JPH0323809B2 - - Google Patents

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Publication number
JPH0323809B2
JPH0323809B2 JP58197199A JP19719983A JPH0323809B2 JP H0323809 B2 JPH0323809 B2 JP H0323809B2 JP 58197199 A JP58197199 A JP 58197199A JP 19719983 A JP19719983 A JP 19719983A JP H0323809 B2 JPH0323809 B2 JP H0323809B2
Authority
JP
Japan
Prior art keywords
gas
gas sensor
air ratio
concentration
exhaust gas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP58197199A
Other languages
Japanese (ja)
Other versions
JPS6089624A (en
Inventor
Nobuaki Murakami
Hironori Iokura
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Figaro Engineering Inc
Original Assignee
Figaro Engineering Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Figaro Engineering Inc filed Critical Figaro Engineering Inc
Priority to JP58197199A priority Critical patent/JPS6089624A/en
Publication of JPS6089624A publication Critical patent/JPS6089624A/en
Publication of JPH0323809B2 publication Critical patent/JPH0323809B2/ja
Granted legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N1/00—Regulating fuel supply
    • F23N1/02—Regulating fuel supply conjointly with air supply
    • F23N1/022—Regulating fuel supply conjointly with air supply using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/003—Systems for controlling combustion using detectors sensitive to combustion gas properties
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00—Measuring
    • F23N2225/08—Measuring temperature
    • F23N2225/10—Measuring temperature stack temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F23N2235/14—Fuel valves electromagnetically operated
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

Description

【発明の詳細な説明】[Detailed description of the invention]

この発明は、燃焼機器の排ガスによる熱損失の
減少に関するもので、ボイラーや湯沸器、火力発
電機、工業炉等に適したものである。 熱交換器は燃焼機器に関して、排ガスにより水
等の流体を加熱するものを意味する。しかしこの
明細書では、流体に限らず鉱石等の固体を排ガス
により加熱するものも熱交換器に含めるものとす
る。 燃焼機器の熱効率は、排ガスと共に未利用の熱
が運び去られることにより低下する。排ガスによ
る熱損失（以下排ガス損失と言う。）を小さくす
るには、バーナへの空気供給量を必要最小限にと
どめれば良い。 排ガス損失の減少のため、排ガス中のO2濃度
を検出して空気比を制御することが、行われてい
る。しかし実際に必要なのは、空気比を一定にす
ることではなく、黒煙の発生がなくCO等の可燃
性ガスの発生量が少ない範囲でできる限り空気比
を小さくすることである。そして最適な空気比
は、バーナの状態や燃焼負荷等により絶えず変化
する。排ガス中のO2濃度が一定でも、CO等の発
生量は変化する。またO2濃度を検出する場合、
煙道への空気の混入により、検出濃度が低下す
る。 排ガス中のCO2濃度は、燃料の種類と燃焼状態
の双方で定まる。燃料の変化による影響を除くた
めには、SO2の影響なしで空気比を制御せねばな
らない。 排ガス中の可燃性成分は、COと各種炭化水素
類（以下HCと言う。）、及びH2とからなつてい
る。これらの発生量の比も、燃料の種類やバーナ
の状態により変化する。従つて可燃性成分の検出
は、COだけではなく、これらの可燃性成分全体
に対して行うのが好ましい。 この発明は、可燃性ガスの発生量に基づいて空
気比を制御し排ガス損失を小さくすることを基本
的目的とする。そして副次的目的として、COの
みでなく可燃性ガスの全量による制御を行うこ
と、およびSO2の影響を除くことを課題とする。 この発明では、バーナからの排ガスを熱交換器
により200〜500℃程度に冷却した後に検出を行
う。バーナの上流では排ガスの温度は高く、ガス
センサは可燃性ガスに感応せず、O2濃度のみの
影響を受ける。つぎに可燃性ガスの検出は、可燃
性ガスにより抵抗値が変化する金属酸化物半導体
からなるガスセンサにより行う。このガスセンサ
は、COのみでなくH2やHC等のガスにも感応し、
可燃性ガスの総量に対応した出力を与える。次に
本発明者らは、ガスセンサにはCOへの感度が最
大でSO2への感度が最小となる特定の温度がある
ことを見出した。そしてガスセンサは、排ガス、
あるいは排ガスとセンサ加熱用のヒータとの双
方、により好ましい温度に加熱される。ガスセン
サの出力は、最適空気比からの変化で定まり、こ
の出力により空気比を最適値に制御することがで
きる。 以下に、この発明の実施例を説明する。 第１図Ａは、工業用ボイラーでＣ重油を燃料と
した際の、空気比ｍと排ガス組成の関係を示すも
のである。このボイラーは、Ｃ重油を燃料とする
と2000／hrの燃料供給量で負荷率が100％とな
るもので、このボイラーを用いて実施例を検討し
た。図のl1は負荷率30％でのCO濃度を、m1は50
％でのCO濃度を、h1は80％でのCO濃度を示す。
またm2は負荷率50％でのO2濃度を、m3とm4は
同じ負荷率での水蒸気濃度とSO2濃度とを示す。
なおO2濃度や、水蒸気やSO2の濃度は、負荷率の
影響をほとんど受けず、他の成分はN2とCO2と
である。この図から最適空気は燃焼の負荷率によ
り変化すること、及びO2濃度による制御では空
気比は最適値に保たれないことがわかる。 第１図Ｂは、Ａ重油を燃料とした場合の同じボ
イラーの排ガス組成を示す。この図でl11は負荷
率30％でのCO濃度を、m11は50％でのCO濃度
を、h11は80％でのCO濃度を示す。またm12は負
荷率50％でのO2濃度を、m13は同じ負荷率での
H2O濃度を示す。この図から、最適空気比は燃
料の種類によつても変化することがわかる。 次に第２図は、このボイラーについてのSnO2
系ガスセンサの抵抗値と空気比ｍの関係を示すも
のである。このガスセンサは、SnO2100重量部に
0.3重量部のPdを添加したもので、加熱温度は250
℃である。実験に用いた燃料はＣ重油で、曲線
l21は負荷率30％でのデータを、m21は50％での
データを、h21は80％でのデータを示す。第１図
Ａと第２図とを対照すると、ガスセンサの抵抗値
は空気比により単純に定まるのではなく、最適空
気比からずれにより定まることがわかる。この性
質は、ガスセンサの抵抗値がCO等の可燃性ガス
により定まることで、説明できる。即ち最適空気
比付近での空気比の変動を特徴づける量は、排ガ
ス中の可燃性ガス濃度の変動なのである。そして
このガスセンサの抵抗値は排ガス中の可燃性ガス
濃度により定まる。そこでガスセンサの抵抗値
は、最適空気比からのシフトを示す量として用い
ることができる。 つぎに第３図Ａ，Ｂを基に、実施例の装置の構
造を示す。燃料供給弁２と空気供給弁４を介し
て、ボイラーのバーナ６に燃量と空気とを供給す
る。バーナ６の排ガスにより、熱交換器８で給水
弁１０から送られる水を加熱し、蒸気を得る。熱
交換器８を通る過程で、排ガスの温度は200〜500
℃に低下し、排ガス中のV2O5が固化して除かれ
る。また排ガスは熱交換器８の内部で混合され、
ガスの組成が一様になる。熱交換器８と空気予熱
器１１の中間に、ガスセンサ１２と温度検出用サ
ーミスタ１４とを配置する。ガスセンサ１２に
は、可燃性ガスにより抵抗値が変化する金属酸化
物半導体を用い、排ガス中のCO、H2、HC等の
可燃性ガス濃度を検出する。そしてこのガスセン
サ１２はこれらの可燃性ガスの総濃度を検出す
る。ガスセンサ１２は、排ガスと第３図Ｂに示す
ヒータ１６とで加熱される。排ガス温度の変動
は、サーミスタ１４により検出され、ヒータ１６
への電力が変化し、ガスセンサ１２の温度は一定
に保たれる。 ガスセンサ１２の出力は、コントローラ１８に
送られ、空気比を制御する。ここでは空気供給弁
４を制御するようにしたが、燃料供給弁２、ある
いは空気供給弁４と燃料供給弁２の双方をコント
ローラ１８により制御しても良い。コントローラ
１８の詳細を第３図Ｂに示す。電源２０にガスセ
ンサ１２と負荷抵抗２２とを直列に接続し、負荷
抵抗２２への印加電圧をコンパレータ２４によ
り、基準電位と比較する。コンパレータ２４によ
り空気供給弁制御器２６を制御し、空気比を変化
させる。このようにして、空気比が最適空気比よ
りも小さい時には空気比を増し、大きい時には空
気比を減らし、空気比を最適値に保つ。ガスセン
サ１２の抵抗値は、温度により変化する。サーミ
スタ１４により排ガスの温度を検出し、基準温度
からのシフトを差動増幅器２８により検出し、可
変電源３０を制御し、ヒータ１６への印加電圧を
変化させる。このようにしてガスセンサ１２の温
度を一定にする。 ガスセンサ１２の材料には、可燃性ガスにより
抵抗値が変化する金属酸化物半導体を用いる。ガ
スセンサ１２の材料として最も好ましいものは
SnO2であり、つぎに好ましいものはIn2O3であ
る。これらの材料はSO2ガスによる冷間腐蝕を受
けない。発明者はこのことを明らかにするため、
SnO2とIn2O3、ZnOの３つの材料でガスセンサ１
２を作り、SO22000ppｍを含む飽和水蒸気中に10
日間室温で放置した。SnO2やIn2O3を用いたガス
センサ１２では、この試験によつては劣化は生じ
なかつた。しかしZnOでは材料の一部がZnSO4に
変化してしまつた。SO2による冷間腐蝕の効果を
確認するため、SnO2センサとIn2O3センサに対
し、前記の試験を10回繰り返した。しかしいずれ
のセンサも、SO2による劣化を生じなかつた。つ
ぎに他の材料として、α−Fe2O3とMgFe2O4とを
検討したが、これらのものはCOガスへの感度が
小さく、実用に耐えなかつた。例えば350℃に加
熱した単味の金属酸化物半導体に対して、空気中
に150ppｍのCOガスを注入すると、SnO2の抵抗
値は1/7に、In2O3の抵抗値は1/3に減少するのに
対して、α−Fe2O3では抵抗値は10％減少するに
過ぎず、またMgFe2O4では抵抗値は20％増大す
るに過ぎない。 ガスセンサ１２の特性は、温度により変化す
る。SnO2100重量部に0.3重量部のPdを加えたガ
スセンサ１２について、加熱温度とガス中での抵
抗値との関係を第４図に示す。図の各実線（S1、
S3、S5）はSO2を含まない雰囲気での抵抗値を、
各破線（S2、S4、S6）は1500ppｍのSO2を含む
雰囲気での抵抗値を示し、実線と破線との間隔は
SO2への感度を示す。各ガスの組成を図に示す
が、実際にはこれに10％の水蒸気を加えN2ガス
でバランスしたものを用いた。COガスの感度に
は、250℃附近に極大値が有り、温度を増しても
減らしても感度は低下する。SO2の影響は複雑
で、COを含まない雰囲気では高温で影響が大き
く、COを含む雰囲気では低温と高温の双方で影
響が増す。そしてCOガスへの感度が極大となる
250℃附近で、SO2の影響が最小となる。従つて
このガスセンサ１２については、加熱温度を250
℃付近とするのが良い。 ガスセンサ１２の好ましい温度は、材料によつ
ても変化する。これらの結果を表１に示す。 This invention relates to reducing heat loss due to exhaust gas from combustion equipment, and is suitable for boilers, water heaters, thermal power generators, industrial furnaces, and the like. A heat exchanger refers to a combustion device that heats a fluid such as water using exhaust gas. However, in this specification, heat exchangers include not only fluids but also those that heat solids such as ores with exhaust gas. The thermal efficiency of combustion equipment is reduced due to unused heat being carried away with the exhaust gases. In order to reduce heat loss due to exhaust gas (hereinafter referred to as exhaust gas loss), the amount of air supplied to the burner may be kept to the minimum necessary. In order to reduce exhaust gas loss, the air ratio is controlled by detecting the O 2 concentration in the exhaust gas. However, what is actually required is not to keep the air ratio constant, but to make the air ratio as small as possible without generating black smoke and producing a small amount of combustible gases such as CO. The optimum air ratio constantly changes depending on the condition of the burner, combustion load, etc. Even if the O 2 concentration in exhaust gas remains constant, the amount of CO, etc. generated changes. Also, when detecting O 2 concentration,
Air intrusion into the flue reduces the detected concentration. The CO 2 concentration in exhaust gas is determined by both the type of fuel and combustion conditions. In order to eliminate the influence of fuel changes, the air ratio must be controlled without the influence of SO2 . The combustible components in the exhaust gas consist of CO, various hydrocarbons (hereinafter referred to as HC), and H2 . The ratio of these generated amounts also changes depending on the type of fuel and the condition of the burner. Therefore, it is preferable to detect combustible components not only for CO but for all of these combustible components. The basic objective of this invention is to control the air ratio based on the amount of combustible gas generated to reduce exhaust gas loss. As a secondary objective, we aim to control not only CO but also the total amount of combustible gas, and to eliminate the influence of SO 2 . In this invention, detection is performed after the exhaust gas from the burner is cooled to about 200 to 500°C using a heat exchanger. Upstream of the burner, the temperature of the exhaust gas is high, and the gas sensor is not sensitive to combustible gases, but is only affected by the O 2 concentration. Next, combustible gas is detected using a gas sensor made of a metal oxide semiconductor whose resistance value changes depending on the combustible gas. This gas sensor is sensitive not only to CO but also to gases such as H 2 and HC.
Provides an output corresponding to the total amount of combustible gas. The inventors then discovered that there are certain temperatures at which the gas sensor has maximum sensitivity to CO and minimum sensitivity to SO2 . The gas sensor detects exhaust gas,
Alternatively, it is heated to a preferable temperature by both exhaust gas and a heater for heating the sensor. The output of the gas sensor is determined by the change from the optimum air ratio, and the air ratio can be controlled to the optimum value using this output. Examples of the present invention will be described below. FIG. 1A shows the relationship between the air ratio m and the exhaust gas composition when C heavy oil is used as fuel in an industrial boiler. This boiler has a load factor of 100% at a fuel supply rate of 2000/hr when C heavy oil is used as fuel, and examples were investigated using this boiler. In the figure, l1 is the CO concentration at a load rate of 30%, and m1 is 50%.
h1 indicates the CO concentration at 80%.
Furthermore, m2 indicates the O 2 concentration at a load rate of 50%, and m3 and m4 indicate the water vapor concentration and SO 2 concentration at the same load rate.
Note that the O 2 concentration, water vapor, and SO 2 concentration are hardly affected by the load rate, and the other components are N 2 and CO 2 . This figure shows that the optimal air ratio changes depending on the combustion load rate, and that the air ratio cannot be maintained at the optimal value by controlling the O 2 concentration. FIG. 1B shows the exhaust gas composition of the same boiler when fueled with heavy oil A. In this figure, l11 indicates the CO concentration at a load rate of 30%, m11 indicates the CO concentration at 50%, and h11 indicates the CO concentration at 80%. Also, m12 is the O 2 concentration at a load rate of 50%, and m13 is the O 2 concentration at the same load rate.
Indicates H 2 O concentration. This figure shows that the optimum air ratio also changes depending on the type of fuel. Next, Figure 2 shows the SnO 2 for this boiler.
It shows the relationship between the resistance value of the system gas sensor and the air ratio m. This gas sensor contains 100 parts by weight of SnO2
Added 0.3 parts by weight of Pd, heating temperature is 250
It is ℃. The fuel used in the experiment was C heavy oil, and the curve
l21 shows data at 30% load factor, m21 shows data at 50%, and h21 shows data at 80%. Comparing FIG. 1A and FIG. 2, it can be seen that the resistance value of the gas sensor is not determined simply by the air ratio, but by the deviation from the optimum air ratio. This property can be explained by the fact that the resistance value of the gas sensor is determined by a combustible gas such as CO. That is, the quantity that characterizes the fluctuation in air ratio around the optimum air ratio is the fluctuation in the combustible gas concentration in the exhaust gas. The resistance value of this gas sensor is determined by the combustible gas concentration in the exhaust gas. Therefore, the resistance value of the gas sensor can be used as an amount indicating the shift from the optimum air ratio. Next, the structure of the apparatus of the embodiment will be shown based on FIGS. 3A and 3B. Fuel and air are supplied to the burner 6 of the boiler via the fuel supply valve 2 and the air supply valve 4. The exhaust gas from the burner 6 heats the water sent from the water supply valve 10 in the heat exchanger 8 to obtain steam. During the process of passing through heat exchanger 8, the temperature of the exhaust gas increases from 200 to 500.
℃, and V 2 O 5 in the exhaust gas solidifies and is removed. In addition, the exhaust gas is mixed inside the heat exchanger 8,
The composition of the gas becomes uniform. A gas sensor 12 and a temperature detection thermistor 14 are arranged between the heat exchanger 8 and the air preheater 11. The gas sensor 12 uses a metal oxide semiconductor whose resistance value changes depending on the combustible gas, and detects the concentration of combustible gases such as CO, H 2 and HC in the exhaust gas. This gas sensor 12 then detects the total concentration of these combustible gases. The gas sensor 12 is heated by exhaust gas and a heater 16 shown in FIG. 3B. Fluctuations in exhaust gas temperature are detected by the thermistor 14 and detected by the heater 16.
The temperature of the gas sensor 12 is kept constant. The output of gas sensor 12 is sent to controller 18 to control the air ratio. Although the air supply valve 4 is controlled here, the fuel supply valve 2 or both the air supply valve 4 and the fuel supply valve 2 may be controlled by the controller 18. Details of the controller 18 are shown in FIG. 3B. A gas sensor 12 and a load resistor 22 are connected in series to a power source 20, and the voltage applied to the load resistor 22 is compared with a reference potential by a comparator 24. A comparator 24 controls an air supply valve controller 26 to change the air ratio. In this way, when the air ratio is smaller than the optimum air ratio, the air ratio is increased, and when it is larger, the air ratio is reduced, thereby maintaining the air ratio at the optimum value. The resistance value of the gas sensor 12 changes depending on the temperature. The thermistor 14 detects the temperature of the exhaust gas, the shift from the reference temperature is detected by the differential amplifier 28, the variable power supply 30 is controlled, and the voltage applied to the heater 16 is changed. In this way, the temperature of the gas sensor 12 is kept constant. The gas sensor 12 is made of a metal oxide semiconductor whose resistance value changes depending on the combustible gas. The most preferable material for the gas sensor 12 is
SnO 2 is the next preferred one, and In 2 O 3 is the next preferred one. These materials are not subject to cold corrosion by SO 2 gas. In order to clarify this, the inventor
Gas sensor 1 made of three materials: SnO 2 , In 2 O 3 , and ZnO
2 and 10 in saturated steam containing 2000ppm SO 2
It was left at room temperature for several days. In the gas sensor 12 using SnO 2 or In 2 O 3 , no deterioration occurred in this test. However, in the case of ZnO, a part of the material changed to ZnSO 4 . In order to confirm the effect of cold corrosion caused by SO 2 , the above test was repeated 10 times for the SnO 2 sensor and the In 2 O 3 sensor. However, neither sensor caused deterioration due to SO 2 . Next, α-Fe 2 O 3 and MgFe 2 O 4 were considered as other materials, but these materials had low sensitivity to CO gas and were not suitable for practical use. For example, if 150 ppm of CO gas is injected into the air into a single metal oxide semiconductor heated to 350°C, the resistance of SnO 2 will be reduced to 1/7, and the resistance of In 2 O 3 will be reduced to 1/3. In contrast, with α-Fe 2 O 3 the resistance value decreases by only 10%, and with MgFe 2 O 4 the resistance value increases by only 20%. The characteristics of the gas sensor 12 change depending on the temperature. FIG. 4 shows the relationship between the heating temperature and the resistance value in the gas for a gas sensor 12 containing 100 parts by weight of SnO 2 and 0.3 parts by weight of Pd. Each solid line in the figure (S1,
S3, S5) are the resistance values in an atmosphere that does not contain SO 2 ,
Each dashed line (S2, S4, S6) indicates the resistance value in an atmosphere containing 1500ppm SO2 , and the interval between the solid line and the dashed line is
Indicates sensitivity to SO2 . The composition of each gas is shown in the figure, but in reality, 10% water vapor was added to it and balanced with N2 gas. The sensitivity of CO gas has a maximum value around 250°C, and the sensitivity decreases regardless of whether the temperature is increased or decreased. The effects of SO 2 are complex; in atmospheres without CO, the effects are greater at high temperatures, and in atmospheres containing CO, the effects increase at both low and high temperatures. And the sensitivity to CO gas becomes maximum.
At around 250℃, the influence of SO 2 is minimal. Therefore, for this gas sensor 12, the heating temperature is set to 250℃.
It is best to keep it around ℃. The preferred temperature of the gas sensor 12 also varies depending on the material. These results are shown in Table 1.

【表】【table】

【表】 先の実施例から添加物のPdを除くと（第１の
試料１）、最適加熱温度が100℃高温側にシフトす
る。これが添加Pdの効果である。Pdに代えても
他のものを、例えばPt、Ph、Ir、Au等の貴金属
を加えても良い。その際の結果を試料２〜６とし
て示す。そしてPd等の添加量は1.0重量部以下が
好ましく、これ以上ではCOへの感度が低下し、
SO2の影響が増す（表１の試料３、４参照）。い
ずれにせよ重要なことは、ガスセンサ１２には
COへの感度が最大で、SO2の影響が最小となる
温度が存在することである。そしてガスセンサ１
２をこの温度に保つことにより、空気比の制御精
度を増すことができる。 第５図に、実施例の方法による空気比の制御例
を示す。ボイラーには第１図Ａ，Ｂの測定に用い
たものを、Ｃ重油に燃料として作動させる。ガス
センサ１２には表１の試料３のものを250℃に加
熱して用いる。図の上部はガスセンサ１２の出力
（VRL）と、各出力の最適空気比からのシフト
（Vm）とを示すものである。そして図の下部に
燃料供給量を示す。この図から、最適空気比付近
に、空気比を保ち得ることがわかる。 つぎに、排ガス中のCO、HC、H2、及びO2濃
度の分析例を表２に示す。[Table] When the additive Pd is removed from the previous example (first sample 1), the optimum heating temperature shifts to a higher temperature side by 100°C. This is the effect of added Pd. Instead of Pd, other materials such as noble metals such as Pt, Ph, Ir, and Au may be added. The results at that time are shown as samples 2 to 6. The amount of Pd etc. added is preferably 1.0 parts by weight or less; if it is more than this, the sensitivity to CO will decrease.
The influence of SO 2 increases (see samples 3 and 4 in Table 1). In any case, the important thing is that the gas sensor 12
There is a temperature at which the sensitivity to CO is maximum and the effect of SO 2 is minimum. and gas sensor 1
By keeping 2 at this temperature, the accuracy of controlling the air ratio can be increased. FIG. 5 shows an example of controlling the air ratio by the method of the embodiment. The boiler used for the measurements shown in Figure 1 A and B was operated using C heavy oil as fuel. For the gas sensor 12, sample 3 in Table 1 is used after being heated to 250°C. The upper part of the figure shows the output (V RL ) of the gas sensor 12 and the shift (Vm) of each output from the optimum air ratio. The fuel supply amount is shown at the bottom of the figure. From this figure, it can be seen that the air ratio can be maintained near the optimum air ratio. Next, Table 2 shows an analysis example of CO, HC, H 2 and O 2 concentrations in exhaust gas.

【表】【table】

【表】 COとHC、及びH2の濃度比は様々で、同じボ
イラーでさえも燃焼負荷の変化等により異なるこ
とがわかる（試料１〜４）。しかしこのガスセン
サ１２は、可燃性ガスの総濃度を示す出力を与え
るので、ガスの濃度比が変化しても検出精度が低
下しないことがわかる。 以上に述べた様に、この発明では燃焼機器の空
気比を常に最適値に保つことができる。そしてガ
スセンサの温度を選ぶことにより、SO2の影響を
事実上除くことができる。さらにガスセンサは
CO以外の、H2やHC等の可燃性ガスにも感応す
るので、生ずる可燃性ガスの組成が変化した際に
も検出精度が低下しない。[Table] It can be seen that the concentration ratios of CO, HC, and H 2 vary, and even in the same boiler, they differ due to changes in combustion load, etc. (Samples 1 to 4). However, since this gas sensor 12 provides an output indicating the total concentration of combustible gases, it can be seen that the detection accuracy does not decrease even if the gas concentration ratio changes. As described above, according to the present invention, the air ratio of the combustion equipment can always be kept at an optimum value. By selecting the temperature of the gas sensor, the influence of SO 2 can be virtually eliminated. Furthermore, the gas sensor
Since it is sensitive to flammable gases other than CO, such as H 2 and HC, detection accuracy does not decrease even when the composition of the combustible gas that is generated changes.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図Ａ，Ｂは、それぞれ燃焼機器の特性図で
ある。第２図は実施例のガスセンサの特性図、第
３図Ａは実施例に用いた装置のブロツク図、第３
図Ｂはその回路図である。第４図は実施例のガス
センサの特性図、第５図は実施例の方法の特性図
である。 ２……燃料供給弁、４……空気供給弁、６……
バーナ、８……熱交換器、１１……空気予熱器、
１２……ガスセンサ、１４……サーミスタ、１８
……コントローラ。 FIGS. 1A and 1B are characteristic diagrams of combustion equipment, respectively. Figure 2 is a characteristic diagram of the gas sensor of the example, Figure 3A is a block diagram of the device used in the example, and Figure 3A is a block diagram of the device used in the example.
Figure B is its circuit diagram. FIG. 4 is a characteristic diagram of the gas sensor of the example, and FIG. 5 is a characteristic diagram of the method of the example. 2...Fuel supply valve, 4...Air supply valve, 6...
Burner, 8... Heat exchanger, 11... Air preheater,
12... Gas sensor, 14... Thermistor, 18
……controller.

Claims (1)

【特許請求の範囲】[Claims] １ バーナからの排ガスを熱交換器により冷却
し、可燃性ガスにより抵抗値が変化する金属酸化
物半導体からなるガスセンサをCOガスへの感度
が最大でかつSO2ガスへの感度が最小となる温度
に加熱し、このガスセンサにより熱交換後の排ガ
ス中の可燃物濃度を検出し、このガスセンサの検
出信号により空気比を制御するようにした燃焼機
器の空気比制御方法。1 The exhaust gas from the burner is cooled by a heat exchanger, and a gas sensor made of a metal oxide semiconductor whose resistance value changes depending on the combustible gas is set at a temperature at which the sensitivity to CO gas is maximum and the sensitivity to SO 2 gas is minimum. A method for controlling the air ratio of combustion equipment, in which the concentration of combustible substances in the exhaust gas after heat exchange is detected by the gas sensor, and the air ratio is controlled by the detection signal of the gas sensor.
JP58197199A 1983-10-21 1983-10-21 Control method for air ratio of burner Granted JPS6089624A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP58197199A JPS6089624A (en) 1983-10-21 1983-10-21 Control method for air ratio of burner

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP58197199A JPS6089624A (en) 1983-10-21 1983-10-21 Control method for air ratio of burner

Publications (2)

Publication Number Publication Date
JPS6089624A JPS6089624A (en) 1985-05-20
JPH0323809B2 true JPH0323809B2 (en) 1991-03-29

Family

ID=16370459

Family Applications (1)

Application Number Title Priority Date Filing Date
JP58197199A Granted JPS6089624A (en) 1983-10-21 1983-10-21 Control method for air ratio of burner

Country Status (1)

Country Link
JP (1) JPS6089624A (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS625015A (en) * 1985-07-01 1987-01-12 Youei Seisakusho:Kk Burner
WO1991000978A1 (en) * 1989-07-07 1991-01-24 Forschungsgesellschaft Joanneum Gmbh Furnace control device
CN102767842B (en) * 2012-03-09 2015-03-18 武汉海尔热水器有限公司 Method and device for controlling burning efficiency

Also Published As

Publication number Publication date
JPS6089624A (en) 1985-05-20

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