Fluid bed bubbling

Because bubbles occupy space in a bubbling fluid bed, the expansion of the bed becomes a function of both the bubble velocity and the volume of the gas entering the bed ... 

Other relevant gasifier types are bubbling fluid beds being tested by Enerkem and the high-pressure high-temperature slurry-fed entrained flow Texaco gasifier. 

Bubbling fluid-bed furnace indirectly heated by using steam as the fluidizing medium PulseEnhanced heater. Air pollution control (APC) wet scrubber. 

On this view of the reactor it is not surprising to find Astarita and Occone s methods for uniform kinetics work for the bubbling fluid bed. Replacing kcp by kcp x, t) F[/ K(y)cp(y)dy]. Thus the balance over the dense phase is... 

The summary withdrawal of Indiana s support was all the more galling to Mr. Kellogg because it meant Indiana had selected a rival company, Hydrocarbon Research, Inc., to be its partner in development, design, and construction of a hydrocarbon synthesis facility. Mr. P. C. ( Dobie ) Keith had founded Hydrocarbon Research for the specific purpose of developing an American version of Germany s Fischer-Tropsch synthesis. Keith s Hydrocol Process would use bubbling fluid bed reactors. 

Wood Gasification in a Pressurized, Air-Blown, Bubbling Fluid-Bed Gasifier... 

Bubbling fluid beds have been selected for further development by several companies including Union Fenosa (16) who have built and operated a 200 kg/h pilot unit in Spain, Dynamotive who have a 75 kg/h unit in Canada based on a RTI design (17) with a 10 t/d plant under construction (18) and Wellman who have built a 250 kg/h unit in the UK. Many research units have been built as they are relatively easy to construct and operate and give good results (14, and in these proceedings). 

Bubbling fluid beds have many attractive features, particularly for research and development, which include ... 

A typical plant configuration is shown in Figure 4, in this case based on a bubbling fluid bed, but similar principles apply to most reactors. 

CR S is operating a 10 kg/h circulating fluid bed unit with the char combustor integrated into the base of the CFB riser as a bubbling fluid bed (22) as indicated in Figure 5. Liquid yields of 60-70% wt on a dry feed basis have been achieved. 

Char is burned in a secondary bubbling fluid bed combustor. The hot sand is recirculated to the pyrolyser,... 

Bubbling Fluid Bed continuous phase solids dispersed phase gas... 

An advanced power plant can use FBC to increase its fuel efficiency and lower harmful emissions. Inside the combustor, there is a bed of inert material that will not be burned itself, typically a form of sand. To the solid fuel particles that are added to the bed is mixed a solid sorbent, which absorbs potentially harmful substances released during combustion. Typically, when coal is used as fuel, limestone or dolomite is used as sorbent to absorb sulfur that would otherwise react and be emitted as sulfur oxide, a strong atmospheric pollutant. The solid particles are fluidized by the injection of a fluid, typically heated air. There are two kinds of arrangements for the bed of solids that is hit by the fluid, either a bubbling fluid bed or a circulating fluid bed. 

The most difficult problem to solve in the design of FT reactors is the high exothermicity combined with a high sensitivity of product selectivity to temperature. Hence, the reactor must have provisions for efficient heat removal. Four reactor types are considered today, namely, multi-tubular fixed bed reactors, slurry bubble column reactors, circulating fluidized bed reactors, and bubbling fluid bed reactors. 

Fig. 10.7 Types of fluidized bed reactors [43], Reprinted with permission from the authors. The primary fluidized bed reactor types 1 bubbling fluidized bed, 2 turbulent fluidized bed, 3 circulating fluidized bed, 4 riser, 5 drowner, 6 cross-current fluid bed, 7 counter-current fluid, 8 spouted fluidized bed, 9 floating fluidized bed, 10 twin fluidized bed. The key issues leading to re-design of the conventional bubbling fluid bed A higher gas velocity, B counter-current contacting is beneficial, C incompatible differences in desired environment, D dusty environment, E large paiticles/low gas load...

In the development of bubble fluid bed models, first theoretical relations for bubble properties based on single bubbles were Introduced which led to elegant models with only the effective bubble dlauneter as fitting parameter (level II models). The assumptions were too far from reality, however, and more and more empirical relations have been Introduced In later models. 

---