Flux addition as a filter conditioner

• US 8,580,151 B2
• Filed: 02/02/2010
• Issued: 11/12/2013
• Est. Priority Date: 12/18/2009
• Status: Active Grant

• Current Assignee: Lummus Technology Inc.
• Original Assignee: Lummus Technology Inc.
• Inventors: Troxclair, Emile J. III
• Primary Examiner(s): LANGEL, WAYNE A
• Application Number:
  US12/698,660
• Publication Number:
  US 20110147666A1
• Time in Patent Office: 1,379 Days
• Field of Search: 252/373, 48 61-1185, 481/97.R
• US Class Current: 252/373
• CPC Class Codes: B01D 29/66 by flushing, e.g. counter-current air-bumps
• CPC Class Codes: C10J 2300/0993 Inert particles, e.g. as heat exchange medium in a fluidized or moving bed, heat carriers, sand
• CPC Class Codes: C10J 2300/0996 Calcium-containing inorganic materials, e.g. lime
• CPC Class Codes: C10J 2300/1807 Recycle loops, e.g. gas, solids, heating medium, water
• CPC Class Codes: C10J 3/485 Entrained flow gasifiers
• CPC Class Codes: C10J 3/721 Multistage gasification, e.g. plural parallel or serial gasification stages
• CPC Class Codes: C10J 3/84 with means for removing dust or tar from the gas
• CPC Class Codes: C10J 3/86 combined with waste-heat boilers
• CPC Class Codes: C10K 1/024 by filtration
• CPC Class Codes: C10K 1/026 by centrifugal forces cyclones B04C

Abstract

Improvements in a gasification system and process for gasifying carbonaceous feedstock with improved energy efficiency. Improved methods and systems for more efficient removal of particulates from a raw synthesis gas while simultaneously providing a novel mechanism for fluxing agent addition to the gasification reactor. A conditioning agent, in the form of coarse fluxing agent particles, is added to the raw synthesis gas upstream from the particle filtration unit. The conditioning agent allows more rapid turnaround of the filtration unit following filter element replacement, extend filter life, facilitates the removal of filter cake from the particle filters, and combines with removed filter cake for recycling to the gasifier. Addition of fluxing agent via this route eliminates the need to premix fluxing agent with the carbonaceous feedstock, thereby maximizing the rate of feedstock addition to the gasification reactor.

Claims

1. An improved process for gasification of a carbonaceous material, comprising:

a. providing a gasification reactor, wherein said reactor converts carbonaceous feedstock to produce a mixture product comprising a first gaseous product stream and char,

wherein said gaseous product stream comprises H₂, and CO,

b. passing said mixture product through an initial separating device, whereby some of said char is removed from said gaseous product stream,

c. introducing a coarse particulate fluxing agent into the gaseous product stream downstream from said initial separating device, wherein said coarse particulate fluxing agent has an average size range between 5 microns and 30 microns,

d. providing a particle filtration unit comprising a plurality of filter elements downstream from the point of introduction of said coarse particulate fluxing agent,

e. depositing a thin layer of the fluxing agent onto and within the pores of the filter elements to condition the filter elements and decrease the subsequent permeability of the filter elements to entrained char particles, while maximizing permeability of the filter elements to synthesis gas;

f. periodically removing a mixture comprising filter-cake from the filter elements by back-pulsing, wherein said filter-cake comprises coarse particulate fluxing agent and char,

g. forming a mixture comprising the removed char of step (b) and the removed filter-cake of step (f), then routing this mixture to the gasification reactor of step (a).

2. The process of claim 1,

wherein said coarse particulate fluxing agent decreases the melting point and viscosity of molten slag in the gasification reactor, thereby assisting in the removal of the molten slag from the reactor.

3. The process of claim 1,

wherein the average size of said coarse particulate fluxing agent is from about 5 to 35 microns.

4. The process of claim 1,

wherein the coarse particulate fluxing agent of step (d) comprises limestone, magnesium oxide, clay, silicates, borates, flyash, slag, and mixtures thereof.

5. The process of claim 1, further comprising a step of passing said mixture product of step (a) into a heat recovery zone prior to step (b),

wherein said heat recovery zone comprises a heat recovery device selected from a group consisting of radiant heat type boiler, water tube boiler, fire tube boiler and combinations thereof.

6. The process of claim 1 or 5,

wherein the gasification reactor of step (a) comprises a first and second stage.

7. An improved process for gasification of a carbonaceous material, comprising:

a. providing a gasification reactor comprising a first stage for partially combusting the carbonaceous material to produce heat and a first mixture product, and an unfired second stage for pyrolyzing the mixture product, wherein said reactor converts carbonaceous feedstock to produce a mixture product comprising a first gaseous product stream and a solid particulate stream,

wherein said first gaseous product stream comprises H₂ and CO,

and wherein said solid particulate stream comprises char;

b. passing said mixture product through an initial separating device, whereby some of said char is removed from said gaseous product stream,

c. introducing a coarse particulate fluxing agent into the gaseous product stream downstream from said initial separating device, wherein said coarse particulate fluxing agent has an average size range between 5 microns and 30 microns,

d. providing a particle filtration unit comprising a plurality of filter elements downstream from the point of introduction of said coarse particulate fluxing agent,

e. depositing a thin layer of the fluxing agent onto and within the pores of the filter elements to condition the filter elements and decrease the subsequent permeability of the filter elements to entrained char particles, while maximizing permeability of the filter elements to synthesis gas;

f. periodically removing a mixture comprising filter-cake from the filter elements by back-pulsing, wherein said filter-cake comprises coarse particulate fluxing agent and char.

g. forming a mixture comprising the removed char of step (b) and the removed filter-cake of step (f), then routing this mixture to the gasification reactor of step (a).

8. The process of claim 7,

wherein the coarse particulate fluxing agent decreases the melting point and viscosity of molten slag in the gasification reactor, thereby assisting in the removal of the molten slag from the reactor.

9. The process of claim 7,

wherein the coarse particulate fluxing agent comprises limestone, magnesium oxide, clay, silicates, borates, flyash, slag, and mixtures thereof.

10. The process of claim 7, further comprising a step of passing said mixture product of step (a) into a heat recovery zone prior to step (b), wherein said heat recovery zone comprises a heat recovery device selected from a group consisting of radiant heat type boiler, water tube boiler, fire tube boiler and combinations thereof.