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Matthias, F. T. (ed.) / The Wisconsin engineer
Volume 33, Number V (February 1929)

Engineering review,   pp. 170-171


Page 170


1The WISCONSIN ENGINEER
Volume 33, No. 5
IElnneerinr Pviewi
             .a   ..         He                     w  w And~~I-l
STEAM GENERATED FROM HIGH
        VOLTAGE CURRENT
   The Swedish Institute of Industrial
 and Engineering Research is carrying
 out experiments in generating steam
 from high-voltage electric current (50,-
 000 to 80,000 volts). If successful,
 the great surplus energy of the water-
 falls of Sweden could in this way be
 utilized  to  advantage.  A  tension
 higher than 30,000 volts cannot be
 used by the electric boilers in present
 use, but this method of generating
 steam will become remarkably cheap
 it the costly transformation from
 transformation-line voltage can be
 avoided. Industries which are very
 large consumers of steam, such as the
 pulp mills, would benefit by this ar-
 rangement.
      A GIBRALTAR TUNNEL
   Now that the eyes of Europe are
turned toward Africa as the next
field for commercial exploitation the
idea of digging a tunnel under the
Strait of Gibraltar comes to the front.
The scheme appears more practicable
than formerly in view of the success
in construction of the Hudson River
tunnel; the second Simplon tunnel, 12
miles long, and the Shandaken tunnel
of the New York water supply, 18
miles long. A Spanish engineer, Iba-
nex de Ibero, has prepared a plan
which he thinks could be carried out
within five years at a cost of $70,-
000,000. He estimates that the traffic
would by 1934 be enough to pay
dividends on that sum.
  The northern approach to the tun-
nel will not be of course Gibraltar,
since that is British territory. Nor will
it be located at Tarifa, although this
is the nearest point to Africa, for the
depth of the straits at this crossing
is 3,300 feet.  But from   Vaqueros
Bay, west of Tarifa, a tunnel could
be constructed no more than 1,300
feet below sea level at any point, and
by running to Tangier, an interna-
tional port, would pass for 19 miles
undersea with about 10 miles of
approaches.
   When, or if, the French construct
 their proposed railroad across the
 Sahara from Tangier to Dakar on
 the extreme western projection of
 Africa, the journey from Paris to
 Brazil may be reduced to three days
 -by rail and four days or fewer by
 sea.                      -Collier's
       COAL DUST ENGINES
   The successful operation of the
Pawlikowski powdered coal engine
proves that Doctor Diesel's original
patent on the internal combustion en-
gine was sound, even though he was
forced to turn to oil for satisfactory
operation. That the two engines now
using coal dust at Gorlitz, Germany,
are beyond the experimental stage is
attested by impartial American engi-
neers who have seen the machines in
action.  The  original unit was a
single cylinder machine, 16.5" by 25",
and rated at 80 HP. To this has been
added a three cylinder unit of 180 HP.
capacity.
  In operation of the engine, coal is
fed into a hopper which is heated by
the exhaust gases to dry the coal.
From the hopper this coal is fed to
a grinder, where it is pulverized until
80 per cent of it will pass a 100
mesh screen. A blower then conveys
the crushed coal to a separator above
the cylinder head, where the coarser
particles are returned to the grinder,
and the finer particles are kept in
suspension by the air currents until
they are deposited in the feed hopper
immediately above the cylinder head.
From the hopper outlet the coal dust
is conveyed to the fuel valve by a
screw conveyor, and the engine is pro-
vided with a second conveyor to carry
the excess fuel back to the hopper
outlet, thus providing a constant
stream of fuel over the inlet valve,
and the speed of the conveyors is
such that the fuel is kept well mixed
with air.
   The fuel valve is the most ingenious
 part of the whole layout. It consists
 of a double valve, with an outlet to
 the air provided for insuring no more
 than atmospheric pressure in the com-
 bustion chamber when the fuel is to
 be injected into an auxiliary chamber
 connecting with the clearance space
 of the engine. The action described,
 and the closing of the relief port to
 the atmosphere, followed by the in-
 jection of fuel to the auxiliary cham-
 ber, takes place during the suction
 stroke of the engine, and the entire
 fuel valve is closed when compression
 begins.  Just before head end dead
 center on the compression stroke a
 fuel valve injects a minute quantity
 of fuel oil into the auxiliary chamber,
 and at the same time an air valve is
 opened and the mixture of coal and
 oil is injected into the cylinder proper
 by the air blast. The ignition of the
 oil insures the ignition of the coal
 charge.
 The combustion proceeds as in the
 oil Diesel, and the piston moves on
 the power stroke. At approximately
 bottom dead center the hot gas ports
 to the coal drier are opened, and air
 from a scavenging pump is directed
 across the piston to clear it of ash.
 It has been found that this scouring
 is not needed, and that ash is kept
 off the piston through the use of more
 lubricating oil which is later reclaimed.
 On the exhaust stroke air is blown
 through a port higher in the cylinder
 to scour the ash off the piston and
 force it through the exhaust ports.
 From experiments with and without
 these jets it has been found that lub-
 rication within the cylinder walls.
 The success of this engine is due
 chiefly to the design of the fuel inlet
 valve and the use of a small charge
 of oil to insure ignition. In former
 designs the fuel caked about the inlet
valve and refused to enter the cylin-
170


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