Purification bed systems and methods of use

Abstract

The present disclosure provides methods of directing regeneration gas In some embodiments, a method includes providing a regeneration gas to an open loop regeneration system comprising a purification bed. The regeneration gas includes hydrogen. The regeneration gas is directed to the purification bed. The regeneration gas is directed from the purification bed to a gas unit.

Description

PURIFICATION BED SYSTEMS AND METHODS OF USE CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application number 63 / 612704, filed on December 20, 2023, entitled “Purification Bed Systems and Methods of Use”, the entirety of which is incorporated by reference herein. FIELD

[0002] The present disclosure relates to polyolefin synthesis. BACKGROUND

[0003] Current purification bed regeneration involves high volumes of nitrogen gas, which is routed to flare for disposal due to low levels of residual hydrocarbon in the beds. Unfortunately, nitrogen has a low heating value and does not easily combust, which consequently involves supplementation with natural gas for combustion to occur and leads to generation of combustion products such as CO2. Additionally, due to the use of both nitrogen and natural gas for flare, operating costs increase.

[0004] Conventional approaches to reduce directing nitrogen gas to flare included producing a purification bed regeneration system that included a closed nitrogen recirculation system. The system would utilize high volumes of nitrogen gas that would be recycled and used during subsequent regenerations of purification bed. However, after regeneration across the purification bed, the nitrogen gas would have a high temperature, then involving cooling to be able to handle the nitrogen gas in blowers or mechanical compressors necessary for recirculation, which further increases operating costs.

[0005] Moreover, cooling of the nitrogen gases can result in the condensation of water in the lines, which should be separated out of the lines prior to introduction to a gas-phase polymerization reactor. Additionally, residual re-circulated hydrocarbons may remain in a closed nitrogen recirculation system, which may lead to coking out of the hydrocarbons and subsequent impurities in the lines of the purification bed regeneration system.

[0006] Accordingly, there is a need for an improved purification regeneration bed systems and methods of use thereof, including purification bed systems capable of reducing nitrogen use (for regeneration of the bed system).

[0007] Some references of potential interest in this regard include: US Pat No.8,557,029; US2020 / 0255564; WO2022 / 187791; WO 2023 / 091854; CN106467597; as well as PCT application No. PCT / US2023 / 082941.SUMMARY

[0008] The present disclosure provides methods of directing regeneration gas. The methods include providing a regeneration gas to an open loop regeneration system comprising a purification bed. The regeneration gas includes hydrogen. The regeneration gas is directed to the purification bed. The regeneration gas is directed from the purification bed to a gas unit.

[0009] The present disclosure also provides methods of recycling regeneration gases. The methods include providing a regeneration gas to a closed loop regeneration system. The closed loop regeneration system includes a purification bed. The regeneration gas includes hydrogen. The regeneration gas is directed to the purification bed. A first portion of the regeneration gas is recycled. A second portion of the regeneration gas is directed to a gas unit. BRIEF DESCRIPTION OF THE DRAWINGS illustrate certain aspects of the embodimentsas The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to those skilled in the art and having the benefit of this disclosure.

[0011] FIG. 1 depicts a schematic diagram of an illustrative open-loop purification bed regeneration system, according to embodiments of the present disclosure.

[0012] FIG. 2 depicts a schematic diagram of an illustrative closed-loop purification bed regeneration system, according to embodiments of the present disclosure.

[0013] FIG. 3 depicts a schematic diagram of an illustrative gas phase polymerization system for making polymers according to embodiments of the present disclosure.

[0014] While the disclosed process and system are susceptible to various modifications and alternative forms, the drawing illustrates a specific embodiment herein described in detail by way of example. It should be understood, however, that the description herein of a specific embodiment is not intended to limit the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims. DETAILED DESCRIPTION

[0015] The present disclosure provides improved purification bed systems capable of bed regeneration and reduction in potential generation of combustion products including CO2 in flaring operations by replacing nitrogen, having a low heating value, with a regeneration gas, e.g., hydrogen, having a higher heat capacity than nitrogen. The higher heat capacity of hydrogen may allow for shorter regeneration times due to the lack of hydrogen heating as rapidly as compared to nitrogen. Hydrogen may also allow for reduced generation ofcombustion products such as CO2, as the higher heating value reduces or eliminates the need for supplemental natural gas (or other carbon-containing combustible gas) during flare to promote combustion. Additionally, the use of hydrogen creates products of H2O upon flaring or combusting in a furnace or boiler. The use of hydrogen may also reduce operational expenses as there is a significant increase (e.g., 14x) in the volumetric flow rate of hydrogen gas, as opposed to nitrogen, due to the lower molecular weight of hydrogen compared to nitrogen. Moreover, the use of hydrogen in conjunction with a cracker or polyethylene polymerization reactor may reduce the operational costs of flowing hydrogen through the purification regeneration bed system as hydrogen is readily produced and may be diverted to the purification bed system for regeneration of the bed.

[0016] The regeneration of the purification bed may allow for longer purification of monomers and / or comonomers prior to entering a fluidized bed in a polymerization reaction zone, leading to a reduction of impurities of the polymer product being produced, increased efficiency, and increased production rate of the polymer product in the polymerization reaction zone.

[0017] Illustrative embodiments of the subject matter claimed below will now be disclosed. In the interest of clarity, some features of some actual implementations may not be described in this specification. It will be appreciated that in the development of any such actual embodiments, numerous implementation-specific decisions must be made to achieve the developer’s specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort, even if complex and time-consuming, would be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

[0018] The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, e.g., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein.

[0019] “Regeneration gas,” as used herein, refers to a gas that does not readily undergo chemical reactions with one or more of the reactants, monomers, comonomers, catalysts, or other chemical substance in the purification bed material.

[0020] “Carrier gas,” as used herein refers to a gas that carries at least a nominal amount of a first component, e.g., unreacted components, to a purification bed and / or a gas-phase polymerization reactor. In at least an embodiment, the carrier gas is an inert gas that does notreadily undergo chemical reactions with one or more of the reactants, monomers, comonomers, catalysts, or other chemical substances. In at least an embodiment, the carrier gas is a gas capable of reacting with non-polymer component(s) and / or polymer component(s).

[0021] An “olefin,” alternatively referred to as “alkene,” is a linear, branched, or cyclic compound of carbon and hydrogen having at least one double bond. For purposes of this specification and the claims appended thereto, when a polymer or copolymer is referred to as comprising an olefin, the olefin present in such polymer or copolymer is the polymerized form of the olefin. For example, when a copolymer is said to have an "ethylene" content of 35 wt% to 55 wt%, it is understood that the mer unit in the copolymer is derived from ethylene in the polymerization reaction and said derived units are present at 35 wt% to 55 wt%, based upon the weight of the copolymer. A “polymer” has two or more of the same or different mer units. A “homopolymer” is a polymer having mer units that are the same. A “copolymer” is a polymer having two or more mer units that are different from each other. A “terpolymer” is a polymer having three mer units that are different from each other. Accordingly, the definition of copolymer, as used herein, includes terpolymers and the like. “Different” as used to refer to mer units indicates that the mer units differ from each other by at least one atom or are different isomerically. An "ethylene polymer" or "ethylene copolymer" is a polymer or copolymer comprising at least 50 mol% ethylene derived units, a "propylene polymer" or "propylene copolymer" is a polymer or copolymer comprising at least 50 mol% propylene derived units, and so on.

[0022] -olefin.

[0023] The term “hydrocarbon” means a class of compounds containing hydrogen bound to carbon, and encompasses (i) saturated hydrocarbon compounds, (ii) unsaturated hydrocarbon compounds, and (iii) mixtures of hydrocarbon compounds (saturated and / or unsaturated), including mixtures of hydrocarbon compounds having different values of n. Likewise, a “Cm-Cy” group or compound refers to a group or compound comprising carbon atoms at a total number thereof in the range from m to y. Thus, a C1-C50alkyl group refers to an alkyl group comprising carbon atoms at a total number thereof in the range from 1 to 50.

[0024] “Catalyst,” as used in the method disclosed herein, is the same catalyst throughout the method. That is to say, that the catalyst used for making the first polyethylene will be the same catalyst used for making the second polyethylene, and inherently any transitional polyethylene produced using the gas-phase polymerization process.

[0025] “Induced condensing agent (ICA),” as used herein, means one or more inert condensable fluids which are readily volatile liquid hydrocarbons, which may be selected fromsaturated hydrocarbons containing from 2 to 10 carbon atoms, such as 3 to 10 carbon atoms. Some suitable saturated hydrocarbons are propane, n-butane, isobutane, n-pentane, isopentane, neopentane, n-hexane, isohexane, and other saturated C6 hydrocarbons, n-heptane, n-octane and other saturated C7and C8hydrocarbons or mixtures thereof. A class of exemplary inert condensable hydrocarbons are C5 and C6 saturated hydrocarbons. Another class of exemplary hydrocarbons are C4to C6saturated hydrocarbons. Exemplary hydrocarbons for use as condensable fluids include pentanes, such as isopentane. The condensable fluids may also include polymerizable condensable comonomers such as olefins, diolefins or mixtures thereof including some of the monomers mentioned herein which may be partially or entirely incorporated in the polymer product.

[0026] “Efficiency,” as used herein, refers to the amount of actual polymer product that is produced as a result of the gas-phase polymerization reaction compared to the amount of non- polymer components, e.g., unreacted monomers and unreacted comonomers that remain in the product after polymerization, for example, hydrogenated monomers or comonomers and / or un- polymerized monomers or comonomers. Efficiency may be represented by a w / v % of the total product formed. For example, a polymerization may have an efficiency of 90% where the reactants polymerized to produce 90 w / v% product and 10 w / v% of non-polymer components.

[0027] “Production rate,” as used herein, refers to the amount of polymer product produced per unit time based on the amount of reactant that is introduced into the polymerization reactor, where the unit time may be represented by seconds, minutes, hours, days, or the like.

[0028] “Polyethylene,” as used herein, means an ethylene homopolymer or a copolymer comprising at least 50 wt% ethylene. The terms “polyethylene polymer,” “polyethylene,” “ethylene polymer,” “ethylene copolymer,” and “ethylene-based polymer” have the same meaning as polyethylene copolymer, except where otherwise indicated (e.g., where a polyethylene homopolymer is referred to, this means a polymer formed from ethylene monomer without comonomer units, e.g., 100 wt% ethylene-derived units). Open Loop System Monomer Injection

[0029] FIG. 1. depicts a schematic diagram of an illustrative open-loop purification bed regeneration system 100, according to one or more embodiments. A monomer 102 is introduced to the open-loop purification bed regeneration system 100 via line 104. The monomer 102 may include one or more monomers such as ethylene, propylene, co-monomers, e.g., butene, hexene, or octene, or diluents, e.g., ethane, propane, butane, iso-pentane, hexane, nitrogen, or non-reactive inert gas. The monomer 102 may be impure, e.g., the monomerincludes about 1% v / v to about 10% v / v of impurities, e.g., about 1% v / v to about 3% v / v, about 3% v / v to about 5% v / v, about 5% v / v to about 7% v / v, or about 7% v / v to about 10% v / v. In an embodiment, monomer 102 may include one or more induced condensing agent, continuity additive, static control agent, or a combination thereof, as described below in detail.

[0030] The monomer 102 stream is split into a first purification line 108A and a second purification line 108B. The first purification line 108A transmits the monomer through open valves 106A and 106B towards a first purification bed 110A (such as an adsorption purification bed), where valves 106C, 106I, 106D, and 106E are closed. The second purification line 108B transmits the monomer through open valves 106P and 106Q towards a second purification bed 110B (such as an adsorption purification bed), where valves 106O, 106M, and 106N are closed. The first purification bed 110A and the second purification bed 110B may include a plurality of bed materials, e.g., alumina complexes or molecular sieves. In at least one embodiment, the first purification bed 110A and the second purification bed 110B may independently include two or more different bed materials in the same vessel. The two or more different bed materials may be arranged in a stacked and / or co-mingled arrangement. Without being bound by theory, by using two or more different bed materials varying types of impurities may be removed from the monomer 102 and / or a reduction of total regeneration time may occur. While only two purification beds 110A and 110B are shown in FIG. 1, any number of purification beds may be incorporated into the open-loop purification bed regeneration system 100. For example, the purification bed regeneration system 100 may include about 1 purification bed to 10 or greater purification beds.

[0031] In at least one embodiment, the monomer 102 may exit the first purification bed 110A via line 112A. The monomer 102 may flow through open valves 106Y, 106Z, and 106BB via line 114, where valves 106FF and 106AA are closed. Independently or concurrently, the monomer 102 may exit the second purification bed 110B via line 112B. The monomer 102 may flow through valves 106KK, 106MM, and 106OO via line 114, where valves 106JJ and 106NN are closed. In at least one embodiment, line 114 may split to lines 114A and 114B, where line 114A may flow the purified monomer through valve 106TT to a first reactor 116A, and line 114B may flow the purified monomer through valve 106UU to a second reactor 116B. While only two reactors 116A and 116B are shown in FIG.1, any number of reactors may be incorporated into the open-loop purification bed regeneration system 100. For example, the open-loop purification bed regeneration system 100 may include about 1 reactor to 10 or greater reactors.Purification Bed Regeneration

[0032] In at least one embodiment, after the monomer 102 has been introduced into the reactor, a regeneration process is performed to regenerate the bed material of at least one of the first purification bed 110A or the second purification bed 110B. In an embodiment, the regeneration process may be independently performed to regenerate the bed material of the first purification bed 110A or the second purification bed 110B. For example, one of the purification beds purifying monomer while the other of the purifications beds is undergoing a regeneration process. As one example, a regeneration process may be performed only on the first purification bed 110A. As a further example, a regeneration process may be performed only on the second purification bed 110B. As a further example, the regeneration process may be performed on both the first purification bed 110A and the second purification bed 110B concurrently.

[0033] The regeneration process may include closing valves 106A, 106P, and 106I, to prevent monomer 102 from entering the open-loop purification bed regeneration system 100. A regeneration gas stream 118 may be introduced to the open-loop purification bed regeneration system 100 via line 120. The regeneration gas 118 may include a carrier gas having a heating value, e.g., greater than 300 BTU / SCF. In at least one embodiment, the regeneration gas 118 introduced via line 120 may include nitrogen, argon, helium, or hydrogen. For example, the regeneration gas 118 may include hydrogen. Without being bound by theory, hydrogen may be relatively inert to the one or more bed materials of the purification beds, e.g., alumina complexes or molecular sieves, reducing the likelihood of coking out the hydrocarbons and / or decomposing the hydrocarbons. For example, the bed material may include alumina complexes or molecular sieves. Hydrogen is also stable at regeneration temperatures of about 250 °C to about 320 °C. Additionally, and without being bound by theory, a regeneration gas 118 including hydrogen may allow for a larger volumetric flow rate due to the smaller molecular weight of nitrogen, creating about 14 times more mass flow of hydrogen gas as compared to nitrogen gas. Without being bound by theory, a larger volumetric flow rate may reduce operational expenses as less volume of hydrogen gas may be needed to flow through the purification bed to achieve the same amount of purification. Further, as already noted, the use of hydrogen as a regeneration gas may reduce the generation of CO2 in combustion reactions from flaring, as compared to nitrogen, because when using hydrogen or another high heating value (greater than 300 BTU / SCF), it is unnecessary to supplement the regeneration gas with a combustible gas, e.g., natural gas or other carbon-containing gas such ashydrocarbon gas. Thus, only the hydrogen would be routed to flares, furnaces, boilers, and / or thermal oxidizers, where combustion with oxygen would produce only water vapor.

[0034] In at least one embodiment, the regeneration gas 118 may be introduced via line 120 from an integrated olefins unit capable of producing hydrogen as a byproduct, e.g., a methane reforming unit, which may reduce and / or eliminate the need for introducing supplemental hydrogen gas. In at least one embodiment, the regeneration gas 118 is introduced to line 120 at ambient temperature, e.g., about 10 °C to about 45 °C, such as about 10 °C to about 20 °C, 20 °C to about 22 °C, about 22°C to about 24 °C, or about 23 °C to about 25 °C, or about 25 °C to about 45 °C. In at least one embodiment, the regeneration gas is introduced to line 120 at a pressure of about 1 psig to about 200 psig, e.g., about 1 psig to about 50 psig, about 50 psig to about 100 psig, about 100 psig to about 150 psig, or about 150 psig to about 200 psig. Line 120 may transfer the regeneration gas 118 to a heater 122. The heater 22 may heat the regeneration gas 118 to a temperature of about 100 °C to about 500 °C, e.g., about 100 °C to about 200 °C, about 200 °C to about 300 °C, about 300 °C to about 400 °C, or about 400 °C to about 500 °C.

[0035] In at least one embodiment, the regeneration gas 118 may be directed via line 124 to valve 106QQ, which may allow for the flow of the regeneration gas to the purification bed regeneration system 100. When open, the regeneration gas 118 may flow via line 126 through valves 106U, 106WW, and 106V. Line 126 may split to line 126A and line 126B, where a first portion of the regeneration gas 118 is directed to line 126A and a second portion of the regeneration gas 118 is directed to line 126B. The first portion of the regeneration gas 118 may flow through open valves 106HH and 106FF, via line 128, where valve 106GG is closed. The regeneration gas then enters line 112A and flows through open valve 106Y, where the valve 106Z is closed. The regeneration gas 118 flows through the first purification bed 110A. The regeneration gas 118 flows, via lines 108A, through open valve 106B towards line 130, where valves 106D and 106E are closed. The regeneration gas 118 flows through line 130 and passes through open valve 106C, where valves 106A, 106D, and 106E are closed. The regeneration gas 118 is then directed to a gas unit, e.g., flare, a flare gas recovery unit, a blue hydrogen unit, a thermal oxidizer, a furnace, a boiler, or a combination thereof, via line 132 and line 134. Alternatively, the regeneration gas 118 may flow through open valves 106E and 106G via line 136, where valves 106B and 106D are closed. The regeneration gas 118 exits the purification bed regeneration system 100 via line 138 after flowing through open valves 106R, 106RR, and 106T. In at least one embodiment, line 138 splits to line 138A and 138B to control a pressure of the regeneration gas 118 flowing through line 138 to be about 20 psig to about 40psig, e.g., about 20 psig to about 25 psig, about 25 psig to about 30 psig, about 30 psig to about 35 psig, or about 35 psig to about 40 psig. For example, the regeneration gas may flow through line 138A and exit the purification bed regeneration system 100 via open valves 106R, 106RR, and 106T to de-pressurize the system 100. Alternatively, the regeneration gas 118 may flow through line 138B and exit the purification bed regeneration system 100 via open valves 106S, 106RR, and 106T to increase an amount of pressure in the system by creating a backpressure in the system 100. Alternatively, the regeneration gas 118 may flow through open valve 106H via line 141, where valves 106B, 106D, 106E, and 106F are closed.

[0036] Concurrently, the second portion of the regeneration gas 118 may flow through open valves 106II and 106JJ, via line 148, where valve 106LL is closed. The regeneration gas then enters line 112B and flows through open valve 106KK, where valve 106MM is closed. The regeneration gas 118 flows through the second purification bed 110B. The regeneration gas 118 flows, via lines 108B through open valve106Q towards line 150, where valve 106P is closed. The regeneration gas 118 flows through line 150 and passes through valve 106O. The regeneration gas 118 is then directed to flare via line 152 and line 134. Alternatively, the regeneration gas 118 may flow through open valves 106N and 106K via line 154, where valves 106Q and 106M are closed. The regeneration gas 118 exits the purification bed regeneration system 100 via line 138 after flowing though valves 106R, 106RR, and 106T. In at least one embodiment, line 138 splits to line 138A and 138B to control a pressure of the regeneration gas 118 flowing through line 138 to be about 20 psig to about 40 psig, e.g., about 20 psig to about 25 psig, about 25 psig to about 30 psig, about 30 psig to about 35 psig, or about 35 psig to about 40 psig. For example, the regeneration gas may flow through line 138A and exit the purification bed regeneration system 100 via open valves 106R, 106RR, and 106T, or the regeneration gas 118 may flow through line 138B and exit the purification bed regeneration system 100 via open valves 106S, 106RR, and 106T to regulate an amount of pressure that is directed to a gas unit, e.g., flare, a flare gas recovery unit, a blue hydrogen unit, a thermal oxidizer, a furnace, a boiler, or a combination thereof. Alternatively, the regeneration gas 118 may flow through open valve 106H via line 141, where valves 106B, 106D, 106E, and 106F are closed.

[0037] In at least one embodiment, a portion of the regeneration gas 118 may be sampled for a temperature via line 162, using a sensor 164. The sensor 164 may include a shared indicator capable of analyzing the temperature of the regeneration gas 118 as it exits the heater 122. In at least one embodiment, the sensor 164 may transmit a signal back to the heater 122, via line 166 to adjust one or more temperatures of the heater 122. Without being bound bytheory, heating the regeneration gas 118 to a temperature of about 290 °C to about 320 °C may allow for better purification of regeneration of the reactor bed 116A as the impurities dissociate from the bed material at a higher rate, e.g., about 290 °C to about 300 °C, about 300 °C to about 310 °C, or about 310 °C to about 320 °C.

[0038] In at least one embodiment, the monomer 102 and / or the regeneration gas 118 may flow through lines 112A and / or 128B towards line 178. Line 178 may flow the monomer 102 and / or the regeneration gas 118 through open valve 106CC, 106EE, and / or 106DD towards line 184, where valves 106TT and 106UU are closed. Line 184 may direct the monomer 102 and / or the regeneration gas 118 through open valve 106VV towards a dryer 182. A dryer 182 may include a C4and / or C6dryer. In at least one embodiment, the C4and / or C6dryer may be preloaded with the monomer 102 and / or the regeneration gas 118. For example, the dryer 182 may be preloaded by mixing the monomer 102 with the regeneration gas 118. Alternatively, the monomer 102 and / or the regeneration gas 118 may flow through line 180 towards line 184. Line 184 may direct the monomer 102 and / or the regeneration gas 118 back into line 126 by flowing through open valves 106X, 106SS, and 106W, to be used to preload the purification bed regeneration system 100.

[0039] In at least one embodiment, a first regeneration gas may be used to purge the purification bed regeneration system 100, and a second regeneration gas is used to purge the purification regeneration system. For example, a first regeneration gas, e.g., hydrogen, may be used to purge the purification bed regeneration system 100, and a second regeneration gas, e.g., nitrogen, may then be used to purge the purification bed regeneration system 100. Without being bound by theory, the use of a second regeneration gas that differs from the first regeneration gas may provide additional purification of the purification bed and may reduce impurities from entering the reactor 116, reducing the amount of hydrogen that may proceed to a reactor of a gas-phase polymerization system, and increasing efficiency and production rate of a polymer product. For example, if hydrogen is used as the first regeneration gas, residual CO2may be present in the hydrogen gas, where the residual CO2may be purged from the system and sent to flare using a second regeneration gas of nitrogen.

[0040] In an embodiment, the system 100 may include one or more pressure mechanisms to provide suitable pressures, temperatures, and / or flow rates of the regeneration gas 102 and / or the monomer 102 through the diagram of FIG. 1. For example, the suitable pressures may include a pressure of about 1 psig to about 200 psig, e.g., about 1 psig to about 50 psig, about 50 psig to about 100 psig, about 100 psig to about 150 psig, or about 150 psig to about 200 psig. In an embodiment, the open loop regeneration system may be pressured by flowing themonomer 102 through valve 106I, where orifice 140 may restrict the flow of gas to limit the pressurization rate of the system 100. For example, the suitable temperatures may include about 20 °C to about 350 °C, e.g., about 20 °C to about 100 °C, about 100 °C to about 125 °C, about 125 to about 150 °C, about 150 °C to about 175 °C, about 175 °C to about 200 °C, about 200 °C to about 225 °C, about 225 °C to about 250 °C, or about 250 °C to about 350 °C.

[0041] Without being bound by theory the first reactor bed 110A and / or the second reactor bed 110B may remove about 50% w / w to about 99.9% w / w of the impurities in the monomer 102, e.g., about 50% w / w to about 60% w / w, about 60% w / w to about 70% w / w, about 70% w / w to about 80% w / w, about 80% w / w to about 90% w / w, or about 90% w / w to about 99.9% w / w. While FIG. 1 shows an example of a counter current flow process, a co-current flow process may additionally or alternatively be implemented. Closed Loop System Purification Bed Process

[0042] FIG. 2 depicts a schematic of an illustrative closed loop regeneration system 200 capable of bed regeneration, according to one or more embodiments. A regeneration gas 202 is introduced to the closed loop purification bed regeneration system 200 via line 204. The regeneration gas 202 may include any of the regeneration gas 118 as described above, with reference to FIG. 1. In at least one embodiment, the regeneration gas 202 includes hydrogen gas. Without being bound by theory, a regeneration gas 202 of hydrogen may reduce the production of CO2 because there would be no need to supplement the hydrogen gas with natural gas (or other carbon-containing gas such as hydrocarbon gas) for combustion in the gas unit, e.g., flare, a flare gas recovery unit, a blue hydrogen unit, a thermal oxidizer, a furnace, a boiler, or a combination thereof. Additionally, by using a closed loop regeneration system, a reduction of the amount of hydrogen gas needed may occur, reducing the peak load hydrogen needed to regenerate a purification bed and promoting integration with other facilities to supply the hydrogen gas, e.g., an olefins processing plant.

[0043] The regeneration gas is pumped through a valve 206, which is configured to regulate the amount of regeneration gas 202 that is introduced into the system 200. In at least one embodiment, the valve 206 may provide a flow of about 400 lb / hour to about 20,000 lb / hour to the system 200, e.g., about 400 lb / hour to about 1,000 lb / hour, about 1,000 lb / hour to about 5,000 lb / hour, about 5,000 lb / hour to about 10,000 lb / hour, about 10,000 lb / hour to about 15,000 lb / hour, or about 15,000 lb / hour to about 20,000 lb / hour. The regeneration gas 202 flows to a heater 208, via line 210. For example, the heater may include an electric heater, e.g., resistive heater, and / or steam. The heater 208 may heat the regeneration gas 202 to atemperature of about 140 °C to about 170 °C, e.g., about 140 °C to about 150 °C, about 150 °C to about 160 °C, or about 160 °C to about 170 °C. In at least one embodiment the heater 208 may include a heating element 222. The heating element 222 may include a resistive element capable of heating the regeneration gas 202. In at least one embodiment, the heating element 222 may be coupled to a temperature sensor 224, which analyzes line 226. In at least one embodiment, line 226 may include one or more valves (not shown) to regulate flow of the regeneration gas in line 226. Without being bound by theory the temperature sensor 224 may prevent the heating element 222 from exceeding temperatures that may “coke out” any recirculated residual hydrocarbons, increasing the number of regeneration cycles that may be performed before needing to clean the system 200.

[0044] In at least one embodiment, the regeneration gas 202 may flow from line 210 through open valves 212 and 214 to a cooler 216. The cooler 216 may include any cooler suitable to reduce the temperature of the regeneration gas 202. For example, the cooler 216 may cool the regeneration gas 202 to a temperature of about 290 °C to about 320 °C, e.g., about 290 °C to about 300 °C, about 300 °C to about 310 °C, or about 310 °C to about 320 °C. In at least one embodiment, the cooler 216 may include a water cooler. The water cooler may include a circulating water system. The circulating water system may include an inlet 218 that introduces cold water, e.g., about 20 °C to about 50 °C, e.g., about 20 °C to about 30 °C, about 30 °C to about 40 °C, or about 40 °C to about 50 °C. The circulating water system may include an outlet 220 that removes water from the cooler 216.

[0045] In at least one embodiment, the regeneration gas 202 that has been either heated and / or cooled is transmitted to a purification bed 228 via line 230, where valve 229 is open and valve 252 is closed. The purification bed 228 includes any of the purification bed 110A or 110B, as described above with reference to FIG. 1. The regeneration gas 202 that passes through the purification bed is 228 is then directed to line 232, where valve 231 is open and valve 254 is closed. In at least one embodiment, line 232 may direct the regeneration gas 202 to flare, via line 234. Without being bound by theory, any regeneration gas 202 having a high heating value, e.g., greater than 300 BTU / SCF, and not having combustion products including CO2(e.g., not being a hydrocarbon), may allow for a reduction of generation and / or emission of CO2 because there is a reduced or eliminated supplementation of such regeneration gas 202 with natural gas in the gas unit, e.g., flare, a flare gas recovery unit, a blue hydrogen unit, a thermal oxidizer, a furnace, a boiler, or a combination thereof. Again, as noted before, this overcomes problems associated with using a regeneration gas such as nitrogen, since flaring nitrogen can be required to avoid excessive buildup of the nitrogen in the system, but flaringsuch a relatively low heating value gas requires supplementing the flare with natural gas or another carbon-containing gas such as a hydrocarbon gas (that is, a compound that forms combustion products including CO2).

[0046] In at least one embodiment, line 232 may direct the regeneration gas 202 to a suction cooler 233, via line 238. In at least one embodiment, line 238 may include one or more valves (not shown) to regulate flow of the regeneration gas in line 238. A suction cooler 233 may include any suction cooler suitable to reduce the temperature of the regeneration gas 202. For example, the suction cooler 233 may cool the regeneration gas 202 to a temperature of about 20 °C to about 50 °C, e.g., about 20 °C to about 30 °C, about 30 °C to about 40 °C, or about 40 °C to about 50 °C. The suction cooler 233 may include a suction circulation system. The compressor suction feed system may include a suction inlet 235 that introduces about 20 °C to about 50 °C, e.g., about 20 °C to about 30 °C, about 30 °C to about 40 °C, or about 40 °C to about 50 °C, of a fluid, e.g., water. The compressor suction feed system may include a suction outlet 236 that extracts the fluid from the suction cooler 233 to provide circulation of the fluid through the suction cooler 233.

[0047] In at least one embodiment, the regeneration gas 202 may be chilled and transferred to a collector 240, via line 242. The collector 240 may assist in removing any condensed water or fluid formed as a byproduct of the regeneration gas 202 flowing through the purification bed 228. In at least one embodiment, the collector 240 may include a fluid that captures the one or more condensed fluids, while allowing regeneration gas to rise above the fluid level and exist via line 244. Without being bound by theory, the collector 240 may remove the water or fluid formed as a byproduct, which may increase the longevity of the purification bed 228.

[0048] In an embodiment, the regeneration gas 202 may flow to a compressor 246, via line 244. The compressor 246 can compress the regeneration gas 202 to produce compressed regeneration gas. The compressed regeneration gas can be at a pressure of about 60 psi to about 500 psi, e.g., about 60 psi to about 100 psi, about 100 psi to about 150 psi, about 150 psi to about 200 psi, about 200 psi to about 250 psi, about 250 psi to about 300 psi, about 350 psi to about 400 psi, about 400 psi to about 450 psi, or about 450 psi to about 500 psi. For example, the compressed purge gas can be at a pressure ranging from a low pressure of about 60 psi to about 100 psi to a high pressure of about 100 psi to about 500 psi. Depending, at least in part, on the particular composition of the regeneration gas, the temperature of the compressed regeneration gas can be about 100 °C to about 250 °C, e.g., about 100 °C to about 125 °C, about 125 to about 150 °C, about 150 °C to about 175 °C, about 175 °C to about 200 °C, about 200 °C to about 225 °C, about 225 °C to about 250 °C.

[0049] In at least one embodiment, the compressed regeneration gas may flow through line 248 to line 210 where the compressed regeneration gas may either be heated or cooled by opening valves 212 or 214 and directing the compressed regeneration gas to the heater 208 or the cooler 216. In at least one embodiment, the recycled compressed regeneration gas in line 248 may mix with the regeneration gas 206 to produce a mixture of about 0% to about 20 % of regeneration gas, via line 206, and about 100% to about 80% of recycled compressed regeneration gas, via line 248.

[0050] In another embodiment, the compressed regeneration gas may flow through line 250 such that the compressed regeneration gas may be recycled into the suction cooler 233 to allow operation of the system using varying flow rates, while maintaining a constant volume in the compressor. In at least one embodiment, line 250 may include one or more valves (not shown) to regulate flow of the regeneration gas in line 250. In at least one embodiment a counter current flow process or a co-current flow process may be implemented in system 200. Monomer Injection

[0051] In at least one embodiment, a monomer 102 is introduced to the closed-loop purification bed regeneration system 200 via line 104. The monomer 102 may include any of the monomer 102 as described above, with reference to FIG.1. The monomer may flow through line 104 to the purification bed 228 where valve 252 is open and valve 229 is closed. The monomer may flow through the purification bed 228 and exit via line 114A, where valve 254 is open and valve 231 is closed. Polymerization Processes

[0052] FIG. 3 depicts a flow diagram of an illustrative gas phase polymerization system 300 for making polymers, according to one or more embodiments. The polymerization system 300 includes a reactor 301 in fluid communication with one or more discharge tank(s) 355 (only one shown), compressor(s) 370 (only one shown), heat exchanger(s) 375 (only one shown), purge bin(s) 380 (only one shown), and purge gas recovery unit(s) 382 (only one shown). The polymerization system 300 can also include more than one reactor 301 arranged in series, parallel, or configured independent from the other reactors, each reactor having its own associated discharge tank(s) 355, compressor(s) 370, heat exchanger(s) 375, purge bin(s) 380, or purge gas recovery unit(s) 382 or alternatively, sharing any one or more of the associated discharge tank(s) 355, compressor(s) 370, heat exchanger(s) 375, purge bin(s) 380, or recovery unit(s) 382. For simplicity and ease of description, the polymerization system 300 will be further described in the context of a single reactor train.

[0053] The conditions for polymerizations in the reactor 301 vary depending upon the monomers, catalysts, catalyst systems, and equipment availability. For example, the to about 120°C, and more often about 70°C to about 110°C. Pressures can be within the range of from about 10 kPag to about 10,000 kPag, such as about 500 kPag to about 5,000 kPag, or about 1,000 kPag to about 2,200 kPag, for example.

[0054] The reactor 301 can include a cylindrical section 303, a transition section 305, and a velocity reduction zone or dome 307. The cylindrical section 303 is disposed adjacent the transition section 305. The transition section 305 can expand from a first diameter that corresponds to the diameter of the cylindrical section 303 to a larger diameter adjacent the dome 307. As mentioned above, the location or junction at which the cylindrical section 303 connects to the transition section 305 is referred to as the “neck” or the “reactor neck” 304. The dome 307 has a bulbous shape. One or more cycle fluid lines 315 and vent lines 318 can be in fluid communication with the top head 307. The reactor 301 can be free from the use of stirring and / or wall scraping. The reactor 301 can include the fluidized bed 312 in fluid communication with the top head 307.

[0055] In general, the height to diameter ratio of the cylindrical section 303 can vary in the range of from about 2:1 to about 5:1. The range, of course, can vary to larger or smaller ratios and depends, at least in part, upon the desired production capacity and / or reactor dimensions. The cross-sectional area of the dome 307 is typically within the range of from about 2 to about 3 multiplied by the cross-sectional area of the cylindrical section 303.

[0056] The velocity reduction zone or dome 307 has a larger inner diameter than the fluidized bed 312. As the name suggests, the velocity reduction zone 307 slows the velocity of the gas due to the increased cross-sectional area. This reduction in gas velocity allows particles entrained in the upward moving gas to fall back into the bed, allowing primarily only gas to exit overhead of the reactor 301 through the cycle fluid line 315. The cycle fluid recovered via line 315 can contain less than about 10 wt%, less than about 8 wt%, less than about 5 wt%, less than about 4 wt%, less than about 3 wt%, less than about 2 wt%, less than about 1 wt%, less than about 0.5 wt%, or less than about 0.2 wt% of the particles entrained in fluidized bed 312 over a period of time, e.g., about less than 10 wt% in mass per unit time. The cycle line 315 and the elements therein (compressor 370, heat exchanger 375) can be smooth surfaced and devoid of unnecessary obstructions so as not to impede the flow of cycle fluid or entrained particles.

[0057] The reactor feed via line 114A, providing purified monomer 102 as discussed above with reference to FIG.1, can be introduced to the polymerization system 300 at any point. For example, the reactor feed via line 114A can be introduced to the cylindrical section 303, the transition section 305, the velocity reduction zone 307, to any point within the cycle fluid line 315, or any combination thereof. Figure 3 depicts the reactor feed via line 114A entering the cycle fluid in line 315 after the heat exchanger 375, however the reactor feed via line 114A may be implemented in one or more alternative locations, e.g., before the heat exchanger 375 or after the heat exchanger 375. The catalyst feed via line 313 can be introduced to the polymerization system 300 at any point. For example, the catalyst feed via line 313 is introduced to the fluidized bed 312 within the cylindrical section 303.

[0058] During normal operation, e.g., polymer production, under a given set of operating conditions, the fluidized bed may be maintained at essentially a constant height by withdrawing a portion of the bed as polymer product at the rate of formation of the particulate polymer product. Since the rate of heat generation during polymerization is directly related to the rate of product formation, a temperature rise of the fluid across the reactor (the difference in temperature between reactor feed lines, e.g., 114A, and exit cycle fluid via line 315) is indicative of the rate of particulate polymer formation at a constant fluid velocity if no or negligible vaporizable liquid is present in the inlet fluid.

[0059] The reactor feed line 114A feeds one or more unreacted monomers, unreacted comonomers, induced condensing agents, and / or inerts in a carrier stream. For example, the carrier gas stream that carries the one or more unreacted monomers or unreacted comonomers through the reactor feed line 114A can include ethane, ethylene, or methane, or the like. In an embodiment, the carrier gas may have a temperature, e.g., about 40 °F to about 120 °F, such as about 60 °F to about 100 °F, 80 °F to about 90 °F, or about 40 °F to about 100 °F. In an embodiment, the carrier gas may have a temperature, e.g., about -10 °F to about 40 °F, such as about -10 °F to about 10 °F, 10 °F to about 30 °F, or about 20 °F to about 40 °F.

[0060] The cycle fluid via line 315 can be compressed in the compressor 370 and then passed through the heat exchanger 375 where heat can be exchanged between the cycle fluid and a heat transfer medium. For example, during normal operating conditions a cool or cold heat transfer medium via line 371 can be introduced to the heat exchanger 375 where heat can be transferred from the cycle fluid in line 315 to produce a heated heat transfer medium via line 377 and a cooled cycle fluid via line 315. In another example, during idling of the reactor 301 a warm or hot heat transfer medium via line 371 can be introduced to the heat exchanger 375 where heat can be transferred from the heat transfer medium to the cycle fluid in line 315to produce a cooled heat transfer medium via line 377 and a heated cycle fluid via line 315. The terms “cool heat transfer medium” and “cold heat transfer medium” refer to a heat transfer medium having a temperature less than the fluidized bed 312 within the reactor 301. The terms “warm heat transfer medium” and “hot heat transfer medium” refer to a heat transfer medium having a temperature greater than the fluidized bed 312 within the reactor 301. The heat exchanger 375 can be used to cool the fluidized bed 312 or heat the fluidized bed 312 depending on the particular operating conditions of the polymerization system 300, e.g., reactor start-up, normal operation, idling, and shut down. For example, the heat exchanger 375 can cool the cycle fluid in line 315 to about 100 °C to about 250 °C or lower. Alternatively, the heat exchanger 375 can heat the cycle fluid in line 315 to about 50 °C to about 500 °C , e.g., about 50 °C to about 100 °C, about 100 °C to about 300 °C, or about 300 °C to about 500 °C . Illustrative heat transfer mediums can include water, air, glycols, or the like. It is also possible to locate the compressor 370 downstream from the heat exchanger 375 or at an intermediate point between several heat exchangers 375.

[0061] After cooling, all or a portion of the cycle fluid via line 315 can be returned to the reactor 301. The cooled cycle fluid in line 315 can absorb the heat of reaction generated by the polymerization reaction. The heat transfer medium in line 371 can be used to transfer heat to the cycle fluid in line 315 thereby introducing heat to the polymerization system 300 rather than removing heat therefrom. The heat exchanger 375 can be of any type of heat exchanger. Illustrative heat exchangers can include shell and tube, U-tube, and the like. For example, the heat exchanger 375 can be a shell and tube heat exchanger where the cycle fluid via line 315 can be introduced to the tube side and the heat transfer medium can be introduced to the shell side of the heat exchanger 375. If desired, several heat exchangers can be employed, in series, parallel, or a combination of series and parallel, to lower or increase the temperature of the cycle fluid in stages.

[0062] In some embodiments, the cycle gas via line 315 is returned to the reactor 301 and to the fluidized bed 312 through fluid distributor plate (“plate”) 319. The plate 319 can be installed at the inlet to the reactor 301 to prevent polymer particles from settling out and agglomerating into a solid mass and to prevent liquid accumulation at the bottom of the reactor 301 as well to facilitate easy transitions between processes which contain liquid in the cycle stream 315 and those which do not and vice versa. Although not shown, the cycle gas via line 315 can be introduced into the reactor 301 through a deflector disposed or located intermediate an end of the reactor 301 and the distributor plate 319.

[0063] The catalyst feed via line 313 can be introduced to the fluidized bed 312 within the reactor 301 through one or more injection nozzles (not shown) in fluid communication with line 313. The catalyst feed is introduced as pre-formed particles in one or more liquid or gas carriers (e.g., a catalyst slurry or a particle in a gas). Suitable liquid carriers can include mineral oil and / or liquid or gaseous hydrocarbons including propane, butane, isopentane, hexane, heptane octane, or mixtures thereof. Suitable gas carriers include carrier gases that have a higher heat capacity and / or gas density value, e.g., ethane, ethylene, or a combination thereof, which may provide a higher temperature during the polymerization reaction, which drives the reaction to produce more products at a higher efficiency. For example, the gas carrier of line 313 may include about 0% ethylene and / or ethane to about 100% ethylene and / or ethane, e.g., about 0% v / v to about 20% v / v about 20% v / v to about 40% v / v, about 30% v / v to about 50% v / v, about 40% v / v to about 60% v / v, about 50% v / v to about 70% v / v, about 60% v / v to about 80% v / v, about 70% v / v to about 90% v / v, or about 80% v / v to about 100% v / v. The gas carrier can also be used to carry the catalyst slurry into the reactor. In one example, the catalyst can be a dry powder. In another example, the catalyst can be dissolved in a liquid carrier and introduced to the reactor 301 as a solution. The catalyst via line 313 can be introduced to the reactor 301 at a rate sufficient to maintain polymerization of the monomer(s) therein. Hydrogen can be added via line 314.

[0064] Fluid via line 361 can be separated from a polymer product recovered via line 317 from the reactor 301. The fluid can include unreacted monomer(s), hydrogen, induced condensing agents (ICAs), and / or inerts, such as ethane and / or ethylene. The separation of the fluid can be accomplished when fluid and / or product leave the reactor 301 and enter the product discharge tank 355 (one is shown) through valve 357, which can be, for example, a ball valve designed to have minimum restriction to flow when opened. Positioned above and below the product discharge tank 355 can be conventional valves 359, 367. The valve 367 allows passage of product therethrough. For example, to discharge the polymer product from the reactor 301, valve 357 can be opened while valves 359, 367 are in a closed position. Product and fluid enter the product discharge tank 355. Valve 357 is closed and the product is allowed to settle in the product discharge tank 355. Valve 359 is then opened permitting fluid to flow via line 361 from the product discharge tank 355 to the reactor 301. Valve 359 can then be closed and valve 367 can be opened and any product in the product discharge tank 355 can flow into and be recovered via line 368. Valve 367 can then be closed. The particular timing sequence of the valves 357, 359, and 367 can be accomplished by use of conventional programmable controllers which are well known in the art. The fluid via line 361 can be introduced to thereactor 301. Alternatively, the fluid via line 361 can be introduced to the recycle line 315 (not shown).

[0065] The product via line 368 can be introduced to a purge bin 380 (only one is shown). Alternatively, the product line 368 can be introduced to a plurality of separation units, in series, parallel, or a combination of series and parallel, to further separate gases and / or liquids from the product. The purge bin 380 may receive the product via line 368, in which a plurality of gas stripping streams within the purge bin 380 may direct one or more purge vent streams via line 384 to a purge gas recovery unit 382. For example, the gas may include about 0% ethylene and / or ethane to about 100% ethylene and / or ethane, e.g., about 0 % v / v to about 20 % v / v, about 20% v / v to about 40% v / v, about 30% v / v to about 50% v / v, about 40% v / v to about 60% v / v, about 50% v / v to about 70% v / v, about 60% v / v to about 80% v / v, about 70% v / v to about 90% v / v, or about 80% v / v to about 100% v / v.

[0066] In at least one embodiment, the purge bin 380 includes a region comprising a rotary feeder and a nitrogen gas inlet to prevent one or more hydrocarbons from leaking out of the purge bin. The rotary feeder may direct one or more polymer products from the purge bin to a finishing system (not shown) via a convey line 398.

[0067] The purge vent streams in line 384 can have a concentration of one or more unreacted monomers, unreacted comonomers, impurities, or catalytic components ranging of 500 ppmw or greater. In an embodiment, the purge vent stream in line 384 can be a purge gas that is about 500 ppmw or greater of hydrocarbons. In at least an embodiment, the purge vent stream in line 384 can include about 0 % v / v to about 100 % v / v of one or more unreacted monomers, unreacted comonomers, impurities, or catalytic components, e.g., about 0 % v / v to about 20 % v / v, about 20 % v / v to about 40 % v / v, about 40 % v / v to about 60 % v / v, about 60 % v / v to about 80 % v / v, or about 80 % v / v to about 100 % v / v. For example, the purge vent stream in line 384 can include about 0.004 % v / v to about 0.006 % v / v methane, about 32 % v / v to about 35 % v / v ethene, about 2 % v / v to about 4 % v / v ethane, about 20 % v / v to about 22 % v / v 2-methyl propane, 1.07 x10-11% v / v to about 1.1 x 10-11% v / v of butane, about 12 % v / v to about 14 % v / v 2-methyl butane, about 11 % v / v to about 13 % v / v 1-hexene, about 7 % v / v to about 9 % v / v cis-2-hexene, or about 1.18 x10-17% v / v to about 1.20 x 10-17% v / v of hexane. In at least an embodiment, the purge vent stream in line 384 can include about 3.2 x10-5% v / v to about 3.3 x 10-5% v / v of hydrogen and / or about 4 % v / v to about 6 % v / v of nitrogen.

[0068] The fluid in line 384 may be processed in the purge gas recovery unit 382. The purge gas recovery unit 382 may receive a makeup gas stream from a line 386 to assist in cooling the fluid in line 384. In at least an embodiment, the makeup gas stream from line 386may cool the fluid in line 384 at an interchanger, while concurrently heating the makeup gas stream from line 386. Without being bound by theory, concurrent heating of the makeup gas stream in line 386 and cooling of fluid in line 384 may provide a low energy heating potential to the fluid in line 386 prior to being introduced to the purge bin 380 via line 396. The makeup gas stream may include one or more makeup gases capable of cooling the fluid in line 384. For example, the makeup stream may include a makeup gas such as argon, nitrogen, ethane, ethylene, or methane. For example, the makeup gas may include about 0% ethylene and / or ethane to about 100% ethylene and / or ethane, e.g., about 0% v / v to about 20% v / v, about 10% v / v to about 30% v / v, about 20% v / v to about 40% v / v, about 30% v / v to about 50% v / v, about 40% v / v to about 60% v / v, about 50% v / v to about 70% v / v, about 60% v / v to about 80% v / v, about 70% v / v to about 90% v / v, or about 80% v / v to about 100% v / v. The makeup gas stream may be introduced in the purge gas recovery unit 382 at a lower pressure than the pressure of line 384, such that the drop in pressure results in a further chilling of the fluid in line 384.

[0069] A recovery fluid in line 388 may leave the purge gas recovery unit 382, in which the recovery fluid may be introduced to the reactor 301 via line 388 or may be introduced back to the purge bin 380 via line 396. Alternatively, the recovery fluid of line 388 may be introduced to the recycle line 315 (not shown). The recovery fluid in line 388 may be regulated by one or more valves 390. The one or more valves 390 may limit or restrict a flow of the recovery fluid in line 388 from being introduced to the reactor 301 or the recycle line 315 (not shown).

[0070] The recovery fluid in line 388 may be diverted through an exhaust valve 392. The exhaust valve 392 may open or close an exhaust line 394. The exhaust line 394 may transmit fluid to flare. Alternatively, the exhaust line 394 may be transferred to an olefins processing plant to perform one or more hydrocarbon recovery processes. In at least one embodiment, the recovery fluid in line 394 may have a low nitrogen content, e.g., about 1% v / v to about 10% v / v, e.g., about 1% v / v to about 3% v / v, about 2% v / v to about 4% v / v, about 5% v / v to about 7% v / v, about 6% v / v to about 8 % v / v, about 7% v / v to about 9 % v / v, or about 8% v / v to about 10% v / v.

[0071] One embodiment of a product discharge system employs at least one (parallel) pair of tanks comprising a settling tank and a transfer tank arranged in series and having the separated gas phase returned from the top of the settling tank to a point in the reactor near the top of the fluidized bed.Recovery Unit

[0072] A purge vent stream via line 384 may exit the purge bin 380 and be introduced to the purge gas recovery unit 382. The purge gas recovery unit may include a cooler. The cooler may include a heat exchanger as described above. For example, during normal operating conditions a hot or warm purge vent stream via line 384 may be introduced to the cooler of the recovery unit 382 where heat is transferred from the hot or warm purge vent stream to the cooler via a heat transfer medium. The heat transfer medium may include any suitable material that is capable of absorbing the heat emitted by the hot or warm purge vent stream. For example, and without limitation, the cooler may include a chilled water system capable of absorbing the heat from the purge vent stream. As a further example, the cooler can include a shell and tube exchanger including cooling water as a cooling medium. As a further example, the cooler can include a refrigeration system and / or a plate and frame / spiral system.

[0073] The cooler can produce a purge vent stream in line 384 having a temperature of about 15 °C to about 60 °C, e.g., about 15 °C to about 20 °C, about 20 °C to about 25 °C, about 25 °C to about 30 °C, about 30 °C to about 35 °C, about 35 °C to about 40 °C, about 40 °C to about 45 °C, about 45 °C to about 50 °C, about 50 °C to about 55 °C, or about 55 °C to about 60 °C. Without being bound by theory, when the purge vent stream in line 384 is cooled, the pressure will drop. As such, the purge vent stream in line 384 is sent to a compressor of the recovery unit 382 from the cooler to allow for a controlled temperature increase downstream.

[0074] The compressor can compress the purge vent stream to produce compressed purge gas. The compressed purge gas can be at a pressure of about 60 psi to about 500 psi, e.g., about 60 psi to about 100 psi, about 100 psi to about 150 psi, about 150 psi to about 200 psi, about 200 psi to about 250 psi, about 250 psi to about 300 psi, about 350 psi to about 400 psi, about 400 psi to about 450 psi, or about 450 psi to about 500 psi. For example, the compressed purge gas can be at a pressure ranging from a low pressure of about 60 psi to about 100 psi to a high pressure of about 100 psi to about 500 psi.

[0075] During compression of the purge vent stream within the compressor of the recovery unit the temperature of the purge gas can be maintained below a predetermined maximum temperature. The maximum temperature can be based, at least in part, on the particular make- up or composition of the purge gas product in line 384. For example, if the purge vent stream includes catalytic components such as triethylaluminum (TEAL) and one or more olefins, the predetermined maximum temperature could be about 140 °C, because if the purge gas product is heated to higher temperatures, polymerization could be initiated within the compressor. Depending, at least in part, on the particular composition of the purge vent stream, e.g., thepresence of catalytic components and / or the concentration of catalytic components in the purge vent stream, the temperature of the purge vent stream can be maintained below about 100 °C to about 250 °C, e.g., about 100 °C to about 125 °C, about 125 to about 150 °C, about 150 °C to about 175 °C, about 175 °C to about 200 °C, about 200 °C to about 225 °C, about 225 °C to about 250 °C during compression.

[0076] The compressor can compress the purge vent stream in line 384 at any desired pressure ratio, e.g., any desired ratio of the pressure of the purge vent stream introduced to the compressed compared to the pressure of the compressed purge gas recovered from the compressor. For example, a purge vent stream in line 384 may have a pressure of about 110 kPa in line 384 entering the compressor of the recovery unit 382, in which the compressed purge gas exiting the compressor of the recovery unit 382 may have a pressure of about 385 kPa, which would be a ratio of about 1:3.5. The compressor of the recovery unit 382 cancompress the purge vent stream at a pressure ratio ranging from about 1:2 to about 1:10 ̧e.g.,about 1:2 to about 1:4, about 1:3 to about 1:5, about 1:4 to about 1:6, about 1:5 to about 1:7, about 1:6 to about 1:8, about 1:7 to about 1:9, or about 1:8 to about 1:10. Without being bound by theory, the pressure ratio within the compressor of the recovery unit 382 can be based, at least in part, on the desired pressure of the compressed purge gas, the type of compressor, the desired predetermined maximum temperature of the compressed purge gas after compression, or any combination thereof.

[0077] The compressed purge gas may have a temperature that is based on the amount of compression in the compressor and the temperature of the purge vent stream in line 384 after exiting the cooler of the recovery unit 382. As the purge vent stream in line 384 is compressed the partial pressure of the unreacted monomers, unreacted comonomers, impurities, and catalytic components increases, such as hydrogenated monomers or comonomers and / or un- polymerized monomers or comonomers. As such, the potential for polymerization initiating increases, requiring control of the maximum temperature of the compressed purge gas. By controlling the pressure ratio of the compressor, the temperature of the compressed purge gas may be controlled, in which a temperature that is below the maximum temperature may be produced, limiting polymerization in the compressor of the recovery unit 382.

[0078] The compressed purge gas is introduced to an interchanger in the recovery unit 382. The interchanger may direct the compressed purge gas to a water cooler and a condenser to condense liquid hydrocarbons. The interchanger may include a series of diverters or valves capable of directing or redirecting the compressed purge gas. In at least one embodiment, the interchanger may receive compressed gas, where the compressed gas is about 90 °C to about150 °C, at about 120 psi to about 180 psi, and receive the gas product, where the gas product in line 216 is about -20 °C to about -30 °C, at about 120 psi to about 180 psi, in which the compressed gas may be cooled while concurrently warming the gas product. Without being bound by theory, the interchanger may be used to recover one or more additional hydrocarbons using a water cooler and / or a condenser, as described below, without requiring all of the purge gas to be sent to flare.

[0079] The water cooler can reduce the temperature of the compressed purge gas from a temperature range of about 100 °C to about 250 °C to a temperature range of about 20 °C to about 50 °C, e.g., about 20 °C to about 30 °C, about 30 °C to about 40 °C, or about 40 °C to about 50 °C.

[0080] The cooled compressed purge gas is introduced to one or more condensers of the recovery unit 382 to produce a gas product and a condensed product. The condenser 214 can reduce the temperature of the compressed purge gas from a temperature range of about 20 °C to about 50 °C to a temperature range of about -30 °C to about 0 °C, e.g., about -30 °C to about -20 °C, about -20 °C to about -10 °C, or about -10 °C to about 0 °C. In at least an embodiment, the condenser 214 can reduce the temperature of the compressed purge gas using a refrigeration system or integrated letdown system.

[0081] The condensers can be or include any system, device, or combination of systems and / or devices suitable for separating gas from liquids. For example, the condensers can be or include one or more flash tanks, distillation columns, fractionation columns, divided wall columns, or any combination thereof. The condensers can contain one or more internal structures including trays, random packing elements such as rings or saddles, structured packing, or any combination thereof. The condensers can be or include an open column without internals. The condensers can be a partially empty column containing one or more internal structures. Without being bound by theory, due to the use of ethane, a distillation column, fractionation column, or condenser may be used to separate hydrocarbons without the need for a cryogenic distillation, pressure swing adsorption, or membrane technology which can reduce processing costs during gas-phase polymerization reactions.

[0082] The gas product of the condenser is reintroduced to the interchanger, which may recycle a gas for the gas-phase polymerization reaction. The gas product in line 216 can be at a temperature of about -30 °C to about -10 °C, e.g., about -30 °C to about -25 °C, about -25 °C to about -20 °C, about -20 °C to about -15 °C, or about -15 °C to about -10 °C.

[0083] The condensed product of the condenser can include one or more of the heavier hydrocarbons contained in the purge gas vent stream in line 384. For example, when the purgegas vent stream in line 384 contains ethylene and one or more comonomers such as butene, hexene, and / or octene, the major component(s) of the condensed fluids of the condenser can include the one or more comonomers. As used herein, the term “major component” refers to a component of composition that is present in the composition in more than trace amounts, e.g., greater than 100 parts per million (ppm). When the purge gas vent stream in line 384 contains ethylene and one or more inert hydrocarbons, e.g., solvents, diluents, or induced condensing agents (ICAS), such as propane, butane, pentane, hexane, and / or octane, the major component(s) of the condensed fluids of the condenser can be the inert hydrocarbons. In another example, when the purge gas vent stream in line 384 contains ethylene, one or more comonomers, and one or more inert hydrocarbons, the major component(s) of the condensed fluids of the condenser can be the comonomer(s) and the inert hydrocarbons.

[0084] Depending, at least in part, on the particular composition of the purge gas vent stream in line 384, the composition of the condensed fluids in the condenser can widely vary. When the purge gas product contains inert hydrocarbons, e.g., iso-pentane, the concentration of the inert hydrocarbons can range from a low of about 20 wt %, about 25 wt %, or about 30 wt % to a high of about 60 wt %, about 70 wt %, about 80 wt %, about 90 wt %, or about 95 wt %. When the purge gas product contains comonomers, the concentration of comonomers, e.g., butene, hexene, and / or octene, can range from a low of about 10 wt %, about 20 wt %, or about 30 wt % to a high of about 40 wt %, about 50 wt %, about 60 wt %, about 70 wt %, about 80 wt %, about 90 wt %, or about 95 wt %.

[0085] All or a portion of the condensed fluid of the condenser can be recycled to the polymerization reactor 301. The condensed fluid recovered from the condenser can be recycled via line 388 to the polymerization reactor and / or introduced to the cycle fluid lines 315, not shown.

[0086] The gas product of the condenser may be recycled back to the interchanger. The gas product of the condenser may be recycled and mixed with the makeup gas to provide a fresh makeup gas that may assist in additional cooling of the compressed purge gas that enters the interchanger. The interchanger may divert the gas product of the condenser to return to the water cooler. Alternatively, the interchanger may direct the gas product of the condenser to be sent to line 388 where it may be recycled via line 396 or vented or flared via line 394. For example, all or a portion of the gas product via line 388 can be vented, flared, combusted to generate heat, or otherwise disposed via line 394. Advantageously, the use of ethane reduces the amount of nitrogen that is sent to flare, reducing undesirable NOx gases from being generated and / or emitted by the polymerization system 300. Moreover, the use of ethane havinga higher heating value than nitrogen may result in a more efficient energy production of the flare that may be used for heating a subsequent or alternative process, e.g., an olefins processing plant for producing olefins or polymerizing olefins.

[0087] The amount of the gas product via line 394 removed from the polymerization system 300 can range from about 0% to about 10% of the gas product via line 188, e.g., about 0% to about 3%, about 3% to about 6%, about 6% to about 9%, or about 5% to about 10%. At times 100% of the gas product in line 388 can be recycled via line 396 to the polymerization reactor 301. In another example, all or a portion of the gas product in line 388 can be vented to flare via line 394. According to some embodiments, it is preferred to recycle a percentage, such as about 70% to about 100% of the gas product via line 388, e.g., about 70% to about 80%, about 80% to about 90%, or about 90% to about 100%. In this way, flaring of (and generation of combustion products from) the gas product is advantageously reduced or eliminated.

[0088] Overall, an improved purification regeneration bed systems are provided that can replace nitrogen with a higher heating value gas, e.g., greater than 300 BTU / SCF, such as hydrogen. The higher heating value of hydrogen allows for longer purification regeneration processes to be performed as hydrogen does not heat rapidly, when compared to nitrogen. Moreover, the use of hydrogen reduces and / or eliminates the need for supplemental natural gas or other carbon-containing gas such as hydrocarbon gas during flare, such that H2O rather than CO2is produced as a flare product. The use of hydrogen also reduces operational expenses as there is a significant increase (e.g., 14x) in the volumetric flow rate of hydrogen gas, as compared to nitrogen. Additionally, by integrating the purification regeneration bed system with a cracker or polyethylene polymerization reactor, a reduction of operational costs may occur as hydrogen is readily produced and may be directed to the purification regeneration bed system. EMBODIMENTS

[0089] The present disclosure provides, among others, the following embodiments, each of which can be considered as optionally including any alternate embodiments:

[0090] E1. A method, comprising providing a regeneration gas to an open loop regeneration system comprising a purification bed, the regeneration gas comprising hydrogen, directing the regeneration gas to the purification bed; and directing the regeneration gas from the purification bed to a gas unit.

[0091] E2. The method of embodiment E1, further comprising providing a monomer to the open loop regeneration system comprising the purification bed; purifying the monomer via the purification bed; and directing the monomer to a reactor of a gas-phase polymerization system.

[0092] E3. The method of embodiment E1 or E2, wherein providing the regeneration gas to the open loop regeneration system comprises providing the regeneration gas at a temperature of about 10 °C to about 45 °C and a pressure of about 1 psig to about 200 psig.

[0093] E4. The method of embodiment E3, wherein providing the regeneration gas to the open loop regeneration system comprises heating the regeneration gas to a temperature of about 100 °C to about 500 °C using a heater.

[0094] E5. The method of any one of embodiments E1-E4, further comprising regulating a pressure of the regeneration gas being directed to the gas unit.

[0095] E6. The method of embodiment E5, wherein the pressure is about 1 psig to about 30 psig.

[0096] E7. The method of any one of embodiments E1-E6, further comprising providing the first regeneration gas to the open loop regeneration system; directing the first regeneration gas to the gas unit; providing a second regeneration gas to the open loop regeneration system; and directing the second regeneration gas to the gas unit.

[0097] E8. The method of embodiment E7, wherein the second regeneration gas comprises nitrogen.

[0098] E9. The method of any one of embodiments E1-E8, further comprising providing the regeneration gas from an integrated olefins processing plant.

[0099] E10. The method of any one of embodiments E1-E9, further comprising regulating a flow of the regeneration gas being provided to the open loop regeneration system.

[0100] E11. The method of embodiment E10, wherein the flow is about 400 lb / hr to about 20,000 lb / hour.

[0101] E12. A method, comprising providing a regeneration gas to a closed loop regeneration system comprising a purification bed, the regeneration gas is hydrogen; directing the regeneration gas to the purification bed; recycling a first portion of the regeneration gas; and directing a second portion of the regeneration gas to a gas unit.

[0102] E13. The method of embodiment E12, wherein providing the regeneration gas comprises cooling the regeneration gas to a temperature of about 30 °C to about 40 °C using a cooler.

[0103] E14. The method of embodiment E13, wherein recycling the first portion of the regeneration gas comprises directing the first portion of the regeneration gas to the cooler.

[0104] E15. The method of any one of embodiments E12-E14, wherein providing the regeneration gas comprises heating the regeneration gas to a temperature of about 250 °C to about 300 °C using a heater.

[0105] E16. The method of embodiment E15, wherein recycling the first portion of the regeneration gas comprises directing the first portion of the regeneration gas to the heater.

[0106] E17. The method of any one of embodiments E12-E16, wherein recycling the first portion of the regeneration gas cooling the first portion of the regeneration gas to a temperature of about 30 °C to about 40 °C using a suction cooler.

[0107] E18. The method of embodiment E16, further comprising removing condensed water using a collector.

[0108] E19. The method of embodiment E18, further comprising compressing the first portion of the regeneration gas to form a compressed regeneration gas using a compressor.

[0109] E20. The method of embodiment E19, wherein the compressed regeneration gas comprises a pressure of about 5 psig to about 100 psig.

[0110] E21. The method of embodiment E19, wherein the compressed regeneration gas comprises a temperature of about 100 °C to about 250 °C.

[0111] E22. The method of any one of embodiments, E12-E21, further comprising providing the regeneration gas from an integrated olefins processing plant to the closed loop regeneration system.

[0112] Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges including the combination of any two values, e.g., the combination of any lower value with any upper value, the combination of any two lower values, and / or the combination of any two upper values are contemplated unless otherwise indicated. Certain lower limits, upper limits and ranges appear in one or more claims below. All numerical values are "about" or "approximately" the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

[0113] All documents and references cited herein, including testing procedures, publications, patents, journal articles, etc. are herein fully incorporated by reference for all jurisdictions in which such incorporation is permitted and to the extent such description is consistent with the disclosure.

[0114] Likewise, whenever a composition, an element or a group of elements is preceded with the transitional phrase “comprising”, it is understood that we also contemplate the same composition or group of elements with transitional phrases “consisting essentially of,” “consisting of”, “selected from the group of consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa. The phrases, unless otherwise specified, “consists essentially of” and “consisting essentially of” do not exclude the presence of othersteps, elements, or materials, whether or not, specifically mentioned in this specification, so long as such steps, elements, or materials, do not affect the basic and novel characteristics of the claimed disclosure, additionally, the phrases do not exclude impurities and variances normally associated with the elements and materials used.

[0115] While the claimed disclosure is described with respect to a number of embodiments and examples, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope and spirit of the disclosure.

Claims

CLAIMS 1. A method, comprising: providing a regeneration gas to an open loop regeneration system comprising a purification bed, the regeneration gas comprising hydrogen; directing the regeneration gas to the purification bed; and directing the regeneration gas from the purification bed to a gas unit.

2. The method of claim 1, further comprising: providing a monomer to the open loop regeneration system comprising the purification bed; purifying the monomer via the purification bed; and directing the monomer to a reactor of a gas-phase polymerization system.

3. The method of claim 1 or claim 2, wherein providing the regeneration gas to the open loop regeneration system comprises providing the regeneration gas at a temperature of about 10 °C to about 45 °C and a pressure of about 1 psig to about 200 psig.

4. The method of claim 3, wherein providing the regeneration gas to the open loop regeneration system comprises heating the regeneration gas to a temperature of about 100 °C to about 500 °C using a heater.

5. The method of claim 1 or any one of claims 2-4, further comprising regulating a pressure of the regeneration gas being directed to the gas unit.

6. The method of claim 5, wherein the pressure is regulated to be within the range from about 1 psig to about 30 psig.

7. The method of claim 1 or any one of claims 2-6, further comprising: providing a second regeneration gas to the open loop regeneration system; and directing the second regeneration gas to the gas unit, wherein the second regeneration gas comprises nitrogen.

8. The method of claim 1 or any one of claims 2-7, further comprising providing the regeneration gas from an integrated olefins processing plant to the open loop regeneration system.

9. The method of claim 1 or any one of claims 2-8, further comprising regulating a flow of the regeneration gas being provided to the open loop regeneration system.

10. The method of claim 9, wherein the flow is regulated to be within the range from about 400 lb / hr to about 20,000 lb / hour.

11. The method of claim 1 or any one of claims 2-10, wherein directing the regeneration gas to the gas unit comprises directing at least a portion of the regeneration gas to a flare; and wherein the method further comprises flaring the portion of the regeneration gas without adding a supplemental compound that forms combustion products including CO2.

12. A method, comprising: providing a regeneration gas to a closed loop regeneration system comprising a purification bed, wherein the regeneration gas is hydrogen; directing the regeneration gas to the purification bed; recycling a first portion of the regeneration gas; and directing a second portion of the regeneration gas to a gas unit.

13. The method of claim 12, wherein providing the regeneration gas comprises cooling the regeneration gas to a temperature of about 30 °C to about 40 °C using a cooler or a suction cooler, and further wherein recycling the first portion of the regeneration gas comprises directing the first portion of the regeneration gas to the cooler.

14. The method of claim 12, wherein providing the regeneration gas comprises heating the regeneration gas to a temperature of about 250 °C to about 300 °C using a heater, and further wherein recycling the first portion of the regeneration gas comprises directing the first portion of the regeneration gas to the heater.

15. The method of claim 13, wherein cooling the regeneration gas uses a suction cooler, and wherein the method further comprises removing condensed water using a collector.

16. The method of claim 15, further comprising compressing the first portion of the regeneration gas to form a compressed regeneration gas using a compressor.

17. The method of claim 16, wherein the compressed regeneration gas comprises a pressure of about 5 psig to about 100 psig and / or a temperature of about 100°C to about 250°C.

18. The method of claim 12 or any one of claims 13-17, further comprising providing the regeneration gas from an integrated olefins processing plant to the closed loop regeneration system.

19. The method of claim 12 or any one of claims 13-18, wherein directing the second portion of the regeneration gas to the gas unit comprises directing at least part of the second portion of the regeneration gas to a flare; and wherein the method further comprises flaring said part of the regeneration gas without adding a supplemental compound that forms combustion products including CO2.

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