GAS FROM STRAW.
Page 16
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How Useful Fuel Can be Obtained by Carbonizing Straw Refuse.
AVERY interesting communication has reached us from Professor R. D. MacLaurin of the department of chemistry of the Saskatchewan University, which gives a considerable amount of interesting information with regard to a method of producing gas from straw refuse.
The matter is of considerable importance to Canada, because, on the prairies, there's no wood, and the average price for either hard or soft coal , is very high. Again, there is a large amount of straw which simply goes to waste, and every autumn this straw is burnt and is regarded as having absolutely no commercial value whatever. This sounds rather curious because, in this country, the ash from the burning of the straw would be regarded as having considerable manurial value. This point, however, is not dealt with in Professor MacLaurin's information to us. Insufficiency of labour and plant to spread and turn in the ash may explain its non-use as a manure.
Carbonizing the Straw. .
In order to deal profitably with this straw, Mr. George Harrison, manager of the Saskatchewan Bridge and Iron Co., of Moose Jaw, Saskatchewan, has invented a retort for carbonizing it and any other cellulose material thereby decomposing it into combustible gases, tars and ammonia, with a carbon residue, Professor MacLaurin having undertaken the chemical work in conneetion with the development of the project. A number of experimental plants have been made, and it is hoped to get them installed on
a certain number of farms during, the present winter. The uses to which the farmer can put the products of combustion will be for lighting, heating and power in connection with his farming operations and also in connection with his , household, and he will reap benefits in other ways, in that he Will be independent of strikes of miners and also of transportation d;fficulties. Profeesor MacIiaurin suggests that, as most of the farm work in Canada is done with tractors, there an be no reason why a. couple of retorts should not be placed on a tractor, so that a constant supply of gas can be furnished to a gas container whilst, the tractor is in operation. In order to reduce the size of the retort, negotiations are at present being entered into with regard to a baling machine which will press the straw, into the shape and size of the retort, and to such a density that a bale cubing 1 ft. will contain 25 lb. of straw. . This will enable the straw to be handled very easily, and greatly facilitate the operation of the tractor. We ourselves are helping in connection with these experiments by sending out to Professor MacLaurin flexible gas holders suit
able for use in connection with this work. .
What the Straw Yields.
The retort is made out of highly refined steel, andis designed in such a shape that the gases are removable in a very short time ; it is also designed for individual use on the farm, and is of small dimensions. It consists of three oval cylinders, 1 ft. long, with a major axis of 24 ins. and a minor axis of 61ins., the retort being enclosed in a metal or firebrick casing with a firebox below. With a 'scrubber and a gaiometer, the total cost including installation is expected in Canada to be 500 dollars, about £105. Thestraw, compressed into bales the size and shape, of the retort, is placed in it, the doors are shut by a clamp, and straw is burnt in the fireplace -below: After the operation when straw is used as fuel, a certain proportion of the gas given off is used for the purpose of the carbonizing process, about 30. per cent.
054 of the total volume of the gas being utilized in this way. The gas begins to come' off at a temperature of 200 degrees Centigrade, and reaches its maximum between 500 and 600 degrees 'Centigrade. All the gas may be removed 'from the straw in about 30-45 minutes, rapidity of operation being an important factor from a commercial standpoint.
Each ton of straw priecluces between 11,000 and 1,000 cubic ft. of gas, the quantity and quality of the gas varying slightly from different kinds of Straw, The gas after generation in a retort passes into a scrubber (this being a metal cylinder 4 ft. long by 18 or 24 ins, diameter), and thence into the gas container or flexible bag. If the gas is washed and purified so that the volume ie reduced to 16,000 ecubic ft, and, as stated above, 30 per cent, be utilized in carbonizing a ton of straw, there would be a surplus of 7000 cubic ft. for every tonof 'straw carbonized. The calorific value of straw gas is approximately 400 B.T.U.s per cubic ft, so that one ton of straw would contain 4,000,000.B.T.U.s. In this country we reckon that about 250 ft. of coal-gas is equal to one gallon of petrol, and the thermal value in B.T.Ths of a gallon of petrol is calculated in the States at approximately 114,000. In this country we give it a higher, value. Taking 7000 cubic ft.. as the net output from a ton of straw, the heating value of the gas from that quantity of straw would be 2,800,000 B.T.U.s, which can bee taken as equivalent to 25 gallons of petrol.
140,000,000,000 c. ft. Going to Waste.
From every ton of straw there is obtained between eix to eight gallons of tar and ammo•niacal liquors. This tar in its crude state would pay for the cost of baling the straw, which may be approximately put down at 4s. 6d. a ton, so that the farmer would have his fuel prepared ready for nee at the cost of hauling it from the field to his retort. The carbon reSidue, of which there is about 600 lb. to a ton of straw, woulel find a ready sale as lamp-black or (in this country) a
ready i use as Manure. , It s to he doubted whether there is a sufficiency of straw unused in this country at any time to warrant experiments of the kind, but as indicative of the importance of the scheme in the U.S.A. or Canada, it may be mentioned that on the 20,000,000 acre e which are cropped annually in the three prairie 'provinces of Western Canada only and giying a yield of one ton of straw per acre, there is a total yield of straw of. 20,000,000 tons. Allowing, for washing and purifying, and for the use of about 30 per Cent, of the gas for the purpose of carbonizing the straw, there would be procurable 140,000,0005000 (one hundred and forty thousand million) cubic ft. of gas, which may be taken to be equal to 22,000000,000,000 (twenty-two million million) h.p. hours. With regard to the durability of the retort, it will be observed that the straw is carbonized at the comparatively low tern.perature. of 500 to 600 degrees. Centigrade, and it is well known that good steel or wrought iron will Withstand such a temperature prac
tically. indefinitely. . ... • .
A final word with regard to the gas itself. It is found to be utilizable in exactly the same way as coal or natural. gas. The constituents are -methane,' hydrogen and carbon monoxide. It has a slight
°deity; and has been . found quite :suitable for incan descent lamps, stoves, grates and furnaces. • . . It must be realized that conditions differ so materially in different countries that a scheme which may be feasible in Canada would not have the least ground for success over here.