JPH07119734B2 - Combustion air analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to combustion for measuring an air supply amount of combustion air sent to a combustion chamber of an industrial furnace in order to control a combustion state of the industrial furnace such as a boiler. The present invention relates to an air analyzer for use.

(Prior art) This year, NO _X in the combustion exhaust gas in the furnace of the combustion device
In order to reduce the above, combustion systems such as a two-stage combustion system, an exhaust gas mixing system and a flame splitting system have been implemented using various burners. Any of these methods is one in which the combustion temperature is lowered, the air supply amount is reduced, or a combination of these methods is used, and so-called thermal NO that easily occurs at a high temperature and an excessive air supply amount.
_It suppresses _X. There are also so-called fuel NO _X which produces nitrogen compounds contained in the addition in the fuel cause, as reduction method of the fuel NO _X, there is a combustion at a low oxygen partial pressure is desirable. To reduce these thermal NO _X and the fuel NO _X, JP 61
In the -1903 publication, burners are arranged in stages in the furnace, and first, in the lower stage, for example, an air ratio of 0.7 or less, that is, an average oxygen concentration in the total supplied air amount is 17% or less in an excessive fuel excess state. Strong reduction combustion is performed, then combustion is performed in the middle stage according to the air supply amount (air ratio of 0.8 to 0.9), and finally, in the upper stage, the insufficient air is supplied to complete combustion of the unburned components. A method for carrying out combustion according to the theoretical amount to be consumed is described. In order to perform the multi-stage combustion described in the above publication in a furnace, it is necessary to appropriately supply combustion air to each burner.

In the conventional combustion device, the combustion air first passes through the common duct, is then individually introduced into the burner combustion duct, and is supplied to each burner disposed near the opening in the duct furnace. To check the condition of combustion air,
An oxygen sensor was installed in the common duct, and the oxygen concentration was measured only at its representative point.

(Problems to be solved by the invention) However, if the representative point is measured in the common duct, multi-stage combustion with an appropriate air supply amount as described above cannot be performed, that is, optimum combustion of each burner ( Combustion management)
However, it was not possible to effectively reduce the NO _{X in} the combustion exhaust gas.

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

(Means for Solving Problems) A combustion air analyzer of the present invention is a combustion air analyzer for analyzing the supply air amount of combustion air sent to each burner of an exhaust gas recirculation type industrial furnace, An oxygen sensor for measuring the wet oxygen concentration of the combustion air; and an oxygen concentration calculator connected to the oxygen sensor for controlling the oxygen sensor and for performing a predetermined correction on the voltage signal corresponding to the measured wet oxygen concentration. Connected to the oxygen concentration calculator to calculate a gas component and a mixing ratio in the combustion exhaust gas from the wet oxygen concentration in the combustion air, the wet oxygen concentration in the combustion exhaust gas and the fuel composition,
Based on these data, a conversion means for converting the wet oxygen concentration of the combustion air into a dry oxygen concentration, a flow velocity sensor for measuring the flow velocity of the combustion air, and a flow velocity sensor connected to the flow velocity sensor and corresponding to the flow velocity obtained from the flow velocity sensor. It is characterized by comprising a means for temperature-compensating the measured value and a conversion means connected to the means for converting the measured value into a predetermined volume flow rate.

(Operation) In the present invention, among the supply air amounts of the combustion air sent to each burner, those related to the combustion of the burner are the dry oxygen concentration and the
And the volumetric flow rate of the combustion air supplied.

By the way, in the present invention, the “wet” oxygen concentration means the oxygen concentration in a state where the water (H ₂ O) contained in the gas to be measured is not removed, and the “dry” oxygen concentration is the opposite of the above. It means the oxygen concentration in the state of almost removing water.

In the exhaust gas recirculation method, since a part of the exhaust gas containing water is mixed with the combustion air, the wet gas is measured by the oxygen sensor, and as a result, the wet oxygen concentration is obtained.
However, since the actual control is performed with the dry oxygen concentration, the wet oxygen concentration is converted into the dry oxygen concentration by the conversion means. Next, the flow velocity sensor obtains a signal corresponding to the flow velocity, which is converted into the volume flow rate of the combustion air by the volume flow rate conversion means related to the actual combustion of the burner.

(Example) The Example of this invention is described based on drawing.

Figure 1 shows a schematic diagram of an industrial combustion furnace. 1 for the furnace 3
Reference numeral 5 denotes a separate duct that introduces combustion air into the furnace 1, supplies combustion air to each burner, and is partitioned into each chamber. Reference numeral 5 denotes a valve member that limits the flow rate of combustion air flowing into the separate duct 3. . Separate duct 3 for furnace 1
Burners provided so as to protrude from the furnace 1 are arranged in two stages, four burners in each stage. The lower burner 7 is a reduction burner, and the upper burner 9 is a main burner. An NO port 11 is formed on the upper furnace wall of these burners, and two-stage combustion is performed by these.

Further, a common duct 13 for supplying combustion air to the separate duct 3 is provided, and to the common duct 13, for example, air having an oxygen concentration of 20.6% sent from an air blower 15 through an air heater 17 is connected to an exhaust gas recirculation path. Combustion air having an oxygen concentration of, for example, 17%, which is a mixture of a part of combustion exhaust gas having an oxygen concentration of 2%, is supplied. This is generally called an exhaust gas recirculation system. further,
A combustion air analyzer 21 is inserted through the pipe wall of each duct at a position between each burner and each valve member of each separate duct 3.

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

In Fig. 2, an oxygen sensor probe 31 for measuring the oxygen concentration of combustion air (hereinafter referred to as "measurement gas"), which is the measurement gas, and a flow sensor probe, which also measures the flow rate of the measurement gas. 33 and 33 are inserted into an opening 37 formed in the wall portion 35 of each separate duct 3, and the probes 31 and 33 are integrated at their base ends, that is, a terminal box 39, and are formed in this terminal box 39. Mounting flange 41,
The wall side flange 43 provided on the wall portion 35 is screwed to maintain the inserted state of the probes 31 and 33.

As shown in detail in FIG. 3, the probe 31 for the oxygen sensor
On the front end side of the probe 31, for example, a low and low cylindrical oxygen sensor 45 is attached to the probe jig of the probe 31 by a screw or the like via a sensor fastener 47 that is hermetically fixed by, for example, a shrink fitting method.
It is screwed to 53. Further, around the oxygen sensor 45 attached in this way, a heater holder 51 (which constitutes a heater unit) having a heater 49 built therein is fitted to the sensor fastening fitting 47 from the inside, and integrated by cement bonding. It is fixed to. Therefore, the oxygen sensor 45, the sensor fastener 47, the heater 49, and the heater holder 51.
(That is, the heater unit) is integrated into a sensor unit 52.

On the side of the oxygen sensor 45 exposed to the gas to be measured, in order to prevent the inflow of dust and the like, a probe jig 53 is fitted with a filter holder 55, and an opening provided in the filter holder 55. The filter 57 is inserted into the part and the filter 57
Are fixed by screwing a pressing jig 59 having an opening at the center. By the way, a step portion is provided on the outer peripheral portion of the outer corner portion of the filter holder 55 on the side that abuts the sensor fastener 47, and the step portion of the filter holder 55 and the probe jig are provided.
A gas passage 60 is formed between 53. Furthermore, a gas inlet / outlet 69 communicating with the outlet 63 of the calibration gas inlet pipe 61 of the filter holder 55 and communicating with the internal space 67 is provided, and further, a portion opposite to the gas inlet / outlet 69 of the filter holder 55 is provided. A gas exhaust port 69 is provided at a position of the probe jig 53 that is substantially opposite to the position. Therefore, a communication space from the internal space 67 to the measured gas space is formed. Therefore, the measurement gas or the calibration gas introduced into the internal space 67 can be quickly discharged to the outside.

With respect to the oxygen sensor having such a predetermined shape, the gas to be measured is introduced into the internal space 67 through the filter 57, and a part of the gas is replaced by gas diffusion and thermal convection due to the concentration difference of the gas to be measured. The measurement is performed and reaches the measurement electrode provided inside the oxygen sensor 45. Other gases to be measured are discharged to the outside through the gas inlet / outlet port 65, the gas passage 60 and the gas outlet port 69 as shown in the figure. Therefore, since the oxygen sensor 45 is provided with a gas flow passage from the inflow to the outflow of the gas to be measured, the gas to be measured is rapidly introduced into the internal space, and moreover, the measurement electrode of the oxygen sensor is almost free. By performing the gas replacement while maintaining the equilibrium state, it is possible to protect the oxygen sensor 45 with high responsiveness and at the same time protect it against thermal shock.

Similarly, when introducing the calibration gas for calibrating the output of the oxygen sensor, first, the calibration gas passes through the calibration gas introduction pipe 61 arranged outside the probe 31, and passes through the opening 63 and the gas inlet / outlet 65. The interior 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 filled in the internal space 67 reaches the deep portion of the oxygen sensor 45 after gas replacement is performed by gas diffusion and gas convection due to a difference in gas concentration, and contacts the measurement electrode. The other calibration gas is discharged from the gas discharge port 69 through the gas passage 60 when the internal space 67 has a negative pressure with respect to the pressure of the measurement gas atmosphere. Therefore, the calibration gas does not hit the measurement electrode of the oxygen sensor 45 directly when the calibration gas is introduced,
That is, it does not cool rapidly, and the temperature change of the oxygen sensor between the time of measuring the gas to be measured and the time of introducing the calibration gas is small, which enables highly accurate calibration.

On the other hand, on the tip side of the probe 33, as shown in FIG. 4, a constant temperature hot wire type flow velocity sensor (hereinafter abbreviated as “flow velocity sensor”) 71 for measuring the flow velocity of the gas to be measured is provided. This flow velocity sensor 71 has a wind sensing element 73 for measuring the flow velocity.
And a wind temperature element 75 for temperature compensation, and in a portion of the probe 33 corresponding to the flow velocity sensor 71, a mesh filter 72 is provided to prevent dust and the like from entering the probe 33. The gas to be measured is introduced while excluding the inflow. By the way, to explain the principle of the wind sensitive element, when the measured gas hits the sensor part which is placed in the flow of the gas to be measured and is heated by the electric current flowing through the resistance wire as the sensor part, the resistance wire is cooled. The temperature will drop. The amount of heat taken at this time is related to the flow velocity, and the relationship between the flow velocity U (m / s) and the radiated heat amount H at this time is shown by King's equation.

H = (a + b · U ^{1 / m} ) (T−Ta) (1) where H: heat dissipation a, b, m: constant determined by fluid etc. U: flow velocity T: heated object (ie Temperature) Ta: Temperature of surrounding fluid.

However, in the constant temperature hot wire flow velocity sensor, the same amount of heat as the amount of heat radiated is supplied by the electric current, the amount of heat radiated and the amount of heat supplied are always kept constant, and the resistance temperature is kept constant. Therefore, the flow velocity is obtained by measuring the supplied heat amount. For this reason, if a bridge circuit having a heat wire on one side is configured, the resistance of this heat wire is R _H , and the current flowing in the heat wire is I _H , the heat supply Q is Q = I _H ² · R _H (2) At this time, the amount H of heat dissipated and the amount Q of heat supplied are balanced, so if we set H = Q, then I _H ² · R _H = (a + b · U ^{1 / m} ) (T−Ta) (3) Therefore, If the I _H -T relationship and Ta are known, the flow velocity U can be obtained by measuring the current value I _H. However, in order to obtain Ta, the air temperature element 75 is used to measure the temperature of the gas to be measured.

This hot-wire type wind sensitive element 73 is characterized by other differential pressure type flow rate measurement,
Compared to the Karman vortex flow rate measurement, it is not affected by the fluid pressure, viscosity, etc., and is particularly effective in the case of combustion air flowing into an industrial furnace such as a boiler because the draft pressure is large. Also, this type is convenient because it can be made compact and lightweight in terms of structure.

As described above, the probe 31 having the oxygen sensor 45 and the probe 33 having the flow velocity sensor 71 are integrated at the base end portions thereof, and the tips of the respective probes are placed close to each other so as not to interfere with each other's operation. Because of the arrangement, the oxygen concentration in the burner combustion air and the combustion air flow rate (that is, the oxygen flow rate) can be continuously measured at substantially the same installation point.

Next, as a modified example 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 of FIG. A cylindrical cell support tube 85 made of metal is inserted, and the cell support tube 85 has an outward flange 87 and a frustoconical portion.
89 and the opening provided in this frustoconical portion 89
A bottomed cylindrical oxygen sensor 91 is fitted in 90 with its bottom portion facing the flange side.

Further, a cylindrical measured gas introducing pipe 95 having an outward flange 93 is inserted into the sensor supporting pipe 85 from the outside, and the sensor supporting pipe 85 and the measuring gas introducing pipe 95 are connected to their outward flanges 87 and 93. It can be fixed to the probe 31 by being screwed to the inward flange 83 with a bolt or the like in the area. By the way, a calibration gas introducing pipe 84 penetrating the inward flange 83 and the outward flange 87 is provided, and the calibration gas is supplied to the cell supporting pipe 85 and the measured gas introducing pipe 95.
The oxygen sensor 91 is sent through the gap formed between the two. In addition, the flange side opening 97 of the measured gas introduction pipe 95 is provided with a porous ceramic filter for dust removal.
99 is adhered by means such as alumina cement.

Inside the probe 31, a stainless steel support fitting 101 inserted from the base end side of the probe extends concentrically with the probe 31, and a reference gas is diffused between the support fitting 101 and the probe 31. I am trying to get in. Further, a temperature detecting means 103 for measuring the temperature in the vicinity of the oxygen sensor, for example, a thermocouple or the like is attached to the support fitting 101 by a fitting 105. Further, a heater support tube 115 having an annular heater 113 is connected to the tip of the support fitting 101 via a joint flange 109. An electric 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 for holding 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.

In the device configured as described above, a cylindrical gap is formed between the measured gas introduction pipe 95 and the sensor support pipe 85 in a state where all the components are attached, and this gap is formed by the sensor support pipe 85. Calibration gas inlet tube 84 that extends through the
The gas from the gas outlet is guided to blow the gas from the outer periphery to the base side of the detection cell toward the tip side. Further, since this gap has a large surface area, the heat is efficiently transferred to the calibration gas from the heater 113 which is located in the vicinity of the cell support pipe 85 and the heater support pipe 115 with the wall of the gap therebetween. Therefore, it is possible to reduce the rapid cooling of the detection cell, that is, the disturbance of the temperature control caused by spraying the calibration gas having a large temperature difference from the gas to be measured on the detection cell.

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

In the block diagram shown in FIG. 6, the output voltage corresponding to the oxygen concentration of the combustion air is supplied from the oxygen sensor 45 of the sensor unit 52 to the O ₂ calculator 121 connected to the oxygen sensor 45, where the output voltage of the oxygen sensor 45 is changed. In addition to performing control, various processes of linearizing the relationship between the output voltage and the oxygen concentration, calibrating, and correcting the pressure are performed. The output voltage processed by the O ₂ calculator 121 is the Wet / Dry converter connected to the 0 ₂ calculator 121.
It is supplied to 125, where the process of converting the measured wet oxygen concentration containing water into the measured dry oxygen concentration containing no water is performed. The measured value of the dry air is output to a controller (not shown), and the controller performs feedforward control based on this value. Data necessary for the calculation of the Wet / Dry converter 125 is input to the Wet / Dry converter 125 from the input terminals O and F through the air ratio calculator 129 and the mixing ratio calculator 127.

Further, the flow velocity U (m / s) is obtained from the equation (3) from the current I _H and the temperature Ta measured by the wind sensitive element 73 and the wind temperature element 75, and the data is calculated by the mass flow rate calculation connected to these elements. Output to the device 133. In this computing unit 133, the flow velocity U is calculated based on the data of the duct cross-sectional area A (m ² ) supplied from the input terminals A, P, t, the duct internal pressure P (mmHg), and the duct internal gas temperature t (° C). (M / s) is converted to mass flow rate m (kg / S), and 1 / ρ is calculated by the volume flow calculator 137 in the next stage.
₀ Based on the data from the calculator 135, the mass flow rate m / (kg /
s) is converted into a volume flow rate F (m ³ / s), which is output to the control device via the output converter.

Next, each circuit will be described in detail. The air ratio calculator 129
Calculates based on the following principle. When the fuel is a gaseous fuel, the various gas components (%) in the gaseous fuel are
_{2%, CO%, H 2} %, CH 4%, C 4 H 10%, C 5 H 12%, N 2%, O 2
%, H ₂ O%, the theoretical air amount A ₀ (N _m ³ / N _m ³ ) is And the volume of each component of the exhaust gas after combustion is GCO ₂ = (CO ₂ + CO + Σm · C _m H _n ) / 100 …… (5) The volume G (N _m ³ / N _m ³ ) of moist (water-containing) exhaust gas is G = GCO ₂ + GH ₂ O + GO ₂ + GN ₂ = GK 1 + μ × A ₀ …… (9) The air ratio μ is calculated from equations (7) and (9). (However, O _ZECW : Oxygen concentration in combustion exhaust gas) is required. That is, the air ratio μ can be obtained from the 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 25 is input from the input terminal O, data regarding the fuel composition is input from the input terminal F, and the air ratio calculator 12
Within 9 the air ratio is required.

The concentration of each component other than O ₂ in the combustion exhaust gas can be calculated by the following formula.

The above calculation is also performed by the air ratio calculator.

When the fuel is solid or liquid fuel, the concentration of each component in the combustion exhaust gas can be calculated in the same manner as in the case of gaseous fuel.

Further, the mixing ratio calculator 127 calculates based on the following principle.

In the exhaust gas recirculation system, the fuel gas Q _EC (m ³⁾ incorporation, when mixed with air Q _A (m ³⁾ from air blower, when the mixing ratio at this time is M, The mixed air amount Q _WB is Q _WB = Q _A + Q _EC (m ³ ) (16) If the oxygen concentration in the combustion air at this time is O _ZWBW (%), the amount of O ₂ before and after mixing is The following equation is obtained from the balance.

Q _WB / O _ZWBW = 20.6 / Q _A + O _ZECW / Q _EC (17) However, O _ZECW is the oxygen concentration in the combustion exhaust gas.

Therefore, by substituting and rearranging equations (16) and (17), Therefore, the mixing ratio M is Therefore, the mixing ratio M is obtained from the oxygen concentration in the combustion exhaust gas and the oxygen concentration in the combustion air. Therefore, the mixing ratio calculator 127 displays the oxygen concentration O obtained by the oxygen sensor 25.
_ZECW is input via input terminal O and oxygen sensor
The oxygen concentration O _ZWBW obtained by 45 is input through the O ₂ calculator 121, and the mixing ratio M is calculated.

The Wet / Dry converter 125 in the next stage converts the wet gas, which is the gas in which the moisture (H ₂ O) contained in the combustion exhaust gas is not removed, into the dry gas, which is the gas from which most of the moisture is removed. Is a circuit for performing the calculation of. To explain the principle below, wet oxygen concentration O _ZWBW (%) First, when the dry oxygen concentration O _ZWBD (%), is expressed by the following equation (20).

From equation (19) From equations (20) and (21), oxygen concentration O in dry gas
_ZWBD (%) is Required by. That is, in the Wet / Dry converter 125, the oxygen concentration O _ZECW in the combustion exhaust gas input from the input terminal O and the moisture concentration H ₂ O in the combustion exhaust gas calculated by the air ratio calculator 129
A process of calculating the dry oxygen concentration O _ZWBD from the _ECW and the mixing ratio M calculated by the mixing ratio calculator 127 is performed. This dry oxygen concentration O _ZWBD is output to the control device and used for control.

On the other hand, the flow velocity / temperature compensation calculator 131 calculates the flow velocity U (m / sec) in the duct from the current I _H measured by the wind sensitive element 73 and the wind temperature element 75 and the fluid temperature Ta according to the equation (3). It

In the mass flow rate calculator 133 in the next stage, the gas flow rate is converted into a mass flow rate, and therefore the processing is performed based on the following principle. First, the mass flow rate m (kg / sec) is m = U ・ A ・ ρ (23) where U: Velocity in duct (m / sec) A: Duct cross-sectional area (m ² ) ρ: Gas density (kg) / m ³ ) By the way, the gas density ρ (kg / m ³ ) is Indicated by. Therefore, the data of the duct cross-sectional area A (m ² ), the duct internal pressure P (mmHg), and the duct internal gas temperature t (° C) are received from the input terminals A, P, and t, respectively, and 1 / ρ
_The data regarding the gas standard density ρ ₀ (kg / Nm ³ ) is received from the ₀ calculator 135, and the calculation processing according to the equation (23) is performed.

Since the 1 / ρ ₀ calculator 135 first calculates each component of the combustion air, the mixing ratio M calculated by the mixing ratio calculator 127 is calculated.
From _these , CO ₂ , H ₂ O, and N ₂ other than the oxygen concentration O _ZWBW are obtained.

Next, the standard density ρ ₀ (kg / Nm ³ ) of the gas is obtained from each composition.

ρ ₀ = 1.429 ・ O _ZWBW ＋1.965 ・ CO _ZWBW ＋0.804 ・ H ₂ O _WBW ＋1.251 ・ N _ZWBW / 100 …… (25) Therefore, oxygen concentration in combustion exhaust gas obtained from oxygen sensor 25 O _ZECW And from the mixing ratio M obtained by the mixing ratio calculator 127,
The standard density ρ ₀ (kg / Nm ³ ) of the gas is calculated. The standard density ρ ₀ (kg / Nm ³ ) of this gas is input to the mass flow calculator 133 and the volume flow calculator 137.

Furthermore, in the volume flow rate calculator 137, the volume flow rate F (m ³ / se
c) is Since the mass flow rate m (kg / sec) obtained by the mass flow rate calculator 133 is divided by ρ ₀ obtained by the 1 / ρ ₀ calculator 135, the calculation processing is performed inside the The flow rate is output.

As described above, the oxygen sensor unit 52 or the oxygen sensor 45
Concentration output obtained through each circuit from the
By the air flow rate output obtained from 71 through each circuit,
It is possible to adjust the feed rate of combustion air by feed-forward controlling valve members, etc., and perform appropriate multi-stage combustion.
As a result, NO _X in the combustion exhaust gas can be reduced.

(Effect) As is clear from the above description, the combustion air analyzer of the present invention converts the wet oxygen concentration of the combustion air obtained by the oxygen sensor into the dry oxygen concentration involved in the actual combustion of the burner. , Converting the flow velocity of the combustion air obtained by the flow velocity sensor into the volume flow rate of the combustion air supplied to the burner,
From these conversion values, it is possible to accurately calculate the oxygen supply amount involved in the actual combustion of the burner from the combustion air. If the oxygen supply is controlled by the controller, the combustion state of each burner can be feedforward controlled,
Moreover, since the control that was conventionally performed based on the theoretical oxygen amount is performed based on the actual oxygen supply amount, it is possible to more accurately match the combustion balance between the burners, and the flame temperature (heat curve and heat distribution). Can be controlled more accurately and the amount of oxygen supplied can be made relatively low. Therefore, these effects can be synergistically combined to significantly reduce the NO _X generated by combustion. Further, at the beginning of combustion at the start of the industrial furnace, optimum combustion can be achieved.

[Brief description of drawings]

FIG. 1 is an overall schematic view showing a combustion apparatus 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 an oxygen sensor mounting structure. FIG. 4 is a side view and a plan view showing the internal structure of the flow velocity sensor, FIG. 5 is a sectional view showing a modified example 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. It is a block diagram shown. 1 ... Furnace, 3 ... Separate duct 5 ... Valve member, 7 ... Burner 9 ... Burner, 11 ... NO port 13 ... Common duct, 15 ... Air blower 17 ... Air heater, 19 ... Exhaust gas re- Circulation path 21 …… Combustion air analyzer, 25 …… Oxygen sensor 31 …… Oxygen sensor probe, 33 …… Flow velocity sensor probe 35 …… Wall, 37 …… Opening 39 …… Terminal box, 41 …… Mounting flange 43 …… Wall side flange, 45 …… Oxygen sensor 47 …… Sensor bracket, 49 …… Heater 51 …… Heater holder, 52 …… Sensor unit 53 …… Probe jig, 55 …… Filter holder 57 …… filter, 59 …… pressing jig 60 …… gas passage, 61 …… calibration gas inlet tube 63 …… opening, 65 …… gas inlet / outlet 67 …… internal space, 69 …… gas outlet 71 …… Flow velocity sensor, 72 …… Filter 73 …… Air sensing element, 75 …… Air temperature element 83 …… Inward flange, 84 …… Calibration gas inlet pipe 85 …… Sensor support pipe, 87 …… Outward flange 89 …… Head-cone-shaped part, 90 …… Opening 91 …… Oxygen sensor, 93 …… Outward flange 95 …… Measured gas introduction Pipe, 97 ...... Flange side opening 99 ...... Ceramic filter, 101 ...... Support metal fitting 103 ...... Temperature detection means, 105 ...... Mounting metal fitting 109 ...... Join flange, 113 ...... Heater 115 ...... Heater support pipe, 117 ...... … Electric contacts 118 …… Insulators, 121 …… O ₂ calculator 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 ₀ calculator, 137 …… Volume flow calculator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Kodachi 24-18 Shinkaimachi, Mizuho-ku, Nagoya-shi, Aichi No. 402 Shinkai Housing (72) Inventor Hiroshi Yamada Tsurugazawa, Narumi-cho, Midori-ku, Nagoya-shi, Aichi No. 49, No. 3 (56) Reference JP-A-53-58289 (JP, A) JP-A-60-85360 (JP, A) JP-A-1-250745 (JP, A)

Claims (1)

[Claims] 1. A combustion air analyzer for analyzing the amount of combustion air supplied to each burner of an exhaust gas recirculation type industrial furnace, and an oxygen sensor for measuring the wet oxygen concentration of the combustion air. An oxygen concentration calculator connected to the oxygen sensor to control the oxygen sensor and to perform a predetermined correction on the voltage signal corresponding to the measured wet oxygen concentration; and an oxygen concentration calculator connected to the oxygen concentration calculator, Calculate the gas components and mixing ratio in the combustion exhaust gas from the wet oxygen concentration and the wet oxygen concentration in the combustion exhaust gas and the fuel composition,
Based on these data, a conversion means for converting the wet oxygen concentration of the combustion air into a dry oxygen concentration, a flow velocity sensor for measuring the flow velocity of the combustion air, and a flow velocity sensor connected to the flow velocity sensor and corresponding to the flow velocity obtained from the flow velocity sensor. A combustion air analyzer comprising: a means for temperature-compensating a measured value; and a conversion means connected to the means for converting into a predetermined volume flow rate.