JPH01250746A - Analyzing apparatus of air for burning - Google Patents

Abstract

PURPOSE:To detect the quantity of supply of air for burning which is supplied to each burner, by providing a converting means for converting the concentration of wet O2 of the air for burning into the concentration of dry O2. CONSTITUTION:An O2 concentration computing unit 121 is connected to an O2 sensor 52 measuring the concentration of wet O2 of air for burning, and it controls the sensor 52 while applying prescribed correction to a voltage signal corresponding to a measured concentration of wet O2. A Wet/Dry converter 125, which is connected to the computing unit 121, computes a gas component in a burning gas and the mixture ratio thereof from the concentration of wet O2 in the air for burning, the concentration of wet O2 in a burnt exhaust gas and burning composition, and converts the concentration of wet O2 of the air for burning into the concentration of dry O2. A flow velocity/ temperature compensation computing unit 131 is connected to a flow velocity sensor 71 measuring the flow velocity of the air for burning and applies temperature compensation to a measured value corresponding to the flow velocity obtained. By an output of the concentration of O2 (or the flow of the air) obtained from the sensor 52 (or 71) through each circuit, according to this constitution, the quantity of supply of the air for burning can be adjusted by applying a feed forward control to a block member or the like, and NOx in a burning gas can be lessened by conducting appropriate multi-stage burning.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a combustion engine that measures the amount of combustion air supplied to the combustion chamber of an industrial furnace in order to control the combustion state of an industrial furnace such as a boiler. The present invention relates to a commercial air analysis device.

(Conventional technology) This year, NO in combustion exhaust gas was
In order to reduce All of these methods reduce the combustion temperature, reduce the air supply amount, or combine these methods, and suppress so-called thermal NO8 that tends to occur in conditions of high temperature and excessive air supply. It is something to do. In addition, combustion under a low oxygen partial pressure is considered to be desirable as a method for reducing so-called fuel NO11, which is generated due to nitrogen compounds contained in fuel. In order to reduce these thermal NO and fuel N roy, JP-A-61-1903 discloses that burners are arranged in stages in the furnace, and first, in the lower stage, the air ratio is set to 0.7 or less, that is, the Strong reductive combustion is performed in an extreme fuel excess state where the average oxygen concentration in the total air amount is 17% or less, and then in the middle stage, the air supply amount (air ratio 0.8 to 0
．． 9), and finally, in the upper stage, the insufficient amount of air is supplied, and combustion is performed using the theoretical amount that should be consumed for complete combustion of the unburned matter. In order to perform the multistage combustion described in the above publication in a furnace, it is necessary to appropriately supply combustion air to each burner.

In conventional combustion equipment, combustion air first passes through a common duct, then is introduced into individual burner combustion ducts, and is supplied to each burner arranged near the opening in the duct furnace. To check the condition of combustion air,
An oxygen sensor was placed in the common duct and the oxygen concentration was measured only at its representative points.

(Problems to be Solved by the Invention) However, if the representative point is measured within the common duct, it is not possible to perform multi-stage combustion with an appropriate air supply amount as described above. combustion management)
Therefore, NO in the combustion exhaust gas could not be effectively reduced.

An object of the present invention is to provide a combustion air analyzer capable of detecting the amount of combustion air supplied to each burner.

(Means for Solving the Problems) The combustion air analyzer of the present invention is a combustion air analyzer that analyzes the amount of combustion air supplied to each burner of an industrial furnace of exhaust gas recirculation type. an oxygen sensor that measures the moist oxygen concentration of combustion air; and an oxygen concentration calculator connected to the oxygen sensor that controls the oxygen sensor and performs a predetermined correction on a voltage signal corresponding to the measured moist oxygen concentration. , which is connected to the oxygen concentration calculator, calculates the gas components and mixture ratio in the combustion exhaust gas from the moist oxygen concentration in the combustion air, the moist oxygen concentration in the combustion exhaust gas, and the fuel composition, and calculates the combustion air from these data. a conversion means for converting a wet oxygen concentration into a dry oxygen concentration; a flow rate sensor for measuring the flow rate of combustion air; and a means connected to the flow rate sensor for temperature compensating a measured value corresponding to the flow rate obtained from the flow rate sensor. and converting means connected to the means for converting into a predetermined volumetric flow rate.

(Function) According to the present invention, of the amount of combustion air sent to each burner, the one that is related to the combustion of the burner is the dry oxygen concentration;
This is based on the fact that the volumetric flow rate of oxygen is.

By the way, in the present invention, "wet" oxygen concentration means the oxygen concentration in a state where the moisture (820) contained in the gas to be measured is not removed, and "dry" oxygen concentration, contrary to the above, It means the oxygen concentration in a state where most of the oxygen is removed.

In the exhaust gas recirculation method, a portion of the exhaust gas containing moisture is mixed with the combustion air, so the humid gas is measured with an oxygen sensor, and as a result, the humid oxygen concentration is obtained.

However, since actual control is performed using dry oxygen concentration, this wet oxygen concentration is converted into dry oxygen concentration using a conversion means. Next, the flow rate sensor obtains a signal corresponding to the flow rate, which is converted into a volumetric flow rate of combustion air by a volumetric flow rate conversion means related to actual combustion in the burner.

(Example) Embodiments of the present invention will be described based on the drawings.

Figure 1 shows a schematic diagram of an industrial combustion furnace. 1 is the furnace, 3
5 shows a separate duct that introduces combustion air into the furnace 1, supplies combustion air to each burner, and is partitioned into each chamber, and 5 shows a valve member that limits the flow rate of the combustion air flowing into the separate duct 3. . Furnace 1 has separate duct 3
Four burners protruding from the furnace 1 into the furnace 1 are arranged in each stage to perform two functions. The lower burner 7 is a reduction burner, and the upper burner 9 is a main burner. NO ports 11 are formed in the upper furnace walls of these burners, and are configured to perform two-stage combustion.

Further, a common duct 13 is provided to supply combustion air to the separate duct 3.
For example, air with an oxygen concentration of 20.6% sent from the near blower 15 via the air heater 17 is mixed with a portion of the combustion exhaust gas with an oxygen concentration of 2%, sent through the exhaust gas recirculation path 19. 17% combustion air is provided. This is commonly referred to as exhaust gas recirculation. Further, a combustion air analyzer 21 is inserted into each separate duct 3 at a position between each burner and each valve member by penetrating the pipe wall of each duct.

Next, a specific embodiment of the combustion air analyzer according to the present invention will be described below with reference to FIG.

In Figure 2, combustion air (hereinafter referred to as “
"Gas to be measured." ) and a flow rate sensor probe 33 that also measures the flow rate of the gas to be measured are inserted into, for example, an opening 37 formed in the wall 35 of each separate duct 3, These probes 31 and 33 are integrated at their base end portions, that is, at the terminal box 39, and a mounting flange 41 formed on the terminal box 39 and a wall side flange 4 provided on the wall portion 35.
3 are screwed together to maintain the inserted state of the probes 31 and 33.

Probe 3 for the oxygen sensor, as shown in detail in FIG.
1, an oxygen sensor 45 having a cylindrical shape with a bottom, for example, is screwed onto the probe jig 53 of the probe 31 with a screw or the like via a sensor clasp 47 which is airtightly fixed by, for example, a boundary method. ing.

Further, around the oxygen sensor 45 mounted in this manner, a heater holder 51 containing a built-in heater 49 (these constitute a heater unit) is fitted into the sensor fastener 47 from the inside, and is integrally bonded with cement. is fixed. Therefore, the oxygen sensor 45, the sensor fastener 47, the heater 49, and the heater holder 51 (i.e., the heater unit) are integrated into the sensor unit 5.
2.

On the side of the oxygen sensor 45 exposed to the gas to be measured,
In order to prevent the inflow of dust etc., the probe jig 53 has
The filter holder 55 is fitted, and this filter holder 55 is
A filter 57 is fitted into the opening provided in the opening, and the filter 57 is fixed by screwing a pressing jig 59 having an opening in the center. By the way, a stepped portion is provided on the outer periphery of the outer corner of the filter holder 55 on the side that abuts against the sensor clasp 47.
A gas passage 60 is formed between the stepped portion and the probe jig 53. Furthermore, the calibration gas introduction pipe 61 of this filter holder 55
A gas inlet/outlet 69 leading to the internal space 67 is provided to coincide with the opening 63 on the outlet side of the filter holder 5.
A gas outlet 69 is provided at a position of the probe jig 53 that is substantially opposite to the opposite side of the gas inlet/outlet 69 of the probe jig 53. Therefore, a communication space is formed from the internal space 67 to the gas space to be measured. Therefore, the gas to be measured or the calibration gas introduced into the internal space 67 can be quickly discharged to the outside.

For the oxygen sensor having such a predetermined shape, the gas to be measured passes through the filter 57 and is introduced into the internal space 67, and a portion of the gas is replaced by gas diffusion and thermal convection due to the difference in concentration of the gas to be measured. and reaches the measurement electrode provided deep inside the oxygen sensor 45. Other gases to be measured are discharged to the outside through a gas inlet/outlet 65, a gas passage 60, and a gas outlet 69, as shown in the figure. Therefore, since this oxygen sensor 45 is provided with a gas flow path from the inflow to the outflow of the gas to be measured, the gas to be measured is quickly introduced into the internal space, and moreover, almost all of the gas to be measured is introduced into the internal space. By performing gas replacement while maintaining an equilibrium state, the responsiveness of the oxygen sensor 45 can be maintained high and protection against thermal shock can be provided at the same time.

Similarly, when introducing a calibration gas to calibrate the output of the oxygen sensor, the calibration gas first passes through the calibration gas introduction tube 61 arranged outside the probe 31, passes through the opening 63 and the gas inlet/outlet 65. The internal space 67 is filled. At this time, since the internal space 67 is in a positive pressure state, the inflow of the gas to be measured is blocked. A part of the calibration gas filling the internal space 67 reaches the deep part of the oxygen sensor 45 after being replaced by gas diffusion and gas convection due to the difference in gas concentration.
Contact the measuring electrode. Other calibration gases are used in the internal space 6.
7 is discharged from the gas outlet 69 via the gas passage 60 when the pressure becomes negative with respect to the pressure of the gas atmosphere to be measured.

Therefore, when the calibration gas is introduced, the measurement electrode of the oxygen sensor 45 is not directly hit by the calibration gas, that is, the measurement electrode is not rapidly cooled.
Furthermore, there is little temperature change in the oxygen sensor between the measurement of the gas to be measured and the introduction of the calibration gas, making highly accurate calibration possible.

On the other hand, on the tip side of the probe 33, as shown in FIG. 4, a constant temperature deformable hot wire type flow rate sensor (hereinafter abbreviated as "flow rate sensor") 71 for measuring the flow rate of the gas to be measured is provided. This flow rate sensor 71 has an air temperature element 73 for measuring the flow rate and an air temperature element 75 for temperature compensation, and also has a mesh filter in a portion of the probe 33 corresponding to the flow rate sensor 71 72 is provided,
The gas to be measured is introduced while preventing dust and the like from flowing into the probe 33. By the way, to explain the principle of the air temperature element, when the sensor part is placed in the flow of the gas to be measured and is heated by passing a current through the resistance wire as the sensor part, when the gas to be measured hits the sensor part, the resistance wire is cooled down. The temperature will drop. The amount of heat taken away at this time is related to the flow velocity, and the relationship between the flow velocity U (m/s) and the amount of heat dissipated H at this time is expressed by King's equation.

H=(a+b-U'')(T-Ta)(
1) Here, H: amount of heat dissipated a, b, m: constant determined by the fluid etc. U: flow rate T: heated object (i.e. temperature of the hot wire) Ta: temperature of the surrounding fluid.

However, in the constant temperature hot wire flow rate sensor, the same amount of heat as the amount of heat dissipated is supplied by current, the amount of heat dissipated and the amount of supplied heat are always kept constant, and the resistance temperature is kept constant. Therefore, the flow rate can be determined by measuring the amount of heat supplied. Therefore, if a bridge circuit is constructed with a hot wire on one side, and the resistance of this hot wire is RH1, and the current flowing through the hot wire is to, then the amount of heat Q supplied is as follows: Q=1. ' ・Ra((2) At this time, the amount of heat dissipated H and the amount of heat supplied Q are balanced, so if we set H=Q, 1.2・R,= (a+b-U ``''') (T-Ta
) (3) Therefore, 1. - If the T relationship and Ta are known, the flow velocity U can be determined by measuring the current value ■□.
can be found. However, in order to find Ta,
The temperature of the gas to be measured is measured using the air temperature element 75.

The feature of this hot wire type air temperature element 73 is that it is not affected by fluid pressure, viscosity, etc. compared to other differential pressure type flow rate measurement and Karman vortex flow rate measurement, and it is not affected by fluid pressure, viscosity, etc. when flowing into an industrial furnace such as a boiler. This is particularly effective in the case of combustion air, since the draft pressure is high. Further, this type is convenient because it can be made smaller and lighter in terms of structure.

As described above, the probe 31 having the oxygen sensor 45 and the probe 33 having the flow rate sensor 71 are integrated at their proximal ends, and are placed close to each other at the distal ends of the probes so as not to interfere with each other's operations. Because it is placed
The oxygen concentration in the burner combustion air and the combustion air flow rate (ie, the oxygen flow rate) can be continuously measured at approximately the same installation point.

Next, as a modification of the mounting structure of the oxygen sensor 45 to the tip of the probe 31, as shown in the cross-sectional view of the main part in FIG. A metal cylindrical cell support tube 85 is inserted, the cell support tube 85 having an outwardly facing flange 87 and a frusto-conical portion 89.
An oxygen sensor 91 having a cylindrical shape with a bottom is inserted into an opening 90 provided in the
is fitted with its bottom facing the flange side.

Furthermore, a cylindrical measured gas introduction pipe 95 having an outward flange 93 is inserted into the sensor support pipe 85 from the outside,
The right sensor support tube 85 and the gas introduction tube 95 to be measured can be fixed to the probe 31 by screwing them to the inward flange 83 with bolts or the like in the areas of their outward flanges 87 and 93. By the way, a calibration gas introduction pipe 84 is provided that passes through the inward flange 83 and the outward flange 87, and the calibration gas is introduced into the cell support pipe 8.
5 and the gas to be measured is fed to the oxygen sensor 91 through a gap formed between the gas inlet tube 95 and the gas to be measured. In addition,
A porous ceramic filter 99 for dust removal is adhered to the flange-side port 97 of the gas inlet pipe 95 using alumina cement or the like.

Inside the probe 31, a stainless steel support fitting 101 inserted from the proximal end of the probe extends concentrically with the probe 31, and the reference gas is diffused between the support fitting 101 and the probe 31. We are trying to get an influx of people. Further, a temperature detection means 103 for measuring the temperature near the oxygen sensor, such as a thermocouple, is attached to the support fitting 101 by a mounting fitting 105. Furthermore, a heater support tube 115 having an annular heater 113 is connected to the tip of the support fitting 101 via a joining flange 109 . An electrical contact 117 is provided on the inner wall of the heater support tube 115 via an insulator 118, and the contact 117 can be composed of a contact terminal and a concave ring that holds the contact terminal. . With such a configuration, when the oxygen sensor is inserted into the contactor 117, it can be electrically connected to an electrode provided on a predetermined outer surface of the oxygen sensor.

The device configured in this manner has the gas to be measured inlet pipe 95 and the sensor support pipe 8 when all its parts are attached.
A cylindrical gap is formed between the sensor support tube 85 and the gas outlet of the calibration gas introduction tube 84 that extends into the gap through the sensor support tube 85. Gas is blown out from the outer periphery of the base toward the tip. Furthermore, since this gap itself has a large surface area, heat is efficiently transferred from the heater 113 located near the gap across the tube walls of the cell support tube 85 and the heater support tube 115 to the calibration gas. Therefore, it is possible to reduce the rapid cooling of the detection cell, that is, the disturbance in temperature control caused by spraying the calibration gas having a large temperature difference with the gas to be measured onto the detection cell.

Next, a processing circuit for one measurement value in the combustion air analyzer 21 will be explained.

In the block diagram shown in FIG.
The output voltage corresponding to the oxygen concentration of the combustion air is connected to the oxygen sensor 45 from the oxygen sensor 45.
1, where it controls the oxygen sensor 45, linearizes the relationship between the output voltage and oxygen concentration, and calibrates it.
Various processes for pressure correction are performed. 0□ Arithmetic unit 121
The output voltage processed in is supplied to the Wet/Dry converter 125 connected to the 02 computing unit 121, which converts the measured value of wet oxygen concentration containing moisture into the measured value of dry oxygen concentration without moisture. Conversion processing is performed. This measured value of dry air is output to a control device (not shown), and the control device performs feedforward control based on this value. The data necessary for the calculation of this Wet/Dry converter 125 is sent to the Wet/Dry converter 125 through the air ratio calculator 129 and the mixture ratio calculator 127 from the input terminals 0 and F.
It is input to the t/Dry converter 125.

In addition, the flow velocity U (m/s) is obtained from the current IM and temperature Ta measured in the temperature sensing element 73 and the air temperature element 75 using equation (3), and the data is transferred to the mass flow calculator connected to these elements. 133. This calculator 133 converts the flow rate U (m/s) to the mass flow rate M (kg/kg/s) based on data from input terminals A, P, and t.
Conversion to S) is performed, and the next stage volume flow and quantity calculator 137
So, 1/ρ. Based on the data from the calculator 135,
The mass flow rate M (kg/s) is converted into a volumetric flow rate (m'/S), which is output to the control device via an output converter.

Next, to explain each circuit in detail, the air ratio calculator 129
performs calculations based on the following principle. When the fuel is gaseous fuel, various gas components (%) in the gaseous fuel are expressed as CD2
%, 00%, 82%, C84%, C41'llO%, C
If 5H is 10%, N2%, 02%, and 820%, then the theoretical air amount^. (N, 3/N,') is...(4), and the volume of each component of the exhaust gas after combustion is GCO,=
(CD, +CD+Σcn -C,H,,)/100
-(5) GH20=(H2+H20+ n-・C, t
ln) /100 ... (6) The volume of humid (moisture-containing) exhaust gas G (N, 3/N,') is G = GC02 + G
H20+GO□+GN2=GK10μ×^.・・・
・(9) Air ratio μ is obtained from equation (7) and (9) (where, Ozt!cw: oxygen concentration in combustion exhaust gas)
is required. That is, the air ratio μ is determined from data regarding each composition of the fuel and the wet oxygen concentration in the combustion exhaust gas.

Therefore, data regarding the oxygen concentration of the combustion exhaust gas from the oxygen sensor 45 is input from the input terminal 0, data regarding the composition of the fuel is input manually from the input terminal F, and the air ratio is determined in the air ratio calculator 129. .

In addition, the concentrations of each component other than 0□ in the combustion exhaust gas can be calculated using the following equations.

CO2 [:[12=-X 100(%)-C[l. p
cw (12) H20 H20=-×100(%)...H2O6°,
(13) N2 L” X 100 (%) ・・・N2Ecw
'(14) The above calculations are also performed by the air ratio calculator.

Note that even when the fuel is solid or liquid fuel, the concentration of each component in the fuel exhaust gas can be calculated in the same manner as in the case of gaseous fuel.

Further, the mixture ratio calculator 127 performs calculations based on the following principle.

In the exhaust gas recirculation system, the combustion exhaust gas is converted to QEo (m3
) is taken in and mixed with air OA (m') from the near blower, and if the mixing ratio at this time is M, then the amount of mixed air QWB is. Wll” OA+Ωpc (m')
...-(16) If the oxygen concentration in the combustion air at this time is 0□wBy (%), then the following equation is obtained from the balance of 0□ before and after mixing.

Qwn' 021BW =20.6・OA+02
EC11・Q.

...(17) However, 022CW is the oxygen concentration in the combustion exhaust gas.

Therefore, by substituting and rearranging equations (16) and (17), the mixture ratio M becomes, and the mixture ratio M is obtained from the oxygen concentration in the combustion exhaust gas and the oxygen concentration in the combustion air. Therefore, the mixture ratio calculator 127 includes the oxygen concentration o obtained by the oxygen sensor 45.
zacw is input through the input terminal 0, and the oxygen concentration 0□wttw obtained by the oxygen sensor 45 is input manually through the 0□ calculator 121, and the mixture ratio M is calculated.

The next-stage Wet/Dry converter 125 converts wet gas, which is gas from which moisture (H, O) contained in the combustion exhaust gas has not been removed, into dry gas, which is gas from which most of the moisture has been removed. This is a circuit that performs calculations. The principle is explained below. First, the moist oxygen concentration is 0□. W (%)
If the dry oxygen concentration is 02wBIl (%), then from equation (19), (20), and (21), the oxygen concentration in the dry gas is 0.
21BD (%) is calculated as follows. That is, in the Wet/Dry converter 125, the oxygen concentration in the combustion exhaust gas input manually from the input terminal O is 0.
A process is performed to calculate the dry oxygen concentration 021180 from 28CW, the moisture concentration 1 (20B(w) in the combustion exhaust gas calculated by the air ratio calculator 129, and the mixture ratio M calculated by the mixture ratio calculator 127. Dry oxygen concentration 02w!l.

is output to the control device and used for control.

On the other hand, in the flow rate/temperature compensation calculator 131, the temperature sensing element 73
From the current In and the fluid temperature Ta measured by the air temperature element 75, the flow velocity in the duct is 0 (m/5ec) according to equation (3).
) is processed.

The mass flow rate calculator 137 at the next stage converts the gas flow rate into a mass flow rate, and thus processes are performed based on the principle shown below. First, the mass flow rate m (kg/5ec) is m = U-A
- ρ However, U: flow velocity in the duct (m/5ec) A: duct cross-sectional area (m2) ρ: gas density (kg/m3) By the way, the gas density ρ (kg/m') is expressed as. Therefore, from the input terminals A, P, and t, the duct cross-sectional area A (m2) and the duct internal pressure P (mmHg>
, data on the gas temperature t('C) in the duct are received, and further the gas standard density ρ is obtained from the 1/ρ0 calculator 135. (kg
/)4m3) Uke takes the data on (21
) performs arithmetic processing according to the formula.

Note that the 1/ρ0 calculator 135 first calculates each component of the combustion air, so the mixture ratio calculator 12'? CD□, N20 for oxygen concentrations other than 0□wBw from the mixture ratio M calculated in
Find °N2.

Next, from each composition, calculate the standard density ρ of the gas. (kg/N,
').

ρ. =1.429・0□, Bw+1.965・CD. W
BII+Q, 804 ・N20 waw+1.251
-N2waw/100... (24) Therefore, from the oxygen concentration 0□l1ICW in the combustion exhaust gas obtained from the oxygen sensor 45 and the mixture ratio M obtained from the mixture ratio calculator 127, the standard density ρ of the gas is determined. (kg/Nm') is easily calculated. Standard density of this gas ρo (kg/Nm
') C Mass flow rate calculator 133 and volume flow rate calculator 1
371 people are empowered.

Furthermore, the volumetric flow rate calculator 137 calculates the volumetric flow rate F (m
'/5ec) is F=m・ □ ...(2
5) Since it is given by ρ0, the mass flow rate M (kg/5ec) obtained by the mass flow rate calculator 133 is added to ρ obtained by the 1/ρ0 calculator 135.

Arithmetic processing is performed within it to divide the air flow rate, and the air flow rate is output.

As described above, the valve members and the like are controlled in a feed forward manner using the oxygen concentration output obtained from the oxygen sensor 52 through each circuit and the air flow rate output obtained from the flow rate sensor 71 through each circuit. The amount of air supplied can be adjusted, multistage combustion can be performed appropriately, and as a result, N08 in the combustion exhaust gas can be reduced.

(Effects) As is clear from the above explanation, the combustion air analyzer of the present invention can calculate the dry oxygen concentration obtained during actual burner combustion from the moist oxygen concentration of the combustion air obtained by the oxygen sensor. Convert the flow rate of combustion air obtained by the flow rate sensor to the volumetric flow rate of combustion air supplied to the burner,
From these converted values, it is possible to accurately calculate the amount of oxygen supplied from the combustion air to the burner for actual combustion. If this oxygen supply amount is controlled by a control device, the combustion state of each burner can be controlled in a feedforward manner.
In addition, control that was conventionally performed based on the theoretical amount of oxygen is now performed based on the actual amount of oxygen supplied, making it possible to match the combustion balance between burners more precisely, as well as controlling the flame temperature (heat curve and heat distribution). control becomes more precise and the amount of oxygen supplied can be relatively low, so these effects combine synergistically to significantly reduce NOx generated by combustion. Moreover, it enables optimal combustion in the early stage of combustion when starting up an industrial furnace.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic diagram showing a combustion device according to an embodiment of the present invention, FIG. 2 is a side view showing a combustion air analyzer of the present invention, and FIG. 3 is a sectional view showing the mounting structure of an oxygen sensor. Fig. 4 is a side view and a plan view showing the internal structure of the flow rate sensor, Fig. 5 is a sectional view showing a modification of the mounting structure of the oxygen sensor, and Fig. 6 is an internal processing circuit of the combustion air analyzer of the present invention. FIG. 1... Furnace 3... Separate tact 5
...Valve member 7...Burner 9...Burner 11...NO port 13...Common duct 15...Near blower 17...Air heater
19...Exhaust gas recirculation path 21...Combustion air analyzer 25...Oxygen sensor 31...Oxygen sensor probe 33...Flow rate sensor probe 35...Wall part 37... Opening 39...
Terminal box 41...Mounting flange 43...Wall side flange 45...Oxygen sensor 47...Sensor fastener 49...Heater 51...Heater support tube 5
2...Sensor unit 53...Probe jig 5
5... Filter holder 57... Filter 5
9...Press jig 60...Gas passage 61...
・Calibration gas introduction pipe 63...opening 65...
-Gas inlet/outlet 67...Internal space 69...Gas discharge lower 1...Flow rate sensor 72...Filter 73...Bad air element 75...Air temperature element 83
... Inward flange 84 ... Calibration gas introduction pipe 85
...Sensor support tube 87...Outward flange 89
...Frustoconical portion 90...Opening 91...Oxygen sensor 93
...Outward flange 95...Measurement gas introduction pipe 9
9...Ceramic filter 101...Support fitting 103...Temperature detection means 105...Mounting fitting 109...Joining flange 113...Heater 115...Heater support tube 117...Electrical contact Child 118...Insulator 12
1...02 Arithmetic unit 123...Temperature controller 125
= Wet/Dry converter 127...Mixing ratio calculator 129...Air ratio calculator 131...Flow velocity/temperature compensation calculator 133...Mass flow calculator 135...1/ρ. Calculator 137...Volume flow rate calculator Patent applicant: Tokyo Electric Power Co., Ltd. Patent applicant: Nippon Insulator Co., Ltd.

Claims (1)

[Claims] 1. In a combustion air analyzer that analyzes the amount of combustion air supplied to each burner of an industrial furnace using an exhaust gas recirculation method, an oxygen sensor that measures the moist oxygen concentration of the combustion air. an oxygen concentration calculator connected to the oxygen sensor to control the oxygen sensor and perform a predetermined correction to a voltage signal corresponding to the measured wet oxygen concentration; Calculate the gas components and mixture ratio in the combustion exhaust gas from the moist oxygen concentration in the air, the moist oxygen concentration in the combustion exhaust gas, and the fuel composition,
a conversion means for converting the wet oxygen concentration of the combustion air into a dry oxygen concentration from these data; a flow velocity sensor for measuring the flow velocity of the combustion air; A combustion air analysis device comprising: means for temperature compensating measured values; and converting means connected to the means for converting into a predetermined volumetric flow rate.