GB2064292A

GB2064292A - Whey drainage apparatus

Info

Publication number: GB2064292A
Application number: GB8009466A
Authority: GB
Original assignee: Alfa Laval AB
Current assignee: Alfa Laval AB
Priority date: 1979-03-23
Filing date: 1980-03-20
Publication date: 1981-06-17
Also published as: GB2064292B

Abstract

Apparatus for draining whey from a slurry of curd and whey to form a mat of curd on a moving conveyor in a cheese making installation. The apparatus comprises a reservoir 11, Fig. 1, having a weir 13 for overflow of the slurry from the reservoir, and a downwardly inclined drainage screen 14 for receiving slurry from the weir. The screen is curved with the upper end of the screen lying at a steep angle and the lower end at a shallow angle. The reservoir and screen form a single unit which is adjustable by screw-threaded rods 17 to vary the angle of inclination of the screen. The drainage apertures 52 in the screen are flared in the direction of flow of whey therethrough (see Fig. 3), to cause a reduction of pressure at the surface of the screen and thereby draw the whey into the apertures. <IMAGE>

Description

SPECIFICATION Whey drainage apparatus in cheese making installations This invention relates to whey drainage apparatus in cheese making installations, and is concerned more particularly with apparatus for forming a mat of curd from a slurry of curd and whey for processing on a conveyor of the installation.

The object of the invention is to provide apparatus adapted to drain a large proportion of the whey from a curd and whey slurry before the curd is deposited on the conveyor, and to deposit the curd on the conveyor in a mat of substantially constant thickness.

According to the present invention there is provided apparatus for forming a mat of curd from a slurry of curd and whey for processing on a conveyor in a cheese making installation, comprising a reservoir for the slurry, the reservoir having a weir for overflow of the slurry, and a drainage screen downwardly inclined from the weir for reception of slurry flowing over the weir, the weir being arranged to distribute the slurry substantially uniformly across the width of the screen, and the screen being arranged so that curd will flow downwardly thereon by gravity while whey is draining therefrom and then slide off the lower front end of the screen to form a mat of curd on a conveyor below the screen.

The inclination of the drainage screen is preferably selectively variable in order to control the residence time of the curd on the screen and thereby control the drainage of whey and hence the moisture content of the curd deposited on the conveyor. Conveniently, the reservoir and screen form a single unit which is pivotable to adjust the angle of inclination of the screen.

In a preferred construction, the apparatus includes a drainage tray below the screen for reception of whey draining therethrough. The reservoir, weir and tray then preferably form a single unit, the screen being mounted on the unit across the top of the tray, and the unit being pivotably mounted to adjust the angle of inclination of the screen. The pivot axis of the unit is preferably above the lower end of the screen when the screen is at its smallest angle of inclination to the horizontal, so as to reduce to a minimum the variation, in height of the lower end of the screen upon pivotal movement of the unit.

The drainage screen is preferably curved with the end of the screen adjacent the weir lying at a steep angle to the horizontal and the end of the screen remote from the weir lying at a shallow angle. The curd then tumbles and rolls down the steep upper part of the screen, thereby becoming effectively separated from the whey which drains through the apertures in the screen, but builds up into a mat on the lower part of the screen.

The drainage screen preferably comprises a plurality of horizontal parallel bars spaced apart from one anotherto define drainage apertures therebetween, the bars being of wedge shaped cross section and arranged so that the upper surface of the screen is comparatively smooth and the opposing walls defining the drainage apertures are flared outwardly from one another in the direction from the upper surface to the lower surface of the screen. In use, flow of whey through the flared apertures causes a reduction in pressure at the inlet end of each aperture, due to the increase in cross sectional area in the direction of flow through the aperture. This reduction in pressure draws the whey into the apertures and thereby increases the effectiveness of the screen in separating the whey from the curd.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure lisa sectional side elevation of part of a cheese making installation showing apparatus for forming a mat of curd from a slurry of curd and whey, and part of an endless slat conveyor for receiving the mat of curd for processing in a treatment zone within the installation, the frame of the installation and its outer casing being cut away to show the apparatus and conveyor, Figure 2 is a front elevation of the above mentioned apparatus ofthe cheese making installation, and Figure 3 is a sectional view of part of a whey drainage screen of the apparatus shown in Figures 1 and 2, taken along the line Ill-Ill in Figure 2.

Referring to the drawings, the apparatus in the cheese making installation for forming a mat of curd from a slurry of curd and whey comprises a hollow casing 10 formed of stainless steel and defining a reservoir 11 for reception of a slurry of curd and whey, a tray 12 for reception of whey drained from the slurry, and a weir 13 between the reservoir and the tray. A drainage screen 14 extends downwardly from the weir 13 and across the top of the tray. The front end of the casing 10 is supported on a transverse shaft 15 which is pivotally mounted in bearings (not shown) in the frame 16 of the installation, and the rear end of the casing is supported on two screwthreaded rods 17 (only one of which is shown in the drawings) engaged in screw threaded nuts 18 supported on lugs 19 on the frame of the installation.

The reservoir 11 comprises upright front and rear walls 25, 26, two upright side walls 27, 28 and a semi-circular bottom wall 29 which slopes downwards towards an inlet pipe 30 formed in the side wall 28. The tray 12 comprises an upright rear wall 31, a front wall which has a front section 33 inclined downwards and rearwards at a relatively shallow angle, an intermediate section 34 inclined downwards and rearwards at a steeper angle and a rear section 35 which is upright, two upright side walls 36, 37, and a semi-circular bottom wall 38 which slopes downwards towards an outlet pipe 39 in the side wall 37. The front section 33 of the front wall of the tray lies at a much lower level than the top of the rear wall 31 of the tray.The side walls 27 and 36 are formed from a single side plate 40 which also forms a sidewall oftheweir13. Similarly the side walls 28 and 37 are formed from a single side plate 41 which also forms the other side wall ofthe weir 13. The spillway of the weir comprises a semi-circular wall 42, the rear edge of which is integral with the front wall 25 of the reservoir and the front edge of which is integral with the rear wall 31 of the tray. The casing also includes a cover 43 which is integral with the rear wall 26 of the reservoir and extends across the top of the reservoir, the weir and partially across the top of the tray and screen. The front edge of the cover co-operates with an external casing 44 of the installation which encloses the remainder of the tray and drainage screen.

The drainage screen 14 comprises horizontal transverse bars 45 (Figure 3) mounted on longitudinal bars 46 which are curved along their length. The transverse bars 45 are spaced a short distance from one another and form the upper surface of the screen. The front and rear edges of the screen are fitted with end bars 47, 48 for mounting the screen in position. The drainage screen is mounted across the top of the tray 12 with the end bar 47 detachably secured to brackets (not shown) on the upper end portion of the rearwatl 31 ofthetray, and the remainder of the screen resting on two cross bars 49, 50 fixed to the side walls 36, 37 of the casing. The front end of the screen 14 projects beyond the front wall of the tray.

The parallel bars 45 as shown in Figure 3 are of wedge shaped cross section with flat upper surfaces 51 which co-operate to provide a substantially smooth upper surface to the screen. Each pair of adjacent bars 45 co-operate to define a drainage aperture 52 in which the opposing surfaces 53,54 are flared outwardly from one another in the direction away from the upper surface of the screen. The minimum spacing between the bars 45, that is at the upper surface ofthe screen, is preferably 0.5 mm.

Each bar 45 can conveniently be made of a stainless steel strip with the longitudinal margins turned over to form a hollow wedge shaped bar.

The curvature of the longitudinal bars 46 which support the transverse bars 45 is such that the bars 45 at the rear of the screen adjacent the weir have thsir surfaces consituting the upper surface of the screen disposed at a steep angle, and the bars 45 at the front of the screen have their surfaces constituting the upper surface of the screen disposed at a shallow angle to the horizontal.

An imperforate transition plate 55 is secured to the rear wall 31 of the tray above the screen. The upper edge of the plate 55 engages tangentially against the semi-cylindrical wall 42 of the weir and the lower edge portion 56 of the plate 55 is turned over and abuts the wall 31, the remainder of plate 55 providing a substantially smooth continuous surface between the wall 42 of the weir and the upper surface of the screen The part of the walls 42 of the weir above each screw threaded rod 17 is supported internally by a semi-cylindrical block 60, and a transverse circular section bar 61 is welded in a recess in the block. The upper end of the rod 17 abuts against the bar 61. The lower end of the rod 17 is formed with a handle 62 for turning the rod.

The side wall 27 of the reservoir and the side wall 36 of the tray are each provided with a sealed inspec tion hatch 65 which can be opened for cleaning pur poses. The cover 43 is also provided with an inspec tion hatch 66.

As shown in Figure 1 an endless slat conveyor 68 is mounted on the frame of the installation and arranged to receive curd sliding off the front end of the screen 14. The slats 69 of the conveyor are provided with apertures for drainage of any further whey which may be expressed from the curd while on the conveyor.

In operation, a slurry of curd and whey is fed continuously into the reservoir through the inlet pipe 30.

When the reservoir is full, the slurry flows over the spillway of the weir in a continuous stream of constant depth, and then onto the upper surface of the screen 14. The weir and transition plate provide a primary section having a horizontal imperforate radiused area extending for some distance downwards and above the screen. This primary section is specifically to even out the curd and whey slurry across the full width of the weir spillway, as well as arranged and orient the curd grains evenly to also develop sufficient velocity for arrival at the screen for optimum separation of whey from the curd. The curd in the slurry tumbles and rolls down the steep rear portion of the screen and is thereby effectively separated from the whey which flows through the apertures 52 into the tray 12 and is drained therefrom through the outlet pipe 39.Since the drainage apertures are flared, the flow of whey therethrough causes a reduced pressure in the apertures and this reduced pressure draws the whey into the apertures and thereby increases the drainage effect. When the curd reaches the front portion of the screen which is inclined downwards at only a shallow angle, the curd collects into a mat and then slides off the front end thereof onto the moving conveyor 68.

The period of time spent by the curd on the screen is dependent on the angle of inclination of the drainage screen. Whey is continuously being drained from the curd during its passage down the screen, so that the whey content of the curd can be adjusted as desired by varying the inclination of the screen. This can be done by turning the screw threaded rods 17 so as to raise or lower the rear end of the casing and thereby pivot the whole unit about the shaft 15.

Since the shaft 15 is above and slightly in front of the screen, pivotal movement of the unit about the shaft through a small angle will not appreciably alter the height of the front end of the screen above the conveyor 68.

Claims

1. Apparatus for forming a mat of curd from a slurry of curd and whey for processing on a conveyor in a cheese making installation, comprising a reservoirforthe slurry, the reservoir having a weirfor overflow ofthe slurry, and a drainage screen downwardly inclined from the weir for reception of slurry flowing over the weir, the weir being arranged to distribute the slurry substantially uniformly across the width ofthe screen, and the screen being arranged so that curd will flow downwardly thereon by gravity while whey is draining therefrom and then slide off the lower front end of the screen to form a mat of curd on a conveyor below the screen.

2. Apparatus as claimed in claim 1, wherein the inclination ofthe drainage screen is selectively vari able.

3. Apparatus as claimed in claim 2, wherein the reservoir and screen form a single unit which is pivotable to adjust the angle of inclination of the screen.

4. Apparatus as claimed in claim 2, including a drainage tray below the screen for reception of whey draining therethrough, wherein the reservoir, weir and tray form a single unit, the screen is mounted on the unit across the top of the tray, and the unit is pivotable to adjust the angle of inclination of the screen.

5. Apparatus as claimed in claim 3 or 4, wherein the pivot axis of the unit is approximately above the 'lower end of the screen when the screen is at its smallest angle of inclination to the horizontal.

6. Apparatus as claimed in claim 5, including elevating means operable to adjust the height of the rear end of the unit so as to pivot the unit about said axis.

7. Apparatus as claimed in any of claims 1-6, wherein the rear end of the screen adjacent the weir lies at a steep angle to the hozizontal and the front end of the screen remote from the weir lies at a shal low angle.

8. Apparatus as claimed in claim 7, wherein the drainage screen is curved from the rear end ofthe screen adjacent the weir to the front end of the screen remote from the weir.

9. Apparatus as claimed in any ofthe preceding claims, wherein the screen comprises a plurality of parallel bars spaced apart from one anotherto define drainage apertures therebetween, the bars being of wedge shaped cross section and arranged so that the upper surface of the screen is comparatively smooth and the opposing walls of the bars defining the drainage apertures are flared outwardly from one another in the direction from the upper surface to the lower surface of the screen.

10. Apparatus as claimed in claim 9, wherein the parallel bars extend across the screen transversely with respect to the direction of flow of curd down the screen.

11. Apparatus as claimed in claim 9 or 10, wherein the bars are spaced apart a distance of approximately 0.5mm.

12. A cheese making installation comprising a conveyor for passing cheese curd through a treat ment zone, and apparatus as claimed in any of the preceding claims arranged to receive a slurry of curd and whey in said reservoir and deposit curd from the lower end of the screen onto said conveyor to form a mat of curd thereon.

13. Apparatus for forming a mat of curd from a slurry of curd and whey for processing on a conveyor in a cheese making installation, substantially as hereinbefore described with reference to the accompanying drawings.