Processing of oil by steam addition
Salt is removed from crude oil by exposing the salt bearing crude to successive stages of water injection and steam injection where the water injection includes high shear and the stream injection does not include high shear applied to the steam bubbles. The steam is seen to transfer salt from the crude via a different transfer mechanism and therefore doesn't require the high shear mixing of conventional water injection systems.
1. A process for removing salt from crude oil wherein the salt may be in the form of particles of crystalline salt suspended in the crude oil or as small droplets of brine water suspended in the crude oil, or both, wherein the process comprises the steps of:
a) injecting steam into the crude oil in the form of steam bubbles that are larger relative to any salt particles or relative to the any droplets of brine water so as to create steam bubbles that will have broad contact with the crude oil along with any nearby suspended salt particles and brine droplets, such that a single steam bubble may actually contact a plurality of many salt particles and brine droplets;
b) condensing the steam bubbles into droplets of liquid water while at the same time dissolving available salt particles forming new brine water droplets and also delivering liquid or vaporous water from the steam bubbles into any available small brine droplets resulting in coalesced brine droplets having a size more amenable for separation from the crude oil;
c) separating liquid water from the crude oil including water with dissolved salt therein to thereby remove the salt and water from the crude oil and thereby form a first pass desalted crude oil, wherein the process is more particularly characterized in that it does not impose high shear mixing on steam bubbles or resulting condensed water prior to this step (c);
d) injecting liquid water into the first pass desalted crude oil forming droplets having a first average size;
e) imposing aggressive high shear mixing on the injected water and first pass desalted crude oil to break up the injected water into droplets of water having a second average size that is smaller than the first average size and, at the same time, enhance contact of the smaller droplets of water with remaining salt particles and remaining brine droplets to enhance dissolving of salt particles and also coalesce droplets of water whether brine droplets or droplets of injected water;
f) separating liquid water from the first pass desalted crude oil with any dissolved salt therein to thereby remove salt and water from the first pass desalted crude.
2. The process for removing salt from crude oil according to claim 1 wherein the steps for separating the liquid water from the crude oil includes subjecting the crude oil to low shear coalescer mixing followed by gravity separation of the water droplets from the crude oil.
3. The process for removing salt from crude oil according to claim 2 further including the step of adding demulsifier into the crude oil prior to the first step of separating the liquid water from the crude oil.
4. The process for removing salt from crude oil according to claim 3 wherein the step of injecting steam further includes injecting the steam into a vertically oriented chamber where the crude oil and steam flow vertically as the steam bubbles condense.
5. The process for removing salt from crude oil according to claim 4 wherein the vertical flow in the chamber is downward.
6. The process for removing salt from crude oil according to claim 4 wherein the vertical flow in the chamber is upward.
7. The process for removing salt from crude oil according to claim 2 wherein the step of injecting steam further includes injecting the steam into a vertically oriented chamber where the crude oil and steam flow vertically as the steam bubbles condense.
8. The process for removing salt from crude oil according to claim 7 wherein the vertical flow in the chamber is downward.
9. The process for removing salt from crude oil according to claim 7 wherein the vertical flow in the chamber is upward.
10. The process for removing salt from crude oil according to claim 1 wherein the step of injecting steam further includes injecting the steam into a vertically oriented chamber where the crude oil and steam flow vertically as the steam bubbles condense.
11. The process for removing salt from crude oil according to claim 10 wherein the vertical flow in the chamber is downward.
12. The process for removing salt from crude oil according to claim 10 wherein the vertical flow in the chamber is upward.
13. The process for removing salt from crude oil according to claim 1 further including the step of adding demulsifier into the crude oil prior to the first step of separating the liquid water from the crude oil.