Agitating – Having interrelated feed and discharge means – Recirculating from and to mixing chamber
Reexamination Certificate
1998-12-07
2001-04-17
Cooley, Charles E. (Department: 1723)
Agitating
Having interrelated feed and discharge means
Recirculating from and to mixing chamber
C366S165500, C366S173200, C134S16800C, C134S16900A
Reexamination Certificate
active
06217207
ABSTRACT:
FIELD OF THE INVENTION
This invention concerns a method and device for recovering crude oil bound in thickened crude oil or its sludgy to compact sediments in vessels in which crude oil is stored and/or transported.
BACKGROUND OF THE INVENTION
Crude oil hauled from the ground in crude oil production is first stored without further treatment in storage vessels, i.e., in crude oil tanks of large volume and is held ready for distribution. The storage times of the oil in this kind of vessel is frequently sufficiently long for considerable sedimentation to occur, especially under extreme climatic conditions. The sedimentation speed and the composition of the sediments usually differ according to the origin of the oil. If such vessels are emptied and refilled several times without removing the sediments, a layer of sediments of a thickness of 1.5 m or more can be formed. The quantity of crude oil contained in this kind of sediment layer is considerable because this layer consists to a large extent of thickened oil and higher molecular substances such as, e.g., asphalt, paraffins or waxes. The sediments can, however, also be formed from lighter components of crude oil by means of thickening under the influence of heat. The sediments often have a jelly-like consistency and are nothing else than a heavy fraction of crude oil, the components of which are very mixable with crude oil or lighter components of crude oil or are soluble in these. The sediments, however, also contain foreign matter in form of, e.g., stones or pieces of metal, mostly rust.
For a long time, the sediments in crude oil containers as described above have been unwanted material which still today are removed in periodic cleaning processes from the vessels with suitable cleaning media, mostly aqueous solutions of detergents, is deposed of in more or less sensible manner or is destroyed. In the patent publication EP-160805, a method has been described with which this kind of sediment in crude oil containers or similar storage or transport vessels can be brought into a recyclable form. For this purpose, crude oil is injected into the sediment by means of rotating heads with nozzles which heads are introduced into the sediment. Thus, over a large area the sediment is swirled around and distributed in the liquid, is made to move, and is dissolved at least partly. It proves to be advantageous to match the activities of the individual nozzle heads to each other, such that due to opposite rotation, the vortices created by each nozzle head create currents.
From the named publication (EP-160805) it can be seen that the described method is rather complicated. The reason for this is the necessary use of rotating lances with which a region as large as possible is treated with injected oil and with which the vortices are to be achieved. Regarding the use of energy and in particular regarding the device and the method for assembling it, the whole thing is relatively costly. Means, i.e., drives, for rotating the lances are required. The diluting media, the fresh crude oil must be introduced through these same lances. For the desired forming of eddies, controlling means are required to control the direction of rotation of the lances. Furthermore, this type of rotating lance is complicated mechanically and thus subject to disturbances. If the combined rotation fails the forming of eddies also fails, which, however, is relatively insignificant due to the two-dimensional effect of the rotating nozzles. However, the required simultaneous triple function, i.e., rotating the heads with, e.g., pneumatic means, pumping and injecting the crude oil and controlling the nozzle heads is costly and rather disadvantageous concerning the process. In addition, the construction of rotating lances requires a relatively high precision because roller bearings and other elements requiring narrow tolerances, e.g., for fit are included in the device. This makes designing and manufacturing such devices relatively expensive.
SUMMARY OF THE INVENTION
The inventive method substantially consists in bringing a plurality of liquid jets having a fixed spatial direction into and directly above the sediment by means of hydrodynamic energy such that the introduced liquid forms a substantially horizontal current. The object is to create with the totality of all the liquid jets a concerted current or concerted currents, respectively. The plurality of specifically arranged and directed lances having defined nozzle orientation effect in a vessel with a circular plan e.g. a current which is closed in itself and which behaves as if driven by a gigantic stirrer. Hereby, the upper border of the flowing liquid is to remain as little disturbed as possible and its lower border, i.e., the border between flowing liquid and sediment, is to be formed such that an amplified erosive effect is achieved by the current. In order to keep the energy required for the process as low as possible it is also an object of the method only to create directed mass currents where they are necessary for dissolution of the sediment. An attempt is made to substantially only form a current within a predetermined layer, i.e., in the region just above the sediment layer. It is not necessary to move the liquid above this region. However, due to the inner friction in the liquid this cannot be prevented totally but the additionally required energy is kept low.
Thus, the inventive method consumes less process energy than known methods and is simpler to carry out. The device to be created for carrying out the inventive method is much simpler and is easier to operate than the corresponding device for the known method and it is in particular more easily adapted to and mounted in the vessels to be treated. The required means are very simple, are cheaply fabricated, easily mounted, robust, little susceptible and practically maintenance-free lances.
The liquid introduced directly above the sediment differs from the crude oil above the sediment at least in that its concentration of substances from the sedimentation is lower. This liquid, in the case of a crude-oil tank, is, e.g., crude oil from the upper region of the vessel or a less concentrated portion of the same crude oil, i.e., a portion of crude oil from which the heavy components have been removed. In any case, the main components of the liquid are the same as the main components of the liquid to be stored and/or transported in the vessel to be treated. Therefore, the liquid, after taking up the sediments can be mixed into the stored liquid without scruples and/or can be fed into the same further processing.
The inventive method makes use of the finding that by suitable supply of current energy (hydrodynamic energy) it is possible to produce a current in a region or a layer of a resting liquid, whereby a kind of shear planes are formed between the flowing layer and the resting layer above or below the flowing layer or between the flowing layer and layers above and below which flow at different speeds. In order to form this kind of flowing layer the liquid to be introduced is injected into the resting liquid in a direction substantially tangential to the flow axis and at a predetermined speed. For this purpose, the pressurized liquid is pressed through stationary injection nozzles which are correspondingly orientated in a fixed direction.
It is advantageous if, at least in the region of the upper shear plane, mixing is impeded as far as possible; this for the following reason: in vessels in which crude oil or liquids of similar character are stored in a stationary condition for a sufficiently long time not only sediments form but probably also a composition gradient across the whole height of the liquid column such that the concentration of the substances most concentrated in the sediment increases from top to bottom. The lowermost layers of liquid thus contain a considerable concentration of the substances contained in the sediment and therefore, are hardly suited for an efficient re-liquefaction of the described sediments. With the inventive method it beco
Frei Alexandra Sarah
Streich Bruno
Cooley Charles E.
Farley Walter C.
Lindenport S.A.
LandOfFree
Current creating device and method for liquefaction of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Current creating device and method for liquefaction of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Current creating device and method for liquefaction of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2443510