Shear Strength Testing of Synthetic Ash: The Role of Surface vs Interparticle Adhesions

Abstract

In thermal power plants, deposition of fly ash on the surfaces of the heat exchanger causes a significant drop in the heattransfer efficiency and this inhibits effective fuel utilization. It is widely accepted that alkali metals such as sodium and potassium are the trigger for fly ash deposition given that the alkali metals potentially form low-melting-point materials which have adhesive properties and can be deposited on the surface of the exchanger. However, detailed mechanistic studies of this process are challenging due to the chemical complexity and diversity of fly ash samples collected from commercial thermal plants. Herein, it is demonstrated that fly ash deposition triggered by alkali metals can have different mechanisms due to the effects of interparticle and/or surface adhesions. A key enabler for facilitating detailed mechanistic studies is the combined use of tensile and shear strength testers linked to a synthetic ash strategy that utilizes chemically synthesized inorganic particles.

Phosphorus-Related Ash Chemistry at High Temperatures: Role of Aluminum on Particle Adhesion

“…Ash chemistry is complicated, and a mechanistic understanding is required. However, this is a challenging topic because chemical characteristics of ash particles generated from commercial plants contain various elements and minerals. ,,,, We previously studied the ash adhesion behavior using synthetic ashes as models for ashes. ,− The synthetic ashes consisted of the target element to induce particle adhesion at high temperatures such as P and base materials, which are stable particulate materials. The simple and controllable chemical composition of synthetic ashes has been used to understand the relationship between the ash chemistry and adhesion behavior.…”

Optimization of a Sootblowing System for Effective Deposit Removal in Radiant Syngas Cooler Using Numerical Simulation

“…The thickness of a deposit on the membrane wall of RSC has an important effect on the heat transfer efficiency . High thermal resistance caused by the ash and slag layer reduces the heat absorption and transfer capacity of the membrane wall, leading to an increase in the outlet temperature of syngas and a decrease in the efficiency of gasification system. − Additionally, deposition accumulation can cause erosion on membrane wall tubes and reduce the reliability of RSC operation, generating an abnormal operation and even blockage at the slag tap due to extensive slag detachment. Such a circumstance seriously affects the operating safety of RSC .…”