Bodies Also called vapor heads or flash chambers; the unit
where vapor-liquid separation takes place. Also a label given
to the basic module of an evaporator, comprising one heating element
and one flash chamber.
Calandria The unit in which heat transfer takes place.
Compression Evaporation A process in which evaporated vapor
is compressed to a higher pressure level and then condensed. The
compressed vapor provides heat required for evaporation. Energy
economy obtained by multi-effect evaporation can often be equalled
in a compression evaporation system.
Condenser Evaporator equipment used to condense the vapor
from the last effect or used as an intercondenser in multi-stage
vacuum producing systems.
Cooling Water Water used in the condenser of an evaporator
to condense the vapor phase that exists in the separator. Cooling
water can come from cooling towers or reservoirs, or once-through
process water can used.
Direct Contact Condenser Condenses vapors as they are contacted
with the cooling medium. There are no heat transfer surfaces
and therefore the vapor pressure drop is low. Due to contact
with the process solution, the cooling water will require waste
Effect One or more bodies boiling at the same time.
Evaporator The entire system of effects, not necessarily
one body or one effect.
Fouling Formation of deposits other than salt or scale.
Heat Pump A device in which a refrigerant fluid is continuously
circulated through a closed cycle. The gaseous refrigerant is
first compressed and then allowed to condense by giving out heat
to a cooler environment. The liquid refrigerant is then throttled
to low pressure, by means of an expansion valve and allowed to
evaporate in another heat exchanger, drawing in heat. The vapor
is then circulated to the compressor to begin another cycle.
Intercondenser A condenser within a multistage system that
condenses some of the steam between stages and reduces steam consumption.
Mechanical Compression Uses a compressor driven by a mechanical
drive to compress all the overhead vapors.
Mechanical Pumps One of two devices (see steam jet ejectors)
used to produce a vacuum. More energy efficient than steam jet
ejectors but less reliable due to the number of moving parts involved.
Precondenser A condenser that removes process vapors and
permits the use of smaller vacuum pumps.
Refrigeration Systems that absorb heat not wanted or needed
and reject it elsewhere. Heat is removed from the system by evaporation
of a liquid refrigerant and is rejected by condensation of the
Scaling Growth or deposition on heating surfaces of a material
that is either insoluble or has a solubility that decreases with
an increasing temperature.
Staging Two or more sections of a single effect evaporator
operating at different concentrations.
Steam Jet Ejectors One of two devices (see mechanical pump)
used to produce a vacuum. Jet ejectors usually have lower initial
costs, lower maintenance costs (fewer moving parts) but higher
operating costs (less energy efficient) than mechanical systems.
Multistage jet ejectors (connected in series) improve thermodynamic
Surface Condenser A condenser with a heat transfer surface
on which condensing occurs. The heat transfer surface is subject
to fouling, corrosion and plugging. Generally more expensive
than direct contact condensers. Cooling water is not contaminated
with the process solution.
Thermal Compression Uses a steam jet to compress a fraction
of the overhead vapors with high pressure steam.
Thin Film Thin films of solution are created in evaporators
to maximize the liquid surface area per unit volume of flow and
therefore facilitate rapid evaporation.
Sources: ref: 373, 374, 423.
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