CA1191378A - Method of processing cattle feed products and a plant for performing the method - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A method of processing cattle feed products based on agricultural material, such as sugar best pulp, citrus fruit pulp and peel, and material obtained in the fermentation of agricultural material, such as distiller's grain, which material is available after either a fermentation process or sugar leaching of beet pulp or after mechanical dewatering (pressing) or evaporation.
To improve the nutrient value and general quality of the cattle feed product while at the same time improving the heat economy of the production process the invention proposes a method comprising the steps of preheating the material in steam, known as carrier steam, disintegrating the material in said steam for fragmentation thereof into uniform particle size, and drying the material particles in heat exchangers. Preferably the carrier steam is a part of the drying medium used in the process, that is for heating and conveyance of the particles.
The cattle feed processing steps may be performed in the order indicated or processed in any other suitable order.
The cattle feed product/material is then seperated from the carrier steam and cooled.
The plant designed to perform the method includes a pressure vessel to which moist cattle-feed material is transported via a pressure lock, equipment for disintegration of the material to equalize the paritcle size, equiptment for drying the maaterial and a pressure lock to discharge and separate the material from the carrier steam.

Description

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~ACKGROUND OF THE INVENTION
The subject invention concerns a method of processing cattle-feed products which ara based on agricultural materi~lR such as suger pulp, citrus pulp and psel, or on material obtained in th~ fermentation of agricultural products such as d$etiller ' 8 grain~
from e,g. corn, wheat and barley.
In the production of natural sugar ~cane RU9ar9sa charoses) from sugar beet and cane the fibre material is used for various purpose~ after removal of the sugar juice through leachlng. ~eet pulp whirh is obtained from sugar beat may be used without further as cattlfl feed.
To facilitate transport and storags of beet pulp larg0 amounts are driad and somstimes formed into pellets.
Prior to drying the beet pulp is usually enriched with molasses, which is a by-product obtained in the production of sugar syrup, The product obtained in this process i9 a very val~able, highly nourishing cattle feed which is rich in fibres, Aftar removal of the beet tops and washing of the beet roots, the bset ronts are cut into small pieces by specially dQ~igned cutters to form a pulp. Diffusers are used to leach the sugar frnm th~ pulp with the aid of water, usually in counter-current flow. The sugar 0xtracted from the beet pulp is obtained as crude juice ,~

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which may b~ further refined, and th~ beet pulp is then dewatercd in a prsssing operation in s~g, cone pr0sses or screw-spindle pressQs. To produce cattle fe~d, tha pulp is normally dewatsred from appr. 5~
dry contents to dry contents of between 15 and 25~, The water sxtracted in the pr~ssing oporati~n is used in the leaching process which is carried out in diffusers, as mentioned above.
When beet pulp i8 enriched with molass~s tha molasses is added after the pressing procedure but prior to drying the pulp. Molas~es which contains approximately 20% of water and the beet pulp are mixsd in proportions ensuring that the dry solids content will be in the range of between ~0 and 40%, usually about 35~o, This means that approximately 30~ of the dry matter is sugar Tha subsequent drying is carried out in hot gas, usually flue gas which is ganerated in the burning of oil or gas, Flue gas and beet pulp are brought into contact, ganerally in a rotating drum dryer but also drying in stream dryers, so callad pneumatic drying in flue gas) is possible.
Modern ~lue gas dryers consume about 100 li-ters of fuel oil for each ton of evaporated water, that is, fuel oil in amounts varying between 150 and 2ûO liters '7&~

per ton product, depending on the water contents of the beet pulp at the beginning of the drying procsss, In addition, soma smaller amounts of oil are used per ton of product to ganerqte the steam required for pre -heating and atomiziny the fuel oil, as well as about 100 kWh par ton product in elactric snergy~
The residence time in rotary dryers is nDrmally at least 30 minutes, The t0mperature of the gas at ths onset of the drying procedure mey ba 9~9J 580C but 110C at drysr outlet, If gas i3 recirculated in order to maintain a wst bulb temperatura af 70C the average operative t~mperature differsnce is appr, 185C. The elevated temperature is nscessary to remous (evaporate) the moisture from the hygroscopic material in 30 minutes, Th~ total area of the particlas that is ~xposed to the effects of the drying in rotary dryers is very ~mall, since most of the time tha material is at the hottom of the rotating drum~
The data given above show that it is very expensive to produce cattle fecd with prior-art methods, Howev~r, not only the high manufacturing price of such cattle fesd products is a disadvantage but also in other respects the manuf`acturing technique used today suffers from serious drawbacks, For instance~ flue gas drying takes place at el~vated tempQratures, ganerally bstwaen 400 and 600C but of`ten as high as 1000C, When be0t pulp :~L9~3'~

is exposed to the efFects o~ diract contact with such very hot gases the smallest particlas in the pulp dry very quickly, oxidize and burn, In this way some 5 to 10~ of the dry solide content of the product is lost.
In addition, ths charred remnants in the beet pulp give the product a bad flavour and a dark colour whlch reduc~s the quality of the product.
It has recently been reportad in litarature (for instance "Oritish Sugar Conference" June 19BO) that harmful chemicals may be found in c~ttle fe~d that has been dried by means of f lu9 gases obtained ~rom the co~bustion of oil or gas.
When oil or flue gas iY used, ccmbustion products, such as soot and ashes but also unburned hydrocarbons ara absorbed in the cattle feed.
Owing to the presence in tha beet pulp of partlcles of vsry varying sizes there is a mark0d risk that the larger particles will not dry to the desired extent. Tha prssence of such not sufficiently dry particles reduces the shelf life of the cattle feed and makes it nacessary to control the flue-gas drying process cars-fully in order that it be possible to obtain a high and even leval of dryness. If the level of dryness is too low mildew and moulding may form and the product must be discarded.

3'713 Because of the drawbacks uutlined above sugar~
-beet pulp, for in~tance, has up to now only becn used as cattle feed despite the high nutritious value and the high fibre content of this matsrial.
Owing to ths method in acccrdance with the invention the drQwbacks outlined aboue and lnherent in ths techniques hitherto used to process e.g. beet pulp and similar agricultural material into an edible product, have been eliminated. In addition, the method in accordance with the invantion uses considerably lass energy to dry the beet pulpu SUMMARY OF THE INVENTION
The method in accordance with the invention is characteri-~ed in that the agricultural materi~l to be procsssed into cattle fèed, such as sugar-beet pulp, .. .
citrus pulp and peel, or agricultural material obtained in the fermentation of agricultural products, such as distiller's grain9 after having baen dewatered in a pressing and/or svaporation process, is subjecte~ to the processing steps consisting of heating the material in water vapour, known as carrier steam, disintegrating the material in said carrier steam to obtain an approximately uniform particle size throughout of all solid matter incorporated in said material, drying said particles in a heat axchanger wherein said carrier steam prefcrably servas as a contributory drying medium, said processing .11~13~lB

steps being carried out in th0 ssquence indicat~d or in any othsr suitabls segwence, saparating said material from the carrier steam and cooling said material.
The invention likewise concerns a plant design~d for performing the method. The plant i~ primarily charact-erised by a vesssl containing pressurized steam to which the material is tran~ported via a fir~t pressurs lock, disintegrating means to impart to a ? 1 particl0S
incorporated in tha beet pulp an approximately uniform size, equipment for drying the material and means for conveying the material through ~aid drying equipment and fer separating said material from steam which ser~es as a material carriar medium, and a second pressure lock for discharging said material to the atmosphere, 15 BRIEF DESCRIPTION OF THE C~RAWINGS
The inuention wlll be dascribed in closar detail in the following with reference to ths accompanying drawings showing eome embodiments of a plant ussd to process cattle feed matsrial in accordance with the 9ubject invention. In the drawings Fig. 1 i9 a schematical view of a first embodiment of 3 plant in accordance with the invsntion for processing sugar bset pulp, Fig, 2 is a graph, showing beet pulp drying timB
with and without expansion of the material, 3'~1~

Fig 3 is a schemntical Vi8W of a second arnbodiMent of a plant in accordance with the invention used for processing beet pulp to which mol~sses has not been added, Fig 4 shows schematically processing of peel and pulp from citrus fruit~, and Fig 5 shows a third smbodiment oF a plant in accordance with the invention for processing distiller' 9 grain.
DETAILED DESCRIPTION OF PREFERRED EM~ODIMENTS
The invention will be de~cribed in the Following with reference initially to Fig 1 which shows a plant for processing beet pulpo From a leaching plant tnot shown) where sugar is extracted, beet pulp 1 is transported by a feed screw 2 to an intermediate storage 3 to be further processed. While the pulp is being conveyed in the fsed screw 2 molasses is proferably addad thereto, to be homogeneously mixed with the beet pulp 1 t From the intermediate storage 3 beet pulp 1 is collveyed continuously by a second feed screw 4 into a steam pressure vessel 5 which is filled with water vapour.
The vapour is pressurized, preferably at 0 6 MPa, The steam pressurs ls generatsd by a stsam ejector 6 which with the aid of high-pressure steam in a proportion of 30~o and at a pressure of 2 MPa compresses steam in a proportion of 70~ and at a pressure of 0.4 MPa into a 3'~

pressure nf 0.6 MPa, In the pressure vessel 5, the water vapour condenses on the best pulp, hea-ting it rapidly ta s~turation temperaturQ, about 150C.
The beet pulp ls thereafter convsyed to a chamber 7 which is pressurized to a lower pr~ssure (U.4 MPa) than the steam vsssel 5, ~s~era entering ths chamber 7 the pulp has to pass through a rotary ~ana f~eder ~ which serves as a pres~ure look~ The material expands as a result of ths prassur~ reduction and the liquid-fillod lD cells of the material bur$t, giving tho material a fluffinr structure which facilit~tes the ensu-ing drying, In addition, it'saasior to dig~st by cattle.
From the chamber 7 a screw feedsr 9 conveys tha beet pulp to a defib~ator 10 which in the em~iment shown is a disc refiner, although other types of def~ibrators may be used, such as disc crushers, attrition mills or defri-brators. The dafibrator 10 operates at an e~fsctivn di c cl~arance of betwean 0.5 and 1,0 millimeter Th~ material is blown out of the refiner hou~ing and into the subsequent dryer 11 by means of carrier steam at a pressure of û.4 MPa.
Th~ sxpansion as well as the mechanical disintegration in ths refiner or d~fibrator 10 results in fragmentatien of the material with a view to produce particles a~ as far as possible uniform size, which makes it possible to reduce the length of the ensuing drying process considerably~
rhe dryer 11 iR a so called counter-pressure dryer or stsam dryer and consists of heat exchangers and transport Ll9~

pipes interconnectsd by pipa bends. This typa o~ dryer i5 describ~d in US 4 043 049 and i~ used to dry callulose Fibres, usually from a 50~ solids content to approximate 90~ solids con~tant. From the plant turbine 12 (or steam boiler) steam is supplied to the dryar at a prassure of between 1 and 1.2 MPa. The heating ste~m condensas and the condensate is collected from ths heat axchangers and carried to the feed-water Rystem to prehaat the fresh feed water~ Tho heating ~team may alsu b~ a mixture of the staam from tha turbine (boiler) and of the carri~r stcam mentioned prsviously which mixture i8 obtain~d e.g, from mechanical comprQssion operatlons Sth~rmo_compression or uapour comprassion) or e.g. from a steam ejector. The haating steam may also be carrier steam alone, which is generated in ths drying process and is subsequently compressad in a compressor, Heat may also he addad in other media than water vapour at a higher pressure than the carrier steam. For instance hot oil Dowtherm ~ may be used, which is made to condense or i9 cooled in the heat axchangers of the dryer 11.
The beet pulp is mixed with carrier steam, preferably in proportions by weight of between 1:2 and 1:1û The suspensinn consisting of beet pulp, particle~ and car~ier steam~ is tran portad through the dryar 11 Wi ttl the aid of fans 12, 13 at a velocity of 20-30 In/s lnitially and 3'~

of 40 m/s towards the snd ~ As th~ wat~r is evapDratsd from the beet pulp tha amount/proportion of steam in ths susperlsion increases. ~ecause the beet pulp is dried in super heatod carrier ~team, a surplus of carrier steam is formed as well as dried beet pulp, that is, cattle feed3 when water i~ evaporated from the beet pulp.
rhis surplus of carrier steam may, as described above, be used as h~ating dryer steam after comprassion, However~
it is preferable to use it a~ processing steam in th0 plant, for instance to avaporate the sugar juice (S08 Fig, 1), the so called light juice, in a multiple-effact evaporation plan~ The surplus steam thus generat~d may bs osed oithar directly or after rsgeneration in a staam genarator. In th~ latter, pure condensate deri~ed from thu heat sxchangers of ths dryer plant 11 or from the feed water system is heat~exchanged with surplus steam. The staam is condensed and transfers its heat in the steam generator to ~he water which ~nrms staam, In this manner, pure procassing stsam is formed which may be carried to the low-pressure steam system of the plant (usually 0~2 to 0,5 MPa).
In many cases it i5 sufficient9 howe~er, to purify tha steam by filtration, or better still, by so called scrubbing with the aid of saturated condensates~ Steam is thsn allowed to bubble through a pressurized container which is Filled with a condensate in which particles from the steam become suspended and gaseous chemicals abso~hsd.

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An ana:Lysis of the carrier steam aFter and before purification with condensate is given in the table balow:
Quality of Steam after Dryinq Suqar aeet Pulp containinq Mola6ses solids pH alcohols acids mg/l value mg/l m3/l Unpurlfied steam 40 4,5 650 275 Purified steam ~fter scrubbing with alcaline condensate None 7.3 625 20 Owing to ths method described abova stea~
gsnara-ted in the drying process may be used for evaporation without new equipment (such as stainless-steel euaporators) having to be installed, Instead; the existing carbon--steal equipment may be usad.
A~ter dryingJ which usually take~ place at a pres~ure of between 0 2 and 0,6 MPa, the beet pulp is s~parated from the carrisr steam in a cyclona 14. Driad beet pulp, i.e. the cattla feed, is dischargad by a rotary valve feeder 15 into a strsam of cold air at atmospheric pressure~ In this process the material obtains the desired final dry contants, usually between ao and 95~; and air cools the cattle feed while the latter is being transported to be palletsd and/or packaged.

The separated carrier steam is returned to the defibrator 10 through a recirculation pipe 16. The fans 12 and 13 supply the energy necessary to maks up for the pressure 10~8 during transport, 3'7~

A bleeder pipe 17 is connectsd to the recirculation pipe 16~ A pressure control valve 18 in the pipe 17, which valve is set for a pressurQ of ~ 4 MPa is used to bleed off surplus carrier staam to replace a part of the fresh steam used to evaporate the sugar jUiC3 9 in the present case 457t of that steam.
The method in accordance with the invention provides considerable advantages over the conventional technique For instan~e, non-desired changes of flavour which wera earlier caused by charred be0t pulp and burning fuel oil ara eliminated. In addition, it has been found that the bitt~r flavours existing naturally in sugar be~t root disappear compl2tely, probably through thermal disintagration and/or in the dQstillation of tha water in/
vapourO In ths processing method accordance with the invention ths baet pulp is al~o disinfected, which facilitates storaga and handling uf the product, It has also been found that the digestibility, that iS7 the panetration ~by gastric juires and substances incorporated therein, is highly improved in beet pulp processed in accordance with the mathad of the subject invantion as compared with that found in beet pulp dried with flue gas Ths wetting and swelling properties of tha product are also improued. Samples of the vapour-dried product in accordance with the invention swell when submerged in water, considerably more rapidly and absorb largar quantities of watsr than doas flue-gas dried beet pulp.

In fact, the swHlling proper-ties are improved by about 100 percent as compared with the prior-art product.
The surprlsing improvements in quality thus obtainHd in cattl~-f~ed proouct~ processed as described herein make the end product in accordance with the invention suitable alsu as foodstuff for human comsumption.
The food product may consist of the purified and dried fibra productO Additions may be made, both before and after drying, Preferably b0et pulp without molassas is used when producing food for human consumptian~
Preferably the entire processing method described is carrled out in water vapour pressurized to a saturation temperature of betwesn 105C and 180C, that is, an excess pressure of between 20 and 90û kPa.
The disintegration step may, however, bs carried out at atmospharic pressure in air or othar media, The expansion may bs carried oùt in steam at a lower prsssure or to air at ~tmospheric pressura, As described in the afore-going9 molasses is preferably 2dded after tha conventional dewataring of the beet pulp but it should be obvious that the method in accordance with the invention is equally applicable to beet pulp processing without such addition of molasses.
It is, however, necassary to modify the various processing steps somewhat because of the lesser dry cnntents of the beet pulp as compared with thH dry contents of molassesO

3~8 During the drying proc~dure and ths subsequent discharge of the beat pulp, some further disintegration takas place in the dryer 11 as a result of the high flow v~lccities and the impact from sudden uelocity changss and in tha pulp di~charg0 procedure as a result of the expansion from a higher to a lowor pressure, This di~integration must be considered in the overall plcnning of the procc~s to en~ure that the end product meat3 the desired demandsun e~g. quali~y.
One has Found that in tha drying operation nat only wat~r but also subatances pressnt in sugar beet that earlier gavs a charactaristic bitter taste to ths ~eed productt are avaporated. Some such substances ara thermally decomposed.
Compared with single-step procedures using flue--gas drying ths proposed new method is considerably more efficient9 particularly for agricultural materials~
such as sugar beet pulp and peel and pulp from citrus fruits. In ~uch materials, water is retainad in the cells and is alRo hound hygroscopically to carbohydrates~
pectins and proteins~
As mentioned previously, in rotary dryers a residence time o~ 30 minutes or more is necessary when flue-gases are used for drying. The average temperature difference is 1a5C. In a steam atmosphere~ on the other hand, the total residence time including prehearing, disintegration, drying and separation, is about 50 seconds 3'7~

and the a\/erage temperrture dif~erence is 30C, Th~ differ~nce in he~t tranRfer ratas (efficiency) mey be expressed by the following relatinn:
TimH x ternperature dif~e~ence in Fluu-qa~ dryln~_ 30 x 60 x 1~5 = 222 Time x t0mpe~aturs difference 50 x 30 in steam pr~ce~3einq i.e. heat is transferred about 200 times more efficiently when ~tsam ie uscd.
The method according to the invontion also gives valuable gains rogarding energy consumption, The examples below show tha various valuss of pressures, temperatures and othsr data of the ~ystems of tha plant in accordance with thn invention.
Cattle Feed, Dry Substance 1û tons/h Water Contents bafore Processing 65~;1.C6 kg - water/kg dry substance Temperature before Processing 60C
Temperature Staga No, 1 150C, D.5 MPa 2û Water Contents Stagn No~ 1 70%;2.30 kg water/kg dry substance T~mperature aftsr Refiner 134C
Water Contents after Refiner 64~o;1 .7B kg water/kg dry substance Refinirlg Enargy sdded 350 kW
~leating steam added 21.5 tons/h, 1 MPa Steam added to Ejactor 1.4 tons/h9 Steam added to Ejector 3,~ ~ons/h ~ 15 _ 4 MPa 3'78 Produced Prooessing Steam to Evaporation 1B.5 tons/h Lost Processing Steam 1,5 tons/h to atmosphere 5 Fan Energy addsd 290 kW
Moieture Carltsnt in Final Product 10~9 0,11 kg water/kg dry substance Tntal D0mand of Steam in 10 Evaporation 55 tons/h Demand of Fresh Steam from Coiler 36.5 tons/h Steam from ~rying o~ Oe0t Fodder 18,5 tons/h A comparison of the energy requirements of the new method of conventional methods gives the following values:
Dryinq: Naw Method Conventional Method Steam Demand 1 MPa21~5 tons/h Steam Damand 2 MPa1.4 tons/h Steam Demand 0.4 MPa - 1.0 tons/h Overall Electricity added 640 kW ~30 kW
25 Fuel Oil - 1800 litres/h Evaporation:
Steam Demand 0,4 MPa 36~5 tons/h 55 tons/h ~L~Lt3 ENERGY CONSUMPTION:
Convention~l Dryinq: New method method MJ/ton dry MJ/ton dry Sub. Sub, Steam Demand 1 MPa (2015 M;l/ton)4332

2 MPa 5(2800 MQ/ton) 392 0.4 MPa (2739 MJ/ton) - 274 Flectricity (0,36 M~/ton dry sub,) 230 263 Fuel Oil (36 MJ/l fuel oil) - 6480 10 Evaporation:

Steam Demand 0,4 MPa (2134 MJ/ton)7789 11737 Total MJ/ton dry substancE3 12743 18754 Savinqs: 6011 M~/ton dry substance 167 l fuel oil/ton dry substance or 1670 l fuel oil/h Fig, 2 shows a graph plotting the drying time of beet pulp ~fter n)~pqnsic~n verus drying time without such expansionO
A second embodim~nt of ths invention will now 2Q be described with reference to Fig, 3, According to this embodiment beet pulp having no additic~n thereto of molasses and without having been previously ground or expandad is dried in a two-stage operation.
The first drying stage 19 operates with heating 25 steam at a pressure of 1.2 MPa and with carrier steam at -- 17 ~

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a prsssure of 0,5 MPa, Beet pulp is introducad into the drying ~tage via ~ rotary vans feeder 20 and tha moi~ture content3 are reduced in this stage from 78~ to 65%, The matarial is then passed through a rotary valve fseder 21, wherein it expands when subjected to a prsssure of 0,2 MPa, and is thereafter ground in a disc rafiner 22, It is thereafter dried to a moistura contant oF 10~ in a second drysr stage 23 at a prassure of 0,2 MPa~ Steam produced at a pressure of 0,5 MPa ~0rves as the haating steam, In the drying operation a balance is maintainad between the two stages 19 and 23 to ensure that just ~nough steam at 0,5 MPa is consumed to dry the best ,oulp to the desirad dry contents. Particular care should be taken to optimi~e separately ths amount of carrisr steam from the first stage 19 to the second staga 23.
In the first dryer stage 19 weight ratios betwesn beet pulp and carrier staam are 1:5 and the averaga Flow valocity approximately 30 m/s, In the second dryer etage 23 the Gorresponding weight ratio is 1:3 and the avarage flow velocity 20 m/s, It should be avidant that tha space requirements for the plant and tha electricity consumption of the fans of the systams thereforc may be reducsd considerably, Should it be nacessary to increase temporarily the capacity of the second drying stage 23, this may be dona by increasing the amount of steam to a staam ejactor 24 ~9~3'7~ , which is connected to this dryar ~tage. As a result, the pressur~ of ths heating steam in the socond ~rying stag~ rises, After drying in the second drysr stage 23 th0 bcet pulp i~ sxpandsd via a rotary ualve f0eder 25 to the atmosphare, According to a thlrd embodiment of th~ method accordin~ to the invention hot oil may be ussd as the heating medium instead of steam~to dry the cattle feed.
The so called Dowtherm medium or equivalent media may be used. This medium i5 heated with or without euaporation to elevated temperatures in a boller which in turn may be heated elsctrically or by any convenient fuel, The advantags of this procedure i8 that high temperatures may be obtained without high pressure being required.
The hot oil is supplied to the heat exchangers of tha dryer plant. In this case only gsnerated steam may be used to process tha material. It i8 not possible to re-use thi~ steam for drying purposes by mean~ of pressing (machanically or with the aid of steam ejectors).
Instead, it may be used to pre-procQss the matsrial and/or for evaporation.
The inuention is not limited to the embodiments described and illustratad but may be modified in various ways within the scope of the appended claims, For instancs, _ 19 -37~

th0 disintagratlon as well as the sxpansion and dryingmay be carried out in savaral stages in different arrangements qnd sequences, In ord0r to prolonge the yearly running tim0 5 of plants - today it extends only over a few months -sugar beet pulp may b0 dried before leaching, and be stor0d and used to produce sugar, Partial leaching before drying may also be used, ~y treating and drying in a steam armosphere 10 high material quality is maintainad and the dried pulp remains hydrophilic, that is~ it is aasy to rewet and use in the leaching process, The method in accordancs with tha invention i8 also applicabla to other industrial procasses that are 15 similar to sugar refining processes, Ons such procass is juice production where juice is produced from citrus fruits, such a~ ~ranges, lemons, tangerines and grape fruit, The fruit is washed and the juice is pressed and saparated from the fruit pulp before being concentrated 20 in a multiple-effect ~vaporatin~ process~ The peel and the pulp materi~l is dried into cattle fe3d together with molasses which is pressed from ths peel and pulp9 iS
concentrated with the aid of another multiple-effect evaporator before it is mixed with the pressed peel and 25 pulp before drying, Lime may be added to increase dewatera-bility in the presses, Moist flue gases from rotary dryer~

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ars used today to heat the molasses svaporator~ Expensive citrus oils such as D-limorlene rnay be recovered from both the juica and molasses suaporators.
Fig, 4 shows the method according to the invention as applied in a process of drying citrus peel and pulp into a cattle faed product.
The product obtained whan using the method in accordance with the inventiun is improved as to quality compared with similar products hitharto obtained in convantional processas, in addition to which it is produced in a more economical manner, 5urprisingly enough, 50 to 70~ more citrus oil can be recov0rad from the molasses evaporator and the steam reboiler.
Also distiller's grain may be used to produce cattla feed in accordancc with the method of the subject invention. Fig. 5 shows a plant designed for this purpose.
To dry distiller's grain originating from batch or continuous fermentation the feed/material initially has to be mechanically dewatered and/or concentrated ?0 by evaporation to a maximum dry content of 20 to 30 solids, ay recycling the dried product, the sludgy material obtained in the fermentation process may be granulated, rha granulated faed is preheated by direct condensation of generated carrier steam in heater 26.
After having been fed to a pressure value 27, the granu-lated material is further preheated in a pr0ssurized steam heater 28 and disintegrated by hiyh-velocity steam 3'~

jets ej~cted from a nozzla 29. The pressure reductior f.rom tlla inlet to the nozzle is batween 0.01 and 0,1 MPa ~n ordsr to reducn ovHr-~lzed granules.
Tha thus disintegrated grain granul0s are dried in ,the same carrier ~team ~8 i3 used for the disintagration by being pass~d through 6team-he~tad tubular heat exchangers 3D.
rhe drl~d product is separated from the stenm in ~ ~eparator 31 and dischargHd by a valve 32 and thareafter cooled, stored ~nd packed as c~ttle faed.
Surplu8 of g~nerat~d cnrrier ~team may be u~ed to ferment or di till ethanol that i~ produced in the plant, ~5

Claims (14)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a method of producing cattle feed from agricultural material comprising dewatering the material by applying pressure and applying heat to evaporate water the improvement comprising the steps:
heating the material with carrier steam;
disintegrating the material while it is in the carrier steam to obtain solid material of approximately uniform particle size;
drying the particles in a heat exchanger, using the carrier steam as at least part of the drying medium;
separating the particles from the carrier steam;
and cooling the particles.

2. A method as claimed in claim 1 in which the heating is carried out in at least two steps, separated by the disintegration.

3. A method as claimed in claim 1 in which the disintegration is achieved by a mechanically breaking agri-cultural material.

4. A method as claimed in claim 1 in which the disintegration is achieved by reducing the pressure of the steam, causing the particles to burst.

5. A method as claimed in claim 1 comprising disintegrating the material with a combination of mechani-cal breaking and pressure induction.

6. A method as claimed in claim 1 comprising drying the material in steam and excess pressure, expanding the material and subjecting it to mechanical disin-tegration, subjecting the material so obtained to a second drying operation and then expanding the material to the atmosphere.

7. A method as claimed in claim 1 in which the agricultural material is selected from sugar beet pulp, citrus fruit pulp and peel and material obtained in the fermentation of agricultural materials.

8. A method as claimed in claim 7 in which the material obtained in the fermentation of agricultural material is distillers grain.

9. In a plant for processing cattle feed pro-ducts based on agricultural material, said agricultural material having been cut into chips, leached in water to extract the sugar, and dewatered through pressing, the improvement comprising:
a pressure vessel to contain pressurized steam, a first pressure lock to enable said material to be transported to the pressure vessel via the first pressure lock, disintegrating means, said disintegrating means being adapted to impart to all particles incorporated in said material an approximately uniform size, means for drying said material, means for conveying said material through said drying equipment and for separating said material from said steam, said steam serving as a material carrier medium, and a second pressure lock for discharging said material to the atmosphere.

10. A plant as claimed in claim 9, in which the disintegrating means is a rotary valve feeder, a chamber pressurized to a pressure below that of said pressure vessel, said rotary valve feeder conveying said material from said pressure vessel to said chamber to cause expan-sion, and possibly bursting, of the particles of said material.

11. A plant as claimed in claim 9, wherein said disintegrating means is a defibrator, said defibrator being arranged to disintegrate said material mechanically.

12. A plant as claimed in claim 9, wherein said disintegration means is a steam, said steam jet causing said carrier steam to accelerate as a result of a sudden pressure drop of between 0.01 and 0.3 MPa.

13. A plant as claimed in claim 9, wherein said pressure vessel serves as a dryer.

14. A plant as claimed in claim 9, wherein said equipment for conveying said material to the atmosphere consists of a cyclone and a rotary valve feeder