Oil Engines That Have Seen Long Water Works Service
Three Units Installed in City of Clayton in 1911, 1912 and 1917, Respectively—Still Giving Good Satisfaction—Record of Service
WHILE much has been published in these columns on the subject of oil engine performance the following article is unique in giving the record of three units which have been installed for several years and have given good satisfaction during that period. The article will give a very good idea of the reliability of this type of motive power:
During the past twenty, and especially during the last ten years, the oil engine has been forcing its way into the water pumping field, solely upon its own merits, having long since reached a point in its development where it has proven its reliability and its operating efficiency can no longer be questioned. In comparatively recent years, many installations of Diesel, semi-Diesel and low compression oil engines, some of them of fairly large size, have been made for water pumping service, and it is interesting to note that practically all of them have given, not only reliable service, but much more economical service than could generally be obtained from other types of prime movers. This is especially true of the oil engines of the larger sizes, and both large and small engines manufactured by firms whose designs are the result of years of experience.
Cause of Unsatisfactory Service
It has been the writer’s observation that what little unsatisfactory service that has been reported from oil engine users, not only in water pumping service, but in other service as well, is directly traceable to one or the other of two causes; first, lack of competent attendance and supervision of the equipment and second, the installation of equipment of defective or untried design. Fortunately difficulties from the latter cause, in recent years have not been numerous because of the simple reason that makers of a cheap or inferior engine have not been able to sell their product in competition with those of proven designs. However, to my knowledge, there have been a few unfortunate instances where incompetent operators have brought much unjust condemnation upon perfectly good oil engine installations.
Good Records Should Be Published
In view of the present wide use of the oil engine and its much more general use that we may reasonably expect in the future, it is regrettable that so little information of general
interest covering such installations is given through our many trade publications. Of course the makers of oil engines have given much publicity to the remarkable operating records of some of their equipment, but many readers, especially some who may be inclined to be prejudiced in the matter, are inclined to view the manufacturers publicity in the light of advertising propaganda. The users of the equipment, themselves, too often seem to be entirely indifferent, so far as publicity is concerned, of operating records of which they may justly be proud. Aside from the pride these men may feel in the results they have been obtaining, there is another reason why an expression from them would be of interest and of practical benefit to other men engaged in the same line of work. The day is long since past when the engineer should be secretive of the knowledge and experience he has gained, and by no better means than expression through our trade journals, can the knowledge that comes from careful study and actual experience, be disseminated among our fellow workers.
Good Results from Early Installation
Among many engineers the opinion seems to prevail that it is only in very recent years that the oil engine has proven its reliability and economy, an opinion that is erroneous to say the least. But for the good results obtained from many of the early installations, the oil engine today would not hold the prominent place it does in the field of power development. While there have been marvelous improvements in the oil engine in the last ten years, the fact remains that these improvements have been largely in the nature of refinements in design, better workmanship and more suitable materials of construction, and but little has been effected toward increasing the thermal efficiency. It is not the intention to argue that the modern oil engine is not superior to the older types, because it has been through these refinements that the oil engine has been able to establish its reputation, not only as the heat engine of the highest thermal efficiency, but as one of the most reliable and most economical as regards total costs of operation. However, there are many old oil engines in different parts of the country, still in service that consistently continue to give a good account of themselves, a brief description of one of such installations, though of small size may be of interest.
The Three Clayton Units
In the power plant of the Clayton, N, M., municipal water and light department, are two 90 h. p. and one 180 h. p. oil engines. These arc all single cylinder, horizontal, four cycle engines with air injection of fuel, a cylinder compression of about 275 lbs. per sq. in. with ignition assisted by a hot ball, known as the Type FH, manufactured by the De La Vergne Machine Company, of New York City. Each of these engines is belted to an alternator, the 90 h. p. engines each driving 75 KVA alternators and the 180 h. p. engine, a 125 KVA alternator, all the alternators being 2,200 volt, .3 phase, 60 cycle machines. Excitation is furnished by individual belted exciters on the two 75 KVA alternators and by a direct connected exciter for the 125 KVA machine.
The first 90 h. p. unit was installed in 1911, the second in 1912, and the 180 h. p. unit in 1917. Fuel oil is unloaded from tank cars at a siding some 200 feet from the plant, piped to and stored in two 10,000 gal. underground tanks at the rear of the plant building, from which it is pumped by motor driven rotary pumps as needed into a small service tank of about 100 gallons capacity located in the plant building. As pumped to the service tank the fuel is metered, and the meter registrations are regularly checked by measurements of the underground storage tanks. All three engine fuel pumps are supplied by gravity from this service tank and no records are kept of the fuel consumption of each individual unit. Fuel oils ranging from 24 to 32 degree Baume are used, and the only difficulty experienced from the fuel oils has been some trouble in handling the heavier oils through the pipe lines in serverely cold weather, due to lack of adequate arrangements for heating the oil. For this reason it is the practice to use oils above 30 degree Baume for at least four months of the winter.
How Cooling Water Is Furnished
On the roof of the plant building is a tank of about 50 bbl. capacity, over which is built a cooling tower. Cooling water for the engines flows by gravity from this tank, through the engine jackets discharging into a municipal bathing pool near tinplant, which has a capacity of about 225,000 gal. Frotn this pool the cooling water is pumped continuously by a small motor driven centrifugal pump back to the cooling tower and tank on the plant roof. Emergency cooling water
is also piped directly to the engines from the city mains, for use in case of failure of the regular cooling arrangement. To avoid possible danger from lack of cooling water, an electric alarm system is installed, operated by a float in the tank on plant roof, which gives notice to the plant operators by ringing a bell when the water level drops below a predetermined point. This alarm is given some 15 minutes before the cooling water supply can become exhausted, thus giving ample time to either remedy the trouble or turn on the water from the high pressure city mains. This alarm system has also been extended to notify the operators in case the rotary fuel pumps fail to keep the service tank properly supplied.
Oil Purified by Reclaimer
A De La Vergne oil reclaimer is in use through which all the used lubricating oil is purified for further use. Oil for the crank pins, air compressor eccentrics and shaft bearings is supplied by gravity from the overhead reclaimer storage tank, and the cylinders are lubricated by force feed lubricators driven from the engine cam shafts. A regular schedule is maintained for grinding valves, checking wear of bearings, removal of scale from water jackets and inspection and repair of the entire plant equipment.
The plant switchboard consists of three combined generator and exciter panels, four feeder panels and one voltage regulator panel. Suitable voltmeters, ammeters, frequency indicator and synchronizing indicators are provided and a watt hour meter that registers the entire plant output, however no watt hour meters are installed for measuring the output of each individual unit. Watt hour meters are also installed on each of three feeder circuits; one supplying the municipal street lights, another power and light for the power plant building and the third, power for all the pumps of the water department. The various feeder circuits supplying commercial light and power over the town are unmetered.
All Pumping Equipment Motor Driven
All the pumping equipment of the water department, is electric-motor driven. The principal source of water supply is from a small stream about three miles from town, although three old wells are still maintained in operating condition, which range in depth from 250 to 600 feet, these being used only as an emergency supply. At the pumping plant at the creek a small triplex and a centrifugal pump are installed, both direct connected to motors, which deliver water to an underground reservoir at the plant which has a capacity of 500,000 gal. A transmission line extends from the plant to the creek pumping station to supply current to the motors. At the time the creek pumping installation was made, the writer was freely and unfavorably criticised because of his decision to control the pumping equipment entirely from the power plant. It was necessary from economic reasons to keep the cost of operation of this pumping equipment as low as possible and the most expedient way appeared to be to eliminate the expense of wages of operators. Since it was necessary to operate but one pump at a time, a starting compensator was installed in the power plant building at one end of the switchboard, through which the transmission line leading to the creek pump motors was connected. By means of this compensator the motors at the pumping station may be started or stopped at any time by the plant engineers. For protection, a no voltage release and inverse time limit overload relays are provided with the starting compensator, and a watt-hour meter and an ammeter give the plant engineers some indication of the operation of motors. Provision is made at the pumping station to insure that the pumps will always be primed, but should one fail to draw water immediately upon starting, the ammeter indication gives notice of trouble. It is the practice to inspect the pumping station equipment every two or three days to see that bearings are oiled and when the triplex pump is in operation it is usually visited every day. In spite of the fact that one or the other of the creek pumps is in operation from 16 to 20 hours each day, no serious difficulties or troubles have developed in the four years that this plant has been in operation.
From the half million gallon underground storage reservoir at the power plant, the water is pumped as needed into the mains and a 75.000 gal. steel tower tank 140 feet high, by duplicate centrifugal pumps direct connected to electric motors, located inside the power plant building. The total connected motor load of the water department including the motors driving the deep well working heads, that are merely a reserve and seldom used, is 155 h. p. The total lift in pumping water from the creek pumping station to the elevated steel tower tank is about 290 feet and in normal operation, including friction loss in the long pipe line, the actual pumping head is approximately 310 feet.
Summary of Power Plant Report
The following summary of the power plant report for the month of January, 1924, is quite typical of the average results obtained from this old plant.
Fuel consumed …………………… 5253 Gal.
Lubricating oil used ……………… 71.75 Gal.
KWHrs. generated per gal. fuel …….. 3.39 KWHrs.
KWIIrs. generated per gal. lubricating oil 552.1 KWHrs.
KWIIrs. used for water pumping ……. 15530 KWHrs.
Water pumped …………………… 618570 Cu. Ft.
Water pumped …………………… 4639275 Gal.
KWHrs. used per M gal. water pumped 3.34 KWHrs.
This plant is operated 24 hours per day, and in common with many or practically all small plants, the expense of labor is by far the largest item. During the year 1923, the entire expense for repairs in this plant, excluding the water pumping equipment, but including engines, generators, belting, exciters and switchboard was $542.18. More than half of this amount was for a rather extensive overhauling of one of the small engines, when a number of new parts including a cylinder liner were purchased.
Satisfactory Fuel Consumption Per Unit
Considering the fact that these engines are all belted to their generators and that from the nature of our load it is necessary to operate them for a large part of the time at load factors ranging from 50 to 70 per cent., the fuel consumption per unit output is very good, in fact closely approaching that of modern direct connected units. The best fuel economy ever obtained in the last two years was for the month of October 1923, when 8.83 kw. hrs. was obtained per gallon of fuel and the lowest in May of the same year when the output was but 7.63 kw. hrs. per gallon of fuel.
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Oil Engines of Long Water Works Service
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In starting these engines, it is necessary to heat a bulb by means of a torch and usually requires from ten to fifteen minutes to bring a machine up to speed and synchronize its alternator with the other units in operation. In spite of this handicap, for more than twenty months the current has never been off the switchboard buss bars, which the chief engineer and the operators consider to be an unusually good record. Of coure there have been shut downs of units in Ibis time due to minor trouble, but none in the nature of breakdowns that have caused interruptions to the electrical service before other units could be put on the line.
New Pumper for Hamden—Hamden, Conn., has purchased a Stutz combination hose and pumper with a 70-gallon booster attachment.