POWER SUPPLY.

Press, Volume LXVI, Issue 19979, 14 July 1930, Page 13

POWER SUPPLY.

COAL VERSUS WATER. ADDRESS BY PROFESSOR S. STEELE. "The subject of this paper was not suggested by recent happenings at Arapuni resulting in the steam power station : at Auckland being called into service again," said Professor S. Steele, in opening his presidential address to the Canterbury College Engineering Society on Saturday night. v . The speaker continued that the statement so often made, that lor locomotive and irarino work, the day of the steam engine wo* passing, was apt to give one .1 wrong impression as tt> the standing of steam in the world to-day, and to this false idea was gn en added importance locally by the- ousting of fcteam power plants in New Zealand ■towns. In the three great power using countries of the world, America, Germany, and Groat Britain, the main source of power was steam, and at present there was no indication that steam was los-' ing, its predominance. : For many jears it was accepted that . .the limit for boiler pressures was between 250 and 300 pounds per square x ( inch, but at present commercial hoilers rWere being built to resist pressures up to 3300 pounds per square inch. ' Other -modern .tendencies . worthy of notice were the rapid increase in the sizes of the power units, both for boilers and turbines, and the capacity'of these units to''give continuous •service,- In theVnited States o£America, ltmHy'potcntial-'sourcea power have remained undeveloped, because the cost at which ; be' sold from then), could n&J compete ', ' wisi the cost of current -supplied 'from steam power stations. This was tine to the much higher first .costs. Considering another competitor ' of * steam, namely, the internal '.cDmbusiion engine using crude oils-Jsttr it was found that engines. of ~tnis>type such as the Diesel, had a better 'thermal efficiency, but that only for marine ;work were they a serious - rival: to steam. As every. modern ipfljrk ."^a 8 supplied with bulk oil storage, passen-' - ger boats would use ©il v either as fuel under boilers or in Diesel - engines, even if the cost per trip* were higher than for coal fuel because 'of the cleaner "boat, fewer firemen, and.time, saved in fueling. However, the results, of tests which were at 'present being •' carried out with powdered coal on the 7 . Hororata,. and on German -vessels,,, might cause a swing .back in favour'of : <.- / coal."for cargo boats. The spread of, , - ;• the use of powdered coal in'land.pU*ts was very marked, the reasons for this •*„, spread being that< combustion,, > ; , more complete, with consequent^ - '•','; 'temperatures, and that" otherwise un-, /; saleable slack coal coidd 1 bought at very cheap rates, being quite satisfactory when powdered. '. ,■' ,1 h -'' * Professor Steele proceeded* to describe * the improvements-in details of .steam . "-' boilers and their furnaces, pointing * out that for boilers with" veryj • high temperatures and pressures wngj j .better material than ordinary mud _ -. steel would be required. In referring . ; to locomotives, he stated that' recent - - trials on tb« Schmidt boiler 'snowed - «. 4 an efficient of 9.4 per oent„ which v , was an increase tof 10-per cent, on'the _ ' previous best. These figures showed the progress made when one consider- <i*. Ed Stephenson's Rocket bad an effici- n; ency of 8 per cent.- ' • In moving a hearty vote of thanks ' , * to the president for his address. Pro- „*- - rfsssor Powell said that hydro power , supply was overdone in Zealand,. • - ■' and the proximity to a waterfall did ~ not necessarily mean that the cheapest , Jpower could be derived from 'the fall. - One often heard of schemes to develop ' ;: small hydro plants on the West Coast, ' .*■ where they had a very cheap supply of power—coal.