US 4,536,969 AGranted

Hot water drying of low rank coal

AssigneeKamyr, Inc.

InventorMichael I. Sherman

Life of this patent

Estimating the term…

Loading patent…

Abstract

A method and apparatus are provided for the dehydration of low rank coal, such as lignite, utilizing hot water. Particles of low rank coal are preheated, entrained in liquid, fed to a high pressure feeder, and transferred into a high pressure loop leading to a heat exchange vessel, and at a pressure of about 500-1,000 psi. Particles discharged from the bottom of the heat exchange vessel pass to the top of a dehydration vessel. Water at a temperature (e.g. 250.degree.-260.degree. C. at 700 psi) sufficient to facilitate dehydration of the coal is fed to the bottom of the heat exchange vessel, and to the particles as they pass from the heat exchange vessel to the dehydration vessel. For particles withdrawn from the bottom of the dehydration vessel the pressure is gradually reduced so that they do not explode, and then the liquid and particles are separated while still at a temperature of about 180.degree.-200.degree. F. utilizing a vibrating dewatering screen, Vortex sieve, and vibratory centrifuge. Liquid is withdrawn from a screen at a central portion of the dehydration vessel and fed to the bottom of the heat exchange vessel, and liquid is withdrawn from a central screen of the heat exchange vessel, passed to flash tanks, a Lamella gravity settler, and a disk filter, sodium, sulfur, and other minerals in the withdrawn liquid being removed from the system.

Claims20

Dependent claims

A method of dehydrating low rank coal utilizing a heat exchange vessel having a top and a bottom, and comprising the steps of continuously:

(a) establishing a first flow stream of particulate low rank coal;
(b) preheating the first flow stream of particles;
(c) immersing the first flow stream of particles in water;
(d) transferring the particles flowing in the first stream immersed in water to a second flow stream having a pressure higher than in said first flow stream, but at a temperature less than the steam saturation temperature of the first stream;
(e) feeding the particles in the second flow stream to the top of the heat exchange vessel, and extracting liquid from the particles at the top of the heat exchange vessel and recirculating the extracted liquid to the second flow stream;
(f) introducing hot water to the bottom of the heat exchange vessel, to flow downwardly therein, the water having a temperature sufficient to facilitate dehydration of the low rank coal particles;
(g) discharging low rank coal particles from the bottom of the heat exchange vessel;
(h) feeding the low rank coal particles discharged from the bottom of the heat exchange vessel, with hot water, to the top of a dehydration vessel;
(i) extracting liquid from the particles at the top of the dehydration vessel and recirculating the extracted liquid to the heat exchange vessel;
(j) effecting counter-current washing of the particles at the bottom of the dehydration vessel to cool and wash the particles at the bottom of the dehydration vessel;
(k) withdrawing spent hot wash water, and water of dehydration, from the dehydration vessel and directing the hot spent wash water, and water of dehydration, to the heat exchange vessel to flow countercurrently to the low rank coal therein to effect a substantial recovery of heat from dehydrated low rank coal;
and
(l) depressurizing the particles of low rank coal as they are discharged from the bottom of the dehydration vessel, the particles being withdrawn in a third particle flow stream, by transferring the particles flowing in the third flow stream to a fourth, lower pressure flow stream.

10 more elements

Apparatus for dehydrating solid porous organic material or the like comprising:

a first high pressure feeder including a low pressure first material flow loop, and a high pressure second material flow loop;
a vertical heat exchange vessel having a top and a bottom, with a liquid extraction means at the top thereof, a hot water liquid introduction means adjacent the bottom thereof, and a material discharge device at the bottom thereof;
a first conduit connecting said first high pressure feeder second loop to the extracting means at the top of the heat exchange vessel, and a second conduit returning from the extracting means to the first high pressure feeder;
a vertical dehydrating vessel;
a third conduit operatively interconnecting the material discharging device adjacent the bottom of the heat exchange vessel and a liquid extracting means at the top of the dehydration vessel;
a fourth conduit operatively interconnecting the liquid extracted from the extracting means at the top of the dehydration vessel to the hot water introduction to the bottom of the heat exchange vessel, said conduit including a heat exchanger disposed therein, a fluid having a temperature higher than the temperature of liquid in said conduit fed to said heat exchanger to effect heating of the liquid;
temperature control means for sensing the temperature of liquid in said fourth conduit said heat exchanger, and controlling the amount of heated fluid fed to the heat exchanger in response to said temperature sensing;
a second high pressure feeder, including a third material flow high pressure loop, and a fourth material flow low pressure loop;
a material discharge device adjacent the bottom of said dehydration vessel;
a fifth conduit interconnecting the discharging device of the dehydration vessel to the second high pressure feeder and defining a part of the third flow loop, and a sixth conduit extending from the second high pressure feeder in the third loop and connected to a conduit for introducing water adjacent the bottom of the dehydration vessel;
and
liquid-material separating means operatively connected to the second high pressure feeder by a seventh conduit, which conduit defines the fourth loop.

9 more elements

Dependencies are inferred from the claim text.