# US 7,019,190 B1 · Soil remediation system

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- Number: US 7,019,190 B1
- Document ID: US7019190B1
- Status: Granted
- Kind: B1
- Application number: 09/786,184
- Filed: 1999-09-16
- Granted: 2006-03-28
- Earliest claimed: 1998-09-28
- Assignees: Innova Soil Technology PTY LTD
- Inventors: John Anthony Lucas; Louis James Wibberley
- Web page: https://patentgrep.com/patent/US7019190B1

## CPC

- B09C 1/06: thermally
- F23G 5/165: {arranged at a different level}
- F23G 5/20: having rotating or oscillating drums
- F23G 5/46: Recuperation of heat
- F23G 7/14: of contaminated soil, e.g. by oil
- F23G 2203/209: with variable inclination of rotation axis
- F23G 2206/10: reintroducing the heat in the same process, e.g. for predrying
- F23G 2900/52002: Rotary drum furnaces with counter-current flows of waste and gas
- Y10S 588/90: Apparatus
- B09C: RECLAMATION OF CONTAMINATED SOIL (gatherers for removing stone or the like from the soil A01B43/00; sterilising soil by steam A01G11/00; removing undesirable matter, e.g. rubbish, from the land E01H15/00)
- F23G: CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A process and apparatus for energy efficient remediation of soil contaminated with hydrocarbons, including desorbing the hydrocarbon contaminants from a bed of the soil by thermal desorption in a treated desorption chamber (20) and thereafter combusting the contaminants in a thermal oxidiser (30). The combustion air for the desorption chamber and the thermal oxidiser, and the desorbed contaminants prior to admission to said thermal oxidiser, are preheated by heat exchange (40) with offgases from the thermal oxidiser. The offgases are then rapidly quenched at below 200° C.

## Claims

### Claim 1

A process for remediating soil contaminated with hydrocarbons, including:
desorbing the hydrocarbon contaminants from a bed of the soil by thermal desorption in a desorption chamber and thereafter combusting the contaminants in a thermal oxidiser;
wherein combustion air for said desorption chamber and said thermal oxidiser, and said desorbed contaminants prior to admission to said thermal oxidiser, are preheated by heat exchange with offgases from the thermal oxidiser;
and wherein, after said heat exchange with said combustion air and said desorbed contaminants, said offgases from the thermal oxidiser are rapidly quenched to below 200° C.

### Claim 2 (depends on 1)

A process according to claim 1, wherein said offgases preheat the combustion air first and then the desorbed contaminants.

### Claim 3 (depends on 1)

A process accordingly to claim 1, wherein excess preheated air is vented during treatment of soil with high hydrocarbon contamination levels.

### Claim 4 (depends on 1)

A process according to claim 1, wherein the heat exchange is conducted in a heat exchanger having metal heat exchange surfaces and wherein the metal surface temperatures are maintained above 500° C. and below 700° C.

### Claim 5 (depends on 4)

A process according to claim 4, wherein the heat exchanger is arranged for co-current flow.

### Claim 6 (depends on 1)

A process according to claim 1, wherein the hot gas flow through both the combustion air and contaminants heat exchanges is controlled.

### Claim 7 (depends on 1)

A process according to claim 1, wherein the separated contaminants are treated in said thermal oxidiser in at least two stages, including a combustion stage in which the contaminants are combusted with a first supply of combustion air at a substantially adiabatic temperature in the range 900–1200° C., and a second stage in which a second supply of combustion air is admitted for combustion of residual compounds and for controlling the offgas outflow temperature.

### Claim 8 (depends on 1)

A process according to claim 1, wherein desorbed contaminants in gaseous form are at least in part combusted within said desorption chamber by controlled admission of air into said chamber above said bed to effect such combustion.

### Claim 9 (depends on 1)

A process according to claim 1, wherein said rapid quenching is by injection of ambient air.

### Claim 10 (depends on 9)

A process according to claim 9, wherein said ambient air is injected by an ejector powered by said offgases.

### Claim 11 (depends on 1)

A process according to claim 1, wherein a proportion of offgases from the thermal oxidiser bypasses said heat exchange with said combustion air and said desorbed contaminants and is subjected to said rapid quenching to below 200° C.

### Claim 12 (depends on 1)

A process according to claim 1, wherein said rapid quenching is carried out in less than 750 ms.

### Claim 13

Apparatus for remediating soil contaminated with hydrocarbons, including:
a first furnace defining a desorption chamber in which a bed of said soil is treated to separate the hydrocarbon contaminants from the soil by thermal desorption;
a second furnace for combusting said hydrocarbon contaminants by thermal oxidation;
respective ducts for conveying combustion air to said desorption chamber and to said second furnace, and for conveying the desorbed contaminants from the desorption chamber to the second furnace;
a heat exchange configuration for preheating said combustion air and said desorbed contaminants by heat exchange with offgases from the second furnace; and
a quenching module for rapid quenching of said offgases to below 200° C. after said heat exchange with said combustion air and said desorbed contaminants.

### Claim 14 (depends on 13)

Apparatus according to claim 13, wherein the heat exchange configuration is a series configuration so that said offgases preheat the combustion air first and then the desorbed contaminants.

### Claim 15 (depends on 14)

Apparatus according to claim 14, wherein the heat exchange configuration is directly installed in the hot gas duct at the offgas outlet end of the second furnace.

### Claim 16 (depends on 14)

Apparatus according to claim 14, wherein the heat exchange configuration is arranged for co-current flow.

### Claim 17 (depends on 13)

Apparatus according to claim 13, wherein the heat exchange configuration is directly installed in the hot gas duct at the offgas outlet end of the second furnace.

### Claim 18 (depends on 17)

Apparatus according to claim 17, wherein the heat exchange configuration is arranged for co-current flow.

### Claim 19 (depends on 17)

Apparatus according to claim 17, wherein the leading tube bank of the heat exchange configuration incorporates variable tube spacing to facilitate said direct installation.

### Claim 20 (depends on 13)

Apparatus according to claim 13, further including an energy dump valve from the heat exchange configuration for venting of excess preheated air.

### Claim 21 (depends on 13)

Apparatus according to claim 13, wherein the heat exchange configuration includes combustion air and contaminants heat exchangers that includes a hot gas by-pass and damper system or by-pass duct to control hot gas flow through both the combustion air and contaminants heat exchangers.

### Claim 22 (depends on 21)

Apparatus according to claim 21, wherein the heat exchanger for the contaminants is adapted to be made reversible depending on operating conditions.

### Claim 23 (depends on 13)

Apparatus according to claim 13, wherein said second furnace includes at least two stages including a combustion stage in which the contaminants are combusted with a first supply of combustion air at a substantially adiabatic temperature in the range 900–1200° C., and a second stage in which a second supply of combustion air is admitted for combustion of residual compounds and for controlling the offgas outflow temperature.

### Claim 24 (depends on 13)

Apparatus according to claim 13, further including:
a control device for controlled admission of air into said desorption chamber above said bed to effect in the said chamber at least partial combustion of said desorbed contaminants in gaseous form; and
a duct for conveying the products of said at least partial combustion to said second furnace for further combustion therein.

### Claim 25 (depends on 13)

Apparatus according to claim 13, wherein said quenching module comprises an ambient air injection device.

### Claim 26 (depends on 25)

Apparatus according to claim 25, wherein said ambient air injection device comprises an ejector powered by said offgases.

### Claim 27 (depends on 13)

Apparatus according to claim 13, further comprising a duct that bypasses said heat exchange configuration to said quenching module for conveying a proportion of offgases from the thermal oxidiser direct to the quenching module.

### Claim 28 (depends on 13)

Apparatus according to claim 13, wherein said quenching module is arranged to carry out said rapid quenching in less than 750 ms.

### Claim 29

A process for remediating soil contaminated with hydrocarbons, including:
desorbing the hydrocarbon contaminants from a bed of the soil by thermal desorption in a desorption chamber and thereafter combusting the contaminants in a thermal oxidiser;
wherein offgases from the thermal oxidiser are utilised to preheat process feed gases by heat exchange with the offgases and are thereafter rapidly quenched to below 200° C.

### Claim 30 (depends on 29)

A process according to claim 29, wherein the heat exchange is conducted in a heat exchanger having metal heat exchange surfaces and wherein the metal surface temperatures are maintained above 500° C. and below 700° C.

### Claim 31 (depends on 30)

A process according to claim 30, wherein the heat exchanger is arranged for co-current flow.

### Claim 32 (depends on 29)

A process according to claim 29, wherein the separated contaminants are treated in said thermal oxidiser in at least two stages, including a combustion stage in which the contaminants are combusted with a first supply of combustion air at a substantially adiabatic temperature in the range 900–1200° C., and a second stage in which a second supply of combustion air is admitted for combustion of residual compounds and for controlling the offgas outflow temperature.

### Claim 33 (depends on 29)

A process according to claim 29, wherein said rapid quenching is by injection of ambient air.

### Claim 34 (depends on 33)

A process according to claim 33 wherein said ambient air is injected by an ejector powered by said offgases.

### Claim 35 (depends on 29)

A process according to claim 29, wherein a proportion of offgases from the thermal oxidiser bypasses said heat exchange and is subjected to said rapid quenching to below 200° C.

### Claim 36 (depends on 29)

A process according to claim 29, wherein said rapid quenching is carried out in less than 750 ms.

### Claim 37

Apparatus for remediating soil contaminated with hydrocarbons, including:
a first furnace defining a desorption chamber in which a bed of said soil is treated to separate the hydrocarbon contaminants from the soil by thermal desorption;
a second furnace for combusting said hydrocarbon contaminants by thermal oxidation;
a heat exchange configuration of preheating furnace feed gases by heat exchange with the offgases; and
a quenching module for rapid quenching of said offgases to below 200° C. after said heat exchange with furnace feed gases.

### Claim 38 (depends on 37)

Apparatus according to claim 37, wherein the heat exchange configuration is directly installed in the hot gas duct at the offgas outlet end of the second furnace.

### Claim 39 (depends on 38)

Apparatus according to claim 38, wherein the heat exchange configuration is arranged for co-current flow.

### Claim 40 (depends on 38)

Apparatus according to claim 38, wherein the leading tube bank of the heat exchange configuration incorporates variable tube spacing to facilitate said direct installation.

### Claim 41 (depends on 37)

Apparatus according to claim 37, wherein said second furnace includes at least two stages including a combustion stage in which the contaminants are combusted with a first supply of combustion air at a substantially adiabatic temperature in the range 900–1200° C., and a second stage in which a second supply of combustion air is admitted for combustion of residual compounds and for controlling the offgas outflow temperature.

### Claim 42 (depends on 37)

Apparatus according to claim 37, wherein said quenching module comprises an ambient air injection device.

### Claim 43 (depends on 42)

Apparatus according to claim 42, wherein said ambient air injection device comprises an ejector powered by said offgases.

### Claim 44 (depends on 37)

Apparatus according to claim 37, further comprising a duct that bypasses said heat exchange configuration to said quenching module for conveying a proportion of offgases from the thermal oxidiser direct to the quenching module.

### Claim 45 (depends on 37)

Apparatus according to claim 37, wherein said quenching module is arranged to carry out said rapid quenching in less than 750 ms.