temperature outside. This avoids "overheating" and saves energy resources;
- maintaining a constant differential pressure in the heating circuit. When the pressure in the circuit decreases, the make-up line is automatically switched on, adding water to the circuit in order to provide the set pressure in the system. The control system can diagnose a break in the heating circuit by the duration of the make-up circuit operation:
- Regulation in the hot water circuit of the supply water temperature, the level in the storage tank (if a storage tank is installed) and the pressure of the water supplied to the consumer:
Thus, in normal operation heating station automatic control system provides:
- Maintaining the set water temperature in the heating supply pipeline with correction for the outdoor temperature;
- Maintaining the set water temperature in the hot water supply pipeline;
- Management of pumping groups of heating and hot water circuits with automatic input of a backup pump in case of an accident of the main pump and periodic change of the operating pump;
- Protection of circulation pumps from "dry running";
- Management of the feed valve of the network heating circuit;
- Diagnostics of the state of temperature sensors;
- Automatic or manual mode of operation with registration of the fact of mode change;
- Indication, registration of emergency situations and response to them;
- Displaying the values of technological parameters and events in the system;
- Data transmission over an industrial network for dispatching.