Tipton Gas Works 1954-1960

By David Humphries

Tipton Gas Works produced town gas. It was situated in Alexandra Road on part of the site now occupied by the redundant gas from oil plant. The last coal gas plant was a Woodall Duckham vertical retort plant opened in 1954 and closed in 1960. It replaced an earlier Glover West vertical retort installation. The remains of this old works stood alongside the new for many years.

The Works from the top of No. 4 Holder

Stock Piling Coal in the form of washed singles and washed doubles was delivered into the stockyard by rail. It was unloaded and stockpiled using a Jones KL44 mobile crane. It was essential not to pile it excessively high because of the danger of spontaneous combustion within the heap. It was therefore customary practice to sink steel tubes into the heap. Maximum/minimum thermometers were kept permanently in these tubes to carefully monitor any temperature changes.

The Production Process

Coal was tipped from the railway waggon by a rotary tippler, passing into a receiving hopper below and dropping into a crushing machine which reduced large pieces to a suitable size.

Rotary Tipper

The coal passed into the retort where it was heated to a high temperature (up to 1300° C) and the gas given off was taken off through pipes for purification. As the coal passed down through the retort at a controlled rate it lost all of its volatile content until it became a residue of hot coke. At the base of the retort this red hot coke was quenched by a steam jet to cool it. This had the added advantage of chemically manufacturing water gas by reacting with the coke - increasing the yield of the gas.

Production Process (continued) A conveyor belt then transferred the coal to the basement level of the retort house, discharging it into one of two continuous bucket conveyors which ran longitudinally around the building. These conveyors carried the coal to the top of the works where the coal storage bunkers were situated. From here the coal passed at regular intervals through a gas-tight valve into a much smaller hopper below, which opened directly into a retort.

Producer landing and gas off-take necks to retorts odd side Producer access covers can be seen in the floor. The chalk figures on the necks are original damper opening details.

Production Process (continued) At the bottom of the retort a helical screw cut off the descending coke which collected below in a gas-tight hopper which was discharged at intervals. The discharged coke dropped into one of the two longitudinal conveyors which could be controlled to direct the coke into the screening plant. Here it was graded into sizes and stored, for sale, in large bunkers.

Coke Hoppers and Drive to No. 4 Even Side The drive to the wheel controlling the helical screw inside No. 4 retort shows that pair 3 and 4 are empty for de-scaling. The inspection cover is lying on the steel mesh floor. The pipe on the floor confirms an internal flue leak is being welded. The rod running horizontally controlled the rate of throughput. The “odd side” is

similar.

Purification At Tipton there were eight purifiers, four large units in one set, and four smaller units installed as part of the Glover West installation. The impure coal gas was taken off the retort through a cast-iron off-take pipe. To flush out any solids which condensed there, tar was sprayed into the pipe. From the retort house the hot foul gas was passed down through the primary condenser where the bulk of the tar and some of the ammonia were removed for further processing. The partially clean gas was then pumped through the remaining stages of purification by one of a number of steam driven exhausters (manufactured by Bryan Donkin.)

Testing for tar in gas stream

Purification (continued The gas then passed into a large cast-iron ammonia scrubber. Inside the scrubber were layers of wooden grids which were sprayed with softened water creating a large wet surface that readily dissolved any remaining ammonia in the gas. (The water softener was a Kennicot by John Thompson of Wolverhampton.)

From the scrubber the gas was passed down through secondary condensers to remove any carried over ammonia. At this point the major remaining impurity was hydrogen sulphide – all traces of which had to be removed by law. The gas was passed through layers of iron-oxide in the form of a peat-like bog-ore contained on slatted wooden racks in large steel tanks supported on a steel framework above ground (to facilitate emptying.) The chemical reaction between the iron oxide and the hydrogen sulphide resulted in the deposition of sulphur. As this was an exothermic reaction, the process had to be carefully monitored. The gas was now sufficiently purified for use and after passing through the station meter, was stored in one of Tipton’s four gasholders.

Ammonia Concentration Plant

Waste Reduction The by-products recovered at the Tipton works were all saleable.

Tar: was collected in a tar well where the ammonia which may still be present in it was separated out. The tar was pumped into a storage tank to await collection by canal boat by Midland Tar Distillers.

Ammonia: was pumped to the ammonia concentration plant. After processing it was stored to await collection by rail by Brothertons.

Coke: a ready market was found for both domestic and industrial purposes. Part of the coke output was kept in the retort house as fuel for the producer gas plant which made the gas for heating the retorts. Some coke was also used for standby steam-raising on the works. Two Lancashire boilers were installed for this purpose although under normal operating conditions the waste-heat boiler was more than capable of meeting the demand for steam.

Sulphur: there were two customers for this – Albright and Wilson at Oldbury and I.C.I. at the Willingsworth works. A greater yield of recoverable sulphur could be obtained if oxygen in the form of air was introduced into the gas stream at the inlet to the purifiers. At Tipton a small electrically powered blower was installed. When the iron oxide was saturated with sulphur in the first purifier in the “stream” it could be rejuvenated by changing the sequence of the purifiers. Eventually however the oxide would fail to react further and the affected purifier would be taken out of stream, and opened. The spent-oxide was sampled and analysed to determine its sulphur content. If the sulphur content was near 50% it was sold for the manufacture of sulphuric acid. If the sulphur content was low then the oxide was mechanically broken up and mixed with fresh bog-ore and used a second time.

Control It was necessary to control the temperature in each of the “passes” (or flues) in the retort on a daily basis. A low temperature gave a low gas yield of high calorific value and a high proportion of impurities, whilst a high temperature gave a high yield of gas at a lower calorific value with proportionally lower impurity content. Sliding refractory brick dampers controlled:

• the volume of producer gas admitted

• the volume of hot primary air admitted

• the volume of secondary air admitted

• back pressure in the heating flues

By manipulating the damper openings it was relatively easy to control:

• the length of the heating flame

• the temperature

• the area within the flue where the temperature was highest

Bottom Passes (Even Side) Temperatures are taken by flipping open viewing flaps in the small cast iron covers. The covers rested in tapered guides to give a gastight seal. They were easily lifted off to give access for removal of dust from the heating flues. The trolley arrangement was used by the technician when taking the heating flue temperatures.

Control (continued) The rate at which coal passed into the retorts from the individual bunkers was monitored from the outside by a simple indicator device consisting of a chain passing over a pulley. On the end in the bunker was a weight which rested on top of the coal. On the outside was a “D” shaped handle. The position of this handle was marked at hourly intervals, with chalk, on a cast-iron panel bolted to the outside of each bunker. It is known that coal swells when heated. For gas making it was necessary to use a coal which caked well to make good coke but with a minimum of swelling. Because of the tendency to swell the charge passing down the retort tended to “stick” and as a matter of operating routine plugs were removed from the top casting and long poker inserted to assist the coal to travel smoothly. This was known as “rodding”.

Len Mayo Rodding on Even Side c1958 The marker board and “D” ring for checking coal feed is seen on the right. The thin vertical pipe is the tar spray supply. The rodding holes are sealed with cast iron plugs. The poker is some 12/14 feet long. The heavy timbers lying below the (always) open windows suggests Duckhams are on site doing major re-lining. This was summer time work when gas demand was low.

Joe Atkins Cleaning the Producer Grate