Patent Application
20230341177
This application claims the benefit of priority under 35 U.S.C. § 119 (a) and (b) to FR patent application No. FR 2203801, filed Apr. 25, 2022, the entire contents of which are incorporated herein by reference.
The present invention relates to a method and a device for operating a cryogenic tunnel, the tunnel being of the type in which products to be cooled or deep-frozen circulate, which is equipped with means for injecting a cryogenic fluid and with means for extracting cold gases resulting from the vaporization of the fluid in the tunnel.
The document US 5 606 861 illustrates the state of this technical field in the case of so-called “IQF” products (individual deep-freezing of products such as fruits, vegetables, patties, etc.).
In this industry, users adjust the key operating parameters of the tunnel in order to maintain optimized production.
Among these parameters there are the temperature setpoint prevailing inside the tunnel, the speed of the conveyor and the speed of the blowers.
As is known, these parameters greatly influence the quality of the products obtained and the cost of the method through the consumption of cryogen, hence the importance of it being possible to optimize these parameters.
However, it is well known that the operating conditions of such tunnels are not stable, they vary depending on the batches of products treated: in certain cases the temperature of the entering products varies, in other cases the thickness of the products varies from one batch to another, while in other cases the flow rate of products to be treated or the composition of the products changes in the course of the day.
In this context, the optimization of the production parameters is a very complex objective, and in practice, the users of such tunnels do not adjust the parameters of the tunnel continuously during production processes, in fact they choose to adopt a “mean” setting which is intended to cover most of their production processes as correctly as possible.
Thus, for example, it has been observed that during a given production process the cooling power is too high, and so the temperature of the products exiting the tunnel is too low, this not necessarily causing a drop in quality depending on the products in question.
In other cases, the cooling power is too low, and so the temperature of the products exiting the tunnel is too high; this time, this causes a serious problem of quality and acceptability of the products obtained, and may result in the rejection of the products in question and the need to restart a production process.
This is one of the reasons for which producers prefer, for safety reasons, to adjust their setpoint temperature slightly too low, although this does of course represent a significant cost.
One solution to this problem would be to continuously adjust the operating conditions of the tunnel so that the product is cooled or deep-frozen just to the desired level, for example on the basis of a temperature measurement carried out on the products exiting the tunnel and a retroactive action on the cryogen supply conditions: if the temperature of the products at the outlet is lower than the target, the temperature of the tunnel will be increased, whereas if the temperature of the products at the outlet is too high, the temperature of the tunnel will be rapidly lowered.
Another solution could be based on the temperature of the products entering the tunnel: when the products arrive at a temperature higher than intended, the tunnel passes into a mode adopting a lower setpoint, whereas when the products arrive at a temperature lower than intended, the tunnel passes into a mode adopting a higher temperature setpoint, promoting reduced consumption of cryogen.
The literature in this field mentions in particular the following technical solutions:
A controller manages all of these sensors and is able to automatically adjust the thermal transfer to the products by acting on the cryogen feed.
While the solutions listed above undoubtedly provide an improvement to the method and in particular to the quality of the products obtained, the Applicant for its part considers further improvements to be necessary and that these may be obtained according to the invention using the following approach:
As will be shown in more detail below, the present invention makes it possible to make the equipment easier to use: the user sets their temperature of frozen products, -20° C. for example, and the method according to the present invention manages all the rest, everything that needs to be managed.
The user no longer has to wonder: if I have a fairly hot product entering the tunnel, the flow rate is fairly high so do I need to put the tunnel at -110° C. rather than -100° C.?, the blowers at 90% rather than 50%?, the extraction at X or Y%?
And when the production conditions change, the user does not need to deal with the tunnel, it will adapt by itself to maintain a temperature of deep-frozen products at -20° C.
A cryogenic tunnel is known to generally have the following elements:
It is furthermore possible for there to be one or more of the following devices and the following data:
With these two groups of clearly different parameters, a matrix is constructed for each group, such as those that will exemplified below in order to make the invention easier to understand:
As is described in detail below, the measurements obtained for one or more parameters of these two groups of parameters make it possible to calculate the adjustments to be made to a group of (anticipation and/or retroactive) action parameters, this group of actions being made up of:
It should also then be noted that the second input of the two matrices is made up of the same group of parameters as the group of action parameters set out above.
As will be demonstrated below, the invention, in contrast to the prior art, does not act on just one parameter (for example only on the speed of the blowers or only on the thermal transfer) but on several parameters governing the operation of the tunnel.
To make the invention easier to understand, an example of a first matrix made up of the 1st group of parameters and the anticipation actions carried out will be found below, each cell of this matrix being made up of a factor that establishes a link between a given parameter and a given anticipation action (anticipation action situated in said group of actions that are listed above).
In addition, an example of a second matrix made up of the 2nd group of parameters and the “retroactive” actions carried out will also be found below, each cell of this matrix being made up of a factor that establishes a link between a given parameter and a given retroactive action (retroactive action situated in said group of actions that are listed above).
It should also be noted that if the content in certain cells is set to zero, it should be understood in their case that there is no action or retroactive action to be undertaken.
The actions that can be undertaken are exemplified in the following text:
The same type of action will also be defined in the matrix for each pair of parameters. In addition, if, in a given pair of parameters (a given cell), it is decided that no action is desired, the linking parameter will be set to zero (for example, the decision is made to set x12 to zero and thus the variations in flow rate of products will not bring about any action on the speed of the conveyor). This may for example be the case when it is desired for the conveyor to operate at constant speed. In this case, all the parameters of the matrix that have an impact on the speed of the conveyor will be set to zero. In the above example, x11 will be adjusted to zero.
For the second group of parameters (second matrix), the operation will be exemplified below.
Thus for example, if y51 = -0.5, the system will then carry out the following action: if a product exiting the tunnel has a temperature of 6° C., higher than the fixed setpoint, the tunnel will then automatically adjust the temperature inside the tunnel by 6 × (-0.5) = 3° C. i.e. by decreasing the setpoint by 3° C. per minute, step by step.
The temperature of the exiting products will thus decrease step by step, until the setpoint required at the outlet is reached. When the required set point has been obtained, the system stabilizes and the temperature setpoint in the tunnel will also be stabilized at the value that makes it possible to achieve optimal cooling of the product.
Again, if it is not desired to undertake any action on a given pair of parameters, the corresponding cell of the matrix is set to zero, for example if the cell y22 is set to zero, a variation in the flow rate of cryogen injected will not bring about any action on the speed of the blowers.
It is thus apparent, from the examples given here, that the actions are calculated differently but they act on the same group of action parameters, be this for the anticipation actions or the retroactive actions.
Whether it is detected that the products are arriving in too hot a state (it is then possible to envisage reducing the temperature of the tunnel by anticipation) or that the products are exiting in too cold a state (it is then possible to envisage reducing the temperature of the tunnel by retroactive action so that the following products are at the correct temperature), the action is the same.
In other words, there may be two different causes/origins for modifying a single tunnel parameter.
By contrast, a single parameter that brings about the modification of several parameters of the tunnel may also be observed.
As will be clearly apparent to a person skilled in the art, the matrices presented here can be established for a smaller number of parameters, or for a larger number of parameters, by adding parameters that are not listed here, for example for treating the tunnels provided with more than one conveyor, or with several temperature regions and therefore several temperature setpoints.
An example of the experimental determination of the values constituting the cells of the two matrices described above will be described in the following text.
To this end, to fill a cell, that is to say to determine the factor occupying the cell in question, a step-by-step procedure is carried out.
Consider the example of the factor y51 which establishes a relationship between the setpoint temperature of the deep freezer and the temperature of the products at the outlet of the deep freezer.
Step 1: the user puts the apparatus into operation with products. In order for this setting procedure to be successful, it is preferable, if not indispensable, for the method to be as stable as possible, for the flow rate and the temperature of the products to be frozen to be stable, and for the parameters of the deep freezer (speed of the blowers, speed of the belt, extraction speed) to likewise be stable.
Step 2: When the deep-freezing method is taking place stably, the regulating system that is the subject of the present invention is put into operation and a target temperature for the deep-frozen products at the outlet of the deep freezer is defined in accordance with the client’s needs. For the deep-frozen products, a target temperature of -20° C. will often be chosen.
The temperature of the deep-frozen product is then monitored by the user. Preferably, this temperature is recorded and the curve is constructed live.
Step 3: the parameter y51 is adjusted to a randomly chosen value, 1 for example. All the other parameter are adjusted to zero so as not to create interference between the control loops.
Step 4: the user then watches the behaviour of the temperature curve of the deep-frozen product for at least a time equivalent to 4 times the passage time of the product in the deep freezer:
Step 5: the user changes the setpoint temperature of the deep-frozen products and then watches the behaviour of the temperature curve of the deep-frozen product for at least a time equivalent to 4 times the passage time of the product in the deep freezer:
The same procedure could be applied to all the control parameters X or Y of the matrices of the present invention, that is to say to all the pairs of parameters of the method. The user will carry out the same procedure by adjusting each parameter X or Y one by one, taking care to adjust all the other parameters to 0 at the start of the procedure.
When this entire procedure has been completed, all the control parameters X of the method will have been determined.
Optimal control of the operation of the deep freezer will then be obtained.
The invention will be illustrated in the following text by a specific example: as mentioned above, when a cryogenic tunnel operates at a production site, numerous parameters may change at the same time, and all of these parameters have an impact on the deep freezing carried out.
If for example the flow rate of entering products increases by 20% and changes, by way of illustration, from 1000 to 1200 kg/h. If, at the same time, the temperature of the product decreases such that product requires 5% less cold (for example 95 calories/kg rather than 100).
The tunnel may then be considered, overall, to need to supply 1200 × 95 = 114 000 equivalent power as opposed to 100 000 previously. It therefore needs to supply 14% more energy.
The following text contains a summary of what will take place depending on the solution chosen by the user of the tunnel.
The invention could furthermore adopt one or more of the following embodiments:
The present invention thus relates to a method for operating a cryogenic tunnel in which products to be cooled or deep-frozen circulate, the tunnel being equipped with means for injecting a cryogenic fluid and with means for extracting, at a variable flow rate, all or part of the cold gases resulting from the vaporization of said fluid in the tunnel, characterized in that:
The anticipation or retroactive actions being determined by the outputs of the two following matrices governing said actions:
The measurements obtained for one or more parameters of these two groups of parameters making it possible to calculate the adjustments to be made to the group of (anticipation and/or retroactive) action parameters made up of:
The second input of the two matrices being made up of said group of action parameters, and in that values making up the cells of the two matrices have been determined experimentally, each cell of these matrices being made up of a factor establishing a link respectively between a given parameter of the first group and a given anticipation action, and a given parameter of the second group and a given retroactive action.
While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.
The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.
“Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing i.e. anything else may be additionally included and remain within the scope of “comprising.” “Comprising” is defined herein as necessarily encompassing the more limited transitional terms “consisting essentially of” and “consisting of”; “comprising” may therefore be replaced by “consisting essentially of” or “consisting of” and remain within the expressly defined scope of “comprising”.
“Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.
Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.
Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.
All references identified herein are each hereby incorporated by reference into this application in their entireties, as well as for the specific information for which each is cited.
Although the subject matter described herein may be described in the context of illustrative implementations to process one or more computing application features/operations for a computing application having user-interactive components the subject matter is not limited to these particular embodiments. Rather, the techniques described herein can be applied to any suitable type of user-interactive component execution management methods, systems, platforms, and/or apparatus.
It will be understood that many additional changes in the details, materials, steps, and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above and/or the attached drawings.
While embodiments of this invention have been shown and described, modifications thereof may be made by one skilled in the art without departing from the spirit or teaching of this invention. The embodiments described herein are exemplary only and not limiting. Many variations and modifications of the composition and method are possible and within the scope of the invention. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims which follow, the scope of which shall include all equivalents of the subject matter of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR 2203801 | Apr 2022 | FR | national |
