JPH06341629A - Method and device for controlling air ratio in fluidized-bed furnace - Google Patents

Abstract

PURPOSE:To suppress the generation of CO and dust by a method wherein on the basis of the estimated values of the air ratio in the fluidized bed and that in the freeboard the ratio in which the air for combustion is distributed to the inside of the fluidized bed and the freeboard and the flow rate of the air for combustion are controlled. CONSTITUTION:A means of calculating the ratio of combustion in the fluidized bed 30 calculates the ratio of combustion in the fluidized bed K from the temperature of the fed air, the temperature of the fluidized bed, the temperature of the discharged gases at the outlet of the furnace, the flow rate of the primary air, and the flow rate of the secondary air, all for the combustion of materials in a fluidized-bed furnace. A means of calculating the air ratio in the fluidized bed 32 estimates the air ratio in the fluidized bed lambdaB from the ratio of combustion in the fluidized bed K and the flow rate of the primary air. A means of calculating the air ratio in the freeboard 14 estimates the air ratio in the freeboard lambdaF from the flow rate of the primary air and that of the secondary air. On the basis of the air ratio in the fluidized bed lambdaB and the air ratio in the freeboard lambdaF a means of controlling the air ratio 36 controls the ratio in which the air for combustion is distributed to the inside of the fluidized bed and the freeboard and the flow rate of the air for combustion. As a result, the operation is rendered free from a localized shortage of air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for controlling an air ratio in a combustion furnace having a fluidized bed (hereinafter referred to as a fluidized bed furnace), and more specifically, a method for burning and incinerating wastes and other materials TECHNICAL FIELD The present invention relates to a method and apparatus for appropriately controlling the amount of primary air supplied to a fluidized bed and the amount of secondary air supplied to a freeboard section in a bed furnace.

[0002]

2. Description of the Related Art Conventionally, by using plant measurement data such as furnace exhaust gas temperature, water injection water amount, waste calorie, waste incineration amount, exhaust gas O ₂ concentration, etc., it is possible to detect whether combustion inside the furnace is excessive or excessive, and to use it for combustion A control method is known in which the air ratio is controlled to suppress air shortage in the incinerator as a whole.

Further, Japanese Patent Publication No. 61-2843 discloses that
Based on the fluidized bed temperature and the fuel flow rate supplied to the fluidized bed,
A combustion control method for a fluidized bed furnace is described which controls the air ratio of the air supplied to the fluidized bed.

[0004]

The conventional air control method described above has a problem in that CO and dust are generated due to local air shortage in order to suppress air shortage in the entire furnace. Further, when detecting an air shortage based on the exhaust gas O ₂ concentration, there is a large time delay, and there is a limit to the response.

The present invention has been made in view of the above points, and an object of the present invention is to estimate a local combustion by estimating an air ratio in a fluidized bed and an air ratio in a freeboard part from plant measurement data. An object of the present invention is to provide a control method and device for controlling the production air and suppressing the generation of CO and dust. Another object of the present invention is to measure the gas temperature, the time delay in detecting the air flow rate, etc. with a small time delay, perform signal processing with a dynamic characteristic analysis formula and a Kalman filter,
An object of the present invention is to provide a control method and device that are highly reliable and that do not involve analysis delay.

[0006]

In order to achieve the above object, the method for controlling the air ratio in a fluidized bed furnace of the present invention is a plant measurement of the in-bed combustion ratio when burning an object to be treated in the fluidized bed furnace. By estimating from the data, the air ratio in the fluidized bed and the air ratio in the freeboard section, and controlling the distribution ratio and flow rate of the combustion air in the fluidized bed and the freeboard section based on these estimated values Is characterized by. In the above method, as the plant measurement data,
It is desirable to use the supply air temperature, fluidized bed temperature, furnace outlet exhaust gas temperature, primary air flow rate and secondary air flow rate.

As shown in FIG. 1, the air ratio control device for a fluidized bed furnace of the present invention inputs plant measurement data when burning an object to be treated in the fluidized bed furnace, and calculates the combustion ratio K in the fluidized bed. The in-layer combustion rate calculation means 30 for calculating, the in-layer combustion rate K obtained from this in-layer combustion rate calculation means 30, and the primary air flow rate G _{a 1 of the} plant measurement data are input and the inside of the fluidized bed is calculated. The in-layer air ratio calculating means 32 for estimating the air ratio λ _B and the primary air flow rate G _{a 1} and the secondary air flow rate G _{a 2} of the plant measurement data are input to determine the air ratio λ _F in the freeboard portion. Freeboard air ratio calculating means 34 for estimating, and air for inputting the in-layer air ratio λ _B and the freeboard air ratio λ _F to control the distribution ratio and flow rate of combustion air in the fluidized bed and in the freeboard portion. Ratio control means 36
It is characterized by having and. In the above apparatus, it is desirable that the plant measurement data uses the supply air temperature, the fluidized bed temperature, the furnace outlet exhaust gas temperature, the primary air flow rate, and the secondary air flow rate.

[0008]

EXAMPLES The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to the following examples, and various modifications may be made without departing from the scope of the invention. Is possible. FIG. 1 is a system diagram showing an embodiment of the method and apparatus of the present invention, and FIG. 2 is a schematic diagram showing a fluidized bed furnace 10. In FIG. 2, 12 is a fluidized bed, 14 is an air dispersion plate, 16 is a freeboard section, 1
8 is a primary air inlet, 20 is a secondary air inlet, 22 is an exhaust gas outlet, 24 is an object inlet, and 26 is a wind box.

The operation when the fluidized bed furnace shown in FIG. 2 is a fluidized bed refuse incinerator will be described. The dust thrown into the fluidized bed 12 made of a fluidized medium (for example, silica sand) that is vigorously mixed and stirred by the primary air is caught in the bed and burned in a short time by the heat, and further, the freeboard portion 16 Then, the combustion is completed by the secondary air. Further, the incombustibles settle in the bed and are extracted as incineration residues together with the fluidized medium from an incombustibles extraction pipe (not shown). The present inventors created a mathematical model in consideration of the characteristics of the fluidized bed refuse incinerator described above, and fuzzy inferred the amount of refuse, and confirmed that the dynamic characteristic simulation result and the actual machine data match.

As shown in FIG. 2, the amount of waste supplied is G _R kg /
H, theoretical air amount of this waste is A Nm ³ / kg, in-bed combustion ratio is K, freeboard combustion ratio is 1-K, primary air flow rate is G _{a 1} Nm ³ / H, secondary air flow rate is G _{a 2} Nm ³ / H, freeboard temperature T _F ℃, fluidized bed temperature T _B ℃, exhaust gas temperature T _g ℃, and supply air temperature T _a ℃, the in-bed combustion ratio K is expressed by Equation 1. Be done.

[0011]

[Equation 1]

Further, the in-layer air ratio λ _B is expressed by Equation 2.

[0013]

[Equation 2]

Further, the freeboard air ratio λ _F is expressed by Equation 3.

[0015]

[Equation 3]

Further, the amount of refuse supply can be obtained by fuzzy inference in which the rotation speed of the dust feeder and the current of the dust feeder are input.
In the above formula, G _{g B} = K G _R (V ₀ −A ₀ +1.24 ω) + G _{a 1} / η _B G _{g F} = G _R (V ₀ −A ₀ +1.24 ω) + (G _{a 1} + G _{a 2)} / _{[(1- K) η P + Kη} B ] However, K: intralayer combustion ratio T _B: bed temperature (° C.) T _g: furnace exit gas temperature (° C.) T _a: air temperature (° C.) G _{a 1} : Primary air flow rate (Nm ³ / H) G _{a 2} : Secondary air flow rate (Nm ³ / H) C _pg : Gas specific heat (kcal / Nm ³ ° C) C _pa : Air specific heat (kcal / Nm ³ ° C) G _{g B:} layers quantity of exhaust gas _{^{(Nm 3 / H) G g}} F: the furnace exit exhaust gas amount _{^{(Nm 3 / H) H u}} : garbage lower heating value (kcal / kg) G _R: waste supply rate (kg / H) η _B : In-bed combustion efficiency η _F : Freeboard combustion efficiency CB: _Bed material specific heat (kcal / kg ° C) WB: _Bed material weight (kg) V ₀ : Theoretical exhaust gas amount (Nm ³ / kg) A ₀ : Theoretical air amount (Nm ³ / kg) ω: Waste unit amount Medium water content

Next, one embodiment of the control device of the present invention will be described with reference to FIG. Reference numeral 30 denotes an in-bed combustion ratio calculation means, which is plant measurement data when burning an object to be processed in a fluidized bed furnace, for example, supply air temperature T _a ° C and fluidized bed temperature T _B.
℃, furnace outlet exhaust gas temperature T _g ℃, primary air flow rate G _{a 1} Nm ³
/ H and the secondary air flow rate G _{a 2} Nm ³ / H,
The in-layer combustion ratio K is calculated. Reference numeral 32 denotes an in-layer air ratio calculating means, which inputs the in-layer combustion ratio K and the primary air flow rate G _{a 1} to estimate the in-layer air ratio λ _B. Reference numeral 34 is a freeboard air ratio calculation means 14, which inputs the primary air flow rate G _{a 1} and the secondary air flow rate G _{a 2} to input the freeboard air ratio λ.
Estimate _F.

Reference numeral 36 denotes an air ratio control means, which is an in-layer air ratio λ _B
And the freeboard air ratio λ _F is input to control the distribution ratio and flow rate of combustion air in the fluidized bed and to the freeboard section. Reference numeral 40 is a fuzzy inference means, which inputs the dust supply current and the rotation speed of the dust supply device to perform fuzzy inference, and inputs the inference result to the in-layer air ratio calculation means 32 and the freeboard air ratio calculation means 34.

Reference numeral 42 denotes a refuse / air basic calculation means, which inputs the incineration amount and the heat generation amount, and inputs the calculation result to the air ratio control means 36 and the generated heat control means 44. A generated heat calculation means 46 inputs the supply air temperature T _a , the furnace outlet exhaust gas temperature T _g , the primary air flow rate G _{a 1} and the secondary air flow rate G _{a 2} and inputs the calculation result to the generated heat control means 44. .

Next, the method of the present invention will be described with reference to FIG. Of the plant measurement data (actual machine data), the primary air flow rate G _{a 1} , the secondary air flow rate G _{a 2} , the primary air temperature T _a , the fluidized bed temperature T _B, and the furnace outlet exhaust gas temperature T _g are used. , The in-layer combustion ratio K is calculated. Also, this K,
The in-layer air ratio λ _B is calculated from the dust supply amount G _R fuzzy inferred by inputting the dust supply device current I and the rotation speed of the dust supply device and the measured G _{a 1} . Further, a fuzzy inference value G _R by inputting the dust supply device current I and the number of revolutions, an actual measurement G _{a 1} ,
And the freeboard air ratio λ _F is calculated from the measured G _{a 2} . In addition to controlling λ _B and λ _F , the flow rates G _{a 1} and G _{a 2} of the combustion air in the fluidized bed and to the freeboard section are set. In FIG. 1, Q _s represents the amount of combustion of all input waste, λ _{B s} represents the in-layer air ratio set value, and λ _{F s} represents the freeboard air set value. The control method in this embodiment is performed by the configuration of the portion surrounded by the alternate long and short dash line in FIG.

In the above control method, the parameter estimation is performed by utilizing the state estimation method using the Kalman filter in order to compensate the delay of the measurement signal. Then, the in-layer combustion ratio K thus obtained can be used to calculate the in-layer air ratio λ _B and the freeboard air ratio λ _{F. Based} on these values, the optimum primary air flow rate G _{a 1} and the optimum The next air flow rate G _{a 2} can be set.

[0022]

Since the present invention is configured as described above, it has the following effects. (1) By capturing the in-bed combustion ratio from the plant measurement data, the fluidized bed air ratio λ _B and the freeboard air ratio λ _F are estimated, and the distribution ratio of the combustion air is controlled by these. The lack of air can be eliminated and the generation of CO and dust can be prevented. (2) When the air temperature, fluidized bed temperature, exhaust gas temperature, primary air flow rate and secondary air flow rate are used as plant measurement data, there is high reliability and analysis delay as in the case of O ₂ concentration control, etc. It is not accompanied by. (3) The method of the present invention can be implemented without significantly changing the conventional automatic combustion control mechanism.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of an air ratio control method and apparatus in a fluidized bed furnace of the present invention.

FIG. 2 is a schematic explanatory view of a fluidized bed furnace.

[Explanation of symbols]

 10 Fluidized Bed Furnace 12 Fluidized Bed 16 Freeboard Section 18 Primary Air Inlet 20 Secondary Air Inlet 24 Workpiece Inlet 30 In-Layer Combustion Ratio Calculation Means 32 In-Layer Air Ratio Calculation Means 34 Freeboard Air Ratio Calculation Means 36 Air Ratio Control means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hidetaka Miyazaki No. 1-1 Kawasaki-cho, Akashi-shi, Hyogo Prefecture Kawasaki Heavy Industries Ltd. Akashi factory (72) Hiroshi Fujiyama 2-5-25 Tenjinbashi, Kita-ku, Osaka Kawasaki Heavy Industries Ltd. Osaka Design Office (72) Inventor Eiichiro Nanbu 2-5-25 Tenjinbashi, Kita-ku, Osaka Kawasaki Heavy Industries Ltd. Osaka Design Office (72) Inventor Norio Toyoshima 2-5 Tenjinbashi, Kita-ku, Osaka City No. 25 Kawasaki Heavy Industries Ltd. Osaka Design Office

Claims (4)

[Claims] 1. When burning an object to be treated in a fluidized bed furnace, the air ratio in the fluidized bed and the air ratio in the freeboard part are estimated by capturing the in-bed combustion ratio from plant measurement data, and these estimations are made. A method for controlling an air ratio in a fluidized bed furnace, comprising controlling a distribution ratio and a flow rate of combustion air in a fluidized bed and to a freeboard section according to a value. 2. The plant measurement data includes supply air temperature,
The air ratio control method in a fluidized bed furnace according to claim 1, wherein the fluidized bed temperature, furnace outlet exhaust gas temperature, primary air flow rate, and secondary air flow rate are used. 3. The combustion rate (K) in the fluidized bed is input by inputting plant measurement data when burning the material to be treated in the fluidized bed furnace.
In-layer combustion ratio calculating means (30) for calculating, and in-layer combustion ratio (K) obtained from this in-layer combustion ratio calculating means (30) and the primary air flow rate (G _{a 1} ) of the plant measurement data And the in-bed air ratio calculating means (32) for estimating the air ratio (λ _B ) in the fluidized bed, and the primary air flow rate (G _{a 1} ) and the secondary air flow rate (G _{a 1} ) in the plant measurement data ( Free board air ratio calculation means (34) for inputting G _{a 2} ) to estimate the air ratio (λ _F ) in the free board portion, and the in-layer air ratio (λ _B ) and free board air ratio (λ _F ) And an air ratio control means (36) for controlling the distribution ratio and flow rate of combustion air in the fluidized bed and to the freeboard section. 4. The plant measurement data is a supply air temperature,
The air ratio control device in a fluidized bed furnace according to claim 3, wherein the temperature is a fluidized bed temperature, a furnace outlet exhaust gas temperature, a primary air flow rate, and a secondary air flow rate.