Process and apparatus for ventless combustion of waste

• US 5,678,498 A
• Filed: 10/11/1995
• Issued: 10/21/1997
• Est. Priority Date: 10/11/1995
• Status: Expired due to Fees

• Current Assignee: Envirotech Corporation (Baker Hughes Company)
• Original Assignee: Envirotech Corporation (Baker Hughes Company)
• Inventors: Whaley, Charles Wayne
• Primary Examiner(s): Bennett, Henry A.
• Assistant Examiner(s): TINKER, SUSANNE CHRISTINE
• Application Number:
  US08/540,974
• Time in Patent Office: 741 Days
• Field of Search: 110/204-207, 110/215, 110/216, 110/345, 110/346, 110/235
• US Class Current: 110/345
• CPC Class Codes: F23G 5/006 General arrangement of incineration plant, e.g. flow sheets
• CPC Class Codes: F23G 5/444 for solid waste F23G5/448 takes precedence
• CPC Class Codes: F23J 15/006 Layout of treatment plant
• CPC Class Codes: Y02E 20/34 Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

Abstract

A ventless, combustible waste reduction process and apparatus which can utilize any type of combustion means for disposing of hazardous, as well as non-hazardous, burnable waste. Such wastes include toxic combustible liquids, oil slurries, soils contaminated with dioxin, PCBs, creosote, or any other potentially harmful or toxic combustible material. In particular, the present invention relates to a ventless, combustible waste reduction process in which the operating pressure is slightly below atmospheric pressure and which employs no venting or stack discharge of pollutants whatsoever. The entire flue gas stream is scrubbed, enriched with oxygen and recycled to the combustion chamber in varying amounts in response to pressure and temperature measurements taken in the combustion chamber to maintain the pressure and temperature in the combustion chamber within pre-selected ranges.

Claims

1. A process for combusting waste material comprising the steps of:

(a) loading combustible waste into an air-tight combustion chamber where the waste is combusted;

(b) passing a resulting flue gas stream from the combustion chamber to a heat reduction chamber where the temperature of the flue gas stream is reduced;

(c) passing the flue gas stream from the heat reduction chamber to a heat exchanger where the temperature of the flue gas stream is further reduced;

(d) passing the flue gas stream from the heat exchanger to a gas cleaning chamber where some acids contained within the flue gas stream are neutralized and particulates are removed;

(e) enriching the flue gas stream from the cleaning chamber with oxygen; and

(f) injecting the oxygen enriched flue gas stream into the combustion chamber in varying amounts in response to pressure and temperature measurements taken in the combustion chamber to maintain the pressure and temperature in the combustion chamber within pre-selected ranges.

2. The process of claim 1 wherein the combustion chamber comprises a first waste holding chamber reversibly sealed from the outside by a hopper door and from a second waste holding chamber by a first door;

a first transfer ram for transferring waste from the first waste holding chamber to the second waste holding chamber;

the second waste holding chamber being reversibly sealed from a combustion loading chamber by a second door;

a second transfer ram for transferring waste from the second waste holding chamber to the combustion loading chamber;

the combustion loading chamber being reversibly sealed from a combustion zone by a third door; and

a third transfer ram for transferring waste from the combustion loading chamber to the combustion zone.

3. The process of claim 2 wherein the combustion chamber comprises at least one additional transfer ram disposed within the combustion zone for transferring combusted waste into a combusted waste collection means.

4. The process of claim 1 wherein the heat reduction chamber is lined with insulation and refractory material and comprises a lower section having deflectors disposed therein for trapping particulates from the flue gas stream.

5. The process of claim 1 wherein the gas cleaning chamber comprises a lime bath, a lime water spray and a charcoal filter wherein the flue gas stream is introduced into the lime bath at a depth of about 30% below the surface of the lime bath and upon exiting the lime bath, the flue gas stream passes through the lime water spray and through the charcoal filter.

6. The process of claim 1 wherein the flue gas stream coming from the gas cleaning chamber is enriched with oxygen in a ratio from about 20% to about 30%.

7. The process of claim 1 wherein the waste is combusted in the combustion chamber at a pressure below atmospheric pressure.

8. The process of claim 1 wherein the waste is combusted in the combustion chamber at a temperature from about 1800°

F. to about 2000°

F. and the temperature of the flue gas stream in the heat reduction chamber is reduced to about 1100°

F. and the flue gas stream from the heat exchanger is passed through a particulate trap prior to entering the gas cleaning chamber.

9. The process of claim 1 wherein the combustion chamber comprises at least one waste holding chamber reversibly sealed from the atmosphere and from a combustion zone and transfer means for transferring the waste from the waste holding chamber into the combustion zone without the escape of any flue gases from the combustion chamber to the atmosphere.

10. The process of claim 1 comprising the additional step of removing some of the particulates carried by the flue gas stream as it passes through the heat reduction chamber.

11. A process for combusting waste material comprising the steps of:

(a) loading combustible waste material into a first waste holding chamber which is reversibly sealed from the outside and from a second waste holding chamber;

(b) reversibly sealing the first waste holding chamber from the outside;

(c) transferring the combustible waste material from the first waste holding chamber to the second waste holding chamber which is reversibly sealed from a combustion loading chamber;

(d) reversibly sealing the second waste holding chamber from the first waste holding chamber;

(e) transferring the waste from the second waste holding chamber to the combustion loading chamber which is reversibly sealed from a combustion chamber;

(f) reversibly sealing the combustion loading chamber from the second waste holding chamber;

(g) transferring the combustible waste material from the combustion loading chamber to the combustion chamber where the waste is combusted;

(h) passing a resulting flue gas stream from the combustion chamber to a heat reduction chamber where the temperature of the flue gas stream is reduced;

(i) passing the flue gas stream from the heat reduction chamber to a heat exchanger where the temperature of the flue gas stream is further reduced;

(j) passing the flue gas stream from the heat exchanger to a gas cleaning chamber where some acids contained within the flue gas stream are neutralized and particulates are removed;

(k) enriching the flue gas stream from the cleaning chamber with oxygen; and

(l) injecting the oxygen enriched flue gas stream into the combustion chamber in varying amounts in response to pressure and temperature measurements taken in the combustion chamber to maintain the pressure and temperature in the combustion chamber within pre-selected ranges.

12. The process of claim 11 wherein the waste is combusted in the combustion chamber at a temperature from about 1800°

F. to about 2000°

F. and the temperature of the flue gas stream in the heat reduction chamber is reduced to about 1100°

F. and the flue gas stream from the heat exchanger is passed through a particulate trap prior to entering the gas cleaning chamber.

13. The process of claim 11 wherein the heat reduction chamber is lined with insulation and refractory material and comprises a lower section having deflectors disposed therein for trapping particulates from the flue gas stream.

14. The process of claim 11 wherein the gas cleaning chamber comprises a lime bath, a lime water spray and a charcoal filter wherein the flue gas stream is introduced into the lime bath at a depth of about 30% below the surface of the lime bath and upon exiting the lime bath, the flue gas stream passes through the lime water spray and through the charcoal filter.

15. The process of claim 11 wherein the flue gas stream coming from the gas cleaning chamber is enriched with oxygen in a ratio from about 20% to about 30%.

16. The process of claim 11 wherein the waste is combusted in the combustion chamber at a pressure below atmospheric pressure.

17. The process of claim 11 comprising the additional step of removing some of the particulates carried by the flue gas stream as it passes through the heat reduction chamber.

18. An apparatus for the ventless reduction of waste material by combustion comprising:

an air-tight combustion chamber;

a heat reduction chamber in air-flow communication with the combustion chamber;

a heat exchanger in air-flow communication with the heat reduction chamber;

a first fan for drawing flue gases through the apparatus disposed between the heat exchanger and a gas cleaning chamber;

a second fan for drawing the flue gases from the gas cleaning chamber through a conduit back into the combustion chamber;

an oxygen supply for enriching the flue gases in the conduit with oxygen to produce an oxygen enriched flue gas stream;

a motorized gas supply valve disposed in the conduit; and

control means for maintaining the pressure and temperature in the combustion chamber within pre-selected ranges set in the control means by varying the flow of the oxygen enriched flue gas stream through the gas supply valve into the combustion chamber in response to pressure and temperature measurements from the combustion chamber monitored by the control means.

19. The apparatus of claim 18 wherein the combustion chamber comprises a first waste holding chamber reversibly sealed from the outside by a hopper door and from a second waste holding chamber by a first door;

a first transfer ram for transferring waste from the first waste holding chamber to the second waste holding chamber;

the second waste holding chamber being reversibly sealed from a combustion loading chamber by a second door;

a second transfer ram for transferring waste from the second waste holding chamber to the combustion loading chamber;

the combustion loading chamber being reversibly sealed from a combustion zone by a third door; and

a third transfer ram for transferring waste from the combustion loading chamber to the combustion zone; and

at least one additional transfer ram disposed within the combustion zone for transferring combusted waste into a combusted waste collection means.

20. The apparatus of claim 19 wherein the control means controls (i) the operation of the combustion chamber and a hopper containing waste so that the waste is automatically loaded from the hopper to the combustion zone without the escape of any flue gases from the apparatus and (ii) the transfer of the combusted waste into the combusted waste collection means by the at least one additional transfer ram.

21. The apparatus of claim 18 wherein the heat reduction chamber is lined with insulation and refractory material and comprises a lower section having deflectors disposed therein for trapping particulates from the flue gases.

22. The apparatus of claim 18 wherein the gas cleaning chamber comprises a lime bath, a lime water spray and a charcoal filter wherein the flue gases are introduced into the lime bath at a depth of about 30% below the surface of the lime bath and upon exiting the lime bath, the flue gases pass through the lime water spray and through the charcoal filter.

23. The apparatus of claim 18 wherein the waste is combusted in the combustion chamber at a pressure below atmospheric pressure.

24. The apparatus of claim 18 wherein the oxygen enriched flue gas stream comprises from about 20% to about 30% oxygen.

25. The apparatus of claim 18 wherein the combustion chamber comprises at least one waste holding chamber reversibly sealed from the atmosphere and from a combustion zone and transfer means for transferring the waste from the waste holding chamber into the combustion zone without the escape of any flue gases from the combustion chamber to the atmosphere.

26. The apparatus of claim 18 further comprising a particulate trap disposed between the heat exchanger and the first fan which the flue gases pass through prior to entering the gas cleaning chamber.