The wear characteristics of 0.42%C steel, 17Cr stainless steel and pearlitic cast iron at relatively low sliding speed have been examined by the pin-disc type wear machine in relation to the sliding surface temperature, and the general relation between wear of iron and steel and the sliding surface temper
Synopsis 111 relatioll to the slidillg swface tem/JUatllre, wear of pearlitic cast iron alld O.42 % C steel rubbed all 17% Cr stailliess steel, alld 17%C r stailliess steel all 0.60° oC steel was examilled at relatively low slidillg s,lJeeds b), a pill-disc type wear machille, alld tlze general relatiml betweell wear of ira//. alld steel alld the siidillg suiface temperatllre was discllssed 011 the basis q(tlzis sludy alld the previous papers. Bolh the tempnature at real cOlltartillg area called tlze jlash temperature and the meall temperature of the a/Jparellt cOlllact suiface were considered as Ihe slidillg suiface tem/Jerature. It has become clear that tlze wear characteristics of iron alld steel call be eX/llained systemalical0.by llze mutlwl re/atioll betweell Ihe flash temperature all d the meall tem/lerature. R egardless of the slidillg cOllditioll. when the flash lemperature is about 300°C, the maximum wear rale or Ihe specific wear due to the severe wear a/Jpears. alld wear beillg a little below 250°C. II •hen the jlash temperaturr is so high as some q(lhe real cOlltactill. 1(asperilips reach or ap/lroach to the meltillg POillt, wear de/Jfllds Oil Ihe meall tem/lera-Ilire alld its risillg resliits ill sClifJing.
Cleaning-in-place (CIP) of food processing equipment usually requires a huge amount of water. For reduction of water required in its final rinsing step, performance of air-water two-phase flow as a rinsing medium was studied. Horizontal and vertical straight pipes of 23 mm inner diameter were artificially soiled with millet jelly and rinsed with air-water two-phase flow at flow rates of 400, 600, and 800 L/min for air and 2, 3, and 4 L/min for water. At the lowest flow rate of air, the two-phase flow was not completely annular and rinsing efficiency was quite low. At higher air flow rates, however, the two-phase flow was shown to save about 90% of rinsing water with no or slight extension of rinsing time, compared with water flow rinsing at 40 L/min. For non-straight piping parts (tees, elbows, and a diaphragm valve), the air-water two-phase flow was shown to save about 80% of rinsing water but to take twice as much rinsing time as 40 L/min water flow. 1.緒 言 食品や飲料を製造する工場では機器の洗浄を日常的 かつ確実に行う必要がある.大型の機器が導入されて いる大規模な製造設備では,機器を分解することなく 自動洗浄を行う定置洗浄(CIP:cleaning in place)が 採用されている場合が少なくない.適切な条件で CIP を行えば,確実で安定した洗浄効果を期待できるが, CIP には水や薬剤を大量に必要とするという欠点もあ る.例えば,原料用や冷却用などに多量の水が必要と されるビール製造では,全用水量はビール製造量の 10 ~15 倍で,工場あたりにすると 2,000~7,000 m 3 / 日に 及び [1],用途別の水量では洗浄用水が最大の割合を占 める [2] とされている.洗浄用水として使用した場合 には等量の排水を処理する必要にも迫られるため,と くに生産規模の大きい工場にとって,その多さは無視 できない問題である.このため,多くの飲料・食品工 場では近年,用水の回収再利用や洗浄時間の短縮など を主な手法として,洗浄用水を含めた使用水量削減の 努力が重ねられている [i].一方で,使用水量の削減が 可能な新しい洗浄技術の開発も要望されているが,現 在のところ画期的な新技術の開発に係る文献情報は見 あたらない. 著者らは,パイプラインの洗浄において洗浄水削減 効果をもたらす新たな洗浄手段として,気液二相流の (受付 2010 年 6 月 1 日,受理 2010 年 7 月 20 日) 1 〒108-8477 東京都港区港南4-5-7 2 〒108-8477 東京都港区港南4-5-7 3 〒253-0071 神奈川県茅ヶ崎市萩園1225 †
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