JPH06257733A - Secondary air in combustion furnace supplying device - Google Patents

Abstract

PURPOSE:To enable stable and safety combustion by keeping flow velocities of secondary air ports approximately constant through a process of controlling the number of secondary air ports for supplying secondary air after detecting the pressure of a secondary air supply pipe. CONSTITUTION:Secondary air supplying ports 16, 18, 20 are provided in order to supply secondary air to a free board part 32 of a combustion furnace 30. The ports 16, 18, 20 respectively communicate with a secondary air supply pipe 22 through valves 10, 12, 14 and connected to a secondary blower 36. A pressure indicator 24 detects the pressure of secondary air. A control unit 26 controls the number of ports 16, 18, 20 by opening/closing the valves 10, 12, 14 on the basis of the detected value of the pressure indicator 24. When the quantity of heat of the combustion material to be supplied is decreased, or when the load is decreased, the pressure of the secondary air supply pipe 22 is detected by the pressure indicator 24, and one or two valves out of the valves 10, 12, 14 is closed by the control unit 26 so that the secondary air flow velocity in the furnace may be kept constant, thereby the incomplete combustion can be prevented.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention can be used for supplying secondary air to all combustion systems such as refuse incinerators, waste incinerators, coal combustion furnaces, oil combustion furnaces, etc. The present invention relates to a secondary air supply method that enables stable and safe combustion regardless of fluctuations and load fluctuations.

[0002]

2. Description of the Related Art Conventionally, in order to achieve complete combustion of combustion gas, as shown in FIG.
2 was being supplied with secondary air. Reference numerals 16 and 18 are secondary air supply ports. In the steady state, as shown in FIG. 5, stable and safe combustion was possible by supplying the secondary air. When the calorific value or load of the combustion product fluctuates, the air volume of the blower is adjusted to control the supply amount of secondary air. Further, in JP-A-3-170715, the pressure in the fluidized bed incinerator is measured, and the measurement signal is processed to detect the primary combustion state of the incineration object, and based on the primary combustion state. Then, a combustion control method is described in which the amount of secondary air for combustion is appropriately adjusted to generate secondary combustion of combustible gas to prevent incomplete combustion in the furnace.

[0003]

In the above prior art, when the heat value or load of the combustion product fluctuates, the number of secondary air ports to be used remains fixed and only the air volume of the blower is used to generate the secondary air. Since the supply amount was controlled, when the calorific value or the load of the combustion product was reduced, the flow rate of the secondary air was reduced together with the supply amount of the secondary air, as shown in FIG. Therefore, the penetrating force of the secondary air in the furnace becomes small, the agitation in the furnace becomes insufficient, and problems such as central blow through occur as shown in FIG. 6, and incomplete combustion is likely to occur. 33 is a central blow-through portion. As described above, in the conventional techniques shown in FIGS. 5 and 6, the number of secondary air ports used is fixed, and the secondary air is controlled only by the air volume of the blower. And the load could not be changed too much. The present invention has been made in view of the above points, and detects the pressure of the secondary air supply pipe to control the number of secondary air ports that supply the secondary air to keep the flow velocity of the secondary air ports substantially constant. As a result, the secondary air of the combustion furnace that maintains stable penetration of secondary air to prevent incomplete combustion and enables stable and safe combustion even when the calorific value fluctuations and load fluctuations of the combustion products are large The purpose is to provide a supply method.

[0004]

In order to achieve the above object, a method for supplying secondary air to a combustion furnace according to the present invention is a combustion method having a plurality of secondary air ports as shown in FIGS. In the secondary air supply method of a furnace, pressure fluctuations in the secondary air supply line due to fluctuations in the calorific value of combustion products and / or load fluctuations are detected to detect combustion status fluctuations, and secondary air is supplied based on this. It is characterized in that the number of secondary air ports is controlled and the secondary air is appropriately adjusted and supplied so that the secondary air port flow velocity is kept substantially constant.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. However, the shape of the constituent devices described in this embodiment, the relative arrangement thereof, and the like, unless otherwise specified, are not intended to limit the scope of the present invention only to them, but merely illustrative examples. Nothing more. Example 1 In this example, as shown in FIG. 1, secondary air is supplied in a fluidized bed combustion furnace. In FIG. 1, 30
Is a combustion furnace, which has a wind box 38, a dispersion plate 40, and a fluidized bed 42, and a forced air blower 34 for ejecting primary air is connected to the lower part. The freeboard portion 32 of the combustion furnace 30 is provided with secondary air supply ports 16, 18, and 20 for supplying secondary air. Port 1
The valves 6, 18, 20 communicate with the secondary air supply pipe 22 via the valves 10, 12, 14, respectively, and are connected to the secondary blower 36. Reference numeral 24 is a pressure indicator for detecting the pressure of the secondary air, and 26 is a port 16, 1 for opening and closing the valves 10, 12, 14 based on the detection value of the pressure indicator 24.
It is a controller for controlling the number of 8 and 20.

In FIG. 1, in the steady state, the three valves 10, 12, 14 at the upper, middle, and lower sides are open, and the three ports 16,
Secondary air is supplied from 18, 20. in this case,
As shown in FIG. 3, the penetrating force of the secondary air in the furnace is large and the agitation is sufficient, so that incomplete combustion does not occur. However, in FIG. 3, in order to simplify the description, the case where the ports are provided in two stages is shown. However, when the calorific value of the supplied combustion product becomes small or the load becomes small, it is necessary to reduce the supply amount of the secondary air. And one or two of the valves 10, 12, 14 are detected by the controller 26.
By closing these valves, incomplete combustion is prevented by controlling the secondary air velocity in the furnace so that it can be maintained. FIG. 4 shows that at low calorific value and / or low load,
It is shown that the number of ports is controlled to maintain the secondary air flow rate in the furnace and the stirring is sufficiently performed. Even in this case, the central blow-through portion does not occur. The same applies to the case where the forced blower 34 and the secondary blower 36 are shared.

Embodiment 2 In this embodiment, as shown in FIG. 2, secondary air is supplied in a stoker type combustion furnace. In FIG. 2, 3
Reference numeral 0 is a combustion furnace, which has a combustion material inlet 44 and a stoker 46. The freeboard portion 32 of the combustion furnace 30 has secondary air supply ports 16 and 18 for supplying secondary air.
Is provided. Ports 16 and 18 are each valve 1
It communicates with the secondary air supply pipe 22 via 0 and 12, and is connected to the secondary blower 36. Reference numeral 24 is a pressure indicator for detecting the pressure of the secondary air, and 26 is a pressure indicator 2
Based on the detection value of 4, open and close the valves 10 and 12 and port 1
A controller for controlling the number of 6 and 18. Other configurations and operations are similar to those of the first embodiment.

[0008]

Since the present invention is configured as described above, it has the following effects. (1) Since the flow velocity of the secondary air can be kept almost constant, even if there are large fluctuations in the calorific value of the combustion products and fluctuations in the load, stirring in the furnace is always sufficient and incomplete combustion in the combustion furnace is prevented. And stable and safe combustion is possible.

[Brief description of drawings]

FIG. 1 is an elevational view showing an example of a fluidized bed combustion furnace for carrying out a secondary air supply method for a combustion furnace according to the present invention.

FIG. 2 is an elevational explanatory view showing an example of a stoker type combustion furnace for carrying out the secondary air supply method for a combustion furnace of the present invention.

FIG. 3 is an elevational explanatory view showing a steady state when the secondary air supply method for a combustion furnace of the present invention is implemented.

FIG. 4 is an elevational explanatory view showing a state of low calorific value and / or low load when the method for supplying secondary air to the combustion furnace of the present invention is carried out.

FIG. 5 is an elevational explanatory view showing a steady state when a conventional secondary air supply method for a combustion furnace is carried out.

FIG. 6 is an elevational explanatory view showing a state at a low calorific value and / or a low load when a conventional secondary air supply method for a combustion furnace is carried out.

[Explanation of symbols]

 10 valves 12 valves 14 valves 16 ports 18 ports 20 ports 22 secondary air supply pipe 24 pressure indicator 26 controller 30 combustion furnace 32 freeboard part 34 forced air blower 36 secondary air blower 38 wind box 40 dispersion plate 42 fluidized bed 44 combustion Entry slot 46 Stalker

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Tatsuyuki Shimokawa 2-5-25 Tenjinbashi, Kita-ku, Osaka City Kawasaki Heavy Industries, Ltd. Osaka Design Office (72) Yasuhiko Yoshii 2-chome Tenjinbashi, Kita-ku, Osaka No. 25 Kawasaki Heavy Industries Ltd. Osaka Design Office

Claims (1)

[Claims] 1. A secondary air supply method for a combustion furnace having a plurality of secondary air ports, wherein a combustion condition is detected by detecting a pressure fluctuation of a secondary air supply line due to a fluctuation of a calorific value of a combustion product and / or a load fluctuation. A feature is that it detects fluctuations and controls the number of secondary air ports to supply secondary air based on this, and appropriately adjusts and supplies the secondary air so that the flow velocity of the secondary air port is kept almost constant. For supplying secondary air to a combustion furnace.