NOVELTY - The system has a continuous flow autoclave (19) with ohmic heater (9) that heats material to elevated temperature and under pressure. The continuous flow autoclave is provided with positive displacement pumping system to drive materials in slurry in continuous flow through autoclave. The pressure let down valve portion is provided at outflow of autoclave to reduce pressure of out-flowing slurry rapidly in controlled manner. The output slurry from valve portion is passed to fluid separator to separate solid from liquid without heating/ drying.    USE - Hydrothermal dewatering system for removing moisture from coal or other carbonaceous solid fuel material such as biomass, sewage sludge and municipal solid waste in mine or cliff.    ADVANTAGE - Since the continuous flow autoclave is provided with ohmic heater to heat material to elevated temperature and under pressure, the high degree of heat recovery of the dewatering system reduces heating cost and the moisture from coal or other carbonaceous solid fuel material can be removed efficiently. The mechanical components with proven in-service reliability and longevity can be used and the bespoke fabrications can be entirely limited to non-moving portions.    DETAILED DESCRIPTION - The system has multi-staged pressure let down valve portion that is provided with pressure let down valves such that pressure of slurry is reduced towards ambient in stages. The pressure let down valve portion is provided with variable inlet and/or outlet port geometry. The ceramic or glass elements are incorporated to reduce erosion by the slurry. A fluid tank into which outflow from autoclave passes and serves as fluid brake is provided so that fluid in tank absorbs kinetic energy from outflow. A cooling heat exchanger is provided to cool heated slurry from heater. The heat exchanger is set to feed slurry to heater and thermally insulated by a surrounding vacuum tube or lagging. The cooling heat exchanger and pre-heating heat exchanger are linked in circulation loop of heat transfer fluid. The heated material outflow from ohmic heater is turned to-be-passed back alongside inflow to ohmic heater provided with ohmic heater rings. The heater outflow and heater inflow are attained in outer pipe and inner pipe. An annular electrode is located between proximal and distal annular tube sections of ohmic heater. The film of water is delivered on interior wall surfaces of autoclave pipes through which particulates flow to serve as friction-reducing lining. The pipe internal cylindrical surface for length of pipe-work is covered. The wear-reducing shunt or gravel box is provided at bend of pipe-work to minimize wear at bend, to provide rodding eye through which high pressure jetting lance or cleaning rod is inserted for cleaning maintenance. An INDEPENDENT CLAIM is included for method for carrying out hydrothermal dewatering of coal or other carbonaceous solid fuel materials at elevated pressure and temperature, involves applying pressure to the materials from positive displacement pumps and heating the flowing materials by ohmic heating to raise the temperature of the coal/water slurry quickly and uniformly.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the hydrothermal dewatering system.    Stockpile (1)    Coal crusher (3)    Sizing screen (4)    Ohmic heater (9)    Continuous flow autoclave (19)