GB2053709A - An installation and process for the filtering of beer - Google Patents

Abstract

Prior to filtering, a multiple sheet filter is prepared by circulating water under carbon dioxide pressure to remove residual air, then two successive layers of kieselguhr filter aid are applied to the filter, all at specific flow rates. The beer is then filtered, with a further supply of kieselguhr being added continuously thereto. After filtering, residual beer is ejected from the filter by supplying water.

Description

SPECIFICATION An installation and process for building up a filtering substrate for the filtering of beer after fermentation The invention relates to a process for building up a filtering substrate of the cardboard type by deposition of a first and second preliminary layer, as well as to the circuit for carrying out the process.

In the food industry and, more particularly, in the brewing industry, the capacity of filter batteries is increasing considerably.

Some installations now have filter batteries having aflow rate of 1000 hl/l permitting the total volume of the largest fermentation tanks existing at present to be filtered in about ten hours.

For such rates of flow, the surfaces of the filtering elements can be as much as several square meters.

It is important to obtain the best performance from these batteries of filters by: a) correctly filling all the frames right up to the last one; b) lining the filtering substrates over their entire surface area, including the edges, without blisters; c) not altering the hydraulic characterisitcs of flow and of pressure in the filter; d) making the quantity of oxygen added as small as possible; e) making the degree of lustre as small as possible.

The conventional processes for the deposition of preliminary layers only allow suitable results to be achieved on medium filters. With these large capacity filters, the results of conventional processes have turned out to be rather mediocre in view of the large quantities filtered.

The attractive performances of the process according to the invention and of the installation for carrying out the process will be specified in detail in the following description.

The invention also relates to the production of a completely automatic installation which utilises cartridges which filter for longer and reduces the time for intervention between two filtration operations and the actual duration of filtration.

For this purpose, the invention relates to a process for building up a battery of filters, in particular cardboard-type filters, by successive depositions of a substrate composed, for example, of diatomaceous earth, in particular kieselguhr, which is distinguished by an initial phase at high speed in which the circuits are established and the air is evacuated by water emanating from a slightly pressurised tank, in that the first preliminary layer having the largest granulometry is injected using the water as a carrying medium without altering the flow and pressure characteristics in the filter, in that the second preliminary layer having an intermediate granulomentry is injected without altering the hydraulic characteristics of the filter, in that actual filtration of the beer is gradually carried out using a water and beer mixture, by reducing the quantity of water until pure beer is obtained, alluviation being carried out throughout this operation by addition using a special vat with control of the charge.

The installation comprises a main circuit for circulating water from a tank under carbon dioxide pressure to which is attached a circuit for supplying a kieselguhrsuspension, a separate ailuvation circuit, a point for injection of the beer originating from the fermentation tanks and a double outlet connected to the rinsing water tank.

As a result of this procedure, all air pockets are eliminated, the filtering elements are lined integrally over their entire useful suface area and are made to operate with maximum yield due to homogeneous distribution.

The cycle time decreases considerably. Calculations show that a saving of 50% can be achieved.

Quite exceptional results in terms of lustre and quantity of disolved oxygen are achieved in view of the large quantities filtered.

Moreover, the following additional advantages should be mentioned: i) excellent reliability; ii) lustre required in finished product obtained from start; iii) total absence of air pockets which permits elimination of automatic flushing device; iv) rapid drop in the dissolved oxygen content and very slight addition during operation; v) integral preservation of the quality of the beer.

The invention will be understood better on reading the following description given as a non-limiting example with reference to the attached drawing showing schematically the circuits of the installation designed for carrying out the process according to the invention.

The installation will be described first of all so that reference can be made to the circuits in the corresponding part of the process.

The filtration installation has a main circuit comprising a battery 2 of flat filters 3 of the cardboard type held by frames 4.

This battery constitutes a filter having a high rate of flow of the order of 1000 hl/h and is capable of meeting the requirements of a large capacity brewery (of the order of ten million hectolitres per year).

The main circuit 1 is composed upstream of a tank or reservoir of rinsing water 5, preferably water which is deaerated under carbon dioxide pressure by a device 6, followed by a pipe 7 to the battery 2.

A feeder 8 for the supply of fermented beer to be filtered originating from fermentation tanks such as 9 is connected to this pipe 7.

Two injection points 10 and 11 representing the inlets from the alluviation circuit 12 and the supply circuit 13 of the filtering substrate are also connected to this pipe.

These circuits are each connected via a separate pump such as 14to an alluviation reservoir 15 and to a reservoir 16 filled with deaerated water charged with kieselguhr and stirred continuously by an agitator 17 which maintains the homogeneity of the suspension.

The filter outlet is connected to two distinct circuits 18 and 19 possessing two feeders 20 and 21 respectivelyforthe so-called "Vorlauf" and "Nachlauf" (literally pre-run and after-run), the rinsing circuit also comprising a three-way valve 22 with a return branch 23 into the reservoir 25.

The filtered beer issues at 24, in principle via the circuit 19.

The building process according to the invention involves building up the battery of filters having a large surface area in the following manner, using the installation described above.

The filter is prepared during an initial phase at a high rate of flow of from 1200 to 1300 hl/l by circulating water, preferably deaerated water, from the reservoir 5, this water being presurised by compressed carbon dioxide at about 1.5 kg/cm2.

The circuits are established by regulating the rate of flow and by keeping the pressure very constant.

The remaining air returning into the flask is flushed out.

The air is completely evacuated after 2 - 3 minutes.

Once the operations of flushing and filling with water are quite complete, injection of the first preliminary layer is begun at the same flow rate of 1200 to 1300 hl h.

The first preliminary layer is injected in the form of a kieselguhr suspension from the reservoir 16 using water which constitutes the carrying medium for a phase of approximately 15 minutes at the same rate of flow, that is to say a quantity of the order of 20hl.

The hydraulic characteristics: flowrate, pressure are not altered.

An identical sequence is followed for the injection of the second preliminary layer of kieselghur having an intermediate granulometry. Hydraulic characteristics remain identical.

This second injection operation also lasts about 15 minutes.

The beer is then filtered. Grading is then effected using a water and bere mixture by the known "Varlaug" and "Nachlauf" technique.

Once only the beer remains, the actual filtration operation begins at a flow rate of 1000 hl h, that is to say about 10 hours in the case of the very large capacity fermentation tanks used at present.

Alluviation is carried out throughout this entire operation by supplying another type of kieselghur through the circuit 12 from the special alluviation reservoir 15.

This alluviation operation is carried out with strict control of the charge.

At the end of the filtration operation, the beer remaining in the circuit is pushed by water and the water and beer mixture is evacuated by the "Nachlauf" technique.

In addition to the significant gain in the duration of operation and of utilisation of cartridges, the process according to the invention gives surprising results in terms of lustre with the EBC index falling to from 0.2 to 0.3 from the second preliminary layer whereas it was 1.5 in the conventional processes.

With regard to the oxygen, a slight increase of the order of only 0.2 maximun in the relative value is detected, thus eliminating any risk of oxidation.

Claims (2)

1. A process for building up a battery of filters of large capacity, in particular cardboard filters with a filtering substrate of the diatomaceous earth type, in particular kieselguhrtype, characterised in that the filter is prepared during an initial phase at a high flow rate from about 1200 to 1300 hlih by circulation of water, preferably deaerated water from a reservoir under carbon dioxide pressure at about 1.5 kg/cm2, during which phase the circuits are established by regulating the flow rate and the pressure, the air is completely evacuated in the space of from 2 to 3 minutes, in that injection of the first preliminary layer is begun at the same flow rate through a separate circuit using kieselguhr suspension from a reservoir provided with an agitator, the hydraulic characteristics are not altered, this phase lasts approximately 15 minutes, the second preliminary layer of intermediate granulomentry is then injected, the hydraulic characteristics remaining the same, filtration is subsequently carried out with a water and beer intermediate mixture, filtration being carried out at a flow rate of 1000 hl;h while an additional supply is constituted by another type of kieselguhr (alluviation) with strict control of the charge; the beer is evacuated by pushing it with water.

2. An installation for carrying out the process according to Claim 1, characterised in that it is composed of a main circuit 1 comprising a reservoir 5 of water under carbon dioxide pressure, of an inlet 8 for the fermented beer emanating from a fermentation tank, of an alluviation inlet 10, of an inlet 11 for the injection of preliminary layers, of the battery of filters 2, of a double evacuation pipe with return along one of the lines to the pressurised water reservoir 5 and in that the inlet 10 constitutes the merging of the alluviation circuit formed by a alluviation tank 15 and a separate pump, and the inlet 11 similarly constitutes the merging into the main circuit of the circuit for the injection of the preliminary layers from a separate pump and a reservoir having an agitator.