JPH0732559U - Combustible gas detector Gas sensor Poisoning prevention filter - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention protects a gas sensor that detects a leak of flammable gas from being poisoned by SO ₂ gas, and
Eliminates false alarms, extends gas sensor life, and eliminates the need for replacement. An outer wall of the filter case, which comprises a holding frame formed in a main body, a filter cap having a set screw at the center for detachably mounting a filter, and a filter case forming a cylindrical outer wall screwed to the filter cap. A horizontal hole is provided inside, and an inner wire net and an outer wire net are attached to the horizontal hole, and NaCO ₂ as an SO ₂ gas remover is placed between both wire nets.
It is formed by encapsulating a porous carrier that supports the above, and a plurality of openings for ventilation and for checking the operation of the filter are provided on the cylindrical outer wall.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

The present invention protects a gas sensor of a flammable gas detector, which is installed in the vicinity of the fired port of a boiler, for detecting a leak of flammable gas or steam, from a poisonous gas such as SO ₂ gas and gives a false alarm. The present invention relates to a combustible gas detector, a gas sensor, and a filter for preventing poisoning.

[0002]

[Prior art]

 Since there is a risk of fuel vapor and gas accumulating and filling up around the boilers of power plants or factories, which may cause an explosion or fire, multiple combustible gas detectors are installed in these workplaces. Strict constant surveillance is in place. When the concentration of combustible gas exceeds a certain value, it is configured to give an alarm. In this case, there are two types of combustible gas detectors: one that allows gas to enter the gas sensor chamber (chamber) by natural diffusion, and one that sucks gas into the gas sensor chamber by forced suction, depending on the purpose of each. It is used properly.

On the other hand, crude oil or heavy fuel oil contains 1 to 3% of sulfur, which varies depending on the place of origin and type. When this is burned, the sulfur content becomes SO ₂ gas and is contained in the combustion gas. Therefore, about 500 ppm of S ₂ O ₂ gas is contained in the gas leaking from the boiler mouth or the like.

In the conventional gas detector of this type, as shown in FIG. 5, since the gas sensor is constantly heated to 350 ° C. to 500 ° C., the gas sensor is used as an ignition source so as not to become an ignition source. Therefore, the gas sensor element (21) is covered with the sintered metal (8). In order to prevent this sintered metal (8) from becoming clogged, a vent hole (23a) was drilled around the bottom of the sintered metal (8), and a stainless wire mesh filter (22) was attached to the bottomed bottom. The funnel-shaped dust filter (23) is tightened and fixed to the sintered metal holding frame (9) formed on the body with the set screw (6), and is attached and covered.

[0005] Then, a gas sensor is used as the combustible gas detector is a metal oxide semiconductor, especially SnO ₂ semiconductor type gas sensor has been used which uses the constantly SnO ₂ is a gas-sensitive substance SO ₂ When exposed to gas, it becomes more sensitive and sensitive to combustible gases. Therefore, even if the concentration of the gas for issuing an alarm is set to a constant value, if the SO ₂ gas is poisoned, an alarm will be issued even if the concentration is below the set value. The present invention has been made to solve the above problems.

[0006]

[Problems to be solved by the device]

Then, in such a gas sensor, there is a problem that the sensor is poisoned by SO ₂ gas contained in the gas component leaked from the boiler main body and deteriorates, resulting in high sensitivity. However, the conventional combustible gas detector had no protective measures against this SO ₂ gas, so the gas sensor was poisoned by SO ₂ gas, increased the sensitivity, and issued a false alarm. The sensitivity of the sensor had to be checked and adjusted using standard gas.

Furthermore, when poisoning of the gas sensor progresses and sensitivity adjustment becomes impossible, it is determined that the gas sensor has reached the end of its life, and it is necessary to replace it with a new one. There was a problem that it was expensive.

In order to solve the problems of the conventional combustible gas sensor, the present invention takes measures against SO ₂ gas to prevent false alarms from being emitted. The purpose is to significantly extend the life of the sensor.

As shown in FIG. 5, the conventional flammable gas sensor has a detection part which is simply covered with a dustproof filter (23) and is not protected against SO ₂ gas. In the invention, the particle size of the SO ₂ gas remover (4) and the layer thickness are adjusted to meet the response speed based on the High Pressure Gas Control Law, and there is no need to make a malfunction and give a false alarm. An object of the present invention is to provide a SO ₂ gas removal filter that can be tightened and eliminates the need for a dust filter (23), and can easily refill and replace the SO ₂ gas removal agent.

[0010]

[Means for Solving the Problems]

The structure of the present invention for achieving the object will be described with reference to FIGS. 1 to 4 corresponding to the embodiments. In the present invention, the outside of the gas sensor (21) is a porous sintered metal (8). A filter cap (5) having a set screw (6) at the center for attaching the filter to the holding frame (9) formed on the main body so that the filter is detachable. A sintered metal holding frame (SO) for removing SO ₂ gas consisting of a filter case (1) forming a cylindrical outer wall to be screwed onto the filter cap (5) and formed on the main body with a set screw (6) ( It is fastened and fixed to 9). In this SO ₂ gas removal filter (20), a lateral hole (1a) is formed inside the outer wall of the filter case (1), and an inner wire mesh (2) is provided on the inner surface of the lateral hole (1a) and an outer bottom surface. An outer wire mesh (3) is attached to the inner side of the wire mesh, and a porous carrier carrying NaCO ₂ as an SO ₂ gas remover (4) is enclosed between both wire meshes (2) and (3) to form a cylinder. The outer wall is provided with a plurality of openings (7) for ventilation and for checking the operation of the filter.

[0011]

[Action]

Since the present invention has such a structure, the atmosphere containing the combustible gas and SO ₂ gas passes through the wire mesh (3) from the opening (7) of the SO ₂ gas removal filter (20). diffused into, in contact with SO ₂ gas removing agent (4) SO ₂ gas reacts with removal agent (4), but SO ₂ gas is fixed as sulfite, combustible gas passes through the diffusion gap And reaches the gas sensor (21), and an electric output corresponding to the concentration is led to the outside of the control room or the like by an electric conductor.

As the SO ₂ gas remover (4), hydroxides or carbonates of alkali or alkaline earth metals can be used. Among these compounds, there are high humidity conditions such as a rainy season. There are some which deliquesce, corrode the filter components, or cause clogging to impair the air permeability, so it is necessary to select it depending on the operating environment. In particular, NaCO ₂ supported on a porous carrier. Is most preferred.

[0013]

【Example】

An embodiment of the present invention will be described below with reference to the drawings. 1 to 4 are views showing an explosion-proof diffusion type combustible gas detector as one embodiment of the present invention. FIG. 1 shows an SO ₂ gas removal filter (20) of the present invention. FIG. 2 is a perspective view showing a partially cutaway section, FIG. 2 is a sectional view in which an SO ₂ gas removal filter (20) is attached to a combustible gas detector, and FIG. 3 is a diagram showing a correspondence between the thickness of the gas removal layer and the response speed, FIG. 4 is a structural diagram of an apparatus for testing and calibrating the output of the gas sensor.

In the present embodiment, in order to make it an explosion-proof type, the outside of the gas sensor (21) is covered with a covered cylinder (8) of porous sintered metal, and the outside is easily screwed to remove the filter. An SO ₂ gas removal filter (20) consisting of a cap (5) and a synthetic resin or metal filter case (1) forming a tubular outer wall screwed onto the filter cap (5) is covered. The set screw (6) that can be attached and detached is tightened and sealed to the sintered metal holding frame (9) formed on the main body. This SO ₂ gas removal filter (20) includes a filter cap (5) having a set screw (6) in the center for detachably attaching the filter to a holding frame (9) formed on the main body, and the filter cap (5). ) Is formed by forming a cylindrical outer wall that is screwed into the inner wall of the filter case (1), and a horizontal hole (1a) is formed inside the outer wall of the filter case (1) to allow ventilation and gas introduction to the outer wall of the cylinder. In addition, a plurality of openings (7) for checking the operation of the filter are drilled, an inner stainless wire mesh (2) is attached to the inside of the lateral hole (1a), and an outer stainless wire mesh (3) is attached to the outside, and A porous carrier having a particle size of 10 to 30 mesh and carrying NaCO ₂ as a SO ₂ gas remover (4) is enclosed between 2) and 3).

When appropriate, combustible gas and SO₂Atmosphere containing gas is SO₂From the opening (7) of the gas removal filter (20), diffuse through the outside stainless steel wire mesh (3) to the SO ₂ SO when contacted with gas remover (4)₂The gas reacts with the scavenger (4) and SO₂The gas is fixed as sulfite, but the combustible gas diffuses through the gap to reach the gas sensor (21), and an electric output corresponding to the concentration is led out by an electric wire.

The dotted line portion shown in FIG. 4 is a device for calibrating the output of the gas sensor (21), which is covered by a cylindrical calibration cap (14) with a lid to seal the outside of the filter (20) and a standard gas. The sampled gas bag (13) is sent into the calibration cap (14) through the spray (12) and the flow stabilizer (11) to check whether the output of the gas sensor (21) is normal or not. You can test. At the same time, gas can be fed into the calibration cap (14), and the time until the output of the gas sensor (21) shows a predetermined value, that is, the response speed can be confirmed. If the response speed is 30 seconds or more, it can be easily removed by loosening the set screw (6) and the cap can be easily removed by turning the filter cap (5). Since (5) comes off, refill the SO ₂ gas remover (4) with a new one, and calibrate again using standard gas.

The particle size of the SO ₂ gas remover (4) was adjusted to 10 to 30 mesh, the thickness of the packed bed was changed to 0 to 15 mm, a gas having an isobutane concentration of 320 ppm was blown, and an alarm concentration was set to 200 ppm to give an alarm. The time until it emitted was measured. As a result, it was found that the layer thickness of the SO ₂ gas removing agent (4) should be 9 mm or less in order to set the response speed within 30 seconds. The results of these measurements are shown in FIG. However, if the layer of the SO ₂ gas remover (4) is made thin, the response speed becomes faster, but the life becomes shorter, and the frequency of exchanging the SO ₂ gas remover (4) increases. Further, when the particle size of the SO ₂ gas remover (4) is increased, the response speed becomes faster, but the SO ₂ gas removal efficiency becomes worse, and when it is small, the response speed becomes slow.

Although the embodiments considered to be typical of the present invention have been described above, the present invention is not necessarily limited to the structures of these embodiments, and is provided with the above-mentioned configuration requirements of the present invention. The present invention can be carried out by appropriately modifying it within the scope of achieving the object referred to in the present invention and having the following effects.

[0019]

[Effect of device]

As is apparent from the above description, the embodiment of the present invention uses, as the SO ₂ gas removing agent (4), a porous carrier having a particle size of 10 to 30 mesh and supporting NaCO _2. The atmosphere containing combustible gas and SO ₂ gas diffuses from the opening (7) of the SO ₂ gas removal filter (20) to the inside through the outer wire mesh (3) made of stainless steel, and SO ₂ When the gas remover (4) comes into contact, the SO ₂ gas reacts with the remover (4) and the SO ₂ gas is fixed as sulfite, but the flammable gas diffuses through the gap and reaches the gas sensor (21). The electric output depending on the concentration can be derived from the electric conductor to the outside. Therefore, the gas sensor (21) is not deteriorated by SO ₂ gas, the sensitivity is increased, and malfunction does not occur, the need for the dust filter (23) is eliminated, and the sintered metal (8) is clogged. Moreover, the SO ₂ gas remover (4) can be easily refilled and replaced, and it is possible to expect a remarkable practical effect of contributing to the rationalization of work.

Further, since the present invention has the above-mentioned structure, there is also a problem that the sensor (21) is poisoned and deteriorated by SO ₂ gas in the gas component leaking from the boiler body. It has been possible to expect the effect of being able to solve the problem and significantly extending the life of the sensor (21).

Further, in the present invention, the response speed of the sensor (21) to SO ₂ gas is adjusted within 30 seconds by adjusting the particle size of the SO ₂ gas remover (4) and adjusting the layer thickness. It is possible to set it, and it is compatible with the response speed (within 30 seconds) based on the High Pressure Gas Control Law, and by simply refilling and replacing the SO ₂ gas remover (4) with a new one, it will be stable over a long period of time. It became possible to operate the flammable gas detector.

[Brief description of drawings]

FIG. 1 is a perspective view showing a partially cutaway cross section of a SO ₂ gas removal filter of the present invention.

FIG. 2 is a sectional view of a flammable gas detector equipped with the SO ₂ gas removal filter of the present invention.

FIG. 3 is a diagram showing a correspondence between a thickness of a removal layer and a response speed.

FIG. 4 is a structural diagram of an apparatus for testing and calibrating the output of a gas sensor.

FIG. 5 is a partial cross-sectional view showing a conventional example.

[Explanation of symbols]

(1) Filter case (1a) Side hole (2) Inner wire mesh (3) Outer wire mesh (4) SO ₂ gas remover (5) Filter cap (6) Set screw (7) Opening (8) Sintered metal ( 9) Holding frame (11) Flow stabilizer (12) Spray (13) Gas bag (14) Calibration cap (20) Gas removal filter (21) Gas sensor (23) Dust filter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Mizoguchi 1768 Misaki, Ako City, Hyogo Prefecture Misaki Shrine B-5 (72) Inventor Kenji Hamada 5-6-18 Takadadai, Kamigori Town, Ako-gun, Hyogo Prefecture (72) Inventor Toshiaki Sasaki 314, Ohara, Taiko-cho, Ibo-gun, Hyogo Prefecture (72) Inventor Teruaki Kitaura 239-12 Shioya, Ako City, Hyogo Prefecture (72) Inventor Hirofumi Kuwamura 1768, Misakisha, Ako City, Hyogo Prefecture B-6 (72) Inventor Koji Shioi 262-6 Nakahirosha, Ako City, Ako City, Hyogo Prefecture 203 (72) Inventor Kenji Masuda 1-9A-umei Umei, Takasago City, Hyogo Prefecture A-202 (72) Inventor A few people, Tomoho 1656 Misaki, Ako City, Hyogo Prefecture 1656 Misaki Dormitory (72) Inventor Hiroshi Yoshino 1183-1 Tsumaga, Shima-ku, Himeji-shi, Hyogo Prefecture (72) Inventor Yoshikazu Morisawa 310 Hirosaka, Taishi-cho, Ibo-gun, Hyogo Prefecture (72) Tadahiro Maeda 2 Mitsuyanaka, Yodogawa-ku, Osaka-shi, Osaka Chome 5-4 Inside New Cosmos Electric Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A filter cap (5) having a set screw (6) at the center for detachably attaching a filter to a holding frame (9) formed in the main body, and a cylindrical outer wall screwed to the filter cap (5). Forming a filter case (1), a lateral hole (1a) is formed inside the outer wall of the filter case (1), and an inner wire mesh (2) and an outer wire mesh (3) are provided in the horizontal hole (1a). Set up tightly,
NaC as SO ₂ gas remover (4) between both wire nets (2), (3)
Formed by enclosing a porous carrier supporting O ₂ and opening for ventilation and filter operation check on the cylindrical outer wall.
Combustible gas detector equipped with multiple (7) filters for gas sensor poisoning prevention.