JPS58147632A - Device for measuring concentration at inflammable limit - Google Patents

Abstract

PURPOSE:To measure the concentration efficiently even though the initial pressure in a reaction container, oxygen concentration, and the like are changed, by discharging the internal pressure by the explosion of fuel air mixture in the reaction container, and detecting the fact that the pressure in the container which is tightly closed immediately after the discharge becomes a steady state that is lower than the initial pressure. CONSTITUTION:When the explosion occurs in the reaction container 1 which contains the fuel air mixture to be measured, the pressure is discharged from a lid body 2. A first pressure detecting means P1 is provided in the container, and the signal is transmitted to a computer C. A container 3 regulates the operation starting pressure of the lid body 2. Automatic valves V1 and V2 provided on the container 1 are connected to the computer C through an air to electricity transducing means and perform the opening and closing operations. Branching pipes 7, 8 and 9 for introducing air, nitrogen, andn inflammable gas are connected to the part between the automatic valves V1 and V2 of a main pipe 5. A pressure detecting means P2 which is provided between the automatic valves V3 and V2, detects the pressure in the pipe and sends the detected pressure to the computer C through a cable.

Description

[Detailed description of the invention]

The present invention relates to an apparatus for automatically measuring the explosive limit concentration of flammable gas or vapor. Generally, in the petrochemical industry, organic synthetic chemical industry, etc.
Various flammable vapors, such as flammable gases such as hydrogen, ethylene, propane, butane, or vapors of organic solvents, are widely used under various conditions. Of the accidents that occur in industrial facilities that handle these flammable gases or flammable vapors (hereinafter referred to as flammable gases, etc.), the ones that have the most serious consequences and cause the greatest damage both to property and to people are: It was an explosion accident. The ignition explosion of combustible gas, etc., which has such a serious effect, is generally induced by external shocks to the explosive mixture, ignition, and other causes. Therefore, as a measure to prevent the above-mentioned explosion accidents, ■Do not create explosive mixtures. ■Do not create a cause that induces an explosive reaction. These two points are the most basic measures. When attempting to implement the above measure (2), it is necessary to confirm the explosive limit concentration of flammable gases, etc. through actual measurements. Conventionally, the devices for measuring such μ total limit concentration are: α) A device devised by the U.S. Bureau of Mines. (@ Kita-use type device. (3) Device that uses a pressure vessel that can withstand a pressure of about 10 times the initial pressure. Explosive limit concentration is determined by visually determining explosion of flammable gas, etc. and injury to hands at the following pressures.For (3) above, a pressure vessel is used to detect an increase in the internal pressure of the vessel due to an explosion. This method determines the explosive limit concentration by determining whether there is an explosion or a hand injury.Generally, when using the devices described in (1) and (2) above, the judgment of an explosion or a hand injury relies on the observer's visual observation. It takes an extremely large amount of time and a large number of people to conduct tests at various levels by selecting various gas types, pressures, or oxygen concentrations. In order to detect explosive phenomena, very expensive special equipment is required, such as a pressure detection element with an extremely fast response speed, an amplification device to amplify the signal detected by the element, and a recording device to record the high-speed signal obtained from this element. It is necessary to use a pressure vessel that requires a In addition, from a safety perspective, there was a difficult technical problem of having to deal with the violation of both of the generally contradictory characteristics.Furthermore, from a safety perspective, In order to ensure safety, large-scale auxiliary equipment such as strong retaining walls was also required. It is possible to measure the explosive limit concentration with extremely high efficiency even when various conditions such as initial pressure in the container (including cases above and below atmospheric pressure), % oxygen concentration, and temperature are changed if necessary. The present invention will be clarified by describing the embodiments of the present invention in detail with reference to the drawings below. Fig. 1 is a system diagram of the device showing one embodiment of the present invention device. In FIG. 0, C is, for example, a control microcomputer system (hereinafter referred to as computer) that is known per se, and includes a CPUC1, a CRT terminal C, a storage device kC3, a printer C1, an input/output interface Cs, a terminal rack C0, and・It consists of a bus etc. that interconnects these. 1 is a reaction container that stores the mixture to be measured. As this reaction container 1, for example, a cylindrical container with an inner diameter of about 60 u and a height of about 150 fins is used. Can be applied. A pressure release means is provided at the upper opening of the reaction vessel 1 to release the internal pressure that instantly increases due to the explosion to the outside of the vessel when an explosion phenomenon occurs in the reaction vessel 1, and immediately seal the reaction vessel 1 again. The lid 2 is placed on the upper opening of the reaction container 1. When the reaction container 1 has the shape and dimensions as described above, the lid 2 has a diameter of about 90 mm,
A lid having an O ring (not shown) added to a disc having a thickness of about 10 mm can be applied. The reaction vessel 1 is provided with a first pressure detection means PX which detects the pressure inside the vessel and transmits a detection signal corresponding to the detected pressure to the computer C through the cake p. As the first pressure detection means, a known pressure transducer (for example,
Toyoda Machinery Semiconductor Strain Gauge Pressure Transducer PMS-5 type) t! :Can be applied. The upper part of the reaction vessel 1 includes the lid cover to cover the upper opening of the reaction vessel 1,
A container 3 is provided which constitutes a pressure equalizing means for regulating the activation start pressure of the lid as the pressure releasing means by its internal pressure. This container 3 is joined to the upper part of the reaction container 1 by a screw or the like so that the lid 2 can be used as the base. A side pipe 4 is connected to the container 3, and this side pipe has an automatic valve (hereinafter referred to as the third automatic valve) operated by the output of the electro-pneumatic conversion means based on the control signal from the computer C. are inserted, and these constitute the above-mentioned pressure equalization means. The reaction vessel 1 is connected to one end of a main pipe 5 in which a first automatic valve v8 and a second automatic valve v8 are respectively inserted in order of proximity to the reaction vessel 1. The other end of the main pipe 5 is connected to a vacuum pump 6. The first automatic valve v2 and the second automatic valve V are both connected to the computer C by a cable via electro-pneumatic conversion means, and are configured to open and close based on control signals from the computer C, respectively. There is. The main pipe 5
At a position between the first automatic valve v1 and the second automatic valve 73, a branch pipe 7 for introducing air into the main pipe 5, a branch pipe 8 for introducing nitrogen, flammable gas, etc. are introduced. Branch pipes 9 are connected to each of them. Each of these branch pipes 7, 8.9 is inserted into a pipe line connected to the main pipe 5 to form a control valve (in this example, a solenoid valve) Vy. V, #vI are provided. Each solenoid valve V,, V・
, v9 are all connected to the computer C by a cape μ, and are operated based on control signals from the computer C, respectively. In addition, each of the above-mentioned branch pipes 7,
8.9 are provided corresponding to each component of the air-fuel mixture to be measured by the device of the present invention, and when the device is applied to more types of components, the components Of course, it is sufficient to have a structure having branch pipes corresponding to the number of pipes. The pressure inside the pipe between the first automatic valve v1 of the main pipe 5 or the third automatic valve V of the side pipe 4 and the second automatic valve v8 is detected, and the detected pressure is sent to the computer C through the cape μ. A second pressure detection means P for transmitting the pressure is provided. As this second pressure detection means, a known pressure transducer (for example, the diffusion type semiconductor pressure transducer FD1 manufactured by Toyoda Koki Co., Ltd.
-IF type) can be applied to 04. Stirring means I having a stirring plate that moves up and down in the reaction container and an electromagnetic drive means to stir the mixture in the reaction container I.
O is provided. This stirring means 10 is connected to a computer C through a cable 14/, and is configured to create the mixture based on control signals from the computer C. An ignition means 11 having a neon transformer and a discharge electrode having a diameter of about 3M connected to the neon transformer is provided such that the discharge electrode is located within the reaction vessel I. This ignition means 11 is connected to a computer C through a cape μ, and is controlled by control signals from the computer C. The apparatus of the present invention having the above-mentioned configuration is capable of instantly releasing the internal pressure that rises instantaneously due to the explosion of the air-fuel mixture in the reaction vessel 1 to the outside of the reaction vessel by temporarily jumping the lid 2, which is a pressure release means. Pressure Pω inside the reaction vessel that was released and immediately sealed
One of the features is that the first pressure detection means Pi detects that the pressure is at a steady value that is lower than the initial pressure (pressure before explosion), thereby confirming that an explosion has occurred. be. In other words, the explosion is not an instantaneous phenomenon of pressure rise;
The pressure drop (or the pressure after the pressure drop), which is a steady phenomenon, is detected by the first pressure detection means P8. Under various conditions,
A series of operations including introducing the mixture to be measured into the reaction vessel L, igniting it, determining the presence or absence of an explosion, and recording and displaying the results are all based on control signals from the computer C. Another feature of the device of the invention is that it is completely automatic. Therefore, the device of the present invention can essentially be used in a wide variety of ways, and therefore the effects and effects of the method can be selected from a wide variety of ways. - An example will be explained according to the flowcharts in FIGS. 2 to 4. FIG. 2 shows the pressure P(

The operations (operations) will be explained in accordance with the numbers attached to the left side of this two-way chart. Start pump α) vacuum ° 6 (manually). After this, the operation of the vacuum pump 6 is continued. (To) From the CRT terminal C2 of the computer C, the test date, temperature T%, initial pressure P in the reaction vessel, , the number n of components of the mixture to be measured, the names of the same components, the mixture ratio at the start of the test of flammable gases, etc., the minimum change range when changing the mixture ratio of flammable gases, etc. (N, ,)
Determine the range of change (N1) when changing the mixture ratio of inert gas in stages, the range of decrease in the internal pressure of the reaction vessel from the initial pressure (N1) to determine whether the mixture will explode or cause injury to the hand, and the end of the experiment. Input the number of consecutive hand injuries (Ns) (N, if no explosion occurs consecutively, the experiment is terminated as the explosion limit concentration to be determined has been found), etc. (3) The first and second automatic valves V, . At this stage, the second pressure detection means P detects the pressure within the main pipe 5, and therefore the pressure within the reaction vessel 1. (4) The computer C takes in the output signal of the second pressure detection means P1, and the inside of the reaction vessel l becomes a vacuum (10""1WH
1 or less, the same applies hereinafter). The current stage is maintained until it is confirmed that the inside of the reaction vessel 1 is evacuated. (6) The first automatic valve v1 is closed by a control signal from the computer C. Therefore, at this stage, the interior of the reaction vessel 1 is maintained in a vacuum state. (6) The third automatic valve opens according to the control signal from the computer C, so the vacuum pump 6 and the side pipe 4 open.
The gas inside the container 3 is discharged through the main pipe 5. At this stage, the second pressure detection means P□ detects the pressure inside the main pipe, and therefore the pressure inside the container 3. (7) The computer C takes in the output signal of the second pressure detection means P, and executes an operation to determine whether or not the inside of the container 3 is evacuated. The current stage is maintained until it is confirmed that the container 3 is evacuated. At the end of step (4) and step (7) above, the reaction volume? The pressure inside the rgl and the inside of the container 3 are equal (both are in a vacuum state), so the upper and lower portions of the lid serving as a pressure release means are in an equal pressure state. (8) The second automatic valve v8 is closed by the control signal from the computer C. (91 Solenoid valve V by the control signal from computer C,
opens. Branch pipe 8 → Solenoid valve V, → Main pipe 5 → Side pipe 4 → 3rd
Nitrogen is introduced into the container 3 through the automatic valve V, →container 3. (10) The computer C takes in the output signal of the second pressure detection means P (which detects the pressure inside the container 3 at this stage), and when the pressure of nitrogen inside the container 3 is detected at the αth stage, the computer Initial pressure set at C (reaction vessel l just before ignition)
The operation for determining whether the pressure of the air-fuel mixture within the fuel tank has been reached is performed. The current stage is maintained until it is confirmed that the pressure of nitrogen in the container 3 has reached the initial pressure. (The third automatic valve vs and the solenoid valve V are closed by the control signal from the 111 computer C. This is to prevent an explosion within the container 3 and ensure safety in the event that flammable gas or the like leaks into the container 3. Second
The automatic valve ■l z v opens. Therefore, the nitrogen remaining in the side pipe 4 and the main pipe 5 up to the 1'iJ stage is discharged by the vacuum pump 6. The αj computer C takes in the output signal of the second pressure detection means P8 (at this stage, it detects the pressure in the side pipe 4 and the main pipe 5, and therefore the pressure in the reaction vessel 1), and the inside of the reaction vessel 1 is detected. Execute X-specific operation to determine whether vacuum format has been reached. The limit stage is maintained until a vacuum is confirmed. (I4) The second automatic valve V is closed by the control signal from the computer C. Qc9: The solenoid valve ■ is closed by the control signal from the computer C.
, opens. Flammable gas, etc. (for example, water volume) flows into the reaction vessel l through the route of branch pipe 9 → ゛r magnetic valve V, → main pipe 5 → first automatic valve V8 → reaction vessel 1.
be introduced within. The Oυ computer C takes in the output signal of the second pressure detection means P (which detects the pressure of the flammable gas, etc. in the reaction vessel 1 at this stage), and detects the pressure of the combustible gas, etc.
In step 2), an operation is performed to determine whether the pressure (partial pressure) corresponding to the mixture ratio of combustible gas, etc. set in the computer C has been reached. The current stage is maintained until the pressure of the combustible gas reaches the above (partial pressure). (The first automatic valve v1 and the solenoid valve V are closed by the control signal from Iη computer C. The second automatic valve V is opened by the control signal from Ql computer C. Therefore, by the previous stage, the main piping The combustible gas etc. remaining in the main pipe 5 is discharged by the vacuum pump 6. αa computer C detects the pressure of the combustible gas etc. (detecting)) and performs an operation to determine whether or not the inside of the main piping has become a vacuum.The current stage is maintained until it is confirmed that a vacuum has been created.Kan Computer C The second automatic valve V
, closes. H computer C determines whether the mixture to be measured is set as a 3-component mixture or a 2-component mixture based on the data input in the above-mentioned odor stage, and then Determine the operation of the stage. If it is set as the three components above, move to the next first stage, and if it is set as two components, jump to the first stage described below. From Computer C (Foundation) Solenoid valve V,
opens. Therefore, nitrogen as an inert gas (one component of the mixture to be measured) is introduced into the main pipe 5 through the branch pipe 8 and the solenoid valve V$. Captures the output signal of [detecting pressure]. An operation is performed to determine whether the pressure of nitrogen has become lower than the pressure of the combustible gas or the like already introduced into the reaction vessel l. The current stage is maintained until it is confirmed that the pressure of nitrogen introduced into the main pipe 5 is higher than the pressure of the flammable gas, etc. in the reaction vessel 1. The first automatic valve is activated by the control signal from the En computer C.
, opens. At this stage, the pressure of nitrogen in the main pipe s is greater than the pressure of the flammable gas, etc. in the reaction vessel 1, so nitrogen flows unilaterally into the reaction vessel 1 and reverse flow is prevented. Our computer C takes in the output signal of the second pressure detection means P (which detects the pressure of the mixture in the reaction vessel 1 at this stage), and detects the pressure of the mixture in the reaction vessel 1. A determination operation is performed to determine whether or not the internal pressure has reached the pressure (sum of each component) corresponding to the sum of the mixing ratios of combustible gas, etc. and inert gas set in step Q). The current stage is maintained until it is confirmed that the pressure within the reaction vessel 1 has reached the above (sum of each partial pressure). The first automatic valve v is activated by the control signal from the computer C.
1 and the solenoid valve V port are closed. A control signal from computer C opens the second automatic valve vI. Therefore, the nitrogen remaining in the main pipe 5 up to the previous stage is discharged by the vacuum pump 6. @Computer C is the second pressure detection means P (at this stage, it is detecting the pressure of nitrogen remaining in the main pipe 5)
The output signal is taken in and an operation is performed to determine whether or not the inside of the main piping has become a vacuum. The current stage is maintained until it is confirmed that a vacuum has been created. The second automatic valve V is activated by the control signal from the computer C.
8 closes. - Solenoid valve V is opened by a control signal from computer C. Therefore, air (one component of the mixture to be measured) is introduced into the main pipe 5 through the first branch pipe 7 and the solenoid valve (2). 131) Computer C is the second pressure detection means P! (At this stage, the pressure of the air injected into the main pipe 5 is being detected.) A determination operation is performed to determine whether or not the pressure has exceeded the pressure of the mixture (mixture of reactive gas, etc. and inert gas). The current stage is maintained until it is confirmed that the pressure of the air introduced into the main pipe 5 is equal to or higher than the pressure of the gas in the reaction vessel 1. The first automatic valve v1 opens in response to a control signal from computer C. At this stage, the pressure of the air in the main pipe 5 is greater than the pressure of the gas in the reaction vessel 1, so air flows unilaterally into the reaction vessel 1, and backflow is prevented. The computer C takes in the output signal of the second pressure detection means P (which is detecting the pressure of the mixture in the reaction vessel l at this stage), and the pressure of the mixture in the reaction vessel l is determined by the pressure of the mixture in the reaction vessel l. In step (3), an operation is performed to determine whether the test pressure (initial pressure 1) set in computer C has been reached.The current stage is maintained until the pressure of the mixture in reaction vessel 1 reaches the initial pressure. The first automatic valve V and the solenoid valve V are closed by a control signal from the computer C. At this stage, the pressure of the mixture in the reaction volume 91 and the nitrogen pressure in the container 3 are equal to each other. The initial pressure is reached, and the pressure is balanced between the upper and lower parts of the lid body 2, which serves as a pressure release means. - The second automatic valve V is activated by a control signal from the computer C.
, opens. Therefore, the air remaining in the main pipe 5 until the previous stage is discharged by the vacuum pump 6. - Computer C is the second pressure detection means Pa (at this stage, it is detecting the pressure of the air remaining in the main pipe 5)
The main pipe 5 receives the output signal and executes an operation to determine whether or not the inside of the main pipe 5 has become a vacuum. The current stage is maintained until it is confirmed that the inside of the main pipe 5 is evacuated. The second automatic valve V is closed by a control signal from the Gη computer C. (c) Solenoid valve V according to the control signal from computer C,
opens. Therefore, nitrogen is introduced into the main pipe 5 through the branch control pipe 8 and the valve V. - The computer C takes in the output signal of the second pressure detection means PI (at this stage it detects the pressure of the nitrogen introduced into the main pipe 5) and executes it. The current stage is maintained until it is recognized that the pressure of nitrogen in the main pipe 5 has reached the initial pressure. Then, the solenoid valve V is closed by a control signal from the computer C. The operation in stages 1 to - is such that in the unlikely event that flammable gas leaks into the main pipe 5 due to a defect in the solenoid valve ①, a reaction occurs due to a defect in the first automatic valve v1 in this situation. This is to ensure safety even in the event that backfire from an explosion within the container 1 attempts to reach the main pipe 5. (4η The stirring means 1 is controlled by the control signal from the computer C.
o is activated and the air-fuel mixture in one reaction vessel l is stirred and made uniform. (6) Ignition means 1 by control signals from computers C and P
1 is activated, and the discharge electrode provided in the reaction vessel 1 performs an ignition operation. When the air-fuel mixture explodes due to the ignition operation, the pressure within one reaction vessel 1 rises instantaneously. The lid body 2 makes a temporary jumping movement, and the gas in the reaction vessel 1 is ejected into the vessel 3. Immediately after this, the lid body 2 closes and seals the reaction vessel 1 again by its own weight. If no explosion occurs due to the ignition action, no particular change occurs. □□□ Computer C takes in the output signal of the first pressure detection means P□ (detecting the pressure P (t) in the reaction vessel l). (Foundation) Computer C stores the data regarding the pressure inside the reaction vessel l, which was taken in at step i4, in a predetermined location of its storage device, and also controls the operation of the entire apparatus at step (3). to be restored. Of the operations of the apparatus of the present invention explained in accordance with the flowchart in FIG. Each time this series of operations is executed, the pressure P(υ) in the reaction vessel 1 after the ignition means 11 is activated is measured, imported into the computer CiC, and stored (in step (c) above). )) The device of the present invention is for determining the explosion limit concentration, that is, the lower limit value and the lower limit value of the concentration (volume %) of a combustible gas in which an explosion can occur.Therefore, each time the pressure Pω is measured, 1. Compare the initial pressure in the reaction vessel 1 with the initial pressure, and if the range of pressure change exceeds a predetermined value (i.e., the above-mentioned number (N, set in the odor stage)), it is determined that an explosion has occurred; In this case, it is determined that no explosion has occurred, and this determination operation is repeated while varying the concentration of flammable gas, etc., and the explosion limit concentration is determined as the convergence point of these operations.This determination operation is executed. In this case, the combustible gas etc. can be changed using various known methods (for example, the 1/2 division method (shown in Figure 3),
This can be done efficiently by making full use of direct search methods such as the golden section method, but an example of this is shown in the flowchart in Figure 3. By operating this device according to the flowchart in Figure 3. The obtained data and judgment results are shown in Table 1 below. [9 whites below] [Table 1] The values of the lower limit concentration (44 Vo1%) and upper @ boundary concentration (7δ5 VOI%) shown in Table 1 above are the literature values (lower limit concentration 40 Vo1%) using a conventional device. , lower limit concentration 7K
It can be confirmed that the results are in good agreement with OVo1%). Figure 4 shows the broach yard for obtaining the critical curve (so-called right-angled triangular diagram) 1 showing the explosive limit concentration' when the air-fuel mixture has three components: hydrogen, air, and nitrogen.
The results obtained by operating this apparatus according to the flowchart are shown in Table 2 and FIG. 5 (right triangular diagram) below. [Table 2] All of the measurement results by the apparatus of the present invention described above are output on recording paper by the printer C1 of the computer C. Therefore, according to the device of the present invention, the explosive limit concentration measurement is carried out completely automatically, which significantly improves the measurement efficiency.For example, according to the results of the experiments conducted by the inventors, it conventionally took approximately one week for measurement. It has been confirmed that measurements up to the determination of the explosion limit curve (so-called trigonogram) can be completed in about 24 hours. In addition, the measurement conditions can be easily changed, and furthermore, the device of the present invention determines whether an explosion has occurred based on the steady state inside the reaction vessel 1 after the pressure release means (lid 2) is activated, rather than the transient pressure increase. This is done by measuring the pressure of
As the pressure detection means (first pressure detection means P) for making this determination, an inexpensive and robust ordinary pressure detection element can be used. The pressure resistance characteristics required for the reaction vessel 1 only need to be able to withstand the initial pressure plus the internal pressure that rises until the pressure dissolving means is activated, and unlike conventional pressure, it can withstand a pressure increase of about 10 times the initial pressure. There is no need to use a pressure vessel that can withstand it, which simplifies the device as a whole. Furthermore, the pressure release means itself serves as a safety device, and sufficient safety can be ensured without the need for special installation of large-scale incidental equipment such as a solid retaining wall as in the past. Furthermore, since the measurement is completely automated, there is no need for the person performing the measurement to be stationed near the device during the experiment, and in this sense, the person performing the measurement is essentially free from danger. The apparatus of the present invention described above has a configuration in which a temperature detection means Tx inside the reaction vessel is added as shown by the dashed line in FIG. 1, and the output signal thereof is transmitted to the computer C. In this case, by adding a heating means (not shown) such as an electric heater to the main pipe 5, the temperature of the mixture in the reaction vessel 1 of the computer C can be adjusted. In this case, it is possible to particularly confirm the temperature dependence of the explosive limit concentration.

[Brief explanation of the drawing]

Claims (1)

[Claims] A reaction vessel containing a mixture to be measured, when the pressure inside the reaction vessel rises above a certain value, the gas in the reaction vessel is instantly released to the outside, and the reaction vessel is opened again. a pressure release means for sealing; a control computer; a first pressure detection means for detecting the pressure within the reaction vessel and transmitting a signal corresponding to the detected pressure to the computer; a pressure equalizing means for regulating the activation start pressure of the pressure release means; a main pipe connected to the reaction vessel at one end and a vacuum pump at the other end; a position relatively close to the connection point of the main pipe to the reaction vessel; a first automatic valve and a second automatic valve arranged at relatively distant positions and operated based on control signals from the computer, each corresponding to each component of the air-fuel mixture to be measured; branch pipes each connected to a position between the first and second automatic valves of the main pipe, each of the branch pipes being inserted into a pipe line connected to the main pipe, and the computer Each control valve is arranged to detect the pressure between the first and second automatic valves in the main piping, and the computer outputs a signal corresponding to the detected pressure. 1. An explosive limit concentration measuring device comprising: second pressure detection means for transmitting data to the computer; and ignition means for igniting in the reaction vessel, the ignition means being activated based on a control signal from the computer. (2) The explosive limit concentration measuring device according to claim 1, wherein the pressure release means is a shell capable of closing and sealing the opening of the reaction vessel by its own weight. (3) The explosive limit concentration measuring device according to claim 1, wherein the reaction vessel has a stirring means operated based on a control signal from the computer.