This application claims the benefit of priority of U.S. patent application Ser. No. 13/869,017, filed on Apr. 23, 2013, the contents of which are incorporated herein by reference.
The present disclosure relates generally to apparatuses and methods for treatment of fluids. More particularly, the disclosure relates to fluid hammers, hydrodynamic sirens, and stream reactors, implementations of fluid hammers, hydrodynamic sirens, and stream reactors, and methods for treatment of fluids.
Heavy oil in general contains a mixture of hydrocarbons that contain both paraffinic C—C bonds, unsaturated C═C and CC bonds, aromatic rings, C—N, C—S, C—O, C—H and other bonds, each with its own disassociation energy.
Hydrocarbon cracking occurs when the hydrocarbon molecules collide with energies greater than the bond disassociation energy. For example, C—C bond disassociation energy is ˜3.6 eV or ˜350 kJ/mol.
The cracking reaction rate is determined by the Arrhenius equation:
f=zExp[−Ea/RT], (1)
where f is the reaction rate, z is the pre-exponential factor (usually experimentally determined), Ea is the reaction activation energy (experimentally determined), R is the universal gas constant, and T is the temperature.
The Arrhenius equation in turn is based on Maxwell-Boltzmann distribution F(E) of molecular energies E in any ensemble in equilibrium characterized by a temperature T:
F(E)=2(E/π)1/2(1/kT)3/2Exp[−E/kT], (2)
where k is the Boltzmann's constant.
From the Maxwell-Boltzmann distribution (2) it is evident that at any temperature (no matter how high or low), there will be molecules with energies E>Ea, which are high enough to break bonds when the molecules collide. Because the Arrhenius equation is derived by integrating the Maxwell-Boltzmann equation it gives the reaction rate f exponential dependence on both the reaction activation energy Ea (which is derived from the bond disassociation energy) and temperature T.
So, according to the Arrhenius equation (1) the disassociation and cracking reactions will take place even at room temperature although the rate of reaction will be vanishingly small. The rate of reaction becomes significant, however, when the average molecular energy E approaches and exceeds the reaction activation energy, Ē≳Ea. Due to exponential nature of the Arrhenius equation (1) for almost all chemical processes the reaction rate f doubles (triples, quadruples, etc.) for every 10° C. increase in temperature.
Therefore the most natural way to accomplish hydrocarbon cracking amounts to raising the temperature above some critical point (˜400° C. for most heavy oils) corresponding to the cracking reaction activation energy Ea for that particular oil (the cracking reaction activation energy depends strongly on the hydrocarbon molar mass: it is higher for light hydrocarbons and lower for heavy hydrocarbons).
Consequently, all industrial methods for hydrocarbon cracking (such as thermal cracking) rely on high temperature (400-900° C.), which is usually accompanied by elevated pressure (80-1,000 psi). Presence of catalyst such as silica, alumina, or zeolite leads to catalytic cracking and accelerates the reaction while somewhat reducing the temperature and pressure requirements to ˜500° C. and <100 psi accordingly.
As a result, the conventional thermal and catalytic cracking processes are able to convert 90-95% of heavy less valuable hydrocarbons into lighter more valuable ones while generating coke (C), hydrogen (H2), hydrogen sulfide (H2S), and other incondensable gases (C1-C5) as byproducts.
Unfortunately, coke fowls the process equipment by forming harmful deposits that inhibit heat exchange and clog orifices and pores. Coke also fowls catalyst by coating the catalysts' surface and rendering it inert.
Thus, the fowling due to coke and the requirements for high temperature and pressure increase capital (CapEx), energy and maintenance costs (OpEx) associated with the conventional hydrocarbon cracking technologies. At the moment of writing typical commercial hydrocarbon cracking facilities cost hundreds of millions or even billions of dollars and consume approximately 1 MJ of energy per barrel.
Also, the emission of harmful gases—the byproducts of the conventional hydrocarbon cracking technology—further complicates the deployment of these systems due to their large environmental impact (permits may take years to obtain due to mandatory environmental impact studies, public protests, and other issues associated with the environmental protection).
Fortunately, the high-CapEx/OpEx of the conventional hydrocarbon cracking technology and its significant environmental impact can be reduced by implementing the novel hydrocarbon cracking technologies disclosed herein.
It may be desirable to provide apparatuses that, rather than rely solely on temperature and random collision of molecules moving in chaotically in three-dimensional space (3 degrees of freedom), create conditions for organized streaming motion of molecules in one direction (i.e., 1 degree of freedom) and set them onto a collision course.
In some aspects, it may be desirable to provide fluid hammer designs that generate periodic high-pressure pulses that are extremely beneficial for industrial applications such as chemical reaction acceleration, hydrocarbon cracking, crude oil upgrading, waste water treatment, cavitation, and others.
In some aspects, it may be desirable to provide apparatus for fluid treatment with reduced leakage currents and fast valve operation. These designs and optimizations stem from the water hammer theory and to the best knowledge of the author has never been emphasized or implemented in water hammer or hydrodynamic siren designs disclosed in the prior art, including numerous patent applications [U.S. Pat. No. 6,016,798A, EP19940914252, U.S. Pat. No. 2,009,006,5724 A1] and publications [U.S. 20,100,101,978 A1]. This may be accomplished with designs emphasizing tight clearances to reduce the leakage flow and special flow channel configurations resulting in fast valve operation.
Reference will now be made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. Generally, corresponding or similar reference numbers will be used, when possible, throughout the drawings to refer to the same or corresponding parts.
In the collision zone 208 the hydrocarbons will undergo an accelerated cracking reaction if the sum of kinetic and thermal energies K(V) and E(T) of the colliding molecules is greater than the activation energy Ea of the reaction in question:
K(V)+E(T)≳Ea. (3)
For the sake of consistency all energies are energies per mole K(V), E(T) and Ea are energies per mole.
Applying this simplistic model to the configuration with two colliding jets shooting at each other with velocity V we can compute K(V) as:
K(V)=M1V2/2+M2V2/2 (4)
where M1 and M2 are the molar masses of the colliding molecules.
Assuming that M1 and M2 are the same we can derive the required jet velocity from the equations (3) and (4) as:
V=[(Ea−E(T))/M]1/2 (5)
At low temperatures we can neglect the thermal energy contribution (E(T)<<Ea). Thus, for C80 paraffin (Ea=200 kJ/Mol, M≈1 kg/Mol) at room temperature we obtain the equivalent stream velocity V≈450 m/s.
Clearly the increase in the jet velocity V increases the reaction rate and makes the cracking reactions possible even at relatively low temperatures. The reaction temperature reduction has an immense practical importance as it leads to the reduction in formation of coke and incondensable gases (coke and gas production grows exponentially with temperature). In fact the tests conducted by our company at temperatures of 200-300° C. revealed no measurable quantities of coke, asphaltenes, or incondensable gases.
Note that the activation energy Ea in the equation (3) is dependent on the reaction of interest, i.e. C—C bond disassociation energy is different and much lower than C═C bond or aromatic ring disassociation energy.
Also, removing cracking products and light hydrocarbons is necessary because light molecules are typically a lot more numerous than the heavy ones and they will effectively shroud the heavy molecules thus absorbing and dissipating the collision energy and preventing the cracking. Therefore, the input stream to the reactor 200 has to contain predominantly heavy hydrocarbons. Otherwise the cracking may be ineffective or be quenched completely.
For viscosity reduction applications, however, it is beneficial to keep the cracking products dissolved in the feed as shown on
In another embodiment of the reactor shown on
In yet another embodiment of the reactor the colliding jets can be enriched with micron-sized hydrogen (H2) or hydrogen donor gas microbubbles that promote cavitation and hydrogenation for saturation of the unsaturated olefinic bonds formed as a result of the C—C bond disassociation.
High-level diagram of the simplest jet reactor application process is shown on
Both configurations shown on
It is important to note that the disclosed jet reactor can be used to accelerate arbitrary endothermic/exothermic reactions of both synthesis and lysis type as long as the conditions defined by the equation (3) are met. The example of hydrocarbon cracking was chosen solely for illustrative purposes.
Last but not least, the jet reactor can take various shapes. For example, the feedstock can be either gas or liquid. The gas or liquid medium can be accelerated in channels of a hammer device (discussed in more detail below). The medium is accelerated to high flow velocity when the rotary gate of the hammer (or the rotor of the siren) admits flow; then the high-velocity flow is abruptly stopped as the flow collides with the rotary gate of the hammer (or the rotor/stator blank of the siren) as the hammer/siren modulates the flow. Assuming that the flow velocity and the medium temperature satisfy the equation (3) chemical reactions will be accelerated.
Another embodiment of the jet reactor is possible in a fluid flow device engineered to create vortices with maximum rotational velocities satisfying the equation (3). The vortices in general and Rankine vortices in particular can be created by any combination of toothed or pegged rotors designed to create turbulence in fluid (i.e. rotors where the rectangular rotor teeth or round rotor pegs protrude perpendicular to the rotor plane and substantially parallel to the rotor axis of rotation).
Cavitation could be yet another embodiment of the disclosed principle: when cavitation bubbles collapse the bubble walls are accelerated inwards until the collapse is arrested by the compressed gas within the bubble. Chemical reaction acceleration according to the disclosed principle will occur when the maximum bubble wall velocity satisfies the equation (3).
Regardless of the specific implementation of the disclosed invention—be that the colliding jet, the hammer, the siren, the vortex, or the cavitation reactor—the main advantage of the disclosed invention is the reaction acceleration by virtue of high-velocity motion along a single degree of freedom. When this organized motion leads to collision it creates transient high-temperature/high-pressure conditions in the collision zone where the jets or the streams of medium collide with each other or with solid, liquid or gaseous interfaces. Given sufficient stream velocity V as determined by the equation (3) the reactor can operate at less challenging temperatures and pressures thus removing the need for significant CapEx/OpEx associated with current industrial reactors that must operate under high temperature and pressure conditions.
According to various aspects of the disclosure, a fluid hammer can be used to treat various fluids. A fluid hammer is a large rapid pressure pulse that is observed in a pipe when the flow is abruptly stopped, e.g. by closing of valve. The hammer effect can occur in any liquid or gas passing through an enclosed flow channel when the flow is suddenly arrested.
For industrial applications a reactor with one or more modulated (i.e. periodically opened and closed) flow channels can produce the hammer effect generating high periodic pressure pulses.
Regardless of specific configuration any hammer system is conceptually equivalent to a modulated valve. A valve with more than one channel and rotary gate is typically referred to as siren.
The desired function of a hammer device is to generate a large sharp pressure pulse (Pm). In an ideal hammer (when the flow is completely stopped and there is no leakage) the magnitude of the pressure pulse Pm is proportional to the density of the fluid (ρ) and the speed of the flow (v):
P
m
˜ρv. (6)
In a perfectly rigid hammer system the magnitude of the pressure pulse depends on how quickly the flow is arrested. Therefore there are two limiting cases: fast valve and slow valve approximations.
When the flow stoppage time (τ is much smaller than the time it takes for sound to traverse the length of the flow channel (L):
τ<<L/c. (7)
The pressure pulse magnitude is proportional to the speed of sound in the fluid (c):
P
m
≈ρv c. (8)
When the flow is arrested slowly (τ≳L/c) the magnitude of the pressure pulse is proportional to the length of the pipe (L) and inversely proportional to the flow stoppage time:
P
m
≈ρv L/T. (9)
In reality the leakage flow and the lack of system rigidity (i.e. the flow channel or the valve gate deformations) reduce the amplitude of the pressure pulse. In practice the leakage flow is often overlooked, as no periodic valve system is perfectly tight.
The cross-sections of a fast valve hammer system designed according to the principles disclosed in this patent are shown on
Fluid or gas flow enters the input channel 304 of length L made in the casing 301 of the hammer system. The rotary gate 302 turns and modulates (opens and closes) the flow periodically. When the rotary gate 302 is open, the flow goes from the input channel 304 through the gate channel 306 and into the output channel 305. The rotary gate 302 is outfitted with magnets 303, is supported by bearings 307, and rotates either clockwise or counterclockwise depending on the direction of rotation of the magnetic coupling 308 that is driven via shaft 309 by an external motor (not shown). Alternatively, the rotary gate 302 can be coupled to an external motor via a mechanical seal.
To maximize the pressure pulse Pm by reducing the leakage flow the clearance between the rotary gate 302 and the casing 301 must be minimized. Ideally low friction materials (such as brass for the rotary gate and stainless steel for the casing or carbides for both) should be used in order to achieve clearances on the order of few thousands of an inch or less.
To maximize the pressure pulse Pm by ensuring the fast valve operation the width WG of the gate channel 306 must be smaller than the width WI of the input channel 304 (WG<<WI) and relate to the length L of the input channel 304, to the rotary gate diameter RG and the rotary gate rotation frequency F as:
W
G<2πRGF L/c (10)
For example, for RG=5 cm, F=100 Hz, L=10 cm, and c=1500 m/s using (10) we obtain WG<2 mm.
Alternatively, the width WG of the gate channel 306 can be much larger than the width WI of the input channel 304 (WG>>WI); then the relationship (10) must hold true for WI instead of WG.
The tapering conical shape of the input channel 304 on
A noteworthy modification to the hammer system is shown on
Another variation of the hammer system is shown on
A different variant of the same hammer system is shown on
The high-level process diagram of the hammer system application is shown on
Yet another modification of the siren is shown on
Note that the siren shown on
In accordance with the disclosure,
Wastewater typically contains suspended solids, suspended (emulsified) immiscible liquids (like oils), and dissolved solids (like salt, phenols, and other contaminants or toxins). Suspended solids and liquids can be separate naturally by gravity over a period of time in a settlement tank or pond as shown on
The natural settlement approach is widely used by the industry in municipal water treatment plants and in tailing ponds for oil sands production. While this approach requires no energy the necessity to maintain large toxic pools (which in the case of oil sands production can cover immense areas) creates significant environmental concerns due to potential leaks into aquifer.
When rapid settlement of wastewater is necessary artificial gravity via centrifuge can be used. Depending on size of the centrifuge and the rate of rotation a compromise can be achieved between the energy usage, the equipment cost, and the speed of separation. For example, desktop centrifuges rotating at many thousands RPMs can separate blood into plasma and cells by gravity although the initial mixture is highly homogenous and would never separate under ordinary gravity conditions.
For the industrial waste processing the efficiency of large centrifuges is limited by their size: it is exceedingly difficult to create large centrifuges capable of fast rotation and rapid separation of highly homogeneous wastewater and achieve the same degree of performance as high-speed desktop centrifuges. Large industrial centrifuges simply cannot match the performance of desktop devices and thus fail to separate highly homogeneous waste and stable emulsions.
Fortunately, there is another way to create powerful artificial gravity caused by inertial forces: one can accelerate flow of wastewater to high velocity and then abruptly arrest the flow causing floating suspended solid and liquid particles to collide and clamp together as they continue their motion driven by powerful inertial forces.
This approach is illustrated on
Clearly, to accomplish the efficient gravity separation the flow of wastewater 101 through the pipe 121 must be sufficiently fast and the valve 122 must open and close rapidly (and remain closed without significant leakage flow) in order to create large inertial forces that clump the suspended solid particles and the suspended immiscible liquid droplets together. Because the closure of the valve 122 will create a water hammer, the fast-flow section of the pipe must be very rigid to prevent expansion and the valve closure time Tc should obey the ‘fast valve’ condition in order to create the strongest possible inertial forces:
T
C
<L/c, (11)
where L is the length of the rapidly moving flow and c is the speed of sound (for a not perfectly rigid pipe c is actually the wave velocity, which is lower than the speed of sound in water due to the pipe expansion).
The period of time ΔTC the valve must remain closed (the valve-closed time) must be smaller than 2 L/c in order to avoid column separation due to water hammer, which will reverse the flow of the wastewater in the pipe and thus interfere with the separation process:
ΔTC<<2L/c (12)
Cavitation is another effect that must be carefully controlled and in all probability avoided during the water treatment process. Because cavitation tends to homogenize and break apart the suspended particles due to reentrant jets that form in the proximity of surfaces when the cavitation bubbles collapse, the valve 122 must be controlled such that the excessive pressure drop downstream of the valve never occurs. This can be accomplished by maintaining positive pressure downstream of the valve 122.
Although cavitation is not desirable when clamping of the suspended particles is desired, it can play a significant role in removing and oxidization of dissolved solids. While we can remove the suspended solids via periodic water hammer events the dissolved solid contaminants can be removed only via chemical reactions that result in sediment or gas production (rarely the toxins can be oxidized forming other non-precipitating dissolved solids that are environmentally friendly).
In this regard supercritical water oxidization (SCWO) process is of special interest. The SCWO process has been commercialized for removing (via oxidization) dissolved toxins that cannot be disposed of otherwise. The SCWO process involves heating water to 400-650° C. under pressure in excess of 217 atmospheres (supercritical water). Under these conditions the water disassociates into radicals that effectively oxidize the dissolved toxins without creating dangerous byproducts associated with flame burning oxidization under atmospheric conditions.
The extremely high temperatures and pressures requires for the SCWO process, however, make it an expensive and energy hungry enterprise. Fortunately, SCWO conditions can be easily achieved in a water hammer device via injection of microscopic (micron-size) oxygen or ozone bubbles—
ΔP=ρc V, (13)
where p is the density of water.
For example, the wastewater stream moving at 100 m/s once brought to an abrupt stop in a fast-valve water hammer will result in a pressure pulse ΔP=1,500 atmospheres. Driven by this strong pressure pulse the suspended oxygen bubbles 130 permeating the wastewater stream 101 will collapse violently resulting in immense temperature rise in the bubble cores 131 creating temperatures in excess of 5,000° C. thus fully ionizing the oxygen, which when in its ionic form is extremely reactive and will oxidize the dissolved toxins it comes in contact with. Thus, by saturating wastewater with vast quantities of microscopic (micron-size) oxygen or ozone bubbles it is possible to create conditions during the water hammer similar to those occurring during the SCWO process and therefore oxidize a great deal of dissolved solids that otherwise cannot be removed.
The general water process according to the hitherto disclosed invention is shown on
For deeper purification a dual-stage water treatment process can be implemented as shown on
We have developed a variety of high-power acoustic and cavitation apparatuses of both hydrodynamic siren and hammer designs (Patent 1) that are referred hereto as ‘sirens’. Such devices can be produced in form factors small enough to fit standard 6″ or 7.5″ well bore casings and thus could be employed to sonicate the entire well or a particular pay zone within the well as shown on
For a siren to function properly, the entire siren 506 or at least the acoustic openings 510 must be submerged in the well fluids.
For better sound focusing or for a select pay zone stimulation packers can be installed within the tubing 502 to focus the sound.
Power to a siren can be supplied either via an electric cord or via a hydraulic line. In the later case the siren's power drive is a hydraulic high-pressure pump that can be located on the surface of the well; crude oil could act as a hydraulic liquid pressurizing the hydraulic line that powers the siren.
Regardless of the power method the siren can be moved up and down the well to deliver maximum acoustic power to a pay zone of interest. For better energy focusing packers can be used to isolate a pay zone.
The key advantage of our sirens is that they allow delivering 10-100 kW of acoustic power with controllable frequency in the range of a few Hz to tens of kHz, compared to 1-2 kW/fixed kHz frequency possible with conventional piezoelectric or magnetostrictive transducers. Because of much greater power our sirens allow for deeper sonication of the producing formation thus allowing for potentially much larger well output increase.
Another advantage of our siren is unprecedented amplitude of dynamic (acoustic) pressure, which is controllable and could be dialed to exceed 30,000 psi. This dramatic acoustic amplitude enables deeper sonication of the formation since larger amplitude sound can penetrate deeper into material until it is completely attenuated.
Typically sonication is applied for short periods of time (tens of hours) to boost well production. While such episodic application boosts well production initially the production falls back to pre-sonication figures in a matter of days. Moreover, conventional sonication techniques require transducer lowering into the well, which is a time consuming and potentially disruptive operation for a production well. Therefore a much more economically viable technique is an inline sonication of a production well—
In the inline configuration the siren is located outside the well and is directly coupled to the pump. The siren can either operate continuously or under manual control when production requirements require it.
The inline sonication is possible due to high acoustic power (10-100 kW) and relatively low controllable frequency (<10 kHz) generated by our siren, which is sufficient to overcome attenuation en route from the well head to pay zone (attenuation is much higher for high-frequency sound waves generated by conventional ultrasonic transducers).
From the foregoing, it will be appreciated that, although specific embodiments have been described herein for purposes of illustration, various modifications or variations may be made without deviating from the spirit or scope of inventive features claimed herein. Other embodiments will be apparent to those skilled in the art from consideration of the specification and figures and practice of the arrangements disclosed herein. It is intended that the specification and disclosed examples be considered as exemplary only, with a true inventive scope and spirit being indicated by the following claims and their equivalents.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/US14/35211 | 4/23/2014 | WO | 00 |
Number | Date | Country | |
---|---|---|---|
Parent | 13869017 | Apr 2013 | US |
Child | 14786867 | US |