distribution and transport of heat transfer medium between consumers going on a special heat network.She is one of the key elements of the entire structure of utilities.On how it works, and are directly dependent on the reliability of the transmission quality.Piping heat networks - are not the only elements of the structure.Apart from these, it also includes various structures.These include, in particular, the throttle and pumping stations, heat points.
structure
Thermal network, based on centralized supply scheme, its structure is divided into two levels: the main and quarter (district).The first consists of the elements connecting the heat source with the local (regional) items distribution to end users.In most cases, they are electrically connected to a system of pipes (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 much easier maintenance of heat networks.So are various control schemes that improve reliability and increase the quality of supply.Design and installation of heat supply networks of the main types are made taking into account possible failures of any underwater elements.In this regard, communications are redundant.They are connected to a source of heat.This approach creates a unified management.It is able to smoothly provide the stated performance thermal and hydraulic regimes.This work is carried out even if the failure of one of its elements (supplying power, a branch line).The distribution of coolant under these conditions takes place more efficiently, reduced transmission loss as a result, there is a saving of fuel.
Management
Terms of heat networks include the presence of specific elements by which the management structure.These include, in particular, the locking mechanisms - gate.With their help the overall heat network is divided into separate sections.The impact on the valve allows you to enable (disable) the small line segments and arranged on the pumping stations and butterfly.Most modern devices are motorized.They placed them on average every 1-3 km highway.Total network management includes the control mode of operation and state of the structural elements, warning of possible problems.To protect against water hammer in local areas established a special unit the stroke.
District heating network.Features
These structures are branched blind system.Connect it to the heating unit.The control is in the manual and in stand-alone mode.This structure has a diameter of 400 mm, therefore interruptions in the supply of consumers with thermal energy due to the failure of the network is considered acceptable.However, the total supply of the device circuits in case of failure suffered only a small part of the final consumers.Repairs of heating networks in this case does not take much time.Points through which the system gets support, automated.This allows for savings in the expenditure of thermal energy.
Connection line
Connecting the distribution networks for the entire system is done by pumps or mixers (mixing and circular), at least through water heaters.Application of the latest makes the system more flexible and reliable.This is possible due to hydraulic separation modes mains and distribution systems.The carrier entering the common network from different sources can have different temperatures in excess of that which is already in the pipeline.Supply system equipped with pumps, hydraulic isolation exclude roads from the distribution circuits.As a result, management is complicated by the appropriate emergency mode.In this case, it is possible to maintain an independent means of a pump in the distribution network of circular and temperature conditions that are different from the mainstream.
Duplex views of
scheme largest heating network structure has a two-level view.At the top is represented by a ring highway.From her depart branching to the heat of the district.The joining method used ordinary.In case of refusal plot line to which the heating unit, end users lose heat.To point users to join the district with the help of the local systems - a lower level.
Reservation feed
The backbone coolant comes from CHP and district boiler.In this case, the possible implementation of the backup process feed at breakage of one of the points of heating medium.This is done by setting a jumper on the connecting flow and return.The combination of these elements forms a single ring heating network.The projected diameter of the conductive elements of the systems is calculated in such a way as to ensure the required bandwidth media, even in emergency situations.In a stable smooth operation of the coolant moves through all heating pipeline network.In this case, use the jumper loses its meaning.For a more efficient use of bridges and reduce the cost of heating the coolant used the method of "dormant."In this case there is a complete overlap of jumpers.Enable jumper is only a failure of the heating network elements.
heating pipeline networks
on these elements made the motion carrier which serves as a water.Heat conductor installed above ground and underground.In the first case, the gasket has a number of advantages: increased service life, easy control of the system state, facilitating access for troubleshooting.However, installation of aboveground heating pipeline in the conditions of modern cities is virtually impossible because of architectural limitations.Under these conditions, most of the systems - underground.To install these pipes are pulled out special channels.
use of the system before starting the work performed thermal testing of thermal networks.Installed elements are filled with hot water of different temperatures.The fluid then merges repeatedly during the lifetime.As a result of internal influences pipe wall changes, exit from this situation is the installation of expansion joints in the piping.Two end portion fixedly secured to supports.Middle mounted compensator.Additional pipelines are firmly secured about heat exchangers, pumps.It made it to relieve pressures from thermal deformation.Props are placed in special chambers or channels.The channels of the pipeline is laid on the movable support.In order to keep the state systems are built special underground chamber.They placed a variety of valves, drain valves, air valves and expansion joints.In some cases (for example, when a water pipe diameter 500 mm) for the test of thermal networks and more comfortable service of terrestrial cameras built pavilions.Placing items and pumping stations takes place in a specially equipped building.
Selecting optimal variant of thermal networks
Currently, there are a huge number of schemes of heating systems and their installation methods.Therefore, in the design phase we considered several options.Comparing all possible conditions, produce technical and economic calculations, choose the least expensive option with the best characteristics.According to these calculations it is determined by the diameter of the elements used, insulation materials and their thickness, capacity installed pumps.In addition, it keeps records of the costs of construction and maintenance of a heat conductor on the heat loss during transmission from the source to the consumer.
Russian heat supply systems
Most exploited to date heating networks in Russia were built in the Soviet Union, which after the collapse of funding for relaying and updating of existing heat pipelines has dropped dramatically.Ceased to make routine checks of the systems and their regular replacement, control of the state also began to weaken.The overall situation with heat networks in the country began to deteriorate rapidly.In the context of significant savings we have started to decrease demands on the quality of elements used in the relaying of existing systems.Savings resulted in the cheapening of work, which affects their final quality.Constructed in the years the system had a low life and demanded the re-replacement in 5-7 years.All this led to a sharp increase in the number of problems that resulted in an increase in capacity of the emergency services.Heat losses in the transmission media is estimated to range from 20-50% of total production in the heating period and 30 to 70% - in the summer.These figures exceed by several times the rules adopted in the developed countries of Europe.
