DE455223C - Preheater for brine u. like - Google Patents

Description

Preheater for brine and the like. The heating of the dissolving brine in the potash industry generally takes place in tube preheaters, the tubes of which are made of copper or those with a high copper content Alloys exist. These pipes suffer a considerable amount from the brine Attack, so that in general destruction in a relatively short time the pipes occur, which cause them to become unusable. The replacement the pipes burden the operating costs not insignificantly, and one has as a result also always tried, by selecting suitable alloys and other things Ways to prevent destruction.

It has now been established that the destruction of the pipes an always present secondary component of salt brine, namely iron, to a considerable extent Degree is to blame. The iron in the brine is partly divalent and partly trivalent Form present as the corresponding chlorine compound. When passing through the preheater the trivalent chlorine compound of iron is reduced to the divalent one, and a corresponding amount of copper goes into solution. This destruction is supposed to can be avoided according to the invention that there is a filter in front of the preheater switches that with a suitable material for the reduction of trivalent iron is filled. As such material, e.g. B. copper waste come into question, then but also iron waste, e.g. B. turnings or other suitable inexpensive material.

The use of iron filters is in a different area known, namely for the removal of oxygen from boiler feed water. Here but it is a completely different chemical process. The oxygen is simply bound to iron oxide by oxidation of the iron.

The technical effect of the new facility is numerical Comparative tests have been determined.

For the determination of the copper in the brine, the procedure was as follows: that copper and iron were precipitated by the addition of potassium ferrocyanide. To the A quantum of 8 to 1 brine was used for precipitation. After standing for about a week the precipitate was filtered through a membrane filter and washed out. then the precipitate was decomposed by smoking with concentrated sulfuric acid, the residue was taken up with dilute acid and electrolyzed in the usual way.

To determine the divalent iron, the potentiometric Titration using 1 /,. O normal potassium bromate solution in hydrochloric acid solution in the presence used by some potassium bromide.

To see if there is a saline solution that only two-valued Contains iron on metallic. copper is without influence, the procedure was that an artificially produced ferrous brine by boiling with suspended Flower wire in a flask with a Bunsen valve for the purpose of reducing the iron to bivalent was treated. After removing the flower wire and continuing to cook, in order to exclude atmospheric oxygen, bare copper was introduced first and then Cooked further in the absence of air. After pouring off, the solution settled in the copper chips .not detect copper with any of the known reagents.

As far as the results of the investigations are concerned, the following information must be given: A factory brine which was examined in June contained 6 mg of copper per liter, while an industrial brine which was examined in July contained 4m9 copper in a liter. Both times the samples were taken at the outlet of the preheater, while the brine at the inlet was not examined at that time because the copper-dissolving effect was well known. and at first it was just a matter of gaining comparative figures at all. After installing the iron filter, the brine was repeatedly examined at the inlet and outlet of the preheater. This found z. B. in September d. J. a content of 1.5 mg at the inlet and 2.5 mg at the outlet, in October at the inlet a content of r.2 mg and at the outlet of 45 mg copper per liter. The iron chip filter was then improved by increasing the iron surface, and the samples then taken in November showed a content of 0.7 mg copper per liter at the inlet and 0.8 mg copper per liter at the outlet, so that is therefore proven that once the copper content has decreased to imperceptible traces and that there was no longer any increase within the preheater.

The operational observations are consistent with this. While in front of your Installation of the iron chip filter almost every week, individual pipes due to destruction had to be replaced, these replacements have been made since the Iron filter completely stopped.

The effectiveness of the iron filter for reduction results from the following potentiometric determinations of divalent iron. They were at the same time three samples taken: at the entrance of the iron filter, between the iron filter and the preheater, and behind the preheater. On entry into the iron filter, 1.25 ccm became 1/10 normal potassium bromate solution for roo ccm of brine consumed, between iron filters and preheater 5.25 ccm and behind the preheater also 5.25 ccm. It surrenders from the fact that only a little bivalent iron is present when entering the iron filter was that through the action of the iron filter its amount had been approximately quadrupled is and that within the fore, the poorer the amount of divalent iron has not changed, in other words that .within. .of the preheater a dissolving Effect on the copper could not have taken place.

Claims (1)

PATENT CLAIM: Preheater for brine and the like, characterized by an upstream filter, which is a means of reducing the amount contained in the brine contains trivalent iron, e.g. B. copper waste, iron turnings or the like.