GB2307230A

GB2307230A - Filling a pressurised container

Info

Publication number: GB2307230A
Application number: GB9523729A
Authority: GB
Inventors: David Stollery
Original assignee: MFW SYSTEMS Ltd
Current assignee: MFW SYSTEMS Ltd
Priority date: 1995-11-20
Filing date: 1995-11-20
Publication date: 1997-05-21
Also published as: GB9523729D0

Abstract

A method of filling a pressurized container (3) with flowable material, e.g. beer, comprises continuously sensing the weight of the container and its contents as it is filled and automatically arresting, in dependence on the sensed weight, the flow of material into the container (3) when a predetermined amount of flowable material has been introduced.

Description

FILLING A PRESSURISED CONTAINER This invention relates to a method and apparatus for filling a pressurised container with flowable material. In particular, but not exclusively, this material is a liquid, such as beer, but it could comprise a powder.

A method of filling pressurised beer containers known as the gross tare method is currently used. In this method, a container or keg pre-pressurised with nitrogen at approximately 1.7 x lO5Pa is received and weighed at a tare station. The container is then transferred to a fill station where it is filled via a filling valve using a flowmeter to measure the flow of beer. The full container is finally brought to a gross station where it is allowed to settle and then weighed. A computer deducts the tare weight of the container from the gross weight to obtain the weight, and hence the volume, of beer in the container, the computer having been preset with the specific gravity of the beer.

A running average volume is then compared for a number of containers which have been filled and this average value is used to determine the volume with which the next container is to be filled.

A disadvantage of such a passive system is that in order to avoid under-filling the container, the volume of beer per container is set higher than the specified filled value.

This results in excess product being manufactured and dispatched with consequent extra cost and duty. In addition, the known system is dependent upon the accurate cooperation of numerous items of plant. This cannot be achieved on a repeatable basis and extensive maintenance programmes are necessary.

It is an object of the invention to alleviate the above disadvantages.

According to one aspect, the invention consists in a method of filling a pressurised container with flowable material, comprising continuously sensing the weight of container and its contents during filling and automatically arresting, in dependence on the sensed weight1 the flow of the material into the container when a predetermined amount of flowable material has been filled into the container.

Preferably, the rate of flow of material into the container is reduced as more material is introduced into the container. This enables the material to be introduced initially at a fast rate and later at a slower rate during the final stages of a filling operation. The reduction in flow may comprise a reduction in one or more steps from a high flow rate to a low rate.

According to another aspect, the invention consists in apparatus for filling a pressurised container with flowable material comprising valve means through which the container can be filled, means continuously sensing the weight of the container and its contents during filling, and control means closing said valve means in response to a signal received from the sensing means indicating that a pre-determined amount of flowable material has been filled into the container.

Preferably said valve means is controlled by said control means to reduce the flow of material in response to the sensing means indicating that the full pre-determined amount of material to be filled into the containter has almost been reached. For this purpose the valve means may comprise a multi-stage valve operable to allow different flow rates.

The sensing means preferably comprises at lease one load cell for determining the weight of the container. The control means suitably includes computer means for controlling the valve means.

An embodiment of invention will now be described in more detail, by way of example only, with particular reference to the accompanying drawings, in which: Figure 1 shows a side view of an embodiment of apparatus according to the invention, and Figure 2 is a schematic section taken along the line II II of Figure 1, viewed in the direction of the arrows.

Referring to the drawings, a frame 1 of the apparatus supports a feed conveyor 2 along which pre-pressurised inverted beer containers 3 are transported under the control of a main plant controller (not shown) to a beer filling station at which a filling head 4, supported by a filling head mounting 5, is aligned with a valve in the container presently in the filling station. As shown the valve is in the bottom of each container 3, but because of the inversion of the containers, the valve is acturally in the top of each container. A clamping plate 6 clamps the container against the filling head. The clamping plate is fixed to the end of a piston 7 which extends from a pneumatic clamping cylinder 8 retained in a cylinder mounting 9. The clamp/filling head assembly is fixed to a platform 10 mounted on load cells 11 which in turn are mounted on a base unit 12.The load cells are wired to an electronic weighing unit (not shown). The base unit 12 contains a conventional service bulkhead having the elements necessary for the filling operation.

When the container 3 is clamped in place a three stage valve 13 is applied to a valved opening in the "top" of the container. The electronic weighing unit interfaces with the main plant controller to control the filling sequence. The valve 8 has large and small orifices which may be selectively aligned with the valved opening of the container by means of a pneumatic valve cylinder 14 to allow fast and fine filling, respectively. Filling of beer under pressure into the container commences through the large orifice and the weight of the container and its contents is continuously sensed by the load cells 11 and the electronic weighing unit, which has been preset with a value corresponding to the weight of an accurately filled container.

When the sensed weight approaches within a pre-determined range of the preset value, an electronic controller (not shown), supplied with signals from the electronic weighing unit, controls the cylinder 14 to adjust the valve 13 by aligning its smaller orifice with the valved opening of the container 3. Filling of the container is thus completed at a slower rate and when the preset value is reached, the electronic controller closes the valve 13 thus ensuring that the container 3 has been filled with an accurate volume of beer. A pressure valve 15 relieves the excess filling pressure.

Subsequently, control is transferred back to the main plant controller and the filled container is removed by means of a discharge conveyor 16.

A control panel of the apparatus includes a key pad by which any of a number, e.g. 32, of weight values can be preset as well as an additional weight value which is adjustable via the interface at any time.

The apparatus is operable in a calibration mode, in which a container of known weight is used to calibrate the load cells, and in a self-diagnostic mode in which any faults in the automatic functions are detected.

The interface between the electronic weighing unit and the main controller allows the parameters of the former to be adjusted by the latter. Individual sum weights can be output and the number of filling operations and any errors can be passed to the main controller.

The apparatus of the invention can be installed into existing plant as described above or used on its own as a freestanding unit. It is also possible to connect more than one apparatus together and operate them in tandem via one interface. Whilst the system maintains total control of the product at all times, even in the case of varying pressure drops at the filling valve, a manual override feature is provided for safety.

Although the supply of beer into the container has been described with respect to a step control, it will be appreciated that other forms of control may be provided. In its simplest form,the control is merely required to arrest the filling of the beer into the container at the required moment. In other embodiments however, continuous control as opposed to stepped control, may be provided to provide control at least during the final stages of a filling operation.

It will be appreciated that the use of initial fast filling in conjunction with the automatic termination of fine filling maximises both the filling accuracy and speed. In addition, the most favourable instant for final weighing is automatically detected. The capital and maintenance costs of separate gross and tare weighing platforms is avoided and the performance of existing plant maximised. Due to the total control of the "in-flight" product, the system is not dependent on flowmeters. Results are obtained to a high standard of validity and the accuracy of filling avoids the dispatch of the excess product, this increasing profitability. The mechanical handling of the containers remains unaltered from existing systems but maintenance is minimised.

The invention is applicable to the metered or volumetric filling of pressurised containers with liquids and powders wherever accuracy and repeatability are required.

Claims

1. A method of filling a pressurised container with flowable material, comprising continuously sensing the weight of the container and its contents during filling and automatically arresting, in dependence on the sensed weight, the flow of the material into the container when a predetermined amount of flowable material has been filled into the container.

2. A method according to claim 1, in which the flowable material is a liquid.

3. A method according to claim 2, in which the liquid comprises beer.

4. A method according to claim 1 or 3, in which the rate of flow of material into the container is reduced as more material is introduced into the container.

5. A method according to claim 4, in which the reduction in flow occurs in one or more steps from a high flow rate to a low rate.

6. A method according to any one of the preceding claims, in which the flowable material is introduced into the container through a valve positioned, when the container is filled, at the bottom of the container.

7. Apparatus for filling a pressurised container with flowable material comprising valve means through which the container can be filled, means continuously sensing the weight of the container and its contents during filling, and control means closing said valve means in response to a signal received from the sensing means indicating that a pre-determined amount of flowable material has been filled into the container.

8. Apparatus according to claim 7, in which said valve means is controlled by said control means to reduce the flow of material in response to the sensing means indicating that the full pre-determined amount of material to be filled into the container has almost been reached.

9. Apparatus according to claim 8, in which the valve means comprises a multi-stage valve operable to allow different flow rates.

10. Apparatus according to any one of claims 7 to 9, in which sensing means comprises at least one load cell for determining the weight of the container.

11. Apparatus according to any one of claims 7 to 10, in which control means includes computer means for controlling the valve means.

12. Apparatus for filling a pressurised container with flowable material constructed and arranged substantially as herein described with reference to, and as illustrated in, Figures 1 and 2 of the accompanying drawings.

13. A method of filling a pressurised container with flowable material, the method being substantially as herein described with reference to, and as illustrated in, Figures 1 and 2 of the accompanying drawings.