GB2318529A - Degassing device with flow control valve - Google Patents

Abstract

Swirl chamber 17 and reservoir 12 receive fuel to be degassed from any one of compartments 11 of tanker 10 through lines 13. The vortex separator 17 has a gas bubble detector 18 (preferably an optical or infra-red device) and a liquid-level detector 19. Signals from these sensors control a three-way valve 22 which is between the degassing device and the hose reel 23 and outlet 24. If the fuel is free of entrained air, signals from the bubble detector fully open the valve to deliver fuel rapidly to the outlet nozzle 24. However, if the gas detector senses that the fuel contains air, it signals to the valve to restrict the flow of fuel to a slow rate, allowing the fuel in the swirl chamber greater opportunity to release the air therein. This air is vented through line 15. When the trigger at the hose outlet is closed, the valve shuts off the fuel supply to the hose, and recirculates the output from the swirl chamber.

Description

GAS TREATMENT APPARATUS The invention relates to gas treatment apparatus, and particularly, to apparatus for the extraction of gas (e.g. air) from fluids during pumping of the fluids from a tanker vehicle to an outlet, for example a static fuel oil tank.

There are a number of known forms of gas extraction apparatus, but they vary in effectiveness and efficiency and can take up a considerable amount of space on the vehicle.

According to a first aspect of the invention, gas extraction apparatus is provided for attachment to a tanker vehicle, the apparatus comprising a reservoir to receive liquid from a tank, remove gas from the liquid, and deliver the liquid to an outlet, the reservoir having means to detect gas in the liquid, and means to sense the liquid level.

The reservoir may comprise a manifold for liquid combined with a swirl chamber.

The means to detect gas in the liquid preferably comprises an optical device which detects the presence of gas bubbles in the liquid.

The device may be an infra-red device.

The level detector may comprise a pneumatically operated level switch.

Alternatively, it may comprise another optical device.

Preferably, the gas detector and level detector are coupled to a multi position valve such that detection of gas causes a reduction of liquid flow, and subsequent detection of a drop in liquid level causes cessation of liquid flow.

According to a second aspect of the invention, gas extraction apparatus is provided for attachment to a tanker vehicle, the apparatus comprising a manifold for liquid, combined with a swirl chamber, and means to direct liquid from a tank into the manifold and remove liquid from the swirl chamber for delivery, the manifold providing a substantial exposed liquid surface area and the swirl chamber promoting flow of the liquid such as to promote release of gas bubbles from the liquid at the exposed surface in the manifold.

According to a third aspect of the invention, gas extraction apparatus is provided for attachment to a tanker vehicle, the apparatus comprising a combined manifold for liquid and gas extractor, the combined manifold and gas extractor having a common vent pipe.

According to a fourth aspect of the invention, gas extraction apparatus is provided for attachment to a tanker vehicle, the apparatus comprising a combined manifold for liquid and gas extractor, having an optical gas detector and a filter, the filter being such that removal of the filter obscures the optical gas detector thus hindering unauthorised removal of the filter to gain unauthorised access to the liquid supply.

According to a fifth aspect of the invention, a valve is provided for use with an oil delivery system, the valve having a plurality of ports and a plurality of pistons operable to provide the valve with a plurality of operating states, the valve having a body constructed as modules adjustable with respect to one another so that the most convenient orientation of the ports may be selected for any given application of the valve.

By way of example, a specific embodiment of the invention will now be described, with reference to the accompanying drawings, in which Figure 1 is a diagrammatic representation of an embodiment of gas extraction apparatus according to the invention; Figure 2 is a cross-section through a manifold and swirl chamber of the apparatus; Figure 3 is an end view of the swirl chamber; Figure 4 is a plan view of the swirl chamber; Figure 5 is a cross-sectional view through a three-way valve of the apparatus; and Figure 6 is a logic diagram illustrating the operation of the apparatus.

The purpose of the apparatus is to extract gas from fuel oil during pumping of the fuel oil from a tanker vehicle to an outlet, for example a static fuel oil tank.

During movement of such fuel oil by pumping, there is a tendency for gas bubbles to be created and this can have serious implications not only for safety but also for accurate metering of the quantity of fuel oil delivered.

Figure 1 illustrates diagrammatically the tank portion 10 of a vehicle which is divided into four separate compartments 11. Each compartment is linked to a common manifold 12 by an individual supply line 13. The supply lines 13 are controlled by individual valves 14 which are interlocked such that only one tanker compartment can communicate with the manifold 12 at any one time.

The manifold has a vent 15 leading to a shut-off valve 16.

According to one important feature of this embodiment, a swirl chamber 17 is mounted directly underneath the manifold 12.

Within the manifold and swirl chamber assembly, there is mounted an optical bubble detector 18, a liquid level detector 19 and a suction filter 20.

These components interact, in a way to be described below, with a cargo pump 21 and a three-way valve 22 to control the flow of fuel oil such as to extract gas from the fuel oil in a highly effective and efficient manner.

The main outlet from the three-way valve 22 leads to a hose reel 23 and trigger nozzle 24 on the vehicle via a meter 25, shut down valve 26 and non return valve 27.

When fuel oil flows through the apparatus, it passes from the manifold 12 into the swirl chamber 17, passing over weirs 28 (see Figure 2) and past baffles in the form of concentric cylinders 29, eventually reaching the outer periphery of the swirl chamber where the fuel oil exits through a tangential outlet shown at 30 in Figures 3 and 4.

The swirling movement imparted by the design of the swirl chamber assists in the separation of gas bubbles from liquid and the extended liquid surface of the manifold body, positioned above the swirl chamber, is also used to allow rapid separation of gas, which then exits from the upper surface of the manifold into the single vent pipe 15 which accommodates the venting requirements of both the swirl chamber and the manifold.

The optical bubble detector 18 is situated at the top of the suction filter 20, on the upstream side of the filter element, and comprises a fibre optically linked light source and receiver positioned at opposite sides of the manifold.

The device detects bubbles within the liquid. When gas is detected, the device omits a primary signal to slow down the flow of fuel oil through the apparatus, by controlling the three-way valve 22 as described later.

The level switch 19 is positioned at a point adjacent to the exit of the swirl chamber, at the point marked 31 in Figures 3 and 4. This device is used to bring the cargo pump 21 from slow flow operation, once gas has been detected optically in the manifold, to a no-flow state.

The operation of the three-way valve, which is shown in detail in Figure 5, will now be described in more detail.

The valve has an inlet 32 which is connected to the cargo pump 21.

There is a primary outlet 33 controlled by a two-stage poppet valve 34 which is connected to the meter 25. There is also a secondary outlet 35, controlled by a single stage poppet valve 36, the use of which will be described later.

The two-stage poppet valve has a valve poppet 37 spring loaded onto a valve seat and in the closed position shown in Figure 6 communication between the inlet 32 and primary outlet 33 is prevented.

The two-stage poppet valve 34 has two pistons, 38 and 39. Piston 38 is actuated by applying pressurised fluid to a port 40 and piston 39 can be actuated by applying pressurised fluid to a port 41.

The piston 38 has only limited travel and so when pressurised fluid is applied to the port 40 the poppet 37 is only lifted slightly away from the valve seat, and this provides the slow flow condition.

When pressurised fluid is applied to the port 31, the piston 39, which has a greater degree of travel, holds the poppet 37 well clear of the valve seat, and this condition of the valve provides the full flow condition.

Under normal operation, with no detection of air bubbles, the threeway valve is in the full flow condition.

If the optical bubble detector senses the presence of gas bubbles, this causes a signal which removes fluid control pressure from the port 41 of the three-way valve 22 and the valve moves into the slow flow condition.

In this condition air extraction from the fuel oil continues but there is a possibility that the surface level of the fuel oil in the manifold will drop.

If the level drops below a desired level, this is detected by the level detector 19, which is pneumatically operated for reasons of intrinsic safety. If low level is detected, this produces another signal which removes fluid control pressure from the port 40 of the three-way valve 22, causing flow to be stopped completely until the fuel oil level arises again sufficiently within the manifold.

When the three-way valve closes completely, the cargo pump continues to operate, but the fuel oil recirculates. The cargo pump 21 has an in-built full flow relief valve 46 which is capable of either operating as a full system pressure relief, for example 8 bar, or being unloaded proportionally down to, for example 1.5 bar depending on the flow rate of the system. This accommodates the recirculation without causing overheating of the pump.

For some applications, it may be desirable to deliver the contents of the tanker to a direct outlet 42 (see Figure 1) instead of delivering oil to the meter and hosereel. When such delivery is required, the poppet 37 of the three-way valve is closed, and a piston 43 of the poppet valve 36 is actuated by the supply of control fluid to a port 44, thus lifting a poppet 45 off its seat and putting the valve inlet 32 into communication with the secondary outlet 35 which connects to the direct supply conduit 42.

Not shown in Figure 1 is a venturi downstream of the meter 25 which senses pressure drop in the delivery pipework depending on product flow.

This allows proportional pressure reduction in the hosereel, minimising hose dilation when the hose end trigger nozzle 24 is used to conclude a delivery.

The design of the suction filter 20 is such that any attempt to remove or break the filter element joints on the underside of the swirl chamber will cause the optical gas detector 18 to be obstructed, which will bring the system to the slow flow condition. Air cannot therefore be introduced into the pump suction downstream of the gas detection device. For example, part of the suction filter coupling may involve the use of a bayonet fitting which has to be rotated for extraction. The arrangement can be such that rotation of the bayonet fitting to attempt unauthorised removal is detected by the system and causes an aperture in the fitting to move out of register with the optical bubble detector, thus obscuring the optical bubble detector signal.

The suction pipe of the cargo pump 21 may be sealed at both ends for the same reason.

The schematic diagram of the control logic for the apparatus is shown in Figure 6.

A dual rate integrator 50 has an input from the optical detector 18.

The output from the dual rate integrator 50 is respectively connected to ON and OFF connections of a "fast" latch 53 via units 51 and 52. The "fast" latch 53 provides a fast control output signal which is also connected to the ON connection of a "slow" latch 54. An OFF connection of the "slow" latch 54 receives input from the level switch 19. The "slow" latch 54 provides a slow control output.

The "slow" flow control output is enabled once the system is fully primed and degassed as shown. It is disabled if the low level switch 19 operates.

The dual rate integrator 50 is advantageously arranged to have an up rate of perhaps 15% per second, and a down rate of perhaps 180% per second. The direction of integration is up or down depending on the instantaneous state of the signal from the optical detector 18 The dual rate integrator 50, and the two items 51 and 52 effectively form an analogue computer setting the state of the "fast" output according to the short term history of the signal from the optical detector with respect to time.

For correct operation it will be appreciated that the down rate integrator 50, must be faster than the quantity of liquid in the swirl chamber 17, divided by the maximum possible pumping speed of the system.

The proximity of the remotely actuated three-way valve 22 ensures that any air remaining downstream of the pump 21, following a direct delivery through outlet 42, is kept to a minimum in order that any subsequent metered delivery is not rendered inaccurate due to gas entrapment downstream of the gas extractor comprising the manifold and swirl chamber.

By integrating the swirl chamber and pumping system with the manifold, valuable space is made available on the vehicle for extra components. The entire apparatus shown, including bottom loading equipment, to fill the tanker compartments, is easily controlled within a single storage cabinet on the vehicle.

The apparatus may be fitted to existing vehicles. The arrangement of existing pipework on vehicles may vary from vehicle to vehicle. It is an important aspect of the three-way valve shown in Figure 6 that the central valve housing comprises three separate modules 46, 47 and 48. The three modules define respectively the three connection ports 33, 32 and 35.

During assembly of the valve, the modules 46, 47 and 48 can be rotated with respect to one another about the longitudinal axis of the valve, before all the components are bolted together, so that the orientation of each of the ports can be selected for the most convenient connection to existing pipework.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims (14)

1. Gas extraction apparatus for attachment to a tanker vehicle, the apparatus comprising a reservoir to receive liquid from a tank, remove gas from the liquid, and deliver the liquid to an outlet, the reservoir having means to detect gas in the liquid, and means to sense the liquid level.

2. Gas extraction apparatus as claimed in Claim 1, in which the reservoir comprises a manifold for liquid combined with a swirl chamber.

3. Gas extraction apparatus as claimed in Claim 1 or Claim 2, in which the means to detect gas in the liquid comprises an optical device which detects the presence of gas bubbles in the liquid.

4. Gas extraction apparatus as claimed in Claim 3, in which the optical device is an infra-red device.

5. Gas extraction apparatus as claimed in any one of the preceding claims, in which the level detector comprises a pneumatically operated level switch.

6. Gas extraction apparatus as claimed in any one of Claims 1 to 4, in which the level detector comprises an optical device.

7. Gas extraction apparatus as claimed in any one of the preceding claims, in which the gas detector and level detector are coupled to a multi position valve such that detection of gas causes a reduction of liquid flow, and subsequent detection of a drop in liquid level causes cessation of liquid flow.

8. Gas extraction apparatus for attachment to a tanker vehicle, the apparatus comprising a manifold for liquid, combined with a swirl chamber, and means to direct liquid from a tank into the manifold and remove liquid from the swirl chamber for delivery, the manifold providing a substantial exposed liquid surface area and the swirl chamber promoting flow of the liquid such as to promote release of gas bubbles from the liquid at the exposed surface in the manifold.

9. Gas extraction apparatus for attachment to a tanker vehicle, the apparatus comprising a combined manifold for liquid and gas extractor, the combined manifold and gas extractor having a common vent pipe.

10. Gas extraction apparatus for attachment to a tanker vehicle, the apparatus comprising a combined manifold for liquid and gas extractor, having an optical gas detector and a filter, the filter being such that removal of the filter obscures the optical gas detector thus hindering unauthorised removal of the filter to gain unauthorised access to the liquid supply.

11. A valve for use with an oil delivery system, the valve having a plurality of ports and a plurality of pistons operable to provide the valve with a plurality of operating states, the valve having a body constructed as modules adjustable with respect to one another so that the most convenient orientation of the ports may be selected for any given application of the valve.

12. Gas extraction apparatus constructed and arranged substantially as herein described, with reference to the accompanying drawings.

13. A valve constructed and arranged substantially as herein described, with reference to the accompanying drawings.

14. A tanker vehicle having a gas extraction apparatus as claimed in any one of Claims 1 to 12 or a valve as claimed in Claim 13.