Effect of Operation Parameters on the Slagging near Swirl Coal Burner Throat

Abstract

Fluid flow, heat transfer, coal combustion, and slagging processes had been numerically simulated near a swirl burner throat. The effect of the ratio distribution of each burner air, their swirling numbers, and the coal character on the slagging process had been analyzed. The computation results indicate that the maximal stickingparticle numbers occur at the uppermost waterwall, while the sticking-particle number at neither waterwall near the swirl burner outlet is very small. The swirling number has a significant effect on the number of the sticking particle. The sticking-particle number increases rapidly with the increment of the outer secondary air and the primary air-swirling numbers, respectively, because it can strengthen the flow entrainment ability to carry more particles to the waterwall. The inner secondary air has a complicated influence on the slagging process. When the inner secondary air-swirling number is about middle intensive degree (about 0.9), the stickingparticle number reaches maximum. If the inner secondary air-swirling number continues increasing, then the coal particles will combust completely and reduce the particle concentration, thus decrease the sticking-particle number. The ratio of each air has a slight influence on the sticking-particle number relative to the swirling number. The coal particles with small mean diameter combust completely, which can reduce the stickingparticle number.

Ash Fusion Characteristics of a High Aluminum Coal and Its Modification

“…Continuous slag tapping is the key to successful operation on entrained-flow bed gasifier, e.g., the viscosity of 2.5–25 Pa·s is required at the temperatures from 1300 to 1500 °C for Shell gasifier. The ash fusion temperature (AFT) of coal partially reflects ash sintering and agglomeration, which strongly influences ash deposition and slag formation in the gasification. − Although some shortcomings exists, the AFT test is still a acceptable way to predict coal slagging tendency during its conversion (e.g., gasification, combustion) . Generally speaking, when coal are used in the industrial entrained-flow gasifier, it is required that its FT < 1380 °C, its ash content ranges from 18 to 22%, and its ash viscosity <25 Pa·S.…”

Measurement of gas species, temperatures, char burnout, and wall heat fluxes in a 200-MWe lignite-fired boiler at different loads

“…Different aerodynamic fields lead to variations in the coal combustion process [1][2][3][4]. The classification system of the International Flame Research Foundation (IFRF) recognizes four different types of flame.…”

Effects of Secondary Air on Flow, Combustion, and NOx Emission from a Novel Pulverized Coal Burner for Industrial Boilers

“…Therefore, in practical operations, the ignition and combustion of PC are desired to be confined in these regions. 7 The volumetric reflux Q (m 3 /s) over a cross-sectional slice of the ICRZ, based on the recirculation velocity and the local radius r of the ICRZ, may be defined as…”

“…In light of the previous attempts, it is obvious that the design of an efficient PC burner is the key to achieving a compromise between low slagging tendency and high combustion efficiency. The inclusion of outer SA has been attempted intensively in the literature, − and this technique has shown to be a promising solution. Swirling outer SA, however, was used in all the above-mentioned studies.…”