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83
the last four months of 1932, before the station, was in operation, compared
with corresponding periods of 1933 and 1934, do not, however,
indicate any increase of sulphur gas.
Assuming, however, that the coal consumed at the Battersea Power
Station had a sulphur content of 0.9 per cent., and that one ton of coal
liberated 375,000 cubic feet of flue gas the amount of sulphur in the flue
gases, estimated as sulphur dioxide, would be approximately 600 parts
per million parts of flue gas, which is equivalent to 0.753 grains per cubic
foot.
According to the report of the Government Chemist's Committee
the amount of sulphur in the flue gas after treatment is about 0.03 grains
of sulphur as sulphur dioxide per cubic foot of flue gas, equivalent to
24 parts of sulphur dioxide per million parts of flue gas. It thus appears
that the scrubbers at the Battersea Station are removing about 96 per
cent, of the sulphur impurities.
The average amount of sulphurous impurities in the atmosphere over
the City of Westminster, estimated as sulphur dioxide for the years
1932, 1933 and 1934, are given below in parts per million and grains
per cubic foot.
1932 0.137 parts per million.
0.00172 grains per cubic foot.
1933 0.130 parts per million.
0.000163 grains per cubic foot.
1934.0.136 parts per million.
0.000170 grains per cubic foot.
These figures are the mean of the results obtained during the years
mentioned by the instrument installed at the City Hall. Meteorological
factors, which have predominating influence on those figures, must be
taken into account, e.g., fog, temperature, humidity, rainfall, and direction
of the wind. And although up to the present the Battersea Station is
not shown to have caused any increase in the sulphur gas content as
measured at the City Hall, yet on the evidence of the most recent report
more than 2½ tons of sulphur in gaseous form is being added daily to the
air over Central London. The station is but one-third completed and
the Fulham Station has not yet come into the picture. It may be fairly
prophesied, unless sulphur elimination becomes one hundred per cent,
efficient that a much greater amount than 2½ tons of sulphur in gaseous
form will be distributed daily through the air of these central districts,
when the two stations referred to are in full working order.