US 3,946,495 AGranted

Method and apparatus for drying moisture-containing solids particularly domestic refuse and sludge cakes

OwnerAsriel Osdorinventor

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Abstract

Method and apparatus are described for the production of solid fuel and steam by drying moisture-containing solids, such as refuse and sludge cakes, in a multi-stage heating zone by using the moisture-containing solids as the feed-water in a direct contact countercurrent flow pressurized boiler. After vaporizing the bulk of the moisture in the heating zone of the boiler, the solid residue is further dried in a multi-stage flashing zone. From the upper end of the heating zone is removed a nearly saturated steam including the water vapor evaporated from the moisture-contained solids by the heat of cooling of the introduced superheated steam. A portion of the removed steam equal to the vaporized moisture is heated and then directed to a turbine, generating all the power required to operate the system. The bulk of the removed steam equal to the introduced superheated steam is compressed, reheated and recycled through the heating zone. The dried solid is removed at the lower end of the flashing zone and is incinerated, and the recovered heat is utilized to supply the heat required for said drying, and to produce saturated steam for heating purposes, or superheated steam for power generation. In the latter case the heat of condensation of the turbine exhaust steam is utilized advantageously as a heat source in a distillation plant for fresh water production.

Claims23

Dependent claims

A method of using moisture-containing solids, such as domestic refuse and sludge cakes, to produce dried residue and nearly saturated steam at super atmospheric pressure, comprising:

introducing the moisture containing solids into the top of a vertical vessel containing a heating zone at super-atmospheric pressure, the vessel serving as a direct contact pressurized boiler and the moisture-containing solids serving as the feed-water and flowing downwardly therein:
introducing superheated steam into a lower part of the heating zone to flow upwardly in counter-current direct contact with the down-moving moisture-containing solids, the bulk of the moisture contained in the moisture-containing solids being vaporized in said heating zone;
removing from the upper end of the heating zone a nearly saturated steam at a considerably lower temperature and at a slightly lower pressure than the temperature and pressure of said introduced superheated steam, said removed steam including the water vapor evaporated from the moisture-containing solids by the heat of cooling of said introduced superheated steam;
reheating and slightly compressing a quantity of the removed steam equal to the quantity of the introduced superheated steam and recycling same through the heating zone in counter-current flow to the downmoving moisture-containing solids;
directing the partially dried residue leaving the heating zone to move downwardly through a flashing zone maintained at lower pressure than the heating zone, additional moisture from the moisture-containing solids being vaporized by flashing;
removing the dried solid residue;
and directing, at substantially the super-atmospheric pressure of the heating zone, the remaining portion of the removed steam corresponding to the water evaporated from the moisture-containing solids for use as a source of energy.

4 more elements

Apparatus for using moisture-containing solids to produce residue and nearly saturated at super-atmospheric pressure steam comprising:

a vertical pressurized drier having an inlet at the top for the moisture containing solids, and an outlet at the bottom for the dried residue, said drier including an upper heating zone and a lower flashing zone;
means for introducing super-heated steam and for passing same upwardly through the heating zone of the drier in counter-current direct contact with the downmoving moisture-containing solids;
a steam outlet at the upper end of the drier for removing nearly saturated steam at super-atmospheric pressure including the water vapor evaporated from the moisture-containing solids;
means for compressing and reheating a quantity of the so-removed steam equal to the quantity of the introduced superheated steam;
means for recycling the so-compressed and reheated quantity of superheated steam through the heating zone in countercurrent direct contact to the down-moving moisture-contained solids;
means for directing the remaining portion of the steam corresponding to the water evaporated from the moisture-containing solids in said heating zone for use as a source of energy;
means for feeding the moisture-containing solids into the top of the drier against the super-atmospheric pressure therein;
means for removing the dried residue from the bottom of the drier;
said upper heating zone including at least one heating stage, and said lower flashing zone including at least one flashing stage having a water vapor outlet at its top for removing the flashed water vapor;
means for transferring the dried residue from the lower end of the heating zone to said flashing zone;
and means for removing the further dried residue from the lower end of the flashing zone.

8 more elements

Apparatus for drying moisture-containing solids to produce a dried residue;

comprising:
a vertical pressurized drier having an inlet at the top for the moisture-containing solids, and an outlet at the bottom for the dried residue;
means for feeding the moisture-containing solids into the pressurized drier;
a steam inlet at a lower part of the drier for introducing superheated steam into a space comprised between a lower funnel having a central downwardly extending tubular section for the dried residue, and an upper horizontal perforated plate having a central opening with a downwardly extending tubular section;
a screw conveyor passing through both said tubular sections;
the moisture-containing solids being compacted between the screw conveyor and its respective funnel tubular section and thereby forming a barrier for the flow of steam through the screw conveyor forcing same to flow upwardly through the perforations of said perforated plate and in countercurrent direct contact with the down-moving moisture-containing solids;
a steam outlet at the upper end of the drier for removing the nearly saturated steam including the water vapor evaporated from the moisture-containing solids;
means for compressing and reheating a quantity of the so-removed nearly saturated steam equal to the quantity of the introduced superheated steam;
means for recycling the compressed and reheated portion of superheated steam through the drier in countercurrent direct contact with the down-moving moisture-containing solids;
means for removing the dried residue from the bottom of the drier;
and means for diverting the excess of steam removed from the top of the drier for power generation or other uses.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 05/426,247Filed 19 Dec 1973
Granted: 30 Mar 1976
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

F26B 21/25
Circulating air or gases in closed cycles, e.g. wholly within the drying enclosure: partly outside the drying enclosure
F26B 17/1483
The members or bodies being in movement: the movement being a rotation around a vertical axis
F26B 23/028
Using combustion heating: using solid fuel; burning the dried product
Y02P 70/10
Climate change mitigation technologies in the production process for final industrial or consumer products: greenhouse gas [GHG] capture, material…