CN116615273A

CN116615273A - Method for separating water and contaminants from valuable or hazardous liquids

Info

Publication number: CN116615273A
Application number: CN202180070797.0A
Authority: CN
Inventors: 克雷格·纳泽尔
Original assignee: Ke LeigeNazeer
Current assignee: Ke LeigeNazeer
Priority date: 2020-08-14
Filing date: 2021-08-13
Publication date: 2023-08-18

Abstract

The present disclosure is a method of removing water and contaminants from an aqueous feed stream comprising a water-soluble process liquid. Embodiments of the method may include dividing the method into a plurality of stages, vaporizing the process liquid by direct contact with a heated heating fluid, chemically removing the precipitated contaminants, and treating the heating fluid to maintain or enhance its properties.

Description

Method for separating water and contaminants from valuable or hazardous liquids

Technical Field

The present disclosure relates to a method of separating water and contaminants from valuable or hazardous water-soluble process liquids. These process liquids include glycols and amines having lower volatility than water, including those used in oil and gas processing.

Background

Water-soluble liquids, such as glycols and amines, are used in oil and gas production and refining. They are generally less volatile than water and in many cases can be diluted by water and contaminated with dissolved solid matter and liquid contaminants. For economic and environmental reasons, it is standard practice to apply treatment methods to remove at least a portion of the water and contaminants and reuse the liquid. Examples of such treatment methods are disclosed in US6,685,802, US8,728,321 and US8,652,304, which are incorporated herein by reference.

In oil and gas production facilities, fluids from oil and gas wells may contain significant amounts of condensed water and formation water. These fluids typically contain dissolved salts and other undesirable contaminants. In many of these plants, monoethylene glycol ("MEG") is injected into the hydrocarbon stream line to inhibit the formation of hydrates that could otherwise plug the pipeline. MEG and water are mutually soluble so that they together with hydrocarbons form a diluted glycol aqueous solution flowing in the pipe system. When crude hydrocarbons are collected in an oil and gas production plant, the diluted aqueous glycol solution (referred to in the oil and gas industry as "rich MEG") is typically separated from the hydrocarbons using gravity. The rich MEG is then filtered and re-concentrated, also known as "regenerated", typically by steaming off the water to about 70-90% to produce a so-called "lean MEG". Lean MEG is transported back upstream to be re-injected into the hydrocarbon production tubing. In this way, the diol is reused many times. However, without remedial action, contaminants, which typically include dissolved solid matter (e.g. salts) and undesirable liquids, accumulate in lean MEG each time MEG is separated, re-concentrated and re-used.

Contamination in glycols can cause increased corrosion, thermal degradation of glycols, unwanted precipitation of solid matter, fouling of heat transfer equipment, and other serious and costly operating problems. Chlorides, oxides, sulfates, bicarbonates, and carbonates of sodium, potassium, calcium, magnesium, iron, barium, and strontium are examples of inorganic contaminants. Sodium chloride is typically the most common dissolved contaminant in rich MEG. Other dissolved salt contaminants containing divalent ions (e.g., calcium, magnesium) are also often present. Organic acids and organic acid salts (e.g., acetates, propionates) can also be troublesome contaminants. The primary source of dissolved contaminants is formation water that flows out of the oil and gas production well with the hydrocarbon fluid. Another source may be brine (e.g., calcium chloride brine and calcium bromide brine) and other fluids used during drilling or injected into the flowline during or after exploration to prepare for initial production, or as a result of well maintenance activities. Other sources of contamination may include corrosion products of the flow line and chemicals injected into the flow line to control fouling and corrosion. In the oil and gas industry, a process for removing at least a portion of dissolved contaminants to maintain their quality when glycol is reused is known as "MEG recovery".

In plants that recover glycols (e.g., MEG) using the "flash" process disclosed in, for example, US6,685,802 and US8,728,321, a feed stream comprising an aqueous glycol solution containing contaminants (including dissolved inorganic salts) is rapidly boiled when mixed with a heated stream of concentrated glycol within and/or upstream of a flash separation vessel. The process in which water and process liquid are vaporized by direct contact with heated amount of concentrated process liquid is referred to herein as the "flash process liquid" process. Typically at least some of the vaporized components of the feed stream are then condensed or further separated into water and a concentrated process liquid by distillation.

When used for MEG recovery, the process is usually run under vacuum at an absolute pressure of 0.1 to 0.5 bar in order to reduce the operating temperature, which is typically good practice when handling heat-sensitive process liquids such as MEG. Concentrated MEG that has been or will be heated and mixed with the feed stream to cause the above-mentioned flash is withdrawn from the liquid pool in the lower part of the flash separation vessel. One non-limiting example of a heating method includes pumping a portion of the concentrated MEG out of the liquid pool and through a heater to raise its temperature and then mixing the heated pumped MEG with the feed stream as it enters the flash separation vessel. Evaporation results in precipitation of dissolved salts in the feed stream. The precipitated salts accumulate in the liquid pool along with other non-volatile contaminants, if present.

When used for MEG recovery, the flash process liquid process typically comprises additional mechanical separation equipment, such as centrifuges, settling tanks, clarifiers or filters, to separate precipitated and suspended solids from the pool of concentrated process liquid in the flash separation vessel. The solids are then typically disposed of. The need for these increased equipment items presents drawbacks such as complexity, higher capital and operating costs, increased weight and floor space, loss of process liquid containing waste solids, and risk of environmental damage due to loss of process liquid.

In flash separation vessels, sodium chloride typically precipitates in the form of distinct particles that can be separated by gravity or other mechanical means. With respect to non-limiting examples of MEG recovery, it has been widely observed that the above-described process can be used to effect evaporation of water and glycol in a feed stream and precipitation and removal of monovalent salts including sodium chloride and potassium chloride (note that most salts in a typical rich MEG are monovalent salts). However, this method does not solve the problems that occur when MEG in the flash separation vessel is excessively contaminated with divalent ions.

Calcium and other troublesome divalent ions are typically present in rich MEG. If the feed stream contains significant amounts of calcium, the calcium accumulates in the concentrated MEG in the liquid pool in the flash separation vessel without additional treatment. Calcium ions dissolved in the concentrated MEG cannot reliably precipitate to form well behaved particles in the flash process liquid process. Instead, calcium ions can combine with MEG and chloride ions to form complex calcium-ethylene glycol-chloride compounds that solidify if allowed to cool to less than about 95 ℃. This is a costly endeavor in several operating plants. Other divalent ions including magnesium may cause similar effects.

The presence of calcium and other divalent ions in the feed stream to MEG recovery systems is generally unavoidable considering that the composition of several types of subterranean hydrocarbon reservoir rocks (e.g., limestone) includes such elements. In addition, when drilling or preparing for production, operators may use high density fluids containing dissolved calcium (e.g., calcium chloride, calcium bromide, etc.), which may then flow through the hydrocarbon production tubing and into the MEG recovery system. This divalent ion problem is described in reference 1.

Plant designers have sought to solve the divalent ion problem by including additional processing systems. In a typical version of this additional system, an aqueous solution of a treatment chemical (e.g. sodium carbonate) is added to the rich MEG feed stream upstream of the flash process. The calcium ions react with the added carbonate ions to form particles of waste (e.g., calcium carbonate), which can then be mechanically separated from the MEG (e.g., by filtration) and disposed of. Thus, additional waste is generated by this method of treating the divalent ion problem. Disadvantages of this divalent ion treatment method include: the cost and complexity of adding chemicals to the feed stream; additional mechanical separation equipment is required to remove additional waste, both in size, cost and complexity. Furthermore, the mechanical separation device will leave at least one film of process liquid on the surface of the waste particles, thereby increasing the process liquid loss and the potential risk of damage to the environment.

The processes disclosed in US8,652,304 and US10,328,360 are recent variations of flash processes in which an alternative heating medium (referred to herein as a "heating fluid", which may be, for example, an oil or oil liquid) is heated and mixed with the feed stream to evaporate the process liquid, rather than using a concentrated process liquid for this purpose. In this disclosure, the term "flash heated fluid process" refers to a process that uses direct contact between a process liquid and a heated fluid to vaporize at least a portion of the process liquid, thereby separating contaminants from the process liquid.

US8,652,304 and US10,328,360 describe various versions of flash heating fluid processes. Both inventions require filling the flash separation vessel with a large amount of heating fluid that is less volatile than and immiscible with the process liquid. For the MEG recovery example, many suitable heating fluids with these properties will be oily, or expensive to purchase, or potentially harmful or dangerous. The fluid is heated and mixed with the contaminated process liquid, thereby causing non-volatile contaminants (including at least some of those initially in the contaminated process liquid) to mix with and contaminate the heated fluid pool in the flash separation vessel.

US8,652,304 describes the precipitation and removal of contaminants comprising monovalent salts (including sodium chloride) from an aqueous MEG feed stream. The precipitated salts accumulate in the heated fluid pool and are removed by mechanical means, including settling by a stripping process.

In US10,328,360, the process objective is "partial evaporation" of volatile components (i.e. water and process liquid) in a "process stream". The dissolved salts remain dissolved in the unvaporised portion of the process stream. Blowdown is described as a means of removing a mixture of heated fluid and non-evaporated process liquid to remove dissolved salts. The use of blowdown to remove unwanted dissolved species from valuable process liquids is a well known method used in many industries, however the amount of process liquid lost in the blowdown stream is typically significantly greater than the amount of unwanted dissolved species due to solubility limitations. This is acceptable when recovered from temporary operating problems or if the loss of process liquid does not cause damage but may not be tolerable for conventional handling of the salt-containing diol. The solubility of common salts in MEG is only about one sixth of the solubility in water. This blowdown method of removal of sodium chloride at MEG recovery sites will result in loss of several liters of MEG per kilogram of dissolved salt removed due to the low solubility of salt in MEG. MEG losses of this magnitude are far higher than those that currently occur at MEG recovery points using flash evaporation on older process liquid processes (e.g. US6,685,802 and 8,728,321).

In US10,328,360, undissolved solid matter is removed by mechanical separation means designated as "hydrocyclone, centrifuge, particulate filter, settling tank or some other separation means component equivalent to these". These devices separate solid matter from surrounding liquids, which in US10,328,360 consist essentially of a mixture of heating fluid (which may be oily or valuable or dangerous) and process liquid. The separated waste solid material will remain encapsulated (if not immersed) in the mixture of heating fluid and process liquid, resulting in loss of both liquids and the attendant risk of damaging the environment.

Accumulation of contaminants in the heating fluid may cause degradation or other undesirable changes in the properties of the heating fluid. Neither US8,652,304 nor US10,328,360 disclose a remedy to correct contamination and/or degradation of the heating fluid. Degradation of the heating fluid may impair its ability to separate contaminants from the process liquid during evaporation. For the example of MEG recovery, there are multiple streams that can flow from oil and gas wellsNot exceed the numberIs a potential contaminant of (a). Those skilled in the art know what is coming out of the hydrocarbon-bearing reservoir year by year, and not exactly what is possible in advance. Furthermore, if there are problems with oil or gas production, there are many ways to deal with this. Many of these involve adding chemicals to the well stream that eventually enter the rich MEG. In addition, equipment that should intercept contaminants upstream of the MEG recovery system may be undersized or otherwise not performed. A malfunction or operation error may occur. Have been and will continue to be surprisingly present in rich MEG compositions in many oil and gas production sites. Emphasis is often placed on maintaining hydrocarbon production, while MEG recovery systems cope with a wide, often unpredictable, variety of undesirable materials. The present disclosure provides means to remove contaminants from heating fluid used in flash heating fluid processes and maintain or improve their quality thereby improving the reliability of MEG recovery systems. In this disclosure, the term "purifying" a heating fluid means removing, eliminating, dissolving, destroying, or otherwise cleaning at least a portion of any one or more contaminants in the heating fluid that may be in the process of flashing the heating fluid.

Contaminants known to cause problems in MEG recovery systems include acetates, propionates and other organic acid salts. Liquid contaminants can also create problems by interfering with the operation of equipment or instruments or by promoting the formation of slurries or gums or viscous residues. Examples include resins, tars, asphaltenes, waxes, and the like. Other contaminants can cause or promote fouling and corrosion. Another source of contamination may be thermal degradation of glycols (e.g., oxalic acid, formic acid, glycolic acid, etc.).

Contamination and other variations on the heating fluid may also have a chain reaction to the quality of the lean MEG output stream. Contaminants in the heating fluid may be inadvertently transported back into the output product stream.

US8,652,304 specifies that the heating fluid is oily or oily, which is an unnecessary limitation. It has been found that for some applications other liquids including ionic liquids and deep eutectic solvents may be or may become suitable candidates for use in heating fluids.

The prior art does not disclose methods of correcting or preventing contamination, degradation, or other forms of degradation of heated fluids.

The shortcomings of the prior art are addressed or avoided or at least ameliorated in the present disclosure in which a flash heating fluid process is substantially improved by: specifying a wide range of fluids capable of performing the function of heating the fluid; adding new chemical separation means (e.g., by dissolving sodium chloride) to remove contaminants that would otherwise accumulate in the heated fluid to an excessive extent; and adding additional new heating fluid treatment means ("HFTM") including means to enhance, purify, recover and/or regenerate the heating fluid and/or to improve or correct unwanted changes in its composition and/or properties.

The present disclosure also includes novel embodiments wherein the process of separating water and contaminants from process liquids is divided into several process stages, including a flash heating fluid stage. The heating fluid is used only in a flash heating fluid process, which results in significantly less energy consumption than is required to remove similar amounts of contaminants from similar amounts of process liquid using the prior art techniques disclosed in US8,652,304 or US10,328,360. The reduction in energy requirements can be correspondingly reduced: the size and cost of the heating fluid pool; the size and cost of the equipment required to contain, pump and heat the heating fluid; loss of heating fluid (expected loss would also be reduced if less heating fluid is heated); and the risk of inadvertently transferring unwanted substances from the heating fluid into the clean, concentrated process liquid output stream.

The reduced size of the heating fluid pool results in a corresponding significant reduction in the cost of improving the composition of the heating fluid. For example, in MEG recovery, improving the flexibility of heating fluids may help to optimize the treatment of hydrocarbon well streams, which often have widely varying MEG, water and contaminant flow rates over many years of production. Typically, many wells begin with little or no formation water flow. When there is a breakthrough in formation water, the actual amount and composition of salts and other contaminants may vary significantly from the design situation used for the initial construction. The present disclosure provides an option for varying the amount and composition of the heating fluid to optimize performance at a lower cost than the prior art, as Chi Xiao of the heating fluid is much more. The operator may choose to replace the contaminated degraded heating fluid with fresh heating fluid or to change the composition or type of heating fluid. Furthermore, in the future, better heating fluids may be developed, for example by introducing newly developed liquid types (e.g., ionic liquids or deep eutectic solvents), and using the present disclosure will be easier and cheaper with such technological advances.

Disclosure of Invention

In a first aspect, there is provided a method of removing contaminants (including dissolved contaminants) from a feed stream comprising water and the contaminants and a process liquid that is water soluble and less volatile than water, the method comprising the steps of:

a) Heating a heating fluid comprised of components that are immiscible with a salt solvent and less volatile than the process liquid to produce a heated heating fluid;

b) Contacting at least a portion of the feed stream with at least a portion of the heated heating fluid upstream of and/or at one or more locations within a flash separator to vaporize at least a portion of the process liquid, thereby causing at least a portion of the dissolved contaminants to form precipitated solid material;

c) Mixing at least a portion of the heating fluid with at least a portion of the precipitated solid matter, thereby producing a depleted mixture comprising at least a portion of the heating fluid and at least a portion of the precipitated solid matter; and

d) Contacting the salt solvent with at least a portion of the depleted mixture, whereby the salt solvent dissolves at least a portion of the precipitated solid material to produce a waste stream comprising at least a portion of the dissolved contaminants.

In a second aspect, there is provided a method of removing contaminants (including dissolved contaminants) from a feed stream comprising water and the contaminants and a process liquid that is water soluble and less volatile than water, the method comprising the steps of:

a) Applying a concentration process to remove water from at least a portion of the feed stream to produce a stage a output stream having a process liquid concentration higher than the process liquid concentration of the feed stream;

b) Heating a heating fluid comprised of components that are immiscible with a salt solvent and less volatile than the process liquid to produce a heated heating fluid;

c) Contacting at least a portion of the stage a output stream with at least a portion of the heated heating fluid upstream of and/or at one or more locations within a flash separator to vaporize at least a portion of the process liquid, thereby forming at least a portion of the dissolved contaminants into precipitated solid material;

d) Mixing at least a portion of the heating fluid with at least a portion of the precipitated solid matter, thereby producing a depleted mixture comprising at least a portion of the heating fluid and at least a portion of the precipitated solid matter; and

e) Contacting the salt solvent with at least a portion of the depleted mixture, whereby the salt solvent dissolves at least a portion of the precipitated solid material to produce a waste stream comprising at least a portion of the dissolved contaminants.

In one embodiment of the above method, the concentration process comprises heating the feed stream to a temperature sufficient to vaporize and remove at least a portion of the water.

In a third aspect, there is provided a method of removing contaminants (including dissolved contaminants) from a feed stream comprising water and the contaminants and a process liquid that is water soluble and less volatile than water, the method comprising the steps of:

a) Heating the concentrated process liquid to produce a heated concentrated process liquid;

b) Contacting at least a portion of the feed stream with at least a portion of the heated concentrated process liquid upstream of and/or at one or more locations within a stage B separation vessel to vaporize a portion of the process liquid, thereby producing an unvaporised liquid comprising at least a portion of the dissolved contaminants;

c) Mixing at least a portion of the unvaporised liquid with at least a portion of the concentrated process liquid, thereby producing a stage B-C stream comprising at least a portion of the process liquid and at least a portion of the dissolved contaminants;

d) Heating a heating fluid comprised of components that are immiscible with a salt solvent and less volatile than the process liquid to produce a heated heating fluid;

e) Contacting at least a portion of the stages B-C with at least a portion of the heated heating fluid upstream of and/or at one or more locations within a flash separator to vaporize at least a portion of the process liquid, thereby causing at least a portion of the dissolved contaminants to form a precipitated solid material;

f) Mixing at least a portion of the heating fluid with at least a portion of the precipitated solid matter, thereby producing a depleted mixture comprising at least a portion of the heating fluid and at least a portion of the precipitated solid matter; and

g) Contacting the salt solvent with at least a portion of the depleted mixture, whereby the salt solvent dissolves at least a portion of the precipitated solid material, thereby producing a waste stream comprising at least a portion of the dissolved contaminants.

In the above aspect, embodiments are provided wherein the flow rate of the stage B to C streams is adjusted to limit the accumulation of at least a portion of the dissolved contaminants in the stage B separation vessel.

In any of the above aspects, embodiments are provided wherein one or more heating fluid treatment means are applied to decontaminate at least a portion of the heating fluid and/or to adjust a property of the heating fluid.

In any of the above aspects, embodiments are provided wherein one or more substances are added and mixed with at least a portion of the heating fluid to cause a reaction with carbonate and/or bicarbonate contaminants to produce water and/or carbon dioxide.

In any of the above aspects, embodiments are provided wherein one or more substances are added and mixed with at least a portion of the heating fluid to cause a reaction that converts at least a portion of the organic salt contaminants (including acetate salts) to volatile organic acids (including acetic acid) and evaporates at least a portion of the volatile organic acids.

In any of the above aspects, embodiments are provided wherein one or more substances are added and mixed with at least a portion of the heating fluid to remove and/or dissolve and/or destroy asphaltenes, resins, gums, and/or slurries.

In any of the above aspects, embodiments are provided wherein one or more substances are added and mixed with at least a portion of the heating fluid to prevent or inhibit the formation of scale or scale deposits on the metal surface or to enable removal of scale or scale deposits on the metal surface.

In any of the above aspects, embodiments are provided wherein one or more substances are added and mixed with at least a portion of the heating fluid to break up, compress, or inhibit the formation of an emulsion or foam.

In any of the above aspects, embodiments are provided wherein one or more substances are added and mixed with at least a portion of the heating fluid to reduce the cloud point and/or freezing point of the liquid contaminant.

In any of the above aspects, embodiments are provided wherein one or more substances are added and mixed with at least a portion of the heating fluid to neutralize acid and/or increase alkalinity and/or inhibit corrosion.

In any of the above aspects, embodiments are provided wherein one or more substances are added and mixed with at least a portion of the heated fluid to react with dissolved contaminants and cause precipitation of solid substances that can be removed by mechanical separation means.

In any of the above aspects, embodiments are provided wherein one or more substances are added and mixed with at least a portion of the heating fluid to reduce the oxygen content of the heating fluid.

In any of the above aspects, embodiments are provided wherein one or more substances are added and mixed with at least a portion of the heating fluid to adjust one or more properties of the heating fluid, including, but not limited to, density, vapor pressure, viscosity, thermal stability, pH, solubility, heat capacity, thermal conductivity, corrosiveness, toxicity, and flammability.

In any of the above aspects, embodiments are provided wherein at least a portion of the heating fluid is heated to evaporate and thereby remove at least a portion of the liquid contaminant.

In any of the above aspects, embodiments are provided wherein at least a portion of the liquid contaminant is removed from the flash separator in liquid form.

In any of the above aspects, embodiments are provided wherein mercury is removed from at least a portion of the heating fluid.

In any of the above aspects, embodiments are provided wherein contaminant particles of solid matter are removed from at least a portion of the heated fluid by mechanical separation means including, but not limited to, any one or more of centrifugation, sedimentation, clarification, filtration, and hydrocyclone.

In any of the above aspects, embodiments are provided wherein the one or more heating fluid treatment means comprises adding one or more substances and mixing the added substances with at least a portion of the heating fluid to cause a reaction that converts at least a portion of the organic salt contaminants to volatile organic acids and evaporating at least a portion of the volatile organic acids.

In any of the above aspects, embodiments are provided wherein a voltage or current is applied to at least a portion of the heating fluid, thereby causing ions of the contaminant species to migrate toward the electrode from which they can be removed.

In any of the above aspects, embodiments are provided wherein the heating fluid comprises a component that is immiscible with the process liquid.

In any of the above aspects, embodiments are provided wherein the salt solvent comprises water.

In any of the above aspects, embodiments are provided wherein the process liquid comprises any one or more liquids selected from the group consisting of: monoethylene glycol; diethylene glycol; triethylene glycol; and amines.

In any of the above aspects, embodiments are provided wherein the dissolved contaminant comprises any one or more of: monovalent salts including sodium chloride; divalent ions including calcium; and organic acid salts including acetate salts.

In any of the above aspects, embodiments are provided wherein all of the process liquid, except at least a negligible residue, in contact with the heated heating fluid is vaporized.

In any of the above aspects, embodiments are provided wherein at least 95%, or preferably at least 98%, of the process liquid in contact with the heated heating fluid is evaporated.

In any of the above aspects, embodiments are provided wherein at least a portion of the vaporized process liquid is condensed.

In any of the above aspects, embodiments are provided wherein at least a portion of the heating fluid is heated by a heating device located inside the flash separator and/or by flowing through a heater located outside the flash separator.

In any of the above aspects, embodiments are provided wherein the flash separator is operated at a pressure below atmospheric pressure.

In any of the above aspects, embodiments are provided wherein the heating fluid comprises one or more liquid components selected from any of the following: an oil; a fatty acid; a heat transfer fluid; a liquid metal; an ionic liquid; deep eutectic solvents.

In any of the above aspects, embodiments are provided wherein at least a portion of the salt solvent enters the flash separator and mixes with the depleted mixture and dissolves at least a portion of the precipitated solid matter, thereby producing a waste stream comprising at least a portion of the dissolved contaminants.

In any of the above aspects, embodiments are provided wherein at least a portion of the depleted mixture is moved into a solvent washing system, wherein at least a portion of the precipitated solid matter is dissolved in at least a portion of the salt solvent, thereby producing a waste stream comprising at least a portion of the dissolved contaminants. Other embodiments are provided wherein the operating temperature and pressure in the solvent wash system are adjusted in a manner that avoids boiling of the salt solvent in the solvent wash system.

Brief description of the drawings

Fig. 1 shows an overview of the options for arranging the various stages of the overall method. These include three stage options (stage a plus stage B plus stage C), a pair of two stage options (stage a plus stage C, stage B plus stage C), and a single stage option (separate flash heating fluid).

Figure 2 shows a non-limiting example of an optional configuration of a separate flash heating fluid.

Fig. 3 shows a non-limiting example of an optional configuration of stage a plus stage C.

Fig. 4 shows a non-limiting example of an optional configuration of stage B plus stage C.

Detailed Description

The present disclosure provides a method including configuration of process stages for the purpose of separating water, dissolved salts, and other contaminants from a feed stream comprising a solution of water and a water-soluble process liquid such as, but not limited to, glycols, including monoethylene glycol (MEG) and amines. In embodiments, the stage may include the following processes: concentration, labeled herein as "stage a"; flashing the process liquid, labeled herein as "stage B"; and flash heating the fluid, labeled herein as "stage C".

Fig. 1 presents an overview of an embodiment of the present disclosure. These may include three stage options (stage a plus stage B plus stage C), a pair of two stage options (stage a plus stage C, and stage B plus stage C), and a separate flash heating fluid process.

In the three stage option embodiment, the feed stream comprising the aqueous process liquid solution enters stage a where water is removed from the feed stream, thereby producing a concentrated process liquid solution. For example, this stage of the process can include heating the feed stream to evaporate at least a portion of the water and separating the evaporated water from the unvaporized portion of the feed stream. The concentrated process liquid produced in stage a may then flow to stage B where it is heated and partially vaporized using, for example, a flash process liquid process where heat of vaporization is provided by heating a stream of concentrated process liquid and mixing the heated concentrated process liquid stream with the feed stream. The vapor from stage B can be condensed to produce an output stream of concentrated process liquid that is substantially salt-free. The non-vaporized residue stream of the concentrated process liquid containing dissolved and precipitated salts and other contaminants can flow to stage C. Salts and other contaminants may be removed in stage C using a flash heating fluid process in which the heated heating fluid provides heat to vaporize the process liquid. The vaporized process liquid in stage C may be condensed to produce an output stream of substantially salt-free concentrated process liquid.

In the present disclosure, the term "concentrated process liquid" refers to a liquid having an elevated concentration of process liquid in the range of 0.1% up to 100% higher than the concentration of process liquid in the feed stream 10.

Non-limiting examples of preferred embodiments are shown in fig. 2, 3 and 4 and described below.

Independent flash heating fluid

FIG. 2 shows a non-limiting example of a separate flash heating fluid configuration. Referring to the embodiment shown in fig. 2, feed stream 10 comprises water, a water-soluble process liquid having a lower volatility than water, dissolved contaminants including monovalent salts (e.g., sodium chloride), divalent ions (e.g., calcium and magnesium), and organic salts (e.g., acetate salts), and liquid contaminants. The feed stream 10 enters the flash separator 21 through one or more inlets. The flash separator 21 is a flash heated fluid separation vessel that contains a liquid pool into which separated liquid and solid material is collected. In embodiments, the separated vapor can flow out of the upper portion of flash separator 21. The liquid pool in the flash separator 21 may contain a heating fluid comprising a liquid component having a lower volatility than the process liquid. A pump 23 may withdraw heating fluid from the flash separator 21 and pump it through a heater 24 to produce a heating fluid stream 25. Stream 25 and stream 10 are in direct contact with each other upstream of flash separator 21 and/or at one or more locations within flash separator 21. For example, there may be one or more mixing zones or chambers upstream of flash separator 21 into which streams 10 and 25 or portions thereof flow and mix with each other, and/or there may be multiple inlets for streams 10 and 25 to enter flash separator 21, such that the two streams or portions thereof mix with each other within flash separator 21. Alternatively, stream 10 or a portion thereof may enter the liquid pool in flash separator 21 and contact the heated heating fluid therein.

Sufficient heat is added to the heating fluid in heater 24 and/or by heating the heating fluid in flash separator 21 to cause at least a portion of the water and process liquid in stream 10 to evaporate when stream 20 contacts the heated heating fluid.

In embodiments, all of the process liquid in stream 10, except at least a negligible residue, may be vaporized due to contact between stream 10 and the heated heating fluid. In the present disclosure, the term "negligible residue" refers to an amount that does not exceed the maximum loss of process liquid allowed by a particular application of the present disclosure. For example, in MEG reclamation applications, if the allowable maximum loss of MEG is 0.5%, the term "all process liquids except at least negligible residue" refers to at least 99.5% MEG in feed stream 10.

In embodiments, more than 95% or preferably more than 98% of the process liquid in stream 10 will evaporate due to contact between stream 10 and the heated heating fluid.

Those skilled in the art will recognize that alternative possible means of heating the heating fluid exist. In one embodiment, at least a portion of the heating fluid may be heated in the liquid pool of the flash separator 21, for example by immersing a tube bundle or heating coil or vessel heating jacket or other type of heating device. This may be in addition to or in lieu of the pump system shown in fig. 2 (i.e., pump 23 and heater 24).

The following description under the heading: "separation and removal of contaminants"; "heating fluid composition"; and "heating fluid treatment means" are applicable to embodiments of the present disclosure, including those shown in fig. 2, 3, and 4.

Separation and removal of contaminants

The vaporized process liquid and optionally vaporized liquid contaminants and optionally liquid components of the vaporized heating fluid leave flash separator 21 and flow via stream 26 to condenser system 27 where separation and condensation of vapor components may be accomplished using standard methods known to those skilled in the art. The condenser system 27 may comprise equipment enabling the flash separator 21 to be operated at a pressure below atmospheric pressure, for example at a pressure of less than 0.5 bar, or less than 0.2 bar. Stream 28 may include uncondensed gases and vapors, which may then be removed. Stream 29 is the output product stream of the concentrated process liquid that may contain salts and other contaminants depleted. Stream 30 is optional and may comprise condensed heating fluid, which may then be returned to the flash separator 21 liquid pool. Stream 31 is optional and may contain condensed liquid contaminants that are subsequently removed.

The flash heated fluid process removes dissolved contaminants (e.g., salts) by evaporating at least a portion of the liquid containing the dissolved contaminants, thereby causing the dissolved contaminants to precipitate and accumulate in the pool of heated fluid in the flash separator 21. In embodiments, all of the process liquid, except at least a negligible residue, may be removed from flash separator 21 as a vapor. For the example of MEG recovery applications, this may provide an effective simple solution to the divalent ion problem. In the present disclosure, calcium and other divalent ions that may come out of solution when the concentration reaches and exceeds the solubility limit are surrounded by the heating fluid. MEG molecules have been evaporated and thus lack MEG available to form the troublesome complex calcium-MEG-chloride. This enables calcium chloride and/or other non-troublesome calcium salts to precipitate and, together with the precipitated monovalent salt, mix with the heating fluid in the liquid pool in the flash separator 21. Calcium chloride is a well known water-soluble salt. The mixture of heating fluid and precipitated solid matter (e.g., salt) that is subsequently collected in the liquid pool in flash separator 21 depletes the process liquid and is referred to herein as a "depleted mixture".

In the embodiments shown in fig. 2, 3 and 4, a portion of the depleted mixture may be pumped from flash separator 21 to solvent washing system 40. A liquid, referred to herein as a "salt solvent," comprising a component that can dissolve at least a portion of the precipitated salt in the depleted mixture can flow into solvent washing system 40 via stream 42, contact the depleted mixture and dissolve at least a portion of the precipitated salt to produce a salt waste stream. In embodiments, the heating fluid may be comprised of a liquid component that is not miscible with the salt solvent and may be less dense than the waste stream. Thus, after removal of the desired amount of salt, the desalted heating fluid can be readily separated from the salt waste liquid and removed from the solvent washing system 40, and from there further processed and/or returned to the flash separator 21. The separated brine effluent exits solvent washing system 40 via stream 43. In the example of MEG recovery applications, the most common dissolved contaminant is a water-soluble salt that allows water to be used as a component of the salt solvent.

In other applications, the salt solvent may include other liquids (e.g., organic solvents, alcohols, deep eutectic solvents) capable of dissolving the particular contaminants present in these applications.

In one embodiment, the solvent washing system may be operated at a pressure high enough to avoid boiling the salt solvent when the depleted mixture contacts the salt solvent in the solvent washing system 40. Otherwise boiling can disrupt operation. Alternatively or additionally, the depleted mixture may be cooled prior to contacting the salt solvent in the solvent washing system 40.

In embodiments, the step of dissolving at least some of the precipitated salt may be accomplished by temporarily stopping normal operation and adding salt solvent directly to the depleted mixture in the liquid pool in flash separator 21. This may require adjusting the operating temperature and pressure in the flash separator 21 to avoid boiling. The salt solvent will dissolve at least a portion of the precipitated solid matter, thereby producing a waste liquid containing dissolved contaminants, which can be separated from the heating fluid and removed from the flash separator 21.

In a flash heating fluid process, the heating fluid may be intentionally repeatedly exposed to a wide range of substances that were initially in the feed stream 10 and have entered the flash separator 21. Some of these materials may contain undesirable contaminants (solids and liquids) that may not be removed in the solvent washing system 40. Some of these contaminants may result in a reduced quality of the heating fluid. To correct or avoid such degradation of the flash heating fluid process according to one or more embodiments, one or more Heating Fluid Treatment Means (HFTM) may be included, details of which are disclosed elsewhere in the disclosure (including the heading "heating fluid treatment means") to purify and/or alter the properties of the heating fluid and/or provide other remedial measures to maintain or enhance the state and performance of the heating fluid. In the non-limiting illustrations in fig. 2, 3 and 4, a portion of the heating fluid may be pumped from flash separator 21 into a heating fluid processing system (HFTS) 41 in which one or more HFTMs may be implemented. Stream 44 symbolically shows that chemicals may optionally be added to HFTS 41 to perform one or more HFTMs. As shown, the contaminants are removed via stream 46.

While some HFTMs may be performed by pumping a heating fluid into the HFTS, some other HFTMs may be performed by adding chemicals directly into the flash separator 21, for example via optional stream 45, or into the feed stream 10 or at another effective location, and/or removing contaminants directly from the flash separator 21. Some contaminants may optionally be withdrawn from flash separator 21 via stream 47 or vaporized to exit flash separator 21 in stream 26, after which they may be removed via stream 28 and/or stream 31.

In embodiments, the present disclosure substantially reduces the risk of process liquid loss in the waste stream, while correspondingly reducing the risk of harm to the environment. In embodiments in which all but at least a negligible residue of the process liquid is removed as vapor from flash separator 21, there is no way by which a non-negligible amount of the process liquid can enter and be lost with the contaminant-containing effluent.

By comparison in the prior art, the solid waste is separated from the process liquid using mechanical means (e.g., filters, clarifiers, settling tanks, centrifuges). This results in loss of process liquid, as the surface of the disposed of waste solid particles will typically be covered by or immersed into the process liquid to at least some extent.

Heating fluid composition

The heating fluid consists of a component having a lower volatility than the process liquid, the component being immiscible with the salt solvent and selected from one or more of the following groups: unrefined hydrocarbon oils, including crude oil without distillation, diesel, fuel oil, middle distillate, one or more other distilled crude oil fractions; refined hydrocarbon oils including base oils, hydrocracked base oils; synthetic oils and silicone oils; non-hydrocarbon oils including vegetable oils, seed oils, fish oils, biodiesel, other animal oils; fatty acids including oleic acid, erucic acid, other fatty acids; heat transfer fluids, including those used in solar facilities; hydraulic oil, lubricating oil and transmission fluid; liquid metals including gallium and gallium alloys, wood metals, lead tin bismuth alloys, fusible alloys; an ionic liquid; a deep eutectic solvent; the volatility is negligible or at least low enough to avoid excessive evaporation of other fluids.

Some types of fluids have recently been discovered or invented, including many ionic liquids and deep eutectic solvents. These fluids may not be suitable for widespread use due to high costs, however, they are the subject of ongoing extensive research. A non-limiting range of such fluids suggested for heat transfer applications, which may at some time in the future include potential uses as components of the heating fluid in the present disclosure, is described in WO 2017/085600.

Heating Fluid Treatment Means (HFTM)

The quality of the heating fluid may deteriorate over time due to repeated mixing with contaminated process liquid. HFTM is included in the present disclosure to maintain or improve the quality of the heating fluid.

In a non-limiting example of MEG recovery, as described above, most contaminants include water-soluble salts, which can be removed by including water as a component (possibly the sole component) of the salt solvent. However, as discussed below, there may be a variety of other types and sources of contamination of the heating fluid.

The heating fluid is continuously mixed with more and more contaminants from day to day. These contaminants may accumulate and cause undesirable changes in the properties of the heating fluid, such as its thermal stability, chemical stability, density, acidity, alkalinity, viscosity, boiling point, solubility, thermal conductivity, heat capacity, corrosiveness, toxicity, flammability, and/or surface tension. In the example of MEG recovery, upstream systems that typically intercept or counter-balance contaminants (e.g., filters, stoichiometric treatments) may fail or be defeated by unusual process conditions, allowing segments of contaminant material to enter the recovery equipment and mix with the heated fluid.

The prior art does not include means to avoid or correct contamination, degradation and degradation of the heated fluid. Means to maintain or enhance the quality of the heating fluid is desirable so that it can be used repeatedly for months or years. This can be expensive if the user has to discard the heating fluid frequently due to its degradation in quality and replace it with a new cleaning heating fluid, or alternatively has to send it elsewhere for cleaning. The present disclosure reduces or avoids these costs by including a series of optional means of treating the heating fluid and extending its lifetime.

Some contaminants may form an undesirable layer of slurry or debris. Asphaltenes, resins, waxes, and/or other organic contaminants, including those flowing from the well, can form a sticky mass that adheres to equipment surfaces and scale heaters, or form troublesome slurries and cementing equipment. Contaminants may flow out of the separation vessel with the vapor stream and then contaminate the condensed process liquid. Contaminants may be generated by oxidative or thermal degradation of the process liquid or the heating fluid itself. The contaminants may react with the process liquid or the heating fluid to form substances that are difficult to remove.

Mercury is a toxic substance that can contaminate fluids entering MEG recovery facilities.

Oxygen may enter the rich MEG in dissolved form or dissolved in the added liquid or due to air leakage, which may accelerate corrosion and degradation of some process liquids including MEG.

Ions of calcium, sodium, potassium, barium, iron, strontium, magnesium, etc. can combine with carbonate, bicarbonate, hydroxide, sulfide, and/or sulfate ions to form precipitates that cause scaling and fouling. The accumulation of acid in the heating fluid may cause or accelerate corrosion. Fine particles of contaminants such as clay may be trapped in the foam or emulsion in the heating fluid. Ingredients in chemicals (e.g., corrosion inhibitors, dispersants, demulsifiers, defoamers, pH control agents, scale inhibitors) that may be carried into the heating fluid and cause undesirable changes in its properties or otherwise impair its performance have been added to the process liquid before it enters the apparatus for practicing the present disclosure.

HFTM includes means to avoid or correct these problems. The range, type and capacity of HFTM are expected to vary to match the nature and severity of the contamination and degradation encountered in each particular application.

The present disclosure enables inclusion of any one or more HFTM selected from the list of:

adding one or more substances and mixing the added substances with at least a portion of the heating fluid to achieve any one or more of the following effects: causing a reaction with carbonate and/or bicarbonate contaminants to convert at least some of the contaminants to water and/or carbon dioxide; reducing the oxygen content of the heating fluid; removing and/or dissolving and/or disrupting asphaltenes, resins, gums and/or slurries; preventing or inhibiting the formation of scale or scale deposits on the metal surface, or enabling the removal of scale or scale deposits on the metal surface;

break down, compress or inhibit the formation of emulsions or foams (e.g., by adding demulsifiers or defoamers); lowering the cloud point and/or freezing point of the liquid contaminant; neutralizing the acid and/or increasing the alkalinity and/or inhibiting corrosion; reacts with the dissolved contaminants and causes precipitation of solid matter that can be removed by mechanical separation means; and adjusting one or more properties of the heating fluid including, but not limited to, density, vapor pressure, viscosity, thermal stability, pH, solubility, heat capacity, corrosiveness, thermal conductivity, toxicity, and flammability. The added substance may be added directly to the heating fluid or to any stream in contact with the heating fluid.

Removing at least a portion of the heating fluid and replacing said portion with a heating fluid having enhanced properties.

Mercury removal from the heating fluid.

Removing liquid contaminants in liquid form from the flash separator.

Heating at least a portion of the heating fluid to a temperature that causes the liquid contaminant to evaporate and flow out of the flash separator.

Operating the flash separator at a temperature and pressure that causes or promotes decomposition of the emulsion and/or foam.

Applying an electric charge or current to at least a portion of the heating fluid to cause ions of the contaminant species to migrate towards the electrode and thereby be removed.

Removing contaminating particles of solid matter by mechanical separation means including, but not limited to, any one or more of: at least a portion of the heated fluid is centrifuged, sedimentated, clarified, filtered, and hydrocracked. If desired, chemicals may be added which cause the fine particles of the contaminant to flocculate or agglomerate into larger agglomerates which may be removed by mechanical separation means.

Removing acetate salts and possibly other organic salt contaminants by mixing an acidic solution (e.g. dilute hydrochloric acid) with at least a portion of the heating fluid to cause a reaction that converts at least a portion of the organic salts to volatile organic acids, which can then be evaporated and removed.

Stage A plus stage C configuration

FIG. 3 shows a non-limiting example of a system including a stage A (concentration process) plus stage C (flash heated fluid process) configuration. The feed stream 10 comprises water, water-soluble process liquids that are less volatile than water, dissolved contaminants including monovalent salts (e.g., sodium chloride), divalent ions (e.g., calcium and magnesium), and organic salts (e.g., acetate salts), and liquid contaminants. Feed stream 10 enters distillation zone 11. The water vapor leaves the top of distillation zone 11 and condenses in condenser 13. The uncondensed gases leave the condenser 13 in stream 15. The bottoms liquid from distillation zone 11 flows to reboiler 12 where it is heated to evaporate water, thereby producing a concentrated process liquid. Steam from reboiler 12 flows back to distillation zone 11. Heat is provided to reboiler 12 (e.g., via steam or hot oil in the submerged tube bundle) to vaporize enough water to produce a desired degree of process liquid concentration in the output stream 20 exiting reboiler 12.

Stream 20 comprises the concentrated process liquid produced in stage a and flowing into stage C and is thus a non-limiting example referred to herein as the "stage a output stream". The phase a output stream does not have to flow immediately from phase a to phase C. It may for example flow into the intermediate tank and from there or from any other suitable location into stage C. Those skilled in the art will recognize that the stage a process (which includes the steps that result in the production of the output stream 20 as shown in fig. 3) is but one non-limiting example of a few possible alternative designs of a system that can remove water from a feed stream to concentrate a process liquid solution. For example, there are many on-the-fly glycol concentration systems at many oil and gas production points worldwide, including a vessel in which there is a submerged tube bundle for performing the reboiler function and a thermal still (still) that is still directly flanged to the upper vapor-filled portion of the vessel, containing trays or structured or random packing for performing distillation.

Alternative means of separating water from an aqueous process liquid solution to produce a concentrated process liquid may also be feasible (e.g. molecular sieves, membranes).

Stage a concentration includes a process in which water is removed from the feed stream prior to stage B or stage C and by any feasible means to produce an output stream of concentrated process liquid.

In one or more embodiments, stage a is operated at atmospheric pressure, while in other embodiments stage a is operated under vacuum. Operating under vacuum lowers the boiling point of water and enables stage a to achieve higher process liquid concentrations at lower temperatures.

Referring to fig. 3, stream 20 enters flash separator 21 through one or more inlets. The flash separator 21 is a flash heated fluid separation vessel that contains a liquid pool into which separated liquid and solid material is collected. The separated vapor can flow out of the upper portion of flash separator 21. The liquid pool in the flash separator 21 contains a heating fluid consisting of liquid components having a lower volatility than the process liquid. A pump 23 pumps the heated fluid out of the flash separator 21 and through a heater 24 to produce a stream 25 of heated fluid. Stream 25 and stream 20 are in direct contact with each other upstream of flash separator 21 and/or at one or more locations within flash separator 21. For example, there may be one or more mixing zones or chambers upstream of flash separator 21 into which streams 20 and 25, or portions thereof, flow and mix with each other, and/or there may be multiple inlets for streams 20 and 25 into flash separator 21, such that the two streams, or portions thereof, mix with each other inside flash separator 21. Alternatively, stream 20, or a portion thereof, may enter a liquid pool in flash separator 21 and contact the heated heating fluid therein.

Adding sufficient heat to the heating fluid in heater 24 and/or by heating the heating fluid in flash separator 21 causes at least a portion of the process liquid in stream 20 to evaporate as stream 20 contacts the heated heating fluid.

In embodiments, all of the process liquid in stream 20, except for at least a negligible residue, is vaporized due to contact between stream 20 and the heated heating fluid.

In one embodiment, more than 95% or preferably more than 98% of the process liquid in stream 20 evaporates due to contact between stream 20 and the heated heating fluid.

Further description of this configuration of the present disclosure is given under the heading "separation and removal of contaminants", "heating fluid composition" and "heating fluid treatment means" above.

In the stage a plus stage C configuration of the present disclosure, the flow rate of the stream entering the flash heating fluid process (i.e., stream 20) may be significantly less than the flow rate of the feed stream 10. This is possible because the feed stream 10 first enters stage a, which preferably removes most of the water, thereby significantly reducing the amount of liquid entering the flash heating fluid process. This can significantly reduce the amount of heat required to drive the flash heating fluid process when compared to the prior art (e.g., US8,652,304 and US10,328,360). The heat stored in stage C is approximately equal to the heat applied in stage a. However, the application of this heat in stage a enables the use of simpler, lower cost equipment, as in stage a water can be evaporated at a lower temperature than is required to evaporate the less volatile process liquid. Furthermore, the heat of vaporization of water is significantly greater than that of many process liquids, which is another reason for applying this heat using the lower cost stage a process.

In a non-limiting example of MEG recovery, there is a need for treatment at 10m ³ An existing gas production point for salt-containing rich MEG lean solution (i.e. feed stream) flowing at a flow rate of/h or higher. Consider a phase a plus phase C configuration in which the present disclosure is configured to handle MEG concentrations of 30% and at 10m ³ And/h into the feed stream 10 of stage A. Stage a will be carried out by evaporation (in reboiler 12) and removal (in stream 14) of about 6.6m ³ The MEG solution was re-concentrated to 90% strength with water/h. This requires about 4.5MW of heat to be provided by reboiler 12. This results in about 3.4m ³ /h(10m ³ /h minus 6.6m ³ The flow of 90% of the concentrated MEG of/h) enters stage C via stream 20, which corresponds to a flow rate of 66% less than the feed stream 10. Stream 20 also contains salts and other non-vaporized contaminants initially in feed stream 10.

In this configuration, the stage C flash heating fluid process requires only about 1.2MW of heat to evaporate MEG and water from stream 20, thereby precipitating and removing monovalent salts (e.g., sodium chloride) and divalent ions (e.g., calcium, magnesium) initially in stream 10. In embodiments, all MEG in stage C vapor stream 20 except at least a negligible residue.

For the above embodiment, the total heat required to fully vaporize the water and MEG in stream 10 is about 5.7MW, but only 1.2MW of this heat is required for stage C because 4.5MW is provided in stage a. By comparing prior art versions of flash heating fluid processes (e.g., US8,652,304 or US10,328,360), 5.7MW of heat is required to remove similar amounts of salt.

The significantly lower heat demand in the stage C flash heating fluid process results in a corresponding reduction in the amount of heating fluid required compared to the prior art, which reduces the cost of purchasing and maintaining or upgrading the heating fluid pool and enables smaller and less costly equipment (e.g., pumps, valves, pipes and heaters) to be used to pump and heat the heating fluid.

The power requirements are also reduced. The primary consumption of electrical power in the stage a plus stage C configuration shown in fig. 3 is pump 23, pump 23 pumping heating fluid through heater 24 in the pump loop. The flow rate of such pumped streams varies with the amount of heat required to drive the evaporation process, which, as noted above, is much lower in the present disclosure than in the prior art (i.e., about 80% lower in the example described above). The prior art does not have phase a and therefore the electrical load in phase a needs to be considered. However, in stage a, the heating process (e.g., the submerged tube bundle in reboiler 12) is simpler than in stage C, and there is typically no pump around loop, and therefore no significant power consumption. Thus, the stage a plus stage C configuration of the present disclosure provides a means of significantly reducing overall power consumption.

Stage B plus stage C configuration

Fig. 4 shows a non-limiting example of a stage B (flash process liquid process) plus stage C (flash heating fluid process) configuration.

The feed stream 10 comprises water, water-soluble process liquids that are less volatile than water, dissolved contaminants including monovalent salts (e.g., sodium chloride), divalent ions (e.g., calcium and magnesium), and organic salts (e.g., acetate salts), and liquid contaminants.

Stream 10 enters stage B separation vessel 51 through one or more inlets. The liquid pool in the lower part of the stage B separation vessel 51 contains liquid consisting of concentrated process liquid. The stage B pump 53 withdraws concentrated process liquid from the liquid pool in the stage B separation vessel 51 and pumps it through the stage B heater 54 to produce a heated stream 55 of concentrated process liquid. Stream 55 and stream 10 are in direct contact with each other upstream of stage B separation vessel 51 and/or at one or more locations within stage B separation vessel 51. For example, there may be one or more mixing zones or chambers upstream of stage B separation vessel 51 into which streams 10 and 55 or portions thereof flow and mix with each other, and/or there may be multiple inlets for both streams 10 and 55 to enter stage B separation vessel 51, such that the two streams or portions thereof mix with each other inside stage B separation vessel 51, and/or stream 10 or portions thereof may enter the liquid pool in stage B separation vessel 55 and contact the heated concentrated process liquid therein.

Sufficient heat is added to the concentrated process liquid stream in stage B heater 54 to cause at least a portion of the water and process liquid in stream 10 to evaporate as stream 10 and stream 55 contact one another.

Vapor comprising vaporized process liquid and water, and optionally liquid contaminants, exits stage B separation vessel 51 and flows via stream 56 into stage B distillation system 57. Those skilled in the art will recognize that the separation and condensation of vapor components can be accomplished using standard methods (e.g., vacuum distillation). The stage B distillation system 57 includes equipment that enables the stage B separation vessel 51 to operate at a sub-atmospheric pressure. Stream 58 contains non-condensing gases and vapors that are subsequently removed. Stream 59 is the output product stream that may comprise salt and other contaminant depleted process liquids. Stream 60 is optional and may contain condensed liquid contaminants (if present) that are subsequently removed.

The second output stream 70 may convey contaminated process liquid to stage C, thereby removing salts and possibly other contaminants from stage B and into stage C, where they will be separated and removed. As used herein, the term "stage B to C stream" refers to a stream (e.g., stream 70) that conveys a mixture comprising at least a portion of contaminants and at least a portion of non-vaporized process liquid from stage B to stage C.

Stage B is significantly different from several versions of the flash process liquid process of the prior art. In said prior art (US 6,685,802 and US8,728,321) the process proceeds beyond the extent of precipitation of salts and other dissolved substances and starts to accumulate in a large pool of concentrated process liquid in the separation vessel. In MEG recovery systems, the rate of salt accumulation can be large (e.g., over 5 tons/day). Without further steps, the accumulation of precipitated salts can quickly become intolerable and cause shutdown of the recovery system. For this reason, the prior art relies on mechanical means to separate a large amount of precipitated solid matter from concentrated process liquids (e.g. settling tanks, clarifiers, filters, centrifuges, salt downcomers).

Conversely, in this stage B plus stage C configuration of the present disclosure, precipitation of salts is controlled such that there is no excessive accumulation of precipitated solid matter in stage B. Thus, the present disclosure enables the elimination of mechanical separation systems from flash process liquid processes, thereby significantly reducing complexity and cost. The equipment avoided (which may include centrifuges, settling tanks, filters, salt tanks, downcomers, etc.) is typically large, complex, heavy, expensive to purchase, operate, and maintain. The elimination of such devices results in a simpler, safer system that can be constructed and operated at lower cost. The salt must be removed but this is accomplished primarily in a phase C flash heating fluid process using simpler, less costly non-mechanical means, which reduces the risk of process liquid loss and environmental hazards.

In a non-limiting example of MEG recovery, sodium chloride, potassium chloride and optionally other monovalent salts are precipitated in the liquid pond of stage B separation vessel 51 and form a slurry with the concentrated MEG. However, divalent ions remain dissolved in the concentrated MEG, avoiding the risk of divalent ions binding to MEG to form unwanted complexes (e.g. calcium-MEG-chloride, magnesium-MEG-chloride), which is known to the person skilled in the art to be particularly problematic in MEG recovery systems. This divalent ion problem is discussed in reference 1. The present disclosure avoids the divalent ion risk by ensuring that there is sufficient flow of the mixture of salt and process liquid from stage B into stage C via stream 70. Fig. 4 shows an embodiment in which stream 70 is part of the heating output from stage B heater 54. Those skilled in the art will recognize that stream 70 may alternatively be withdrawn from a location upstream of stage B heater 54 or from a tank that has collected salt and concentrated process liquid from the stage B separation vessel or from another equivalent location.

The present disclosure includes directly controlling the flow rate in stream 70 therebyMeans to prevent unwanted accumulation of divalent ions in stage B. This feature adds considerable value to the present disclosure that can be illustrated by considering a non-limiting example of MEG recovery. Taking into account the same situation as described above, i.e. 10m containing 30% MEG ³ And/h feed stream 10. The feed stream also contains 20g/ltr of monovalent salt and 1g/ltr of divalent ion salt. These salt concentrations are typical in many gas production sites worldwide for brine formation water produced with natural gas.

The steady flow under the above conditions results in a daily monovalent salt load of about 4,800kg/d and a divalent ion salt load of about 250 kg/d. For these conditions, the flow rate of stream 70 may be adjusted to maintain about 1m ³ Flow rate/h. This flow may appear small but it is high enough to ensure that the concentration of precipitated monovalent salt in the stage B separation vessel 51 remains below about 7vol%. This is easily tolerated considering that many existing MEG recovery systems are conventionally operated with MEG salt slurries having higher salt concentrations. This flow is also sufficient to ensure that divalent ions (especially calcium) remain dissolved at a concentration of less than about 4 g/ltr. This concentration of divalent ions in the concentrated MEG pool in stage B separation vessel 51 is easily tolerated and well below the recommended limit of 10g/ltr set forth by experienced MEG recovery system designers and operators (reference 1).

Stream 70 enters flash separator 21 through one or more inlets. The liquid pool in the lower part of the flash separator 21 contains a heating fluid consisting of liquid components having a lower volatility than the process liquid. A pump 23 pumps the heated fluid out of the flash separator 21 and through a heater 24 to produce a stream 25 of heated fluid. Stream 25 and stream 70 are in direct contact with each other upstream of flash separator 21 and/or at one or more locations within flash separator 21. For example, there may be one or more mixing zones or mixing chambers upstream of flash separator 21, both streams 70 and 25, or portions thereof, flowing into the mixing zones or mixing chambers and mixing with each other, and/or there may be multiple inlets for both streams 70 and 25 to enter flash separator 21, such that the two streams, or portions thereof, mix with each other within flash separator 21. Alternatively, stream 70, or a portion thereof, may enter the liquid pool in flash separator 21 and contact the heated heating fluid therein.

Adding sufficient heat to the heating fluid in heater 24 and/or by heating the heating fluid in flash separator 21 causes at least a portion of the process liquid in stream 70 to evaporate as stream 70 contacts the heated heating fluid.

In an embodiment, all of the process liquid in stream 70, except for at least a negligible residue, is vaporized due to contact between stream 70 and the heated heating fluid.

In one embodiment, more than 95%, or preferably more than 98% of the process liquid in stream 70 evaporates due to contact between stream 70 and the heated heating fluid.

The phase C system in the phase B plus phase C configuration is more compact and consumes even less energy when compared to the phase C system in the phase a plus phase C configuration. Consider the same MEG recovery scheme as described previously, i.e. stage B plus stage C configured to handle 10m MEG concentration of 30% ³ And/h feed stream. Stage B includes flashing the process liquid process to produce an output product stream 59 comprising salt-depleted (or salt-free) concentrated MEG. This requires about 5.4MW of heat, which may be provided by stage B heater 54.

Stream 70 is at about 1.0m ³ The flow rate/h carries salts, possibly other contaminants and concentrated MEG from stage B to stage C, which is 10m higher than ³ The flow rate of feed stream 10 per h was 90% lower. Because stage C can be operated at such low flow rates, the amount of heat required in stage C is only about 0.3MW. Stage C precipitates and removes monovalent salts (e.g., sodium chloride) and divalent ions (e.g., calcium and magnesium) originally present in stream 10. In embodiments, all but at least a negligible residue of MEG in stage C vapor stream 70.

For the above embodiments, the total heat required to fully vaporize the water and MEG in stream 10 is about 5.7MW, which is about the total heat that needs to be provided when the flash heating fluid only process is applied as described in the prior art (e.g. US8,6752,304 or US10,328,360). By comparison, the flash heating fluid process in this stage B plus stage C configuration only requires 0.3MW of heat.

The significantly lower heat requirement of the stage C flash heating fluid process results in a corresponding reduction in the amount of heating fluid required compared to the prior art, which reduces the cost of purchasing and maintaining or upgrading the heating fluid pool.

The methods of the present disclosure may be used in a batch or continuous manner.

Other embodiments and modifications may be made by one of ordinary skill in the art using the disclosure and teachings herein without undue experimentation. All such embodiments and variations are considered a part of this disclosure. Accordingly, one of ordinary skill in the art will readily appreciate from the disclosure that subsequent modifications, substitutions, and/or variations performing substantially the same function or achieving substantially the same result as embodiments described herein may be utilized in accordance with these related embodiments of the disclosure. Accordingly, the present disclosure is intended to cover within its scope modifications, alternatives, and variations of the methods, articles of manufacture, compositions of matter, compounds, means, methods, and/or steps disclosed herein. The description herein may include subject matter that falls outside the scope of the claimed disclosure. The subject matter is included to aid in understanding the present disclosure.

In this specification, where external sources of information including patent specifications and other documents have been cited, this is generally to provide a context for discussing the features of the disclosure. Unless otherwise indicated, the reference to such sources of information in any jurisdiction should not be construed as an admission that such sources of information are prior art or form part of the common general knowledge in the art.

Reference to the literature

1.“Removal of Divalent Salts from Aqueous MEG Solutions in aMEG Reclamation System”,GPA Europe Annual Conference,Sept 2011,Simon Crawley-Boevey。

Claims

1. A method of removing contaminants, including dissolved contaminants, from a feed stream comprising water and the contaminants and a process liquid that is water soluble and less volatile than water, the method comprising the steps of:

2. A method of removing contaminants, including dissolved contaminants, from a feed stream comprising water and the contaminants and a process liquid that is water soluble and less volatile than water, the method comprising the steps of:

c) Contacting at least a portion of the stage a output stream with at least a portion of the heated heating fluid upstream of and/or at one or more locations within a flash separator to vaporize at least a portion of the process liquid, thereby causing at least a portion of the dissolved contaminants to form precipitated solid matter;

3. A method of removing contaminants, including dissolved contaminants, from a feed stream comprising water and the contaminants and a process liquid that is water soluble and less volatile than water, the method comprising the steps of:

b) Contacting at least a portion of said feed stream with at least a portion of said heated concentrated process liquid upstream of and/or at one or more locations within a stage B separation vessel to vaporize a portion of said process liquid,

thereby producing an unvaporised liquid comprising at least a portion of said dissolved contaminants;

4. The method of claim 2, wherein the concentration process comprises heating the feed stream to a temperature sufficient to vaporize and remove at least a portion of the water.

5. A method according to claim 3, further comprising the step of regulating the flow of the stage B to C streams to limit the accumulation of at least a portion of the dissolved contaminants in the stage B separation vessel.

6. A method according to any one of claims 1 to 3, further comprising the step of applying one or more heating fluid treatment means to decontaminate at least a portion of the heating fluid.

7. A method according to any one of claims 1 to 3, further comprising the step of applying one or more heating fluid treatment means to at least a portion of the heating fluid to adjust one or more properties of the heating fluid, including but not limited to density, vapor pressure, viscosity, thermal stability, pH, solubility, heat capacity, thermal conductivity, corrosiveness, toxicity, and flammability.

8. The method of claim 6, wherein the one or more heating fluid treatment means comprises adding one or more substances and mixing the added substances with at least a portion of the heating fluid to achieve any one or more of the following effects: causing a reaction with carbonate and/or bicarbonate contaminants to produce water and/or carbon dioxide; reducing the oxygen content of the heating fluid; removing and/or dissolving and/or disrupting asphaltenes, resins, gums and/or slurries; preventing or inhibiting the formation of scale or scale deposits on the metal surface, or enabling the removal of scale or scale deposits on the metal surface; decomposing, compacting or inhibiting the formation of the emulsion or foam; lowering the cloud point and/or freezing point of the liquid contaminant; neutralizing the acid and/or increasing the alkalinity and/or inhibiting corrosion; and reacting with the dissolved contaminants and causing precipitation of solid matter that can be removed by mechanical separation means.

9. The method of claim 6, wherein the one or more heating fluid treatment means comprises heating at least a portion of the heating fluid to evaporate and thereby remove at least a portion of the liquid contaminant.

10. The method of claim 6, wherein the one or more heating fluid treatment means comprises removing contaminating particles of solid matter from at least a portion of the heating fluid by mechanical separation means, including but not limited to any one or more of centrifugation, sedimentation, clarification, filtration, and hydrocyclone.

11. The method of claim 6, wherein the one or more heating fluid treatment means comprises adding one or more substances and mixing the added substances with at least a portion of the heating fluid to cause a reaction that converts at least a portion of organic salt contaminants to volatile organic acids and evaporate at least a portion of the volatile organic acids.

12. The method of claim 7, wherein the one or more heating fluid treatment means comprises adding one or more substances and mixing the added substances with at least a portion of the heating fluid to adjust one or more properties of the heating fluid, including but not limited to density, vapor pressure, viscosity, thermal stability, pH, solubility, heat capacity, thermal conductivity, corrosiveness, toxicity, and flammability.

13. A method according to any one of claims 1 to 3, wherein the heating fluid comprises a component that is immiscible with the process liquid.

14. A process according to any one of claims 1 to 3, wherein the salt solvent comprises water.

15. A method according to any one of claims 1 to 3, wherein the process liquid comprises any one or more liquids selected from the group consisting of: monoethylene glycol; diethylene glycol; triethylene glycol; and amines.

16. A method according to any one of claims 1 to 3, wherein the dissolved contaminants comprise any one or more of: monovalent salts including sodium chloride; divalent ions including calcium; and organic acid salts including acetate salts.

17. A method according to any one of claims 1 to 3, wherein all of the process liquid, except at least a negligible residue, in contact with the heated heating fluid is evaporated.

18. A method according to any one of claims 1 to 3, wherein at least a portion of the vaporised process liquid is condensed.

19. A process according to any one of claims 1 to 3, wherein the flash separator is operated at a pressure below atmospheric pressure.

20. A method according to any one of claims 1 to 3, wherein the heating fluid comprises one or more liquid components selected from any of the following groups: an oil; a fatty acid; a heat transfer fluid; a liquid metal; an ionic liquid; and a deep eutectic solvent.

21. A process according to any one of claims 1 to 3, wherein at least a portion of the salt solvent enters the flash separator and is mixed with depleted mixture and dissolves at least a portion of the precipitated solid matter, thereby producing a waste liquid comprising at least a portion of the dissolved contaminants.

22. A process according to any one of claims 1 to 3, wherein at least a portion of the depleted mixture is moved to a solvent washing system, wherein at least a portion of the precipitated solid matter is dissolved in at least a portion of the salt solvent, thereby producing a waste liquid comprising at least a portion of the dissolved contaminants.

23. A method according to any one of claims 1 to 3, wherein at least a portion of the heating fluid is heated by a heating device located inside the flash separator and/or by flowing through a heater located outside the flash separator.