WO2011149701A2

WO2011149701A2 - Apparatus and method for providing a temperature-controlled gas

Info

Publication number: WO2011149701A2
Application number: PCT/US2011/036722
Authority: WO
Inventors: Daniel James Gibson; Marna Beth Schmidt; Michael Robert Himes
Original assignee: Air Products And Chemicals, Inc.
Priority date: 2010-05-27
Filing date: 2011-05-17
Publication date: 2011-12-01
Also published as: TW201200288A; WO2011149701A3

Abstract

A method and apparatus for directing gas at cryogenic temperatures onto at least some of the contact surfaces of machinery used in a cutting process. The gas is supplied at a relatively high flow rate (preferably exceeding 1000 SCFH) and at cryogenic temperatures (e.g., below -70 degrees C). The temperature at which the coolant gas is supplied is preferably maintained within ±5 degrees F (±3 degrees C).

Description

APPARATUS AND METHOD FOR

PROVIDING A TEMPERATURE-CONTROLLED GAS

BACKGROUND

[0001] The present invention is directed to cutting and grinding processes in which a cold gas at a controlled temperature is used to improve process performance.

[0002] There are many applications in which a material, such as a food product or elastomerics, thermoplastics, thermosets, semi-crystalline and other glassy plastics, biopolymers and other polymers, is subjected to a cutting process. For the purposes of the specification and claims, the term "cutting process" is intended to mean any process in which a material is broken into smaller pieces by contact with one or more mechanical surfaces and where the desired products of the process are pieces of uniform size or pieces having a consistent size distribution. Examples of cutting processes, include, but are not limited to, slicing, dicing, shredding, crushing, shearing, granulating and grinding. In many such applications, performing a cutting process on a material under ambient temperature conditions results in clogging of the machinery used to perform the cutting process, which requires the machinery to be taken out of service for cleaning. In addition, it is not uncommon for significant amounts of waste material to be generated by the cutting process.

[0003] One method of addressing with this problem is to reduce the temperature at which the material is supplied to the cutting process. Unfortunately, in many applications, a significant residence time is required to uniformly cool the material to a desired temperature. It is not uncommon for such cooling to take more than twenty-four hours. In addition, cooling the material often reduces, but does not eliminate, clogging of the machinery used for the cutting process because the processes themselves generate heat which, in turn, reheats the material which may lead to further clogging.

[0004] Freezing the material or chilling the material in a manner that results in a crust is problematic because it results in the frozen portion of the material shattering during the cutting process. In applications, such as slicing and dicing, where a product that is uniform in size and/or shape is desired, the shattered pieces will become waste material (referred to in the art as "fines"), which is undesirable. In many applications, supplying a frozen or crusted material can damage the contact surfaces, which is particularly problematic in food applications in which metal from contact surfaces could become mixed in with the product. In addition, a product that is frozen quickly or crust frozen will often have a relatively warm inner core which, when cut, has the potential to stick to contact surfaces of the cutting process.

[0005] Accordingly, there is a need for an improved system and method for performing a cutting process. This need is addressed by the embodiments of the invention described herein and by the claims that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a block diagram showing an exemplary coolant delivery system;

[0007] Figures 2A and 2B are examples of mixing tubes used with the coolant delivery system of Figure 1 and represent an enlarged partial view of area 2-2 of Figure 1 ;

[0008] Figure 3 is a flow chart showing an example of a method of controlling the coolant delivery temperature for the coolant delivery system of Figure 1 ;

[0009] Figure 4 is a sectional side view of one example of a vessel, dicer and coolant delivery system for dicing a food product;

[0010] Figure 5 is a top front perspective view of the dicer of Figure 4;

[0011] Figure 6 is a bottom front perspective view of the dicer of Figure 4;

[0012] Figure 7 is a table showing product buildup observed on the blades of a dicer at specific time intervals during two tests performed on the dicer using a fruit product;

[0013] Figure 8 is a table showing product buildup observed on the feed drum of a dicer at specific time intervals during two tests performed on the dicer using a fruit product;

[0014] Figure 9 is a table showing product buildup observed on the blades of a dicer at specific time intervals during two tests performed on the dicer using cheese slices; and

[0015] Figure 10 is a graph representation of the amperage draw of the dicer during two tests performed on the dicer using a fruit product.

SUMMARY OF THE INVENTION

[0016] In one respect, the invention comprises a method comprising: (a)performing a cutting process on a product using a cutting machine; and (b) directing a coolant gas at a cryogenic temperature onto at least one cutting surface of the cutting machine while step (a) is being performed. [0017] In another respect, the invention comprises a coolant delivery system including: a cryogen supply line that is connected to a source of a cryogen in liquid phase; a gas supply line that is connected to a source of a supply gas; a programmable logic controller that is in communication with at least one temperature sensor and is adapted to control the flow of the cryogen through the cryogen supply line; a mixing zone at which the cryogen from the cryogen supply line and the supply gas from the gas supply line are combined to form a coolant gas; and a coolant delivery device that is in flow communication with the mixing zone and downstream from the mixing zone, the coolant delivery device being capable of discharging the coolant gas at a rate of at least 28 SCMH, wherein the programmable logic controller is programmed to adjust the proportional valve maintain to maintain an actual temperature within a predetermined temperature range of a set-point temperature, the actual temperature being a function of temperatures measured by the at least one temperature sensor.

[0018] In yet another respect, the invention comprises an apparatus comprising: a cutting machine that is adapted to perform a cutting process on a product, the cutting machine having at least one cutting surface; and a coolant delivery system that is adapted to discharge a coolant gas through at least one coolant delivery device at a total flow rate greater than 28 SCMH and to maintain a discharge temperature of the coolant gas within 6 degrees C above and below a set-point temperature and each of the at least one coolant delivery device being positioned to direct the coolant gas onto one of the at least one cutting surface.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The ensuing detailed description provides preferred exemplary embodiments only, and is not intended to limit the scope, applicability, or configuration of the invention. Rather, the ensuing detailed description of the preferred exemplary embodiments will provide those skilled in the art with an enabling description for implementing the preferred exemplary embodiments of the invention. It being understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the invention.

[0020] To aid in describing the invention, directional terms may be used in the specification and claims to describe portions of the present invention (e.g., upper, lower, left, right, etc.). These directional terms are merely intended to assist in describing and claiming the invention and are not intended to limit the invention in any way. In addition, reference numerals that are introduced in the specification in association with a drawing figure may be repeated in one or more subsequent figures without additional description in the specification in order to provide context for other features. [0021] As used herein, the term "cryogen" is intended to mean a liquid, gas, or mixed-phase fluid having a temperature less than -70 degrees C. Examples of cryogens include liquid nitrogen (LI N), liquid oxygen (LOX), liquid argon (LAR), liquid helium, liquid carbon dioxide and pressurized, mixed phase cryogens (e.g., a mixture of LIN and gaseous nitrogen). As used herein, the term "cryogenic temperature" is intended to mean a temperature below -70 degrees C.

[0022] As used herein, the term "cutting machine" is intended to include any machinery used to perform a cutting process, as defined herein. Similarly, as used herein, the term "cutting surface" is intended to include any surface of a cutting machine that a product comes into contact with during the cutting process.

[0023] Applicants have discovered the directing gas at cryogenic temperatures onto at least some of the contact surfaces of machinery used in a cutting process can substantially improve performance of the cutting process. An important aspect of successful implementation of the invention is the ability to supply a gas (referred to herein as a "coolant gas") at a relatively high flow rate and at a low, controlled temperature. In some embodiments, it is preferable for gas to be supplied at temperatures below -70 degrees C and at a flow rate exceeding 1000 standard cubic feet per hour (SCFH), which is equivalent to 28 standard cubic meters per hour (SCMH). It is also preferable that the temperature at which the coolant gas is supplied be able to be maintained within ±10 degrees F (±6 degrees C) and, more preferably, ±5 degrees F (±3 degrees C).

[0024] Referring to Fig. 1 , an exemplary coolant delivery system 1 is shown. The coolant delivery system 1 comprises cryogen supply line 14 and a gas supply line 12, which intersect at a mixing zone 35 and are then supplied to a vessel 50. A cryogen is supplied to the cryogen supply line 14 by a storage vessel, which is a tank 1 1 in this embodiment.

[0025] In this embodiment, gas for the gas supply line 12 (hereinafter "supply gas") is also supplied by the tank 1 1 . The cryogen is separated into liquid and gas phases by a phase separator 16. A vaporizer (not shown) is preferably positioned around the interior perimeter of the tank 1 1 and feeds the gas phase to the phase separator 16. In this embodiment, the tank 1 1 provides a supply pressure of about 100 psig (7.0 kg/cm²). The liquid phase is fed into the cryogen supply line 14, which is preferably controlled with a proportional valve 22. The gas phase is fed into the gas supply line 12, which preferably includes an on/off valve 15. In order to provide additional operational flexibility, a proportional valve (not shown) could optionally be provided instead of the on/off valve 15. Supply gas flows from the on/off valve 15 to a mixing zone 35 via a gas supply line 26. [0026] In alternate embodiments, the gas supply line 12 could be supplied with pressurized gas from a source other that the tank 1 1 . For example, a separate tank (not shown) could be provided or a pump (not shown) could be used. In order to avoid condensation and/or frost formation in the coolant delivery system 1 , it is preferable that dry gas (e.g., less than 30% relative humidity) be supplied to the gas supply line 12.

[0027] In this embodiment, the cryogen is liquid nitrogen (LI N) and the supply gas is gaseous nitrogen (GAN). The GAN is preferably supplied at a consistent temperature, and is preferably supplied at a higher pressure than the pressure at which the cryogen is supplied. A pressure differential of 20 - 30 psi (138 - 207 kPa) is preferable. All pressure values provided in this application should be understood as referring to relative or "gauge" pressure.

[0028] In order to avoid condensation or freezing of the supply gas, it is preferable that the supply gas have a boiling point that is no higher than the temperature operating range for the coolant delivery system 1 . More preferably, the supply gas has a boiling point that is no higher than the boiling point of the cryogen. In some applications, it is also preferable for the supply gas and the cryogen to have the same chemical composition (as is the case in this embodiment) so that the chemical composition of the air inside the vessel 50 does not change as the flow rate of the cryogen is varied for reasons discussed herein.

[0029] LI N flows through the cryogen supply line 14, into a pressure regulator 21 , through a proportional valve 22, through a distribution line 27, and into a mixing zone 35. The proportional valve 22 is preferably controlled by a programmable logic controller (PLC) 23. Alternatively, any suitable process controller could be substituted for the PLC. The PLC is preferably adapted to communicate with a user panel 24. As will be described in greater detail herein, the PLC 23 can adjust the proportional valve 22 for the purpose of increasing or decreasing the flow rate of the cryogen in the distribution line 27. In other embodiments, other types of proportional fluid control devices could be substituted for the proportional valve 22.

[0030] The proportional valve 22 is described herein as being used to regulate the temperature of the coolant gas that is supplied to the vessel 50. As used herein, the term "flow rate" should be understood to mean a volumetric flow rate. It should further be understood that the proportional valve 22 is adjusted by increasing or decreasing the size of the opening through which the cryogen flows, which causes a corresponding increase or decrease, respectively, in the flow rate of cryogen through the opening. Increasing the size of the opening also decreases the pressure drop across the proportional valve 22, and therefore, increases the pressure of the cryogen downstream of the proportional valve 22. Conversely, decreasing the size of the opening increases the pressure drop across the proportional valve 22, and therefore, decreases the downstream pressure of the cryogen. Therefore, due to the direct proportional relationship between flow rate and downstream pressure of the cryogen, adjusting the proportional valve 22 regulates both the flow rate and the pressure at which the cryogen is provided to the mixing zone 35. In addition, due to this direct proportional relationship, the supply characteristics of the supply gas and cryogen may be described herein in terms of either their respective flow rates or their respective pressures.

[0031] The cryogen that flows through the cryogen supply line 14 and through a pressure regulator 21 , in this embodiment, maintains the cryogen at an operating pressure in the range of 60 to120 psi (414 to 827 kPa) and, preferably, at about 80 psi (552 kPa).

[0032] As noted above, the flow of supply gas intersects the flow of the cryogen at the mixing zone 35. The purpose of the mixing zone 35 is to enable the supply gas and cryogen to mix in a relatively uniform fashion. Figures 2A and 2B show two examples of mixing zone configurations. In the mixing zone 35, shown in Figure 2A, the gas supply line 26 comprises a tube that intersects the distribution line 27, then includes an elbow 42 which orients the flow of supply gas exiting the gas supply line 26 roughly parallel to the flow of cryogen in the distribution line 27. The tube may be a copper tube, for example. Mixing zone 35 is intended for applications in which the GAN flow rate and the desired coolant gas temperature are relatively low (i.e., below 32 degrees F / zero degrees C).

[0033] Mixing zone 135, shown in Figure 2B, is intended for applications in which the GAN flow rate and desired coolant gas temperature are relatively high (i.e., above 32 degrees F / zero degrees C). In mixing zone 135, the distribution line 127 intersects the gas supply line 126 at a right angle. In this embodiment, the distribution line 127 preferably has a smaller diameter than the gas supply line 126 in the mixing zone 135.

[0034] Referring again to Figure 1 , after intersecting at the mixing zone 35, the supply gas and the cryogen form a coolant gas, which flows through a delivery line 44 and is discharged through a coolant delivery device 48 into the vessel 50. The coolant delivery system 1 is preferably operated so that the coolant gas includes little or no liquid phase when it is discharged through the coolant delivery device 48. The temperature of the coolant gas will depend upon several factors, including, but not limited to, the temperatures and pressures (which, as explained above, are related to flow rates) at which the supply gas and cryogen are supplied to the mixing zone 35.

[0035] In this embodiment, a temperature probe 36 is positioned within the vessel 50 and is part of a thermocouple. The temperature probe 36 is configured to transmit continuous real time temperature measurements to the PLC 23. It should be understood that other temperature monitoring methods may be used in other embodiments without departing from the scope of the present invention. For example, optional temperature sensors (not shown) such as diodes, resistance temperature detectors, infrared sensors, and capacitance sensor thermometers, for example, may be used to monitor the surface temperature of the product (before and/or after the cutting process), exhaust temperature, or contiguous atmosphere temperature, for example. In such an instance, the optional temperature sensors could transmit a stream of data to the PLC 23, as described in this embodiment.

[0036] Operation of the cryogenic coolant delivery system 1 begins by determining a target or set-point temperature for the vessel 50. The value of the set-point temperature, as well as how and where it is measured, will depend upon the process being performed in the vessel. For example, the set-point temperature could be a desired air temperature within the vessel 50, a desired air temperature in an exhaust stack (not shown) of the vessel 50, or a desired surface temperature of a product as it enters or exits the vessel 50.

[0037] In this embodiment, the desired set-point temperature is entered into the user panel 24 by an operator and the set-point temperature is communicated to the PLC 23. In this embodiment, the set-point temperature can range from between about -265 degrees F to about 85 degrees F (-165 degrees C to 29 degrees C). In alternate embodiments, the set-point temperature could be fixed or non-user adjustable. In such embodiments, the set-point temperature could simply be part of the programming of the PLC 23.

[0038] During operation of the cryogenic coolant delivery system 1 , if the temperature in the vessel 50, as measured by the thermocouple, deviates from the set-point, the PLC 23 is programmed to adjust the proportional valve 22 in order to bring the temperature in the vessel 50 back to the set-point temperature by adjusting the flow rate of the cryogen. Given that the composition, and therefore temperature, of the coolant gas is dependent, at least in part, on the pressure differential between the supply gas and the cryogen at the mixing zone 35, it is preferable that the flow rate (and pressure) at which the supply gas is supplied to the mixing zone 35 be as constant as possible.

[0039] In other embodiments, multiple temperature probes 36 could be used. In this case, deviation from the set-point could be determined a number of different ways. For example, the PLC 23 could be programmed to adjust the cryogen flow rate if any of the temperature probes 36 deviates sufficiently from the set-point, or the PLC 23 could be programmed to adjust the cryogen flow rate based on the average of the temperature probes 36.

[0040] In embodiments in which the set-point temperature is close to the vaporization temperature of the coolant gas, it is preferable to position at least one temperature probe in the mixing zone 35, just downstream from the end of the gas supply line 26. Positioning the temperature probe in the mixing zone 35 reduces the likelihood that any liquid would remain in the coolant gas when it exits the coolant delivery device 48. In such an embodiment, the set- point temperature would be based, at least on part, on temperature readings from the temperature probe located in the mixing zone 35.

[0041] A flow chart showing an example of a method used by the PLC 23 to control coolant gas temperature is shown in Figure 3. When the PLC 23 receives a temperature reading from the thermocouple, it determines the difference between the measured temperature and the set- point temperature and compares the difference to the predetermined range (see step 60). If the difference is not greater than the predetermined range, no adjustment of the proportional valve 22 is made by the PLC 23 (see step 61 ).

[0042] If the difference is greater than the predetermined range, the PLC 23 determines if the measured temperature is greater than the set-point temperature (see step 62). If so, the PLC 23 begins adjusting the proportional valve 22 to increase the flow rate of the cryogen (see step 64) until the measured temperature of the coolant gas drops to the set-point temperature (see step 66). If not, the PLC 23 adjusts the proportional valve 22 to decrease the flow rate of the cryogen (see step 68) until the measured temperature of the coolant gas rises to the set-point temperature (see step 70). When the measured temperature is equal to the set-point temperature, adjustment of the proportional valve 22 is stopped (see step 72).

[0043] A time delay (step 74) is preferably provided between each temperature measurement. The time delay steps and the predetermined range are intended to prevent constant adjustment of the proportional valve 22. The magnitude of the time delay and predetermined range will depend, in part, upon the acceptable temperature variation in the vessel 50.

[0044] If it is desirable to maintain a set-point temperature within an acceptable temperature range (a first predetermined range), it is preferable that the predetermined range of step 60 (a second predetermined range) be no greater than the acceptable temperature range and, more preferably, less than the acceptable temperature range. For example, if an application requires that the temperature measured by the thermocouple be within 5 degrees F (2.7 degrees C) of the set-point temperature, a predetermined range of two degrees F (1 .1 degrees C) could be used.

[0045] Based on testing of a prototype of cryogenic coolant delivery system 1 , the system is able to maintain temperature in a vessel within 1 degree F (0.6 degrees C) above or below a set temperature when operating at set temperatures above 32 degrees F (zero degrees C). The system 1 was able to maintain temperature in a vessel within 5 degrees F (2.8 degrees C) above or below a set temperature when operating at a set temperature of -150 degrees F (-101 degrees C).

[0046] In addition, the coolant delivery system 1 is capable of delivering coolant gas to a vessel at a flow rate of 5000 standard cubic feet per hour, while maintaining the above- referenced temperature control characteristics. This high flow rate capability enables the coolant delivery system 1 to be used in applications requiring a gaseous coolant at higher flow rates. In addition, the high flow rate capability provides for reduced vessel startup times and reduced temperature fluctuations under changing vessel conditions (e.g., when a material is first introduced into the vessel 50 or in applications in which the feed rate of the material varies substantially).

[0047] Figure 4 shows an exemplary embodiment in which a coolant gas is used to improve performance of a cutting process. In this embodiment, a food product (not shown) is transported through a vessel 150, then processed by a dicer 170. The vessel 150 comprises a chamber 160 through which the product is moved on a conveyor 162 and a coolant delivery device 148 located at the top of the chamber 160. The coolant delivery device 148 comprises a manifold of tubes having holes facing the conveyer 162. The primary components of the dicer 170 are a hopper 172, a feed drum 174, a feed spindle 176, blades 178, stripper bars 180 and an exit chute 182. Additional views of the dicer 170 are shown in Figures 5 and 6.

[0048] Returning to Figure 4, when the cutting process is performed, the food product is transported by the conveyer 162 and into the hopper 172. The food product is then drawn into the dicer 170 by the feed drum 174 and feed spindle 176 and cut by the blades 178. The stripper bars 180 rest against the blades 178 and assist in separating the food product from the blades 178 as it is drawn downwardly by the feed drum 174. The dicer 170 may optionally include crosscut blades (not shown), which would be positioned below the blades 178.

[0049] A coolant delivery system 100 is also provided and is substantially similar to the coolant delivery system 1 shown in Figure 1 . The coolant delivery system 100 is used to supply coolant gas to the dicer 170 and, optionally, to the vessel 150. In this embodiment, the coolant gas is GAN, which is supplied via copper tubing having holes facing the component to be cooled. A first portion of tubing 184 is positioned above the feed drum 174. A second portion of tubing 186 is positioned on the front side of the blades 178 and a third portion of tubing 188 is positioned below the stripper bars 180. When the dicer 170 is operated and, optionally, prior to beginning operation of the dicer 170, the coolant delivery system 100 supplies coolant gas to the copper tubing, which causes GAN to flow to the feed drum 174, blades 178 and stripper bars 180. The flow of GAN also cools the entire interior of the dicer 170. [0050] The ability of the cooling delivery system 100 to deliver GAN at controlled cryogenic temperatures without discharging any significant cryogenic liquid is important to the performance of the cutting process. Any discharge of cryogenic liquid onto the contact surfaces of the dicer 170 could cause damage or undesirable performance. For example, the blades 178 are relatively thin and made of stainless steel. Discharging a cryogenic liquid onto the blades 178 during a cutting operation could cause the blades 178 to crack or fracture. In addition, the discharge of a cryogenic liquid is undesirable in cutting processes in which food is being cut because many types of food become discolored or damaged when they come in contact with a cryogenic liquid.

[0051] Optionally, temperature feedback could be used to monitor the process and/or adjust the temperature at which the coolant gas is supplied. In the example shown in Figure 4, three temperature sensors are provided. A first temperature sensor 190 monitors the temperature of product as it enters the conveyor 162, a second temperature sensor 192 monitors the temperature of product as it exits the conveyor 162 and a third temperature sensor 194 monitors the temperature of product as it passes through the exit chute 182. All three of these sensors provide temperature information to the cooling delivery system 100, which uses the information to adjust the temperature and/or flow rate at which the coolant gas is supplied to the tubes 184, 186, 188.

[0052] For example, if the third temperature sensor 194 detects an increase in the temperature of the product as it exits the dicer 170 (as compared to the temperature at which the product enters the dicer 170, as measured by the second temperature sensor 192), the cooling delivery system 100 could be programmed to reduce the set-point temperature of the coolant gas and/or increase its flow rate. In addition, the operation of the coolant delivery system 100 could be controlled by a computer.

[0053] Based on tests performed using an Urschel model CD-A dicer to cut a dried fruit product, directing cold gas onto the contact surfaces that come in significant contact with the fruit product during the cutting process significantly reduced the production of "fines," i.e., food particles that are smaller than the desired cut size, and significantly reduced clogging of the dicer. Applicants also discovered that cooling the fruit product prior to the cutting process did not improve performance and, in some tests, increased the production of fines.

[0054] The method disclosed above for directing a coolant gas onto the contact surfaces could be implemented in a wide variety of types of cutting processes. For example, the coolant gas could be directed onto both sides of a cutting screen or a separating screen for a granulator. In addition, the method could be used in cutting processes used to cut products other than foods, such as recycle materials, elastomerics, thermoplastics, thermosets, semi- crystalline and other glassy plastics, biopolymers and other polymer materials.

[0055] The operating parameters for a cutting process in which coolant gas is directed onto at least some of the contact surfaces may vary widely and will depend upon many factors, such as, for example, the type of cutting machine being used, the physical properties of the product being processed (including its propensity to stick to contact surfaces), the temperature at which the product is provided to the cutting process, the rate at which the product is fed to the cutting process. Once these parameters are known, a preferred flow rate and temperature for the coolant gas can be determined and set. In the tests described above, it was found that providing the coolant gas at a temperature in the range of -94 to -265 degrees F (-70 to -165 degrees C) and, more preferably, in the range of -190 to -265 degrees F (-123 to -165 degrees C), provided significant improvement of the cutting processes tested.

[0056] Further benefits of directing a temperature-controlled coolant gas onto at least some of the contact surfaces of a cutting process include the ability to eliminate use of lubricants and/or flow agents. Examples of lubricants and flow agents include food grade oils to lubricate and prevent sticking during the cutting process and rice flour to prevent the product from sticking together and from sticking to the process equipment. The use of lubricants and flow agents is undesirable because of the potential to change the taste and/or appearance of the food product being processed and increase the costs associated with such processing.

[0057] Moreover, many cutting processes generate heat, which often results in warming of the product being processed. Such warming is often undesirable, and in some cases, may be harmful to the product. Use of the cold gas cooling can assure that the product exits the process at the same temperature as it entered and, in fact, can also be cooled further during the processing if necessary.

[0058] The following are examples of applications with which the coolant delivery system 1 can be used. In all five examples, GAN was used as the supply gas and LI N was used as the cryogen and the GAN temperatures recited were all measured by a temperature probe located in the mixing zone.

[0059] Example 1

[0060] In this example, a fruit product was supplied to a conveyor at a temperature above 80 degrees F (27 degrees C), then processed using an Urschel model CD-A dicer. 300 pounds (136 kg) of the fruit was processed in just over one hour. During processing, GAN was directed onto the blades, feed drum and stripper bars from quarter-inch inner diameter tubing. The cold GAN was supplied using the coolant delivery system 1 at a temperature of -285 degrees F (-176 degrees C) and an approximate flow rate of 3000 SCFH (85 SCMH). It should be noted that the GAN temperature at the mixing zone was below the vaporization temperature of nitrogen, but that any liquid present in the coolant gas vaporized before exiting the coolant delivery device. This was due, in part, to a relatively large distance between the mixing zone and the coolant delivery device. The temperature of the fruit product was reduced to about 51 degrees F (1 1 degrees C) at the exit chute. After running the dicer for over an hour, 70 - 80% of the blades remained clean and free of the fruit product, which represented a significant improvement over the performance of the dicer without cold GAN being directed onto the contact surfaces.

[0061] Example 2

[0062] In this example, a fruit product was supplied to a conveyor at a temperature above 80 degrees F (27 degrees C), then processed using a Stokes model 43-6 granulator. During processing, GAN was directed onto both sides of the cutting screen of the granulator from quarter-inch inner diameter tubing at a temperature of -200 degrees F (-129 degrees C). The cold GAN was supplied using the coolant delivery system 1 . Directing cold GAN directly onto the cutting screen significantly reduced clogging and smearing of the fruit product as compared to operation of the granulator without cold GAN.

[0063] Example 3

[0064] In this example, a fruit product was supplied to a conveyor at a temperature above 80 degrees F (27 degrees C), and processed using an Urschel model CD-A dicer. A baseline test was performed in which the fruit product was processed without any cooling for the components of the CD-A dicer. A second test was then performed in which the fruit product was processed and gaseous nitrogen was directed on the blades, feed drum, and stripper bars from an expression device comprising quarter inch diameter tubing, where the gaseous nitrogen was supplied at a temperature of -200 degrees F (-129 degrees C) and an approximate flow rate of 3000 SCFH (85 SCMH). The gaseous nitrogen was supplied using the coolant delivery system of Figure 1 . In each test, approximately 350 pounds (159 kg) of fruit product was processed over approximately a one hour period. During both tests, the amperage of the CD-A dicer motor (at 60 Hz and 460 volts) was measured and the amount of product buildup on the blades and drum of the CD-A dicer was observed at several time intervals.

[0065] As illustrated in Figure 7, after running the CD-A dicer for approximately one hour with gaseous nitrogen being directed onto the blades, 90% of the blade surfaces remained clean and free of the fruit products. In contrast, a 50% product buildup on the blades was observed during the baseline test (no use of gaseous nitrogen) after only 28 minutes. [0066] As illustrated in Figure 8, similar results were observed with respect to the feed drum of the CD-A dicer. In the baseline test, the feed drum became completely covered with layers of fruit product paste and were so thick that the safety covers that protect internal components of the CD-A dicer began shaving off the fruit paste. In second test, only 2 to 5 thousands of an inch (.051 to .127 millimeters) of fruit product had collected on the drum at the end of the test.

[0067] A graph showing the amperage data collected from both tests is shown in Figure 10. During the first 20 minutes, the amperage of the CD-A dicer motor during the baseline test was slightly lower or the same as the amperage of the CD-A dicer motor during the second test. After 20 minutes, however, the amperage use of the CD-A dicer motor during the baseline test was significantly higher than the amperage use of the CD-A dicer motor during that same time period of the second test. This suggests that product build-up on the blades and inefficiency of the cutting or dicing from such build up resulted in higher consumption of power in the baseline test.

[0068] One surprising positive result of the second test was a reduction in the amount of fines or wasted fruit product resulting from the processing of the food product using gaseous nitrogen. Using the gaseous nitrogen in the processing of the fruit product resulted in reducing the fines or wasted fruit product by 3% to 4% compared with the baseline test not using the gaseous nitrogen. Such reduction of the fines or wasted fruit product was calculated by determining the product weight loss resulting from the fruit product processing.

[0069] Example 4

[0070] In this example, a fruit product was supplied to a conveyor at a temperature above 80 degrees F (27 degrees C), and then processed using an Urschel model LA dicer. Approximately 1730 Ibs/hr of fruit product was processed for approximately 6 hours. During processing, gaseous nitrogen was directed on the blades, feed drum, and stripper bars of the LA dicer from an expression device comprising one quarter inch diameter tubing, where the gaseous nitrogen was supplied at a temperature of -265 degrees F (-165 degrees C) and an approximate flow rate of 3000 SCFH (85 SCMH). The cold gaseous nitrogen was supplied using the coolant delivery system of Figure 1. After approximately 20 minutes the blades jammed in the stripper bars due to frozen product build-up. The dicer was cleaned and dried. The gaseous nitrogen was directed away from the stripper bar and the temperature set-point was increased to -200 degrees F (-129 degrees C). The LA dicer ran for approximately 6 hours processing approximately 1730 Ibs/hr of fruit product with very limited build-up on the blades. [0071] Example 5

[0072] In this example, quarter-inch (6.4 mm) thick American Cheese slices supplied to an Urschel CD-A dicer at a temperature of 59 degrees F (15 degrees C). A baseline test utilizing no gaseous nitrogen was performed, as well as a second test in which gaseous nitrogen was directed onto the blades and feed drum using an expression device comprising one quarter inch diameter tubing. The gaseous nitrogen was delivered at a temperature of -200 degrees F (-129 degrees C) and an approximate flow rate of 3000 SCFH (85 SCMH). As illustrated in Figure 9, in the baseline test, the blades of the CD-A dicer were 100% coated with cheese paste after only one minute of run time. The feed drum experienced no buildup. In the second test (with gaseous nitrogen), only a 5% buildup of cheese paste on the blades of the CD-A dicer and no buildup on the feed drum was observed over the same time interval.

[0073] As such, an invention has been disclosed in terms of preferred embodiments and alternate embodiments thereof. Of course, various changes, modifications, and alterations from the teachings of the present invention may be contemplated by those skilled in the art without departing from the intended spirit and scope thereof. It is intended that the present invention only be limited by the terms of the appended claims.

[0074] Aspect 1 A method comprising:

(a) performing a cutting process on a product using a cutting machine; and

(b) directing a coolant gas at a cryogenic temperature onto at least one cutting surface of the cutting machine while step (a) is being performed.

[0075] Aspect 2. The method of Aspect 1 , wherein step (b) comprises directing a coolant gas at a cryogenic temperature in the range of -165 to -123 degrees C onto at least one cutting surface of the cutting machine while step (a) is being performed.

[0076] Aspect 3. The method of any of Aspects 1 through 2, further comprising:

(c) maintaining the cryogenic temperature of the coolant gas within a predetermined range of a set-point temperature while step (b) is being performed.

[0077] Aspect 4. The method of any of Aspects 1 through 3, further comprising:

(d) maintaining the cryogenic temperature of the coolant gas within 6 degrees C of a set-point temperature while step (b) is being performed.

[0078] Aspect 5. The method of any of Aspects 3 through 4, further comprising: (e) measuring first and seconds temperatures, the first temperature being the temperatures of the product prior to performing step (a) and the second temperature being the temperature of the product after step (a) has been performed on the product; and

(f) determining the set-point temperature based on observed as a function of any difference between the first and second temperatures.

[0079] Aspect 6. The method of any of Aspects 3 through 5, further comprising:

(g) measuring first and seconds temperatures, the first temperature being the temperatures of the product prior to performing step (a) and the second temperature being the temperature of the product after step (a) has been performed on the product; and

(h) selecting the set-point temperature that results in the being second temperature no greater than the first temperature when step (b) is being performed.

[0080] Aspect 7. The method of any of Aspects 1 through 6, wherein step (b) comprises directing a coolant gas at a total flow rate greater than 28 SCMH onto at least one cutting surface of the cutting machine while step (a) is being performed.

[0081] Aspect 8. The method of any of Aspects 1 through 7, wherein step (a) comprises performing a cutting process on a food product.

[0082] Aspect 9. A coolant delivery system including:

a cryogen supply line that is connected to a source of a cryogen in liquid phase;

a gas supply line that is connected to a source of a supply gas;

a programmable logic controller that is in communication with at least one temperature sensor and is adapted to control the flow of the cryogen through the cryogen supply line;

a mixing zone at which the cryogen from the cryogen supply line and the supply gas from the gas supply line are combined to form a coolant gas; and

a coolant delivery device that is in flow communication with the mixing zone and downstream from the mixing zone, the coolant delivery device being capable of discharging the coolant gas at a rate of at least 28 SCMH;

wherein the programmable logic controller is programmed to adjust the proportional valve maintain to maintain an actual temperature within a predetermined temperature range of a set-point temperature, the actual temperature being a function of temperatures measured by the at least one temperature sensor. [0083] Aspect 10. The coolant delivery system of Aspect 9, further comprising a proportional valve located on the cryogen supply line, wherein the programmable logic controller is adapted to control the proportional valve.

[0084] Aspect 1 1 . The coolant delivery system of any of Aspects 9 through 10, wherein the supply gas is supplied to the mixing zone at a higher pressure than the cryogen is supplied to the mixing zone.

[0085] Aspect 12. The coolant delivery system of any of Aspects 9 through 1 1 , wherein the supply gas is supplied to the mixing zone at a pressure that is at least 138 kPa higher than a pressure at which the cryogen is supplied to the mixing zone.

[0086] Aspect 13. The coolant delivery system of any of Aspects 9 through 12, wherein the set-point temperature is between -165 degrees C and 29 degrees C.

[0087] Aspect 14. The coolant delivery system of any of Aspects 9 through 13, wherein the cryogen is liquid nitrogen and the supply gas is gaseous nitrogen.

[0088] Aspect 15. The coolant delivery system of any of Aspects 9 through 14, wherein the predetermined temperature range comprises 6 degrees C above or below the set-point temperature.

[0089] Aspect 16. The coolant delivery system of any of Aspects 9 through 15, wherein the at least one temperature sensor is located in the mixing zone.

[0090] Aspect 17. An apparatus comprising:

a cutting machine that is adapted to perform a cutting process on a product, the cutting machine having at least one cutting surface; and

a coolant delivery system that is adapted to discharge a coolant gas through at least one coolant delivery device at a total flow rate greater than 28 SCMH and to maintain a discharge temperature of the coolant gas within 6 degrees C above and below a set-point temperature and each of the at least one coolant delivery device being positioned to direct the coolant gas onto one of the at least one cutting surface.

[0091] Aspect 18. The apparatus of Aspect 17, wherein the set-point temperature is no greater than -70 degrees C.

[0092] Aspect 19. The apparatus of any of Aspects 17 through 18, wherein the coolant delivery system further comprises:

a gas supply line that is connected to a source of a supply gas; a programmable logic controller that is in communication with at least one temperature sensor and is adapted to control a proportional valve located on the cryogen supply line; and a mixing zone at which the cryogen from the cryogen supply line and the supply gas from the gas supply line are combined to form a coolant gas;

wherein each of the at least one coolant delivery device is in flow communication with the mixing zone and downstream from the mixing zone;

wherein the programmable logic controller is programmed to maintain the discharge temperature of the coolant gas within 6 degrees C above and below a set-temperature by sensing adjusting the proportional valve maintain to maintain an actual temperature within a predetermined temperature range of a set-point temperature, the actual temperature being a function of temperatures measured by the least one temperature sensor.

[0093] Aspect 20. The coolant delivery system of Aspect 19, wherein the cryogen is liquid nitrogen and the supply gas is gaseous nitrogen.

Claims

1 . A method comprising:

(a) performing a cutting process on a product using a cutting machine; and

2. The method of claim 1 , wherein step (b) comprises directing a coolant gas at a cryogenic temperature in the range of -165 to -123 degrees C onto at least one cutting surface of the cutting machine while step (a) is being performed.

3. The method of claim 1 , further comprising:

4. The method of claim 1 , further comprising:

5. The method of claim 3, further comprising:

(e) measuring first and seconds temperatures, the first temperature being the temperatures of the product prior to performing step (a) and the second temperature being the temperature of the product after step (a) has been performed on the product; and

6. The method of claim 3, further comprising:

7. The method of claim 1 , wherein step (b) comprises directing a coolant gas at a total flow rate greater than 28 SCMH onto at least one cutting surface of the cutting machine while step (a) is being performed.

8. The method of claim 1 , wherein step (a) comprises performing a cutting process on a food product.

9. A coolant delivery system including:

a gas supply line that is connected to a source of a supply gas;

wherein the programmable logic controller is programmed to adjust the proportional valve maintain to maintain an actual temperature within a predetermined temperature range of a set-point temperature, the actual temperature being a function of temperatures measured by the at least one temperature sensor.

1 0. The coolant delivery system of claim 9, further comprising a proportional valve located on the cryogen supply line, wherein the programmable logic controller is adapted to control the proportional valve.

1 1 . The coolant delivery system of claim 9, wherein the supply gas is supplied to the mixing zone at a higher pressure than the cryogen is supplied to the mixing zone.

1 2. The coolant delivery system of claim 9, wherein the supply gas is supplied to the mixing zone at a pressure that is at least 138 kPa higher than a pressure at which the cryogen is supplied to the mixing zone.

1 3. The coolant delivery system of claim 9, wherein the set-point temperature is between -165 degrees C and 29 degrees C.

1 4. The coolant delivery system of claim 9, wherein the cryogen is liquid nitrogen and the supply gas is gaseous nitrogen.

1 5. The coolant delivery system of claim 9, wherein the predetermined temperature range comprises 6 degrees C above or below the set-point temperature.

1 6. The coolant delivery system of claim 9, wherein the at least one temperature sensor is located in the mixing zone.

1 7. An apparatus comprising:

1 8. The apparatus of claim 17, wherein the set-point temperature is no greater than -70 degrees C.

1 9. The apparatus of claim 17, wherein the coolant delivery system further comprises:

a gas supply line that is connected to a source of a supply gas;

a programmable logic controller that is in communication with at least one temperature sensor and is adapted to control a proportional valve located on the cryogen supply line; and a mixing zone at which the cryogen from the cryogen supply line and the supply gas from the gas supply line are combined to form a coolant gas;

wherein each of the at least one coolant delivery device is in flow communication with the mixing zone and downstream from the mixing zone; wherein the programmable logic controller is programmed to maintain the discharge temperature of the coolant gas within 6 degrees C above and below a set-temperature by sensing adjusting the proportional valve maintain to maintain an actual temperature within a predetermined temperature range of a set-point temperature, the actual temperature being a function of temperatures measured by the least one temperature sensor.

20. The coolant delivery system of claim 19, wherein the cryogen is liquid nitrogen and the supply gas is gaseous nitrogen.