The invention of a self propelling engine, capable of working without
fuel economically and for a considerable time, has often been attempted,
and was, perhaps, never before so nearly accomplished as about the time
of the introduction into practical use of Faure's electric storage
batteries; but at the present moment it appears that electric power has
to give way once more to steam power. Mr. Honigmann's invention of the
fireless working of steam engines by means of a solution of hydrate of
soda--NaO HO--in water is not quite two years old, and has in that time
progressed so steadily towards practical success that it is reasonable to
expect its application before long in many cases of locomotion where the
chimney is felt to be a nuisance. The invention is based upon the
discovery that solutions of caustic soda or potash and other solutions in
water, which have high boiling points, liberate heat while absorbing
steam, which heat can be utilized for the production of fresh steam. This
is eminently the case with solutions of caustic soda, which completely
absorb steam until the boiling point is nearly reached, which corresponds
to the degree of dilution. If, therefore, a steam boiler is surrounded by
a vessel containing a solution of hydrate of soda, having a high boiling
point, and if the steam, after having done the work of propelling the
pistons of an engine, is conducted with a reduced pressure and a reduced
temperature into the solution, the latter, absorbing the steam, is
diluted with simultaneous development of heat, which produces fresh steam
in the boiler. This process will be made clearer by referring to the
following table of the boiling points of soda solutions of different
degrees of concentration, and by the description of an experiment
conducted by Professor Riedler with a double cylinder engine and tubular
boiler as shown in Fig. 2:
+---------------------+------------------+----------------------
| | Boiling point in | Steam pressure above
| Solution of soda. | Centigrades. | atmospheric pressure
| | | in atmospheres.
+---------------------+------------------+----------------------
|100 NaO HO + 10 H2O | 256 deg. C. | 40 atm.
| " + 20 " | 220.5 " | 21 "
| " + 30 " | 200 " | 15 "
| " + 40 " | 185.5 " | 10.2 "
| " + 50 " | 174.5 " | 7.7 "
| " + 60 " | 166 " | 6.1 "
| " + 70 " | 159.5 " | 5.1 "
| " + 80 " | 154 " | 4.2 "
| " + 90 " | 149 " | 3.6 "
| " + 100 " | 144 " | 3.0 "
| " + 120 " | 136 " | 2.2 "
| " + 140 " | 130 " | 1.6 "
| " + 200 " | 120 " | 0.95 "
| " + 300 " | 110.3 " | 0.4 "
| " + 400 " | 107 " | 0.3 "
+---------------------+------------------+----------------------
_Experiment No. 15_.[3]--The boiler of the engine, Fig. 2, was filled
with 231 kilogs. water of two atmospheres pressure and a temperature of
about 135 deg. Cent.; the soda vessel with 544 kilogs. of soda lye of
22.9 per cent. water and a temperature of 200 deg. Cent., its boiling
point being about 218 deg. Cent. The engine overcame the frictional
resistance produced by a brake. At starting the temperature of both
liquids had become nearly equal, viz., about 153 deg. Cent. The
temperature of the soda lye could therefore be raised by 47 deg. Cent,
before boiling took place, but, as dilution, consequent upon absorption
of steam would take place, a boiling point could only be reached less
than 218 deg. Cent., but more than 153 deg. Cent. The engine was then set
in motion at 100 revolutions per minute. The steam passing through the
engine reached the soda vessel with a temperature of 100 deg. Cent.; the
temperature of the soda lye began to rise almost immediately, but at the
same time the steam boiler losing steam above, and not being influenced
as quickly by the increased heat below, showed a decrease of temperature.
The difference of the two temperatures, which was at starting 1.3 deg.
Cent., consequently increased to 7.2 deg. Cent, after 17 min., the boiler
having then its lowest temperature of 148.8 deg. Cent. After that both
temperatures rose together, the difference between them increasing
slightly to 9.5 deg. Cent., and then decreasing continually. After 2 hours
13 min., when the engine had made 12,000 revolutions, the soda solution
had reached a temperature of 170.3 deg. Cent., which proved to be its
boiling point. The steam from the engine was now blown off into the open
air during the next 24 min. This lowered the temperature of both water
and soda lye by 10 deg. and re-established its absorbing capacity. The
steam produced under these circumstances had of course a smaller pressure
than before, in this way the engine could be driven at reduced steam
pressures until the resistance became relatively too great. The process
described above is illustrated by the diagram Fig. 1, which is drawn
according to the observations during the experiment.
[Footnote 3: Zeitschrift d. Vereins Deutscher Ingenieur, 1883, p. 730;
1884, p. 69.]
[Illustration: FIG. 1.]
[Illustration: FIG. 2.]
The constant rise of both temperatures during the first two hours, which
is an undesirable feature of this experiment, was caused by the quantity
of soda lye being too great in proportion to that of water, and other
experiments have shown that it is also caused by an increased resistance
of the engine, and consequent greater consumption of steam. In the latter
part of the experiment, where the engine worked with expansion, the rise
of the temperature was much less, and by its judicious application,
together with a proper proportion between the quantities of the two
liquids in the engines, which are now in practical use, the rising of the
temperatures has been avoided. The smaller the difference is between the
temperatures of the soda lye and the water the more favorable is the
economical working of the process. It can be attained by an increase of
the heating surface as well as by a sparing consumption of steam,
together with an ample quantity of soda lye, especially if the steam is
made dry by superheating. In the diagrams Figs. 3 and 4, taken from a
passenger engine which does regular service on the railway between
Wurselen and Stolberg, the difference of the two temperatures is
generally less than. 10 deg. Cent. These diagrams contain the
temperatures during the four journeys _a b c d_, which are performed with
only one quantity of soda lye during about twelve hours, and show the
effects of the changing resistances of the engine and of the duration of
the process upon the steam pressure, which, considering the condition of
the gradients, are generally not greater than in an ordinary locomotive
engine. It can especially be seen from these diagrams that an increase of
the resistance is immediately and automatically followed by an increased
production of steam. This is an important advantage of the soda engine
over the coal-burning engine, in consequence of which less skill is
required for the regular production of steam power. The tramway engines
of more recent construction according to Honigmann's system--Figs. 5 and
6--are worked with a closed soda vessel in which a pressure of 1/2 to 1½
atmospheres is gradually developed during the process. While the counter
pressure thus produced offers only a slight disadvantage, being at an
average only 1/2 atmosphere, the absorbing power of the soda lye is
materially increased, as shown by the following table, and it is,
therefore, possible to work with higher pressures than with an open soda
vessel. Besides this great advantage, it is also of importance that the
pressure in the steam boiler can be kept at a more uniform height.
[Illustration: FIG. 3.]
[Illustration: FIG. 4.]
TABLE.--100_kilogs. Soda Lye containing 20 parts Water with a
corresponding boiling point of 220 deg. Cent. absorb Steam as follows_:
+----------------------------------+--------------+---------------+
|Final pressure in condenser. | | |
+----------------------------------+Pressure in |Corresponding |
| 0 | ½ atm. | 1 atm. | 1½ atm.|steam boiler. | temperature. |
+----------------------------------+--------------+---------------+
|80 kil.|125 kil.|200 kil.|350 kil.| 2 atm. | 136.0 deg. C. |
|65 " | 88 " |130 " |190 " | 3 " | 143.0 " |
|51 " | 70 " | 98 " |125 " | 4 " | 153.3 " |
|41 " | 58 " | 80 " |100 " | 5 " | 160.0 " |
|34 " | 48 " | 66 " | 80 " | 6 " | 166.5 " |
|27 " | 40 " | 55 " | 70 " | 7 " | 172.1 " |
|22½ " | 33 " | 47 " | 60 " | 8 " | 177.4 " |
|19 " | 28 " | 41 " | 52 " | 9 " | 182.0 " |
|16 " | 24 " | 35 " | 46 " | 10 " | 186.0 " |
|12 " | 18 " | 28 " | 35 " | 12 " | 193.7 " |
| 9 " | 14 " | 22 " | 33 " | 15 " | 200.0 " |
| 2 " | 8 " | 12 " | 21 " | 20 " | 215.0 " |
+-------+--------+--------+--------+--------------+---------------+
Not the least important part of the process with regard to its economy is
the boiling down of the soda lye in order to bring it back to the degree
of concentration which is required at the beginning of the process. This
is done in fixed boilers at a station from which the engines start on
their daily service, and to which they return for the purpose of being
refilled with concentrated soda lye. It is clear that a closed soda
vessel has produced as much steam when the process is over as it has
absorbed, and the quantity of coal required for the evaporation of water
in concentrating the soda lye can therefore be directly compared with
that required in an ordinary engine for the production of an equal
quantity of steam. The boiling down of the soda lye requires, according
to its degree of concentration, more coal than the evaporation of water
does under equal circumstances, and disregarding certain advantages which
the new engine offers in the economy of the use of steam, a greater
consumption of coal must be expected. But even at the small installation
for the Aix la Chapelle-Burtscheid tramway with only two boilers of four
square meters heating surface each, made of cast iron 20 mm. thick, 1
kilog. of coal converts 6 kilogs. of water contained in the soda lye into
steam, while in an ordinary locomotive engine of most modern construction
the effect produced is not greater than 1 in 10. There can be no doubt
that better results could be obtained if the installation were larger,
the construction of the boilers more scientific, and their material
copper instead of cast iron; but even without such improvements the cost
of boiling down the soda lye might be greatly lessened by the use of
cheaper fuel than that which is used in locomotive engines, and by the
saving in stokers' wages, since stokers would not be required to
accompany the engines.
[Illustration: FIG. 5]
[Illustration: FIG. 6]
Apart from these considerations, the Honigmann engines have the great
advantage that neither smoke nor steam is ejected from them, and that
they work noiselessly. The cost of the caustic soda does not form an
important item in the economy of the process, as no decrease of the
original quantities had been ascertained after a service of four months
duration. Besides the passenger engine already referred to, which was
tested by Herr Heusinger von Waldegg[4] in March, 1884, and which since
then does regular service on the Stolberg-Wurselen Railway, there are on
the Aix la Chapelle-Julich railway two engines of 45,000 kilogs. weight
in regular use, which are intended for the service on the St. Gothard
Railway. Their construction is illustrated in Figs. 7 and 9, and other
data are given in a report by the chief engineer of the Aix la
Chapelle-Julich Railway, Herr Pulzner, which runs as follows:
Wurselen, Dec. 23, 1884.
[Footnote 4: Z.d.V.D.I., 1884, p. 978]
[Illustration: DIAGRAMS FOR THE CALCULATION OF STRESSES IN BOWSTRING
GIRDERS.]
A trial trip was arranged on the line Haaren-Wurselen, the hardest
section of the Aix la Chapelle-Julich Railway. This section has a
gradient of 1 in 65 on a length of 4 kilos; and two curves of 250 and 300
meters radius and 667 meters length. The goods train consisted of
twenty-two goods wagons, sixteen of which were empty and six loaded. The
total weight of the wagons was 191,720 kilogs., and this train was drawn
by the soda engine with ease and within the regulation time, while the
steam pressure was almost constant, viz., five atmospheres. The greatest
load admissible for the coal burning engines of 45,000 kilogs. weight on
the same section is 180,000 kilogs.
[Illustration: FIG. 7.]
[Illustration: FIG. 8.]
Proof is therefore given that the soda engine has a working capacity
which is at least equal to that of the coal burning engine. The heating
surface of the soda engine, moreover, is 85 square meters, while that of
the corresponding new Henschel engine is 92 square meters. On a former
occasion I have already stated that the soda engine is capable not only
of performing powerful work and of producing a large quantity of steam
during a short time, but also of travelling long distances with the same
quantity of soda. Thus, for example, a regular passenger train, with
military transport of ten carriages, was conveyed on Nov. 6, 1884, from
Aix la Chapelle to Julich and back, i.e., a distance of 45 kilos, by
means of the fireless engine. The gradients on this line are 1 in 100, 1
in 80, and 1 in 65, being a total elevation of about 200 meters. For a
performance like this a powerful engine is required, and a proof of it can
be recognized in the consumption of steam during the journey, for the
quantity of water evaporated and absorbed by 4½ to 5 cubic meters soda
lye was 6,500 liters.
Another certificate concerning the tramway engine illustrated in Figs. 5
and 6 is of equal interest, and runs as follows:
Aix la Chapelle, Jan. 5, 1885.
A fireless soda engine, together with evaporating apparatus, has been at
work on the Aix la Chapelle-Burtscheid tramway for the last half year. In
order to test the working capacity of this locomotive engine, and the
consumption of fuel on a certain day, the Honigmann locomotive engine was
put to work this day from 8:45 o'clock a.m. till 8 o'clock p.m., with a
pause of three-quarters of an hour for the second quantity of soda lye.
The engine was, therefore, at work for fully 10½ hours, _viz._, 5½ hours,
with the first quantity, and five with the second. The distance between
Heinrichsalle and Wilhelmstrasse, where the engine performed the regular
service, is 1 kilo, and there are gradients
Of about 1 in 30 in 400 meter length.
" 1 " 45 " 250 "
" 1 " 72 " 350 "
This distance was traversed sixty-four times, the total distance,
including the journeys to the station, being 66 kilos. The engine gives
off fully 15-horse power on the steepest gradient, the total traction
weight being 8½ to 9 tons; it is worked with an average steam pressure of
5 atmospheres, and has cylinders of 180 mm. diameter and 220 mm. stroke,
cog wheel-gear of 2 to 3, and driving wheels of 700 mm. diameter. The
quantity of water evaporated during the service time of 10½ hours was
found to be about 1,600 kilogs., consequently about 800 kilogs. steam was
absorbed by one quantity of soda, the weight of which was ascertained at
about 1,100 kilogs. The averaging heating surface is 9.8 square meters;
the difference of temperature between soda lye and water was toward the
end only 3 deg. Cent.; 234 kilogs. pitcoal were used for boiling down the
lye for the 10½ hours' service, which corresponds to a 6.6 fold
evaporation.
(Signed) M.F. GUTERMUTH,
Assistant for Engineering at the Technical High School.