Air Preheaters

The Ljungström Air Preheater 1920
An International Historic Mechanical Engineering Landmark

June 21, 1995 Stockholm, Sweden

SMR
Svenska Mekanisters Riksförening American Society of Mechanical Engineers

Stockholm 1920 The Ljungström Air Preheater
The inventor Fredrik Ljungström from the Ljungström Medal

Historical Significance of Landmark
Throughout the history of boilers therehave been many advancements in order to obtain a better performance and lower fuel consumption. However, few inventions have been as successful in saving fuel as the Ljungström Air Preheater invented by Fredrik Ljungström, then Technical Director at Aktiebolaget Ljungström Ångturbin (ALÅ). The first installation in a commercial boiler saved as much as 25% of the fuel consumption. In a modern utilityboiler the Ljungström Air Preheater provides up to 20% of the total heat transfer in the boiler process, but the Ljungström Air Preheater only represents 2% of the investment. The Ljungström Air Preheater is a remarkable invention in many ways. About 20,000 had been supplied to all corners of the globe by 1994. It has been estimated that the total operating hours amassed by all Ljungström AirPreheaters amount to about 1,500,000,000. The earliest installations of the Ljungström Air Preheater have been taken out of service because the fact that the boiler plants have been torn down, consequently the ASME International Historic Mechanical Engineering Landmark is placed at Tekniska Museet in Stockholm with a permanent exhibition comprising a working model earlier used for experiments 1961 -77 at Svenska Rotor Maskiner AB.

Economic Impact of the Landmark
The use of a Ljungström Air Preheater in a modern boiler plant saves a considerable quantity of fuel - so much that the cost of the preheater is generally recovered after only a few months. It has been estimated that the total world-wide fuel savings resulting from all Ljungström Air Preheaters which have been in service isequivalent to 4,500,000,000 tonnes (4,960,000,000 tons) of oil. An estimate shows that the Ljungström Air Preheaters in operation annually saves about $30 Billion US. The distribution of thermal power capacity in which Ljungström Air Preheaters are installed over the world is shown in the table below. The estimated distribution of annual saving in $US can also be found in the table below:
Installedcapacity GW 65 Africa 471 North America South America 35 370 Asia 216 CIS 365 Europe 38 Oceania 1560 TOTAL Continent Saving $BUS/year 1.6 6.6 0.7 7.7 3.8 7.6 0.5 28.5

% 5 30 2 24 14 23 2 100

Landmark Contribution to Development of New World Wide Industry
The use of the Ljungström Air Preheater started in the 1920:s throughout the whole world. In the beginning the marketing of the LjungströmAir Preheater was made in close connection with ALÅ, but most of the deliveries have actually been made through a network of licensees throughout the world.

Figure 1. T h e l a n d m a r k e d m o d e l o f the Ljungström Air Preheater at Tekniska Museet, Stockholm.

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Licensees
1923 Svenska Maskinverken AB, Sweden James Howden & Co., G:t Britain* Maskin & Brobyggnad, Finland 1924Smulders, Belgium* Nebrich, Czechoslovakia Gefia, Austria 1925 Oekonomia/Ganz, Hungary* Feuerungstechnik, Germany Lammers & Maase, Germany 1926 Air Preheater Company, USA* 1927 Gadelius, Japan* Babcock & Wilcox, France* 1930 Luftvorwärmer, Germany Sulzer, Switzerland 1932 Hueck & Büren, Germany Julius Pinsch, Germany 1933 Wiesner, Czechoslovakia 1934 Kraftanlagen Heidelberg, Germany* 1935 Dano, DenmarkSkoda, Czechoslovakia Witkowitz, Czechoslovakia Cegielski, Poland 1936 Simmering, Austria* 1937 Erste Brünner, Czechoslovakia* Ceskomoravska, Czechoslovakia 1942 Venezia, Italy* Holima, the Netherlands* Breda, Italy* 1943 Ansaldo, Italy* 1947 Tosi, Italy* 1949 Gefia, Genua, Italy 1952 Tampella, Finland 1957 Ganz, Hungary* 1958 Burmeister & Wain, Denmark 1959 Rafako, Poland* 1967 Stein, France* *...