Each kettle had a heat, or energy, source under it. The Jamaica Train was a very dangerous system, requiring much manpower because it was not mechanical. The sugar produced in the old system was of a low quality, because the amount of heat going into the kettles could not be regulated. Also, in the Jamaica Train, much sugar was lost in transition from one kettle to another. Another reason that is was not economical is that it required many heat, or energy sources.
More money going into energy means less profits for the people making sugar.
The Rillieux Apparatus has many advantages over the Jamaica Train. First of all, there is no danger involved, because there is no actual physical work involved. Not much manpower is required, because it is mechanical. No sugar is lost in the system, because it is not carried by ladles over the floor from one kettle to another. Also, by lowering the amount of heat required to evaporate the sugar in the container by creating a vacume, there is again less heat required originally.