System for Introducing Gas into a Gas Grid Pipeline

Abstract

A system for introducing gas from an unconventional source into a gas grid pipeline includes a passive blender (10) that introduces gas from an unconventional source (1) into a gas grid (2), the passive blender (10) having gas inputs (3, 11) from the unconventional source (1) and the gas grid (2) and a blended gas output (12), and wherein an internal flow path within the passive blender (10) is shaped and sized to provide entraining and mixing of the gases. The passive blender (10) acts to entrain gas from a gas grid (2) through input (11) by utilising the flow of gas from an unconventional source (1) through input 3, proportionally blending inputs 3 and 11 before outputting the blended gas back to the main gas grid (2). The system comprises the passive blender (10) of the present invention, a first gas input pipe (11) from a grid gas pipeline (2) into the passive blender (10) a second gas input pipe (3) from the unconventional source (1) into the passive blender (1), and an output pipe (12) from the passive blender (10) into the grid gas pipeline (2). The blender (10) and system of the present invention are advantageous in that they can greatly reduce the necessary conditioning of unconventional gas before it is introduced into a gas grid supply (2) without additional means of flow motivation or controls.

Claims

1. A system for introducing gas from an unconventional source into a grid gas pipeline comprising: an inspirating passive blender having a grid gas input, an unconventional source input, and a blended gas output, wherein an internal flow path within the inspirating passive blender is shaped and sized to provide entraining using an inspiration effect; a first gas input pipe from the grid gas pipeline into the inspirating passive blender; a second gas input pipe from the unconventional source into the inspirating passive blender; and an output pipe from the inspirating passive blender into the grid gas pipeline.

2. The system according to claim 1, further comprising a sample point in the output pipe between the inspirating passive blender and the grid gas pipeline, wherein a sampler is provided at the sample point to measure one or more physical characteristics of gas passing through the sample point.

3. The system according to claim 2, further comprising: gas conditioner located between the unconventional source and the sample point such that gas from the unconventional source is treated by the gas conditioner before passing through the sample point.

4. The system according to claim 3, wherein the gas conditioner includes an apparatus for adding propane or liquid petroleum gas to the first input pipe.

5. The system according to claim 3, wherein the gas conditioner includes an apparatus for adding propane or liquid petroleum gas into the second input pipe.

6. The system according to claim 3, wherein the gas conditioner includes an apparatus for adding propane or liquid petroleum gas to the output pipe before the sample point.

7. The system according to claim 3, wherein the gas conditioner includes a gas cleaner.

8. The system according to claim 1, further comprising a compressor or regulator located in the second gas input pipe to increase or decrease the pressure of gas from the unconventional source.

9. A method of conditioning gas from an unconventional source to allow the gas to be entered into a main grid gas pipeline, the method comprising: providing a gas input from the main grid gas pipeline into a first gas input of an inspirating passive blender; providing a gas input from the unconventional source into a second gas input of the inspirating passive blender; directing an output from the inspirating passive blender back into the main grid gas pipeline; and shaping and sizing an internal flow path within the inspirating passive blender provide entraining using an inspiration effect.

10. The method according to claim 9, further comprising: sampling the output from the inspirating passive blender at a gas sample point and measuring one or more physical characteristics of gas passing through the gas sample point; and when the one or more of the physical characteristics is measured to be outside of an acceptable range for entering the main grid gas pipeline, injecting the gas input from the unconditional source with LPG or propane to alter the physical characteristics of said gas input.

11. The method according to claim 9 further comprising: injecting liquid petroleum gas or propane into the gas input from the unconventional source to raise the calorific value of the unconventional gas prior to input into the inspirating passive blender.

12. The A method according to claim 11, further comprising determining the amount of liquid petroleum gas or propane injected into the gas input based on an analysis of the calorific value of the gas of the output of the inspirating passive blender.

13. The method according to claim 12, further comprising obtaining the analysis of the calorific value of the gas of the output from a sampling point positioned at the output.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG. 1 is a schematic diagram of a system for introducing gas from an unconventional source into a grid gas pipeline according to the prior art;

[0046] FIG. 2 is a schematic diagram of a system for introducing gas from an unconventional source into a grid gas pipeline according to an embodiment of the present invention;

[0047] FIG. 3 is a cross-section and schematic of a first embodiment of a passive blender that may form part of a system according to the present invention;

[0048] FIG. 4 is a cross-section and schematic of an alternative passive blender that may form part of a system according to the present invention;

[0049] FIG. 5 is a cross-section and schematic of a further alternative passive blender that may form part of a system according to the present invention; and

[0050] FIG. 6 is a cross-section and schematic of another alternative passive blender that may form part of a system according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0051] Part of a system for introducing gas from an unconventional source into a grid gas pipeline according to the present invention is shown in FIG. 2. The system comprises a passive blender 10, a first gas input pipe 11 from a grid gas pipeline 2 into the passive blender 10, a second gas input pipe 3 from an unconventional source 1 into the passive blender 10, and an output pipe 12 from the passive blender 10 to the grid gas pipeline 2. The system further comprises a compressor or regulator 25, a liquid petroleum gas (LPG) injection apparatus 5, a gas cleaner 4, and an analyser 13. The pipe 3 transports gas from the unconventional source 1 into the grid gas pipeline 2. The analyser 13 communicates with the injection apparatus by means of a feedback signal 24. The system of FIG. 2 operates in the following manner.

[0052] Gas from the grid gas pipeline 2 is fed into the passive blender 10 via the first gas input pipe 11. This input is at the pressure ‘p’ of the grid gas pipeline 2. Gas from the unconventional source 1 is fed into the passive blender 10 via the second gas input pipe 3. This input is at a pressure ‘P’. Pressure ‘P is greater than pressure ‘p’. The precise composition of the gas output with regards to proportion of gas from the grid gas pipeline and gas from the unconventional source can be controlled by design of the passive blender 10 and/or the size of the first and second gas input pipes 11, 3 and/or controlling the flow of the gas in the second gas input pipe 3.

[0053] Gas from the unconventional source 1 is conditioned and compressed and/or regulated in the manner according to the prior art. This may include using LPG from the LPG injection apparatus 5. The gas is then fed into the passive blender 10 and mixed with gas from the grid gas pipeline 2. The gas then outputs the passive blender 10 through the output pipe 12, passes through a sample point connected to the analyser 13, and is passed into the grid gas pipeline 2 downstream of where the first input pipe 11 takes gas from the grid gas pipeline 2. Should the grid pipeline gas reverse direction of flow, the passive blender system continues to operate safely but less efficiently. The analyser 13 analyses gas passing through the output pipe 12 and when it is determined that the gas in the output pipe 12 is not suitable for entry into the grid gas pipeline 2 this is communicated to the injection apparatus 5 and LPG injection will begin or be increased to until the gas in the output pipe 12 is of an acceptable quality for injection into the grid gas pipeline 2.

[0054] As the gas from the unconventional source 1 is mixed with gas from the grid gas pipeline 2 in the passive blender 10 before being introduced into the grid gas pipeline the gas can require less conditioning. In particular, the amount of LPG that is required to be mixed with the gas may be reduced or eliminated. This is because previously it was necessary for the conditioned gas from the unconventional source 1 to be suitable for entering the grid gas pipeline 2, whereas in the system of the present invention all that is required is that conditioned gas from the unconventional source 1 is suitable for entering the grid gas pipeline 2 after it has been mixed with a significant proportion of gas from the grid gas pipeline.

[0055] The analyser 13 is provided after the passive blender 10. This provides control of the LPG injection, by means of a signal (24), based on characteristics and properties measured and/or calculated from samples of the blended gas analysed in the analyser 13.

[0056] A cross-section of a first embodiment of a passive blender 10 forming part of a system according to the present invention is shown in FIG. 3. The passive blender 10 substantially comprises a swept tee joint formed of a suitable material. The first input pipe 11 from the grid gas pipeline 2 is attached to a side of the passive blender 10. The second input pipe 3 from the unconventional source is attached to a first end of the passive blender 10. The output pipe 12 from the passive blender is attached to a second end of the passive blender 10. The gas from the unconventional source 1 is at pressure ‘P’. The gas from the grid gas pipeline 2 is at the same pressure ‘p’ as the gas in the grid gas pipeline, p being lower than P. Although not accurately depicted in the Figure, where they enter the passive blender the second input pipe 3 is smaller in diameter than the first input pipe 10 and the output pipe 12. In this manner the gas from the unconventional source 1 entrains gas from the grid gas pipeline 2 into its flow and the two are blended together.

[0057] A cross-section of a second embodiment of a passive blender 10′ that may comprise part of a system according present invention is shown in FIG. 4. This passive blender 10′ is cylindrically symmetrical and comprises an input section 21 wherein gas from the grid gas pipeline 2 enters the passive blender, this section narrows in diameter along a direction in which the gas flows. Gas from the unconventional source 1 is input into the passive blender 10′ at the end of the input section 21. The input 22 from the unconventional source 1 is substantially annular and surrounds the end part of the input section such that the gas from the unconventional source 1 is introduced around the gas from the grid gas pipeline 2 at the narrowest point of the passive blender 10′. After the end of the input section 21 is an output section 23 in which the diameter of the passive blender 10′ gradually increases in diameter. The gas from the unconventional source 1 is at pressure ‘P’. The gas from the grid gas pipeline 2 enters the passive blender 10′ at the same pressure ‘p’ as the gas in the grid gas pipeline, p being lower than P.

[0058] The decrease in diameter of the passive blender 10′ in the input section 21 followed by the increase in diameter of the passive blender in the output section 23 result in the passive blender 10′ and the increased velocity and direction of the gas from input 3 using an inspiration effect to entrain and mix the gas from the grid gas pipeline 2 with the gas from the unconventional source 1.

[0059] A third embodiment of a passive blender 10″ that may form part of a system according to the present invention is shown in FIG. 5. The third embodiment 10″ is similar to the second embodiment in that it comprises an input section 21 in which the diameter of the passive blender 10″ reduces and an output section 23 in which the diameter of the passive blender 10″ increases. However, the gas from the unconventional source 1 is injected substantially centrally into the flow of gas from the grid gas pipeline 2 by means of a substantially central injector pipe that has an outer end positioned within the input section 21 of the passive blender 10″. The gas from the unconventional source 1 is at pressure ‘P’. The gas from the grid gas pipeline 2 enters the passive blender 10″ at the same pressure ‘p’ as the gas in the grid gas pipeline, p being lower than P.

[0060] In the same manner as the second embodiment of the passive blender 10′ the decrease in diameter of the passive blender 10′ in the input section 21 followed by the increase in diameter of the passive blender in the output section 23 result in the passive blender 10′ and the increased velocity and direction of the gas from input 3 using the inspiration effect to entrain and mix the gas from the grid gas pipeline 2 with the gas from the unconventional source 1.

[0061] A fourth embodiment of a passive blender that may form part of a system according to the present invention is shown in FIG. 6. This passive blender 10′″ comprises an input section 21 wherein gas from the grid gas pipeline 2 enters the passive blender, this section narrows in diameter along a direction in which the gas flows. The passive blender 10′″ has a central section of relatively low diameter between an end of the input section and a start of an output section 23.

[0062] In the output section 23 the diameter of the passive blender 10′″ gradually increases in diameter. Gas from the unconventional source 1 is input into the passive blender 10′ in the central section. In particular, an input 22 from the unconventional source 1 is substantially annular and surrounds the central section such that the gas from the unconventional source 1 is introduced around the gas from the grid gas pipeline 2 substantially at a mid-point of the central section. The gas from the unconventional source 1 is at pressure ‘P’. The gas from the grid gas pipeline 2 enters the passive blender 10′ at the same pressure ‘p’ as the gas in the grid gas pipeline, p being lower than P.

[0063] The decrease in diameter of the passive blender 10′ in the input section 21, followed by the central section of relatively low diameter, followed by the increase in diameter of the passive blender in the output section 23 result in the passive blender 10′ and the increased velocity and direction of the gas from input 3 using an inspiration effect to entrain and mix the gas from the grid gas pipeline 2 with the gas from the unconventional source 1.

[0064] Any of the passive blenders of FIGS. 3 to 6 may be used in the system of FIG. 2. In any such system a compressor 25 or other similar apparatus may be used to increase the pressure of the unconventional gas before it enters the passive blender 10, 10′ or 10″.