Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C13/00—Details of vessels or of the filling or discharging of vessels
  • F17C13/04—Arrangement or mounting of valves
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2205/00—Vessel construction, in particular mounting arrangements, attachments or identifications means
  • F17C2205/01—Mounting arrangements
  • F17C2205/0123—Mounting arrangements characterised by number of vessels
  • F17C2205/013—Two or more vessels
  • F17C2205/0134—Two or more vessels characterised by the presence of fluid connection between vessels
  • F17C2205/0146—Two or more vessels characterised by the presence of fluid connection between vessels with details of the manifold
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2205/00—Vessel construction, in particular mounting arrangements, attachments or identifications means
  • F17C2205/03—Fluid connections, filters, valves, closure means or other attachments
  • F17C2205/0302—Fittings, valves, filters, or components in connection with the gas storage device
  • F17C2205/0323—Valves
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2221/00—Handled fluid, in particular type of fluid
  • F17C2221/03—Mixtures
  • F17C2221/032—Hydrocarbons
  • F17C2221/033—Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
  • F17C2223/01—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the phase
  • F17C2223/0107—Single phase
  • F17C2223/0123—Single phase gaseous, e.g. CNG, GNC
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
  • F17C2227/01—Propulsion of the fluid
  • F17C2227/0192—Propulsion of the fluid by using a working fluid
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
  • F17C2227/04—Methods for emptying or filling
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
  • F17C2250/03—Control means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
  • F17C2250/03—Control means
  • F17C2250/032—Control means using computers

Definitions

• the invention relates to a natural gas filling equipment, particularly to a hydraulic compressed natural gas filling equipment and a gas filling control method for said filling equipment.
• Natural gas as a clean energy, has been increasingly used as fuel for motor vehicles, such as compressed natural gas (CNG) which is a common alternative fuel.
• CNG compressed natural gas
• a special fuel transporting system i.e. the natural gas filling system
• Said system can be constructed near a natural gas pipe network or alternatively at a place without the pipe network.
• the system is also known as natural gas filling substation when it is constructed at a place without the pipe network.
• a hydraulic CNG filling system of the prior art generally comprises a gas supply unit for storing CNG and a hydraulic power unit for driving the CNG out of the gas supply unit.
• the hydraulic power unit fills pressurized hydraulic medium into the gas supply unit to replace and push out the CNG stored therein.
• U.S. patent US5884675 discloses a hydraulic CNG filling system, wherein the pressurized hydraulic medium returns to a normal-pressure tank each time after the CNG replacement. The hydraulic medium in the normal-pressure tank is then pressurized into a high-pressure state afterwards.
• Another filling substation system for hydraulic natural gas vehicles is disclosed by Chinese patent ZL200520133308.X, wherein a high-pressure pump is used to pressurize the liquid medium from the normal-pressure gas tank directly and fill the pressurized medium into a CNG storage cylinder to push the CNG in the cylinder out. The hydraulic medium in the cylinder is then returned to the normal -pressure tank through the residual pressure in the CNG storage cylinder. The high-pressure pump is again used to pressurize the medium from the normal-pressure tank and fill it into a second CNG storage cylinder. The operation process is thus repeated.
• Both of the above patents have the same operation process that, in each wording cycle, the pressurized hydraulic medium is returned to the tank of normal-pressure, and then are pressurized again and fed to the gas supply unit for replacing the CNG.
• the pressure energy in the pressurized hydraulic medium is not utilized but converted into heat of the hydraulic medium, which is harmful to the system operation.
• One objective of the invention is to provide a hydraulic CNG filling equipment, which has less energy consumption during its operation.
• Another objective of the invention is to provide a gas filling control method for the hydraulic CNG filling equipment to reduce the energy consumption during the operation of said filling equipment.
• a hydraulic CNG filling equipment which comprises at least one CNG supply unit, a hydraulic power unit, and a control unit for controlling the operation of the CNG supply unit and the hydraulic power unit.
• Said at least one CNG supply unit comprises: two sets of cylinders for storing CNG, each set having the same number of cylinders, and each cylinder being arranged with a medium filling and returning port and a CNG outlet port; a first medium filling and returning pipe, connected with the medium filling and returning ports of the cylinders of one set; and a second medium filling and returning pipe, connected with the medium filling and returning ports of the cylinders of the other set.
• the hydraulic power unit comprises: a tank for storing hydraulic medium of normal pressure; a closed circuits pump for supplying pressurized hydraulic medium to the CNG supply unit, which has a first medium port, a second medium port and an inclined plate for controlling the working states of the first and the second medium ports; a reversible valve for changing the position of the inclined plate; a supply pipe, through which the first and the second medium ports of the closed circuits pump are connected to the tank; a first hydraulic pipe, connected between the first medium port and the first medium filling and returning pipe; and a second hydraulic pipe, connected between the second medium port and the second medium filling and returning pipe.
• the inclined plate can be switched among two active positions and a middle position disposed between the two active positions.
• Said two active positions include a first position and a second position.
• the first medium port serves as a pressured medium port while the second medium port serves as a medium inlet port.
• the second medium port serves as the pressured medium port while said first medium port serves as the medium inlet port.
• the closed circuits pump is in a passive state.
• the hydraulic pipe connected to the pressured medium port is in a medium filling state for providing the CNG supply unit with the pressurized hydraulic medium, while the hydraulic pipe connected to the medium inlet port is in a medium returning state for allowing the hydraulic medium return from the CNG supply unit to the hydraulic power unit.
• a gas filling control method for the above-mentioned hydraulic CNG filling equipment comprises the following steps: (1) setting the inclined plate of the closed circuits pump at one active position, so that one of the two hydraulic pipes is in medium filling state while the other is in medium returning state; (2) sucking the hydraulic medium in the hydraulic pipe in medium returning state into the closed circuits pump via its medium inlet port; (3) pressurizing the sucked hydraulic medium by the closed circuits pump to a predefined value equivalent to the pressure of the CNG stored in the cylinder, and draining the pressurized hydraulic medium into the hydraulic pipe in medium filling state via the pressured medium port; (4) performing a medium filling operation, as well as a CNG draining operation at the same time, to one cylinder of one set connected with the hydraulic pipe in medium filling state; (5) stopping the medium filling operation and the CNG draining operation to the cylinder of said one set, when the flow amount of the hydraulic medium through said hydraulic pipe in medium filling state
• the pressure energy in the returned hydraulic medium from the cylinders of the CNG supply unit can be folly used.
• the hydraulic medium returned at the beginning of the medium returning operation is in high-pressure state.
• the pressure of the returned hydraulic medium reduces gradually with the decrease of the hydraulic medium in the cylinder, the pressure of the hydraulic medium returned from the cylinder is always higher than that of the hydraulic medium in the tank of normal pressure. It is appreciated that the work done by the hydraulic system is a function of the pressure difference between the sucked and drained hydraulic medium by the hydraulic pump, wherein the greater the difference, the larger the work.
• the invention takes advantage of the high-pressure energy of the hydraulic medium returned from the cylinder, so as to raise the energy utility of the system, reduce significantly the power consumption during the operations of the CNG filling equipment, and avoid the unfavorable influence of the heat converted from the part of high-pressure energy on the CNG filling equipment.
• Fig.l is a schematic drawing showing the structure of a hydraulic CNG filling equipment according to the invention.
• Fig.2 is a schematic drawing showing the hydraulic structure of a hydraulic CNG filling equipment according to the invention.
• Fig.3 shows the gas filling control method according to the invention.
• a hydraulic CNG filling equipment 10 comprises, in general, at least one CNG supply unit 100, a hydraulic power unit 200 and a control unit 300.
• the CNG supply unit 100 comprises two sets of cylinders for storing CNG, wherein the first set 101 and the second set 102 have the same number of the cylinders.
• Each cylinder 130 is arranged with, at its one end, a medium filling and returning port 132, through which the hydraulic medium passes, and at it's the other end, a CNG outlet port 134, through which the CNG passes.
• the CNG supply unit 100 further comprises a first medium filling and returning pipe 110 and a second medium filling and returning pipe 120, each connecting with the medium filling and returning ports 132 of one set of the cylinders.
• a valve is arranged at each medium filling and returning port 132 for controlling its opening and closing.
• the hydraulic power unit 200 is configured to comprise: a tank 210, a closed circuits hydraulic pump 200 (hereinafter referred as closed circuits pump for short), a reversible valve 230, a supply pipe 240, and a first and a second hydraulic pipes 250, 260.
• Hydraulic medium e.g. fluid, such as oil
• the closed circuits pump 220 is used for providing the CNG supply unit 100 with pressurized hydraulic medium, which has a first medium port 221 and a second medium port 222 as well as an inclined plate for controlling the operation states of the two medium ports.
• the inclined plate can be switched among a first position, a second position, and a middle position between said first and second positions.
• the first medium port 221 acts as a pressured medium port while the second medium port 222 acts as a medium inlet port (i.e., medium suction poif).
• the second medium port 222 acts as the pressured medium port while the first gas medium port 221 acts as the medium inlet port.
• the closed circuits pump 220 is in a passive state (i.e., out of service).
• the first and the second positions are also known as active positions. When the inclined plate is at the active position, the hydraulic medium is sucked via the medium inlet port into the closed circuits pump 220 and drained out via the pressured medium port after being pressurized.
• the reversible valve 230 is utilized for switching the position of the inclined plate.
• the reversible valve 230 is of the type of explosion-proof electrolytic reversible valve.
• the reversible valve 230 is a reversible/position controlling valve, which can not only change the position of the inclined plate but also control the angle of the inclined plate deviated from the middle position when the inclined plate is at one active position. The larger the angle by which the inclined plate deviates from the middle position, the larger the flow discharge of the hydraulic medium from the pressured medium port of the closed circuits pump.
• Both of the first and the second medium port 221 and 222 of the closed circuits pump 220 are connected to the tank 210 via the supply pipe 240.
• the first medium port 221 is further connected to the first medium filling and returning pipe 110 of the CNG supply unit 100 through the first hydraulic pipe 250
• the second medium port 222 is further connected to the second medium filling and returning pipe 120 of the CNG supply unit 100 through the second hydraulic pipe 260.
• the medium port 221/222 serves as the pressured medium port
• the hydraulic pipe 250/260 connected therewith is in a state of medium filling, so that the pressurized hydraulic medium can be supplied to the CNG supply unit 100 through the corresponding hydraulic pipe 250/260.
• the hydraulic pipe 250/260 connected therewith is in a state of medium returning, so that the hydraulic medium can be returned to the hydraulic power unit 200 from the CNG supply unit 100.
• the arrangement of the closed circuits pump 220 allows the hydraulic medium to enter into said closed circuits pump directly from the hydraulic pipe that is in medium returning state, and be provided again to the other hydraulic pipe that is in medium filling state after having been pressurized to a predefined value.
• the returned hydraulic medium has a relatively high pressure, which has small pressure difference with or even is equivalent to the pressure of the hydraulic medium for filling. Therefore, the closed circuits pump does very small or even no work. In this way, the pressure energy of the returned hydraulic medium with high pressure is fully utilized, which reduces energy consumption and avoids the undesired influence of the heat that converted by the pressure energy when the pressurized medium returned into the tank of normal pressure.
• the control unit 300 is used to control the operations of the CNG supply unit 100 and the hydraulic power unit 200, which can be realized by a PLC controller or the like, or even by a computer.
• the first and the second hydraulic pipes 250, 260 are connected to the first and the second medium ports 221, 222, respectively, via respective control valves 251, 261.
• the control unit 300 is electrically connected to each of the control valves 251, 261 so as to control their opening and closing respectively.
• an overflow valve 255/256 is arranged between each control valve 251/261 and the corresponding medium port 221/222 of the closed circuits pump to prevent the hydraulic pipe from overflow.
• pressure transducers 252, 262 are arranged in the first and the second hydraulic pipes 250, 260 respectively to detect the pressure of the hydraulic medium in the respective hydraulic pipes. According to the detecting result, the control unit 300 can further control the opening and closing of the relevant control valve, so as to ensure a safe operation for the hydraulic pipe and the closed circuits pump.
• the control unit 300 switches the inclined plate of the closed circuits pump from its current active position to the middle position by means of the reversible valve 230, and closes the control valve 251/261 for said hydraulic pipe 250/260 in the medium filling state, until the pressure in said pipe decreases to a value less than a lower limit value of pressure (e.g. 20MPa).
• an upper limit value of pressure e.g. 22MPa
• the control unit 300 switches the inclined plate of the closed circuits pump from its current active position to the middle position by means of the reversible valve 230, and closes the control valve 251/261 for said hydraulic pipe 250/260 in the medium filling state, until the pressure in said pipe decreases to a value less than a lower limit value of pressure (e.g. 20MPa).
• the closed circuits pump 220 After a predefined time period since the inclined plate of the closed circuits pump 220 being switched to the middle position, if the pressure in the hydraulic pipe, which is in medium filling state originally, is still higher than the upper limit valve of pressure, the closed circuits pump 220 will be closed, which will not be restarted until the pressure decreases to a value less than the lower limit value of pressure. Afterwards, the inclined plate 230 returns to the previous active position by means of the reversible valve 230, while the control valve for the hydraulic pipe in medium filling state is reopened.
• the upper limit value and the lower limit value can be respectively determined according to the practice, while the upper limit value of pressure should not be less than the lower limit value of pressure.
• the angle, by which the inclined plate in the active position deviates from the middle position can be controlled according to the discharging rate of the CNG from the CNG filling equipment, so that the flow rate of the pressurized hydraulic medium provided from the hydraulic power unit 200 to the CNG supply unit
• a theoretical flow rate of the pressurized hydraulic medium that should be output from the closed circuits pump 220 can be determined according to the discharging rate of the CNG.
• the inclined plate can be set at the active position deviated from the middle position by a predefined angle, by means of the reversible/position valve 230, according to the theoretical flow rate.
• flowmeters 253, 263 can be arranged in the first and the second hydraulic pipes 250, 260 respectively for detecting the flow rate or amount of the hydraulic medium passing through the relevant hydraulic pipe and transmitting the detected results to the control unit 300.
• the flowmeters 253, 263 can be high-pressure flowmeters.
• returning electromagnetic valves 254, 264 can be arranged in the first and the second hydraulic pipe 250 and 260, respectively.
• the returning electromagnetic valve 254/264 is connected at its one end between the flowmeter 253/263 and the control valve 251/261 of the corresponding hydraulic pipe, and communicated at its the other end with the tank 210.
• the hydraulic medium in the cylinder can return directly to the tank 210 through the corresponding hydraulic pipe 250/260.
• the control unit 300 is electrically connected with each of the returning electromagnetic valves, to respectively control their opening and closing.
• a differential pressure switch 212 is arranged in the tank 210 to detect the pressure of hydraulic medium within said tank. When the pressure of hydraulic medium in the tank 210 is too large, the control unit 300 can close the corresponding returning electromagnetic valve 254/264 to ensure the safety of the system.
• radiators 257, 267 can be arranged respectively in the first and the second hydraulic pipes 250, 260 for heat dissipation.
• the control unit 300 is electrically connected with each of the radiators to respectively control their working states.
• temperature transducers 258, 268 can be arranged in the hydraulic pipes 250, 260 respectively, to detect the temperature of the hydraulic medium in the respective hydraulic pipes. When the detected temperature exceeds an upper limit value of temperature, the control unit 300 opens the radiator in the relevant hydraulic pipe to dissipate the heat, whereas when the detected temperature is lower than a lower limit value of temperature, the control unit 300 closes the relevant radiator to save energy.
• the upper limit value of temperature is not less than the lower limit value of temperature.
• the first and the second medium ports 221, 222 are connected with the supply pipe 240 through check valves 256, 266, respectively, so that the hydraulic medium can only flow in the direction from the supply pipe 240 to respective the first and the second medium ports 221, 222 and cannot flow reversely.
• a supply pump 270 is preferably arranged between the tank 210 and the supply pipe 240 to pre-pressurize and supply the hydraulic medium in the tank 210 to the supply pipe 240.
• a pressure transducer 241 can be arranged in the supply pipe 240 to detect the pressure of the hydraulic medium therein.
• the closed circuits pump 220 When the closed circuits pump 220 is starting-up, its inclined plate is set in the middle position. When the starting-up operation becomes smooth, the inclined plate can be switched to one of its active positions while the control valve 251/261 of the hydraulic pipe 250/260 can be opened. In a preferred embodiment, the control valves 252 and 261 are closed before the closed circuits pump being started-up.
• the hydraulic medium from the tank 210 is prepressurized and then fed to the supply pipe 240 through the supply pump 270.
• the closed circuits pump is not started-up until the pressure detected by the pressure transducer 241 reaches a predefined value.
• a double-cylinder filter 242 can be arranged in the supply pipe 240 to filter the hydraulic medium in the supply pipe 240.
• a transmitter 243 for communication with the control unit 300 can be further arranged on the double-cylinder filter 242. When the filter core of the double-cylinder filter 242 is jammed, the transmitter 243 will give a signal to the control unit 300 for alarming.
• a check valve 245 for medium supply protection can be connected in parallel between the supply pipe 240 and the tank 210 in such a way that the hydraulic medium can only flow from the tank 210 to the supply pipe 240 through said check valve 245.
• the check valve 245 takes the effect of supply protection to prevent the closed circuits pump 220 from being sucked up.
• a check valve 246 for pressure preserving can be further connected in parallel between the supply pipe 246 and the tank 210 in such a way that the hydraulic medium passing through said check valve 246 can only flow from the supply pipe 240 to the tank 210.
• the check valve 246 for pressure preserving is arranged with a spring to keep certain pressure in the supply pipe 240.
• the CNG When the CNG is in contact with the hydraulic medium, it may solve slightly into the hydraulic medium.
• the solved natural gas which tends to gasify, will be carried in the hydraulic medium in form of gas bubbles.
• the gas bubbles within the hydraulic medium will damage the closed circuits pump 220.
• bubble removing devices 259, 269 can be further arranged in the first and the second hydraulic pipes 250, 260, respectively.
• Step SlO the hydraulic medium in one hydraulic pipe that is in medium returning state, i.e. the hydraulic pipe 260, will be sucked into the closed circuits pump 220 through its sucking medium inlet port.
• the closed circuits pump 220 pressurizes the sucked hydraulic medium to a predefined pressure value and discharges the pressurized hydraulic medium out via its pressured medium port into the other hydraulic pipe that is in medium filling state, i.e. the hydraulic pipe 250, (Step S20).
• the predefined pressure value is generally equivalent to the pressure of the CNG stored in the cylinder.
• a medium filling operation is performed to one of the cylinders 130 in the set 101 corresponding to the hydraulic pipe in medium filling state, i.e. the hydraulic pipe 250, (Step S30).
• the medium filling operation includes: opening the medium filling and returning port 132 of the cylinder, and filling the pressurized hydraulic medium into said cylinder from its medium filling and returning port 132 through the medium filling pipe 110.
• the CNG draining operation includes: opening the CNG outlet port 134 of the cylinder, and pushing the CNG in said cylinder out via the CNG outlet port 134 by the filled hydraulic medium.
• Step S40 the hydraulic medium in the cylinder returns into the hydraulic pipe relevant to the cylinder (here is the hydraulic pipe 250, which is in medium returning state now). After the medium returning operation is finished, the medium filling and returning port of the cylinder is closed.
• a first predefined flow amount for example, 95% of the cylinder's volume
• the first hydraulic pipe 250 is in the medium returning state while the second hydraulic pipe 260 is in the medium filling state.
• the above-mentioned steps can be repeated so as to perform the medium filing operation and the CNG draining operation to another cylinder 130 in the other set 102 relevant to the hydraulic pipe 260 in medium filling state currently.
• the natural gas can be obtained in turn from the two sets of cylinders 101, 102 of the CNG supply unit 100.
• the medium returning operation will be described in details by taking the medium returning operation to the cylinder 130 in the first set 101 as an example.
• the first hydraulic pipe 250 is in medium returning state
• the second hydraulic pipe 260 is in medium filling state for performing the medium filling operation to one cylinder 130 in the first set 101.
• the control unit 300 closes the control valve 251 in the hydraulic pipe 250 and opens the returning electromagnetic valve 254 therein, allowing the remaining hydraulic medium in the hydraulic pipe 250 returning to the tank 210 via said the returning electromagnetic valve 254. Since the control valve 251 in the hydraulic pipe in medium returning state (i.e. 250) is closed, the hydraulic medium to the closed circuits pump 220 is supplied from the supply pipe 240 to continue the medium filling operation to said another cylinder.
• a second predefined flow amount which is less than the first predefined flow amount (e.g. 90% of the cylinder volume)
• the control unit 300 closes the control valve 251 in the hydraulic pipe 250 and opens the returning electromagnetic valve 254 therein, allowing the remaining hydraulic medium in the hydraulic pipe 250 returning to the tank 210 via said the returning electromagnetic valve 254. Since the control valve 251 in the hydraulic pipe in medium returning state (i.e. 250) is closed, the hydraulic medium to the closed circuits pump 220 is supplied from the supply pipe 240 to continue the medium filling operation to said another cylinder.
• the medium returning operation to the cylinder 130 in the second set 102 is similar to that to the first set, which will not be described here in details.
• the pressure of the hydraulic medium in the tank 210 is detected frequently.
• the relevant returning electromagnetic valve is needed to be closed.
• a secondary medium returning operation can be performed to each of the cylinders, which belong to the different set from the last cylinder.
• the secondary medium returning operation will now be described in details with the example in which the last cylinder belongs to the second set 102.
• the first hydraulic pipe 250 is in the returning state with the control valve 251 therein closed, while the second hydraulic pipe 260 is in the medium filling state.
• the secondary medium returning operation can be performed to the cylinders in the first set 101 in the same sequence as that in their CNG draining operations.
• the secondary medium returning operation comprises: opening the medium filling and returning port 132 of the relevant cylinder; making the hydraulic medium remained in said cylinder return to the tank 210 through the hydraulic pipe 250; and closing the medium filling and returning port 132 of the said cylinder after the hydraulic medium therein has returned completely.
• the CNG supply unit replacing operation comprises two steps. At the first step, the returning electromagnetic valve 254 of the hydraulic pipe 250 is closed after the second medium returning operations to all cylinders in the first set 101 are finished.
• the hydraulic pipe 250 (which is in medium returning state) and the relevant pneumatically controlled lines are disconnected from the current CNG supply unit, and connected to one medium filling and returning pipe and lines for the first set of cylinders (for example) of another CNG supply unit to finish the first step of the CNG supply unit replacing operation.
• the inclined plate is switched to the other active position to interchange the medium filling/returning states of the two hydraulic pipes 250 and 260.
• the medium filling operation can be performed to the first cylinder of the latter CNG supply unit, while the medium returning operation is performed to the last cylinder of the former CNG supply unit.
• the hydraulic medium in the last cylinder of the former CNG supply unit is returned to and pressurized by the closed circuits pump, and then provided to the first cylinder of the latter CNG supply unit.
• the returning electromagnetic valve (i.e. 264) of the hydraulic pipe in medium returning state (i.e. 260) can be opened to perform the secondary medium returning operations to the second set of cylinders in sequence.
• the secondary medium returning operations to the second set are similar to that to the first set, which will not be described here in details.
• the returning electromagnetic valve 264 of the hydraulic pipe 260 (which is now in medium returning state) is closed. And then the hydraulic pipe 260 and the relevant pneumatic control lines are disconnected from the former CNG supply unit and connected to the other medium filling and returning pipe of the latter CNG supply unit, so as to finish the second step of the CNG supply unit replacing operation.
• each of the closed circuits pump 220, the reversible valve 230, the control valves 251 and 261, the returning electromagnetic valves 254 and 264, the overflow valves 255 and 266, the check valves 256 and 266, the temperature transducers 258 and 268, the gas bubble removing devices 259 and 269, and the supply pump 270 can be respectively controlled by the control unit 300, so as to realize an automatic CNG filling process.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)

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Cited By (2)

Citations (7)

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• 2010
  • 2010-03-16 WO PCT/CN2010/000322 patent/WO2010105504A1/en active Application Filing
  • 2010-03-16 RU RU2011141836/06A patent/RU2493477C2/ru not_active IP Right Cessation
  • 2010-03-16 PE PE2011001668A patent/PE20121154A1/es not_active Application Discontinuation
• 2011
  • 2011-09-28 CO CO11127240A patent/CO6410253A2/es active IP Right Grant
  • 2011-10-12 ZA ZA2011/07471A patent/ZA201107471B/en unknown

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