Gas–liquid multiphase flows play an essential role in the workings of Nature and
the enterprises of mankind. Our everyday encounter with liquids is nearly always
at a free surface, such as when drinking, washing, rinsing, and cooking. Similarly,
such flows are in abundance in industrial applications: heat transfer by boiling is
the preferred mode in both conventional and nuclear power plants, and bubbledriven
circulation systems are used in metal processing operations such as steel
making, ladle metallurgy, and the secondary refining of aluminum and copper.
The dual fluidized beds experimental set up is made of transparent perspex material. The
system consists of a fast bed riser, a cyclone to separate the solids, a down comer with a L-
valve, a bubbling fluidized bed and a return pipe with another L-valve. The system is
shown schematically in Fig 1. The solids after passing through the fast bed riser gets
separated in the cyclone, descend downwards through the down comer and enter the
bubbling bed reactor through the L-valve. A part of bed materials in the bubbling bed
system are then transferred back into the...
When analyzing kinetic data or designing a chemical reactor, it is important
to state clearly the definitions of reaction rate, conversion, yield, and selectivity.
For a homogeneous reaction, the reaction rate is defined either as the
amount of product formed or the amount of reactant consumed per unit
volume of the gas or liquid phase per unit time. We generally use moles
(g mol, kg mol, or lb mol) rather than mass to define the rate, since
this simplifies the material balance calculations.
Defects, the scourge of the metalcaster. These can be as simple as broken or loose sand,
or more complicated like gas bubbles. In any case, it doesn't look good, and it may make
the casting useless.
Now, I'm pretty good at casting , so I don't make many mistakes... but here's one that
got by me:
This casting shows a very common defect, flash. This is where the
mold somehow seperated enough to allow metal between the halves,
along the parting line. (See also the trivet for more flash.) You can
see the inside circle here is nearly completely filled in with flash. ...
Preface Nomenclature CHAPTER 1. PHASE CHANGE, NUCLEATION, AND CAVITATION 1.1 Introduction 1.2 The Liquid State 1.3 Fluidity and Elasticity 1.4 Illustration of Tensile Strength 1.5 Cavitation and Boiling 1.6 Types of Nucleation 1.7 Homogeneous Nucleation Theory 1.8 Comparison with Experiments 1.9 Experiments on Tensile Strength 1.10 Heterogeneous Nucleation 1.11 Nucleation Site Populations 1.12 Effect of Contaminant Gas 1.13 Nucleation in Flowing Liquids 1.14 Viscous Effects in Cavitation Inception 1.15 Cavitation Inception Measurements 1.16 Cavitation Inception Data 1.17 Scaling of...
Cold seeps occur in geologically active and passive continental margins, where pore
waters enriched in methane are forced upward through the sediments by pressure gradients. The
advective supply of methane leads to dense microbial communities with high metabolic rates.
Anaerobic methane oxidation presumably coupled to sulphate reduction facilitates formation of
carbonates and, in many places, generates extremely high concentrations of hydrogen sulphide in
A dual fluidized beds system essentially comprises of two fluidized bed reactors coupled
together with a provision of gas or materials transfer in between. It may be a combination of
circulating-circulating or bubbling-circulating or bubbling-bubbling type systems. A noble
application is in a gasification process for coal or biomass where nitrogen of air is not
allowed to dilute the product gas.
The purging device must be designed to accept 5 mL samples with a water
column at least 3 cm deep. The gaseous head space between the water column
and the trap must have a total volume of less than 15 mL. The purge gas
must pass though the water column as finely divided bubbles with a diameter
of less than 3 mm at the origin. The purge gas must be introduced no more
than 5 mm from the base of the water column. The purging device illustrated
in Figure 1 meets these design criteria.
An inert gas is bubbled through a 5 mL water sample contained in a
specially-designed purging chamber at ambient temperature. The purgeables are
efficiently transferred from the aqueous phase to the vapor phase. The vapor is swept
through a sorbent trap where the purgeables are trapped. After purging is completed,
the trap is heated and backflushed with the inert gas to desorb the purgeables onto a
gas chromatographic column. The gas chromatograph is temperature programmed to
separate the purgeables which are then detected with a mass spectrometer....