JPH06147401A - High-efficiency quick start type boiler - Google Patents

Abstract

PURPOSE:To provide a boiler structure having a long life, capable of being quickly started at high efficiency and performing low-pollution combustion. CONSTITUTION:An upper body 2 into which a plurality of fire tubes 7 are inserted is provided on the upper part of a furnace 1, and a furnace side wall 3 and a furnace rear wall 4 are formed into a water screen, moreover a pair of non-heating downcomers 8 out of the downcomers for connecting lower headers 5d on the right and left furnace side walls to the upper body 2 are provided on the upper body rear part, while two pairs of those are provided on the upper body front part, respectively. Moreover, the upper body 2 is connected to the right and left furnace side wall upper headers 5u by a plurality of riser tubes 9, and an upper header 6u on the rear wall and a rear end plate of the upper body 2 are connected to each other by a riser tube wall 10 composed of a plurality of riser tubes with fins, moreover one part of a flue 11 positioned near the upper body is formed into an economizer 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler device which can be rapidly started with high efficiency and which is capable of low-pollution combustion.

[0002]

2. Description of the Related Art A conventional flue tube type boiler is shown in FIG.
As shown in (A), a furnace cylinder 1a connected to the front wall of the main body and a plurality of smoke pipes connecting the rear part of the furnace cylinder and the rear wall of the main body are provided in the main body 2a, and the combustion gas passes through the flue 4a. It is discharged to a chimney (not shown). This type of boiler is used as a small capacity boiler with an evaporation amount of about 5 to 10 T / H. However, due to the limitation of the diameter of the main body, it cannot be used for large capacity boilers and high pressure boilers, and the combustion chamber is small for its capacity, so pollution control is difficult. There are various types of water tube boilers that make up a furnace with a water tube wall.
Widely used for high pressure boilers. An example of the relatively small capacity is shown in FIG. The furnace side wall 3b normally connects the upper body 2b and the lower body 2b 'together with the evaporating pipe group, and the boiler efficiency can be made relatively high by combining an economizer and an air heater (not shown) separately installed. However, there is a problem that the metal temperature difference between the upper body, the lower body, and the evaporation tube at the time of pressurization is large, and rapid startup cannot be performed. However, in recent years, there are cases where the number of times of starting and stopping is large, which is suitable for this, and quick starting is possible, and the C in exhaust gas is highly efficient.
Boilers capable of low-pollution combustion with little O, NOx, and dust particles are being demanded. At the time of conventional start-up, the rate of increase in combustion load, that is, rapid start-up is limited by the relationship between the strength and life of the material of the boiler, especially the material of the upper shell, and the relationship between the required drum thickness and the steam pressure. Some require. This is because if there is a large temperature difference between the temperature of the boiler water in the upper shell and the outer surface of the upper shell, which is affected by combustion gas, internal stress is generated in the shell plate, and the temperature difference between the rising pipe and the upper shell is repeated. This will cause a crack on the trunk and lead to a serious accident. We are trying to extend the start-up time and make it safer than these restrictions. This is not limited to the upper case, and similar attention should be paid to each component of the boiler affected by the combustion gas. In order to enable a steam temperature rise of 300 ° C / h as a condition for rapid startup, the temperature difference between the boiler water in the upper shell and the surface of the shell plate should be within the limit value of the cyclic stress of the upper shell material. Then it is necessary to increase the combustion load. However, in a conventional boiler, even if steam is generated, there may be a difference of 150 ° C. between the boiler lower member and the steam temperature, and it may not be desirable to increase the rising rate of boiler water. On the other hand, in the past, the design was focused on the separation of steam and boiler water, and the dryness of saturated steam, and it has been found that rapid startup does not pay much attention. The inventor
Focusing on smoke tube type boilers that designers have not paid much attention to recently, it is possible to rapidly raise the temperature of boiler water by arranging the riser pipe and downcomer pipe, and at the same time construct a furnace with a water cooling wall We propose a structure of a boiler that secures a large combustion volume, burns enough to achieve low pollution, and has high efficiency and quick start.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to propose a structure of a boiler which can be rapidly started with high efficiency, can perform low-pollution combustion, and has a long life.

[0004]

SUMMARY OF THE INVENTION The present invention is a boiler apparatus in which an upper shell in which a plurality of smoke tubes are inserted is provided in the upper part of a furnace, the furnace side wall and the furnace rear wall are formed as water cooling walls, and the left and right furnace side walls are formed. One set of two unheated downcomer pipes for connecting the lower head and the upper case are provided at the rear of the upper case and two at the front of the upper case. The upper side wall of the side wall is connected to the upper head by a plurality of rising pipes, and the upper head of the rear wall and the rear end plate of the upper body are connected by a rising pipe wall composed of a plurality of rising pipes with fins. This is a high-efficiency rapid start-up type boiler device in which a part of the flue located in the vicinity is formed in the economizer section.

[0005]

Embodiment 1 FIG. 1A is a perspective view of a boiler showing a first embodiment of the present invention, and FIG. 1B is a perspective view of an economizer section. The furnace 1 is composed of left and right furnace side walls 3 and a furnace rear wall 4. The side wall of the furnace and the rear wall of the furnace are formed as water cooling walls, the side wall of the furnace is connected to the upper header 5u and the lower header 5d, and the rear wall of the furnace is upper header 6u and the lower header 6d.
Connected to. The upper heads 5u and 6u and the lower heads 5d and 6d are connected in a katakana "U" shape as shown in the drawing. Upper body 2 is furnace 1
Is located above and has a plurality of smoke tubes inserted therein, and the combustion gas flows in the smoke tubes to exchange heat with the boiler water. In the rear of the upper body, which is the rear wall side of the furnace of the upper body 2, unheated downcomer pipes 8 surrounded by refractory materials and the like are provided in pairs, one on each of the left and right sides of the upper body. 2 are connected. Two sets of unheated downcomers, which are similarly surrounded by a refractory material, are provided in the front part of the upper body on the front wall side where the burner is connected, connecting the upper body and the lower header 5d. The number of unheated downcomer pipes 8 on the front side of the upper body is double that of the rear part because the amount of heat received from the combustion gas on the furnace wall surface in the rear part is larger than that in the front part, and the circulation of the boiler water is smoothly lowered. It was done to The diameter of the front unheated downcomer may be larger than the diameter of the rear unheated downcomer. The upper head 5u and the upper body 2 are connected by a plurality of rising pipes 9. As a result, the steam-water mixed fluid generated in the furnace side wall 3 flows into the upper shell almost immediately after the burner ignition, and the temperature of the boiler water in the upper shell is rapidly increased. Further, the rear end plate of the upper shell and the upper header 6u of the rear wall of the furnace are connected by a rising pipe wall 10 composed of a rising pipe with a plurality of fins, and similarly, a steam-water mixed fluid is supplied to the upper shell 2 at the same time when the boiler is started. Therefore, the temperature of the boiler water is further increased by absorbing heat from the combustion gas of the smoke tube group 7 in the upper body. Combustion gas 15
Transfers heat with good efficiency in heat exchange with boiler water in the smoke tube group 7 in the upper body. The combustion gas that has exited the smoke tube group 7 enters the flue 11, heats the feed water in the economizer section 12 that forms a part of the flue, and flows to the chimney (not shown). The heat transfer tube of this economizer is a finned tube, but a smooth tube may be used if necessary.
The economizer 12 is shown as a perspective view in FIGS. 1 (A) and 1 (B), and has a structure having a reversing flow path of the combustion gas as shown by an arrow to facilitate the parallel arrangement with the upper case. Block assembly may be used to facilitate on-site construction.

[Embodiment 2] A plurality of screen tubes 13 are provided at the inlet of the combustion gas passage between the rear portion of the upper body and the finned riser wall 10 for adjusting the temperature of the combustion gas flowing into the smoke tube group 7 in the upper body. It can also be provided.

[0006]

The following effects can be obtained by implementing the present invention. It is a boiler that can make the furnace volume necessary and sufficient for various fuels, can perform low-pollution combustion with suitable combustion, and can be easily modified for future fuel conversion. The downcomer consists of two unheated downcomers surrounded by heat insulating material, one set for the one with a large amount of furnace heat transfer in the rear of the upper body, and one set for the front of the upper body with a relatively small amount of heat transfer. Double the number of pairs to improve the circulation of boiler water in the upper body. The upper shell and the upper header of the side wall of the furnace are connected by a plurality of rising pipes, and the steam-water mixed fluid flows into the upper shell almost at the same time as the boiler is started, and the temperature of the boiler water in the upper shell is increased quickly. Similarly, the steam-water mixed fluid from the rear wall of the furnace passes through the rising wall 10 on the rear wall side of the furnace and flows into the upper shell almost at the same time as the boiler is started, and the temperature of the boiler water in the upper shell rises quickly. To Since the smoke tube group is arranged in the upper body, the temperature of the boiler water in the upper body can be further raised. Due to the above items, the temperature difference between the boiler water side and the combustion gas side due to the thickness of the body plate of the upper body can be reduced, and a rapid start-up of 300 ° C / h can be achieved. For this reason, it is the optimum type of boiler to be combined in the waste heat boiler as a device that requires rapid start-up under the condition from the waste gas generation side. Due to the above-mentioned items, the thickness of the upper shell can be reduced, and the temperature difference between the boiler water side and the combustion gas side is small, enabling rapid startup. Further, the plate thickness can be made thin and the manufacturing cost can be remarkably reduced. The block-assembled economizer section 12 is arranged near the upper body, and the above-described steps 1 to 3 enable high-efficiency quick start operation. The upper body and the furnace tube wall can be manufactured separately, and even if the capacity increases, the upper body with a large external dimension can be easily annealed even in an existing annealing furnace, and the transportation limit can be dealt with. Installation time can be shortened. The maximum evaporation amount is 5T / H, the maximum working pressure is 10Kg / cm
^2, a temperature check test of each component was performed with a test boiler prototyped with a steam pressure of 8.5 Kg / cm ² and a feed water temperature of 20 ° C. The temperature difference between the connection with 5u and the connection between the riser and the upper shell was 14 ° C, half the planned value, and all metal temperatures were within ± 30 ° C of the saturated steam temperature. Even with a large amount of evaporation, the difference between the temperature of the saturated steam inside the upper shell and the temperature of the saturated steam inside the upper shell is about half that of conventional package water tube type boilers.
It was at 5 ° C. The boiler efficiency was 92% or more.

[Brief description of drawings]

FIG. 1A is a perspective view of a boiler device according to an embodiment of the present invention. (B) is a perspective view of the economizer attached to (A).

FIG. 2A is a vertical cross-sectional view of an example of a conventional flue tube boiler. (B) is sectional drawing of an example of the conventional water tube boiler.

[Explanation of symbols]

 1 Furnace 2 Upper body 3 Furnace side wall 4 Furnace rear wall 5d Lower side wall of furnace side wall 5u Upper head of furnace side wall 6d Lower head wall of furnace rear wall 6u Upper head of rear wall of furnace 7 Smoke tube group 8 Downcomer pipe 9 Upcomer pipe 10 Rise pipe Wall 11 Flue 12 Economizer part 13 Screen tube 14 Burner mounting port 15 Combustion gas

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eitaro Kataoka 1-2-10 Isogo Isogo, Isogo-ku, Yokohama, Kanagawa Bab Hitachi Engineering Services Co., Ltd.

Claims (2)

[Claims] Claim: What is claimed is: 1. In a boiler apparatus having an upper shell with a plurality of smoke tubes inserted in the upper part of the furnace, the furnace side wall and the furnace rear wall are formed as water cooling walls, and the lower headers of the left and right furnace side walls and the upper shell are One set of two sets of unheated downcomers for connecting the two is provided at the rear of the upper body, and two sets are provided at the front of the upper body, and the upper body and the left and right furnace side wall upper headers are respectively provided in plurality. Part of the flue located adjacent to the upper shell, with the upper head of the rear wall and the rear end plate of the upper shell connected by the rising wall of a plurality of finned tubes. A high-efficiency rapid start-up type boiler device characterized by being formed in the economizer section. 2. A high-efficiency quick-start type boiler apparatus according to claim 1, wherein a plurality of screen tubes are provided at an inlet of a combustion gas passage between a rear portion of the upper body and the fin-equipped rising pipe wall. .