The present disclosure relates to apparatuses, systems and methods used in crude oil desalting processes. More particularly, the present disclosure relates to systems and methods used to inject dilution water into a crude oil stream in order to contact and coalesce entrained water within the stream.
The crude oil desalting process involves washing a crude oil stream with water having a low salt content (e.g. typically about 250 ppm or less) followed by electrostatic dehydration of the resulting mixture. The washing step involves mixing the low salt-content (“fresh” or “dilution”) water with the crude oil stream so as to add energy into the stream and coalesce the dilution water with the brine water already entrained in the crude oil stream.
Mixing is accomplished through a mixing valve, static mixer, or some combination of the two. The degree of emulsification of the dilution water primarily depends on the pressure drop imparted by the valve. A normal design range for this pressure drop is in a range of 5 to 25 psi, with most valves or mixers operating below 15 psi. If too large of a pressure drop is created, the water droplets decrease to a size which makes them difficult to coalesce and remove in the downstream electrostatic dehydration process. A pressure drop control system, like that shown in
Prior to the crude oil stream entering the mixing valve, it is advantageous to disperse the dilution water in the oil phase. This is typically done by way of a disperser which uses medium pressure spraying of the dilution water through holes on the dispersing tube of the disperser at a rate of 3-10% of oil flow rate. The spraying occurs in a direction perpendicular to the flow of the crude oil stream (see
One problem with the prior art dispersion system and method is, the dilution water droplets being sprayed or dispersed into the crude oil stream are greater than 1000 microns in size. In the disclosure described below, spray nozzles atomize wash water into the crude oil stream. The atomized water droplets are in a size range of 10 to 300 microns. This smaller wash water droplet size works to increase the contact efficiency with the brine droplets contained in the crude oil stream, thereby increasing desalting performance.
In general, disclosed herein are systems, methods, and apparatuses for desalting a crude oil stream includes an elongated, vertically oriented vessel that has an interior, piping structure arranged concentric to the vessel. The piping structure—which can be ring-shaped, cross-bar shaped, or any other shape preferable—has a plurality of spray nozzles oriented at a downward angle and receives wash water from a wash water inlet of the vessel. The piping structure may include more than one level of piping, and each level of piping may be fed by its own wash water inlet.
The spray nozzles may be located on different sides of the piping structure and, when more than one level is used, each level may have a different number of spray nozzles than the other levels. The spacing of the spray nozzles does not have to be even within or between levels and, if located on different sides of the piping structure, the nozzles do not have to be placed opposite one another.
The pressure drop through each spray nozzle is preferably no greater than 300 psi and the nozzles preferably deliver a dilution water droplet preferably no larger than 300 microns in diameter.
This disclosure is to improve desalting performance by increasing the contact efficiency of the wash water with the brine droplets contained in the crude oil stream. Contact efficiency can be further increased by placing a mixing valve, static mixer, or some combination of the two downstream of the vessel.
So that the manner in which the above recited features can be understood in detail, a more particular description may be had by reference to embodiments, some of which are illustrated in the appended drawings, wherein like reference numerals denote like elements. It is to be noted, however, that the appended drawings, illustrate various embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments.
In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. However, it will be understood by those of ordinary skill in the art that the system and/or methodology may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
In the specification and appended claims: the terms “connect”, “connection”, “connected”, “in connection with”, and “connecting” are used to mean “in direct connection with” or “in connection with via one or more elements”, and the term ‘set” is used to mean “one element” or “more than one element”. Further, the terms “couple”, “coupling”, “coupled”, “coupled together”, and “coupled with” are used to mean “directly coupled together” or “coupled together via one or more elements”. As used herein, the terms “up” and “down”, “upper” and lower”, “upwardly” and “downwardly”, “upstream” and “downstream”, “above” and “below”; and other like terms indicating relative positions above or below a given point or element are used in this description to more clearly describe some embodiments of the disclosure.
Although the preceding description has been described herein with reference to particular means, materials and embodiments, it is not intended to be limited to the particulars disclosed herein; rather, it extends to all functionally equivalent structures, methods, and uses, such as are within the scope of the appended claims.
Referring to
The spray nozzle 11 is arranged so that a centerline 13 of a spray pattern 15 of the dilution water droplets being delivered by the spray nozzle 11 is parallel to the longitudinal centerline 17 of the mixing vessel 10 (i.e., in a direction of flow “F” of the crude oil stream flowing through the mixing vessel 10). Therefore, the spray from each nozzle 11 is in a generally downward direction and into the downward flow F of the crude oil stream.
Mixing vessel 10 is a vertically oriented pipe located upstream of a mixing valve (not shown) and electrostatic dehydration process (also not shown). The spray nozzle 11 is plumbed to a horizontally oriented inlet pipe 19 which is in communication with a dilution water source (not shown). The spray nozzles 11 atomize the wash water from the dilution water source into the crude oil.
The spray nozzle 11 can be a first stage (or level) of spraying and at least one other spray nozzle 11 can be arranged downstream from and in an identical manner to the first-mentioned spray nozzle 11. The other spray nozzle 11 is a second stage (or level) of spraying. Multiple stages of spraying within the same mixing vessel 10 can be used as appropriate, as can multiple mixing vessels 10. Each stage within the vessel 10 makes use of the same size of spray nozzle 11 and operates at the same pressures and rates. The number of spray nozzles 11 between inlet pipes 19 may be the same or vary as appropriate.
The pressure drop through each spray nozzle 11 is in a range of 50 psi to 300 psi and in a range of 80 to 120 psi.
The spray nozzles 11 deliver dilution water droplets in the range of 10 to 300 microns in diameter and in the range of 10 to 30 microns in diameter.
The system (
If the spray nozzle 11 is located upstream of a conventional disperser like a mix valve, the contact efficiency increases to 90%. Therefore, the spray nozzle 11 can be used along with a conventional mix valve, static mixer, or both to improve contact efficiency (see e.g.
Referring now to
Each level 55, 57, 59 is connected to three vertical pipes 45, 47, and 49, with one vertical pipe 45, 47 or 49 providing wash water to the level 55, 57, 59 and that level's rings 61, 63. Each ring 61, 63 supports a plurality of spraying heads or manifolds 71, each manifold 71 having a plurality of spray nozzles 21. The first or top level 55 has 45% of the total spray nozzles 21, the second or middle level 57 has 30% of the total nozzles 21, and the third or bottom level 59 has 25% of the total nozzles 21.
Referring now to
Before entering the vessel 10, the wash water stream is divided into three sub-streams 25, 27, and 29 to allow a reasonable system turndown ratio. The sub-streams 25, 27 and 29 provide a wash water sub-stream to a respective vertical piping 45, 47 or 49 connected to the top, middle, or bottom level 55, 57, 59 (and the level's respective rings 61,63) of the nozzle spool 20.
Each inlet stream or piping 25, 27, 29 is equipped with a respective flow meter 85, 87, 89 and an on-off valve 95, 97, 99. The flow meter 85, 87, 89 monitors the sub-stream line 35, 37, 39 for plugged or leaking spray nozzles 21. The on-off valve 95, 97, 99 is used to direct the flow to each ring 61, 63 on the respective level 55, 57, 59 to maintain the pressure drop through the nozzles 21.
Similar to spray nozzle 11, spray nozzles 21 atomize the wash water from the dilution water source into the crude oil stream. The pressure drop through each spray nozzle 21 is in a range of 50 psi to 300 psi, and in a range of 80 to 120 psi. The spray nozzles 21 deliver dilution water droplets in the range of 10 to 300 microns in diameter and in the range of 10 to 30 microns in diameter. The spray from each nozzle 21 is in a general downward direction and into the crude oil flow as it flows in a downward direction through the vessel 10.
A crude oil stream enters the system through a crude oil inlet 81. The crude oil flow rate is monitored by a flow meter 91. The mixing vessel 10 could be bypassed to route the crude oil flow to static mixer 103 and mixing valve 105.
Vessel 10, when in use, represents the washing step located upstream of a separator vessel such as an electrostatic dehydration unit. The vessel 10 may replace the typical washing step described in the Background section or may be used in combination with it (see e.g.,
The system and method described above are not all of the possible embodiments of the disclosure. The scope of the disclosure is defined by the following claims, including elements or steps which are equivalent to those recited.
The present application is a continuation application which claims priority to U.S. patent application Ser. No. 14/256,647, now U.S. Pat. No. 9,505,990, filed on Apr. 18, 2014, each of which is incorporated herein by reference.
Number | Name | Date | Kind |
---|---|---|---|
1838029 | Isles | Dec 1931 | A |
20080192566 | Yamashita | Aug 2008 | A1 |
Number | Date | Country |
---|---|---|
1586620 | Oct 2005 | EP |
2286694 | Apr 1976 | FR |
Number | Date | Country | |
---|---|---|---|
20170073590 A1 | Mar 2017 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 14256647 | Apr 2014 | US |
Child | 15362263 | US |