Improvements in Method and Apparatus for Generating Formaldehyde Gas.
Year: 1897

page_text: Date of Application, 4th Nov., 1897-Accepted, 4th Dec., 1897
COMPLETE SPECIFICATION,
Improvements in Method and Apparatus for Generating
Formaldehyde Gas.
I, RAFAEL EMILIO PARRAGA, of 36, W 94th. Street, in the City of New York, County
and State of New York, United States of America, Merchant, 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.
The present improvements relate particularly to process of and apparatus for
the regeneration of formaldehyde gas from a commercial aqueous solution, and to the
utilizing of such gas for disinfection or effecting germicidal action.
Heretofore, this gas has been generated from a solution thereof by subjecting the
solution to heat in a closed vessel or generator, and holding the generated gas
confined in the generator until a pressure of at least two atmospheres has been
obtained, before permitting the gas to escape into the space or into contact with the
articles to be disinfected.
This method while partially successful, is still inefficient in respect of best
economy; in respect of securing from the solution the maximum of gas; in regard
to safety of use, cost and care of attention in generation; and in the production of
the gas in such pure condition as to best fit it to penetrate and act upon articles to
be disinfected.
It is not practicable, in commercial apparatus and especially in common hand
apparatus, to employ with safety the high pressure and heat necessary to break up
the products of polymerization and resolve them into original formaldehyde gas,
especially the products paraformaldehyde and trioxymethelene: isomeric compounds
locking up or rendering unavailable for the purposes of disinfection large percentages
of the formaldehyde in the solution.
Again it is known that the methyl alcohol usually added to the commercial
solution, to prevent the precipitation of the paraformaldehyde, will act in the common
process of generation to reduce the quantity of liberated formaldehyde gas by uniting
therewith to form a third product known as methelal, a substance having no
germicidal property. And further, it is known that the moisture or vapor of water
in the gas as heretofore generated acts to reduce the penetrative and germicidal
action of the gas by facilitating the formation of the isomer paraformaldehyde.
The present apparatus and process consist in submitting the commercial solution
to a high degree of heat (higher than anything heretofore attempted), by feeding
the solution in a fine sheet or strean to and conducting the regenerated gas along a
passage, channel or tube of considerable length (which is to be openly connected with
the space to be disinfected), and superheating the gas as it progresses through the
As the solution
tube by a source of heat acting on the walls of the passage or tube.
is introduced into the tube and first comes in contact with the heated portions
thereof, it is instantly vaporized, and as this vapor progresses through the tube, it is
superheated and brought to a temperature (say 1000° Fah.) sufficient to thoroughly
break up the products of polymerization and to convert, by partial oxidization, the
methyl alcohol into formaldehyde gas.
By this process, I generate from a given solution the maximum of formaldehyde
gas in purest form, and without the danger attending the use of high pressures, and

page_text: without the necessity of the exercise of any special skill or attention in working the
apparatus.
Referring to the drawings accompanying this application, the figure shown
illustrates a hand generator adapted to practise my process. A is a cylindrical
reservoir supported by the uprights B, which also carry a lamp or other source of
heat, G being the lamp, and D, its fount. E is a spirally arranged copper tube, one
end of which opens into the reservoir A and is controlled by a needle valve F, the
stein of which is threaded in the stuffing box G in the top of the generator so as to
render the valve adjustable to and from its seat H. I is the bottom of the reservoir
which is preferably composed of asbestos or some other non-conductor of heat. I
utilize this non-conductor for the purpose of preventing any essential application of
heat to the contents of the reservoir, and so that I can arrange the reservoir over
the lamp in a form of apparatus most compact and convenient for handling. The
other end of the copper coil J connects with a pipe K which is connected to the place
or space where it is desired to use the formaldehyde gas.
Assuming that the reservoir contains a quantity of solution of formaldehyde, the
lamp will be lighted, and in a few moments will bring the regenerating coil to a high
heat, practically incandescent heat. Then the needle valve will be slightly raised
and the contents of the reservoir permitted to pass under gravity in a fine stream
into the coil. When the solution strikes the heated portion of the coil, it immediately
vaporizes and this vapor, progressing through the coil, is heated to a sufficiently high
heat to reduce or break up the products of polymerization, and, at the same time,
convert, by partial oxidation, the methyl alcohol into formaldehyde gas.
The gas resulting from the pacctice of this process will be found to be penetrative
to a greater extent than heretofore known, as also greater in quantity, from a given
solution, and with less of deposit on or combination with the material of the articles
treated. The apparatus needs no special attention during the generation of the gas,
as the matter of pressure is not an incident, and the generation of gas is not
intermittent, but goes on continuously and automatically.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, declare that what I
claim is:-
1. The herein described process of regenerating formaldehyde gas which consists
in heating a solution from which the gas may be regenerated or vaporized, and
subsequently superheating such vapor without subjecting it to pressure, substantially
as described.
2. The herein described process of regenerating formaldehyde gas, which consists
in heating a solution from which the gas may be generated or vaporized, and
thereafter superheating the vapor formed from the solution for the purpose of
changing the isomeric products carried by such vapor, substantially as described.
3. The herein described process of regenerating formaldehyde gas, which consists
in heating very small quantities of a solution from which the gas may be generated
and to vaporize the same, and subsequently superheating the vapor so produced,
substantially as described.
4. The herein described apparatus adapted to be used in the regeneration of
formaldehyde gas, consisting of a reservoir adapted to contain a solution, having a
bottom of non-heat-conducting material, a coil arranged close under such bottom, a
heater for such coil, and a controllable liquid passage from the interior of such
reservoir into the coil, substantially as described.
Dated this 4th day of November 1897
FELL & JAMES
Agents for the Applicant.