Improvements in or relating to Preventing Incrustation in Steam Generators.
Year: 1898

page_text: Date of Application, 24th Nov., 1898-Accepted, 4th Feb.,
1899
COMPLETE SPECIFICATION.
Improvements in or relating to Preventing Incrustation in Steam
Generators.
I, WILHELM KIRCHNER, of Hemelingen, near Bremen, in the German Empire,
Technical Director of the Aluminium and Magnesium Factory of Hemelingen,
aforesaid, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement, that is to say :-
This invention relates to improvements in preventing incrustation in steam
generators, by means of electro positive plates suspended in the generator and
placed in suitable connection with the walls thereof. The galvanic current thus
generated evolves hydrogen bubbles which settle on the walls of the generator and
thereby prevent the sediment from firmly adhering to the generator surface.
Experiments have been made for preventing incrustation of steam generators by
using zinc blocks located in the interior of the generator, in appropriate metallic
receivers, the remaining space in which was filled with sodium chloride.
A copper
core connected with the zinc block established communication with the walls of the
generator by the aid of suitably connected conducting wires. The intended action
was that the hydrogen bubbles resulting from the decomposition of the water
would prevent the sediment from forming incrustation. This has not, however,
been successful in practice, as the amount of hydrogen developed was too small to
prevent incrustation.
For this reason, it was sought to ensure a better result by employing an
alternating current, but in such case, however, special switching apparatus were
required.
Now, the object of the present invention is the production of an energetic
formation of hydrogen in a very simple manner, whereby all solid incrustation is
completely prevented.
To this end, instead of using zinc electrodes, as formerly, I use electrodes
consisting of zinc and magnesium alloys.
It is well known that magnesium constitutes a far stronger electro-positive
element than zinc, so that by forming an alloy of these two metals, a much more
energetic effect will be obtained than has hitherto been possible. Ziuc is alloyed
with magnesium and the resulting alloy is either used in such state, or is, in
addition, alloyed with copper, or with aluminium, or with both copper and
aluminium.
These plates are so suspended in the generator as to be in conducting contact
with the walls thereof, and so as to be simultaneously completely immersed in the
water in the generator.
The following effect is produced by these plates:
By the conjunction of iron and zinc-magnesium in water which contains salt, a
galvanic current is generated.
The zinc magnesium plates become positive and are consumed by oxidation. On
the other hand, hydrogen bubbles are separated on the walls of the generator and
thus prevent sediment from firmly adhering to their surfaces. At the same time,

page_text: all injurious salts contained in the feed water of the generator, more especially the
chlorides, act solely upon the magnesium-zinc while the iron walls remain free from
corrosion.
The loose sediment may thus be removed by simply brushing or scraping, and
the difficult operation of chipping off the scale with pointed tools, whereby the
walls of the generator are often greatly injured, is entirely avoided.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. For preventing incrustation in steam generators, in the manner referred to,
the employment of electrodes consisting of an alloy of zinc and magnesium either
separately or alloyed with copper or aluminium, or with copper and aluminium.
2. My improvements in or relating to preventing incrustation in steam
generators, substantially as herein before described.
May Hiper 1030.
ERNEST DE PASS,
Chartered Patent Agent, 78, Fleet Street, London,
5A, Market Street, Nottingham, Agent for the Applicant.