Ex parte JOHNSON et al. - Page 8
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Board of Patent Appeals and Interferences > 2000 > Ex parte JOHNSON et al. - Page 8
Appeal No. 1997-1551
Application No. 08/235,597
The examiner indicates that Steag at p. 2, lines 4-13 sets forth a process for removing
SO2/SO3 out of a flue gas by initially passing the contaminated gas through a
dust collector followed by a dry cleaning of the gas to remove SO2/SO3.
After the dry cleaning, however, Steag captures the particles in a cloth filter (p. 2, lines
Steag does not teach the actual injection of dry sorbent particles into the flue gas stream
after the particulate collection step.
Instead, the reference teaches a multiple stage filtration in which the dust content
is reduced from 10-15 g/m3 to 600 mg/ m3 in the first filtration, to 100-
200 mg/ m3 after the dry gas cleaning stage, and to 10 mg/ m3 in the final
filtration (p. 2, lines 55-83 and 105-115).5
The reference does not explicitly discuss the dry gas cleaning process itself but
only indicates that such processes are Aknown per se@ at p. 2, line 15.
Steag does not teach wet scrubbing in particular but only acknowledges the existence of
such processes in the prior art at p. 1, lines 60-65.
The examiner relies upon Peterson at p. 6A-9 to show dry sorbent particles of 10 microns in
size, which meets the greater than 1.0 micron limitation presently claimed.
Although not specifically addressed in the Examiner=s Answer, Peterson shows the actual step
of ASorbent Injection@ into the flue gas stream for the purpose of removing SO3. See
p. 6A-16, para. 1. The dry sorbent is
5 The A10 to 15 mg/ m3@ reported at p. 2, line 57, of Steag is an obvious typographical error.
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