Control of mercury emissions from solid fuel combustion

• US 20050039598A1
• Filed: 10/08/2004
• Published: 02/24/2005
• Est. Priority Date: 06/03/2003
• Status: Active Grant

• Current Assignee: General Electric Technology GmbH (GE Vernova, Inc.)
• Original Assignee: Alstom Technology Ltd. (Alstom SA)
• Inventors: Srinivasachar, Srivats, Kang, Shin G., Johnson, Kurt W.
• Granted Patent: US 8,069,797 B2
• Time in Patent Office: Days
• US Class Current: 95/134
• CPC Class Codes: B01D 2253/102 Carbon
• CPC Class Codes: B01D 2257/602 Mercury or mercury compounds
• CPC Class Codes: B01D 53/10 with dispersed adsorbents
• CPC Class Codes: B01D 53/64 Heavy metals or compounds thereof, e.g. mercury
• CPC Class Codes: B01D 53/83 with moving reactants
• CPC Class Codes: B01J 20/20 comprising free carbon; comprising carbon obtained by carbonising processes
• CPC Class Codes: B01J 20/28004 Sorbent size or size distribution, e.g. particle size
• CPC Class Codes: F23J 15/003 for supplying chemicals to fumes, e.g. using injection devices
• CPC Class Codes: F23J 15/006 Layout of treatment plant
• CPC Class Codes: F23J 2215/60 Heavy metals; Compounds thereof
• CPC Class Codes: F23J 2217/102 electrostatic
• CPC Class Codes: F23J 2219/60 Sorption with dry devices, e.g. beds

Abstract

A system 26 for removing elemental mercury or mercury compounds handles carbonaceous sorbent 28 of a starter batch stored in a silo 30 in an agglomerated state. The sorbent 28 is fed by a feeder 32 to a separation device 34, which comminutes (if necessary) and de-agglomerates the sorbent particles 28 to their primary size distribution. This device 34 may be a particle-particle separator or a jet mill, where compressed air or high-pressure steam is the energy source. The de-agglomerated sorbent 28 of a contact batch created from the starter batch is conveyed by an airsteam for injection at a contact location 66 in a flue gas duct whereat carbonaceous sorbent of the contact batch adsorbs mercury from the flue gas.

Claims

1-20. -20. (cancelled)

21. A method for removing mercury from the products of fuel conversion comprising:

disposing carbonaceous sorbent into contact with the products of fuel conversion at a contact location having a temperature between 400°

F. and 1100°

F., whereupon the carbonaceous sorbent adsorbs mercury; and

removing the carbonaceous sorbent having mercury adsorbed thereon.

22. A method according to claim 21, wherein disposing the carbonaceous sorbent into contact with the products of fuel conversion at a contact location having a temperature between 400°

F. and 1100°

F. includes disposing the carbonaceous sorbent into contact with the products of fuel conversion at a contact location having a temperature between 500°

F. and 900°

F.

23. A method according to claim 21, wherein disposing the carbonaceous sorbent into contact with the products of fuel conversion at a contact location having a temperature between 400°

F and 1100°

F. includes disposing the carbonaceous sorbent into contact with the products of fuel conversion at a contact location having a temperature between 550°

F. and 750°

F.

24. A method according to claim 21, and further comprising depositing at least one of a halogen species and an acidic species on the carbonaceous sorbent prior to disposing the carbonaceous sorbent into contact with the products of fuel conversion.

25. A method according to claim 21, wherein the products of fuel conversion include fly ash generated by the combustion of coal and removing the carbonaceous sorbent having mercury adsorbed thereon includes separating carbonaceous sorbent which has absorbed mercury from the products of fuel conversion includes subjecting the products of fuel conversion to a classification process operable to separate carbonaceous sorbent from relatively coarser and denser fly ash.

26. A method according to claim 21, wherein the products of fuel conversion include flue gases generated by the combustion of coal and the carbonaceous sorbent adsorbs at least one of elemental mercury and mercury compounds from the flue gases.

27. A method according to claim 21, wherein the sorbent collection temperature is configured in correspondence with the respective contact location temperature such that, during the time at which the sorbent and the flue gas are in contact with one another while traveling between the contact location and the collection location, the exposure temperature deviation during this time, which is the difference in temperature between the respective temperature at the contact location and the respective temperature at the collection location, is greater than 50°

F., whereupon, in correspondence with the respective temperature at the contact location that lies in the range between 400°

F. and 1100°

F., the respective collection temperature is a value at least 50°

F. less than the respective contact location temperature.

28. A method according to claim 27, wherein the respective collection temperature is configured in correspondence with the respective temperature at the contact location to be a value between 100 to 800°

F.

29. A method according to claim 27, wherein the respective collection temperature is configured in correspondence with the respective temperature at the contact location to be a value between 120 to 400°

F.

30. A method according to claim 27, wherein the respective collection temperature is configured in correspondence with the respective temperature at the contact location to be a value between 140 to 300°

F.

31. A method according to claim 21, wherein the sorbent collection temperature is configured in correspondence with the respective contact location temperature such that, during the time at which the sorbent and the flue gas are in contact with one another while traveling between the contact location and the collection location, the exposure temperature deviation during this time, which is the difference in temperature between the respective temperature at the contact location and the respective temperature at the collection location, is greater than 100°

F., whereupon, in correspondence with the respective temperature at the contact location that lies in the range between 400°

F. and 1100°

F., the respective collection temperature is a value at least 100°

F. less than the respective contact location temperature.

32. A method according to claim 21, wherein the sorbent collection temperature is configured in correspondence with the respective contact location temperature such that, during the time at which the sorbent and the flue gas are in contact with one another while traveling between the contact location and the collection location, the exposure temperature deviation during this time, which is the difference in temperature between the respective temperature at the contact location and the respective temperature at the collection location, is greater than 200°

F., whereupon, in correspondence with the respective temperature at the contact location that lies in the range between 400°

F. and 1100°

F., the respective collection temperature is a value at least 200°

F. less than the respective contact location temperature.

33. A method according to claim 27, and further comprising modifying at least one of the surface of the carbonaceous sorbent and a surface along the path between the contact location and the collection location to thereby enhance the deposition of the carbonaceous sorbent on a surface along the path between the contact location and the collection location during which the sorbent and the flue gas are in contact with one another.

34. A method according to claim 33, wherein modifying at least one of the surface of the carbonaceous sorbent and a surface along the path between the contact location and the collection location includes treating the carbonaceous sorbent with an additive to increase the stickiness of the carbonaceous sorbent.

35. A method according to claim 34, wherein treating the carbonaceous sorbent with an additive to increase the stickiness of the carbonaceous sorbent includes treating the carbonaceous sorbent with ammonium halide.

36. A method according to claim 33, wherein modifying at least one of the surface of the carbonaceous sorbent and a surface along the path between the contact location and the collection location includes imparting an increased electrical charge to the carbonaceous sorbent.

37. A method according to claim 21, wherein the products of fuel conversion are traveled through an air heater to effect transfer of heat from the products of fuel conversion to an air stream and disposing carbonaceous sorbent into contact with the products of fuel conversion at a contact location includes injecting the carbonaceous sorbent upstream of the air side of the air heater.

38. A method according to claim 21, wherein the products of fuel conversion are traveled through an air heater to effect transfer of heat from the products of fuel conversion to an air stream and disposing carbonaceous sorbent into contact with the products of fuel conversion at a contact location includes injecting the carbonaceous sorbent both upstream of the air side of the air heater and upstream of the flue gas side of the air heater.