DK148914B - SUBSTANCES FOR THE REMOVAL OF HARMFUL SUBSTANCES, ISAER H2S, SO2, HCN, NOX, HF, HCL, PHENOL, FORMAL HYDROGEN AND LIKE, FROM GASES - Google Patents

Description

14891A

in Island

The present invention relates to a sorbent for removing harmful substances, in particular H2S, SO2, HCN, Ν0Ν, HF, HCl, phenol, formaldehyde and the like, from gases contacted with the sorbent.

According to a proposal from the applicant, which is not yet known in the prior art, such harmful substances can be removed from gases with alkali metal and / or alkaline earth metal compounds which are present as dusty, reactive and possibly milled masses, the blowing agent is blown into a gas stream, brought into contact with the gas and the harmful substances and then removed from the gas again. For this purpose tubular ducts with venturi-like inserts can be used in which intensive contact between the sorbent and the gas and the harmful substances contained therein takes place. After a relatively short stretch of pipe, the sorbent can be removed from the gas stream. This method is suitable in itself, but it is the object of the present invention to provide a sorbent having improved sorption properties which are available in large quantities and are economically advantageous.

This object is met with a sorbent of the kind described in the preamble, which sorbent contains a dust formed by a technical process which contains at least iron III oxide and alkali metal oxides and / or alkaline earth metal oxides, and which sorbent is characterized in that: a dust formed by iron or steel production, stirred to a suspension, is applied to the inflated perlite as a carrier.

30 A dust of the kind specified above is formed by iron or steel production in relatively large quantities. Due to its alkaline properties, this dust is excellent for removing harmful substances from gases. In the table below, quantitative 35 analysis values for three different dust samples were taken, which at different times were taken from dust removal systems in 2 148914

ISLAND

Steel:

Composition Sample no.

% by weight _ 12 3_ 5 Glow loss 6.07 2.38 3.02

SiO2 1.97 1.04 0.93

Fe203 48.88 42.50 33.42 A1203 0.00 0.50 0.20

CaO 28.75 23.20 24.34 MgO 3.70 6.25 4.02

Na20 3.80 2.80 2.45 K20 0.71 1.43 1.02

Pb - 1.04 1.62 V - 0.50 0.80 Ni - 0.08 0.12 P205 - 1.28 2.14 SO3 1.54 4.58 16.33

Zn 0.00 3.25 1.68 2o When, in a special case, a higher alkalinity of the dust is desired, calcium hydroxide and / or white fine lime can also be added. Furthermore, the adsorption capacity of the dust can be enhanced by the addition of ant ore and / or heavy metal salts.

25 Depending on the apparatus available for removing the harmful substances from the gases, the dust may be used in natural or pellet form.

Furthermore, the dust can be used dry or moist, whereby the metal particles in the dust in the latter case form 30 hydroxides which have highly active properties for the quantitative binding of harmful substances, especially H2S, HCN, NOx and SO2.

If aluminum is present, this will, due to the amphoteric properties under alkaline conditions, dissolve as an aluminate complex, but may also dissolve some of the harmful substances.

3

1489U

island

According to the invention, the particularly advantageous properties are that the sorbent is applied to the inflated perlite as a carrier. For this purpose, the sorbent or dust is stirred together with water for a sprayable suspension which is applied or sprayed onto the perlite in a mixer.

Inflated perlite as a carrier, in particular by dry adsorption, offers a number of advantages: its low density allows large amounts of the suspension to be deposited on the carrier without significantly adversely affecting the flight properties of the particles in the air or gas stream to be purified. The irregular shape of the pearlite corners and the large surface ensure a good adhesion and create favorable conditions for the regeneration of -used sorbent.

Perlite is chemically neutral, non-combustible and free of 15 organic impurities. In addition, perlite can withstand moisture impacts. Furthermore, since the pore structure of the inflated perlite allows a high water absorption, namely up to 70%, the perlite can also be wetted to thereby improve, as already explained above, the adsorption properties of the sorbent.

For the wetting, water or also sodium hydroxide solution may be used which simultaneously increases the alkalinity of the sorbent.

The inflated pearl's high sintering temperature of approx. 1000 ° C and high thermal softening temperature of approx.

25 1220-1320 ° C also works favorably, so that it is also possible to apply the sorbent applied to such a carrier to purify very hot gases, e.g. from high-pressure coal gasification or from waste incineration, which gases have temperatures up to 750 ° C 30 or even higher.

The high temperature resistance of inflated perl also has a favorable effect on the regeneration of spent sorbent.

Roasting of used sorbent produces SO2-containing rice gases which can be converted into sulfuric acid in a Claus plant or by wet catalysis. The perlite is retained and can be cooled by spraying water and re-energized when · roasting temperature does not exceed 300 ° C, because at higher temperature the recovery of iron IIl hydroxide is no longer possible.

The carrier perlite is also retained by sulfur recovery 5 by extracting the spent and with air to iron III hydroxide and sulfur genomide sorbents by means of ammonium polysulfide or carbon disulphide, as perlite is not soluble in organic solvents.

Finally, it does not present any difficulty in depositing the spent sorbent after absorption of the harmful substances together with the carrier, namely perlite, as little space is needed for this. Namely, inflated perlite can be compressed to 1/10 of the original volume, thereby binding all the absorbed harmful substances.

The present sorbent is sufficiently alkaline to regulate the adsorption of harmful substances under stable conditions. The presence of bases also allows regeneration or further processing of the sorbents e.g. by roasting and wetting, thereby ensuring a rapid genome formation of the iron constituents for iron III hydroxide.

The present sorbent can be used both dry and moist in the most diverse methods and apparatus by which harmful substances are removed from gases by adsorption.