JPS5824204Y2 - Spontaneous ignition test device - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an improvement of a spontaneous ignition test device.

This spontaneous ignition test device is equipped with a thermocouple that detects the temperature inside the jacket and a thermocouple that detects the sample temperature in a jacket that houses a sample in a constant temperature bath kept at a constant temperature. The differential output of the thermocouple is fed back to the temperature controller in the jacket, and the temperature inside the jacket is controlled to follow the rise in sample temperature due to the introduction of oxygen into the sample cell, and the output of one thermocouple is recorded on a recorder. This device measures the ignition characteristics of a sample from the recorded results.

A conventional spontaneous ignition test device will be explained in more detail with reference to FIG. 1, which schematically shows the conventional spontaneous ignition test device.

In Figure 1, 1 is a constant temperature bath, 2 is a heat insulating jacket, and 3
is a heater, 4 is a heat insulating member, 5 is a sample, 6 and 7 are thermocouples, 8 is a purge gas source, 9 is a gas flow path, 10 is a temperature controller,
11 is a recorder, 12 is a spreader, 13 is a temperature control unit, 1
4 is a heater.

The inside of the constant temperature bath 1 is maintained at a constant temperature with a uniform temperature distribution by a temperature controller 13, a heater 14, and a spreader 12.

A heat insulating jacket 2 is provided inside the constant temperature bath 1, and a sample 5 is loaded into the heat insulating jacket 2 (in a sample cell).

Further, inside the heat insulating jacket 2, a thermocouple 7 for detecting the internal temperature of the jacket and a thermocouple 6 for detecting the temperature of the sample 5 are provided.

The thermocouples 6 and 7 are connected so that a signal voltage is differentially output, and this signal voltage is input to the temperature controller 10, and then the output signal voltage of the thermocouples 6 and 7 is The temperature regulator 10 controls the heater 3 of the heat insulating jacket so that the temperature of the heat insulating jacket 2 and the temperature of the sample 5 become zero (in other words, the temperature of the heat insulating jacket 2 and the temperature of the sample 5 are the same).

On the other hand, the output of either thermocouple 6 or 7 is also connected to a recorder 11, and the elapsed time of the temperature of the sample 5 is recorded.

Next, a spontaneous ignition test of the sample with the above configuration will be described.

First, when oxygen gas (or air) is passed through the sample 5 in the sample cell, the sample is oxidized and the temperature of the sample 5 itself rises slightly.

In this state, when the temperature of the heat insulating jacket 2 is made to follow the temperature of the sample 5, the sample 5 finally ignites.

Then, the progress of the temperature change of the sample 5 up to this ignition is recorded, and the spontaneous ignition characteristics of the sample 5 are measured based on the recorded results.

During this time, the constant temperature bath 1 is set and maintained at a constant temperature, and the test is repeated by changing this set temperature variously.

However, this conventional device has the following problems.

When the thermocouple 7 is connected to the recorder 11, a closed loop is formed between the internal resistance of the recorder 11 and the thermocouple 7, and a current due to thermoelectromotive force flows through the thermocouple 7.

Of course, this current itself is extremely small, but the signal from thermocouple 7 is also at an extremely low voltage level of several millivolts, and it was found that even a disturbance of this level can disrupt the overall temperature control (temperature control). As mentioned above, almost no voltage is applied to the input of the temperature regulator 10, so the influence of the input resistance of the temperature regulator 10 can be completely ignored.

The present invention attempts to provide a device that solves this problem, and its gist is that a resistor approximately equal to the input resistance of the recorder 11 is connected to the thermocouple 6 that is not connected to the recorder 11. The reason is that they are connected in parallel so that the surface thermocouple elements always operate in a balanced manner.

Next, the operation of the main parts of the present invention will be explained with reference to FIG. 2, which is a schematic diagram of the main parts.

In Figure 2, the same numbers as in Figure 1 are numbered.
21 is a resistor having the same resistance value as the input resistance of the recorder 11, 22 is a switch, and 5 is the same as that shown in the figure.
A-3o is a contact point of the switch.

First, when the switch 22 is in the direction shown in the figure, a closed loop is formed (thermocouple 6 - input resistance of recorder 11 (not shown), one terminal Sn, one terminal Sm - thermocouple 6), and at the same time the thermocouple 7 one terminal Sa one terminal sb - resistor 2
1 - A closed loop of thermocouple 7 is formed, and surface thermocouple 6,
A current flows through 7.

However, the input resistances of the resistor 21 and the recorder 11 are the same, so the currents flowing through the surface thermocouples 6 and 7 are equal.
The influence of this current on the surface thermocouples 6 and 7 will be exactly the same.

Also, when the switch 22 is turned in the opposite direction to that shown in the figure,
A closed loop of thermocouple 7, terminal So, terminal Sn, input resistance of recorder 11, and thermocouple 7 is formed, and at the same time, thermocouple 6, terminal SC, terminal sb, resistor 21, and thermocouple 6 are formed. In the same case, the currents flowing in the side thermocouples 6 and 7 are equal.

Therefore, no matter which thermocouple 6 or 7 the recorder 11 is connected to, the surface thermocouples 6 and 7 are always balanced (under the same conditions).
The temperature can be detected while the

Note that the recorder 11 is normally connected to a thermocouple for detecting the temperature of the sample 5, but since the temperature inside the insulating jacket 2 follows the temperature of the sample 5, the insulating jacket 2
Needless to say, it may be connected to a thermocouple for detecting the temperature of the sensor.

In addition, the present invention is not only a spontaneous ignition test device, but also a device that connects a pair of thermocouples differentially, records this output signal, and performs thermal analysis of the sample. Needless to say, it can also be used in cases where the thermocouple is connected and the signal from one of the thermocouples is used in some way.

As detailed above, the present invention solves the problem of unbalanced surface thermocouples due to the connection of recorders in spontaneous ignition test equipment, and obtains accurate spontaneous ignition characteristics of samples with a fairly simple configuration. be able to.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a conventional spontaneous ignition test device, and FIG. 2 is an explanatory diagram of main parts of a spontaneous ignition test device according to the present invention. 1... Constant temperature chamber, 2... Insulating jacket, 3... Heater, 4... Insulating member, 5... Sample, 6 ,7...Thermocouple,8
...Purge gas source, 9...Gas flow path,
10...Temperature controller, 11...Recorder, 1
2... Expander, 13... Temperature control unit, 14... Heater, 21... Resistor,
22...Switch.

Claims (1)

[Scope of utility model registration request] Temperature detection thermocouples are installed inside the jacket in the constant temperature oven and in the sample cell inside the jacket, and the differential outputs of these thermocouples are fed back to the temperature controller in the jacket to detect oxygen in the sample cell. In a system that measures the ignition characteristics of the sample by controlling the temperature inside the jacket to follow the rise in temperature of the sample as it is introduced, and recording the output of one thermocouple on a recorder, the other thermocouple that is not connected to the recorder To,
A spontaneous ignition test device characterized in that a resistor approximately equal to the input resistance of a recorder is connected in parallel, and the same thermocouple is always operated in a balanced manner.