CN1332985C - Loop reactor apparatus and polymerization process with multiple olefin and catalyst feed points - Google Patents

Abstract

A slurry polymerization process wherein olefin monomer is fed to a continuous loop reactor at two or more locations to enable operation at higher and more stable monomer concentrations in the circulating slurry. The loop reactor apparatus has two or more monomer feeds and may have two or more catalyst feeds and/or two or more product take offs, each feed may have its own associated control scheme.

Description

Loop Reactor Apparatus and Polymerization Process for Multiple Olefin and Catalyst Feed Points

related application

This application claims priority under 35 U.S.C. § 119(e) to U.S. Patent Provisional Application 60/410,367, filed September 13, 2002. The latter is hereby incorporated by reference.

technical field

The present invention relates to the polymerization of olefinic monomers in a liquid medium, especially in a large loop reactor, by a slurry polymerization process.

Background technique

Polyolefins such as polyethylene and polypropylene can be produced by particle-form polymerization, also known as slurry polymerization. In this technique, feed materials such as monomer and catalyst are fed into a polymerization reactor (eg, a loop reactor), while a product slurry containing solid polyolefin particles in a liquid medium is withdrawn.

In continuous loop reactors, various feeds can be fed to the loop reaction section in different ways. For example, the monomer and catalyst can be fed separately or together, and the monomer and catalyst can be mixed with different amounts of diluent before being fed to the loop reaction section. In the loop reaction section, monomer and catalyst are dispersed in a fluid slurry. The monomers react at the catalyst in a polymerization reaction as they circulate through the loop reaction section in a fluid slurry. Polymerization produces solid polyolefin particles in a fluid slurry.

Slurry polymerization in the loop reaction section has proven commercially successful. Slurry polymerization technology has achieved worldwide success, producing billions of pounds of olefin polymers annually. However, it is still desirable to design and build larger reactors.

The properties of the polymer are influenced by the reactor conditions including the monomer concentration during the polymerization. In the loop polymerization process, during the polymerization process, the concentration of monomers often decreases as the monomers react to form polymers. In existing polymerization processes and loop reactors, the concentration of monomer is maintained within an acceptable range in the loop reactor throughout the loop reaction section using a single monomer feed.

The concentration of monomer in the loop reaction section is often estimated by measuring the concentration of monomer in the product slurry withdrawn from the loop reaction section. It is generally easier to measure the monomer concentration outside the loop reaction section than inside the loop reaction section.

Contents of the invention

As an aspect, a slurry polymerization method is provided. In the described method, solid polyolefin particles are produced in a liquid medium. The method includes feeding olefin monomer and catalyst into a loop reaction section. The catalyst must be capable of polymerizing olefin monomers. The method also includes feeding the olefin monomer into the loop reaction section through multiple (two or more) monomer feed ports. The amount of olefin monomer fed should make the concentration of olefin monomer in the loop reaction section within the desired range. For example, the concentration of olefin monomer in the liquid medium in the reactor can be maintained at 1.05% or less by feeding the olefin monomer at multiple symmetrically installed feed locations. The variation in olefin monomer concentration in the reactor can be kept so low that the standard deviation of olefin monomer concentration along the reactor is 0.4% or less. In some embodiments, there is at least one monomer feed port per 800 feet of reactor length, or at least one monomer feed port per 18,000 gallons of reactor volume.

The method may also include withdrawing a portion of the fluid slurry as an intermediate product through a plurality of product withdrawal ports. Catalyst can be fed through multiple catalyst feed ports. Preferably, the monomer feed port and the product feed port are installed symmetrically along the reaction section of the loop pipe. Catalyst feed ports can also be installed symmetrically along the loop reaction section.

The method also includes measuring the concentration of olefin monomer in the withdrawn fluid slurry portion and adjusting the feed of olefin monomer based on the measured concentration. The olefin monomer feed can be adjusted so that the amount of olefin monomer fed at one olefin feed port differs from the amount fed at the other monomer feed port.

As another aspect, a loop reactor apparatus is provided. The loop reactor apparatus comprises a plurality of primary sections and a plurality of upper and lower secondary sections. Each primary section is connected at an upper end to an upper secondary section and at a lower end to a lower secondary section by smooth bends. In this manner, the primary and secondary sections form a continuous flow path suitable for conveying fluid slurries. The flow path is substantially free of internal obstructions.

In another aspect, the loop reactor apparatus may comprise a first main leg, a second main leg, a third main leg, a fourth main leg, a fifth main leg, a sixth main leg, a seventh main leg, and an eighth main leg . The apparatus may also comprise a plurality of secondary sections, each of which is connected to two main branches to form a continuous flow path. The apparatus may comprise a first monomer feed port connected to the first main branch; a first product intake port connected to the third main branch; a second monomer feed port connected to the fifth main branch; A second product intake connected to the seventh main branch and at least one catalyst feed connected to a branch or section.

The above-mentioned loop reactor equipment comprises at least two devices for sending olefin monomer into the continuous flow channel, one device for sending the polymerization catalyst into the continuous flow channel and at least two devices for taking out the continuous flow channel Part of the fluid slurry equipment. The loop reactor apparatus may further comprise at least one apparatus for measuring the concentration of the olefin monomer withdrawn fluid slurry. The measuring device is fluidly connected to the reclaiming device. Said loop reactor unit may also comprise a unit for controlling the feeding of monomers into the unit. The measuring device supplies a signal representative of the measured concentration to the control device.

Description of drawings

Figure 1 is a perspective view of a loop reactor having multiple monomer feed ports, multiple catalyst feed ports, and multiple product withdrawal ports for withdrawing a portion of the slurry.

Detailed ways

The process and apparatus are suitable for the homopolymerization of ethylene and the copolymerization of ethylene with higher 1-olefins such as butene, 1-pentene, 1-hexene, 1-octene or 1-decene. The preferred method is the copolymerization of ethylene with as starting material 0.01-10% by weight, preferably 0.01-5% by weight, most preferably 0.1-4% by weight, of a comonomer selected from the Higher 1-alkenes and weight percents are based on the weight of ethylene and comonomer. (Such copolymers are still called polyethylene). On the other hand, a sufficient amount of comonomer can be used as starting material so as to obtain the product polyolefin with an added amount of comonomer in the range of 0.01-10, preferably 0.01-5, more preferably 0.1-4% by weight.

The liquid medium can be a diluent for the solid polymer particles, which can be different from or be the unreacted monomer. Diluents suitable for use in the process are well known in the art and include hydrocarbons which are inert liquids or supercritical fluids under the reaction conditions. Suitable hydrocarbons include isobutane, propane, n-pentane, isopentane, neopentane and n-hexane, with isobutane being particularly preferred. Alternatively, the liquid medium may be the unreacted monomer itself. For example, the present method and apparatus are also applicable to the polymerization of propylene in a loop reactor. In propylene bulk polymerization, there is no separate diluent for the monomer because the monomer (propylene) acts as the liquid medium. Of course, the concentration of olefin monomer is much higher than if a liquid medium is also present.

Suitable catalysts are well known in the art. Particularly suitable are chromia/supports such as silica catalysts such as are broadly disclosed in US 2825721 (March 1950) by Hogan and Banks, incorporated herein by reference. Ziegler catalysts, metallocenes and other well known polyolefin catalysts and cocatalysts can also be used. Preferably, only one catalyst is used for a given polymerization process, with the same catalyst being fed in each of the plurality of catalyst feed ports.

Additional details on loop reactor equipment and polymerization processes can be found in US 4,674,290, 5,183,866, 5,455,314, 5,565,174, 6,045,661, 6,051,631, 6,114,501 and 6,262,191, incorporated herein by reference.

In a loop reaction section where monomer is polymerized in a diluent to form solid polymer particles, the monomer concentration in the loop reaction section often varies as the fluid slurry flows along the loop reactor, at least in part due to the The desired result, conversion of monomers to polymers. As a general rule, as the length of the loop reaction section increases, there will often be a greater degree of variation in monomer concentration if the monomers are all fed into the loop reaction section at one location. For example, in an 18,000 gallon loop reactor for the slurry polymerization of ethylene, there are about 48,000 pounds (about 18,000 kilograms) of liquid with about 2,200 pounds (about 800 kilograms) of ethylene in the liquid. At a production rate of about 40,000 lb/hr (about 15,000 kg/hr), the process described consumes about 333 lbs (about 125 kg) of ethylene during the time that ethylene flows through the reactor loop. The ethylene concentration in the loop was calculated to be about 4.27% by weight before the ethylene feed inlet to about 4.93% by weight just after the ethylene feed inlet. A 35,000 gallon loop reactor may have the same diameter as an 18,000 gallon loop reactor, but be twice as long. At a production rate of about 88,000 lb/hr (about 33,000 kg/hr), the process described consumes about 1467 lbs (about 550 kg) of ethylene. The reactor contained about 93,300 pounds (about 68,300 kilograms) of liquid, including about 4,200 pounds (about 1,567 kilograms) of ethylene. In such a reactor, the concentration of ethylene in the loop reactor is calculated to be about 3.72% by weight before the ethylene feed to 3.72 wt. About 5.28% by weight. This constitutes a relatively wide variation in the ethylene concentration.

For some polyethylene products, such as copolymers with a melt index of 0.55 and a density of 0.9505, it is desirable to maintain the ethylene concentration from about 4 to about 5.5% by weight (it is determined that the range is 1.5% by weight). For other polyethylene products, such as high load melt index 15.5, density 0.9360 copolymers, it is desirable to maintain the ethylene concentration from about 1.7 to about 2.7% by weight (it is determined that the range is 1.0% by weight). For most polyethylene products, it is desirable to have an ethylene concentration in the range of about 0.65%, or about 0.85%, or about 0.95%, or about 1.05% along the reactor. Alternatively, it is desirable to operate the process such that at any point in the reactor the ethylene concentration is within the standard deviation of the mean ethylene concentration. Preferably, the standard deviation of the reactor's ethylene concentration is about 0.2%, or less than 0.3%, or less than 0.4%. The present method and apparatus are capable of providing and maintaining these desired ethylene concentrations.

A small amount of ethylene can also enter the reactor at the diluent flush point. Such a flush point does not serve as a "monomer feed". Flush points, including pump seals, catalyst feed points, product withdrawal points and pressure relief points, need to remain open for safe and reliable reactor operation, with little polymer accumulation in such openings. This flush may contain one percent ethylene, which is in the reactor flash gas and recycled to the reactor. The amount of ethylene recycled to the reactor with the recycled diluent is usually about 0 to 10%, typically 5%.

Excessive changes in ethylene concentration can slightly lower the maximum allowable operating temperature because the reaction rate is higher in reactor sections with higher ethylene concentrations than in reactor sections with lower ethylene concentrations. For example, in some places, the reaction rate may be about 30%. This approximation is based on the fact that the reaction rate is proportional to the concentration of monomer in the reactor. By using the present method and apparatus, the maximum operating temperature can be increased by approximately 3.0°F (1.7°C), and the polymerization process described can be operated at 218.5°F or higher for polymers with a maximum reactor temperature of 215.5°F . The maximum operating temperature is the temperature that causes the polymer to soften and foul the reactor, and it also depends on the type of polymer, the ability of the control system, and the ability of the reactor jacket to remove the heat of polymerization.

In contrast to the polymerization process disclosed in US 4789714, where an additional monomer feed is used to initiate the formation of a supplementary MWD regime, in the present method and apparatus an additional monomer feed can be used to prevent The molecular weight distribution of polyolefins prepared by the method does not change the level of expansion. This enables the production of the same high quality product in large reactors as in smaller reactors. The method and apparatus can be used to produce solid polyolefin particles having a unimodal molecular weight distribution.

Referring now to the drawings, FIG. 1 shows a loop reactor 10 having a primary section 12 , an upper secondary section 14 and a lower secondary section 16 . Secondary sections can be simple elbows connected to primary sections. Preferably, the lower secondary section is relatively curved to facilitate continuous withdrawal of product slurry. In Figure 1, the loop reactor has 8 main sections, although the inventors contemplate that the present method and apparatus may be used with a loop reactor with a greater or lesser number of main sections, for example a loop reactor with 4 branches or 12 paragraphs. It should be understood that the specific number of segments here does not necessarily imply that branch pipes are preferred, since the loop reactor is circular. Fig. 1 shows that the main sections are the first branch pipe 1, the second branch pipe 2, the third branch pipe 3, the fourth branch pipe 4, the fifth branch pipe 5, the sixth branch pipe 6, the seventh branch pipe 7 and the eighth branch pipe 8. The first to eighth branches are surrounded by cooling jackets 18 for heat exchange, ie removal of at least a portion of the heat of polymerization from the loop reactor and to provide a means of controlling the temperature of the loop reactor contents.

The upper and lower secondary segments determine the upper and lower segments of the secondary flow. Each section or branch is connected to the next section or branch by a smooth bend or bend 20, thereby providing a continuous flow path substantially free of internal obstructions. As shown in Figure 1, some of the upper and lower secondary sections may consist of smooth bends or bends such that the secondary sections form continuous bends. The fluid slurry is circulated by vanes (not shown) driven by motor 24 .

Preferably, the loop reaction section of the loop reactor has a volume greater than 20,000 gallons, more preferably greater than 30,000 gallons, most preferably greater than 35,000 gallons.

Monomer (which may be mixed with diluent) is fed into the reactor from one or more monomer sources 26, which may be fresh ethylene supplies, through two monomer feed ports (shown as conduit 30 connected to the loop reactor). recycle unreacted ethylene from the feedstock or slurry withdrawn from the reactor. Conduit 30 is fitted with a flow controller 32 which controls the amount of monomer fed to the loop reactor. The monomer feed can be any known device for feeding monomer into the reactor, such as a simple opening, nozzle, injector or other fluid distribution device.

As shown in Figure 1, two separate monomer control schemes are used to control two separate monomer feed ports. If only one control scheme is used to control multiple monomer feed ports, there is a danger of polymer buildup causing all monomer streams to pass through one feed port. The control scheme shown in Figure 1 controls the monomer feed to the loop reactor based on the monomer concentration measured in the slurry fraction withdrawn at the downstream withdrawal point. Alternatively, the monomer feed can be controlled based on the monomer concentration measured in the portion of the slurry withdrawn at the upstream withdrawal point or the average of the measured monomer concentrations in the slurry withdrawn at several withdrawal points. Alternatively, the monomer concentration in the flash gas can be measured after the two withdraw streams are combined. Alternatively, the monomer concentration can be measured directly at one or more points in the reactor.

Conduit 30 may be adapted to provide feedstock streams other than monomer, such as comonomer and/or make-up diluent. The flow control valve 32 is adjusted by a flow rate controller 38 which receives a control signal from a computer 42 . The analysis converter 40 is suitable for analyzing the slurry sample taken from the loop reactor, and sends the monomer concentration signal to the computer 42 according to the analysis of the monomer-containing stream. Computer 42 receives an input monomer concentration signal and optionally other input signals, such as an operator input representing a desired monomer concentration. Although two computers (one for each individual control flow) are shown in Fig. 1, a single computer capable of separately controlling two or more control flows may also be used. Separate control valves and circuits for each monomer feed are to ensure a constant split (50/50 in the case of 8 branches, symmetrical installation). Each controller need not act on the monomer concentration of a separate effluent.

As shown in Figure 1, the monomer feed port and the product feed port are installed symmetrically along the loop reactor. The advantage of this symmetrical setup is that the monomer concentration can be expected to be close to or exactly the same at each product intake (assuming roughly the same amount of monomer is fed to each feed and the loop reactor is functioning well) . It is easier to control the process if the monomer concentration at the product withdrawal is expected to be about the same.

Comonomer may also be fed through conduit 30 or another feed location. Preferably, multiple comonomer feed ports are installed symmetrically along the loop reactor, and the control flow is partially similar to (or added to) the control flow shown for the monomer feed.

Catalyst is fed into catalyst feed ports 44 through conduits which provide a stage (location) for catalyst feed. In the embodiment shown in Figure 1, the catalyst feed ports 44 are also located symmetrically along the reactor. Alternatively or additionally, the method and apparatus for preparing catalyst slurry and providing it to the loop reaction (polymerization) section disclosed in US 6262191 (previously incorporated by reference) may be used with the present method and apparatus.

The dashed lines are the signal lines in the figure, which in this preferred embodiment are electrical or pneumatic signal lines. However, mechanical, hydraulic or other signaling devices for conveying information are also suitable. In almost all control schemes, some combination of these signal types will be used. However, the use of any other type of signal delivery that is compatible with the method and apparatus being used is within the scope of the present invention.

The loop reactor plant of Fig. 1 also includes means for withdrawing a portion of the slurry from the reactor (product take-off). The equipment used to withdraw the slurry portion may be a settling leg, a hollow attachment for continuous withdrawal, or other conduits for withdrawing the product slurry without significant leakage or interference with the operation of the loop reactor. Settling legs have long been used in this field and are disclosed in US 3293000 and 4613484, incorporated herein by reference. In the embodiment shown in FIG. 1 , the elongated hollow attachment for continuous withdrawal of the intermediate product slurry is indicated by parameter 34 . The continuous reclaimer 34 is located at or near a lower horizontal reactor loop section 16 and/or near or at the connecting elbow 20 . Additional details regarding the continuous reclaim mechanism are disclosed in US 6,239,235 to Hottovy et al., incorporated herein by reference.

The withdrawn slurry portion is sent through conduit 36 to equipment for separating solid polyolefin particles from diluent and unreacted monomer. Conduit 36 may comprise an outer conduit containing a heating fluid that provides indirect heating to the product slurry in conduit 36 . Such a configuration is called flash line heating. The separation of solid polyolefin particles using a two-stage flash design is broadly disclosed, for example, in Hanson and Sherk US 4,424,341 (January 3, 1984), incorporated herein by reference. Using such a design, typically 70-90% or more of the diluent is expected to be recovered in a high pressure flash.

For example, in a vessel, the polymer (fluff) collects by gravity at the bottom, and the diluent and unreacted monomer and comonomer are separated and drained at the top. The vessel is operated at a sufficiently high pressure that substantially all of the vented vapors can be condensed with cooling water and pumped back to the reactor. The vaporized monomer diluent can be further processed, including condensing by simple heat exchange with a recycle condenser, and then returned to the system through a recycle diluent line without compression. Recycled monomer may be returned to monomer source 26 .

Example

Example 1

18,000 gallon loop reactor for slurry polymerization of ethylene. The pipes forming the loop reactor had a nominal diameter of 24 inches and an overall length of about 860 feet. There are about 48,000 pounds (about 18,000 kilograms) of liquid, of which about 2,200 pounds (about 800 kilograms) of ethylene in the liquid. At a reactor production rate of about 40,000 lb/hr (about 15,000 kg/hr), the reactor consumes about 333 lbs (about 125 kg) of ethylene in the time required for ethylene to flow down the reactor loop. The concentration of ethylene in the loop reactor was about 4.27% by weight (2200 lbs ethylene - half of 333 lbs, divided by the 48,000 lbs liquid content in the reactor) just before the ethylene feed to 4.93% just after the ethylene feed (weight) (2200 lbs ethylene + half of 333 lbs, divided by 48000 lbs liquid content in reactor).

Example 2

35,000 gallon loop reactor for slurry polymerization of ethylene. The reactor described had the same diameter as the 18,000 gallon loop reactor of Example 1 but was twice as long. The reactor has only one ethylene feed port. The reactor contained about 85,916 pounds (about 62,900 kilograms) of liquid, including about 3,437 pounds (about 1,282 kilograms) of ethylene. The reactor produced approximately 87,500 lb/hr of polymer. It takes approximately 48 seconds for the slurry to flow through the entire 35,000 gallon loop reactor. In 60 seconds, the reactor consumed about 1458 pounds (about 547 kilograms) of ethylene. In the reactor described, the ethylene concentration in the loop reactor was about 3.32% by weight (3437 lbs ethylene - half of 1167 lbs divided by 85916 lbs) just before the ethylene feed to just after the ethylene feed That's about 4.68% (3437 lbs ethylene + half of 1167 lbs, divided by 85916 lbs).

Example 3

Table 1 lists the reactor characteristics and process characteristics for ethylene polymerization of the 35,000 gallon loop reactor shown in Figure 1 . The input columns refer to the values selected by the operator of the loop reactor; the output columns refer to the values determined using the input values and the properties of the reactor and process. Tables 2 and 3 provide material balance calculations for ethylene polymerization with one monomer feed and two monomer feeds, respectively.

Table 1 Reactor and process characteristics

enter output Reactor size Shell inner diameter inch 22.0625 - flow area square feet - 2.6548 Branch length foot 1,616 - Number of elbows 16 - Elbow radius foot 6.00 - Elbow length foot - 9.42 total reactor length foot - 1,756 Reactor volume gallon 35,116 - pump part properties Reactor solids %(weight) 48.0% - Reactor temperature f 214.0 - Particle solids volume fraction 0.91 - solid density ml/g 0.9540 - lb/ ^ft3 - 59.50 Reactor Fluid Density ml/g - 0.409 lb/ ^ft3 25.56 - Reactor slurry density lb/ ^ft3 - 35.1965

Table 1 (continued)

Reactor CTO discharge productivity lb polyethylene/hour 87,500 - CTO solid %(weight) 50.0% - CTO ethylene %(weight) 4.0% - Slurry discharge rate lb/h - 175,000 liquid discharge lb/h - 87,500 Ethylene emissions lb/h - 3,500 Reactor Feeds and Materials Ethylene feed (assuming homopolymer) lb/h - 91,000 circulating liquid feed lb/l - 84,000 Reactor slurry volume pound - 165,224 Reactor liquid volume pound - 85,916 Reactor solids pound - 79,308 Reactor Ethylene pound - 3,437

Table 1 (continued)

Reactor Cycles and Reactions reaction speed lb/min 1,458 Reaction cycle rate g/min 43,800 Reaction cycle rate ^ft3 /min 5,856 speed ft/min 2,205 revolutions per minute rpm 1.25 Effective length of branch pipe FOTO-WEAR 221 The response of each tube lb/min 182

Table 2 shows calculated values for a 35,000 gallon loop reactor in which ethylene monomer was fed into the reactor through a monomer feed just after the pump. The rightmost column shows that the concentration of ethylene in the fluid slurry varied from 3.35% to 4.64%, with a range of 1.11%, a mean of 3.73%, and a standard deviation of 0.41%.

Table 2. Material balance calculation for a loop reactor with one monomer feed point

Vinyl Isobutane (all other liquids) all liquid Polyethylene All slurry solid Vinyl lb/min lb/min lb/min lb/min lb/min %(weight) %(weight) Pump 3,589 103,574 107,163 98,920 206,083 48.00% 3.35% Feed (1.29%) 1,517 1,400 2,917 Branch 2 inlet 5,106 104,974 110,080 98,920 209,000 47.33% 4.64% Branch 3 inlet 4,923 104,974 109,898 99,102 209,000 47.42% 4.48% branch pipe 3 outlet 4,741 104,974 109,715 99,284 209,000 47.50% 4.32% CTO 31.5 697.7 729.2 729.2 1,458.3 50.00% 4.32% branch pipe 4 inlet 4,710 104,277 108,986 98,555 207,541 47.49% 4.32% Branch pipe 5 inlet 4,527 104,277 108,804 98,738 207,541 47.57% 4.16% Branch pipe 5 outlet 4,345 104,277 108,621 98,920 207,541 47.66% 4.00% Feed (0%) 0 0 0 Branch 6 inlet 4,345 104,277 108,621 98,920 207,541 47.66% 4.00% Branch pipe 7 inlet 4,163 104,277 108,439 99,102 207,541 47.75% 3.84% branch pipe 7 outlet 3,980 104,277 108,257 99,284 207,541 47.84% 3.68% CTO 26.8 702.4 729.2 729.2 1,458.3 50.00% 3.68% Branch pipe 8 inlet 3,954 103,574 107,528 98,555 206,083 47.62% 3.68% Branch 1 inlet 3,771 103,574 107,345 98,738 208,083 47.91% 3.51% branch pipe 1 outlet 3,589 103,574 107,163 98,920 206,083 48.00% 3.35%

Table 3 shows calculated values for a 35,000 gallon loop reactor in which ethylene monomer is fed into the reactor through two monomer feed ports, one just after the pump and the other just after the bottom of the fifth reactor leg . In the described reactor, the ethylene feed port and the product take-off port (CTO) are installed symmetrically. The rightmost column in Table 3 shows that the concentration of ethylene in the fluid slurry varied from 3.67% to 4.32%, with a range of 0.65%, a mean of 3.74%, and a standard deviation of 0.21%.

Table 3 Material balance calculation for a loop reactor with two monomer feed points

Vinyl Isobutane (all other liquids) all liquid Polyethylene All slurry solid Vinyl lb/min lb/min lb/min lb/min lb/min %(weight) %(weight) Pump 3,937 103,227 107,163 98,920 206,083 48.00% 3.67% Feed (0.65%) 758 700 1,458 Branch 2 inlet 4,695 103,927 108,621 98,920 207,541 47.66% 4.32% Branch 3 inlet 4,513 103,927 108,439 99,102 207,541 47.75% 4.16% branch pipe 3 outlet 4,330 103,927 108,257 99,284 207,541 47.84% 4.00% CTO 29.2 700.0 729.2 729.2 1,458.3 50.00% 4.00% branch pipe 4 inlet 4,301 103,227 107,528 98,555 206,083 47.82% 4.00% Branch pipe 5 inlet 4,119 103,227 107,345 98,738 206,083 47.91% 3.84% Branch pipe 5 outlet 3,937 103,227 107,163 98,920 206,083 48.00% 3.67% Feed (0.65%) 758 700 1,458 Branch 6 inlet 4,695 103,927 108,621 98,920 207,541 47.66% 4.32% Branch pipe 7 inlet 4,513 103,927 108,439 99,102 207,541 47.75% 4.16% branch pipe 7 outlet 4,330 103,927 108,257 99,284 207,541 47.84% 4.00% CTO 29.2 700.0 729.2 729.2 1458.3 50.00% 4.00% Branch pipe 8 inlet 4,301 103,227 107,528 98,555 206,083 47.82% 4.00% Branch 1 inlet 4,119 103,277 107,345 98,738 206,083 47.91% 3.84% branch pipe 1 outlet 3,937 103,227 107,163 98,920 206,083 48.00% 3.67%

Tables 2 and 3 (especially the calculated ethylene concentrations in the last column of each table) demonstrate that the use of a system with two monomer feeds results in a more consistent monomer concentration in the loop reactor.

While this invention has been described in detail for purposes of illustration, it should not be construed as limiting but intends to cover all variations that come within the spirit and scope of the invention.

Claims (20)

1. slurry polymerization process that in liquid diluent, generates solid polyolefin particles, described method comprises:

Liquid diluent is sent into loop reaction zone;

Catalyzer is sent into loop reaction zone, and described catalyzer can make described olefinic monomer polymerization;

Olefinic monomer is sent into loop reaction zone by a plurality of monomer feed, wherein add olefinic monomer so that the concentration of olefinic monomer in loop reaction zone in required scope;

With the olefinic monomer polymerization, in liquid diluent, generate the fluid slurry of solid polyolefin particles; And

Take out a part of fluid slurry as intermediates.

2. according to the process of claim 1 wherein that catalyzer sends into by a plurality of catalyst feeds.

3. according to the process of claim 1 wherein that described fluid slurry is partly by a plurality of product material taking mouths taking-ups.

4. according to the method for claim 3, wherein monomer feed and product material taking mouth are installed along the loop reaction zone symmetry.

5. according to the process of claim 1 wherein that required scope is 1.05% or littler.

6. according to the process of claim 1 wherein that described a plurality of monomer feed is that per 800 feet reactor length have at least one monomer feed.

7. according to the process of claim 1 wherein that described a plurality of monomer feed is that per 18000 gal reactor volumes have at least one monomer feed.

8. according to the process of claim 1 wherein that described fluid slurry has a plurality of monomer concentrations along loop reaction zone, the standard deviation of described a plurality of monomer concentrations is equal to or less than 0.4%.

9. according to the method for claim 1, also comprise following steps: measure the olefinic monomer concentration of the segment fluid flow slurry that takes out and the olefinic monomer of sending into according to the concentration adjustment of measuring.

10. according to the method for claim 9, wherein regulate the olefinic monomer of sending into, so that the olefin monomer of sending into a monomer feed is different with another monomer feed.

11. according to the process of claim 1 wherein that the volume of described loop reaction zone is greater than 20000 gallons.

12. according to the process of claim 1 wherein that the volume of described loop reaction zone is greater than 30000 gallons.

13. according to the process of claim 1 wherein that the volume of described loop reaction zone is greater than 35000 gallons.

14. separately control described each monomer feed according to the process of claim 1 wherein.

15. according to the process of claim 1 wherein that described solid polyolefin particles has unimodal molecular weight distribution.

16. a loop reactor apparatus, described equipment comprises:

A plurality of major sections;

A plurality of upper minor sections;

A plurality of lower minor segments;

Wherein each described major section links to each other with a described upper minor section in the upper end, and link to each other with a described lower minor segments by level and smooth lower bend in the lower end, so that described major section and described minor segment form the continuous runner that is applicable to the conveyance fluid slurry;

At least two equipment that are used for olefinic monomer is sent into continuous runner;

An equipment that is used for polymerizing catalyst is sent into continuous runner; And

At least two equipment that are used for taking out a part of fluid slurry from continuous runner.

17. according to the loop reactor apparatus of claim 16, also comprise the equipment of at least one fluid slurry that is used for measuring taking-up part olefinic monomer concentration, described metering facility links to each other with the described material equipment fluid of getting.

18., also comprise one and be used to control the equipment that described monomer is sent into equipment, and described metering facility will represent that the signal of described measurement concentration offers described operating device according to the loop reactor apparatus of claim 17.

19. according to the loop reactor apparatus of claim 16, described equipment comprises:

First primary branch; Second primary branch; The 3rd primary branch; The 4th primary branch; The 5th primary branch; The 6th primary branch; The 7th primary branch and the 8th primary branch; A plurality of minor segment, each section is connected to each other with two described primary branches, thus described arm and described section are a continuous runner;

First monomer feed that links to each other with described first primary branch;

The first product material taking mouth that links to each other with described the 3rd primary branch;

Second monomer feed that links to each other with described the 5th primary branch;

The second product material taking mouth that links to each other with described the 7th primary branch; And

At least one catalyst feeds that links to each other with a described arm or section.

20. according to the loop reactor apparatus of claim 19, comprise first and second catalyst feeds, wherein:

Described first and second monomer feed are along runner symmetry installation continuously;

The described first and second product material taking mouths are along runner symmetry installation continuously; And

Described first and second catalyst feeds are along runner symmetry installation continuously.

Images