GB2068519A - Method and equipment for treating chopped crops - Google Patents

Abstract

In the treatment of chopped crops containing a mixture of grains or other seed, such as peas, beans, etc., and other plant components, the goods are introduced into a separating section (7) through which air flows, in a rotating drum, the temperature of the air entering a preliminary drier (6) being regulated (47... 50) so that the superficial moisture of the goods is mainly removed before the goods are introduced into the separating section, as a result of which the grains can be removed without being damaged by prolonged overheating. The preliminary drier and the separating section consists of an integrated, rotating drum. Round the shell of the drum there are discharge openings (33) for the grains, and in the separating section there are members (80) (Figs. 3, 4) for feeding the grains back towards the grain discharge openings to the extent that they have passed the openings (33) without being discharged. Alternatively a plurality of openings around the drum may be replaced by one continuous opening around the drum. Furthermore there are entrainment means for lifting up straw particles in the drum so that the separating work is facilitated. In the front end of the drum there is a discharge opening (83) for the straw particles. <IMAGE>

Description

SPECIFICATION Method and equipment for treating chopped crops The invention relates to a method of treating chopped crops containing a mixture of grain or other seed and lighter plant components. The invention likewise relates to apparatus for drying, threshing and separating chopped crops, comprising a rotatable drum with a primary drying section and a separating section with a discharge opening for the lighter components of the threshed crops in the remote end of the separating section, and means for blowing, drying and conveying air through the primary drying and separating sections.

In SE 408 122 an installation for treating chopped crops is described. The installation comprises a drying device consisting of a rotating hot-air drier of the through-flow type for continuous drying of the chopped crops and a conveyor device disposed at the discharge end of the drying device to feed the dried crops to a separating device which comprises a throwing apparatus and a separator housing. The walls and bottom of the separator housing form a plurality of funnel-shaped collecting shafts, separated from one another, in the lower portion of the housing, situated at different distances from the throwing apparatus in the direction of throwing and provided with devices for feeding the material separated into different fractions to one or more devices for further treatment and taking care of the fractions.

The latter devices consist of storage silos, preparation devices for producing fodder mixtures and compressing devices for producing cakes, pellets or the like.

The object of this known installation is to be able to preserve the large amounts of vaulable components included in the crops, which are wasted by conventional harvesting methods, such as the straw, for example, which today is often ploughed in or burnt and which contains both parts which are rich in cellulose and parts which are rich in protein. The part rich in cellulose consist primarily of straw and stalk portions while the parts rich in protein consist primarily of husks, leaves and parts of grains. The latter part is often called chaff.

A disadvantage of the known methods, however, is that the drying in the drying devices must be continued as long as is necessary for the parts which are most difficult to dry. This consists primarily of the straw fraction. But in order that the straw fraction may be sufficiently dried, it is difficult to avoid damaging the valuable grains at the same time. When drying in the known installations, therefore, there is a great risk that the grains may be damaged, particularly if the crop has a high moisture content. This is a very serious disadvantage of the known installation. Another disadvantage is that the installation has a high energy consumption.

One object of the invention is to provide a method and apparatus for drying, threshing and separating a crop which contains components of different kinds in such a manner that none of the components is damaged but on the contrary can be utilized in the most suitable manner. More specifically, it is an object to be able to dry and separate chopped crops which contain valuable grains such as chopped corn, or other seeds such as peas and beans substantially without the grains of other seeds being damaged during the drying regardless of the moisture content of the crop.

Accordingly one aspect of the present invention provides a method of treating chopped crops containing on the one hand grains or other seed, and on the other hand other plant constituents, wherein the chopped crops are introduced into a separating section of a rotating drum through which air flows, and the temperature of the air entering the separating section is regulated so that the grains or other seed can be separated without being damaged by prolonged overheating.

Another aspect of the invention provides apparatus for treating chopped crops, comprising a rotatable drum having a separating section with a discharge opening for the lighter components of the threshed crops in one end of the separating section; means for blowing air through the separating section; and, in the separating section of the drum: entrainment means fixed to the inside of the drum and adapted to lift up the crop when the drum is rotated and to release the goods again afterwards into a stream of air passing through the drum in use of the apparatus; a grain discharge opening encircling the drum or a plurality of grain discharge openings distributed round the drum; and oblique conveying members fixed to the inside of the drum and adapted, on rotation of the drum, to convey goods towards said grain discharge opening or openings.

The invention also provides chopped crops treated by the method just described.

These methods and apparatuses can be used to treat crops with a very varying moisture content so that the harvest season can be extended over a considerably longer time than is possible with the conventional harvest methods.

Such a method can be performed so as to be economical as regards energy, more specifically by utilizing the various hot gases which are produced or obtained in the system in an optimum manner in view of what the different plant fractions require with regard to gas purity and drying effect.

The apparatus is one in which different types of crop can if desired, be treated and provides a high degree of utilization for the components of the apparatus and a considerably reduced requirement for special machines for different kinds of crops.

Various aspect of the method and apparatus described hereinafter are also claimed in our British Patent Application No. 80 (Publication No.

In order that the present invention may more readily be understood the following description is given, merely by way of example, with reference to the accompanying drawings in which: Figure 1 constitutes a basic diagram of the equipment according to the invention; Figure 2 shows a side view of a device included in the equipment which consists of an integrated primary drier, threshing mechanism and separating mechanism for chopped cereals, according to a first preferred form of embodiment of the invention: Figure 3 constitutes a section on the line Ill-Ill of Figure 2; Figure 4 constitutes a section on the line IV--IV in Figure 2; and Figure 5 shows diagrammatically the internal parts of an integrated primary drier, threshing mechanism and separating mechanism included in the installation, according to another form of embodiment of the invention.

In all the Figures, the various parts are shown more or less diagrammatically, and certain parts have even been omitted so that what is important for an understanding of the invention may stand out better.

The installation illustrated diagrammatically in Figure 1 comprises three drying devices, namely a device 1 which is an integrated primary drier, threshing mechanism and separating mechanism for chopped cereals, a second drier 2 for straw and chaff and a grain drier 3 for the final drying of the grains which are separated in the first device 1.

The integrated device 1, which will be described in more detail later with reference to Figures 2-4, can be divided into the following main parts, namely a mixing chamber 4 for drying air, a feed pipe 5 for the crop which is chopped but otherwise untreated to a primary drier 6, a separating section 7 which together with the primary drier also forms a threshing mechanism, and an outlet device 8 for grain between the primary drier 6 and the separating section 7. The primary drier 6 and the separating section 7 have the form of a coherent rotatable drum with a horizontal axis of rotation.

A screw conveyor 9 is adapted to feed chopped crops from a container 10 into a feed pipe 5 in the device 1. A belt weighing device is designated 11, a screw conveyor is designated 12 and a lock is designated 13. There is also a member 82 to regulate the feed of the conveyor 9 of goods out of the container 10 depending on the amounts recorded by weight.

Disposed after the drying device is a so-called outlet box 14 which is connected to an opening 83 in the front end of the separating section 7. A suction fan 1 5 and a cyclone separator 16 are connected to the outlet box 14. A conveyor 18 connects the outlet box 1 4 to a feed pipe 1 9 to the secondary drier 2. A lock 20 is disposed between the conveyor 18 and the secondary drier 2. A mixing chamber 21 for drying air is disposed in the front end of the secondary drier 2. The actual drying section in the device 2 has the form of a rotating, horizontal drying drum 22 can be of the known type of through-flow drier for hot air.

Also disposed after the secondary drying drum 22 is an outlet box 23 with a section fan 24 which is adapted, via a heat exchanger 25 and a cyclone separator 26, to separate small amounts of chaff from the conveying air and combustion gases.

Separated chaff is conveyed via a lock 27 to a chaff line BL for the production of fodder cakes or peliets. The cooled waste gases from the cycline separator 26 are drawn off in a chimney, while air heated in the waste-gas heat exchanger 25 is used in the grain drier 3. The main part of the medium-weight parts of the crop which are rich in cellulose, mainly parts of straw collects in the bottom of the separating box 23. A conveyor 28 is adapted to convey this material for further treatment in a straw line HL, where the material is conditioned, for example mixed with liquor and/or molasses for fodder purposes, after which this material is also formed into fodder cakes or pellets.Furthermore, the main part of the chaff is separated in the lower portion 29 of the separating box 23 in a stream of air generated by a fan 30 which conveys separated chaff to a cyclone separator 31, after which the chaff is conveyed to the chaff line BL.

The outlet device 8 for grain is disposed following on a constriction 32 between the primary drier 6 and the separating section 7, grain discharge openings 33 being disposed in the back portion of the separating section 7, distributed round the shell of the rotating drum. The outlet device 8 is connected, via a lock 34 and a coarse cleaning machine 35, to the grain drier 3.

Furthermore, an inlet pipe 37 for fresh air is connected to the outlet device via damper 38 to regulate the flow of fresh air through the pipe 37 into the outlet device 8 and from there through openings 33 into the separating section 7. The main part of the straw and chaff which has accompanied the grain into the outlet device is separated in the coarse cleaning machine 35. This cleaned portion is conveyed to the feed pipe 1 9 of the secondary drier.

The combustion furnace 1 7 can be fired with any fuel such as oil, gas, coal, wood and/or with products which are separated in the installation described. A fan 41 is provided to blow combustion gases into the mixing chamber 21 of the secondary drier 2, while a fan for blowing colder fresh air into the mixing chamber is designated 42. Inside the secondary drying drum 22 there is a temperature measuring device 43 which delivers a temperature measurement to a regulating device 44. The regulating device 44 is in turn adapted to regulate the drying process hy acting on a flow regulating valve 45, 46 disposed in each connecting pipe for hot flue gas and colder fresh air respectively.

Also disposed in the primary drier 6 in the device 1 is a temperature measuring device 47, more pecifically immediately in front of or possibly inside the actual constriction 32, that is to say in front of the separating section 7. A regulating device, designated 48, as adapted to be able to regulate the flows into the mixing chamber 4 of hot air and cold air respectively, depending on measurements from the measuring device 47, by acting on a pair of flow regulating valves 49 and 50 in the connections 54, 55 respectively. The hot air is adapted to be heated by the flue gases from the combustion furnace 1 7 in a heat exchanger 51 and is blown into the mixing chamber 5 by a fan 52. A cold-air fan is designated 53.

The device 1 will now be explained in more detail with reference to Figures 2-4. As stated, the primary drier 6 and the separating section 7 have the form of a coherent rotatable drum with a horizontal axis of rotation. The rotating drum is designated 60 in Figures 2-4 and is adapted to be rotated by a motor 61 about the horizontal axis rotation. The drum 60 rests against two pairs of rollers 62 which are supported, via bearing pedestals 63 by a base 64.

The primary drier 6 is provided, at the inside of the drum 60, with lifting laminations 65 in the form of pieces of plate directed radially inwards. The constriction 32 between the primary drier 6 and the separating section 7 is determined by a sleeve-shaped portion 66 with a conical collar 67 which is connected to the inside of the drum 60 in the direction of the primary drier 6. Thus an annular pocket 68 is formed between the sleeve 66, the collar 67 and the drum 60. The abovementioned grain discharge openings 33 are formed in the shell of the drum 60 in the region in front of this pocket 68. The openings 33 are evenly distributed round the periphery of the drum and number at least eight, preferably more.

According to the form of embodiment, the number of grain discharge openings 33 goes up to eighteen. Instead of a number of separate openings, it might be advantageous to provide a continuous opening encircling the drum 60 and providing connecting means, preferably on the outer side of the drum, to connect the sections of the drum which are separated by such continuous opening.

Outside the openings 33 and surrounding the drum 60 there is disposed an outlet box 69. Along 3/4 of its periphery only a small air gap 70 separates the wall of the box from the outside of the drum, while in the region of the remaining quarter, the box 69 expands into a funnel-shaped outlet box 71. The outlet box 69 together with the outlet box 71 forms the outlet device 8 referred to earlier. The distance between the outlet box 69 and the outisde of the drum 60 is so short that the flow of air through its annular openings can be disregarded. As mentioned previously, a temperature measuring device 47 is disposed in the front portion of the primary drier. As can be seen from Figure 3, the temperature measuring device 47 is more specifically localized at the entrance to the constriction 32.Telemetric transmission is used to transmit temperature values to the regulating equipment 48, Figure 1.

The separating section 7 is cylindrical and is clad internally with spiral threads 80 consisting of sheet-metal strips, twisted in spiral shape and directed radially inwards and welded to the inside of the drum 20. The threads extend along the whole cylindrical part of the separating section 7, that it to say from the discharge opening 83 to the pocket 68. Disposed at a certain distance from each spiral thread 80, calculated with respect to the constriction 32 and the pocket 68, is a helical rod 76 of carriers 81 consisting of pins directed radially. The pins 81 are welded to the inside of the drum 60 and are so tightly placed in the individual rows 76 that pieces of straw which are lying crosswise cannot pass or can only do so with difficulty, while grains can pass through easily.

Each row 76 thus forms a sort of helical "rake" which can entrain long objects such as pieces of straw but to a considerably lesser extent can entrain objects consisting of finer particles such as grains, when the drum 60 rotates.

The mode of operation of the equipment described will now be explained in more detail.

The chopped crops are discharged from the silo 10 by means of the screw conveyor 9 and weighed on the belt weighing device 11. The discharge from the silo 10 is controlled by means of the regulating equipment 82 so that a relatively even flow of crops is obtained. The crops are fed via the lock 13 and pipe 5 into the primary drier 6 where they meet the hot air flowing through from the mixing chamber 4. In the primary drier 6, the crops are tumbled round by the paddles 65 when the drum 60 is rotated. The paddles 65 lift up the chopped crops in a manner known per se and then let them fall down again into the hot air flowing through which afterwards advances the material forwards towards the constriction 32. The temperature of the air flowing through is measured by the temperature measuring device 47.The temperature of the air flowing through is regulated by means of the device 48 by adjusting the valves 49 and 50 in the pipes 54, 55 for hot air and cold air respectively. The total flow of air is maintained constant, however. Thus the temperature in the primary drier 6 is regulated so that the superficial moisture in the goods is removed to such an extent that the grains can be threshed out while the material advances forwards in the primary drier 6.

When the crops reach the constriction 32, the grains are thus mainly threshed out. In the constriction 32, the material receives an increase in speed as a result of the fact that the air speed increases. In the course of this, the air flowing through entrains the lighter parts to a greater extent than the heavier grains, as a result of which a first separating effect is achieved. The threshing then continues in the separating section 7 to the extent that this has not already been completed in the primary drier 6. The material, particularly the straw parts, are lifted up by the pins 81 which form a helical rod 76 in front of each spiral thread 80.As a result of the fact that the pins 81 in the individual rows 76 are relatively close together, the entrainment means (the pins 81) entrain primarily the straw while the grains, on the other hand, can pass to a considerable extent between the pins 81. As a result of this, a second separating effect is achieved. The material which is fed up along the walls of the drum 60 by means of the pins 81 has therefore been further impoverished with regard to grains and when the entraining material falls down into the stream of air in the separating section 7, this material is thrown to a greater extent than remaining heavier grains in the direction of the discharge opening 83. By this means, a third separating effect is achieved. At the same time, the helically disposed elements 80 feed material in a backward direction.In view of the fact that the grains are present to a greater extent than other components in the bottom of the separating section and so can be exposed to the work of the screws 80, a fourth separating effect is achieved. Finally the material which is conveyed backwards by the screws - the spiral threads - 80 reaches the pocket 68 and passes out through the openings 33 in the shell of the drum 60 in the region in front of the outlet box 71. In the pocket 68, the discharge opening 33 and the outlet box 71, the material meets the colder fresh air which is continuously blown int6 the outlet box 71 and into the separating section 7 via the openings 33.By this means, a fifth separating effect is achieved, since the air entrains the lighter components to a greater extent than the grains which advance downwards towards the lock 34. The total effect is therefore that the predominant proportion of the lighter components, that is to say straw and chaff, is blown out through the discharge openings 83 in the far end of the separating section 7, while the grains are discharged into the outlet box 7.1 through the openings 33 in counter-current to the air which is continuously blown in through the pipe 37. Thus the grains describe a reciprocating movement which in certain cases can even be repeated a number of times so that the duration of stay for some of the grains in the separating section 7 cannot be ignored.As a result of the fact that colder air is continuously blown in from the pipe 37 via the outlet box 71 and the discharge opening 33, however, the temperature in the separating section 7 is kept at such a low level that damage to the grains can be avoided completely.

The straw and other components of the crop which passed through the discharge opening 83 into the outlet box 14 are conveyed to the secondary drier 22 by means of the screw conveyor 18 and the pipe 19. Hot air from the air mixer 21 flows through the secondary drier 22. In the same manner as in the primary drier 1 , the temperature in the secondary drier is regulated by adapting the flows of hot and cold gases by means of the valves 45 and 46. The combustion gases from the combustion furnace 17 are used as hot air. Before that, however, the combustion gases are used in the heat exchanger 51 to hear the air for the primary drier 1. Warm air from the cyclone separator 1 6 and/or 26 is used as secondary air for the combustion furnace.Thus the gas system of the installation is integrated to a great extent which affords a very high degree of energy utilization. With regard to the method of operation of other parts of the installation described with reference to Figures 1-4, no special explanation is needed.

With reference to Figure 5, a rotatable drum is designated by the numeral 1 60. The drum 1 60 corresponds to the drum 60 in Figure 3. A primary drier and a separating section are designated 1 06 and 107 respectively. The former, as in the previous form of embodiment, is provided with lifting laminations 1 65 in the form of pieces of plate directed radially inwards and possibly scoopshaped. According to this form of embodiment, the separating section 107 consists of four sections 107a, b, c and d. Disposed between the primary drier 106 and the first section 1 07a is a first orifice plate 132.Disposed between the first and second section 1 07a and 1 07b respectively, is a first line of discharge openings 1 33a, which are evenly distributed along the periphery of the drum 1 60. Disposed between the second and the third sections 1 07b and 1 07c respectively, is a second orifice plate 132b, and disposed between the third section 1 07c and the last section 1 07d is a second line of discharge openings 1 33b like the openings 133a. Outside the discharge openings 1 33a and 1 33b is an outlet device provided for each line of openings or alternatively a common outlet device (not shown in the Figure).

All the sections in the separating section 107 contain helically wound entrainment means of the same type as the element 80 in Figure 3. In Figure 5, the corresponding element is designated 180a, b, c and d with reference to the sections 107a, b, c and d. The elements 180a, b, c and d are only shown diagrammatically. The direction of the thread of the helical elements 1 80a and 1 soy in the sections 1 07a and 1 07c respectively is such that with normal rotations of the drum 1 60 they tend to drive material forwards in the direction of the arrows towards the discharge openings 1 33a and 1 33b respectively.In the sections 1 07b and 107d, the helical elements 1 80b and 180d are threaded with the opposite hand so that with normal rotation of the drum, they drive material backwards, see arrows, towards the openings 1 33a and 133b. In the last two sections 1 07c and 107d, pins 181 c and 181 d respectively are also disposed in rows 1 76c and 1 76d respectively, at a distance from the helical elements 1 80c and 1 80d respectively calculated with respect to the second line of discharge openings 133b. The object of the developed form of embodiment according to Figure 5 is to make more effective the separation of grain and straw components. With regard to the working principle, reference should be made to the basic principles which were described with reference to the previous form of embodiment.

Claims (24)

1. A method of treating chopped crops containing on the one hand grains or other seed, and on the other hand other plant constituents, wherein the chopped crops are introduced into a separating section of a rotating drum through which air flows, and the temperature of the air entering the separating section is regulated so that the grains or other seed can be separated without being damaged by prolonged overheating.

2. A method as claimed in claim 1, wherein the chopped crops are subjected to a certain amount of drying and threshing before being introduced into said separating section, by being conveyed through a primary drier in a rotating drying drum wherein the chopped crops are then treated at a considerably lower air temperature in the separating section than in the primary drier and during the treatment in the separating section the threshing is completed to the extent to which it is not already completed while at the same time the grains or seed are separated from the lighter components of the crops and wherein the grains or seeds and the lighter components are then finally dried in separate driers.

3. A method as claimed in claim 2, wherein said primary drier is a drum which is integrated with the separating drum and through which hot air is blown in the direction of conveying of the goods through the drier drum.

4. A method as claimed claim 2 or 3, wherein the lighter constituents are divided into a medium light fraction represented by plant constituents such as straw, stem or stalk components and a very light fraction represented by plant constituents such as husks, flower and leaf components, and wherein said division is preferably carried out substantially after the final drying of the lighter components.

5. A method as claimed in any one of the preceding claims, wherein the chopped crops in the separating section are lifted up by entrainment means on the inside of the drum, while the chopped crops are ventilated and subjected to threshing, while at the same time the lighter components are blown by the air flowing towards a discharge opening in the far end of the drum to a greater extent than the heavier grains, which instead are conveyed by oblique members towards one or more of grain discharge openings in the shell of the drum; and wherein air is continuously introduced into the separating section through said discharge openings thereby making more effective the separation of the lighter components from the grain material which is discharged.

6. A method as claimed in claim 5, wherein said entrainment means lift up longer portions of the goods which then fall down again.

7. A method as claimed in claim 5 or 6, wherein said oblique members are helical.

8. A method as claimed in claim 5, 6 or 7, wherein there is a plurality of said grain discharge openings each substantially encircling said drum.

9. A method as claimed in claim 5, 6 or 7, wherein there are at least two lines of said grain discharge openings axially spaced apart along the drum with each line substantially encircling the drum.

10. A method as claimed in any one of the preceding claims wherein the air temperature is measured before entry into the separating section and the temperature of the air entering the primary drier is regulated by regulating the mixing proportion between hot air and colder inlet air with a constant flow of air into the primary drier, and the combustion gases are then appropriately used in a secondary drier (2) to dry further the lighter products separated from the grains in the separating section.

11. A method as claimed in claim 10, wherein the hot inlet air is obtained by heating in a heat exchanger with combustion gases from a combustion furnace.

12. A method as claimed in claim 10 or 11, wherein the hot combustion gases are mixed with said colder inlet air before it is introduced into the secondary drier in a mixing proportion which is regulated depending on the temperature in the secondary drier.

13. A method as claimed in claim 2 alone or in combination with any of claims 3 to 12, wherein the major part of the lighter components of the chopped crops, the chaff fraction, is separated from the rest of said lighter components in discharge casings with a forced stream of air connected to the remote discharge end of the secondary drier.

14. A method as claimed in claim 5 or in any one of claims 7 to 1 3 when appendant thereto, wherein the grains or other seeds in the separating section are discharged through at least two said discharge openings or through lines of said discharge openings which are disposed spaced apart in the axial direction and at least substantially encircle the drum, and wherein the grains or other seeds which are to be discharged through said openings are fed forwards and backwards from both directions towards the discharge openings.

1 5. Apparatus for treating chopped crops, comprising a rotatable drum having a separating section with a discharge opening for the lighter components of the threshed crops in one end of the separating section; means for blowing air through the separating section; and, in the separating section of the drum: entrainment means fixed to the inside of the drum and adapted to lift up the crop when the drum is rotated and to release the goods again afterwards into the stream of air passing through the drum in use of the apparatus; a grain discharge opening encircling the drum or a plurality of grain discharge openings distributed around the drum; and oblique conveying members fixed to the inside of the drum and adapted, on rotation of the drum, to convey goods towards said grain discharge opening or openings.

16. Apparatus according to claim 15, wherein said oblique conveying members extend helically around the drum.

17. Apparatus as claimed in claim 1 5 or 16, wherein the entrainment means comprise elements with a short extent in the axial direction, which may appropriately be disposed in helical rows to form rake-like entrainment members with the capacity to entrain elongated products, such as straw components, while non-elongate components such as grains or other seeds can pass between the elements in said rows.

18. Apparatus as 'claimed in claim 17, wherein said elements are radially directed pins.

1 9. Apparatus as claimed in one of the claims 1 5 to 18, wherein there are at least two said discharge openings for the grains each encircling the drum or there are several said discharge openings disposed in at least two lines round the shell of the drum; and wherein said oblique conveying members are adapted to feed the grains or seeds or corresponding heavier products towards the discharge openings from both directions.

20. Apparatus as claimed in any one of the claims 1 5 to 19, wherein a discharge casing disposed outside the drum in the region in register with the grain discharge openings and surrounding the drum along a large part of the total periphery so that during rotation of the drum at least one said grain discharge opening is always in the region in register with the discharge casing.

21. Apparatus according to claim 20, wherein said discharge casing constitutes a part of a discharge manifold which surrounds the drum in the region in front of the discharge openings.

22. A method of treating chopped crops substantially as hereinbefore described with reference to the accompanying drawings.

23. Apparatus for treating chopped crops substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.

24. Chopped crops treated by the method of any one of claims 1 to 14 and 22.