JPH0654305B2 - Industrial gas concentration measuring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an industrial gas concentration measuring device, and more specifically, it is installed on a furnace wall or exhaust gas passage wall of various combustion furnaces such as industrial furnaces and boilers. The present invention relates to an industrial gas concentration measuring device for measuring a gas concentration in combustion exhaust gas or an atmosphere in a furnace or an exhaust gas passage.

(Prior Art) Conventionally, as this type of industrial gas concentration measuring device, for example, a cylindrical probe that is inserted into various combustion furnaces and collects exhaust gas, and a part that is provided in this probe and exposed to exhaust gas It is composed of a bottomed cylindrical oxygen detection element and a filter for removing soot and dust in the exhaust gas. The oxygen detection element is, for example, a solid electrolyte having oxygen ion conductivity, for example, a stabilized zirconia porcelain doped with calcium oxide or yttrium oxide as a partition wall, and a measurement electrode layer and a reference electrode layer provided on both sides of the partition wall, respectively. Is an oxygen detection unit, one of the electrodes is exposed to a reference atmosphere, and the other electrode is exposed to exhaust gas, and an electromotive force generated by the principle of the oxygen concentration battery is used as a detection signal.

By the way, in such a gas concentration measuring device, it is necessary to take out an electric output to the outside of the combustion furnace according to the gas concentration in the gas to be measured which is detected in the oxygen detecting section of the oxygen detecting element. Therefore, an auxiliary lead wire for connecting the oxygen detection element and the external lead wire is provided in the probe.

(Problems to be Solved by the Invention) However, the oxygen detection element and the auxiliary lead wire can be connected to each other by a contact means such as a connector having a spring piece made of phosphor bronze in a low temperature range, but a high temperature. In the region, the contacting means such as the connector deteriorates the spring characteristics and causes poor contact, which is undesired in this temperature region. Therefore, conventionally, when used in a high temperature range, a lead wire made of platinum is brazed and connected to an electrical contact of the oxygen detection element by silver brazing, platinum brazing or the like. In this way, the connection will be reliable, but the connection work will be troublesome and difficult, and if the oxygen detection element is provided at the tip of the probe as in the direct insertion method, the There has been the inconvenience of having to replace each probe in order to replace the detection element.

The present invention eliminates such conventional inconveniences, the detection unit is small and lightweight, only the detection unit can be replaced when the detection unit deteriorates, and the detection unit can be easily attached and detached. An object is to provide an industrial gas concentration measuring device.

(Means for Solving the Problems) In the industrial gas concentration measuring device of the present invention, a sensing unit in which a sensing cell and a heating body and / or a temperature sensing body are integrally laminated in a plate shape is arranged in a probe. An industrial gas concentration measuring device comprising: a contact having a heat-resistant electric contact provided in the probe, and a protective tube accommodating the detection part is detachably attached to the probe through a mounting flange. At the same time, the electrical contact terminal provided at the base end of the detection unit is detachably inserted into the heat-resistant electrical contact of the contact to be electrically connected.

(Operation) In the above-described configuration, the detection unit has a plate-like laminated and integrated structure, so that the detection unit is thin and compact and lightweight. Also,
The electric contact terminal provided by printing on the detection portion and the heat-resistant electric contact are guided to the connector to facilitate electrical connection. The contact between the electric contact terminal and the electric contact is effectively ensured even in a high temperature range to some extent. Further, the protective tube for housing the detector is detachably attached to the probe, so that the manufacturing and assembling work of the device can be remarkably simplified.

(Example) As a specific example of the industrial gas concentration measuring device of the present invention, a case of applying to an industrial gas concentration measuring device will be described with reference to the drawings.

FIG. 1 is a sectional view of a main part of an industrial oxygen concentration measuring device according to an embodiment of the present invention, in which 1 is a detection part, and this detection part 1 has a mounting flange 2 and a cylindrical probe 3 It is supported in the probe 3 by being screwed to the protruding portion 4. The probe 3 is made of a metal such as alumina. A filter mounting auxiliary tool 5 is detachably attached to the tip end surface of the probe 3 by using a sealing means such as a metal O-ring 6 and screwing. A porous ceramic filter 7 for removing dust is attached to the other end of the auxiliary tool 5 through means such as alumina cement. Further, a gas rectifying plate 8 having a semi-cylindrical shape with a bottom is provided on the outer periphery of the thick portion of the auxiliary tool 5 so as to have an opening on the downstream side of the exhaust gas flow. The gas rectifying plate 8 prevents the exhaust gas from being directly blown onto the ceramic filter 7 and prevents the filter 7 from being contaminated by soot and dust.

Further, in the probe 3, an electric contact terminal M of the detection unit 1 which will be described later is directly inserted into a funnel-shaped contact 11 screwed to the protruding portion 10 of the probe 3, and a heat-resistant elastic connection fitting provided on the contact 11. 12 can be electrically connected. Further, the connecting fitting 12 is connected to a lead wire 13 which is electrically connected to an external control circuit. The material of the lead wire is preferably platinum wire in consideration of heat resistance.
Since the lead wire 13 taken out from the contact 11 through the probe 3 to the outside insulates the respective lead wires from each other, in the vicinity of the funnel-shaped contact 11, the lead wire 13 is inserted through, for example, a miniature insulating tube 14 made of alumina, It is taken out of the probe through the inside of this alumina insulating tube. The alumina insulating tube 15 is attached to a metal plate 16 having a width substantially equal to the diameter of the probe 3 and extending inside the probe by a mounting member 17, for example.

By the way, a calibration gas introducing pipe 18 penetrating from the outside of the probe to the side wall of the auxiliary tool 5 on the gas flow downstream side is provided,
It is also possible to supply the calibration gas through the calibration gas introduction pipe 18 to the oxygen detection portion D of the detection unit 1 which will be described later. By doing this, the output signal of the detection unit 1
A transition due to high temperature exhaust gas can be detected, and this transition can be electrically corrected by an external control circuit.

Next, the detection unit 1 and the funnel-shaped contact 11 will be described with reference to FIG. The outer periphery of the detection unit 1 is covered with a cylindrical metal protection tube 20, and the oxygen sensor element S is housed in the protection tube 20. The oxygen sensor element S is supported by two cylindrical ceramic spacers 21 and 22 which are spaced apart from each other in the middle portion thereof, and a sealing agent 23 such as cement or talc is filled between the ceramic spacers 21 and 22, Further, a sealant 22a such as glass is filled in the oxygen sensor element S on the base end side of the ceramic spacer 22 so as to be airtight to the air 29 on the tip side of the protective tube. The space 29 on the tip side of the oxygen sensor element S separated in this way
While the oxygen detecting portion D of the oxygen sensor element S is located at the base end portion of the oxygen sensor element S, the base end portion 24 having the outlet of the air passage 51 and the electrical contact terminal M, which will be described later, is provided at the base end portion side. It projects and extends from.

The base end portion 24 projecting from and extending from the protection tube 20 is guided by the inner surface of the conical portion 25 of the funnel-shaped contact 11 having the housing of the low temperature firing porcelain and inserted therein. . Further, the insertion of the base end portion 24 is ended by the housing of the protection tube 20 coming into contact with the conical portion 25, which effectively prevents the detection portion 1 from being excessively inserted into the contact 11. . The base end portion 24 of the inserted oxygen sensor element S is elastically connected to the electrical contact terminals M formed by printing on both surfaces thereof (see FIG. 3 (B)) and the connecting fitting 12 made of a heat-resistant spring material. To make an electrical connection between them. The material of the connecting fitting 12 is high temperature (for example,
SUS material, Ni-Cr steel, etc. are used so that the spring characteristics do not deteriorate even at 600 ° C), and they are plated with platinum or gold to improve conductivity. Therefore, even if the contact 11 is exposed to a high temperature atmosphere, the contact between the electric contact terminal M and the connection fitting 12 can be effectively ensured, and an effective electric connection can be made. In addition, in the cylindrical portion 26 of the funnel-shaped contact 11, an insulator 27 is provided to electrically insulate the metal fitting 12 and the platinum lead wires connected thereto.
Is stored.

Reference numeral 28 denotes a mounting housing portion screwed to the protruding portion 10 of the probe 3.

In this way, the electrical connection of the lead wires to the plurality of electrical contact terminals M can be made at the same time by inserting the base end portion 24 of the oxygen sensor element S. The effect of simplifying and speeding up the assembly work of this device is remarkable.

Next, regarding the structure of the oxygen sensor element S, FIG. 3 (A), (B)
Also, description will be made with reference to FIG.

First, in the upper part, the solid electrolyte body 40 and this solid electrolyte body
An oxygen pump portion P including an upper pump electrode 41 and a lower pump electrode 42 arranged on both upper and lower sides of 40 is provided. An upper heating portion H1 is provided on the upper surface side of the oxygen pump portion P so as to surround the upper pump electrode 41.

Next, similarly to the oxygen pump section P, the solid electrolyte body 43
And the measurement electrodes arranged on the upper and lower sides of this solid electrolyte body 43.
An oxygen concentration battery section B consisting of 44 and a reference electrode 45 is provided.

It should be noted that, between the oxygen pump portion P and the oxygen concentration battery portion B, a diffusion chamber 46 having a narrow gap flat space for guiding the gas to be measured under a predetermined diffusion resistance is formed from an insulator. A space member 47 (47a, 47b) having a predetermined thickness is interposed. In addition, at a position corresponding to the central portion of the diffusion chamber 46 in the oxygen pump portion P, gas introduction holes 48 (48a, 48b, 48c, 4) for communicating the diffusion chamber 46 with the external space in which the gas to be measured exists.
8d) has been formed. Therefore, this gas introduction hole 48
(48a, 18b, 48c, 48d) guides the gas to be measured to the diffusion chamber 4
It is diffused under a predetermined diffusion resistance in 6 and contacts the lower pump electrode 42 of the oxygen pump portion B. Further, the lower pump electrode 42 is also connected to the measurement electrode 44 of the oxygen concentration battery section B.
Contact the gas to be measured in the vicinity of.

Next, below the oxygen concentration battery section B, a space member 49 made of a solid electrolyte body and a solid electrolyte body 50 are sequentially provided. As a result, an air passage 51 exposing the reference electrode 45 is formed. The air passage 51 communicates with the atmosphere at the base of the oxygen sensor element S. The reference air, which is the atmosphere, is introduced through the air passage 51 and comes into contact with the reference electrode 45.

In the air passage 51, a temperature detecting portion T is provided on the lower surface of the solid electrolyte body 43 at a position close to both sides of the reference electrode 45.

Furthermore, a lower heating unit H2 is provided on the lower side. Therefore, the heating section H2 and the upper heating section H1 are arranged on both sides of the oxygen pump section P and the oxygen concentration battery section B so as to sandwich the oxygen pump section P and the oxygen concentration battery section B, and the predetermined temperature (for example, from both sides). It can be heated to more than 600 ℃.

The solid electrolyte body 40, 43, 50 and the space member 49,
It is composed of stabilized or partially stabilized zirconia porcelain that exhibits oxygen ion conductivity at high temperatures. As is well known, this stabilized or partially stabilized zirconia porcelain is obtained by dissolving yttrium oxide, calcium oxide or the like in zirconium oxide.
The electrodes 41, 42, 44, 45 are each made of porous platinum or the like. Of these electrodes 41, 42, 44, 45, the upper pump electrode 41 and the lower pump electrode 42 that come into contact with the gas to be measured.
The measurement electrodes 44 are provided with porous ceramic layers 52, 53, 54 made of alumina or the like in a laminated state. Therefore, these porous ceramic layers 52,
The gas to be measured comes into contact with the electrodes 41, 42 and 44 through 53 and 54, respectively.

On the other hand, the heating portions H1 and H2 cover the heater elements 55 and 56, which are heater elements, with porous layers 57 (57a, 57b) and 58 (58a, 58b) made of alumina or the like having electrical insulation properties. It is provided in the opened state. These porous layers
Airtight layers 59 and 60 made of a solid electrolyte such as zirconia are further provided on 57 (57a, 57b) and 58 (58a and 58b).
As a result, each of the heater elements 55 and 56 can be shielded or isolated from the external measured gas.
The heater elements 55 and 56 are formed by a method such as printing and arranging a paste containing alumina powder and platinum powder as main components, or arranging a cermet-shaped film.

Further, the oxygen detector T has a structure including a resistor or the like having a positive or negative temperature coefficient whose electric resistance largely changes due to temperature change. The temperature detecting element 61 is constructed by being embedded in a porous layer 62 made of alumina or the like having electrical insulation, and surrounding solid electrolyte body 43 and space member.
It is designed to be electrically isolated from 49. It should be noted that the temperature detecting element 61 of the resistor is a paste containing ceramic powder such as zirconia and alumina and platinum powder as main components, or a paste containing cermet, ceramic powder such as zirconia and alumina and platinum powder as main components. Positively, such as a paste or cermet with about 0.5% titanium dioxide added, or a paste or cermet with manganese, cobalt, or nickel oxide added to a ceramic powder such as zirconia or alumina. It is formed by printing and laminating a paste having a higher temperature coefficient of resistance, or arranging a cermet-shaped film. Further, as the temperature detecting element 61 of the resistor, zirconia porcelain, platinum wire, platinum thin film, or the like may be used. A technique such as CVD, vacuum deposition, or sputtering can be used for the print lamination of these platinum wires or platinum thin films. Further, instead of the temperature sensing element 61 of the resistor, different metals (for example, platinum and gold) or pastes or cermets containing these different metals are combined and printed and laminated as a thermocouple to form a thermocouple. The temperature detecting element 61 may be configured.

The oxygen pump portion P, the oxygen concentration battery portion B, the upper heating portions H1 and H2, the temperature detecting portion T, and the space member 47 as described above are stacked as shown in the figure, and have an integrated narrow plate-like longitudinal shape. The laminated structure is formed into a unitary structure by sintering. Note that M is the upper pump electrodes 41, 42, the measurement electrode 44, the reference electrode 45, the heater element.
55, 56 and temperature sensing element 61 with printed electrical contact terminals.

In the case of the present embodiment, the oxygen pump portion P and the oxygen concentration battery portion B constitute the sensing cell in the present invention, but the sensing cell may be constituted by only one of them.

Further, from the oxygen sensor element S, the heating body or the temperature detecting body can be omitted.

(Advantages of the Invention) In the industrial gas concentration measuring device of the present invention, the detector can be easily attached to and detached from the probe, and the detector is connected in order to maintain a reliable electrical connection even in an atmosphere at a higher temperature than before. The work is extremely simple and the assembling work can be simplified.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional side view showing the device of the present invention, FIGS. 2 (A) and 2 (B) are more detailed explanatory views of FIG. 1, and FIGS. 3 (A) and 3 (B) are detection results. 3 is an exploded perspective view and a perspective view of a portion (oxygen sensor element), and FIG. 4 is a transverse sectional view taken along line III-III in FIG. 3 (A). 1 ... Detection part, 3 ... probe 11 ... funnel-shaped contact, 12 ... connection fitting 13 ... lead wire, B ... oxygen concentration battery part H1, H2 ... upper and lower heating part M ... electrical contact Terminal, P ... Oxygen pump section T ... Temperature detection section

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location 7363-2J G01N 27/46 327 H 7363-2J 27/58 B (56) References JP-A-60 -128348 (JP, A) JP 61-108953 (JP, A) JP 54-123091 (JP, A) JP 60-123758 (JP, A) JP 60-188840 (JP, A) ) Actual development Sho 54-394 (JP, U)

Claims (1)

[Claims] 1. An industrial gas concentration measuring device comprising a probe and a detection section, which is formed by integrally laminating a sensing cell and a heating element and / or a temperature detecting element in a plate shape, and is provided in a probe. A contact having a contactor is provided in the probe, and a protective tube accommodating the detection part is detachably attached to the probe through a mounting flange, and at the same time, an electric contact terminal provided at the base end part of the detection part is attached. An industrial gas concentration measuring device, characterized in that it is detachably inserted into a heat-resistant electric contact of the contact and electrically connected.