Patent Description:
In a crude oil refinery, generally the oil is pumped from a storage tank to a crude unit for processing. The crude unit cleans the oil through water washing in a desalter and then splits the oil into fractions in an atmospheric distillation tower. These fractions are pumped to various processing units downstream of the crude unit (e.g., vacuum distillation, delayed coker, catalytic cracker, hydroprocessing units etc.). Corrosion and corrosion byproduct deposition (the latter sometimes referred to herein as fouling) occur in many areas of a crude unit.

Refinery crude unit processing has become increasingly difficult in recent years and is predicted to become even more challenging and complex for several reasons, For example, significant increases in crude oil prices have caused refiners to aggressively pursue "opportunity" or "challenging" crudes that are obtainable at discounted prices. The lower price is linked to a crude property such as high acid or high solids content that makes it less desirable than the light, sweet benchmark crudes.

Refiners switch crude slates more frequently (every <NUM>-<NUM> days) than in the past due to minimum on-hand crude oil inventory combined with increased crude oil variety. A crude slate switch typically upsets the steady state condition of a crude unit for up to several hours. Generally, about eighty percent of the corrosion and fouling occurs during these switches or disruptions, which normally last about twenty percent of the time. If fouling and corrosion issues are severe enough, the refiner will discontinue processing the crude oil or blend of crudes causing the problem. However, these challenging crudes are available to the refiner at a discount thus making them more profitable. Discontinuing such problematic crudes is accordingly not a very popular option.

In efforts to reduce corrosion, a crude unit may be serviced two or three times per week, or in some cases daily. Daily service at best provides a snap shot view of a dynamic crude unit system. Crude type and/or raw crude storage tanks are switched several times per week, sometimes daily. The contents of each tank are different from the others, so each switch causes a change of feed quality to the crude unit, many times upsetting the steady state status and causing disruptions in the system. Preheating, desalting, and distilling operations shift with the new crude, sending products and/or effluent water sources off specification. Many adjustments over several hours (in some cases days) normally take place to return the crude unit to steady state operation.

The most common current industry practice to control such disruptions and optimize crude unit operation is to provide enough manpower and man-hours. For instance, each crude unit may have an operating crew from three to ten people, depending on size and complexity of the unit. This crew may spend their day gathering various samples for wet chemistry lab testing, and measuring and making adjustments for temperature and flow to keep the unit running within specification. Such practice is typically geared toward keeping the unit operating properly regarding fractionation quality cut points and end points, with minimal attention being paid to a specialty chemical control program. If a disruption is severe, changes may be made to the process chemicals and/or changes in levels, flows, or temperatures may be recommended around the crude unit to keep the dynamic system in as optimum a condition as possible. There thus exists an ongoing need for systems and methods for automated real-time monitoring and controlling of desalting in a crude oil unit.

<CIT> discloses a process and apparatus for desalting crude oil including the mixing of crude oil, water and an additive across a mix valve, and forming an emulsion which is resolved under an electric field.

This invention accordingly provides a system according to claim <NUM>.

It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present invention.

Described herein are systems and methods for automated real-time monitoring and controlling desalting in a crude distillation unit. The systems and methods can be advantageous in reducing unit variability that may lead to desalting upsets that in turn can impact waste water operations, corrosion and fouling of crude unit equipment, and other downstream applications. The system includes a mix valve, a desalter vessel, an emulsion level indicator coupled to an outer surface of the desalter vessel, a chlorine analyzer, a water analyzer, and a controller operatively coupled to the mix valve, emulsion level indicator, and/or chlorine analyzer, and/or water analyzer. In some embodiments, the emulsion level indicator, chlorine analyzer, and water analyzer may be retrofitted to an incumbent mix valve and desalter vessel.

Conventional desalter analyzers or emulsion level indicators utilize probes that are inserted into the desalter vessel through suitable ports. Accordingly, if the ports do not exist in the desalter vessel, the conventional desalter analyzer may not be used. Probes inserted into the desalter vessel may be prone to fouling and erroneous readings due to wax and/or iron sulfide present. Furthermore, probes inserted into the desalter vessel can be damaged through the insertion, retraction, calibration process, and during an inspection or cleaning operation in a shutdown. In contrast, the emulsion level indicator disclosed herein is coupled to an outer surface of the desalter vessel. As such, the desalter system disclosed herein may not require any probes to be inserted into the desalter vessel for measuring at least one property associated with the emulsion. Furthermore, the emulsion level indicator may be installed without the need to shut down the desalter system.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Preferred methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in practice or testing of the present invention. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.

The terms "comprise(s)," "include(s)," "having," "has," "can," "contain(s)," and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that do not preclude the possibility of additional acts or structures. The singular forms "a," "and" and "the" include plural references unless the context clearly dictates otherwise. The present disclosure also contemplates other embodiments "comprising," "consisting of" and "consisting essentially of," the embodiments or elements presented herein, whether explicitly set forth or not.

Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, for the recitation of numeric ranges herein, each intervening number therebetween with the same degree of precision is explicitly contemplated. For example, for the range of <NUM>-<NUM>, the numbers <NUM> and <NUM> are contemplated in addition to <NUM> and <NUM>, and for the range <NUM>-<NUM>, the number <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are explicitly contemplated.

The term "controller" refers to a manual operator or an electronic device having components such as a processor, memory device, digital storage medium, a communication interface including communication circuitry operable to support communications across any number of communication protocols and/or networks, a user interface (e.g., a graphical user interface that may include cathode ray tube, liquid crystal display, plasma display, touch screen, or other monitor), and/or other components. The controller is preferably operable for integration with one or more application-specific integrated circuits, programs, computer-executable instructions or algorithms, one or more hard-wired devices, wireless devices, and/or one or more mechanical devices. Moreover, the controller is operable to integrate the feedback, feed-forward, or predictive loop(s) of the invention. Some or all of the controller system functions may be at a central location, such as a network server, for communication over a local area network, wide area network, wireless network, internet connection, microwave link, infrared link, wired network (e.g., Ethernet) and the like. In addition, other components such as a signal conditioner or system monitor may be included to facilitate signal transmission and signal-processing algorithms.

The present invention is directed to a system for automated real-time monitoring and controlling desalting in a crude oil unit. Referring to <FIG>, the system <NUM> includes a mix valve <NUM>, a desalter vessel <NUM>, an emulsion level indicator <NUM>, a chlorine analyzer <NUM>, a water analyzer <NUM>, and a controller <NUM> operatively coupled to the mix valve <NUM>, emulsion level indicator <NUM>, and/or chlorine analyzer <NUM>, and/or water analyzer <NUM>. The mix valve <NUM> mixes crude oil <NUM> and wash water <NUM> by a pressure drop across the mix valve <NUM>, and thereby forms a crude oil/water phase stream <NUM>. In the illustrated embodiment, the mix valve <NUM> includes an inlet <NUM> for receiving the crude oil <NUM> and wash water <NUM>, and an outlet <NUM> for discharging the crude oil/water phase stream <NUM>. The pressure drop in the illustrated embodiment is determined between the inlet <NUM> and outlet <NUM>. The desalter vessel <NUM> receives the crude oil/water phase stream <NUM>, whereupon an emulsion (not shown) forms at an interface between the crude oil and the water phase. The desalter vessel <NUM> is configured to contact the crude oil/water phase stream <NUM> with a dosage of an emulsion breaker <NUM> in an applied field. In some embodiments, the emulsion level indicator <NUM>, chlorine analyzer <NUM>, and water analyzer <NUM> may be retrofitted to an incumbent mix valve <NUM> and desalter vessel <NUM>. As explained below, the pressure drop across the mix valve <NUM> and the dosage of the emulsion breaker <NUM> are adjusted substantially in real time by the controller <NUM> for automated real-time monitoring and controlling desalting.

The emulsion level indicator <NUM> is coupled to an outer surface <NUM> of the desalter vessel <NUM>. As such, the emulsion level indicator <NUM> may be installed without the need to shut down the system <NUM>. In some embodiments, the emulsion level indicator <NUM> is positioned adjacent to the interface between the crude oil and the water phase. In further embodiments, the emulsion level indicator <NUM> is positioned at a first range of elevations, the interface between the crude oil and the water phase is positioned at a second range of elevations, and the first and second ranges overlap. In some embodiments, the emulsion level indicator <NUM> is attached to existing try-lines (also called "taps" or "trycocks") on the outside of the desalter vessel <NUM>. Typically, five or six try-lines are built in to a desalter vessel to visually see where the emulsion is, how wide it may be, and what it might be composed of. Clamping the emulsion level indicator <NUM> to the try-lines affords an easier installation compared to other commercial alternatives. Moreover, the installation work can be done under a "cold-work permit" because the emulsion level indicator <NUM> does not need to be directly welded to the desalter vessel <NUM>.

The emulsion level indicator <NUM> is capable of measuring at least one property associated with the emulsion, which property is a width of the interface and a rate of change. In some embodiments, the emulsion level indicator <NUM> is capable of measuring a water percentage at, below, and above the crude/oil interface, and then convert this to an actual level (e.g., inches or cm/mm depending on country), all external to the desalter vessel <NUM>. In some embodiments, the emulsion level indicator <NUM> works by measuring the hydrogen content in the hydrocarbon, emulsion, and water phases inside the desalter vessel <NUM>, with detectors and equipment <NUM> physically located outside the vessel. The detectors <NUM> may measure the hydrogen content based on neutron backscatter principles. For example, the detectors <NUM> may use a low level radiation source such as one derived from americium <NUM> (<NUM>Am). An oxide of americium may be pressed with beryllium to make an efficient neutron source for the detectors <NUM>. Although <FIG> illustrates the emulsion level indicator <NUM> as including four detectors <NUM> coupled to the outer surface <NUM> of the desalter vessel <NUM>, it is to be appreciated that other embodiments may utilize other numbers of detectors <NUM>. For example, the emulsion level indicator <NUM> may include one or more, two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, or ten or more detectors <NUM>. Each detector <NUM> may be located at a corresponding level of existing try-lines. As such, checking the accuracy of the output of the detectors <NUM> may be a simple and regular process. Each detector <NUM> may be connected by cabling to a multichannel reader that can route the output through a communication hardware to the data control system (not shown) as explained below. As explained below, the properties of the emulsion measured by the emulsion level indicator <NUM> are used by the controller <NUM> for automated real-time monitoring and controlling desalting.

The chlorine analyzer or salt-in-crude monitor <NUM> is capable of measuring or determining a total chlorine of the crude oil. In some embodiments, the chlorine analyzer <NUM> may measure the total chlorine of the crude oil based upon bombarding or irradiating the crude oil with neutrons. The neutrons are slowed down and thereafter engage in thermal neutron capture reactions with the elements chlorine and sulfur in the crude oil. Gamma ray energy radiation of the crude oil is emitted in response to the capture of thermal neutrons. A measure of the concentration of chlorine and/or sulfur may be obtained based upon the detection of gamma radiation. Though any suitable gamma ray detector may be used, exemplary gamma ray detectors include those disclosed in U. Patent App. Publ'n No. <NUM>/<NUM> titled "Method for Monitoring Fouling in a Cooling Tower. A typical gamma ray detector is a <NUM>-inch sodium iodide scintillation detector, such as the ones manufactured by Ludlum. Although not shown in <FIG>, a radiation counting device receives the signal from the detector. A Model <NUM> Scalar Ratemeter by Ludlum is a typical type of counting device. The detector and counting device measure the intensity of the transmitted gamma radiation. For example, a typical counting device may display the measurement of the radiation intensity as counts of radiation per specified time period (e.g. <NUM>,<NUM> counts/<NUM> seconds).

In some embodiments, the chlorine analyzer <NUM> is capable of measuring a total chlorine of about <NUM>,<NUM> ppm or less. In further embodiments, the chlorine analyzer <NUM> is capable of measuring a total chlorine of about <NUM>,<NUM> ppm or less, <NUM>,<NUM> ppm or less, <NUM>,<NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, about <NUM> ppm or less, or about <NUM> ppm or less. As explained below, the total chlorine of the crude oil measured by the chlorine analyzer <NUM> is used by the controller <NUM> for automated real-time monitoring and controlling desalting.

The water analyzer <NUM> is capable of measuring a water percentage of the crude oil. In some embodiments, the water analyzer <NUM> is capable of measuring the water percentage of about <NUM>% or less. In some embodiments, the water analyzer <NUM> is capable of measuring a water percentage of about <NUM>% or more, <NUM> %, or more, <NUM>% or more, <NUM>% or more, <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, or about <NUM>% or more. In further embodiments, the water analyzer <NUM> is capable of measuring a water percentage of about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, or about <NUM>% or less. This includes water percentages of about <NUM>% to about <NUM>%, <NUM>% to about <NUM>%, or about <NUM>% to about <NUM>%. As explained below, the water percentage of the crude oil measured by the water analyzer <NUM> is used by the controller <NUM> for automated real-time monitoring and controlling desalting.

The controller <NUM> adjusts substantially in real time at least one of the pressure drop across the mix valve <NUM> (e.g., how much the mix valve <NUM> open and closes) and the dosage of the emulsion breaker <NUM> in response to at least one of the measured properties, total chlorine, and water percentage. In some embodiments, the controller <NUM> controls the total chlorine in the crude oil to be less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, or less than about <NUM> ppm. Limiting the total chlorine to less than about <NUM> ppm in the crude oil may protect downstream processes from excess corrosion, and also reduce the amount of sodium (Na) going downstream. Sodium can deactivate catalysts used in fluid catalytic cracking units and other units, and can cause high rates of foiling in furnaces and put finished products (like high grade coke) off-specification. To reduce the amount of sodium going downstream, the controller <NUM> can advantageously control the total chlorine of the crude oil.

In some embodiments, the controller <NUM> adjusts on a substantially continuous basis at least one of the pressure drop and the dosage of the emulsion breaker <NUM> in response to at least one of the measured properties, total chlorine, and water percentage. In other embodiments, however, the pressure drop and the dosage of the emulsion breaker <NUM> are adjusted intermittently or in relation to a schedule as determined for the particular system <NUM>. In some embodiments, the controller <NUM> is capable of generating an alert/alarm when at least one of the measured properties, total chlorine, and water percentage changes by more than a predetermined amount. In further embodiments, the controller <NUM> is capable of generating an alert/alarm when the measured properties, total chlorine, and water percentage changes by more than a predetermined amount in a predetermined amount of time. In response to the measured properties, total chlorine, and water percentage changes, the controller <NUM> can provide an early warning that the system <NUM> is changing so as to preempt potentially deleterious effects of the change.

The wash water <NUM> and emulsion breaker <NUM> may be introduced to the system <NUM> using any suitable type of chemical feed pump. Most commonly, positive displacement injection pumps are used powered either electrically or pneumatically. Continuous flow injection pumps are sometimes used to ensure specialty chemicals are adequately and accurately injected into a rapidly moving process stream. Though any suitable pump or delivery system may be used, exemplary pumps and pumping methods include those disclosed in <CIT> titled "Method for Injection Treatment Chemicals Using a Constant Flow Positive Displacement Pumping Apparatus" and <NUM>,<NUM>,<NUM>, titled "Improved Method for Injecting Treatment Chemicals Using a Constant Flow Positive Displacement Pumping Apparatus," each incorporated herein by reference in its entirety.

The chemical injection pumps can be in fluid communication with one or more storage devices. In one aspect, there could be a conduit running from the chemical injection pump into the storage device. If necessary, the chemical injection pump could then supply a chemical through the conduit and into the storage device. There can also be multiple chemical injection pumps and each pump can have a conduit running therefrom to the storage device, or each storage device, if there is more than one storage device. Each different chemical injection pump can have a different chemical housed therein, so that based upon the measurements of the sample, one or more different chemicals could be added to the system <NUM> to modify its properties. In other aspects, the chemical injection pumps do not need to comprise conduits for routing the chemical into the storage device but instead may be located sufficiently close to the storage device so that they can simply release chemicals into the storage device in a manner similar to a faucet over a sink. Moreover, a chemical injection pump can comprise a conduit that leads directly into a pipeline in the system <NUM>. In all aspects, the presently disclosed chemical injection pumps can be in communication with the controller <NUM>, as will be described hereinafter in greater detail.

In some embodiments, the controller <NUM> is operable to transmit signals directed to a data control system (not shown), and the signals are associated with at least one of the measured properties, total chlorine, and water percentage. Data transmission of measured parameters or signals to chemical pumps, alarms, remote monitoring devices such as computers or cellular telephones, or other system components is accomplished using any suitable device, and across any number of wired and/or wireless networks, including as examples, WiFi, WiMAX, Ethernet, cable, digital subscriber line, Bluetooth, cellular technologies (e.g., <NUM>, <NUM>, Universal mobile Telecommunications Systems (UMTS), GSM, Long Term Evolution (LTE), or more), etc. The Nalco Global Gateway is an example of a suitable device. Any suitable interface standard(s), such as an Ethernet interface, wireless interface (e.g., IEEE <NUM>. 11a/b/g/x, <NUM>, Bluetooth, optical, infrared, radiofrequency, etc.), universal serial bus, telephone network, the like, and combinations of such interfaces/connections may be used. As used herein, the term "network" encompasses all of these data transmission methods. Any of the described devices (e.g., archiving systems, data analysis stations, data capturing devices, process devices, remote monitoring devices, chemical injection pumps, etc.) may be connected to one another using the above-described or other suitable interface or connection.

For example, when the system <NUM> comprises one or more chemical injection pumps, these chemical injection pumps can be in communication with the controller <NUM> in any number of ways, including, as examples, through any combination of wired connection, a wireless connection, electronically, cellularly, through infrared, satellite, or according to any other types of communication networks, topologies, protocols, standards and more. Accordingly, the controller <NUM> can send signals to the pumps to control their chemical feed rates.

In an aspect, the system <NUM> is implemented to have a plurality of sensors (e.g., including, but not limited to, the emulsion level indicator <NUM>, chlorine analyzer <NUM>, and water analyzer <NUM>) provide continuous or intermittent feedback, feed-forward, or predictive information to the controller <NUM>, which can relay this information to a relay device, such as the Nalco Global Gateway, which can transmit the information via cellular communications to a remote device, such as a cellular telephone, computer, or any other device that can receive cellular communications. This remote device can interpret the information and automatically send a signal (e.g. electronic instructions) back, through the relay device, to the controller <NUM> to cause the controller <NUM> to make certain adjustments to the output of the pumps. The information can also be processed internally by the controller <NUM> and the controller <NUM> can automatically send signals to the pumps, to adjust the amount of chemical injection. Based upon the information received by the controller <NUM> from the plurality of sensors or from the remote device, the controller <NUM> can transmit signals to the various pumps to make automatic, real-time adjustments, to the amount of chemical that the pumps are injecting into the system <NUM>.

In the illustrated embodiment, the system <NUM> further includes a brine effluent analyzer <NUM> capable of measuring an oil percentage of the water phase. In some embodiments, the brine effluent analyzer <NUM> is capable of measuring the oil percentage of about <NUM>% or less. In some embodiments, the brine effluent analyzer <NUM> is capable of measuring the oil percentage of about <NUM>% to about <NUM>%. In some embodiments, the brine effluent analyzer <NUM> is capable of measuring an oil percentage of about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, or about <NUM>% or more. In further embodiments, the brine effluent analyzer <NUM> is capable of measuring an oil percentage of about <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, or about <NUM>% or less. The controller <NUM> may be operatively coupled to the brine effluent analyzer <NUM>, and adjust substantially in real time a dosage of an adjunct additive in response to the measured oil percentage so as to maintain the oil content in the effluent within a predetermined range.

Referring also to <FIG>, the controller <NUM> can accommodate a diagnostics display or dashboard <NUM>. For example, the diagnostics display <NUM> can include one or more of the following: a table <NUM> listing the volts and amps used to apply the electric field in the desalter vessel <NUM>, a listing <NUM> of the salt, chlorine and/or sulfur, and water in the raw crude oil; a listing <NUM> of the salt, chlorine and/or sulfur, and water in the desalted crude; and an oil percentage <NUM> of the water phase. Other arrangements of the diagnostics display <NUM> may also be used.

In operation, crude oil <NUM> and wash water <NUM> are mixed by a pressure drop across the mix valve <NUM>, thereby forming the crude oil/water phase stream <NUM>. The crude oil/water phase stream <NUM> is supplied into the desalter vessel <NUM>, whereupon an emulsion forms at an interface between the crude oil and the water phase. The crude oil/water phase stream <NUM> is contacted with a dosage of the emulsion breaker <NUM> in an applied electric field. At least one property associated with the emulsion (e.g., a width of the interface and a rate of change) is measured using the emulsion level indicator <NUM>. A total chlorine and a water percentage of the crude oil is measured. At least one of the pressure drop and the dosage of the emulsion breaker is adjusted substantially in real time in response to at least one of the measured properties, total chlorine, and water percentage. For example, if the controller <NUM> sees a sustained climb of total chlorine or a level of total chlorine of about <NUM> ppm or more, the controller <NUM> may be recommending changes to the mix valve <NUM> settings so as to maintain the total chlorine to about <NUM> ppm or less. It should be appreciated that a suitable or optimal chloride ion concentration range should be determined for each individual system. The optimum range for one system may vary considerably from that for another system. It is within the concept of this non-invention embodiment to cover any possible optimum chloride ion concentration range.

In some embodiments, a dosage of a caustic is injected substantially in real time in response to at least one of the measured properties, total chlorine, and water percentage. As a caustic agent, a dilute solution of sodium hydroxide is typically prepared in a <NUM> to <NUM> % concentration (<NUM> to <NUM>° Baume) for ease of handling and to enhance distribution once injected into the crude oil <NUM> or wash water <NUM>, for example. Concentration may be adjusted according to ambient conditions, such as for freeze point in cold climates. In some embodiments, changes in the caustic pump are limited in frequency. In some aspects, adjustment limits are set at a maximum of <NUM> per <NUM> and sequential adjustments in the same direction may not exceed <NUM>. For example, in some embodiments, after <NUM> total adjustments or a change of <NUM> % or <NUM> %, the pump could be suspended for an amount of time (e.g., <NUM> or <NUM> hours) and alarm could be triggered. If such a situation is encountered, it is advantageous to trigger an alarm to alert an operator. Other limits, such as maximum pump output or maximum sodium contribution to the system may also be implemented. It should be appreciated that it is within the scope of this non-invention embodiment to cause any number of adjustments in any direction without limitation. Such limits are applied as determined by the operator or as preset into the controller <NUM>. The disclosed systems and methods for automated real-time monitoring and controlling of desalting may be used in a variety of systems, including in a crude oil unit and in all desalting and/or dehydration technologies, used in upstream and downstream oil and gas process, with and without electrostatic fields.

It is understood that the foregoing detailed description and accompanying examples are merely illustrative and are not to be taken as limitations upon the scope of the invention, which is defined solely by the appended claims.

Claim 1:
A system for monitoring or controlling desalting in a crude distillation unit, comprising:
a mix valve for mixing crude oil and wash water by a pressure drop across the mix valve, thereby forming a crude oil/water phase stream;
a desalter vessel for receiving the crude oil/water phase stream, whereupon an emulsion forms at an interface between the crude oil and the water phase, the desalter vessel configured to contact the crude oil with a dosage of an emulsion breaker in an applied electric field;
an emulsion level indicator coupled to an outer surface of the desalter vessel, the emulsion level indicator capable of measuring at least one property associated with the emulsion at an interface between the crude oil and the water phase, wherein the at least one property associated with the emulsion is the width of the interface and a rate of change;
a chlorine analyzer capable of measuring a total chlorine of the crude oil;
a water analyzer capable of measuring a water percentage of the crude oil; and
a controller operatively coupled to the mix valve, emulsion level indicator, and either the chlorine analyzer, the water analyzer, or the chlorine analyzer and the water analyzer, wherein the controller adjusts substantially in real time at least one of the pressure drop and the dosage of the emulsion breaker in response to at least one of the measured properties, total chlorine, and water percentage.