CA1323764C - Scrap freezing tunnel - Google Patents
Scrap freezing tunnelInfo
- Publication number
- CA1323764C CA1323764C CA 615317 CA615317A CA1323764C CA 1323764 C CA1323764 C CA 1323764C CA 615317 CA615317 CA 615317 CA 615317 A CA615317 A CA 615317A CA 1323764 C CA1323764 C CA 1323764C
- Authority
- CA
- Canada
- Prior art keywords
- tunnel
- scrap
- end portion
- cryogenic material
- support structure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 230000008014 freezing Effects 0.000 title claims abstract description 19
- 238000007710 freezing Methods 0.000 title claims abstract description 19
- 239000007788 liquid Substances 0.000 claims abstract description 40
- 239000004078 cryogenic material Substances 0.000 claims abstract description 36
- 230000004044 response Effects 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 8
- 230000008878 coupling Effects 0.000 claims 3
- 238000010168 coupling process Methods 0.000 claims 3
- 238000005859 coupling reaction Methods 0.000 claims 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 41
- 229910052757 nitrogen Inorganic materials 0.000 description 20
- 239000007789 gas Substances 0.000 description 13
- 230000001965 increasing effect Effects 0.000 description 8
- 238000002347 injection Methods 0.000 description 6
- 239000007924 injection Substances 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 239000002826 coolant Substances 0.000 description 4
- 230000007246 mechanism Effects 0.000 description 4
- 238000010276 construction Methods 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000011144 upstream manufacturing Methods 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000012080 ambient air Substances 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 101100478173 Drosophila melanogaster spen gene Proteins 0.000 description 1
- 101100513476 Mus musculus Spen gene Proteins 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D3/00—Devices using other cold materials; Devices using cold-storage bodies
- F25D3/10—Devices using other cold materials; Devices using cold-storage bodies using liquefied gases, e.g. liquid air
- F25D3/11—Devices using other cold materials; Devices using cold-storage bodies using liquefied gases, e.g. liquid air with conveyors carrying articles to be cooled through the cooling space
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Separation By Low-Temperature Treatments (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A tunnel for freezing scrap is adapted to reduce consumption of volatile liquid cryogens. The tunnel is supported in an inclined orientation androtated to move scrap from a scrap inlet to a scrap outlet. A liquid cryogen is injected into the tunnel. The scrap inlet may incorporate a screw drive or othermechanism to reduce loss of gaseous cryogenic material. An exhaust conduit permits discharge of spent gaseous cryogen. The temperature of the spent gas is sensed and indicated, and the rate at which spent cryogen is exhausted and fresh cryogen is introduced is varied with the temperature. A discharge end of the tunnel contains an annular plate which prevents free discharge of liquid cryogen. A longitudinal rib attached to the interior surface of the tunnel adjacent the plate lifts scrap from liquid cryogen accumulating at the plate and drops the scrap through the central opening. The plate is inclined relative to the rational axis of the tunnel so that the opening in the plate is angled to properly receive the scrap. The rate of processing is controlled by varying both the rotational speed and inclination of the tunnel so that different degrees of tumbling actioncan be provided at a desired processing speed.
A tunnel for freezing scrap is adapted to reduce consumption of volatile liquid cryogens. The tunnel is supported in an inclined orientation androtated to move scrap from a scrap inlet to a scrap outlet. A liquid cryogen is injected into the tunnel. The scrap inlet may incorporate a screw drive or othermechanism to reduce loss of gaseous cryogenic material. An exhaust conduit permits discharge of spent gaseous cryogen. The temperature of the spent gas is sensed and indicated, and the rate at which spent cryogen is exhausted and fresh cryogen is introduced is varied with the temperature. A discharge end of the tunnel contains an annular plate which prevents free discharge of liquid cryogen. A longitudinal rib attached to the interior surface of the tunnel adjacent the plate lifts scrap from liquid cryogen accumulating at the plate and drops the scrap through the central opening. The plate is inclined relative to the rational axis of the tunnel so that the opening in the plate is angled to properly receive the scrap. The rate of processing is controlled by varying both the rotational speed and inclination of the tunnel so that different degrees of tumbling actioncan be provided at a desired processing speed.
Description
1323~6~
FIE~LI) (:)F THE INVENTION
The invention relates to recycling of scrap by freezing and shattering, and more particularly, to apparatus used to freeze scrap for such 5 purposes.
BACKGROUND OF THE INV~NTION
Freezing tunnels for use in recycling scrap are known. An exemplary tunnel was proposed by the present inventor in Canadian patent No. 1,136,594 which issued on November 30, 1982. That patent describes an 10 insulated freezing tunnel which is inclined and rotated to convey scrap from a receiving end of the tunnel to a discharge end of the tunnel. Liquid nitrogen isinjected into ~e tunnel and freezes the scrap during transit. At the discharge end of the tunnel, the scrap might typically be delivered to a hammer mill whichshatters the frozen materials.
The cost of operating a freezing tuMel is detern~ined in large measure by the quantity of liquid cryogen required. In the past, nitrogen in gaseous form has been allowed to escape freely from the tunnd and such discharge would occur before the gas was fully spent. lt would be desirable to avoid such waste of cryogenic material and to provide more thorough transfer 20 of heat to the spent gas before discharge.
Another shortcoming associated with prior freezing tunnels is actual loss of liquid cryogen at the discharge end of the tunnel. The scrap locates principally at the bottom of the tunnel and is often immersed in liquid cryogen. At the discharge end of the tunnel, the liquid cryogen escapes with the25 scrap into the associated hammer mill. Reducing loss of liquid cryogen in this manner is dif~lcult as obs~uction of liquid flows necessarily obstructs the discharge of solid scrap.
Another problem with prior prac!ices is clinging of fine scrap, B
132~76~L
such as certain plastics, to the walls of the tunnel. The scrap can be li~ted from the tunnel walls by providing ribs to enhance tumbling action and by increasing the rate of tunnel rotation. However, increasing the rate of tunnel rotation incidentally increases the rate of transport of the materials and the residence time S within the tunnel. This hampers the ability to process scrap at appropriate speeds.
The present invention in its various aspects addresses these and other shortcornings associated with prior freezing tunnels.
SUMMARY OF THE INV~TION
In one aspect, the invention provides apparatus for freezing scrap comprising a tunnel having a central longitudina1 axis. An inlet communicates with the interior of the tunnel for delhery of scrap into a receiving end portion of the tunnel. An outlet communicates with the interior ofthe tunnel for discharge of the scrap at a discharge end portion of the tunnel.
15 Means are provided for suppo~ting the tunnel for rotation about its central longitudinal axis, inclined downwardly from the receiving end portion to the discharge end portion. Means are provided for rotating the tunnel to cause movement of scrap between the receiving and discharge end portions. Means are also provided for delivering volatile cryogenic material into the interior of 20 the tunnel for freezing of the scrap in transit. The term "volatile" as used herein should be understood as designating a material which is either a gas, a liquid which tends to transform readily into a gas, or a combination thereof. Means are provided for closing the tunne1 sufficiently that spent cryogenic material in a gaseous s~ate accumulates in the tuMel. An exhaust outlet communicates with 25 the interior of the ~uMel for discharge of spent cryogenic material in a gaseous state. Means are provided for sensing and indicating the temperature of the spent gases. Valiable flow generating means produce a discharge flow of the spent gaseous cryogenic material from the interior of the tunnel through the ~9 exhaust outl t and permit the rate of flow to be varied in response to the indicated temperature. The flow generating means may be manually operated in response to indicated temperature or may be automatically controlled in response to the temperature. This permits more effective use of costly liquid 5 cryogens. In preferred form, delivery of cryogenic material is also controlled in response to the sensed temperature of the spent gaseous cryogen.
In another aspect of the invention, the apparatus is adapted to reduce the escape of liquid cryogenic material through the scrap outlet. An obstruction is formed at the interior surface of the tunnel tunnel discharge end10 portion preventing liquid cryogenic mate~ial accumulated at the bottom of thetunnel from escaping into the scrap outlet. A passage is spaced from the bottom of the tunnel and comrnunicates with the scrap outlet. A scrap lifting member isfixed to the tunnel and extending inwardly from the interior surface of the tunnel, the scrap lifting member being so positioned relative to the obstruction15 and so shaped that the lifting member raises and separates scrap from the accumulated cryogenic material and drops the raised scrap into the passage in response to rotation of the tunnel. The passage may have an open end confronting the scrap moving from the tunnel receiving end portion towards the tunnel discharge end portion which is inclined relative to the central longitudinal 20 axis of the tunnel to facilitate receipt of the raised scrap. The preferred form of the obstruction is a simple plate actually fL~(ed to the tunnel itself and having a central opening, the plate being inclined selative to the central axis of the tunnel.
Other aspects and advantages associated with the present invention will be apparent from a description below of a preferred embodiment 25 and will be more specifically defined in the appended claims.
A~a The invention will be ~etter understood with the refe~nce to drawings in which:
B
i t32376~
fig. 1 is a side elevation of a freezing tunnel apparatus;
fig. 2 is a view along the lines 2-2 of fig. 1 illustrating how a tunnel is supported and illustrating apparatus for changing the tunnel's inclir ation;
S fig. 3 is an enlarged, fragmented elevational view of a discharge end portion of the tunnel detailing structure for retaining liquid cryogens;
fig 4 is a fragmented perspective view of a discharge end portion of the tunnel indicating a mechanism for separating solid scrap from liquid cryogens.
DESCRIPIION OEPRl~E~E~l~ODIMENT
Reference is made fig. 1 which diagramrnatically illustrates apparatus for freezing scrap. The apparatus includes an insulated turmel 10 having a scrap receiving end portion 12 and a scra~ discharge end portion 14.
The tunnel 10 is mounted on a steel support structure 16 for rotation about its longitudinal axis 18 (indicated in fig. 2). Three pairs of rollers attached to the support structure 16 support the tunnel 10 intermediate its ends forrotation about its cen~al longitudinal axis 18. Only one central pair of rollers is specifically indicated with reference number 20 in figs. 1 and 2. These rollers 20 have their rotational axes (not illustrated) aligned with the central longitudinal axis 18 of the tunnel 10 and engage an outer surface of the tunnel structure. A
circumferential flange 22 and another pair of rollers 24 prevent axial displacement of ~e tunnel 10 in response to its inclination. The flange 22 is simply attached to the exterior of the tunnel 10 generally pe~pendicular to the central longitudina1 axis 18 of the tunnel 10. The two rollers 24 are attached to the support structure 16 with their rotational axis vertical, perpendicular to the central longitudinal axis 18 of the tunnel 10. The flange 22 is wedged between the rolle~s '74 which consequently prevent axial displacement. A conventional adjustment mechanism may be provided to permit displacement of one of the B
1~237~
pair of rollers 20 such that spacing relative to the flange 22 can be adjusted. A
variable speed motor 26 is mounted on an extension of the support structure 16.
It is coupled in a conventional manner to the tunnel 10 by a chain 28 and a sprocket wheel 30 attached to the exterior of the tunnel 10 to cause rotation of5 the tunnel 10.
The support structure 16 is itself mounted on a stationary steel base 32. Hinges 34 define a pivot connection which joins the support structure 16 to the base 32. A manually-operable hydraulic jack 36 acting between the base 32 and the support structure 16, spaced from the hinges, permits pivoting 10 of the support structure 16 relative to the base 32 about the pivot connection.
The inclination of the tunnel 10 can consequently be selected substantially as desired by appropriate operation of the jack 36. Mounting of the motor 26 and various rollers on the support structure 16 immediately engaging the tunnel 10 is important to ensure that motor 26 and rollers remains operatively coupled to 15 the turmel 10 despite tilting. It should be noted that the maximum inclination of the tunnel 10 relative to horizontal in this embodiment is limited to about 15 degrees.
A metal inlet 38, including a hopper 40, is mounted on the support structure 16 at the tunnel receiving end portion 12. The inlet 38 20 communicates with the interior of the tunnel 10 for delivery of the scrap to the tunnel receiving end portion 12. A screw drive 42 is preferably provided at the base of the hopper 40 to drive scrap into the tunnel 10. One aspect of such a screw drive 42 is that it tends to close the receiving end portion 12 of the tunnel 10 against discharge of gaseous cryogens. It also tends to reduce the 25 introduction of warm ambient air into the tunnel 10. A metal scrap outlet 44 is provided at the tunnel discharge end portion 14. This too is mounted on the support structure 16 for pivoting with the tunnel 10. An injection line 46 extends tluough the scrap outlet 44 into the discharge end portion 14 of the 132376~
tunnel 10 to permit injection of liquid nitrogen under pressure from a source such as conventional metal bot~es (not illustrated). The injection line 46 is formed with adjustable nozzles (not illustrated) that effectively spray the liquid downwardly onto the scrap in the bottom of the tunnel 10 much of the liquid 5 evaporating upon injection. Discharge of gaseous cryogen at the discharge end portion 14 of the tunnel 10 is normally not critical, but if desired, a rotary gate mechanism or spring-biased baffles can be provided in the scrap outlet 44 to reduce the escape of gaseous cryogens and introduction of ambient air while pern~tting discharge of scrap. Seals may be forrned bet veen the scrap inlet 38,10 the scrap outlet 44 and the outer surface of the tunnel 10 to reduce undesired discharge of gaseous nitrogen. It should be noted, however, that absolute and precise sealing is not required for purposes of the invention and the cost of insuring gas-tight seals for such machinery would not normally be cost-justified. The benefits of the invention are obtained if the tunnel 10 is closed15 sufficiently to accumulate spent gases therefore allowing for controlled discharged.
An exhaust outlet 48 communicating with the interior of the tunnel 10 for discharge of spent nitrogen gas is provided at the base of the inlet hopper 40. (I~ is desirable in practice that the exhaust outlet 48 be coupled to a 20 discharge stack, as with flexible tube, leading to points external to the plant where the apparatus is operated.) A fan unit 50 is mounted in the exhaust outlet48 and a conventional manually-operable darnp~r 52 in the exhaust outlet 48 pennits the rate of discharge of spent nitrogen to be controlled. A temperature sensor 54 is mounted in the wall of the exhaust outlet 48 just outwardly of the 2S fan unit 50 to sense the temperature of the spent gaseous nitrogen being exhausted, which temperature is visually indicated by the sensor 54 externally of the exhaust oudet 48. The temperature gives an indication of how rapidly the nitr~gen is absorbing heat from the scrap. The arrangement pennits the rate of B
~32376~
discharging of spent nitrogen to be adjusted in response ~o termperature.
Basically, the damper 52 is adjusted such that the flow rate is increased with increasing temperatures and reduced with declining temperatures. It is within the ambit of the invention to incorporate automatic control of either the damper52 or the fan unit 50 itself (thereby elirninat ng the damper 52) to vary discharge flow rates in proportion to sensed and electronically indicated temperature. It should be appreciated, however, that a precision process is not practised in thefreezing tunnel 10 and that such controls may not provide considerable additional advantage.
The delivery of fresh liquid nitrogen from a pressurized source is controlled by a manually-operable valve 56 diagrarn~T~tically illustrated in the injection line 46. The valve 56 can be manually adjusted in response to the indicated temperature of the exhaust gases to vary the rate of delivery of freshliquid nitrogen in proportion to the sensed temperature. Basically, as the temperature of the spent gaseous nitrogen increases, the rate of delivery is increased. As the temperature drops, the rate of delivery is reduced. The rate of delivery can be varied automatically in response to sensed temperature, but once aga~n automatic control may not provide significant advantages over manual control.
The apparatus is also adapted to reduce any significant loss of liquid nitrogen which might occur at the scrap outlet 44 in a more convention freezing tunnel 10. An apertured "wobble" plate 58 is provided. This is ~n annular membar which is fitted tightly to interior surfaces of the tunnel 10 at the discharge end portion 14. It is inclined relative to the central longitudinal axis 18 of the tunnel 10 which for pulposes of the invention should be understood as meaning that its general plane is not perpendicular to the tunnel axis 18.
Accordingly, as the tunnel 10 rotates the plate S8 appears to go through a wobbling motion. One extremc of that wobbling motion is illustrated in solid ; - 7 -`- B
132376~ `
outline in fig. 3; the opposite extreme is illustrated in phantom outline. The plate 58 of course obstructs ~ee discharge of liquid nitrogen accumulating at the bottom of the tunnel 10 through the scrap outlet 44.
A longitudinal rib 60 is attached to the tunnel 10 and extends S inwardly from the tunnel's interior surface upstrearn of the wobble plate 58.
The rib 60 tends to lift scrap from the bottom of the tunnel 10 and drop the scrap against the upstream face 62 of the wobble plate 58. (The terrn "upstream" as used herein should be understood as indicating a direction contrary to that in which materials such as scrap are moving.) The quadrant of lO rotation 64 where such dropping occurs has been indicated by dotted shading in fig. 2 (assuming clockwise rotation of the tunnel in the plane of fig. 2).
Basically, the rib 60 is positioned circumferentially relative to the plate opening 66 such that the scrap is dropped into the opening 66 when the wobble plate 58 is in the orientation illustrated in solid outline in fig. 3. The reladve positioning 15 is more apparent in the perspective view of fig. 4 and dotted shading has been used in figs. 3 and 4 to indicate the dropping of scrap from the rib 60 through the plate opening 66. The rib 60 snay typically be positioned relative to the plate such that the extreme orientadon of the plate 58 shown in solid outline in fig. 3 is achieved when the rib is substandally m~dway in the quadrant 64. In this 20 orientation of the plah 58, the open end of the passage 66 confrondng the scrap is inclined such that the material ^an readily fall through.
A number of points should be noted. 'While the exact construction of the annular member used is not critical, it very desirable for the open end of the passage of such a member confronting the scrap moving 25 downstream from the tunnel receiving end portion 12 be incl;ned to facilitatereceipt of the rnaterials at least during actual dropping of the materials against the annular member. Any construction of the rib 60, including the shelf-like construction illustrated, which p~rnits liquid nitrogen to flow from the rib 60 ~ ~B
1~2~76~
back to the bottom of the tunnel 10 as the rib 60 rotates with the tunnel 10 is appropriate. The Ab 60 is apertured (not illustrated) at least adjacent the wobble plate 58 to enharlce drainage back to the bottom of the tunnel lO of liquid nitrogen raised with the scrap. Two other Abs 68, 70 are provided for tumbling 5 scrap ups~eam of the wobble plate 58 (enhancing exposure of the scrap to the gaseous coolant), but do not assist in discharging mateAals through the wobble plate 58.
Operation of the tunnel 10 will largely be apparent from the foregoing descAption of its components. Liquid nitrogen may initially be 10 injected into the empty tunnel 10 to achieve a desired operating temperature.For polyvinylchloride scrap this might ~pically be -45 degrees centigrade; for rubber products, -70 to -lO0 degrees centigrade. Scrap is introduced into the hopper 40 and is driven by the screw drive 42 into the interior of the tunnel 10.
The scrap is exposed to gaseous coolant upstream of the injection line 46. In 15 some instances, depending on the nature oî the scrap being processed, the scrap may be deliberately mingled with liquid coolant adjacent the wobble plate 58 to thoroughly freeæ the scrap. In other applications, the nozzles used to spsay theliquid coo1ant into the tunnel 10 and the rate of delivery may be adjusted to reduce the amount of liquid coolant which accumulates. At the tunnel discharge 20 end portion 14, the frozen scrap is raised by the rib 60 thereby separating it from any liquid cryogen and is dropped through the centTal opening of the wobble plate 58 for discharge through the scrap outlet 44.
The gas temperature indicated by the sensor 54 will be monitored closely during start-up. The rate of exhausting of gas wUI be 25 adjusted and the rate of delivery of fresh liquid nitrogen adjusted in general pr~portion to the indicated temperature untU steady-state operation is achieved.If the exhaust tcmperature is ~oo high, the rates of discharge of spent gaseous nitrogen and delivery of fresh liquid nitrogen are increased. However, if the :.
B
temperature of the exhaust gas dr~ps, indicating that the spent gas can still beused to advantage to draw heat from ~ncoming scrap, then the rate of discharge of spen$ gas is slowed as is the rate of delivery of fresh liquid nitrogen.
If scrap of a ~pe which is known to cling to the tunnel 10 is 5 being processed, the speed of tunnel rotation can be increased to provide greater tumbling action. To permit appropriate residence tirne despite ~e increased rotational speed, the inclination of the tunnel 10 can be decreased by appropriate operation of ~e hyd~aulic jack 36.
A screw drive feed mechanism is preferred for delivery of small 10 particulate scrap. As mentioned above, a screw dr~ve tends to reduce loss of gaseous nitrogen and introduction of a nbient air. If large items of scrap are to be processed, and a screw drive is inappropriate, spring-operated baffles may be provided in the scrap inlet to reduce gas transfer. Alterna~ively, a rota~y gate with several radial doors might be used.
It will be appreciated that a particular embodiment of the invention kas been described and that modifications may be made therein wi~out departing from the spirit of the invention or necessarily departing from the scope of the appended claims.
.~
.~
.
FIE~LI) (:)F THE INVENTION
The invention relates to recycling of scrap by freezing and shattering, and more particularly, to apparatus used to freeze scrap for such 5 purposes.
BACKGROUND OF THE INV~NTION
Freezing tunnels for use in recycling scrap are known. An exemplary tunnel was proposed by the present inventor in Canadian patent No. 1,136,594 which issued on November 30, 1982. That patent describes an 10 insulated freezing tunnel which is inclined and rotated to convey scrap from a receiving end of the tunnel to a discharge end of the tunnel. Liquid nitrogen isinjected into ~e tunnel and freezes the scrap during transit. At the discharge end of the tunnel, the scrap might typically be delivered to a hammer mill whichshatters the frozen materials.
The cost of operating a freezing tuMel is detern~ined in large measure by the quantity of liquid cryogen required. In the past, nitrogen in gaseous form has been allowed to escape freely from the tunnd and such discharge would occur before the gas was fully spent. lt would be desirable to avoid such waste of cryogenic material and to provide more thorough transfer 20 of heat to the spent gas before discharge.
Another shortcoming associated with prior freezing tunnels is actual loss of liquid cryogen at the discharge end of the tunnel. The scrap locates principally at the bottom of the tunnel and is often immersed in liquid cryogen. At the discharge end of the tunnel, the liquid cryogen escapes with the25 scrap into the associated hammer mill. Reducing loss of liquid cryogen in this manner is dif~lcult as obs~uction of liquid flows necessarily obstructs the discharge of solid scrap.
Another problem with prior prac!ices is clinging of fine scrap, B
132~76~L
such as certain plastics, to the walls of the tunnel. The scrap can be li~ted from the tunnel walls by providing ribs to enhance tumbling action and by increasing the rate of tunnel rotation. However, increasing the rate of tunnel rotation incidentally increases the rate of transport of the materials and the residence time S within the tunnel. This hampers the ability to process scrap at appropriate speeds.
The present invention in its various aspects addresses these and other shortcornings associated with prior freezing tunnels.
SUMMARY OF THE INV~TION
In one aspect, the invention provides apparatus for freezing scrap comprising a tunnel having a central longitudina1 axis. An inlet communicates with the interior of the tunnel for delhery of scrap into a receiving end portion of the tunnel. An outlet communicates with the interior ofthe tunnel for discharge of the scrap at a discharge end portion of the tunnel.
15 Means are provided for suppo~ting the tunnel for rotation about its central longitudinal axis, inclined downwardly from the receiving end portion to the discharge end portion. Means are provided for rotating the tunnel to cause movement of scrap between the receiving and discharge end portions. Means are also provided for delivering volatile cryogenic material into the interior of 20 the tunnel for freezing of the scrap in transit. The term "volatile" as used herein should be understood as designating a material which is either a gas, a liquid which tends to transform readily into a gas, or a combination thereof. Means are provided for closing the tunne1 sufficiently that spent cryogenic material in a gaseous s~ate accumulates in the tuMel. An exhaust outlet communicates with 25 the interior of the ~uMel for discharge of spent cryogenic material in a gaseous state. Means are provided for sensing and indicating the temperature of the spent gases. Valiable flow generating means produce a discharge flow of the spent gaseous cryogenic material from the interior of the tunnel through the ~9 exhaust outl t and permit the rate of flow to be varied in response to the indicated temperature. The flow generating means may be manually operated in response to indicated temperature or may be automatically controlled in response to the temperature. This permits more effective use of costly liquid 5 cryogens. In preferred form, delivery of cryogenic material is also controlled in response to the sensed temperature of the spent gaseous cryogen.
In another aspect of the invention, the apparatus is adapted to reduce the escape of liquid cryogenic material through the scrap outlet. An obstruction is formed at the interior surface of the tunnel tunnel discharge end10 portion preventing liquid cryogenic mate~ial accumulated at the bottom of thetunnel from escaping into the scrap outlet. A passage is spaced from the bottom of the tunnel and comrnunicates with the scrap outlet. A scrap lifting member isfixed to the tunnel and extending inwardly from the interior surface of the tunnel, the scrap lifting member being so positioned relative to the obstruction15 and so shaped that the lifting member raises and separates scrap from the accumulated cryogenic material and drops the raised scrap into the passage in response to rotation of the tunnel. The passage may have an open end confronting the scrap moving from the tunnel receiving end portion towards the tunnel discharge end portion which is inclined relative to the central longitudinal 20 axis of the tunnel to facilitate receipt of the raised scrap. The preferred form of the obstruction is a simple plate actually fL~(ed to the tunnel itself and having a central opening, the plate being inclined selative to the central axis of the tunnel.
Other aspects and advantages associated with the present invention will be apparent from a description below of a preferred embodiment 25 and will be more specifically defined in the appended claims.
A~a The invention will be ~etter understood with the refe~nce to drawings in which:
B
i t32376~
fig. 1 is a side elevation of a freezing tunnel apparatus;
fig. 2 is a view along the lines 2-2 of fig. 1 illustrating how a tunnel is supported and illustrating apparatus for changing the tunnel's inclir ation;
S fig. 3 is an enlarged, fragmented elevational view of a discharge end portion of the tunnel detailing structure for retaining liquid cryogens;
fig 4 is a fragmented perspective view of a discharge end portion of the tunnel indicating a mechanism for separating solid scrap from liquid cryogens.
DESCRIPIION OEPRl~E~E~l~ODIMENT
Reference is made fig. 1 which diagramrnatically illustrates apparatus for freezing scrap. The apparatus includes an insulated turmel 10 having a scrap receiving end portion 12 and a scra~ discharge end portion 14.
The tunnel 10 is mounted on a steel support structure 16 for rotation about its longitudinal axis 18 (indicated in fig. 2). Three pairs of rollers attached to the support structure 16 support the tunnel 10 intermediate its ends forrotation about its cen~al longitudinal axis 18. Only one central pair of rollers is specifically indicated with reference number 20 in figs. 1 and 2. These rollers 20 have their rotational axes (not illustrated) aligned with the central longitudinal axis 18 of the tunnel 10 and engage an outer surface of the tunnel structure. A
circumferential flange 22 and another pair of rollers 24 prevent axial displacement of ~e tunnel 10 in response to its inclination. The flange 22 is simply attached to the exterior of the tunnel 10 generally pe~pendicular to the central longitudina1 axis 18 of the tunnel 10. The two rollers 24 are attached to the support structure 16 with their rotational axis vertical, perpendicular to the central longitudinal axis 18 of the tunnel 10. The flange 22 is wedged between the rolle~s '74 which consequently prevent axial displacement. A conventional adjustment mechanism may be provided to permit displacement of one of the B
1~237~
pair of rollers 20 such that spacing relative to the flange 22 can be adjusted. A
variable speed motor 26 is mounted on an extension of the support structure 16.
It is coupled in a conventional manner to the tunnel 10 by a chain 28 and a sprocket wheel 30 attached to the exterior of the tunnel 10 to cause rotation of5 the tunnel 10.
The support structure 16 is itself mounted on a stationary steel base 32. Hinges 34 define a pivot connection which joins the support structure 16 to the base 32. A manually-operable hydraulic jack 36 acting between the base 32 and the support structure 16, spaced from the hinges, permits pivoting 10 of the support structure 16 relative to the base 32 about the pivot connection.
The inclination of the tunnel 10 can consequently be selected substantially as desired by appropriate operation of the jack 36. Mounting of the motor 26 and various rollers on the support structure 16 immediately engaging the tunnel 10 is important to ensure that motor 26 and rollers remains operatively coupled to 15 the turmel 10 despite tilting. It should be noted that the maximum inclination of the tunnel 10 relative to horizontal in this embodiment is limited to about 15 degrees.
A metal inlet 38, including a hopper 40, is mounted on the support structure 16 at the tunnel receiving end portion 12. The inlet 38 20 communicates with the interior of the tunnel 10 for delivery of the scrap to the tunnel receiving end portion 12. A screw drive 42 is preferably provided at the base of the hopper 40 to drive scrap into the tunnel 10. One aspect of such a screw drive 42 is that it tends to close the receiving end portion 12 of the tunnel 10 against discharge of gaseous cryogens. It also tends to reduce the 25 introduction of warm ambient air into the tunnel 10. A metal scrap outlet 44 is provided at the tunnel discharge end portion 14. This too is mounted on the support structure 16 for pivoting with the tunnel 10. An injection line 46 extends tluough the scrap outlet 44 into the discharge end portion 14 of the 132376~
tunnel 10 to permit injection of liquid nitrogen under pressure from a source such as conventional metal bot~es (not illustrated). The injection line 46 is formed with adjustable nozzles (not illustrated) that effectively spray the liquid downwardly onto the scrap in the bottom of the tunnel 10 much of the liquid 5 evaporating upon injection. Discharge of gaseous cryogen at the discharge end portion 14 of the tunnel 10 is normally not critical, but if desired, a rotary gate mechanism or spring-biased baffles can be provided in the scrap outlet 44 to reduce the escape of gaseous cryogens and introduction of ambient air while pern~tting discharge of scrap. Seals may be forrned bet veen the scrap inlet 38,10 the scrap outlet 44 and the outer surface of the tunnel 10 to reduce undesired discharge of gaseous nitrogen. It should be noted, however, that absolute and precise sealing is not required for purposes of the invention and the cost of insuring gas-tight seals for such machinery would not normally be cost-justified. The benefits of the invention are obtained if the tunnel 10 is closed15 sufficiently to accumulate spent gases therefore allowing for controlled discharged.
An exhaust outlet 48 communicating with the interior of the tunnel 10 for discharge of spent nitrogen gas is provided at the base of the inlet hopper 40. (I~ is desirable in practice that the exhaust outlet 48 be coupled to a 20 discharge stack, as with flexible tube, leading to points external to the plant where the apparatus is operated.) A fan unit 50 is mounted in the exhaust outlet48 and a conventional manually-operable darnp~r 52 in the exhaust outlet 48 pennits the rate of discharge of spent nitrogen to be controlled. A temperature sensor 54 is mounted in the wall of the exhaust outlet 48 just outwardly of the 2S fan unit 50 to sense the temperature of the spent gaseous nitrogen being exhausted, which temperature is visually indicated by the sensor 54 externally of the exhaust oudet 48. The temperature gives an indication of how rapidly the nitr~gen is absorbing heat from the scrap. The arrangement pennits the rate of B
~32376~
discharging of spent nitrogen to be adjusted in response ~o termperature.
Basically, the damper 52 is adjusted such that the flow rate is increased with increasing temperatures and reduced with declining temperatures. It is within the ambit of the invention to incorporate automatic control of either the damper52 or the fan unit 50 itself (thereby elirninat ng the damper 52) to vary discharge flow rates in proportion to sensed and electronically indicated temperature. It should be appreciated, however, that a precision process is not practised in thefreezing tunnel 10 and that such controls may not provide considerable additional advantage.
The delivery of fresh liquid nitrogen from a pressurized source is controlled by a manually-operable valve 56 diagrarn~T~tically illustrated in the injection line 46. The valve 56 can be manually adjusted in response to the indicated temperature of the exhaust gases to vary the rate of delivery of freshliquid nitrogen in proportion to the sensed temperature. Basically, as the temperature of the spent gaseous nitrogen increases, the rate of delivery is increased. As the temperature drops, the rate of delivery is reduced. The rate of delivery can be varied automatically in response to sensed temperature, but once aga~n automatic control may not provide significant advantages over manual control.
The apparatus is also adapted to reduce any significant loss of liquid nitrogen which might occur at the scrap outlet 44 in a more convention freezing tunnel 10. An apertured "wobble" plate 58 is provided. This is ~n annular membar which is fitted tightly to interior surfaces of the tunnel 10 at the discharge end portion 14. It is inclined relative to the central longitudinal axis 18 of the tunnel 10 which for pulposes of the invention should be understood as meaning that its general plane is not perpendicular to the tunnel axis 18.
Accordingly, as the tunnel 10 rotates the plate S8 appears to go through a wobbling motion. One extremc of that wobbling motion is illustrated in solid ; - 7 -`- B
132376~ `
outline in fig. 3; the opposite extreme is illustrated in phantom outline. The plate 58 of course obstructs ~ee discharge of liquid nitrogen accumulating at the bottom of the tunnel 10 through the scrap outlet 44.
A longitudinal rib 60 is attached to the tunnel 10 and extends S inwardly from the tunnel's interior surface upstrearn of the wobble plate 58.
The rib 60 tends to lift scrap from the bottom of the tunnel 10 and drop the scrap against the upstream face 62 of the wobble plate 58. (The terrn "upstream" as used herein should be understood as indicating a direction contrary to that in which materials such as scrap are moving.) The quadrant of lO rotation 64 where such dropping occurs has been indicated by dotted shading in fig. 2 (assuming clockwise rotation of the tunnel in the plane of fig. 2).
Basically, the rib 60 is positioned circumferentially relative to the plate opening 66 such that the scrap is dropped into the opening 66 when the wobble plate 58 is in the orientation illustrated in solid outline in fig. 3. The reladve positioning 15 is more apparent in the perspective view of fig. 4 and dotted shading has been used in figs. 3 and 4 to indicate the dropping of scrap from the rib 60 through the plate opening 66. The rib 60 snay typically be positioned relative to the plate such that the extreme orientadon of the plate 58 shown in solid outline in fig. 3 is achieved when the rib is substandally m~dway in the quadrant 64. In this 20 orientation of the plah 58, the open end of the passage 66 confrondng the scrap is inclined such that the material ^an readily fall through.
A number of points should be noted. 'While the exact construction of the annular member used is not critical, it very desirable for the open end of the passage of such a member confronting the scrap moving 25 downstream from the tunnel receiving end portion 12 be incl;ned to facilitatereceipt of the rnaterials at least during actual dropping of the materials against the annular member. Any construction of the rib 60, including the shelf-like construction illustrated, which p~rnits liquid nitrogen to flow from the rib 60 ~ ~B
1~2~76~
back to the bottom of the tunnel 10 as the rib 60 rotates with the tunnel 10 is appropriate. The Ab 60 is apertured (not illustrated) at least adjacent the wobble plate 58 to enharlce drainage back to the bottom of the tunnel lO of liquid nitrogen raised with the scrap. Two other Abs 68, 70 are provided for tumbling 5 scrap ups~eam of the wobble plate 58 (enhancing exposure of the scrap to the gaseous coolant), but do not assist in discharging mateAals through the wobble plate 58.
Operation of the tunnel 10 will largely be apparent from the foregoing descAption of its components. Liquid nitrogen may initially be 10 injected into the empty tunnel 10 to achieve a desired operating temperature.For polyvinylchloride scrap this might ~pically be -45 degrees centigrade; for rubber products, -70 to -lO0 degrees centigrade. Scrap is introduced into the hopper 40 and is driven by the screw drive 42 into the interior of the tunnel 10.
The scrap is exposed to gaseous coolant upstream of the injection line 46. In 15 some instances, depending on the nature oî the scrap being processed, the scrap may be deliberately mingled with liquid coolant adjacent the wobble plate 58 to thoroughly freeæ the scrap. In other applications, the nozzles used to spsay theliquid coo1ant into the tunnel 10 and the rate of delivery may be adjusted to reduce the amount of liquid coolant which accumulates. At the tunnel discharge 20 end portion 14, the frozen scrap is raised by the rib 60 thereby separating it from any liquid cryogen and is dropped through the centTal opening of the wobble plate 58 for discharge through the scrap outlet 44.
The gas temperature indicated by the sensor 54 will be monitored closely during start-up. The rate of exhausting of gas wUI be 25 adjusted and the rate of delivery of fresh liquid nitrogen adjusted in general pr~portion to the indicated temperature untU steady-state operation is achieved.If the exhaust tcmperature is ~oo high, the rates of discharge of spent gaseous nitrogen and delivery of fresh liquid nitrogen are increased. However, if the :.
B
temperature of the exhaust gas dr~ps, indicating that the spent gas can still beused to advantage to draw heat from ~ncoming scrap, then the rate of discharge of spen$ gas is slowed as is the rate of delivery of fresh liquid nitrogen.
If scrap of a ~pe which is known to cling to the tunnel 10 is 5 being processed, the speed of tunnel rotation can be increased to provide greater tumbling action. To permit appropriate residence tirne despite ~e increased rotational speed, the inclination of the tunnel 10 can be decreased by appropriate operation of ~e hyd~aulic jack 36.
A screw drive feed mechanism is preferred for delivery of small 10 particulate scrap. As mentioned above, a screw dr~ve tends to reduce loss of gaseous nitrogen and introduction of a nbient air. If large items of scrap are to be processed, and a screw drive is inappropriate, spring-operated baffles may be provided in the scrap inlet to reduce gas transfer. Alterna~ively, a rota~y gate with several radial doors might be used.
It will be appreciated that a particular embodiment of the invention kas been described and that modifications may be made therein wi~out departing from the spirit of the invention or necessarily departing from the scope of the appended claims.
.~
.~
.
Claims (15)
1. Apparatus for freezing scrap, comprising:
means defining a tunnel having a central longitudinal axis;
means defining a scrap inlet communicating with the interior of the tunnel for delivery of scrap into a receiving end portion of the tunnel means defining a scrap outlet communicating with the interior of the tunnel for discharge of scrap from a discharge end portion of the tunnel;
means supporting the tunnel for rotation about its central longitudinal axis and inclined downwardly from the tunnel receiving end portion to the tunnel discharge end portion;
means for rotating the tunnel to cause movement of scrap from the tunnel receiving end portion to the tunnel discharge end portion;
means for delivering volatile cryogenic material into the interior of the tunnel;
means closing the tunnel sufficiently that spent cryogenic material in a gaseous state accumulates in the tunnel;
means defining an exhaust outlet communicating with the interior of the tunnel for discharge of the spent gaseous cryogenic material;
temperature sensing means for sensing and indicating the temperature of the spent gaseous cryogenic material;
variable flow generating means for producing a discharge flow of the spent gaseous cryogenic material from the interior of the tunnel through the exhaust outlet and for permitting the rate of flow to be varied in response to the indicated temperature.
means defining a tunnel having a central longitudinal axis;
means defining a scrap inlet communicating with the interior of the tunnel for delivery of scrap into a receiving end portion of the tunnel means defining a scrap outlet communicating with the interior of the tunnel for discharge of scrap from a discharge end portion of the tunnel;
means supporting the tunnel for rotation about its central longitudinal axis and inclined downwardly from the tunnel receiving end portion to the tunnel discharge end portion;
means for rotating the tunnel to cause movement of scrap from the tunnel receiving end portion to the tunnel discharge end portion;
means for delivering volatile cryogenic material into the interior of the tunnel;
means closing the tunnel sufficiently that spent cryogenic material in a gaseous state accumulates in the tunnel;
means defining an exhaust outlet communicating with the interior of the tunnel for discharge of the spent gaseous cryogenic material;
temperature sensing means for sensing and indicating the temperature of the spent gaseous cryogenic material;
variable flow generating means for producing a discharge flow of the spent gaseous cryogenic material from the interior of the tunnel through the exhaust outlet and for permitting the rate of flow to be varied in response to the indicated temperature.
2. The apparatus of claim 1 in which the variable flow generating means comprise:
a fan unit; and, damper means mounted in the exhaust outlet for controlling gas flows through the exhaust outlet.
a fan unit; and, damper means mounted in the exhaust outlet for controlling gas flows through the exhaust outlet.
3 . The apparatus of claim 1 adapted to reduce the escape of liquid cryogenic material from the interior of the tunnel through the scrap outlet, comprising:
means defining an obstruction at the interior surface of the tunnel discharge end portion preventing liquid cryogenic material accumulated at the bottom of the tunnel from escaping into the scrap outlet and defining a passage spaced from the bottom of the tunnel that communicates with the scrap outlet;
a scrap lifting member fixed to the tunnel and extending inwardly from the interior surface of the tunnel, the scrap lifting member being so positioned relative to the obstruction and so shaped that the lifting member raises and separates scrap from the accumulated cryogenic material and drops the raised scrap into the passage in response to rotation of the tunnel.
means defining an obstruction at the interior surface of the tunnel discharge end portion preventing liquid cryogenic material accumulated at the bottom of the tunnel from escaping into the scrap outlet and defining a passage spaced from the bottom of the tunnel that communicates with the scrap outlet;
a scrap lifting member fixed to the tunnel and extending inwardly from the interior surface of the tunnel, the scrap lifting member being so positioned relative to the obstruction and so shaped that the lifting member raises and separates scrap from the accumulated cryogenic material and drops the raised scrap into the passage in response to rotation of the tunnel.
4. The apparatus of claim 3 in which the passage is located substantially centrally within the obstruction and has an open end confronting scrap moving from the tunnel receiving end portion towards the tunnel discharge end portion, the open end being inclined relative to the central longitudinal axis of the tunnel for receipt of the dropped scrap.
5. A freezing tunnel as claimed in claim 4 in which the lifting member is apertured to permit drainage to the bottom of the freezing tunne; of liquid cryogenic material raised with the scrap material.
6. The apparatus of claim 1 adapted to reduce the escape of liquid cryogenic material from the interior of the tunnel through the scrap outlet, comprising:
an annular plate attached to and circumscribing the interior surface of the tunnel at the tunnel discharge end portion such that liquid cryogenic material accumulated at the bottom of the tunnel is prevented from escaping into the scrap outlet, the annular plate being inclined relative to the central longitudinal axis of the tunnel and having a central opening;
a scrap lifting member fixed to the tunnel and extending inwardly from the interior surface of the tunnel proximate to the plate, the scrap lifting member being so positioned relative to the plate and so shaped that the lifting member raises and separates scrap from the accumulated cryogenic material and drops the raised scrap through the opening in response to rotation of the tunnel.
an annular plate attached to and circumscribing the interior surface of the tunnel at the tunnel discharge end portion such that liquid cryogenic material accumulated at the bottom of the tunnel is prevented from escaping into the scrap outlet, the annular plate being inclined relative to the central longitudinal axis of the tunnel and having a central opening;
a scrap lifting member fixed to the tunnel and extending inwardly from the interior surface of the tunnel proximate to the plate, the scrap lifting member being so positioned relative to the plate and so shaped that the lifting member raises and separates scrap from the accumulated cryogenic material and drops the raised scrap through the opening in response to rotation of the tunnel.
7 . The apparatus of claim 6 in which the lifting member is apertured to permit drainage to the bottom of the freezing tunnel of liquid cryogenic material raised with the scrap material.
8. The apparatus of claim 1 in which:
the support means comprise a base, a support structure, means connecting the support structure to the base such that the support structure can pivot relative to the base, means attached to the support structure and securing the tunnel to the support structure such that the tunnel is rotatable about its longitudinal axis, and means for selectively pivoting the support structure relative to the base to vary the inclination of the tunnel; and, the means for rotating the tunnel comprise motor means mounted on the support structure and means coupling the motor means to the tunnel such that the motor means rotate the tunnel.
the support means comprise a base, a support structure, means connecting the support structure to the base such that the support structure can pivot relative to the base, means attached to the support structure and securing the tunnel to the support structure such that the tunnel is rotatable about its longitudinal axis, and means for selectively pivoting the support structure relative to the base to vary the inclination of the tunnel; and, the means for rotating the tunnel comprise motor means mounted on the support structure and means coupling the motor means to the tunnel such that the motor means rotate the tunnel.
9. Apparatus for freezing scrap, comprising:
means defining a tunnel having a central longitudinal axis and an interior surface;
means defining a scrap inlet communicating with the interior of the tunnel for delivery of scrap into a receiving end portion of the tunnel;
means defining a scrap outlet communicating with the interior of the tunnel for discharge of scrap from a discharge end portion of the tunnel;
means supporting the tunnel for rotation amount its central longitudinal axis and inclined downwardly from the tunnel receiving end portion to the tunnel discharge end portion;
means for rotating the tunnel to cause movement of scrap from the tunnel receiving end portion to the tunnel discharge end portion;
means for delivering volatile cryogenic material into the interior of the tunnel;
means defining an obstruction at the interior surface of the tunnel discharge end portion preventing liquid cryogenic material accumulated at the bottom of the tunnel from escaping into the scrap outlet and defining a passage spaced from the bottom of the tunnel that communicates with the scrap outlet;
a scrap lifting member fixed to the tunnel and extending inwardly from the interior surface of the tunnel, the scrap lifting member being so positioned relative to the obstruction and so shaped that the lifting member raises and separates scrap from the accumulated cryogenic material and drops the raised scrap into the passage in response to rotation of the tunnel.
means defining a tunnel having a central longitudinal axis and an interior surface;
means defining a scrap inlet communicating with the interior of the tunnel for delivery of scrap into a receiving end portion of the tunnel;
means defining a scrap outlet communicating with the interior of the tunnel for discharge of scrap from a discharge end portion of the tunnel;
means supporting the tunnel for rotation amount its central longitudinal axis and inclined downwardly from the tunnel receiving end portion to the tunnel discharge end portion;
means for rotating the tunnel to cause movement of scrap from the tunnel receiving end portion to the tunnel discharge end portion;
means for delivering volatile cryogenic material into the interior of the tunnel;
means defining an obstruction at the interior surface of the tunnel discharge end portion preventing liquid cryogenic material accumulated at the bottom of the tunnel from escaping into the scrap outlet and defining a passage spaced from the bottom of the tunnel that communicates with the scrap outlet;
a scrap lifting member fixed to the tunnel and extending inwardly from the interior surface of the tunnel, the scrap lifting member being so positioned relative to the obstruction and so shaped that the lifting member raises and separates scrap from the accumulated cryogenic material and drops the raised scrap into the passage in response to rotation of the tunnel.
10. The apparatus of claim 9 in which the passage is located substantially centrally within the obstruction and has an open end confronting scrap moving from the tunnel receiving end portion towards the tunnel discharge end portion, the open end being inclined relative to the central longitudinal axis of the tunnel for receipt of the dropped scrap.
11. The apparatus of claim 9 comprising:
means closing the tunnel sufficiently that spent cryogenic material in a gaseous state accumulates in the tunnel;
means defining an exhaust outlet communicating with the interior of the tunnel for discharge of the spent gaseous cryogenic material;
temperature sensing means for sensing and indicating the temperature of the spent gaseous cryogenic material;
variable flow generating means for producing a discharge flow of the spent gaseous cryogenic material from the interior of the tunnel through the exhaust outlet and for permitting the rate of flow to be varied in response to the indicated temperature.
means closing the tunnel sufficiently that spent cryogenic material in a gaseous state accumulates in the tunnel;
means defining an exhaust outlet communicating with the interior of the tunnel for discharge of the spent gaseous cryogenic material;
temperature sensing means for sensing and indicating the temperature of the spent gaseous cryogenic material;
variable flow generating means for producing a discharge flow of the spent gaseous cryogenic material from the interior of the tunnel through the exhaust outlet and for permitting the rate of flow to be varied in response to the indicated temperature.
12. The apparatus of claim 9 in which:
the support means comprise a base, a support structure, means connecting the support structure to the base such that the support structure canpivot relative to the base, means attached to the support structure and securingthe tunnel to the support structure such that the tunnel is rotatable about its longitudinal axis, and means for selectively pivoting the support structure relative to the base to vary the inclination of the tunnel; and, the means for rotating the tunnel comprise motor means mounted on the support structure and means coupling the motor means to the tunnel such that the motor means rotate the tunnel.
the support means comprise a base, a support structure, means connecting the support structure to the base such that the support structure canpivot relative to the base, means attached to the support structure and securingthe tunnel to the support structure such that the tunnel is rotatable about its longitudinal axis, and means for selectively pivoting the support structure relative to the base to vary the inclination of the tunnel; and, the means for rotating the tunnel comprise motor means mounted on the support structure and means coupling the motor means to the tunnel such that the motor means rotate the tunnel.
13. Apparatus for freezing scrap, comprising:
means defining a tunnel having a central longitudinal axis and an interior surface;
means defining a scrap inlet communicating with the interior of the tunnel for delivery of scrap into a receiving end portion of the tunnel;
means defining a scrap outlet communicating with the interior of the tunnel for discharge of scrap from a discharge end portion of the tunnel;
means supporting the tunnel for rotation about its central longitudinal axis and inclined downwardly from the tunnel receiving end portion to the tunnel discharge end portion;
means for rotating the tunnel to cause movement of scrap from the tunnel receiving end portion to the tunnel discharge end portion;
means for delivering volatile cryogenic material into the interior of the tunnel;
an annular plate attached to and circumscribing the interior surface of the tunnel at the tunnel discharge end portion such that liquid cryogenic material accumulated at the bottom of the tunnel is prevented from escaping into the scrap outlet, the annular plate being inclined relative to thecentral longitudinal axis of the tunnel and having a central opening;
a scrap lifting member fixed to the tunnel and extending inwardly from the interior surface of the tunnel proximate to the plate, the scrap lifting member being so positioned relative to the plate and so shaped that the lifting member raises and separates scrap from the accumulated cryogenic material and drops the raised scrap through the opening in response to rotation of the tunnel.
means defining a tunnel having a central longitudinal axis and an interior surface;
means defining a scrap inlet communicating with the interior of the tunnel for delivery of scrap into a receiving end portion of the tunnel;
means defining a scrap outlet communicating with the interior of the tunnel for discharge of scrap from a discharge end portion of the tunnel;
means supporting the tunnel for rotation about its central longitudinal axis and inclined downwardly from the tunnel receiving end portion to the tunnel discharge end portion;
means for rotating the tunnel to cause movement of scrap from the tunnel receiving end portion to the tunnel discharge end portion;
means for delivering volatile cryogenic material into the interior of the tunnel;
an annular plate attached to and circumscribing the interior surface of the tunnel at the tunnel discharge end portion such that liquid cryogenic material accumulated at the bottom of the tunnel is prevented from escaping into the scrap outlet, the annular plate being inclined relative to thecentral longitudinal axis of the tunnel and having a central opening;
a scrap lifting member fixed to the tunnel and extending inwardly from the interior surface of the tunnel proximate to the plate, the scrap lifting member being so positioned relative to the plate and so shaped that the lifting member raises and separates scrap from the accumulated cryogenic material and drops the raised scrap through the opening in response to rotation of the tunnel.
14. The apparatus of claim 13 comprising:
means closing the tunnel sufficiently that spent cryogenic material in a gaseous state accumulates in the tunnel;
means defining an exhaust outlet communicating with the interior of the tunnel for discharge of the spent gaseous cryogenic material;
temperature sensing means for sensing and indicating the temperature of the spent gaseous cryogenic material;
variable flow generating means for producing a discharge flow of the spent gaseous cryogenic material from the interior of the tunnel through theexhaust outlet and for permitting the rate of flow to be varied in response to the indicated temperature.
means closing the tunnel sufficiently that spent cryogenic material in a gaseous state accumulates in the tunnel;
means defining an exhaust outlet communicating with the interior of the tunnel for discharge of the spent gaseous cryogenic material;
temperature sensing means for sensing and indicating the temperature of the spent gaseous cryogenic material;
variable flow generating means for producing a discharge flow of the spent gaseous cryogenic material from the interior of the tunnel through theexhaust outlet and for permitting the rate of flow to be varied in response to the indicated temperature.
15. The apparatus of claim 13 in which:
the support means comprise a base, a support structure, means connecting the support structure to the base such that the support structure canpivot relative to the base, means attached to the support structure and securingthe tunnel to the support structure such that the tunnel is rotatable about its longitudinal axis, and means for selectively pivoting the support structure relative to the base to vary the inclination of the tunnel; and, the means for rotating the tunnel comprise motor means mounted on the support structure and means coupling the motor means to the tunnel such that the motor means rotate the tunnel.
the support means comprise a base, a support structure, means connecting the support structure to the base such that the support structure canpivot relative to the base, means attached to the support structure and securingthe tunnel to the support structure such that the tunnel is rotatable about its longitudinal axis, and means for selectively pivoting the support structure relative to the base to vary the inclination of the tunnel; and, the means for rotating the tunnel comprise motor means mounted on the support structure and means coupling the motor means to the tunnel such that the motor means rotate the tunnel.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 615317 CA1323764C (en) | 1989-09-29 | 1989-09-29 | Scrap freezing tunnel |
| PCT/CA1990/000332 WO1991005212A1 (en) | 1989-09-29 | 1990-09-28 | Scrap freezing tunnel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 615317 CA1323764C (en) | 1989-09-29 | 1989-09-29 | Scrap freezing tunnel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1323764C true CA1323764C (en) | 1993-11-02 |
Family
ID=4140899
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 615317 Expired - Fee Related CA1323764C (en) | 1989-09-29 | 1989-09-29 | Scrap freezing tunnel |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1323764C (en) |
| WO (1) | WO1991005212A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1286442B1 (en) * | 1996-12-05 | 1998-07-08 | Pugnale S R L | APPARATUS FOR CONTINUOUS FREEZING OF FOOD PRODUCTS |
| WO2011106103A1 (en) | 2010-02-25 | 2011-09-01 | Langley J Barton | Method and apparatus for chilled water injection |
| US9089149B2 (en) | 2013-03-15 | 2015-07-28 | Cooling & Applied Technology, Inc. | Poultry chiller with multi-blade long-pitch auger |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3992899A (en) * | 1974-05-31 | 1976-11-23 | Messer Griesheim Gmbh | Device for cooling bulk material by low-boiling liquefied gas |
| US4084387A (en) * | 1975-06-17 | 1978-04-18 | The Union Corporation | Apparatus and process for refrigerating materials |
| DK452378A (en) * | 1977-10-12 | 1979-04-13 | M Tucek | SCRAP TREATMENT PROCEDURE |
| GB2131142B (en) * | 1982-10-29 | 1986-03-05 | Air Prod Ltd | Food freezing tunnels |
| US4569204A (en) * | 1985-03-11 | 1986-02-11 | Aga, A.B. | Method and apparatus for simultaneously cooling and conveying a food substance |
| US4578957A (en) * | 1985-06-18 | 1986-04-01 | Cunningham Larry L | By-products chiller and method for using same |
| GB2225846A (en) * | 1988-12-09 | 1990-06-13 | Air Prod & Chem | Tunnel freezer |
-
1989
- 1989-09-29 CA CA 615317 patent/CA1323764C/en not_active Expired - Fee Related
-
1990
- 1990-09-28 WO PCT/CA1990/000332 patent/WO1991005212A1/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| WO1991005212A1 (en) | 1991-04-18 |
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| MKLA | Lapsed |