page 591 |
Previous | 1 of 6 | Next |
|
|
Loading content ...
Section Six SOLIDIFICATION, STABILIZATION, AND COMBUSTION RESIDUES 62 CEMENTITIOUS PROPERTIES OF ATMOSPHERIC FLUIDIZED BED COMBUSTION RESIDUES AND THEIR USE IN ENGINEERING APPLICATIONS R.T. Hemmings, Vice President E.E. Berry, President Radian Canada Incorporated Mississauga, Ontario, Canada INTRODUCTION Atmospheric pressure fluidized bed combustion (AFBC) is gaining acceptance for the utilization of "problem" fuels, such as low grade or high-sulfur coals, for thermal power generation. However, it has become increasingly clear that the management of the AFBC by-products can impose a major obstacle to the future development of the technology on a large scale. The development of FBC technology has entered the medium-term phase during which research on the application of residues can be started, an effort that will form the basis for future commercial utilization.1 Although considerable research has been conducted and utilization options have been proposed for AFBC byproducts, commercial applications have not been established to date.2,3 The various uses investigated for AFBC by-products have included numerous attempts to incorporate them in some form of concrete, frequently in combination with portland cement. As part of a comprehensive evaluation of potential uses of AFBC materials, in 1984, Berry2 concluded that their composition was incompatible with portland cement concrete in structural applications. In 1985, Rose et al.4 examined a range of portland cement-based concrete mixes containing spent bed discharge material from the TVA 20 MWe bubbling AFB combustor at Shawnee. These authors concluded that such concretes may have commercial potential in underground mine applications where extended setting times and expansion are acceptable. AFBC residues contain unreacted lime (CaO) and calcium sulfate (CaS04), both of which react exothermically with water and are potential sources of expansive reactions in cemented systems. Further, because of their composition, residues from limestone sorbents, rather than showing pozzo- lanic action, are more likely to provide the lime component necessary to induce pozzolanic reactivity in a fly ash or natural pozzolan.3,5 Recognizing the limitations of the materials, a novel approach to the use of AFBC by-products was reported in 1986 by Rose et al.6 during studies conducted by TVA and the Kentucky Energy Cabinet. This approach involved the production of what was termed "no-cement" concretes from co-utilization of FBC by-products in combination with conventional pulverized fuel fly ash (PFA). The PFA in these mixes was introduced, ostensibly, to act as a "pozzolan" through reactions with CaO from the spent bed residue. Also, to mitigate the temperature rise and to reduce the expansive potential of the FBC by-products, the spent bed residue was prehydrated with ~ 10% by mass of water. The above studies were all conducted on mixes made with spent bed materials from the TVA AFBC pilot plant and two different PFA samples, also from TVA sources (Shawnee Steam and Kingston Plants). For these materials, it was found that specific proportions of constituents (i.e., 1 part PFA to 2.1 parts AFBC spent bed residue to 3.4 parts coarse limestone aggregate) produced optimal, workable concretes at 4-to 5-inch slump, with compressive strengths over 5,100 psi after 60 days of curing. Subsequent work by Bland7 suggested that the ratio Ca(OH)2 to PFA is a chemical factor related to the optimum properties of no-cement binders. All of the studies conducted on the TVA materials were 49th Purdue Industrial Waste Conference Proceedings, 1994 Lewis Publishers, Chelsea, Michigan 48118. Printed in U.S.A. 591
Object Description
Purdue Identification Number | ETRIWC199462 |
Title | Cementitious properties of atmospheric fluidized bed combustion residues and their use in engineering applications |
Author |
Hemmings, R. T. Berry, E. E. |
Date of Original | 1994 |
Conference Title | Proceedings of the 49th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://e-archives.lib.purdue.edu/u?/engext,44602 |
Extent of Original | p. 591-596 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Date Digitized | 2009-12-10 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 591 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | Section Six SOLIDIFICATION, STABILIZATION, AND COMBUSTION RESIDUES 62 CEMENTITIOUS PROPERTIES OF ATMOSPHERIC FLUIDIZED BED COMBUSTION RESIDUES AND THEIR USE IN ENGINEERING APPLICATIONS R.T. Hemmings, Vice President E.E. Berry, President Radian Canada Incorporated Mississauga, Ontario, Canada INTRODUCTION Atmospheric pressure fluidized bed combustion (AFBC) is gaining acceptance for the utilization of "problem" fuels, such as low grade or high-sulfur coals, for thermal power generation. However, it has become increasingly clear that the management of the AFBC by-products can impose a major obstacle to the future development of the technology on a large scale. The development of FBC technology has entered the medium-term phase during which research on the application of residues can be started, an effort that will form the basis for future commercial utilization.1 Although considerable research has been conducted and utilization options have been proposed for AFBC byproducts, commercial applications have not been established to date.2,3 The various uses investigated for AFBC by-products have included numerous attempts to incorporate them in some form of concrete, frequently in combination with portland cement. As part of a comprehensive evaluation of potential uses of AFBC materials, in 1984, Berry2 concluded that their composition was incompatible with portland cement concrete in structural applications. In 1985, Rose et al.4 examined a range of portland cement-based concrete mixes containing spent bed discharge material from the TVA 20 MWe bubbling AFB combustor at Shawnee. These authors concluded that such concretes may have commercial potential in underground mine applications where extended setting times and expansion are acceptable. AFBC residues contain unreacted lime (CaO) and calcium sulfate (CaS04), both of which react exothermically with water and are potential sources of expansive reactions in cemented systems. Further, because of their composition, residues from limestone sorbents, rather than showing pozzo- lanic action, are more likely to provide the lime component necessary to induce pozzolanic reactivity in a fly ash or natural pozzolan.3,5 Recognizing the limitations of the materials, a novel approach to the use of AFBC by-products was reported in 1986 by Rose et al.6 during studies conducted by TVA and the Kentucky Energy Cabinet. This approach involved the production of what was termed "no-cement" concretes from co-utilization of FBC by-products in combination with conventional pulverized fuel fly ash (PFA). The PFA in these mixes was introduced, ostensibly, to act as a "pozzolan" through reactions with CaO from the spent bed residue. Also, to mitigate the temperature rise and to reduce the expansive potential of the FBC by-products, the spent bed residue was prehydrated with ~ 10% by mass of water. The above studies were all conducted on mixes made with spent bed materials from the TVA AFBC pilot plant and two different PFA samples, also from TVA sources (Shawnee Steam and Kingston Plants). For these materials, it was found that specific proportions of constituents (i.e., 1 part PFA to 2.1 parts AFBC spent bed residue to 3.4 parts coarse limestone aggregate) produced optimal, workable concretes at 4-to 5-inch slump, with compressive strengths over 5,100 psi after 60 days of curing. Subsequent work by Bland7 suggested that the ratio Ca(OH)2 to PFA is a chemical factor related to the optimum properties of no-cement binders. All of the studies conducted on the TVA materials were 49th Purdue Industrial Waste Conference Proceedings, 1994 Lewis Publishers, Chelsea, Michigan 48118. Printed in U.S.A. 591 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Tags
Comments
Post a Comment for page 591