US1422008A - Apparatus for purifying coal gas - Google Patents

Description

F. Sonny. APPARATUS FOR PURIFYING COAL GAS.

APPLICATION FILED AUG.5| 1920.

PatentedvJuIy 4, 1922` @E i z mimi mwa@

STATES FREDERICK SODDY, 0F OXFORD, ENGLAND.

APPARATUS FR PURIFYING CQAL GAS.

Specification of Letters Patent.

Patented any a, ieee.

Application led August 6, 1.920. Serial No. 401,696.

To all whom it may cof/106ML.'

Be it known that I, FREDERICK SODDY, a subject of the King of Great Britain, formerly residing in Aberdeen, Scotland, but now residing in Oxford, England, have invented a certain new and useful Improvement in Apparatus for Purifying Coal Gas, of which the following is a specification.

This invention relates to apparatus suitable for applying the process described in my application for United States Letters Patent Serial No. 289,352 dated 11th April 1919.

The general principle involved in the process for which the apparatus is intended, is the continuous travel of charcoal irst through a cool chamber in which it is exposed to the current of gas at ordinary tem-- perature, and then through a heated chamber in which it is cut oil" fromthe gas current, the expelled illuminants being suitably withdrawn. This principle is applied in such a manner that a certain fractionation ofthe illuminants from the non-illuminants is attained, whereby a more concentrated product may be continuously obtained than is possible by known methods of absorbing and recovering.

The invention is illustrated by 4the-accompanying drawing in which Fig. 1 shows in diagrammatic vertical section an4 apparatus for the continuous treatment of LAcoal gas by means of charcoal; Fig. 2 is a diagrammatic sectional elevation of a modified form of the apparatus; Fig. 3 is a cross section on line 7-7 of Fig. 2; Fig. 4 is a vertical section in i a plane at right angles to that of Fig. 2, and Flgs. 5 and 6 are respectively'fsections on lines 9-9 and 10-10 of Fig. 2.

Fig. 1 represents a tower subdivided into two chambers by a Valve e. The upper part e of the upper chamber is the absorber, the lower part e2 (containing heating pipes e5) is the heater, while the lower chamber e3 (containing cooling pipes e6) is the cooler and has a valve e4 atv its lower part.

These valves e, .e4 are of any known type for transferring a solid while checking passage of gas; they need not in this case be completely gas-tight so long as they effectively check gaseous flow. The charcoal descends the tower .by gravity and. is again raised by a conveyor f* working in a gastight casing. The main stream of coal as enters at g and leaves at g', substantia ly stripped by the charcoal descending the and \apou1s,'some of which are withdrawn by ypump L through a condenser h while the rest ascend to join the gas entering at g. The part of the expelled gas so ascending is subjected to the fractionating action hereinbefore mentioned. It consists of the gas expelled 1n the initial stages of the heating of the charcoal, which in passing over successively cooler layers of charcoal is deprived of its excess of illuminants by the charcoal and gains from the charcoal a partv of the non-illuminants previously absorbed by the charcoal before it was heated. The gases withdrawn by the pump k through the condenser L, consist of the part of the' absorbed gases expelled in the later stages of the heating. They consist of the illuminants in the coal-gas in a highl concentrated condition, the removal of w ich from `the coal-gas is the object of the invention.

The gas so removedis the richer in illuminants the less of it that is so withdrawn. The volume withdrawn must not be less than the volume of the total illuminants in the gas passed through and may, in general, be somewhat greater than this volume.

For washing the charcoal descending among the pipes e, stripped gas is withdrawn in determined amount from the top of the tower, passing down the casing of the elevator, by pump z' and is caused to pass through the cooler so as to carry the illuminants'from the charcoal therein (through a condenser if necessary), into the upper chamber at a place above the heating tubes e5. The volume of gas so used for washing may be somewhat greater than, for example,

`from two to four times as great as, the volulne of charcoal passing down the tower. A pump c may withdraw a gas rich in hydrogen from the upper' part of the tower.

TBy this means a small part of the vstripped gas, which otherwise would leave by the exit pipe g', is caused to pass through a relatively large mass of fresh charcoal at ordinary tem'- perature which has not yet absorbed any-gas and, in consequence, the methane and carbonmonoxide are absorbed preferentially and the content in hydrogen of the part not absorbed thereb increased.

It will be un erstood that the washing of the charcoal with stripped gas with the double object of preventing the accumulation in it of the less volatile and more ditlicultly removed constitutents and the recovery of the small and relatively unimportant part of the illuminants it carries along with it inits pores, and also `the withdrawal of a small part of the total gas richer in hydrogen than the main quantity of stripped gas, are subsidiary to and not essential to the main proce whichy can be operated without them. In this case the pump z', condenser z" with their connecting pipes, and the pump k may be dispensed with, andthe exit pipe g taken from the top of the tower.

To construct an-apparatus thus diagrammatically represented, regard must be had to the conditions under which charcoal will flow under gravity. Lumps which will pass through a 1 inch sieve will flow through a pipe of circular cross-section 6 inches in diameter but will bridge in a pipe 4 inches in diameter. It will iiow'through la rectangular 4slot 3 inches wide, butl 4 inches is a safer dimension. Its angle of repose is about 45 and the sides of a hopper through which it- .is to flow without bridging should make an angle of not less than 50 with the horizontal.

Referring now to Figs, 243, the interior of the absorber Z issubdivided by vertical plates Z in planesy at right-angles to each other into elongated cells down which the charcoal descends. The descent is regulated and made uniform over the cross sectional area of the tower b meansv of the grooved rollers m rotated y suitable mechanism. The coal-gas enters the absorber at n and leaves it at o (Fig. 2), consisting essentiallyv of hydrogen, methane, carbon monoxide and nitrogen. To ensure a uniform withdrawal of the gas over the cross sec, tion of the tower, at the plane of the exit o there are lixed in the cells rectangular funnels p and the vertical partitions are perorated at the places which are behind these funnels (Fig. 3). The charcoal descending through the funnels assumes .the angle of repose indicated by dotted lines p', leaving spaces which are all in communication with each other and with the exit o through the said perforations.- A like construction is provided at the ends of the by-pass g referred to below, and the charcoal also takes up its natural angle of repose, indicated by p2. at the line of the exit y.

The charcoal having left the absorber descends the heater which is also of cellular structure, but the cells 1' alternate with heat- 'ing flues 1" divided into an upper and a lower set by horizontal partitions r2. They may in addltion be subdlvided by transverse A partitions in planes parallel to the .paper (F ig. 2). As shown in Fig. 4 heating gases circulate first through the lower heating flues and then through the upper, so that the lower part of the heater is the more strongly heated and the heat is used economically. Having left the heater the charcoal descends through the cooler which is similarly constructed with upper and lower flues for circulation of cooling gases or liquid as indicated in Fig. 4. In passage `through the heater and cooler the relative movement that occurs among the pieces 'of charcoal decreases the time required for heating and cooling the charcoal. At the bottom of the cooler are grooved rollers s to regulate the descent, driven by any suitable mechanism.V From the cooler the charcoal travels through a hoppert, having a suitable device, such as two flaps t', which is so geared to the conveyor u that it permits passage of charcoal only when there is a bucket of the conveyor beneath the discharge opening. For instance, flaps t may assume the position shown each'time a conveyor bucket is beneath the discharge opening of the hopper and may be turned into the position to close the hopv per as soon as the bucket has paed. The

conveyor discharges the charcoal to the ro-l tating bucket valve 'v at thetop of the a'b sorber.

As in the case of Fig. l, stripped gas, which may be taken from the main stream of stripped gas delivered in regulated amount through a pipe w into the lower part of the cooler and a corresponding amount is withdrawn by pump m from the upper part and passed through byass to the upper ypart of the heater. he iluminants are withdrawn at y. Gas rich in hydrogen may be withdrawn at z, or in the event of this not. being required, the main stream of stripped gas may leaveA at a instead of at'o. The meters or pumps controlling the -low of gases through the pipes fw and g are driven at a constant relative speed found, by `trial, best to revent intermixture of the illuminants wit the gas Aused for washing the charcoal, which in this form of vsaid invention and the best means I know of carrying the same into practical effect, I claim i 1. Apparatus for treating coal-gas to separate the non-illuminant hydrocarbon and other gases from the illuminants, comprisin a container, a heated chamber, a coole chamber and a chamber which is neither heated nor cooled in the said container, means for circulating charcoal successively through the heated chamber, the cooled chamber and the chamber which is neither heated nor cooled, means for passing coalgas through the lastnamed chamber in counter-current to the charcoal and means for withdrawing gas from the heated chamber.

2. Apparatus for treating coal-gas to separate the non-illuminant hydrocarbon and other gases from the illuminants, comprising a container, a heated chamber, a cooled chamber and a chamber which is neither heated nor cooled in the said container, means for circulating charcoal successively through the heated chamber, the cooled chamber and the chamber which is neitherheated nor cooled, means for passing coalgas through the last-named chamber in counter-current to the charcoal, means for withdrawing gas from the heated chamber, means between the heated chamber and the cooled chamber adapted to permit passage of charcoal while hindering passage of gas, means for withdrawing gas from the chamber which is neither heated nor cooled and introducing it into the cooled chamber, and

means for withdrawing gas from the cooled chamber and passing it into the chamber which is neither heated nor cooled.

3. Apparatus for treating coal-gas to separate the non-illuminant hydrocarbon and' other gases from the illuminants, comprisin va container, a heated chambeiga coole chamber and a chamber which is neither heated nor cooled in said container, means for circulating charcoal successively through the heated chamber, the cooled chamber and the chamber which is neither heated nor cooled, means for passing coal-gas through the last-named chamber in counter-current to the charcoal, means for withdrawing gas from the heated chamber, means between the heated chamber and the cooled chamber adapted to permit passage of charcoal While hindering passage of gas, means for with-

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