Hot-gas pressure-filter apparatus

A method for operating a temperature controllable and pressurizable fixed volume pressure filter apparatus formed with an openable filtration chamber for separating a quantity of slurry (124) into slurry solids and slurry liquids to form a substantially dry slurry solids filter cake, said apparatus comprising:

• at least one pressure sealable fixed volume filtration chamber (120) consisting of an upper inlet plate (100) having an inlet cavity (106), a lower outlet plate (102) having an outlet cavity (116), said inlet plate and outlet plate having continuous mating surfaces to form a sealable internal cavity, said inlet plate having entry port means (108) into said sealable internal cavity and said outlet plate having exit port means (118) for exit from said internal cavity, said lower outlet plate including a fixed porous support grid (112) adjacent to said mating surfaces, said filtration chamber of fixed volume being formed between the interior of said inlet cavity and the surface of said porous grid when said mating surfaces of said inlet plate and outlet plate are sealed against each other, means for opening and closing said filtration chamber by relatively moving said upper and lower plates,
• a movable porous filter medium (104), said medium being disposed within said filtration chamber between said continuous mating and sealing surfaces of said upper and lower plates and supported on said fixed porous support grid when said filtration chamber is closed and movable through said filtration chamber when said filtration chamber is open,
• means for moving said filter medium through said filtration chamber when said filtration chamber is open,
• a source of slurry, said source of Slurry (124) coupled with said at least one filtration chamber through said input port means when said plates are closed,
• at least one source of temperature controllable and pressurizable fluid (126,128,130,132) coupled with said at least one filtration chamber through said input port means when said plates are closed,
• separate valving means (A,B,D,E,F) for controlling entry of said slurry and said temperature controlled and pressurizable fluid into said at least one filtration chamber after each closing of said filtration chamber,
• means for controlling said separate valving means (80) to uniformly distribute aid slurry into said filtration chamber after each closing of said filtration chamber and for introducing said temperature controllable and pressurizable fluid into said filtration chamber at predetermined pressure and temperature when said filtration chamber is closed for separating slurry liquid from said slurry and passing said separated slurry liquid through said exit port means to form said slurry solids filter cake on said filter medium,
• and means for moving said filter medium through said filtration chamber after each closing of said filtration chamber and when said filtration chamber is open by separation of said plates for discharging said slurry solids filter cake (104) from said apparatus,
• the method including the steps of:
• a) after each closing of said upper and lower plates to establish said at least one pressure sealable fixed volume sealed filtration chamber with said filter medium supported within said filtration chamber between said continuously mating surfaces, uniformly distributing said quantity of slurry (124, B, 108) in said at least one sealed filtration chamber (120) after said closing of said filtration chamber, pressurizing and temperature controlling said sealed filtration chamber to a predetermined pressure and temperature,
• b) after forming said sealed filtration chamber forcing a first portion of said slurry liquid from said distributed slurry through the said filter medium (104) and through said exit port means in said sealed filtration chamber with a first quantity of said predetermined temperature controllable and pressurizable fluid (D,E,F, 108) to produce an initially formed formation of a filter cake of slurry solids and any retained portions of said slurry liquids within said filtration chamber on said filter medium, and
• c) after forming said filtration chamber and while said sealable filtration chamber is closed and temperature and pressure controlled at least to said first predetermined temperature and pressure, introducing and passing dry steam or hot gas fluid (A, 108) through said filter medium (104) and said initially formed filter cake to heat and displace said retained portion of said slurry liquid from said filter cake and through said exit port means to form said substantially dry slurry solids filter cake on said filter medium, said introduced and passed dry steam or hot gas fluid being maintained at least as high in temperature and pressure as the temperature and pressure in said sealed filtration chamber so as to be maintained in it's dry state and to prevent any precipitation of liquids onto said filter cake while said filter cake is in said filtration chamber,
• d) after predetermined conditions have been attained, discontinuing said introduction and passing of dry steam or hot gas fluid,
• e) after discontinuing said introduction of dry steam or hot gas fluid, venting said filtration chamber,
• f) opening said filtration chamber by relatively moving said upper and lower plates,
• g) then moving said substantially dry slurry solids filter cake on said filter medium through said open filtration chamber,
• h) discharging from said open filtration chamber and from said filter medium (104) said substantially dry slurry solids filter cake from said filtration chamber formed during each closing of said filtration apparatus on said filter medium, and
• i) repeating said steps a) through f) for successive closing and opening of said upper and lower plates in repeated operation of said pressure filter apparatus and for forming said substantially dry filter cake on said filter medium.