According to reports, the length of thermal systems in EU has reached 185 thousand km. This figure does not fully reveal the scale, branching and complexity of their creation. That is why this article will address issues related to the design of heating networks and the heat supply of settlements in our vast.
Any heat supply system is designed for heating, hot water supply and ventilation of buildings and structures of various nature, as well as industrial facilities. As a rule, heat sources are boiler houses and CHPPs (combined heat and power plants) that produce heat energy by burning hydrocarbons.
The main product of thermal energy sources is steam and hot water, which are subject to serious requirements. The thing is that when an untreated liquid is heated, some of the solid particles and minerals contained in it are deposited on the walls of the pipeline and equipment, which significantly reduces their service life. To remove impurities, almost every boiler house and CHP has water treatment and softening points.
Any heat supply system consists of a heat source and transport systems through which it is delivered to the consumer. The latter are heat-using equipment operating in engineering systems.
On the territory of Europe, the most common steel pipeline for heat supply. In addition to pipes, in the construction of heating networks, they use: supports, expansion joints, control, pumping equipment, heating points.
Classification and design features
Heat supply systems are classified as follows:
- Decentralized. Delivery of the coolant is carried out from the boiler room or from the house (apartment) heat generator.
- Centralized heating systems. There are four varieties of them:
- District (within the district of one settlement).
- Heat supply of a group of buildings.
City heating systems are distinguished by:
The type of coolant produced, which, in turn, is classified according to thermal potential: up to 150 ° C; from 150 to 400°C; from 400°С.
Important! The domestic sector uses a low-grade coolant, where the temperature in the supply pipe does not exceed 150°C. and the pressure is 1.4 MPa. High-potential — in steam systems it is used in heat supply schemes of enterprises.
- Heat production method.
- Heat generation takes place separately from electricity generation.
Simultaneous receipt of heat and electricity.
Important! The second method of district heating wins significantly in terms of efficiency. It’s all about the possibility of simultaneously generating electricity and heat by burning low-grade hydrocarbons, which are impossible or extremely difficult to use in boiler houses.
- The method of supplying hot water from the source to the consumer.
- Open means drawing water for hot water supply directly from the heat source.
- With the closed method, the coolant is used exclusively for heating water from the water supply system in special devices — boilers.
- pipeline number. The most widespread in EU are two-pipe systems.
- According to the method of providing the consumer with heat, the heat supply systems of cities are:
- Designs where the consumer is connected directly to the heating networks. Heating points are located at the junction point.
- Systems where distribution points are located between the heat producer and the consumer. In them, the initial characteristics of heated water can vary based on the actual heat consumption.
The advantages of the second method are obvious: when placing distribution points, it is possible to reduce initial costs due to the reduction in equipment used.
Basic heat supply schemes
Today in EU, two schemes of heat supply systems are used, differing in composition and design.
- The first option involves the supply of heated water for heating and hot water needs through the same transport networks. Water is drawn from the supply line, which creates a situation where different volumes of water flow through two branches of the pipeline.
- According to the second scheme, heated water is supplied only for heating needs. To create a hot water supply, points for heating tap water with a heat carrier are used.
The advantages of the first scheme are the low cost of the project (heat exchangers are not required) and operation. The disadvantage is high water losses and deterioration of its quality.
The advantages of the second are stable temperature and water quality, ease of control. The disadvantage is the rise in the cost of hot water supply for subscribers, due to the use and maintenance of additional equipment (boilers).
Important: the development of a city heat supply scheme is the most important process to provide the population, industrial and cultural facilities with heat and hot water with minimal environmental impact.