DE2215065B2 - Process for removing sulfur or chlorine compounds from dust or flue gases - Google Patents

Description

The invention relates to a method for removing sulfur or chlorine compounds from dust or smoke gases by adding chemical compounds in powder form or from dust gases of higher temperature than suspension and separation of the solid sulfur or formed Chlorine compounds.

In flue or dust gases, in special cases, gaseous or vaporous sulfur or Contain chlorine compounds that are harmful to the environment and therefore have to be removed from the gases are. that they no longer flow into the open air with the clean gases.

It is already known to use flue gases containing sulfur or chlorine compounds, e.g. B. contain sulfur dioxide, to supply chemical substances (additives) that chemically bind the sulfur dioxide in such a way that the resulting Compounds are not or only partially soluble in water and therefore in suitable places can be deposited without adversely affecting the groundwater. It is this has already been proposed, the flue gases from z. B. with oil-fired power plants already in the boiler combustion chamber supply calcium compounds in front of electric filters or wet cleaning systems, sprayed into the combustion gases in powder form or as a suspension.

In practice it has been shown (see the journal "Chemieingenieurtechnik", 1972, Issues 1 and 2, essay A. M. Squires) that by the aforementioned Measures only a very small percentage of sulfur or chlorine compounds of the smoke or Dust gas can be cleaned out, which is essentially due to the fact that the time to bind sulfur and chlorine to the chemical additive is relatively short, or that, if higher degrees of desulfurization are to be achieved, then the effort is uneconomical, with also very large excess amounts of additive substances have to be added, most of them as Veilust must be considered. The low desulphurisation effect is largely due to electrostatic precipitators or wet cleaning systems with the addition of chemical additives also due to the fact that the too cleaning gas can pass through such systems without being divided into many small partial flows.

ίο The object of the invention is now to the The sulfur or chlorine compounds contained in the gases to be purified have sufficient opportunity to Reaction of the sulfur or sulfur dioxide or the chlorine ions with the chemical to be added To give additive and thereby add additives to the gases to be controlled and to lead in such a way that none or only extremely low losses of additives occur that are not related to the sulfur or chlorine of the in the sulfur or chlorine compounds contained in the gases to be cleaned react.

This object is achieved according to the invention in that the separation of the fixed connections by means of Bag or bag filters are carried out, whereby the dust filtered out in the filter enters the filter in quantities of

the order of magnitude of 2 to 100 times the amount of dust that arrives per unit of time and is to be filtered The amount of fine dust contained in the gas is removed and the dust gas to be cleaned up in front of or in the filter is fed back, and the filter an accumulating

The amount of dust that is taken is that of the amount of dust gas to be cleaned that arrives per unit of time Dust corresponds, and that the supply of chemical compounds together with that in the cycle the filter is constantly fed dust.

It is understandable that by using bag or bag filter systems with dust recirculation in the cycle according to an older proposal, the addition of additives to a special one simple process and a particularly simple system leads to the sulfur or the chlorine the sulfur or chlorine compounds contained in the flue or dust gas completely or almost completely to react completely to solid nitrable substances without major losses of additives

step. - ■■ ■ "■ '" ■ "

This combination of process steps wi'-d in a particularly simple and economical way created the possibility of the sulfur or the chlorine of the im to be cleaned. Gas containing sulfur

Free or chlorine compounds to any degree or completely or almost completely to the Binding additive. By using a bag or bag filter, the incoming, gas flow to be cleaned is divided into many tiny partial flows, so that the probability the meeting of the sulfur or chlorine compounds contained in the gas to be cleaned with the powdery additives is increased very much. The additives can also be used as a suspension Gas flow are added when the gas to be cleaned has higher temperatures, as then the water the suspension in the filter can evaporate, while the additive remains as a powder. Above all Things, however, it is now possible to add any excess of the gas to be cleaned without or with almost no losses or adding only as many additives as normal for binding the sulfur or Chlorine in the incoming per unit of time, too

215

065

cleaning gas is required. but still for the chemical. Reaction an arbitrarily large amount of shots on additives, because they don't Additives leading to the reaction are also returned to the filter with the dust recirculation, so that there is any desired excess of additives that is capable of reducing the sulfur or chlorine compounds in the gas to be cleaned completely or almost completely with the additive to react. In case the time for the sulfur and chlorine compounds to react with the additive is not sufficient, it is naturally possible to reduce the number of circuits for the return of the in the filter to increase any dust and additives that occur when cleaning the filter surfaces.

The combined process steps, namely the desired number of cycles for dust recirculation for pocket or bag filters and the supply of additives thus results in the possibility of using the Additives with only very low losses to react with the contained in the flue gases or the like.

Tenen sulfur or chlorine compounds to force, whereby it is also possible to use the additives continuously or intermittently add the gas to be cleaned.

For the reaction of the sulfur or chlorine in the Sulfur or chlorine compounds of the smoke or dust gas to be cleaned or the one in these gases containing sulfur dioxide and / or chlorine ions with the powder or as a suspension

ίο the additives to be added to the cleaning gas above all oxides or hydroxyls of alkali metals, alkaline earth metals, aluminum or others chemical substances used in conjunction with the sulfur or chlorine contained in the dust gas Sulfur or chlorine compounds to produce solid substances react. For example, as a dry powder or as a suspension, for. B. Calcium Oxide (Burnt Lime), calcium hydroxide, sodium hydroxide, potassium hydroxide, dolomite (calcium magnesium carbonate), Magnesium (semi-burnt dolomite) is used as an additive.

Claims (1)

Claim: Process for removing sulfur or chlorine compounds from dust or flue gases by adding chemical compounds in powder form or in the case of dust gases of higher Temperature as a suspension and separation of the solid sulfur or chlorine compounds formed, characterized in that the separation of the fixed connections by means of pocket or bag filters, the dust filtered out in the filter being transferred to the filter in quantities of the order of magnitude of 2 to 100 times the amount of dust arriving per unit of time, The amount of fine dust contained in the gas to be filtered is removed and the dust gas to be cleaned is constantly fed back in front of or in the filter and an accumulating amount of dust is removed from the filter the amount of dust arriving in the dust gas to be cleaned per unit of time corresponds, and that the supply of chemical compounds together with the dust constantly to be supplied to the filter in the circuit he follows.