Method for processing of liquid hydrocarbon raw materials
Technical Field
The invention pertains to the field of petroleum processing and may
find application in petroleum and petrochemical industries, in field of fuel
power engineering.
Background Art
Treatment of crude oil for refinery (in particular crude oil which has
complicated rheological structure) is a process that determines profitability of
the whole petrochemical industry.
Upon availability of treatment (pre-processing of crude oil before
feeding to the reactor for refining) the subsequent processing of oil raw
materials requires much less time, thus increasing the productivity of the
process.
Pre-processing of crude oil is performed with the following purposes:
- desalting and dehydration,
- viscosity reduction of oil and petroleum products (improvement of
rheological properties),
- removing sulfur and sulfur compounds from crude oil.
It was developed some methods of pre-processing of crude oil focused
on partial modifications in the structure of hydrocarbon links in order to, in
addition to the above, as far as possible to increase the yield of light ends on
the earliest stages.
There is a method (RU 2158288, 27.10.2000), under which crude oil
before feeding to the column for refinery is exposed to complex hydro
mechanical and acoustic treatment in the rotary-pulsating acoustic apparatus
in a certain range of velocities in the gap between rotor and stator. As a result
of changes in the disperse oil state, the yield of oil distillate fractions
increases. Disadvantage of the method is a great energy and metal
consumption.
There is a method (US 4323448, 06.04. 1982), under which mechanical
activation of hydrocarbons is carried out by passing them through a
disintegrator with exposure of impacts at a given frequency.
There is a method (RU 2122457, 27.1 1.1998), under which
hydrocarbon compounds in a liquid form are placed in an artificial gravity
field and supply of mechanical energy to the liquid is provided by means of
mechanical elements. Disadvantage of these methods is a great energy and
metal consumption.
There is a method of cavitation effect in the processing of different
liquids, including for intensification of processing of hydrocarbon raw
materials.
Method of patent (KZ 14129,15.03.2004) is characterized by the fact
that, when petroleum passes through cavitator, formation and growth of
cavitation bubbles and their subsequent collapse occur, accompanied by shock
waves disrupting structure of heavy molecules of hydrocarbons, including
paraffin and asphalt-resinous substances.
Gas temperature inside a cavitation bubble at the end of collapse
becomes very high, because the process happens so quickly that it's no time
to establish heat exchange between contents of the bubble and surrounding
liquid. Hot gas contacting heavy molecules, heats them up to the temperature
at which strength of links between atoms decreases and molecules are
disintegrated to more simple compounds. At disintegration of paraffin
molecules more simple hydrocarbons, light fractions, are formed (paraffin
content is reduced due to disintegration of its molecules). Asphalt-resinous
substances content decreases due to their dissolution by the formed light
fractions.
However, using of petroleum raw materials of different chemical and
fractional composition, different viscosity and other physical and chemical
characteristics, for some of them the cavitation mechanism can not be realized
and in this case the mechanical destruction of these raw materials may not be
carried out.
Disclosure of Invention
The announced method involves pretreatment of crude oil and
petroleum products before the main process - rectification with formation of
light fractions and fractionation.
The object of the invention is to develop high-performance, energyefficient
technology for processing of both light and heavy crude oil and
petroleum products, such as high-paraffin crude oil and oils with a high
content of resins and asphaltenes.
The technical result which this invention is aimed at consists in quality
improvement of processed liquid hydrocarbon raw materials and intensity
increase of its treatment while reducing energy costs.
The technical result is achieved by a method for processing of liquid
hydrocarbon raw materials which includes preliminary pretreatment of raw
materials flow and further processing with fractionation, which is different
that the pretreatment is performed by means of forming of the primary flow
with characteristics of a straight tubular laminar flow, whereupon the raw
materials flow is forced into directed progressive rotary motion preserving
laminarity, for this purpose it is directed to a spiral tubing while the primary
flow is forced to move at a velocity the maximal value of which on the
boundary of vortex axile zone satisfies the conditions of achievement by the
Reynolds number of critical values for tubular spiral flow of liquid.
The mentioned velocity can be provided by regulated dynamic pressure
of raw material primary flow.
For large volumes of pretreatment oil more than one primary flow can
be formed.
The directed motion of the flow along vortex trajectory can be provided
by means of pipeline geometry modification.
In the other particular case the directed motion of the flow along vortex
trajectory can be provided by means of tangential input of straightforward
flow into the vortex zone.
The dynamic pressure volume is preserved in its natural fluctuation
limits.
Maintaining accuracy of the dynamic pressure values is provided within
limits of its natural fluctuations.
Previously formed primary flow is evenly divided into parallel streams
through hydro dynamically separated channels.
Additionally it should be noted that the features included in the
dependent claims are used in particular cases.of the method implementation.
The laws of hydrodynamics, in particular, the laws describing regimes
of motion of viscous fluids, which include the flow of hydrocarbons, are laid
in the basis of the method announced.
It is known that motion of a viscous fluid can be performed in two
regimes: laminar, characterized by steady-layered fluid motion with no
mixing of particles and turbulent, in which the fluid particles, in addition to
progressive motion have rotational motion.
Regimes differ by different intensities of heat and mass transfer
processes. It is believed that laminar regime of pipeline operation is the most
profitable in energy terms. Comparison of pressure differentials for turbulent
and laminar flows (performed on the basis of Poiseuille equation for viscous
liquids) shows that increasing fluid pumping velocity through pipes in
turbulent flow requires a much greater increase in pressure differential than in
laminar. Laminar regime is more effectively transfers heat, besides when
turbulent eddy forms the effective hydraulic resistance increases, that is a
reason of pressure loss along the length of pipeline. For these reasons, the
ability of flow to preserve the laminarity (hydrodynamic stability of a laminar
flow regime, resistance to formation of a turbulent flow regime) is an
important operational feature of a system transporting and processing
hydrocarbons flow (system effectiveness measure).
Hydrodynamic flow regime is characterized by the dimensionless
Reynolds number. Variables connected with Reynolds number directly or
indirectly are controlling flow parameters and regime change depends on
these variables.
Re = vLp/n, (1)
where: p-liquid density,
v -flow velocity,
L - characteristic length of flow elements (flow pipe radius),
h- coefficient of molecular viscosity.
Regime of transition from laminar to turbulent flow is characterized by
a critical value of the Reynolds number. This number, at which eddy
formation begins, varies widely subject to not only on the flow velocity,
diameter and fluid viscosity, but also additional conditions contributing
overcoming of potential barrier of cohesive forces between liquid molecules.
At other known parameters in the equation (1), it can be allocated a
transient regime zone, characterized by an interval of flow velocities in the
range of nominal values (upper and lower critical velocities).
Transition from laminar to turbulent flow can be considered as a
process of self-organization, which takes place in accordance with the laws of
phase transition or a sequence of phase transitions in an unstable
heterogeneous system, which can be represented by flow of hydrocarbons (a
complex mixture of hydrocarbons of different structural-group composition
and heteroderivatives with a wide range of physical and chemical properties).
If in the part of hydrocarbon flow it can be achieved a velocity, met the
conditions needed for creation of the energy density per unit volume in
accordance with the formula:
ire
En 2mc2 (l + - ), (2)
where: m - electron mass,
c - velocity of light in vacuum,
M - molecule mass in working fluid (hydrocarbons flow).
phase transition under critical regime, is a transition into the fifth (positron)
medium state, taking place with release of significant energy being domestic
energy resource of the system (A.I. Akhiezer, V.V. Berestetsky "Quantum
electrodynamics", Moscow, Nauka, 1969).
The basis of this statement is comprehension of Dirac positron medium
state, contained in the monograph P.A.M. Dirac, The Principles of Quantum
Mechanics, 1930. The above mentioned impacts on working fluid creates the
conditions for quantum-mechanical resonance with the fifth state of Dirac
medium, actuating in it polarization processes similar to electron-positron
pairs creation. This process is a special case of the first type phase transition
and a subject to all laws natural to it.
On the other hand, it's known that vortex motion is characterized by
full use of the internal energy of a working body and additional dynamic
pressure by means of working medium rotational flow motion in general. In
the vortex (as a dynamic non-linear structure) transfer of energy and
momentum increases drastically, by orders.
Studies of the hydrodynamic model have shown that the beginning of
intensive energy growth in axile zone of the vortex is almost identical with
the boundary of instabilities formation in laminar flow.
Based on the foregoing the applicant has made an assumption
(subsequently confirmed experimentally) that tubular spiral flow of
hydrocarbons can be regarded as vortex-like. Upon condition of preservation
of flow in a state corresponding to the critical flow regime, up to the border of
the vortex axile zone, and prevention of transition of working fluid laminar
flow in tubular flow (in-tube flow) into turbulent flow regime until
achievement of this boundary, it is possible without significant energy
consumption to provide in the axile zone for micro volume of substance
matter constituting the working medium, conditions of phase transition into
the fifth state of medium that is accompanied by significant energy release.
According to experimental studies fact of the mentioned phase transition was
confirmed by accompanying shortwave radiation.
In this context micro volume is a physically small volume in
comparison with liquid volume, but it's a large volume in comparison with
molecular distance.
For preservation of flow dynamical structure stability at its transition
from straightforward to vortex mode, preservation accuracy of flow controlled
parameter has the basic significance due to gentle approach to the phase
transition mentioned above guarantees the system temporal stability. Some
studies devoted to the first type phase transitions show that the transitions are
initiated by spontaneous fluctuations of one of thermodynamic system
parameters, caused by thermal or quantum-mechanical effects. Since flow
velocity supporting by dynamic pressure is the controlled parameter, one can
speak about value fluctuations of the last-mentioned. At that pumping system
creating required pressure should meet rigid requirements on average value
maintenance for the parameter determined fluctuation range. This
maintenance may be performed, including, by means of feedback on the
parameter controlled.
Energy release in hydrocarbon flow is accompanied by processes
analogous to those occurring as a result of cavitation effect, but unlike the
last-mentioned, not depending on chemical and fractional composition,
viscosity and other chemical-physical characteristics of crude oil. Energy
released in the process of phase transition of part of micro objects of working
body into the fifth medium state, causes interatomic links strength decrease,
in consequence of which hydrocarbons heavy molecules structure is
disintegrated, including paraffin and asphalt-resinous substances. As a result
of factors complex interaction, oil quality increases and already at this stage
partial light fractions separation takes place, which is an indication of
processing intensity increasing. Simultaneously flow temperature increase
contributes oil and water density difference increasing and liquid fractionation
process is facilitated. Water is distributed in the flow evenly dissolving salts
contained in it, and it is extracted from heavy residue as a part of steam-andfluid
mixture.
Best Mode for Carrying out the Invention
Example of practical performance of the method announced is
illustrated by Fig. 1, where operational diagram of apparatus for liquid
hydrocarbon raw materials processing is presented, and effectiveness of the
method announced is illustrated by Fig. 2, where data on crude oil and oil
processed one time with use of the method announced are presented.
This apparatus consists of reservoir for hydrocarbon raw materials
pretreatment 1, pump 2 for creation of raw material dynamic pressure in the
chamber, pump 3 for heat-carrying agent supply, evaporator 4 for separation
of light oil fractions, mixer 5, and fractionation reactor 6. Moreover the
apparatus has different equipment for raw material storage and collection of
the products produced (not shown).
Reservoir for pretreatment 1 has a system of hydrodynamically
separated channels (tubular units, pipe-lines) in which any flow regime can be
maintained. Each tubular unit has straightforward initial part, as far as
possible smoothly conjunct with raw material storage wall. It was made with
purposes of maximal decrease in hydraulic resistance occurring due to
difference in tube and storage sizes and prevention of eddy (turbulence) in
this zone.
The straightforward part of pipe-line smoothly transforms into spiralshaped.
This part shape can be determined, in particular, by a threedimensional
curve which projection on the plane orthogonal of vertical axe,
is, for example, Archimedean spiral, logarithmic or hyperbolic spirals.
Regulated computational form of vortex flow guarantees achievement of
significant flow rotation velocity in axile zone wherein formula (2) is true.
Pipe smooth curve is considered the most suitable from the point of
view of pressure losses due to absence of dangerous zones of turbulence.
However maximal radius of the pipe curve is to be selected on the basis of the
condition of achievement of flow velocity critical value on the axile zone
boundary, wherein hydrodynamic stability of entering this part flow against
possible vortex laminarity violations can be achieved. At that circumferential
velocity values regular distribution depending on distance from rotative axis
shall be taken into consideration.
Complex of the conditions developed for the process stability
supporting being performed for one separate channel (or pipe-line)
automatically performs for the whole channel system (or pipe-lines).
Other elements of the apparatus are no different from the known on the
technical level.
This method is performed in the following manner.
Hydrocarbon raw materials (oil) are fed into the tank for pretreatment 1
from the storage through pump 2. Pump 2 produces hydrodynamic pressure
for providing of flow velocity interval needed for primary flow laminarity
supporting. At determining of the velocity interval mentioned above
according to formula (1) raw feedstock viscosity and pipe-line geometric
configuration parameters are to be taken into consideration. Further the
primary flow curls along spiral trajectory with preservation of computational
laminarity, which is maintained by regular hydrodynamic pressure of raw
materials in intake branch pipe, allowing on the one side to use rotative
motion source power in full for vortex flow producing, on the other side, to
maintain permanent flow characteristics up to axile vortex zone boundary (as
a rule it forms up to half of vortex flow radius). Velocity distribution in the
vortex has axisymmetric characteristics with velocity increase up to the
maximum value and pressure decreasing down to the minimum in the vortex
axile zone, at that from the moment of the vortex formation the law of
conservation of momentum starts operating. Features of the vortex, as a
dynamic self-organizing structure are such that velocities in the axile zone
reaches critical values and there are conditions for necessary phase transition
of working fluid microvolume with release of significant energy, contributing
intensification of further separation process of hydrocarbons into fractions. In
the evaporator 4, where hydrocarbons flow enters from the draining zone of
reservoir 1, a partial separation of light hydrocarbons in the form of a gasvapor
mixture from dehydrated heavy component takes place. Further, heavy
hydrocarbons, mixed in a mixer 5 with coolant supplied by pump 3, enter the
reactor 6 for further refining.
Figure 2 presents comparative results for separation of light and heavy
crude oil residue and oil, refined by the announced method, in percentage of
light hydrocarbon fractions to the whole mass. High viscosity materials with
high content of resins and asphaltenes were processed.
Refined oil quality evaluation made according to integrated indicator of
pipeline oil quality (K), calculated on the basis of the above data by the
method described in the study of Degtiarev V.N. «Oil Quality Bank», Oil
Industry, 1997, N 3 , p.62-63 [3], shows oil quality increase in several times.
Integrated indicator of refined oil quality was Nref = 0.455 for initial oil
indicator of Ki = 2.92. Downward bias of unit deviation of the Quality
integrated indicator leads to falling costs of processing.
Industrial Applicability
The announced method can be used to process both light and heavy
crude oil and petroleum products, and allows by means of pretreatment of
hydrocarbon flow to improve substantially the quality of the finished product,
as well as intensity and energy efficiency of the rectification process.
Claims
1. Method for processing of liquid hydrocarbon raw materials which
includes preliminary pretreatment of raw materials flow and further
processing with fractionation, which is different that the pretreatment is
performed by means of forming of the primary flow with characteristics of a
straight tubular laminar flow, whereupon the raw materials flow is forced into
directed progressive rotary motion preserving laminarity, for this purpose it is
directed to a spiral tubing while the primary flow is forced to move at a
velocity the maximal value of which on the boundary of vortex axile zone
satisfies the conditions of achievement by the Reynolds number of critical
values for tubular spiral flow of liquid.
2. Method according to claim 1, in which the mentioned velocity is
provided by regulated dynamic pressure of raw material primary flow.
3. Method according to claim 1, in which more than one primary flow
is formed.
4. Method according to claim 2, in which the dynamic pressure volume
is preserved in its natural fluctuation limits.