Coaxial cryogenic injection system

A vacuum tumble mixer is provided with a hollow drive shaft at one end thereof. The hollow drive shaft provides access by means of a probe to the cylindrical center section of the vacuum tumble mixer in order to inject the ingredients to be mixed, to introduce cooling material such as liquid nitrogen or carbon dioxide, and finally to permit cleaning fluids to be circulated about the interior of the tumbler while the tumbler is rotating. The use of the hollow shaft greatly improves the efficiency and operation of the tumbler for vacuum massaging and tumble chilling of meat, poultry, seafood and other products that are mixed at the commercial level.

BACKGROUND OF THE INVENTION 
This invention relates to food mixing machines, and more particularly, to 
the access and chilling system for use in such machines. 
Vacuum tumblers are large, cylindrical drums which are positioned with the 
cylinder access in a horizontal orientation or nearly horizontal 
orientation. Vacuum tumblers which are used to tumble massage meat, 
poultry and seafood products with a marinade are rotated about their axes. 
Integral with the tumbling process is the use of a vacuum to remove air in 
the meat and replace it with the associated marinade. Once the product is 
properly mixed, an additional and important use of the tumbler is to chill 
the product down to or near the freezing point of the meat cells in order 
to stiffen the meat so that it will retain a formed shape for cooking. 
Vacuum tumblers of the type disclosed herein are similar to that disclosed 
in U.S. Pat. No. 5,104,232, which is assigned to the assignee of this 
invention. Such tumblers as described in the aforesaid patent may be 
designed with doors at one or both ends. The two-door version uses one of 
the doors for loading and the other for unloading. The one-door tumbler 
generally has a drum drive shaft welded or affixed at the end opposite the 
single door. The two-door tumbler is supported by drive wheels which 
rotate the drum by friction. Similar idler type wheels may be utilized in 
the axially driven drums in order to support the weight of the rotating 
drum. 
A major use for vacuum tumblers is to chill the product for forming into 
shapes such as nuggets or patties before cooking. In order to make the 
meat stiff enough to form meat shapes out of small pieces of chicken, 
beef, or pork, it is necessary to chill down the meat so that thirty to 
forty percent of the meat cells are frozen. This is generally done by 
spraying a liquid cryogenic material such as liquid nitrogen or liquid 
carbon dioxide onto the meat. Utilizing this conventional system, the 
process chills down the drum, causing condensed water and frost to form on 
the outside of the drum. In the case of drive wheel drums, the slippery 
drum surface makes rotating the drum by friction very inefficient. 
Generally speaking, tumblers that are designed for chilling are 
direct-driven through a welded-on drive shaft and associated gearing or 
chain drive. These chilling tumblers are therefore restricted to having 
only one door. 
In the one-door version, all the ingredients and additives must enter the 
single door to the vacuum tumbler through the door opening on the end 
opposite the tumbler drum drive shaft. In a large facility where meat is 
processed in batches of thousands of pounds, the single door type tumbler 
results in extreme congestion around the single door. This is caused 
because it is the only point at which product can be positioned in the 
tumbler. Carts or bins of product weighing between 400 pounds (180 kg) and 
2,000 pounds (900 kg) must be lifted and poured or dumped into the tumbler 
drum through this single opening. The lift mechanisms, of course, are 
heavy and difficult to move. 
The product must also be discharged through the same opening, up to 4,000 
pounds (1800 kg) of product into the same 400 pound (180 kg) bins, one 
after another. With 30 inch (75 cm) diameter vacuum doors, the door is 
hinged and swung closed. Since the door is designed for a full vacuum, it 
is heavy and clumsy and requires a great deal of space to move into 
position. 
At the same time, the tumbler must be provided with a means to inject 
liquid carbon dioxide or liquid nitrogen for chilling the product to make 
the formed shapes. This requires a second door to be moved into position. 
This door generally does not rotate with the drum as does the vacuum door 
as the stationary door not only contains the entry point for the liquid 
carbon dioxide or nitrogen, but it also contains a vent hose to vent away 
the cryogenic gas. Since the large vent hose must be permanently connected 
to the outside of the building, the vent door cannot rotate with the drum 
as does the vacuum door. This vent door is even more difficult to position 
than the vacuum door because the vent hose is attached. For cryogenic 
chilling, a long probe is attached to the door to reach into the drum so 
that nitrogen or carbon dioxide can be injected through the probe. 
Nitrogen or carbon dioxide cryogenic flashes from a liquid into a gas very 
rapidly when it is sprayed into the atmosphere. Since the chilling 
efficiency is enhanced if the cryogenic nozzles are positioned close to 
the product during the injection and chilling processes, the probe should 
be long enough to reach the back of the drum where the product tumbles in 
the existing type drums, as disclosed in U.S. Pat. No. 5,104,232. In a 
production size tumbler, the nitrogen probe would have to be six to eight 
feet long, which is not practical since the probe must be removed after 
chilling each batch, two or three times per hour, to make room for 
connecting the vacuum door for the next batch. The longer the probe, the 
more difficult it is to keep it adjusted, the more room it takes up when 
it is retracted, and the more complicated the mechanism it requires to 
retract it. For these reasons, the probe has been designed quite short in 
existing production models, thereby reducing the efficiency of the cooling 
process. 
One method that has been tried is to position the nitrogen injection probe 
on a track that moves in directly from in front of the door. In addition 
to being expensive, the probe mechanism takes up an enormous amount of 
valuable factory floor, not to mention the fact that the space is right in 
front of the loading and unloading area described above. 
A second method is to rotate the nitrogen door and probe down from above 
the tumbler drum utilizing the head space above the machine. This solution 
improves the congestion in the critical area in the front of the door of 
the machine; however, the enormous mechanism required to rotate and 
position the probe system down from above the drum is very expensive and 
very difficult to keep in adjustment. 
Both of the above systems result in poor efficiency and chilling with 
liquid nitrogen and carbon dioxide. Due to the need to keep the length of 
the probe short to minimize the retracted space problem, the spray nozzles 
end up too far from the product tumble zone. As a result, the majority of 
the cryogenic liquid flashes into gas rather than the droplets being 
sprayed onto the surface of pieces of the product and freezing onto the 
surface without flashing to gas. 
When the cryogenic flashes to gas without making contact with the product, 
the gas freezes everything it contacts. The chilling efficiency is 
therefore reduced, creating a number of production problems, including 
freezing the stainless steel drum as well as the product pieces. In some 
instances, the product pieces will stick to the inside of the tumbler drum 
so that the stuck pieces remain in the drum after the product is 
discharged. To minimize the sticking problem, water is sprayed on the 
outside of the drum to keep the steel from reaching a temperature below 
freezing. The use of water in this way is expensive and messy, requiring 
expensive drainage systems and, in order to preclude wastage of water, a 
recirculating system. Since the purpose of the water spray is to heat up 
the tumbler drum to prevent it from freezing, more liquid nitrogen must be 
used to achieve the chilling. In those instances Where the chilling 
capacity of the liquid cryogenic is partially wasted on heating the steel 
drum by the water sprayed on the surface of the steel drum, substantially 
more cryogenic is required to chill the product. Since more cryogenic 
liquid is necessary and this liquid can only be sprayed on the product at 
a limited rate and still evenly coat the product pieces, it takes a longer 
time to chill the product. This reduces the utilization of the expensive 
machine, requiring more capital investment for more machines. 
One of the problems with existing tumble mixers is associated with cleaning 
the interiors thereof. The vane system used to tumble the product is 
difficult to clean, with the back side of the vanes particularly hard to 
reach. Accordingly, in the larger tumble mixers, it is almost routine for 
an individual to climb inside the drum in order to perform a cleaning 
operation. Generally speaking, the individual carries therewith a hose or 
other cleaning material to accomplish the cleaning chore. 
This invention overcomes the objections to the previous tumbler drums. In 
particular, it is an object of this invention to provide an 
axially-mounted, removable probe to provide material to the interior of a 
tumbler drum while the drum is rotating. 
It is a further object of this invention to provide a probe system wherein 
a cryogenic liquid may be provided to the interior of a tumbler drum. 
It is also an object of this invention to provide a probe system that may 
be used to provide product to be processed to the interior of a tumbler 
drum. 
It is still another object of this invention to provide a probe system for 
a tumbler drum that can be used for cleaning. 
It is also an object of this system to provide a probe system that can be 
utilized while the drum is rotating. 
It is a further object of this invention to provide a probe system that is 
interchangeable so that a product supply probe can be replaced with a 
cryogenic probe, which in turn may be replaced with a cleaning probe. 
Briefly stated, the invention comprises a tumble mixer having a rotatable 
drum with a horizontal axis. The rotatable drum includes a cylindrical 
midsection with an entry and discharge end section. The entry and 
discharge end section has an axial opening. The rotatable drum further 
includes a service access end section affixed to the rotatable drum at the 
end opposite the entry and discharge end section. Said service access end 
section is aligned axially with the rotatable drum axis. A material 
communication probe for providing material to the rotatable drum is also 
included. The service access end section defines an axially-aligned 
sealable entry for removably positioning the material communication probe 
within the cylindrical midsection whereby material can be communicated to 
the interior of the rotatable drum while the drum is rotating. Also 
included is the capability to rotate the drum by a drive member drivingly 
connected to the service access end.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A tumble mixer 10 is illustrated in FIG. 1. Tumble mixer 10 includes a 
rotatable drum 12. In the embodiment shown in FIG. 1, tumble mixer 12 is 
axially supported by a drive mechanism 14 which provides the capability to 
rotate drum 12 about its axis 16 shown by a conventional center line. In 
the embodiment depicted in FIG. 1, a support roller 18 is illustrated. 
Support roller 18 may comprise several rollers in order to prevent undue 
strain on the drive mechanism. In relatively small tumble mixers, of the 
type used in laboratories, the support roller 18 has been found to be 
superfluous as the drive mechanism can be adequate to support the drum. 
A frame 20 supports the entire structure, with the drive mechanism 
supported by an upstanding member 22. 
The structure of the rotatable drum 12 is best described in U.S. Pat. No. 
5,104,232, which illustrates the vane structure for moving and massaging 
the product that is positioned within the drum. U.S. Pat. No. 5,104,232 is 
incorporated herein for reference in its entirety. 
In FIG. 1, a rotatable drum is shown with a sealable vacuum door 24 
positioned at one end of the rotatable drum. Specifically, the vacuum door 
closes an entry and discharge end section wherein product may be 
positioned in the drum or removed from the drum. It is noted for reference 
purposes that this invention also includes means for introducing product 
through the opposite end of the drum by a probe mechanism. However, the 
discharge end section 26 can also be utilized for positioning product 
within the drum. A vacuum source 28 and conduit 30 provide means for 
drawing a vacuum within drum 12. In addition, an appropriate valve 32 and 
a swivel type joint 34 interconnect the vacuum source 28 with the vacuum 
door 24. Swivel joint 34 permits rotation of drum 12 while a vacuum is 
being maintained in the drum. Vacuum door 24 may be positioned on hinges 
(not shown), or may simply be a removable member that can be stored at 
another site during the loading and cooling processes of this drum. 
Referring to FIG. 2, the same tumble mixer 10 is illustrated, but in this 
instance with a vent door 36 positioned at the entry and discharge end 
section 26. Vent door 36 includes a vent 38 which is connected to a 
flexible conduit (not shown) that will vent the gaseous contents of 
rotatable drum 12 to the atmosphere. Preferably, the vent system vents the 
cryogenic gases used in cooling (to be described) to the outside of the 
building which contains the tumble mixer. Vent door 36 as described in 
U.S. Pat. No. 5,104,232, does not rotate with drum 12, but rather remains 
stationary. While positioned on hinges 40, it can also be completely 
removable. 
It is pointed out that vacuum door 24 does rotate with the drum and the 
rotation is taken up by the swivel 34 so that conduit 30 does not rotate 
with the drum. 
Having described the essential points of previous tumble mixers, it is 
appropriate to point out at this stage that in the present devices, entry 
and discharge of material is performed through entry and discharge end 
section 26. Generally speaking, this is performed by either a loading 
chute (not shown) or by hand loading with shovels and the like. 
The invention herein lies at the opposite end of tumble mixer 10. 
Specifically, drive axle 42 is hollow, defining a hole 44 through its 
entire length. Through hole 44, a probe for providing material such as 
cryogenic or nitrogen probe 46 may be introduced to the interior of the 
drum 12, which is shown broken away in FIGS. 1 and 2. Nitrogen probe 46 is 
supported at the end closest the nozzle 48 by a guide bushing 50. At its 
opposite end, probe 46 includes a sanitary rotary joint 52 that 
interconnects with the hollow shaft or axle 42. Thus, probe 46 is 
supported at both ends within the hollow shaft or axle 42. A liquid 
cryogenic source 54, preferably nitrogen, is provided with this invention, 
along with a conduit 56 which includes a flexible coupling. Appropriate 
valving 59 is provided to control the flow of liquid nitrogen through 
probe 46 and nozzle 48 to the interior of tumble mixer 10. 
Nozzle 48 is configured so that liquid nitrogen or whatever cryogenic 
material is used is generally directed to the rear of the rotatable drum 
12, the rear being to the left as seen in FIG. 1. 
Referring now to FIG. 5, probe 46 is vacuum jacketed, that is, there is an 
internal hollow tube 58 that is mounted within an outer cylindrical member 
60 which is sealed at one end to nozzle 48 and sealed at the other end to 
the sanitary rotary joint 52. The tube 58, of course, runs from the 
sanitary rotary joint 52 (available from Thomsen in Kenosha, Wis.) through 
to the nozzle 48. A vacuum is permanently established between the inner 
tube 58 and the outer jacket 60 so that liquid nitrogen which is passed 
through tube 58 does not flash into a gaseous state until it is released 
from nozzle 48. 
Hollow shaft 42 is supported on upstanding member 22 by two shaft support 
bearings 62 and 64. 
Drive mechanism 14 preferably includes a motor 66 and a gear box 68 which 
has a reversing capability. The drive from gear box to hollow shaft 42 is 
conventional in nature and can be either a direct geared connection (shown 
schematically in FIG. 2) or, in larger installation, a chain and sprocket 
connection (shown schematically in FIG. 1). 
Referring to FIGS. 3 and 4, two alternative probes for providing material 
to drum 12 are shown which are used in conjunction with nitrogen probe 46. 
First, in FIG. 4, a product probe is illustrated. In most instances, the 
product associated with this tumble mixer will be a meat product such as 
beef, chicken, pork or the like, which is mixed in rotatable drum 12 with 
a marinade, i.e., seasoning. Thus, probe 70, through which chopped meat or 
poultry is transported, could include a feed screw 72 type device which, 
in a manner of a conventional helical feed mechanism, will force the 
product through probe 70. A product source 74 may be loaded in any manner 
convenient to the user. It is pointed out that produce probe 70 includes a 
guide bushing 50' and a sanitary rotary joint 52' in a manner similar to 
the nitrogen probe described above. Thus, the product probe as shown in 
FIG. 4, with the removal of the nitrogen probe from the hollow shaft, may 
simply be inserted through hollow shaft 42 and product fed into the drum. 
Once the product is in the drum, the product probe may be withdrawn and 
the nitrogen probe replaced for appropriate use to be described. 
Also included in the invention is a third material probe in the form of 
cleaning probe 76 which is also configured in a manner similar to the 
nitrogen probe. In FIG. 3, cleaning probe 76 has at one end a nozzle 78 
that includes a plurality of holes 80 that would spray a cleaner around 
the interior of rotating drum 12. Cleaning probe 76 also includes the 
guide bushing 50" and the sanitary joint 52". Thus, it is in effect a 
duplicate of the nitrogen probe, except that it is provided with a source 
of cleaner 82 which may include hot water and some cleaning solution. 
Both product probe 70 and cleaner probe 76, along with the nitrogen probe 
46, are sufficiently lightweight so that they may be readily removed from 
hollow shaft 42 and replaced one with another without undue difficulty, 
nor do they take up sufficient space to hinder the operation of the tumble 
mixer. 
Operation of the tumble mixer should be apparent to those skilled in the 
art; however, the following description is provided for convenience's 
sake. Should the user elect to load the tumble mixer 12 through the probe 
70, then the probe 70 is first inserted into the hollow shaft 42 and 
product is forced therethrough by feed screw 72 or the like. 
Alternatively, product may be loaded into the tumble mixer through entry 
and discharge end section 26, which has been the procedure in the prior 
art devices. 
Once the product is loaded, the product probe 70 is withdrawn and the 
nitrogen probe 46 is inserted through the hollow shaft 42. Initially, 
vacuum door 24 closes the entry and discharge end section 26 in the 
conventional manner and a vacuum is drawn within the rotatable drum 12 by 
means of the vacuum pump 28. Once sufficient vacuum is drawn on the 
rotatable drum 12, rotation of the drum can commence. The purpose of the 
vacuum, as is well known in the art, is to permit the marinade which is 
placed with the product in the drum to penetrate the pores of the product, 
be it meat or poultry or the like. During this phase of the operation, the 
drum is rotated with the vacuum pump 28 still maintaining a vacuum within 
the drum. After a sufficient period of time, the massaging and marinating 
of the meat has been accomplished and the drum may be stopped so that 
vacuum door 24 can be replaced with vent door 36 as shown in FIG. 2. With 
vent door 36 in position, the rotation starts again of the rotatable drum 
12 and the cryogenic liquid, preferably liquid nitrogen but alternatively 
liquid carbon dioxide, is passed through nitrogen probe 46 into the 
interior of rotatable drum 12. The rotatable drum 12, having vanes in the 
manner of that described in U.S. Pat. No. 5,104,232, will cause the 
product to accumulate at the drive end or left end of the drum as shown in 
FIG. 1. The liquid nitrogen is directed generally at that direction, with 
the probe being positioned toward the left end of the drum, that is, away 
from the entry and discharge end section. Rotation of the rotatable drum 
12 continues until the temperature of the product contained therein 
reaches the desired point, at which time rotation stops. During the 
chilling portion, that is, the portion of the time while liquid nitrogen 
is being applied to the interior of the drum, the gaseous nitrogen which 
of course accumulates within the drum is vented by means of vent 38 to the 
atmosphere. 
Once the chilling is complete, the vent door 36 can be removed and, by 
reversing the drum, the veins described in U.S. Pat. No. 5,104,232, will 
force the product out through the entry and discharge end section 26 into 
appropriate loading and unloading carts. 
At this point, cleaning may take place in between cycles by removing the 
nitrogen probe and replacing it with the cleaner probe 76 as shown in FIG. 
3. Alternatively, the nitrogen probe can be withdrawn and, without 
cleaning the product, probe 70 can be inserted in its place for the 
insertion of additional product and the beginning of a second cycle. 
Most significantly, there is a distinct reduction in time for chilling 
product and the reduction of the amount of liquid cryogenic material 
required to chill a batch of product. Tests have indicated that the time 
for chilling is reduced by 30 to 35 percent over the existing systems, and 
the savings in cryogenic is from seven to 12 percent. Further, since the 
cryogenic is sprayed directly onto the product, less cryogenic is required 
to chill a product and the stainless drum does not freeze up so that no 
water is required to keep the drum warm. Without water, very little 
product freezes to the inside of the drum. 
Finally, in using the cleaning probe, it has been found that the back sides 
of the tumbler vanes (not shown) could not be cleaned with the 
conventional spray through the single door, that is, the front opening 
device in the prior art. This therefore necessitated a worker climbing 
inside the drum to clean the backs of the tumbler vanes. Not only does the 
instant invention reduce Labor costs, it is infinitely better from a 
safety standpoint. 
While this invention has been described with some particularity in the 
specification, it is to be considered limited only by the appended claims.