Abstract: An apparatus is provided for converting coal to gas, liquid and solid products. The coal is subjected to a pyrolysis reaction at a temperature of at least about 260.degree. C. in the presence of a hydrogen-containing gas, and the resultant solid residue subjected to a gasification reaction with oxygen and steam at a temperature of at least about 482.degree. C. thereby generating the necessary hydrogen-containing gas for the pyrolysis reaction and producing a solid product. Heat generated in the exothermic gasification reaction is transferred to the pyrolysis reaction, so the apparatus does not require any external source of heat except for means (88) to control the temperature of the gases passing to the pyrolysis reaction chamber. The gaseous fraction generated in the pyrolysis reaction is cooled to produce liquid and gas products, preferably after having first been subjected to a Fischer-Tropsch reaction.

Abstract: A voltage or current balancing control for supplying a balanced three-phase alternating current supply to an electrical three-phase load. Three controllable full wave semiconductor gates respectively feed one phase of a three-phase alternating current supply to the electrical load. The semiconductor gates are adapted to controllably adjust the voltage or current of a phase of the supply in accordance with a gate control signal to be applied thereto. A comparator circuit is connected to receive the three-phase alternating current supply and is adapted to compare either the voltage or current characteristics, or both (power) of each phase to determine an unbalanced condition therebetween which is analyzed by an analog or digital computer, which accordingly supplies gate control signals to the semiconductor gates respectively to independently control them in accordance with the unbalanced condition to adjust the voltage and/or current of all three phases of the supply to an equal or balanced condition.