JPH11270812A - Duct burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and properly control a combustion quantity by mounting a fuel flow control valve to a fuel main pipe, and mounting a second fuel flow control valve which differs in capacity from the fuel flow control valve to a fuel bypass pipe which bypasses the fuel flow control valve. SOLUTION: Four duct burners 2 are inserted in an exhaust gas duct 1 and two center-side duct burners 2 are grouped into one group as a fuel burner pipe 6. The fuel burner pipe 6 which forms the group is communicated with a common header pipe 5 and is further communicated with a fuel main pipe 4 which constitutes a fuel source by way of a main shut-off valve 7 and a flow control valve 8 and the like. Furthermore, on each fuel burner pipe 6, an independent fuel sub shut-off valve 17 which shuts off fuel on every burner group is mounted. Still furthermore, with respect to the flow control valve 8 mounted on the fuel main pipe 4, a fuel bypass pipe 10 which bypasses this flow control valve 8 is provided, and a second fuel control valve 18 which has a smaller capacity than that of the flow control valve 8 and therefore is capable of performing a fine control is mounted on this fuel bypass pipe 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duct burner for burning fuel such as heavy oil or gas in a duct by using oxygen remaining in exhaust gas.

[0002]

2. Description of the Related Art An example of a conventional duct burner will be described with reference to FIG. Reference numeral 1 denotes an exhaust gas duct that forms a flow path for exhaust gas discharged from an internal combustion engine, a gas turbine, or the like (not shown). A plurality of fuel nozzles 3 are provided in a fuel burner pipe 6 extending across the flow path in the longitudinal direction. A plurality of duct burner bodies 2 are arranged.

[0003] Each fuel burner pipe 6 communicates with a common fuel header pipe 5 at each end thereof.
Is connected to the fuel main pipe 4 on the upstream side.

A main fuel shutoff valve 7 and a fuel flow control valve 8 are provided in the main fuel pipe 4, and are opened / closed in response to a command to detect a flow rate by a fuel flow meter 9 provided upstream thereof. It has become so.

A required number of duct burners, each composed of the exhaust gas duct 1 and the duct burner main body 2, are installed in accordance with the amount of fuel used, and all of them are used.

[0006]

Generally, in this type of burner, the maximum capacity (maximum combustion amount) is determined by the maximum fuel pressure, and the minimum combustion amount is determined by the minimum allowable pressure.

For this reason, in the conventional systems including the above-mentioned conventional example, the range in which the amount of combustion can be controlled is limited because there is no special control means, and the adjustment of the temperature after combustion is hindered.

[0008] Especially when gas fuel is used,
When the fuel composition or the calorific value changes from the design value, the range in which the amount of combustion can be controlled is greatly restricted.

Further, in the above-described conventional apparatus, even if the amount of combustion decreases, the amount of combustion must be maintained at or above the permissible lower limit of each burner, and there is no special control means. In particular, when the calorific value of the fuel increases, the heat input of the fuel cannot be reduced.

Therefore, when the temperature of the exhaust gas after combustion exceeds a required value and an exhaust gas boiler is installed downstream,
This results in a disadvantageous result that a loss occurs such that the amount of generated steam exceeds the required value and is released to the atmosphere.

An object of the present invention is to provide a duct burner which can solve such a problem in the conventional one and can control the amount of combustion accurately and suitably.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a plurality of duct burner bodies arranged in a flow path of exhaust gas are commonly used at positions symmetrical with respect to the center of the flow path. A plurality of groups are formed by communicating with the fuel burner pipes, each fuel burner pipe is communicated with a common fuel main pipe, and an independent fuel cutoff valve is provided for each of the duct burner main body, each fuel burner pipe, and the fuel main pipe. Is arranged,
It is an object of the present invention to provide a duct burner in which a fuel flow control valve is provided in the fuel main pipe, and a second fuel flow control valve having a capacity different from that of the fuel flow control valve in the fuel main pipe is provided in a fuel bypass pipe that bypasses the fuel flow control valve.

That is, according to the present invention, the duct burner main bodies are divided into groups so as to be symmetrically arranged with respect to the center of the flow path. Since an independent fuel cutoff valve is provided, by selectively opening and closing each fuel cutoff valve according to a change in the amount of combustion, suitable and precise control can be performed while taking into consideration the distribution balance in the duct. .

In addition to the control based on the selection of the plurality of fuel cutoff valves, the fuel flow control valve of the fuel main pipe and the second fuel having different capacities provided in the fuel bypass pipe bypassing the fuel flow control valve are provided. The precision of the control is further improved by fine adjustment by the flow rate control valve.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. Note that the same parts as those of the above-described conventional one are denoted by the same reference numerals in the drawings, and redundant description will be omitted as much as possible, and the points unique to the present embodiment will be mainly described.

In the exhaust gas duct 1, four duct burner bodies 2 are inserted in the flow path thereof.
The two lines closer to the center with respect to a horizontal plane passing through the center of the center are grouped together as one group in the fuel burner pipe 6, and similarly the two lines closer to the outside are grouped as another group in another fuel burner line 6.

Each of the fuel burner pipes 6 forming each group communicates with a common fuel header pipe 5, and is a fuel which is a source flow provided with a fuel main shutoff valve 7, a fuel flow control valve 8 and a fuel flow meter 9. It is connected to the main pipe 4.

Each of the four duct burner bodies 2 is provided with an independent fuel burner shutoff valve 27 for shutting off fuel for each burner, and each fuel burner pipe 6 forming each group is also provided with a separate fuel burner shutoff valve 27. An independent fuel sub-cutoff valve 17 for shutting off fuel is provided for each burner group, and the fuel main pipe 4 for shutting off all fuel is provided.
Each of these fuel shut-off valves, including the fuel main shut-off valve 7 provided in the above, is individually ON-OFF controlled.

For the fuel flow control valve 8 provided in the fuel main pipe 4, a fuel bypass pipe 10 for bypassing the fuel flow control valve 8 is provided.
A second fuel flow control valve 18 having a smaller capacity than that of the fuel flow control valve 8 and capable of small adjustment is provided therein.

In this embodiment configured as described above, the fuel is supplied to the duct burner base 2 via the fuel main pipe 4, the fuel header pipe 5, and the fuel burner pipe 6, and is ejected from the fuel nozzle 3 to be discharged from the exhaust gas duct. The fuel gas is mixed with oxygen in the exhaust gas supplied and burned.

The flow rate of the fuel gas is adjusted by the fuel flow control valve 8 and the second fuel flow control valve 18 having different capacities, which are installed in the fuel main pipe 4, so that the exhaust gas after combustion has a required temperature. It is measured by the fuel flow meter 9.

In terms of normal valve operation, the main fuel shutoff valve 7 is fully closed when the burner is stopped and fully opened when the burner is operating, while the fuel sub shutoff valve 17 or the fuel burner shutoff valve 2 is closed.
7 controls according to the fuel combustion amount.

In addition, since all burners are used at the time of maximum combustion, both the fuel sub-cutoff valve 17 and the fuel burner cutoff valve 27 are controlled to be fully opened.

In the present embodiment, when the amount of combustion is less than the permissible lower limit of each burner when all the burners are used, the fuel burner shutoff valves 27 provided in each of the four duct burner bodies 2 are selectively used. , And the burner quantity can be reduced to secure the combustion amount at or above the permissible lower limit.

However, in the case where the burner is selected at random, if there is a bias of the flame when the burner is shut off, the problem of local heating of the downstream duct or the like spreads. Therefore, in this embodiment, the burners are grouped. By shutting off fuel in groups by the fuel sub shutoff valve 17, control and adjustment can be performed so that there is no deviation in flame.

As described above, according to the present embodiment, a wide range of load adjustment (combustion amount) can be achieved, the heat loss can be greatly reduced, and the composition of the gas fuel, the calorific value and the like can be changed. The follow-up makes it possible to use a variety of fuels. In addition, by leveling the exhaust gas temperature after combustion to prevent local heating, it is effective in maintaining the life of the downstream part of the burner such as a gas duct.

Although the present invention has been described with reference to the illustrated embodiment, the present invention is not limited to such an embodiment.
It goes without saying that various changes may be made to the specific structure within the scope of the present invention.

For example, the applicable range of the present system is not limited to exhaust gas, but can include normal air combustion.
In addition, the gas burner duct burner is taken as an example and the burner quantity is 4
Although the case of the unit has been described, the fuel type and the number of burners are not limited to this.

[0029]

As described above, according to the present invention, a plurality of duct burner bodies arranged in the exhaust gas flow path are connected to a common fuel burner pipe at positions symmetrical with respect to the center of the flow path to form a plurality of groups. Forming, connecting each fuel burner pipe to a common fuel main pipe, disposing an independent fuel cutoff valve in each of the duct burner main body, each fuel burner pipe and the fuel main pipe, and providing a fuel flow rate in the fuel main pipe. Since a control valve is provided and a second fuel flow control valve having a different capacity from the fuel flow control valve of the fuel main pipe is provided in a fuel bypass pipe for bypassing the control valve, a fuel burner is provided. By independently controlling the opening and closing of each fuel cutoff valve according to the change in the amount of combustion by the fuel cutoff valve provided independently for each body and for each group, Fine and fine adjustment by the control valve and the second fuel flow control valve with different capacity provided in the fuel bypass pipe that bypasses the fuel flow control valve enables suitable and precise control considering the distribution balance in the duct The system was able to be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an outline of a duct burner according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing an outline of a conventional duct burner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust gas duct 2 Duct burner main body 3 Fuel nozzle 4 Fuel main pipe 5 Fuel header pipe 6 Fuel burner pipe 7 Fuel main shutoff valve 8 Fuel flow control valve 9 Fuel flow meter 10 Fuel bypass pipe 17 Fuel sub shutoff valve 18 Second fuel flow control Valve 27 Fuel burner shutoff valve

Claims (1)

[Claims] A plurality of groups are formed by connecting a plurality of duct burner bodies arranged in an exhaust gas flow path to a common fuel burner pipe at positions symmetrical with respect to the center of the flow path to form a plurality of groups. Are connected to a common fuel main pipe, and an independent fuel cutoff valve is provided for each of the duct burner bodies, each fuel burner pipe, and the fuel main pipe, and a fuel flow control valve is provided for the fuel main pipe. A duct burner, wherein a second fuel flow control valve having a capacity different from that of the fuel flow control valve of the fuel main pipe is provided in a fuel bypass pipe to be bypassed.