Gas-pu′ri-fier.
An apparatus in which gas is purified of its sulphur compounds.The purification of gas by passing it through limewater is the invention of Mr. Clegg, England, and was introduced in 1807.
The ordinary illuminating gas, after having been evolved in the retort, its tar eliminated in the condenser, and its ammonia abstracted in the washer, is passed through the purifier, whose duty is to remove the sulphur and render the gas fit for consumption.
The wet-lime purifier has several chambers containing a certain depth of cream of lime. The gas passes through each chamber in succession, bubbling up through the liquid, the contact being rendered more intimate by arms which rotate in the spaces through which the gas passes in flowing from one chamber to another. The arms also stir up the lime and prevent its settling.
The cream of lime absorbs the sulphureted hydrogen and carbonic acid, the water absorbs the remaining ammonia.
This process has been generally abandoned on account of the difficulty of disposing of the foul cream of lime known as “blue billy.”
In the dry-lime process slightly moist hydrate of lime is placed on trays, or iron boxes, through which the gas is made to pass. This process is very effective, and has very generally superseded the wetlime process. It removes the sulphur compounds and the carbonic acid equally well. When the foul lime is removed, however, it evolves the same odor of sulphide of ammonium which caused the wet-lime process to be abandoned. The suppression of this offensive odor has been effected by washing and special purification. The dry-lime meter has been generally abandoned in Europe, however, as was the wet-lime process previously.
The Laming process, now used in Paris, and generally over the continent of Europe, was introduced in 1849. The hydrated sesquioxide of iron forms a substitute for the lime. It is prepared of a [954] suitable quality by mixing copperas (sulphate of iron) with slacked lime and sawdust, and exposing the mixture to the air to oxidize the protoxide of iron to the sesquioxide. The resulting mixture contains hydrated sesquioxide of iron, sulphate of lime, and sawdust. When an excess of hydrate of lime is employed, the resulting mixture contains this substance also. This material is very effective in removing the sulphur compounds from the gas, and is not offensive when fouled with sulphur. The latter may be distilled to produce sulphuric acid.
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| Gas-register. |
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| Gas-regulator. |
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| Gas-regulator. |
The iron-ore process of Hill consists in the use of the natural hydrated sesquioxide of iron or bog iron ore, to which is added by the New York Gas-Light Company a quantity of iron borings and turnings moistened by ammoniacal liquor and exposed to the air. To the mixture is added pulverized charcoal. Other ores are used in Germany, where the oxides of iron are used in purification, to the exclusion of all the lime processes.
In some forms of apparatus for the purification of gases which are led through a liquid, a wheel with fans is made to revolve and keep the liquid agitated, while also exposing a large wetted surface to the passing gas.
