Cleaning and liquid contact with solids – Processes – Hollow work – internal surface treatment
Patent
1994-01-24
1995-08-22
Simmons, David A.
Cleaning and liquid contact with solids
Processes
Hollow work, internal surface treatment
134 8, 134 16, 134 37, 134 2218, B08B 500, B08B 900, B08B 700
Patent
active
054436540
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to a method and apparatus for introducing hot process or flue gases through an inlet duct into a gas cooler. The method and apparatus according to the invention are especially suitable for feeding hot gases as fluidizing gas into a gas cooler provided with a fluidized bed.
Hot process gases usually contain fouling components, such as fine dust and molten or evaporated components, which turn sticky when they cool and condense, thereby adhering to each other and to surfaces in contact with the gases. In this way, these fouling components may very fast grow harmful deposits on the wall surfaces in contact with the process gases. Usually, the deposits seem to accumulate most easily in the border area between the hot and the cooled surfaces. For example, gas inlets of waste heat boilers are places where such deposits usually accumulate. Consequently, the inlet becomes easily clogged unless swept at times. Sweeping as such may be difficult in those hot conditions.
Furthermore, it is normally difficult to disengage the deposits accumulated in the hot inlet opening because the deposits accumulating on hot surfaces are hard and compact. In most cases, the inlet ducts are of refractory-lined construction or of ceramic material, having a slightly uneven and possibly even porous surface, which contributes to the adhesion of deposits to the surfaces. Sweeping of a refractory-lined surface may in turn damage the refractory lining.
The formation of deposits has been attempted to prevent, e.g., by blowing gas which is, for example, recirculated, cooled and purified process gas, into the inlet. This prevents, to some extent, sticky compounds from adhering to the walls in the vicinity of the inlet. However, the volume of the recirculated gas has to be considerably large in order to keep the inlet clear. This enlarges the overall gas volume entering the gas cooler, which grows the dimensions of the gas cooler and subsequent gas cooling means, in other words, increases the costs. Furthermore, the efficiency of heat recovery from the gases is lowered by mixing of cooled gas with hot process gases prior to heat recovery units.
An object of the present invention is to provide an improved method and apparatus for introducing hot process gases into a gas cooler in comparison with those described hereinabove.
An object is especially to provide a method and apparatus by which the deposits accumulated in the hot gas inlet duct are readily removable.
A still further ojject is to provide a method and apparatus by which the properties of the deposits accumulated in the inlet duct allow such deposits to be readily disengaged from the duct walls.
A characteristic feature of the method according to the invention for introducing hot process or flue gases into a cooling chamber is that the inlet duct wall is indirectly cooled with a cooling medium by bringing the wall surface opposite to the gas side surface into contact with the cooling medium, whereby the deposits formed on the wall surface on the inlet duct gas side embrittle and become readily removable.
For disengaging the deposits from the inlet duct walls, these walls are subjected to a sudden mechanical force, which causes a temporary deformation or vibration of the wall, thereby loosening the deposits accumulated on the wall surface.
A characteristic feature of the apparatus according to the invention for introducing hot process or flue gases into a gas cooler is that the inlet duct of the gas cooler is formed of a cooled, elastic structure, in which the inlet duct walls are formed of cooled surfaces made of metal.
The inlet duct is preferably provided with an apparatus by which the inlet duct walls may be subjected to a sudden mechanical force, which causes a temporary deformation and/or vibration of the walls.
The invention is especially suitable for plants where hot process gases are cooled in a cooling chamber provided with a fluidized bed and where the hot process gas simultaneously serves as a fluidizing ga
REFERENCES:
patent: 2971830 (1961-02-01), Kawai et al.
patent: 4874037 (1989-10-01), Papst et al.
Hiltunen Matti A.
Ikonen Ossi
A. Ahlstrom Corporation
El-Arini Zeinab
Simmons David A.
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