WO2008004281A1

WO2008004281A1 - Combustion apparatus

Info

Publication number: WO2008004281A1
Application number: PCT/JP2006/313329
Authority: WO
Inventors: Osamu Tanaka; Yukihiro Tokunaga; Yusuke Okamoto; Kenji Yasui
Original assignee: Miura Co., Ltd.; Miura Protec Co., Ltd.
Priority date: 2006-07-04
Filing date: 2006-07-04
Publication date: 2008-01-10
Also published as: CN101415994A; CN101415996B; CN101415994B; CN101512224B; CN101415996A; CN101512224A

Abstract

A combustion apparatus that first attains reduction of the amount of nitrogen oxide emitted to next to nil and reduction of the amount of carbon monoxide emitted to a tolerance level; secondly realizes energy saving through combustion at a low air ratio close to zero; and thirdly attains stable air ratio control within a low-air-ratio combustion region. There is provided a combustion apparatus including a burner, heat absorption means for conducting heat absorption from a gas produced by the burner, a catalyst for oxidation of carbon monoxide contained in the gas having passed through the heat absorption means and reduction of contained nitrogen oxide by carbon monoxide, a sensor for detection of the air ratio of the burner and air ratio regulation means for controlling the air ratio of the burner at a set air ratio in accordance with a detection signal from the sensor, characterized in that the burner and the heat absorption means are so constructed that when the air ratio has been regulated at the set air ratio by the air ratio regulation means, there can be obtained the oxygen, nitrogen oxide and carbon monoxide concentration proportions on the primary side of the catalyst which render the nitrogen oxide concentration on the secondary side of the catalyst substantially zero.

Description

Specification

Combustion device

Technical field

[0001] The present invention relates to a combustion apparatus applied to a water tube boiler, a regenerator of an absorption chiller, and the like.

Background art

[0002] In general, as a principle for suppressing NOx generation, suppression of flame (combustion gas) temperature, shortening of residence time of high-temperature combustion gas, and the like are known. There are various low NOx technologies that apply these principles. For example, the two-stage combustion method, the concentration combustion method, the exhaust gas recirculation combustion method, the hydrogenation combustion method, the steam injection combustion method, and the flame cooling combustion method using water tube groups have been proposed and put to practical use.

[0003] By the way, even with a relatively small capacity! / 水 NOx generation source such as a water tube boiler, the impact on the environment has increased, and a further low NOx emission has been demanded. In reducing NOx, reducing NOx production increases CO emissions, making it difficult to reduce NOx and CO simultaneously.

[0004] The cause is that low NOx and low CO are contradictory technical issues. In other words, if the combustion gas temperature is drastically lowered to promote low NOx and suppressed to a low V and temperature of 900 ° C or less, a large amount of CO is generated and the generated CO is not oxidized. As a result, CO emissions will increase. Conversely, if the combustion gas temperature is suppressed to a high level to reduce CO emissions, the amount of NOx produced will be insufficiently suppressed.

[0005] In order to solve this problem, the applicant suppresses the combustion gas temperature so that the amount of CO generated with low NOx emissions is reduced as much as possible and the generated CO is oxidized. Proposed low N Ox and low CO technologies and commercialized them (see Patent Documents 1 and 2). However, the low NOx technology described in Patent Documents 1 and 2 actually has a generated NOx value of only about 25 ppm.

[0006] As a solution to this problem, the applicant reduced the NOx emission by suppressing the combustion gas temperature so that the suppression of NOx generation has priority over the reduction of the emission CO value, and the generated NOx value is less than a predetermined value. And then a low NOx combustion method is proposed in which a CO reduction step in which the emission CO value from the NOx reduction step is set to a predetermined value or less is performed (see Patent Documents 3 and 4). According to the technologies described in Patent Documents 3 and 4, it is difficult to realize a low NOx concentration of less than 5 ppm, which enables a low NOx concentration of less than 10 ppm. This is due to the inevitable generation of NOx above 5ppm due to the characteristics of combustion!

[0007] The low NOx technologies described in Patent Documents 3 and 4 belong to a so-called high air ratio combustion region having an air ratio of 1.38 or more. On the other hand, in the premixed combustion region where the air ratio is 1.1 or less (hereinafter referred to as “low air ratio”), the amount of carbon monoxide and carbon is increased, making it difficult to put it into practical use, and the air specific force ^ In the following cases, stable combustion control is difficult, such as causing a backfire, so the low air ratio combustion region has not been the subject of research and development until now.

[0008] On the other hand, as the background of the times, there is a demand for lower NOx emissions for boilers and a low air ratio operation that saves energy.

Patent Document 1: Japanese Patent No. 3221582

Patent Document 2: US Patent No. 5353748

Patent Document 3: Japanese Patent Application Laid-Open No. 2004-125378

Patent Document 4: U.S. Patent No. 6792895

Disclosure of the invention

Problems to be solved by the invention

[0010] The inventors of this application have reduced the amount of nitrogen oxides emissions to nearly zero in a combustion region with a low air ratio that is as close to 1 as possible with little research. We have been researching a combustion device that can reduce carbon monoxide emissions to an acceptable level and achieve energy savings with a low air ratio.

[0011] The problem to be solved by the present invention is, firstly, to reduce the amount of nitrogen oxides to almost zero and to reduce the amount of carbon monoxide to an allowable range. . The second is to realize energy saving by combustion at a low air ratio close to 1. Thirdly, the air ratio control is stably performed in the combustion region of the low air ratio.

Means for solving the problem [0012] The present invention has been made to solve the above-mentioned problems. The invention according to claim 1 is directed to a burner, a heat absorption means for performing heat absorption from a gas generated by the burner, and the heat absorption hand. A catalyst for oxidizing carbon monoxide contained in the gas after passing through the stage and reducing nitrogen oxide by carbon monoxide, a sensor for detecting the air ratio of the PANA, and a detection signal of the sensor An air ratio adjusting means for controlling the air ratio of the burner to a set air ratio, and when the air ratio adjusting means adjusts the air ratio to the set air ratio by the air ratio adjusting means, The catalyst is characterized in that the concentration ratio of oxygen, nitrogen oxide and carbon monoxide on the primary side of the catalyst can be obtained so that the nitrogen oxide concentration on the secondary side is substantially zero. In this and the following claims, the detected air ratio and the set air ratio can be replaced with a detected air-fuel ratio, a set air-fuel ratio or a detected oxygen concentration, and a set oxygen concentration, respectively.

[0013] The invention according to claim 2 oxidizes carbon monoxide contained in the gas after passing through the heat absorption means that absorbs heat from the gas generated by the burner, and the gas generated in the heat absorption means. A catalyst for reducing nitrogen oxides with carbon monoxide, a sensor for detecting the air ratio of the panner, and an air ratio adjustment for controlling the air ratio of the panner to a set air ratio based on the detection signal of the sensor And when the air ratio is adjusted to the set air ratio by the air ratio adjusting means, the nitrogen oxide concentration on the secondary side of the catalyst is substantially zero. The air ratio is characterized by NOx · CO characteristics.

[0014] The invention according to claim 3 oxidizes carbon monoxide contained in the gas after passing through the endurance means, endothermic means for absorbing heat from the gas generated in the parner, and the endothermic means. A catalyst for reducing nitrogen oxides with carbon monoxide, a sensor for detecting the air ratio of the panner, and an air ratio adjustment for controlling the air ratio of the panner to a set air ratio based on the detection signal of the sensor And when the air ratio is adjusted to the set air ratio by the air ratio adjusting means, the carbon monoxide concentration in the gas on the primary side of the catalyst is increased by the acid ratio adjusting means. A value obtained by adding the concentration of carbon monoxide reduced in the catalyst by the gas-ion and the concentration of carbon monoxide reduced in the catalyst by the reduction. It is characterized by being configured to be almost equal! /, Or more.

[0015] The invention according to claim 4 oxidizes carbon, monoxide contained in the gas after passing through the endotherm, endothermic means that absorbs heat from the gas generated in the parner. A catalyst for reducing nitrogen oxides with carbon monoxide, a sensor for detecting the air ratio of the panner, and an air ratio adjustment for controlling the air ratio of the panner to a set air ratio based on the detection signal of the sensor And when the air ratio is adjusted to the set air ratio by the air ratio adjusting means, the concentration ratio of the gas before flowing into the catalyst is expressed by the following equation (1): Combustion device characterized by being configured to satisfy.

([NOx] + 2 [0]) /[CO]≤2.0

2

(In Formula (1), [CO], [NOx] and [O] are the carbon monoxide concentration and nitrogen acid, respectively.

2

Indicates the concentration of oxide and oxygen, and [o]> 0

2 Satisfy the condition. )

According to the first to fourth aspects of the invention, it is possible to provide a combustion apparatus that can reduce the amount of nitrogen oxides discharged to almost zero.

[0016] The invention of claim 5 is characterized in that, in claim 1 to claim 4, the set air ratio is substantially 1.

[0017] According to the invention described in claim 5, the effect of the invention described in claims 1 to 4 is reduced, and as close to 1 as possible, energy saving by low air ratio combustion can be realized. Play.

[0018] The invention according to claim 6 oxidizes carbon, monoxide contained in the gas after passing through the heat absorption means that absorbs heat from the gas generated in the burner, and the heat generated by the heat absorption means. A catalyst for reducing nitrogen oxides with carbon monoxide, a sensor for detecting the air ratio of the burner, and an air ratio adjusting means for controlling the air ratio of the burner based on a detection signal of the sensor; The burner and the endothermic means are used to oxidize oxygen and nitrogen on the primary side of the catalyst so that the nitrogen oxide concentration and oxygen concentration on the secondary side of the catalyst become substantially zero by controlling the air ratio of the air ratio adjusting means. It is structured to be able to obtain the concentration ratio of the product and carbon monoxide. Here, the oxygen concentration is substantially zero, the force to make lOOppm or less, preferably the measurement limit value or less. [0019] According to the invention described in claim 6, the amount of nitrogen oxides discharged can be reduced to nearly zero, and can be reduced to as close as 1 to realize energy saving by low air ratio combustion.

[0020] The invention according to claim 7 is the invention according to claim 1 to claim 6, wherein the air ratio adjusting means includes an electric control means and Z or mechanical control means for stably controlling the air ratio. It is characterized by that.

[0021] According to the invention of claim 7, in addition to the effects of the inventions of claims 1 to 6, the air ratio can be stably controlled, and oxygen and carbon monoxide on the primary side of the catalyst. The concentration ratio and nitrogen oxide concentration ratio adjustment can be realized stably.

[0022] The invention according to claim 8 is the invention according to claim 7, wherein the air ratio adjusting means includes a flow rate adjusting means for controlling an air ratio of the burner, a motor for controlling an opening degree of the flow rate adjusting means, And a mechanical control unit configured to control the degree of opening change of the flow rate adjusting unit in accordance with a driving amount.

[0023] According to the invention of claim 8, in addition to the effect of the invention of claim 7, the opening degree change amount of the flow rate adjusting means is controlled by a motor that controls according to the drive amount. As a result, the opening degree of the flow rate adjusting means can be reliably controlled.

[0024] The invention according to claim 9 is characterized in that, in claim 8, the motor is a stepping motor.

[0025] According to the invention of claim 9, in addition to the effect of the invention of claim 8, it is possible to achieve an effect that position control can be performed with high accuracy.

The invention according to claim 10 is the invention according to claim 7, wherein the air ratio adjusting means includes a flow rate adjusting means for controlling an air ratio of the burner and a motor for controlling an opening degree of the flow rate adjusting means. And the electric control means for controlling the air ratio detected by the sensor to be within a set range including the set air ratio.

[0027] According to the invention of claim 10, in addition to the effect of the invention of claim 7, the air ratio can be converged and controlled within the set range, so that the air ratio can be controlled stably. It has the effect of being able to

[0028] The invention according to claim 11 is the mechanical control device according to claim 10, wherein the motor is a motor that controls an amount of change in opening of the flow rate adjusting means according to a drive amount. It is characterized by comprising steps.

According to the invention of claim 11, in addition to the effect of the invention of claim 10, the opening degree change amount of the flow rate adjusting means is controlled by a motor that controls according to the drive amount. As a result, the opening degree of the flow rate adjusting means can be reliably controlled.

[0030] The invention according to claim 12 is the invention according to claim 11, wherein the electrical control means changes a drive amount per unit time of the motor in accordance with a difference between the detected air ratio and the set air ratio. A first control zone and a second control zone with the drive amount set to a predetermined value outside the first control zone are provided to control the drive amount of the motor.

[0031] According to the invention of claim 12, in addition to the effect of the invention of claim 11, when the detected air ratio is in the first control zone, overshooting and notching of the air ratio When the detected air ratio is in the second control zone, the air ratio can be set to the first control zone in terms of speed and force.

[0032] Further, the invention of claim 13 is characterized in that in claim 1 to claim 11, the panner is a premixed panner.

[0033] According to the invention of claim 13, in addition to the effects of the invention of claims 1 to 11, in particular, in the combustion region of a low air ratio! There is an effect that the concentration ratio can be adjusted relatively easily.

The invention's effect

[0034] According to the present invention, it is possible to provide a combustion apparatus that can reduce the amount of nitrogen oxides discharged to nearly zero and reduce the amount of carbon monoxide emitted.

Brief Description of Drawings

FIG. 1 is an explanatory view of a longitudinal section of a steam boiler according to a first embodiment.

FIG. 2 is a sectional view taken along line II—II in FIG.

FIG. 3 is a diagram showing a main configuration of the catalyst of FIG. 2 as viewed from the flow direction of exhaust gas.

FIG. 4 is a diagram showing the air ratio-ΝΟχ · CO characteristics of Example 1.

FIG. 5 is an explanatory view of a partial cross section of the damper position adjusting device according to the first embodiment when used.

FIG. 6 is a cross-sectional explanatory view of a main part of the damper position adjusting device.

FIG. 7 is a diagram for explaining output characteristics of the sensor of the first embodiment. FIG. 8 is a diagram for explaining motor control characteristics of the first embodiment.

FIG. 9 is a diagram illustrating NOx and CO reduction characteristics of Example 1.

FIG. 10 is an explanatory view of a longitudinal section of a steam boiler according to the second embodiment.

FIG. 11 is a diagram for explaining motor control characteristics of the second embodiment.

Explanation of symbols

[0036] 1 Pana

4 Catalyst

7 Sensor

8 Controller

28 Air ratio adjustment means

29 Damba

30 Damper position adjustment device

34 Motor

BEST MODE FOR CARRYING OUT THE INVENTION

Next, an embodiment of the present invention will be described. Prior to describing the embodiments of the present invention, terms used in this application will be described. “Gas” refers to the gas from the PANA to the end of passing through the catalyst, and the gas after passing through the catalyst is referred to as “exhaust gas”. Therefore, the gas includes a gas in the combustion reaction (combustion process) and a gas in which the combustion reaction is completed, and can be referred to as a combustion gas. Here, when the catalyst is provided in multiple stages along the gas flow, “gas” refers to the gas that has passed through the final stage catalyst, and “exhaust gas” refers to the final stage catalyst. The gas after passing through.

[0038] The "primary side of the catalyst" is the side where the catalyst is provided with a partner! /, And unless otherwise specified, refers to the gas immediately before passing through the catalyst. “Secondary side” refers to the opposite side of the primary side of the catalyst.

[0039] Also, "not containing HC" means that the gas substantially contains HC that reduces nitrogen oxides (below the measurement limit). .

[0040] Further, the air ratio m is defined as m = 2lZ (21— [O]). However, [O] is in the exhaust gas.

twenty two

[O] used to calculate the air ratio is excessive in the oxygen excess region. It represents the oxygen concentration. In the excess fuel region, the deficient oxygen concentration required for burning unburned gas such as carbon monoxide and carbon at an air ratio m = 1 is expressed as a negative value.

Next, an embodiment of the present invention will be described. The present invention is applied to a combustion apparatus (may be referred to as a thermal apparatus or a combustion apparatus) such as a water tube boiler such as a small once-through boiler, a water heater, or a regenerator of an absorption chiller.

[0042] An embodiment of the present invention includes a burner, a heat absorption means that absorbs heat from the gas generated in the parser, and carbon monoxide contained in the gas that has passed through the heat absorption means to oxidize and nitrify carbon monoxide. A catalyst for reducing oxygen oxide with carbon monoxide, a sensor for detecting the air ratio of the panner, and an air ratio adjusting means for controlling the air ratio of the panner to a set air ratio based on the detection signal of the sensor And when the air ratio is adjusted to the set air ratio by the air ratio adjusting means, the nitrogen gas concentration on the secondary side of the catalyst is substantially zero. It is a combustor characterized by being configured to obtain a concentration ratio of oxygen, nitrogen oxides, and carbon monoxide on the primary side of the catalyst.

[0043] The set air ratio is preferably controlled to a set air ratio of 1. As a result of the reaction at the catalyst, the oxygen concentration on the primary side of the catalyst that can satisfy the set air ratio of 1 is a predetermined concentration. The air ratio can also be controlled so that Further, “when adjusting to the set air ratio by the air ratio adjusting means, the concentration of nitrogen oxides on the secondary side of the catalyst is substantially zero, and the oxygen, nitrogen oxides on the primary side of the catalyst and “The concentration ratio of carbon monoxide can be obtained” is satisfied at the set air ratio.

[0044] In an embodiment of the present invention, the burner burns while the air ratio is controlled to the set air ratio by the air ratio adjusting means. The gas generated by combustion is subjected to an endothermic action by the endothermic body, and then the carbon monoxide is oxidized by the catalyst and the nitrogen oxide is reduced. As a result, the emission of nitrogen oxides in the gas is reduced to a value close to zero of 5 ppm or less. In addition, carbon monoxide emission is reduced. Here, when the nitrogen oxide concentration on the secondary side of the catalyst is substantially zero, the nitrogen oxide concentration is 5 ppm, preferably 3 ppm, and more preferably Oppm.

[0045] According to an embodiment of the present invention, the air ratio is adjusted by the air ratio adjusting means. By controlling to a constant air ratio, a concentration ratio of oxygen, nitrogen oxides, and carbon monoxide on the primary side of the catalyst can be obtained in which the nitrogen oxide concentration on the secondary side of the catalyst is substantially zero.

[0046] In low air ratio control, stable air ratio control is difficult, but the air ratio adjusting means includes an electrical control means and Z or mechanical control means for stably controlling the air ratio. By doing so, stable air ratio control can be performed.

[0047] The concentration ratio adjustment on the primary side of the catalyst is preferably such that the concentration of carbon monoxide in the gas on the primary side of the catalyst is reduced in the catalyst by oxidation of carbon monoxide (first reaction). It is almost equal to or higher than the sum of the concentration of carbon monoxide and the concentration of carbon monoxide reduced in the catalyst by the reduction of nitrogen oxides with carbon monoxide (second reaction). Controlled.

[0048] This reduction action is considered to be performed as follows. In a gas that does not contain HC (hydrocarbon), the catalyst generates, as the main reaction, a first reaction that oxidizes carbon monoxide and a second reaction that reduces nitrogen oxides with carbon monoxide. ing. In the reaction (catalytic reaction) in the catalyst, in the presence of oxygen, the first reaction is superior to the second reaction, and carbon monoxide is consumed by oxygen based on the first reaction. After the concentration is adjusted, the nitrogen oxides are reduced by the second reaction. This description is simplified. Actually, the first reaction is a competitive reaction with the second reaction, but the reaction between carbon monoxide and oxygen occurs apparently faster in the presence of oxygen than the second reaction. It is considered that the first reaction is performed in the stage and the second reaction is performed in the second stage.

In short, in the catalyst, in the presence of oxygen, CO + 1/20 → CO

2 2 Oxygen is consumed by the first reaction, and using the remaining CO, 2CO + 2NO → N2 + 2CO

2 By the second reaction, the nitrogen oxides are reduced and the concentration of exhausted nitrogen oxides is reduced.

[0050] Here, in the description of the above reaction formula, NO is used without using NOx. The composition of the generated nitrogen oxide in the high temperature field is NO as the main component, and NO is a number % Over

2

This is because it can be described approximately. NO, if present, is the same as NO It is thought that it is reduced by CO.

[0051] The panner and the endothermic body are configured to adjust the concentration ratio by both. In this case, the panner and the endothermic body have the following air ratio NOx′CO characteristics. This air ratio-one NOx'CO characteristic is obtained when the air ratio is adjusted to the set air ratio by the air ratio adjusting means so that the concentration of nitrogen oxides on the secondary side of the catalyst is substantially zero. The concentration ratio of oxygen, nitrogen oxides, and carbon monoxide in the primary gas can be obtained. The air ratio-one NOx'CO characteristic is preferably such that the concentration of the nitrogen oxides on the primary side of the catalyst is 300 ppm or less. By doing so, the amount of the catalyst used can be reduced.

[0052] The concentration ratio adjustment by the PANA and the endothermic material is performed by obtaining an air ratio-one NOx'CO characteristic based on experimental data. By adjusting the concentration ratio, the carbon monoxide concentration in the gas on the primary side of the catalyst is reduced in the catalyst by the oxidation of carbon monoxide and the monoacid acid and nitrogen monoxide monoacids. If the concentration ratio cannot be adjusted to a value that is approximately equal to or greater than the sum of the concentration of carbon monoxide and carbon that is reduced in the catalyst by reduction with carbon, it is It can be configured to adjust by carbon injection or oxygen injection.

[0053] In this concentration ratio, if the air ratio is controlled to a set air ratio of substantially 1, it is preferable to achieve energy saving. In addition, the concentration ratio adjustment is preferably performed by suppressing the nitrogen oxide amount and the carbon monoxide amount to a predetermined amount or less by adjusting the combustion temperature and reducing the carbon monoxide concentration obtained by maintaining the gas temperature. This is done by not reducing it. Carbon monoxide carbon is easily oxidized when the gas temperature is about 900 ° C. or higher. Therefore, it is preferable that the gas flow at the primary side of the catalyst is maintained at 600 ° C. or lower so that the gas temperature is maintained at 600 ° C. or lower. The above-mentioned heat sink is constituted.

[0054] An expression representing the range of the concentration ratio can be expressed by the following expression (1).

([NOx] + 2 [0]) /[CO]≤2.0

2

Indicates the concentration of oxide and oxygen, satisfying the condition [o]> 0. )

2

Here, the value of ([NOx] + 2 [0]) Z [CO] (concentration ratio value) should be 2.0 or less, but it is preferable. Or 1.5 or less. The nitrogen oxide concentration ([NOx]) is the total concentration of the nitric oxide concentration ([NO]) and the diacid nitrogen concentration ([NO]). Further, the above formula (1) is satisfied.

2 Concentration ratio of carbon monoxide concentration, nitrogen oxide concentration, and oxygen concentration is the predetermined concentration ratio.

[0055] When the value of the predetermined concentration ratio is 1, theoretically, the oxygen concentration, nitrogen oxide concentration, and carbon monoxide concentration discharged from the catalyst can be made zero. On the other hand, in the experiment, a small amount of carbon monoxide is emitted. ([NOx] +2 [0] = l in the formula (1) is based on the experimental result,

2]) Z [CO reaction and second reaction stress Theoretically derived.

[0056] When the value of the predetermined concentration ratio is smaller than 1, the concentration of carbon monoxide is higher than the concentration necessary for the reduction of the nitrogen oxides, so the exhaust oxygen concentration is zero, and the catalyst Carbon monoxide remains in the gas after passing. For this reason, the lower limit of the concentration ratio in the formula (1) is not provided. When carbon monoxide is contained after passing through the catalyst, it is preferable to further provide an oxidizing means for oxidizing the residual carbon monoxide. The oxidation means can be configured to provide a catalyst separate from the catalyst and oxidize carbon monoxide by introducing oxygen upstream of the catalyst.

[0057] Further, the concentration ratio value exceeding 1.0 of 2.0 is considered to be due to the following reason, which is an experimentally obtained value. The reaction occurring in the catalyst has not been completely elucidated, and it is considered that a side reaction occurs in addition to the main reaction of the first reaction and the second reaction. As one of the side reactions, hydrogen is generated by the reaction between steam and carbon monoxide, and nitrogen oxide and oxygen are reduced by this hydrogen.

Next, the components of the embodiment of the present invention will be further described. The panner is preferably an all-primary air premixed panner that premixes and burns gas fuel. In order to effectively cause the first reaction and the second reaction to occur in the catalyst, the concentration ratio as shown in the above formula (1) for oxygen, nitrogen oxides, and carbon monoxide is reduced. is important. By using the premixing burner as the burner, the predetermined concentration ratio can be obtained relatively easily in a low air ratio region. However, if the oxygen, nitrogen oxides, and carbon monoxide in the gas on the primary side of the catalyst are uniformly mixed and the respective concentrations can be controlled to the predetermined concentration ratio, a premixing panner is used. Can be other than PANA wear.

[0059] Further, the oxygen concentration O on the primary side of the catalyst is 0% under the condition of satisfying the formula (1).

2

If <0 ≤1.00%, the air ratio is almost 1 and the exhaust concentration is close to zero, low NOx and low C

2

In addition to o, energy saving is realized, and it is possible to provide a low-pollution, energy-saving combustion device.

[0060] Further, the heat absorber is a water pipe when the combustion apparatus is a boiler, and an absorbing liquid concentrating pipe when it is a regenerator. The endothermic body also has a function of controlling the gas temperature flowing into the catalyst close to the activation temperature of the catalyst. That is, the gas temperature is controlled to a temperature that effectively causes the first reaction and the second reaction, suppresses deterioration due to temperature, and considers durability.

[0061] The catalyst is a catalyst having a function of reducing the nitrogen oxides in a state where HC is not contained in the gas, and has a structure in which a catalytically active substance is supported on a base material having air permeability. As the base material, metals such as stainless steel and ceramics are used, and a surface treatment is applied to widen the contact area with the exhaust gas. Platinum is generally used as the catalytically active material, but depending on the implementation, noble metals represented by platinum (Ag, Au, Rh, Ru, Pt, Pd) or metal oxides should be used. Can do.

[0062] The air ratio adjusting means includes a flow rate adjusting means, a motor for driving the flow rate adjusting means, and a control means for controlling the motor. The flow rate adjusting means is a means for adjusting the air ratio of the burner by changing one or both of the burner air amount and fuel amount of the burner to change the ratio between them. In the case of adjusting the amount of combustion air, a damper (including the meaning of a valve) is preferably used. The structure of this damper includes a rotary type that changes the opening degree of the flow path by a valve body that rotates around a rotating shaft, and a slide type that changes the opening degree of the flow path by sliding with respect to the cross-sectional opening of the flow path. It can be done.

[0063] When this flow rate adjusting means changes the amount of combustion air, it is preferably provided in the air flow path between the blower and the fuel supply means, but the suction port of the blower such as the suction port of the blower. Can be provided on the side.

[0064] The motor is preferably means for driving the flow rate adjusting means, and the flow rate adjusting means. A motor that can control the amount of opening of the adjusting means according to the drive amount and that can adjust the drive amount per unit time. This motor constitutes a part of “mechanical control means” for stably controlling the air ratio of the present invention. The phrase “the amount of opening can be controlled according to the amount of driving” means that the opening of the flow rate adjusting valve can be stopped at a specific position if the amount of driving is determined. Further, “the drive amount per unit time can be adjusted” means that the responsiveness of the position control can be adjusted.

[0065] This motor is preferably a force gear motor (which can be called a geared motor), a servo motor, or the like, which is a stepping motor (which can be called a step motor). In the case of the stepping motor, it is a driving pulse to which the driving amount is applied, and the opening position of the flow rate adjusting means is opened and closed by an amount corresponding to the number of reference opening position force driving pulses, and is arbitrarily set. The target stop position can be controlled. In the case of the gear motor or the servo motor, the driving amount is the opening / closing driving time, and the opening position of the flow rate adjusting means is opened / closed by an amount corresponding to the reference opening position force opening / closing driving time. It can be controlled to any desired stop position.

[0066] The sensor represents an excess oxygen concentration in an oxygen excess region, and a negative oxygen concentration necessary for burning unburned gas such as carbon monoxide carbon at an air ratio m = l in a fuel excess region. An oxygen concentration meter expressed as the value of can be suitably used.

In addition, as the sensor, an air ratio can be obtained approximately by combining an oxygen concentration sensor and a carbon monoxide concentration sensor.

The mounting position of the sensor as described above is preferably the secondary side of the catalyst, but is not limited to this, and the exhaust heat recovery is performed on the primary side of the catalyst or on the downstream side of the catalyst. If a vessel is provided, this can be the downstream side.

[0068] Based on an air ratio control program stored in advance, the control means inputs the detection value of the sensor, feedback-controls the driving amount of the motor, and controls the primary gas in the primary side of the catalyst. The oxycarbon concentration is approximately equal to the value obtained by adding the concentration of carbon monoxide reduced in the catalyst by the acid and the concentration of carbon monoxide reduced in the catalyst by the reduction, or The air ratio is controlled to a set air ratio of 1 so as to satisfy the above or to satisfy the formula (1). [0069] Preferably, the air ratio control program can be expressed as a drive amount per unit time of the motor (time per drive unit) according to a difference between the detected air ratio and the set air ratio. )) And a second control zone outside the first control zone and a second control zone in which the driving amount per unit time is a fixed predetermined value so as to control the driving amount of the motor. Configure. This control constitutes the electrical control means for controlling so that the detected air ratio of the present invention falls within a set range centered on the set air ratio. Note that the air ratio control program is not limited to this control method, and can be various PID controls. The control amount in the first control zone can be controlled by the product of the difference between the detected air ratio and the set air ratio and the set gain. By such control, it is possible to quickly control the set air ratio and to achieve an effect of performing control with less overshoot and notching.

[0070] The concentration ratio adjustment by the burner and the endothermic body includes a form which is performed by an element constituting the gas passage to the burner and the catalyst other than the endothermic body and an element included in the gas passage.

[0071] Further, the mechanical control means comprises a combustion air supply passage comprising a main passage and an auxiliary passage in parallel therewith, and the air flow rate is roughly adjusted by the operation of a valve body provided in the main passage. The air flow rate can be finely adjusted by the operation of the valve provided in the auxiliary passage. Further, the mechanical control means comprises a fuel supply passage comprising a main passage and an auxiliary passage in parallel therewith, and the air flow rate is roughly adjusted by the operation of a valve provided in the main passage, and is provided in the auxiliary passage. The air flow rate can be finely adjusted by the operation of the valve body.

Example 1

[0072] Next, an embodiment in which the combustion apparatus of the present invention is applied to a steam boiler will be described with reference to the drawings. FIG. 1 is an explanatory view of a longitudinal section of the steam boiler of the first embodiment, FIG. 2 is a sectional view taken along line II-II in FIG. 1, and FIG. 3 is a flow direction of exhaust gas through the catalyst of FIG. Fig. 4 is a diagram illustrating the air ratio NOx'CO characteristic of the first embodiment, and Fig. 5 is a diagram illustrating the use of the damper position adjusting device of the first embodiment. FIG. 6 is an explanatory diagram of a partial cross section of the damper position adjusting device in use, and FIG. 7 is a diagram illustrating the output characteristics of the sensor of the first embodiment. Figure 8 shows the motor control characteristics of Example 1. FIG. 9 is a diagram illustrating the NOx and CO reduction characteristics of the first embodiment.

[0073] First, the steam boiler of this example will be described. This steam boiler is composed of a can 3 including a heat exchanger tube (water tube) group 2 as a heat absorption means for absorbing heat generated by the gas generator 1 and the gas generated from the heat generator tube 1, and the oxygen after passing through the heat transfer tube group 2. , A gas containing nitrogen oxide and carbon monoxide at a predetermined concentration ratio passes through them, and the gas fuel is supplied to the catalyst 4 that oxidizes the carbon monoxide and reduces the nitrogen oxide, and to the above-mentioned Parner 1. A fuel supply means 5 for supplying the combustion air to the burner 1, and a combustion air supply means 6 for premixing the combustion air and fuel, a sensor 7 for detecting the oxygen concentration downstream of the catalyst 4, and A controller 8 as a boiler controller that inputs a signal from the sensor 7 or the like and controls the fuel supply means 5, the combustion air supply means 6 and the like is provided as a main part.

[0074] The burner 1 is a complete premix burner having a flat combustion surface (a premixed gas ejection surface). This panner 1 has the same configuration as the panner described in Patent Document 1.

The can body 3 includes an upper header 9 and a lower header 10, and a plurality of inner water tubes 11, 11,... Constituting the water tube group 2 are arranged between the headers. Then, as shown in FIG. 2, a pair of water pipe walls 14, 14 formed by connecting outer water pipes 12, 12,... With connecting members 13, 13,. A first gas passage 15 is formed between the water pipe walls 14 and 14 and the upper header 9 and the lower header 10 so that the gas from the Parner 1 flows almost linearly. One end of the first gas passage 15 is provided with the above-described Parner 1, and a second gas passage (smoke) 17 through which exhaust gas flows is connected to the exhaust gas outlet 16 at the other end. In the first embodiment, the parner 1 and the can 3 are known ones.

The second gas passage 17 includes a horizontal part 18 and a vertical part 19, and the catalyst 4 is attached to the horizontal part 18. A feed water preheater 20 as an exhaust heat recovery device is attached to the vertical portion 19 so as to be located downstream of the catalyst 4, and the sensor 7 is disposed between the catalyst 4 and the feed water preheater 20. ing.

[0077] The components from the Parner 1 including the Parner 1 and the pre-water pipe group 2 to the catalyst 4 adjust the predetermined concentration ratio in the gas on the primary side of the catalyst 4. sand That is, the air ratio is adjusted to the set air ratio by an air ratio adjusting means 28, which will be described later, so that the air ratio 1ΝΟχ · CO characteristic shown in FIG. 4 can be obtained. This air ratio one NOx · CO characteristic is the above-mentioned in the primary side gas of the catalyst 4 in which the nitrogen oxide concentration on the secondary side of the catalyst 4 is substantially zero when adjusted to the set air ratio. A predetermined concentration ratio is obtained. This air ratio 1 NOx 'CO characteristic is a novel characteristic of the low air ratio region that has been studied so far.

[0078] The catalyst 4 oxidizes carbon monoxide and carbon contained in the gas not containing HC after passing through the water tube group 2 (first reaction) and reduces nitrogen oxides (second reaction). In Example 1, a catalyst having a catalytically active material as platinum is used. As described in the section of “Best Mode for Carrying Out the Invention”, the gas and the catalyst satisfying the concentration ratio formula of the formula (1) are theoretically considered based on the experimental results. It is considered that the contact with the catalytically active substance 4 mainly causes a first reaction that oxidizes carbon monoxide and a second reaction that reduces nitrogen oxides with monoxide carbon. Whether or not the reaction proceeds in the first reaction is determined depending on the oxygen concentration. In the catalyst 4, the first reaction is considered to be superior to the second reaction.

[0079] The catalyst 4 will be described more specifically. This catalyst has a structure as shown in FIG. 3, and is formed as follows, for example. A large number of minute irregularities are formed on the surfaces of the flat plate 21 and the corrugated plate 22 made of stainless steel as the base material, and a catalytically active material (not shown) is supported on the surfaces. Next, the flat plate 21 and the corrugated plate 22 having a predetermined width are overlapped with each other and then wound into a spiral shape to form a roll. This roll-shaped product is surrounded and fixed by the side plate 23. Platinum is used as the catalytically active material. In FIG. 3, only a part of the flat plate 21 and the corrugated plate 22 is shown.

[0080] The catalyst 4 has oxidation activity in a low temperature region, and is disposed in the horizontal portion 18 in the middle of the second gas passage 17, at an exhaust gas temperature of about 100 ° C to 350 ° C. Has been. The catalyst 4 is detachably attached to the second gas passage 17 so that it can be replaced when the performance deteriorates! Speak.

[0081] The fuel supply means 5 includes a gas fuel supply pipe 24 and a fuel provided in the gas fuel supply pipe 24. It is configured to include a flow rate adjusting valve 25 for adjusting the charge flow rate. The flow rate adjusting valve 25 has a function of controlling the fuel supply amount to a high combustion flow rate and a low combustion flow rate.

The combustion air supply means 6 adjusts the amount of combustion air that flows through the air blower 26, the air supply passage 27 that supplies the combustion air from the air blower 26 to the burner 1, and the air supply passage 27. The air ratio adjusting means 28 for adjusting the air ratio of the PANA 1 is included. The gas fuel supply pipe 24 is connected to the air supply passage 27 so as to eject fuel gas.

[0083] The air ratio adjusting means 28 is a damper 29 as a flow rate adjusting means for adjusting the opening degree (flow passage cross-sectional area) of the air supply passage 27, and the opening position of the damper 29 is adjusted. The damper position adjusting device 30 and the controller 8 for controlling the operation of the damper position adjusting device 30 are configured.

As shown in FIG. 5, the damper position adjusting device 30 includes a drive shaft 32 that is detachably connected to the rotary shaft 31 of the damper 29. The drive shaft 32 is connected via a speed reducer 33. It can be rotated by motor 34. As the motor 34, a motor capable of arbitrarily adjusting the rotation stop position is used. In this embodiment, a stepping motor (pulse motor) is used.

The drive shaft 32 is connected to the rotary shaft 31 of the damper 29 via a coupling 35 so that the drive shaft 32 can rotate integrally on substantially the same axis. The coupling 35 has a stepped columnar shape, and a small diameter hole 36 and a large diameter hole 37 are formed in the central portion thereof so as to penetrate in the axial direction. The drive shaft 32 is inserted into the small diameter hole 36, and the drive shaft 32 is integrated with the coupling 35 with a mounting screw 38. On the other hand, a rotary shaft 31 of the damper 29 can be inserted into the large-diameter hole 37, and the rotary shaft 31 can rotate integrally with the coupling 35 by a key 39. For this purpose, key grooves 40 and 41 are formed in the large-diameter hole 37 of the rotary shaft 31 and the coupling 35, respectively.

Such a coupling 35 is rotatably held by the outer case 43 of the damper position adjusting device 30 through the bearing 42 at the other end with the drive shaft 32 inserted at one end. It is. In the outer case 43, the speed reducer 33 and the motor 34 are held at one end, and the large diameter hole 37 with the keyway 41 of the coupling 35 is exposed at the other end. Thus, the coupling 35 and the rotation abnormality detection means 44 are sealed inside.

The rotation abnormality detecting means 44 includes a detected plate 45 and a detector 46. The detected plate 45 is fixed to the stepped portion at the axially central portion of the coupling 35 so as to extend radially outward. The detection plate 45 is provided concentrically with the coupling 35 and the drive shaft 32. A slit forming region 48 in which a large number of slits 47, 47... Are formed at equal intervals in the circumferential direction is provided in a part of the outer peripheral portion of the detection plate 45. In the present embodiment, the slit forming region 48 is provided for the arc of a quarter (90 degrees). The slits 47 formed in the slit formation region 48 have the same shape and size. In this embodiment, elongated rectangular grooves along the radial direction of the plate 45 to be detected are punched and formed at equal intervals along the circumferential direction.

The detector 46 for detecting the slit 47 is fixed to the outer case 43. The detector 46 is a transmissive photointerrupter, and is attached in a state where the outer peripheral portion of the detection plate 45 is interposed between the light emitting element 49 and the light receiving element 50. By interposing the detection plate 45 between the light emitting element 49 and the light receiving element 50 of the detector 46, a position corresponding to the detector 46 (from the light emitting element 49 to the light receiving element 50). Whether the light receiving element 50 receives light from the light emitting element 49 or not is switched depending on whether the slit 47 of the detection plate 45 is disposed at a position corresponding to the optical path). Thereby, the opening position of the damper 29 can be detected.

[0089] The damper position adjusting device 30 has the damper 29 in the state in which the clockwise end slit 51 of the slit forming region 48 in Fig. 6 is disposed at a position corresponding to the detector 46. The air supply passage 27 is positioned so as to be fully closed, and is attached to the rotary shaft 31 of the damper 29.

[0090] Since the slit forming region 48 is formed by 90 degrees of the detection plate 45, the clockwise end slit 51 of the slit forming region 48 corresponds to the detector 46. In this state, the damper 29 fully closes the air supply passage 27 as described above, while the counter slit 52 in the counterclockwise direction of the slit forming region 48 corresponds to the detector 46. In the state of being arranged in the above position, the damper 29 will open the air supply passage 27 fully. In the damper position adjusting device 30, the motor 34 and the detector 46 are connected to the controller 8, and the rotation of the motor 34 is controlled while monitoring the rotation abnormality of the damper 29. It is configured to be able to. That is, in order to control the motor 34, the damper position adjusting device 30 has a generation circuit of a control signal including a drive pulse to the motor 34, and the generated control signal can be output to the motor 34. It is. Thereby, the rotation angle of the motor 34 is arbitrarily controlled in accordance with the forward rotation or reverse rotation and the drive amount, that is, the number of drive pulses. In addition, the rotation speed can be controlled by changing the interval (feed speed) of the drive noise.

When actually opening and closing the damper 29, the controller 8 first performs an origin detection operation in order to set the fully closed position of the damper 29 as the origin. First, in FIG. 5, the detected plate 45 is rotated counterclockwise. Now, assuming that the detector 46 is disposed in the slit forming region 48 of the plate 45 to be detected, the detector 46 is periodically inserted into the slit 47 as the plate 45 is rotated. Therefore, the detected pulse is input to the controller 8 as a detection signal. Then, when the detection plate 45 is rotated until the detector 46 is disposed outside the slit forming region 48, no nose is detected. If the pulse is not detected for a predetermined time, the controller 8 recognizes that the detector 46 is outside the slit forming region 48 and switches the rotation direction to the reverse direction. That is, in the present embodiment, the detected plate 45 is rotated in the clockwise direction, and the position where the pulse (the end slit 51 in the clockwise direction) is first detected is set as the origin. The origin check by this clockwise rotation is performed at a lower speed than the counterclockwise rotation before switching the rotation direction.

[0093] Since the origin detected in this way corresponds to the fully closed position of the damper 29, the controller 8 outputs a drive signal to the motor 34 based on this state, The damper 29 can be controlled to open and close. When the controller 8 drives the motor 34 to open and close the damper 29, the detection signal of the slit 47 is acquired as a pulse from the detector 46 accordingly. Therefore, the controller 8 can monitor the rotation abnormality of the damper 29 by comparing the detection signal from the detector 46 with the control signal to the motor 34. Specifically, a control signal that also has a driving pulse force to the motor 34 is compared with a detection signal that also has a detection pulse force of the slit 47 by the detector 46, and Monitor for abnormal rotation.

[0094] For example, when a detection pulse is not detected from the detector 46 even though a driving noise is sent to the motor 34, the controller 8 determines that the rotation is abnormal. At this time, since the detection pulse from the detector 46 is usually different from the frequency of the drive pulse to the motor 34, it is controlled in consideration of this difference. For example, if no pulse of the detection signal is detected even after the time corresponding to a predetermined pulse of the drive signal has elapsed, control is performed so that a rotation abnormality is determined for the first time. When it is determined that the rotation is abnormal, the controller 8 performs measures such as notifying abnormality and stopping combustion. Conversely, when a pulse is detected from the detector 46 even though no driving pulse is sent to the motor 34, a rotation abnormality can be detected.

[0095] The controller 8 uses a prestored air ratio control program so that the air ratio of the banner 1 becomes the set air ratio based on the detection signal of the sensor 7 (first control condition). The motor 34 is controlled such that the concentration ratio of the gas on the primary side of the catalyst 4 satisfies the following formula (1) (second control condition) at the set air ratio.

([NOx] + 2 [0]) /[CO]≤2.0

2

Indicates the concentration of oxide and oxygen, and [o]> 0

2 Satisfy the condition. )

In this embodiment, the first control condition is directly controlled, and the second control condition is automatically satisfied by satisfying the first control condition.

[0096] When the first condition is not satisfied, an unburned component such as HC is generated. In this case, energy is lost and NOx reduction in the catalyst 4 is not effectively performed.

[0097] The second condition is a condition necessary to make the exhausted nitrogen oxide concentration substantially zero.

In order to make the nitrogen oxide concentration and the carbon monoxide concentration on the secondary side of the catalyst 4 zero, from the first reaction and the second reaction, ([NOx] + 2 [0

2]) It was found from experiments and theoretical considerations that the concentration ratio of Z [CO] should be approximately 1. However, it has been confirmed that the concentration of discharged nitrogen oxides can be made substantially zero even if the concentration ratio is 1 to 2.0 of 1 or more. ing.

[0098] As the sensor 7, a zirconia air-fuel ratio sensor with a good response and a response time of 2 sec or less with a resolution of exhaust oxygen concentration of 50 ppm is used. As shown in FIG. 7, the output characteristic of the sensor 7 is an output related to the oxygen concentration on the positive side and an output related to the carbon monoxide concentration on the negative side. That is, the measured oxygen concentration (excess oxygen region), carbon monoxide concentration, etc. (fuel excess region) force air ratio m is calculated, and current or voltage output corresponding to this air ratio m is obtained.

[0099] The air ratio control program is a force for controlling the air ratio of the burner to be a set air ratio based on the output signal of the sensor 7. Specifically, the air ratio control program is as follows. It is configured. That is, as shown in FIG. 7, the first feed rate V (drive amount per unit time) of the motor 34 is changed according to the difference between the output value from the sensor 7 and the set value corresponding to the set air ratio. Control for controlling the drive amount of the motor 34 by providing a control zone and second control zones A and B having the feed rate V as the first set value and the second set value, respectively, outside the first control zone. Instructions are included.

[0100] The setting range of the first control zone is set with an oxygen concentration N1 (for example, lOOppm) and a carbon monoxide concentration or the like N2 (for example, 50ppm), and is controlled so that the air ratio is substantially 1. .

[0101] The feed speed V in the first control zone is calculated by the following equation (2). The feed speed V is a driving amount per unit time. The rotation angle of the motor 34 in this embodiment in one step is 0.075 degrees, which corresponds to a fluctuation of about 30 ppm when converted to O.

(Where Κ is a gain, and ΔΧ is a difference from (the output value of the sensor 7) (the set value).)

Next, the operation of the steam boiler having the above configuration will be described. First, regarding the schematic operation of the steam boiler, the combustion air (outside air) supplied from the blower 26 is premixed in the supply passage 27 with the fuel gas supplied from the gas fuel supply pipe 24. This premixed gas is ejected from the burner 1 toward the first gas passage 15 in the can 3. The premixed gas is ignited by an ignition means (not shown) and burns. This combustion takes place at a low air ratio. [0103] The gas generated by this combustion is cooled by crossing with the upstream water tube group 2 and then absorbed by heat exchange with the downstream water tube group 2 to obtain a gas of about 100 ° C to 350 ° C. It becomes. This gas is treated by the catalyst 4 and the nitrogen oxide concentration and the carbon monoxide concentration are made substantially zero, and then discharged from the second gas passage 17 to the atmosphere as exhaust gas.

Next, the air ratio control by the air ratio adjusting means 28 will be described. The boiler of this embodiment is operated by switching between high combustion and low combustion. For this purpose, the damper 29 is positioned by selecting either! / Or a deviation between the high combustion air volume position and the low combustion air volume position.

The position adjustment of the damper 29 is performed by the damper position adjusting device 30 in accordance with a command from the controller 8. That is, the controller 8 inputs a selection signal for high combustion / low combustion and an output value corresponding to the detected air ratio of the sensor 7, and outputs a drive signal for the motor 34, Adjust the opening position of damper 29. The controller 8 stores the set opening position of the damper 29, which is a set value corresponding to the set air ratio at the time of high combustion and low combustion, as an initial value in terms of the number of pulses of the origin force.

First, control during high combustion will be described. The controller 8 controls the current opening position of the damper 29 relative to the set opening position (open side if not controlled in the closing direction) or closed side (opened direction). If not, it is determined whether the motor side is) and the number of driving noises of the motor 34 is calculated. In addition, in FIG. 8, it is determined whether the output value belongs to a deviation between the first control band and the second control band A, B.

When belonging to the second control zone A, the motor 34 is driven at the first set feed speed and the calculated drive pulse, and the damper 29 is closed at a high speed. When belonging to the second control zone B, the motor 34 is driven at the second set feed speed and the calculated drive pulse, and the damper 29 is opened at a high speed. In this way, when the set value force corresponding to the set air ratio is relatively far away, the output value corresponding to the detected air ratio is controlled to approach the set value corresponding to the set air ratio at a high speed, so the responsiveness is good. Air ratio control can be performed.

[0108] Further, when belonging to the first control zone, after determining the rotation direction, the feed rate of the motor 34 is calculated based on the formula (2), and the calculated feed rate and the calculated drive are calculated. The motor 34 is driven with a pulse. The control in the first control zone is effective against the set air ratio. Increase the feed rate as you move away from the set value. By such control, it is possible to quickly approach the set value corresponding to the target set air ratio. In addition, it is controlled by a stepping motor that can reliably control the rotational position, and the feed rate is controlled to decrease as the output value corresponding to the detected air ratio approaches the set value corresponding to the set air ratio. Thus, overshooting and notching of the air ratio in the vicinity of the set value corresponding to the air ratio can be suppressed.

[0109] By such air ratio control, the air ratio of the Parner 1 is controlled to be a low air ratio close to 1, and the change ratio of the concentration ratio of the gas on the primary side of the catalyst 4 is controlled to be small. It can be satisfied stably. As a result, the nitrogen oxide concentration on the secondary side of the catalyst 4 can be made substantially zero, and the carbon monoxide concentration can be reduced to a value within the practical range.

(Experiment 1)

[0110] A can body 3 with an evaporation amount of 800 kg per unit time (applicant's manufacturing model: can body called SQ-800) was burned with a premixing burner 1 with a combustion amount of 45.2 m ³ N / h. The experimental results for a catalyst with a volume of 10L and an inner diameter of 360mm that support Pt at a rate of 2. OgZL as the catalytically active substance will be explained. When the set air ratio is 1, the carbon monoxide concentration, nitrogen oxide concentration, and oxygen concentration on the primary side of catalyst 1 (before passing through catalyst 4) are 2295 ppm, 94 ppm, The concentration on the secondary side of the catalyst 1 (after passing through the catalyst 1) was adjusted to 1655 ppm, and the average value for 10 minutes was less than 13 ppm, 0.3 ppm, and lOOppm. Here, the oxygen concentration lOOppm on the secondary side of the catalyst 1 is an oxygen concentration measurement limit (measured using PG-250 manufactured by Horiba, Ltd.).

(Experiment 2)

[0111] The same Pana 1 and Can 3 as in Experiment 1 were used, the combustion amount was the same as in Experiment 1, and Pd was supported as a catalyst active material at a ratio of 2. OgZL. Figure 9 shows the values for the carbon monoxide concentration, nitrogen oxide concentration, and oxygen concentration ratio. Here, since the oxygen concentration after passing through the catalyst was measured using the same oxygen concentration sensor as in Experimental Example 1, even if the value was actually less than lOOppm, it was indicated in lOOppm.

Example 2

[0112] Another embodiment 2 of the present invention will be described with reference to Figs. This Example 2 is an acid A sensor 7 for detecting the element concentration is provided on the primary side connecting the secondary side of the catalyst 4. This sensor 7 is a sensor that detects only the oxygen concentration. FIG. 11 shows the control characteristics of the motor 34 based on the sensor 7. Hereinafter, only different points from the first embodiment will be described, and description of common parts will be omitted.

[0113] In Example 2, the sensor 7 detects the primary side oxygen concentration of the catalyst 4 so that the set air ratio is 1 (the secondary side oxygen concentration of the catalyst 4 is zero). It indirectly controls the air ratio. Based on various experimental results, when the oxygen concentration O on the primary side of the catalyst 4 is controlled to 0% and O ≦ 1.00%, the above equation (1) is satisfied and the catalyst 4

twenty two

It is known that the oxygen concentration on the secondary side can be made almost zero, that is, the air ratio can be made almost 1.

Therefore, in the air ratio control program of the second embodiment, as shown in FIG. 11, based on the detected value (oxygen concentration signal) from the sensor 7, the detected value and the set oxygen concentration value are A first control zone that changes the feed rate V (drive amount per unit time) of the motor 34 according to the difference, and a feed rate V outside the first control zone is set to a first set value and a second set value, respectively. A control procedure for controlling the drive amount of the motor 34 by providing the second control zones A and B to be included is included.

[0115] The setting range of the first control zone is controlled to fall within the range set by the oxygen concentration N1 and the oxygen concentration N2. The feed speed V in the first control zone is calculated by the above equation (2) as in the first embodiment.

[0116] The present invention is not limited to the above embodiments. For example, in the second embodiment, a force carbon monoxide concentration sensor in which the sensor 7 is an oxygen concentration sensor can be used. The structure of the damper position adjusting device 30 can be variously modified. The motor 34 may be a gear motor (not shown) other than the stepping motor. Further, a force that controls the damper position adjusting device 30 with a single controller (a controller for boiler control) 8 Aside from this controller 8, another controller for the damper position adjusting device 30 (illustrated) (Omitted) and this controller can be connected to the front sensor 7 and the controller 8 to perform air ratio control.

Claims

The scope of the claims

[1] With Pana,

An endothermic means for absorbing heat from the gas generated by the panner;

A catalyst that oxidizes carbon monoxide contained in the gas after passing through the endothermic means and reduces nitrogen oxides with carbon monoxide;

A sensor for detecting the air ratio of the panner;

An air ratio adjusting means for controlling the air ratio of the panner to a set air ratio based on a detection signal of the sensor,

When the air ratio is adjusted to the preset air ratio by the air ratio adjusting means, the panner and the endothermic means have a primary nitrogen oxide concentration on the secondary side of the catalyst that is substantially zero. Combustion device configured to obtain a concentration ratio of oxygen, nitrogen oxide, and carbon monoxide on the side.

[2] With Pana,

An endothermic means for absorbing heat from the gas generated by the panner;

A sensor for detecting the air ratio of the panner;

When the air ratio is adjusted to the preset air ratio by the air ratio adjusting means, the panner and the endothermic means have an air ratio NOx ′ that makes the nitrogen oxide concentration on the secondary side of the catalyst substantially zero. Combustion device characterized by having CO characteristics.

[3] With Pana,

An endothermic means for absorbing heat from the gas generated by the panner;

A sensor for detecting the air ratio of the panner;

Based on the detection signal of the sensor, the air ratio of the panner is controlled to the set air ratio. A ratio adjustment means,

When the air ratio is adjusted to the preset air ratio by the air ratio adjustment means, the carbon monoxide concentration in the gas on the primary side of the catalyst is reduced in the catalyst by the oxidation. The carbon monoxide concentration is approximately equal to or greater than the value obtained by adding the carbon monoxide concentration reduced in the catalyst by the reduction. Combustion device.

[4] With Pana,

An endothermic means for absorbing heat from the gas generated by the panner;

A sensor for detecting the air ratio of the panner;

When the air ratio is adjusted to the preset air ratio by the air ratio adjusting means, the panner and the heat absorbing means are configured so that the concentration ratio of the gas before flowing into the catalyst satisfies the following formula (1): Combustion device characterized by comprising.

([NOx] + 2 [0]) /[CO]≤2.0

2

Indicates the concentration of oxide and oxygen, and [o]> 0

2 Satisfy the condition. )

[5] The combustion apparatus according to any one of claims 1 to 4, wherein the set air ratio is substantially 1.

[6] With Pana,

An endothermic means for absorbing heat from the gas generated by the panner;

A sensor for detecting the air ratio of the panner;

Air ratio adjusting means for controlling the air ratio of the panner based on the detection signal of the sensor, The burner and the endothermic means are used to oxidize oxygen and nitrogen on the primary side of the catalyst so that the nitrogen oxide concentration and oxygen concentration on the secondary side of the catalyst are substantially zero by controlling the air ratio of the air ratio adjusting means. Combustion device configured to obtain a concentration ratio of a product and carbon monoxide.

[7] The air ratio adjusting means includes an electric control means for stably controlling the air ratio, and Z or mechanical control means. Combustion equipment.

[8] The air ratio adjusting means includes flow rate adjusting means for controlling the air ratio of the panner;

A motor for controlling the opening of the flow rate adjusting means;

The combustion apparatus according to claim 7, further comprising: the mechanical control unit configured to use the motor as a motor that controls an opening change amount of the flow rate adjusting unit according to a driving amount.

9. The combustion apparatus according to claim 8, wherein the combustion apparatus is the motor force stepping motor.

[10] The air ratio adjusting means includes flow rate adjusting means for controlling the air ratio of the panner;

A motor for controlling the opening of the flow rate adjusting means;

The combustion apparatus according to claim 7, further comprising: an electric control unit that controls the air ratio detected by the sensor to be within a set range including the set air ratio.

11. The combustion apparatus according to claim 10, wherein the mechanical control unit is configured by using the motor as a motor that controls an amount of change in opening of the flow rate adjusting unit according to a driving amount.

[12] The electrical control means is configured to control the motor according to a difference between the detected air ratio and the set air ratio.

A first control zone for changing the drive amount per unit time and a second control zone having the drive amount as a predetermined value outside the first control zone are provided to control the drive amount of the motor. The combustion apparatus according to claim 11.

[13] Any one of claims 1 to 12, wherein the panner is a premixed panner. Or the combustion apparatus according to claim 1.