A Practical Manual On Sea Water Distillation
With A Description Of The Necessary Machinery For The Process

MULTIPLE DISTILLATION. 205 regard to cooling requirements. The steam at each distillation is condensed inside the evaporator coils, so that the only condensing duty that has to be done by the distiller is to deal with the steam that is generated by the final evaporator, and this, as we have seen, gets less and less as each evaporator is added. 77. We, therefore, have a rule, as follows, viz. :—That at each successive distillation the distiller condensing surface decreases, whilst the distiller cooling surface in- creases, and that they respectively decrease and increase in the same proportion. 78. The distilling condenser surfaces for condensing and cooling would, therefore, respectively cZecrease and in- crease, as in Table O below—i.e., assuming an increase of 80 per cent, of gained water at each successive distillation. TABLE 0. Type of Distillation. Distilling Condenser. Cooling Surface. Condensing Surface. Single Distillation, ..... Double „ Treble „ Quadruple „ Quintuple „ Sextuple „ x sq. ft. 1-8 x 2’44 x 2’95 x 3’36 x 3-69 x y sq. ft. 0’8 y 0'64 y 0'512 y 0'409 y 0-327 y 79. The above surfaces are given for theoretical re- quirements, but it is always wise not to cut down surfaces too close. Experience from what takes place with dif- ferent types and makes of machinery can alone be a guide as to the margin that is advisable to allow. The con- densing surface will be assisted by the action of the