JPH033761Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] This invention relates to an improvement for improving the radiation heat transfer characteristics of combustion gas to the water tubes of a gas-fired multi-tubular once-through boiler.

[Prior art]

In a boiler, the form of heat transfer between combustion gas and water tubes is generally classified into the following two types. One type is based on radiant heat transfer that utilizes radiation from high-temperature gas generated when fuel is combusted, and the other is based on radiant heat transfer that uses radiation from the combustion gas that is lowered in temperature by radiant heat transfer. The main method is convective heat transfer by causing the material to flow along the heat transfer surface.

In the furnace of a boiler, the combustion gas temperature is high, and most of the heat transfer is by radiation heat transfer. This radiation heat transfer is also caused by gas radiation radiated from water vapor and carbon dioxide gas in the combustion gas (non-luminous flame radiation), and radiant radiation from ultrafine carbon grains generated when petroleum, coal, etc. are burned. It is divided into flame radiation. In the case of an oil-fired boiler, non-bright flame radiation and bright flame radiation occur simultaneously, and efficient radiation heat transfer is performed within the combustion furnace. However, in the case of gas-fired boilers, bright flame radiation almost never occurs, except in special conditions due to incomplete combustion such as lack of air or uneven combustion, and the radiation heat transfer effect in the combustion furnace is Smaller than a fire.

[Summary of the idea]

This idea improves the radiation heat transfer characteristics in the combustion furnace by installing a simple-structured radiation heat transfer promoter in the combustion furnace and making it red hot. The aim is to provide a once-through boiler.

[Example of idea]

This invention will be explained below based on the drawings. FIG. 1 is a schematic longitudinal cross-sectional view of an embodiment of this invention, and FIG. 2 is a cross-sectional view of FIG. 1.
In the figure, 1 is an upper header, 2 is a lower header, and 3 is a water pipe, and the upper and lower headers 1 and 2 are connected by the 3 groups of water pipes. The three groups of water tubes are arranged in an annular shape, and the inside thereof is formed as a combustion chamber 4. Reference numeral 5 denotes a radiation heat transfer accelerator, which is disposed on the combustion chamber 4 side of the three groups of water tubes arranged in an annular shape, in front of the water tubes with a certain gap between them. The radiation heat transfer promoter is made of, for example, a wire mesh or punched metal with a large number of holes, and is installed to cover the entire length of the water pipe. 6 is a flue.

Next, the operation will be explained based on the drawings. The supplied gaseous fuel is combusted in the combustion chamber 4, and the combustion gas is
It flows into the gap between the three groups of water tubes only through the perforations of the radiation heat transfer promoter, and further reaches the flue 6 through the outer periphery of the three groups of water tubes. Radiant heat transfer promoter 5 in combustion chamber 4
is heated by flameless radiation heat transfer and convection heat transfer from the combustion gas in the combustion chamber 4, and becomes red-hot. In this state, the radiation heat transfer promoter 5 is heated independently due to the constant (preferably several mm) gap provided between it and the water tube 3, and the surface of the water tube (heat transfer surface) In order to maintain the desired temperature difference between
Generation of radiant heat is not impaired.

The surface of the water pipe 3 on the side facing the radiant heat transfer promoter 5 is heated by the radiant heat transfer promoter 5 which has become red hot as described above, and the radiant heat can be effectively transferred to the water pipe. . That is, compared to a conventional gas-fired multi-tubular once-through boiler, the amount of radiant heat transferred within the combustion furnace is greatly increased. The combustion chamber 4 side of the group of water tubes 3 is heated by flameless radiation heat transfer from the combustion gas in the combustion chamber, radiation heat transfer due to the red heat of the radiation heat transfer promoter 5, and convection heat transfer of the combustion gas. The outer peripheral surface of the three groups of water tubes is heated by convection heat transfer from the low-temperature combustion gas and a small amount of flameless radiation.

[Effect of idea]

This idea was made in order to solve the above-mentioned drawbacks of gas-fired multi-tube once-through boilers, and was designed to provide a fixed interval from the water tubes on the combustion chamber side of the water tube group over the entire length of the water tubes. By heating the radiant heat transfer accelerator disposed in front of the radiant heat transfer accelerator with combustion gas and making it red-hot, flameless radiation from the combustion gas and red-hot radiation from the radiant heat transfer accelerator are generated on the heat transfer surface surface of the water tube group. This system is designed to improve heat transfer to the water pipes, so by simply installing a radiation heat transfer accelerator with a simple structure inside the combustion chamber, a gas-fired multi-tubular once-through system with excellent heat transfer efficiency can be achieved. A boiler can be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal cross-sectional view showing an embodiment of this invention, and FIG. 2 is a cross-sectional view of FIG. 1. 1... Upper header, 2... Lower header, 3...
Water pipe, 4... Combustion chamber, 5... Radiant heat transfer promoter, 6
...flue.

Claims (1)

[Scope of claim for utility model registration] The upper header 1 and the lower header 2 are combined into a large number of water pipes 3.
In this multi-tube once-through boiler, a space surrounded by a group of water tubes is formed as a combustion chamber 4, and the three groups of water tubes have a large number of holes formed of a cylindrical member on the side of the combustion chamber 4. A gas-fired multi-tube type gas-fired multi-tube type, characterized in that the radiation heat transfer accelerator 5 is disposed to cover the inner surfaces of the water pipes 3 over the entire length thereof, with a constant gap between them. Once-through boiler.