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Method for purifying waste gases produced during the production of cyanuric chloride

A cyanuric chloride and tail gas technology, applied in chemical instruments and methods, cyanogen halide, separation methods, etc., can solve the problems of unstable chlorine content, easy change, low reaction rate of chlorine and hydrogen cyanide, etc., and achieve cost and production. The effect of low cost, efficient cleaning steps, and low technical complexity

Inactive Publication Date: 2009-06-17
EVONIK DEGUSSA GMBH
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Problems solved by technology

[0004] The disadvantage of DE-B 28 43 383 is that the reaction rate of chlorine and hydrogen cyanide is low in the residual gas workup and that large quantities of water have to be recycled into the cyanogen chloride reactor
[0005] In addition, the chlorine content in the tail gas is not constant, but easy to change, so the composition of the obtained cyanogen chloride solution varies greatly
However, due to the recycling of this solution into the cyanogen chloride reactor, there arises the problem of not being able to optimally control the reaction in the reactor

Method used

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  • Method for purifying waste gases produced during the production of cyanuric chloride

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Embodiment

[0018] Column B is filled with water via line 9 to a level of about 1 m below line 3 . Then turn on the circulating pump PB (150m 3 / h), and the level is maintained at this level with the LIC. When the lower part of column A overflows in line 4, the circulating pump PA (150m 3 / h). Now, adjust the amount of water provided to 4m 3 / h, and add 30% sodium hydroxide solution until the pH in column A>10. The introduction of the tail gas obtained in the preparation of cyanuric chloride can now be started.

[0019] The obtained tail gas (about 12000m 3 / h) Introduced into the lower part of the washing column A, wherein the tail gas contains, in addition to air, about 200 kg of chlorine and about 25 kg of cyanogen chloride. The alkaline hypochlorite (hypochlorite forms immediately when chlorine gas is introduced into the sodium hydroxide solution) aqueous solution pumped in by line 2 circulation removes part of the chlorine gas and almost all of the cyanogen chloride in the tail...

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Abstract

The invention relates to a method for purifying waste gases produced during the production of cyanuric chloride. In the first step, the waste gas is treated with a weak alkaline, aqueous solution that contains hypochlorite and is treated, in the second step, with a strongly alkaline, aqueous solution. The harmful substances chlorine cyanide and chlorine are practically quantitatively bonded without it leading to a high contamination of waste water.

Description

technical field [0001] The invention relates to a method for purifying tail gas obtained in the preparation of cyanuric chloride. Background technique [0002] Cyanuric chloride is prepared on an industrial scale by reacting hydrogen cyanide and / or sodium cyanide with chlorine gas in the presence of water to form cyanuric chloride and hydrochloric acid or sodium chloride. Subsequently, cyanuric chloride is trimerized to cyanuric chloride on activated carbon. The cyanuric chloride vapor leaving the trimerization reactor and still containing a certain amount of unconverted chlorine and cyanogen chloride is then sent together with cold air to a separator in which cyanuric chloride is obtained in crystalline form. For environmental reasons, the gas from the separator, consisting essentially of air and the unconverted compounds cyanogen chloride and chlorine, cannot be released directly into the atmosphere but needs to be worked up. It is known to extractively scrub the off-gas...

Claims

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Application Information

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IPC IPC(8): B01D53/68B01D53/54B01D53/78C01C3/00C07D251/28
CPCC07D251/28C01C3/004
Inventor H·陶茨
Owner EVONIK DEGUSSA GMBH
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