Use of surface-active monomers to mitigate fouling in olefin plants

Abstract

A method of reducing fouling in a water system of an olefins production plant is disclosed. The method includes adding to the water system an effective amount of a surface-active monomer, wherein the surface-active monomer forms a water-soluble adduct by covalently binding to one or more fouling precursor compounds formed during the olefins production process.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 085980, filed September 30, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention generally relates to reducing scaling in olefin production facilities. In particular, this invention may include the use of surfactant monomers to reduce scaling in the water systems of olefin production facilities. Background Technology

[0004] Olefins are common feedstocks for a variety of petrochemicals. One method for producing olefins is through steam cracking of hydrocarbon feedstocks such as naphtha, liquefied petroleum gas (LPG), ethane, propane, and / or butane. In steam cracking (pyrolysis) processes, hydrocarbons are superheated to temperatures of 750°C to 950°C in a reactor. In the cracking process, a dilution steam generator (DSG) supplies dilution steam to the reactor to reduce the partial pressure of the hydrocarbons. The hot hydrocarbons are then rapidly cooled (quenched) to stop the reaction after a certain time point, thereby optimizing the yield of cracking products. In many processes, water in a quench tower (QWT) is used to quench the superheated gas. Hot cracked gas (containing olefins) flows into the bottom of the quench tower while water is sprayed onto the top. As the water in the quench tower descends, it comes into contact with the upward-flowing hot cracked gas, thus cooling the hot cracked gas (containing olefins) and the dilution steam.

[0005] Because the hot cracked gases in the quench tower are in direct contact with the condensate of the dilution vapors, the water flowing out of the quench tower mixes with the condensed hydrocarbons (e.g., cracked gasoline). In the quench tower, the cracked gasoline and water mix and can form an emulsion. Therefore, the quench tower effluent flowing from the bottom of the quench tower can contain an emulsion with a hydrocarbon phase dispersed in the aqueous phase. Hydrocarbon-in-water emulsions are particularly difficult to break down. In other words, such emulsions are stable because once formed, the water is not easily separated from the cracked gasoline.

[0006] To facilitate the separation of water from the cracked gasoline, the quench tower effluent flows from the quench tower to the quench water settling tank (QWS). In the QWS, the quench water effluent (containing the emulsion) settles, and water is drawn out. The water from the QWS is then conveyed to the process water stripping tower (PWS). The process water stripping tower strips water containing acid gases and dissolved hydrocarbons. After stripping in the process water stripping tower, the water is conveyed to the dilution steam generator (as described above). The water used to generate dilution steam for the cracking furnace, which is subsequently condensed in the quench tower, then recycled back to the quench water settling tank, then to the process water stripping tower, and finally back to the dilution steam generator, is called process water and circulates within the quench tower loop. The quench tower, quench water settling tank, process water stripping tower, and dilution steam generator are collectively referred to as the dilution steam system (DSS).

[0007] Because the emulsion in the quench tower tends to stabilize, attempts to separate cracked gasoline from water in the quench tower and / or quench tower settling tank are often ineffective and can be time-consuming and expensive. Therefore, process water can carry significant amounts of scaling precursors, such as reactive monomer species, into the process water stripper, causing scaling in the stripper. The dilution steam generator can also scale due to the carryover of hydrocarbons and subsequent polymerization. The conditions for generating dilution steam are conducive to continuous reactions between scaling precursors. Furthermore, process water exiting from the bottom of the quench tower and the quench water settling tank may contain trace amounts of styrene and styrene oligomers formed in the water due to the long residence time of the water in the quench tower loop. These oligomers can continue to grow under process water stripper conditions and can cause scaling in the dilution steam system.

[0008] Scaling in dilution steam systems, such as at the bottom of process water strippers and in dilution steam generator preheaters, can lead to poor energy efficiency. In the worst-case scenario, excessive scaling can restrict the flow of process water in the quench tower loop, causing equipment shutdown. Many olefin cracking units suffer from poor quench / process water quality due to scaling. Scaling can also occur in other water systems of olefin production plants where free radical reactions are expected. Scaling is one of the key performance issues in the operation of olefin plants.

[0009] Currently, scaling problems are mainly addressed by adding dispersants or polymerization inhibitors and by adding demulsifiers upstream of the dilution steam system. Dispersants disperse scaling precursors through physical adsorption on their surfaces. Physical adsorption or binding typically weakens and breaks down at high temperatures, such as those used to generate dilution steam. This makes it less efficient to reduce scaling in olefin production equipment by adding dispersants. For example, US20140263078A1 teaches methods for reducing scaling in equipment used when recovering hydrocarbons from crude oil or bituminous sands. Scaling can be reduced by dispersing scale, adding slot dispersants, and hydrocarbon dispersants. Summary of the Invention

[0010] The findings offer solutions to some of the aforementioned problems related to scaling in the water systems of olefin production facilities. In particular, these solutions can be based on the use of surfactant monomers to reduce scaling in the dilution steam systems and / or other water systems of olefin production facilities that produce olefins via steam cracking.

[0011] Embodiments of the present invention include a method for reducing scaling in a water system of an olefin production facility. The method may include adding an effective amount of a surfactant monomer to the water system, wherein the surfactant monomer forms a water-soluble adduct by covalently binding with one or more scaling precursor compounds formed during the olefin production process. The covalent bond is significantly stronger than the electrostatic or other non-covalent interactions commonly found in conventional dispersants. The water-soluble adduct is stable at high temperatures, such as at temperatures used to generate dilution steam for hydrocarbon cracking. The olefin production facility can produce olefins through steam cracking of a hydrocarbon feedstock. In some aspects, the hydrocarbon feedstock may be naphtha, LPG, ethane, propane, butane, or any combination thereof. In some aspects, the olefin may be ethylene, propylene, or both. The water system may be a dilution steam system. The water-soluble adduct may be a water-soluble polymer. In some aspects, the amount of scaling precursor compounds present in the water system may be determined, and the weight ratio of the added surfactant monomer to the scaling precursor compounds present in the water system may be from 0.25:1 to 1.2:1. In some aspects, the amount of styrene present in the water system can be determined, and the weight ratio of the added surfactant monomer to the styrene present in the water system can be from 0.25:1 to 1.2:1. In some aspects, the amount of styrene present in the dilution steam system can be determined, and the weight ratio of the added surfactant monomer to the styrene present in the dilution steam system can be from 0.25:1 to 1:1. Non-limiting examples of scaling precursor compounds can be styrene, indene, divinylbenzene, methylstyrene, cyclopentadiene, or any combination thereof. In some aspects, water-soluble adducts can be removed from the water system. In some aspects, water-soluble adducts can be removed from the process water of the dilution steam system by wastewater treatment. Compared with self-polymerization, the surfactant monomers of the present invention can preferentially polymerize with scaling precursors. In some aspects, the surfactant monomers can be maleic acid, maleic anhydride, polyethylene glycol (PEG)-functionalized diamine maleate, PEG-polypropylene glycol (PPG) block copolymer-functionalized diamine maleate, or any combination thereof. In some specific aspects, PEG-functionalized diamine maleate can have the chemical structure of Formula I or Formula II.

[0012]

[0013] In Equation I, n can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10; in Equation II, k and l can be independently 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0014] Surfactant monomers can be added via feed, condensate, direct injection, slipstream, or any combination thereof. As those skilled in the art will understand, surfactant monomers can be added at any point in the water system. In some aspects, surfactant monomers can be added to the process water of a dilution steam system. In some aspects, surfactant monomers can be added to the process water of a dilution steam system in the absence of free gasoline in the process feed. In some specific aspects, surfactant monomers can be added to the process water at the process water stripping tower unit of the dilution steam system. In some specific aspects, surfactant monomers can be added to the process water at the bottom of the process water stripping tower unit.

[0015] The following contains definitions of various terms and phrases used in this specification.

[0016] The term “about” or “approximately” is defined as close to as understood by one of ordinary skill in the art. In one non-limiting embodiment, the term is defined as a deviation of less than 10%, preferably less than 5%, more preferably less than 1%, and most preferably less than 0.5%.

[0017] The terms “weight%”, “volume%”, or “molar%” refer to the percentage of a component’s weight, volume, or number of moles in the total weight, volume, or number of moles of the material containing that component. In a non-limiting example, 10 moles of a component in 100 moles of material is a 10 mol% component.

[0018] The term “basically” and its variations are defined as including a range of deviations within 10%, 5%, 1%, or 0.5%.

[0019] The terms “suppress” or “reduce” or “prevent” or “avoid” or any variations thereof, when used in the claims and / or description, include any measurable reduction or complete suppression in order to achieve the desired result.

[0020] As used in this specification and / or claims, the term "effective" means suitable for achieving the desired, expected, or anticipated result.

[0021] As used herein, the term "effective amount" refers to the amount of surfactant monomers added to the water system of an olefin production facility that is statistically significant and measurably sufficient to reduce scaling in the water system compared to scaling in the water system without the addition or use of surfactant monomers.

[0022] The terms and phrases “scaling precursor,” “scaling precursor compound,” or “scaling material” are used interchangeably herein to refer to reactive monomeric species that can form in a furnace and / or are present in the water system of an olefin production facility that produces olefins by steam cracking. Scaling precursors can polymerize under the process conditions used for olefin production and form water-insoluble polymers. The term “scaling” in the context of a water system refers to the presence of scaling precursor compounds, water-insoluble oligomers, and / or polymers of scaling precursor compounds in the water system.

[0023] As used herein, the term "surfactant monomer" refers to a polymerizable surfactant. A surfactant monomer is a surfactant monomer that can be polymerized.

[0024] Cracked gasoline is a pyrolysis byproduct with a density less than water. Cracked gasoline may include alkanes, aromatics, alkenes and / or dienes, or any combination thereof. In some aspects, cracked gasoline may include C5 to C12 alkanes, aromatics, alkenes and / or dienes, or combinations thereof. In some specific aspects, cracked gasoline may include styrene, isoprene, isoprene, cyclopentadiene, indene, divinylbenzene, methylstyrene, or any combination thereof.

[0025] When used in conjunction with the terms “comprising,” “including,” “containing,” or “having” in the claims or specification, the absence of a number before an element may indicate “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more.”

[0026] The words “contain,” “include,” “have,” or “contain” are inclusive or open-ended and do not exclude other unmentioned elements or methods or steps.

[0027] The method of the present invention may "comprising," "substantially constitute," or "consist of" the specific ingredients, components, compositions, etc., disclosed throughout this specification. In one particular aspect, with respect to "substantially constitute," the essential and novel features of the present invention may include the use of (one or more) surfactant monomers to reduce scaling in the water systems of olefin production facilities.

[0028] As used in this specification and / or claims, the term "primarily" means any value and range greater than 50 wt%, 50 mol%, and 50 vol%. For example, "primarily" can include all values ​​and ranges from 50.1 wt% to 100 wt%, 50.1 mol% to 100 mol%, or 50.1 vol% to 100 vol%.

[0029] Other objects, features, and advantages of the present invention will become apparent from the following accompanying drawings, detailed description, and embodiments. However, it should be understood that while the drawings, detailed description, and embodiments illustrate specific embodiments of the invention, they are given by way of example only and are not intended to be limiting. Furthermore, it is anticipated that variations and modifications that can be made by those skilled in the art within the spirit and scope of the invention will become apparent through these detailed embodiments. In other embodiments, features from a specific embodiment may be combined with features from other embodiments. For example, a feature from one embodiment may be combined with a feature from any other embodiment. In other embodiments, additional features may be added to the specific embodiments described herein. Attached Figure Description

[0030] For a more complete understanding, please refer to the following description in conjunction with the accompanying drawings, in which:

[0031] Figure 1 : Schematic diagram of the method for producing olefins according to the present invention.

[0032] Figure 2 As described in Example 1, polystyrene was deposited on a carbon steel specimen.

[0033] Figure 3 As described in Example 1, the mass of polystyrene deposited on carbon steel specimens with different weight ratios of maleic acid and styrene.

[0034] Figures 4A to 4B As described in Example 1, the weight ratio of maleic acid to styrene is 0.3:1. Figure 4A ) and 1:1 ( Figure 4B The process water scaling simulator (PWFS) water phase.

[0035] Figures 5A to 5B : in high ( Figure 5A ) and low ( Figure 5B At pH 1, a PWFS aqueous phase having the weight ratio of maleic acid to styrene as described in Example 1. Detailed Implementation

[0036] Discoveries have provided solutions to at least some of the aforementioned problems related to scaling in water systems of olefin production facilities. In one aspect, the solution may include adding an effective amount of a surfactant monomer to the water system, wherein the surfactant monomer can form a water-soluble adduct by covalently binding with a scaling precursor compound formed during olefin production. The olefin production facility may be a pyrolysis unit and may produce olefins through steam cracking of a hydrocarbon feedstock. The method of the present invention is capable of reducing scaling in water system components and aqueous solutions, such as in dilution steam systems and process water. The presence of surfactant monomers in the aqueous solution of the water system reduces scaling on surfaces that come into contact with the aqueous solution during olefin production. In some aspects, the surfactant monomers of the present invention can reduce scaling due to the presence of cracked gasoline and / or emulsions containing pyrolysis gas oil and water in the process water of dilution steam systems.

[0037] These and other non-limiting aspects of the invention are discussed in the following sections.

[0038] A. Surfactant monomers

[0039] The surfactant monomer of the present invention may contain polar functional groups. The polar functional groups may be carboxyl, hydroxyl, amide, ester, ether, or any combination thereof. In some aspects, the surfactant monomer may be maleic acid, maleic anhydride, PEG-functionalized diamine maleate, PEG-PPG block copolymer-functionalized diamine maleate, or any combination thereof. In some specific aspects, the average molecular weight of the PEG-functionalized diamine maleate or the PEG-PPG block copolymer-functionalized diamine maleate may be from 200 g / mol to 5000 g / mol, or at least equal to or between any two of the following: 200 g / mol, 400 g / mol, 600 g / mol, 800 g / mol, 1000 g / mol, 1200 g / mol, 1400 g / mol, 1600 g / mol, ... 1800 g / mol, 2000 g / mol, 2200 g / mol, 2400 g / mol, 2600 g / mol, 2800 g / mol, 3000 g / mol, 3200 g / mol, 3400 g / mol, 3600 g / mol, 3800 g / mol, 4000 g / mol, 4200 g / mol, 4400 g / mol, 4600 g / mol, 4800 g / mol, and 5000 g / mol. In some aspects, the PEG-functionalized diamine maleate can be a compound having a chemical structure of Formula I or Formula II. In some aspects, the surfactant monomer can be maleic acid. In some aspects, the surfactant monomer can be maleic anhydride. In some aspects, the surfactant monomer can be PEG-functionalized diamine maleate. In some aspects, the surfactant monomer can be PEG-PPG block copolymer-functionalized diamine maleate. In some aspects, the surfactant monomer can be a combination of the surfactant monomers described herein. Non-restrictive combinations may include:

[0040] Maleic acid, and at least one of maleic anhydride, PEG-functionalized maleic diamine, and PEG-PPG block copolymer-functionalized maleic diamine;

[0041] Maleic anhydride, and at least one of maleic acid, PEG-functionalized maleic acid diamine and PEG-PPG block copolymer-functionalized maleic acid diamine;

[0042] PEG-functionalized maleic diamine, and at least one of maleic acid, maleic anhydride, and PEG-PPG block copolymer-functionalized maleic diamine; and / or

[0043] The PEG-PPG block copolymer-functionalized maleic diamine, and at least one of maleic acid, maleic anhydride and PEG-functionalized maleic diamine.

[0044] The surfactant monomers of this invention can be covalently bonded to scaling precursor compounds formed during olefin production via the vapor cracking of hydrocarbons, and can form water-soluble adducts. In some aspects, the covalent bonds can be carbon-carbon covalent bonds. In some aspects, the water-soluble adducts can be water-soluble polymers. In some aspects, the water-soluble polymers can be polymers formed by polymerizing surfactant monomers and scaling precursor compound monomers, and / or polymers formed by surfactant monomers covalently bonded to polymers of scaling precursor compounds.

[0045] B. Methods for producing olefins

[0046] One aspect of the invention describes a method for producing olefins. The method may include steam cracking of a hydrocarbon feedstock to obtain a cracked gas containing olefins, quenching and purifying the cracked gas to obtain purified olefins, and adding a surfactant monomer to an aqueous system used for quenching and / or purifying the cracked gas. In some aspects, the cracked gas may contain a mixture of olefins. See also... Figure 1This describes a system and method for producing olefins. System 100 may include units such as a steam cracking unit 102, a quench water tower (QWT) 104, a quench water settling tank (QWS) 106, a process water stripping tower (PWS) 108, a dilution steam generator (DSG) 110, and unit 112. In some aspects, unit 112 may include a compressor. Hydrocarbon stream 118 may be fed into steam cracking unit 102 and may be cracked at a temperature of 600°C to 1000°C to form hot cracked gas and cracked gasoline. Cracking in steam cracking unit 102 may be carried out in the presence of dilution steam to reduce hydrocarbon partial pressure. DSG 110 may supply dilution steam to steam cracking unit 102 via stream 120. Stream 122, containing hot cracked gas as well as cracked gasoline and dilution steam, may be fed to the bottom of QWT 104. In QWT 104, stream 122 can contact water stream 124, the hot cracked gas can be cooled, the dilution vapor can be condensed, and at least a portion of the cracked gasoline can be mixed with water to form an emulsion. Stream 126 containing cooled cracked gas can be directed from QWT 104 to unit 112. Stream 128 containing cracked gasoline and a water mixture containing cracked gasoline, water, and / or a cracked gasoline-water emulsion can be fed from QWT 104 to QWS 106. Water and cracked gasoline can be separated in QWS 106. Stream 130 containing cracked gasoline can exit QWS 106. Further processing steps (not shown) can be performed on cracked gasoline stream 130. Stream 132 containing water can be fed from QWS 106 to PWS 108. The water in stream 132 can contain dissolved hydrocarbons and acid gases. At least a portion of the dissolved acid gases and hydrocarbons can be separated from the water in PWS 108 to form stripped water. A stream 134 containing stripped water can be fed from PWS 108 to DSG 110. DSG 110 can generate dilution steam, and a stream 120 containing dilution steam can be fed to steam cracking unit 102. A stream 136 containing a portion of the water in DSG 110 can be sent to a water treatment facility (not shown). The water used to generate dilution steam for steam cracking is referred to as process water, which is then condensed in QWT 104, then recycled to QWS 106, then to PWS 108, and finally returned to DSG 110. QWT 104, QWS 106, PWS 108, and DSG 110 are collectively referred to as the dilution steam system. According to the method of the invention, surfactant monomers can be added to the DSS. In some aspects, surfactant monomers can be fed to PWS 108. In some aspects, surfactant monomer 138 can be fed from the bottom of PWS 108.

[0047] Cooled cracked gas from QWT 104 can be directed to other processing steps, such as compression, purification, drying, and / or separation in Unit 112, to obtain polymer-grade olefins. In some aspects, Unit 112 may include one or more compression units, alkali towers, drying units, cooling chambers, separation columns and units, and / or cooling towers. In some aspects, the compression of the cooled cracked gas may be performed in multiple stages, and the compression unit may include multiple compression units. In some aspects, the separation columns and units may include demethanizing columns, deethanering columns, C2 separators, depropanizing columns, and / or C3 separators. In some aspects, a stream 140 containing polymer-grade ethylene may be obtained from Unit 112. In some aspects, a stream 142 containing polymer-grade propylene may be obtained from Unit 112. In some aspects, both stream 140 containing polymer-grade ethylene and stream 142 containing polymer-grade propylene may be obtained from Unit 112. Other olefins may also be obtained within the context of this invention.

[0048] The addition of surfactant monomers can be carried out by any method known in the art, including non-limiting methods such as spraying, dripping, or casting. The amount of surfactant monomers added can be adjusted according to the hydrocarbon feed, the operating conditions of the olefin equipment, the scale present or formed during olefin production, or any combination thereof. In some aspects, the amount of surfactant monomers added is adjusted based on the turbidity of the process water in the dilution steam system. In some aspects, the amount of scale precursor compounds present in the water system can be determined, and the weight ratio of the added surfactant monomers to the scale precursor compounds present in the water system can be from 0.25:1 to 1.2:1, or at least equal to or between any two of the following: 0.25:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, and 1.2:1. In some aspects, the amount of styrene present in the water system can be determined, and the weight ratio of the added surfactant monomer to the styrene present in the water system can be from 0.25:1 to 1.2:1, or at least equal to or between any two of the following: 0.25:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, and 1.2:1. In some aspects, the amount of styrene present in the steam dilution system can be determined, and the weight ratio of the added surfactant monomer to the styrene present in the steam dilution system can be from 0.25:1 to 1:1, or at least equal to or between any two of the following: 0.25:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, and 1:1. In some aspects, the surfactant monomer can be added by continuous metered feeding. In some respects, the quantitative feed rate can be adjusted based on the concentration of scaling precursors in the water system.

[0049] In some aspects, surfactant monomers can be added to process water in a dilution steam system to achieve a target concentration of about 1 ppm to 1000 ppm, or a target concentration of at least, equal to, or between any two of the following: 1 ppm, 5 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, and 1000 ppm. In some aspects, an aqueous solution and / or dispersion of the surfactant monomer in water is formed, and the solution or dispersion is added to the water system. In some specific aspects, the aqueous solution or dispersion of the surfactant monomer may contain 1% to 70% by weight of the surfactant monomer, or contain at least, equal to, or between any two of the following surfactant monomers: 1% by weight, 2% by weight, 5% by weight, 10% by weight, 20% by weight, 30% by weight, 40% by weight, 50% by weight, 60% by weight, and 70% by weight. In some aspects, the reduction in fouling obtained by the method of the present invention can be demonstrated by the operating changes in pressure in the PWS 108 and / or the logarithmic mean temperature difference (LMTD) of the system's heat exchanger.

[0050] In some respects, water-soluble adducts formed by the addition of surfactant monomers can be removed from the water system. In other respects, water-soluble adducts can be removed from process water by wastewater treatment from stream 136 to water treatment equipment.

[0051] A unit in an olefin production process may include one or more heating and / or cooling devices (e.g., insulation, electric heaters, wall-jacketed heat exchangers) and / or controllers (e.g., computers, flow valves, automatic valves, inlets, outlets, etc.) for controlling the processing temperature and pressure of the reaction and / or process mixture. Single or multiple units may be used. These units may be arranged in parallel and / or in series.

[0052] As part of the disclosure of this invention, specific embodiments are included below. These embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art will readily recognize that parameters can be changed or modified to produce substantially the same results.

[0053] Example

[0054] Example 1

[0055] The efficiency of surface-active monomers in reducing and slowing down scaling.

[0056] The scaling reduction and mitigation effects of surfactant monomers were evaluated using a process water scaling simulator (PWFS). The PWFS consisted of a 500 mL glass container. A total of 400 mL of DM water with a pH of 8–9 (increasing with monoethanolamine) and a conductivity of approximately 215 μS / cm (increasing with NaCl) was introduced into the container. Metal specimens made of carbon steel were suspended in a cooler by immersion in the water. After purging with nitrogen for 15 minutes, purging was stopped, and the surfactant monomer maleic acid was added. The container was then immersed in an oil bath heated to 140 °C. Maleic acid (a hydrolyzed maleic anhydride solution) was added to the aqueous phase. A total of 8 mL of TBC-free styrene was metered in via a filler at a rate of 60 mL / h. This styrene contained 7000 ppm of azobisisobutyronitrile (AIBN), which initiates free radical polymerization. The resulting polystyrene deposited on the specimen. Figure 2 After 1 hour, polymerization was stopped, and the sample was dried overnight at 35°C / vacuum. Once the sample was dry, it was weighed, and the polystyrene mass was compared with other experiments. A lower polystyrene mass indicates effective reduction of scaling. The aqueous phase was also sampled after each experiment. When the weight ratio of maleic acid to styrene was 0.3:1, the polystyrene mass on the sample was halved. Figure 3 At higher weight ratios of maleic acid to styrene, the amount of polystyrene on the sample did not decrease significantly. However, it can be noted that the water quality was greatly affected. In fact, at a weight ratio of maleic acid to styrene of 1:1, the post-polymerization aqueous phase was very clear, meaning that most of the polystyrene formed was soluble in water (Figure 4). This indicates that most of the adducts formed in the process water stripping tower can easily flow to the dilution steam generator and ultimately be discharged to the wastewater treatment equipment.

[0057] The zeta potentials (ζ-potentials) of two different aqueous phases after polymerization were measured. A maleic acid to styrene weight ratio of 0.1:1 resulted in a ζ-potential of -52 mV at pH 8. When the pH of the solution was lowered with acetic acid, the ζ-potential decreased to -11 mV. This confirmed that maleic acid was bound to the polystyrene backbone. A strong effect of pH on the stability of the polymer was also observed. Figure 5A and 5B As the maleic acid groups are protonated, the polymer aggregates at low pH. Similar results were obtained at a maleic acid to styrene weight ratio of 0.01:1.

[0058] Although the embodiments and advantages of this application have been described in detail, it should be understood that various changes, substitutions, and modifications can be made without departing from the embodiments as defined by the appended claims. Furthermore, the scope of this application is not intended to be limited to the specific embodiments of the processes, machines, products, combinations of substances, means, methods, and steps described in the specification. Those skilled in the art will readily appreciate from this disclosure that existing or developing processes, machines, products, combinations of substances, means, methods, or steps that perform substantially the same function or achieve substantially the same results as the corresponding embodiments described herein can be used. Therefore, the appended claims are intended to include such processes, machines, products, combinations of substances, means, methods, or steps within their scope.

[0059] In the context of this invention, at least the following embodiments are described. Embodiment 1 relates to a method for reducing scaling in a water system of an olefin production facility, the method comprising adding an effective amount of a surfactant monomer to the water system, wherein the surfactant monomer forms a water-soluble adduct by covalently binding with one or more scaling precursor compounds formed during the olefin production process. Embodiment 2 relates to the method of Embodiment 1, wherein the olefin production facility produces olefins through steam cracking of a hydrocarbon feed. Embodiment 3 relates to the method of any one of Embodiments 1 or 2, wherein the water system is a dilution steam system. Embodiment 4 relates to the method of any one of Embodiments 1 to 3, wherein the surfactant monomer is added to a process water stripper unit of the dilution steam system. Embodiment 5 relates to the method of Embodiment 4, wherein the surfactant monomer is added to the bottom of the process water stripper unit. Embodiment 6 relates to the method of any one of Embodiments 1 to 5, wherein the water-soluble adduct is a water-soluble polymer. Embodiment 7 relates to the method of any one of Embodiments 1 to 6, wherein the surfactant monomer is maleic acid, maleic anhydride, polyethylene glycol (PEG)-functionalized diamine maleate, PEG-PPG block copolymer-functionalized diamine maleate, or any combination thereof. Embodiment 8 relates to the method of Embodiment 7, wherein the PEG-functionalized maleic anhydride has a chemical structure of Formula I or Formula II. Embodiment 9 relates to the method of any one of Embodiments 1 to 8, wherein one or more scaling precursor compounds are styrene, indene, divinylbenzene, methylstyrene, cyclopentadiene, or any combination thereof. Embodiment 10 relates to the method of any one of Embodiments 1 to 9, further comprising removing the water-soluble adduct from the water system. Embodiment 11 relates to the method of Embodiment 10, wherein the water system is a dilution steam system, and the water-soluble adduct is removed from the process water of the dilution steam system by a sludge treatment. Embodiment 12 relates to the method of any one of Embodiments 1 to 11, further comprising determining the amount of a scaling precursor compound present in the water system, and adding a surfactant monomer to the water system such that the weight ratio of the added surfactant monomer to the scaling precursor compound is 0.25:1 to 1.2:1. Embodiment 13 relates to the method of Embodiment 12, wherein the scaling precursor compound is styrene. Embodiment 14 relates to the method of Embodiment 13, wherein the weight ratio of the added surfactant monomer to styrene is 0.25:1 to 1:1, and wherein the water system is a dilution steam system. Embodiment 15 relates to the method of any one of Embodiments 1 to 14, wherein the surfactant monomer is continuously and quantitatively fed. Embodiment 16 relates to the method of any one of Embodiments 1 to 15, wherein the hydrocarbon feed is naphtha, liquefied petroleum gas, ethane, propane, butane, or any combination thereof. Embodiment 17 relates to the method of Embodiment 4, wherein the surfactant monomer is added to the process water of the process water stripping tower unit.

Claims

1. A method for reducing scaling in the water system of an olefin production facility, the method comprising: Add an effective amount of maleic acid, maleic anhydride, and / or polyethylene glycol (PEG)-functionalized diamine maleate to the water system. Maleic acid, maleic anhydride, and / or polyethylene glycol (PEG) functionalized diamine maleate form a water-soluble adduct by covalently binding with one or more scaling precursor compounds formed during olefin production.

2. The method according to claim 1, wherein the olefin production equipment produces olefins through steam cracking of the hydrocarbon feedstock.

3. The method according to claim 1 or 2, wherein the water system is a dilution steam system.

4. The method according to claim 3, wherein maleic acid, maleic anhydride and / or polyethylene glycol (PEG) functionalized diamine maleate is added to the process water stripping tower unit of the dilution steam system.

5. The method of claim 4, wherein maleic acid, maleic anhydride and / or polyethylene glycol (PEG) functionalized diamine maleate is added to the bottom of the process water stripping tower unit.

6. The method according to claim 1 or 2, wherein the water-soluble adduct is a water-soluble polymer.

7. The method according to claim 1 or 2, wherein maleic acid is added to the water system.

8. The method according to claim 1 or 2, wherein maleic anhydride is added to the water system.

9. The method according to claim 1, wherein the polyethylene glycol (PEG)-functionalized diamine maleate has a chemical structure of formula I or formula II. Where n is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, k and l are independently 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, and k and l are not both 0.

10. The method according to claim 1 or 2, wherein one or more of the scaling precursor compounds are styrene, indene, divinylbenzene, methylstyrene, cyclopentadiene, or any combination thereof.

11. The method according to claim 1 or 2, further comprising removing the water-soluble adduct from the water system.

12. The method of claim 11, wherein the water system is a dilution steam system, and the water-soluble adduct is removed from the process water of the dilution steam system by a sludge treatment.

13. The method according to claim 1 or 2, wherein the weight ratio of the added maleic acid, maleic anhydride and / or polyethylene glycol (PEG) functionalized diamine maleate to the scaling precursor compound is from 0.25:1 to 1.2:

1.

14. The method of claim 13, wherein the scaling precursor compound is styrene.

15. The method according to claim 1 or 2, wherein maleic acid, maleic anhydride and / or polyethylene glycol (PEG) functionalized diamine maleate are continuously and quantitatively fed.

16. The method according to claim 2, wherein the hydrocarbon feedstock is naphtha, liquefied petroleum gas, ethane, propane, butane, or any combination thereof.

17. The method according to claim 3, wherein the hydrocarbon feedstock is naphtha, liquefied petroleum gas, ethane, propane, butane, or any combination thereof.

18. The method according to claim 4, wherein the hydrocarbon feedstock is naphtha, liquefied petroleum gas, ethane, propane, butane, or any combination thereof.

19. The method according to claim 5, wherein the hydrocarbon feedstock is naphtha, liquefied petroleum gas, ethane, propane, butane, or any combination thereof.

20. The method according to claim 6, wherein the hydrocarbon feedstock is naphtha, liquefied petroleum gas, ethane, propane, butane, or any combination thereof.

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