EXPERIMENTAL PRODUCTION OE STRAW GAS. 9 
IMPROVEMENT OF EXPERIMENTAL EQUIPMENT. 
Much could be done to lower the cost of, simplify, and improve 
the experimental equipment used. 
The brick arch and walls incasing the retort are effective in con- 
serving heat, but their initial cost is high, as well as their cost of 
upkeep in case it is necessary to repair or replace the retort. The 
retort would probably last for four or five years when used to produce 
300.000 cubic feet of gas per year and subjected to the heat of straw 
burned in the fire box. The retort is very inaccessible under the 
present arrangement. A sheet-iron casing, similarly shaped and 
covered with heavy layers of asbestos, inclosing a readily replaceable 
retort or baking chamber, would be more practicable from every 
standpoint. The main gas line could be 2-inch piping, with attach- 
ment to the retort on top at its center. 
The front end of the retort should be equipped at the top with a 
single large gas-tight charging door which can be readily opened 
and closed. A similar door should be placed at the bottom to permit 
easy and rapid removal of the carbon residue after the charge has been 
carbonized. For the exclusive burning of straw, the fire box should 
be equipped with a regular straw-firing door. 
The return flue, while increasing the cost of the retort, slightly 
decreasing its volumetric capacity, and making the charging opera- 
tion more laborious, permits a more even and rapid carbonization of 
the charge. 
Everything considered, the gas burners, as arranged in the fire box, 
were not entirely successful, and the burning of straw in the fire box 
seemed to be more satisfactory. 
While effective, the scrubber is bulky and expensive, with an in- 
terior not readily accessible, A better arrangement would be a se- 
parate, compact water-cooled condenser, and. a separate scrubber 
which could be much smaller than the one used. Such equipment 
would cost less and at the same time result in a more effective and 
satisfactory recovery of tar, heavy oils, and ammoniacal liquors. On 
account of the size and thickness of the main gas line, there is a 
tendency for the tar to condense and collect in the gas outlet and 
elbow at the front of the retort. 
A retort the size of that in the experimental unit would require a 
gasometer having a capacity of at least 400 cubic feet. It could be 
constructed of lighter material than that used and could be made 
more compact by making the lower bell upright instead of inverted. 
Gasometers are expensive, bulky, and somewhat troublesome, especi- 
ally during the winter when antifreezing solution must be kept in the 
water compartment. The question arises as to the most satisfactory 
method of storing the gas, for which several other devices suggest 
themselves. A steel tank in which the gas could be stored at a pres- 
sure of, say, 75 to 100 pounds per square inch, or an impervious can- 
vas-rubber bag, similar to those used in England during the*World 
War on motor busses driven by coal gas, might be more practicable. 
