U.S. patent application number 13/508716 was filed with the patent office on 2013-05-30 for method and apparatus for processing a dry fuel.
This patent application is currently assigned to Fire Stixx Holz-Energle GmbH. The applicant listed for this patent is Franz Blieninger. Invention is credited to Franz Blieninger.
Application Number | 20130133246 13/508716 |
Document ID | / |
Family ID | 42282974 |
Filed Date | 2013-05-30 |
United States Patent
Application |
20130133246 |
Kind Code |
A1 |
Blieninger; Franz |
May 30, 2013 |
Method and Apparatus For Processing a Dry Fuel
Abstract
The invention relates to a method and device for processing a
dry fuel, in particular a wood pallet, wherein a dust-binding
additive is added to the conveying medium that transports the dry
fuel. The conveying medium that transports the dry fuel comprises
an air flow fed from a high-pressure or low-pressure source, the
dust-binding additive being added to the air flow in the form of a
mist.
Inventors: |
Blieninger; Franz;
(Vilsbiburg, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Blieninger; Franz |
Vilsbiburg |
|
DE |
|
|
Assignee: |
Fire Stixx Holz-Energle
GmbH
|
Family ID: |
42282974 |
Appl. No.: |
13/508716 |
Filed: |
November 9, 2010 |
PCT Filed: |
November 9, 2010 |
PCT NO: |
PCT/DE2010/001306 |
371 Date: |
May 8, 2012 |
Current U.S.
Class: |
44/602 ;
44/629 |
Current CPC
Class: |
C10L 9/10 20130101; C10L
5/44 20130101; Y02E 50/10 20130101; C10L 5/32 20130101; Y02E 50/30
20130101; B65G 53/526 20130101 |
Class at
Publication: |
44/602 ;
44/629 |
International
Class: |
C10L 5/32 20060101
C10L005/32 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 10, 2009 |
DE |
10 2009 052 643.9 |
Claims
1.-14. (canceled)
15. A method for processing a dry fuel wherein the dry fuel is
transported over a predetermined transport route with the aid of a
conveying means, characterized in that an additive which increases
elasticity, lowers material stresses and at the same time
lubricates and binds dust is added to the dry fuel on the transport
route through the intermediary of the conveying means.
16. The method according to claim 15, wherein the dry fuel is a
wood pellet.
17. The method according to claim 15, wherein the conveying means
comprises a conveying medium transporting the dry fuel, in
particular an air flow fed by a high-pressure or low-pressure
source, and the additive is added to the conveying medium or air
flow in the form of a spray mist.
18. The method according to claim 15, wherein the addition of the
additive takes place immediately after the entry of the dry fuel
into a delivery conduit.
19. The method according to claim 15, wherein the additive is taken
to a predetermined temperature prior to its application to the dry
fuel.
20. The method according to claim 15, wherein the additive has an
evaporation temperature that is lower than the ignition temperature
of the dry fuel.
21. The method according to claim 15, wherein the additive is added
to the dry fuel inside the injection conduit of a vehicle upstream
or downstream from the feed conduit.
22. The method according to claim 21, wherein the vehicle is
selected from the group comprising a road silo pump car vehicle, a
rail silo pump car vehicle, or a transport ship.
23. An apparatus for processing a dry fuel comprising conveying
means for transporting the dry fuel over a predetermined transport
route, wherein the conveying means is associated with feed means
whereby an additive which increases elasticity lowers material
stresses and at the same time binds dust is added to the conveying
means transporting the dry fuel.
24. The apparatus of claim 23, wherein the dry fuel is a wood
pellet.
25. The apparatus of claim 23, wherein the conveying means
comprises a conveying medium transporting the dry fuel, wherein the
conveying medium is an air flow fed by a high-pressure or
low-pressure source, and the additive is added to the conveying
medium in the form of a spray mist.
26. The apparatus of claim 23, wherein the addition of the
dust-binding additive takes place immediately after the entry of
the dry fuel into a delivery conduit.
27. The apparatus of claim 23, wherein the additive is introduced
at several different locations on the transport route.
28. The apparatus of claim 23, wherein the temperature control
means is provided whereby the additive is taken to a predetermined
temperature prior to the application of the dry fuel.
29. The apparatus of claim 23, wherein the additive has an
evaporation temperature that is lower than the ignition temperature
of the dry fuel.
30. A dry fuel wherein the dry fuel is coated at its surface with
an additive such that the surface of the dry fuel presents an
increased elasticity, reduced internal stresses, and a property of
binding dust due to adhesion.
31. The dry fuel of claim 30, wherein the dry fuel is a wood
pellet.
32. The dry fuel of claim 30, wherein the dust-binding additive
includes at least one component selected from the group consisting
of an oil, a molten wax, a liquid wax or a lipid.
33. The dry fuel of claim 30, wherein the dust-binding additive
includes a mixture of water and at least one component selected
from the group consisting of swollen starch, gelatin or glue.
Description
PRIORITY CLAIM
[0001] This application is a United States National Stage
Application claiming the benefit of priority under 35 U.S.C. 371
from International Patent Application No. PCT/DE2010/001306 filed
Nov. 9, 2010, which claims the benefit of priority from German
Patent Application Serial No. DE 102009052643.9 filed Nov. 10,
2009, the entire contents of which are herein incorporated by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a method and an apparatus
for processing a dry fuel, in particular a wood pellet, such that
the dry fuel is transported over a predetermined transport route
with the aid of a conveying means, characterized in that an
additive which increases elasticity, lowers material stresses and
at the same time lubricates and binds dust is added to the to the
dry fuel on the transport route through the intermediary of the
conveying means, and wherein a dry fuel, in particular a wood
pellet, characterized in that the dry fuel is coated at its surface
with an additive such that the surface of the dry fuel presents an
increased elasticity, reduced internal stresses, and a property of
binding dust due to adhesion.
BACKGROUND OF THE INVENTION
[0003] Large quantities of sawing by-products are generated in the
wood-processing industry. Thus, no more than approximately 60% of a
log's volume can be converted into a main product, with the
remaining 40% having to be termed waste in the widest sense. The
latter primarily include sawdust, wood shavings, and chips of which
wood pellets are usually produced. By way of example, such a
rod-shaped wood pellet has a diameter of between 4 mm and 10 mm, a
length of between 5 mm and 50 mm, a bulk density of about 1.1 to
1.3 kg/dm.sup.3, and an energy density of about 5 kWh/kg. The
manufacture of the pellets takes place in a ring die or flat die
pelleting press that is known per se, wherein crushing rollers
press the material to be pressed through the bores of the die. One
essential precondition for high-grade pellets is a starting
material having a highest possible fineness. Thus, the dried wood
particles are finely ground with the aid of fast-moving hammer
mills before entering the presses. Inside the presses the wood
particles are then ground even more finely in a combined grinding
and pressing process by the rotary movements of roller and die
through the application of high shear forces, and are pushed
through the bores in the die. This engenders temperatures of more
than 120.degree. C. and very high pressures. The pressures are
highest on the walls of the bores. In comparison with feedstuff
pellets, for instance, the specific energy input for wood pellets
is higher by a factor of 3-5.
[0004] As a consequence the cylindrical surface of the pellets
presents an extremely high density and a smooth surface. The
boundary area accordingly is substantially hard but brittle.
Following their passage through the bores the pellets are cut, then
drop into the cooler where the pellets lose another 2%-3% of their
humidity by releasing water vapor to the air passing through, are
cooled further, and undergo surface hardening. In the storage silo
the core temperature of the pressed pieces remains elevated for
another 1-3 weeks in comparison with the surface temperature. These
factors jointly result in several properties that are specific for
wood pellets. Thus, the finished pellets are for a large part made
up of extremely fine wood flour. An average breakdown of 6-mm
pellets by fractions might be as follows:
TABLE-US-00001 <3.15 mm 98.00% <2.0 mm 95.00% <1 mm 63.00%
<0.5 mm 25.00%
These figures illustrate the fineness at which the particle sizes
are present within the pellets.
[0005] Wood pellets for heating purposes have a residual humidity
of about 6% to about 10% at the most. This humidity content, which
is very low for wood, is necessary in heating pellets in order to
ensure a high energy density in combination with a good ignition
behavior. The humidity content at the cylindrical surfaces is lower
than in the core areas. As a result, the cylindrical surface
shrinks and due to the extremely low water content becomes very
brittle and fragile, and is subjected to tensile stresses. The
starch as a pressing aid moreover forms a so-called pressing skin
on the cylindrical surface of the pellets, which is equally fragile
and brittle because of the high dry content. Due to the
inhomogeneous pressure distribution inside the bore of the die, the
apparent density is distributed non-uniformly over the
cross-section of the pellets. Starting from the center, the density
increases radially toward the cylindrical surface. These factors in
combination with the high dust content result in an inherent
tendency of wood pellets to generate relevant quantities of abraded
matter in the form of fragments and dust during every
manipulation.
[0006] Wood pellets for heating purposes are delivered to the end
consumer in two ways: On the one hand in the form of bagged product
on pallets, mostly for use in pellet stoves; on the other hand, in
the form of loose product for use in central heating in the usual
performance range between 10 kW and 1,000 kW. The loose product is
customarily delivered to the customer by means of silo trucks and
injected via tube conduits with the aid of a pressure system
(reservoir +compressor). This technique has been known and accepted
for decades. Silo reservoir trucks are used to transport, e.g.,
cereal flours, animal feeds and granulates of all kinds and inject
them into the provided storage containers. In these known
applications the product to be conveyed either already is in dust
form (flour), or on the other hand the tendency to form dust is
substantially less pronounced than in the case of wood pellets
(example: feedstuffs that are substantially more elastic because of
their oil/lipid content, that are less highly compacted, do not
present material stresses like wood pellets, contain less
particulate matter, and already possess properties of binding fines
contents). In the case of wood pellets the excess air is evacuated
from the pellet storage to be filled (bag silo, storage space) via
an extractor fan. The storage space is accordingly provided with
two ports mostly having a size of 100 mm, namely, one for injection
and one for evacuation. Injection distances of 20 meters are
common, with up to 50 meters being technically viable. Injection
heights of up to 30 meters can be overcome in a vertical direction.
During injection the wood pellets are subjected to high mechanical
strains which depend on the tube lengths and local circumstances.
Owing to the material properties of wood pellets described in the
foregoing, this results in the generation of so-called abraded
matter having the form of wood dust and fragments. In addition, a
certain quantity of dust inherently clings to the wood pellets,
which is then set free by the movement and the air flow during
injection. Downstream from the extractor fan a filter sack is
provided as a preventive measure against the high dust load. Within
the storage a large part of the generated fine dust does, however,
settle on and in the voids between the pellets, especially in zones
where the air flow may be calmed or circulates. This is where
so-called "nests of dust" may additionally form, i.e., areas having
an elevated proportion of fines. So-called fragments are
furthermore produced inside the injection conduit. These are
compacted grains having sizes of about 0.1 mm to 3.15 mm (under the
DIN standard [German Industrial Standard], particles>3.15 mm are
not termed fines any more). A high proportion of dust and fragments
degrades the flow characteristics of the pellets in the storage and
in the conveying means leading to the pellet heating system proper,
may cause clogging within worm conveyors, brings about an
unpleasant fine dust load in the basement and housing space in the
case of the widely common vacuum systems, degrades the ignition
behavior in the burner, with the possibility of the fine dust
proportion also increasing in the flue gases in consequence,
combustion in general is degraded (degraded air management in the
primary air area), and altogether brings about a degradation of the
boiler efficiency.
[0007] DE 39 18 523 C2 proposes a method for preventing dust
formation during loading or transport of fertilizer granules,
wherein a liquid mixture of molasses and glycerol or polyethylene
glycol or triethanolamine as a second organic substance are added
as a dust binder. Such additives are not acceptable in the case of
a fuel because of the toxic effect of these substances during
combustion.
SUMMARY OF THE INVENTION
[0008] The present invention is based on the object of providing an
environmentally compatible and at the same time low-cost solution
for processing a dry fuel, in particular a wood pellet, which
renders the dry fuels more resistant to mechanical stresses. This
objective is achieved through the method and apparatus as well as
the dry fuel of the present invention.
[0009] The method of the invention and the apparatus of the
invention for processing a dry fuel, in particular a wood pellet,
are characterized in that an additive which increases elasticity,
lowers material stresses and at the same time lubricates and binds
dusts is added to the dry fuel on the transport route by means of
the conveying means. Here it is provided in accordance with the
principle of the invention that the conveying medium transporting
the dry fuel includes an air flow fed by a high-pressure or
low-pressure source, and the dust-binding additive is added to the
air flow in the form of a spray mist. Advantageously it is provided
that the addition of the dust-binding additive takes place
immediately after the entry of the dry fuel into a delivery
conduit. In accordance with the invention the addition of about 1
to 3 liters of additive is required for every 1,000 kg of dry
fuel.
[0010] The advantage of the invention resides in the fact that the
surface of the dry fuel is given dust-binding properties while at
the same time the flow characterristics and thus the
transportability of the fuels are improved considerably, the
material stresses are lowered, and the surface of the fuels is
rendered more elastic.
[0011] An advantageous development of the invention consists in the
addition inside the injection conduit of a spray mist which
collides with the wood pellets and encloses them with a thin oil
film or emulsion layer. Moreover the dust particles may collide
with droplets of the additive and furthermore bind to larger-sized
wood pellets.
[0012] One important effect in the framework of the invention
resides in the fact that lowering the surface stresses and raising
the surface elasticity globally causes less abraded matter to be
produced during manipulation of the pellets. Apart from practical
tests involving a silo injection truck, this effect could also be
proven through the so-called abrasion test. The abrasion test
describes a standardized method for testing the mechanical abrasion
resistance of wood pellets that is widely common in the pellet
industry and prescribed by DIN. In this test, 100 g of pellets are
whirled about inside a defined air flow during 1 minute, and
afterwards the produced fines content is reweighed. Abraded matter
values of 1-2% are standard. By means of the surface treatment of
the pellets it was possible to lower the quantity of abraded
matter.
[0013] A second effect consists in the removal of dust due to the
fact that the pellets are coated with a tacky, at least
dust-binding layer by spraying in the additive, so that the dust
particles may bind to this surface. Another effect of rather minor
importance is that small dust particles combine with each other to
form larger-sized particles as they collide with each other. The
coating prevents the dust adhering to the pellets from detaching.
Thus it is crucial that the surface of the pellets is covered by a
dust-binding layer.
[0014] It is one positive side effect of the utilization of oils,
waxes or resins that automatic ignition by the burner is
facilitated.
[0015] In principle any sprayable substance that reduces material
stresses, increases elasticity, possesses dust-binding properties,
does not or only insubstantially increase the calorific value, and
does not bring about unfavorable properties during combustion, may
serve as the spraying liquid. Ideally, however, the additive should
have the following properties: [0016] 1. Reduce the material
stresses and/or increase the surface elasticity [0017] 2. Lubricate
the inner surfaces of injection conduits, worm coils and conveying
spirals [0018] 3. Possess dust-binding properties [0019] 4. Present
a low surface tension [0020] 5. Have no properties degrading
combustion, or generate noxious exhaust gases [0021] 6. Be
low-cost, and [0022] 7. Be of natural origin
[0023] Advantageously it is provided that the coating additive
includes an oil and/or a molten or liquid wax and/or a lipid. Some
oils possess the best properties. Before the background that the
standard heating systems are adapted to the energy content of wood
having a humidity content of about 6-10%, however, it is crucial to
consider a possible undesirable augmentation of the calorific
value. The burners of pellet furnaces and boilers have a certain
control range which is, however, rather restricted due to their
construction. The feed augers for conveying the pellets into the
firing chamber are as a general rule controlled and preset
volumetrically. In other words, if the calorific value of the
pellets per volume unit is significantly (more than about 3%)
higher than that of untreated wood pellets, there is a possibility
of excessive energy being supplied to the burner. As a consequence
the heating system then is frequently not capable any more of
sufficient readjustment control, with a deficiency of air or oxygen
being created inside the firing chamber. This causes the combustion
to become less clean, and more exhaust gases are produced,
involving the risk of the formation of ashes. In this regard, care
should be taken to keep the added amount of an additive increasing
the calorific value as low as possible or necessary. In trials
including canola oil, e.g., 1 to 3 liters per metric ton
(corresponding to approx. 0.1-0.3%) were already sufficient in the
form of a spray mist application inside the injection conduit in
order to attain the desired advantages. In this case the calculated
increase of the calorific value is only 0.2% to 0.6% per volume
unit. The required quantity specifically depends on the quality of
the wood pellets. Pellets of a poorer quality which present--or
create during transport--a higher content of abraded matter and
dust require more additive.
[0024] As the wood pellets are an ecological fuel, however,
preference should at any rate be given to natural substances. In
this sense it is advantageous if the coating additive includes a
mixture of water with swollen starch and/or gelatin and/or glue.
The effect is improved by lowering the surface tension with the aid
of a tenside. In practice a water-based additive is not expected to
be employed as it will cause the pellets to swell even in cases of
slight excess quantities or droplet formation. We could not observe
such easy and rapid swelling when oils, waxes or resins were
used.
[0025] An additional advantage is brought about if the spraying
device is installed in a location of the injection conduit
downstream from where the pellets enter from the reservoir into the
delivery conduit. As a result, the spray mist is already mixed
homogeneously with the injection air prior to the actual contact
with the pellets.
[0026] The efficiency of the dust binding process is enhanced by
the fact that the velocity of flow of the air inside the injection
tubes is substantially (by about a factor 10) higher than the flow
velocity of the pellets (pellets=approx. 5 m/sec, air>50 m/sec).
In addition the air has to meander, as it were, through the pore
passages of the pellets while undergoing numerous and lasting
changes of direction and velocity. Photographs of pellets flowing
inside the injection conduit showed that the pellets have a
relatively uniform distribution and are afloat separately in the
air flow. As a result there is a very high and uniform probability
of the pellets or particles to collide with the droplets of spray
mist. Furthermore a thin oil film is deposited on the walls of the
injection conduits. This thin oil film in addition allows the
pellets to slide more smoothly on the walls, and dust and fragments
may also adhere there before again being carried along and bound by
pellets. All in all this has a very strong effect of reducing the
fine dust content.
Spray liquids found to be suitable were, for example:
[0027] vegetable oils, canola oil, linseed oil, sunflower oil
[0028] mineral oils such as, e.g., glycerol, paraffin oils,
[0029] water-based additives on the basis of swollen starch or
gelatin
[0030] wax emulsions and lipids
[0031] An additional advantage is that the compressed air in the
injection conduits is heated. As a result it is also possible to
use substances that are normally semi-solid or solid but not
brittle at ambient temperature. These do, however, have to be
pre-heated in a storage container (lipids, waxes, sterols, etc.).
The further advantages of the processing of dry fuels in accordance
with the invention by means of the present method are as follows:
The frictional resistance of the pellets as a bulk material is
reduced, with the flowability of the pellets in the storage
space/silo consequently being improved. The oily coating lubricates
the injection conduits and the conveying means leading to the
heating burners (screws, spirals, suction conduits). According to
our observations, the oils do not soak completely into the inside
of the pellets but a lasting thin "lubricating film" is preserved
(hardly any cavities present in the extremely compacted pressed
pieces). The slight increase in pellet stability reduces the
generation of abraded matter even following injection of the
pellets into the end consumer storage from which the pellets must
then again be conveyed one last time--sometimes via several
stations--to the burner.
[0032] The apparatus of the invention for transporting a dry fuel,
in particular a wood pellet, comprising a conveying means which
transports the dry fuel with the aid of a conveying medium, in
particular an air flow fed by a high-pressure or low-pressure
source, is characterized in that the conveying means is associated
with a feed means whereby an additive which increases elasticity,
lowers material stresses and at the same time binds dusts is added
to the conveying medium transporting the dry fuel. Here it is
provided that the conveying medium transporting the dry fuel
includes an air flow fed by a high-pressure or low-pressure source,
and the additive is added to the air flow in the form of a spray
mist.
[0033] In accordance with a quite particularly preferred
development of the invention it is provided that the additive has
an evaporation temperature that is lower than the ignition
temperature of the dry fuel. It is advantageous if the additive,
such as a vegetable oil, is crosslinked during heating in the
burner to thus form a viscous resinous coat. As a result the
so-called aerosols (fine dusts) are also retained in the coat, and
especially the organic constituents undergo postcombustion.
Aerosols are predominantly formed during the pyrolysis phase in
which the combustion process is not clean yet. This is precisely
why it is advantageous if the vaporization point of the additive is
lower than the ignition point of the fuel. In this way, the coating
ignites before it burns up, with the aerosols undergoing
postcombustion as a result. In addition an early, superficial
back-up fire is created which makes combustion cleaner. Here it is
necessary to consider each individual pellet. The life cycle of a
pellet lasts about 3 minutes and is divided into 4 phases:
[0034] 1) the evaporation phase (water vapor escapes,
<100.degree. C.) [0035] 2) the pyrolysis phase (heating on the
bed of glowing embers, <about 350.degree. C.) [0036] 3) the gas
phase (with flame) [0037] 4) the ember phase.
[0038] The additive coating has the effect of the pyrolysis phase
being shortened to some extent and the clean gas phase commencing
somewhat earlier. Thus, in the case of canola oil the ignition
point is at about 320.degree. C. but appears to even be raised,
just like the vaporization point, due to crosslinking of the
additive coat. The precise chemical processes have not been
examined sufficiently yet.
[0039] In a preferred development of the invention it may be
provided that the additive is taken to a predetermined temperature
prior to its application on the dry fuel. Here it is important to
pre-heat the oil to a fixed and adjustable temperature prior to
spraying on the pellets, for the viscosity changes greatly with the
temperature. This temperature is at about 35.degree. C. to allow
good atomization of the oil, at pressures of about 10 bars to 20
bars.
[0040] In an advantageous development of the apparatus of the
invention it is provided that the addition of the dust-binding
additive takes place immediately following the entry of the dry
fuel into a delivery conduit.
[0041] In a particularly preferred development, the apparatus of
the invention represents a utility vehicle for use on a road or
waterway.
[0042] The invention further relates to a dry fuel for heating
purposes, in particular a wood pellet, which is characterized by
the fact that the dry fuel is coated at its surface with an
additive such that the surface of the dry fuel presents an
increased elasticity, reduced internal stresses, and a property of
binding dust due to adhesion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] Further details, advantages, expedient points and
developments of the invention may be taken from the following
description of a practical example making reference to the figures
of the drawings, wherein:
[0044] FIG. 1 is a schematic sectional view of a practical example
of the invention; and
[0045] FIG. 2 is a schematic sectional view of a further practical
example of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0046] The apparatus 1 of the invention represented in FIGS. 1 and
2 for the transport and/or storage of a dry fuel 2, in particular a
wood pellet, comprises a conveying means 3 which transports the dry
fuel 2 with the aid of a conveying medium, in particular an air
flow (arrow 4) fed by a high-pressure or low-pressure source (not
shown in detail in the figures) and conducted inside an injection
conduit 5, wherein the conveying means 3 is associated with a feed
means 6 whereby a coating additive 7 is added to the conveying
medium 4 transporting the dry fuel 2; namely, the additive 7 is
added to the air flow 4 in the form of a spray mist. The feed means
6 comprises an additive reservoir 8 in which a predetermined
pressure prevails and which on the output side feeds an atomizer
nozzle 10 arranged in the injection conduit via an additive feeding
conduit 9. As regards quantity and droplet size of the spray mist 7
emitted by the atomizer nozzle 10, the spray mist 7 is adjusted as
a function of the transport route.
[0047] The dry fuels 2 stored in the pellet chamber 12 "flow" via a
funnel-shaped chamber outlet 13 connected to the bottom side of the
pellet chamber into the injection conduit 5 (in accordance with
arrow 14) and are in a given case transported to a pellet storage
(equally not represented) of a residential building via further
tube conduits (not represented in detail) in accordance with arrow
11. The addition of the additive 7 takes place immediately
following the entry 13 of the dry fuel into the delivery conduit 5.
The injection conduit 5 and all of the conduits and tubes connected
thereto are coated with the additive. This coating 15 has the
effect of increasing strength, binding dust, lowering the sliding
resistance of the dry fuels, and brings about a reduction of
fragments and abraded matter. Inside the injection conduit 5 the
dust particles bind to the dry fuel 2 and to larger-sized
particles. The dry fuel 2 is coated at its surface with the coating
15 of dust-binding additive 7 such that the surface of the dry fuel
2 is given higher elasticity, abrasion resistance, slidability, and
a property of binding dust through adhesion.
[0048] In FIG. 1 the basic effective principle of the invention is
illustrated in a schematic sectional view.
[0049] FIG. 2 shows a preferred practical example of the apparatus
1 of the invention having the form of a silo truck including three
pellet chambers 12a, 12b, 12c, wherein selecting a pellet chamber
may be affected with the aid of a slide valve 16 in order to open
the desired pellet chamber 12a, 12b, or 12c.
* * * * *