THE HORIZONTAL RETORT BENCH
113
R. J. Rew has a'dopted the principle of fitting a special duet to the base of the retort and has met with considerable success. The principle will be readily understood by reference to Fig. 58.
Perhaps success is chiefly dependent upon ampie recognition. being given, to the following points :—
(b) A retort temperature of approximately 1,100° C. (2,000° F.) should be consistently maintained.
(c) Superheated steam must be used.
(d) The supply of steam should be carefully regulated so as to avoid anytliing approaching an excess. Moreover, the pressure should not be too great, as high pressure means high space-velocity
throughout the charge, whereas compara-tively low time-contact is desirable.
(e) In systems where steam is ad-mitted by duet or pipe throughout the length of the retort the precaution should be taken of stopping the first two or three feet of such duet or pipe. This par-ticularly applies to stop-ended retorts with one ascension pipe, for if the steam is allowed to escape in the first few feet it will tend to short-circuit direetly up the outlet pipe.
(f) It has been found advisable to work all steamed retorts under a vaeuum of from 2 to 5-tenth.s, otherwise with
Fig. 58.—Rew’s Channel System for Steaming Horizontal Retorts.
retorts in bad repair the gas escapes into the furnace instead of going forward by the ascension pipes.
As regards the effeet of steaming horizontal retorts, P. B. Ellacott1 has given the following figures which were obtained from fairly prolonged working at Newry Gasworks :—■
Without Steam. With Steam.
Gas made per ton of coal (cubic feet). . . . 12,000 .. 14,200
Coke sold per ton of coal (cwts.) ______________________.... 9 .. 8
Fürther results obtained by the Devon Gas Association, working with Rew’s channel system, were as follows:—
Gas made per ton of coal (cubic feet) . Coke sold per ton of coal (cwts.).
Without Steam. . 11,248
8-1
With Steam.
15,030 7-2
OUTSIDE PRODUCERS
The term “ outside ” or “ external ” producer embraces those types which do not form part and parcel of the retort bench; that is to say, the producer gas is 1 Gas World, LXXI, page 142.
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