CN1033978C - Improvements in fluidized bed polymerization reactors - Google Patents

Abstract

The present invention discloses a fluidized bed reactor and an operation method thereof. The reactor comprises a gas distributing board for causing a gas which upward flows into a fluidized bed to reach uniform distribution, a mixing chamber arranged below the distributing board, a gas inlet device preferably arranged at the bottom of the reactor for causing the gas to flow into the reactor, a fluid director mutually connected with the inlet device for providing at least a directly upward airflow channel and an outward airflow channel along the wall of the mixing chamber, in this way, the accumulation of solid particles and liquid in the mixing chamber is prevented.

Description

The working method of fluidized-bed polymerization reactor and polymerization technique

The present invention relates to fluidized-bed polymerization reactor, relate to the improvement of fluidized-bed polymerization reactor and the improvement that the air-flow of introducing this class reactor is distributed or rather.

The invention of fluidized-bed process, for the production of polymkeric substance provides a kind of method of making variety of polymers, the polyolefins of polyethylene etc. for example.And, to compare with traditional technology, fluidized-bed process can reduce initial cost and energy consumption significantly.Yet, when carrying out the polyreaction of heat release, to limit to some extent so that make liberated heat be able to do in time from fluidized-bed, to migrate out speed of reaction with fluidized-bed reactor.

In the fluidized-bed reactor technology of routine, the method for the most common and the most the most frequently used transfer heat is that the somewhere outside reactor is compressed circulating current and cool off.At the technical scale fluidized bed reaction system that is used for producing such as polymkeric substance such as polyethylene, be used for the required circulation gas flow of transfer polymerization reaction heat to be greater than to supporting the fluidized-bed fluidisation and for making the required airshed of solids thorough mixing in the fluidized-bed.Yet, must the gas velocity in the reactor be limited, in case the fluid stopping oxidizing gases is taken away too much solid particulate when outflow reactor.Therefore, be used for shift reaction heat and carry out the round-robin airshed and similarly be restricted.

A kind of method that improves the reaction heat transfer rate is compressed the gas that is free state that need loop back reactor and cooled off, and makes it to take place the condensation of part.The monomer air-flow that those liquid that produced are recycled is carried secretly and is turned back in the reactor thereupon.This operation is referred to as the polyreaction methodology of " condensation mode ".What disclose this method at first is Application No. 361,547, and the applying date is March 24 nineteen eighty-two, approximately at the same time, people such as J.M.Jenkins have applied for that also (act on behalf of case number and be D-13,475-2), its exercise question is " improving one's methods of fluidized bed polymerization process " to United States Patent (USP).These two parts of files are listed, for your guidance herein.As being announced, make the working method of this condensation mode can reduce the temperature of circulating current, and because evaporation of liquid will absorb heat, the combination of these two kinds of effects, the space-time yield of " non-condensing pattern " working method that makes the space-time yield of this technology be higher than significantly, in a kind of method in back, the temperature of circulating current is maintained at it more than dew point, and so-called dew point is meant and begins the temperature that has condenses to come out in this air-flow.

The test-results of carrying out with a scaled reactor bottom device and all show by the experience that plant-scale polymerization reactor obtained, the reactor inlet of open nozzles formula is suitable for the operation of the condensation mode of fluidized-bed reactor, and the reactor inlet of standpipe/taper hat type is suitable for the operation of the non-condensing pattern of reactor.The inlet of standpipe/taper hat type is not suitable for the operation of condensation mode, and this is owing to liquid flooding takes place or produce bubble at reactor bottom, if the content liquid in the circulating current is relatively low when using industrial reactor this phenomenon will take place.On the contrary, the open nozzles inlet is not suitable for the operation of the non-condensing pattern of industrial reactor, and this is because in the bottom of reactor, and too much resin solid agglomeration of particles especially takes place around the ingress.

In the real-world operation process of large-scale commercial production reactor, wish sometimes a kind of working method of non-condensing pattern is changed into the working method of condensation mode or carried out opposite change.In view of above-mentioned reason, in technology in the past, reactor must be stopped in order to carry out this conversion, inlet device is more changed in the hope of meeting the requirement of new model working method.It is worthless that this parking is changed, and this is not only because this repacking will make maintenance cost increase, and parking also can cause serious production loss.For some industrial reactor, according to its art production process, conversion inlet device continually possibly.Therefore, the hope acquisition is a kind of consumingly can satisfy the condensation mode of reactor and the multi-purpose reactor inlet device of these two kinds of working method of non-condensing pattern simultaneously.

The objective of the invention is: (1) improves the production efficiency of fluidized-bed reactor, (2) reduce the maintenance cost and/or the productive expense of this class reactor, (3) give this class reactor a kind of handiness, make it produce diversified polymkeric substance and can not cause the production loss that causes owing to stopping with the production efficiency higher than routine techniques, the example of the said polymer has ethene and heavy alpha-olefinic polymer (multipolymer and terpolymer) and propene polymer (homopolymer and segmented copolymer or random copolymers).Director of the present invention can reach these purposes, this is by means of a kind of multiduty reactor inlet device, thereby has eliminated the accurate defect that just must make reactor shutdowns when changing into the working method of non-condensing pattern (or opposite) by condensation mode.

According to the present invention, a kind of like this fluidized-bed reactor has been proposed, a grid distributor is installed below its fluidisation section, this grid distributor becomes a mixing section with the below space boundary of grid distributor in the reactor, and one or more air flow inlet devices are arranged, so that gas is introduced reactor and is passed through mixing section.The below that has at least a director to be installed in grid distributor also is connected with an inlet device at least.Said director can provide two gas channels that allow gas enter mixing section at least, promptly along first gas channel that mixes locular wall and second gas channel that directly makes progress, in operating process, in second gas channel or just entering wherein solids and carried secretly up by air-flow and flow; Mix locular wall by airflow scouring, therefore prevented the gathering of said solids; Prevented also that simultaneously liquid from assembling in mixing section.

Preferable director is a kind of annular director, a perforation is arranged so that a upwards gas passage at the center to be provided in the middle of it, and it also provides one around around the director and along the peripheral gas channel that mixes locular wall.When operating with this director, the gas that enters mixing section feeds a mouthful device and is separated, and forms two gas channels, promptly by the gas channel of perforation with by the peripheral annular gas channel between director and the mixing locular wall.

The accompanying drawing summary:

Fig. 1 is used for making various monomers to carry out the synoptic diagram of the preferable system of continuous fluidized bed polyreaction according to of the present invention;

Fig. 2 is the cross-section elevation of reactor bottom, comprising grid distributor, mixing section and director;

Fig. 2 A is the vertical view of the director cut open along 2A-2A line among Fig. 2;

Fig. 3 is the upright enlarged view of looking in the cross section of inlet device among Fig. 2 and director;

Fig. 4 is the vertical view of the grid distributor cut open along 4-4 line among Fig. 2, the arrangement mode of cap shown in it on grid distributor;

Fig. 5 is the cross-section elevation of reactor inlet part, a kind of variation pattern of the director shown in it among Fig. 3;

Fig. 6 is the cross-section elevation of reactor inlet part, and the another kind of director shown in it changes pattern.

In the continuous fluid bed polymerizing reactor, distribution grid be installed in fluid bed below, its supporting The bed material of fluid bed and make gas in the whole cross section of fluid bed uniform distribution be arranged. Distribution grid Also play a kind of boundary face, it is defined as a mixing to the space reactor of distribution grid below The chamber. When air-flow passed the aperture of distribution grid from the fluid bed bottom, the major function of mixing chamber was to protect Card gas and the condensed fluid wherein carried secretly (if any words) have at the whole cross section of mixing chamber Distribute uniformly. Usually, in the operating process of condensation mode, at the circulating current Returning reactor Can isolate some liquid of carrying secretly on the inner surface of the conduit that is passed through (mainly due to circulation is led Due to the inertial collision of tube wall). For the situation of carrying secretly and distributing is reached fully evenly, The very important point be want so that in mixing chamber isolated liquid again carried secretly with mixed. For this reason, must so that air-flow when entering fluid bed by distribution grid, can be evenly distributed fully. This The guiding device of invention can provide this required distribution effect.

In better embodiment of the present invention, shown in the arrow of Fig. 2 and Fig. 3, circulating air Stream is divided into two strands, and one is directly making progress by annular air deflector (annular disk) central hole Air-flow, another strand are the peripheral air streams by annular air deflector peripheral space. The peripheral air stream of annular Peripheral space by annular air deflector also washes away the mixing locular wall, has therefore prevented solid material (tree Fat) assemble at wall. Be appreciated that and in circulating current, usually be entrained with a small amount of solids Material. Just as shown by arrows, the air-flow of center updraft and periphery mixes, thereby has guaranteed Any liquid in the air-flow and/or solid matter reach required more uniform distribution.

The technological parameter of listing in the table has below been described to obtaining the applicable elements of required flow behavior.

Table 1

Scope preferred values (1) 0.1≤A ₂/ A ₁A in≤0.75 0.3 formula ₁=along mixing the area (side opening area) that locular wall mobile gas is passed through, hereinafter this passage is called first gas channel

A ₂The area of=the perforation that central gas stream passed through up is called second gas channel with this passage hereinafter, wherein, and for the preferable annular director among Fig. 2 and Fig. 3:

The diameter of di=central hole in the formula; Side opening area=π doh wherein do is the external diameter of annular director, and h is to the minor increment of mixing locular wall from the minimum outer rim of annular disc.

When giving a definition for the side opening area, do such supposition, promptly with respect to transitable that part of area in " side opening " area, support or the occupied area of title spacer 32a (consulting Fig. 2 and Fig. 3) are very limited negligible in other words conj.or perhaps, therefore it can be ignored when handling the above-mentioned relation formula.That is to say, in Fig. 2 and better model shown in Figure 3, the spacer very little part of side opening area that only accounts for.

Preferred values

Z is the horizontal direction distance from inlet tube top preglabellar field top to director in 2 formulas, wherein, concerning the annular director of Fig. 2 and Fig. 3 is: $0.5\≤\frac{\mathrm{do}-\mathrm{de}}{2h}\≤5,$ Because Z is for annular director Wherein do is person as defined above, and de is the diameter (is inlet tube or claims circulation line 22 at Fig. 2) of inlet device.

Preferred range (3) Hv＞344.74 handkerchiefs, Hv＞1378.95 handkerchiefs, Hv is based on the velocity head that total flow area of director calculates in the formula, and the definition of the total flow area of director is the summation of following two areas: promptly add the area of the perforation of conduct second gas channel that passes through towards overdraught along the sectional area (being the side opening area) of first gas channel that mixes locular wall, wherein $\mathrm{Hv}={\mathrm{\ρGV}}_G^2/9266**$ (sectional area (A) of * * perforation should not surpass inlet device sectional area about 2/3).ρ g is (* 16.02 kilograms/meter of gas densities in the formula ³); VG is gas velocity (* 304.80 mm/second), and its definition is:

V _G=144W _G/ A _Dρ g, W in the formula _GBe the mass flow rate that enters the gas of director, for the system of Fig. 2 and Fig. 3, the total current area of director is A _D=π di ²/ 4+ π doh.

Must be pointed out, for simplicity, di, do and h measure (1 meter=39.37 inches) with inch.

Under such operational condition, the synthesis rate and the relative mass flow rate of central gas stream and annular flow (or claiming peripheral air-flow), can guarantee the tight mixing of air-flow and guarantee by droplets entrained and solids enter fluidized-bed and by the upward air stream of grid distributor in continue to be suspended.Have been found that under such condition the state that drop and solids are separated is can be not persistent from the air-flow of carrying them secretly.In mixing section, undesirable liquid flooding had not both taken place, the gathering of solids (resin) does not take place again, and both of these case can be broken away from all and be carried secretly state and caused by drop and solids.

According to the present invention, the two mutual relationship aspect mass flow rate and gas velocity two of locular wall air-flow is mixed on maintenance center upward air stream and edge, obtains the required suitable air-flow in two air-flow approach and makes the mixing in the mixing section reach desired degree with this.

The aspect ratio of mixing section generally can be up to 1.5, and are preferably about 0.7 to about 1.0.Equally, the ratio of the gas inlet device of mixing section diameter and reactor (inlet or conduit) diameter generally should be less than or equal to about 10: 1, and preferred range is from about 5: 1 to about 8: 1.

In addition, in the operation of condensation mode, in mixing section the superfacial velocity of gas (Um) with at the gas end speed (U of mixing section bottom ₁) ratio (as the following definien of institute) preferably be at least 0.18: 1.

Um/U ₁Ratio be at least 0.18: 1, so just can reduce in generation liquid flooding of mixing section lower region or blistered possibility.Um represents the superficial gas velocity in the mixing section, and U ₁Represent critical gas flow velocity, just when surpassing this speed, by droplets entrained just by finely divided and these drops are being carried secretly upwards by air-flow flow.Critical gas flow velocity can be expressed (identical unit is arranged) with following formula on dimension:

U ₁＝2.0(gσ ₁Δρ/·ρg ²) ^0.25，

In the formula: g is a universal gravity constant;

σ ₁It is surface tension of liquid;

Δ ρ is the density difference of liquids and gases;

ρ g is the density of gas.

In the operation of condensation mode, generally definite, the shared weight percentage of condensed fluid that is entrained in the circulating current can reach 0.2 (20% weight), is preferably 2-10% (weight), and concrete per-cent depends on the concrete polymkeric substance of being produced.

To explain the fluidized bed reaction system that is particularly suitable for producing the polyene resin of the present invention with accompanying drawing below.As seen from Figure 1, reactor 10 comprises a conversion zone 12 and a braking section 14.

In general, the aspect ratio of conversion zone is in 2.7: 1 to 4.6: 1 scope.It is bigger or littler that this scope may become, and this depends on required throughput.The sectional area of braking section 14 is generally about 2.6 to about 2.8 times of conversion zone 12 sectional areas.

Conversion zone 12 comprises the growth bed of a polymer particle, and the pioneer that formed polymer particle and in a small amount part or all of have activated forms and/or catalyzer (below be referred to as catalyzer).They are all passed through conversion zone and fluidisation by the gaseous fraction continuous flow of polymerisable and modification with the form of compensation or circulating liquid.In order to keep a persistent fluidized-bed, must make superficial gas velocity (SGV) surpass the required lowest speed of rheomorphism by this bed, this lowest speed is about the 60.96-152.40 mm/second usually.Usually should make SGV exceed 5.08 mm/second than the needed lowest speed of fluidisation at least, just should make SGV usually is the 121.92-213.36 mm/second.Under normal circumstances, SGV is no more than 1524 mm/second, and commonly used be to be no more than 762 mm/second.

Particle in fluidized-bed can prevent to form in the part " focus " and with the catalyst pellets muon capture and impel it in entire reaction section distributed uniform.Therefore, when starting, must pack into earlier in the reactor, and then feed fluidizing agent as the polymer based particle.These particles can be identical or different with the polymkeric substance of need preparation.Not not simultaneously, they are then discharged from fluidized-bed as firstling with the required polymer particle of new formation.Fluidized-bed when at last, just having replaced starting fully by the molecular fluidized-bed of required polymer beads.

Used catalyzer generally is oxysensible, and the catalyzer that therefore is used for producing polymkeric substance in fluidized-bed preferably is stored in the container 16, and uses this catalyzer to inert gasses as protective atmosphere, for example nitrogen or argon gas.

Fluidized bed material since the circulating current of higher rate from wherein by being fluidized, the speed of recycle gas is about 50 times of raw material supply gas velocity usually.Because fluidizing agent seepage flow is crossed fluidized-bed layer, thereby can make the material that presents intensive shape in the bed become the particle of single-unit activity.Pressure by bed falls and is generally equal to or is a bit larger tham the sectional area of the weight of bed material divided by fluidized-bed, and this will depend on the geometrical shape of reactor.

Gas in interface 18 places supply enters reactor assembly by pipeline 22.The composition of circulating current is measured with a gas-analysis apparatus 21, regulates the composition and the consumption of supply gas then according to analytical results, therefore just can keep a stable basically gaseous constituent in fluidized-bed.

Used gas-analysis apparatus is a kind of gas-analysis apparatus of routine, and the working method of its available routine is measured the composition of circulating current, and can be regulated charging in view of the above, and this analyzer is very easy to be buied from market.Gas-analysis apparatus 21 can be installed in certain point between braking section 14 and the heat exchanger 24 so that to gas sampling, preferably it is installed between compressor 30 and the heat exchanger 24.

If necessary, can join other additive the circulation line 22 by pipeline 40 from a suitable dispenser 38.

In order to guarantee sufficient fluidisation, circulating current, or add part supply air-flow where necessary, by inlet 26 Returning reactors of circulation line 22 below bed.There is a gas distribution grid 28 top that is preferably in the air-flow reentry point to impel a materials flowization even, supports solids in the time of simultaneously can be at prestart or at system shutdown.The reaction heat that reaction was produced with regard to absorbing polymer when air-flow made progress by bed.

That part of gas that does not react in bed when air communication is crossed fluidized-bed will become circulating current, this air-flow leaves conversion zone 12 and enters the braking section 14 of bed top, most of herein the landing by entrained particles returns in the fluidized-bed, therefore reduced the amount of carrying secretly of solids.

Under general condition, be used for producing resin, conventional fluidized-bed process during particularly from monomer production polymkeric substance is implemented by following step, promptly under reaction conditions, contain one or more monomeric air-flows continuously by fluidized-bed reactor, and the speed of this air-flow should be enough to make the bed of solids to keep suspended state with following of the condition that has catalyzer to exist.The air-flow that contains unreacted gaseous monomer is discharged from reactor continuously, its compression, cooling and recirculation are returned in the reactor.Product is taken out and monomer is added to the circulating current from reactor.For the bed material that makes fluidized-bed keeps suspended state.Must make one air-flow with certain speed by fluidized-bed reactor, in this process, the solids in the bed have seldom a part and are taken out of reactor by air-flow, this strand air-flow returns recirculation to reactor.Since these particles be heat and contain catalyzer, therefore carried secretly when passing through the recycle system when their quilts, they will with further reaction and the continued growth of the gas of free state, this will make these particles depositions and be agglomerated into solid piece or be bonded to circulation line and the inwall of heat exchanger on.May cause the obstruction of circulation line or heat exchanger at last and have to parking.Therefore, very important point is to make the solids amount of being carried secretly in the circulating current into drop to minimum level as far as possible.

Though in fact can manage to overcome fully the entrainment problem of solids, its cost is to increase maintenance and the process cost that has also therefore increased these utility appliance with the investment of hand utility appliance (for example cyclonic separator) greatly.If only carry very a spot of solids secretly in circulating current, that is easy-to-handle, therefore, would rather allow very a spot of solids to be carried secretly rather than will be fully with its elimination.Yet according to task of the present invention, in the working method of condensation mode, the problem of so-called " mud " can allow, and this will go through hereinafter.

Because polyreaction is heat release, therefore when carrying out polyreaction, must keep a kind of like this mode, promptly not only to be lower than the decomposition temperature of resin and catalyzer, and will be lower than the fusing and the agglutinating temperature of the resin that is generated in the gas flow temperature of inside reactor.Must prevent the reactor plugs of growing up rapidly and causing owing to the polymer blocks grain, this polymer blocks grain can't emit as product in a continuous manner.Therefore very clear, in the fluidized-bed reactor of a given volume, the at the appointed time interior amount of polymer that can produce is directly related with the heat that can remove from fluidized-bed.

When carrying out the operation of condensation mode, wittingly circulating current be cooled to its below dew point so that it forms a kind of mixture that includes liquid and gas, this mixture also can allow to contain very a spot of solids.

When carrying out the operation of condensation mode, be to improve of the removal of circulating current dew point wittingly in some example with further raising heat.The method that improves circulating current is: (1) improves the working pressure of reactive system, and (2) improve the concentration of condensable gases in circulating current, and/or (3) reduce the concentration of uncondensable gas in the circulating current.For example, can all be in the inert condensable gases adding circulating current catalyzer, reactant and polymeric reaction product, improve the dew point of circulating current whereby a kind of.The said gas that is added in the circulating current can add or add with any other device or any other position in this system with supply gas.The example of this class gas has stable hydrocarbon such as butane, pentane or hexane.

The major limitation of this method is the refrigerative degree, promptly should make circulating current be cooled to it below dew point, makes gas/liquid ratio keep such numerical value again, makes the liquid phase in the mixture flow remain on the state of being carried secretly or suspend, till this liquid evaporates fully.Also must make simultaneously the upward air stream speed of gas distribution grid top be enough to make fluidized-bed to maintain suspended state.

Content liquid in the circulating current can be quite high, but when air communication is crossed grid distributor usually the condensed fluid content in gas phase should not surpass 20% (weight), (gross weight with circulating current is a radix).And when being lower than 2% (weight), the content of liquid just is difficult to obtain favourable result.

When carrying out the operation of condensation mode, if solids are being carried secretly from reactor by air-flow, the very important point is to make the liquid in the circulating current reach certain content in the case, makes it be enough to prevent the formation of " mud ".Undesirable " mud " can be owing to solids humidification, coalescent and break away to carry secretly and assemble and be deposited on that position relatively low in the system somewhere of heat exchanger and circulation line (for example) forms.Solids that the air-flow that comes out from reactor is carried secretly normally seldom for example can be 0.1-0.5% (weight) (in the fluid gross weight).Yet, also bigger content can appear, according to appointment 1% (weight) or higher sometimes.Because can cause the liquid that forms mud is variablely (can believe to the ratio of solids to a certain extent, at least to a great extent relevant with the shape and the size-grade distribution thereof of particle), therefore, in order to prevent to generate mud, should the liquid-solid ratio in the circulating current be maintained more than 2 to 1, preferable more than 5 to 1, best more than 10 to 1.Adopt last higher like this ratio taking place playing a kind of provide protection under the not normal situation of operation, not normally cause moment to have relatively large solids to be taken out of reactor by air-flow because operate.

Superfluous liquid can prevent solids any position gathering in system, if there is not the deposition that solids just might take place superfluous liquid.In addition, Guo Sheng liquid also can wash away system totally.When the content liquid in entering the round-robin air-flow maintains this required scope of 2-20% (weight), liquid-solid ratio just can not take place drop to situation below 2 to 1.When carrying out the operation of non-condensing pattern, in circulating current, do not have liquid or only contain very a spot of liquid, at this moment the liquid-solid ratio in circulating current is just unimportant, because at this moment solid can be by not moistening significantly, so just can not produce the problem that forms mud.

Circulating current compressed it earlier before returning fluidized-bed in compressor 30, by heat exchange zone, removed heat from circulating current then.Heat exchange zone can be the heat exchanger 24 of a routine, and it can be horizontal or vertical.The circulating current that comes out from heat exchanger is from bottom 26 Returning reactors of reactor.Enter fluidized-bed by mixing section 26a with by gas distribution grid 28 then.In the preferable embodiment of Fig. 1-3, the ring discoid director is installed in the place that certain distance is arranged apart from the reactor inlet of mixing section 26a bottom.

Preferable annular director as shown in Fig. 2 and Fig. 3 comprises an annual disk 32, by a spacer 32a this annual disk is supported in reactor inlet 26 tops and enters the mouth into certain distance (h) and locate, said annular director is divided into two strands to the circulating current that enters, one is a center upward air stream 33, and another strand is the peripheral annular air-flow 33a along the reactor bottom sidewall.Then two strands of air-flows mix and order by protection sieve plate 27, grid distributor 28 hole 29 and be fixed on the tapered cap 36a and the 36b of grid distributor upper surface, enter fluidized-bed then.When coming the operant response device with the non-condensing pattern, said air-flow is the mixture of gas and normally very a spot of solids (resin).And with the condensing mode operation reactor time, said fluid then is gas, drop and the mixture of normally seldom measuring solids (resin).

When coming the operant response device with condensation mode, the drop that can carry secretly in reactor bottom or the mixing section at the center of mixing section 26a upward air stream 33, and these can be delivered in the fluidisation section by droplets entrained.And peripheral air-flow 33a can prevent that solids from assembling at reactor bottom, and this effect all is effectively for two kinds of patterns of reactor operation, because this strand air-flow can wash away the internal surface of reactor wall.When carrying out the operation of condensation mode, when particularly the content of liquid is higher in operating system, possible some drop breaks away from wall to be carried secretly or gathering bottom mixing section, and peripheral air-flow can make any liquid that gathers together like this that atomizing again takes place equally and carry secretly.Because director 32 can provide that the center makes progress simultaneously and along two strands of air-flows of neighboring, therefore it can make a reactor can not cause the problem at reactor bottom generation liquid flooding and too much pitch again with the operation of non-condensing pattern with condensation mode.

The temperature of fluidized-bed depends on three factors basically: the rate of injection of (1) catalyzer, and it is controlling the speed of polyreaction, and is therefore controlling the speed of heat release, the temperature of (2) circulating current; (3) volume of the circulating current by fluidized-bed.Certainly, few more than the amount of liquid in the introducing fluidized-bed, certainly influence the variation of bed temperature, no matter these liquid be enter with circulating current and/or be this influence all to be arranged with what independent jet apparatus injected, this is to cause the temperature reduction because liquid volatilizees in fluidized-bed.In normal circumstances, the rate of injection of catalyzer only is used to the throughput rate of controlling polymers.Under steady state conditions, can come bed temperature is controlled at the numerical value of a substantially constant by the method for constantly removing reaction heat.Tangible thermograde does not appear in the position on fluidized-bed.The temperature ladder exists only in fluidized-bed layer bottom and upwards expands to the bed of certain altitude from gas distribution grid, and for example this bed height can reach the 152.40-304.80 millimeter, this since inlet air flow with bed interior material temperature is different causes.But at this fluidized-bed upper area more than bed of bottom, bed material temperature substantially constant ground keeps best temperature value.

For operant response device effectively, good gas distribution is very important.Contain in the fluidized-bed growing up with established particulate polymer granules and catalyst particle.Since polymer particle be heat and may be active, therefore must prevent that them from settling down, if there is the immobilized material to exist, the active catalyst that is present in so wherein will continue the fusing that reaction also may cause polymer particle, under extreme case, this fusing effect can cause forming solid mass in reactor, remove this agglomerate is very difficult and necessary the parking long period.Because fluidized-bed in the industrial-scale reactor of routine all may contain thousands of pounds solids in any fixed time, therefore to remove a solid mass in the big like this volume and just need pay huge effort.Therefore, the very important point is will make circulating current speed by bed diffusion be enough to keep the bed material to be in fluidized state.

For reaching good gas distribution, gas distribution grid 28 is a kind of devices preferably.This grid distributor may be the plate of sieve plate, slotted plate, porous plate or a kind of bubble-cap type etc.The part of grid distributor can be whole fixed, perhaps also can be to resemble U.S. Pat, disclosed mobilizable that class in 3,298,792.Design in any case, it must make circulating current spread by the particle layer of bed bottom, and can play a kind of support effect to immobilized resin particle bed material when reactor shuts down simultaneously.Preferably adorn a block protection sieve plate 27 below grid distributor 28, stopped up by the chip of resin to prevent contingent grid distributor, this obstruction is normally because circulating current is being carried the resin chip secretly upwards collides and cause on grid distributor.

The preferred type of gas distribution grid 28 is normally a kind of with the foraminate plate that all distributes on the metal whole surface.The diameter of these apertures generally is about 12.70 millimeters.These apertures pass grid distributor, and angle bar (illustrating with reference number 36a and 36b in Fig. 1) is housed above these apertures, and angle bar is firmly fixed on the grid distributor 28.Angle bar is alternately arranged by having angle to each other, and its angle is preferably 60 °, replaces parallel arrangement mode and is shown among Fig. 4.These angle bar can make the surface arrangement of air-flow along grid distributor, in order to avoid the solid stagnant areas occurs.In addition, when the bed material was in sedimentation or immobilized state, these angle bar can prevent that resin particle from falling by aperture.

This fluidized-bed reactor can be operated under the condition of pressure up to 6894760 handkerchiefs (gauge pressure), is 1723690-3447380 handkerchief (gauge pressure) for the preferable working pressure of producing polyolefin resin.

Inlet 42 above grid distributor 28 is sentenced intermittently or the successive mode is injected bed to part or all of active catalyst by required speed.Preferably catalyzer is injected into the place of polymer particle generation well blend in the bed.

Can use various technology that catalyst injection is gone in the reactor.For the polyreaction of ethene, preferably use a kind ofly as U.S. Pat 3,779, disclosed catalyzer feeder adds catalyzer in the reactor continuously in 712.The adding point of catalyzer preferably is equivalent to the place of reactor diameter 20-40% at the distance reactor wall, and this point leaves the 5-30% that the height of bed bottom should be about fluidized bed height.

The gas that is used for catalyzer is brought in the bed material must be inert to this catalyzer, for example nitrogen or argon gas.

The generating rate of polymkeric substance in fluidized-bed depends on the rate of injection of catalyzer and the monomer concentration in circulating current.Can come the generating rate of controlling polymers easily by the rate of injection of regulating catalyzer simply.

As above-mentioned, in order to avoid the obstruction of gas distribution grid as far as possible, a sieve plate 27 is installed in the below that is preferably in grid distributor, is stopped up by the resin chip (agglutinating solids) from circulating current to prevent the aperture on grid distributor.

When the granular polymer product is discharged from reactor 10, preferably carry out gas solid separation and gas is sent in the recycle circuit 22 again.Can finish this process with various known methods.A kind of system wherein is shown in the drawings.Like this, air-flow leaves reactor 10 with solid phase prod, by pipeline 44 and enter product blow-down drum 46, comes discharging, this valve will be designed to there is not what resistance when its open mode basically by a valve 48 (for example ball valve) then.In the above and below of blow-down drum 46 a kind of common valve 50 and 52 are housed respectively, valve 52 be product enter 54 of product surge tanks must through passage.Be equipped with on the product surge tank 54 with the gas barrier shown in the pipeline 56 with the gas inlet device shown in the pipeline 58.In the bottom of product surge tank 54 discharge valve 60 is housed also, this valve is opened to be emitted product so that pass on storage.When valve 50 was opened, the gas of emitting just entered surge tank 62 through this valve.The gas of emitting from product discharge tank 46 is directly by strainer 64, enters circulation line 22 through surge tank 62, compressor 66 and by pipeline 68 then.

In typical operation, valve 48 to be opened and valve 50 and 52 is cut out, product and air-flow just enter product blow-down drum 46 together.Valve 48 cuts out, make product sedimentation in the product blow-down drum.Then valve 50 is opened, made gas flow to surge tank 62, and then will compress continuously from the gas of surge tank and make it return recycle circuit 22 from product blow-down drum 46.Then valve 50 cuts out and valve 52 is opened, at this moment the product in the product blow-down drum 46 just flows into product surge tank 54.Then valve 52 cuts out.Use rare gas element, preferably nitrogen comes cleaning products, and the nitrogen that enters product surge tank 54 by pipeline 58 is discharged via pipeline 56.Then product is emitted from product surge tank 54, send to storage through valve 60 and pipeline 20.

Another kind of alternative preferable product discharge system is being proposed on July 28th, 1981 by Robert G.Aronson; application number is 287; No. 815; (this application has also been applied for patent in EUROPEAN PATENT OFFICE to its exercise question for disclosed and claimed discharge system in the U.S. Patent application of " fluidized-bed discharging method "; and open January 9 nineteen eighty-three, publication number is EP-A-0071430).This system at least will be with a pair of basin (two pairs of preferably parallel basins), one of this a pair of jar is slurry tank, another is a transfer tank, they are by arranged in series, also it has the gas phase separation device in this system, and the gas that will come out from the slurry tank top sends back to the ingress that the gas that comes out near the fluidized-bed top sends back to close fluidized-bed top in reactor reactor.This alternative preferable product discharge system does not just need the recompression pipeline 64,66,68 as shown in the accompanying drawing system.

In the main embodiment of implementing method system for use in carrying of the present invention, reactor comprises the fluidized-bed that makes the solids fluidisation, and the source line that air communication is crossed reactor bottom enters and discharges by the outlet line at top.The slurry tank of an emptying is installed in outside the fluidized-bed, preferably is lower than fluidized-bed, with a drainage conduit and a vapor pipe slurry tank and fluidized-bed is coupled together.Vapor pipe is directly connected on the reactor near the place of fluidized-bed layer end face, and the drainage conduit of solids then is connected to the bottom of reactor, preferably near the place of grid distributor.The position of transfer tank is lower than slurry tank, and the bottom that transfer tank is received slurry tank by a pipe connecting is connected on the follow-up processing unit by a drainage conduit in addition.At first, reactor and slurry tank and transfer tank all separate with valve each other and between they and its follow-up processing unit.Open the outlet valve that slurry tank is closed in blow-off valve and discharge line valve and maintenance.So just solids and gas are discharged into the slurry tank from reactor.First pressure with slurry tank is increased to the pressure near reactor bottom during beginning, and the pressure difference of utilizing solids fluidisation bed two ends then makes solids and gas flow through discharge line as motivating force.The part of fluidizing gas and the solids discharge line of flowing through enters slurry tank, this be because by this by way of resistance be less than resistance by solids fluidisation bed.Solids are separated with gas in slurry tank, owing to have other solid and gas to enter slurry tank, they go out isolated gas displacement, make it pass through the outlet line Returning reactor.After the solids that slurry tank is gone out by sedimentation are full of with some gases, close the valve of discharge and gas outlet tube, slurry tank and reactor are separated.Open the valve on the pipeline between slurry tank and the transfer tank then, solids are transferred to transfer tank from slurry tank by pressure difference and gravity.When solids entered transfer tank and jar in pressure reached balance after, with the valve closes on the pipeline.So far slurry tank can be prepared to begin another discharge circulation or can temporarily be waited, and to be transferred jar is transferred to the discharge that its upstream device begins slurry tank later on more fully with solids.Then, open the outlet valve of transfer tank, the solids of transfer tank are transported to upstream device with lower pressure.The conveying of solids can adopt conventional solids treatment facility to carry out, and perhaps uses pressurized air to carry out high-pressure delivery, and solid transfer (may need additional gas) in gas entrainment at this moment.After solids are discharged from transfer tank, outlet valve cuts out, so far transfer tank can prepare to begin another circulation.

In a kind of alternative preferred version, solids periodically emit from the high pressure vessel that contains solids fluidisation bed, its method is to adopt the slurry tank and the transfer tank of two pairs of parallel runnings, its operation steps is earlier the interstitial gas of solids to be entered a container that pressure is lower in proper order, and then solids are entered in this container.First sky slurry tank is used to receive the solids and the gas of discharging from fluidized-bed.After first slurry tank is full of by solids, just the gas that a part is entrained with solids enters second slurry tank (being in another parallel running system), this jar only as the temporary storage device of gas, after this more enters reactor with gas wherein indirectly.Then solids are discharged into a transfer tank that pressure is lower from slurry tank, operation can make the loss of gas minimize like this.Between two parallel slurry tanks that are used to receive from the solids of fluidized-bed and gas, the discharge operation is to carry out with alternating mode continuously.

Fluidized-bed reactor is equipped with suitable exhaust system (not shown), so as in starting and when to stop with the bed emptying.This reactor need not stir and/or scrape wall.Circulation line 22 and the equipment (compressor 30 and heat exchanger 24) on this circuit should have slick internal surface and should avoid unnecessary resistance, so as not to hinder circulating current or wherein institute's entrained particles pass through.

Embodiment

A kind of plant-scale fluidized-bed olefin polymerization reactors, the ring-type director in the bottom of reactor employing form shown in Fig. 2 and 3 had carried out the operation of condensation and two kinds of patterns of non-condensing with this reactor, any problem does not take place.The size of this reactor is as follows: mixing section diameter d m=3.51 rice; The high L=2.54 rice of mixing section; Inlet diameter de=0.58 rice; Director outside diameter do=0.97 rice; Circular diameter d=0.35 rice in the director; And the clear distance h=0.10 rice of director.Support annular disc also to keep the clear distance (h) between annular disc outward flange and the reactor bottom surface whereby with four legs.For this annular disc, A/A is 0.33, Z/h be 1.9 and Hv be 6894.76 handkerchiefs (gauge pressures).Once produce polymkeric substance with this reactor, wherein be by condensation and two kinds of mode of manufacture of non-condensing the multipolymer of ethene, and the Alathon of having pressed a kind of mode of manufacture of non-condensing.According to the product of required production, reaction conditions can be exemplified below:

Temperature of reactor, T:89-95 ℃;

Reactor pressure, P:2068428-2102902 handkerchief (gauge pressure);

Superficial gas velocity in the fluidized-bed, the Us:0.55-0.70 meter per second;

Fluidized bed height, Hfb:11.90 rice;

The maximum condensation rate at reactor inlet place, Wmax:11% (weight);

The throughput rate of reactor: the 9.526-18.145 kilogram/hour.

Have been found that the employing of guiding device, the operation of reactor do not produced any problem, and to the quality of product also without any adverse influence.Even under the situation of maximum condensation rate (the reactor inlet place is 11% weight), turn round the phenomenon of the device fluctuation of service that also do not react.This result shows, even reach above-mentioned degree of condensation, liquid still can be carried secretly and import and send into fluidized-bed and the phenomenon of liquid in reactor bottom accumulation and liquid flooding do not take place with the form of drop.Often reactor is checked, do not found too much to gather the scale problems that causes owing to resin particle.Check and find that internal surface cleans, even than under the situation of using conventional standpipe/cone cap shape reactor inlet device, also cleaning.Therefore, use director of the present invention can provide a kind of can again can be by the working method of non-condensing pattern by condensation mode, arbitrary pattern does not all have a negative impact to the performance and the quality of product.

Following table is listed some and is produced more polyvinyl embodiment by the polyreaction working method of condensation mode or non-condensing pattern, and the technical scale polymerization reactor that is adopted is above-described reactor.Carry out the test of listed product in the production table 2, listed the pattern of production operation in the table 2 and the content of condensed fluid in these two kinds of patterns.Whole operational conditions in this twice experiment are all listed in the table 3.

Liquid in the table 2 experiment product operation pattern reactor inlet air-flow

The content of body (weight %) I ethene hexene copolymer condensation 9～10II ethylene-butylene copolymer non-condensing 0

Table 3

Experiment I II* bottom pressure differential deltap p (* 6894.76 handkerchief) 5.2 5.0 cooler pressure differential deltap p (* 6894.76 handkerchief) 6.0 6.5 fluidized-bed temperature Tbed (℃) (* 16.02 kg/ms of superficial gas velocity Us (* 304.80 mm/second) 2.2 2.2 fluidized bed height Lfb (* 304.80 millimeters) 39.0 39.0 diffusion mixing chamber height L (* 304.80 millimeters) 8.33 8.33 diffusion mixing chamber diameter Dm (* 304.80 millimeters) 11.5 11.5 throughput rates (* 453.60 kg/hrs) 40.0 22.0 space-time yields in 95.0 89.0 fluidized-bed pressure Pbed (* 6894.76 handkerchiefs, gauge pressure), 305.0 305.5 entrance velocity Ui (* 304.80 mm/second), 79.2 79.2 fluid beds³Hour) 9-10.0 5.4 melt index MI 0.83 100.0 melt flow index MFR 25.0 27.0 density p (gram per centimeters ³) 0.926 0.931 ash content (%), 0.042 0.040 tap density ρ b (* 16.02 gram/rice ³) 27.0 24.5 median size APS (25.40 millimeters) 0.027 0.0226

* bottom Δ p represents that pressure by director falls with pressure by grid distributor and falls sum.Annotate: I=ethene hexene copolymer

The II=ethylene-butylene copolymer

Just as illustrated in Figures 5 and 6, (the preferable director as shown in Figures 2 and 3) of the not necessarily flat or orientation levels of director.Director shown in for example available Fig. 5 and 6 replaces the preferable director among Fig. 2, and the director among Fig. 5 and 6 is respectively towards grid distributor with convex surface and concave surface.Be installed in as the director with Fig. 5 and Fig. 6 that then the situation with director as shown in Fig. 2 and Fig. 3 is identical on the bottom inlet 26, the two all can provide one along first gas channel of mixing section wall and the second center upward air stream passage by the director centre hole.

The vertical height of director (or claiming thickness) is not very strict, as long as can meet the thickness requirement that structure of reactor proposes.Thin director is substantially the same with a quite thick director role.Like this, for the director of installing for level haply, itself whether has convex surface or the concave surface this point is insignificant, and which kind of form can successfully be operated, and in addition, does not also have the requirement of strictness for the thickness of director.

Though the bottom that is connected with straight drum part in the technical scale fluidized-bed reactor is generally elliposoidal or semisphere, other shapes also can be used for the present invention.For example, the reactor with coniform bottom also can be used this principle of director.Should be noted that the annular director of flats as shown in the drawing or convex arc shaped is more more desirable than the annular director of concave arc shape for the reactor of ellipsoid shape or hemisphere state bottom.

Theme of the present invention can be applicable to fluidized-bed polymerization reactor miscellaneous system.In the operation of fluidized-bed reactor, need sometimes to change into the non-condensing pattern from condensation mode, otherwise perhaps mutually, and the present invention just has this adaptability to changes.The present invention is specially adapted to polyolefine, for example polyethylene, polypropylene and their polyreaction that monomer carried out.

Claims (2)

1. the working method of a fluidized-bed polymerization reactor, this reactor contains grid distributor, this grid distributor is installed in below the bed, making it play air-flow to bed distributes and two kinds of effects of physical support, inlet is arranged near the bottom of reactor or its so that allow air-flow enter this reactor, normally annular director is connected with inlet device, there is a mixing section to be between grid distributor and the inlet device, when operation, one air-flow enters this reactor by inlet continuously, upwards pass through mixing section then, then by gas distribution grid and fluidized-bed, it is characterized in that, this method comprises that an air-flow that enters is divided into two strands at least, their flowpaths is respectively along annular director periphery and mixes between the locular wall upwardly and outwardly mobile first gas channel and by annular director centre hole mobile second gas channel that makes progress, and the orientation of gas velocity and all gas channels is combined can make carried secretly by grid distributor from the solids of mixing section and drop go forward side by side into fluidized-bed.

2. the working method of a fluidized bed polymerization process, it comprises:

A. polymerisable gas is introduced mixing section by an inlet device continuously, the speed during introducing is enough to make granular bed material to maintain the state of fluidisation and suspension,

B. gas is divided into two strands of air-flows at least, they is flowed at least two gas channels,

Guide the gas at least one gas channel to flow upwardly and outwardly, and guide the gas at least one gas channel upwards mobile along the central shaft of mixing section along mixing locular wall, so can:

Making is enough to (1) and makes solids be carried secretly and continue to remain in the air-flow of carrying it secretly and (2) stop the solid particulate polymeric articles to be assembled mixing on the locular wall along mixing the locular wall airflow flowing speed that makes progress,

Prevent that liquid from accumulating at mixing section,

Making is enough to prevent that along the mixing section central shaft airflow flowing speed that makes progress the solid particulate polymeric articles from falling into inlet,

Make the closing speed and direction thereof and can guarantee that combined flow reaches overall uniform mixing and good distribution when arriving the upper area of mixing section of each air-flow,

The combined flow that reached overall uniform state is entered by a gas distribution grid that is roughly level be positioned at mixing section and the fluidisation section above the grid distributor, the general speed that gas enters the fluidisation section is enough to make the bed of solid polymer particles to keep suspending and fluidized state.

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