System for verifying the operation of cryogenic equipment extractions

Abstract

A method for managing the operation of a cryogenic cooling or freezing installation for products, an installation comprising cryogenic cooling equipment such as a cryogenic tunnel, a mixer, or a cutting or chopping unit known as a "cutter", equipment which is equipped with means for extracting the cold gases formed in the equipment due to the vaporization of the cryogen used for cooling, and where the extraction means include at least one discharge pipe with an end opening outside the premises housing the equipment, characterized in that a part which can be described as a "valve", which is movable, is positioned at the outside end of the one or each one of said discharge pipes.and which is capable of closing the pipeline in question when the equipment is not in production mode, and in that the flow rate of gas extracted by the pipeline in question is measured in order to be able to detect any possible obstruction of this pipeline in question, by measuring the opening angle of the valve equipping the pipeline in question. Figure from the abstract: Fig. 1,

Description

Title of the invention: "System for verifying the operation of cryogenic equipment extractions"

[0001] The present invention relates to the field of extraction hoods equipping freezing tunnels, but more generally equipping all cryogenic equipment fitted with one or more forced extractions to the outside of the building housing this equipment, such as mixers (also called "kneaders"), meat etc...., and other "cutters" (cutting and mincing equipment).

[0002] By way of illustration, blast freezers are most often equipped with two cold gas extraction hoods located at the top of the room housing the tunnels: one at the tunnel inlet and one at the tunnel outlet. These hoods manage the evacuation, from the room, of gases resulting from the vaporization of the cryogenic fluids used in the tunnel (most often nitrogen or CO2). This extraction system therefore serves to evacuate the gases formed in the equipment and thus ensure the safety of operators by protecting them from any risk of anoxia, while maintaining the productivity of the tunnels.

[0003] It is known in particular that it is commonly observed that, due to the very low temperature of the extracted gases and the presence of humidity, ice can form in the extraction pipes, leading to a reduction in extraction, even if the extraction speed itself has been kept constant.

[0004] It should be noted that although most tunnels are equipped with two extraction hoods, sometimes tunnels are equipped with only one hood, or tunnels operate with only one of their two hoods in operation, most often the one located at the entrance, or with two hoods connected to each other.

[0005] The extraction flow rate of each of these hoods must be correctly adjusted in order to aspirate the right amount of gas, i.e. enough to avoid the spreading of gases outside the tunnel and endangering the operators, but without excessive suction so as not to draw cold gases out of the tunnel and thus cause overconsumption of cryogenic fluid.

[0006] Generally, we start by trying to confine the fluids in the middle of the tunnel by means of curtains or deflectors, then we balance the cold gases in the tunnel by means of deflectors or so-called "push" fans, and then we adjust the extraction flow rate.

[0007] Currently, if it is noted that there is gas spreading outwards at the open parts of the tunnel, at the entrance and / or at the exit, the suction flow rate is increased.

[0008] It is therefore understood that there is a crucial issue in the ability to control the extraction performance on such cryogenic equipment, not only for safety reasons (risk of anoxia of personnel), but more broadly to avoid back-pollution from the outside which could occur during shutdowns, or to maintain overpressure in the workshop for hygiene reasons, and to avoid heat entering the equipment, which would lead to overconsumption of cryogen.

[0009] Of course, this technical field already has certain solutions, among which we can mention: • The presence of a vacuum sensor fixed in the extraction duct, a sensor which allows the correct suction of the extractor to be validated.

[0010] The reliability of this type of sensor for this type of application depends on the environment inside the extraction duct: a humid, cold environment, potentially with flying fragments of frozen products. Over time, these sensors become blocked by frost or product deposits, rendering them unusable. • Hot wire (a measurement of heating resistance that maintains a temperature, based on the power supplied to the hot wire to maintain the temperature, from which an airflow rate is deduced). The same disadvantages as before can be mentioned here.

[0011] As will be seen in more detail below, in order to address these concerns, the present invention focuses on knowing in real time the information indicating whether the extraction(s) are working correctly or not, in order to be able to take appropriate emergency measures or not.

[0012] The technical solution proposed within the framework of the present invention is simple, reliable, and low cost.

[0013] It can be summarized as follows: - At the (outer) end of the extraction port(s) of the equipment, a part which can be described as a "valve", which is movable, is positioned to close the extraction pipe (when the equipment is not in production, this is understood); - The objective of the present invention is to measure the flow rate of gas extracted by the pipe in question, in order to be able to detect any possible obstruction which would lead in particular to risks of gas leakage into the room surrounding the equipment; - For this, by measuring the opening angle of the valve and depending on the diameter of the extraction pipe, we deduce a flow rate of the evacuated gases and we can therefore be able to detect a drop in flow rate; - We have previously established, through experience, a table (or curve) of flow rates measured for different opening rates of the valve, taking into account the diameter of the pipe, for example via velocity measurements carried out using an anemometer.

[0014] The measurements of opening angles can be carried out by any type of sensor known to a person skilled in the art.

[0015] It can be noted that during periods of production shutdown it is very advantageous to close the valve, which is beneficial for reducing air intake into the room containing the equipment and for limiting the phenomena of "back-pollution".

[0016] The attached [Fig.1] illustrates by means of two partial schematic views an example of an installation according to the invention, positioned on the roof of the premises housing a freezing tunnel, roof through which the extraction of the tunnel opens, views a) and b) which allow visualization of the valve, respectively in closed and open position.

[0017] The attached [Fig.2] illustrates an example of experimental determination of a table (and curve) of flow rates measured for different valve opening rates, taking into account the diameter of the pipe considered.

[0018] The present invention relates to a method for managing the operation of a cryogenic cooling or freezing installation for products, an installation comprising cryogenic cooling equipment such as a cryogenic tunnel, a mixer, or a cutting or chopping device known as a "cutter", equipment which is equipped with means for extracting the cold gases formed in the equipment due to the vaporization of the cryogen used for cooling, and where the extraction means include at least one exhaust pipe having an end opening outside the premises housing the equipment, characterized by the implementation of the following measures: - A part which can be described as a "valve", which is movable, is positioned at the outer end of the or each or at least one of the said drainage pipes, and which is capable of closing the pipe in question when the equipment is not in production phase; - We measure the flow rate of gas extracted by the pipe in question, in order to be able to detect any possible obstruction of this pipe in question, by measuring the opening angle of the valve equipping the pipe in question; - We have previously, through experimentation, established a table of measured flow rates for different valve opening rates, taking into account the diameter of the pipe in question; - The said extracted gas flow rate is determined from the said opening angle measurement using the said table; Where appropriate, an alert is triggered based on the value of said gas flow rate and its position relative to a setpoint value, to signal any anomaly and, for example, to request equipment maintenance.

Claims

[Claim 1] Demands Method for managing the operation of a cryogenic cooling or freezing installation for products, an installation comprising cryogenic cooling equipment such as a cryogenic tunnel, a mixer, or a cutting or chopping unit known as a "cutter", equipment which is equipped with means for extracting the cold gases formed in the equipment due to the vaporization of the cryogen used for cooling, and where the extraction means include at least one exhaust pipe with an end opening outside the premises housing the equipment, characterized by the implementation of the following measures: - A part which can be described as a "valve", which is movable, is positioned at the outer end of the or each or at least one of the said drainage pipes, and which is capable of closing the pipe in question when the equipment is not in production phase; - We measure the flow rate of gas extracted by the pipe in question, in order to be able to detect any possible obstruction of this pipe in question, by measuring the opening angle of the valve equipping the pipe in question; - We have previously, through experimentation, established a table of measured flow rates for different valve opening rates, taking into account the diameter of the pipe in question; - The said extracted gas flow rate is determined from the said opening angle measurement using the said table; - Where appropriate, an alert is triggered based on the value of said gas flow and its position relative to a setpoint value, to signal any anomaly and, for example, to request equipment maintenance.

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