8.2.2 The Circulation Apparatus
There is little doubt that the circulation apparatus too was developed in an
incremental fashion, and in his 1928 paper
10 Robert provided some indication of how progress was made between May 1908 and March 1909. He tells
us that ‘great difficulties … arose again and again from the scientific and technical side … [eventually] a small technical [circulation] apparatus was built but
experiments made with it proved disappointing and that’s why more strenuous
efforts were made to find a better catalyst. … At the same time when the
experiments for a suitable catalyst were taking place a new smaller apparatus was
built …’.
Like the furnace then, at least two versions of the circulation machine
evolved, but once again it is only possible to describe the final machine with
any accuracy. The primary feature of these machines was high pressure, but
because of the cost of the feedstock, circulation was recognised as an essential
component, returning ‘unbound’ gases back to the catalyst and replenishing
the used gases from a high-pressure reservoir, of which no technical detail
remains. Their previous work—especially ‘Bestimmung …’—had suggested
that circulation would not prove a major problem and this design not only
economised on raw materials but minimised the work required to
re-compress the gases. Circulation however required a circulation pump, and
so a small ‘double acting’ steel pump, designed by Robert, was built which
not only circulated gases but also served to exhaust the apparatus prior to
pressurisation. The pump operated at about 300 rev. min
−1 with a maximum
capacity 72 m
3 h
−1 measured at ‘NTP’, and although in practice it was not
quite as efficient as Robert would have liked due to the leather packing of the
piston proving ‘not quite satisfactory’,
15 it operated well at pressures up
200 atm. ‘Troublesome’ as Haber later described the whole task,
23 at no time
during this period did the workers report any particular difficulty in achieving
and maintaining pressures between 100 and 200 atm whilst freely moving gas
through the apparatus. This was due to ‘Kirchenbauer’s’
16
‘special joints’, the
use of ‘Vulcan fibre’ gaskets which made other joints gas-tight, and of course
Robert’s special ‘conical’ valves.
‘Conical valves’ however were hardly a new invention; indeed, they had
been around for almost 100 years and were widely used in steam engines.
Their use in a ‘pneumatic’ apparatus was described as long ago as 1820
24
when The New Monthly Magazine carried an article by Sig. Crivelli,
Professor of Natural Philosophy in Milan who described such a valve,
declaring that ‘ … the emission of the gas may in this way be regulated with great
164
D. Sheppard
There is little doubt that the circulation apparatus too was developed in an
incremental fashion, and in his 1928 paper
10 Robert provided some indication of how progress was made between May 1908 and March 1909. He tells
us that ‘great difficulties … arose again and again from the scientific and technical side … [eventually] a small technical [circulation] apparatus was built but
experiments made with it proved disappointing and that’s why more strenuous
efforts were made to find a better catalyst. … At the same time when the
experiments for a suitable catalyst were taking place a new smaller apparatus was
built …’.
Like the furnace then, at least two versions of the circulation machine
evolved, but once again it is only possible to describe the final machine with
any accuracy. The primary feature of these machines was high pressure, but
because of the cost of the feedstock, circulation was recognised as an essential
component, returning ‘unbound’ gases back to the catalyst and replenishing
the used gases from a high-pressure reservoir, of which no technical detail
remains. Their previous work—especially ‘Bestimmung …’—had suggested
that circulation would not prove a major problem and this design not only
economised on raw materials but minimised the work required to
re-compress the gases. Circulation however required a circulation pump, and
so a small ‘double acting’ steel pump, designed by Robert, was built which
not only circulated gases but also served to exhaust the apparatus prior to
pressurisation. The pump operated at about 300 rev. min
−1 with a maximum
capacity 72 m
3 h
−1 measured at ‘NTP’, and although in practice it was not
quite as efficient as Robert would have liked due to the leather packing of the
piston proving ‘not quite satisfactory’,
15 it operated well at pressures up
200 atm. ‘Troublesome’ as Haber later described the whole task,
23 at no time
during this period did the workers report any particular difficulty in achieving
and maintaining pressures between 100 and 200 atm whilst freely moving gas
through the apparatus. This was due to ‘Kirchenbauer’s’
16
‘special joints’, the
use of ‘Vulcan fibre’ gaskets which made other joints gas-tight, and of course
Robert’s special ‘conical’ valves.
‘Conical valves’ however were hardly a new invention; indeed, they had
been around for almost 100 years and were widely used in steam engines.
Their use in a ‘pneumatic’ apparatus was described as long ago as 1820
24
when The New Monthly Magazine carried an article by Sig. Crivelli,
Professor of Natural Philosophy in Milan who described such a valve,
declaring that ‘ … the emission of the gas may in this way be regulated with great
164
D. Sheppard