JPS6355657B2 - - Google Patents

Description

[Detailed description of the invention] With the rapid development and expansion of the petrochemical industry and organic synthetic chemical industry in recent years, hydrogen, ethylene, propane,
Various flammable gases such as butane or organic solvent vapors and dusts are used in a wide range of low and high pressure areas, and the most common accidents occur in industrial facilities that handle these flammable gases and dusts. It goes without saying that explosions are accidents that cause serious consequences and cause great damage both to property and to people.

The ignition and explosion of flammable gas and dust, which has such a serious impact, is generally induced by external shocks to explosive mixtures, ignition, etc. Measures to prevent this can be summarized in two points: (1) not to create an explosive mixture, and (2) not to create a cause that would induce an explosive reaction.

The present invention, as one of the accident prevention measures mentioned above,
In particular, this method focuses on preventing the creation of explosive mixtures as described in (1) above, and is a means of explosion/non-flammability (no explosion) when measuring the explosive limit concentration of various flammable gases and dust. The present invention relates to a detection method and device for detecting the limits of (the same).

Conventionally, practical methods for measuring the explosive limit concentration for flammable gases include: (1) a method using an explosive tube devised by the U.S. Bureau of Mines;

(2) Kitagawa method.

For combustible dust, (3) the Hartmann method devised by the U.S. Bureau of Mines.

(4) A natural fall method used by the Mine Safety Institute and others in the UK.

Commonly used methods include: (5) A method using a pressure vessel that can withstand a pressure approximately 10 times the initial pressure.

Among these, (1) to (4) visually determine whether an explosive mixture is explosive or nonflammable at atmospheric pressure or lower pressure, and (5) uses a pressure-resistant container. Explosions can be detected by detecting the rising pressure after an explosion.
This is to determine nonflammability.

By the way, since the former method relies on human visual inspection to determine whether it is explosive or non-combustible, it requires a large amount of time when testing is performed under several conditions, such as varying the type of gas or dust, pressure conditions, and oxygen concentration. It required a number of people.

On the other hand, in the latter method, because it is necessary to grasp the explosion phenomenon that occurs instantaneously, a pressure detection element with a fast response speed and an amplification device to amplify the signal captured by the element are required, and the high-speed signal generated from the pressure detection element is required. Very expensive special equipment such as high speed storage or recording equipment was required to record. Furthermore, as a matter of course, explosive containers must withstand an instantaneous pressure rise of about 10 times the initial pressure, it was necessary to use an ultra-pressure resistant container for testing at high pressures. The pressure sensing element used was also subject to conflicting technical constraints of sensitivity and pressure resistance. Furthermore, large-scale auxiliary equipment such as a solid retaining wall was required to ensure the safety of those involved in the test in the event of an emergency.

The present invention focuses on the conventional method of detecting the limit of explosion and non-flammability when measuring the explosive limit concentration as described above, and aims to overcome the actual situation and solve the drawbacks, and detect explosion and non-flammability at a very low cost. The purpose of the present invention is to provide an innovative detection method and device that enables automation.

That is, the main object of the present invention is to provide a detection method that allows easy measurement of the initial pressure in a reactor not only under atmospheric pressure but also under increased pressure and reduced pressure.

In addition, the present invention can use a slow-response, inexpensive, and durable pressure detection element that is widely available in the world, and can meet the limits of explosion and nonflammability with simple equipment without requiring expensive equipment. Another important objective is to provide a practical detection means that can perform detection reliably.

Furthermore, the present invention is not damaged by an instantaneous pressure increase during an explosion, and is equipped with a pressure detection element that can detect the reduced pressure generated in the reaction vessel after the pressure release device opens and closes, making it possible to automate the device. It is another object to provide a novel detection device that is both safe and secure.

Therefore, the detection method of the present invention, which meets the above-mentioned objectives, detects the explosion by releasing the increased pressure caused by the explosion into the external space and then detecting the reduced pressure generated within the reaction vessel. The detection device is characterized in that it detects a phenomenon, and the detection device is constructed by assembling a reaction vessel with a pressure release means, a pressure detection means, a stirring means, and an ignition means, respectively.

Hereinafter, specific aspects of the present invention will be described in further detail in sequence based on embodiments shown in the accompanying drawings.

FIG. 1 is a schematic cross-sectional view showing one example of the apparatus used in the detection method of the present invention, in which a reaction vessel 1 with an inner diameter of approximately 60 mm and a height of approximately 150 mm that accommodates the explosive mixture to be measured; When an explosion phenomenon occurs in the reaction vessel 1, it opens instantaneously due to the pressure increase due to the explosion, and after the pressure is released to the outside of the vessel, it closes under its own weight, and thereafter maintains an airtight state, with a diameter of approximately 86 mm, A pressure release device 2 consisting of a combination of a flat lid with a thickness of about 10 mm and an O-ring, and the reaction vessel 1
The main component is a pressure detection element 3, which is attached to the reactor and is not damaged by the instantaneous pressure increase during an explosion, and which measures the reduced pressure generated in the reaction vessel 1 after the pressure release device 2 is closed. Furthermore, as an attached device, there is an electromagnetic vertical stirring type stirrer 5 that homogenizes the explosive mixture, an electric ignition device 4 for the explosive mixture consisting of a combination of a neon transformer and a discharge electrode with a diameter of about 3 mm, and a pressure release device. The main part consists of a stopper 6 that prevents the device 2 from falling off.

In the illustrated example, the reaction vessel 1 is connected to piping at its bottom end via a pot 7, and is connected to the atmosphere side via a pot 10 and a vacuum pump 11. A mercury manometer 12 for confirming and detecting the presence of flammable gas such as acetone vapor between the air tank 7 and the air tank 10, and a air tank 8 communicating with the atmosphere.
In addition, sample bottles 13 for supplying flammable gas such as acetone vapor are branched off from each other via a container 9.

Here, each of the above-mentioned element members can be of a known structure, and by combining them to suit the above-mentioned purpose, a series of devices is constructed.

Next, details of a method for measuring the explosive limit concentration of combustible gas, etc. using the above-mentioned apparatus will be explained using an example under atmospheric pressure conditions using an acetone-air mixture.

First, in the apparatus shown in FIG. 1, after starting the vacuum pump 11, the chambers 7 and 10 are opened to evacuate the reaction vessel 1. At this time, the vacuum state is checked using a mercury manometer 12. When the reaction vessel 1 is evacuated, the pot 10 is closed, and then the pot 9 is opened and a certain amount of acetone vapor is released from the sample bottle 13 while checking the reaction vessel 1 with the mercury manometer 12.
Put it in. Once a certain amount of acetone vapor has been added, the pots 7 and 9 are closed.

Next, open pot 10 and remove the acetone vapor from pot 7. At this time, confirmation that the acetone vapor has been removed is performed using a mercury manometer 12.
After the acetone vapor is removed, the pot 10 is closed, and the pot 8 is then opened to introduce air to the pot 7.

In this state, the pot 7 is opened and air is introduced into the reaction vessel 1 to atmospheric pressure, and when the air reaches atmospheric pressure, the pots 7 and 8 are closed.

After completing the above operations, the stirrer 5
to make the explosive mixture in the reaction vessel 1 uniform. Then, when the explosive mixture in the reaction vessel 1 becomes uniform, electric ignition is performed by the electric ignition device 4.
At this time, if the concentration of the explosive mixture falls within the explosive range, an explosion will occur and the pressure within the reaction vessel 1 will rise. If the pressure rises above a certain value, the pressure release device 2 opens and the internal pressure is released, but once the internal pressure is released, the pressure release device 2 closes and the pressure inside the reaction vessel decreases.

In this way, the internal pressure of the reaction vessel is maintained in this state, and a decrease in this pressure is detected by the pressure detection element 3 to determine an explosion state.

In this case, it goes without saying that the internal pressure will not change unless an explosion occurs.

The results detected in this way are shown in the diagram of FIG. In the chart, the vertical axis shows pressure, and the horizontal axis shows time. Also, this figure 2 shows an acetone concentration of 6 vol.
This is a case where an explosion occurs using a mixture of % and
is the initial pressure, and Y is the pressure inside the reaction vessel 1 after the explosion occurs.

The situation of pressure changes inside the reaction vessel 1 was measured using a semiconductor strain gauge type pressure transducer (Toyoda Machinery Co., Ltd. PMS-
5 type), an amplifier (AA-3004 type manufactured by Toyoda Machinery Works), an oscilloscope (V-121B type manufactured by Hitachi), and a recorder (type 3057 manufactured by Yokogawa).

From the above results, it was confirmed that explosion/nonflammability can be determined safely and reliably by the above method.

FIG. 3 shows an example of an apparatus, which is a modification of the apparatus shown in FIG. 1, for carrying out the method of the present invention on flammable gas under pressurized or reduced pressure.

In the figure, 1 is a reaction vessel, 2 is a pressure release device, 3 is a pressure detection device, 4 is an electric ignition device, and 5 is a stirring device. These devices are compared to those in FIG. 1 above, and the same parts are given the same symbols. Also shown is a chamber 6' over the pressure relief device 2 for pressure balancing with the reactor pressure.

In the device of this embodiment, when the increased pressure caused by the explosion in the reaction vessel 1 is released, the lid body constituting the pressure release device 2 absorbs the impact exerted on the lid portion of the chamber 6'. A spring is housed in the chamber 6' to ensure that the pressure relief device 2 returns to its pre-release condition after pressure relief. Note that this chamber 6' is a sealable chamber and is connected to the pressure detection device 14.

Next, I will explain the measurement method using this device.
Reaction vessel 1 as described above, illustrated by way of example under atmospheric pressure conditions using an acetone-air mixture
Before the operation of creating a mixture in the reaction vessel 1, the pressure inside the chamber 6' for pressure balancing with the pressure inside the reaction vessel is set to the initial pressure inside the reaction vessel, and under this condition, a mixture is created in the reaction vessel 1 and measurements are performed. . In this case, the operation for creating a mixture in the reaction vessel 1 and the method for determining the explosion state are the same as those described above.

Further, FIG. 4 of the accompanying drawings shows one example of an apparatus for implementing the present invention on combustible dust as a modification of each of the above-mentioned examples.

In this figure as well, 1 is a reaction vessel, 2 is a pressure release device, 3 is a pressure detection device, 4 is an electric ignition device,
Reference numeral 6' denotes a pressure detection device, and a chamber 14 for balancing pressure with the internal pressure of the reaction vessel is indicated by the same reference numerals as in each of the above examples, but a dust sample diffusion plate 15 is further provided at the bottom of the reaction vessel 1. This is connected to an air tank 17 via a solenoid valve 16 for feeding air into the reaction vessel.

Although this device is similar to the above-mentioned devices in that there is no particular difference in the basic aspect of measurement, the details of the measurement method using this device will be explained below.

That is, first, a solenoid valve 16 is passed through the chamber 6' into the reaction vessel 1 for pressure balancing with the internal pressure of the reaction vessel.
The pressure is set to balance with the pressure inside the reaction vessel 1 when a certain amount of air is blown from the air tank 17. Next, a certain amount of air is blown into the reaction vessel 1 through the solenoid valve 16 from the air tank 17 to disperse the dust sample within the reaction vessel 1 . Then, the dust sample dispersed in this manner is electrically ignited by the electric ignition device 4 to determine the explosive state. The method for determining the explosion state in this case is the same as described above.

As explained above, the present invention provides a method for detecting an explosion phenomenon by detecting a reduced pressure generated within a reaction vessel after the increased pressure generated by the explosion is released to an external space, and a method for implementing the method. The apparatus has the following various effects depending on each of the above methods and the configuration of the apparatus. That is, (1) Since the detection method of the present invention detects a reduced pressure as described above, the initial pressure inside the reaction vessel can be reliably measured not only under atmospheric pressure but also under increased pressure and reduced pressure.

(2) The reaction vessel used in the present invention has a pressure release device that can be closed and sealed using its own weight or the restoring force or repulsive force of a spring, and the Kitagawa type, which has been used in the past, can be easily measured by making improvements. .

(3) The pressure detection element used in the present invention must not be damaged by the instantaneous pressure increase during an explosion, and must be able to detect the reduced pressure that occurs in the reaction vessel after the pressure release device opens and closes. It is sufficient to have any structure as long as it can detect the pressure, and therefore, it is possible to use pressure detection elements that are widely available in the world and have a slow response, are inexpensive, and are durable.

(4) Detection of the limit between explosion and non-flammability is easy and reliable, and the device can be automated.

(5) The pressure resistance of the explosion container can be simplified compared to the conventional method because the initial pressure (test starting pressure) plus the internal pressure that rises until the pressure release device is activated is sufficient.

(6) The pressure release device itself plays the role of a safety device, and can handle explosive phenomena from low pressure ranges below atmospheric pressure to high pressure ranges of several tens of atmospheres without the need for ultra-pressure containers or large-scale incidental equipment. , which can be detected safely and reliably, is an industrial breakthrough.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing an example of a device for detecting the explosion phenomenon of combustible gas under atmospheric pressure. Figure 3 shows the first system for detecting an explosion phenomenon under pressure or reduced pressure of combustible gas.
FIG. 4 is a schematic view of another implementation device different from the one shown in the figure, and FIG. 4 is a schematic diagram showing still another implementation device for detecting an explosion phenomenon of combustible dust. 1...Reaction vessel, 2...Pressure release device, 3...
Pressure detection device, 4... Electric ignition device, 5... Stirring device, 6'... Chamber for achieving pressure equilibrium with the pressure inside the reaction vessel, 14... Pressure detection device.

Claims (1)

[Claims] 1. Under a predetermined pressure, an explosive mixture contained in a reaction vessel is caused to explode, and when the increased pressure caused by the explosion rises above a certain value, it is released to an external space. Detecting an explosion phenomenon of combustible gas and dust, characterized in that after reducing the pressure inside the reaction vessel by reducing the pressure inside the reaction vessel, the explosion phenomenon is detected by detecting this reduced pressure inside the reaction vessel with a pressure detection element. how to. 2. The method for detecting an explosion phenomenon of flammable gas and dust according to claim 1, wherein the initial pressure in the reaction vessel is atmospheric pressure. 3. The method for detecting an explosion phenomenon of flammable gas and dust according to claim 1, wherein the initial pressure in the reaction container is pressurized pressure. 4. The method for detecting an explosion phenomenon of flammable gas and dust according to claim 1, wherein the initial pressure in the reaction vessel is a reduced pressure. 5 A pressure release device that releases the internal pressure in the reaction vessel when the internal pressure of the reaction vessel rises above a certain pressure, a pressure detection device that detects the reduced pressure in the reaction vessel after the pressure release device is activated, and a pressure detection device that detects the air-fuel mixture in the reaction vessel. 1. A device for detecting explosion phenomena of flammable gas and dust, comprising a stirring device for homogenizing the mixture and a device for igniting an explosive mixture. 6. The device for detecting explosion phenomena of flammable gas and dust according to claim 5, wherein the pressure release device is a lid of a reaction vessel that can be closed and sealed by its own weight. 7. The device for detecting an explosion phenomenon of flammable gas and dust according to claim 5, which is a lid of a reaction vessel that can be closed and sealed by the restoring force and repulsive force of a spring to which a pressure release device is attached. 8. The device for detecting explosion phenomena of flammable gas and dust according to claim 5, wherein the reaction vessel is equipped with a device for balancing the external space pressure and the initial pressure inside the reaction vessel.