Corrosion and viscous ash deposition of a rotary air preheater in a coal-fired power plant

Chen, Heng; Pan, Peiyuan; Shao, Huaishuang; Wang, Yungang; Zhao, Qinxin

doi:10.1016/j.applthermaleng.2016.10.160

Cited by 70 publications

(32 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Formation of H 2 SO 4 occurs in a temperature range between 200 and 400 C while its content depends on the amount of sulphur trioxide SO 3 and water vapour in the flue gas. The temperature of condensation decreases proportionally to the content of sulphuric acid or water vapour in flue gas and it is in the range of 95-160 C [9][10][11]. However, roughly 90% of sulphuric acid condenses in a temperature range between 115 and 138 C [12].…”

Section: Discussionmentioning

confidence: 99%

Analysis of Coal-Fired Power Unit Operation in Reduced Minimum Safe Load Regime

Żymełka¹,

Żyrkowski²,

Bujalski³

2018

Thermal Power Plants - New Trends and Recent Developments

View full text Add to dashboard Cite

Large coal-fired power plants were typically designed as a base load units. Any changes in load level, as well as start-up time, are noticeably slow on that kind of units. However, in order to adapt to changing market conditions with increasing number of renewable energy sources, coal-fired power plants need to improve their flexibility. In the paper, 200 MWe class unit has been taken into consideration. During the test campaign, a minimum safe load of the unit was decreased from 60 to 40%. Paper presents results of a model that was made using Ebsilon ® Professional software. The simulation model is comprised of boiler and turbine part of the power unit. Obtained results were validated using measurements collected from the test campaign. Parameters important from the technical and economical point of view were investigated. Results revealed that simulation model can be utilised successfully to scrutinise coal-fired units under off-design operation conditions. As the outcome of the performed analysis, a number of issues related to low load operation of the coal-fired unit are presented and discussed. Paper indicates sensitive areas that need to be addressed when operation in decreased safe load is considered. Finally, overall potential for flexibility improvement for 200 MWe class coal-fired units has been evaluated.

show abstract

Section: Discussionmentioning

confidence: 99%

Analysis of Coal-Fired Power Unit Operation in Reduced Minimum Safe Load Regime

Żymełka¹,

Żyrkowski²,

Bujalski³

2018

Thermal Power Plants - New Trends and Recent Developments

View full text Add to dashboard Cite

show abstract

“…They indicated that the high sulfate content can act as a cementing agent for the formation of the deposits. Chen et al 15 sampled the deposits and corroded heat transfer elements in the cold end of RAPH and conducted analysis by X-ray fluorescence (XRF), XRD, and SEM, and they found that the condensation of H 2 SO 4 rather than NH 4 HSO 4 was the main cause for the corrosion and ash deposition. It can be seen that researchers still have different views and understandings on the ash plugging mechanism in the RAPH.…”

Section: Introductionmentioning

confidence: 99%

Study on the formation process of low‐temperature ash deposition induced by ammonium bisulfate in pulverized coal‐fired boiler

Wang

Tang

et al. 2019

Asia-Pacific J Chem Eng

View full text Add to dashboard Cite

In order to explore the mechanism of low-temperature ash deposition induced by ammonium bisulfate (ABS), ash deposits, and a corroded heat transfer plate in the rotary air preheater (RAPH) of a 1,000-MW pulverized coal-fired power plant in China were analyzed by X-ray fluorescence, ion chromatography, X-ray diffraction, and scanning electron microscope equipped with energy dispersive X-ray spectroscopy. The element composition, main compounds, and ammonium ion in the samples were analyzed. The thermal gravimetric analysis of ash samples was conducted to infer the type of ammonium salt ultimately existing in the ash. The prediction of the ABS deposition range coincides well with both the area of serious ash deposition and the area of NH 4 + distribution obtained by ion chromatography. The cause for corrosion and plugging in the RAPH was proposed by analyzing the reactions or mineral transformations involved in the ash deposits. The results indicate that ABS can form in a large height range in the RAPH. The ammonium induces the sulfur trioxide to deposit on and react with the metal plate or the ash particles to form sulfates, which act as the bridging agent, finally leading to serious plugging problems in the RAPH. FIGURE 7Morphology of the ash sample (a) and metal plate and energy dispersive X-ray spectroscopy analysis areas (b)

show abstract

“…The ABS has a higher dew point and can condense in the middle and cold layers of rotary regenerative air-preheater (RAPH). Liquid ABS can capture fly ash and other complex particles in the flue gas such as sulfuric acid droplets, ammonium nitrate, and calcium salt and finally lead to the plugging and corrosion of RAPH [1,[5][6][7]. The plugging can increase the pressure drop in the RAPH and then reduce the unit load due to the limit of induced draft fan [1].…”

Section: Introductionmentioning

confidence: 99%

Influence of operating conditions on ammonium bisulfate deposition in the rotary air preheater of coal-fired power plants

Wang¹,

Bu²,

He³

et al. 2019

THERM SCI

View full text Add to dashboard Cite

Original scientific paper https://doi.org/10.2298/TSCI180524213W To achieve the maximum NOx reduction in coal-fired power plant, excess ammonia is injected into the selective catalytic reduction reactor, which leads to the formation of ammonium bisulfate due to the reaction between ammonia escaping from the selective catalytic reduction reactor and SOx in the flue gas. Ammonium bisulfate can condense in the rotary regenerative air-preheater, which would adversely affect the safe and efficient operation of the air-preheater. An improved radian number is proposed to estimate the ammonium bisulfate deposition. The operating conditions or modes of the air-preheater, i. e., air-flow bypass, cold--end protection and different splitting fluid sector arrangements, are comparatively studied to analyze the temperature and ammonium bisulfate deposition distributions. The hot air re-circulation is not helpful to mitigate the ammonium bisulfate deposition in medium matrix layer. The splitting gas sector arrangement would cause more serious plugging problem, but the splitting air sector arrangements can alleviate the ammonium bisulfate deposition. To increase the air bypass rate is more effective than the splitting air sector arrangements to alleviate the plugging problem. The improved radian number is more reasonable to reflect the ammonium bisulfate deposition compared with the original radian number.

show abstract

Corrosion and viscous ash deposition of a rotary air preheater in a coal-fired power plant

Cited by 70 publications

References 22 publications

Analysis of Coal-Fired Power Unit Operation in Reduced Minimum Safe Load Regime

Analysis of Coal-Fired Power Unit Operation in Reduced Minimum Safe Load Regime

Study on the formation process of low‐temperature ash deposition induced by ammonium bisulfate in pulverized coal‐fired boiler

Influence of operating conditions on ammonium bisulfate deposition in the rotary air preheater of coal-fired power plants

Contact Info

Product

Resources

About