LNG / CNG (liquefied natural gas / compressed natural gas) mutual standby metering system

Abstract

The utility model relates to a LNG / CNG (liquefied natural gas / compressed natural gas) mutual standby metering system which comprises an LNG metering loop and a CNG metering loop, the LNG metering loop and the CNG metering loop are connected in parallel, and the LNG metering loop comprises a ball valve I, an emptying valve I, a filter I, a flow meter I, a ball valve II and a check valve I which are connected in sequence; the CNG metering loop comprises a third ball valve, a second emptying valve, a second filter, a second flow meter, a fourth ball valve and a second check valve which are connected in sequence; an inlet of the LNG metering loop is connected with an inlet of the CNG metering loop through a pipeline, and a normally closed valve is arranged on the pipeline; and an outlet of the LNG metering loop is connected with an outlet of the CNG metering loop and then is connected with a gas supply port. According to the LNG and CNG metering system, inlet ends are connected with a normally closed ball valve arranged in the middle through a pipeline, an outlet is provided with a check valve, and the LNG and CNG metering systems are connected in parallel through a pipeline tee joint behind the check valve. The double gas sources can be supplied simultaneously under the condition of outlet pressure fluctuation; and mutual standby application of two sets of metering equipment can be realized under the condition that the cost is not increased.

Description

Technical Field

[0001] The utility model relates to a metering system with LNG / CNG backup for each other. Background Art

[0002] Due to the large fluctuations in international and domestic energy prices, when selecting gas sources for many gas enterprises, they often require the simultaneous availability of CNG (compressed natural gas) and LNG (liquefied natural gas) gas source supply conditions.

[0003] However, due to the different incoming gas pressures and pressure regulating equipment of the two gas sources, and LNG also has BOG gas at the same time. When the two gas sources are supplied simultaneously, the outlet pressures are often inconsistent. If the outlets are directly paralleled, when the outlet pressure of one gas source is higher than that of the other gas source, natural gas may flow reversely into the flowmeter of the other gas source at the outlet, resulting in incorrect metering data.

[0004] In addition, the flowmeter needs to be calibrated regularly, and the filter element of the filter needs to be replaced regularly. If there is only one set of filtering and metering system for both gas sources, the gas supply will need to be stopped when calibrating the flowmeter and replacing the filter element of the filter. Summary of the Invention

[0005] The problem to be solved by the utility model is to provide a metering system with LNG / CNG backup for each other, which can realize the simultaneous supply of the two gas sources without the phenomenon that natural gas flows reversely into the flowmeter of the other gas source at the outlet, resulting in incorrect metering data; and can realize that neither the LNG nor the CNG gas supply system needs to stop gas when calibrating the flowmeter and replacing the filter element of the filter without increasing the cost.

[0006] The technical solution provided by the utility model is: it includes an LNG metering circuit and a CNG metering circuit. The LNG metering circuit and the CNG metering circuit are connected in parallel. The LNG metering circuit includes a ball valve 1, a filter 1, a flowmeter 1, a ball valve 2, and a check valve 1 connected in sequence; the CNG metering circuit includes a ball valve 3, a filter 2, a flowmeter 2, a ball valve 4, and a check valve 2 connected in sequence; the inlet of the LNG metering circuit is connected to the inlet of the CNG metering circuit through a pipeline, and a normally closed valve is provided on the pipeline; the outlet of the LNG metering circuit is connected to the outlet of the CNG metering circuit and then connected to the gas supply port (user gas supply port).

[0007] The outlet of the above LNG metering circuit, the outlet of the CNG metering circuit, and the gas supply port are connected through a tee joint.

[0008] A vent valve 1 is provided between the ball valve 1 and the filter 1 of the LNG metering circuit; a vent valve 2 is provided between the ball valve 3 and the filter 2 of the CNG metering circuit.

[0009] In the utility model, the LNG and CNG metering systems are connected at the inlet end through a pipeline with a normally closed ball valve installed in the middle, and a check valve is installed at the outlet. After the check valve, they are connected in parallel through a pipeline tee.

[0010] During normal operation, the parallel ball valve (i.e., the normally closed valve) at the inlet end is in the normally closed state, and the check valve can prevent the reverse flow of the two gas sources when the outlet pressures are inconsistent.

[0011] When calibrating the flowmeter or replacing the filter element of any equipment, close the valves before the filter and after the flowmeter, and open the normally closed valve. Gas supply can be carried out through the other loop, so as to realize continuous gas supply during flowmeter calibration and filter element replacement. Description of the Drawings

[0012] Figure 1 It is a schematic structural diagram of the utility model. Detailed Embodiment

[0013] Refer to the attached Figure 1 As shown in the figure, the utility model includes an LNG metering loop 1 and a CNG metering loop 2. The LNG metering loop 1 includes an LNG metering system valve 1.1 (ball valve one), a vent valve one 1.2, a filter one 1.3 (filter one), a flowmeter one 1.4, a ball valve two 1.5, and a check valve one 1.6 connected in sequence; the inlet of the LNG metering loop is connected to the incoming LNG; the CNG metering loop 2 includes a CNG metering system valve 2.1 (ball valve three), a vent valve two 2.2, a filter two 2.3, a flowmeter two 2.4, a ball valve four 2.5, and a check valve two 2.6 connected in sequence; the inlet of the CNG metering loop 2 is connected to the incoming CNG; the inlet parallel system includes a pipeline and a valve 5. The LNG and CNG metering loops are connected at the inlet end through a pipeline with a normally closed ball valve 3 installed in the middle, and a check valve is installed at the outlet. After being connected in parallel through a pipeline tee behind the check valve, they are connected to the user end.

[0014] For the metering system where LNG and CNG are mutually backup, the normally closed valve 3 is in the normally closed state during normal operation, and the other valves are in the normally open state during normal operation. The check valve can prevent the reverse flow of the two gas sources when the outlet pressures are inconsistent.

[0015] When calibrating the flowmeter or replacing the filter element of any equipment, close the valves before the filter and after the flowmeter, and open the normally closed valve 3. Gas supply can be carried out through the other loop, so as to realize continuous gas supply during flowmeter calibration and filter element replacement.

[0016] The utility model utilizes the respective metering equipment of LNG and CNG, adds a normally closed valve and a check valve, and connects the inlet and outlet in parallel, so as to realize the function of mutual backup between LNG and CNG gas sources without increasing the cost.

Claims

1. An LNG / CNG mutual backup metering system, characterized by: It includes an LNG metering circuit and a CNG metering circuit, which are connected in parallel. The LNG metering circuit includes a ball valve 1, a filter 1, a flow meter 1, a ball valve 2, and a check valve 1 which are connected in sequence; the CNG metering circuit includes a ball valve 3, a filter 2, a flow meter 2, a ball valve 4, and a check valve 2 which are connected in sequence; the inlet of the LNG metering circuit is connected to the inlet of the CNG metering circuit through a pipeline, and a normally closed valve is provided on the pipeline; the outlet of the LNG metering circuit is connected to the outlet of the CNG metering circuit and then connected to the gas supply port.

2. The LNG / CNG mutual backup metering system according to claim 1 is characterized in that: The outlet of the LNG metering circuit, the outlet of the CNG metering circuit and the gas supply port are connected via a three-way joint.

3. The LNG / CNG mutual backup metering system according to claim 1 or 2, characterized in that: A vent valve 1 is provided between the ball valve 1 and the filter 1 of the LNG metering circuit; a vent valve 2 is provided between the ball valve 3 and the filter 2 of the CNG metering circuit.

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