JPS59195019A - Fluidized-bed type combustion furnace - Google Patents

Abstract

PURPOSE:To prevent production of NOX, by a method wherein the air fed to a fluidized-bed combustion furnace is divided into a primary air and a secondary air. CONSTITUTION:A furnace is provided with a first flow meter 12 for measuring the flow rate of a primary air, a second flow meter 14 for measuring the flow rate of a secondary air, an oxygen concentration meter 16 for measuring oxygen concentration in exhaust gas, and a computing part 17 which, based on output signals from the flow meters 12 and 14, and the oxygen concentration meter 16, computes an xygen concentration condition on a fludizied bed surface 18. A first regulating part 19 outputs a control signal which regulates the flow rate of a primary air, based on a deviation between an oxygen concentration condition outputted from the computing part 17 and a previously set oxygen concentration condition on the fluidized bed surface 18. A second regulating part 20 outputs a control signal which controls the flow rate of a secondary air so that an output signal from the oxygen concentration meter 16 attains a previously set value. This prevents production of NOX.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluidized bed combustion furnace, and in particular controls the amount of secondary air and the amount of secondary air to appropriate values to reduce nitrogen oxides N in exhaust gas.
The present invention relates to a fluidized bed combustion furnace for suppressing the generation of Ox and performing complete combustion.

In fluidized bed combustion, oil, oil,
Coal, garbage, sludge or various wastes at 700-900℃
It is a combustion method that burns with low humidity at the front and back, and because it burns at a lower temperature than the combustion temperature of normal coal boilers and oil boilers (approximately 130'0°C or more), there are very few paths for the generation of legal nitrogen oxides. However, some kind of countermeasure has been desired for the generation of nitrogen oxides (NOx) contained in the materials to be incinerated.

Here, the conventional flow jλ, the nitrogen oxidation of the fuel going into combustion'
To give an overview of the method of reducing 1 Gino, for example,
In the method disclosed in Publication No. 5-240058, air supplied to a fluidized bed incinerator is divided into primary air and secondary air,
The primary air flow supplied to the hearth is set to a value less than 1 times the theoretical air amount required for combustion of sludge plus auxiliary fuel,
The atmosphere on the surface of the fluidized bed is made reducing, and secondary air is supplied to the free board above the fluidized bed (thus, complete combustion is achieved. According to this method, the atmosphere above the fluidized bed becomes reducing). The nitrogen content from the nitrogen compounds in the incinerated material that is kept separately and thermally decomposed in that area is converted into nitrogen oxides NO.
However, it is believed to have the effect of suppressing the generation of a considerable amount of nitrogen oxide NOx. However, as described in the same publication, this method can only be applied to fluidized bed combustion of sludge. That is, if the theoretical air 1n required to burn the material to be incinerated supplied to the fluidized bed changes, the amount of secondary air may become excessive.

Therefore, it is said that this method can only be applied to the incineration of sludge in which the amount supplied to the fluidized bed is extremely stable and its components are constant. In addition, in order to eliminate the above-mentioned drawbacks of the method described in Japanese Patent Publication No. 55-24-005,
Publication No. 90 is published under Special Publication No. 55-24. Fluidized bed combustion is carried out under the most extreme conditions envisaged by the method in the OOS publication. That is, m of the primary air is set to the minimum amount of air at which the fluidized bed can perform appropriate fluidization, and the remaining amount of air necessary for complete combustion is supplied to the freeboard as secondary air. In fluidized bed combustion, it is difficult to reduce nitrogen oxides (NOx) by more than the method of Japanese Patent Publication No. 47-5790 just by the relationship between the secondary air skewer and the amount of secondary air.However, in general Combustion furnaces are not operated with a focus on the amount of nitrogen oxides (NOx) produced; they simply burn things (even if they are incinerators of
There are some things that must be done, and if the incinerator is equipped with a boiler or hot water heat exchanger, It is necessary to burn as much material as the load requires.Therefore, there are limits to applying the method disclosed in Japanese Patent Publication No. 17-5790 to current fluidized bed combustion furnaces.

As a method of overcoming the limitations of the above two methods, the method of Publication No. 17366 proposes supplying ammonia gas to the upper part of the fluidized bed. It is true that this method of adding ammonia gas can be used as a strong nitrogen oxide NOx reduction method, but since ammonia scum is constantly consumed during fluidized bed combustion, it is recommended to use the 1F11 bed when the load value is extremely high. Although it can be used for combustion, in many cases it cannot be used.The present invention was made in view of these circumstances, and the fluidized bed combustion furnace of the present invention 6. The fluidized bed combustion furnace of the present invention is capable of suppressing the amount of nitrogen oxides (NOx) produced by combusting sludge, sludge, various wastes, etc. This reduces the emission of not only nitrogen oxides (NOX) but also carbon monoxide (CO) or right-side smoke in the exhaust gas by 41'Ji.

The fluidized bed combustion furnace of the present invention is basically the above-mentioned
2 Il, In the same way as the invention described in Publication No. OO5, nitrogen oxide N is produced as a fuel by dividing the air supplied to a fluidized bed combustion furnace into primary air and primary air.

This is intended to suppress the occurrence of x.

The present invention provides a fluidized bed combustion furnace in which combustion air is divided into primary air supplied from the lower part of the fluidized bed and primary air supplied to a freeboard, and the primary air is supplied into the furnace.
A first flow meter 1 that measures the flow rate of secondary air, a second flow meter that measures the flow rate of secondary air, an oxygen Na gas meter that measures the oxygen concentration in the exhaust gas, and the flow rates of the first and second holes 12. a first operating section that calculates the state of oxygen (m) on the surface of the fluidized bed based on the output 'fi' fE from the oxygen concentration meter and the oxygen concentration meter; a first adjustment section that outputs an operation signal for adjusting the outflow of the primary air based on the deviation between the concentration state and the 82 degree oxygen state at the surface of the fluidized bed, which has been set to 82 degrees; This fluidized bed combustion furnace is equipped with a second adjustment section that outputs an operation signal for adjusting the outflow of secondary air so that the output signal from 12 degrees δ1 becomes a preset setting point.

Next, the fluidized bed combustion furnace of the present invention will be briefly explained using the drawings.

FIG. 1 is a schematic diagram of an embodiment of the fluidized bed combustion furnace of LJ Honsha "SU". The main body 1 of the fluidized bed combustion furnace consists of an air box 2, a fluidized bed 3, and a tree board 4. Between the air box 2 and the fluidized bed 3, air is distributed and introduced from the air box 2 to the fluidized bed 3. A dispersion plate 5 is provided.Incineration materials containing combustible materials such as coal are supplied to the fluidized bed 3 by a screw feeder 6.They are supplied to the main body 1 of the fluidized bed combustion furnace. The air is divided into primary air supplied from the lower part of the fluidized bed 3 and secondary air supplied to the freeboard 4. The secondary air is supplied by being introduced into the box 2, while the secondary air is sucked in by a fan 9 and is introduced into the freeboard 4 through a pipe 10 having air blowouts at multiple locations on the freeboard 4. It is supplied by

- The waste gas is sucked by an induction fan (not shown) through the exhaust gas duct 1'1 having an opening connected to the freeboard 4, and is similarly discharged into the atmosphere from a chimney (not shown). −
The primary air conduit 8 is provided with a first flow rate side 12 for measuring the flow rate of the primary air and a control valve 13 for adjusting the flow rate of the primary air. A second outflow field 14 for measuring the air flow height h4 and a control valve 15 for adjusting the outflow of secondary air are provided. The 1-1 gas duct 11 is provided with an oxygen concentration meter 16 for measuring the oxygen concentration in the J-1 gas.

The first calculation unit '17 outputs No. 481 S1 indicating the flow rate of the primary air output from the first flow mountain G112, and the second
The output signal 82 indicating the flow rate of primary air output from the flow meter 114 of There is one method in which the oxygen-enriched state on the surface 18 of 3 is determined by calculation. In this performance part 17 J-
3. The calculation calculates the flow mountain of the primary air specified by the output word S1 as QtCNv? >, the secondary air flow gutter specified by the output signal S2 is Q 2 (N Tel'
) and the oxygen concentration in the waste gas specified by the output signal 83 are expressed as x (%), 'l' = ((Ql +
Q2 ) · IC! - indicates a condition. That is, if Y=O, the supply amount of primary air is equal to the theoretical air amount,
If Y is a positive value, it indicates that the supply amount of negative air is larger than the theoretical air amount, and if Y is a negative value, the supply of primary air, 4B is 1! This shows that it is smaller than the theoretical air enclosure. -jlノ.

Therefore, the magnitude of the absolute value of Y corresponds to the magnitude of each degree. The arithmetic section 17 outputs an arithmetic expression Y representing the acid A jl/jl/attitude on the surface 18 of the fluidized bed 3 thus obtained as an output signal s4.

The first adjustment unit 19 has a function of outputting an operation signal for controlling the flow rate of primary air based on the output signal S4 from the first calculation unit 17, and has a function of outputting an operation signal for controlling the flow rate of primary air. part oxygen) 83 degree controller 190, control width limit calculator 19b
, - The numerical airflow network also consists of a sub-setting device '19C and - a numerical airflow master controller 196. Hearth part acid concentration adjustment 2it19aL; oxygen concentration state Y specified by the preset oxygen concentration state YO on the surface 18 of the fluidized bed 3 and the output signal @s4 from the calculation section 17 The controller 19b outputs output No. 5 S5 so that the deviation ΔY (ΔY=YO-Y) from , - Reference set in advance in the numerical airflow reference setting device 19C - Numerical airflow H>
By manually inputting the signal S6 corresponding to Qo, the following formula (2) is obtained.
is calculated and outputs a signal S7.

S7 = Se +2α (Ss-0,5)...(2) Here, α is the minimum flow rate (G mf ) required for fluidization of sand
ffr and prevents the bundle from running out of control in the event of poor control or poor oxygen concentration.
``i'' is the allowable width for J-SG.

If this is explained with reference to FIG. 2, the signal S7 corresponds to the signal $5 from O to 1, and the signal S7 becomes ±± with the signal S6 as the base.
Things that change within the range of α - (" d vine.

The lower limit value of this signal S7 is defined by (Slj-α). The flow rate is maintained above a value corresponding to the minimum flow rate (Gmf). Roughly speaking, the numerical airflow controller 19d takes the above-mentioned signal S7 as the set value, inputs the signal $1 from the first flowmeter 12, and the signal 81 becomes the signal S7.
This is a controller that outputs a signal S9 that operates the control valve 13 that controls the air flow rate.

Negative '12 adjustment section 20 is exhaust gas oxygen concentration! Smelling idiom 20a
and a secondary air flow monotonic fib 8120b, which inputs the output signal S3 from the acid concentration meter 16 and adjusts the secondary air flow rate so that the acid concentration in the exhaust gas becomes a preset value. It is an adjustable barrel that allows you to control the operation. This second. In the adjustment section 20, first, the signal $3 is input as the exhaust gas oxygen concentration adjustment ii' 2.0 a'\large input;
The signal S3 is output to the setting 1st shift SVO corresponding to the preset oxygen a degree value in the exhaust gas.J: The signal gS9 is output from the sea urchin exhaust gas oxygen concentration controller 20a. flt+Hf2011 exhaust gas acid purification melon style ill
Input the signal S9 from i'1M20a as the setting value,
Furthermore, it is a controller that inputs a signal S2 from the second flow rate side 14 and outputs a signal S+o that operates a regulating DO valve 15 that controls the secondary air flow rate so that the signal S2 becomes equal to the signal S]. . It is preferable to perform a proportional-integral-derivative (PID) operation as the control operation for the a3 city 2 hearth oxygen concentration adjustment cutter 19a and the exhaust gas oxygen concentration controller 20a.
In addition, the control operation of the numerical air flow m adjustment B+5 it i 9 d and the secondary air flow controller 20b is preferably proportional (P) operation when a boiler is installed on the side of the fluidized bed combustion equipment.
On the other hand, if the boiler is not installed, the proportional integral (P
I) It is preferable to spell it as action. In the fluidized bed combustion furnace of the present invention shown in FIG. ) Set the production state to the reducing range and keep the atmosphere of the combustion gas (approximately (combustion gas on the surface of the J fluidized bed)) immediately before being affected by water intake from the secondary air at the d3 platform to be always reducing. The amount of air supplied to the fluidized bed 3 must be maintained.
The nitrogen oxides NOx generated in the gas are reduced by the action of carbon monoxide gas CO.
ω will be significantly reduced to i.

In addition, in the present invention, the second adjustment section 20 controls the flow rate of the secondary air so that the oxygen concentration in the exhaust gas becomes a constant value, so that the combustible components in the combustion gas are effectively combusted and the visible 4r Ru to suppress the generation of smoke.

The present invention provides a fluidized bed combustion furnace in which combustion air is divided into primary air supplied from the lower part of the fluidized bed and primary air supplied to the freeboard and supplied into the furnace. The first flow rate side to be measured, the second flow rate ff1=l to measure the flow rate of secondary air, and the total oxygen concentration in the gas 1
a first calculation unit that determines the oxygen concentration state at the fluidized bed surface based on the output signals from the first and second flowmeters and the oxygen 'amaro'; The first
a first adjustment section that outputs an operation number for adjusting the flow rate of the primary air based on the deviation between the oxygen concentration state output from the calculation section and the preset oxygen concentration state on the surface of the fluid; , the output signal from the oxygen concentration H1 becomes a preset setting value (a fluidized bed combustion furnace is provided with a second adjustment section that outputs an operation signal for adjusting the flow rate of secondary air).

Therefore, according to the fluidized bed section and kiln of the present invention, the oxygen concentration state on the surface of the fluidized bed can be grasped without installing an expensive It is possible to reduce the amount of nitrogen oxide (NOx) in gas.Since the seismic intensity (oxygen in gas) is controlled independently, it is possible to suppress the generation of smoke on the right side at all times. It becomes possible to perform a complete combustion cycle.

In particular, in the conventional low nitrogen oxide NOX fluidized bed combustion furnace, only extremely homogeneous incineration materials such as sludge can be used, but in the present invention, it is possible to incinerate materials with a low calorific value such as municipal waste. Nitrogen oxides are heterogeneous and their changes are unpredictable.

This allows for combustion while suppressing the occurrence of x.

[Brief explanation of the drawing]

Figure 1 [J1 IL of a fluidized bed combustion furnace which is an embodiment of the present invention
This is a schematic diagram of λ, and Figure 2 shows the operation of the controller (four times). 1...furnace body 2...air box 3...fluidized bed 4...freeboard 5... air dispersion tentative
6...Screw feeder 7...Pushing fan 8
...Pipe line 9...Fan 10...Pipe line
11... Exhaust gas gas 91-12... First flow (i>
St, 13...Control valve 14...Second flow rate 15...Control valve 16...Oxygen'a meter 17...First stage part 18...Surface of fluidized bed 19...'1st adjustment section 19a...Heart part oxygen i/ratio controller 19b...control width limiter 19C...-Numerical airflow quality base 4 (setting device 19d
...-Number air flow monotone tti) it 20...
Second adjustment unit 20a...Exhaust gas oxygen concentration adjustment 11iiδ1 20b...Secondary airflow controller S1~
S 1o...Signal

Claims (1)

[Claims] The combustion air is divided into primary air supplied from the lower part of the fluidized bed and secondary air supplied to the freeboard, and the fluidized bed combustion furnace is supplied with the divided air into the furnace. flow ff1ffl, and a second one that measures the flow rate of secondary air.
An oxygen concentration meter that measures the flow Sl and the oxygen concentration in the J No. I gas, and an oxygen concentration meter that measures the oxygen concentration in the fluidized bed surface based on the output signal from the oxygen concentration meter and the flow Sl and the oxygen concentration in the A first calculation unit that calculates the concentration state; and a first calculation unit that calculates the concentration state; and a first adjustment section that outputs an operation signal to adjust the flow of the primary air based on the oxygen concentration h1; and an operation word that adjusts the flow rate of the secondary air so that the output signal from the oxygen concentration h1 becomes a preset value. A fluidized bed combustion furnace characterized by comprising: a second regulating section for outputting molten metal.