The present invention relates to an apparatus for removing volatile components, such as chloride, alkali and sulphur, from exhaust gases in a cement manufacturing plant, which plant comprises a preheater for preheating cement raw materials, a kiln for burning cement clinker, and a transition zone between the preheater and the kiln, said apparatus comprising a cooled condensation body having an outer surface temperature which is lower than the condensation temperature of the volatile components and being placed into the exhaust gases at a location where the temperature of the exhaust gases exceeds the mentioned condensation temperature so that volatile components when brought into contact with the condensation body are cooled to a level below their condensation temperature and are thereby condensed and deposited on the condensation body.

An apparatus of the aforementioned kind is known from DK 176861 . This known apparatus which is used to reduce the quantity of volatile components, such as chloride, alkali and sulphur which have been introduced to a cement manufacturing plant together with the cement raw materials and the fuel, and which circulate in the kiln system of the plant, with potential to cause clogging and unsteady kiln operation, operate, briefly described, according to a principle where the condensation body is alternately introduced into the exhaust gases for collecting volatile components by condensation and deposition of such volatile components on the condensation body and taken out from the exhaust gases for cleaning of deposited condensation products. First of all, in order to avoid false air to enter the plant this known apparatus would require an airtight compartment located outside the location where the condensation body is placed into the exhaust gases and fully enclosing the condensation body and/or the opening through which it is introduced into the exhaust gases and taken out for cleaning.

In addition, by some of the shown embodiments the cleaning procedure involves an interruption of the gas cleaning process, which of course reduces the overall cleaning capacity of the known cleaning equipment.

It is the object of the present invention to provide an apparatus for removing volatile components from a cement manufacturing plant by means of which the aforementioned disadvantages are eliminated or significantly reduced.

According to the invention this is achieved by an apparatus of the kind mentioned in the introduction, and being characterized in that means for cleaning the condensation body is constantly located inside the plant accommodating the exhaust gases to be cleaned.

It is hereby obtained that the cleaning procedure of the condensation body may take place inside the plant, thus an airtight compartment may be omitted, and essential without any interruption.

The condensation body may in principle have any appropriate form, however, it is preferred that it have the form of an elongated bar shaped body, which extends into the exhaust gases to be cleaned from a wall of the plant. Such elongated bar may have a cross section of any appropriate form, such as polygonal, however, it is preferred that it has a circular cross section.

The means for cleaning the condensation body may be means allowing relative movement of sections of the condensation body itself, however, as such a solution suffers from a high risk of failing because of the dusty environment may probably cause interlocking of neighbouring sections. Thus, it is preferred that the means for cleaning the condensation body comprises a stationary elongated scraper bar having essentially the same length as the condensation body and being positioned in close vicinity to the latter. In such embodiment, a relative movement between the condensation body and the stationary elongated scarper bar would cause the deposited layer of condensation product to crack and fall off the condensation body, and it is therefore preferred that the condensation body comprises rotation means for rotating it about its centre line. Only a minor angular rotation of a few degrees, i.e. 1 to 5 degrees, should be enough to ensure cracking and falling off of the condensation products.

In an alternative embodiment, the means for cleaning the condensation body may comprise a thin mantle enveloping the condensation body in tight relation and having a longitudinal slit allowing the mantle to expand, and means for providing such expansion of the mantle, which e.g. may be a lever having an oval cross section and being arranged in the said slit. Some condensation products, such as alkali and sulphur, may be allowed to fall down into the kiln, thus being included in the produced cement clinker. However, condensation products such as chloride would evaporate if allowed to fall down into the kiln and should therefore be removed from the plant. For this purpose the apparatus may comprise a hopper arranged below the condensation body and a sluice, e.g. a wheel sluice, being in communication with the hopper for sluicing out the condensation products.

The invention will now be explained in further details with reference to the drawing, being diagrammatical, and where

Fig. 1 shows a sectional view of a cement manufacturing plant viewed from the side which comprises an apparatus according to the present invention for removing volatile components , and Fig. 2 shows details of the apparatus according to the invention, and

Fig. 3 shows details of an alternative embodiment of the apparatus according to the invention. In Fig. 1 is seen a sectional view of a plant for manufacturing cement clinker, which plant comprises a preheater 1 for preheating cement raw materials, a rotary kiln 5 in which cement raw materials in counter flow to hot kiln exhaust gases are burned into cement clinker, as well as a transition zone 3 in the form of a riser duct for diverting exhaust gases from the rotary kiln 5 and onward to the preheater 1 . The shown plant further comprises an apparatus 7 according to the invention for removing volatile components, such as chloride, alkali and sulphur, from the cement manufacturing plant, which apparatus 7, in the shown embodiment, is arranged in the transition zone 3 where the temperature of the exhaust gases exceeds the condensation temperature of the volatile components, and comprising a condensation body 9.

In the embodiments shown in Fig. 2 and 3 the condensation body 9 comprises an elongated bar 9 having a circular cross section and extending into the exhaust gases to be cleaned from a wall 10 of the transition zone 3.

According to the invention means for cleaning the elongated bar 9 is constantly located inside the transition zone 3 accommodating the exhaust gases to be cleaned, thus an airtight compartment located outside the transition zone 3 may be omitted.

In the embodiment shown in Fig. 2 the means for cleaning the elongated bar 9 comprises a stationary elongated scraper bar 1 1 having essentially the same length as the elongated bar 9 and being positioned in close vicinity to the latter. In this embodiment, the elongated bar 9 is connected to rotation means 12 enabling the elongated bar 9 to be rotated about its centre line, thus providing relative movement between the elongated bar 9 and the stationary elongated scarper bar 1 1 , thereby causing the deposited layer, indicated in the cross section view A-A by 13, of condensation product to crack and fall off the elongated bar 9. Only a minor angular rotation of a few degrees, i.e. 1 to 5 degrees, should be enough to ensure cracking and falling off of the condensation products. In the alternative embodiment shown in Fig 3, the means for cleaning the elongated bar 9 comprises a thin mantle 14 enveloping the elongated bar 9 in tight relation and having a longitudinal slit 15 allowing the mantle 14 to expand, and a lever 16 having an oval cross section and being arranged in the said slit 15 for providing such expansion of the mantle 14.

Some condensation products, such as alkali and sulphur, may be allowed to fall down into the kiln 5, thus being included in the produced cement clinker. However, condensation products such as chloride would evaporate if allowed to fall down into the kiln 5 and should therefore be removed from the plant. For this purpose the apparatus may comprise a hopper 17 arranged below the elongated bar 9 and a sluice 18, e.g. a wheel sluice, being in communication with the hopper 17 for sluicing out the condensation products, preferably into a silo 19.