JPH0421084B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method of burning solid fuel such as coke, and more particularly to a method of burning solid fuel in a deposited layer within a combustion chamber.

Prior Art When a solid fuel such as coke is loaded and deposited in a combustion chamber and combustion air is passed from below to above the deposited layer, the supplied combustion air is combusted with the coke in the lower part of the deposited layer. Consumed in reaction. Coke becomes CO ₂ through a combustion reaction, but CO ₂ is reduced by the coke layer and becomes CO. Secondary air is introduced to completely burn this CO, but since the blowing is not controlled, the amount of secondary air becomes excessive at the end of combustion, the residual oxygen concentration in the combustion chamber increases, and the combustion chamber temperature increases. becomes high and the ash after coke combustion melts to produce clinker. When this clinker was produced, it became difficult to achieve stable combustion, and many other problems occurred, such as making it difficult to clean the inside of the combustion chamber.

Furthermore, when reducing the amount of combustion or stopping combustion, combustible matter tends to be transiently generated within the combustion chamber. Conventionally, when combustion air was supplied to restart combustion in a state where the concentration of combustibles was high, rapid combustion occurred and ignition noise was sometimes generated.

Purpose The purpose of the present invention is to solve the above-mentioned technical problem,
To make it possible to efficiently and stably burn solid fuel, and to prevent sudden combustion caused by transiently generated combustible matter immediately after reducing the amount of combustion or stopping combustion. The object of the present invention is to provide a solid fuel combustion method that enables the combustion of solid fuel.

Composition of the Invention The present invention provides a solid fuel combustion method in which primary air for combustion and a part of combustion exhaust gas are recirculated and supplied from below a deposited layer of solid fuel.
By controlling the supply of secondary air supplied from multiple nozzles provided above and below the peripheral wall of the combustion chamber in accordance with the amount of solid fuel deposited as combustion progresses, In addition to suppressing abnormal temperature rises in the combustion chamber, the amount of unburned gas generated in the combustion chamber when combustion is stopped or when the combustion amount is reduced is controlled by a control valve installed in the combustion exhaust gas path. The amount of unburnt gas generated in the combustion chamber is released from the combustion device by controlling the amount of recirculation to a relatively small amount and opening another control valve provided at the top of the combustion device. This is a solid fuel combustion method characterized by:

Effects According to the present invention, by controlling the supply of secondary air in accordance with the amount of solid fuel deposited, abnormal temperature rise in the solid fuel deposited layer is suppressed and clinker generation is prevented. If a large amount of unburned matter is generated in the combustion chamber, a control valve provided at the top of the combustion chamber is opened to release the unburned matter in the combustion chamber and maintain stable combustion.

Embodiment FIG. 1 is a system diagram of an embodiment of the present invention.
A grate 2 is arranged near the bottom of the combustion chamber 1,
Coke 3 is deposited on the grate 2. In order to ignite this coke 3, a burner 4 is installed in the combustion chamber 1. This burner 4 is supplied with liquid fuel or gas fuel. Ashes from the combustion of coke 3 are dropped from the grate 2 by an ash removing means 6, and the fallen ash is guided to a container 8 by a conveyor 7.

At the top of the combustion chamber 1, there is an inlet 9 and an inlet 9.
A door 10 for opening and closing is provided. Inlet port 9
, open the skip hopper 11 with the door 10 open.
Coke 3 is added. Door 10 during combustion
remains closed.

An exhaust gas outlet 13 is provided in the upper part of the combustion chamber 1, and the exhaust gas from the exhaust gas outlet 13 is sucked by a suction blower 17 from a pipe 14 through a heat exchanger 15 and a pipe 16, and is sent from a pipe 18 to a chimney. Guided by 19. A branch duct 20 is provided in the middle of the pipe 16, and the branch duct 20 supplies a part of the exhaust gas from the suction blower 21 to the pipe 22 below the grate 2 of the combustion chamber 1. Ru. Conduit 22
Primary air is supplied from a conduit 23 to a control valve 24 .

A passage 25 is formed in the combustion chamber 1, through which water as a heat medium flows. The water passed through the passage 25 and heated is guided from the pipe 26 to the heating chamber 28 via the circulation pump 27. The temperature of the heating chamber 28 is raised by the heated water.

The water from the heated chamber 28 is transferred from the pipe 29 to the pipe 3.
0, part of it is returned to the passage 25 provided outside the combustion chamber 1, and the other part is returned to the heat exchanger 15.
It is heated through a flow path 32 provided outside the pipe line 14 and guided to the passage 25.

Another outlet 3 provided at the top of the combustion chamber 1
A conduit 35 is connected to the chimney 4, which is connected to the middle of the chimney 19. In the middle of the pipe line 35, there is a stack valve 3.
6 is interposed.

The water to be used as a heat medium is directly transferred from the pipe 37 to the tank 38, passes through a flow path 39 provided in the pipe 35, is heated by the exhaust gas flowing through the pipe 35, and is returned to the tank 38. It will be done. Water from tank 38 is supplied to passage 25 via conduit 40.

A control valve 41 is interposed upstream of the suction blower 17 and downstream of the joining position of the pipe line 16 and the branch duct 20. In the branch duct 20,
A control valve 42 is interposed.

Referring to FIG. 2, a perspective view of the combustion chamber 1 is depicted. An annular header 4 surrounds the combustion chamber 1.
4, 45, and 46 are arranged in this order with an interval above and below.

FIG. 3 is a horizontal sectional view of a position near the header 44. The combustion chamber 1 is configured such that a passage 25 is formed between an outer wall 47 and an inner wall 48. Nozzles 49 having horizontal axes are arranged in the combustion chamber 1 at intervals in the circumferential direction. This nozzle 49 is commonly connected to the header 44. Similarly, nozzles 50 and 51 are connected to the headers 45 and 46. Secondary air is supplied to the headers 44, 45, and 46 via control valves 52, 53, and 54, and is selectively supplied into the combustion chamber 1 from nozzles 49 to 51 in accordance with the amount of coke 3 deposited. be done. The nozzle 51 located at the bottom is above the grate 2. Secondary air is sent to coke 3 from nozzles 49 to 51.
By injecting the coke into the deposited layer, the coke can be completely combusted.

FIG. 4 is a cross-sectional view of the stack valve 36. In the stack valve 36, an exhaust pipe 56 that extends vertically is fixed to the upper part 55 of the combustion chamber 1. The lower part of the exhaust pipe 56 serves as an outlet 34 and opens into the combustion chamber 1 . A seal seat 57 is fixed to the upper part of the exhaust pipe 56. By means of a pin 58 having a horizontal axis,
The lid 59 is seated on the seal seat 57 to close the outlet 34 as shown in FIG. 4, and can be opened by being angularly displaced clockwise in FIG. 4 about the axis of the pin 58. A connecting member 6 is connected to the lid 59 by a pin 60.
1 is supported. A long hole 62 is formed in the connecting member 61 . The long hole 62 has a drive arm 6
A protrusion 64 fixed to one end of 3 is fitted.
The other end of the drive arm 63 is connected to a drive shaft 65 having a horizontal axis. exhaust pipe 56, lid 59,
The connecting member 61 and the drive arm 63 are housed in a cover body 66, and the upper part of the cover body 66 is connected to the pipe line 3.
5.

When the pressure inside the combustion chamber 1 becomes high, the lid 59
is pushed up, the gas inside the combustion chamber is discharged to the pipe 35, and safety is maintained. As will be described later, when stopping the combustion of coke 3, the drive shaft 65,
Therefore, the drive arm 63 is angularly displaced clockwise in FIG. 4, and the lid 59 is opened as shown by the imaginary line 59a.

The combustion control state will be explained with reference to FIG.
During high-load combustion before time t1, the suction blower 17 is operating as shown in FIG. 51, and the suction blower 21 is also operating as shown in FIG. 52. The combustion exhaust gas generated in the combustion chamber 1 is transferred to the pipe 14, the heat exchanger 15, and the pipe 1.
6 and is suctioned by the suction blower 17 from the control valve 41 which is fully open as shown in FIG. A part of the exhaust gas is transferred to the pipe 18
It is then discharged from the chimney 19. On the other hand, as shown in FIG.
and guided to the conduit 22. Conduit 2
Control valve 24 of pipe 23 connected in the middle of 2
is fully open as shown in FIG. 5, so 1
Secondary air is introduced into the pipe 22, and the remainder of the exhaust gas is mixed with the primary air and supplied to the lower part of the combustion chamber 1.

The upper part of the coke 3 deposit in the combustion chamber 1 is the nozzle 4.
9, the control valve 52 is fully open as shown in FIG. 5, the control valve 53 is fully open as shown in FIG. 5, and the control valve 53 is fully open as shown in FIG. Since the control valve 54 is fully opened at 2.
Air is distributed and supplied into the deposited layer of coke 3 from the nozzles 49 to 51.

Stack valve 36 provided at the top of the combustion chamber 1
is closed as shown in FIG. 5, and no combustion exhaust gas flows into the pipe 35. As described above, when the pressure inside the combustion chamber 1 becomes high, the stack valve 36 is opened by the pressure, thereby reducing the pressure inside the combustion chamber 1. In this way, high-load combustion is kept stable and safe.

In FIG. 5, even during low-load combustion from time t1 to time t4, the suction blowers 17, 21
is working. In order to change from high-load combustion to low-load combustion, it is necessary to reduce the amount of combustion air supplied to the combustion chamber 1. Since the control valve 41 is half-opened at time t1 as shown in FIG. 5, the amount of combustion air supplied is reduced. At time t1, the control valve 4 as shown in FIG.
2 is closed and becomes half open at time t3.

FIG. 6 is a diagram showing the experimental results of the inventor of the present invention. FIG. 6 1 shows the relationship between the amount of coke 3 burned and time, and FIG. 6 2 shows the relationship between the combustible content concentration in the combustion exhaust gas in the combustion chamber 1 and time. According to the experiment conducted by the inventor of the present invention, by closing the control valve 42 at time t1 as described above, the combustible content concentration initially decreases by a small amount, as shown by the solid line in FIG. The value becomes high, but decreases after time tp, and reaches a stable value at time t3. If the control valve 42
If it is kept fully open or half open after time t1, the combustible content concentration will gradually increase as shown by the virtual line. In a state where the combustible content is at a high concentration, rapid combustion occurs, which may cause ignition noise. During the transition period W1 from high-load combustion to low-load combustion, the control valve 42 is closed and the combustible content is removed. By stopping the recirculation of the contained exhaust gases, stable combustion conditions can be maintained.

During this low-load combustion, the supply of secondary air is limited, but during the transition period W1 from high-load combustion to low-load combustion, the control valves 52 to 52 By continuing to fully open 54, the reduction in the combustible content concentration can be accelerated. After time t2, the control valves 52 to 54
is partially opened to limit the supply of secondary air. During this period, the operation of the control valve 52 is as shown in FIG.
3 is shown in FIG. 5, and the control valve 54 is shown in FIG. 5, respectively.

Even during low-load combustion, the stack valve 36 remains closed unless the pressure inside the combustion chamber 1 becomes high.

In FIG. 5, combustion is stopped from time t4 to time t7. As shown in FIG. 5, the suction blower 2 at time t4
1 is stopped and the recirculation of exhaust gases into the combustion chamber 1 is stopped by closing the control valve 42 as shown in FIG. Suction blower 17
is operated until time t5 after a predetermined time W2 has elapsed, as shown in FIG. 5, and the exhaust gas in the combustion chamber 1 is discharged. At time t5 when the recycle gas is completely cut off, the suction blower 17 is stopped.

As shown in FIG. 5, the control valve 41 is kept half open until time t5, and the suction blower 1
7 is stopped, it is fully opened, and exhaust gas is discharged after time t5 due to the natural draft force of the chimney 19.

The control valve 24 is kept fully open until time t5, as shown in FIG.
The opening degree is maintained in accordance with the natural draft force, and a state where re-combustion is possible is maintained. Further, at time t5, the upper part of the deposited layer of coke 3 is at position 70 (first
As shown in FIG. 5, the control valve 52 is fully open as shown in FIG. 5, the control valve 53 is fully open as shown in FIG. 5, and the control valve 53 is fully open as shown in FIG. The control valve 54 is fully opened. By this operation, a large amount of secondary air is sent into the coke layer, and the combustibles remaining in the furnace are burned and quickly discharged from the combustion chamber 1.

As shown in FIG. 5, the stack valve 36 is fully opened at time t6 during the combustion stop period, and the combustion chamber 1 is closed due to the natural draft force of the chimney 19.
This prevents exhaust gas from accumulating inside the tank.

In FIG. 5, after time t7, a state in which high-load combustion has been restarted is shown. As shown in FIG. 5, at time t7, the stack valve 3
6 is closed, and the suction blower 17 is closed as shown in FIG.
is activated. At time t8, when the concentration of combustibles in the exhaust gas in the combustion chamber 1 becomes extremely low, as shown in FIG.
The suction blower 21 is activated as shown in FIG.
Similarly, the control valve 42 is fully opened as shown in FIG. 5, and the control valve 24 shown in FIG. 5 is also fully opened. These operations restart high-load combustion.

Time t9 shown in FIG. 5 is when the top of the pile of burning coke 3 reaches position 71 (imaginary line in FIG. 1), that is, below the position of the nozzle 49 for supplying secondary air. Indicates the point in time. Nozzle 4
Since the secondary air from the exhaust gas outlet 13 bypasses the exhaust gas outlet 13 and the combustion efficiency deteriorates, the control valve 52 is closed and the supply of secondary air from the nozzle 49 is stopped. When the combustion progresses further and the upper part of the deposited layer reaches position 72, the control valve 53 is further closed and the supply of secondary air from the nozzle 50 is stopped.

By controlling the combustion of coke 3 as described above, stable and efficient combustion is possible, and no clinker is generated.

Referring to FIGS. 1 and 2, control valves 52 to 54 are operated at intervals set by a timer to control secondary air according to positions 70 to 72 above the deposited layer of coke 3. may be controlled as described above, or means for detecting the positions 70-72 of the deposited layer may be provided to control the control valves 52-54.

Although coke was described as a solid fuel in the above embodiment, the present invention is also applicable to the combustion of solid fuels other than coke.

In the above embodiment, the structure for supplying secondary air is described in which three stages of headers 44 to 46 are provided as shown in FIGS. 2 and 3, but a plurality of headers may be used as appropriate. It may be provided. Further, it is not always necessary to use a header; for example, the side wall of the combustion chamber 1 may have an air jacket structure.

As another embodiment of the present invention, the medium to be heated may be air, and the present invention may be applied to other combustion devices such as hot air blowers.

As a further embodiment of the present invention, the stack valve 36 provided above the outlet 34 of the upper part 55 of the combustion chamber 1 is replaced by a pipe 75 on the upstream side of the pipe 14 as shown in FIG. It may also be arranged and joined on top of it. Furthermore, the stack valve 36 is not limited to the structure shown in FIG. 4, but may have other structures that perform the same function.

As another embodiment of the present invention, the exhaust gas path system may be configured as shown in FIG. 8, and the exhaust gas may be circulated only by the suction blower 17, or the control valves 41 and 42 may be connected to the suction blower as shown in FIG. They may be arranged downstream of 17 and 21, respectively.

Effects As described above, according to the present invention, primary air is supplied from below to above the solid fuel accumulation layer, and secondary air is distributed and supplied above and below the accumulation layer, and With changes in the amount of solid fuel deposited,
By changing the distribution method of secondary air to prevent clinker formation, we also prevent unburned gases that may be generated in the combustion chamber when stopping combustion or reducing the combustion rate to the combustion chamber. Stable combustion can be achieved by opening the provided control valve and discharging.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention, FIG. 2 is a perspective view of a combustion chamber 1 of an embodiment of the present invention, and FIG. 3 is a horizontal sectional view of the position near the header 44.
FIG. 4 is a sectional view of the stack valve 36, FIG. 5 is a diagram showing the combustion control state, FIG. 6 is a diagram regarding the CO concentration in exhaust gas, and FIG. 7 is for explaining still another embodiment of the present invention. , FIG. 8, and FIG. 9 are diagrams for explaining other embodiments of the present invention. 1... Combustion chamber, 3... Coke, 36... Stack valve, 42... Control valve.

Claims (1)

[Claims] 1 In a solid fuel combustion method in which primary air for combustion and part of the combustion exhaust gas are recirculated and supplied from below the solid fuel accumulation layer, multiple combustion chambers are provided above and below on the peripheral wall of the combustion chamber. By controlling the supply of secondary air supplied from a nozzle according to the amount of solid fuel deposited as combustion progresses, abnormal temperature rise inside the solid fuel deposit layer is suppressed and combustion is suppressed. A control valve installed in the combustion exhaust gas path controls the amount of recirculation of combustion exhaust gas to reduce the amount of unburned gas generated in the combustion chamber when the combustion chamber is stopped or when the combustion amount is reduced. 1. A method for burning a solid fuel, characterized in that unburned gas generated in a combustion chamber is released from a combustion device by suppressing the amount of gas generated in the combustion chamber and opening another control valve provided at the top of the combustion device.