Characteristics of solid hold up and circulation rate in the CFB reactor with 3-loops
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.]. Chem. Eng., 1810), 1000-1(}04(2f101)
Characteristics of Solid HoM Up and Circulation Rate in the CFB Reactor with 3-Loops Jong-Min Lee ~, Jae-Sung Kim and Jong-Jin Kim Advanced Power Generation & Combustion Group, Power Generation Lab., Korea Electric Power Research Institute, KEPCO, Daejeon 305-380, Korea (Received 5 Afarch 2001 9 accepted 2 .hdy 200t)
Abstract-The effects of the 11 PA/[PA+SA] ratio, u)tal v)Iid invenmr'y' and fluidizing vetocky of toopseal on the axial solid holdup and the ~lid circulation rate have been determincd with different particle sizes t 174, I9% 281,377 gin) mad particle Upes (silica staid: narrow PSD, coal ~sh: wide PSD~ in a CFB reactor with 3-k)ops. A simple model tbr solid hold-up based on the previous works was in agreement with the experimental data. With increasing t J,,, G., increased exponentially, and in the center-loop, G, was 1.5 times Iarger than that li)und in the other side-loops, As the PA/[PA+SA] ratio increased, and as SA iniection tx~rt was placed at a lower part in the riser, the axial solid holdup and (;, increased. With increasing fluidizing velocity, of loopseal u) a~mut 1.5u,,~,, G, ~)mewhat increased, but above the gas x,elocity of 1,5a,~,. the loopseal lost the ability of the control of G. The folk)wing correlation tbr the solid circtflation rate in the CFB was developed with good accuracy; G., qJ,,.,[PA/TA]e'~[H,/H~]"~[Ar] -~ ~[Fr]>'"'[KU,,/U,]-~4,. Key words: CFB, 3-L(x)ps, Axial Solid Hoid-Up. Solid Circulation Rate
INTRODUCTION
on the other hand. are a ~lativeiy simple way to determine the overJ1 vertical profile of the crass-sectional average solids concentra-
The chvuiating fluidized bed (CFB) has been successfully used in the tx4roleum refining industry for the catalytic cracking of crude oil since the early 40"s. Its industrial use for noncatalytic reactions started with the Lurgi CFB calciner around 1970, and during the [980"s CFB's found wide application for combustion [Grace et at., [996]. CFB combustion technology is now economically so important that about 240 CFB combustion units (>50 MWth) with a total power of 36~000 MWth are in operation. One of these CFB units is the Tonghae CFB power plant with a total power for 400 MWe (200 MWe:,.2 unit) in Korea. It has been under commercial operation since 1998, where Korean anthracite is used as fuel [Lee and Kim, 19991. The Tonghae CFB boiler consists of a rectangular furnace, three cyclones, loopseals and fluidized bed heat exchangers (FBttEs) and a fluidized bed ash cooler (FBAC). Unlike the existing CFB units, the furnace of which aspect ratio is more than 2 : 1 has three loops for circulation of solid particles. In the furnace, coal ash is only used as bed material due to much ash in coal fed. Therefore, file characteristics o f the gas and solid flow are expected to be somewhat different, On the other hand, knowledge of the flow pattern of gas and particles in the CFB is important for a description of heat transfer and temperature profile and for mapping of the distribution of unburned fuel
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