178
MODERN GASWORKS PRACTICE
ing doors which admit of the main being cleaned whilst in use. Separate tar and liquor take-offs are fitted, and the gas is passed through a retort-house governor wliicli is mounted on a common platform with the collecting mains.
Bracings, consisting of buckstays and tie-rods, are provided to give ample support to the brickwork, the buckstays being supported on a joist built into the supporting walls. At the upper end the buckstays are attached to the framework surrounding the hoppers, the latter also forming the support for the charging floor.
As will be seen from Fig. 93, the retort house consists virtually of two steel-frame buildings.
The upper one forms a housing for the hoppers and charging floor, and the lower one covers the coke discharging floors and platforms carrying the collecting mains If desired, the space at the sides between the floor-level and the charging floor may be leffc open.
In the outer wall of the setting at the base of each retort a manhole is provided for access when renewals are required. At this point are also fitted nozzles with control valves for steaming the charge, the steaming being carried on continuously or immediately before withdrawing coke as may be required.
Fig. 9ß.—The Central System. Plan.