JPS60256706A - Combustion method of solid fuel - Google Patents

Abstract

PURPOSE:To improve an efficiency of a combustion by changing a dispersion method of a secondary air following to a decrease of a fuel, with a primary air is supplied upwardly from a lower part of a deposited layer of a solid fuel, and the secondary air is supplied being dispersed over upper and lower sides of the former. CONSTITUTION:A primary air is introduced into a pipe line 22, a remainder of an exhaust gas and the primary air is supplied to a lower part of a combustion chamber 1 after being mixed. A control valve 52 is closed and a supply of a secondary air from a nozzle 49 is stopped, since the secondary air from the nozzle 45 is by-passed to an outlet port 13 of the exhaust gas, and an efficiency of a combustion is made worse, when an upper part of a diposited layer of a burning coke 3 is reached to a position 71, that is, the former is descended lower than a position of the nozzle 45 for the supply of the secondary air. Further, a control valve 53 is closed and the supply of the secondary air from a nozzle 50 is stopped, when the upper part of the deposited layer is reached to a position 72 owing to a progress of the combustion. Thereby, a stable and excellently effective combustion can be accomplished.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a method of burning solid fuel such as coke,
In particular, the present invention relates to a combustion method for burning solid fuel in a deposited layer within a combustion chamber.

Prior Art When a solid fuel such as coke is charged 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 CO2 through a combustion reaction, but % CO2 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. Clinker is produced by melting the ash after coke combustion, which is not high in coke. When this clinker is produced, it becomes difficult to achieve stable combustion, and many other problems occur, such as making it difficult to clean the inside of the combustion chamber.

Purpose An object of the present invention is to provide a solid fuel combustion method that solves the above-mentioned technical problems and allows solid fuel to be burned efficiently and stably.

Example FIG. 1 is a system diagram of one embodiment of the present invention.

A grate 2 is arranged near the bottom of the combustion chamber 1, and 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. From the grate 2, ash from the combustion of the coke 3 is dropped by an ash removal means 6, and a door 10 is provided which opens and closes the fallen ash by a conveyor 7. Inlet port 9
Coke 3 is charged from the skip hopper 11 with the door 10 open. The door 10 remains closed during combustion.

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 blown from a pipe 14 through a heat exchanger 15 and a pipe 16 by a suction blower 17, and is sent from a pipe 18 to a chimney 19. be guided. A branch duct 20 is provided in the middle of the pipe 16, and a part of the exhaust gas passing through the branch duct 20 is supplied from a suction blower 21 to a pipe 22 below the grate 2 of the combustion chamber 1. Ru. Primary air is supplied to the pipe line 22 from a pipe line 23 via 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
It is guided from the pipe line 26 to the heating chamber 28 via the circulation pump 27. The temperature of the heating chamber 28 is raised by the heated water.

Water from the heating chamber 28 is returned to the passage 25 provided outside the combustion chamber 1 via a pipe 29 and a pipe 30, and a portion of the water heated by the heat exchanger 15 is also returned to the pipe 30. It is heated through a flow path 32 provided outside the path 14 and led to the path 25.

Another outlet 34 provided in the upper part of the combustion chamber 1 has a
A stack valve 36 is interposed in the middle of the pipe 35 to which the pipe 35 is connected and which is connected to the chimney 19 midway.

The water to be used as a heat medium is transferred from the pipe 37 to the tank 38 immediately after, and also to the flow channel 39 provided in the pipe 35.
The water is heated by the exhaust gas flowing through the pipe 35 and returned to the tank 38. Water from the tank 38 is supplied to the passage 25 via the pipe 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 exhaust duct 20. A control valve 42 is interposed in the exhaust duct 20 .

Referring to FIG. 2, a perspective view of the combustion chamber l is depicted. Surrounding the combustion chamber 1, annular headers 44, 45, and 46 are vertically spaced apart and arranged in this order.

FIG. 3 is a horizontal sectional view of a position near the header 42. The combustion chamber 1 has a passage 25 between an outer wall 47 and an inner wall 48.
is formed and composed. Nozzles 49 having horizontal axes are arranged in the combustion chamber 1 at regular intervals in the circumferential direction. This nozzle 49 is commonly connected to the header 44. Similarly, nozzles 50 and 51 are connected to pegs 45 and 46. Control valves 52 and 5 are provided in the headers 45 and 46.
3° 54, the coke 3 is selectively supplied into the combustion chamber 1 from the nozzles 49 to 51 in accordance with the amount of coke 3 deposited.

The nozzle 51 located at the bottom is above the grate 2. By blowing secondary air into the deposited layer of coke 3 from the nozzles 49 to 51, the coke can be completely combusted.

FIG. 4 is a cross-sectional view of the stack valve 36. The stack valve 36 has an exhaust pipe 56 extending vertically in the upper part 55 of the combustion chamber 1.
is fixed. The lower part of the exhaust pipe 56 serves as an outlet 34 and opens into the combustion chamber l. A seal seat 57 is fixed to the upper part of the exhaust pipe 56. Pin 5 with horizontal axis
8, the lid 59 is attached to the seal seat 57 as shown in the fourth figure.
It can be seated on top to block the outlet 34 and opened by angular displacement clockwise in FIG. 4 about the axis of the pin 58. A connecting member 61 is pivotally supported on the lid 59 by a pin 60. A long hole 62 is formed in the connecting member 61 . A protrusion 64 fixed to one end of the drive arm 63 is fitted into the elongated hole 62 .

The other end of the drive arm 63 is connected to a drive shaft 65 having a horizontal axis.
is connected to. Exhaust pipe 56, lid 59, connecting member 61
and the drive arm 63 is housed within the cover unit 66,
The upper part of the cover unit 66 is connected to the pipe line 35.

When the pressure inside the combustion chamber 1 becomes high, the lid 59 is pushed up and the gas inside the combustion chamber is discharged to the pipe line 35, thereby maintaining safety. As will be described later, when the combustion of the coke 3 is stopped, the drive shaft 65 and therefore the drive arm 63 are angularly displaced clockwise in FIG.
The valve becomes open as shown by a.

The combustion control state will be explained with reference to FIG.

During high-load combustion before time t1, Fig. 5 (1)
As shown in , the suction blower 17 is operating.
In addition, as shown in FIG. 5 (2), the suction blower 21
is also working. The combustion exhaust gas generated in the combustion chamber 1 passes through the pipe 14, the heat exchanger 15, and the pipe 16 in sequence as shown in Fig. 5 (3).
), air is sucked by the suction blower 17 from the control valve 41 which is fully open. A part of the exhaust gas is discharged from the chimney 19 via the pipe 18. on the other hand,
The remainder of the exhaust gas is passed from the control valve 42 through the exhaust duct 20 to the suction blower 21, as shown in FIG. 5(4).
is absorbed by and guided into the conduit 22. The control valve 24 of the pipe line 23 connected in the middle of the pipe line 22 is shown in FIG.
), it is fully open, so the primary air flows into pipe 2.
The remainder of the exhaust gas is mixed with primary air and supplied to the lower part of the combustion chamber 1.

When the top of the coke 3 deposit in the combustion chamber 1 is near the height of the nozzle 49, the control valve 52 is fully opened as shown in FIG. 5(6), and the control valve 52 is fully opened as shown in FIG. 5(7). As shown in FIG. 5(8), the control valve 53 is fully opened, and the control valve 54 is fully open as shown in FIG.
51, it is distributed and supplied into the deposited layer of coke 3.

The stack valve 36 provided at the upper part of the combustion chamber 1 is closed as shown in FIG. 5 (9), and the pipe line 35 is closed.
No combustion exhaust gas flows into the tank. Combustion chamber 1 as mentioned above
When the pressure inside the combustion chamber 1 becomes high, the stun valve 36 opens due to the pressure (reducing the pressure inside the combustion chamber 1).In this way, high-load combustion is stabilized and safe. is maintained.

In FIG. 5, the suction blower 17.21 is in operation even during low-load combustion from time tl to time t4. 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. Figure 5 (3)
As shown in FIG. 2, the control valve 41 is half-opened at time t1, so the amount of combustion air supplied is reduced. At time t1, the control valve 42 is closed as shown in FIG. 5(4), and at time t3 it is half open.

FIG. 6 is a diagram showing the experimental results of the inventor of the present invention. Figure 6 (1) shows the relationship between the amount of combustion of coke 3 and time,
FIG. 6(2) shows the relationship between the concentration of combustible substances in the combustion exhaust gas in the combustion chamber 1 and time. According to the inventor's experiments, by closing the control valve 42 at time t1 as described above, as shown by the solid line in FIG. 6(2),
The combustible content concentration initially becomes a little high, but decreases after time tp, and reaches a stable value at time t3. If the control valve 42 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 at time t during the transition period W1 from high-load combustion to low-load combustion.
By keeping the control valves 52 to 54 fully open from 1 to time t2, which is a predetermined time later, the combustible concentration can be reduced more quickly. After time t2, the control valves 52 to 54 are half-opened to limit the supply of secondary air. The operations during this time are shown in FIG. 5(6) for the control valve 52, FIG. 5(7) for the control valve 53, and FIG. 5(8) for the control valve 54, 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 t44 to time t7. As shown in FIG. 5(2), the suction blower 21 is stopped at time t4, and as shown in FIG. By closing the control valve 42 as shown in 4), the recirculation of the exhaust gas into the combustion chamber 1 is stopped. The suction blower 17 is operated until a time t5 after a predetermined time W2 has elapsed, as shown in FIG. 5(1), 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(3), the control valve 41 is kept half open until time t5, and is fully opened at the same time as the suction blower 17 is stopped, and due to the natural draft force of the chimney 19, the control valve 41 is kept half open until time t5. After t5, exhaust gas is discharged.

The control valve 24 is kept fully open until time t5, as shown in FIG. It is maintained. Also, at time t5, the top of the deposited layer of coke 3 is at position 70 (imaginary line in FIG. 1), so the fifth
As shown in FIG. 16), the control valve 52 is fully open, and as shown in FIG. 5(7), the control valve 53 is fully open.
As shown in FIG. 5(8), 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(9), the stack valve 36 is fully opened at time t6 during the combustion stop period, and the stack valve 36 is fully opened.
The natural draft force prevents the exhaust gas from accumulating in the combustion chamber 1.

In FIG. 5, after time t7, a state in which high-load combustion has been restarted is shown. As shown in FIG. 5(8), the stack valve 36 is closed at time t7, and the suction blower 17' is operated as shown in FIG. 5(1).

At time t8, when the concentration of combustibles in the exhaust gas in the combustion chamber 1, 4.1, became extremely low, 1 in Fig. 5 (2)
The suction blower 21 is activated as shown in .

Similarly, the control valve 42 is fully opened as shown in Figure 5 (4), and the control valve 24 is also fully opened as shown in Figure 5 (5). 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, when it is lower than the position of the nozzle 45 for supplying secondary air. Show t. Since the secondary air from the nozzle 45 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 top of the deposited layer reaches position 72, the control valve 53 is further closed and the supply of secondary air from the noil 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 the position of the deposited layer 70~
72 may be provided to control the control valves 52-54.

In the above example, coke was described as a solid fuel, but
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 includes three stages of headers 4 as shown in FIGS. 2 and 3.
Although the case where headers 4 to 46 are provided has been described, a plurality of headers may be provided as appropriate. 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 invention, the upper part 55 of the combustion chamber 1
The stack valve 36 provided above the outlet 34 of
As shown in FIG. 7, a pipe line 75 may be disposed midway on the upstream side of the pipe line 14 and joined to the upper part thereof. Also stack valve 3
6 is not limited to the structure shown in FIG. 4, but may have other structures that function similarly.

As another embodiment of the present invention, according to the present invention, primary air is supplied from below to above the solid fuel accumulation layer, and secondary air is accumulated in the exhaust gas path system as described above. Combustion efficiency can be increased and the formation of tarinka can be prevented by supplying fuel in a distributed manner across the top and bottom of the layer, and by changing the method of dispersing secondary air as the amount of fuel deposited decreases. Stable combustion can be achieved.

[Brief explanation of the drawing]

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 invention, Fig. 3 is a horizontal cross-sectional view of the position near the header 42, and Fig. 4 is a sectional view of the stack valve 36, FIG. 5 is a diagram showing the combustion control state, and FIG.
The figure is a diagram relating to CO concentration in exhaust gas, FIG. 7 is a diagram for explaining still another embodiment of the present invention, and FIGS. 8 and 9 are diagrams for explaining other embodiments of the present invention. It is. 1... Combustion chamber, Mikawa coke, 36... Stack valve, 42... Control valve Representative Patent Attorney Kei Nishi Part 1.1 A Figure 4 Figure 5 t1 t2 t4 tt) t7 Figure 6 tl tpt3 Tojiri room 1 1-2 22 yen 1 Σ Silence room

Claims (1)

[Claims] Depositing a solid fuel on a grate of a combustion chamber, supplying primary air from below to above the grate into the deposited layer, and arranging a plurality of nozzles vertically on a peripheral wall of the combustion chamber, A solid fuel combustion method characterized in that the supply of secondary air from a nozzle above the vicinity of the top of the deposited layer is stopped, and the secondary air is supplied from a nozzle below the vicinity of the top.