CS199367B1 - Equipment for analysis of oxygen content in the flue gases - Google Patents

Abstract

1534949 Solid electrolyte oxygen sensor KOMBINAT MESS-UND REGELUNGSTECHNIK VEB 23 Dec 1976 [30 Jan 1976] 53814/76 Heading G1N A sensor for measuring oxygen content of a gas stream comprises a solid electrolyte tube 1 closed at one end except for a capillary 3, carrying internal (4) and external (6) electrodes and surrounded by a furnace 12 having gas passages in a porous body; the tube 1 being attached at its open end to a metal, glass or ceramic air supply tube 35 through which pass the conductors 40 for the electrodes and to the outside of which are attached the furnace conductors 16 and the conduit for the gas stream, the air supply tube being surrounded by a protective tube 32. The solid electrolyte tube 1 and furnace 12 are surrounded by a filter 24, the capillary 3 leading into a tube 27 with side outlets 34 and closed end 29. Reference air is sucked through air supply tube 35 and the sensor by reduced pressure in the gas stream, but positive pressure can be applied if necessary.

Description

The invention relates to an apparatus for analyzing the oxygen content of flue gases by means of a galvanic salt cell comprising a solid electrolyte in the form of a tube open on both sides and an inner electrode surrounded by air and an outer electrode surrounded by the analyzed gas. is reversed to L n ^{and y} ZOV ^{n s p} l ^y it well, and is of ^{p tr} en tepHárním hole and Galvan ^{* i} CKY cL ^and EQS is stored in an oven with holes for the passage of air · · in the porous body

The vacuum in the combustion chamber sucks air into the cell through the capillary opening. This device, which is briefly called a solid electrolyte probe, is designed to continuously analyze the oxygen content of a stream of hot industrial gases · The device works most easily when the pressure is analyzed gas pressure lower than air pressure · In particular, this device can be used to continuously measure the partial pressure of oxygen in the flue gases ·

Of the procedure described in GDR, file No 21 673, in GDR, file no. 48-83,

980 and 11 248 proposed improvements, as well as equipment for carrying out this procedure ·

The embodiment described in GDR 11 248 has proved to be particularly advantageous, with a solid electrolyte cell carrying oxygen ions having a tube shape open on both sides, an inner electrode surrounded by air and an outer electrode surrounded by the gas to be analyzed, the end of the tube of solid electrolyte that is open

199 367. '2

199 397 'towards the gas to be analyzed,' is -. narrowed down to the capillary hole and the salt is surrounded by a chamber with through-holes for 'gas - in a porous ceramic body''Symmetrical arrangement of the salt, heating chamber and porous body guarantees favorable conditions' for salt heating and gas exchange with eye] ± · The cell voltage is not present in this arrangement - in which the weak air flow flowing through the inner electrode does not cause any appreciable cooling drawn by thermoelectric voltages and can therefore be evaluated without calibration according to thermodynamic laws. any sucking analyzed gas and sufficient correction of the measured values on the basis of minor pressure differences between - electric air «K№ <rteu and 'measuring electrodes Z b · ^y tangential stream vzduclhu ^(5-20 1 / h) Buf ^Hooks gaping. by re Eren ^{f S} n ⁱ etaktrody of Slánka is negligible compared to the current analyzed gas in furnaces · Temperature fluctuation Slánka to 10 * K is irrelevant when nároctah to ^EXAMPLE esnos ^t in heating and elektaárnách ·

Other known apparatuses for measuring oxygen in flue gases without sampling using oxygen solid electrolytes are disadvantageous or costly in comparison to the arrangement of HER Pat. No. 111,248. In fixed reference systems, the potential of the reference gradually changes. electrodes due to the permeability of the solid electrolyte material to the oxygen and thereby to the oxygenation of the reference system. can be conveniently evaluated without respecting the temperature, but requires sensitive and fault gas preparation systems ·

The use of small solid electrolyte bodies on metal- or ceramic supports requires specialized brazing or bonding processes and is associated with the risk of temperature breakage. gas must be used with relatively-rapid changes due to uncertainty. · When metal layers are used on the solid electrolyte as potential. - these layers act as electrodes in the hot probes themselves, the dimensions of the salt cells are distorted and there is no longer a certain temperature of the salt and a certain gas measuring point · In addition, there is still a problem of contacting the layers. with flame-resistant alloys, since these alloys form electrically insulating layers · Therefore, no simple, inexpensive and reliable plug connections can be made between the salt cell and the hot probe leads.

Arrangement with heating pipes of the solid electrolyte from the inside and with an arrangement of metal pipes directly on the measuring electrode, chloro oxime tube has openings for the passage of gas and for instance simultaneous serve as potential lead leads likely great disturbances due termoelektMcký ^ overvoltages ^ who ^{EXAMPLE despite} ekrývaj overvoltages ^{it went} ge · s ^ ka wire around a heating chamber with a salt shaker solid electrolyte nedostateSnou provides protection against shock and easily koordujep neSistotě and as explosion protection casing also acts

199 397 fine-porous ceramic body · The 'second salt' in the probe is unnecessary with careful cell design.

In the arrangement according to MR-A-111 248, however, it is difficult to seal the air-filled support tube against the gas chamber at the locations for the insulated passage of the electrical lines and the passage of the gas line. It is possible, but lengthy, to stop with high melting glass or to incorporate conduits into asbestos seals. Simple alkaline sealants greatly reduce the insulating resistance in a hot configuration, ceramic sealants remain mostly porous. with the analyzed gas distorts the measured values ·

Problematic is - further fastening electrical "lead on article · solid electrolyte due to the thrust exerted on the line during assembly is easily torn off the inner mesh cell and release the electrical contact ¹ · drilled pipe in the solid electrolyte -důsledku A deposit of the equipotential lines of the external electrode, folded from outside to inside, to the glass, it is threshing on which the solid electrolyte tube breaks easily under load ·

Coatings coated with fine platinum grating of sintered platinum powder are best suited for long term stability of cells. However, the use of platinum leads and PtRh / Pt thermocouples in long analysis probes is too expensive for wider use in furnaces of all kinds.

Finally, the disadvantage of the arrangement according to the GDR of U.S. Pat. No. 111,248 is that in order to introduce the reference or test gas into the internal electrode, the entire support tube must be purged.

Úč ^e l ^e m of the invention is a refine-T device к potenciomete ^ by analysis of industrial ^p lynů and simplify them to the extent that it can be manufactured easily be reliable function - and could be widely used for control and regulation of industrial plants · and

The invention is based on the task of providing a simple solution for sealing problems, as well as for fixing, electrical insulation and electrical wiring problems so that it is as free from precious metals as possible.

According to the invention, the solid electrolyte tube, with its end remote from the gas to be analyzed, is mounted on an air, conduit made of metal, glass or ceramic and arranged to direct ambient air to a reference electrode within the solid electrolyte tube, which is the power lines are routed to the cell and on the outside are insulated power lines for the cell furnace and gas line and are surrounded by a protective tube ·

According to a preferred embodiment of the invention, in the region of transition from the solid electrolyte tube to the air guide tube, a centering disk is placed on which the heating element is mounted.

198 397 furnace and which is mounted on a common patio for the protective tube and filter element · The electrical knowledge of the heating chamber, insulated in a glass or ceramic tube, and in the case of conduit, thermocouple and gas conduit are closely aligned but not centering • The centering disc pushes on when the indoor building unit is inserted. end against the high temperature sealant disc at the bottom of the filter body · ^{Completely sealed} between the protective tube and the tube for. air ducting with ^p Roveda outside space with analyzed gas at normal temperature by known means · The protective tube is filled with flue gas · prevent disturbances on měřioi electrode due vzduohu or analyzed gas of different composition, which results in the centering disc through unsealed vias, jspu by In another embodiment of the invention, holes are provided in the surrounding protective tube for the passage of the analyzed gas.

According to another embodiment of the invention, the solid electrolyte tube with the air outlet capillary protrudes through a winding or a plug of asbestos and a filter wolf into a tube with side openings on which the end plate rests.

For temperature measurement is term by cell,. preferably a nickel chrome / nickel type with hot brazing in place in the region of the solid electrolyte cell, located outside of the air guide tube or is incorporated. inside the air guide tube ·

^{P N} ew of guidance ^and fixation to the exterior ^and is elektaodě ob ^ Ti. The passage of the solid electrolyte tube through the centering disk is expediently provided on the outer wall of the solid electrolyte tube or is embedded in a groove in the outer wall of the solid electrolyte tube by glass sealing.

According to a further embodiment of the invention, at the end of the solid electrolyte tube directed to the air guide tube is a capillary tubular part 1 of sintered corundum, in the capillaries of which the cell lines are individually arranged. Solid electrolyte and upevntaa glass melt, and which is either P & mo ^{of manufacture} with ^the leněnou melt / '/ or indirectly via one of the guide wire rigidly connected to the tube of solid electrolyte ·

Between the tube of solid electrolyte and between the capillary tube portion in a hood or its electrical supply pipe ^Ia wherein R ^ d is fóetaě microns in ^both walls and ^l eepon one line ^of EZ průohod air from the pipe for guiding air into the tube of solid electrolyte ·

According to a further embodiment of the invention on both layers, contacts or lines of a noble metal, for example a solid electrolyte cell, are preferably welded at the same temperature points by welding, the electrical lines of the opaque alloy.

Transition from; noble metal erosion-resistant alloy can be provided directly on síňkách on průliničitých metal layers of the electrodes, which are for example of platinum or ^p alladia not ^b o to rumor of vzácnéta metal which are to ^tyt axis ^Ink y welded, and mute, 199,397 be Wires of precious metal or wires are used to avoid thermal forces. In each case, for the two electrodes of the same material, the transition points are placed close to each other at a temperature equalization point. The most effectively threaded tubular parts of electrically resistant metal serve as the connection between the metal wires and the aluminum alloy wires. welded · 'erosion-resistant alloy wires comprise for example from nichrome or Kanthal alloy · ¹

According to a preferred embodiment of the invention has a tube for conveying air at the end intended for the air inlet gas tight Objínúcou on which is disposed a gas supply pipe with ^t ro ametrem (device with suspended cough) ·

The flow velocity of the air drawn in through the reference electrode can be observed on the rotameter. The 'solid electrolyte probe standing in the air can be supplied with any test gases through the rotameter and the lance for testing'. which is higher than the air pressure, the inlet pipe is used to inject the reference gas stream.

The device according to the invention has the advantage of manufacturing, assembling and disassembling in comparison with known devices that it consists of individual stable building units. The components consisting of a solid electrolyte cell, a heating chamber, a centering disc and an air duct give the accessory an indoor unit that can be plugged into an outdoor unit consisting of a filter head, a protective tube and a shut-off element. after removal from the indoor unit, cut off from the inlets and the casing is replaced. Also, the defective solid electrolyte cell can be cut off from the inlets after loosening the connection between the air duct and the centering disc and the solid electrolyte cell is stable for long-term operation and they are created with the least content of precious metals in order to allow extensive use · ¹

The outer electrode lead is separated from the solid electrolyte by ceramic insulating tubes and glass sealing »this lead can also be in contact with the probe body · The inner electrode lead is completely embedded in the ceramic tube, thereby guaranteeing electrical insulation can be easily checked and regulated at the entry point · Testing of solid electrolyte cells is possible in the installed state. by feeding the test gas to both the outer electrode and the inner electrode ·

The described solid electrolyte probe operates without a gas pump · It is only necessary to connect the power lines that are routed to the control room · Here the heating current can be taken from the control transformer and the cell voltage as well as with scales for percent oxygen by volume and for degrees Celsius, and can be po6

The invention will now be explained in more detail by way of example with reference to the drawings.

Giant. 1 shows a cross-section of a solid electrolyte probe 8 with a thermocouple on an external electrode.

Giant. 2 shows a cross-section perpendicular to the cross-section of FIG. 1, but with the thermocouple on the inner electrode and with the alignment of the air outlet location altered;

Giant. ? is a diagram of a solid electrolyte probe used to measure oxygen in a flue gas. .

To trublty ^'i with ^p evným ele tro ^{ly to} TEM, both open ^e stoanách is behind. A ceramic capillary 5 is inserted by means of ceramic or glass g. The internal reference electrode 6 of the lead-in platinum layer and the platinum screen is connected to the lead wire 6 and the external electrode 6 also consisting of the lead-like platinum layer and the platinum screen. which is made of the same material as the leakage wire 6, the glass sealing point 6 in the grooves 7 of the solid electrolyte tube X, which is fixed in the asbestos-filled plug 6 '. The seal 2 is seated on the centering disk 10 together with the guide. The electric furnace consists of a ceramic body with gas passage openings 14 and cavities 15 which comprise the electrical wires of the heating wire and are sealed. The electrical connections 16 of the furnace 12 pass through the centering disk 10 in the ceramic insulating tubes 12 and are connected to the heating current conduit 12 via the tubes of a refractory material. The inlets 12 are protected in the ceramic tubes 22 and the centering disk 10 lies above the asbestos disk 22 on the patio 2j.

Cap 22 'carries a porous filter tube 24 »which is assisted holder 25 closed by a filter cover 26''Filtračnívíko 20 comprises a tube 22 of side holes ⁸ 28, wherein the tube 22 ^m ay be open or may be closed by an end plate 22 · gap between the pipe 1 of a solid electrolyte and a filter lid 26 closes the asbestos cord winding 20 or the asbestos plug 51. The base 22 3® is fastened to a protective tube 52 comprising gas passage openings 52. The openings 52 in the protective tube 32 and the openings 28 in the tube 22 are covered by a fine wire mesh 54 for explosion protection. On the asbestos seal there is a gas-tight air guiding tube 35.

On the other hand, in front of the open end of the solid electrolyte tube 1, a capillary tubular member 50 is disposed. At this end of the solid electrolyte tube 1, an air passage cutout 52 is provided, the cutout opposite to the cutout 37 comprising a lead wire Z, sealed into glass. The electrical conductors 4 and 2 of the solid electrolyte cell are fixed in a tubular capillary tube by glass. panel 34 and through trubičky'jQ of erosion-resistant material and connected with a wire (£ 0, also from cpalnvzdcrnéhc material. Heat ^to Lane ^No. 41 type. ^Ni Cr ^{/ Ni} is stubbornly either externally on tauboe 50 ^P ro airflow in the ^ra me ^The capillary tube 52 is embedded in the solid electrolyte tube 1 and guided through the tubular capillary member 56 and the air guide tube 52. In addition, a flame-resistant steel cannula 43 extends along the air guide tube 52 through the centering disk 10.

199 397 Together with Ceramic Pipes 21 and 42 Is the steel canal 50 fixed to the air guide tube 52 by opaque metal wires 44? called test signal * This test signal and its temporal behavior. gives information on the dynamics and - aging of the solid electrolyte cell ·

· Figure J shows instruction probes with ^p evným Elektrol ^s tem, umístěným- ro ^{p e} ni measuring oxygen in the flue gas in the combustion chamber ·

The solid electrolyte spindle is surrounded by a protective tube 22, which is outside of the furnace chamber wall 52, gas-tightly connected to the pipe 52 For air conduction having a collar 46 ··· The other end of the probe that protrudes into the furnace chamber is a solid ele trol ^the TEM ^{y Ca} · ^T ^ i ^ s ^ nu ^ly op g ^ přta Zii. ^p ro measurement kysHku article in a solid electrolyte, or a part of the flue gas - flow outside the cell with a solid electrolyte, the entire flue gas leaving the chimney g · Reference gas such vz ^d uh, pMchází. ^EXAMPLE es conduit £ ££ with rotameter (flowmeter) into ^{a straight} pipe ⁴⁷ and the supply air objimkrnu 46 to the inner electrode of the cell with solid electrolyte · £ Reference air flows through the capillary into the combustion chamber, and the probe is a solid electrolyte ^to ODVA ^d en ou ^r ew ^ply nem R * V ^{b of} the can by ^T £. collected on No. EIT ^p ^ ge. from ^- electrodes (external ^and vnittaí and e-electrode on the m ^ ^s s ^{t h} e £ m ^b e ^longer taken thermoelectric ^yt ^ r ^ W and the voltage at the point ^£ can be connected to a heating power for the furnace.

Claims (10)

1 · Equipment for analyzing the oxygen content of the flue gases with the aid of. a galvanic cell consisting of a solid electrolyte in the form of a tube open on both sides, with an internal electrode surrounded by air and an external electrode surrounded by the analyzed gas, the end of the solid electrolyte tube facing the analyzed gas having a capillary opening and a galvanic cell It is housed in an oven with openings for the passage of air in a porous body, characterized in that the solid electrolyte tube (10), with its end facing away from the gas to be analyzed, is mounted on an air guide tube (35) made of metal, glass or ceramic materials, and which is uspořtó ^ and for guiding ^and Otol ^ him air к re ^f Eren ^{N NU} e ^lacquer TRODAT ⁽⁴⁾ inside the tube ⁽¹⁾ from the solid el ^e ktrolytu ^{6 to} Tero are guided etattr-tert management ^and (5, 7) ^{to the element} then and which are insulated from the outside ^says disposed ^^ e ^ rta line. ⁽¹ 6) for a heating furnace (12) of the article ^{and p} l ^{y newly} fed ^and (43 ^ and ^a is oblk ^ p woman with protective desire ⁽ 32 ⁾ · 2 · Device according to claim 1, characterized in that in the transition area from the pipe '(1) from the solid Elektrol ^y herein to tubes ^to u (35) for guiding ^the air is uirás ^ are assured cente ^- wheel (10) ^kt ESEM is u ^ female ^t o ^p N ^{and P} ec ⁽¹²⁾ and ^kt era is mounted on the SLP ^l ECN ^s Pa ^Ti c ^{i (23)} to the protective pipes ^to u ^{(32) and FII} trαčn ^{i '-} i ^ Sa ⁽ 24 ⁾ · 198 3Β7 3. Device according to claim 1, wherein the protective tube (32 ⁾ has openings (33) for the passage of the gas to be analyzed. 4 · Glare ^and zen ^IP ccording to claims 1 to 3, there vyznačují.cií, ^Z e tube ⁽¹⁾ from the solid-eta rclytu and capillary (3) for outlet of air in ^y vinutLm Hand ^and VA (30) or UC ^p AVKO ⁽³¹⁾ from the filter ^and asbeatu ^and CN ± m lid ⁽²⁶⁾ into a tube ⁽²⁷⁾ and lateral openings ^and mi ^(2S) _I era abuts on ^{kt. k} oncov 'dea ^k a ⁽ 29 ⁾ · 5. Zařtaoní. according to item ^{1 to} 4 distinguished. ^ 'e ⁱ n that the thermo ^ARTICLE no ^{to (41),} and preferably of nickel chromium-nickel and hot ^Fr Jena mtatem in ^b las ^t i ^c l ^á HKU ⁽¹⁾ and solid ktroJytam e ^ j placed outside the pipe ^{(35) P b} ro'vedení no air is incorporated by UVN ^{i TER} pipe ⁽³⁵⁾ for guiding air · 6 · 'under ^RI zen ^cut down stings. ^1-5 wherein *, ^TI m, ^from E to ^P z- line. ⁽⁷⁾ U evněné the outer electrode (6U is in the passage of the tube (1) from solid electrolyte centering disc ^{(L 0)} is provided at said ^external tent tru ^{BKY (1)} of ^p EVN ^é it. Ele ^ ro ^ t and not ^b is a woman of u ^ ^f paw in the outer. wall of the insert tube ⁽¹⁾ from ^p EVN ^é ^ ro ^ eta Lytu sealing glass ^(8). 7 Device. ^p from ^l e points. ¹ § characterized in-that t ⁱⁿ that at ^the downstream end pipes' ⁽¹⁾ - from ^p evné ^h of an electrolyte, which is directed into a tube (35) for guiding air, the capillary tube part (36) of ^e and ^Pék An ^eh o 'is ^H corundum in oz ^for ILAR and ^p are stored jednotHvě ele ^thirty-ka line. (5 * 7) cell ⁽¹⁾ and the fixed e ^ ktaoíytem, the fixed glass melt (38 ^ ^and which is either Prince molten glass (3S) no ^b o ne ^EXAMPLE mo ^EXAMPLE EC ^d en of the conductor ^and c ^H Dr ^{sulfates (5} n ^e bo 7) and rigidly connected to the tube (1) from solid electrolyte * 8 · retracted under Point 7 * ^{characterized brand} uj ^s c ^s e there ^from E. limit ^and barrel ⁽¹⁾ from ^p evného ELE ^to an electrolyte ^and between kapilárnto tubular dttem ⁽³⁶⁾ UEBO in ^{AP ilá} darkroom trubtovém DHU ^{(36 )} is uitastěn ^{and p} ou les one line ^of ez ⁽³⁷⁾ for the passage of air to tru ^BKY (35) for guidance of air into the tube ⁽¹⁾ of the fixed ^eh elektroljrtu · The device according to points 1 to 8, characterized by: ae in that on both layers, contacts or guidance ^and CH ⁽⁵ and 7) from ^{rarely him} ovu such ^example Cl ^and n ^ u (1) from the solid ^é by e ^ ktrolytu are locations of the same temperature is attached, and preferably welding, electric lines (40) of the op ^al uvzdorn ^{é y} alloy (39) · 10 · 'Apparatus according to claims 1-9, characterized in that the tube (35) for guiding the air on the end ^determined en ^é m input vzducta plynotěenou objhnku at which ^E umtatěna ^p řivodn ^{s t} ru ^BK and (47) for ^p l ^y n, a. rotameter (4)