Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Sulfur or sulfur containing component
Patent
1986-10-09
1988-11-08
Heller, Gregory A.
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Sulfur or sulfur containing component
423210, 423235, 423240, 423390, 423522, C01B 1700, C01B 2100, B01D 4700, B01J 800
Patent
active
047833262
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for the removal of pollutants from hot gases, in which the gas is cooled and, at a specified temperature, a condensing out of acid is effected and the condensate removed, and in which, after a further cooling, heavy metals are removed with the condensate. The invention relates moreover to a purification plant for carrying out the process.
The invention is concerned in particular with the purification of flue gases. It is known that gases loaded with pollutants which reach the atmosphere represent a considerable pollution of the environment and cause considerable damage. The pollutants come back to earth, in particular along with drops of water, and contaminate the soil so that plants growing on the latter are poisoned or destroyed. This phenomenon is known as "acid rain".
The sulfur content of the exhaust gases, in particular, are held responsible for the acid rain. The desulfurization of flue gases is therefore known and is now stipulated for large furnace plants. For this purpose the gas is scrubbed, as a result of which sulfuric acid at high dilution is produced. Said sulfuric acid is extremely corrosive and handling it therefore presents considerable difficulties.
However, the desulfurization of flue gases has now also been recognized as inadequate. A substantial part of the injurious action of the acid rain is not to be ascribed to the sulfur content, but to the heavy metal content.
A process, described as the KOS process, has become known by which both sulfur dioxide and also heavy metals can be removed from the flue gas. For this purpose the flue gas is cooled, after which sulfuric acid is removed at a temperature above 60.degree.. After a further cooling condensate is removed which contains heavy metals. After a final scrubbing of the gas, it is discharged into the atmosphere.
The KOS process consequently exploits the condensation of the moisture contained in the flue gas to remove pollutants from the flue gas. To facilitate condensation as sulfuric acid, an oxidizing agent in the form of hydrogen peroxide (H.sub.2 O.sub.2) is added to the flue gas before the precipitation of the sulfuric acid. This reinforces the oxidation of SO.sub.2 to SO.sub.3.
The KOS process offers the advantage that a heat recovery can be conducted as a result of the cooling of the flue gases.
In addition, the sulfuric acid produced in the condensation can also be commercially exploited.
The invention therefore relates to an improvement of the known process.
The invention is thus based on the object of developing the purification, mentioned in the introduction, of the hot gases from pollutants in a manner such that the purification takes place with a high efficiency regardless of the composition and the state of the hot gases.
This object is achieved according to the invention by a process wherein the moisture content of the hot gas is adjusted to a fixed value on entering the purification plant, wherein a controlled, step-wise cooling to various temperatures is undertaken at each of which a precipitation of condensate is undertaken, and wherein the particular precipitation takes place in each case slightly below the dew point of the particular acid formed by exhaust gas constituents with the condensate.
The invention is based on the discovery that it is important for the operation of the purification process that a relatively precisely defined quantity of water is present in the flue gas. If said quantity of water is not present, the efficiency of the purification drops considerably. It has emerged that, for the purification of flue gases which are introduced into the purification plant at a temperature of over 110.degree. C. , a water content of 100 g/m.sup.3 - 15/+20 g/m.sup.3 is ideal. With this water content an adequate quantity of condensate is produced for the formation of the acid, and on the other hand the latter is not too greatly diluted as a result of too much water. As a result of the regulation of the moisture content of the hot gases it is possible to precipitate a multiplici
REFERENCES:
patent: 3953578 (1976-04-01), Thirion
patent: 4048287 (1977-09-01), Kelleher et al.
patent: 4454100 (1984-06-01), Faatz
patent: 4617180 (1986-10-01), Vogg
ERA GmbH
Heller Gregory A.
LandOfFree
Process for the removal of pollutants from hot gases does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the removal of pollutants from hot gases, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the removal of pollutants from hot gases will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-463215