JP2551779Y2 - Furnace smoke tube boiler - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention has been devised to provide a function suitable for large-scale heat source equipment such as district heating and cooling. Specifically, the present invention has a wide combustion control range and can follow a sudden load change. The present invention relates to a furnace tube type boiler having a function and high thermal efficiency.

[0002]

2. Description of the Related Art A boiler used as a heat source for district heating / cooling has extremely large load fluctuations depending on the time of day and night and seasonal load fluctuations, and the boiler is required to have a wide combustion control range. However, the combustion control range of the conventional furnace tube boiler has a minimum load control limit of about 1/8 to 1/10 when the maximum load is set to 1 (hereinafter, this control range is referred to as a turndown ratio). .

When the load of the boiler falls below the control limit value, the burner repeats the intermittent operation of stop-restart-stop in response to a start / stop signal of a pressure switch provided on the boiler body, so-called ON-OFF control. Driving. When the burner is stopped and restarted, post-purge and pre-purge are always performed with cold air for discharging unburned gas and the like remaining in the gas passage of the boiler. In particular, the amount of prepurge is required to be at least four times the total volume of the boiler combustion chamber volume, smoke tube, smoke chamber, flue, and other gas passages. It has been known that heat loss is caused and heat efficiency of the boiler equipment is significantly reduced.

[0004]

In order to solve the above problems, the present inventor has proposed a furnace tube type which has a wide range of boiler combustion control, high combustion efficiency, and stable operation. The present invention was completed by repeatedly devising the purpose of providing a boiler.

[0005]

Means for Solving the Problems According to the present invention which has achieved the above object, a plurality of furnace tubes are arranged in a boiler body,
The gist of the invention is that a partition is provided in the smoke chamber, and the combustion chamber of the furnace tube and the group of smoke tubes are divided for each furnace tube by the partition.

[0006]

FIG. 1 is a partially cutaway side view showing a typical embodiment of the present invention, and FIG. 2 is a partially cutaway side view seen from the right in FIG. Inside the boiler body 2, there are two furnace tubes 3A, 3B and a large number of smoke tube groups 8 above them in the storage water.
A and 8B are arranged side by side, and a rear smoke chamber 10 having a partition 9 for partitioning the furnace tube 3A and the smoke tube group 8A, and the furnace tube 3B and the smoke tube group 8B is disposed behind the boiler. The partition 9 completely divides the smoke chamber 10 into right and left, and the furnace tube 3A communicates only with the smoke tube group 8A, and the furnace tube 3B communicates only with the smoke tube group 8B.

[0007] Each furnace tube 3A, 3 in front of the boiler.
At the front end of B, fuel supply pipes 4A and 4B and burner air supply pipes 5A and 5B of the burner 4 are provided.
At the front end openings of A and 8B, a front smoke chamber 12 divided by a partition 11 is formed like the rear smoke chamber.

[0008]

According to the present invention, which has achieved the above object, the present invention is applied to a case where a burner is mounted at the end of a furnace tube through a smoke chamber.
Combustion gas circulates through several flue pipes and heat medium inside the boiler body
In a flue-tube type boiler for heating
A plurality of furnace tubes are provided, and a partition is provided in the smoke chamber.
The combustion chamber of the furnace tube and the smoke tube group
Each furnace tube is configured so that it can operate independently.
And the gist. In addition, the plurality of furnace tubes
Use a caliber that can support burners with different firing capabilities.
It can be installed in one boiler shell.

In such a flue tube boiler 1, the combustion gas generated by burning in the burners 4, 4 of the flue tubes 3A, 3B passes through the rear smoke chamber 10 fractionated from the flue tubes 3A, 3B. After passing through the smoke tubes 8A and 8B, it is guided to the front smoke chamber 12, and is discharged from the exhaust port 14 through the waste heat recovery device 13 provided at the upper part of the front smoke chamber 12.

The water stored in the boiler body 2 is heated by the furnace tubes 3A and 3B and the smoke tubes 8A and 8B to generate steam and supply it to the load side.

The burners provided in the two furnace tubes can individually increase or decrease the combustion amount according to the amount of steam used (load). When the load becomes extremely light, either one of the burners can be used. Burner stops first, and the operation is continued only by the other burner. In experiments using two identical capacity burners and furnace tubes, the turndown ratio was increased to 1/20. In addition, in this boiler, the amount of air for post-purging or pre-purging at the time of stopping or restarting combustion requires only a smaller amount of air than in the past because the volume of the furnace tube and the like has been reduced by half. Could be enhanced.

The number of furnace tubes provided in one boiler body is not limited to two as shown in the figure, but may be any number, such as 3, 4,. Further, not only are the furnace tubes provided with the same capacity but also furnace tubes having different capacities may be combined. For example, 20T /
In the h boiler, the turndown ratio of the combustion device is 1: 1 /
When 10 furnaces are used, the minimum load factor when two 10 T / h furnace tubes are arranged side by side is 5%, whereas the minimum load ratio is 15 T / h.
The minimum load factor when the h furnace tube and the 5T / h furnace tube are combined can be 2.5%.

FIG. 3 is a boiler equipment efficiency curve (shown by a solid line) of an embodiment of the present invention in which two furnace tubes having the same capacity are disposed in the same boiler body. The two-dot chain line indicates the equipment efficiency curve of a single furnace boiler having the same capacity, and the broken line indicates the boiler having a half capacity.
It is a facility efficiency curve at the time of base installation, These are comparative examples. In the case of a two-furnace boiler, the boiler load factor is 1
At 0%, combustion is switched from two furnace cylinders to one furnace cylinder.

As is apparent from this graph, when the load is lower at an equipment load factor of 10% or less, the OOF in the single furnace type is smaller.
The intermittent control of N-OFF is increased, and the loss heat removed by the forced cooling by the purge air is large each time, and the efficiency is remarkably reduced (the purge air amount is about 2 in the two-tube boiler).
Times).

Also, two boilers of 1/2 capacity are arranged side by side to
When the reactor is operated at the minimum load (5% load as equipment), the waste loss ratio is the same as when switching from two cylinders to one cylinder combustion in a two cylinder boiler, but the surface area of the boiler is one. Since the capacity of two 1/2 capacity boilers is wider, the equipment efficiency is reduced by the heat radiation loss ratio.

On the other hand, as in the embodiment of the present invention, in the case of a flue-tube type boiler in which burners are dispersed in a plurality of units, stable operation is maintained while maintaining high-efficiency combustion even with a large load fluctuation. Can be done. In addition, since combustion under unreasonable conditions is eliminated, combustion with an appropriate amount of oxygen can be performed, which has an additional effect that the generation of NOx, which increases as the burner combustion amount increases, can be suppressed as small as possible.

Further, in the boiler according to the present invention,
Since the combustion capacity of each furnace tube is lower than that of a single furnace tube, the diameter of the furnace tube can be reduced, so that it is not necessary to make the wall thickness of the furnace tube excessively thick in terms of pressure resistance, and the manufacturing cost of the device is reduced. Can be suppressed.

[0018]

Since the present invention is configured as described above, the turn-down ratio is as wide as 1- (1/20 to 1/40), and the operation can be performed with a high heat-burning efficiency. Therefore, even when used as a heat source for district cooling and heating with large load fluctuations, safe and economical operation can be performed.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view showing a typical embodiment of the present invention.

FIG. 2 is a partially cutaway side view as seen from the right in FIG. 1;

FIG. 3 is a graph showing the boiler thermal efficiency of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace smoke tube boiler 2 Boiler trunk 3A, 3B Furnace tube 4 Burner 4A, 4B Fuel supply tube 5A, 5B Combustion air supply tube 6A, 6B Push fan 7A, 7B Exhaust gas recirculation device 8A, 8B Smoke tube 9 Partition 10 Rear smoke chamber 11 Partition wall 12 Front smoke room 13 Waste heat recovery device 14 Exhaust port

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Minoru Minami 1-3-29 Shimae-cho, Toyonaka City, Osaka Prefecture Inside Takao Iron Works Co., Ltd. (72) Keiichi Otsuka 1-chome Shimae-cho, Toyonaka-shi, Osaka No. 29 in Takao Iron Works, Ltd. (56) References JP-A-52-106001 (JP, A)

Claims (2)

(57) [Scope of request for utility model registration] 1. A flue gas tube type boiler in which a combustion gas flows from a furnace tube having a burner attached to an end through a smoke chamber into a large number of smoke tubes and heats a heat medium in the boiler body. In addition to disposing a plurality of furnace tubes, a partition is provided in the smoke chamber, and the combustion chamber of the furnace tube and the smoke tube group are partitioned by the partition so that each furnace tube can be operated independently. Configured
A flue-tube type boiler, characterized in that: 2. A flue-tube type boiler according to claim 1, wherein the plurality of furnace tubes have a diameter capable of coping with burners having different combustion capacities, and are arranged in the same boiler body.