CN1071509A - SO 2 sensor and process for detecting SO 2 - Google Patents
SO 2 sensor and process for detecting SO 2 Download PDFInfo
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- CN1071509A CN1071509A CN 91109616 CN91109616A CN1071509A CN 1071509 A CN1071509 A CN 1071509A CN 91109616 CN91109616 CN 91109616 CN 91109616 A CN91109616 A CN 91109616A CN 1071509 A CN1071509 A CN 1071509A
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Abstract
The present invention relates to low concentration oxysulfide (SO in a kind of detection air flow (being generally burner exhaust stream)
2) method and a kind of catalysis SO that can be used for this method
2The sensing system.
Description
The present invention relates to the sulfur oxide (SO that a kind of detection is present in low strength range in the air flow (generally being burner exhaust stream)
2) method and relate to a kind of catalytic type SO that can be used for this method
2The sensing system.
The compound of various sulphur (is generally SO in the waste gas that the fuel combustion of originating with air oxidant produces
2Or SO
3) content little, but merit attention very much.SO
2Being the photochemically reactive participant who forms modern " smog ", is very tedious therefore.
Existing many can removing or treatment S O
2Method, but each such method is to depend on accurate detecting device to detect low content SO to a great extent
2.The commercially available low content SO that in fact is applicable to closed loop controller
2Sensor is actually rare.Many previous measurement mechanism insufficient sensitivity.Therefore, need to be lower than the SO of 150ppm in the suitable precision measure burning gases
2The ability of content.
A kind of SO
2Mensuration comprises infrared beam, detecting device and than the use of measuring cell.At US 4,647, be that a branch of infrared light is entered in the selectivity infrared detector by gas sample in 777(Meyer).Light beam is divided into two, and a part is by the container of a carrying liquid, and this liquid can absorb selected gaseous spectrum wavelength, and two light beams are compared, and its difference is represented the amount of selected gas in the sample.
US 4,836, people such as 012(Doty) semiconductor devices made of a kind of photoelectric cell of narration, when exposure, the voltage of generation or electric current change as the function of the kind of adsorbed gas.The Schottky type restraining barrier that this device needs a kind of its electrical property to change with the kind of adsorbed gas, this layer is a kind of gas absorption metallic film of printing opacity.This patent suggestion is used for detecting CO, hydrocarbon, water vapour etc., and suggestion does not detect SO
2
US 4,778,764(Fine) describe a kind of Apparatus and method for, wherein the sample of band solvent injected the various materials that chromatographic column exists with separating sample.The effluent of chromatographic column is at one or more NO
x, SO
2, CO
2There is burning down with the halogen detecting device.
Neither one proposes to use the catalysis sensitive element to detect the method or the device of the existence of gaseous component in the patent specification of above invention.
With the mark of the gas temperature rising of gas when catalytic bed reacts as the component concentration of this gaseous mixture, this notion has obtained proof.For example at US 2,751,281(Cohen) in, the method for the light concentration gas impurity (for example oxygen) of a kind of measurement in the 0.0001%-0.001% scope is disclosed, the thermopair of configuration makes cold reference junction be placed on the upstream of catalytic bed, thermojunction is placed on the downstream.When gas stream is crossed catalyzer,, the temperature of measurement gas calculates the composition that enters gas thereby raising.
US 3,488,155(Ayers) disclose a similar approach, and the temperature on its every limit of hydrogenation catalytic bed is to measure in containing the hydrogen stream of gas.Temperature difference is relevant with the hydrogen richness of inlet air flow.
US 3,537,823(Ines) propose, and measure the amount of " hydrocarbon that forms smog in the gas sample " by the way of measuring temperature rise in the oxidation catalysis bed.In addition, at US 3,547, find relevant method in 587(Ines).
US 3,607, people such as 084(Mackey) measuring method of a kind of combustible gas content of narration disposes couple of conductor in splendid attire has the cell of inflammable gas, catalytic mixtures with metal oxide and platinum group metal powder is coated on the surface of single line, and another root does not then have coating.To two line electric heatings.Change the amount that caused resistance difference provides combustible in this gas container by the band coating conductor temperature.
US 4,170, and the temperature that 455(Henrie) also proposes the upstream and downstream by measuring oxidation catalyst is monitored the hydrogen of air-flow or the method for oxygen content.
US 4,343,768(Kimura) narrated a kind of detector with semiconductor technology.Detecting device adopts two heating elements at the head and tail of gas channel.An element applies with " catalysis or air-sensitive film ", and film can be platinum or palladium.Detect the increase of catalytic membrane temperature, amount to into the composition that resistance variations is come calculated gas flow.
At last, US 4,355, people such as 056(Dalla Betta) a kind of differential thermocouple combustible gas sensor proposed, thermopair knot catalytic coated wherein, and another knot does not apply.Contain gas in the air-flow, it is said to such as SO just like carbon monoxide and hydrogen and so on
2With the pollutant of NO and so on be insensitive.
In above patent, all do not propose to remove in the tested air-flow of first catalytic oxidation SO
2Outside whole oxidizable substances, then on independent catalysis element SO
2Be oxidized to SO
3
The present invention relates to a kind of sensor groups that the catalytic oxidation pre-converter is housed and particular configuration on the catalysis sensitive element function of the thermometric device (for example thermistor or RTD(resistance temperature detector) that overall thermal isolates is housed.Another part of sensor is the temperature reference elements.
This sensor arrangement, especially together with the method for invention, make sensor very accurately express-analysis by the SO of gas
2Content, and to insensitive from the interference of other component in the tested air-flow.
As mentioned above, the present invention relates to a kind of SO
2Sensor and this sensor of use are measured the SO in the air flow
2Method.
Sensor groups itself can partly be made up of three main discrete function: catalytic oxidation pre-converter, catalysis sensitive element, reference sensitive element.
The catalytic oxidation primary heater is to remove SO in the tested air-flow
2Most of oxidizable species in addition, for example NO
x, CO, amine, NH
3, wait the such catalytic oxidation stage that all is oxidized to highest oxidation state.
Catalysis sensitive element and reference sensitive element (in being configured in air-flow time) are the downstreams in the catalytic oxidation pre-converter.Have and being suitable for of thermometric device contacts in the periphery of catalysis sensitive element SO
2Be oxidized to SO
3Catalyzer.Both generally isolate with operating environment heat, and heat is isolated mutually.Selection of catalysts and the arrangement around the thermometric device should make the just SO of gas flow rate
2Be oxidized to SO at catalyst surface and oxygen
3The thermometric device can be RTD, thermistor, or thermopair, and this device detects because of SO takes place on the catalyzer
2Oxidation and the faint temperature rise that occurs.Catalyzer answers entity closely should be able to keep the reaction heat that most of reduction reaction produces near (desirable contacts) and its structure with the thermometric device.Reaction heat should only cause rising with the temperature of the thermometric device of catalyzer intercommunication, available dividing plate or guard shield reduce the heat that radiation is fallen near the catalysis sensitive element, and this radiation comprises from this catalysis element to reference elements (if use) or to the radiation of other peripheral part of sensor groups.
The temperature of catalysis sensitive element obviously is converted into electricity by the thermometric device and can measures (voltage, resistance etc.) and compare with the similar quantity from reference elements.SO in the difference of its temperature and the tested gas
2Concentration is directly proportional.
As all high-quality measuring instruments, the calibration of sensitive element group is desirable, also is necessary.
Fig. 1 is the block scheme of device of the present invention.
Fig. 2 is the carrier that is applicable to the catalytic oxidation pre-converter.
Fig. 3 is the sensitive element group that is used for senser element of the present invention.
Fig. 4 is whole SO of the present invention
2The section sketch of senser element.
Fig. 5 is as sensor groups SO
2, the sensor output curve diagram to the input function of sensor groups of NO and hydrocarbon.
The present invention relates to measure low concentration SO2Sensor and detect SO in air flow with this sensor2Method.
As shown in Figure 1, enter gas and can contain various components, in the burning air-flow, remove SO2Outside also can have such as CO, H2, HCN, amine etc. component. Enter air some N are arranged usually2And O2Exist as component, they react by the burning process. In the catalytic oxidation pre-converter, catalyst is oxidized in the back SO to other component2The material that measuring phases is can not be more oxidized. For example, in the pre-inversion stage, the CO of existence is oxidized to CO2, this CO2At catalytic type SO2Non-oxidizable in the sensing element.
The gas that contains already oxidised gas component enters SO then2Measuring phases, the oxidant here, for example O2, on the catalytic type sensing element SO2Be oxidized to SO3, because oxidation is anti-Should, the temperature of catalytic type sensing element raises. This temperature rise is to be oxidized to SO at the catalytic type sensing element with being present in the air-flow3SO2Amount is relevant, therefore, is SO with tested gas from the signal of telecommunication output of catalytic type sensing element2Content is relevant.
The catalytic oxidation pre-converter
Pre-converter is a kind of simple catalyst bed or monolithic, with a kind of at a lower temperature very active catalyst come can be oxidized in the oxidizing gas stream component (SO2Except). We have found that, many VIII family noble metal, for example Ru, Rh, Pd, Os, Ir and their mixture are especially suitable as catalyst in this stage. Platinum is unaccommodated, because it is SO2Be oxidized to SO3 What preferentially select is rhodium, palladium, particularly their mixture. These metals can at 300 ℃-500 ℃, be preferably under 400 ℃-500 ℃ and make non--SO2(and nonhydrocarbon) but the oxide oxidation.
The amount of the VIII family noble metal that exists in the catalyst should be effective amount at least, and this amount depends on, for example, and the activity of selected catalyst, the easy degree of evenly disperseing and the type of used substrate. But common metal content is about 0.01%-3.5%, is more preferably 0.01%-2.5%. In addition, the metal consumption when adopt filling bed is generally 0.1%-2.0%(weight), be 0.01%-6%(weight when selecting high space-time speed through the monolithic substrate of passage).
The method that the VIII family noble metal of mentioning is added on the substrate has: add when dipping, carbonyl decomposition, Gas Phase Adsorption, substrate are synthetic, the absorption of metal steam; The most handy dipping method.
Fig. 2 shows the monolith catalyst substrat structure that is suitable for as catalytic oxidation pre-converter carrier, and it can be made up of any suitable carrier material. As with pottery, be advisable with cordierite. As Use metal substrate, be advisable with salic steel. Can use aluminium oxide, swollen profit clay, diatomite, zeolite, silica, active carbon, magnesia, oxidation boron, titanium oxide, silica, aluminium oxide etc. carry out suitable compacting, and are molded or make bonding material all in one piece with other method. The surface area of carrier should be greater than about 50m2/ g is preferably 100m2/g-300m
2/ g. Require this material all in one piece pressure loss when gas flows through lower. On the other hand, because the gas high velocity stream is crossed material all in one piece, the UD of required catalytic metal may be bigger. Preferably by containing Al2O
3The low surface area metal carrier made of corrugated plating steel. This kind material generally is used for the catalytic converter of automobile, has bought easily on the market. Should be coated with the high surface area material film on this metal carrier, for example the aluminium oxide slurries generate the carrier that adheres to after doing, and roasting becomes high surface area carrier again. Add as mentioned above then catalysis material.
On the contrary, catalyst support can be the packed bed form of particle, slimeball, Pall ring etc., is made by above-mentioned same material.The catalyzer that general packed bed need be used lacks than the monolithic material all in one piece, because the hourly space velocity of gas much lower than in the monolithic material all in one piece in the packed bed.
SO
2Sensor groups
Sensor groups is by two critical primary clusterings (catalysis sensitive element and reference elements) and somely makes at textural other assembly of operation simplification and dependability that can provide.
At first, the catalysis sensitive element is made with catalyzer and thermal detector.
Fig. 3 shows the sketch map of analysing and observe of catalysis sensitive element (311) in the scope of the invention and reference elements (320).This modification form of device of the present invention adopts a kind of heat-insulating carrier or substrate (the 310 and 322) part as element.Probe or probe that this class carrier can be used separately as each element to be inserted in the air flow.Substrate should be a kind ofly the heat insulation carrier of sufficient mechanical strength to be arranged with catalyzer in the support flow moving air flow and thermal detector.Substrate (310) can be pottery or be coated in high Cen soil, aluminium oxide, silicon dioxide one aluminium oxide and the silicon dioxide that the pottery on the metallic carrier, suitable stupalith comprise sintering.General stupalith as catalyst support also is suitable for doing substrate, as long as the circulation change of temperature when having necessary physical strength and withstanding device and switch on and off is withstood normal physical shock between very long time of spending under the predetermined operating temperature and installation and on-stream period.Because catalysis material (312) is adhered on the ceramic substrate (310) the various practices, above-mentioned stupalith also is suitable for.
Thermometric device (314) can be that any can generation when device temperature changes can be surveyed the device that physical quantity (for example voltage or resistance) changes.Bimetallic thermocouple, particularly nichrome alumino-nickel couple, available known ready-made ceramic bond bonds on the substrate (310).The sensitivity of the thermometric device of selecting for use must be mated with the sensitivity of last resulting analyzer.For example, as thumb rule, thermopair can only be accurate to ± 1F °.Measuring low content SO
2When (being lower than 60ppm), just need sensitiveer thermometric device) such as the RTD(resistive thermal detector such as content.Thermal detector surface away from carrier should not have barrier layer for gases basically, makes tested gas contact catalysis surface (312).The optional thermistor that adequate sensitivity is arranged in the proper temperature scope of selecting of thermometric device.As long as selected ceramic substrate (310), the thermometric device does not just need discrete, does not need to be installed on the substrate and can directly make of known technology at ceramic surface.Referring to for example US 4,129, people such as 848(Franc) shown on ceramic substrate, prepare the method for thermistor.Make the measurement with the corresponding variable physical amount of device temperature become possibility from the lead-in wire (316) of thermometric device.The thermometric device can be placed in the substrate; Substrate can be made by thermocouple sheath.
At last, Catalytic Layer (312) can be done quite thinly with reaction heat guiding thermometric device (314) that impels the surface generation and the caloic that reduces the catalysis sensitive element.
The appropriate catalyst of following reaction has many kinds:
SO
2+1/2O
2→SO
3
Preferred catalyzer comprises VIII family noble metal catalyst, such as platinum, palladium and rhodium and their potpourri; V B family metal oxide is such as the oxide of vanadium; With the group VIII metal oxide, such as iron oxide.
Owing to objectively need to make the catalyst layer of minimum thickness, availablely a kind ofly contain few or do not have the liquid of solid constituent to come coated catalysts or catalyst precarsor.For example, the catalyst precarsor of catalytic metal a kind of dissolving or chelating, for example available a kind of acetylacetonate compound, (for example dimethyl formamide) floods ceramic surface in suitable solvent.Coating through dipping, spray into washcoat or after dipping, element can be in oxygen or air roasting to generate active catalyst.
A kind of specially suitable be the method for catalyst-coated on the catalysis sensitive element to be coated on the component carrier by means of the slaine that utilizes suitable catalytic metal.This salt is nitrate, sulfuric acid or chloride preferably, with the form of saturated aqueous solution apply so that effectively catalytic metal on element, reach maximal value.
Use to wish to make by catalytic surface (312) at some and reduce to minimum to the radiation of other colder part of reference elements or sensor groups and the thermal loss of convection current with baffle plate or every cover (318).
Secondly, reference elements (320) in design can be similar with catalysis element (311), just removes the protective seam (326) that catalyst layer also can at random add the thermometric device.
Reference elements (320) is used to provide a kind of comparative temperature survey, and this temperature is the nonreactive gas temperature that flows through reference elements or catalysis sensitive element.In fact reference elements can be a kind of optional definite value element, as long as the gas that the catalysis sensitive element " detects " and the temperature of environment can be controlled subtly.For example, make environment temperature come down in controlled rather than the adiabatic environment that records or replace the reference elements of measure local temperature with a voltage source (when the thermometric device is thermopair) as the catalysis sensitive element being placed on one with regard to an available precision resistor (when the thermometric device of catalysis sensitive element is RTD or thermistor).
Two elements do not adopt electric current to flow through sensitive element directly to heat, i.e. the mode of resistance heated.
In Fig. 3, reference elements (320) is made with mechanical carrier, thermometric device and a kind of protective seam arbitrarily.Modification form of the present invention shown in Fig. 3 is included in mechanical carrier (322) similar to carrier (310) on the function, thermometric device (324) is installed on the carrier, perhaps as the situation of catalysis element, can integrally make with the ceramic surface of carrier, carrier at this moment is ceramic certainly.Protective finish (326) is arbitrarily, and this depends on the corrosivity of tested air-flow and the reactivity of used thermometric device.
Protective seam arbitrarily (326) on the reference elements can be made by aluminium oxide, silicon dioxide, epoxy resin, carbon or other Heat Conduction Material.This coating is that protection thermometric device (324) is avoided in the air-flow as SO
2, SO
3, NO
2, H
2The corrosion of compositions such as O, but should not disturb the task of reference elements measure local temperature.In addition, protective finish (326) can improve the caloic coupling of reference elements (320) and catalysis sensitive element (311).If catalysis sensitive element (311) has been coated with catalyzer and has not been coated with on the reference elements, the caloic of comparing reference elements so with the catalysis sensitive element will be much smaller, and is more faster than catalysis sensitive element to the response of flowing gas temperature variation on every side.This response difference can be given SO undoubtedly
2Measurement bring error.And the basal area that protective finish (326) provides for reference elements (320) is more similar with surface area to the basal area that catalysis sensitive element (311) provides with surface area.The similarity of area causes similar convection heat transfer load.
Reference elements (320) is design so preferably, and the structural form of gas is similar in the time of crossing catalysis sensitive element (311) to air flow stream when crossing this element with convenient gas stream.In other words, the gas dynamics shape of two elements should be similar.Two elements should be placed in the typical flow region of phase Sihe of tested gas ideally, and promptly two elements can be placed in the turbulent area of gas, so that tested gas is representational equally.For example, should avoid an element is placed on the non-turbulent flow district and another element is placed on turbulent area, because this causes the inequality that enters temperature of air-flow to be measured.
Two elements should optimization make the thermal loss of convection current and radiation reduce to minimum on shape and structured material.Carrier material should be selected like this, so that the reaction heat on the catalyst coatings (312) of catalysis sensitive element (311) is retained on the thermometric device (314).Element is by the actual miniaturization of can trying one's best, and making might be to temperature and SO
2Content is made quick response.Adopt miniaturized component generally can also reduce the radiation heat loss of environment towards periphery.Two elements should have similar caloic and should have similar heat transfer property as much as possible.Catalysis sensitive element and reference elements not necessarily must be structural forms shown in Figure 3.Other is revised form and also is suitable for.
Catalytic oxidation pre-converter shown in Figure 1, catalysis sensitive element and reference elements are preferably in tested specific gas flow rate and its temperature is used in the sensor groups of meticulous control.
Come the relatively signal of each the thermometric device in catalysis element and reference elements with known circuit (Wheatstone bridge, differentiating amplifier etc.), through calibrating the SO that measures in the air-flow
2Content is because the linearity of apparatus of the present invention just can directly be measured SO through after this calibration
2Concentration.Catalytic oxidation pre-converter and SO
2Sensor groups can form shown in Figure 4 be assembled.
The gas that the quilt of the burning gas chimney that comes the self-discharging burning gas is sampled sucks by injection port (410), sample gas is by the heat transfer block (412) of labyrinth type heat exchanging section (414) inflow Controllable Temperature, and this piece has some functions but mainly provides an adiabatic thermal source makes the sample gas mixture bring up to operating temperature range.This block can contain one or more heating elements (416).One is revised form is that a kind of this block that keeps is in piece well heater outward predetermined temperature under.In any case, it can be the labyrinth heat exchanger surface shown in Fig. 4 that the sample gas mixture is flowed through, be heated to working temperature after, gas is by the catalytic oxidation pre-converter element (418) of above-mentioned Fig. 2 form.The working temperature of catalytic oxidation pre-converter element (418) wishes it is 400 ℃-500 ℃, preferably 425 ℃-475 ℃.The oxidation pre-converter can be made such as pottery, ceramic coated metal or metallic carrier with the material of routine.The stupalith that is suitable for doing substrate comprises aluminium oxide, silicon dioxide, the high Cen soil of sintering, silica-alumina etc.Other refractory metal oxide also is fit to.
The catalytic metal that is suitable for the oxidation pre-converter is known above-mentioned.
Oxidizable components in the tested gas is then oxidized in oxidation pre-converter (418), flows out to the second Controllable Temperature heat transfer block (420).Available barrier liner (422) is separated first heat transfer block (412) and second heat transfer block (420).The gas temperature of the catalyzer of oxidation pre-converter like this, (418) can break away from downstream temperature and be controlled independently.
The temperature of second heat transfer block (420) can be controlled with one or more heating element (424).Gas stream is crossed labyrinth heat interchanger path (426) and is reached above-listed SO shown in Figure 3
2Sensor groups (428), SO
2The element group contains catalysis sensitive element (430) and reference elements (432), is used for electronic processing from the signal lead (434) of thermometric device in the element group and produces SO
2The signal of content shows.So far, tested air-flow leaves heat transfer block (420).Sample airshed by controlled heat transfer block (412 and 420) can be controlled by operation valve (436) and vacuum pump (435).Operation valve (436) can be certain other suitable flow control device, as orifice flowmeter etc.Vacuum pump (438) can be other suitable evacuator, such as thrower, aspirator or thermal siphon etc.
The gas sample can be discharged then.
Concise for what discuss, it is conspicuous SO that this instructions has omitted the common staff in this area
2The non-main part of sensor.For example, line temperature from sample gas to sensor that supply with should be kept above dew point, with prevent condensation problem and thereby the device precision that causes reduce.Equally, anti-installation filter is removed the particle that suspends in the gas before gas reaches the sensor group.
SO
2Detection method
This method is followed above-mentioned SO very nearly
2Detecting device make usage.
Containing SO
2The sample air-flow be heated to the suitable temperature of the catalytic oxidation pre-converter of the above-mentioned type.Oxidizable components (SO in the air-flow
2Except) basically by the excess of oxygen oxidation in the sample air-flow.
And then the SO that contains that leaves the catalytic oxidation pre-converter
2With oxidized component (NO
2, CO
2Deng) be heated to suitable temperature after, deliver to SO
2Sensor groups (top also describe in detail), catalysis material can be selected from above-mentioned those materials.Catalyzer can make SO
2Generate SO with oxygenant generation themopositive reaction
3, cause the catalysis element temperature to raise.In view of some O are arranged in the catalysis element
2The O of air-flow is wished in sensitivity
2Concentration is suitably stable, produces the output signal surveyed that roughly is directly proportional with temperature rise by the thermometric device, measures the temperature that increases.Thermosensitive device can be a kind of the have essential sensitivity and thermopair of temperature range.As adopt thermopair in thermosensitive device, the output signal of device will be a voltage.When adopting other device, for example RTD or thermistor, the resistance of device will change with temperature.Apply suitable voltage to the thermometric device then, just can detect last resulting resistance.Thermometric device according to the optics principle of work also is known.A kind of suitable light thermal detector is seen US 4,861,979.
Gas also can pass through a reference elements of being made up of the thermosensitive device of catalysis sensitive element homotype.The output signal that thermosensitive device provides with from the output signal of catalysis element relatively, just can determine the difference of element output signal.Can calculate SO from the output signal difference of two elements
2Content.
Embodiment
Sensor and detection method have been described above in detail.The following example explanation each side aspect of the present invention, but be not to be used for scope disclosed in this invention is made restriction.
Embodiment 1
Present embodiment shows the monolithic type catalytic oxidation pre-converter Preparation of catalysts method of the present invention that is applicable to.
Have the monoblock trichroite in 400 holes (Corning company) per square inch and cut into 10 holes * 10 holes, whole 1.5 inches long some squares.This square sample is washed acetone earlier again and is washed, then in air with 450 ℃ of roastings 1 hour.The section in hole is square, passes sample always.
Not really fine and close in view of violet green grass or young crops, surface area is less, so will be with the alumina coated of high area.The alumina sol method for making that applies usefulness is aluminium oxide (Versal G H), water, HNO
3About 2 days of the potpourri ball milling of (pH ≌ 3.0).Earlier the trichroite sample is soaked with alumina sol, use N again
2Air-flow is blown away excessive solution, again cated carrier drying and roasting.The alumina sol coating makes carrier increase weight about 7.0%.
Then calcinated support is immersed in palladium bichloride (PdCl
2- 4) in the Y solution, using H
2Sample contained Pd about 0.25% after S handled (with fixing palladium), drying and roasting.
Present embodiment shows the packed bed type catalytic oxidation pre-converter Preparation of catalysts method of the present invention that is applicable to.
The spherical commodity gamma-aluminium oxide carriers of a kind of 1/8 diameter (Rhone-Polenc SCS100) are pulverized, and particle diameter reaches and meets the 16-32 order that catalytic bed requires.Levigate aluminium oxide carries out hydro-thermal method with air and 10% water vapour down at 620 ℃ to be handled so that the surface-stable of aluminium oxide.
The aluminium oxide of above-mentioned processing is with containing Pt/Ph=0.67(weight) platinum-rhodium solution soak clearly.Final catalyzer contains about 0.35% noble metal.
Catalyst loading is made it fix in position with filter screen and glass wool in stainless-steel tube (1.5 English * 0.5 inch diameter).
Embodiment 3
Present embodiment shows and is applicable to the SO of employing of the present invention RTD as the thermometric device
2The method for making of catalysis sensitive element.
This catalysis sensitive element and reference elements adopt a kind of about 1/4 inch bonding potsherd of the usefulness sheet for preparing 100 ohm RTD, and two above-mentioned RTD sheets are suspended in the ceramic pipe of one 1/4 inch external diameter (OD).Then the RTD sheet is applied with the alumina solution that uses among the embodiment 1.
Then a sheet is immersed in the platinum acid chloride solution that contains 0.16g Pt/g solution once more.Dipping operation and drying process hocket.At last at H
2Platinum is fixed, and sensitive element was 500 ℃ of following roastings 1.5 hours.
Two sheets (one is that catalysis sheet one is the reference sheet) are installed on the insulating carrier and make at SO
2Can stand upright securely in the air flow of sensor.
Embodiment 4
Present embodiment shows SO of the present invention
2Sensor groups contains various components (such as CO, SO to some
2With NO etc.) gas the time SO of the present invention
2The work of sensor groups.
Total flow by sensor groups gas is about 100CSCCm.The temperature of pre-converter and sensor all is 450 ℃.
Catalyzer in the oxidation pre-converter is a kind of Pt-Rh material, prepared material in the embodiment 2.That describes among sensitive element and the embodiment 3 is similar, and just component carrier is the stainless steel of ceramic coated.
* contain 1.2%H
2O and 9.86%O
2
The above results is shown among Fig. 5.Must make clear, the existence of oxidizable components CO and NO does not influence downstream SO
2The work of sensor.
The present invention has made open report with explanation and embodiment.These embodiment should not limit the invention in this claim scope by any way nothing but embodiment.In addition, for those of ordinary skills, change and equivalent are conspicuous, and also can in kind measure SO
2, but still be in the spirit and scope of claims of the present invention.
Claims (24)
1, SO in a kind of measurement air flow
2The device of concentration, this device comprises:
A. an oxidizable components that is suitable for the oxidation air flow (but is not SO
2) oxidation catalyst, before this catalyzer is placed at it and the catalysis sensitive element contacts, with those the oxidable components in the oxidation air flow;
B. catalysis sensitive element, this element comprises that a kind of being suitable for makes SO having under the situation of oxygen
2Be oxidized to SO
3Catalyzer and a kind of thermometric device; Catalyzer is placed so that catalyzer contacts with air flow like this with the thermometric device in this element, and SO
2The temperature ascending amount of the thermometric device that the heat that oxidation produces causes basically with air flow in SO
2Concentration is directly proportional;
C. reference elements that is suitable for detecting near the air flow environment temperature of catalysis sensitive element;
D. one kind is suitable for before by the catalysis sensitive element the flowing gas temperature controller of the adjustment of air flow to working temperature.
2, the device of claim 1, wherein the thermometric device of this catalysis sensitive element is resistance temperature detector (RTD).
3, the device of claim 1, wherein the thermometric device of this catalysis sensitive element is a thermistor.
4, the device of claim 1, wherein the thermometric device of this catalysis sensitive element is a thermopair.
5, the device of claim 1, wherein oxidation catalyst is selected from Ru, Rh, Pd, Os, Ir, and composition thereof; Group VIB metal or its oxide; Or the oxide of group VIII metal.
6, the device of claim 5, wherein oxidation catalyst comprises rhodium, palladium, or its potpourri.
7, the device of claim 1, wherein the catalyzer on the catalysis sensitive element comprises a kind of metal that is selected from VIII family noble metal.
8, the device of claim 7, wherein catalyzer or catalysis sensitive element comprise a kind of platinum that is selected from, rhodium, the metal of palladium, or its potpourri.
9, the device of claim 1, wherein reference elements comprises the RTD of contiguous catalysis sensitive element.
10, the device of claim 1, wherein reference elements comprises the thermistor of contiguous catalysis sensitive element.
11, the device of claim 1, wherein reference elements comprises the thermopair of contiguous catalysis sensitive element.
12, the device of claim 1, wherein reference elements is a resistor.
13, the device of claim 1, wherein the air flow temperature controller comprises heat interchanger.
14, the device of claim 1 also comprises in addition and is suitable for entering the well heater of gas temperature with control before oxidation catalyst contacts.
15, the device of claim 14, wherein well heater is a kind of heat interchanger.
16, a kind of measurement contains SO
2With SO in the air flow of oxidizable components
2Method, this method comprises the following steps:
A. air flow is led to that a kind of to be suitable in that oxidation oxidizable components under the situation of oxygen is arranged (but be not SO
2) oxidation catalyst on;
B. the adjustment to of an air flow suitable working temperature;
C. air-flow is led on the catalysis sensitive element, this element comprises a kind of SO that makes when being suitable under the situation of oxygen is arranged contacting with air flow
2Be oxidized to SO
3Catalyzer and thermometric device, catalyzer and thermometric device are placed so that SO like this
2The temperature ascending amount of the thermometric device that the heat that oxidation produces causes basically with flowing gas in SO
2Concentration is directly proportional, and wherein the thermometric device provides a kind of surveyed output signal relevant with temperature rise.
17, the method for claim 16, wherein air flow also leads on the reference elements of contiguous catalysis sensitive element, this reference elements comprise produce with the output signal surveyed of the temperature correlation of mixed airflow and with the output signal the surveyed homotype of catalysis sensitive element.
18, the method for claim 16, wherein can survey output signal is voltage.
19, the method for claim 17, wherein can survey output signal is resistance.
20, the method for claim 16, wherein oxidation catalyst is selected from Ru, Rh, Pd, Os, Ir, and composition thereof; Group VIB metal or its oxide; The oxide of base group VIII metal.
21, the method for claim 20, wherein catalyzer comprises rhodium, palladium, or its potpourri.
22, the method for claim 16, wherein the catalysis sensitive element comprises a kind of metal that is selected from VIII family noble metal.
23, the method for claim 22, wherein the catalysis sensitive element comprises a kind of platinum, rhodium of being selected from, the metal of palladium, and composition thereof.
24, the method for claim 16, wherein oxidizable components comprises one or more CO, H
2, NO
xAmine, and NH
3
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 91109616 CN1071509A (en) | 1990-08-17 | 1991-10-09 | SO 2 sensor and process for detecting SO 2 |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/569,066 US5338515A (en) | 1990-08-17 | 1990-08-17 | SO2 sensor |
| CN 91109616 CN1071509A (en) | 1990-08-17 | 1991-10-09 | SO 2 sensor and process for detecting SO 2 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1071509A true CN1071509A (en) | 1993-04-28 |
Family
ID=25742715
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 91109616 Pending CN1071509A (en) | 1990-08-17 | 1991-10-09 | SO 2 sensor and process for detecting SO 2 |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1071509A (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102438943A (en) * | 2009-05-11 | 2012-05-02 | 赛默飞世尔科技有限公司 | Generation of sulfur trioxide and sulfuric acid |
| CN104569038A (en) * | 2013-10-11 | 2015-04-29 | 上海锦宜仪器有限公司 | Device and method for combustible gas detection |
| CN105092661A (en) * | 2015-09-08 | 2015-11-25 | 无锡百灵传感技术有限公司 | Catalytic combustion-type gas sensor |
| CN106018704A (en) * | 2016-07-07 | 2016-10-12 | 洛阳高昌机电科技有限公司 | Nitrogen trifluoride leakage concentration detection device |
| CN108187480A (en) * | 2018-01-23 | 2018-06-22 | 青岛双瑞海洋环境工程股份有限公司 | Marine exhaust desulphurization system |
| CN110045056A (en) * | 2019-05-16 | 2019-07-23 | 北京联合大学 | A kind of cross sensitivity material of carbon monoxide and sulfur dioxide |
| CN110770581A (en) * | 2017-07-03 | 2020-02-07 | 林德股份公司 | Method and system for analyzing fuel gas |
-
1991
- 1991-10-09 CN CN 91109616 patent/CN1071509A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102438943A (en) * | 2009-05-11 | 2012-05-02 | 赛默飞世尔科技有限公司 | Generation of sulfur trioxide and sulfuric acid |
| CN102438943B (en) * | 2009-05-11 | 2015-06-17 | 赛默飞世尔科技有限公司 | Generation of sulfur trioxide and sulfuric acid |
| CN104569038A (en) * | 2013-10-11 | 2015-04-29 | 上海锦宜仪器有限公司 | Device and method for combustible gas detection |
| CN105092661A (en) * | 2015-09-08 | 2015-11-25 | 无锡百灵传感技术有限公司 | Catalytic combustion-type gas sensor |
| CN106018704A (en) * | 2016-07-07 | 2016-10-12 | 洛阳高昌机电科技有限公司 | Nitrogen trifluoride leakage concentration detection device |
| CN110770581A (en) * | 2017-07-03 | 2020-02-07 | 林德股份公司 | Method and system for analyzing fuel gas |
| CN108187480A (en) * | 2018-01-23 | 2018-06-22 | 青岛双瑞海洋环境工程股份有限公司 | Marine exhaust desulphurization system |
| CN110045056A (en) * | 2019-05-16 | 2019-07-23 | 北京联合大学 | A kind of cross sensitivity material of carbon monoxide and sulfur dioxide |
| CN110045056B (en) * | 2019-05-16 | 2021-07-09 | 北京联合大学 | Cross sensitive material of carbon monoxide and sulfur dioxide |
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