Safety management of town gas regulator system

Gas regulator system is the core of the whole town gas transmission and distribution system, is the town gas supply safety, stability and continuity of the guarantee. In this paper, the role of the gas regulator on the basis of a brief description, focusing on how to protect the downstream network pressure within the safety range, as well as regulator maintenance and maintenance, good regulator system safety management.

1, gas regulator introduction and risk analysis

Gas regulator is a gas supply system to control the pressure of the equipment, with the role of reducing pressure and stabilizing pressure. According to the principle of operation can be divided into direct-acting and indirect-acting; according to the use can be divided into regional regulators, special regulators and user regulators; according to the import and export pressure can be divided into high-pressure, high medium-pressure, high and low-pressure regulators, medium-pressure, low-pressure and low-pressure regulators.

Regulator is to control the gas in different pressure pipe network transmission and distribution of security, if the regulator malfunction and failure, will cause the pressure of the gas pipeline directly and the pressure capacity of the lower pipeline connected to the high pressure gas not only the impact of the low-pressure pipeline of each interface, but also a direct impact with the low-pressure pipeline connected to the user gas equipment, it is easy to produce gas leaks in these places, which led to fires, explosions, and It is easy to produce gas leakage in these places, which will lead to fire, explosion and casualty accidents. Therefore, the pressure regulating system must ensure that the outlet (downstream) pressure cannot exceed the allowable value.

2、Commonly used overpressure protection methods

It is clearly stipulated in the national specification that when there is a possibility of exceeding the maximum allowable working pressure, safety protection equipment should be set up to prevent overpressure of pipelines. The following is an introduction to the most commonly used methods of overpressure protection:

(1) Ultra-high pressure cut-off device

Ultra-high pressure cut-off valve is usually installed in the upstream of the regulator, is a kind of quick-closing valve, the purpose is to protect the downstream pipeline network system, to prevent the system pressure from being too high due to emergencies or upstream equipment failures, in the regulating system outlet pressure up to a dangerous level before the ultra-high pressure cut-off device will automatically cut off the gas supply. The cut-off valve used on the gas regulating system can only be restored and reset manually after the cut-off.

(2) Ultra High Pressure Discharge Device

Ultra-high-pressure venting valves are designed to vent gases exceeding a preset venting pressure to the atmosphere, keeping the downstream pressure within a safe range. Some dispersion valves can be installed directly outdoors, while others require the installation of a lead pipe to connect to the outdoor dispersion. Norms require that the safety of the pressure regulator cabinet discharge pipe from the ground height should not be less than 4m; set in the building wall regulator safety discharge pipe should be higher than the eaves of the building 1.0m. so the installation of the most important thing is to release the device is the location of the mouth of the discharge pipe to meet the requirements of the safety regulations.

(3) series monitoring regulator

Two regulators in series, a regulator (air flow downstream) normal work, play a role in regulating pressure; another regulator (air flow upstream) does not work, play a monitoring role. Under normal circumstances to monitor the regulator valve is in a fully open state, the work regulator is responsible for regulating the outlet pressure, when the work regulator failure leads to increased outlet pressure, monitor the regulator began to work, that is, to regulate the outlet pressure, control the pressure does not continue to rise, and within the safety range.

   At present, whether it is a relatively large regional regulator station, or a small wall-mounted regulator box, are to take at least one method of ultra-high pressure protection, or a combination of two or three methods. In addition, remote pressure monitoring measures can also be taken to set the alarm pressure data, integrated into the SCADA system, can be more reliable to achieve the safety control of pressure.

3, regular inspection and pressure analysis of the pressure regulating system

After the regulator system is put into use, it is necessary to monitor its operating conditions, generally speaking, is divided into manual inspection and automatic monitoring of two ways. Work content is to measure the regulator system whether there is gas leakage hidden danger, in addition is to observe the regulator's export pressure value, it fluctuations should be in the scientific range, the highest value can not exceed the pipeline network and the user's gas equipment can withstand the pressure value.

For civil users of the regulator's export pressure, it should be 24 hours for the cycle of change, according to the living habits of residents, every day in the morning, in the evening, there are three gas peak, the export pressure is low; and early in the morning this time should be the gas peak period, the export pressure is also the highest, the highest pressure value can be approximated as the regulator's shutdown pressure. For industrial users, the outlet pressure of the regulator should follow the production time, when the production equipment starts, the gas consumption increases, the outlet pressure decreases, and vice versa. If we compare the pressure cycle change chart, and the actual situation does not match, the pressure is too high (low) situation, said it is likely that the pressure regulator equipment failure, need to send someone to carefully check the maintenance.

4, regulator maintenance and maintenance

 Different regulator manufacturers production, are on their own products of vulnerable parts of the specified use cycle, after reaching the cycle should be replaced. Generally speaking vulnerable parts mainly refers to: a variety of rubber membrane, rubber seals, valve gaskets, etc., and even some manufacturers designed regulator, is the metal shell can be all the components, a one-time replacement. For the regulator to speak, regular maintenance and maintenance is a must. Regulator manufacturers are their own products have follow-up services, you can order directly from the manufacturer with the matching "accessories package", which contains all the regulator regularly need to replace the new parts, their size is the same as the old parts in the regulator, very convenient.

5, without stopping the gas state of the regulator maintenance and maintenance

 To a regulator for maintenance or maintenance, you need to close the regulator before and after the control valves, the pipeline gas emissions, and then dismantle the shell for, this process regulator is not working. If it is a system with multiple regulators in parallel or on a circular pipeline network with multiple regulator stations (cabinets) supplying gas together, it is possible to temporarily close the front and rear valves of a regulator and closely monitor the downstream pressure to complete the maintenance and repair work. And many of the regulator system is a single regulator for gas supply, if you want to close its front and rear valves, the entire downstream users have to stop gas. In accordance with the prevailing regulations, the user gas shutdown is required to post a notice in advance, limited time frame, and in the resumption of gas supply to determine the user's gas equipment is completely closed and no leakage of the pipeline network can be carried out, the completion of these tasks is very difficult, but also very likely to cause safety accidents.

 We take the building-type regulator as an example to introduce a simple and quick solution, this type of regulator system is mostly used in the form of "1 + 0" structure, there is no bypass pipe, only by a single regulator work. If you want to dismantle the regulator for maintenance and repair, the traditional way is to stop the gas first, dismantle the regulator, and then restore the gas. We can make this type of building regulator slightly modified, in front of the regulator's import and export valves to install a set of bypass interface (with valve). When we want to carry out maintenance and maintenance of the regulator, you can prepare a suitable type of bypass regulator, its import and export and the building regulator box is connected to the reserved interface, through the boost switching method to make the bypass regulator instead of building regulator work, then you can rest assured that the building regulator off the import and export valves, dismantle the regulator and begin to work to achieve a non-stop gas state of the regulator Repair or maintenance of the regulator without stopping the gas.

    Gas regulator system operation is good or bad, not only the design of a scientific process system and procurement of high-quality products and equipment, but also need to check the use of the regulator system working conditions in line with the actual demand, do a good job of regular pressure testing and leakage measurements, and in accordance with the deadline for the completion of the corresponding maintenance and maintenance. A healthy pressure regulating system is the cornerstone of a safe, continuous and stable town gas transmission and distribution system.