GB2089640A

GB2089640A - Method of an apparatus for making an animal feed from a beet material

Info

Publication number: GB2089640A
Application number: GB8138680A
Authority: GB
Original assignee: Danske Sukkerfabrikker AS
Current assignee: Danske Sukkerfabrikker AS
Priority date: 1980-12-23
Filing date: 1981-12-23
Publication date: 1982-06-30
Also published as: CH646584A5; JPS57194754A; DE3150592A1; DK147291B; ES8304769A1; AT375246B; PL234377A1; BE891582A; ATA552381A; FR2496410B1; YU42028B; ES508246A0; NL8105766A; YU305681A; DK553580A; DK147291C; FI814139L; IT8125768A0; FR2496410A1; IT1211152B

Abstract

Beet material, such as extracted sugar beet slices or sugar beet peels, is subjected to acid hydrolysis in a hydrolyzer at elevated temperature and elevated pressure to form a hydrolyzed product, which is separated on a filter into a liquid fraction which is neutralized and evaporated to form a low moisture content liquid product suitable as animal feed, and a solids fraction. The solids fraction may be pressed to form a product having a high dry matter content or may be used directly as a starting material for the production of glucose by acid hydrolysis.

Description

SPECIFICATION Method of and apparatus for making an animal feed from a beet material This invention relates to a method of and apparatus for making an animal feed from a beet material and more particularly from extracted sugar beet slices and beet peels.

During the production of sugar from sugar beets the beets delivered to the sugar factory by the farmers are initially washed to remove soil and other contaminations adhering to their surfaces and are subsequently sliced.

It is well known to remove the outer layer of the washed sugar beets before they are sliced in order to obtain an increased yield of sugar compared to the yield obtained by the above-mentioned traditional washing method. The sliced sugar beets are then extracted with water to form a sugar juice which is then worked up, ordinarily in the form of crystalline sugar. The extraction step may be carried out in an extractor comprising an inclined trough and two or more rotatable screw conveyors mounted in the trough in such a matter that sugar slices introduced into the trough at its lower end are carried towards its upper end in countercurrent with water, which is introduced into the trough at its upper end and which after being enriched with sugar is discharged from the trough at its lower end in the form of sugar juice.

The extracted sugar slices which may be called beet pulp and which is the residue left when the major proportion of soluble sugars and salts have been removed as a result of the extraction are ordinarily compressed so as to increase the dry matter content to a value of between about 11% and 21% by weight depending on the press used.

By adding a chemical, such as Al2(SO4)3 to the pulp, the dry matter content may be increased by further 1-2%.

The compressed beet pulp may be used as a ruminant feed either directly or after being ensiled.

Since the compressed beet pulp still has a relatively high moisture content, it is inconvenient to ship it over longer distances. Therefore, if it has to be used at places which are remote from the sugarfac- tory, it is ordinarily dried. The product thus obtained is commercially available in some countries under the registered Trade Mark "PULPETTER".

It is possible to add molasses to the dried beet pulp and a product thus obtained is commercially available in some countries under the registered Trade Mark "KOSETTER". Both products are suitable as ruminant feeds.

Both the compression and the drying of the compressed pulp is energy consuming and as a result of continuously increasing energy costs there is a need for providing a low energy method of making an animal feed having a low water content from beet materials.

The present invention in one aspect provides a method of making an animal feed from a beet material, comprising subjecting the beet material to acid hydrolysis at an elevated temperature and an elevated pressure, and separating the hydrolyzed product into a liquid fraction which is subsequently neutralized and evaporated to form an animal feed having a low moisture content, and a solids fraction.

The invention is based on the discovery that beet materials, such as pulp and beet peel, contain several polymers, such as pectin and pentosans, which at elevated temperature and elevated pressure can be hydrolyzed with acid to form a liquid hydrolyzate which is easy to evaporate to form a product which is similarto molasses and has a high dry matter content, e.g. of about 60%.

The invention is also based on the discovery that when the hydrolyzed products have been removed therefrom, the solids fraction is easy to compress so as to obtain a dry matter content of above 30%, i.e.

considerably higher than the 22-23% which is the maximum dry matter content obtainable by the prior art method comprising the addition of chemicals.

However, it should be noted that the solids fraction without being compressed is suitable for the production of glucose by hydrolysis because the relative amount of cellulose in the starting material has been considerably increased as a result of the removal ofthe hydrolyzable products.

During the acid hydrolysis step the starting material is preferably heated to a temperature of 100-165"C, or 104-165"C, and more preferably about 1300C. The heating is preferably effected by steam injection.

It is preferable to effect the hydrolysis at a pressure of from 100 to 920 kPa and more preferably from 300 to 510 kPa.

The acid used is preferably a strong inorganic acid, such as sulfuric acid, phosphoric acid or hydrochloric acid. The beet material is preferably impregnated with acid at room temperature and atmospheric pressure, i.e. before it is heated to an elevated temperature and put under pressure.

The invention in another aspect provides apparatus for making an animal feed from a beet material, comprising a mixer for providing a mixture of beet material and acid; a hydrolyzer which is connected to the mixer and which includes means for establishing a superatmospheric pressure within the hydrolyzer, means for heating the contents of the hydrolyzer and means for discharging treated material from the hydrolyzer; means for separating the hydrolyzed product into a liquid fraction and a solids fraction; and means for neutralizing and evaporating the liquid fraction to form a liquid product having a low moisture content.

The apparatus of the invention may also comprise a pressure relieving vessel mounted in a conduit connecting the hydrolyzer with the means for separating the hydrolyzate into a liquid fraction and a solids fraction.

The means for establishing a superatmospheric pressure in the hydrolyzer may comprise a cone mounted at the location where the mixture of the starting material and acid is introduced into the hydrolyzer under pressure.

The mixer preferably consists of a trough having mounted therein two parallel shafts provided with propeller-like blades capable of simultaneously mix ing the beet material with the acid and advancing the mixture from one end of the trough towards the opposite end.

The invention will be further described, by way of example only, with reference to the accompanying drawing, which schematically illustrates an apparatus for carrying out the method of the invention.

The apparatus illustrated comprises a mixer 1 which may be of a type comprising a trough having mounted therein two horizontal rotatable shafts having blades which are capable of mixing beet pulp and acid, such as sulfuric acid, phosphoric acid or hydrochloric acid, and of moving the mixture from one end of the trough towards the opposite end.

Beet pulp having a dry matter content of for example 12-16% and heated diluted sulfuric acid are introduced into the trough 1 at the end thereof through supply means 2 and 3, respectively. The impregnated material is passed into a hydrolyzer 5 by means of a screw conveyor 4. The material is pressed against a cone 6 mounted in the hydrolyzer 5, the cone exerting a counter pressure which is slightly higher than the superatmosphoric pressure which is to be established in the hydrolyzer 5. The hydrolysis is preferably effected at a superatmospheric pressure of up to 810 kPa and for a period of 10 minutes when the pressure is high and for a longer period at a lower pressure. The mixture contained in the hydrolyzer 5 is heated by injecting steam through steam injection pipes 7.

Via a suitable valve 8, e.g. a rotatable ball valve of the type used in the cellulose industry, the hydrolyzed material is passed into a pressure relieving vessel 9 in which the pressure is reduced to atmospheric pressure under generation of steam which is discharged through a pipe 10 and which optionally is utilized elsewhere in the apparatus described.

The pressure relieved hydrolyzed material is pumped from the pressure relieving vessel 9 through a conduit 11 and onto a filter 12, e.g. a band filter, on which the hydrolyzed product is filtered to form a solids fraction and a liquid fraction.

The liquid fraction istranferred to a neutralizing vessel 14 through a conduit 13. A base, e.g. a CaCO3 solution, lime, a Na2CO3 solution or a NH3 solution, is introduced into the neutralizing vessel 14 through a conduit 15. After being neutralized to a pH value of about 6, the liquid material is passed through a conduit 16 to a filter 17 on which solids are removed.

Subsequently, the neutralized filtered hydrolyzate is passed through a conduit 18 to a multistage evaporator 19 in which the hydrolyzate is evaporated to increase the dry matter content to about 60%. The liquid product thus obtained is discharged through a conduit 20 and is useful as a ruminant feed to replace molasses obtained in the production of sugar from sugar beets or sugar cane.

The solids fraction ordinarily contains more than 30% organic solids and is suitable for use as a starting material in the following two processes. Thus, the extracted material may be neutralized and dried like non-treated beet pulp. However, the energy required per kg of dried product is much lower than in a method in which non-treated pulp is dried because of the considerably increased dry matter content. Alternatively, the solids fraction may be heated to a high temperature, i.e. of between 200 and 250"C.

The acid still present in the compressed material will cause the cellulose of the treated beet material to be converted into glucose. The glucose thus obtained can be converted into ethanol by fermentation and the ethanol produced may be recovered in pure form by distil;ation.

The invention will be further illustrated in the following example: Example Extracted beet slices having a organic dry matter content of 15% and a temperature of 65"C were introduced into a mixer at a rate of 80 kg per hour. A sulfuric acid solution of a concentration of 25% (w/w) and a temperature of 90 C was introduced into the mixer at a rate of 3.55 kg per hour. The two materials were intimately mixed and the mixture was then introduced into a thermally insulated hydrolyzer in which the mixture was heated to 131"C and was maintained at this temperature for 30 min.The mixture thus treated was continuously passed into a pressure relieving vessel in which the temperature was reduced about 10000. The hydrolyzed mass was then introduced onto a band filter at a rate of about 92 kg per hour to remove the liquid portion of the mass. The solids fraction obtained from 92 kg of the hydrolyzed mass was about 17.6 kg having a dry matter content of about 32%. The separated liquid material together with wash water amounted to about 90 kg containing about 6.3 kg dissolved organic material. This liquid was neutralized, filtered and evaporated. The liquid product thus obtained typically has the following data: Dry matter content, % 57.6 Ash at 550"C, % 13.0 Ash at 1050 C, % 11.8 Reducing sugars (miller) %1100 dry substance 20.5 Uronic acids and pentoses, determined by conversion into furfural, O/o/100 dry substance about 50 Hexoses (determined enzymatically) O/o/100 dry substance about 2.5 Acetic acid (determined enzymatically) %/100 dry substance 0.8 Formic acid (determined enzymatically) %/100 dry substance 0.03

Claims

1. A method of making an animal feed from a beet material, comprising subjecting the beet material to acid hydrolysis at an elevated temperature and an elevated pressure, and separating the hydrolyzed product into a liquid fraction which is subsequently neutralized and evaporated to form an animal feed having a low moisture content, and a solids fraction.

2. A method as claimed in Claim 1, wherein the acid hydrolysis is effected at a temperature of from 100"to165"C.

3. A method as claimed in Claim 1 or 2, wherein the acid hydrolysis is effected at a pressure of from 100 to 920 kPa.

4. A method as claimed in any of Claims 1 to 3, wherein the beet material is impregnated with acid at room temperature and atmospheric pressure.

5. A method as claimed in any of Claims 1 to 4, wherein the separation of the hydrolyzed product into a solids fraction and a liquid fraction is effected by filtration on a band filter.

6. A method as claimed in any of Claims 1 to 5, wherein the starting material used is extracted sugar beet slices andlor sugar beet peels.

7. A method according to Claim 1 of making an animal feed from a beet material, substantially as herein described with reference to the accompanying drawing.

8. Apparatus for making an animal feed from a beet material, comprising a mixer for providing a mixture of beet material and acid; a hydrolyzer which is connected to the mixer and which includes means for establishing a superatmospheric pressure within the hydrolyzer, means for heating the contents of the hydrolyzer and means for discharging treated material from the hydrolyzer; means for separating the hydrolyzed product into a liquid fraction and a solids fraction; and means for neutralizing and evaporating the liquid fraction to form a liquid product having a low moisture content.

9. Apparatus as claimed in Claim 8, further comprising a pressure relieving vessel mounted in a conduit connecting the hydrolyzer with the means for separating the hydrolyzed product into a liquid fraction and a solids fraction.

10. Apparatus as claimed in Claim 8 or 9, wherein the means for establishing a superatmospheric pressure in the hydrolyzer comprises a cone mounted at the location where the mixture of beet material and acid is introduced into the hydrolyzer.

11. Apparatus as claimed in any of Claims 8 to 10, wherein the mixer comprises a trough having mounted therein two parallel rotatable shafts provided with propeller-like blades capable of simultaneously mixing the beet material with the acid and advancing the mixture from one end of the trough towards the opposite end.

12. Apparatus according to Claim 8 for making an animal feed from a beet material, substantially as herein described with reference to, and as shown in, the accompanying drawing.