Description:FIELD OF THE INVENTION:
Present invention provides a novel system incorporating an eductor system devoid of moving parts wherein the purge gas can be sucked using the motive fluid i.e. high pressure carrier gas (HP carrier gas) sourced from the carrier gas compressor system. This purge gas is then in-turn sent to the mother plant i.e. FCCU for recovery along with the carrier gas.

BACKGROUND OF THE INVENTION:
A gas-phase agitated bed Polypropylene (PP) technology that employs a reactor featuring a helical agitator is known in the literature. Such gas-phase agitated bed Polypropylene (PP) technology is used to ensure a uniform reaction environment. The reaction predominantly utilizes Propylene as the monomer and deploys a conventional Ziegler-Natta catalyst. Tri-Ethyl-Aluminium (TEAL) is employed as a co-catalyst, while Silane serves as a stereo-modifier to regulate the properties of the resulting PP product, whereas Hydrogen is known to be used as a polymer chain terminating agent throughout the reaction process. These polymerization reactions are exothermic in nature and to manage the heat generated during polymerization, the circulating recycle gas from the reactor's top undergoes a cooling and liquefaction process within a shell and tube heat exchanger. The resulting cooled liquid is subsequently reintroduced into the reactor to regulate the temperature of the reactor bed. Following the reaction, the produced polypropylene powder is discharged to a powder discharge vessel through two powder discharge lines, thereby maintaining a uniform powder level within the reactor.

Now, the major step in production of Polypropylene using gas-phase agitated bed Polypropylene (PP) technology involves disengagement of carrier gas from the powder. The method known in literature involves disengaging unreacted gases, including Carrier Gas (primarily Monomer, Nitrogen and traces of TEAL, Hydrogen & Silane) from the powder within the discharge vessel. These gases are directed to carrier gas filtration, followed by washing and compression for further monomer (Propylene) recovery through distillation at the mother unit. However, residual monomer persists in the powder within the discharge vessel. The powder from the discharge vessel is directed to two dedicated purge vessels, where an extensive counter-current purging process using Nitrogen is employed to eliminate lingering monomer from the powder. Subsequently, the purified powder is fed into the downstream extrusion section to generate the final Polypropylene pellet as the end product.

The primary limitation of the known method is evident in the treatment of the outlet gas from the purge vessel, which comprises a mixture of monomer Propylene and Nitrogen. This gas mixture is directed to a conventional Membrane system for the separation and recovery of Monomer (Hydrocarbon gas) and Nitrogen. However, the membrane technology faces operational challenges for the following significant reasons:

- The inherent nature of the process results in the transportation of a small quantity of powder fines along with the purge gas, leading to the formation of sludge in the oil-flooded screw compressor of the membrane recovery unit. This sludge accumulation causes frequent system shutdowns, resulting in the flaring of the purge gas. Additionally, the purge gas contains trace amounts of unreacted TEAL, and the oil used in the screw compressor is incompatible with TEAL, causing further sludge formation. This, in turn, contributes to the choking of the entire system, and even changing the type of oil in the oil-flooded compressor does not alleviate the choking issue.

- Consequently, the shutdown of this system, attributed to the above mentioned challenges, results in substantial economic losses due to Monomer loss on account of flaring. Furthermore, the environmental impact is significant due to the flaring of hydrocarbons during system shutdowns.
Considering the recognized limitations of the existing method, the difficulties outlined in the purge gas recovery segment of the Polypropylene plant have spurred the creation of a novel solution. This innovative approach incorporates an Eductor system in conjunction with a fine-mesh filter to facilitate the recovery of monomer from the purge gases.

OBJECT OF THE INVENTION:
The main object of the present invention is to improve the reliability of existing complex purge gas monomer recovery system which comprises of a compressor and membrane system; by providing a novel system, in-place of the existing system, incorporating an eductor system devoid of moving parts wherein the purge gas can be sucked using the motive fluid i.e. high pressure carrier gas (HP carrier gas) sourced from the carrier gas compressor system.

Another object of the present invention is to provide a novel system that provides recovery of propylene monomer at the mother plant through distillation wherein the method ensures the complete recovery of purge gas monomers.

Another object of the present invention is to provide a novel system that stops hydrocarbon flaring (Environmental hazard) completely as being observed in the system known in literature due to frequent sludge formation in oil of membrane system screw compressor.

Another object of the present invention is to provide a novel system that provides recovery of propylene monomer wherein the method is sturdy, stable, reproducible and highly economical at plant level.

SUMMARY OF THE INVENTION:
The known gas-phase agitated bed Polypropylene (PP) technology provides a method wherein the polypropylene monomers produced after reaction are discharged to powder discharge vessel to remove unreacted carrier gases from the powder. Even the powder is required to be purged using Nitrogen to remove the left-over Monomer from the powder. These outlet gases from the purge vessel i.e., mixture of monomer Propylene and Nitrogen is then fed to a conventional Membrane system for the separation & recovery of Monomer (Hydrocarbon gas) and Nitrogen. This known method involves the loss of purge gas through flaring due to the shutdown of the membrane recovery system, which occurs as a result of sludge formation in the oil used in the oil-flooded screw compressor. This compressor is part of the membrane system installed in the purge gas recovery section of the gas-phase agitated bed Polypropylene production process.

Standard technology designs typically lack provisions to permanently resolve and overcome these issues associated with the membrane system. There is no permanent solution for the issue related to the sludge formation in oil due to presence of Teal traces in purge gas. Several types of synthetic oil of different grades were used to resolve the sludge formation issue in oil but the issue of sludge formation re-surfaces after few hours of plant operation.

Further, the oil being highly expensive and frequent replacement of oil followed by cleaning of the entire system due to sludge formation leads to significant increase in OPEX (Operating Expenditure) of the unit along with appreciable flaring loss.

To overcome the above mentioned challenge of known gas-phase agitated bed Polypropylene (PP) technology, present invention provides a novel system incorporating an eductor system devoid of moving parts which effectively resolves the reliability issues associated with membrane systems, wherein the method of the present invention involves sucking of the purge gas using the motive fluid i.e. high pressure carrier gas sourced from the carrier gas compressor system. This combined purge gas and motive fluid is directed to the carrier gas washing and compression system, subsequently contributing to the overall recovery at the mother plant through distillation.

This invention introduces a novel process in which the purge gas is innovatively recovered using an Eductor system (along with fine filter) with High Pressure Carrier Gas as the Motive fluid. The mixture of purge gas and the motive fluid is sent to the Carrier-Gas Washing & Compression section for the recovery in the mother plant inside the refinery.

The invention completely removes the requirement of frequent purge gas flaring issue while operating with the membrane system. This is also highly cost-effective solution without any rotary items i.e. zero energy consumption & no additional process investment other than hardware part i.e. Eductor & filter.

Accordingly, the main aspect of the present invention is to provide a system for recovery of propylene (PP) monomer from the Purge Gas system of Agitated Gas-phase Polypropylene comprising of:
a) an eductor system [200] comprising an eductor [201] devoid of moving parts and a fine-mesh filter [203], for recovering polypropylene (PP) monomer and nitrogen from purged gas;
wherein said Purge Gas system of Agitated Gas-phase Polypropylene further comprising of:
b) gas phase polypropylene reactors comprising of homopolymer reactor-1 [101] and Homopolymer reactor-2 [102] for polymerization of feed to produce the polypropylene product powder containing carrier gas and powder resin;
c) a discharge vessel [107] for separating the carrier gas and the PP powder resin; and
d) two purged vessels [113] and [114] in which the PP powder resin is purged with Nitrogen to remove residual polypropylene monomers and to form a purge gas, wherein said purge gas is directed to the eductor system [200] of step a).

In another aspect, the present invention provides a method of recovering polypropylene monomer without use of membrane system, wherein said method comprises:
a) polymerizing feed in gas phase polypropylene reactors comprising of homopolymer reactor-1 [101] and homopolymer reactor-2 [102] to form polypropylene product powder containing carrier gas and powder resin;
b) separating carrier gas and powder resin from the polypropylene product powder in downstream discharge vessel [107], wherein said polypropylene product powder is passed to the downstream discharge vessel [107] through two powder discharge lines;
c) directing the powder resin from the discharge vessel [107] in two parallel purge vessels [113] and [114] using nitrogen to remove residual polypropylene monomers and to form a purge gas;
d) directing the purge gas to eductor system [200] containing an eductor [201] and fine-mesh filter [203];
e) treating the carrier gas of step b) to generate high pressure carrier gas serving as motive fluid [202] in the eductor [201];
f) combined purge gas and motive fluid [202] is directed to the carrier gas washing and compression system containing carrier gas wash tower [112] and carrier gas compressor [119] for compressing the purge gas and motive fluid, and recovering the polypropylene monomer in mother unit [120] through distillation.

With the new innovative design, following improvements were achieved.
• Issue of frequent shutdown of the purge gas recovery section is eliminated.
• With the new innovative design, significant economic losses due to frequent requirement of Oil replacement, cleaning of the entire membrane system including lines/vessels and flaring of Hydrocarbon (purge gas) is eliminated.
• The stoppage of purge gas flaring not only has a positive economic effect, but also it has resulted in a positive environmental effect.
• The new design is very simple in nature, hence the same is operation friendly with no maintenance except time to cleaning of filter as per process requirements without any flaring.

BRIEF DESCRIPTION OF DRAWINGS
The present invention will now be described in detail with reference to the accompanying drawings.

These and other features, aspects and advantages of the present drawings will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represents like parts throughout the drawings, wherein:

Fig. 1 provides a typical Gas-phase Agitated bed Process,
Fig. 2 provides a typical Purge Gas Recovery System Process Block Flow Diagram along with the Membrane System,
Fig. 3 provides a typical Purge Gas Recovery System Process Block Flow Diagram along with the Innovative Eductor System for Purge Gas Recovery.
Fig. 4 provides a flow diagram illustrating the method of recovering the polypropylene monomer using Eductor system.
Fig. 5 provides working of the Eductor system.
Fig. 6 provides Purge Gas System Trends Before Implementation of Innovative Eductor System in Plant
Fig. 7 provides Purge Gas System Trends After Implementation of Innovative Eductor System in Plant

DETAILED DESCRIPTION OF THE INVENTION
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.

Reference throughout this specification to “an aspect”, “another aspect” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrase “in an embodiment”, “in another embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by "comprises...a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.

Herein, “Polypropylene” and “PP” are used interchangeably throughout the specification.

Herein, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, to provide a thorough understanding of embodiments of the disclosed subject matter.

Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings.

Referring to Fig. 1, illustrating a typical Gas-phase Agitated bed Process which in conjunction with Fig. 2 illustrates a typical Purge Gas Recovery System Process using the typical Membrane System. A typical Gas-phase Agitated Bed Polypropylene process can yield various resin grades, such as homopolymer, random copolymer, ter-polymer, and impact copolymer, defined by the reactor system configuration. The type of polymer produced depends on factors such as the type of feed (Propylene/Ethylene ratio), co-catalyst, stereo-modifier, hydrogen, and additives used in extrusion).

Fig. 1 shows a typical Gas-phase Agitated bed Process that involves Homopolymer Reactor-1 [101], and Homopolymer Reactor-2 [102]. Fresh propylene, Co-catalyst, Stereo-modifier (silane), Hydrogen and Additives (propylene and ethylene) are fed to Gas-phase Agitated bed PP reactor (Homopolymer Reactor -1 [101] and Homopolymer Reactor -2 [102]). Polymerization is carried out in the reactors [101] and [102] and as the reaction is exothermic, the heat dissipation is managed by evaporative cooling system [103] and [104]. Liquid propylene entering the reactor vaporizes and thereby removes the exothermic reaction energy. The unconverted monomer gas i.e. Propylene from the reactor top is recycled back to the condenser [105] and [106] via filter wherein condensation takes place. This condensed recycled liquid from cooling system [103] and [104] is used a coolant to control reactor bed temperature. The Gas-phase agitated bed process further comprises of Polypropylene production line consisting of many other Processing Sections viz. Purification in discharge vessel [107], Powder Conveying via purge vessel [108] containing purge vessels [113] and [114], Extrusion via Extruder [109] & Carrier Gas Recovery. The polypropylene product powder is discharged from reactors [101] and [102] to downstream discharge vessel [107] with the help of two powder discharge lines. Along with powder, some un-reacted gases called carrier gas is also discharged. In the discharge vessel, the Carrier gas and powder resins are separated. Referring to Fig. 2, The carrier gas is routed from Discharge vessel [107] through a cyclone [110] and filter [111] to remove entrained powder and then scrubbed with the mixture of white oil & Atmer in a wash tower [112] to remove residual teal traces followed by coalescing element prior to sending to the compression unit [119]. The compressed carrier gas is then routed to upstream mother unit for further recovery of monomer. Powder from the discharge vessel is routed via rotary feeders to two purge vessels [113] and [114] which are operating in parallel. Nitrogen is used to purge the powder in purge vessel for removal of residual monomers. The purge gas from the purge vessels is sent to Membrane System [115] for Monomer & Nitrogen recovery.

On other hand, the PP powder from the purge vessels [113] and [114] is pneumatically conveyed using Nitrogen as the conveying media to the powder silos [116] (Fig. 1) and the powder product from these silos is fed to the extruder [109] wherein polymer powder and additives are mixed based on product application, melted, homogenized, and extruded through a die plate. Pelletizing of the final product is carried out in an underwater pelletizer using cutter blades [117]. Pelletizing of the final product occurs in an underwater pelletizer, followed by drying and classification. The water used in the pelletizer is termed pellet cooling water, which is used for quenching of the pellets as well as transportation media to centrifugal dryer wherein separation of water and pellets takes place. Water is recycled back to a pellet water tank. The pellets after drying in Degassing unit [118] are sent to classifier for separation of desired size from under and over size pellets and finally pellets are pneumatically conveyed to the pellet blending silos [121] by an air conveying system. After homogenization in the blending silos the pellets are conveyed to the bagging and palletizing system.

Typically, the 2 nos. of Homopolymer reactors i.e. Homopolymer Reactor-1 [101] and Homopolymer reactor-2 [102] operate in parallel mode (Operating Pressure: 30-31 kg/cm2g), Operating Temperature: 80-81oC). The Polypropylene powder product produced in these parallel reactors is sent to the discharge vessel [107] (Operating Pressure: 1.1-1.5 kg/cm2g), Operating Temperature: 70-75oC) wherein the PP powder resin is disengaged from the unreacted gases from the reactor, these unreacted gases are called carrier gas which comprise primarily Monomer, Nitrogen and traces of TEAL, Hydrogen & Silane. From the discharge vessel, the powder is sent to 2 nos. of purge vessels [113] and [114] (Operating Pressure: 0.3-0.35 kg/cm2g), Operating Temperature: 70-75oC) wherein the PP powder is purged with Nitrogen to remove the residual monomer from the PP powder. This purging Nitrogen along with the residual monomer from 2 nos. purge vessels forms the “Purge Gas”.

The carrier gas from the discharge vessel as explained above, is sent to the carrier gas wash tower [112], where the traces of TEAL present in the carrier gas are neutralized using the counter-current contact of White-oil & ATMER mixture (3:1 ratio) in the carrier gas wash tower (Operating Pressure: 1.0-1.4 kg/cm2g, Operating Temperature: 70-75oC). The washed carrier gas is then passed through the carrier gas cooler and carrier gas coalescer (Operating Pressure: 0.7-1.0 kg/cm2g, Operating Temperature: 40oC) to remove the carried-over white-oil / ATMER from the carrier gas.

The recovered purge gas using the eductor system (as part of the invention) is mixed with the carrier gas at the upstream of the carrier gas wash tower. Subsequently, the carrier gas (along with the recovered purge gas) is sent to the carrier gas compressor (reciprocating 3-stage compressor), wherein the same is compressed (Operating Pressure: 21-23 kg/cm2g, Operating Temperature: 80-100 oC) and sent to the mother unit [120] i.e. FCCU for recovery. A part of the high pressure carrier gas is also sent to the purge gas eductor as the motive fluid [202] as explained in aforementioned points

Polypropylene (PP) production is a crucial industrial process, which is nowadays produced inside the Gas-phase Agitated polypropylene Reactor. The gas phase agitated polypropylene reactor technology used for production of polypropylene utilizes a reactor equipped with a helical agitator to maintain a consistent reaction environment. Within a conventional Gas-phase Agitated Bed Polypropylene facility, the recurrent issues arising from membrane system failure, attributed to sludge formation, result in a complete system shutdown, causing disruptions in overall plant operations and substantial flaring losses of Hydrocarbon-laden purge gas. Existing technological designs typically lack permanent solutions to effectively address and overcome the issues associated with membrane system failures. The problem of sludge formation in the oil, attributed to the presence of Teal traces in the purge gas has not been permanently resolved. Various types of synthetic oils of different grades were employed to mitigate sludge formation; however, the issue resurfaces after a few hours of plant operation and hence the issue remains unresolved despite attempts with various synthetic oils of different grades. The recurrence of sludge formation within a few hours of plant operation necessitates frequent oil replacement and comprehensive system cleaning, significantly elevating the Operating Expenditure (OPEX) of the unit, in addition to considerable flaring losses.

The conventional process involves a stirred gas-phase reaction system, complemented by additional processing sections like Purification, Powder Conveying, Extrusion, and Carrier Gas Recovery. Fresh propylene from OSBL is directed through the propylene Purification section to the Gas-phase Agitated Bed PP reactor, along with the necessary catalyst, co-catalyst, hydrogen, and stereo-modifier (Silane). The exothermic polymerization reaction occurs in a gas-phase stirred reactor, managed by evaporative cooling through the vaporization of liquid propylene entering the reactor. The discharged polypropylene product powder, along with un-reacted gases (carrier gas), is directed to a downstream discharge vessel through two powder discharge lines. In the discharge vessel, carrier gas and powder resins are separated, with the carrier gas undergoing filtration, scrubbing, and coalescing before compression and further recovery of monomer in the upstream mother unit. The powder from the discharge vessel is purged in two parallel vessels using Nitrogen to remove residual polypropylene monomers. The purge gas from these vessels is sent to a Membrane System for Monomer and Nitrogen recovery. Operational insights reveal constraints in the current purge gas recovery system based on membranes in Gas-phase Agitated Bed Polypropylene Production technology. Due to the inherent nature of the process, a small quantity of powder fines is entrained with the purge gas, resulting in sludge formation in the oil-flooded screw compressor of the membrane recovery unit. This frequent sludge-related shutdown of the system leads to the flaring of the purge gas. Additionally, the purge gas contains a minor amount of unreacted TEAL, and the oil used in the screw compressor is incompatible with TEAL, causing sludge formation. This, in turn, leads to system choking and the subsequent flaring of the purge gas. Despite efforts to address the issue, such as changing the type of oil in the oil-flooded screw compressor of the membrane recovery unit, the choking of the entire system persists. Consequently, the shutdown of this system, due to the aforementioned reasons, results in substantial economic losses and has a significant environmental impact due to hydrocarbon flaring.

An embodiment of the present invention involves a novel approach wherein purge gas is recovered using an Eductor system (in combination with a fine-mesh filter) with High-Pressure Carrier Gas as the Motive fluid. The present invention eliminates the need for frequent purge gas flaring issues when operating with the membrane system making the process and system used for recovery a cost effective solution with solution with no rotary components, translating to zero energy consumption and requiring no additional process investment other than the hardware components, namely the Eductor and filter.

Referring to Fig. 3, in this new system that illustrates typical Purge Gas Recovery System Process Block Flow Diagram along with the Innovative Eductor System for Purge Gas Recovery, rather than directing the purge gas to the membrane system, it is introduced into a dedicated eductor system [200] coupled with a fine-mesh filtration setup (comprising two filters - one operational fine filter [203] and the other on standby). This arrangement effectively eliminates powder fines carried over with the purge gas. In this process, the high-pressure carrier gas serves as the motive fluid [202] in the eductor [201]. The high-pressure motive fluid or carrier gas, draws in the low-pressure purge gas, and the resulting mixture is directed to the carrier gas washing section for subsequent recovery.

Referring to Fig. 4, provides method [300], illustrating an innovative method of recovering the PP monomers in a gas phase agitated reactors without the use of membrane system. The method [300] includes:
Step [301] which includes feed stock introduction in PP reactor [101] and [102].
Step [302] which provides Polymerization of feedstock (or feed) in Gas-Phase Stirred Reactors [101] and [102], wherein said feed includes mixture of Propylene and Ethylene, co-catalyst, stereo-modifier like silane, hydrogen, and additives;
and wherein said reactors are homopolymer Reactor-1 [101] and Homopolymer Reactor-2 [102].
Step [303] and [304] provides directing polypropylene product powder containing carrier gas and powder resin from the reactors to the discharge vessel [107].
Step [305] and [306] shows that the carrier gas and the powder resin present in polypropylene product powder are separated in the discharge vessel.
Step [308] involves directing powder resin to purge vessels [113] and [114] to for purge gas, wherein step [305] shows that carrier gas is compressed in the compressor systems [119] which under high pressure form motive fluid [202] under the step [310].
Step [309] shows that the purge gas is directed to the eductor system [200] containing an eductor [201] and fine-mesh filter [203].
As per Step [311] combined purge gas and motive fluid [202] is directed to the carrier gas washing and compression system [119].
As per step [313], combined purge gas and motive fluid [202] is directed to the carrier gas washing and compression system, containing carrier gas wash tower [112] and carrier gas compressor [119] for compressing the purge gas and recovering the polypropylene monomer in mother unit [120] through distillation.

Now, referring to Fig. 5 that provides working of Eductor system which is based upon Bernoulli’s Principle, wherein as the velocity of a fluid increases, its pressure decreases, and vice versa. An Eductor works by accelerating a high pressure stream (the ‘motive-fluid’ [202]) through a nozzle [401], converting the pressure energy into velocity. Around the nozzle tip, where velocity is highest, a low pressure region is created. This is often called the suction chamber [402] of the Eductor. Where the pressure in this region is lower than the pressure of the suction fluid connected to the Eductor side-inlet or ‘suction branch’, it will be entrained/sucked into the body of the Eductor (this process is also called the “venture Effect”). The two fluid streams then travel through the diffuser section [403], where velocity is decreased as a result of the diverging geometry and pressure is regained.

In the purge gas eductor system as part of this invention, the high pressure motive fluid [202] i.e. carrier gas (Operating Pressure: 21-23 kg/cm2g), Operating Temperature: 80-100oC) is used to suck the low pressure purge gas (Operating Pressure: 0.3-0.35 kg/cm2g), Operating Temperature: 70-75oC) coming from two number purge vessels [113] and [114] of the Polypropylene unit. At the outlet of the eductor, the combined purge gas & carrier is sent to the upstream of the carrier gas washing section (Operating Pressure: 1.0-1.4 kg/cm2g), Operating Temperature: 70-75oC) for compression and subsequent recovery of this purge gas along with carrier gas coming from the discharge vessels [107].

Accordingly, in one embodiment, the present invention provides a system for recovery of propylene monomer from the Purge Gas system of Agitated Gas-phase Polypropylene comprising of:
a) an eductor system [200] comprising an eductor [201] devoid of moving parts and a fine-mesh filter [203], for recovering polypropylene monomer and nitrogen from purged gas;
wherein said Purge Gas system of Agitated Gas-phase Polypropylene further comprising of:
b) gas phase polypropylene reactors comprising of homopolymer Reactor-1 [101] and Homopolymer reactor-2 [102] for polymerization of feed to produce the polypropylene product powder containing carrier gas and powder resin;
c) a discharge vessel [107] for separating the carrier gas and the powder resin present in polypropylene product powder; and
d) purged vessels [113] and [114] to which the powder resin is directed to form the purge gas, wherein said purge gas is directed to the eductor system [200] of step a).

In another embodiment, the feed added to reactors [101] and [102] includes mixture of Propylene and Ethylene, co-catalyst, stereo-modifier like silane, hydrogen, and additives.

In another embodiment, the carrier gas is directed to carrier gas compressor system [119] to generate high pressure carrier gas that can be used as motive fluid [202] in eductor system [200].

In another embodiment, the system of the present invention further comprising of:
a) a powder silo [116] for collecting the polypropylene monomer powder from discharge vessel [107], wherein said polypropylene monomer powder is recovered from powder resin;
b) an extruder [117] for extruding the polypropylene monomer powder in form of polypropylene pellets; and
c) a degassing unit [118] for drying of pellets followed by pneumatically conveying to pellet blending silos [121].

In another embodiment, the system of the present invention further comprises of:
a) a carrier gas wash tower [112] wherein the carrier gas and the purge gas undergoes filtration, scrubbing, and coalescing before compression;
b) a carrier gas compressor [119] for compressing the carrier and the purge gas; and
c) a mother unit [120] for recovering the polypropylene monomer from the carrier and the purge gas.

In another embodiment, the eductor system [200] of the present invention further involves use of High-Pressure Carrier Gas as the Motive fluid [202].

In another embodiment, the present invention provides a method of recovering polypropylene monomer without use of membrane system, wherein said method comprises:
a) polymerizing feed in gas phase polypropylene reactors comprising of homopolymer Reactor-1 [101] and Homopolymer Reactor-2 [102] to form polypropylene product powder containing carrier gas and powder resin;
b) separating carrier gas and powder resin from the polypropylene product powder in downstream discharge vessel [107], wherein said polypropylene product powder is passed to the downstream discharge vessel [107] through two powder discharge lines;
c) directing the powder resin from the discharge vessel [107] in two parallel purge vessels [113] and [114] using nitrogen to remove residual polypropylene monomers and to form a purge gas;
d) directing the purge gas to eductor system [200] containing an eductor [201] and fine-mesh filter [203];
e) treating the carrier gas of step b) to generate high pressure carrier gas serving as motive fluid [202] in the eductor [201]; and
f) combined purge gas and motive fluid [202] is directed to the carrier gas washing and compression system, containing carrier gas wash tower [112] and carrier gas compressor [119] for compressing the purge gas and recovering the polypropylene monomer in mother unit [120] through distillation.

In another embodiment, the eductor system [200] is devoid of moving parts wherein the purge gas is sucked using the motive fluid.

Results:
Referring to Fig. 6, it is observed that before implementation of the innovative eductor system, the complex membrane system used to remain under shutdown leading to complete flaring of the purge gas. This is indicated in the trend observed in Fig. 6, wherein the opening of purge gas control valve towards flare is ~100% (1st trend) indicating flaring of ~450-500 kg/hr purge gas (2nd trend). At this time, the innovative eductor system was not in-use which is indicated by the 0% opening of the motive fluid valve (3rd trend).

Now, referring to Fig. 7, it is observed that after implementation of the eductor system, the flaring of purge gas has stopped which is indicated by the 0% opening of the purge gas control valve towards flare (1st Trend). The purge gas (~500 kg/hr flow-rate) is getting recovered (2nd trend) along with the motive fluid i.e. high pressure carrier gas through the eductor system. At this time, the innovative eductor system was commissioned which is indicated by the ~40% opening of the motive fluid valve (3rd trend). After commissioning of the innovative eductor system, the combined purge gas and carrier gas is being sent to mother plant i.e. FCCU for recovery.

Accordingly, in one another embodiment of the present invention, the implementation of the new innovative design has led to the following improvements:
a) The recurring issue of frequent shutdowns in the purge gas recovery section has been completely eradicated as the eductor sytem is devoid of moving parts and as there is no requirement of use of screw compressor and hence sludge formation in oil used in the screw compressor is totally omitted.
b) With the introduction of the innovative design, substantial economic losses stemming from the frequent need for oil replacement, comprehensive cleaning of the entire membrane system (including lines and vessels), and the flaring of hydrocarbons (purge gas) have been eliminated. In present invention,aAs the eductor system is coupled with a fine-mesh filtration setup, this arrangement effectively eliminates powder fines carried over with the purge gas, hence avoiding flaring of hydrocarbons (purge gas).
c) The cessation of purge gas flaring not only has positive economic implications but also has resulted in a beneficial environmental impact.
d) The simplicity of the new design makes it operation-friendly, requiring minimal maintenance, limited to occasional cleaning of the filter as per process requirements, without any associated flaring. , Claims:1. A system for recovery of propylene monomer from the Purge Gas system of Agitated Gas-phase Polypropylene comprising of:
a) an eductor system [200] comprising an eductor [201] devoid of moving parts and a fine-mesh filter [203], for recovering polypropylene monomer and nitrogen from purged gas;
wherein said Purge Gas system of Agitated Gas-phase Polypropylene further comprising of:
b) gas phase polypropylene reactors comprising of homopolymer Reactor-1 [101] and Homopolymer reactor-2 [102] for polymerization of feed to produce the polypropylene product powder containing carrier gas and powder resin;
c) a discharge vessel [107] for separating the carrier gas and the powder resin present in polypropylene product powder; and
d) purged vessels [113] and [114] to which the powder resin is directed to form the purge gas, wherein said purge gas is directed to the eductor system [200] of step a).

2. The system as claimed in claim 1, wherein the system further comprising of:
a) a powder silo [116] for collecting the polypropylene monomer powder from discharge vessel [107], wherein said polypropylene monomer powder is recovered from powder resin;
b) an extruder [117] for extruding the polypropylene monomer powder in form of polypropylene pellets; and
c) a degassing unit [118] for drying of pellets followed by pneumatically conveying to pellet blending silos [121].

3. The system as claimed in claim 1, wherein the system further comprising of:
a) a carrier gas wash tower [112] wherein the carrier gas and the purge gas undergoes filtration, scrubbing, and coalescing before compression;
b) a carrier gas compressor [119] for compressing the carrier and the purge gas; and
c) a mother unit [120] for recovering the polypropylene monomer from the carrier gas and the purge gas, wherein the carrier gas is routed from discharge vessel [107] through a cyclone [110] and filter [111] to remove entrained powder and then scrubbed with the mixture of white oil & Atmer in a wash tower [112] to remove residual teal traces followed by coalescing element prior to sending to the compression unit [119], and wherein the washed carrier gas is then passed through the carrier gas cooler and carrier gas coalescer (Operating Pressure: 0.7-1.0 kg/cm2g, Operating Temperature: 40 Deg oC) to remove the carried-over white-oil / ATMER from the carrier gas.

4. The system as claimed in claim 1, wherein the carrier gas is directed to carrier gas compressor system [119] to generate high pressure carrier gas that is used as motive fluid [202] in eductor system [200], and wherein the called carrier gas comprises of Monomer, Nitrogen and traces of TEAL, Hydrogen and Silane.

5. The system as claimed in claims 1, wherein from the discharge vessel [107], the powder is sent to purged vessels [113] and [114] (Operating Pressure: 0.3-0.35 kg/cm2g), Operating Temperature: of 70-75oC), and wherein the polypropylene powder is purged with Nitrogen to remove the residual monomer from the polypropylene powder.

6. The system as claimed in claim 4, wherein the motive fluid [202] in eductor system [200] operates at a pressure of 21-23 kg/cm2g and a temperature of 80-100oC, wherein said motive fluid is used to suck the purge gas operating at pressure of 0.3-0.35 kg/cm2g and a temperature of 70-75oC.

7. The system as claimed in claim 4, wherein at the outlet of the educator system [200], the combined purge gas and carrier is sent to the upstream of the carrier gas washing section at an operating pressure of 1.0-1.4 kg/cm2g, and an Operating Temperature of 70-75oC for compression and subsequent recovery of this purge gas along with carrier gas coming from the discharge vessel [107].

8. A method of recovering polypropylene monomer without use of membrane system, wherein said method comprises:
a) polymerizing feed in gas phase polypropylene reactors comprising of homopolymer Reactor-1 [101] and Homopolymer reactor-2 [102] to form polypropylene product powder containing carrier gas and powder resin;
b) separating carrier gas and powder resin from the polypropylene product powder in downstream discharge vessel [107], wherein said polypropylene product powder is passed to the downstream discharge vessel [107] through two powder discharge lines;
c) directing the powder resin from the discharge vessel [107] in two parallel purge vessels [113] and [114] using nitrogen to remove residual polypropylene monomers and to form a purge gas;
d) directing the purge gas to eductor system [200] containing an eductor [201] and fine-mesh filter [203];
e) treating the carrier gas of step b) to generate high pressure carrier gas serving as motive fluid [202] in the eductor [201]; and
f) combined purge gas and the motive fluid [202] is directed to carrier gas washing and compression system, containing carrier gas wash tower [112] and carrier gas compressor [119] for compressing the purge gas and motive fluid, and recovering the polypropylene monomer in mother unit [120] through distillation.

9. The method as claimed in claim 8, wherein the feed added to reactors [101] and [102] includes mixture of Propylene and Ethylene, co-catalyst, stereo-modifier like silane, hydrogen, and additives.

10. The method as claimed in claim 8, wherein from the discharge vessel [107], the powder is sent to purged vessels [113] and [114] (Operating Pressure: 0.3-0.35 kg/cm2g), Operating Temperature: of 70-75oC), and wherein the polypropylene powder is purged with Nitrogen to remove the residual monomer from the polypropylene powder.