Metal working – Method of mechanical manufacture – Heat exchanger or boiler making
Patent
1998-10-06
2000-10-10
Cuda, Irene
Metal working
Method of mechanical manufacture
Heat exchanger or boiler making
2940218, B23P 1526
Patent
active
061288225
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for repair and/or reinforcement of a partition of a partition-type heat exchanger.
BACKGROUND OF THE INVENTION
There is conventionally known a partition-type heat exchanger having an object to apply a treatment such as heating of an object to be heated, phase transformation or a reaction by arranging a heating gas on one side of the partition and the object to be heated on the other side, and causing the heat from the heating gas to transfer through the partition to the object to be heated.
For example, the "CERAMIC HEAT EXCHANGER CONCEPTS AND TECHNOLOGY", (NOYES PUBLICATIONS, 1985) discloses various partition-type heat exchangers for heat exchange between gases (hereinafter referred to as the "prior art 1"). More specifically, a partition-type heat exchanger disclosed in the prior art 1, is of the finned plate type, the tube in shell type, the tube in tube type or the helical type in terms of the structure, and the material of the partition comprises codielite (2MgO/2Al.sub.2 O.sub.3 /5SiO.sub.2), magnesia-alumina silicate and silicon carbide. Such a ceramic partition suffers from quality deterioration during a long-term use, leading to occurrence of cracks. Further, when cracks grow into through-cracks, a gas on the high-pressure side leaks through the partition to the low-pressure side, thus making the partition inapplicable. The prior art 1 describes no method for repairing through-cracks occurring in the partition. In the aforementioned heat exchanger, therefore, a damaged partition is conjectured to be abandoned.
A coke oven is a furnace for manufacturing coke through dry distillation of coal, and serves also as a heat exchange between a gas and a solid. In the coke oven, there are alternately arranged carbonization chambers into which coal is charged and combustion chambers for generating a heating gas via partitions. First, the partition is heated by the heating gas. Then, heat is transferred, via the partition, to the coal charged in the carbonization chamber. The coal is thus pyrolysed, and dry distillation proceeds. Silica bricks are usually used for the aforementioned partition. Further, Japanese Unexamined Patent Publication No. S52-91,001 discloses use of a partition comprising silica carbide bricks. The partition has generally a thickness within a range of from 50 to 150 mm.
Finished high-temperature coke upon the completion of dry distillation is discharged by an extruder from the extruding side to the coke side after removal of covers on the extruding side and the coke side. Then, coal of the next charge at the room temperature is charged through a coal charging port provided at the top, and the aforementioned process is repeated. The partition is shaven by the extruded coke. Repetition of heating and cooling causes joint breakage between bricks or a cracking damage to the bricks. When a cracking damage becomes larger as to run through the carbonization chamber and the combustion chamber, a dry distillation gas containing aromatic hydrocarbon leaks from the carbonization chamber into the combustion chamber, making it difficult to continue dry distillation of coal. To avoid this inconvenience, it is the usual practice to repair the above-mentioned cracking damage.
For the purpose of repairing, there is known a method of pneumatically transporting a refractory powder to an empty carbonization chamber and filling a through-crack with the refractory powder. This method, although permitting temporary reduction of gas leakage, does not ensure reinforcement of bricks, with the gas leakage reducing effect not lasting long. This is attributable to the fact that the refractory powder accumulated at the through-crack shrinks as sintering proceeds, leading to production of voids, and then, the gas flowing from the voids causes scattering of sintered pieces, thus causing again expansion of cracks. When, upon filling the through-crack with the refractory powder, the powder passes through the through-crack, reaches the combustion chambe
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Kato Akira
Nishio Hiroaki
Cuda Irene
NKK Corporation
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