MX2008001907A - Method and device for removing volatile organic components from waste gases of a clinker installation - Google Patents

Abstract

The invention relates to a method for removing volatile organic components (VOC) from waste gases of a clinker installation, according to which the largely cooled waste gases are subjected to post-combustion which is carried out in such a way as to ensure a reduction of the concentration of the VOC below the authorised threshold values. The post-combustion is carried out in order to produce water vapour for a gas volume to be burned, ensuring that a partial quantity of the waste gas corresponding to the gas volume enables the reduction of VOC in the waste gas, emitted in the time unit, below the authorised concentration values, by rarefaction. Said partial quantity is simultaneously used for the production of a quantity of water vapour sufficient for the economical operation of a determined steam turbine. The invention also relates to a device for carrying out said method, characterised in that a branch line is connected to the waste gas line of the clinker installation, between a preheater and the waste gas suction fan, a combustion chamber for a heat exchanger for producing water vapour and a stream turbine being connected to said branch line.

Description

METHOD AND DEVICE FOR REMOVING COMPONENTS ORGANITIES VOLATILES OF DISPOSAL GASES OF AN INSTALLATION FOR CLINKER The invention relates to a method and device for removing volatile organic compounds (VOCs) from waste gases from a clinker installation, where excessively cooled waste gases are subjected to afterburning.

Document DE 101 46 418 A1 shows and describes a method in which volatile organic compounds (VOCs) are removed by combustion. In the production of hydraulic cement clinker from pure cement powder, it is possible to use raw material, which not only contains sulfides and therefore can lead to sulfur contamination of waste gases, but also shows an increase in the content of TOC (total organic carbon). In modern installations for clinker, pure powder is preheated in multistage preheater and in particular in cyclonic stages of a line of heat exchangers, so that pure powder remains afloat in the cyclonic stages. To this end, the waste hot gas is extracted from the rotary kiln and is conducted through the cyclonic stages, whereby the hot waste gases are cooled in the individual stages and in return the pure powder fed is heated. In particular in the upper cyclonic stages for a respective pure powder with Increased content of TOC A considerable fraction of volatile organic compounds or VOCs can be expelled and subsequently reach uncontrolled waste gases without burning. Document DE 101 46 418 Al has proposed to install an oxidation zone in the waste gas line that descends to the line of heat exchangers in the direction of the gas stream, where the waste gas is forced to pass to the waste gas line. through the open flame and therefore oxidizes effectively. Such a device implies that the gases, which are already considerably cold at this point and that are mostly burnt except for the volatile organic components, are heated again at temperatures ranging from 300 ° C to 900 ° C, for ensure the combustion of volatile organic compounds. As in other concepts, even all the process gas that includes water vapor and leakage air has to be heated from plus or minus 100 ° C to 900 ° C after pure powder grinding. As in this arrangement all the volume of gas extracted from the rotary kiln has to be heated again, it requires a large input of energy, so that the hot waste gas produced can be used again only for preheating needs, for example in a dry grinding installation.

The latent heat of hot gases can be used naturally in different ways. In the gas turbines and in particular steam turbines for the operation of electric generators, the production of hot waste gases for the production of superheated steam in heat exchangers has to be planned precisely, since said steam turbines They ask for a definite stream of water vapor for efficient operation. In order to protect a corresponding economic efficiency, a large quantity of hot combustion gases must be supplied, in a manner equal to that normally achieved by direct combustion only with high quality fuels. The only heating of large quantities of gas, which only has a very low calorific value, would have to be classified largely as expensive, since until now the latent heat that accumulates in a more or less uncontrolled form dissipated.

The object of the invention is to use the advantages of energy recovery in a steam turbine together with a corresponding reduction of the VOCs in the waste gas. For this purpose, according to the method of invention, it is proceeded in such a way that an afterburning is carried out in a measure that guarantees a reduction of the concentration of the VOC below the acceptable threshold values and that the post-combustion is carried out for the production of steam, so the production is determined in a volume of gas that is going to be burned later, ensuring that a The partial quantity of the waste gas corresponding to the volume of gas allows the reduction of VOC emitted per unit of time in the waste gas below the acceptable values of concentration by rarefaction and therefore this partial quantity is determined simultaneously for the production of waste gas. a sufficient amount of steam for the economic operation of a given steam turbine. Due to the fact that for the economic operation of a certain steam turbine, exact parameters must be maintained, according to the invention a determination corresponding to the correlated totals is conceived. Therefore, the steam turbine is not designed for complete heating of the total amount of waste gas from the rotary kiln, since this amounts to an unnecessary heating of large quantities of more or less inert gases and therefore would only show an efficiency marginal economic According to the invention, the steam turbine is determined in such a way that quantities smaller than the total amount of waste gas are sufficient, so that again the limiting value is chosen, so that the partial amount is derived of the waste gas stream, which protects in each case, that after the complete combustion of the volatile components in this partial amount the total amount of VOCs subsequently emitted per unit of time remains below of legally acceptable concentration values. The fact that the total amount of most inert gases does not have to be reheated for steam production in order to reduce the VOC content, increases the economic efficiency of the method considerably, since it is now sufficient to heat exactly the amount of more or less inert gases, whose heating, in turn, results in the consumption of exactly the amount of VOCs, which in total produce the release of an acceptable amount of VOCs per unit of time. Simultaneously this partial quantity is adjusted optimally to the requirements of the consecutive steam turbine, so that in total an economic method can be achieved.

The device according to the invention for removing volatile organic components from waste gases from a hydraulic cement clinker kiln installation, where the very cold waste gases are subjected to afterburning, is generally characterized in that a Derivative line is connected to the waste gas line of the hydraulic cement clinker furnace installation, between the precalcination furnace and the waste gas suction fan, where a combustion chamber is connected to the bypass line. heat exchanger for the production of steam and a steam turbine. Preheater in clinker installations Modern hydraulic cement as already mentioned, are designed as cyclonic / fluidized-bed heat exchangers, and in most cases, a plurality of such cyclones are connected in series in order to form a line of heat exchangers . The temperature of the hot gases extracted from the hydraulic cement clinker furnace is reduced incrementally by means of the present, so that the derivative line corresponding to the pressure drops in the individual stages of the heat exchanger line does not necessarily it has to be connected to the last heat exchanger, but rather allows an outward transfer to an already higher temperature level. The temperature level in any case is selected so that it can be assumed that at the lower temperatures a combustion of VOCs stops and on the contrary a release of VOCs is possible without difficulty. Strictly speaking, this applies to temperatures of < 300 ° C and in most cases corresponds to the temperature of the waste gases at the entrance of the pure powder preheater.

A feedback of the amount of gas leaving the heat exchanger for the production of steam can preferably be carried out in the pure powder pulverizer mill or in the grinding facility dry. The device in this way is preferably conceived as the placement of the derivative line between the preheater and a pure powder pulverizer mill.

Through the device according to the invention in total, the advantage is achieved that this can be done without a full expensive afterburning and simultaneously the energy used for the post-combustion can be used optimally for the production of steam and for the steam relaxation in a steam turbine. Thus, the latent heat of gases heated to correspondingly high temperatures of up to 900 ° C for the combustion of VOCs is best utilized so that the economic efficiency of the whole method is increased.

Claims (3)

1. Method to remove volatile organic compounds (VOCs) from waste gases from a hydraulic cement clinker kilns installation where the highly cooled waste gases are subjected to afterburning, which is characterized in that afterburning takes place in a measure that ensures a reduction of the concentration of VOCs below the acceptable threshold values and that the post-combustion is made for the production of steam, so that the production of steam in the post-combustion is determined in a volume of gas that is going to burn later, ensuring that a partial amount of the waste gas corresponding to the volume of gas allows the reduction of VOC emitted per unit time in the waste gas below the acceptable concentration values by rarefaction and therefore this partial quantity is determined at the same time for the production of a sufficient amount of steam for the economic operation of one of finished steam turbine.

2. Device for removing volatile organic components (VOC) from waste gases from a hydraulic cement clinker kiln installation, where the highly cooled waste gases are subjected to an afterburning, characterized in that the derivative line is connected to the waste gas line from the installation of hydraulic cement clinker kilns, between the precalciner and the waste gas suction fan, where a by-line is connected to a combustion chamber for a heat exchanger for the production of steam and a steam turbine.

3. Device according to claim 2, characterized in that the derivative line is placed between the preheater and a pure powder pulverizer mill. SUMMARY OF THE INVENTION Method and device to remove volatile organic components from waste gases from a clinker installation In a method to remove volatile organic compounds (VOCs) from waste gases from a hydraulic cement clinker kiln installation, where excessively cooled waste gases are subjected to afterburning, afterburning is carried out to a degree that ensures reduction of the VOC concentration below the acceptable threshold values. The post-combustion is done for the production of steam, so the production of steam in the post-combustion is determined in a volume of gas that is going to be burned later, ensuring that a partial amount of the waste gas that corresponds to the volume of gas allows the reduction of the VOCs emitted per unit of time in the waste gas below the acceptable values of concentration by thinning and for which this partial quantity is determined simultaneously for the production of a quantity of steam sufficient for the economic operation of a certain steam turbine. The device for carrying out the method is characterized in that a derivative line is connected to the waste gas line of the hydraulic cement clinker kiln installation, between the precalciner and the suction fan. of waste gases, where the derivative line is connected to a combustion chamber for a heat exchanger for steam production and a steam turbine. The invention also concerns a device for carrying out the method, characterized in that a derivative line is connected to the waste gas line of the clinker installation, between a preheater and the exhaust gas fan, a combustion chamber for a heat exchanger to produce water vapor and a steam turbine that connects to the derived line.