JPS5812904A - Multitubular type once-through boiler - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a multi-tubular once-through boiler.

Conventionally, the water tubes used in multi-tubular once-through boilers are bare tubes, which have the drawback of having a small heat transfer area per unit volume and requiring a large installation space.

Therefore, it is possible to use a finned water tube, but a finned water tube in which the fins are attached in a circumferential direction or in a spiral has the disadvantage that the flow rate of combustion gas through the tube is slow and a high heat transfer coefficient cannot be achieved.

In view of the above points, it is an object of the present invention to provide a multi-tubular once-through boiler that requires a small installation space and has good heat transfer.

Hereinafter, an embodiment of the present invention will be described based on the drawings. An upper header 1 and a lower header 2 are both formed in an annular shape. The upper and lower headers 1 and 2 are connected by a large number of vertical water pipes 3, and these water pipes 3 are arranged as an annular water pipe wall with a slight gap. A boiler outer wall 4 is housed outside the water pipe wall at a distance from this. Thus, an annular combustion gas passage 5 is formed between the water pipe wall and the boiler outer wall 4. A combustion device 6 is provided inside the upper header 1. If desired, this combustion device 6
can also be placed here by utilizing the space formed inside the lower header 2.

A combustion chamber 7 is formed within the annular water pipe wall. Both ends of each water pipe 3 are reduced-diameter parts 8, which are fitted and welded to the tube plates of the upper header 1 and the lower header 2, respectively. water pipe 3
The fins 9 are attached in a circumferential direction or in a spiral shape. It is preferable that the fins 9 are bent or cut at their mutually contacting portions to shorten the distance between the water pipes and increase the flow rate of the combustion gas. Fined water pipe 3
The valley of the part facing the boiler outer wall 4 side has a cross section of approximately V.
Letter-shaped heat transfer promoting plates 10 are attached, and these heat transfer promoting plates 10 are arranged so as to leave a slight gap between them and the finned water tubes 3.

To explain its operation in the above configuration, the combustion gas generated in the combustion chamber 7 first exchanges heat with the finned water pipe 3 by radiation heat transfer, flows almost perpendicularly to the water pipe, and flows into the adjacent finned water pipe. 3. It passes through the gap formed by 3 while exchanging heat by convection heat transfer, and further passes through the gap formed between it and the heat transfer promotion plate 10 while exchanging heat, and reaches the annular combustion gas passage 5. . At this time, fin 9
And heat transfer is good due to the heat transfer promotion plate 10.

The combustion gas is then discharged to the outside from a chimney (not shown) provided on a part of the boiler outer wall 4.

As explained above, this invention uses a finned water pipe,
Furthermore, since the heat transfer promoting plate is attached, it is possible to provide a multi-tubular once-through boiler that requires a small installation space and has good heat transfer.

[Brief explanation of the drawing]

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 a partially enlarged cross-sectional view. 1 is an upper header, 2 is a lower header, 3 is a water pipe, 4 is an outer wall of the boiler, 5 is a combustion gas passage, 6 is a combustion device, 7 is a combustion chamber, i is a reduced diameter part of a water pipe, 9. 10 is a fin attached to the water pipe in a circumferential direction or spirally, and 10 is a heat transfer promoting plate. Figure 1

Claims (1)

[Claims] Both the upper header 1 and the lower header 2 are formed in an annular shape, and the upper and lower headers 1 and 2 are connected by a large number of vertical water pipes 3, and these water pipes 3 are arranged as an annular water pipe wall with a slight gap. The boiler outer wall 4 is installed at intervals on the outside of the water pipe wall.
An annular combustion gas passage 5 is formed between the water tube wall and the boiler outer wall 4, a combustion chamber 7 is formed within the annular water tube wall, and fins 9 are provided in the water tube 3 in a circumferential direction or in a spiral shape. Attach a heat transfer promoting plate 10 with a substantially V-shaped cross section to the valley of the finned water pipe 3 facing the boiler outer wall 4,
A multi-tube once-through boiler characterized in that these heat transfer promoting plates 10 are arranged so as to have a slight gap between them and the finned water tubes 3.