Method for monitoring the inertization of a treatment tank and monitoring system

Abstract

The invention relates to a method for monitoring the inerting of a treatment vessel (10) with an inert gas (G), comprising the following steps: - Introducing the inert gas (G) into the treatment vessel (10), - Determining an oxygen partial pressure (Pox) by the oxygen sensor (20), - Determining a total pressure (Ptot) by the pressure sensor (30), - Determining an oxygen indicator based on the oxygen partial pressure (Pox) and the total pressure (Ptot), wherein the oxygen indicator comprises the quotient of the oxygen partial pressure (Pox) and the total pressure (Ptot), - Outputting an inerting condition based on the oxygen indicator from the output unit (50). (Fig. 1)

Description

Title of the invention: Method for monitoring the inertization of a treatment tank and monitoring system

[0001] The invention relates to a method for monitoring the inerting of a treatment tank and a monitoring system.

[0002] In analytical measuring technology, in particular in the field of water management, environmental analysis, in the industrial field, for example in food technology, biotechnology and pharmacy, as well as for the most diverse laboratory applications, measured variables such as the pH value, the conductivity or the concentration of analytes, such as ions or gases dissolved in a gaseous or liquid measuring medium, are of great importance. These measured variables can, for example, be detected and / or monitored by means of electrochemical sensors, such as optical, potentiometric, amperometric, voltametric or colorimetric sensors, or conductivity sensors.

[0003] In the field of inerting process vessels with an inert gas, for example, optical oxygen sensors are used to monitor the oxygen content in the process vessel during inerting. In this case, it is particularly important to immediately detect and identify problems due to a leaking process tank, due to a lack of purity of the inert gas.

[0004] It is therefore an objective of the invention to provide a method which safely, quickly and reliably determines the oxygen content in a process.

[0005] This problem is solved by the invention of the method for monitoring the inerting of a treatment tank with an inert gas comprising the following steps:

[0006] - Providing a monitoring system with the process container, a oxygen sensor, a pressure sensor and an evaluation unit,

[0007] wherein the oxygen sensor and the pressure sensor are communicatively connected to the evaluation unit and are arranged in measurement terms so as to be adapted to be exposed to the inert gas, the evaluation unit comprising an output unit,

[0008] - Introduce the inert gas into the treatment container,

[0009] - Determine a partial pressure of oxygen by the oxygen sensor,

[0010] - Determine a total pressure by the pressure sensor,

[0011] - Determine an oxygen indicator based on the partial pressure of oxygen and total pressure, wherein the oxygen indicator comprises the quotient of the partial pressure of oxygen and the total pressure,

[0012] - Output an inerting condition based on the oxygen indicator of the output unit.

[0013] The method according to the invention makes it possible, using the oxygen indicator, to precisely measure the volumetric percentage of oxygen contained in the pipeline, furnace, tank or any other equipment requiring gaseous inerting. This is in order to guarantee, and in a non-limiting manner, - The absence of oxygen in an environment to guarantee the absence of the oxygen oxidant in an explosive zone (Lower Explosive Limit), - The absence of oxygen which could alter by oxidation the quality of the product stored or treated in the tank, oven etc. - Accurately measure and regulate the gaseous oxygen level in a process requiring exact control of this oxygen value (% Vol O2) for the quality of the product or treatment, - Guarantee the absence of oxygen in controlled atmospheres.

[0014] According to one embodiment of the invention, a first alert message is emitted as an inerting state when the oxygen indicator is greater than a first threshold value and a first period of time has been exceeded since the introduction of the inert gas, the first alert message signaling in particular a possible problem with the purity of the inert gas and / or a possible problem with the sealing of the treatment tank.

[0015] According to one embodiment of the invention, a first alert message is emitted when the oxygen indicator has fallen below a first threshold since the introduction of the inert gas and has then exceeded, after a second period of time, the first threshold as well as a second threshold, the first alert message signaling in particular a possible problem with the purity of the inert gas and / or a possible problem with the sealing of the treatment tank.

[0016] According to one embodiment of the invention the monitoring system comprises a sample chamber having an inlet and an outlet, the inlet and outlet being fluidically connected to the treatment tank, and the oxygen sensor and the pressure sensor being disposed in the sample chamber,

[0017] the inerting state being further based on the total pressure and a third warning message being issued when the oxygen indicator has fallen below a first threshold value and the total pressure has fallen below a third threshold value, the third warning message signaling in particular an obstruction of the inlet.

[0018] According to one embodiment of the invention, the output unit comprises at least one display and / or at least one control output and the inerting state is displayed on the display and / or is delivered on the control output.

[0019] The above-mentioned problem is also solved by a monitoring system for monitoring inerting with an inert gas comprising:

[0020] - A treatment tank,

[0021] - An oxygen sensor,

[0022] - A pressure sensor,

[0023] - An evaluation unit with an output unit,

[0024] in that the oxygen sensor and the pressure sensor are communicatively connected to the evaluation unit and are exposed by measurement to the inert gas, in that the monitoring system is capable of implementing the method as described above.

[0025] According to one embodiment of the invention the monitoring system comprises a sample chamber with an inlet and an outlet, wherein the inlet and the outlet are fluidically connected to the treatment tank and the oxygen sensor and the pressure sensor are arranged in the sample chamber.

[0026] According to one embodiment, a vacuum pump is connected to the outlet.

[0027] Other advantages and characteristics will emerge more clearly from the following description, given by way of non-limiting example, of the monitoring method according to the invention, from the appended drawings in which: - [Fig.l] shows a schematic representation of a monitoring system according to the invention; - [Fig.2] shows an example of the evolution of the oxygen indicator I and the total pressure.

[0028] [Fig.l] shows a monitoring system 100 according to the invention, comprising a treatment tank 10, an oxygen sensor 20, a pressure sensor 30 and a treatment unit 40. The monitoring system 100 is adapted to monitor the inerting of the treatment tank 10 by an inert gas G.

[0029] The treatment tank 10 is, for example, a pipeline, a furnace, a reactor or any other system to be inerted by an inert gas G. The treatment tank 10 is a tank of inert gas G.

[0030] The inert gas G is for example nitrogen, a rare gas such as helium, neon, argon, krypton, xenon, radon, or a gaseous molecular compound such as sulfur hexafluoride.

[0031] The term inerting here designates the addition of inert substances in the form of gas with the aim of modifying the safety characteristics of a gas mixture in order to prevent the formation of an explosive atmosphere, as well as the presence of oxygen which could alter (by oxidation) the characteristics of the product stored in the tank.

[0032] The oxygen sensor 20 is preferably an optical or amperometric oxygen sensor. The oxygen sensor 20 is adapted to measure a partial pressure of oxygen Pox and the temperature. The pressure sensor 30 is adapted to measure a total pressure Ptot. The pressure sensor 30 and the oxygen sensor 20 are communicatively connected to the evaluation unit 40 and are exposed to the inert gas G so that the sensors are capable of measuring the inert gas G. For example, according to a configuration not shown, the oxygen sensor 20 and the pressure sensor 30 are directly installed on the treatment tank 10.

[0033] The evaluation unit 40 is adapted to evaluate and process the measured values ​​determined by the oxygen sensor 20 and the pressure sensor 30. The evaluation unit 40 has an output unit 50. The output unit 50 is adapted to determine an oxygen indicator Ind based on the oxygen partial pressure Pox, the total pressure Ptot and the temperature. Likewise, the evaluation unit 40 is adapted to determine an inertization state of the treatment tank 10 on the basis of the oxygen indicator Ind. Preferably, the evaluation unit 40 is adapted to operate in an explosion hazard zone.

[0034] The output unit 50 comprises, for example, a transmitter 41 and a computer 42. The transmitter 41 is, for example, adapted to convert the raw signals from the oxygen sensor 20 into measurement signals. The computer 42 is, for example, adapted to read the oxygen partial pressure Pox and the total pressure Ptot and to generate warning messages. The output unit 50 preferably comprises a display 51, a control output 52, a data output 53, a screen 54. The display 51 displays, for example, the oxygen partial pressure Pox, the total pressure Ptot, the oxygen indicator Ind and / or the inerting state. Binary signals are preferably output at the control output 52. For example, an alarm indicator is output at the control output 52. The data output 53 preferably outputs measurement data or messages via a HART protocol or another protocol. Screen 54 preferably displays the same data as display 51.The screen 54 is preferably placed in an area not subject to a risk of explosion.

[0035] According to the exemplary embodiment illustrated in [Fig.l], the monitoring system 100 has a test chamber 11 with an inlet 12 and an outlet 13. The inlet 12 and the outlet 13 are fluidically connected to the treatment tank 10. In this embodiment, the oxygen sensor 20 as well as the pressure sensor 30 are arranged in the sample chamber 11. Preferably, a vacuum pump is connected to the outlet 13 (not shown). The vacuum pump allows the inert gas G to be safely introduced from the treatment tank 10 into the sample chamber 11.

[0036] The method for monitoring the inerting of a treatment tank 10 by an inert gas G according to the invention is described below.

[0037] First, the monitoring system 100 described above is made available. This means that the monitoring system 100 is ready for use. The oxygen sensor 20 as well as the pressure sensor 30 are connected to the evaluation unit 40 by communication means and are arranged so that they can be exposed to the inert gas G. As described above, the oxygen sensor 20 and the pressure sensor 30 are for example placed in the treatment tank 10 or in the sampling chamber 11 (see [Fig.l]).

[0038] The next step is to introduce the inert gas G into the treatment tank 10, as shown by the arrow in the treatment tank 10 in [Fig.l]. If a test chamber 11 is used, the inert gas G also flows into the test chamber 11 when it is introduced through the inlet 12. If the outlet 13 has a vacuum pump, the entry of the inert gas G into the sampling chamber 11 is ensured by means of the vacuum pump.

[0039] Then, the oxygen sensor 20 determines the oxygen partial pressure Pox. The oxygen partial pressure Pox is preferably stored by the evaluation unit 40.

[0040] The pressure sensor 30 then determines a total pressure Ptot. The total pressure Ptot is preferably recorded by the evaluation unit 40.

[0041] Furthermore, the oxygen indicator Ind is determined on the basis of the oxygen partial pressure Pox, the total pressure Ptot. Preferably, the oxygen indicator Ind also takes into account the temperature to perform a compensation. The oxygen indicator Ind comprises the quotient of the oxygen partial pressure Pox and the total pressure Ptot. The oxygen partial pressure Pox is in some way normalized by the total pressure Ptot.

[0042] The next step is to emit an inerting state based on the oxygen indicator Ind.

[0043] When exiting the inerting state, a first alert message is issued when the oxygen indicator Ind is greater than a first threshold S1 and a first time period ta has been exceeded since the introduction of the inert gas G. In [Fig.2], this situation is reached at the first moment T1 and the evolution of the oxygen indicator Ind is represented by the curve C2.

[0044] The first threshold value S1 is a user-defined target value that the gas mixture in the treatment tank 10 normally reaches during normal inerting after the first period ta, which is also user-defined. The first threshold value SI is, for example, 0.05 (without unit of measurement). If the first threshold value SI is not reached after the first time period ta, the treatment tank 10 is probably not leak-tight, or the supposedly inert gas G actually contains oxygen. The first warning message indicates in particular a possible problem with the purity of the inert gas G and / or a possible problem with the leak-tightness of the treatment tank 10.

[0045] Preferably, a first alert message is issued when the oxygen indicator Ind has fallen below the first threshold SI since the introduction of the inert gas G. and that it has then exceeded after a second time period tb, i.e. at a second time T2 the first threshold SI as well as a second threshold S2 (see [Fig.2]). The second threshold value S2 is higher than the first threshold value SI and is set by the user. For example, the second threshold value S2 is 0.1 (without unit of measurement). In this case too, there is either a problem with the purity of the inert gas G and / or a possible problem with the sealing of the treatment tank 10.

[0046] If, as described above, the monitoring system 100 comprises a sampling chamber 11 with an inlet 12 and an outlet 13, the inerting state is further based on the total pressure Ptot. In this case, a third alert message is issued when the oxygen indicator Ind has fallen below the first threshold S1 and the total pressure Ptot has fallen below the third threshold S3 (third curve C3 in [Fig. 2]), the third alert message signaling in particular an obstruction of the inlet 12. Preferably, the partial oxygen pressure Pox, the total pressure Ptot, the value of the oxygen indicator Ind and the inerting state are displayed on the display 51 and / or delivered to the control output 52.

[0047] The use of an oxygen indicator Ind has an advantage, compared to taking into account only the partial pressure of oxygen Pox. Indeed, this advantage is that when the pressure and / or the temperature of the process varies, the value of the oxygen index expressed in Percentage of Oxygen by Volume (% Vol O2) remains permanently reliable. The operator can thus without any problem directly use this index value Ind to control his inerting process. Otherwise, without using the combination of Pox, Ptot and Temperature, the process variations and / or inerting fault could not be interpreted with certainty, because each parameter influences the others. This would have the impact of triggering thresholds incorrectly.

Claims

Claims

1. Method for monitoring the inerting of a process vessel (10) with an inert gas (G), comprising the following steps: - Providing a monitoring system (100) with the process vessel (10), an oxygen sensor (20), a pressure sensor (30) and an evaluation unit (40), in which the oxygen sensor (20) and the pressure sensor (30) are communicatively connected to the evaluation unit (40) and are arranged in terms of measurement so as to be adapted to be exposed to the inert gas (G), the evaluation unit (40) comprising an outlet unit (50), - Introducing the inert gas (G) into the process vessel (10), - Determining an oxygen partial pressure (Pox) by the oxygen sensor (20), - Determining a total pressure (Ptot) by the pressure sensor (30), - Determining an indicator of oxygen (Ind) based on the partial pressure of oxygen (Pox) and the total pressure (Ptot),wherein the oxygen indicator (Ind) comprises the quotient of the partial pressure of oxygen (Pox) and the total pressure (Ptot), - Outputting an inerting condition based on the oxygen indicator (Ind) from the output unit (50).,

2. Method according to claim 1, in which a first alert message is issued as an inerting state when the oxygen indicator (Ind) is greater than a first threshold value (SI) and a first period of time (ta) has been exceeded since the introduction of the inert gas (G), the first alert message signaling in particular a possible problem with the purity of the inert gas (G) and / or a possible problem with the sealing of the treatment tank (10).

3. Method according to any one of the preceding claims, in which a first alert message is emitted when the oxygen indicator (Ind) has fallen below a first threshold (SI) since the introduction of the inert gas (G) and has then exceeded after a second period of time (tb) the first threshold (SI) as well as a second threshold (S2), the first alert message signaling in particular a possible problem of purity of the inert gas (G) and / or a possible problem of sealing of the treatment tank (10).

4. A method according to any preceding claim, wherein the monitoring system (100) comprises a sample chamber (11) having an inlet (12) and an outlet (13), the inlet (12) and the outlet (13) being fluidically connected to the treatment tank (10), and the oxygen sensor (20) and the pressure sensor (30) being arranged in the sample chamber (11), the inerting state being further based on the total pressure (Ptot) and a third warning message being issued when the oxygen indicator (Ind) has fallen below a first threshold value (SI) and the total pressure (Ptot) has fallen below a third threshold value, the third warning message signaling in particular an obstruction of the inlet (12).

5. Method according to one of the preceding claims, wherein the output unit (50) comprises at least one display (51) and / or at least one control output (52) and the inerting state is displayed on the display (51) and / or is output on the control output (52).

6. Monitoring system (100) for monitoring inerting with an inert gas, comprising: - A treatment tank (10), - An oxygen sensor (20), - A pressure sensor (30), - An evaluation unit (40) with an output unit (41), in that the oxygen sensor (20) and the pressure sensor (30) are communicatively connected to the evaluation unit (40) and are exposed by measurement to the inert gas (G), in that the monitoring system (100) is capable of implementing the method according to any one of the preceding claims.

7. The monitoring system (100) of claim 6, wherein the monitoring system (100) comprises a sample chamber (11) with an inlet (12) and an outlet (13), wherein the inlet (12) and the outlet (13) are fluidically connected to the treatment tank (10) and the oxygen sensor (20) and the pressure sensor (30) are disposed in the sample chamber (11).

8. A monitoring system (100) according to claim 7, wherein a vacuum pump is connected to the outlet (13).

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