Wear Mechanisms of Chromia Refractories in Slagging Gasifiers

Abstract

The hot‐face refractory lining is a key component of gasification systems. The refractory liner protects the gasification system from the high‐temperature corrosive gaseous and from the molten slag environment associated with the conversion of carbon feedstocks. This paper will discuss the effect of gasifier operating conditions and carbon feedstock slag/ash chemistry on the refractory service life. Particular attention is focused on the wear mechanism of chromia refractories, determined through postmortem analysis of spent refractory bricks from service in gasifiers. Also presented is the behavior of a phosphate‐containing chromia refractory with improved resistance to structural spalling.

A Critical Review of Mineral Matter Related Issues during Gasification of Coal in Fixed, Fluidized, and Entrained Flow Gasifiers

“…Reliability and availability of the gasifier is dependent upon ability of refractory lining to withstand elevated temperature (>1773 K), temperature fluctuations, attack of hot corrosive gases, variation in feedstock, cyclic change in oxidizing and reducing conditions, alkali vapor and molten slag [103]. The refractory lining used in gasifiers varies with design.…”

“…Studies were conducted to determine the causes of corrosion for chromia rich refractories [103,109,110]. Postmortem analysis on spent high chromia from a commercial gasifier indicated that the reaction between FeO in slag and Cr2O3 in refractory forming iron chromium spinel as one of the primary reasons for degradation of the refractory [89].…”

“…Postmortem analysis on spent high chromia from a commercial gasifier indicated that the reaction between FeO in slag and Cr2O3 in refractory forming iron chromium spinel as one of the primary reasons for degradation of the refractory [89]. While the formation of iron chromium spinel prevented the diffusion of FeO into the refractory, it was also suggested to have resulted in chemical spalling [103]. Although Cr2O3 provided corrosion resistance, it did not prevent slag from penetrating.…”

“…One way to reduce penetration is through adding phosphate to the high chrome refractory. Addition of phosphate to high chromia refractory not only reduced porosity but also increased the viscosity of the penetrated slag by interacting with it and consequently reduced spalling [103]. The other approach to reduce slag refractory interaction is to reduce the wettability of refractory by the slag by changing the slag composition or refractory properties.…”

Materials Challenges for Advanced Combustion and Gasification Fossil Energy Systems

“…Further limiting the discussion to slagging gasifiers, the fuel mineral matter can be expected to undergo phase changes due to its properties and system conditions. Some of these mineral components will liquefy at gasifier temperatures (T = 1573 K to 1873 K (1300°C to 1600°C), P = 2.75 MPa, and log(P O2 ) = -9 to -7) [24] and may coalesce into a stream that leaves the gasifier as slag. Some of the mineral matter will also leave the system entrained with the product syngas as flyash.…”