Gas control points are installed near residential and industrial premises. In the article we will consider the purpose, structure and classification of hydraulic fracturing. We also give the basic principles for installing items and requirements for their operation.
Decoding and types of hydraulic fracturing
Gas control point (HF) is a complex consisting of technological equipment and mechanisms for adjusting gas pressure. The main purpose of the installation: reducing the input pressure of natural substances and maintaining a given level at the output, regardless of consumption.
Types of hydraulic fracturing relative to the installation site are:
- GRPSh (gas control points cupboard) - for this type provides for the placement of appropriate equipment in a special cabinet made of fireproof materials;
- GRU (gas control units) - for this type of equipment, it is mounted on a frame and located in the place of gas use or in another place;
- PGB (gas control block points) - with this arrangement, equipment is mounted in container-type buildings, one or more;
- Hydraulic fracturing (decoding - stationary gas control points) - with this type of equipment, it is located in specialized buildings or separate rooms, such a device is not accepted as a typical product with full factory readiness.
Classification
Hydraulic fracturing can be classified according to several parameters. For example, if possible, lower the gas pressure. Explanation of hydraulic fracturing is discussed below.
- One-stage gas control points. In such systems, the gas pressure from the input to the working one is regulated in one step.
- Multistage gas control points. In systems with too high pressure, one regulator may not be able to cope with the lowering function. In this case, the adjustment takes place in several stages by installing one or more controllers.
According to the gas outlet pressure, which is provided by hydraulic fracturing (interpretation: gas control points), the distinction is made between installations that provide the same or different pressure.
Also, hydraulic fracturing can be with one or two exits. The device may be left-sided or right-sided, depending on the place of gas supply.
The input and output of the volatile substance can be made from opposite sides of the hydraulic fracturing, on the one hand, to be vertical and horizontal.
The gas pressure at the outlet of the item may vary, while hydraulic fracturing is classified:
- low gas pressure when it decreases from high (0.3–1.2 MPa) or medium (5 kPa - 0.3 MPa) parameters to low (less than 5 kPa);
- average, with such a decrease, the outlet pressure is 0.005-0.3 MPa.
- high pressure, when the output gas indicators are 0.3-1.2 MPa.
Hydraulic fracturing lines
Decoding of hydraulic fracturing has already been given. Points can be dead end or loopback. Such a scheme is used for gas supply reliability. It consists in combining several hydraulic fracturing. It is believed that the more installations are looped, the higher the reliability of the system. A deadlock is a scheme when it is not practical to use more than one hydraulic fracturing for gas supply to a consumer.
According to hydraulic fracturing technological schemes distinguish:
- One-thread items. They are equipped with one gas reduction line.
- Multi-thread. They can be equipped with two or more parallel gas reduction lines. Such a device is used when trying to achieve maximum reliability and hydraulic fracturing performance parameters.
- With a bypass. The backup reduction line, which is used during the repair of the main line.
Regulators in multi-thread installations can be connected in parallel or in series.
The hydraulic fracturing is equipped with the following equipment:
- gas pressure reducer;
- gas filter;
- safety fittings;
- shutoff valves;
- instrumentation;
- gas odor input unit;
- gas heaters.
Two shut-off devices are installed on the backup line, between which a pressure gauge is mounted.
One-thread items
Gas control points (hydraulic fracture interpretation) with one gas reduction line consist of: technological equipment and the frame on which it is located.
The principle of operation of such devices:
- Gas passes through the inlet and enters the filter. Here it is cleaned from harmful substances and impurities.
- Then the gas is supplied to the pressure regulator through the safety shut-off valve, in which the pressure is regulated - lowering to the required parameters, as well as maintaining the values at the desired level.
If, while passing through the regulator, the pressure does not decrease to the normative parameters, then a safety-relief valve or a hydraulic lock will be activated.
If the gas has not been discharged, the safety shut-off valve is activated and the gas supply to the RN-hydraulic fracturing stops (decryption: pressure parameter at the beginning of the slam-shut device opening) no more than + 0.02 MPa — the standard set value for valve actuation (GOST R 53402-2009 Sec. 8.8.2.7).
In gas control plants, regulators of both direct and indirect action can be used.
When choosing a hydraulic fracturing with one reduction line, they usually rely on the operating parameters of the regulator: throughput, pressure at the inlet and outlet.
Multi-item items
Explanation of the abbreviation for hydraulic fracturing - gas control points, as has already been said, come with one line of reduction, with two or more.
Regulators on the gas pressure relief line can be installed both in parallel and in series.
The principle of the multi-thread system:
- One gas source is used for gas supply.
- After entering, gas is distributed along all hydraulic fracturing lines.
- At the output, the lines are combined into one collector.
Multi-thread systems are more reliable, because if one of the reduction lines fails, its functions can be performed by the others. Similar actions are carried out and, if necessary, technical work: replacing the regulator, cleaning the filter.
Schemes are mainly used at high pressure points, for example, to supply industrial consumers. Multi-thread systems are more expensive compared to single-thread counterparts, they have large dimensions.
Hydraulic fracturing with bypass line
The above describes how fracturing is decrypted and what types it happens. In this paragraph, the last option for the organization of a gas control point will be presented - with a bypass.
Bypass is called bypass, another name is backup, natural gas reduction line. It is used at the time of the main repair.
Multi-line or single-line circuits are endowed with a bypass line. It is equipped with the same equipment as the worker, but does not participate in the gas supply process, if the main line is operational.
The backup safety shut-off valve is configured to close at high pressure, and the regulator to a lower one. Thus, when the outlet pressure is exceeded due to a malfunction of the main regulator, the shut-off valve stops supplying gas to the consumer. As it is consumed, the output pressure drops and reaches the operating norm of the bypass regulator. Typically, the pressure indicator is set 10% lower than on the main line. The controller maintains this level of reduction.
“Technical Regulation on the Safety of Gas Distribution and Gas Consumption Networks” dated October 29, 2010, paragraph No. 44, prohibits the design of single-line cabinet and block hydraulic fracturing with a bypass reduction line. Only replacement of equipment that is already in operation is permitted.
Hydraulic fracturing with gas metering unit
The gas control station may be equipped with a unit for metering gas consumption. Counters are selected depending on the input and output pressure, productivity and the number of consumers.
To choose the right metering device, use the requirements that apply to measuring instruments. Counters can be direct or indirect measurements.
A hydraulic fracturing equipped with a gas metering unit consists of:
- auxiliary room (it contains electrical equipment and a boiler);
- the technological room in which the gas distribution equipment is located, it is installed on supports or brackets.
Such hydraulic fracturing is equipped with natural ventilation, which provides a three-time air purge per hour. If necessary, an automatic system can be installed.
Fracturing requirements
The gas control station must be equipped in accordance with the requirements.
- The building should be one-story. It is not allowed to equip the attic.
- The entrance width is more than 0.8 meters.
- Doors necessarily open outward and do not interfere with the operation of the item.
- Heating should be centralized.
- Three-time ventilation per hour (supply and exhaust).
- Maintaining the temperature regime above +5 ° C. When the rate decreases, the pressure regulator seat will begin to freeze.
- Lighting must be explosion proof, natural or artificial.
- The hydraulic fracturing building is equipped with a separate lightning protection.
- The internal diameter of the purge gas candles must be not less than the largest diameter of the regulator seat mounted on the equipment.
- Installation of disconnecting devices at the input and output of the line.
- All rooms - boiler room, telemetry building should be separated by airtight partitions.
In addition to hydraulic fracturing, the requirement is established: equipping the building with telemetry. It helps provide pressure control, temperature, power and door opening.
When operating the item, it is necessary to maintain the relevant documentation:
- operational passport and logbook of hydraulic fracturing;
- task to inspect the condition of the item;
- schedules for inspection, inspection and maintenance of the item;
- mode card;
- operating certificate of the regulator.
Principles of choosing a regulator for hydraulic fracturing
When designing a gas control point, it is important to choose the right pressure regulator.
It is selected taking into account:
- type of regulatory object;
- necessary gas consumption;
- maximum and minimum inlet and outlet pressure;
- regulation accuracy;
- acoustic requirements for the operation of the regulator.
An important criterion when choosing a regulator is to ensure the stability of its operation at different pressures. So, for example, for a dead end line, a statistical direct action regulator is used. With the consumption of gas in large volumes - indirect effect.
Ringed and branched lines are most often equipped with astatic regulators of indirect action.
Outlet pressure may vary depending on some factors. For example, insufficient adjustment of the operating mode of the device or deficiency of individual parts of the controller.
Conclusion
The article examined how hydraulic fracturing stands for abbreviations, types of points and requirements for their operation.
The points provide additional purification of natural gas after the gas distribution station and maintain the required outlet pressure. This allows consumers to seamlessly receive the substance and use it.
When designing a gas control device, it is important to make the calculations correctly and take into account the necessary parameters. What type of hydraulic fracturing will be installed depends on the needs of the area. Particular attention is paid to the basic parameters of a gas pressure regulator.