CHAPTER VII

ENGINES FOR USE WITH POOR GASES

_Simplex motor_ (Fig. 45).—Although this motor works equally well with coal gas and oil, we have put off the description of it until now because it has become associated particularly with the production of poor gases, and by their help forms one of the most formidable rivals of the steam engine.

The Simplex was invented in 1884 by MM. Edouard Delamare-Deboutteville and Léon Malandin. In appearance it is of the usual four-cycle type. A lateral shaft transmits the rotation of the crank-shaft to a small crank which actuates the sliding valve. This sliding valve forms one of the principal features of the engine, and consists of a sliding iron plate pierced with two holes, one oblique regulating the ignition, and the other straight forming the admission valve. The piston having completed its first forward stroke comes back to compress the explosive mixture, and the sliding valve having advanced puts it in communication with a chamber containing two metallic points, between which a continuous stream of electric sparks is made to flow. After the explosion this cavity and the passage leading to it are filled with burnt gas, which must be driven out to prevent a miss-fire at the next stroke. This is effected by a small purging hole, through which they are driven by a fresh charge entering the cylinder.

In earlier patterns of this engine an ingenious air governor was used, but it has now been replaced by a fresh arrangement of a different pattern. This governor (Figs. 46 and 47) consists of a double pendulum, which takes up a vertical position because of the lower ball, seen in the illustration, being the heaviest. The whole pendulum is pivoted on a fixed bearing. The variation in the speed is obtained by a weighted knife blade acting on the gas-valve. The sliding valve is provided with a knife blade square at one end and pointed at the other, which catches in a notch on the pendulum, and is held by it in position so that the square end hits the end of the gas-valve and admits gas. If, however, the speed of the engine be too great the sliding valve carries its knife blade forward too soon and it does not catch in the notch, with the result that no gas is admitted as the square end is too low. The speed of the engine, therefore, tends to remain adjusted to the rate of vibration of the pendulum, which is a fixed quantity. A self-starting arrangement is provided by stopping the engine half-way back along the compression stroke, so that it is only necessary to pass an electric spark across for an explosion to occur and give it the necessary starting impetus.

MM. Delamare-Deboutteville and Malandin were the first to construct units of very great power. At the Havre Exhibition in 1889 they exhibited a Simplex engine using Dowson gas, and in 1889 they exhibited at the Paris Exhibition a 100 horse-power single-cylinder motor.

Their latest achievement in this direction is the erection of a 320 horse-power engine supplied by two Buire-Lencauchez gasogenes with poor gas. This is the largest single-cylinder gas engine in the world. The Simplex engine was the pioneer of motors using poor gas. The machine we described was for use with coal gas, and some modification has to be made in the parts when the motor is required to use gases of the Dowson type. The economy is very good, only 580 litres of coal gas or 550 grammes of anthracite being used per horse-power hour.

_Gardie motor._—We have shown how poor gases are, beyond a shadow of a doubt, cheaper than coal gas for the production of power. Many makers have therefore attempted to use it by simply adding a gas-producing plant to existing engines. Sometimes these motors were totally unsuited for these cheaply produced gases, and the result has been failure from miss-fire or irregular speed. The Crossley, Niel, and Andrews motors are exceptions, and a few others have also given fairly good results.

We described in the previous chapter the ingenious gasogene devised by M. Gardie of Nantes; the motor which is constructed for use with it is rather novel. It has two cylinders placed side by side, a compressing pump and reservoir for compressed air. The gaseous mixture arriving at a high temperature from the gasogene passes into the cylinders, and is mixed with a volume of air coming from the reservoir; these gases are compressed to about 100 lbs. on the square inch. At the entrance to the cylinders are placed two igniters of platinum heated to a white heat by an electric current at starting, but the temperature is afterwards maintained by the combustion. During the admission the gaseous mixture burns without any explosion and without raising the pressure, but considerably increasing in volume. At the commencement of the stroke the pressure in the cylinder is therefore the same as in the compressor, but it soon decreases by virtue of the expansion and driving forward of the piston.

After having exhausted themselves in doing work the gases pass out into a regenerator, which communicates their heat to the air for admission. The valves are actuated by a horizontal shaft placed above the cylinders; the cams are three in number corresponding to three valves, of which two regulate the admission of gas and air to a chamber in which they are mixed. The third valve opens the exhaust. This arrangement is not unlike that adopted by MM. Forest and Gallice for their marine oil engines.

The cylinders are surrounded by water jackets for cooling purposes, aided by air which can enter the front end when the piston is moving in its backward stroke. The hottest portion is therefore that situated at the valve end, and in which the explosion takes place. This portion is surrounded by a closed chamber forming a boiler, where steam is formed for use in the gas plant; the steam is superheated in a spiral coil placed on the top of the gasogene. As we have already stated, this system of gas production avoids the ammoniacal products, which are a constant source of trouble in other engines. The drawback lies in the compressor, which uses up about one-third of the indicated power, but the speed is exceedingly constant, and averages about 175 revolutions per minute. The consumption of gas is not very high, probably owing to the amount of heat which is absorbed from the waste gases, usually lost. A number of other engines exist of a similar type to the Gardie motor, such as the Shaw, Woodburg, Crowe, Buchett, and others, which cannot, however, consume poor gases, and which have not any distinguishing features worth mentioning.

_Bénier motor gasogene_ (Figs. 49 and 50).—We have described the Bénier gasogene, and we will now complete the description by a short notice of the motor associated with it. This motor works on the Dugald-Clerk cycle, and in general arrangement is not unlike the Dugald-Clerk motors. A special compressing cylinder is provided cast in one with the motor cylinder, and the cranks are set at 90° degrees apart from one another. The pump is double, with two pistons coupled tandem-wise in the same cylinder. One of these draws in the air and the other forces the gas into the gasogene. The air and gas thus conducted by different paths reach the mixing chamber placed behind the motor cylinder and provided with a valve. The motor cylinder has exhaust ports perforating the walls, and which are uncovered by the piston when it has moved through five-sixths of the forward stroke. It remains open during the remaining sixth and the first sixth of the return stroke. At this moment the two piston pumps have forced into the cylinder the air and gas which they contain. The mixture enters through a valve and a perforated plate, which thoroughly mixes them in the cylinder. During the return stroke the piston, having closed the exhaust ports, compresses the explosive mixture till the end of the stroke. Ignition then takes place, and the explosion drives the piston forward, and the products of combustion escape to the air directly the exhaust ports are uncovered by the piston.

By this arrangement it might happen that the explosive mixture introduced into the cylinder might escape by the open exhaust valves. M. Bénier has obviated this difficulty by a novel device. Pure air is first admitted, driving out the products of combustion; the explosive mixture which follows is only admitted when the ports are closed. This result is obtained by properly regulating the supply of air and gas from the pump. One explosion therefore occurs in every revolution.

The Bénier engine is constructed in sizes up to 100 horse-power, and also smaller ones of a few horse-power. A 5 horse-power motor consumes 800 grammes of anthracite per horse-power hour: this result is very remarkable, because great difficulty has been found in working these small engines at all with poor gas; the gas generator seems to work badly when its dimensions are so small. A 15 horse-power motor only consumes 600 grammes per horse-power hour. The Bénier combined plant shown in Figs. 49 and 50 has received a most flattering reception on the Continent, and there is good reason to believe that it will be very much more widely used in the future. We close this chapter with a table setting forth the relative merits and economy of a number of motors.

+----------+-------+-------------+------------+------+---------- | | | | | Cost | | Nature | Power | |Consumption | per | Trials Type of Engine. | of |of the | Consumption | per |horse-|conducted | Fuel. |Engine.| of Fuel. |horse-power |power | by | | | | hour. |hour, | | | | | |pence.| ----------------+----------+-------+-------------+------------+------+---------- Lenoir (1860) | Coal gas | ·9 | 2400 litres| 2700 litres| 9 |Tresca Hugon (1866) | ” | 2·07 | 5400 ” | 2600 ” | 8·5 | ” Langen and Otto | ” | ·46 | 660 ” | 1380 ” | 4·5 | ” (1867) | | | | | | Wittig and Hees | ” | 4 | 4960 ” | 1240 ” | 3·5 |Brauer (1881) | | | | | | Koerting- | ” | 2·18 | 2700 ” | 1275 ” | 3·7 |Schettler Lieckfeld | | | | | | Otto | ” | 8·34 | 9500 ” | 915 ” | 2·8 |Allard and | | | | | | Potier Dugald-Clerk | ” | 11·6 | 9700 ” | 877 ” | 2·5 |Sterne (1884) | | | | | | Lenoir (1885) | ” | 2 | 1320 ” | 655 ” | 1·9 |Tresca Simplex (1885) | ” | 9·41 | 5580 ” | 593 ” | 1·1 |Witz ” ” | Dowson | 3·66 | 6040 ” | 3300 ” | ·7 | ” | gas | | | | | Lenoir (1885) |Carburet- | 4·15 | 2·7 ” | ·65 ” | 4·5 |Tresca | ted air | | (petroleum) | | | Benz (1885) | Coal gas | 5·1 | 3600 litres| 707 ” | 1·4 | ” Atkinson (1888) | ” | 9·48 | 6000 ” | 618 ” | 1·3 |Society | | | | | | of Arts Crossley(1888) | ” | 14·74 |10,800 ” | 765 ” | 1·5 | ” ” Griffin (1888) | ” | 12·51 | 9500 ” | 786 ” | 1·5 | ” ” Charon (1889) | ” | 4·17 | 2210 ” | 530 ” | 1·1 |Witz Forest (1890) |Petroleum | 16·67 | 7 kilg. 400 | 458 grms. | 3 |Martin | spirit | | | | | Niel (1891) | Coal gas | 3·75 | 1250 ” | 402 litres| ·8 |Witz Simplex (1889) | Poor gas | 75 |191 cub. met.| 2370 ” | ·7 | ” ” (1893) | ” |220 |110 kilg. | 500 grms. | ·3 |Leblan | | |(anthracite) | | | Lenoir (1891) | Coal gas | 6 | 4260 | 710 litres| 1·5 |Lencauchez Charon (1892) | ” | 7·5 | 4380 | 586 ” | 1·2 |Chauveau Priestman (1890)| Daylight | 7·7 | 3 kilg. | 385 grms. | 1·7 |Unwin | oil | | | | | ” (1891)|Russoline | 6·7 | 2 kilg. 700 | 428 ” | 1·9 | ” Crossley (1892) | Dowson |148 | 415 kilg. | 280 ” | ·2 |Dowson | gas | |(anthracite) | | | Atkinson (1892) | ” | 16·7 | 6·6 kilg. | 455 ” | ·3 |Tomlinson Schleicher-Schum| Poor gas | 92 | 55 ” | 596 ” | ·32 |Spanglon Trusty |Petroleum | 4·3 | 1·83 ” | 440 ” | 2·2 |Beaumont |(ordinary)| | | | | Delamare- |Lencauchez| 62 | 37 ” | 603 ” | ·2 |Bourdon Deboutteville | gas | | |(cheap coal)| | (1894) | | | | | | Campbell (1895) |Petroleum | 6 | 2·4 ” | 400 grms. | 2·5 | ” |(ordinary)| | | | | ----------------+----------+-------+-------------+------------+------+---------- The price of fuel has been calculated from prices current at the dates given.