Распределение и транспортировка теплоносителя between consumers occurs through a special heating network. It is one of the main elements of the entire structure of engineering communications. Reliability and quality of transmission directly depend on how it works. Heat pipelines are not the only elements of this structure. In addition to them, it also includes various facilities. These include, in particular, throttle and pumping stations, heat points.
Тепловая сеть, основанная на централизованной the supply scheme, in its structure is divided into two levels: main and quarterly (microdistrict). The first consists of elements connecting heat sources with local (district) distribution points among the final consumers. In most cases, they are a looped pipe system (diameter 500-1400 mm) and engineering structures. These elements are located throughout the city, which ensures the reliability of the transmission and the ability to meet the demand for consumption. Due to the separation significantly simplifies the operation of heat networks. Thus, various control schemes are created that increase the reliability of work and increase the quality of supply. The design and installation of heat mains of the trunk type are carried out taking into account possible failures in the operation of any underwater element. In this connection, backup links are created. They are connected to heat sources. With this approach, a unified management system is created. It is able to smoothly provide the declared indicators of thermal and hydraulic regimes. In this case, the work is carried out even if one of its elements fails (supplying source, one of the main branches). The distribution of the coolant under such conditions occurs more qualitatively, the losses due to the transmission are reduced, fuel economy is observed.
The rules of heating networks includespecial elements with which the structure is managed. These include, in particular, locking mechanisms - valves. With their help, the total heating network is divided into separate sections. The impact on the valves allows you to enable (disable) small sections of the line, as well as pumping stations and throttle stations located on them. Most modern appliances are electrically driven. They are placed on average every 1-3 km of the highway. General network management includes monitoring of the mode of operation and the state of structural elements, warning of possible problems. To protect against water hammering, a special discharge device is installed at local points.
These structures are brancheddeadlock systems. They are connected with thermal points. Management takes place both in manual and offline modes. Such a structure has a diameter of up to 400 mm; therefore, interruptions in the supply of thermal energy to consumers as a result of the failure of such a network is considered permissible. However, as a result of the general design of the supply chain, in the event of a malfunction only a small part of the end users suffers. Repair of heating networks in this case does not take much time. Items through which the carrier enters the system are automated. This allows you to save money when using heat.
Connection of distribution networks to the commonthe system occurs with the help of mixers or pumps (mixing circular), less often through water heaters. The use of the latter makes the system more flexible and reliable. This is possible due to the separation of the hydraulic modes of the main and distribution systems. The carrier entering the general networks from different sources may have different temperatures exceeding that which it already has in the pipeline. Supply systems, equipped with pumps, exclude hydraulic isolation of highways from distribution circuits. As a result, management of the relevant emergency mode is complicated. In this case, it becomes possible to maintain independently with the help of a pump in distribution networks of circular and temperature conditions that will differ from the main ones.
Схема большой структуры тепловой сети имеет two-level view. At the top is a circular highway. Branches to the heat points of the districts depart from it. The connection uses the ordinary method. In case of failure of the section of the highway to which the heat point is connected, the final consumers lose heat energy. Users are connected to the district point via local systems - this is the lower level.
В магистральную сеть теплоноситель поступает из CHP and district boiler house. In this case, it is possible to carry out the process of reserving the supply if one of the points for heating the carrier breaks. This is done by installing a jumper on the supply and return lines. The combination of these elements forms a single ring heat network. The projected diameter of the conductive elements of the systems is calculated in such a way as to ensure the carrying capacity of the required carrier even in emergency situations. In conditions of stable uninterrupted operation, the coolant moves through all the heat lines of the network. In this case, the use of jumpers loses its meaning. For more efficient use of jumpers and reduce the cost of heating the coolant, the "unloaded reserve" method is used. In this case, there is a complete overlap of the jumpers. The jumpers are switched on only if the elements of the heating network break down.
These elements are movingcarrier in the form of which water acts. Heat pipes are installed above ground and underground methods. In the first case, the gasket has a number of significant advantages: increased service life, easy control of the system, easy access to eliminate the problem. However, installation of an aboveground heat conductor in the conditions of modern cities is practically impossible due to architectural constraints. Under these conditions, most systems are underground. For the installation of such pipelines special channels are pulled out.
Перед рабочим запуском осуществляются тепловые heat network testing. Installed elements are filled with hot water of different temperatures. The fluid is subsequently repeatedly drained over its service life. As a result of all the internal effects of the pipe wall change, the way out of this situation is the installation of compensators in pipelines. The two ends of the section are fixed on the supports. A compensator is installed in the middle. Additionally, pipelines are fixed around heat exchangers, pumps. This is done to relieve the load caused by temperature distortion. Supports are placed in channels or special chambers. In the channels of the pipeline is placed on the movable supports. In order to continuously monitor the state of the systems, special underground chambers are constructed. They place various valves, drain valves, air valves and expansion joints. In some cases (for example, with a water pipe diameter of more than 500 mm), ground pavilions are erected to carry out testing of heating networks and more comfortable maintenance. Placing points and pumping stations occurs in specially equipped buildings.
Currently there are a huge numberschemes of heat networks and methods of their installation. Therefore, at the design stage, several options are considered. Comparing all possible conditions, make technical and economic calculations, the least cost option with the best characteristics is selected. According to these calculations, the diameter of the elements used, the insulating materials and their thickness, the power of the installed pumps are determined. In addition, cost accounting for the construction and maintenance of the heat pipeline, for heat loss during transmission from the source to the consumer is kept.
Most currently in useheating networks in Russia were built back in the USSR, after the collapse of which funding for the transfer and renewal of existing heat pipelines was sharply reduced. Planned inspections of the state of the systems and their regular replacements were ceased, state control also began to weaken.
