HCL Technologies - Interview Procedure
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HCL Technologies - Interview Procedure


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Visit for latest Jobs Chat with other engineers at Get latest Fresher / Experienced Engineering Jobs at For More Placement Papers visit Page 1 of 214 HCL Paper Pattern on 25th September 2008 1) In a murder case there are four suspects P,Q,R,S. Each of them makes a statement.
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Publié par
Nombre de lectures 30
Langue English


Preface, ix
Gas Treating with a Physical Solvent; 1
J. W Sweny
Comparison of Physical Solvents Used for Gas Processing, 42
R. W Bucklin and R. L Schendel
Equilibrium Between
J. S. Staton, R. W Rousseau, and J. K. Ferrell
R. N. Maddox, G. J. Mains, A. Bhairi, and A. Shariat
for EOR in Venezuela, 164
J. C Polasek and J. A. Bullin
The Rectisol Wash-New Developments in Acid Gas Removal from
and Ethanolamine Solutions, 212
Synthesis Gas, 80
G. Ranke and V Mohr
G. Aldana, R. Arai, and D. G. Elliot
Process Considerations in Selecting Amines, 190
Improved AMISOL Process for Gas Purification, 112
M. Kriebel
Regeneration of Physical Solvents in Conditioning Gases from Coal, 131
An Evaluation of Sources of
H C0
conditions and equipment are so unlike the others.
omit methanol from comparisons of solvents since the processing
special recovery methods to prevent high solvent losses. This paper will
normal process conditions and therefore requires deep refrigeration or
Of these solvents, methanol is relatively high in vapor pressure at
dialkyl ethers or polyethylene glycol - mixture of -MPE Sepasolv
Selexol dimethyl ether of polyethylene glycol or - Selexol
- methanol Rectisol
pyrrolidone or NMP - normal methyl Purisol
- propylene carbonate or PC Fluor Solvent
tributyl phosphate or TBP - Estasolvan
solvents are:
Today the commercially proven physical solvent processes and their
better suited to meet specific process requirements, have been developed.
As developments in physical solvent processing matured, other solvents,
hydrocarbon loss as the only contingent requirement.
removal with minimum than other physical solvents for bulk C0
methane solubility. Even today, propylene carbonate ranks somewhat better
a relatively low solubility concurrent with Solvent was its high C0
The chief criterion for selection of propylene carbonate for Fluor
that time.
gas treating plants with competitive physical solvents developed since
of mechanical arrangement and flow scheme have since been used in several
used to recover about half of the required pumping energy. The same type
pressure flash tank to minimize methane losses. Hydraulic turbines were
compressor was used to recycle the flash gases from an intermediate
successively lower pressures to achieve solvent regeneration. A
removed from the methane, followed by a series of flash tanks at
was contactor where the C0 high pressure very simple, involving only a
circulation pumps and the recycle gas compressor. The process design was
was unique in that the only significant energy consumers were the solvent
equipment were required to satisfy the process conditions. The process
nor alloy steel and operating costs were achieved. Neither external heat
carbon dioxide removal. The process objectives of lowest possible capital
-ambient temperatures for of a kind using a physical solvent at mild sub
El Paso's Terrell County Treating Plant was a first Company and Fluor.
was commercialized by the cooperative efforts of El Paso Natural Gas
In the late 1950's, the Fluor Solvent process using propylene carbonate
Even though there can be sizeable interaction effects between the solutes
from ideal, so that Henry's Law is applicable only in dilute solutions.
S tend to deviate significantly and H solute. The polar compounds C0
In all cases, the solution is relatively dilute with respect to the
vs 1/T. log plot of Henry's constant a similar ether on a log slope of
Sepasolv was extrapolated from published data7 at 0°C using the same
Sepasolv. The value for the commercial solvents we are comparing except
atmosphere partial pressure of solute is in the public domain for all of
temperature for this comparison. Solubility data at 25°C and one
most of the commercial applications, so 25°C is a suitable reference
-20°C cover condition. Operating Process temperature ranges from 30°C to
volume of carbon dioxide per volume of solvent at a suitable reference
on the most significant comparative solvent data is solubility data
removal is desired cases wherein either bulk or essentially complete C0
and landfill gas) or synthesis gases (hydrogen and carbon monoxide). In
primarily with acid gas removal from either hydrocarbon gases (natural
All of the physical solvent processes being compared are concerned
largely determined by the required volume of solvent circulation.
equipment and piping as well as power requirements for the process are
size of process in similar processing schemes. This is true because the
reference condition is a useful comparative value for solvents to be used
vapor at the reference condition per unit volume of solvent at the
effectiveness in removing the solute. The volume of solute expressed as
saturation would not be good indicators of the solvent's relative
mol fraction or weight portion of solute in the solvent at comparison of
differences in densities of the various solvents. Therefore, the
There is a wide variation in molecular weights and significant
to carbon dioxide.
compares each solvent's affinity for various gases relative Table 2
Estasolvan process have been built. plants using the
solubility of TBP may explain why no commercial The relatively poor C0
construction for a simple cycle process scheme.
noncorrosive, nontoxic and require only carbon steel solvents are
is a comparison of miscellaneous solvent data. All of the Table 1
in the case study later in this paper.
carbonate are compared in this manner Selexol and propylene performance.
to illustrate how some solvents differ in basic character and
compositions for identical process configurations and conditions in order
volumes, and stream circulation rates, relative recycle stream
possible, however, to use public information to indicate relative
cannot be published without violating existing secrecy agreements. It is
Therefore, definitive comparative information about solvent performance
Most of the equilibrium data are proprietary to the process licensors.2
thermally stable for water removal by atmospheric distillation. PC
chilldown. TBP is different solvent for hydrate control during feed gas
PC and TBP have limited water solubility and therefore require a
control the water content of the circulating solvent stream.
atmospheric pressure. Slipstreams of these solvents can be processed to
to reject water at are thermally stable at temperatures required
Sepasolv have infinite water solubility and Selexol and in Table 1, NMP,
Differences in water handling flexibility can also be important. As shown
Effect of Water in Feed gas
S removal is controlling. grain per 100 SCF for natural gas) means H
S usually permitted in the treated gas (1/4 the low concentration of H
S is present in more than trace concentrations. This is so because if H
In fact, it is difficult to find situations where PC would be recommended
S removal. where propylene carbonate would be recommended for selective H
Actual experience confirms this prediction. The authors know of no cases
S removal from gas containing carbon dioxide is required. selective H
Sepasolv are superior to PC if Selexol, NMP and The data indicate that
S Removal Selective H
washing of both the treated gas and the rejected acid gases for solvent
pressure about five times higher than PC. The licensor recommends water
solvents, solvent losses have generally been very low. NMP has a vapor
carbonate has a vapor pressure much higher than the high molecular weight
All of the solvents have low vapor pressures. Although propylene
Solvent Loss
performance for various processing techniques.
chemical inertness, royalty cost, thermal stability and proven plant
loss or removal with acid gas removal, solvent cost, solvent supply,
controlling water content of circulating solvent, concurrent hydrocarbon
ease of , HCN, etc., ease of handling water content in feed gas
COS S, and characteristics of the solvents, such as selectivity for H
The selection of a physical solvent process depends on process objectives
other in the majority of actual process conditions.
selectivities will not vary significantly in relation to each relative
multicomponent mixtures, it is assumed for this comparison that the in 2
amount of methane product in the treated gas.
the methane, the higher the recycle compressor horsepower for the same
The higher the solubility of in the various solvents as shown in Table 3.
contactor can be predicted from the solubility of methane high pressure
horsepower required to recycle these intermediate flash tank gases to the
compression relative recycle of flash gas to limit methane losses. The
A major energy user in physical solvent processes is compression for the
Effect of Recycle Compressor
slipstream regenerator bottoms temperature and pressure conditions.
water content of the return solven

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