JPH071084B2 - Air amount control method for fluidized bed furnace with boiler - Google Patents

Description

TECHNICAL FIELD The present invention relates to an air amount control method for a fluidized bed furnace with a boiler.

[Prior Art] A fluidized bed furnace with a boiler is basically composed of a fluidized bed furnace 1 and a boiler 2 attached to the top of the fluidized bed furnace 1, as shown in FIG. It has a blower 4 for primary air, a blower 5 for secondary air, a gas type primary air preheater 6, a gas type secondary air preheater 7 and a steam type secondary air preheater 8. Incinerators such as municipal waste and sludge cake are put into the storage tank of the dust collector 3 through the dust input hopper, the dust crusher, and the dust transfer conveyor by the dust crane 9, and then in the fluidized bed furnace 1 by the dust feeder 3. Is supplied to. The material to be incinerated forms a fluidized bed 11 together with the fluidized medium in the furnace 1 by the primary air blown from the air diffusing tube 10 and undergoes primary combustion, and is then burned by secondary air blown upward from the air blowing tube 12 to the secondary air. The next combustion occurs and the incineration is completed.

The combustion exhaust gas generated in the fluidized bed furnace 1 heats the boiler water in the boiler 2 at the top of the furnace 1 to generate high temperature steam, and then is introduced into the flue 13 to the air preheater 6 in the flue 13. At 7, the primary air and the secondary air are preheated. Primary air is blower 4
Sent by the air preheater 6 through the air diffuser
Sent to 10. The secondary air is blown out by the blower 5, is preheated by the steam from the boiler 2 in the air preheater 8, and then passes through the air preheater 7 to blow the air.
Sent to 12.

In FIG. 8, 14 is a weight scale for measuring the amount of waste to be incinerated by the dust crane 9 into the dust feeder 3 (the weight of the garbage crane), and 15 is the screw rotation speed of the dust feeder 3. A rotary meter, 16 is a steam amount measuring device for measuring the amount of steam generated in the boiler 2, and 17 and 18 are air amount measuring devices for measuring the primary air amount and the secondary air amount, respectively.

[Problems to be Solved by the Invention] By the way, the dust quality and the amount of dust supplied to the incinerator supplied to the fluidized bed furnace 1 constantly fluctuate, and the primary air and secondary air are supplied to the furnace 1 at an appropriate air amount. If the secondary air is not supplied, the material to be incinerated will not burn well. For example, when the dust quality of the materials to be incinerated is reduced, the total amount of air is reduced, and unless primary air or secondary air is supplied, excessive air combustion occurs,
Boiler efficiency decreases and NOx generation tends to increase. On the contrary, if the amount of dust in the materials to be incinerated is improved and the total air amount is not increased to supply the primary air and the secondary air, insufficient air combustion will occur, and exhaust gas smoke will be easily generated due to the generation of CO.

However, conventionally, the amount of dust to be incinerated to the fluidized bed furnace 1 which is obtained from the amount of the incinerator to be charged into the dust feeder 3 and the screw rotation speed of the dust feeder 3, and the steam generated in the boiler 2 The inlet dampers 1 and 4 of the blowers 4 and 5 for the primary air and the secondary air while the operator relies on the intuition based on the amount and the combustion condition in the furnace 1.
Only the control of adjusting the primary air amount and the secondary air amount by manually operating the opening controller 21, 22 of 9,20 was performed.
For this reason, it is difficult to supply primary air and secondary air to the furnace 1 with an appropriate amount of air in response to fluctuations in the dust quality and the amount of dust supplied to the incinerator supplied to the fluidized bed furnace 1. It was easy to cause instability of burning of incineration.

In view of the above-mentioned current situation, the object of the present invention is to provide a furnace for the incinerator supplied to the fluidized bed furnace, even if there is a change in the quality of dust, or if there is a change in the amount of dust supplied from the evaporation stable control operation. Another object of the present invention is to provide an air amount control method for a fluidized bed furnace with a boiler, which can supply primary air and secondary air with an appropriate air amount.

[Means for Solving the Problem] The air amount control method of the present invention uses the relationship between the current heat input and heat output of the fluidized bed furnace with a boiler to determine the heat generation amount of the incineration object that is currently incinerated, and the waste crane. The current amount of dust is calculated from the input amount and the number of revolutions of the dust collector, and then the total amount of combustion air is calculated from the heat generation amount and the dust supply amount, while the primary air for optimal combustion is calculated from the heat generation amount. Is obtained, and then the primary air amount and the secondary air amount are obtained from the total air amount and the air ratio of the primary air, and the primary air amount and the secondary air amount are controlled.

[Operation] The calorific value of the incineration object currently incinerated in the fluidized bed furnace with a boiler corresponds to the quality of the incineration object. In addition, the current amount of dust supply corresponds to the input amount of the garbage crane and the rotation speed of the dust collector. Therefore, from the relationship between the current heat input and heat output of the furnace, find the heat value of the incinerator that is currently burning,
In addition, the current amount of dust is calculated from the number of revolutions of the dust collector and the input amount of the garbage crane. Then, the total air amount of the combustion air is obtained from the heat generation amount and the dust supply amount, while the air ratio of the primary air for optimal combustion is obtained from the heat generation amount, and the primary air amount and the secondary air amount are further obtained. By controlling the primary air amount and the secondary air amount, it is possible to supply the primary air and the secondary air at the optimum air amount according to the dust quality and the dust supply amount of the incinerator currently being burned. it can.

[Examples] Examples of the present invention will be described in detail below.

FIG. 1 is an explanatory view showing an embodiment of the air amount control method of the present invention. As shown in FIG. 1, in the present invention,
In order to obtain the calorific value of the incineration object currently burning in the fluidized bed furnace 1 equipped with the boiler 2, first, the amount of dust supplied to the incineration object of the incineration object is measured by the weight scale 14 with a garbage crane. It is calculated from the input amount of the incineration object to the dust collector 3 by 9 (weight value of garbage crane) and the screw rotation speed of the dust collector 3 measured by the tachometer 15. In FIG. 1, the same symbols as those in FIG. 8 indicate the same members. In FIG. 1, 23 is a thermometer for measuring the outlet air temperature of the steam type secondary air preheater (SAH) 8, and 24 is a thermometer for measuring the outlet temperature of the GAH (gas type air preheater 6, 7). is there.

The amount of dust incinerated to the fluidized bed furnace 1 that is currently burning is
It is calculated as shown in FIG. That is, the moving average of the screw rotation speed of the dust collector 3 measured by the tachometer 15 is calculated to obtain the average screw rotation speed n (times / minute) for a short time,
Then, the moving average is further updated to obtain the average number of revolutions (times / minute) of the screw for a long time. On the other hand, the scale 14
The average input amount of incinerated materials (kg /
Minutes). Next, based on the average input amount of the incineration object and the average rotation speed of the screw for a long time, the dust supply amount W _R (kg / kg /
Times) as W _R = /.

Then, based on the dust supply amount W _R of the incineration object per screw rotation and the average rotation number n of the screw in a short time, the dust supply amount W _RI ( (Ton / day)
The, obtained as _{W RI = n × W R ×} 60 × 24/10 3.

When the dust supply amount W _{RI of the} incineration object currently incinerated to the fluidized bed furnace 1 is obtained as described above, the calorific value Hu of the incineration object or less is obtained.

First, the calorific value Hu (kCal / k
g) (Lower calorific value) is calculated based on the following equation (1) from the relationship between the current heat input and heat output of the furnace.

However, K: the difference between the steam generated by the boiler 2 and the enthalpy of the boiler feed water (kCal / kg) (given by a constant), η _O : Boiler standard efficiency (%), E: Boiler efficiency correction coefficient, W _RI : Current dust amount (ton / day) W _a2 : Secondary air amount (kg / hour), T: Steam-type secondary air Preheater outlet air temperature (℃), C _pa : Average specific heat of secondary air (kCal / kg ・ ℃) (given by a constant).

Since the boiler reference efficiency η _o has a certain relationship with the heat value Hu of the incineration object as shown in FIG. 3, it is obtained from that relationship. Further, the boiler efficiency correction coefficient E is obtained by the following equation (2).

E = −β / 100 ・ (T _g −T _go ) +1 (2) where β: Change in boiler standard efficiency η _o due to change in exhaust gas temperature at GAH (gas air preheater) outlet when standard dust quality Gradient (% / ° C), T _g : GAH outlet exhaust gas temperature (° C), T _go : Reference exhaust gas temperature (° C).

There is a relationship between the reference exhaust gas temperature T _go and the boiler efficiency η as shown in FIG. 4, and the above-mentioned slope β is β = Δη _o / ΔT
It can be _calculated by _g , but here β is given as a constant.

The calorific value Hu thus obtained corresponds to the quality of the incinerated object to be incinerated at present. Next, from the heat generation amount Hu and the dust supply amount W _RI , the total air amount of combustion air (reference air amount) W
On the other hand, _as is calculated, and the air ratio ε ₁ of the primary air is calculated from the heat generation amount Hu.

First, between the heating value Hu and the total air ratio ε of the combustion air,
A fixed relation as shown in the figure is programmed, and the total air ratio ε is obtained from the relation. Similarly, since the calorific value Hu and the theoretical air amount L _m have a constant interval as shown in FIG. 6, the theoretical air amount L _m (kg / kg) is determined from the relationship.
Next, using the obtained total air ratio ε and the theoretical air amount L _m , the air-fuel ratio L (kg / kg) is obtained by the following equation (3), and the obtained air-fuel ratio L is used to obtain the following (4 ) Calculate total air amount W _as (kg / hour).

L = ε × L _m (3) W _as = L × W _RI / 24 × 10 ³ (4) The primary air ratio ε ₁ for optimal combustion is calculated as shown in FIG. Program in a certain relationship with. Using the calorific value Hu obtained there, the air ratio ε ₁ of the primary air is obtained from this relationship.

The calorific value Hu of the incinerator currently incinerated as described above
If the required total air amount W _as is obtained from the amount of dust and the dust supply amount W _RI and the air ratio ε _{1 of the} primary air is obtained from the heat generation amount Hu, the primary air amount W _a1 (kg / Hour), and using this, find the secondary air amount W _a2 (kg / hour) by the following equation (6).

W _a1 = ε ₁ / ε × W _as …… (5) W _a2 ＝ W _as −W _a1 …… (6) Primary air amount W _a1 and secondary air amount W thus obtained
_a2 is the optimum amount of air according to the amount of dust and the amount of dust to be incinerated at present. A control signal is output based on the primary air amount W _a1 and the secondary air amount W _a2 obtained there,
The opening amounts of the inlet damper 19 of the primary air blower 4 and the inlet damper 20 of the secondary air blower 5 are adjusted to adjust the air amount measuring devices 17, 18
The primary air amount and the secondary air amount may be controlled so that the primary air amount and the secondary air amount measured in step _S1 match the obtained primary air amount W _a1 and the secondary air amount W _a2 .

According to this, it is possible to supply the primary air and the secondary air to the fluidized bed furnace 1 at an appropriate amount according to the quality and the amount of dust to be incinerated currently being incinerated. it can. As a result, the combustion of the incinerated matter is stabilized, the incinerated matter can be satisfactorily primary-combusted in the fluidized bed 11, and the secondary combustion can be performed above the incinerated matter.
And smoke generation due to CO generation due to insufficient air combustion. Further, the furnace 1 can be operated easily and the energy can be saved, and the amount of steam generated by the boiler 2 can be stabilized.

[Effects of the Invention] As described above, according to the present invention, even if there are fluctuations in the quality of dust and the amount of dust to be incinerated supplied to the fluidized bed furnace,
The primary air and secondary air of the combustion air can always be supplied in an optimum air amount according to the quality of dust and the amount of dust supplied. Therefore, the material to be incinerated can be stably burned.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing an embodiment of an air amount control method of the present invention, and FIG. 2 is an explanatory diagram of how to determine the dust supply amount of an incineration object by the method of FIG. Fig. 3 is a graph showing the relationship between the calorific value of the incinerated material and the boiler standard efficiency, Fig. 4 is a graph showing the relationship between the GAH outlet exhaust gas temperature and the boiler efficiency, and Fig. 5 is the calorific value. 6 is a graph showing the relationship between the heat generation amount and the theoretical air amount, and FIG. 7 is a graph showing the relationship between the heat generation amount and the primary air ratio. FIG. 8 is an explanatory view showing a fluidized bed furnace with a boiler. In the figure, 1 is a fluidized bed furnace, 2 is a boiler, 4 is a blower for primary air, and 5 is a blower for secondary air.

Claims (1)

[Claims] 1. The heat generation amount of an incineration object that is currently incinerated based on the relationship between the current heat input amount and heat output amount of a fluidized bed furnace with a boiler, and the current dust supply based on the amount of garbage crane input and the rotation speed of the dust collector. Then, the total air amount of the combustion air is calculated from the heat generation amount and the dust supply amount, while the air ratio of the primary air for optimum combustion is calculated from the heat generation amount, and then the total air amount and the primary air amount are calculated. A method for controlling the amount of air in a fluidized bed furnace with a boiler, wherein the amount of primary air and the amount of secondary air are obtained from the air ratio of air, and the amount of primary air and the amount of secondary air are controlled.