UNDERGROUND PRESSURE REGULATING MODULE

Abstract: An underground pressure regulating module including a slam-shut valve and a pressure regulating valve. The regulating valve includes two diaphragm arrangements (21, 40) to allow a variable pressure output to be obtained. The diaphragm (40) is controlled by a fluid line inlet (42). The fluid to the inlet is provided by a control located above ground which is also a logging device to determine utilisation parameters.

Description: UNDERGROUND PRESSURE REGULATING MODULE The invention relates to a fluid pressure regulator which is designed to be located underground, e.g. in a fuel gas pipeline system. In known underground pressure regulators (see Figure 1 ) a complete gas pressure regulating system is housed in a single body shell 10 with all the major control devices being incorporated into a single cartridge 12 which can be easily replaced. There is access to the module via manhole cover 1 1. In practice the buried system will typically include an inlet valve, an outlet valve and a flap type non- return valve, but these are omitted for the sake of clarity. An inlet has a flange 13 (e.g. 150 mm) for coupling to an inlet pipe and the outlet has a flange 15 (e.g. 200 mm) for coupling to an outlet pipe. A filter 16 is of cylindrical form with a small mesh (e.g. 200 micron) which allows filtered gas to pass internally therethrough and this flows through the open slam-shut valve 17 to the control valve 18. The control valve 18 regulates the outlet pressure of the gas and includes a rod 19, spring 20 and a diaphragm stack 21 comprising four diaphragms coupled together in parallel to provide the sensitive regulation mechanism. The cartridge also contains a relief valve 22 which is impulsed internally as is the slam-shut actuator 23. The preassembled cartridges are easily replaced, saving downtime. The regulator control module can typically cope with inlet pressures of up to 2 Bar and outlet pressure set to between 22 and 47 mBar with a flow capacity up to about 4000 m 3 /Hr. A vent stack 30 provides a reference atmospheric pressure for the cartridge 12 and houses the relief valve outlet pipe and other lines (shown schematically as pipe 31 ). The instrument box 33 contains a chart recorder for inlet and outlet pressures, a filter differential pressure gauge and various test points (e.g. to indicate whether the slam-shut is open or closed). In order to increase the operational efficiency of the system it is possible to include a clock operated actuator 28 so that during the night when demand is low the set pressure of the regulator can be switched. A clock in the instrument box 33 can signal this switchover. This pressure is switched by changing the spring pressure of spring 20. The present invention is concerned with providing a more sophisticated regulation system employing an underground module which can be incorporated without major excavation requirements, for example. According to the invention an underground fluid pressure regulator including a module for insertion into an underground chamber in use, the module including a safety closure device and a pressure regulating valve for providing a variable flow pressure, said valve including a first diaphragm arrangement including at least one diaphragm and a second diaphragm arrangement operable on the first diaphragm arrangement to vary the flow pressure output from the regulator. Further according to the invention there is provided a method of regulating pressure in a fluid pressure regulating system including an underground regulator module provided in an underground chamber the method comprising monitoring fluid utilisation over a given period in a logging device, providing a plurality of setting parameters during a preset period to replicate utilisation requirements and controlling the underground regulator module by means of first and second diaphragm arrangements therein, the second diaphragm being operable on the first diaphragm to vary flow pressure output from the regulator module The invention will now be described by way of example with reference to the accompanying drawings in which Figure 1 shows an underground regulator module arrangement, Figure 2 shows graphs of fluid utilisation requirements, Figure 3 shows a modified regulator arrangement within the module capable of variable fluid pressures to meet utilisation requirements, and Figure 4 shows the logging and other controls above ground to operate the system Figure 2 shows pressure graphs for the gas supply Hence the requirement is to supply customers with a stream of gas at a pressure of at least 20 mBar (see graph (a)) In practice it is possible to reduce the available pressure at the regulator output from 40 mBar to say 30 mBar during the night using the clock arrangement described earlier (see graph (b)) The present invention allows a modified underground module to have a continuously variable pressure setting dependent on previously monitored utilisation by consumers at that particular station in the gas supply network A utilisation profile (see graph (c)) allows the output availability of (a) to be maintained to meet demand requirements whilst allowing reduced pressure to be selected hence lowering volume requirements and the likelihood of leakage, etc. Although the variations of graph (c) are shown as being relatively static over any given short period (e.g. one hour), in practice a large number of variations can be accommodated if desired. In order to perform the function desired the module cartridge 12 is modified as shown in Figure 3. The diaphragm stack 21 now only comprises three diaphragms 21 a, b, c connected in parallel through passage 26. A second independent diaphragm 40 is provided with a passage 41 blanked off from passage 26. An inlet 42 allows fluid to be applied to the diaphragm 40 at a pressure independent of that applied to the other diaphragm stack. The application of the fluid pressure to diaphragm 40 will cause a change in the operating pressure of the regulator via diaphragm stack 21 . Hence this provides the mechanism for providing infinitely variable changes to the selected pressure for the regulator. The line to the inlet from the instrument box 33 can conveniently utilise that previously used for the clock control which is no longer required, hence minimising the changes required and this line can merely be diverted on the module cartridge. A restriction valve may be included in this line in the module if pressure conditions require it. In practice, to provide the degree of intelligence for such system operation an additional box, control box 50, is mounted on vent stack 30 below the existing instrument box 33. Lines for operational control are fed through tube 51 from the instrument box 33. The heart of the control arrangement is the controller/logger 53 which can include a microprocessor, memory, clock and display. A modem 54 allows logged information to be received remotely and control information passed to the logger/control 53 from a remote site. Dependent on operational and safety requirements a low pressure slam-open valve 56 and supply pressure regulator 57 can be included. The controller/logger monitors pressure/usage and so receives the gas supply through a small tube at inlet 60. It also uses the gas to operate components and receives this via the supply pressure regulator 57. The outlet 61 passes to the instrument box 33. A control output 63 provides pressure control to the underground regulator via flexible pipe 64 which is the control line also received by the slam-open valve 4. In the event of a fault, when the slam-open valve senses low output it will dump control pressure to the outlet and allow the outlet to rise to the underground regulator preset value. Line 65 provides a route to exhaust the gas during setting changes. The logger/controller 53 monitors and records information on usage/pressure to allow a profile to be known for that station and this is typically downloaded once every 24 hours following a prompt signal via the telephone link to the modem 54. This information is utilised by a remote computer (not shown) to calculate expected usage requirement and selects a stream of different pressure settings for use throughout the next 24 hours (with a margin for handling a somewhat increased loading) and downloads this via the telephone line to the controller which uses its internal clock to increment and decrement the pressure as previously instructed throughout the day to provide variable pressure to the diaphragm 40 in the cartridge 12 so as to produce the results shown in the graph in Figure 2(c) for example. The logger can also produce alarm and other signals for sending to the remote site via the modem. Although a telephone line can be used, radio or other transmission techniques could be utilised. The cartridge is easily interchangeable with that of Figure 1 and needs no excavation work because it slides into the existing chamber and is closed using the same bulkhead.

Claims: CLAIMS 1 An underground fluid pressure regulator including a module for insertion into an underground chamber in use, the module including a safety closure device and a pressure regulating valve for providing a variable flow pressure, said valve including a first diaphragm arrangement including at least one diaphragm and a second diaphragm arrangement operable on the first diaphragm arrangement to vary the flow pressure output from the regulator 2 A regulator as claimed in claim 1 , wherein the module includes a control flowhne input for receiving a control fluid from an above ground controller 3 A regulator as claimed in claim 2, wherein the controller includes means for detecting utilisation parameters and means for storing said parameters for future pressure control A regulator as claimed in claim 2 or 3, wherein the controller is mounted on a vent stack A regulator as claimed in claim 2, 3 or 4 including a safety pressure control device configured to remove control fluid pressure in the event of fault occurring A regulator as claimed in any one of claims 1 to 5, wherein means are provided to send or receive utilisation parameter information to a remote location to allow pressure variables to be set for the module. 7. A method of regulating pressure in a fluid pressure regulating system including an underground regulator module provided in an underground chamber, the method comprising monitoring fluid utilisation over a given period in a logging device, providing a plurality of setting parameters during a preset period to replicate utilisation requirements and controlling the underground regulator module by means of first and second diaphragm arrangements therein, the second diaphragm being operable on the first diaphragm to vary flow pressure output from the regulator module. 8. A method as claimed in claim 6, including remotely accessing the logged information, computing the setting parameters therefrom and transmitting the parameter information back to the regulating system to allow control thereof. 9. An underground fluid pressure regulator substantially as described with reference to Figures 2 to 4 of the accompanying drawings. 10. A method of regulating pressure in a fluid pressure regulating system substantially as described herein.

Inventors: BLACKMAN RICHARD, KIRKMAN LEE, PERRYMAN CLAYTON, BLACKMAN, RICHARD, KIRKMAN, LEE, PERRYMAN, CLAYTON
Applicants: BRITISH GAS PLC, BG PLC
Application year: 1998
Main classification: G05D16
IPC codes: F17D1, F17D3, G05D16