Description of the Process of Manufacturing Coal Gas, for the Lighting of Streets Houses, and Public Buildings / With Elevations, Sections, and Plans of the Most Improved Sorts of Apparatus Now Employed at the Gas Works in London and the Principal Provincial Towns of Great Britain; Accompanied With Comparative Estimates, Exhibiting the Most Economical Mode of Procuring This Species of Light

by Friedrich Christian Accum

When the retort is in a good working state, the temperature should be kept up by the application of small quantities of fuel at a time. A prodigious saving of fuel may be effected by attending the fire properly, and it is this which distinguishes a careful stoker from a bungler. For in the working of this retort particularly, it is a wasteful process to clog up the fire-place with a large quantity of fuel injudiciously applied. The difference in this respect, with regard to the economy of fuel is so great, that an expert stoker will work the retort with one-third less of fuel and half the labour that would be employed by a negligent workman.

The quantity of gas produced from a chaldron of coal may be ascertained by the gas metre, or by the gas holder, if the outlet valve of the latter be shut during the distillatory process.

The heat at the same time employed for working the retort, will be best defined for the stoker’s guide, by copying carefully on paper the red tint of the retort, as seen through the sight hole, made for that purpose in the brick-work directly over the fire-place.

The first six feet of the perpendicular pipe H, fig. 1, [plate II.], which conveys the distillatory products from the retort, should be well cleaned out once a month, the bonnet at the bended part of the pipe H, fig. 1, is provided for that purpose, as already stated, [page 119].

When the retort remains uncharged, the fire must be kept low in order to prevent its getting beyond the usual temperature, and the arms and moveable axis should be turned occasionally, and the door kept close.

The fire tiles which cover the flues under the retort should be examined about once a fortnight, and if a tile is melted or broken, it must be replaced by a new one, because the preservation of the retort greatly depends upon this precaution.

All the parts of the arms composing the moveable disc within the retort, may be taken out of the door of the retort, if they should require a repair, first taking off the cap from the perpendicular pipe E, fig. 1, [plate II.], surrounding the shaft of the retort, then the centre piece, or rose centre, F, fig. 2, [plate II.], the shaft D, fig. 2, [plate III.], may be drawn up through the pipe which surrounds it.

When the retort requires cleaning, which should be done once every six or eight months, a screw may be attached to the upper extremity of the shaft D, which passes through the retort; by this means, the arms and rose centre within the retort can easily be raised, to leave the bottom of the retort quite clear, in order that the lumps of coke, that may be scattered about, may be easily removed. And if an incrustation of coke should happen to be attached to the bottom of the retort, it may be readily detached by a crow bar, or other suitable instrument.

The trays or coal boxes, fig. 12, [plate II.], may be made by the stoker, of sheet iron, (called in commerce No. 16,) framed upon a wooden mould made for the purpose.

The temperature best suited for the decomposition of coal by means of the horizontal rotary retort depends, as has been already stated in the case of cylindrical cast-iron retorts, altogether on the price of coal, and the price which can be obtained for the coke.