Heat transfer tubes for fluidized bed combustion boilers

Abstract

The invention provides a heat transfer tube of a fluidized bed combustion boiler with a protective part, which reduces the initial cost by avoiding a complicated structure, and takes into account maintenance such as installation and replacement, reduces the risk of cracking and deformation, and is resistant to corrosion Sufficient durability in abrasive environments. The heat transfer tube (1) is used in the fluidized bed of the fluidized bed combustion boiler, and it is composed of the following components: a water tube (2) for fluid flow inside; it is arranged on the outer peripheral side of the water tube (2) and used to protect the water tube ( 2) the thin-walled protective part (4) and the thick-walled protective part (3) made of castings; the heat insulation layer (6) located between the water pipe (2) and the thin-walled protective part (4); and the fixing fixture ( 5), fixing the fixing fixture (5) on the thick-walled protection piece (3), and pressing the thin-walled protection piece (4) arranged on the outer peripheral side of the water pipe (2) by the fixing fixture (5).

Description

technical field [0001] The present invention relates to heat transfer tubes for use in a fluidized bed of a fluidized bed combustion boiler that burns waste and fuels such as RDF (refuse derived fuel), biomass, and recovers the heat of combustion. Background technique [0002] In recent years, efficient use of energy resources has been pursued from the viewpoint of coping with the rising prices of fossil fuels and global warming. Among them, the importance of power generation systems that combust fuels such as waste, RDF, and biomass, which perform a part of heat recovery, is increasing. In this power generation system, there is a way to recover heat energy generated when fuels such as waste and RDF, biomass, etc. are burned using a fluidized bed combustion boiler through heat transfer tubes. In this system, when waste materials and fuels such as RDF and biomass are combusted in a fluidized bed combustion boiler, chlorides generated in the fuel may form a severe corrosive e...

AI Technical Summary

Problems solved by technology

However, since the structure becomes complicated, maintenance becomes complicated in addition to the cost of the protective parts

[0013] Regarding thickening in measures to increase life, although castings are easy to thicken and low in cost, welding may be difficult due to the material

In addition, on-site welding work itself may be difficult, and from the viewpoint of maintenance, it is expected that there will be little on-site welding work.

For example, when the heat transfer tube is fully protected by a protective member, the number of welded parts increases and the workload becomes higher, resulting in deterioration of workability involving installation / replacement

In particular, in the case where the entire circumference of the heat transfer tube needs to be protected, since the number of protective members increases, complicated protective members not only lead to an increase in cost but also to a decrease in work efficiency

In addition, thick-walled protectors also lead to reduced workability due to increased weight.

Further, in the case of combining thick-walled protectors to form a fitted structure, the bed material will intrude between the protector and the heat transfer tube during operation, and excessive stress will be generated during cooling, resulting in Risk of cracking of protective parts

[0014] From the perspective of wear resistance, it is effective to increase the temperature of the protective part, but if there is a gap between the protective part and the heat transfer tube, the bed material will enter into the gap that expands during operation, and due to the Will shrink, so excessive stress will be generated, and there will be a risk of cracking or deformation of the protector, etc.

On the other hand, from the perspective of corrosion resistance, it is proposed to reduce the surface temperature of the protective part, but no suitable method has been found for the appropriate conditions under the conditions of both corrosion resistance and wear resistance.

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