The proximity of the gas pipeline network to the settlement does not guarantee the absence of problems with the connection to it. In conveying the most popular fuel communication different tasks, making the pressure in the pipeline is also different.
Consider how the gas transportation network and under what pressure is supplied to the consumer in its fuel line segments.
The content of the article:
- The supply of natural gas
- The composition of the gas supply system
- How is the system of gas supply
- Types and categories of pipelines
- Multistage gas supply system
- Types of urban gas pipelines according to destination
- Features City Gas Supply Planning
- Mechanisms off natural gas feed
- Useful videos on the topic
The supply of natural gas
Powered by a natural mixture of gaseous hydrocarbons, domestic and industrial equipment are well known to everyone. In homes installed boilers, columns and slabs. At the disposal of many enterprises are boilers and fenced "houses" the GRU. And the streets are arranged gas distribution stations, attention-yellow color and bright red words "Gas. Flammable. "
Everybody knows - gas is supplied through the pipes. Just as it gets in these same tubes? The path traversed by natural gas to each apartment, each house is really huge. After all, from the field to the final consumers of fuel should be sealed branched channels, stretched for thousands of kilometers.
Immediately following field production gas mixture is cleaned of impurities, and prepares for pumping. Compressor stations pumped to high pressures, natural gas is sent through the pipeline to the valve station.
Its installation and reduced pressure gaseous mixture odoriziruyut methane, ethane, and pentane thiols ethyl mercaptan and similar substances, to give it a flavor (neat odor of natural gas It does not have). Having additional purification, the gaseous fuel is sent to the gas pipelines settlements.
Then, the natural gas is supplied to the timing points within urban areas. Before sending a quarter pipeline network, the pressure of the transported gas is reduced to the required minimum. Finally gas should be in domestic gas supply network - to a gas stove, boiler or hot-water column.
Each gas processing installation equipped with a special burner, before combustion turnpike mixing fuel with air. In its pure form (i.e., without oxygen) gas flammability zero.
The composition of the gas supply system
Gas transportation pipelines and form complex structures, as well as technical device operating the supply and distribution of the flow between users. The flow rate of gas is determined by the needs of end-users - industrial and municipal organizations, private households.
Gas supply network consists of:
- pipelines of high, medium and low pressure;
- gas control device - stations (GDS), points (GCP), units (HRU);
- control units and monitoring system;
- dispatch and maintenance service.
Under high pressure gas pipeline delivering natural gas to the dispensing stations, reducing the pressure to the desired level by means of automatic regulation valve. Further, the fuel gas is sent to the network users. GDS automatically maintain pressure values within a given range.
How is the system of gas supply
Its hierarchy of classes determined transmission network elements associated with the pressure of the pumped gas.
The composition gas of the first level includes the gas communication, in which the methane pressure is high or average. For an exception is made redundant portions of dead-end gas pipelines - duplication of separate segments or banding. Creating a deadlock network is allowed only in small settlements.
The high pressure natural gas passes through several successive stages where its pressure is reduced. The process of pressure reduction in paragraphs gazoregulyatsii jumps occur, the output of which a constant pressure. In urban areas the gas communication with the pressure medium and high level formed hydraulically connected to a common network.
The use of hydraulic fracturing allows to supply gas to consumers with different pressure, even if they are located on the same street - unequal pressure gas pipelines are placed in parallel.
second level pipelines provide a supply of gaseous fuel under low pressure to the main number of consumers. Such networks are performed mixed with a predominance of blind segments. Ringing undergo a major pipelines.
Comprising a low-pressure gas pipeline should not cross a large man-made (motorway, w / d path) or natural (lakes, rivers, ravines) barriers. Do not install these communications in industrial environments.
Gas network supplying fuel under low pressure, can not form a hydraulically bound system of a large village. They are designed exclusively as a local complexes, drive multiple hydraulic fracturing, in turn, connected to the networks of average pressure, which in turn are similarly connected to the high-highways pressure.
The third level is the network of gas pipelines used to consuming objects - at the enterprise territory, in the buildings of residential and public buildings. The need for such a pressure networks defined by their purpose and performance gas-powered devices (units). Redundancy (overlap) at the third level of the gas communication is not normally performed.
Types and categories of pipelines
The division of gas supply pipelines by type is reflected in the SNIP 42-01-2002. high-pressure gas transmission pipelines correspond to the type divided into two categories.
Conductive gas communication of the first category are placed exclusively for industrial consumers sector, which consume substantial amounts of gaseous fuel under stable and high (0.6-1.2 MPa) pressure. For example, it's steelmaking plants. Connecting each industrial consumers to the gas pipeline of the first category requires the preparation of a special gas supply project.
Conducting natural gas line of the second category are for other industrial facilities, requiring the supply of the gas mixture under high pressure, but smaller (0.3-0.6 MPa) than consumers the first category. Such as gas pipelines supplying fuel boiler, heated industrial buildings.
Pipelines supplying gas medium (0,005-0,3 MPa) pressure level, are supplied to the boiler, heated domestic and administrative objects. They are also used for public buildings, requiring an increased amount of fuel.
Pipe-line low line pressure (0.005 MPa) extend to household consumers. All domestic equipment it is designed for such gas delivery characteristics. In other than the maximum pressure reducing options to achieve maximum security in gas communication for residential properties is impossible. The organization of gas supply of residential houses and highways medium pressure above is strictly prohibited.
Multistage gas supply system
The need to create multiple levels in the local natural gas supply system including caused by a consumer in need of fuel gas supply at a different pressure.
By the number of pressure stages vary following supply systems:
- Two-stage. Networks are formed under low and middle pressure, or low and high;
- Three-stage. It consists of communications with the pressures of high, medium and low;
- Shagostupenchatye. They form the pipelines with pressures at all levels.
Alternating lines of high and medium pressure is required due to the considerable length of the network of pipelines, as well as due to several transportation directions. In areas with a large population density construction of gas pipelines, conducting gaseous fuel under high pressure, it is not recommended.
Another common cause - in areas of old buildings city streets are not wide enough to stretch underneath the high-pressure gas supplying line. Indeed, the higher the pressure of the moving gas conduit, the more considerable distance required between communications and neighboring buildings.
The need to step scheme of gas supply is also caused by the technological requirements for joining and installation of gas control systems installed on buildings.
Types of urban gas pipelines according to destination
Territory of urban areas equipped with the most extensive network of gas supply communications. The structure of the urban complex supplying natural gas pipelines include the following types:
- Distributors conducting gas at different (actually needed) pressure. Provide transportation for the service area;
- branch subscriber, supplying the gas from the distribution lines specific subscribers;
- in-house and intrashop.
The planned for a city gas distribution communications network directing gas under medium to high pressure, it forms a common network.
Those. municipal consumers boiler and industrial facilities natural gas is supplied at a total gas distribution network. The construction of separate backbone networks for municipal or industrial consumers disadvantageous from the standpoint of economy.
When you select a planning solutions to urban gas accounted for layout and size of the city, the population density and building, power plants and industrial facilities requirements. Are taken into account the prospects for the future development of the city, the presence of large obstacles (artificial, natural) gas pipeline for conducting communications.
Features City Gas Supply Planning
Within the city the ideal of natural gas supply chain is bound to be a cost-effective, operationally-safe and reliable, convenient and simple to work with it.
installed on the pipeline when it is output through the pressure regulating stations, allowing you to switch the gas supplying system circuits
Pipeline gas supply network is required to allow trouble-free off some of its segments for repair. Mandatory condition - complete uniformity of units, equipment and facilities as part of one system.
When the image in Scheme urban pipelines are shown sequentially. However, the streets allowed laying parallel gas communications, provided with different pressure therein. This layout is a cost-effective, as it allows to reduce the consumption of pipes:
- a low pressure gas mains powered multiple fracturing;
- to the central methane is supplied fracturing stacked parallel pipelines medium or high pressure.
Similar laying communications circuit used to supply boilers and enterprises located within residential areas.
Structure urban building require low pressure network in a format of two unbonded zones. For redundancy at a low pressure stage fracturing of each of the two zones are connected to large diameter pipes, the conductive gas under low pressure.
In cities, small and medium size gas used two stage complex combining communication low and high pressure (up to 0.6 MPa).
If it is impossible Bookmarks gas pipe in a central pumping high pressure gas mixtures, their design power split between the high pressure area networks (stacked in the periphery) and medium pressure (created in the central parts). The result is a three-stage natural gas supply system furnished distribution pipeline diameter 50-400 mm.
Mechanisms off natural gas feed
Repairs require periodic shutdown of certain parts of the city gas Communications consisting of high pressure and intermediate level, as well as certain networks under low pressure. Therefore, the gas pipeline systems of network, public and residential pipelines and industrial facilities or several buildings equipped tripping devices - valves (another name - cork cranes).
Mounting valves is performed:
- for gas pipes in hydraulic fracturing (incoming and outgoing);
- on the branches of the main gas pipelines in the districts and neighborhoods;
- before major obstacle intersects the conduit (water, road and rail / track d).
On the outer gas valves installed in recessed wells. Together with them are mounted lens compensators intended pickup voltage readings (Mounting, temperature) on the pipeline, as well as staging procedures to facilitate removal of the closure and fittings. Wells permitted to lay on a distance of more than 2 m from the nearest or fencing construction.
Shut-off valve on the gas entry into the building is placed on the wall, with maintaining meter distance from the nearest openings. Regardless of the pressure level of branching and length of the conductive gas mixture the number of pipeline off devices should be the minimum necessary, with a justification for each location.
Useful videos on the topic
How is the gas supply of apartment buildings:
As arranged, and how to make a ball stop valves for gas lines:
pipeline system provides in good supply of natural gas only if its balance. Any work on gas transportation facilities are made exclusively by specialists of gas services. Foreign interference in the operation of the gas network are unacceptable and extremely dangerous - remember that!