JP2623404B2 - Operating method and apparatus of fluidized bed incinerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a fluidized-bed incinerator, and more particularly to a fluidized-bed incinerator for incinerating raw materials whose quality and quantity change such as municipal solid waste and industrial waste. The present invention relates to an operation method when the power is cut off and a device therefor.

[0002]

2. Description of the Related Art FIG. 2 shows a schematic diagram of a conventional general fluidized bed municipal waste incineration plant. The refuse introduced into the furnace falls into a fluidized bed 1 (here, sand is a fluidized medium) which is usually maintained at 600 ° C. to 750 ° C., and is crushed in the sand. The fuel burns inside, and the remainder becomes combustible gas, which burns in the combustion chamber 2 above it. At this time, the combustible gas from the fluidized bed 1 is supplied at a constant rate, and the amount of air corresponding thereto (the forced air 11 is supplied to the hearth 1 and the secondary air 14
Needs to be supplied to the combustion chamber 2). But,
In extreme cases, due to non-uniform waste quality and fluctuations in the amount of dust supplied by the duster, a large amount of garbage can enter at a time (dropping) or almost no garbage can enter (out of garbage).
The supply speed of combustible gas fluctuates greatly.

[0003] In the case of falling down of refuse, the amount of combustible gas in the combustion chamber rapidly increases, so that the amount of air pushed into the hearth is reduced as far as incombustibles can be extracted, and the hearth is reduced. It slows the flow and stabilizes the supply of combustible gas.
However, in the case of exhaustion, the amount of combustible gas in the combustion chamber sharply decreases, and unless the input amount of the secondary air 14 and the amount of forced air 11 are properly reduced, the furnace temperature decreases and C
Unburned substances such as O are generated. Generally, when the amount of air discharged from the blower is extremely reduced, the blower generates abnormal vibration due to so-called surging. For this reason, in the related art, surging is prevented by setting the lower limit of the secondary air input amount, but unburned matter such as CO has been generated due to the above-mentioned waste.

[0004]

SUMMARY OF THE INVENTION According to the present invention, there is provided a flow system capable of preventing the surging of a blower, closing the flow of secondary air into a combustion chamber when the raw material runs out, and reducing the amount of air forced into the hearth. An object of the present invention is to provide a method of operating a floor incinerator and an apparatus therefor.

[0005]

According to the present invention, there is provided a method for operating a fluidized bed incinerator for incinerating a raw material which varies in both quality and quantity. Closing the inflow of the secondary air into the combustion chamber;
The secondary air is circulated through a secondary air circulation line via a secondary air blower, or flows into an exhaust gas passage downstream of the combustion chamber. Further, in the above, a part of the forced air is caused to flow into the exhaust gas passage downstream of the combustion chamber.

According to the present invention, there is provided a fluidized bed incinerator for incinerating a raw material which varies in both quality and quantity, a means for detecting exhaustion of the raw material in the incinerator, and a secondary air blower is provided in the secondary air supply system. And a secondary air inflow adjusting damper for closing the inflow of excessive secondary air when the exhaustion of the raw material is detected, and a secondary air circulation line via the secondary air blower is provided, Alternatively, a secondary air bypass line for introducing secondary air into an exhaust gas passage downstream of the combustion chamber is provided. Further, in the above device, the forced air supply system is provided with a forced air bypass line that allows a part of the forced air to flow into an exhaust gas passage downstream of the combustion chamber.

In the present invention, as a means for detecting the exhaustion of the raw material in the incinerator, generally, when the raw material is exhausted, the output of the flame sensor (means for detecting the radiated light from the flame) decreases, and the pressure in the furnace and the internal pressure of the furnace are reduced. The temperature also drops. On the other hand, since the furnace O ₂ concentration is increased, it is possible to detect the raw material out by measuring these signals alone or in combination. Of these, the combination of the frame sensor and the in-furnace pressure gauge is the fastest and most effective. The secondary air flow is determined by these detected signals and their rate of change.

[0008]

In general, if the amount of secondary air is reduced to a predetermined amount or less, the blower may be subject to surging. The following four methods are conceivable as the prevention means. (1) Speed control of blower Inverter control. However, the response is slow, and rapid control is difficult. (2) Use of in-surge type blower A blower that does not easily cause surging. However, the efficiency of the blower is poor. (3) Circulation of bypass The excess air is circulated through the bypass line (return line) without reducing the amount of air discharged from the blower. (4) Change of supply destination The excess air supply destination is changed to the downstream side of the incinerator without reducing the discharge air volume of the blower. Among these, the means (3) and (4) are effective from the viewpoint of responsiveness and fan efficiency.

According to the present invention, the secondary air having a secondary air flow rate equal to or higher than the secondary air flow rate determined based on the signal detected as described above,
By circulating the secondary air circulation line or supplying the air downstream of the combustion chamber, it is possible to prevent surging of the blower and to shut off excess air from flowing into the combustion chamber of the secondary air when the raw material runs out. Thus, the furnace temperature can be maintained. When the flame signal is low, a part of the forced air is supplied to the downstream of the combustion chamber similarly to the secondary air. This can reduce excessive inflow of air into the hearth and the combustion chamber, and maintain the temperature in the furnace of the combustion chamber.

[0010]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. Embodiment 1 FIG. 1 shows a schematic configuration diagram of a fluidized bed incinerator using a waste incineration facility of the present invention as an example. In FIG. 1, the fluidized bed incinerator has a fluidized bed portion 1 at a lower portion and a combustion chamber 2 at an upper portion, and forced air 11 is blown into the fluidized bed portion.
Next air 14 is blown. Part of the refuse input from the refuse input / supply machine 3 is partially burned in the fluidized bed portion 1, and the other portion is gasified and burned in the combustion chamber 2. The flue gas passes through the flue gas passage 17, enters the temperature reducing tower 4, is cooled down by the dust removing device 5, and is discharged from the chimney 7 by the induction blower 6.

A flame sensor 18 and an in-furnace pressure gauge 19 are provided above the combustion chamber 2 of the fluidized bed incinerator, and an in-furnace O ₂ meter 20 is provided in the exhaust gas passage of the combustion chamber.
Is provided. The supply system of the forced air 11 is provided with a forced blower 8, a forced air bypass line 12 having a damper 21 on the way to be connected to the exhaust gas passage, and a bypass line 13 having a damper 22 communicating with a lower portion of the combustion chamber 2. The secondary air 14 supply system includes a secondary air blower 9, a secondary air inflow adjusting damper 10, and a secondary air circulation line having a damper 23 connecting an outlet and an inlet of the blower 9. , Adjustment damper 10 and immediately before and exhaust gas passage 17
And a bypass line 16 having a damper 24 connecting the first and second members.

In the thus constructed apparatus, when the output signals of the frame sensor 18 and the in-furnace pressure gauge 19 decrease and the exhaustion of the raw material is detected, the damper 10 for adjusting the inflow of the secondary air is closed. By passing the next air through the circulation line 15 and the bypass line 16, surging of the blower can be prevented. Further, when the flame signal is low, a part of the pushing air is supplied to the exhaust gas passage using the bypass line 12, so that the temperature in the combustion chamber furnace can be maintained. In FIG. 1, a part of the secondary air and the pushing air is supplied to the dust-removing device inlet. However, the supply destination of the secondary air and the pushing air is not limited to the dust-removing device inlet, and is supplied downstream of the combustion chamber. If there is, there is no problem even at the inlet of the cooling tower and the outlet of the dust removal device.

FIG. 3 and FIG. 4 show the results of detection of waste. As shown in FIG. 3, the output of the frame sensor decreases and the furnace temperature also decreases. On the other hand, from FIG. 4, the O ₂ concentration in the furnace increases, and the wet O ₂ concentration and the CO concentration in the furnace also increase. FIGS. 5 and 6 show the results obtained by installing a secondary air bypass line and a forced air bypass line to shut off excess secondary air and forced air from flowing into the combustion chamber. From FIG. 5, the furnace temperature and the furnace temperature are almost constant even when the output from the flame is reduced. From FIG. 6, the furnace O ₂ concentration and the furnace C
The variation in the O concentration is also small, and the variation in the CO concentration in the smoke outlet is also very small.

[0014]

As described above, according to the present invention, the supply amount of the secondary air and the pushing air into the furnace can be changed without changing the output of the blower, so that the surging of the blower can be prevented. Secondly, since the amount of secondary air and the amount of forced air can be quickly changed according to the exhaustion of the raw material, the fluctuations in the furnace temperature and the CO concentration at the smoke outlet can be suppressed to a very small amount.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a fluidized bed incinerator of the present invention.

FIG. 2 is a schematic configuration diagram of a conventional fluidized bed incinerator.

FIG. 3 is a diagram showing a change in a frame signal, a furnace temperature, and a furnace temperature when a material shortage is detected.

FIG. 4 is a graph showing changes in the inside of the furnace and the wet O ₂ concentration and the inside of the furnace and the CO concentration at the smoke outlet when the exhaustion of the raw material is detected.

FIG. 5 is a diagram showing a change in a flame signal, a furnace temperature, and a furnace section temperature when the air amount is controlled according to the present invention.

FIG. 6 shows the inside of the furnace and the wetness O when the air amount is controlled according to the present invention.
Change diagram of ₂ concentration, CO concentration in furnace and stack outlet.

[Explanation of symbols]

1: fluidized bed, 2: combustion chamber, 3: refuse duster, 4:
Cooling tower, 5: dust removal device, 6: induction blower, 7: chimney,
8: push-in blower, 9: secondary blower, 10: damper for adjusting secondary air inflow, 11: push-in air, 12, 13: push-in air bypass line, 14: secondary air, 15: secondary air circulation line, 16 : Secondary air bypass line, 17: exhaust gas passage, 18: flame sensor, 19: furnace pressure gauge, 2
0: furnace O ₂ meter, 21, 22, 23, 24: damper

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Ryuichi Ishikawa 11-1 Haneda Asahimachi, Ota-ku, Tokyo Ebara Corporation (56) References JP-A-3-230007 (JP, A) JP-A Sho 60-238608 (JP, A) JP-A-3-122414 (JP, A)

Claims (4)

(57) [Claims] 1. A method of operating a fluidized bed incinerator for incinerating a raw material that varies in both quality and quantity, wherein when the exhaustion of the raw material is detected, the flow of excess secondary air into the combustion chamber is closed, Of a fluidized bed incinerator characterized by circulating water through a secondary air circulation line via a secondary air blower or into an exhaust gas passage downstream of a combustion chamber. 2. The method of operating a fluidized bed incinerator according to claim 1, wherein a part of the pressurized air further flows into an exhaust gas passage downstream of the combustion chamber. 3. A fluidized bed incinerator for incinerating a raw material that varies in both quality and quantity, comprising means for detecting a raw material shortage in an incinerator, a secondary air supply system and a secondary air blower and the raw material shortage. And a secondary air inflow adjustment damper for closing the inflow of excessive secondary air when the secondary air blower is detected, and a secondary air circulation line via the secondary air blower is provided, or A fluidized bed incinerator characterized by providing a secondary air bypass line for flowing gas into an exhaust gas passage downstream of the combustion chamber. 4. A fluidized bed incinerator according to claim 3, wherein the forced air supply system is provided with a forced air bypass line for allowing a part of the forced air to flow into an exhaust gas passage downstream of the combustion chamber.