Patent Application
20120011862
The present embodiments relate to control of recipes for processing products, such as for cryogenic freezing and chilling of food and pharmaceutical products.
The ability to select a recipe for a freezing or chilling process is becoming common in new freezing and chilling systems. A recipe is a series of predetermined parameters, which establishes the adjustment of process equipment system variables to a particular product being processed to achieve the desired output quality for the product.
Use of a recipe may be applied to any process, such as for example food freezing. To achieve a production rate of 6000 pounds per hour (lb/hr) of hamburger patties for example, with a fixed product inlet temperature and a desired outlet temperature, a recipe can be created so that a freezer will operate at a fixed freezing temperature, conveyor belt speed (residence time) for the product, and fan speed to match the requirements. The operator simply selects a recipe from a menu and the freezer adjusts to the above pre-defined parameters of the recipe.
The problem with known systems is that they do not account for day-to-day or even hour-to-hour deviations in product parameters being provided to the process, such as for example variability in production rates and product inlet temperatures. In addition, freezer performance can deteriorate over time, thereby adversely impacting a temperature of the product from the instance it enters the freezer. To compensate for these conditions, an existing recipe must be manually superceded to change process equipment parameters to accommodate the changed qualities of the product being processed. This defeats the intended purpose of the recipe, since the operator must then guess or estimate as to which parameter(s) to change and to what degree in order to accommodate the changing variables of the product to be processed. For example, does the operator increase or decrease the amount of freezing medium, the residence time of the product in the freezer, the heat transfer coefficient (fan speed), and if so, in which combination? A human operator would not be able to make this determination accurately in order to provide the most cost-effective way to proceed to bring the product “on-spec” at discharge.
The enhancement embodiments to a recipe driven control system are to have the ability for the process equipment controls to “alter” a recipe through operator input of the changed product parameter and by means of internal process calculation, optimise the process either by the operator's desired affect or by optimising process efficiency. For example, if a plant operator were to input new product infeed temperature, then the freezer controls will determine how to best compensate process parameters and make the necessary change in either process temperature, fan speed, product residence time, or possibly a combination of these elements.
The inventive embodiment compensates for “off-spec” product, i.e. the processing system will change or alter machine control parameters to bring subsequent product back into “spec”. Machine recipe settings can include multiple parameters, and changing any one of said parameters will affect to some degree the result of the process. The present embodiments eliminate operator guesswork when changing machinery parameters, such as freezer or oven parameters, through programming not presently available. This is accomplished by establishing a hierarchy of parameters so that a proper parameter is changed along with an internal calculation to establish the degree to which the parameter will be changed. The input to this control of the parameter will be through operator input (most likely but not necessarily temperature input) or through direct feedback from a sensor (such as for example a temperature sensing device) generating a signal responsive to a processed product's temperature.
There is provided a method of adjusting a base recipe for a product introduced into a processor, which includes providing a base recipe used by the processor on the product, identifying at least one parameter of the base recipe to be altered to compensate for at least one corresponding physical parameter of the product discharged from the processor, automatically changing the base recipe in response to the at least one altered parameter to compensate for the at least one physical parameter of the product discharged, and processing new product introduced into the processor with the changed base recipe.
The operator of the present embodiment selects a recipe, starts production with the recipe selected and monitors the product during and after production to determine if the desired result is achieved. If the product result is not achieved, the product attribute which is “off-spec”, typically the product temperature, is input into the processor to adjust the recipe parameters to provide the desired product to be produced during the processing. Since the recipe parameters are changed and displayed during processing, if the operator finds a variable or parameter which is undesirable, and the condition repeats itself, the operator may chose to edit and restore a revised recipe. This will eliminate operator guesswork going forward due to storage of the new recipe for a particular product to be processed.
In general, the plant operator will measure and input the deviation necessary to the known base recipes programmed into the freezer's control system. The operator may adjust any or all of the variables known, such as for example inlet temperature of the product, residence time of the product within the freezer, outlet temperature of the product, product surface area, product weight, product heat load, overall heat transfer co-efficient (fan speed) and moisture content, such that a required operating temperature of the freezer can be calculated and adjusted by the processor. Alternatively, through a hierarchy of parameters, if the product is being discharged or exhausted at an undesirable temperature, the “out-feed” product temperature is input into the processor for adjusting the freezer to a proper freezing parameter. That is, the operator would randomly sample product at the outlet of the processor, such as a freezer or oven, to determine if the temperature at the outlet is “on-spec” for subsequent use or further processing. For example, the out-feed product temperature may be desired to be −20° C., when in fact the random sampling shows that the product temperature is actually −5° C. Therefore, the operator would input into the processor the product temperature at the outlet of −5° C. and the processor would scroll through the hierarchy of parameters to determine which parameter or parameters of the recipe should be altered for the most efficient and cost effective way to provide the product with a temperature of −20° C. at the outlet or discharge end of the processor. The processor will determine which of the parameters of cooling, heat transfer coefficient (fan speed) or residence time (conveyor speed) must be adjusted in order to provide the desired product temperature at the outlet, while maintaining a high operating efficiency of the freezing process. The processor may determine to adjust one or more of these parameters in the recipe so that the product being discharged is at the desired temperature.
The embodiments of the present invention enable an operator of a food processing plant, for example for freezing or chilling of food products, to select from among a plurality of known base recipes to be used with the food product. For example, the plant operator will select the type of product to be frozen, such as for example meat, poultry, fish, vegetables, fruit, bakery products, dairy products, processed foods, pharmaceutical products; and the freezer will prescribe the recipe to be used for such product. However, since the recipe as loaded into the freezer is already pre-set, such a setting may only cause the freezer to function for the product selected at a specific input temperature, throughput volume (e.g. 300 units per hour), output temperature, moisture content, etc. That is, the operator is limited initially to selecting a recipe which, although such can be used for any type of food product, such as chicken for example, such recipe may not be specific enough for the particular type of chicken product (or meat or fish product, etc.) that is actually to be chilled or frozen by the freezer.
In addition, product being introduced into the freezer may arrive from an environment that has drastically altered the product's temperature and consistency from a recipe which is already stored in the processor for the particular product. It would be extremely difficult if not impossible for the operator to determine which parameters of the recipe must be altered, and by how much, in order to have the product introduced at the inlet processed to a desired outlet temperature. Hence, a random sampling of the product at the outlet and input of such data into the processor insures that product being introduced into the inlet will be exposed to the necessary recipe to provide the product with the desired outlet temperature.
Therefore, after the operator selects the base recipe, the operator then may adjust the recipe depending upon the particulars of the product at the inlet, for example, to be frozen or chilled. So, for example, the operator will know that the base recipe for chicken cutlets may be for a certain number of cutlets at a certain inlet temperature to be frozen such that a certain output temperature is provided to the frozen or chilled cutlets. After the operator selects the initial base recipe, the operator then adjusts the freezer control to the required inlet temperature setting by a switch on the control panel to be the known temperature of the food product being introduced into the freezer. Chicken products, for example, may be introduced to the freezer at different temperatures and therefore, such temperatures may not be the same as used in the base recipe. The necessity to change freezer control parameters may also result from deviations in freezer performance, such as for example ice build-up affecting convection circulation in the freezer or environmental conditions, such as for example an unusually hot environmental at an exterior of the freezer (or an unusually cold environment at an exterior of an oven).
Similarly, the plant operator may elect to move 6,000 units per hour through the freezer, as opposed to the base recipe which takes into account only 4,000 units per hour. Further, the operator may need the output temperature at 40° F., as opposed to say 50° F. which may be pre-set into the existing base recipe. Therefore, the operator will further select an adjustment to the freezer control for the throughput volume of product and the desired output temperature of same. When all these adjustments to input/output temperature, and throughput amount or quantity have been made, the freezer recomputes the amount of cryogen, mechanical refrigerant, speed of conveyance, etc., necessary for this particular product, including the residence time (or throughput time) of the food product to transit the freezer, such that the food product is chilled or frozen in the most efficient amount of time using only the necessary amount of cryogen in order to effect the chilling necessary for the product to be on-spec at the outlet of the freezer.
Food products may have different moisture content. That is, certain manufacturers of chicken for example inject marinate or other preservatives into the chicken product and this impacts temperature of the product to be introduced into the freezer, as well as product dwell time in the freezer. The marinate may consist of a brine solution which could affect the temperature of the food product such that adjustment has to be made to the freezer control to accommodate an amount of cryogen necessary to overcome the warming effect of the marinate or other brine product injected into the chicken patty. This condition may not be immediately apparent until the product is inspected upon discharge from the freezer (or oven if used instead), in which case the measured out-feed temperature of the product can be input into the control system for same to adjust the cooling parameters to offset the unacceptable warming of the product.
Sensors may also be used to interface directly with the freezer control, or oven control, which sensors transmit a signal to the control of the particulars of the food product to be frozen (or heated) such that the necessary calculation can be made by the freezer control to the base recipe, depending upon the particulars of the product to be frozen (or heated). That is, sensors may be disposed at an inlet and an outlet of the freezer (or heater) to sense the temperature of the product introduced into and exhausted from the processor, instead of manually sensing the temperature of the product at the inlet and outlet. The actual temperature sensed of the product at the outlet is conveyed as a signal (wirelessly or otherwise) back to the processor control which in turn scrolls through the hierarchy of parameters to adjust the parameters of the receipt as necessary so that the product has the desired temperature when it is removed from the outlet.
The embodiments discussed above are also applicable where the processor is an oven. In that regard, instead of a cooling substance, heat for the recipe can be provided to the processor by at least one of convection currents, conduction and radiation.
It will be understood that the embodiments described herein are merely exemplary, and that one skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as described and claimed herein. Further, all embodiments disclosed are not necessarily in the alternative, as various embodiments of the invention may be combined to provide the desired result.
