DE3326826A1 - Process for immobilising at least a part of the sulphur present in bituminous coal or mixtures of bituminous coal and lignite - Google Patents

Abstract

To reduce the emissions of sulphur dioxide in the combustion of pulverised bituminous coal and mixtures of pulverised bituminous coal and pulverised lignite, these are provided during production with a defined proportion of sulphur-binding substances, preferably CaO and/or MgO or compounds which release CaO and/or MgO at elevated temperatures, in such a way that sulphur-binding substances are admixed to the coal for use in small combustion installations. The operators of such combustion installations thus do not have to take any special precautions for reducing the emission of sulphur dioxide. In particular, it is not necessary to provide the combustion installations with additional equipment for feeding sulphur-binding substances into the combustion chamber.

Description

Method for integrating at least part of the

rock composed of hard coal or mixtures of hard coal and lignite The invention relates to a method for integrating at least one Part of the sulfur found in hard coal or mixtures of hard coal and lignite is present, in the solid combustion residues of the same by admixing sulfur-binding substances, preferably CaO and / or MgO or at higher temperatures CaO and / or MqO releasing compounds.

It is known, for example, in the incineration plants of large power plants the coal to be burned, especially brown coal, before the task on the under Use of the boiler exhaust gas operated grinding-drying plant calcium carbonate or Mix the calcium oxyhydrate with the heat and grind it to dust with the charcoal. The resulting The mixture is then blown into the furnace of the boiler.

The following chemical reactions take place, for example: 1. CaCO3 CaO + CO2 d. This means that calcium carbonate CaC03 becomes burnt with the release of CO2 Lime CaO reduced.

The quick lime then combines with that of the incineration process sulfur dioxide produced; the implementation to plaster of paris takes place according to the following Equations: 2. CaO + SO2 CaS03 and 3. CaS03 + 1/2 02 CaSO4 According to the position of the chemical Equal weights and the chemical kinetics are at least an essential part of the sulfur originally bound in coal in the form of gypsum; he is Part of the solid combustion residues, i.e. the ash that is in the usual way can be deposited. The SO2 emissions from power plants can be significantly reduced using this method.

Part of the pollution caused by SO2 is due to emissions from small fire systems in which coal dust is burned. Here are no facilities for adding sulfur-binding substances and generally not applicable for economic and spatial reasons. The sulfur dioxide that forms in this process is thus released into the atmosphere, as far as the Ash from the coal does not contain components that also contain sulfur dioxide, e.g. B. with the formation of sulfates. It can be assumed that throughout the basic ash constituents of SteXiohlen only in sub-stoichiometric quantities are present, so that even in the presence of these favorable circumstances only a part of the sulfur dioxide is bound in the solid combustion residues.

The aim of the invention is therefore to also apply to small firing systems to enable a reduction in the emission of sulfur dioxide. You are the one The underlying task is to further develop the method described in the introduction and To pretreat coal so that also with Small combustion systems at least a large part of the sulfur dioxide formed during combustion in the solid Combustion residues is incorporated.

To solve this task, the invention proposes that hard coal and optionally lignite and sulfur-binding substance mixed with one another in this way that the sulfur-binding substance in the resulting mixture in finely divided Form.

The operator of the furnace does not need any special equipment and to take measures to at least noticeably reduce SO2 emissions. Rather, the coal is essentially in the form suitable in each case for combustion as fine-grain coal or dust, already as part of a for the achievement the mixture required for the desired effect.

Hard coal and qeq also lignite as well as sulfur-binding substance can first be crushed to approximately the same grain size and then together be mixed. But there is also the possibility of using hard coal and if necessary Lignite and sulfur-binding substance when mixed with one another at the same time to be ground as fine as dust. Good mixing is inevitably ensured here.

While it will normally be difficult to determine the amount of sulfur-binding Substance taking into account only the stoichiometric conditions Select. However, the stoichiometric excess of the sulfur-binding substances becomes the more finely grained these substances are, the smaller they can be. It is assumed that that these substances as possible evenly within the fuel, for example of the dust. It can be assumed that one - theoretically -quantitative conversion of the sulfur in the coal about the two - up to four times the stoichiometric amount of sulfur-binding substances is required. The theoretically calculated amount of sulfur-binding substances to be added could possibly be reduced by the amount of such substances that is present in the ash from the start. The latter will in particular then come into question if the coal is a mixture of hard coal and Lignite trades. In general it can be assumed that the ashes of most hard coals acidic and thus for the involvement of the combustion forming SO2 is not suitable, whereas many brown coals have ash, which contains CaO and comparable compounds that bind SO2 with sulfate formation can and cause the basic character of the ashes.

A mixture of hard coal and brown coal can therefore also be cheap because a lot of brown coals, for example that of the Rhenish mining district, generally have one have relatively low sulfur content volweniqer than 0.5 wt .-% (wf), the also to a noticeable extent due to the presence in the ashes of this lignite basic substances is bound. The mixing ratio between brown coal and hard coal could, for example, depending on the permissible emission, the sulfur content of the coal and the addition of additional sulfur-binding agents Substances are chosen. Additions of, for example, CaO in the order of magnitude from 5 to 10% is quite possible, especially in the case of mixtures of lignite and hard coal practicable, as on the one hand extensive integration of the sulfur is possible, on the other hand, admixtures of inorganic constituents in this order of magnitude does not noticeably affect the burning properties of the coal mixture

Claims (1)

Claims 1. Method for integrating at least one part of sulfur, which is present in hard coal or mixtures of hard coal and lignite is, in the solid combustion residues of the same by adding sulfur-binding Substances, preferably CaO and / or MqO or at higher temperatures CaO and / or MqO-releasing compounds, characterized in that hard coal and qeqebenenfalis Lignite and sulfur-binding substance are mixed with one another in such a way that the Substance in the resulting mixture is in finely divided form. -2. Method according to claim 1, characterized in that hard coal and possibly lignite and sulfur-binding substance at the same time Mixture with each other to be ground to a fine dust.