Continuous process and apparatus for purifying and recycling nitrogen in pneumatic conveying systems

Abstract

A continuous process for separating nitrogen from a contaminated nitrogen mixture in a closed-loop pneumatic conveying system for transporting high-density polyethylene (HDPE) powder is developed. The process comprises introducing a contaminated nitrogen mixture into a filtration unit to remove at least 95% by weight of entrained particles, cooling the filtered gas stream in a first shell-and-tube heat exchanger using a flow control valve and a temperature sensor collectively configured to maintain an outlet temperature of 25°C to 35°C to condense at least 90% by weight of condensable components, producing a two-phase mixture, separating the nitrogen-rich gaseous phase from the liquid phase in an expansion-type separation drum, monitoring the oxygen concentration to maintain it below 5% by volume using an oxygen analyzer transmitter, pressurizing the separated gas stream using at least one blower to produce a reusable nitrogen stream, cooling the reusable nitrogen stream in a second shell-and-tube heat exchanger, and reintroducing the cooled reusable nitrogen stream into the conveying system via a rotary valve.

Description

REF-1404-02-013CONTINUOUS PROCESS AND APPARATUS FOR PURIFYING AND RECYCUING NITROGEN IN PNEUMATIC CONVEYING SYSTEMSCROSS-REFERENCE TO REEATED APPEICATION

[0001] The present disclosure application claims priority from pending IR Patent Application Serial No 140350140003004722, filed on October 06, 2024, entitled “Process for Nitrogen Separation from the Nitrogen Return Line in Closed-Circuit Pneumatic Conveying Systems of High-Density Polyethylene Powders”, which is incorporated by reference herein in its entirety.TECHNICAL FIELD

[0002] The present disclosure is generally related to a continuous process and apparatus for separating nitrogen from a contaminated nitrogen mixture in a closed-loop pneumatic conveying system, more particularly, to a continuous process for removing entrained particles and condensable components from a nitrogen stream used in transporting high-density polyethylene (HDPE) powder to produce a reusable nitrogen stream within a system comprising a filtration unit, heat exchangers, and a separation drum.BACKGROUND

[0003] Nitrogen is widely used as a conveying gas in closed-loop pneumatic conveying systems for transporting high-density polyethylene (HDPE) powder, typically with a bulk density of 300-410 kg / m3. These systems are critical in chemical and polymer industries due to nitrogen’s inert properties, which ensure safe transport of flammable or reactive compositions and effluents such as TIL or Hexane along the HDPE powder conveying stream. However, during operation, the nitrogen stream becomes contaminated with entrained particles, such as HDPE particles with a particle size of 5 micrometers or less, and condensable components, such as hydrocarbons and oligomers. These contaminants reduce nitrogen purity, increase oxygen levels, and pose safety risks, including potential combustion hazards due toREF-1404-02-013 elevated oxygen concentrations. The presence of entrained particles and condensable components in the nitrogen stream complicates its reuse in closed-loop systems. Particles can foul pipelines and equipment, reducing system efficiency and requiring frequent maintenance. Condensable components, such as hexane and oligomers, can form liquid residues that further contaminate the system and impair nitrogen purity, which is critical for maintaining safe operating conditions (e.g., oxygen concentration below 6% by volume). Current methods for nitrogen purification, such as batch filtration or solvent-based separation, are often inefficient, costly, and incapable of achieving continuous operation at high flow rates (e.g., 3000 m3 / h or greater). These methods may also fail to achieve high nitrogen purity (e.g., at least 99% by volume) or adequately remove fine particles and condensable components, necessitating an improved approach. Thus, a cost-effective and efficient continuous process and system have been developed for separating nitrogen from a contaminated nitrogen mixture in a closed-loop pneumatic conveying system, particularly for HDPE powder transport, which is capable of removing at least 95% by weight of entrained particles and at least 90% by weight of condensable components, with specific embodiments achieving at least 99% by weight particle removal under high flow rate conditions (e.g., at least 5000 m3 / h), while producing a reusable nitrogen stream suitable for safe and continuous operation.SUMMARY

[0004] This summary is intended to provide an overview of the subject matter of the present disclosure, and is not intended to identify essential elements or key elements of the subject matter, nor is it intended to be used to determine the scope of the claimed implementations. Its sole purpose is to present some concepts of one or more exemplary aspects in a simplified form as a prelude to the more detailed description that is presented later. The proper scope of the present disclosure may be ascertained from the claims set forth below in view of the detailed description below and the drawings.REF-1404-02-013

[0005] One or more exemplary embodiments may describe an exemplary continuous process for separating nitrogen from a contaminated nitrogen mixture in a closed-loop pneumatic conveying system for transporting high-density polyethylene (HDPE) powder. The exemplary continuous process may comprise (a) introducing a contaminated nitrogen mixture into a filtration unit to remove at least 95% by weight of entrained particles, producing a filtered gas stream, (b) cooling the filtered gas stream in a first shell-and-tube heat exchanger to condense at least 90% by weight of condensable components, producing a two-phase mixture comprising a nitrogen-rich gaseous phase and a liquid phase, (c) separating the nitrogen-rich gaseous phase from the liquid phase in an expansion-type separation drum to produce a separated gas stream and a separated liquid stream, (d) monitoring an oxygen concentration in the separated gas stream to maintain it below 6% by volume using an oxygen analyzer transmitter, (e) pressurizing the separated gas stream using at least one blower to produce a reusable nitrogen stream, (f) cooling the reusable nitrogen stream in a second shell-and-tube heat exchanger to produce a cooled reusable nitrogen stream, and (g) reintroducing the cooled reusable nitrogen stream into the closed-loop pneumatic conveying system via a rotary valve.

[0006] One or more exemplary embodiments may describe one or more of the following features. In an exemplary embodiment, the contaminated nitrogen mixture may comprise nitrogen, entrained particles such as HDPE particles with a particle size of 5 micrometers or less and a density of at least 920 kg / m3, and condensable components such as hexane and oligomers. In one or more exemplary embodiments, the filtration unit may comprise a housing containing multiple cartridge-type dust filters with a high-efficiency filter medium (e.g., antistatic needle felt cartridge filters in NOMEX or PPS Ryton materials), configured to remove at least 95% by weight of entrained particles at a flow rate of 5595 m3 / h, a temperature in a range of 90°C to 110°C, and a gauge pressure in a range of 0.06 bar to 0.16 bar, with specific embodiments achieving at least 99% by weight removal under operating conditions includingREF-1404-02-013 a flow rate of at least 5000 m3 / h and a particle size of 5 micrometers or less. In an exemplary embodiment, the first shell- and-tube heat exchanger may use a coolant comprising an aqueous solution of 25-35% by weight methanol, and may include a flow control valve and a temperature sensor collectively configured to maintain an outlet temperature of the filtered gas stream in a range of 25°C to 35°C by adjusting coolant flow based on temperature measurements, producing a two-phase mixture at a flow rate of 4385 m3 / h. In one or more exemplary embodiments, the expansion-type separation drum may comprise an inlet nozzle, a gas outlet nozzle, a liquid discharge nozzle, a liquid trap tray, a differential pressure transmitter, a liquid level gauge, and a level transmitter, configured to separate the nitrogen-rich gaseous phase at a temperature in a range of 20°C to 40°C and a gauge pressure in a range of 0.01 bar to 0.03 bar, producing a gas stream at a flow rate of 4080 m3 / h. In an exemplary embodiment, the oxygen analyzer transmitter may comprise a zirconia-based or paramagnetic sensor operatively coupled to a control system to maintain the oxygen concentration below 6% by volume. In one or more exemplary embodiments, the at least one blower may comprise a plurality of centrifugal blowers arranged in parallel, pressurizing the separated gas stream to a gauge pressure in a range of 0.65 bar to 0.70 bar, producing a reusable nitrogen stream at a flow rate of 3100 m3 / h and a temperature in a range of 90°C to 100°C. In an exemplary embodiment, the second shell-and-tube heat exchanger may use a water coolant at a temperature in a range of 5°C to 10°C, cooling the reusable nitrogen stream to a temperature of 80°C and a gauge pressure in a range of 0.60 bar to 0.65 bar. In one or more exemplary embodiments, the rotary valve may comprise a star or drop-through valve, configured to control re-entry of HDPE powder into a transport line at a flow rate of 3000 m3 / h. In an exemplary embodiment, a particle removal efficiency may be in a range of 95% to 99% by weight, based on a total particle content of the contaminated nitrogen mixture. In another exemplary embodiment, a condensable component removal efficiency may be at least 90% by weight,REF-1404-02-013 based on a total condensable component content of the contaminated nitrogen mixture. In an exemplary embodiment, the reusable nitrogen stream may achieve a nitrogen purity of at least 99% by volume, with a particle content of less than 5% by weight and a condensable component content of less than 0.3% by weight.

[0007] This Summary may introduce a number of concepts in a simplified format; the concepts are further disclosed within the “Detailed Description” section. This Summary is not intended to configure essential / key features of the claimed subject matter, nor is intended to limit the scope of the claimed subject matter.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The novel features which are believed to be characteristic of the present disclosure, as to its structure, organization, use and method of operation, together with further objectives and advantages thereof, will be better understood from the following drawings in which an exemplary embodiment will now be illustrated by way of example. It is expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the present disclosure. Exemplary embodiments will now be described by way of example in association with the accompanying drawings in which:

[0009] FIG. 1 illustrates flowchart of an exemplary method for synthesizing exemplary calcium carbonate nanoparticles, consistent with one or more exemplary embodiments of the present disclosure;

[0010] FIG. 2 illustrates a schematic representation of an exemplary reaction for forming calcium carbonate by reacting sodium carbonate with calcium chloride, consistent with one or more exemplary embodiments of the present disclosure;

[0011] FIG. 3 illustrates a plot of XRD pattern analysis of exemplary calcium carbonate nanoparticles, consistent with one or more exemplary embodiments of the present disclosure;REF-1404-02-013

[0012] FIG. 4 illustrates a plot of XRD pattern analysis of exemplary calcium carbonate nanoparticles revealing an exemplary composition comprising a mixture of aragonite and calcite phases, consistent with one or more exemplary embodiments of the present disclosure; and

[0013] FIG. 5 illustrates transmission electron microscopy (TEM) images of exemplary calcium carbonate nanoparticles, consistent with one or more exemplary embodiments of the present disclosure.DETAILED DESCRIPTION

[0014] In the following detailed description, numerous specific details are set forth by way of examples to provide a thorough understanding of the relevant teachings related to the exemplary embodiments. However, it should be apparent that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and / or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings.

[0015] The following detailed description is presented to enable a person skilled in the art to make and use the methods and devices disclosed in one or more exemplary embodiments of the present disclosure. For purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that these specific details are not required to practice the disclosed exemplary embodiments. Descriptions of specific exemplary embodiments are provided only as representative examples. Various modifications to the exemplary implementations will be plain to one skilled in the art, and the general principles defined herein may be applied to other implementations and applications without departing from the scope of the present disclosure. The present disclosure is not intended to be limited to the implementations shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein.REF-1404-02-013

[0016] Disclosed herein is an exemplary continuous process and system for separating nitrogen from an exemplary contaminated nitrogen mixture in an exemplary closed-loop pneumatic conveying system, particularly for transporting high-density polyethylene (HDPE) powder. In an exemplary embodiment, an exemplary contaminated nitrogen mixture may refer to an exemplary gas stream comprising nitrogen, entrained particles such as HDPE particles with a particle size of 5 micrometers or less and a density of at least 920 kg / m3, and condensable components such as hexane and oligomers. In an exemplary embodiment, an exemplary closed- loop pneumatic conveying system may refer to an exemplary system configured to transport HDPE powder using nitrogen as an exemplary conveying gas, wherein nitrogen is purified and recycled to maintain system efficiency and safety. In an exemplary embodiment, N% by weight may refer to a measurement where N% of the total weight of an exemplary mixture or solution is composed of an exemplary specified component, such as entrained particles or an exemplary solute. For example, if the density of an exemplary solution is such that 100 mL corresponds to 100 grams, an exemplary N% by weight may be equivalent to N% (w / v) where N grams of an exemplary component are present in 100 milliliters of an exemplary mixture or solution.

[0017] FIG. 1 illustrates flowchart of exemplary continuous process 100 for separating nitrogen from an exemplary contaminated nitrogen mixture in an exemplary closed-loop pneumatic conveying system, consistent with one or more exemplary embodiments of the present disclosure.

[0003] In one or more exemplary embodiments, exemplary continuous process 100 may comprise: (a) introducing an exemplary contaminated nitrogen mixture into filtration unit to remove at least 95% by weight of entrained particles, producing filtered gas stream (102), (b) cooling filtered gas stream to condense at least 90% by weight of condensable components, producing two-phase mixture (104), (c) separating two-phase mixture into an exemplary nitrogen-rich gaseous phase and an exemplary liquid phase in separation unit (106), (d) monitoring an exemplary oxygen concentration in separated gas stream to maintain it belowREF-1404-02-0136% by volume (108), (e) pressurizing separated gas stream to produce reusable nitrogen stream (110), (f) cooling reusable nitrogen stream to produce cooled reusable nitrogen stream (112), and (g) reintroducing cooled reusable nitrogen stream into exemplary closed-loop pneumatic conveying system (114).

[0018] FIG. 2 illustrates schematic diagram of exemplary system 200 for separating nitrogen from an exemplary contaminated nitrogen mixture in an exemplary closed-loop pneumatic conveying system, consistent with one or more exemplary embodiments of the present disclosure.

[0019] In one or more exemplary embodiments, exemplary system 200 may comprise: (a) filtration unit (202); (b) first shell-and-tube heat exchanger (204); (c) expansion-type separation drum (206); (d) oxygen analyzer transmitter (208); (e) at least one blower (210); (f) second shell-and-tube heat exchanger (212); and (g) rotary valve (214), interconnected to form an exemplary closed-loop system for transporting HDPE powder.

[0020] In further detail with respect to step 102, step 102 may comprise introducing an exemplary contaminated nitrogen mixture into filtration unit (202) to remove at least 95% by weight of entrained particles, producing filtered gas stream (104). In an exemplary embodiment, filtration unit (202) may refer to an exemplary device configured to remove particles, such as HDPE particles with a particle size of 5 micrometers or less and a true density of 920 kg / m3, from an exemplary gas stream using an exemplary porous medium. In an exemplary embodiment, filtration unit (202) may comprise an exemplary housing containing multiple cartridge-type dust filters, each with an exemplary high-efficiency filter medium (e.g., anti-static needle felt cartridge filters in NOMEX or PPS Ryton materials) designed to capture fine HDPE particles. In an exemplary embodiment, filtration unit (202) may include inlet (216) for receiving an exemplary contaminated nitrogen mixture, an exemplary gas outlet for filtered gas stream (218), and particulate discharge outlet (220) for collected particles, as shown inREF-1404-02-013FIG. 2 (200). In an exemplary embodiment, filtration unit (202) is configured to handle high flow rates (e.g., 5595 m3 / h) and maintain low pressure drop, ensuring efficient removal of at least 95% by weight of entrained particles under operating conditions of 90°C to 110°C and 0.06 bar to 0.16 bar gauge pressure. In one or more exemplary embodiments, introducing an exemplary contaminated nitrogen mixture into filtration unit (202) may comprise passing an exemplary gas stream comprising nitrogen, HDPE particles, and condensable components (e.g., hexane, oligomers) through cartridge-type dust filter (202) at a flow rate of 5595 m3 / h, a temperature in a range of 90°C to 110°C, and a gauge pressure in a range of 0.06 bar to 0.16 bar, as shown in FIG. 2 (200). Filtration unit (202) produces filtered gas stream (218) with a flow rate of 4878 m3 / h and removes particles to particulate output stream (220). In an exemplary embodiment, filtration unit (202) may remove at least 95% by weight of entrained particles, producing filtered gas stream (218) with less than 5% by weight of particles. In an exemplary specific embodiment, cartridge-type dust filter (202) may be configured to remove at least 99% by weight of entrained particles under operating conditions including a flow rate of at least 5000 m3 / h and a particle size of 5 micrometers or less, consistent with the exemplary high-performance filtration capabilities of exemplary system 200. In one or more exemplary embodiments, filtration unit (202) may comprise, for example, but is not limited to, cartridgetype dust filter, an exemplary bag filter, an exemplary combination thereof, or other filtration devices well-known to those skilled in the art.

[0021] In further detail with respect to operating conditions of exemplary continuous process 100, an exemplary range of 90°C to 110°C for filtration unit (202) may be selected to optimize removal of entrained particles while preventing thermal degradation of HDPE particles with a particle size of 5 micrometers or less, and further to retain upstream isothermal process conditions of the conveying system air-mover. In an exemplary embodiment, a temperature in a range of 90°C to 110°C ensures an exemplary viscosity of an exemplary gasREF-1404-02-013 stream that facilitates passage through an exemplary high-efficiency filter medium (e.g., antistatic needle felt cartridge filters in NOMEX or PPS Ryton materials) while maintaining a low pressure drop. Similarly, a gauge pressure in a range of 0.06 bar to 0.16 bar may be maintained to monitor the flow pressure for as a candidate for filter health conditions. In one or more exemplary embodiments, operating conditions may be adjusted within these ranges based on an exemplary composition of an exemplary contaminated nitrogen mixture, such as a higher concentration of condensable components requiring a lower temperature within a range of 90°C to 110°C to enhance particle capture.

[0022] In further detail with respect to step 104, step 104 may comprise cooling filtered gas stream (218) to a temperature of 25 °C to 35 °C and a gauge pressure in a range of 0.04 bar to 0.08 bar to condense at least 90% by weight of an exemplary condensable components, producing two-phase mixture (222) comprising an exemplary nitrogen-rich gaseous phase and an exemplary liquid phase. In an exemplary embodiment, an exemplary condensable components may refer to hexane, oligomers, or other compounds that condense into an exemplary liquid phase under the specified conditions. In an exemplary embodiment, 90% by weight of an exemplary condensable components may refer to 90% of total weight of an exemplary condensable components (e.g., hexane, oligomers) in filtered gas stream (218) being condensed into an exemplary liquid phase. In an exemplary embodiment, an exemplary first shell- and-tube heat exchanger may comprise an exemplary stainless steel shell containing an exemplary bundle of stainless steel tubes, through which filtered gas stream (218) flows, while an exemplary coolant (25-35% by weight methanol aqueous solution) circulates through an exemplary shell side. In an exemplary embodiment, an exemplary first shell-and-tube heat exchanger may be suction cooler (204). Suction cooler (204) may include an exemplary inlet for an exemplary gas stream, an exemplary outlet for two -phase mixture (222), coolant inlet (224) at -10°C, and coolant outlet (226) at 0°C, as shown in FIG. 2 (200). In an exemplaryREF-1404-02-013 embodiment, suction cooler (204) is equipped with flow control valve (228) and temperature sensor (230) operatively coupled to an exemplary PID controller to regulate an exemplary coolant flow based on temperature measurements, maintaining an exemplary outlet temperature in a range of 25°C to 35°C to optimize condensation of at least 90% by weight of an exemplary condensable components. In one or more exemplary embodiments, cooling filtered gas stream (218) may comprise passing filtered gas stream (218) through suction cooler (204) using an exemplary coolant media comprising an exemplary aqueous solution of 25-35% by weight methanol, entering at -10°C (224) and exiting at 0°C (226), producing two-phase mixture (222) with a flow rate of 4385 m3 / h, as shown in FIG. 2 (200). In other embodiments, the flow rate may be adjusted depending on the volumetric flow rate of conveying system. In an exemplary embodiment, suction cooler (204) may include flow control valve (228) and temperature sensor (230) collectively configured to maintain an exemplary outlet temperature of filtered gas stream (218) in a range of 25°C to 35°C by adjusting coolant flow based on temperature measurements. In one or more exemplary embodiments, alternative coolants may include, but are not limited to, an exemplary glycol solution, an exemplary water, or other cooling media well-known to those skilled in the art.

[0023] In further detail with respect to step 106, step 106 may comprise separating two- phase mixture (222) into an exemplary nitrogen-rich gaseous phase and an exemplary liquid phase in expansion-type separation drum (206) to produce separated gas stream (232) and separated liquid stream (234). In an exemplary embodiment, an exemplary separation unit may refer to expansion-type separation drum (206) configured to continuously separate gas and liquid phases. In an exemplary embodiment, expansion-type separation drum (206) may comprise an exemplary cylindrical vessel with an exemplary conical bottom, designed to exploit pressure reduction and gravitational settling to separate an exemplary nitrogen-rich gaseous phase from an exemplary liquid phase containing condensed hydrocarbons andREF-1404-02-013 oligomers. Expansion-type separation drum (206) may include an exemplary inlet nozzle for receiving two-phase mixture (222), an exemplary gas outlet nozzle for discharging an exemplary nitrogen-rich gaseous phase, and liquid discharge nozzle (236) for removing an exemplary liquid phase. Expansion-type separation drum (206) may be equipped with liquid trap tray (238) to enhance liquid collection, differential pressure transmitter (240) to monitor pressure differences across exemplary separation drum (206), liquid level gauge (242) to measure liquid accumulation, and level transmitter (244) to provide feedback for automated liquid discharge, ensuring continuous operation without liquid carryover into an exemplary gas stream, as shown in FIG. 2. Expansion-type separation drum (206) may accommodate operating conditions of 20°C to 40°C and 0.01 bar to 0.03 bar gauge pressure for an exemplary gas phase, and 0 bar to 0.1 bar for an exemplary liquid phase, tailored for high-efficiency separation in an exemplary closed-loop pneumatic conveying system. In one or more exemplary embodiments, separating two-phase mixture (222) may comprise introducing two- phase mixture (222) into expansion-type separation drum (206) configured to continuously separate an exemplary nitrogen-rich gaseous phase (232) at a temperature in a range of 20°C to 40°C and a gauge pressure in a range of 0.01 bar to 0.03 bar, and an exemplary liquid phase (234) comprising hexane and oligomers at a temperature in a range of 20°C to 40°C and a gauge pressure in a range of 0 bar to 0.1 bar, with a gas stream flow rate of 4080 m3 / h, as shown in FIG. 2. In other embodiments, the flow rate may be adjusted depending on the volumetric flow rate of conveying system. In an exemplary embodiment, expansion-type separation drum (206) may be configured to continuously separate and remove an exemplary liquid phase via liquid discharge nozzle (236). In one or more exemplary embodiments, expansion-type separation drum (206) may include, for example, but is not limited to, liquid trap tray (238), differential pressure transmitter (240), liquid level gauge (242), level transmitter (244), or other monitoring devices well-known to those skilled in the art.REF-1404-02-013

[0024] In further detail with respect to operation of liquid trap tray (238) in expansiontype separation drum (206), liquid trap tray (238) may be configured to collect an exemplary liquid phase comprising hexane and oligomers, preventing re-entrainment into an exemplary nitrogen-rich gaseous phase (232). In one or more exemplary embodiments, liquid level gauge (242) and level transmitter (244) may provide continuous feedback to adjust a flow rate of an exemplary liquid discharge through liquid discharge nozzle (236), ensuring efficient separation and minimal liquid carryover, as shown in FIG. 2.

[0025]

[0009] In further detail with respect to step 108, step 108 may comprise monitoring an exemplary oxygen concentration in separated gas stream (232) to maintain an exemplary oxygen concentration below 5% by volume. In one or more exemplary embodiments, monitoring an exemplary oxygen concentration may comprise using oxygen analyzer transmitter (208) configured to trigger an exemplary alarm when an exemplary oxygen concentration exceeds 5% by volume, wherein an exemplary alarm is operatively coupled to an exemplary control system configured to maintain an exemplary oxygen concentration below 5% by volume, as shown in FIG. 2. In an exemplary embodiment, an exemplary control system may adjust coolant flow rate. In one or more exemplary embodiments, oxygen analyzer transmitter (208) may comprise, for example, but is not limited to, an exemplary zirconia-based sensor, an exemplary paramagnetic sensor, an exemplary combination thereof, or other oxygen analyzers well-known to those skilled in the art.

[0026] In further detail with respect to safety features of exemplary continuous process 100, monitoring an exemplary oxygen concentration in separated gas stream (232) below 5% by volume ensures safe operation in exemplary closed-loop pneumatic conveying system. In an exemplary embodiment, oxygen analyzer transmitter (208) may be operatively coupled to an exemplary automated shutdown system configured to halt operation of exemplary system 200 if an exemplary oxygen concentration exceeds 5% by volume, preventing potentialREF-1404-02-013 combustion risks associated with HDPE powder transport. In one or more exemplary embodiments, an exemplary control system may adjust a flow rate of an exemplary nitrogen purge to dilute an exemplary oxygen concentration, as shown in FIG. 2.

[0027]

[0010] In further detail with respect to step 110, step 110 may comprise pressurizing separated gas stream (232) to a gauge pressure in a range of 0.65 bar to 0.70 bar to produce reusable nitrogen stream (501). In one or more exemplary embodiments, pressurizing separated gas stream (232) may comprise using at least one blower (210), producing reusable nitrogen stream (246) with a temperature in a range of 90°C to 100°C and a flow rate of 3100 m3 / h, as shown in FIG. 2. In other embodiments, the flow rate may be adjusted depending on the volumetric flow rate of the conveying system. In one or more exemplary embodiments, blower (210) may be an exemplary oil-free roots blower or an exemplary oil-free screw compressor. In an exemplary embodiment, at least one blower (210) may comprise an exemplary plurality of blowers arranged in parallel to increase flow capacity. In one or more exemplary embodiments, at least one blower (210) may comprise, for example, but is not limited to, an exemplary centrifugal blower, an exemplary positive displacement blower, an exemplary combination thereof, or other blowers well-known to those skilled in the art.

[0028] In further detail with respect to alternative configurations of at least one blower (210) may include an exemplary variable frequency drive (VFD) to adjust a flow rate of reusable nitrogen stream (246) based on an exemplary demand of exemplary closed-loop pneumatic conveying system, as shown in FIG. 2. In an exemplary embodiment, an exemplary VFD may enable precise control of a blower speed to optimize energy consumption and maintain a gauge pressure in a range of 0.65 bar to 0.70 bar, enhancing operational efficiency of exemplary system 200.REF-1404-02-013

[0029] In further detail with respect to step 112, step 112 may comprise cooling reusable nitrogen stream (246) to a temperature of 80°C and a gauge pressure in a range of 0.60 bar to 0.65 bar to produce cooled reusable nitrogen stream (248). In one or more exemplary embodiments, cooling reusable nitrogen stream (246) may comprise passing reusable nitrogen stream (246) through an exemplary second shell-and-tube heat exchanger using an exemplary coolant comprising an exemplary water at a temperature in a range of 5 °C to 10°C, as shown in FIG. 2. In an exemplary embodiment, an exemplary second shell-and-tube heat exchanger may be discharge cooler (212). In an exemplary embodiment, discharge cooler (212) may comprise an exemplary stainless steel shell containing an exemplary bundle of stainless steel tubes. In one or more exemplary embodiments, alternative coolants may include, but are not limited to, an exemplary glycol solution, an exemplary air, or other cooling media well-known to those skilled in the art.

[0030] In further detail with respect to step 114, step 114 may comprise reintroducing cooled reusable nitrogen stream (248) into exemplary closed-loop pneumatic conveying system. In one or more exemplary embodiments, reintroducing cooled reusable nitrogen stream (248) may comprise using rotary valve (214) configured to control reentry of HDPE powder into transport line (250) at a flow rate of 3000 m3 / h, as shown in FIG. 2. In other embodiments, the flow rate may be adjusted depending on the volumetric flow rate of the conveying system. In an exemplary embodiment, rotary valve (214) may comprise, for example, but is not limited to, an exemplary rotary valve, an exemplary drop through valve, an exemplary combination thereof, or other rotary valves well-known to those skilled in the art.

[0031] In further detail with respect to alternative configurations of suction cooler (204) and discharge cooler (212), suction cooler (204) and discharge cooler (212) may comprise, for example, but are not limited to, an exemplary plate heat exchanger, an exemplary finned-tube heat exchanger, or other heat exchange devices well-known to those skilled in the art. In anREF-1404-02-013 exemplary embodiment, an exemplary plate heat exchanger may be used to achieve a higher heat transfer efficiency for cooling filtered gas stream (218) to a temperature of 25 °C to 35 °C or reusable nitrogen stream (246) to a temperature of 80°C, particularly when an exemplary coolant flow rate is limited, as shown in FIG. 2.EXAMPLES

[0032] Hereinafter, one or more exemplary embodiments will be described in further detail with reference to examples. It will be obvious to a person having ordinary skill in the art that these examples may be for illustrative purposes only and are not to be interpreted to limit the scope of the present disclosure.Example 1: Nitrogen Separation in HDPE Pneumatic Conveying System

[0033] In this example, an exemplary contaminated nitrogen mixture was processed using an exemplary continuous method similar to exemplary continuous process 100. An exemplary contaminated nitrogen mixture, comprising nitrogen, entrained particles (with a particle size < 5 pm and a density > 920 kg / m3), and condensable components (hexane, oligomers), was introduced into filtration unit (202) comprising an exemplary housing with an exemplary multiple cartridge-type dust filters, each with an exemplary high-efficiency filter medium (e.g., anti-static needle felt cartridge filters in NOMEX or PPS Ryton materials), designed to remove at least 95% by weight of an exemplary entrained particles at a flow rate of 5595 m3 / h, a temperature in a range of 90°C to 110°C, and a gauge pressure in a range of 0.06 bar to 0.16 bar. Filtration unit (202) removed at least 95% by weight of an exemplary entrained particles, producing filtered gas stream (218) with a flow rate of 4878 m3 / h and particulate output stream (220), as shown in FIG. 2. In an exemplary specific embodiment, cartridge-type dust filter (202) achieved at least 99% by weight removal of an exemplary entrained particles under operating conditions including a flow rate of at least 5000 m3 / h and aREF-1404-02-013 particle size of 5 micrometers or less. An exemplary filtered gas stream was passed through suction cooler (204) using an exemplary coolant comprising an exemplary aqueous solution of 25-35% by weight methanol entering at - 10°C (224) and exiting at 0°C (226), with flow control valve (228) and temperature sensor (230) collectively configured to maintain an exemplary outlet temperature of an exemplary filtered gas stream in a range of 25°C to 35°C by adjusting coolant flow based on temperature measurements, cooling an exemplary gas stream to a temperature of 25°C to 35°C at a gauge pressure of 0.04 bar to 0.08 bar, condensing at least 90% by weight of condensable components into two-phase mixture (222) with a flow rate of 4385 m3 / h, as shown in FIG. 2. Suction cooler (204) included flow control valve (228) and temperature sensor (230) to maintain an exemplary outlet temperature of 30°C. An exemplary two-phase mixture was introduced into expansion-type separation drum (206), comprising an exemplary cylindrical vessel with an exemplary conical bottom, equipped with inlet nozzle, gas outlet nozzle, liquid discharge nozzle (236), liquid trap tray (238), differential pressure transmitter (240), liquid level gauge (242), and level transmitter (244) for continuous separation, which continuously separated an exemplary nitrogen-rich gaseous phase (232) at a temperature in a range of 20°C to 40°C and a gauge pressure in a range of 0.01 bar to 0.03 bar, and an exemplary liquid phase (234) comprising hexane and oligomers at a temperature in a range of 20°C to 40°C and a gauge pressure in a range of 0 bar to 0.1 bar, with an exemplary gas stream flow rate of 4080 m3 / h, as shown in FIG. 2. Oxygen analyzer transmitter (208) monitored an exemplary separated gas stream, maintaining an exemplary oxygen concentration below 5% by volume via an exemplary control system adjusting coolant flow rate, as shown in FIG. 2. An exemplary separated gas stream was pressurized using two parallel centrifugal blowers (210) to a gauge pressure in a range of 0.65 bar to 0.70 bar, producing reusable nitrogen stream (246) at a temperature in a range of 90°C to 100°C with a flow rate of 3100 m3 / h, as shown in FIG. 2. Reusable nitrogen stream (246) was cooled to a temperature of 80°C at aREF-1404-02-013 gauge pressure in a range of 0.60 bar to 0.65 bar in discharge cooler (212) using an exemplary water coolant at a temperature of 7 °C, as shown in FIG. 2. Cooled reusable nitrogen stream (248) was reintroduced into exemplary closed-loop pneumatic conveying system via rotary valve (214) controlling HDPE powder reentry into transport line (250) at a flow rate of 3000 m3 / h, as shown in FIG. 2.

[0034] In further detail with respect to equipment setup in this example, filtration unit (202) may comprise an exemplary housing containing cartridge-type dust filters, with an exemplary filter medium (e.g., anti-static needle felt cartridge filters in NOMEX or PPS Ryton materials). In an exemplary embodiment, an exemplary feed rate of an exemplary contaminated nitrogen mixture into filtration unit (202) may be controlled at 5595 m3 / h using an exemplary inlet valve to prevent overloading, ensuring a low pressure drop across exemplary cartridgetype dust filters. Similarly, suction cooler (204) may comprise an exemplary stainless steel shell configured to handle a gas flow rate of 4878 m3 / h. In one or more exemplary embodiments, two parallel oil-fee roots blowers (210) may be equipped with high-speed motors operating at 1500 rpm to achieve a gauge pressure in a range of 0.65 bar to 0.70 bar, as shown in FIG. 2.

[0035] In further detail with respect to alternative configurations in this example, filtration unit (202) may comprise, for example, but is not limited to, an exemplary bag filter with a filtration area of about 50 m2or an exemplary cyclone separator, designed to remove at least 95% by weight of entrained particles with a particle size of 5 micrometers or less. In an exemplary embodiment, an exemplary coolant for suction cooler (204) or discharge cooler (212) may include an exemplary glycol solution at a temperature in a range of 5°C to 10°C, achieving comparable condensation or cooling efficiency to an exemplary methanol solution or water coolant, as shown in FIG. 2.REF-1404-02-013Example 2: Characterization of Nitrogen Purity and Removal Efficiencies

[0036] In this example, an exemplary nitrogen purity, particle removal efficiency, and condensable component removal efficiency of exemplary continuous process 100 were characterized. An exemplary nitrogen purity was measured using gas chromatography, and particle and condensable component contents were measured using gravimetric analysis. An exemplary particle removal efficiency (Xparticulate) and an exemplary condensable component removal efficiency (Xcondensable) were calculated using Equation (1) and Equation (2), respectively: Equation (I)> c condensable, initial ^condensable, filtered . Equation (2)X condensable ~ ~ - - - - - x 100'-condensable, initialAn exemplary results are listed in Table 1.TABLE 1Nitrogen Purity and Particle Content.

[0037] As can be seen in Table 1, reusable nitrogen stream 246 achieved a nitrogen purity of at least 99% by volume, with particle content reduced to less than 5% by weight and condensable content reduced to less than 0.3% by weight. These results demonstrate that exemplary continuous process 100 effectively purifies nitrogen for reuse in an exemplary closed-loop pneumatic conveying system, achieving a particle removal efficiency of 95% by weight, with the cartridge-type dust filter achieving at least 99% by weight under operatingREF-1404-02-013 conditions including a flow rate of at least 5000 m3 / h and a particle size of 5 micrometers or less, and a condensable component removal efficiency of at least 90% by weight.

[0038] While the foregoing has described what are considered to be the best mode and / or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications and variations that fall within the true scope of the present teachings.

[0039] Unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain.

[0040] The scope of protection is limited solely by the claims that now follow. That scope is intended and should be interpreted to be as broad as is consistent with the ordinary meaning of the language that is used in the claims when interpreted in light of this specification and the prosecution history that follows and to encompass all structural and functional equivalents. Notwithstanding, none of the claims are intended to embrace subject matter that fails to satisfy the requirement of Sections 101, 102, or 103 of the Patent Act, nor should they be interpreted in such a way. Any unintended embracement of such subject matter is hereby disclaimed.

[0041] Except as stated immediately above, nothing that has been stated or illustrated is intended or should be interpreted to cause a dedication of any component, step, feature, object, benefit, advantage, or equivalent to the public, regardless of whether it is or is not recited in the claims.REF-1404-02-013

[0042] It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. Relational terms such as first and second and the like may be used solely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. An element proceeded by “a” or “an” does not, without further constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0043] Unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain.

[0044] It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study, except where specific meanings have otherwise been set forth herein. Relational terms such as “first” and “second” and the like may be used solely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions.

[0045] The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it may be seen that various features are grouped together in various implementations. This is for purposes of streamlining the disclosure, and is not to be interpreted as reflecting an intention that the claimed implementations require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matterREF-1404-02-013 lies in less than all features of a single disclosed implementation. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.

[0046] While various implementations have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more implementations and implementations are possible that are within the scope of the implementations. Although many possible combinations of features are shown in the accompanying figures and discussed in this detailed description, many other combinations of the disclosed features are possible. Any feature of any implementation may be used in combination with or substituted for any other feature or element in any other implementation unless specifically restricted. Therefore, it will be understood that any of the features shown and / or discussed in the present disclosure may be implemented together in any suitable combination. Accordingly, the implementations are not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.

Claims

REF-1404-02-013What is claimed is:

1. A continuous process for separating nitrogen from a contaminated nitrogen mixture in a closed- loop pneumatic conveying system, the continuous process comprising:(a) introducing a contaminated nitrogen mixture into a filtration unit, wherein the contaminated nitrogen mixture comprises nitrogen, entrained particles, and condensable components, wherein the filtration unit is configured to remove at least 95% by weight of the entrained particles, producing a filtered gas stream;(b) cooling the filtered gas stream to a temperature in a range of 25°C to 35°C and a gauge pressure in a range of 0.04 bar to 0.08 bar to condense at least 90% by weight of the condensable components, producing a two-phase mixture comprising a nitrogen-rich gaseous phase and a liquid phase;(c) separating the nitrogen-rich gaseous phase from the liquid phase in a separation unit to produce a separated gas stream and a separated liquid stream;(d) monitoring an oxygen concentration in the separated gas stream to maintain the oxygen concentration below 5% by volume;(e) pressurizing the separated gas stream to a gauge pressure in a range of 0.60 bar to 0.75 bar to produce a reusable nitrogen stream;(f) cooling the reusable nitrogen stream to a temperature in a range of 75°C to 85°C to produce a cooled reusable nitrogen stream; and(g) reintroducing the cooled reusable nitrogen stream into the closed-loop pneumatic conveying system.REF-1404-02-0132. The continuous process of claim 1, wherein the contaminated nitrogen mixture is obtained from a closed-loop pneumatic conveying system configured to transport high-density polyethylene (HDPE) powder having a density of at least 920 kg / m3.

3. The continuous process of claim 1, wherein the entrained particles comprise high-density polyethylene (HDPE) particles having a particle size of 5 micrometers or less.

4. The continuous process of claim 1, wherein the contaminated nitrogen mixture, prior to introduction into the filtration unit, has a temperature in a range of 90°C to 110°C and a gauge pressure in a range of 0.06 bar to 0.16 bar.

5. The continuous process of claim 1, wherein the filtration unit comprises a cartridge-type dust filter configured to remove at least 95% by weight of entrained particulates.

6. The continuous process of claim 5, wherein the cartridge-type dust filter is configured to remove at least 99% by weight of entrained particles under operating conditions comprising a contaminated nitrogen mixture flow rate of at least 5000 m3 / h and a particle size of 5 micrometers or less.

7. The continuous process of claim 1, wherein cooling the filtered gas stream comprises passing the filtered gas stream through a first shell-and-tube heat exchanger using a coolant comprising an aqueous solution containing 25-35% by weight methanol, wherein the coolant is introduced into the first shell-and-tube heat exchanger at a temperature in a range of -15°C to -5 °C and is discharged therefrom at a temperature in a range of -5°C to 5°C, wherein the first shell-and-tube heat exchanger includes a flow control valve and a temperature sensor collectively configured to maintain an outlet temperature of the filtered gas stream in a range of 25°C to 35°C by adjusting coolant flow based on temperature measurements.

8. The continuous process of claim 1, wherein the liquid phase comprises condensed hydrocarbons and oligomers.REF-1404-02-0139. The continuous process of claim 1, wherein the separation unit comprises an expansion-type separation drum configured to continuously separate the nitrogen-rich gaseous phase from the liquid phase and remove the separated liquid phase.

10. The continuous process of claim 9, wherein the separated gas stream has a temperature in a range of 20°C to 40°C and a gauge pressure in a range of 0.01 bar to 0.03 bar, and the separated liquid stream has a temperature in a range of 20°C to 40°C and a gauge pressure in a range of 0 bar to 0.1 bar.

11. The continuous process of claim 1, wherein monitoring the oxygen concentration comprises using an oxygen analyzer transmitter configured to trigger an alarm when the oxygen concentration exceeds 6% by volume, wherein the alarm is operatively coupled to a control system configured to maintain the oxygen concentration below 6% by volume.

12. The continuous process of claim 1, wherein pressurizing the separated gas stream comprises using at least one blower to produce the reusable nitrogen stream having a temperature in a range of 90°C to 100°C and a gauge pressure in a range of 0.60 bar to 0.75 bar.

13. The continuous process of claim 12, wherein the at least one blower comprises a plurality of blowers arranged in parallel configured to increase a flow capacity of the reusable nitrogen stream.

14. The continuous process of claim 1, wherein cooling the reusable nitrogen stream comprises passing the reusable nitrogen stream through a second shell- and-tube heat exchanger.

15. The continuous process of claim 1, wherein reintroducing the cooled reusable nitrogen stream comprises using a rotary valve configured to control re-entry of high-density polyethylene (HDPE) powder into a transport line of the closed-loop pneumatic conveying system.

16. A system for separating nitrogen from a contaminated nitrogen mixture in a closed-loop pneumatic conveying system for transporting high-density polyethylene (HDPE) powder, the system comprising:REF-1404-02-013(a) a filtration unit configured to remove at least 95% by weight of entrained particulates from a contaminated nitrogen mixture comprising nitrogen, entrained particulates, and condensable components to produce a filtered gas stream;(b) a first shell- and-tube heat exchanger configured to cool the filtered gas stream to a temperature in a range of 25°C to 35°C and a gauge pressure in a range of 0.04 bar to 0.08 bar to produce a two-phase mixture comprising a nitrogen-rich gaseous phase and a liquid phase;(c) an expansion-type separation drum configured to separate the nitrogen-rich gaseous phase from the liquid phase to produce a separated gas stream and a separated liquid stream;(d) an oxygen analyzer transmitter configured to monitor an oxygen concentration in the separated gas stream and maintain the oxygen concentration below 5% by volume;(e) at least one blower configured to pressurize the separated gas stream to a gauge pressure in a range of 0.60 bar to 0.75 bar to produce a reusable nitrogen stream;(f) a second shell-and-tube heat exchanger configured to cool the reusable nitrogen stream to a temperature in a range of 75°C to 85°C; and(g) a rotary valve configured to reintroduce the cooled reusable nitrogen stream and high- density polyethylene (HDPE) powder into a transport line of the closed-loop pneumatic conveying system.

17. The system of claim 16, wherein the filtration unit comprises a cartridge-type dust filter configured to remove at least 95% by weight of high-density polyethylene (HDPE) particles having a particle size of 5 micrometers or less.

18. The system of claim 16, wherein the first shell-and-tube heat exchanger comprises a flow control valve and a temperature sensor collectively configured to maintain an outlet temperature of the filtered gas stream in a range of 25°C to 35°C by adjusting coolant flow based onREF-1404-02-013 temperature measurements, and wherein the coolant comprises an aqueous solution of 25-35% by weight methanol.

19. The system of claim 16, wherein the expansion-type separation drum is configured to continuously separate the nitrogen-rich gaseous phase from the liquid phase and remove the separated liquid stream.

20. The system of claim 16, wherein the at least one blower comprises a plurality of blowers arranged in parallel to increase nitrogen a flow capacity of the reusable nitrogen stream.

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