Smoky Law and the Clean Air Act – 60 years on

‘In 1952 Great London Smog Killed 4,000 People In 4 Days’ (1)

 It is now 60 years since the first Clean Air Act was introduced in the UK. On this anniversary, Energy Institute member George R Mattocks CEng FEI, now 93 years old, writes a personal account of research he undertook and his time at the University of Sheffield and the National Smoke Abatement Society, around the time the act was introduced.

On the 60th anniversary of the first Clean Air Act in 1956, I am reminded of my very fortunate link in the early post-war years at Sheffield University with the resurgent National Smoke Abatement Society. In particular my thanks extend to engineer James Law (1), who was an active stalwart member of the above society. James Law was the Chief Smoke Inspector of Sheffield City Council and, as expected, was known locally as ‘Smoky Law’.

During the war, steel production was paramount but over this period, the Fuel Efficiency Committee of the Ministry of Fuel and Power produced a comprehensive reference book entitled The Efficient Use of Fuel in 1944. The Education Sub-Committee that produced this work was chaired by R J Sarjant DSc, a metallurgical works chemist and statistician who, after the war, was awarded the OBE and also became the Professor of Fuel Technology at Sheffield University.

Within months of the end of the war, in February 1946, a joint meeting was held in Doncaster between the Yorkshire Branch of the Institute of Fuel and the National Smoke Abatement Society entitled ‘Technical Progress in Smoke Abatement’ (2). Papers were presented by metallurgical consultant Dr H A Fells, W A Wordley and Dr J E Garside of Leeds University.

James Law attended meetings around the country, reporting back to the Sheffield, Rotherham and District Smoke Abatement Committee. He also attended a joint meeting of the Regional Smoke Abatement Committees at Wolverhampton on 21 January 1948. James Law was also the Sheffield City Council representative on the Mining and Fuel Committee at the University.

His regular meetings with Professor R J Sarjant led to a research grant from the National Smoke Abatement Society to the University of Sheffield Fuel Department. This grant enabled study into the local problem of smoke emission from low temperature annealing furnaces for tool steels where the operators insisted that a smoky flame was desirable to maintain an acceptable surface quality to the steels.

Following my return to Sheffield University after the war to complete my degree, I obtained a Class 3 Honours degree in Physics in 1948. This disappointing result led me to look for a postgraduate research position in one of the applied sciences. I heard about the above research position in the University’s Fuel Department and was successful in obtaining it. I was very fortunate in joining and working under Professor R J Sarjant with his vast combined academic and industrial experience. I also had access to a very good departmental workshop.

There were two main challenges in the design of the experimental equipment at the department. The first was to produce a lean producer-gas generator that was directly connected to the electrically heated 2” diameter ceramic tubular furnace system comprising of an atmosphere conditioning section and a steel heating section that led finally to an exhaust sampling system. The second design challenge was for a smoke sampling system in the above exhaust system.

The design of the lean producer-gas generator was eventually completed by burning downwards the 500 g charge of graded bituminous coal contained in an extremely well insulated 2” diameter gas pipe. The coal was burnt at a rate of one gram per minute, and after 2.5 hours reached a thermal equilibrium and a constant basic gas composition for a further period of 6 hours.

The measurement of both distillation and particulate matter in the smoke required the design of a robust yet sensitive form of thermal precipitator. This was achieved by drawing the waste gas sample through a fixed electrically heated open-ended conical funnel. Within this funnel was an accurately centred and removable water-cooled matching round-ended cone that created the uniform and adjustable thermal gradient in the annulus required for precipitation. A spun 4” long aluminium cone weighing about 10 grams could be fitted onto the water-cooled cone to collect the smoke. Subsequent weighings after using a solvent enabled the accurate measurement of the two types of smoke from the coal combustion rate of 1 gram per minute.

For the main studies, samples of eight so-called critical tool steels were heated together for a period of 5 hours at a temperature of 860^°C in twelve different coal combustion atmospheres produced from the basic lean producer-gas generator. A continuous record of the CO/CO₂ ratio in the waste gas was obtained and spot samples taken for subsequent quantitative analysis for unburnt hydrocarbons, sulphur gases, oxygen and smoke. The annealed steel samples were assessed for the levels of surface oxidation/scaling and, when required, decarburisation. The normal sample weights before and after pickling to assess the level of oxidation were also used to assess an approximate scale composition. The scale adherence was assessed by dropping the sample through a smooth tube onto a ball bearing.

Using the same apparatus, a second study (3) was made of the conditions of air supply and temperature that resulted in the formation of smoke from the distillation products contained in the same basic lean producer-gas supply.

From these two studies (4) it was concluded that for seven of the eight steels examined, a latent smoke producing atmosphere was unnecessary for the optimum heat treatment/annealing. The value attributed to the presence of smoke was shown to be due to the state of the sulphur gas that arises from the fuel bed. Initially, the sulphur is contained in the tars and as H₂S, and any air provided above the bed to burn the distillation products to avoid smoke also burns the sulphur to the strong oxidising gas SO₂.

This concludes a brief account of my unpublished work that was my small contribution to the work of the National Smoke Abatement Society that led to the 1956 Clean Air Act.

Unfortunately because I took an extra year to complete my work, the results were not available to Professor R J Sarjant to include in his planned paper entitled ‘A Survey of the Problem of Smoke Abatement in Low Temperature Furnaces’ that he gave to a meeting of the Royal Sanitary Institute on 8 June 1951 at Sheffield (5).

However, he did have the work of two other researchers in his department to conclude this excellent 20-year survey. One was the work of R H Oglesby who had made a survey of 106 small heat treatment furnaces in the Sheffield area, of which 76 were coal fired and 47 were hand coal fired. The other was by A Preston who, on a large-scale apparatus, was examining the design of mechanical stokers to avoid smoke production.

In 1952 Professor Sarjant obtained a Department of Scientific and Industrial Research grant to engage postgraduate student P B Simpson to continue my work. He used the same apparatus fired by town gas on the same steels to establish this alternative to coal firing.

Once again, unfortunately this work was finished a year after Professor M W Thring (who had a very different background to Professor Sarjant), had taken over the Chair of the Fuel Department at the University in 1954. Like my own work, this work was immediately disseminated but never published. I strongly believe (6) that this was due to a ‘Clash of the Titans’.

However, in retrospect, I now realise how the extra year that I spent on my challenging research project affected the final Professorial path of my eminent mentor. I am extremely grateful that this path also resulted in the conversion of a 25-year-old physicist, shell-shocked by quantum mechanics, into a latent research technologist.

I also want to express my thanks once again to James Law who set me on a path of industrial research on high temperature furnaces, first in the steel industry and then mainly in the glass industry. In retirement I developed the concept of the use of synthetic air (7) (oxygen mixed with re-circulated waste gas) to greatly improve the thermal performance of regenerative furnaces.

Finally, my second social industrial activity, ‘Smoky’, was a technical submission to the HM Planning Inspectorate Inquiry in 2002 against the installation of an energy-from-waste incinerator on the outskirts of my home town, Kidderminster (8). Also, I want to thank James Law for 60 years of happy marriage because in 1953 I married the arts graduate, ex-WRNS Secretary of both of the Professorial Titans.

G R MATTOCKS

BSc PhD CEng FEI FSGT

References

1. Sheffield Libraries Archives and Information – March 2016.
2. Original copy now with the Energy Institute Archivist.
3. Short paper for Student Fuel Society Journal 1952/1953.
4. Thesis ‘Coal Combustion Atmospheres in the Heating of Steel’ Sheffield University 1952.
5. Advance copy of papers now with the Energy Institute Archivist.
6. Letter to MWT with copy to RJS on 12th December 1958.
7. Glass Technol., 1998, 39(5), 148-56.
8. Letter to the Editor, Journal of the Institute of Energy, June 2003, 76, pp 62–63.