Sludge drying method and installation

Patent metadata

Field	Value
Publication number	US-9869514-B2
Application number	US-201113813771-A
Country	US
Kind code	B2
Filing date	Aug 5, 2011
Priority date	Aug 6, 2010
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

This sludge drying device is characterised in that a gas entraining a mix of sludge and sand is recycled after drying ( 6 ) and separation ( 8 ) to be compressed ( 10 ) and circulate again through the dryer ( 6 ) acting as a heat exchange fluid. Compression has been performed to increase the dew point temperature of the gas containing the evaporated moisture, such that the latent heat of evaporation can be recovered by the drying gas. The required operating power can then be much lower than the required power for evaporating the moisture contained in the sludge, because most of this power is recovered.

First claim

The invention claimed is:

1. Continuous sludge drying method, comprising a mix of a sludge with a divided solid material in a gas flow, sufficient heating of the mix to dry the sludge by evaporating a moisture contained in the sludge into the gas, thus drying the sludge and wetting the gas, and then a separation of the dried sludge from the wet gas and the divided solid material, wherein the wet gas is compressed resulting in an increase in temperature and is then used to heat a next portion of the mix by condensation of the moisture contained in said wet gas; and the mix is driven in a form of a spray by the gas flow during the drying of the sludge at a velocity of 20 to 30 meters per second (m/s), and the mix follows a divided flow through a plurality of blower ducts that pass through a dryer.

2. Sludge drying method according to claim 1 , wherein the wet gas, after heating, is dried and recycled towards a second subsequent portion of the mix.

3. Sludge drying method according to claim 2 , wherein the dried gas is heated before returning to the second subsequent portion of mix.

4. Sludge drying method according to claim 2 , wherein the dried gas is used to entrain the mix through a sludge drying location as far as a separation location.

5. Sludge drying installation, comprising a mix of a wet sludge and a divided solid material, a mixer comprising an outlet, a gas flow injector, a sludge dryer, a separator of a dried sludge, the divided solid material, and a gas that has become wet, a means of transporting the mix between the mixer and the separator through the sludge dryer, wherein the installation comprises a duct connecting the separator to the sludge dryer which is followed by the gas that has become wet, a compressor being present between the separator and the sludge dryer, the sludge dryer comprising a heat exchanger between the wet gas and the mix, wherein the gas flow injector drives the wet sludge and the divided solid material in the form of a spray at a velocity of 20 to 30 meters per second (m/s), and the mix transport means comprises a plurality of blower ducts that pass through the sludge dryer.

6. Sludge drying installation according to claim 5 , wherein the duct also connects the sludge dryer to the gas flow injector passing through a wetting device of the gas.

7. Sludge drying installation according to claim 5 , wherein a shell surrounds the plurality of blower ducts.

8. Sludge drying installation according to claim 5 , wherein the mix transport means further comprises a drum rotating in the sludge dryer, and the duct through which the gas that has become wet passes forms a shell surrounding the drum.

9. Sludge drying installation according to claim 7 , wherein the shell is divided into horizonally aligned compartments by baffles, each of the compartments being provided with a water drainage duct opening under the compartments and extending under the compartments.

10. Sludge drying installation according to claim 5 , wherein the sludge drying installation comprises a superheater of the mix between the sludge dryer and the separator, or a gas preheater between a wetting device of the gas and the injector, or both, as external heat sources.

11. Sludge drying installation according to claim 5 , wherein the heat exchanger comprises a shell formed by the duct through which the gas that has become wet passes, wherein a water drainage duct opens under the shell.

12. Sludge drying method according to claim 1 , wherein the plurality of blower ducts includes about one hundred blower ducts.

13. Sludge drying installation according to claim 5 , wherein the plurality of blower ducts includes about one hundred blower ducts.

Assignees

• Haarlemmer Geert
• Commissariat Energie Atomique

Inventors

• Haarlemmer Geert

Classifications

• F26B23/004 Primary

  by compressing and condensing vapour in exhaust gases, i.e. using an open cycle heat pump system · CPC title

• F26B17/106

  the drying enclosure, e.g. its axis, being substantially straight and horizontal, e.g. pneumatic drum dryers; the drying enclosure consisting of multiple substantially straight and horizontal stretches (F26B17/107 takes precedence) · CPC title

• F26B3/205

  the materials to be dried covering or being mixed with heated inert particles which may be recycled · CPC title

• F26B1/00

  Preliminary treatment of solid materials or objects to facilitate drying {, e.g. mixing or backmixing the materials to be dried with predominantly dry solids (F26B5/005 takes precedence)} · CPC title

• F26B2200/18

  Sludges, e.g. sewage, waste, industrial processes, cooling towers · CPC title