JPH0132402B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a can structure for a multi-tubular once-through boiler that improves heat transfer efficiency.

[Prior Art] Conventionally, a can body of a multi-tubular once-through boiler is known in which a combustion gas flow path extending in the tube axis direction is formed by providing fins between water tubes constituting an annular water cooling wall. However, (Jitsugan 54-124518),
This invention further improves the above-mentioned one, and
The gist is that a combustion gas passage having a substantially triangular cross section is formed by surrounding two adjacent rows of inner and outer water tubes with gap-closing fins.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. In the drawings, numerals 1 and 2 are an annular upper header and a lower header. These upper headers 1 and 2 are connected by a large number of water pipes 3 and 4.

As is clear from FIGS. 2 and 3, the water pipes mentioned above are arranged in two concentric annular rows of water pipes spaced apart in the radial direction, with an inner row of water pipes 3 and an outer row of water pipes 4. The relative positions are set so that they are shifted by half a pitch along the circumferential direction (like a staggered arrangement). Furthermore, the space between each of the adjacent inner row water pipes 3, 3 and the outer row water pipe 4 is closed by a fin 6 and a fin 8, 8 having a width that matches the water pipe gap, so that the fins 8, 8 extend in the pipe axial direction. A large number of extending combustion gas passages 9 each having a substantially triangular cross section are partitioned in the circumferential direction.

Reference numeral 5 denotes an inner smoke vent, which is provided by cutting off the fin 6 between the inner water pipes 3 and 3 at the upper end of the water pipes, as shown in FIG. 7 is also a smoke vent, but this latter outside smoke vent is provided by cutting off the lower end of the fins 8, 8 that are connected to the outer water pipe 4. It is.

Reference numeral 10 denotes a combustion device, which is disposed facing downward inside the upper header 1, and a combustion chamber 11 is formed inside the water-cooled wall formed by the inner row water pipes 3. 12 is a casing, and 13 is a refractory. In the case of such a boiler case, the structure (flow path of combustion gas) can be changed by arranging the positions of the inner and outer smoke vents 5 and 7, the combustion device 10, etc. upside down.

In the structure of the can body according to the present invention, the combustion gas generated in the combustion device 10 is first transferred to the combustion chamber 1.
1, radiant heat is mainly transferred to the inner water pipes 3. This combustion gas passes through the smoke vent 5 on the inside of the upper end side of the inner row water pipe 3 and reaches the combustion gas passage 9.
Furthermore, the combustion gas descends through the combustion gas passage 9 while heating the water pipes 3 and 4, passes through the smoke vent 7 on the outside at the lower end of the water pipe, and passes through a flue (not shown) provided in a part of the casing 12. ), and in this process,
Forced convection heat transfer is applied to the circumferential surfaces of the inner and outer water pipes 3 and 4, and then the heat is discharged to the outside.

[Effects of the Invention] As explained above, the present invention has a structure in which a large number of combustion gas passages each having a substantially triangular cross section extending in the tube axis direction are formed in the circumferential direction by two rows of water tubes and fins. Coupled with the large increase in the thermal surface, the amount of heat held by the combustion gas can be effectively transferred to the water pipes by radiation and convection, and the amount of heat transferred to the inner and outer water pipes is averaged through each fin and localized. It is possible to suppress overheating, further improve heat transfer efficiency, and provide a highly efficient multi-tubular once-through boiler with a small can body.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the invention;
FIG. 2 is a cross-sectional view, and FIG. 3 is an enlarged cross-sectional view of the main part. 1... Upper header, 2... Lower header, 3...
Inner row water pipe, 4... Outer row water pipe, 5... Smoke vent, 6...
... Fin, 7... Smoke vent, 8... Fin, 9... Combustion gas passage, 10... Combustion device, 11... Combustion chamber,
12...Casing, 13...Refractory.

Claims (1)

[Claims] 1. The upper header 1 and the lower header 2 are connected by concentric two rows of inner and outer water pipes 3 and 4, and the positions of the inner row water pipes 3 and the outer row water pipes 4 are shifted by half a pitch in the circumferential direction, while The space between the inner water pipes 3 is closed by a fin 6, and the space between each of the adjacent inner water pipes 3 and the outer water pipe 4 is closed by a fin 8. Each of the combustion gas passages 9 extending in the tube axis direction, which are divided by A can body structure of a multi-tubular once-through boiler, characterized in that a smoke vent 5 and an outside smoke vent 7 are located on opposite sides in the tube axis direction.