On　the　New　Supply　System　of the　LPG　Stored　in　an　Underground　Vessel

Abstract

LPG　is　used　by　a　Iarge　number　of　households，23 million　in 1990．This　number　is 55％ of　households　in　Japan，LPG consumption　per　hQusehQld　increased　from 108kg　in 1965 to 270kg　in 1990，The　storage　rooms　of　LPG　cylinders　are　usually on　the　groulld　surface．In　this　case，many　heavy　LPG　cylinders　are　carried　and　changed　by　hands．In　order　to　save　these handling　jobs　and　to　protect　the　storage　in　the　underground　from　a　fire，a　new　LPG　supply　system　was　proposed　and prototype　experiments　were　carried　out．And　theoretical　discussions　were　also　carried　out　by　the3dimensional　finite difference　method　in　a　numerical　analysis，The　main　results　obtained　are　as　follows：1. Fire　resistance （1）Maximum　nametemperaturewas780℃whell　rafters　of2700kg　werebumed　on　theground．Maximum　radiantheat was10100kca1／m2h．At20minutes　after　the　ignition，flame　temperature　and　radiant　heat　became　lower． （2）The　temperature　at 10cm　depth　from　the　ground　level　was27．5℃（△T－14.5℃）at　l　hour　after　the　ignition，and the　temperature　at20cm　depth　did　not　become　higher．△T＝（temperature original　ground　temperature＝13℃） （3）　The　temperature　in　the　vessel　at　l　hour　was14，5℃（△T＝1，5℃）．II，Field　test　for　LPG　consumption （1）　LPG　of6kg　or3kg／h　x8hours／day×5days／week　wasbumed　with　abumer　for　a　fewmonths，In　thecase　of6 kg／h，the　lowest　liquid　temperatuτe　was 34．4℃，and　two　days　without　bumlng　later，the　liquid　temperature　retumed　to the　original　temperature， （2）The　LPG　co且sumption　of　a　popular　family　was　monitored．Theoretlcal　allalysis　was　carried　out　with　the　monitored data．The　temperature　of　LPG　liquid　did　not　become　lower　than 4℃（△T＝一4．5℃）over　two　weeks　from　ignition，and the　temperature　of　soil　at5cm　from　the　vessel　became　steady　at 2．2℃（△T二一2．7℃），The　natural　vaporization　of　LPG in　the　underground　vessel　was　guaranteed．