Ash deposition in syngas coolers of slagging gasifiers. Final report

Technical Report · Sat Dec 01 04:00:00 EST 1984

OSTI ID:6143196

Austin, L G; Kinneman, W P; Abbott, M F; Tangsathitkulchai, M

Entrained slagging gasifiers are prime candidates for use in advanced coal-gasification-combined cycle (CGCC) power plants. The deleterious effects of coal ash give such problems as reduction of heat exchanger efficiency, corrosion, and premature failure of the system. This investigation was undertaken to study the fundamental mechanisms of ash adhesion to various materials proposed for use in heat exchangers of entrained slagging gasifiers, under conditions simulating the environment in such gasifiers. Ash adhesion was also studied under conditions simulating pulverized coal boiler environments for comparison. In general, it was found that coal ash and slag adhere more strongly to oxidized metal surfaces, present in pulverized coal boilers, than to metal surfaces with a sulfide scale, which are formed in gasifier surroundings. Under oxidizing conditions, molten coal ash reacts readily with the oxide scale above a critical temperature, which depends on the coal ash composition. Above this temperature, the adhesive strength increases exponentially with temperature. Adhesion to low-alloy steels was generally somwhat higher than to austenitic stainless steel or aluminized steel. Under reducing and sulfidizing conditions, adhesive forces between slag, scale, and substrate are generally less than under oxidizing conditions and do not increase rapidly with temperature. The reasons are that silicate glass from the flyash does not react readily with a sulfide scale, and that sulfide scales do not adhere as strongly to a metal substrate as oxide scales. Adhesion to aluminized surfaces was especially low under reducing conditions. The most adherent deposits are formed by iron-rich particles, which are believed to have been derived from pyrites in the coal. 10 references, 3 figures, 8 tables.

• Research Organization: Pennsylvania State Univ., University Park (USA). Dept. of Mineral Engineering
• OSTI ID: 6143196
• Report Number(s): EPRI-AP-3806; ON: TI85920215
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010404* -- Coal
Lignite
& Peat-- Gasification
ADHESION
ASHES
COAL GASIFICATION
COOLING
DATA
DEPOSITION
ENTRAINMENT
EXPERIMENTAL DATA
FLUIDS
FOULING
FUEL GAS
FUELS
GAS FUELS
GASES
GASIFICATION
HEAT EXCHANGERS
INFORMATION
NUMERICAL DATA
RESIDUES
SLAGS
TEMPERATURE EFFECTS
THERMOCHEMICAL PROCESSES