Born 1922 in Argentina, L.D. Porta is a mechanical engineer specialising in the steam locomotive - a dying breed for sure. A protegé of the French engineer André Chapelon, who some would argue was the greatest steam locomotive engineer of all, Porta has played a large part in keeping the further development of the steam locomotive alive.
His two largest innovations in steam locomotive technology have been the Gas Producer Combustion System (GPCS) firebed, and the Lempor exhaust system.
The GPCS burns a thicker than normal bed of fuel with restricted airflow to produce coke or charcoal and combustible gases (carbon monoxide and volatile hydrocarbons) which are then mixed with secondary air above the burning fuel to burn in turn. Because most of the air is introduced above the fuel rather than below, the fierceforced draught of the steam locomotive no longer pulls unburned fuel from the firebed and throws it out the stack, as happens when a conventional locomotive is working hard; this may represent up to 50% of fuel wasted when a non-GPCS locomotive is at maximum capacity. It also is a much simpler fire to tend than the thin, light fire of a conventional steam locomotive, that requires constant manual attention.
The Lempor exhaust produces the maximum draught for the minimum possible back pressure, helping the locomotive's efficiency. It works in tandem with the GPCS firebed, because its greater forced draught cannot be easily handled with a conventional coal-fired locomotive.
Porta's refinements of the steam locomotive have not stopped there, however; the successful optimisation of a machine involves improvements everywhere. Attention is paid to every part of the locomotive; in particular, more efficient steam flow, mechanical lubrication, water treatments, easier maintenance, and many others.
Porta's career began with the Buenos Aires provincial railways, where he produced a fairly advanced 4-8-0 streamlined express passenger locomotive. He followed this by improving their fleet of 2-6-2T locomotives used in commuter service.
In 1957, he took the position of General Manager of the Rio Turbio Railway, a coal-hauling narrow-gauge railroad in the extreme south of Argentina. Here he had the complete freedom to innovate, and he made their fleet of 2-10-2 locomotives into some of the most efficient steam locomotives anywhere. Here Porta's GPCS firebed came into its own, for it was perfectly suited to burning Rio Turbio's low quality coal efficiently.
After a time as the Rio Turbio Railway's general manager, Porta moved into academia as the head of the thermodynamics department at Argentina's INTI institute. Since then, he has been involved in nearly every project to improve steam locomotives worldwide, including the abortive ACE project in the United States, and David Wardale's Red Devil in South Africa.
Currently, he is involved in improving steam locomotives in Cuba, one of the few nations left that still use steam on a regular basis. He has assisted in the design of locomotives that use cheap biomass waste matter as fuel, such as bagasse, the waste husks of sugar cane. The GPCS design allows such fuel to be burned efficiently.
L.D. Porta passed away on June 10, 2003 in Buenos Aires, Argentina at the age of 81. He will be sadly missed, both personally and as an engineer and visionary. Let us hope that he does not go down in history as the last great steam locomotive engineer, even though that would be a fitting epitaph.
Sources include: The Ultimate Steam Page at http://www.trainweb.org/tusp/porta.html; an obituary in The Guardian newspaper at http://www.guardian.co.uk/argentina/story/0,11439,1011043,00.html; and numerous postings on the SteamTech mailing list (http://groups.yahoo.com/group/steamtech).