JPH06201101A - Water tube boiler - Google Patents

Abstract

PURPOSE:To provide a water tube boiler, capable of preventing cracking due to the high-temperature oxidation or thermal stress of a filet having an angular sectional configuration and effecting ventilation with a small ventilating power. CONSTITUTION:In a water tube boiler, having a structure wherein an upper tube plate or an upper cylinder 1 and a lower tube plate or a lower cylinder 2 are communicated through a multitude of inside water tubes 3 and outside water tubes 4, water tubes 14, having no filet 13 of angular sectional configuration, are arranged instead of inside water tubes 3 and outside water tubes 4 arranged along the combustion gas passage 5 positioned from an opening section 10 provided on the water tube wall of the inside water tubes 3 toward the downstream of the flow of combustion gas by a specified length. According to this method, the cracking due to the high-temperature oxidation or thermal stress of the filet can be prevented and a small boiler drum body, requiring a small ventilating power, can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water tube boiler having a structure in which an upper head or an upper body and a lower head or a lower body are connected by a large number of inner water tubes and outer water tubes.

[0002]

2. Description of the Related Art FIG. 4 is a plan sectional view showing the structure of a conventional water tube boiler of this type. As shown in the figure, in the conventional water pipe boiler, the upper head or the upper body (not shown) and the lower head or the lower body (not shown) are connected by a large number of inner water pipes 3 and outer water pipes 4. A combustion gas passage 5 is formed between an annular water pipe wall formed of a row of inner water pipes 3 and an annular water pipe wall formed of a row of outer water pipes 4, and an opening 1 is formed over the entire length of the inner water pipe wall.
0 is provided to connect the combustion chamber 8 formed in the inner water pipe wall with the combustion gas passage 5, and the opening 11 extending over the entire length of the outer water pipe wall is provided so that the combustion gas passage 5 and the flue 12 are provided.
And the inner water pipe 3 facing the combustion gas passage 5
And the outer water pipe 4 is provided with fins 13 having an angle-shaped cross section.

[0003]

In the water tube boiler having the above-mentioned conventional structure, the combustion gas flowing out from the combustion chamber 8 through the opening 10 causes the fins of the inner and outer water tubes 3 and 4 and the cross-section angle-shaped fins. Flows through the combustion gas passage 5 formed by. That is, by flowing through a zigzag-shaped passage that continuously repeats direction change to a direction close to a right angle, the collision repeatedly occurs on the surface of the inner water pipe 3 and the outer water pipe 4 or one side of the fin 13 having an angled cross section, and the water pipe and the fin are forced. Heat is exchanged by convective heat transfer, and the gas temperature is lowered toward the flue 12.

However, when flowing through the zigzag-shaped passage as described above, particularly in the inner water pipe 3 and the outer water pipe 4 with the angled fins 13 arranged near the opening 10 (combustion chamber outlet), There were the following problems. (1) The combustion gas has a high temperature in the vicinity of the opening 10, and the fins having an angled cross section provided in the water pipe in this region come into contact with the high temperature gas, which causes a problem of damage due to high temperature oxidation.

(2) Also, the fin 13 having an angled cross section.
There was a risk that the tip portion of the water temperature became higher than the surface of the water pipe, and the fin or the water pipe was cracked due to thermal stress.

(3) Further, since the fins having an angle-shaped cross section are attached to the majority of the two water pipes 3 and 4 on the inner and outer sides forming the combustion gas passage 5, the combustion gas passes through the combustion gas passage. The flow resistance may be increased due to the direction change because the direction change is continuously repeated and flows over the entire length. In particular, since the combustion gas has a high temperature in the vicinity of the outlet (opening 10) of the combustion chamber 8, there is a problem in that the volume flow rate of the combustion gas increases and the ventilation resistance increases, so that it is necessary to increase the ventilation power of the blower. .

The present invention has been made in view of the above-mentioned problems, and eliminates the above-mentioned problems, prevents cracks caused by high-temperature oxidation of fins and thermal stress, and provides a water tube boiler that requires a small blowing power. The purpose is to

[0008]

In order to solve the above problems, the present invention is directed to a water tube boiler, in which a predetermined length is provided from an opening 10 provided in a water tube wall of an inner water tube 3 toward a downstream side of a flow of combustion gas. The inner water pipe 3 and the outer water pipe 4 are formed as finless water pipes 14 having an angled cross-section over the combustion gas passage 5.

[0009]

With the above-described structure, the combustion gas burned in the combustion chamber 8 branches at the opening 10 to reach the combustion gas passage 5, and then the water in the inner water pipe 3 is mainly heated by convective heat transfer. The combustion gas that has exchanged heat with the pipe wall, the water pipe wall of the outer water pipe 4, and the fin 13 having an angled cross-section merges at the opening 11 provided in the water pipe wall of the outer water pipe 4 toward the flue 12. In this case, since the inner water pipe 3 and the outer water pipe 4 in the vicinity of the opening 10 are provided with the water pipe 14 having an angled cross-section and having no fins 13, the fins are oxidized at high temperature even if the combustion gas temperature is high. Never. In addition, the temperature of the fin rises due to heat exchange with the combustion gas, thermal stress due to the temperature difference is not generated in the fin, the water pipe and the fin attachment portion, and the fin and the water pipe are not cracked.

Further, when the combustion gas is in a high temperature state, the volume flow rate of the combustion gas becomes large, and in the high temperature region where the volume flow rate is large, the inner water pipe 3 and the fin 13 having an angled cross section, as in the conventional case, continuously form a nearly right angle. Ventilation resistance can be reduced because the direction change is not repeated in the direction.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are views showing the structure of a water tube boiler according to an embodiment of the present invention, FIG. 1 is a longitudinal sectional view, and FIG. 2 is a transverse sectional view. The upper header or the upper barrel 1 and the lower header or the lower barrel 2 are both formed in an annular shape, and the upper header or the upper barrel 1 and the lower header or the lower barrel 2 have a large number of inner water pipes 3.
Are connected by a large number of outer water pipes 4 as well.

A large number of inner water pipes 3 are arranged in close contact with each other and are formed as annular water pipe walls. Further, the outer water pipes 4 are connected to each other by fins 15 and arranged to form an annular water pipe wall. A combustion gas passage 5 is formed between the water pipe wall of the inner water pipe 3 and the water pipe wall of the outer water pipe 4, and a casing 6 is provided outside the water pipe wall of the outer water pipe 4 to form a gas tight structure. Insulation 7 outside
Is provided.

A combustion chamber 8 is formed in an annular water pipe wall of the inner water pipe 3 formed in an annular shape. Further, a combustion device 9 is provided inside the upper head 1 or the upper body 1.
An opening 10 is provided at a predetermined position on the water pipe wall of the inner water pipe 3 over the entire length of the water pipe, and the combustion chamber 8 and the combustion gas passage 5 are communicated with each other. Further, an opening 11 is provided at a predetermined position on the water pipe wall of the outer water pipe 4 over the entire length of the water pipe, and the combustion gas passage 5 and the flue 12 are communicated with each other.

The inner water pipe 3 and the outer water pipe 4 are arranged so as to be offset from each other by about a half pitch in the circumferential direction, and the side faces of the inner water pipe 3 and the outer water pipe 4 facing the combustion gas passage 5 have an angular cross-section over the entire length of the water pipe. Although the fin 13 is provided,
Several inner water pipes 3 and outer water pipes 4 facing a certain length in the downstream direction from the opening 10 in the combustion gas passage 5 (3 in FIG.
This is a water pipe 14 with an angled cross section and no fins 13.

Next, the operation of the water tube boiler having the above structure will be described. Combustion gas burned in the combustion chamber 8 has an opening 10
After diverging to reach the combustion gas passage 5, the heat is exchanged mainly between the water pipe wall of the inner water pipe 3, the water pipe wall of the outer water pipe 4 and the angled fin 13 by convective heat transfer, At the portion of the opening 11 provided in the water pipe wall of the water pipe 4, the water pipe 4 merges toward the flue 12. In this case, since the inner water pipe and the outer water pipe are angle-free water pipes 14 near the opening 10 of the combustion chamber 8, that is, near the outlet of the combustion chamber 8, even if the combustion gas temperature is high, As in the conventional example shown in 4,
The angled fin 13 is not oxidized at high temperature.
Further, the temperature of the fin 13 rises due to the heat exchange with the combustion gas, and thermal stress due to the temperature difference is generated in the fin, the water pipe and the fin attachment portion, and the fin and the water pipe are not cracked.

Further, when the combustion gas is in a high temperature state, the volume flow rate of the combustion gas increases, and in a region where the volume flow rate is large, that is, in the vicinity of the opening 10, by the inner water pipe 3 and the fin 13 having an angled cross section as in the conventional case. Ventilation resistance can be reduced because the direction change near a right angle is not repeated continuously.

FIG. 3 is a cross-sectional view showing the structure of a water tube boiler according to another embodiment of the present invention. The difference between the water pipe boiler of FIG. 3 and the water pipe boilers of FIGS. 1 and 2 is that in FIG. 1 and FIG. 2, the rows of the inner water pipes 3 are arranged such that adjacent water pipes are arranged in close contact with each other. On the other hand, in FIG. 3, the rows of the inner water pipes 3 are also connected to each other by fins 16 like the rows of the outer water pipes 4, and the other points are the same.

[0018]

As described above, according to the present invention,
Since the inner water pipe and the outer water pipe are finless water pipes with an angled cross-section over the combustion gas passage of a predetermined length from the opening provided in the row of inner water pipes toward the downstream of the flow of the combustion gas, high temperature oxidation of fins and An excellent effect that a crack due to thermal stress is prevented and a water tube boiler equipped with a can body having a small blowing power can be realized is obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the structure of a water tube boiler according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the structure of a water tube boiler according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing the structure of a water tube boiler according to another embodiment of the present invention.

FIG. 4 is a plan sectional view showing the structure of a conventional water tube boiler of this type.

[Explanation of symbols]

 1 Upper Heading or Upper Body 2 Lower Heading or Lower Body 3 Inner Water Tube 4 Outer Water Tube 5 Combustion Gas Passage 6 Casing 7 Insulation Material 8 Combustion Chamber 9 Combustion Device 10 Opening 11 Opening 12 Flue 13 Fin of Cross Section 14 Finless water pipe with angled cross section 15 Fin 16 Fin

Claims (1)

[Claims] 1. An upper pipe head or an upper body and a lower pipe body or a lower body are both formed in an annular shape, and the upper pipe body or the upper body and the lower pipe body or the lower body are connected by a large number of inner water pipes and outer water pipes. Then, the inner water pipes are closely or connected by fins to be arranged as an annular water pipe wall, and the outer water pipes are tightly or connected by fins to be arranged as an annular water pipe wall, and the inner water pipe and the water pipe wall are A combustion gas passage is formed between the outer water pipe and the water pipe wall, and a fin having a cross section of an angle is attached to one or both of the inner water pipe and the outer water pipe facing the combustion gas passage in the pipe longitudinal direction. , While forming a combustion chamber in the annular water pipe wall of the inner water pipe,
An opening is provided in the annular water pipe wall of the inner water pipe to communicate the combustion chamber with the combustion gas passage, and an opening is provided in the annular water pipe wall of the outer water pipe to connect the combustion gas passage and the flue. In a boiler having a structure in which they communicate with each other, the inner water pipe and the outer water pipe are angled without fins over a combustion gas passage of a predetermined length from an opening provided in the row of the inner water pipe toward a downstream side of a flow of combustion gas. A water tube boiler characterized by using a water tube.