JPH09304311A - Spontaneous ignition testing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spontaneous ignition testing device which can automatically effect measurement starting action, such as start of counting or changing gas. SOLUTION: A sample temperature detector 2 detects the sample temperature T of a sample S by means of a thermocouple 1, and a stable temperature determining circuit 3 determines whether or not the sample temperature T has become stable at a set temperature Tset . If the sample temperature T rises from the room temperature and becomes stable in the vicinity of the set temperature Tset , for example, the stable temperature determining circuit 3 yields a measurement starting signal to cause a data processing device to start collecting data and to cause a solenoid valve drive circuit 4 to control solenoid valves 5, 6 to change the gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-ignition test device for measuring the time until spontaneous ignition is started by keeping a sample at a set temperature in an atmosphere such as oxygen gas or air.

[0002]

2. Description of the Related Art In the process of manufacturing a chemical substance, it may be necessary to temporarily store an intermediate product generated in the middle of the manufacturing process. Some of these intermediate products cause spontaneous ignition when left in a temperature environment above a certain level for a long time, and there are unknown conditions of temperature and time leading to the spontaneous ignition. Spontaneous ignition test equipment can maintain the temperature environment for safe storage and storage by keeping the sample of such intermediate product at a set temperature for a long time and measuring the time until spontaneous ignition starts. It is for checking time in advance.

As shown in FIG. 4, the above-mentioned spontaneous combustion test apparatus comprises an apparatus body 11 and an operation box 12.
The apparatus main body 11 can be mounted inside by inserting a sample holder 13 having a sample holding container 14 for storing a sample at its lower end from the top. Further, a temperature control device is provided in the device main body 11,
The sample temperature of the sample stored in the sample holding container 14 inside the apparatus can be kept at a constant set temperature. Further, on the front surface of the apparatus main body 11, a first port 15 for receiving an inert gas such as nitrogen gas and a second port 16 for receiving an oxygen gas, air, etc. are provided. These ports 15 and 16 are for allowing gas to flow into the interior of the device via electromagnetic valves, respectively. The operation box 12 is used to perform an operation of setting a set temperature of the temperature control device, an operation of operating a solenoid valve, and an operation of switching a gas flowing into the inside of the device body 11.

In the above spontaneous ignition test apparatus, first, a sample for examining the conditions of spontaneous ignition is stored in the sample holding container 14 and the sample holder 13 is attached to the apparatus main body 11. Next, the operation box 12 is operated to set the first port 1 inside the apparatus main body 11.
The inert gas from 5 is made to flow in, the preset temperature of the temperature control device is set, and the temperature control is started. Then
As shown in FIG. 5, when the temperature control is started at time t21, the sample temperature T gradually rises, and reaches substantially the set temperature Tset at time t22 and becomes stable. Then, when the sample temperature T stabilizes, the gas supplied to the inside of the apparatus main body 11 is switched to oxygen gas or the like from the second port 16, and the time until the sample in the sample holding container 14 starts spontaneous ignition is measured. Start.

Here, when the sample is spontaneously ignited by being kept at the set temperature Tset for a long time, the sample temperature T starts to rise at a time t23 shortly before that, and immediately before the spontaneous ignition. To rise. Therefore, this sample temperature T
The rapid increase in the temperature is detected by appropriate means, and the measurement is ended at time t24. At this time, the time from the time t22 when the measurement is started to this time t24 is the time until the sample starts spontaneous ignition. When a rapid rise in the sample temperature T is detected at this time t24, the safety device operates and immediately
By inflowing a large amount of the inert gas from the port 15 into the inside of the apparatus main body 11, it is possible to prevent the sample from actually igniting in advance and prevent the apparatus from being damaged.

The data of the sample temperature may be sent to a data processing device (not shown), and this data processing device may measure the time. At this time, a signal indicating the start or end of the measurement is sent to the data processing device to start or end the data collection.

[0007]

However, in the conventional spontaneous combustion test apparatus, after the temperature control is started at time t21, the operator monitors the rise of the sample temperature T in front of the apparatus to set the set temperature Tset. At the time t22, the measurement start operation was performed by visually observing that the measurement was stable. For this reason, the operator cannot leave the apparatus side until the sample temperature T becomes stable, which causes a problem that the measurement takes time. Further, since it is an operator's subjective judgment as to whether or not the sample temperature T is stable, there is a possibility that the measurement start time t22 may be different depending on the person, and the measurement time may be inaccurate. Further, at time t22 when the measurement is started, the electromagnetic valve of the first port 15 should be closed and the electromagnetic valve of the second port 16 should be opened to promptly switch the gas flowing into the inside of the apparatus main body 11 to oxygen gas or the like. There is also a problem that this gas switching operation is troublesome because it has to be done.

The present invention has been made in view of the above circumstances, and detects that the sample temperature is stable at a set temperature and automatically performs a measurement start operation such as the start of timing or gas switching. An object of the present invention is to provide a spontaneous combustion test device that can perform accurate measurement with less trouble.

[0009]

That is, in order to solve the above-mentioned problems, the present invention provides that the sample temperature detecting means detects the sample temperature and whether the sample temperature is stabilized at the set temperature by the judging means. judge. Then, for example, when the sample temperature rises from room temperature to reach the set temperature and there is almost no change in temperature, the determination means determines that the sample temperature is stable, and starts timing or switches the gas, for example. The measurement starting means automatically starts the measurement.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show one embodiment of the present invention, FIG. 1 is a block diagram showing the configuration of a spontaneous combustion test apparatus, and FIG. 2 shows changes in the sample temperature until it stabilizes at a set temperature in detail. 3 is an enlarged time chart showing the measurement start time, and FIG. 3 is an enlarged time chart showing the measurement start time for explaining an operation example of the temperature stability determination circuit. The same numbers are given to those having the same functions as those of the conventional example shown in FIGS. 4 and 5.

The spontaneous ignition test apparatus of this embodiment comprises an apparatus main body 11 and an operation box 12 similar to those shown in FIG. 4, and a sample holder 13 is attached to the apparatus main body 11 so that the sample The holding container 14 is arranged inside the apparatus. As shown in FIG. 1, the sample holding container 14 is a container having a vent hole at the bottom, and the sample S is placed in this container.
Is stored. Further, the thermocouple 1 is arranged in the sample holding container 14. The thermocouple 1 is connected to the sample temperature detector 2, and the sample temperature detector 2 measures the electromotive force of the thermocouple 1 to detect the sample temperature T which is the temperature near the sample S or the sample S. It has become.

The thermocouple 1 and the sample temperature detector 2
May be used in a temperature control device that controls the temperature for maintaining the sample temperature T at the set temperature Tset. Further, in the present embodiment, the sample temperature detecting means is configured by the thermocouple 1 and the sample temperature detector 2, but the sample temperature detecting means is not necessarily limited to this configuration as long as the sample temperature T can be detected.

Sample temperature T detected by the sample temperature detector 2
Is sent to a data processing device (not shown) and also to the temperature stability determination circuit 3. The temperature stability determination circuit 3 is a circuit that determines whether or not the sample temperature T is stable at the set temperature Tset. In order to determine that the sample temperature T is stable at the set temperature Tset, it is necessary that the sample temperature T reaches near the set temperature Tset and that the temperature change hardly disappears. For example, as shown by the curve A in FIG. 2, when the sample temperature T gradually approaches the set temperature Tset, it can be determined that the sample temperature T is stable only when it reaches the set temperature Tset. However, this curve B of FIG.
As shown in, when the sample temperature T once exceeds the set temperature Tset and overshoots, and gradually converges to the set temperature Tset while repeating the vibration, the time t
It cannot be determined immediately that the sample temperature T has reached the set temperature Tset at 1 or time t2, and it must be determined to be stable after time t3 when the vibration has sufficiently converged. Therefore, the temperature stability determination circuit 3 detects, for example, that the sample temperature T is within a predetermined range before and after the set temperature Tset and that the rate of change of the sample temperature T, that is, the absolute value of the differential value is equal to or less than the predetermined value. By doing so, it can be determined that it is stable. Further, when it is detected that the sample temperature T is within a predetermined range before and after the set temperature Tset for a predetermined time (a predetermined number of samples in the case of digital data), it can be determined that the temperature is stable.

However, the sample temperature T is temperature-controlled by the temperature control device so as to reach the set temperature Tset, and when the temperature difference between the sample temperature T and the set temperature Tset is large,
Since the temperature is controlled so that this temperature difference is always small, it is guaranteed that the sample temperature T is in the vicinity of the set temperature Tset even if the sample temperature T hardly changes over a certain period of time, and the temperature is stable. It can be determined that it did. However, as shown in the curve B of FIG. 2, when the sample temperature T causes an overshoot,
Since the differential value becomes 0 at each maximum point or minimum point of the vibration shown at the point b1 in the figure, it is not always necessary to judge that the absolute value of the differential value of the sample temperature T is equal to or less than a predetermined value. It is necessary that there be almost no temperature change over a certain length of time. Therefore, when the absolute value of the differential value of the sample temperature T becomes equal to or less than the predetermined value over a predetermined time, it can be determined that the temperature is stable. Further, the temperature difference between the maximum value and the minimum value of the sample temperature T within a predetermined time is the predetermined value Δ
It can be determined that the temperature is stable when it is T or less. The maximum value and the minimum value within the predetermined time are used because it is determined whether the temperature difference between the sample temperature T at the start and the end of the predetermined time is less than or equal to the predetermined value ΔT. This is because in the case of the period including the point b1 in the curve B, the sample temperature T at the start and the sample temperature T at the end almost coincide with each other, which may cause an erroneous determination.

When the judgment is made by the temperature difference of the sample temperature T within the above-mentioned predetermined time, the temperature stability judging circuit 3 causes the constant time (for example, each sample in the case of digital data) from the predetermined time to the predetermined time. The maximum value and the minimum value of the sample temperature T are detected, the temperature difference between them is calculated, and the temperature difference is compared with the predetermined value ΔT. Then, when the temperature difference within the predetermined time is equal to or smaller than the predetermined value ΔT, it is determined that the sample temperature T is stable at the set temperature Tset. For example, FIG.
In the example shown in, the time t12 is followed by a predetermined time tc.
Then, the temperature difference ΔT1 between the maximum value and the minimum value of the sample temperature T between the time t11 before this time and this time t12 is calculated and the predetermined value Δ
When compared with T, it is not determined that the sample temperature T is stable because ΔT1> ΔT. Also, at the time t14, when the temperature difference ΔT2 of the sample temperature T between the times t13 and t14 is calculated and compared with the predetermined value ΔT, ΔT2> ΔT is satisfied, so that it is not determined that the sample temperature T is stable. However, at the time t16, the temperature difference ΔT of the sample temperature T between the times t15 and t16
When 3 is calculated and compared with the predetermined value ΔT, ΔT3 <ΔT
Therefore, it is determined that the sample temperature T is stable. In the present embodiment, the predetermined time tc is set to, for example, about 30 seconds so that the temperature difference is always large when the sample temperature T is not near the set temperature Tset. Also, the predetermined value ΔT
Is about 0.5 ° C., which can be considered to be sufficiently stable.

In this embodiment, the judgment means is composed of the temperature stability judgment circuit 3 and realized by an analog circuit or a digital circuit. However, this is composed of a computer program and hardware for executing the program. You can also do it.

When the temperature stability determination circuit 3 determines that the sample temperature T is stable at the set temperature Tset, a measurement start signal is sent to the data processing device and the solenoid valve drive circuit 4. The solenoid valve drive circuit 4 is a drive circuit that controls the opening and closing of the solenoid valves 5 and 6 provided inside the apparatus body 11. The solenoid valve 5 is connected to the first port 15 which receives the supply of the inert gas shown in FIG. 4, and the solenoid valve 6 is connected to the second port 16 which receives the supply of the oxygen gas and the like. Then, the solenoid valve drive circuit 4 opens only the solenoid valve 5 by the operation at the start of the temperature control to allow the inert gas to flow into the inside of the apparatus main body 11, but the temperature stability determination circuit 3 sends a measurement start signal. When sent, the electromagnetic valve 5 is closed and the electromagnetic valve 6 is opened to allow oxygen gas or the like to flow into the inside of the apparatus main body 11. Therefore, the oxygen for spontaneous ignition is supplied to the sample S, and the measurement is started. Further, in the data processing device, when the measurement start signal is sent from the temperature stability determination circuit 3, the measurement is started by starting to collect the data of the sample temperature T. This data processor may measure the time from the start of measurement by an internal timer, or when collecting the sample temperature T as digital data, count the number of samples of the collected digital data. The time can also be measured by.

In this embodiment, the measurement starting means is
The electromagnetic valve drive circuit 4, the electromagnetic valves 5, 6 and the data processing device are included. However, here, in order to prevent the sample S from reacting with oxygen before starting the measurement,
Although the inert gas was flowing into the inside of the device main body 11,
When oxygen gas or the like is introduced from the beginning, it is not necessary for the solenoid valve drive circuit 4 to control the solenoid valves 5 and 6 to switch the gas when starting the measurement. Further, here, the case where the data of the sample temperature T is sent to the data processing device to measure the time has been described, but when the measurement is performed by the timer inside the spontaneous combustion test device, the temperature stability determination circuit 3 is used. It suffices to start the counting of the timer based on the measurement start signal issued by. That is, the measurement starting means is
At least the timing is started, and operations such as gas switching are performed as necessary.

As described above, according to the spontaneous ignition test apparatus of this embodiment, when the sample temperature T detected by the sample temperature detector 2 becomes stable at the set temperature Tset, the temperature stability determination circuit 3 determines this. , Causes the solenoid valve drive circuit 4 to switch the gas, and sends a measurement start signal to the data processing device. Therefore, the operator does not only perform the operation of flowing the inert gas into the apparatus main body 11 but also the operation of starting the temperature control by the temperature control device, and the measurement is automatically started thereafter. It becomes possible to perform other work away from the side of, and the labor of measurement can be reduced. Further, since the temperature stability determination circuit 3 objectively determines whether or not the change in the sample temperature T satisfies a predetermined condition, there is no variation in the start timing of measurement by the operator, and accurate measurement can be performed. . Moreover, even when gas switching is required at the start of measurement, the troublesomeness of this switching operation can be eliminated.

[0020]

As is apparent from the above description, according to the spontaneous ignition test apparatus of the present invention, it is detected that the sample temperature is stable at the set temperature, and the automatic start of timing and gas switching are performed. Since the measurement is performed and the measurement is started, the measurement can be performed without any trouble and the accurate measurement can be performed.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention and is a block diagram showing a configuration of a spontaneous combustion test apparatus.

FIG. 2 shows an embodiment of the present invention and is a time chart in which a measurement start time is enlarged in order to explain in detail the change until the sample temperature stabilizes at the set temperature.

FIG. 3 shows an embodiment of the present invention, and is a time chart in which a measurement start time is enlarged in order to explain an operation example of the temperature stability determination circuit.

FIG. 4 is a diagram showing an appearance of a spontaneous combustion test apparatus.

FIG. 5 is a time chart showing the operation of the spontaneous combustion test apparatus.

[Explanation of symbols]

 1 Thermocouple 2 Sample temperature detector 3 Temperature stability judgment circuit 4 Solenoid valve drive circuit 5 Solenoid valve 6 Solenoid valve S Sample T Sample temperature Tset Set temperature

Claims (1)

[Claims] 1. A self-ignition test device for measuring the time until spontaneous ignition starts while maintaining a sample at a set temperature in an atmosphere of a gas containing oxygen, and sample temperature detecting means for detecting the temperature of the sample or the vicinity of the sample, Determining means for determining whether or not the sample temperature detected by the sample temperature detecting means is stable at a set temperature, and measurement starting means for starting the measurement when the sample temperature is determined to be stable by the determining means, Spontaneous ignition test device characterized by having.