With the increase of urban infrastructure construction in China and the improvement of people's living standards, the pipeline gas industry has developed rapidly. In the city gas transmission and distribution system, the gas pressure regulating device is the main component and is the hub connecting the two-stage pipe network. In the traditional two-stage or multi-stage pipe network transmission and distribution form, most of them adopt regional pressure regulating stations, and use low-pressure pipe network (pressure P≤5 kPa) to transport gas to thousands of households. This approach has its advantages, but there are also many drawbacks. Therefore, the selection of a new type of pressure regulating device and the use of gas medium pressure gas distribution is a common concern in the industry.
Germany, Italy, the United States, and Japan have begun to use medium-pressure gas distribution pressure systems very early, using pressure-regulating cabinets. Since the 1990s, more and more people in China's gas industry have recognized and gradually adopted this type of pressure regulating device [1–4], which have received good economic and social benefits. However, due to the influence of natural conditions in the northern region, there are still many problems in the application of surge tanks in the north that are worth exploring and solving.
1 Application of pressure regulating device
1.1 Most of the regional pressure regulating station regional pressure regulating stations use Renault-type voltage regulators [5]. There are many components of Renault regulator, and the structure is more complicated. The advantage is that the gas supply is large, the automatic pressure regulation performance is good, and the gas supply pressure is stable. However, its drawbacks are: 1 medium and low pressure pipeline double pipe in and out of the pressure regulating station, making the project cost higher. Double or multiple pipes are laid in the same trench. There are many sections where the pipe position is tight and cannot pass. The most critical problem of the 2 regional pressure regulating station is that it is difficult to locate the site, and its distance from the surrounding buildings is strict. The general pressure regulating station has a construction area of ​​not less than 15m2 and covers an area of ​​more than 25m2. It not only covers a large area, but also requires land acquisition. It also needs to apply for the red line position, resulting in large project investment and complicated approval procedures. 3 The filter has serious fouling, and the pressure guiding tube is easy to block, which often causes overpressure to supply air. 4 Because the Renault-type pressure regulating station has no over-pressure safety cut-off, there is only one safety water seal release device. Once the pressure regulator or pilot film breaks, the valve port is not closed, the spring is faulty, and the medium pressure gas is suddenly supplied. , high and low auxiliary pressure regulator failure, needle valve port plugging and other reasons, will cause pressure regulation out of control, so that the outlet pressure is too high, and the safe water seal's ability to disperse is limited, coupled with the release of combustible gas It not only pollutes the environment but also has certain hidden dangers. If you don't pay attention, the gas meter and the gas stove will explode, but the accident will cause personal injury or death.
Due to the large number of pipelines passing through our company, the residents are not very concentrated, and some households, boiler houses and direct combustion engines apply for gas at the same time in one area. Therefore, according to the characteristics of the regional pressure regulating station, our company only works in Xinglong Mountain. There are 3 regional pressure regulating stations in other places.
1.2 Special pressure regulating room for special pressure regulating room According to the provisions of Article 5.6.5 of “Code for Design of Urban Gas Design†GB50028—93, the location is provided by the user and is set in a single single-story adjacent building of the gas-using building. [6], its equipment structure characteristics and requirements: 1 add a corrugated compensator on each voltage regulating line to adjust the leakage of the flange interface caused by temperature changes, and also facilitate the disassembly of the equipment; 2 in each A set of shut-off valves with corrugated compensators is installed at the inlet pipe of the pressure regulating outdoor; 3 a safety release valve is added in front of the population valve of each surge chamber, and the discharge pipe is 2.5 m above the roof; 4 each surge chamber The manufacturer shall set up a special person to manage and install the flammable gas alarm device with centralized alarm, and ensure the inspection once a day, and make a record; 5 the user-prepared filter filter, nitrile film and other wearing parts, timely replacement; There are hot water heating devices in the pressure regulating room.
In the past few years, the pressure regulating equipment of the user-specific pressure regulating chamber has experienced a number of air leakage events at the flange interface, especially the flange interface of the shut-off valve of the outdoor pipeline leaking air. Later, a corrugated compensator was added to solve the problem due to temperature. The flange leak problem. The system has been running so far, the voltage regulation effect is good, the operation is stable, safe and reliable, and the management is in place. However, the dedicated surge chamber is more suitable for industrial, enterprise and utility users, and the construction unit can provide the location of a dedicated surge chamber. It is not suitable for residents.
1.3 Pressure Regulating Cabinet In 2000, our company began to shift the focus of market development to residents' gas supply. Since natural gas is generally mined and purified, the pressure is still high after entering the urban area through long-distance pipelines. In order to make full use of the pressure of natural gas itself, it is advisable to use medium pressure during gas distribution, and the natural gas is directly delivered to the user by the medium pressure pipeline, forming a supply mode of natural gas medium pressure gas distribution. The pressure regulating cabinet is in line with this gas supply characteristic. So in the beginning of 2000, 10 pressure regulating cabinets were purchased and piloted in Chaoyang Apartment and other districts, and the ideal effect was achieved.
Compared with the other two pressure regulating devices, the pressure regulating cabinet has the following advantages: 1 It is not necessary to apply to the planning department for delineating the red line position, which solves the problem that the pressure regulating station is difficult to obtain land and the position is difficult to determine; 2 the low-pressure main pipe of all blocks is cancelled. , slowing down the contradiction of the pipe position on the road, saving investment in the pipe network; using medium-pressure transportation, the same conveying capacity, the pipe diameter is reduced, and saving a considerable cost; 3 no need to build a house, saving civil construction costs 4 Because the pressure regulating device is close to the user, the pressure fluctuation of the user is extremely small, which ensures the stability of the user's gas; 5 the pressure regulating cabinet has good ventilation performance, the equipment is compactly installed, and the overall maintenance amount is less than the pressure regulating station.
2 The composition and characteristics of the pressure regulating cabinet Through the urban medium pressure pipe network, the medium pressure branch pipe is separated, and the medium pressure branch pipe is responsible for the dual tasks of transportation and distribution. Each user is connected by the medium pressure branch pipe, and the pressure regulating cabinet is installed in the courtyard ( Medium-low pressure) enters the house through the low-pressure pipe.
(1) The equipment combination process constituting the pressure regulating cabinet is the same as the special pressure regulating chamber, and is also composed of a pressure regulator, a safety release valve, a filter, a valve, a measuring instrument, etc.; according to the process requirements, it is tightly packed in a metal box, and the whole Can be handled and installed directly.
(2) Features 1 The main components such as the main regulator are imported equipment, such as the United States, Italy, Germany and other products, the quality performance can be guaranteed; 2 the pressure regulator and other pipeline interfaces are threaded connections, easy to disassemble and repair; The pressure regulating cabinet has overpressure cutting and safety release function; 4 pressure regulating cabinet is single layer without heat preservation, and has one-time ventilation device; 5 pressure regulating cabinet inlet and outlet interface is threaded connection, sealed by O-ring; 6 is adopted Direct acting regulator, sensitive and accurate.
3 Problems and Improvements (1) Problems During the two years of use, the pressure regulating cabinets have successively appeared a series of problems. 1 In winter, due to the low temperature, the flange interface in the pressure regulating box has different degrees of leakage; 2 in summer, when the pressure of the pipe network in the front of the pressure regulating cabinet rises to 0.4MPa, the joint of the inlet and outlet pipes of the pressure regulating cabinet leaks. 3 In the winter of 2001, the signal tube, the main regulator valve port and the shut-off valve port were blocked by ice, and the pressure regulation failed, resulting in 3 low-pressure pipe network gas-stop events; 4 Chaoyang Apartment, FAW Special Vehicle Factory and other residential buildings The main pressure regulator valve seat of the pressure regulating cabinet, the lower part of the valve port of the shut-off valve is frozen, the spring is limited by the ice, the function is lost, the safety release valve is out of freezing, the discharge cannot be started, and the inlet and outlet pipelines are directly connected, so that the pressure of the low-pressure pipe network exceeds 0.2MPa or more, resulting in 3 civil table bursts, 2 fires on the stove, 3 people were slightly injured; 5 in the winter, the pressure on the inlet and outlet of the pressure regulating cabinet, often after the sun rises 1h, causing the user to suffocate , causing inconvenience to the user's normal life.
For the above problems, we organized the personnel to repair the repairs in a timely manner, and actively organized engineering and technical personnel to conduct disintegration analysis. We believe that the winter weather in the north is relatively cold, with a minimum temperature of -38 °C and an average temperature of around -20 °C. The temperature of the outlet gas will also drop. Due to changes in ambient temperature and natural gas pressure, the water vapor contained in the natural gas is easy to hang frost, freeze, and form frost plugs and ice plugs, which may cause the regulator to malfunction.
(2) Improvement method 1 The interface between the pressure regulating cabinet and the pipe network is sealed by the threaded sealing ring, and the flange interface is replaced by a high-pressure oil-resistant asbestos pad seal; 2 the PE of the pressure regulating cabinet is perpendicular to the lower elbow of the pressure regulating cabinet. Condensate water tank; 3 pairs of pressure regulating cabinet inlet and outlet from -1.6m to the inner tube section of the pressure regulating cabinet to do polyurethane foam insulation; 4 add a corrugated compensator between the filter and the pressure regulator in the pressure regulating cabinet; 5 pairs of pressure regulators, filters, valves, relief valves and pipelines with double-circuit explosion-proof heating cable with heat treatment, and add temperature control switch, while using polyethylene insulation pipe for external insulation; 6 pressure regulating cabinet body by The single-layer structure becomes a (double-layer) holding cabinet with insulation interlayer; 7 is only a simple disposable ventilation hole, which becomes a ventilated device that can be switched by the ridge-type porous hole, and is closed in winter to ensure the temperature inside the cabinet. Open when open; fully open in summer to ensure ventilation.
According to the above method, the regulator manufacturers have made corresponding improvements. Our company purchased 38 sets of pressure regulating cabinets from Tianjin Xinke. After two years of operation comparison, the improved pressure regulating cabinets performed better and did not stop together. Gas, overpressure, low pressure phenomenon, residents, catering gas reflects good.
4 Conclusion
The pressure regulating cabinet with heat tracing, heat preservation, adding compensator and reasonable ventilation has a small footprint, no need for additional land use, low engineering cost, flexible maneuverability, stable gas supply pressure, excellent safety performance and low pressure drop at the end user. It is suitable for promotion and use in the northern region and is easily accepted by developers and residents. With the development of the city and the increase of pipeline gas users, the pressure regulating cabinet will gradually show its advantages and expand its share in the northern market.
(Source: Hebei Zhenxing Gas Regulator Co., Ltd. gas pressure regulator http://)
Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
Variable Peristaltic Pumpis a peristaltic dosing pump that can distribute many types of liquids, such as water-based liquid/shampoo/sauce/chemical-based liquid, etc.
The flow rate of the industrial variable speed Peristaltic Pump can be adjusted by the digital knob to adjust the motor speed to achieve the effect of adjusting the flow rate
The liquid only gets in touch with the Peristaltic Pump Tubing, will not cause cross-contamination. it's suitable for Liquid transfer occasions with high cleanliness requirements, Eg. : food/beverage/cosmetic/medical/biopharmaceutical...
For the Peristaltic Pump Tubing, We have different material choices for your various liquids. The standard tube is silicon tubing which conforms to the FDA certificate. Except that we also offer the Saint-Gobain imported tubing, Eg.: Norprene®A-60-F/Norprene®chemical /Pharmed® BPT... Which suitable for various chemical-based liquid.
Suitable for various industrial applications.
Variable Peristaltic Pump,Intelligent Programmable Pump,Dosing Peristaltic Pump,Timed Quantitative Pumps
Baoding Chuangrui Precision Pump Co., Ltd. , https://www.crperistalticpump.com