DEB0032803MA - - Google Patents

Description

INN REPUBLIC OF GERMANY

Registration date: September 29, 1954. Advertised on December 29, 1955

GERMAN PATENT OFFICE

PA TENTAN REGISTRATION UNG

CLASS 12k GROUP 9 B 32803 IVa / 12k

Dr. Heinrich Bommer, Ludwigshafen / Rh.

has been named as the inventor

Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen / Rh.

Process for the evaporation of formamide

For the production of hydrogen cyanide from Formamide, the type of evaporation of the formamide plays a crucial role. Formamide has a boiling point of around 200 °. At this temperature there is already considerable cleavage des Formaimidis in coal oxide and ammonia. Formamide can be in a very high vacuum and when using glass or stainless steel or precious metals, evaporate at a reduced rate. That for the avoidance of the decomposition of the formamide during evaporation required high vacuum however, this cannot be sustained when the formamide is used for the production of hydrogen cyanide should serve, as the between the creation of the vacuum and the evaporation of the formamide switched on contact and cleaning equipment the low pressure that is necessary in the evaporator would not be allowed. In addition, the hydrogen cyanide formed in the reaction, if one wants to win it as free acid, sucked off by the vacuum pump and not already before the Pump can be deposited. For the creation of a high vacuum would already be from this Basically, unusually high investments are required.

About the cleavage of formaimide in coblene oxide and to push back ammonia, it has therefore already been proposed to superheat the formamide

509 626/35

Claims (3)

B 32803 IVa112k Ι'Ί; "ιι · Ιιιίι to which it brim hit should be vaporized immediately without being deposited in liquid form in the vaporizer. Fine such rapid evaporation is said to be carried out in the manner according to another proposal that has come to light that the formamide is fed into an inclined, externally heated pipe at such a speed lets drop in that all of the formamide has evaporated at the exit of the tube. from A significant disadvantage in the implementation of this proposal on an industrial scale is that a A multitude of tubes is necessary, each of which contains a precisely dosed amount of formamide must be charged. Fs has now been found to avoid it noticeable yields due to the decomposition of formamide into carbon oxide and ammonia from the previous view it is not necessary to carry out the evaporation in a very high vacuum, but that you can tolerate the decomposition if you add the l'ormaiiiid moderate liter thickness or atinospheric pressure evaporated out of a sump of liquid formamide. Advantageously, the formamide in liner plurality of externally heated and dipping into the sump (U- ^ formamide tubes is evaporated. To this end, one can, l'Ormamid in, Line part introduce a trained as an evaporator Röhrcnkörpers whose pipes by suitably from top to The heating gases conducted below are heated. I) as formamide rises from the sump at the bottom (\ v ^ evaporator up in the tubes and evaporates from the () by "surface of the layer that it forms in the individual tubes and through the temperature of the idle gases is given, very quickly, with the formamide vapor being simultaneously heated to the temperature required for the subsequent contact furnace single tube for the vaporization of the forniamide If increased evaporation of formamide sets in, the counter pressure increases due to the larger amount of evaporated formamide and causes the liquid level in these tubes to drop, whereby the surface area is smaller and the evaporation speed is correspondingly lower. If, on the other hand, the heat transfer in individual tubes is lower as a result of incrustations, the Yorda inoculation speed is compensated for by the rise in the liquid level. In removing the l'Ormamid as quickly as possible from the temperature zone which is particularly favorable for decomposition, the diameter of the Yerdanipfor tubes can be kept as small as possible, or what has proven to be particularly expedient. the tubes are provided with a displacement body!) that an annular space with a width of only a few millimeters is created; The inventive method of operation not only ensures that the formamide reaching the boiling zone is evaporated quickly, but also that the formamide ^{vapor is brought as quickly as possible to the temperature of 360 0} and higher required at the contact, tie-ra.de the rapid passage through the Temperaturzonc the boiling point of -Formamids up to 360 ⁰ for the yield of hydrogen cyanide is of great importance since with the increase in temperature, the speed with which the formamide in Kolilenoxyd wild ammonia breaks down, increases until at 360 ⁰ a. Temperature is reached at which only a cleavage into hydrogen cyanide and water vapor takes place. The rapid passage of the formamide vapor This critical temperature range does not result in any of the described processes Evaporation of formamide achieved. One atomizes according to the mentioned, well-known suggestion Formamide on overheated surfaces without there being a sump of liquid formamide, so if the formamide vapor leaves the evaporator only at the pressure corresponding to the respective pressure Boiling temperature, since the atomization requires an apparatus with a large empty space, which lack the heating surfaces for the rapid heating of the formamide vapor. In the process to make the evaporation in an inclined, externally heated tube, is about it In addition, the available heating surface is not fully used because the formamide is a trickle runs along the testicle. Also by a modification of the arrangement used for this purpose, the one therein consists in placing the evaporator tube vertically and for even distribution of the formamide loaded with packing, it cannot be prevented that considerable losses through decomposition of the forniamide enter into carbon monoxide and ammonia and after a relatively short period of time Operating time the pipes are clogged by polymerizations and cracking of the formamide and need to be cleaned. Patkntansph reu ν. ·. ι. Degeneration of formamide for the preparation of hydrogen cyanide, characterized in that the formamide evaporated from a sump of liquid formamide at moderate negative pressure or atmospheric pressure. 2. Apparatus for carrying out the method according to claim 1, characterized by a plurality of externally heated and ^{immersed in the sump of the I 1} OnIIaInIdS tubes for the evaporation of the formamide. 3. Apparatus according to claim 2, characterized in that the tubes with Vc rdränguiigskörperern charged leaving an annular space only a few millimeters wide are. 509 626/35 12.55