JP4554563B2 - Explosion-proof method and explosion-proof device - Google Patents

Description

  The present invention relates to an explosion-proof method and an explosion-proof device, and in particular, when an object that generates a combustible gas is placed in a tank to give a heating history, the explosion-proof method for maintaining the inside of the tank in an explosion-proof state by inflow of an inert gas and It relates to explosion-proof equipment.

Explosion-proof measures are taken for safety in devices that process objects that generate combustible gases. For example, a waste crushing apparatus is known that uses a minimum oxygen concentration (MOC) method for reducing oxygen concentration using water vapor as an inert gas (see, for example, Patent Document 1). Further, as a method different from the MOC method, there is known a method based on an LEL (Low Explosion Limit) method in which the concentration of a combustible gas is reduced by an inert gas such as nitrogen gas (see, for example, Patent Document 2). Yes.
Japanese Patent No. 3612454 (page 4, FIG. 5) Japanese Patent Laid-Open No. 2002-204968 (5th page, FIG. 3)

  However, in the apparatus of Patent Document 1 using the MOC method, it is necessary to always maintain the atmosphere inside the apparatus at a lower oxygen concentration state than the atmosphere. However, in such a device, it is difficult to completely seal the waste due to the presence of a waste inlet / outlet and a duct that discharges the combustible gas generated inside to the outside. It cannot be stopped. For this purpose, the inert gas must always flow into the apparatus at a certain flow rate. For this reason, there exists a possibility that the usage-amount of an inert gas may become enormous, so that the processing time of the object which generate | occur | produces combustible gas becomes long.

  In the apparatus of Patent Document 2 based on the LEL method, a large amount of combustible gas may be generated abruptly in the apparatus depending on the state of the object generating the combustible gas and the processing operation. In such a state, the inert gas must also flow into the apparatus quickly and in large quantities. If it is not in time, the explosion-proof property may be insufficient. Therefore, it is necessary to consider the case where such a large amount of inert gas is required to be introduced, resulting in an increase in the cost of the device.

  An object of the present invention is to provide an explosion-proof method and an explosion-proof device that can suppress the amount of inert gas used without increasing the cost of the device and that have no problem in explosion-proof performance.

In the following, means for achieving the above object and its effects are described.
The explosion-proof method according to claim 1 is a method of maintaining an explosion-proof state by inflow of an inert gas in the tank when an object that generates combustible gas is placed in the tank to give a heating history, In the initial stage of heating the object, based on the measured value of the oxygen concentration in the tank, the inert gas is set so that the oxygen concentration in the tank is lower than the oxygen control concentration set lower than the explosion limit concentration of oxygen. A combustible gas that executes a minimum oxygen concentration mode for controlling the amount of inflow of gas and that the combustible gas concentration in the tank is set lower than the explosive limit concentration of the combustible gas based on the measured value of the combustible gas concentration in the tank. When entering a low concentration region, the minimum oxygen concentration mode is stopped, and the inactive gas concentration in the tank is less than the inflammable gas control concentration set lower than the explosive limit concentration of the combustible gas. gas Wherein the shifts to the lower explosive limit mode for controlling the inflow.

  When an object that generates combustible gas is heated, a large amount of combustible gas tends to be generated abruptly at the beginning of heating. For this reason, in the initial stage of heating the object, the above-described minimum oxygen concentration mode is executed. That is, the inflow amount of the inert gas is controlled so that the oxygen concentration in the tank is equal to or lower than the oxygen control concentration set lower than the explosion limit concentration of oxygen. Since the oxygen concentration is controlled even if a large amount of flammable gas is suddenly generated, it is only necessary to reduce the concentration of oxygen flowing in from the outside regardless of the flammable gas concentration. Even if it does not flow into the device in large quantities, the explosion-proof effect can be sufficiently improved.

  Thereafter, when the combustible gas concentration in the tank enters a combustible gas low concentration region set lower than the explosive limit concentration of the combustible gas, the minimum oxygen concentration mode is stopped. Then, the explosion lower limit mode described above is executed. That is, the flow shifts to a state where the inflow amount of the inert gas is controlled so that the combustible gas concentration in the tank is equal to or lower than the combustible gas control concentration set lower than the explosive limit concentration of the combustible gas. At this time, the combustible gas concentration is already in the low combustible gas concentration region, and the amount of combustible gas is decreasing, so even if it is not the oxygen concentration control but also the combustible gas concentration control, there is little inertness It will be possible to follow sufficiently with the amount of gas inflow. For this reason, it moves to the explosion lower limit mode. And in this explosion lower limit mode, unlike the oxygen which always flows in, since the combustible gas is generated from the substance in the tank, the amount of combustible gas generated further decreases. In the end, there are cases where almost no occurrence occurs. Therefore, the inflow amount of the inert gas used for controlling the combustible gas concentration is extremely small, and there is a case where the inflow may not be performed finally. For this reason, the usage-amount of an inert gas can be suppressed and an explosion-proof effect can be raised.

  As described above, according to the explosion-proof method of the present invention, it is not necessary to quickly and massively flow the inert gas into the apparatus during the heating history period, and a low flow rate is sufficient. Therefore, the cost of the apparatus related to the inflow of the inert gas is sufficient. There is no uplift. In this way, the amount of inert gas used can be suppressed without increasing the cost of the apparatus, and there is no problem in explosion-proof performance.

  The explosion-proof method according to claim 2, wherein the minimum oxygen concentration mode is executed when it becomes difficult to control the explosion-proof lower limit mode to be lower than the combustible gas control concentration in the explosion lower limit mode. In the minimum oxygen concentration mode, when the combustible gas concentration in the tank enters the low combustible gas concentration region, the lower explosion limit mode is restored.

  Depending on the heating atmosphere, the nature of the object, or the combustible gas component, the amount of combustible gas generated may increase again after the generation of a large amount of combustible gas from the object is completed. In such a case, if the explosion lower limit mode is continued, the combustible gas concentration cannot be quickly reduced, and there is a risk that the combustible gas concentration may be significantly increased beyond the combustible gas control concentration. When it becomes difficult to control the flammable gas concentration below the flammable gas control concentration in this way, the explosion-proof property is achieved even with a small amount of inert gas inflow by executing the minimum oxygen concentration mode again. be able to. When the combustible gas concentration enters the low combustible gas concentration region, the explosion lower limit mode is restored. As a result, the inflow amount of the inert gas can be suppressed.

Even when the combustible gas concentration increases again in this way, the amount of inert gas used can be suppressed without causing an increase in the cost of the apparatus, and there is no problem in explosion-proof performance.
In the explosion-proof method according to claim 3, in claim 2, when the state where the combustible gas concentration in the tank exceeds the combustible gas control concentration continues the judgment reference time, the combustible gas concentration in the tank is set. The present invention is characterized in that it is difficult to control the combustible gas control concentration to be equal to or lower than the combustible gas control concentration.

  The controllability of the combustible gas concentration can be determined to be difficult when the state where the combustible gas concentration in the tank exceeds the combustible gas control concentration continues the determination reference time. By executing the minimum oxygen concentration mode along with this determination, the explosion-proof property can be achieved even with a small inflow of inert gas.

The explosion-proof method according to a fourth aspect is characterized in that, in any one of the first to third aspects, the combustible gas control concentration corresponds to an upper limit concentration of the combustible gas low concentration region.
Thus, the combustible gas control concentration can be the upper limit concentration of the low combustible gas concentration region, and the above-described effects can be appropriately generated.

The explosion-proof method according to claim 5 is characterized in that, in any one of claims 1 to 4, the minimum oxygen concentration mode is executed before heating the object.
This can further ensure explosion-proof properties.

The explosion-proof method according to a sixth aspect is characterized in that in any one of the first to fifth aspects, the object is a canister installed in an internal combustion engine for a vehicle.
The canister can be given as an object that generates combustible gas. Since this canister adsorbs hydrocarbons such as gasoline and light oil, it generates hydrocarbon gas as combustible gas by heating. Therefore, for example, in an apparatus that gives a heating history to test the durability of a canister, as described above, there is no increase in cost, the amount of inert gas used can be suppressed, and a problem is also caused in explosion-proof performance. Absent.

  The explosion-proof device according to claim 7 is a device that maintains an explosion-proof state by inflow of an inert gas in the tank when an object that generates combustible gas is placed in the tank to give a heating history, An oxygen concentration measuring means in the tank, a combustible gas concentration measuring means in the tank, an inert gas inflow means for adjusting the amount of inflow to flow the inert gas into the tank, and an initial heating of the object And controlling the inert gas inflow means so that the oxygen concentration in the tank is lower than the oxygen control concentration set lower than the explosion limit concentration of oxygen based on the measured value of the oxygen concentration by the oxygen concentration measuring means. And the tank based on the measured value of the combustible gas concentration by the combustible gas concentration measuring means during the period in which the minimum oxygen concentration mode executing means controls the inert gas inflow means. When the combustible gas concentration enters the low combustible gas concentration region set lower than the explosive limit concentration of the combustible gas, the control of the inert gas inflow means by the minimum oxygen concentration mode execution means is stopped, and the tank And a lower explosion limit mode execution means for controlling the inert gas inflow means so that the combustible gas concentration in the gas is equal to or lower than the combustible gas control concentration set lower than the explosive limit concentration of the combustible gas. And

  When an object that generates combustible gas is heated, a large amount of combustible gas tends to be generated abruptly at the beginning of heating. For this reason, the minimum oxygen concentration mode execution means controls the inert gas inflow means so that the oxygen concentration in the tank is equal to or lower than the oxygen control concentration at the initial stage of heating the object. The control of the inert gas inflow means by the minimum oxygen concentration mode execution means is the control of the oxygen concentration. It is only necessary to reduce the concentration. Therefore, it is not necessary for the inert gas from the inert gas inflow means to flow into the apparatus quickly and in large quantities. Therefore, even in a low-cost configuration in which the inert gas inflow means cannot flow into the apparatus quickly and in large quantities. The explosion-proof effect can be increased sufficiently.

  Thereafter, when the combustible gas concentration in the tank enters the low combustible gas concentration region, the lower explosion limit mode execution means stops the control of the inert gas inflow means by the minimum oxygen concentration mode execution means. Then, the inert gas inflow means is controlled so that the combustible gas concentration in the tank is equal to or lower than the combustible gas control concentration. At the time of this control, since the combustible gas concentration is already in the low combustible gas concentration range, and the amount of combustible gas is decreasing, the inert gas inflow means is not controlled by the oxygen concentration but also by controlling the combustible gas concentration. However, even a configuration that cannot flow into the apparatus quickly and in large quantities can be sufficiently followed. Therefore, the lower explosion limit mode execution means shifts to a state of controlling the inert gas inflow means. When the lower explosive limit mode execution means is controlled, the amount of combustible gas generated is further reduced since the combustible gas is generated from the substance in the tank, unlike the oxygen that always flows in. In the end, there are cases where almost no occurrence occurs. Therefore, the inflow amount of the inert gas used for controlling the combustible gas concentration by the explosive lower limit mode execution means becomes extremely small, and it may not be necessary to finally perform the inflow. For this reason, the usage-amount of an inert gas can be suppressed and an explosion-proof effect can be raised.

  As described above, the explosion-proof device of the present invention does not need to flow the inert gas quickly and in a large amount during the heating history period, so that even a configuration in which the inert gas inflow means cannot flow in the device quickly and in large amounts is sufficient. In addition, the explosion-proof effect can be increased, and the cost of the inert gas inflow means is not increased. In this way, the amount of inert gas used can be suppressed without causing an increase in cost, and there is no problem in explosion-proof performance.

  The explosion-proof device according to claim 8, wherein the combustible gas concentration is measured by the combustible gas concentration measuring means during the period when the lower explosion limit mode execution means controls the inert gas inflow means. Based on the value, combustible gas concentration control difficulty judging means for judging whether or not it is difficult to control the combustible gas concentration in the tank below the combustible gas control concentration in the explosion lower limit mode execution means, During the period when it is determined by the combustible gas concentration control difficulty determining means that it is difficult to control the combustible gas concentration in the tank below the combustible gas control concentration, the lower explosion limit mode executing means is The control for the inert gas inflow means is temporarily stopped, and the inert gas flow is obtained by the minimum oxygen concentration mode execution means. Characterized in that to execute the control.

  Depending on the heating atmosphere, the nature of the object, or the combustible gas components, the generation of combustible gas may increase again after the generation of combustible gas from the object has once decreased. In such a case, the control of the inert gas inflow means by the explosive lower limit mode execution means cannot quickly reduce the combustible gas concentration, which may cause a significant increase in the combustible gas concentration exceeding the combustible gas control concentration. There is. Therefore, the explosive lower limit mode execution means during the period when the explosive lower limit mode execution means determines that it is difficult to control the combustible gas concentration below the combustible gas control concentration by the explosive lower limit mode execution means. The control by itself is stopped and the control by the minimum oxygen concentration mode execution means is executed.

  By doing in this way, explosion-proof property can be achieved again even with a small flow rate of inert gas. And since the inert gas inflow means is controlled by the explosive lower limit mode execution means outside the period, the flow rate of the inert gas can be suppressed.

Even when the combustible gas concentration increases again in this way, the amount of inert gas used can be suppressed without causing an increase in the cost of the apparatus, and there is no problem in explosion-proof performance.
In the explosion-proof device according to claim 9, in claim 8, the combustible gas concentration control difficulty determination means is a period in which the lower explosion limit mode execution means controls the inert gas inflow means. When it is difficult to control the flammable gas concentration in the tank below the flammable gas control concentration when the flammable gas concentration in the tank exceeds the flammable gas control concentration and the judgment reference time is continued. It is characterized by being.

  The combustible gas concentration control difficulty determining means can determine that it is difficult when the state where the combustible gas concentration in the tank exceeds the combustible gas control concentration continues the determination reference time. As a result, the minimum oxygen concentration mode execution means is controlled again, and the explosion-proof property can be achieved even with a small inert gas flow rate.

In the explosion-proof device according to claim 10, in any one of claims 7 to 9, the combustible gas control concentration corresponds to an upper limit concentration of the combustible gas low concentration region.
Thus, the combustible gas control concentration can be the upper limit concentration of the low combustible gas concentration region, and the above-described effects can be appropriately generated.

An explosion-proof device according to an eleventh aspect is characterized in that in any one of the seventh to tenth aspects, the minimum oxygen concentration mode execution means is activated before heating the object.
This can further ensure explosion-proof properties.

In an explosion-proof device according to a twelfth aspect, in any one of the seventh to eleventh aspects, the object is a canister installed in an internal combustion engine for a vehicle.
The canister can be given as an object that generates combustible gas. Since this canister adsorbs hydrocarbons such as gasoline and light oil, it generates hydrocarbon gas as combustible gas by heating. Therefore, for example, by applying the explosion-proof device of the present invention to a device that gives a heating history to test the durability of the canister, it is possible to suppress the amount of inert gas used without incurring a cost increase as described above, and There is no problem with explosion-proof performance.

[Embodiment 1]
FIG. 1 is a block diagram showing a schematic configuration of a heating device 2 to which the explosion-proof device of the invention described above is applied.

  The heating device 2 includes a thermostat 6 for heating an object giving a heating history (here, the canister 4 of the vehicle internal combustion engine), a gas cylinder 8 for supplying an inert gas into the thermostat 6, and an oxygen concentration in the thermostat 6. An oxygen concentration measuring device 10 for measuring, a combustible gas concentration measuring device 12 for measuring the combustible gas concentration in the thermostat 6 and a control device 14 are provided. In the present embodiment, nitrogen gas is used as the inert gas, and the combustible gas that is subject to explosion protection is hydrocarbon (HC) gas such as gasoline or light oil generated from the canister 4.

  The constant temperature bath 6 includes a heating device 6a for heating the inside of the bath and a temperature sensor 6b for measuring the temperature in the bath. The control device 14 adjusts the amount of heat generated by the heating device 6a so that the temperature inside the tank measured by the temperature sensor 6b becomes the target temperature. Here, the heating device 6a is an electric heater, so that the amount of electricity is adjusted. A duct 6c is provided to release pressure when the pressure in the thermostatic chamber 6 rises, and a lid 6d is provided to prevent outside air from flowing back through the duct 6c from the outside. The lid 6d is opened by a pressure difference when the inside of the tank is at a higher pressure than the outside air and discharges the gas in the tank to the outside.

  An electromagnetic valve 8b for adjusting the flow rate is provided in the nitrogen gas supply path 8a from the gas cylinder 8 into the tank. As will be described later, the control device 14 adjusts the electromagnetic valve 8b for adjusting the flow rate based on the measurement result by the oxygen concentration measuring device 10 or the combustible gas concentration measuring device 12, thereby providing the inside of the tank while the heating history is being given to the canister 4. Is kept in an explosion-proof state.

  The control device 14 is an electronic control device including an input / output device with a computer at the center, and executes processing as shown in the flowcharts of FIGS. 2 and 3 based on a program.

  The heating history process (FIG. 2) and the control selection process (FIG. 3) in which the explosion-proof method of the present invention is executed will be described. These processes are processes that are repeatedly interrupted and executed periodically. The steps in the flowchart corresponding to the individual processing contents are represented by “S˜”.

  When the heating history process (FIG. 2) is started, it is first determined whether or not preparation for starting the heating history process is completed (S100). Here, the preparation for starting the heating history process is completion of disposition of the canister 4 in the thermostat 6, start of inflow of nitrogen gas into the thermostat 6, and start of heating of the thermostat 6. The placement of the canister 4 in the thermostat 6 is performed by an operator (possibly a transport device). The start of the inflow of nitrogen gas into the thermostat 6 and the start of the temperature rise of the thermostat 6 are arranged in the canister 4. This is done by the operator operating the control device 14 after completion. By preliminary control of the control device 14 activated by this operation, nitrogen gas starts to flow into the thermostat 6 and a MOC (Minimum Oxygen Concentration) mode process described later is executed, so that the oxygen concentration in the thermostat 6 is increased. Is reduced to an oxygen control concentration Mcon set lower than the MOC level. Thereafter, the temperature increase of the thermostatic chamber 6 is started (here, the target temperature is 120 ° C.), and the start preparation is completed by the temperature increase start.

  Therefore, in a state where the temperature rise of the thermostat 6 has not been reached (no in S100), the start preparation state (S102) continues, and the MOC (minimum oxygen concentration) mode execution flag Fmoc is set to ON (S104). Will continue. This state is a state before timing t0 in the timing chart of FIG. 4 showing an example of control. As shown in FIG. 4, the MOC level has an oxygen concentration of 10% (the same applies to the volume% or less), and the oxygen control concentration Mcon is set to 8%. That is, the oxygen control concentration Mcon is lower than the MOC level corresponding to the explosion limit concentration of oxygen.

  When the temperature rise of the thermostat 6 is started and the preparation for starting the heating history process is completed (yes in S100: t0), it is next determined whether or not the MOC mode execution flag Fmoc is ON (S106). Here, as described above, the processing for setting the MOC mode execution flag Fmoc to ON in step S104 has been performed until immediately before (S104). Therefore, it is determined as yes in step S106, and then, after the initial heating period, the state where the combustible gas concentration measured by the combustible gas concentration measuring device 12 is equal to or less than the combustible gas control concentration Lcon continues the determination reference time. It is determined whether or not (S108). This determination is for determining a state in which the rapid generation of HC gas from the canister 4 where heating has started has been reduced. Here, the initial heating period is a period in which the increase in the combustible gas concentration at the start of heating is rapid, and is set based on experiments and the like in advance. The combustible gas control concentration Lcon is set to 1/4 (2500 ppm) of the LEL level of HC gas (explosion limit concentration of combustible gas: 10000 ppm).

  If it is assumed that it is the heating initial period (no in S108), the processing in the current control cycle is terminated as it is. Thereafter, as long as it is determined as no in step S108, the state of Fmoc = ON continues.

  Based on the setting state of the MOC mode execution flag Fmoc, the processing contents in the control selection process (FIG. 3) are different. As described above, when Fmoc = ON, it is determined yes in step S150 of the control selection process (FIG. 3). Therefore, the MOC mode process is executed (S152). In the MOC mode process, the electromagnetic valve 8b is adjusted so that the oxygen concentration measured by the oxygen concentration measuring device 10 becomes the oxygen control concentration Mcon which is the target concentration, and the gas cylinder 8 through the nitrogen gas supply path 8a. This is a process for controlling the flow rate of nitrogen gas flowing into the thermostat 6.

  Therefore, the concentration of HC gas in the thermostatic chamber 6 rapidly rises to a high concentration due to the rapid generation of HC gas from the canister 4 after the start of heating, but the supply amount of nitrogen gas from the gas cylinder 8 to the thermostatic chamber 6 is HC. Regardless of the gas concentration, the oxygen concentration in the thermostatic chamber 6 is controlled. As a result, even if the HC gas concentration is equal to or higher than the LEL level (t1 to t2 in FIG. 4), the oxygen concentration is sufficiently lower than the MOC level, so that explosion-proof properties can be maintained.

  Returning to the description of the heating history process (FIG. 2). After the initial heating period, the rapid generation of HC gas from the canister 4 is stopped, so that the HC gas concentration in the thermostatic chamber 6 is lowered mainly by the discharge of gas from the lid 6d. As a result, the combustible gas concentration measured by the combustible gas concentration measuring device 12 becomes equal to or lower than the combustible gas control concentration Lcon (t3). If the state of combustible gas concentration ≦ Lcon continues the determination reference time (yes in S108: t4), it can be determined that the combustible gas low concentration region has been entered. Next, the MOC mode execution flag Fmoc is set to OFF (S110). ), And ends the process in the current control cycle. Note that the determination reference time in step S108 is a time for reliably determining that the combustible gas concentration ≦ Lcon by excluding the temporary decrease in the combustible gas concentration.

  In the next control cycle, since Fmoc = OFF (no in S106), it is determined whether or not the state where the combustible gas concentration is higher than the combustible gas control concentration Lcon continues the determination reference time (S112). . This determination is for determining a state in which the generation of HC gas from the canister 4 has risen again. The determination reference time in step S112 is a time for reliably determining the state in which the generation of HC gas has risen again.

  If the combustible gas concentration> Lcon does not continue the determination reference time (no in S112), the process in the current control cycle is terminated as it is. Therefore, as long as it is determined no in step S112, the state of Fmoc = OFF continues (from t4).

  Since Fmoc = OFF, no is determined in step S150 in the control selection process (FIG. 3). Therefore, the MOC mode processing shifts to LEL (lower explosion limit) mode processing (S154). In the LEL mode process, the electromagnetic valve 8b is adjusted so that the combustible gas concentration measured by the combustible gas concentration measuring device 12 becomes the combustible gas control concentration Lcon set as the target concentration, and the nitrogen gas from the gas cylinder 8 is adjusted. This is a process for controlling the flow rate of nitrogen gas flowing into the constant temperature bath 6 through the supply path 8a.

  Therefore, the supply amount of nitrogen gas from the gas cylinder 8 into the thermostat 6 is controlled according to the combustible gas concentration in the thermostat 6 regardless of the oxygen concentration. In this way, control is performed so that the combustible gas concentration becomes the combustible gas control concentration Lcon in the combustible gas concentration state that has already decreased to the combustible gas control concentration Lcon or less due to the decrease in the amount of combustible gas generated from the canister 4. Become. Therefore, the nitrogen gas can maintain the combustible gas concentration at the combustible gas control concentration Lcon even at a small flow rate (from t4 in FIG. 4), and sufficient explosion-proof properties can be obtained. Although the heating history process shown in FIG. 4 is performed at 120 ° C. for 2 days, the timing t4 usually occurs around 6 hours from the start of the process.

  Note that another example of control is shown in the timing chart of FIG. As shown here, once Fmoc = OFF once in the same process (t10 to t14) as shown in FIG. 4, the amount of HC gas generated from the canister 4 is increased again, and the combustible gas concentration> Lcon is determined as the determination reference time. Is continued (yes in step S112: t15), Fmoc is returned to ON (S104). As a result, in the control selection process (FIG. 3), the determination in step S150 is yes, so that the MOC mode process is temporarily executed instead of the LEL mode process (S152). This makes it possible to maintain explosion resistance without increasing the nitrogen gas flow rate.

  If the flammable gas concentration ≦ Lcon continues the determination reference time again (yes in S108), Fmoc = OFF (S110), so that the process can return to the LEL mode process (S154). Also in this case, since the combustible gas concentration has already decreased below the combustible gas control concentration Lcon, the nitrogen gas can be adjusted to the combustible gas control concentration Lcon even with a small flow rate, and sufficient explosion-proof property can be maintained.

  In the configuration described above, the relationship with the claims corresponds to the oxygen concentration measuring device 10 corresponding to the oxygen concentration measuring means and the combustible gas concentration measuring device 12 corresponding to the combustible gas concentration measuring means. The gas cylinder 8, the nitrogen gas supply path 8a, the electromagnetic valve 8b, and the control device 14 correspond to inert gas inflow means, and steps S152 and S154 executed by the control device 14 correspond to processing as the inert gas inflow means. The control device 14 corresponds to the minimum oxygen concentration mode execution means, the lower explosion limit mode execution means, and the combustible gas concentration control difficulty determination means. Steps S100, S104, S106, S150, and S152 executed by the control device 14 correspond to processing as the minimum oxygen concentration mode execution means. Steps S106 to S110, S150, and S154 correspond to processing as explosive lower limit mode execution means, and step S112 corresponds to processing as combustible gas concentration control difficulty determination means. A combination of the gas cylinder 8, the nitrogen gas supply path 8a, the electromagnetic valve 8b, the oxygen concentration measuring device 10, the combustible gas concentration measuring device 12, and the control device 14 corresponds to an explosion-proof device.

According to the first embodiment described above, the following effects can be obtained.
(I). When the canister 4 is heated, a large amount of HC gas tends to be generated abruptly at the initial stage of heating. Therefore, in the heating history process (FIG. 2) and the control selection process (FIG. 3) executed by the control device 14, at the initial stage of heating of the canister 4, the gas cylinder is set so that the oxygen concentration in the thermostatic chamber 6 is lower than the oxygen control concentration Mcon. The amount of nitrogen gas flowing in from 8 is controlled (S152). Since nitrogen gas inflow control in this MOC mode process is control of oxygen concentration, even if a large amount of HC gas is generated suddenly, it is only necessary to reduce the concentration of oxygen flowing from the outside. The nitrogen gas from the gas cylinder 8 does not need to flow into the thermostat 6 quickly and in large quantities. For this reason, even if the configuration of the gas cylinder 8, the nitrogen gas supply path 8a, the electromagnetic valve 8b, and the control device 14 does not allow nitrogen gas to flow into the thermostat 6 quickly and in large quantities, the explosion-proof effect can be sufficiently improved.

  Thereafter, when the HC gas concentration in the thermostatic chamber 6 becomes equal to or lower than the combustible gas control concentration Lcon set lower than the LEL level, the controller 14 stops the MOC mode because it enters the low combustible gas concentration region. Then, the mode is switched to the LEL mode (S154), and the nitrogen gas flow rate is controlled so that the HC gas concentration in the thermostatic chamber 6 is equal to or lower than the combustible gas control concentration Lcon. Since the HC gas concentration is already lower than the combustible gas control concentration Lcon at the start of the control, the nitrogen gas is rapidly and massively supplied in the thermostat 6 even if the HC gas concentration control is executed instead of the oxygen concentration control. The explosion-proof effect can be sufficiently increased even in a configuration that cannot flow into the tank. In addition, in this state, the amount of HC gas generated is further reduced and finally hardly generated. Therefore, the inflow amount of nitrogen gas used for controlling the HC gas concentration is extremely small, and finally it is not necessary to perform the inflow. For this reason, the usage-amount of nitrogen gas can be suppressed and an explosion-proof effect can be improved.

  Thus, since it is not necessary to flow a large amount of nitrogen gas into the constant temperature bath 6 during the heating history process for the canister 4, the gas cylinder 8, the nitrogen gas supply path 8a, the electromagnetic valve 8b and the control device 14 can be quickly and Even in a configuration in which nitrogen gas cannot flow into the thermostat 6 in a large amount, the explosion-proof effect can be sufficiently improved. For this reason, the usage-amount of nitrogen gas can be suppressed, without causing the cost increase of the heating apparatus 2, and a problem does not arise in explosion-proof performance.

In addition, since the MOC mode process (S152) is executed in advance before the start of heating, the explosion-proof property is further ensured.
(B). Depending on the heating atmosphere in the thermostatic chamber 6, the nature of the canister 4, or the fuel component, the amount of HC gas generated from the canister 4 may once decrease and then increase again. . In such a case, if the LEL mode (S154) is continued, the HC gas concentration cannot be quickly reduced, and the combustible gas control concentration Lcon may be exceeded. Therefore, in the situation where it is determined as yes in step S112, that is, in the period when it is determined that it is difficult to control the HC gas concentration below the combustible gas control concentration Lcon by the control in the LEL mode, instead of the LEL mode. The nitrogen gas inflow control in the MOC mode (S152) is executed.

  By doing in this way, explosion-proof property can be achieved again even with a small flow rate of nitrogen gas. And since it becomes LEL mode other than such a period, nitrogen gas flow volume can be suppressed.

  Thus, even when the HC gas concentration rises again, it can be dealt with, the use amount of the nitrogen gas can be suppressed without causing an increase in the cost of the heating device 2, and there is no problem in the explosion-proof performance.

[Other embodiments]
(A). In step S112 of the heating history process (FIG. 2), it was determined whether or not the state where the combustible gas concentration is higher than the combustible gas control concentration Lcon continues the determination reference time. Instead, a determination reference concentration may be set between the LEL level and the combustible gas control concentration Lcon, and when the determination reference concentration is exceeded, yes may be determined in step S112.

  (B). In the heating history process (FIG. 2), the combustible gas control concentration Lcon is set to the upper limit of the combustible gas low concentration region, but the combustible gas control concentration Lcon may be set higher than the combustible gas low concentration region, It may be set inside the combustible gas low concentration region. Both may be set lower than the explosion limit concentration (LEL level) of the combustible gas.

  (C). Although the canister of the internal combustion engine for vehicles has been mentioned as the object that generates the combustible gas, the heating history processing of other objects is also performed by the processing as in the first embodiment and the above (a) and (b). The effects described in the first embodiment can be produced.

  (D). The electromagnetic valve 8b adjusts the inflow amount of nitrogen gas into the tank by on / off control. However, the inflow rate may be controlled more smoothly by adjusting the inflow speed by valve opening control.

FIG. 2 is a block diagram illustrating a schematic configuration of the heating device according to the first embodiment. The flowchart of the heating history process which the control apparatus of Embodiment 1 performs. 5 is a flowchart of a control selection process executed by the control device according to the first embodiment. 4 is a timing chart illustrating an example of processing according to the first embodiment. 4 is a timing chart illustrating an example of processing according to the first embodiment.

Explanation of symbols

  2 ... heating device, 4 ... canister, 6 ... constant temperature bath, 6a ... heating device, 6b ... temperature sensor, 6c ... duct, 6d ... lid, 8 ... gas cylinder, 8a ... nitrogen gas supply path, 8b ... electromagnetic valve, 10 ... Oxygen concentration measuring device, 12 ... combustible gas concentration measuring device, 14 ... control device.

Claims (12)

When an object that generates combustible gas is placed in a tank to give a heating history, the tank is maintained in an explosion-proof state by inflow of inert gas,
In the initial stage of heating the object, based on the measured value of the oxygen concentration in the tank, the inert gas is set so that the oxygen concentration in the tank is lower than the oxygen control concentration set lower than the explosion limit concentration of oxygen. Run the minimum oxygen concentration mode to control the inflow of
Based on the measured value of the combustible gas concentration in the tank, the minimum oxygen concentration mode is stopped when the combustible gas concentration in the tank enters a low combustible gas concentration region set lower than the explosion limit concentration of the combustible gas. Then, transition to a lower explosion limit mode for controlling the inflow of the inert gas so that the combustible gas concentration in the tank is equal to or lower than the combustible gas control concentration set lower than the explosive limit concentration of the combustible gas. Explosion-proof method characterized by that. In Claim 1, when it becomes difficult to control to become below the flammable gas control concentration during the explosion lower limit mode, the minimum oxygen concentration mode is executed, and the tank is operated during the minimum oxygen concentration mode. The explosion-proof method is characterized by returning to the lower explosion limit mode when the combustible gas concentration in the gas enters the low combustible gas concentration region. In Claim 2, when the state in which the combustible gas concentration in the tank exceeds the combustible gas control concentration continues the determination reference time, the combustible gas concentration in the tank is set to be equal to or less than the combustible gas control concentration. An explosion-proof method, characterized in that it is when control becomes difficult. 4. The explosion-proof method according to claim 1, wherein the combustible gas control concentration corresponds to an upper limit concentration of the combustible gas low concentration region. The explosion-proof method according to any one of claims 1 to 4, wherein the minimum oxygen concentration mode is executed before heating the object. 6. The explosion-proof method according to claim 1, wherein the object is a canister installed in an internal combustion engine for a vehicle. When an object that generates combustible gas is placed in a tank to give a heating history, the apparatus maintains an explosion-proof state by inflow of inert gas in the tank,
Means for measuring oxygen concentration in the tank;
Combustible gas concentration measuring means in the tank;
An inert gas inflow means for adjusting the amount of inflow to flow the inert gas into the tank;
In the initial stage of heating the object, based on the measured value of the oxygen concentration by the oxygen concentration measuring means, the inertness is set so that the oxygen concentration in the tank is lower than the oxygen control concentration set lower than the explosion limit concentration of oxygen. Minimum oxygen concentration mode execution means for controlling the gas inflow means;
Based on the measured value of the combustible gas concentration by the combustible gas concentration measuring means during the period in which the minimum oxygen concentration mode execution means controls the inert gas inflow means, the combustible gas concentration in the tank is determined by the combustible gas concentration. When entering the low combustible gas concentration region set lower than the explosion limit concentration of gas, the control to the inert gas inflow means by the minimum oxygen concentration mode execution means is stopped, the combustible gas concentration in the tank is Explosive lower limit mode execution means for controlling the inert gas inflow means so as to be equal to or lower than the combustible gas control concentration set lower than the explosive limit concentration of the combustible gas;
Explosion-proof device characterized by comprising. The execution of the lower explosion limit mode according to claim 7, wherein the lower explosion limit mode execution means controls the inert gas inflow means, based on the measured value of the combustible gas concentration by the combustible gas concentration measurement means. In the means, combustible gas concentration control difficulty determining means for determining whether it is difficult to control the combustible gas concentration in the tank below the combustible gas control concentration, and
During the period when it is determined by the combustible gas concentration control difficulty determining means that it is difficult to control the combustible gas concentration in the tank below the combustible gas control concentration, the lower explosion limit mode executing means is An explosion-proof device, wherein the control for the inert gas inflow means is temporarily stopped, and the control of the inert gas inflow means by the minimum oxygen concentration mode execution means is executed. 9. The combustible gas concentration control difficulty determining means according to claim 8, wherein the combustible gas concentration in the tank is the combustible gas during a period when the lower explosion limit mode execution means controls the inert gas inflow means. Explosion-proof, characterized in that it is difficult to control the combustible gas concentration in the tank below the combustible gas control concentration when the control reference concentration exceeds the judgment reference time. apparatus. The explosion-proof device according to claim 7, wherein the combustible gas control concentration corresponds to an upper limit concentration of the combustible gas low concentration region. The explosion-proof device according to claim 7, wherein the minimum oxygen concentration mode execution unit is activated before heating the object. The explosion-proof device according to any one of claims 7 to 11, wherein the object is a canister installed in an internal combustion engine for a vehicle.

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