NZ226003A - Apparatus for monitoring specific gravity of a liquid such as fermenting beer - Google Patents

Description

22 6 0 0 3 No.: Date: Priority Date(s): Complete Specification Filed: Class: S.Q 1 /.tO.,.IS i . I Publication Date: P.O. Journal, No: ., iSSk NEW ZEALAND PATENTS ACT, 1953 COMPLETE SPECIFICATION "METHOD AMD APPARATUS FOR MONITORING THE SPECIFIC GRAVITY OF A LIQUID" I/We, PCA ASSOCIATES (CONGLETON) LIMITED, a British company of 19 Moody Street, Congleton, Cheshire, CW12 4AN, United Kingdom hereby declare the invention for which I / we pray that a patent may be granted to me /us, and the method by which it is to be performed, to be particularly described in and by the following statement:- (followed by page la) iiiSSrt 3i' •f ■ 22(5003 - lC\- METHOD AND APPARATUS FOR MONITORING THE SPECIFIC GRAVITY OF A LIQUID o -« : 1—? 1 I l a This invention relates to a method of and apparatus for monitoring the specific gravity of a liquid, especially but not exclusively a fermenting liquid such as beer.

It is known that the specific gravity of a fermenting liquid such as beer decreases as sugars in the liquid are converted to alcohols and it is desirable that process workers operating the fermenting process be aware of such changes in specific gravity for efficient operation of the process.

It is therefore an object of the present invention to provide a simple and effective method of and apparatus for monitoring, continuously or intermittently, the specific gravity of a liquid, especially a fermenting liquid.

The present invention has particular but not exclusive application to the brewing industry.

According to the present invention, therefore, there is provided apparatus for monitoring the specific gravity of a liquid, comprising support means, a load sensing beam mounted as a cantilever on the end of said support means and being associated with four strain gauges mounted on the beam at the corners of a parallelogram for determining deflection of the beam, and an elongate displacement body with a weight per unit volume greater than that of the liqu to be monitored pivotally suspended from the beam, whereby the apparatus is insertable through, and supported by, the wall of a vessel for holding said liquid- Also according to the present invention there is prided apparatus as claimed in claim 1, wherein the is of rectangular cross-section and has two engrally coplanar circular apertures in the plane of ei^'ht sensing deflection of the beam. 22 6 0 Preferably, the connection between the weight-detecting sensor and the body is a pivotal one.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which Fig. 1 is a fragmentary part-sectional side elevation of a process receptacle, for example a fermenting vat, with the specific gravity monitoring apparatus according to the present invention; Fig. 2 is a fragmentary side elevation of the specific gravity monitoring apparatus to an enlarged scale, but omitting details of the spray tube.

Fig. 3 is a detail of the load cell used in the apparatus of Fig. 1; Fig. 4 is a view on the line IV-IV of Fig.3; and Fig. 5 is a modification of the beam deflection limiting means shown in Figs. 3 and 4.

Referring to the drawings, a wall of the fermenting vat within which, for example, beer (B) is being fermented is indicated at 10. The wall 10 adjacent the bottom of the vat which may be of considerable height, say 50.to 60 feet, is apertured at 11 and has an integral tubular port 12 flanged at 13.

The specific gravity monitoring apparatus of the present invention generally indicated at 14 is inserted through this port 12 into the vat and is partially accommodated within the port 12.

The monitoring apparatus 14 comprises an elongate displacer 15 in the form of a closed tubular body of known volume and weight suspended in cantilever fashion within the beer contained in the vat. This displacer 15 is sufficiently substantial so as to have a sufficiently high moment of inertia so as to be generally unaffected by the movement of' 226003 3 \ . (( bubbles and suspended solids in a fermenting liquid.

A bar or rod 16 is welded to one end of the displacer body 15 and is pivoted as indicated at 17 to one end of a load cell unit 18 (indicated in more detail in Fig. 3) forming part of a cantilever beam from which the displacer body 15 is suspended as aforesaid.

The cantilever beam also comprises a support tube 19 welded to the load cell 18, the support tube 19 extending through, and out of, the port 12 and having a flange 20 whereby the cantilever beam 18, 19 is bolted as indicated at 21 to the port flange 13. A sealing disc 22 or similar is sandwiched between the flanges 13, 20.

The signal cable of the load cell unit 18 is indicated at 23 and is housed in the support tube 19. The cable 23 egresses from the support tube 19 externally of the vat as shown and is coupled to amplifying means (not shown) and thereafter to a signal processing means giving, for example, a read-out in units of specific gravity.

The support tube/load cel.! arrangement 18, 19 is a sealed unit to prevent process product, for example, beer ingress, and it together with the displacer body 15 and bar or rod 16 are made of stainless steel, for example 316 stainless steel, to prevent process product contamination and corrosion.

The cantilever beam connection or joint 13, 20 to 22 is leak-proof due to the provision of the sealing disc 22, and is rigid with the port 12 and consequently the vat.

Referring now to Figs. 3 and 4, the load cell unit 1R will be seen to comprise a load sensing beam ! of rectangular cross-section and which has two generally circular which open one into the other. Beam 24 is enclosed in bellows 26. A total of four strain gauges 27 are bonded (e.g. by welding) to beam 24 and each positioned above or below a respective circular cut out 25 as shown. The use of four strain gauges (mounted at the corners of a parallelogram) on the beam 24 means that deficiencies in the machining of the beam 24 are compensated and that accurate measurement of beam deflection is possible. As a variation, it would be possible to use only two strain gauges 27, (positioned diagonally opposite each other) but the measurement would not be so accurate. Obviously the strain gauges are associated with the necessary means for measuring the deformation of the beam.

A rod 28 is screwed at one end into a support 29 (at the end of beam 24) and its free end locates in an elongate aperture 30 in a circular plate 31. Rod 28 serves to prevent excessive deflection of beam 24 (such as might occur by draining of the vat whilst leaving the displacer 15 freely suspended) by engaging against the ends of aperture 30 at a predetermined deflection of the beam.

A modification for rod 29 and aperture 30 is shown in Fig. 5 in which the rod (designated here as 291) has a tapered end. This taper allows for calibration of the over-range limit adjustment.

A platinum resistance thermometer 32 is bonded to beam 24 as shown.

A further feature of the apparatus is a spray tube 33 extending beneath, and parallel to, the support tube 19. This spray tube is for use in sparging the apparatus and for this purpose is connected to a supply of cleaning liquid (e.g. water).

The apparatus is used as a continuous on-line -mongrfcor for the specific gravity of a liquid, particularly a fermenting liquid (e.g. beer). The support tube 19 and displacer 16 are completely submerged in the liquid whereof the specific gravity is to be monitored. Ideally, the volume and/or weight of the displacer 15 is such that at the start of fermentation there is substantially no deflection of the beam 24. The load cell 18 detects apparent gains/losses in weight of the displacer body 15 due to changes in the specific gravity of the beer during fermentation. Signals generated by the load cell 18 are, as aforesaid, transmitted by the cable 23 to the amplifying means and the signal processing means to give the read-out in specific gravity units. The measurement is unaffected by bubbles and suspended solids which, as mentioned previously, do not cause movement of displacer 15.

Thus the specific gravity is continuously monitored to permit a process worker to check and adjust the process operation if necessary.

The platinum resistance thermometer 32 measures the temperature of the beer and allows a correction to be made for giving the specific gravity at a standard temperature, such as may be required for excise duty purposes.

Due to the pivot connection 17 between the displacer body 15 and the cantilever beam 18, 19, it is a simple matter to remove the specific gravity monitoring apparatus 14 through the port 12 after releasing the connection or joint 13, 20 to 22 for maintenance, repair or replacement purposes for example. Re-insertion, or insertion of a replacement apparatus, is equally simple.

Although the invention has been described with specific reference to a support tube 19 extending horizontally from the wall of the vessel, it is possible for the tube to be generally L-shaped with 22 6 0 0 3 one vertical limb (supported above the vessel) and a horizontal limb on which the load sensing beam is mounted.

Claims (19)

WHAT WE CLAIM IS:

1. Apparatus for monitoring the specific gravity of a liquid comprising support means, a load sensing beam mounted as a cantilever on the end of said support means and being associated with four strain gauges mounted on the beam at the corners of a parallelogram for determining deflection of the beam, and an elongate displacement body with a weight per unit volume greater than that of the liquid to be monitored pivotally suspended from the beam, whereby, the apparatus is insertable through, and supported by, the wall of a vessel for holding said liquid.

2. Apparatus as claimed in claim 1, wherein the beam is of rectangular cross-section and has two generally circular apertures in the plane of weight sensing deflection of the beam, and two of said strain gauges are respectively mounted above and below one of said apertures and the other two strain gauges are respectively mounted above and below the other of said apertures.

3. Apparatus as claimed in claim 1 or 2, provided with means for limiting the deflection of the beam.

4. Apparatus as claimed in claim 3,wherein the means for limiting the deflection of the beam comprises a rod fixed at one end relative to deflection of the beam and locating at its.other end in a deflection limiting aperture provided adjacent the end of the beam from which the displacement body is suspended. f) 22600 8

5. Apparatus as claimed in claim 4, wherein the deflection limiting aperture is provided in a flange around the beam.

6 . Apparatus as claimed in any one of claims 1 to 5, provided with a platinum resistance thermometer.

7 . Apparatus as claimed in claim 6 , wherein the thermometer is mounted on the beam.

R'. Apparatus as claimed in any one of claims 1 to 7, wherein the support means is an elongate cantilever support for insertion through, and support by, the wall of a vessel containing liquid.

9. Apparatus as claimed in claim 8, having a spray tube extending parallel to the cantilever support.

10. Apparatus as claimed in claim 8 or 9, in which the cantilever support comprises a support tube connectible, at one end, to the vessel wall and having, at its other end, the load sensing beam.

11. Apparatus as claimed in claim 10, in which a signal-transmission cable from the means for measuring deflection of the beam is housed within the support tube.

12. Apparatus as claimed in claim 10 or 11, in which the support tube is adapted to extend through and be flange-connected to a port in the vessel

13. Apparatus as claimed in claim 12, in which the flange connection incorporates liquid sealing means.

14. Apparatus as claimed in claim 11, in which the signal transmission cable externally of the wall vessel and support K'W />'•. v.:-f-y'.'C-ISi'-i V.A'-' .....j-v!~".i., 226003 9 signal-amplifying means and signal-processing means.

15- Apparatus as claimed in claim 14/ in which the signal-processing means provides a read-out of the apparent body weight gains/losses in terms of specific gravity units.

16. Apparatus as claimed in any one of claims 1 to 15, wherein the displacement body is an elongate body.

17- Apparatus as claimed in claim 16, wherein the elongate body is a sealed hollow tube of known weight and volume.

18. A vessel for holding a liquid and provided with apparatus as claimed in any one of claims 1 to 17.

19. Apparatus for monitoring the specific gravity of a liquid substantialy as hereinbefore described with reference to Figs. 1 to 4 or Fig. 5 of the accompanying drawings. By tyterfthelr authorised Agents., A. J. PARK & SON. Per -■v&uat.