blowing engine
{{Short description|Device which provides forced air to smelters}}
{{Use dmy dates|date=March 2020}}
File:Allis blowing engine (New Catechism of the Steam Engine, 1904).jpg
A blowing engine is a large stationary steam engine or internal combustion engine directly coupled to air pumping cylinders. They deliver a very large quantity of air at a pressure lower than an air compressor, but greater than a centrifugal fan.
Blowing engines are majorly used to provide the air blast for furnaces, blast furnaces and other forms of smelter.
Waterwheel engines
The very first blowing engines were the blowing houses: bellows, driven by waterwheels.
Smelters are most economically located near the source of their ore, which may not have suitable water power available nearby. There is also the risk of drought interrupting the water supply, or of expanding demand for the furnace outstripping the available water capacity.
These restrictions led to the very earliest form of steam engine used for power generation rather than pumping, the water-returning engine. With this engine, a steam pump was used to raise water that in turn drove a waterwheel and thus the machinery. Water from the wheel was then returned by the pump. These early steam engines were only suitable for pumping water, and could not be connected directly to the machinery.
The first practical examples of these engines were installed in 1742 at Coalbrookdale{{Book-Hills-Power from Steam|pages=37 }} and as improvements to the Carron Ironworks on the Clyde in 1765.{{cite book
|last1=Rolt |first1=L T C
|last2=Allen
|title=Steam Engine
|ref=Rolt, Steam Engine
|pages=122
}}
Beam blowing engines
File:Grazebrook Beam Engine.jpg blowing engine, formerly used at the Netherton ironworks of M W Grazebrook, now preserved on the A38(M) in Birmingham, UK]]
Early steam prime movers were beam engines, firstly of the non-rotative (i.e. solely reciprocating) and later the rotative type (i.e. driving a flywheel). Both of these were used as blowing engines, usually by coupling an air cylinder to the far end of the beam from the steam cylinder. Joshua Field describes an 1821 trip to Foster, Rastrick & Co. of Stourbridge,{{cite web
|title=Foster, Rastrick & Co. of Stourbridge
|work=Author's tour through the Midlands
|date=24 Aug 1821
|author=Joshua Field
|authorlink=Joshua Field (engineer)
|url=http://www.tom.cockeram.clara.net/Industry/1821jb.htm
|quote=The third engine is very handsome a 6 column engine [a beam engine with a horizontal frame raised on columns] of 30 H Power working a blowing cylinder of 5 feet, 6 feet stroke"
|url-status=dead
|archiveurl=https://web.archive.org/web/20081012033628/http://www.tom.cockeram.clara.net/Industry/1821jb.htm
|archivedate=2008-10-12
}} where he observed eight large beam engines, one of 30 hp working a blowing cylinder of 5 feet diameter and 6 feet stroke.
Where the later beam engines drove flywheels, this was useful for providing a more even action to the engine. The air cylinder was still driven by the beam alone and the flywheel was used solely as a flywheel, not driving an output shaft. A well-known surviving example of this type are the paired beam engines "David & Sampson", now preserved at Blists Hill open-air museum, Ironbridge Gorge.{{cite web
|title=David and Sampson - a vintage beam engine and a scheduled Ancient Monument at the Blists Hill Site.
|url=http://www.telford.gov.uk/externalfunding/erdf/sampson.html
|format=image
|url-status=dead
|archiveurl=https://web.archive.org/web/20071109023316/http://www.telford.gov.uk/externalfunding/erdf/sampson.html
|archivedate=2007-11-09
|title=David & Samson at Blists Hill
|work=The reconstructed past
|last=Jameson |first=John H.
|isbn=0-7591-0376-3
|year=2004
|url=https://books.google.com/books?id=zXpJaFAcr4UC
|pages=182
|publisher=Rowman Altamira
|ref=Jameson, Reconstructed past
}} These are a pair of single-cylinder condensing beam engines, each driving an air cylinder by their own beam, but sharing a single flywheel between them. They are notable for their decorative Doric arches.{{cite web
|title=David & Sampson: Doric arch
|format=photograph
|author=Mike Ashton
|date=3 May 2008
|url=https://www.flickr.com/photos/macreative/2469682013/
}} The engines had a long working life: 50 years of primary service from 1851 providing the blast for the Priors Lee furnaces of the Lilleshall Company,{{cite web
|title=Lilleshall Collection at Blists Hil
|url=http://www.ironbridge.org.uk/about_us/library_and_archives/collections/lilleshall_collection/
|url-status=dead
|archiveurl=https://web.archive.org/web/20120222223820/http://www.ironbridge.org.uk/about_us/library_and_archives/collections/lilleshall_collection/
|archivedate=2012-02-22
|title=The Lilleshall Company
|url=http://www.corvedale.previewurl.com/history/lilleshall_company.htm
}}{{dead link|date=July 2017 |bot=InternetArchiveBot |fix-attempted=yes }} then a further 50 years until the plant's closure as reserve engines, still being worked occasionally.{{cite web
|title=Blists Hill, Ironbridge Gorge Museum, Madeley, Shropshire
|work=Viewfinder
|publisher=English Heritage
|url=http://viewfinder.english-heritage.org.uk/search/detail.aspx?uid=60056
|url-status=dead
|archiveurl=https://web.archive.org/web/20110606132611/http://viewfinder.english-heritage.org.uk/search/detail.aspx?uid=60056
|archivedate=2011-06-06
}}
Semi-rotative blowing engines
The large vertical blowing engine illustrated at the top was built in the 1890s by E. P. Allis Co. of Milwaukee (later to form part of Allis-Chalmers). The steam cylinder (lower) is {{convert|42|in|m}} diameter, the air cylinder (upper) {{convert|84|in|m}} and both with a stroke of {{convert|60|in|m}}.
The steam cylinder has Reynolds-Corliss valve gear, driven via a bevel-driven auxiliary shaft beneath, at right-angles to the crankshaft.{{cite book
|title=New Catechism of the Steam Engine
|url=https://archive.org/details/newcatechismofst00hawkrich
|year=1897
|last=Hawkins |first=Nehemiah
|authorlink=Nehemiah Hawkins
|publisher=Theo Audel |location=New York
|pages=[https://archive.org/details/newcatechismofst00hawkrich/page/n334 335]–337
|ref=Hawkins, New Catechism of the Steam Engine
}} This also means that the Corliss' wrist plate is at right-angles to the flywheel, rather than parallel as is usual. Edwin Reynolds was the designer of the Allis company and in 1876 had developed an improved version of the Corliss valvegear, with improved trip gear capable of working at higher speeds.Hawkins, New Catechism of the Steam Engine, p.225, p.172 The air valves are also driven by eccentrics from this same shaft.
Like the beam engines, the main force of the piston is transmitted to the air cylinder by a purely reciprocating action and the flywheels exist to smooth the action of the engine. To permit adjustment, the steam piston rod only goes as far as the crosshead. Above this are twinned rods to the air piston. The flywheel shaft is mounted below the steam piston, the paired connecting rods driving downwards and backwards to make this a return connecting rod engine.
Internal combustion blowing engines
File:Machine soufflante John Cockerill 1900.jpg engine of 1900]]
In the late 1800s, internal combustion gas engines were developed to burn gasses produced from blast furnaces, eliminating the need for fuel for steam boilers and increasing efficiency. Bethlehem Steel was one such company to employ this technology.{{cite web
|title=Gas Blowing Engine Room (at Bethlehem Steel)
|url=http://opacity.us/image7748_in_the_pit.htm
}} Huge, usually single-cylinder horizontal engines burned blast furnace gas. SA John Cockerill of Belgium and Körting of Hannover were both noted makers of such engines.
There are some efforts underway to restore a few of these engines.{{cite web
|title=Bethlehem Blowing Engines
|url=http://bethengines.blogspot.com
}} A few firms still manufacture and install multi cylinder internal combustion engines to burn waste gasses today.{{cite web
|title=Furnace Gas for Power Production
|url=https://www.clarke-energy.com/furnace-gas/
}}
Replacement by rotary blowers
As blast furnaces re-equipped after World War II, the favoured power source was either the diesel engine or the electric motor. These both had a rotary output, which worked well with contemporary developments in centrifugal fans capable of handling the huge volumes of air. Although the reciprocating steam blowing engine continued where it was already in use, they were rarely installed after the war. These older plants began to close in the 1950s and numbers were drastically reduced throughout the West during the 1970s. Blowing engines of this form are now rare.
Surviving examples today
File:Backbarrow blowing engine.jpg
Examples of both a beam blowing engine and a vertical engine may be seen at the Blists Hill open-air museum, Ironbridge Gorge. The beam engines "David & Sampson" are scheduled monuments.
An 1817 beam blowing engine by Boulton & Watt, formerly used at the Netherton ironworks of M W Grazebrook, now decorates Dartmouth Circus, a traffic island at the start of the A38(M) motorway in Birmingham (see picture above, location: {{coord|52.492537|-1.888189|region:GB_type:landmark|display=inline}}).
References
{{commons category|Blowing engines|
Blowing engines}}
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