Jökull - 01.12.2007, Page 75

A hot water drill with built-in sterilization
Table 1. Main components of the hot water drilling system (cf. Figure 1). – Helstu hlutar bræðsluborsins.
SYSTEM 1: Closed glycol heating system and snowmelter
Item Unit Type/manufacturer
1A Glycol heater - combustion unit Aquila HB303
1B Pressure relief valve Standard
1C Air eliminator Caleffi 551
1D Heat exchanger SR Vélaverkstæði
1E Snowmelter, 600 liters Borgarplast
1F Circulating pump Grundfos UPS 25–60
1G Expansion vessel Flexcon C/K
SYSTEM 2: Filters, UV-systems, high pressure pump + heater, hose, drill stem
Item Unit Type/manufacturer
2A Water feed pump Grundfos CH2-40
2B Twin-filter 50µm
2C UV-sterilization unit Pura UV20-1 (UV lamp #20, 22W)
2D High pressure pump with heater Kärcher HDS1000 DE
2E Hose winch drum SR Vélaverkstæði
2F Right angle geared winch motor SEW-Eurodrive
2G Hose (600 m) Diesse Hot Water 400
2H Drill stem SR Vélaverkstæði
Electricity required for units 1A (burner fan), 1F, 2A, 2C and 2F is supplied by a 2.2 kW gasoline generator. Unit 2D is powered by an
in-built, 6.6 kW Yanmar diesel engine. Speed control module for winch motor: SEW Eurodrive, MBG11A. S1–S4 on Figure 1 are sampling
outlets. Fuel consumption measured during drilling: Aquila diesel burner; 10 l/hr. – Kärcher diesel burner; 7.5 l/hr – Diesel motor powering
Kärcher high pressure pump and burner fan; 1 l/hr. – Gasoline generator powering units 1A, 1F, 2A, 2C and 2F; 1–1.5 l/hr.
(operating pressure range: 40–210 bar; max. tempera-
ture: 150!C). The water is then pumped into a 600 m
long hose made of synthetic rubber, which is rein-
forced with 2 high-tensile steel braids and deployed
on a winch. The hose winch is powered by a right an-
gle geared motor and fitted with a reduction gear that
allows a minimum rotation rate of 3.3 revolutions per
hour, corresponding to a penetration speed of 5.4 m/h
(1.5 mm/s) for the outermost layer of hose on the
winch. The maximum attainable winching speed in
the borehole is 400 m/h. The water emerges at the
front nozzle of the drill stem; a 2 m-long stainless
steel rod fitted with an exchangeable drill tip (Figure
3). Two versions of the drill stem have been made,
with diameters of 32 mm and 40 mm. During opera-
tions, the hose passes over a top wheel with a diameter
of 0.25 m, fixed at the end of a 2.8 m long, inclined
tower mounted at the end of the drill housing base.
A depth counter with a digital display is connected
to the top wheel axle. Two 2 m-long pieces of steel
wire connect the drill housing and a small hydraulic
jack unit attached to the tower, thereby holding the
tower in place. A pressure meter connected to the
jack serves to measure the tension due to the com-
bined weight of the drill head and hose (useful for
verifying that the drill head and hose are hanging
freely in the borehole).
JÖKULL No. 57 73