Two-component nozzle for spraying liquid

 

(57) Abstract:

In the method of injection of fluid directly into a fluidized bed consisting of a gas and liquid mixture is fed from the mixing chamber through the outlet of the two-component nozzle in a fluidized bed. The fluid flow through each outlet is 0,009 to 0,130 m3/h/mm2and is determined from the equation, the pressure drop in the mixing chamber is from 0.8 to 1.5 bar. Nozzle for injection of fluid has an input for pressurized fluid, one input for the spray gas mixing chamber for mixing the liquid and gas outlet which is located circumferentially around the nozzle, through which consisting of a gas and liquid mixture is fed from the mixing chamber in a fluidized bed. The hole is made in the form of a slit having a size from 300 to 600 mm2. The configuration of the nozzle allows to improve the distribution of the spray liquid in the layer. The nozzle can be used in the continuous polymerization of olefins in a reactor with a fluidized bed. 2 S. and 4 C.p. f-crystals, 1 tab., 1 Il.

The invention relates to a nozzle that can be used for of V.N.Karazin is s, in particular to the nozzle, which allows better control of the injection process and provides a better distribution of the sprayed liquid in the fluidized bed.

The processes of gas-phase homopolymerization and copolymerization of olefins has been widely spread. In such processes, for example, gaseous monomer Inuktitut in mixed and/or fluidized bed consisting of previously obtained polyolefin and necessary for the polymerization catalyst.

In the polymerization of olefins in a fluidized bed polymerization is carried out in a reactor with a fluidized bed consisting of particles of polymer, which are held in a fluidized state passing up through this layer in the gas stream, which contained in the gaseous state reactive monomer. To initiate the polymerization process generally uses a layer of previously obtained particles of a polymer similar to the polymer, which should be obtained in the process of further polymerization. In the polymerization process fresh polymer is formed by the catalytic polymerization of the monomer and the resulting polymer is withdrawn from the reactor, while maintaining more or less on the about layer used mesh, which distributes the fluidizing gas in the whole volume of the layer, and when the gas supply is a particle-retaining layer base. The resulting polymer is usually removed from the reactor through the discharge channel located in the lower part of the reactor near used for the formation of a fluidized bed net. A fluidized bed is a layer of growing polymer particles, particles of the obtained polymer and catalyst particles. This reaction mixture is kept in fluidized state by a continuous stream rising up from the base of the reactor, fluidizing gas, which consists of a fed to the reactor with fresh gas and exhaust gas taken from the top of the reactor.

The fluidizing gas is fed into the reactor from the bottom and preferably passing through the employee base of the fluidized bed net, gets into the fluidized bed.

Polymerization of olefins is an exothermic reaction that causes the need to adopt special measures for cooling layer and the selection generated by the polymerization heat. In the absence of such cooling, the temperature rises layer, which can reach values at which the station is in the fluidized bed is the preferred method of selection generated by the polymerization heat is in the reactor in which the polymerization, serves gas, preferably the fluidizing gas, the temperature of which is less than required for the polymerization temperature and which passes through the fluidized bed, taking him released during polymerization heat, then cooled in an external heat exchanger and re-fed into the reactor. The temperature of the circulating gas can be adjusted in the heat exchanger so that in the fluidized bed was maintained required to polymerization temperature. In this process, the polymerization of alpha-olefins circulating gas typically contains Monomeric olefin, optionally in conjunction with, for example, gaseous or gaseous diluent regulator of the degree of polymerization, such as hydrogen. This circulating gas ogiget layer and the source is supplied to the layer of monomer and simultaneously maintains the temperature of the layer. Continuous adding to the flow of circulating gas of a corresponding quantity of fresh gas provides a constant replenishment of the fluidized bed is consumed during the polymerization reaction of the monomers.

It is well known that the performance (i.e., volume output, determined the s fluidized bed of the type specified above is limited to a maximum speed of cooling of the reactor. The rate of cooling of the reactor can be increased, for example, by increasing the velocity of the circulating gas and/or by reducing its temperature. However, in practice, the maximum possible velocity of the circulating gas has a certain limitation. When excess gas velocity in this limit, the layer becomes unstable or even begin to rise in the reactor up together with the gas flow, clogging the circulation and damaging pumping gas compressor or blower. Similarly in practice is limited and the extent of cooling the circulating gas. First of all this is determined by economic considerations, and in practice the temperature to which it is possible to cool the gas depends on the temperature at the disposal of industrial water, which can be used for cooling the gas. If necessary, you can use the corresponding refrigerators, which, however, has a significant impact on production costs. Therefore, the use in industrial installations only one circulating gas for removal from the fluidized bed heat released during polymerization of olefins, it is not possible to provide the unit with mA the PLA of fluidized gas layer, in which processes of polymerization.

In the United Kingdom patent GB 1415442 described the process of gas-phase polymerization of vinyl chloride in the reactor with a mixer or a fluidized bed, which flows in the presence of at least one gaseous diluent having a boiling point below the boiling point of vinyl chloride. In the example in this patent example 1 describes the process of monitoring the temperature of polymerization, consisting in periodic addition of liquid vinyl chloride in the fluidized bed polyvinyl chloride. Falling into a fluidized bed of liquid vinyl chloride evaporates, taking away from the layer generated by the polymerization heat.

In U.S. patent US 3625932 described polymerization process of vinyl chloride, in accordance with which the layers of particles of polyvinyl chloride in a multistage reactor with a fluidized bed is kept in the fluidized state of gaseous vinyl chloride monomer fed from below into the reactor. Cooling each layer and removal of the heat released during polymerization is carried out by spraying the liquid vinyl chloride monomer in the flow of the fluidizing gas layer under the plate, which is of type check valve, which is designed for spraying liquids in fluid layers, for example, in the liquefied gas layer in which the polymerization ethanobotany monomers. As the fluid used for cooling the layer, you can apply the polymerized monomer or in the case of polymerization of ethylene liquid saturated hydrocarbon. Described in this patent, the spray nozzle is used for polymerization in the fluidized bed of vinyl chloride.

In the United Kingdom patent GB 1398965 described method of polymerization in the fluidized bed ethanobotany monomers, particularly vinyl chloride, in which thermal control of the polymerization process is carried out by injection into the layer of liquid monomer with one or more spray nozzles, the height of which is from 0 to 75% of the height in the reactor in a fluidized bed state of the material.

In U.S. patent US 4390669 described multistage process of gas-phase Homo - or copolymerization of olefins carried out in a reactor with a mixing layer in the fluidized bed reactor, a reactor with a stirrer and a fluidized bed or in tubular reactors. In this process the polymer, and the resulting suspension is given to the second polymerization zone, which evaporates the liquid hydrocarbon. In the example in the patent examples 1-5 says that gas from the second polymerization zone is passed through a cooler (heat exchanger), which condenses a number of liquid hydrocarbon (co monomer, if used). The condensation of the volatile liquid partially served in a liquid state in the apparatus for polymerization, in which it evaporates, selecting due to the latent heat of vaporization released during polymerization heat. In this document, nothing does not specifically mention how the fluid gets into the curing area.

In U.S. patent US 5317036 described the process of gas-phase polymerization using a soluble catalyst based on a transition metal. Soluble catalyst can be fed into the reactor using a spray nozzle, in which it more efficient spray you can use an inert gas. There is no specific information about the design of the nozzle in this document does not contain.

In the European patent EP 89691 describes how to increase volume of output during continuous polymerization of liquid monomers in a fluidized bed gas layer, which bases is over and they carried away the liquid with a temperature below the dew point and return this two-phase mixture in the reactor. This mode is called the "regime of condensation". In the description of the patent specification EP 89691 argues that the main limitation on the degree of cooling of the circulating gas stream to a temperature lower than the dew point is the need to maintain the mixture of gas and liquid in such a state that the liquid phase in two-phase mixture to evaporation of the liquid was in her in suspended or suspended state, and argues that the amount of liquid in the gas phase should not exceed about 20 wt. percent, and preferably should not exceed 10 wt.%, the speed of the two-phase recirculating flow should be high enough for the liquid phase remained in the gas stream is in a suspended state, and that this flow could be maintained in suspension generated in the fluidized bed reactor. In EP 89691 also refers to the possibility of formation of two-phase fluid flow inside the reactor at the point of injection by separate injection of gas and liquid under conditions ensuring formation of two-phase flow, and argues that this method of injection does not give a big advantage, since it requires additional costs for separation after cooling duhf the Pis of the present invention, features a continuous process that takes place in the fluidized bed, the expected gas flow, and the performance of which is improved by cooling the circulating gas stream to a temperature sufficient to form a liquid and gas, followed by the separation of liquid from gas and supply separated from the gas-liquid directly into the fluidized bed. For injection of fluid in the fluidized bed can be used one or more located in the layer injectors. It was found that the use of the specific nozzle design, which is served facilitate the injection of a liquid spray gas with appropriately selected parameters, allows to improve the distribution and penetration of liquid into the fluidized bed.

Thus, according to the present invention proposes a method of injection of fluid directly into the fluidized bed, which requires the use of jets or nozzles, each of which has:

(a) at least one inlet for pressurized fluid,

(b) at least one inlet for the spray gas,

(b) mixing chamber for mixing the liquid and gas

(g) edge the camera directly into the fluidized bed, and which differs in that

(I) the penetration depth extending from each of the outlet fluid in a fluidized bed in the horizontal direction is from 250 to 2500 mm and is determined from the equation:

y = a + bF(x),

where

< / BR>
a and b are constants, equal to a = 507,469, b = 5400,409,

< / BR>
and

< / BR>
and (II) the pressure drop in the mixing chamber is from 0.8 to 1.5 bar.

In a preferred embodiment, the amount of liquid in the layer in the horizontal direction is from 350 to 1500 mm

The pressure drop in the mixing chamber, which is equal to the difference between the pressure at the entrance and outlet pressure from it, is measured by the differential pressure sensors installed properly in the nozzle.

These sensors can be used to control the fluctuations of the pressure in the mixing chamber and determining during operation of the spray parameters.

In a preferred embodiment, the pressure drop in the mixing chamber ranges from 1.0 to 1.25 bar.

The pressure drop in the mixing chamber depends on many factors, including the size of the mixing chamber, the ratio of gas/liquid, sizes transmusicales the camera does not go beyond the ranges specified above.

The total flow of liquid through the nozzle is usually from 500 to 50,000 kg/h, preferably from 2,000 to 30,000 kg/h

Proposed in the invention, the nozzle allows spraying gas accurately and within a narrow range to control the droplet size of the sprayed liquid. The advantage of this nozzle is that when you cut into it, the liquid continues out of the flow of the spray gas will interfere with the intake nozzle of the particles of the fluidized bed, thereby eliminating the risk of contamination and clogging.

A particular advantage of the present invention the nozzle is the ability an appropriate area of the outlet openings and the liquid flow rate to maintain the specified limits the penetration depth of the liquid layer in the horizontal direction, which makes the process of injection fluid in a fluidized bed of optimal.

Providing the ratio between the area of the outlet openings of the nozzles and the flow passing through the liquid and maintaining within the set limits the pressure drop in the mixing chamber, it is possible to achieve optimal penetration of the fluid in the PS is unintended as the difference between the pressure of the liquid or spray gas inlet to the nozzle and pressure in the discharge outlet of the nozzle (i.e., in the fluidized bed), typically ranges from 2 to 7, preferably 3 to 5 bar.

Using the proposed in the present invention the nozzles in a fluidized bed, you can inject an hour from 0.3 to 4.9 or more cubic meters of liquid per cubic meter in the layer of material.

As fluid is injected into the layer through a nozzle, you can use the comonomers of butene, hexene, octene, etc. or inert liquids, such as butane, pentane, hexane, etc.

Using the proposed in the present invention the nozzle the liquid is injected into a fluidized bed in the form of one or more jets of liquid and gas sprayed from one or more of the outlet openings of the nozzles. The speed of the spray liquid at the outlet of each exhaust port is normally around 30 m/s the Speed of the spray gas typically ranges from 2 to 3 m/sec. Each stream of liquid and gas is heterogeneous in its composition, because the exit nozzle velocity liquid droplets exceeds the velocity of the spray gas.

The weight ratio of the spray gas and liquid supplied to each nozzle, is from 5:95 to 25:75.

As the spray gas is usually used is cragnotti around the nozzle, out a jet of liquid and gas. Emerging from the nozzle of the jet of liquid and gas, which are usually directed horizontally, can have some inclination to the horizontal plane, which, however, should not exceed 45oor more preferably 20o. The most preferred angle of divergence of the jet in the vertical plane is the angle in the 15o.

Each nozzle typically has several outlet openings, the number of which varies from 1 to 40, preferably from 3 to 16. In a preferred embodiment, the nozzle has 4 outlets.

The outlet nozzles are located on a circle and preferably at equal angular distance from each other. In a preferred embodiment, the design of the injectors 4 holes these holes are located so that the angle diverging in the horizontal plane consisting of gas and liquid streams ranged from 20 to 80omost preferably 60o.

Typically, the outlet openings of the nozzles are in the form of cracks, however you can use other form of output holes.

Usually slotted holes have dimensions of, for example, from h mm to I mm Square slotted holes abhorance with 4 output holes shown in the appended drawing (Fig. 1), which shows the nozzle (1) channel (2) for supplying a sputtering gas channel (3) for supplying a pressurized fluid and a mixing chamber (4). In the lower part of the drawing shows two outlet openings (5) and (6). Liquid and spray gas fall into the chamber (4) of the individual channels (2) and (3) for the supply of gas and liquid. These channels are one in another, and spray the gas passes through the Central channel (2), which is located inside the outer channel (3) through which flows the liquid.

The spray angle of each of the outlet (5) and (6) in the horizontal plane is approximately the 60oand therefore injected into the layer of liquid is distributed almost throughout the cross section of the layer (total spray angle is from about 240 to 360o). Vertical deflection of the jet of fluid is approximately 15o(7.5oin each direction).

Essentially jet, the projection of which in the horizontal and vertical planes is shown on the drawing, is formed in the layer of the conical zone dispersed in them sprayed liquid. This form of conical jets contributes to a more effective penetration of liquid into the fluidised lemoi it liquid.

As the main characteristics of the nozzles, which is the basis proposed in the invention method, can serve as the quantity of fluid flowing through the output hole.

In this case, the object of the present invention can be formulated as a method of injection of fluid directly into the fluidized bed, which requires the use of jets or nozzles, each of which has:

(a) at least one inlet for pressurized fluid,

(b) at least one inlet for the spray gas,

(b) mixing chamber for mixing the liquid and gas

(g) at least one outlet through which consisting of a gas and liquid mixture is fed from the mixing chamber directly into the fluidized bed, and which is characterized by the fact that

(I) flow rate (R) of liquid through each outlet is in the range from 0,009 to 0,130 m3/h/mm2and is determined from the equation:

< / BR>
and (II) the pressure drop in the mixing chamber is from 0.8 to 1.5 bar.

Preferably, the flow rate should be chosen in such a way that the value of (R) ranged from 0.013 to 0.03 m3/h/mm2.

3/PM

Proposed in the present invention the nozzle is particularly effective when used in a continuous process for obtaining polyolefins in the gas phase by polymerization of one or more olefins at least one of which is an ethylene or propylene. Preferably proposed in the invention process as alpha-olefins to use olefins having from 3 to 8 carbon atoms. If necessary, you can also use small amounts of alpha-olefins having more than 8 carbon atoms, for example, olefins with 9-18 carbon atoms. Proposed in the invention method allows to obtain the homopolymers of ethylene or propylene or copolymers of ethylene or propylene with one or more C3-C8alpha-olefins. Preferably as alpha-olefins to use buta-1-ene, Penta-1-ene, Gex-1-ene, 4-methylpent-1-ene, Oct-1-ene and butadiene. As an example, higher olefins, which can be copolymerisate with the primary monomer is ethylene or propylene, or use as a partial substituent for C3-C8monomer, can be called Oct-1-ene, ethylidenenorbornene.

When copolymerization of ethylene or propylene with allicante monomers in the final product preferably greater than 70%.

Proposed in the invention method can be used for a variety of polymeric materials, for example, linear polyethylene of low density (LDL) based on copolymers of ethylene with butene, 4-methylpent-1-Yong or hexene and high density polyethylene (HDPE), which can represent, for example, homopolyamide or copolymers of ethylene with small amounts of higher alpha-olefin, such as butene, Penta-1-ene, Gex-1-ene or 4-methylpent-1-ene.

The fluid that is injected through the nozzle is separated from the circulating stream and may be a condensed monomer, for example, butene, hexene, octene, used as co monomer upon receipt of LDL, or condensed inert liquid, such as butane, pentane, hexane.

The proposed process is particularly effective in the polymerization of olefins at a pressure of from 0.5 to 6 MPa and at a temperature of from 30 to 130oC. for Example, when receiving LDL temperature usually ranges from 80 to 90oC, but when PVP in the range from 85 to 105oC depending on the activity of the used catalyst.

The polymerization reaction can be carried out in the presence of a catalytic system of the type Locationfor, an organic compound of the metal (in particular ORGANOMETALLIC compound, for example, alkylamino connection). In recent years we have created a variety of highly active catalytic system, which allows to obtain large quantities of polymer within a relatively short period of time and eliminates the need for extraction of the polymer remaining in its catalyst. Such highly active catalytic systems typically contain a solid catalyst consisting primarily of atoms of the transition metal, magnesium and halogen. It is also possible the use of a highly active catalyst, consisting mainly of chromium oxide, activated by thermal treatment and related granular media based on a refractory oxide. The proposed process can also be used with success in cases when the catalyst is used metallocene catalysts and catalysts of the Ziegler silicon-based. Such metallocene catalysts are well known and described in particular in European applications EP 129368, EP 206794, EP and EP 416815 420436.

The catalyst can be used in powder form of prepolymer obtained so far at the stage of preliminary polymeric any suitable way, for example, the implementation of periodic, semi-continuous or continuous polymerization process in a liquid hydrocarbon diluent, or in gas phase.

Below the invention is illustrated in more detail by examples.

Examples

When setting the experiments were taken into account, when large quantities of the spray nozzle of the liquid contained in the sprayed jet of liquid cannot evaporate into the fluidized bed of polyethylene.

Therefore, for experiments on the study of the process of injection fluid through proposed in the invention of nozzles used a special experimental setup. This installation was completed in aluminium housing located at the top and downward two-component nozzle for spraying liquid as a spray nozzle was used nozzle, the construction of which is shown in the appended drawings). In the nozzle filed spray a gas and a liquid hydrocarbon and fixed geometry formed on the output stream and the extent of its spread in the case of installation using conventional x-ray apparatus, comprising a source of x-rays, usilitel is discontinuously recorded output signal of the video camera.

Emerging from the nozzle jet was hit with a wall of the housing, and contained sprayed liquid trickled down the wall of the housing in the receiving tank, located under the nozzle in the lower part of the body. As a liquid during the experiments used 4-methyl-1-penten containing 1-2 wt. % powdered polyethylene (particle size less than 355 microns), the presence of which in the flow of the circulating liquid was allowed to estimate the probability of clogging the nozzle.

For the continuous feed of the liquid in the nozzles used for closed loop circulation of fluid through the receiving tank and the bypass line. The flow rate was determined using a calibrated flow meter (S. G. the class of 0.67, the outside dimensions from 3 to 36 m3/h) and controlled valves through which fluid from the bypass line from the pump was delivered to the nozzle. For different liquids have introduced relevant amendments. For spraying liquid used nitrogen gas, which is fed into the nozzle through a calibrated flow meter to the throttle plate of the battery of cylinders located outside the x-ray machine. Usually to obtain the necessary for the operation of the injector gas flow used the nozzle to the mixing chamber during the experiments was continuously monitored and measured by the pressure sensors Drunk (measuring range overpressure 0-30 bar, calibration with an accuracy of 0.05 bar). The pressure drop in the injector is controlled by the differential pressure sensor Drunk (measuring range gauge pressure 0 to 10 bar, calibration with an accuracy of 0.01 bar). Measured in the system pressure was recorded during the experiments corresponding recording device.

For further analysis of the geometry of the formed jet recorded in the format of the video.

Analysis of the results obtained in the experiment of example 1 showed large fluctuations in the character stream generated stream, starting from a stream with small drops of fluid and to flow with heterogeneous structure, i.e., flow, sometimes consisting only of fluid, and sometimes only from the gas. When the experiment of example 2 was obtained stream, completely filled sprayed it with liquid, confirming the conclusion that to obtain maximum dispersion must have a corresponding nozzle geometry, operating at a pressure drop.

1. The method of injection of fluid directly into the fluidized bed, which consists of gas and liquid mixture is fed from the mixing chamber through at least one output of tickety through each outlet is 0,009 to 0,130 m3/h/mm2and is determined from the equation:

< / BR>
(II) the pressure drop in the mixing chamber is from 0.8 to 1.5 bar.

2. The method according to p. 1, characterized in that the fluid flow is from 0.013 to 0.03 m3/h/mm2.

3. The method according to p. 1, characterized in that the volume flow of liquid through each outlet is from 5 to 20 m3/PM

4. The method according to any of paragraphs.1 to 3, characterized in that the pressure drop in the mixing chamber ranges from 1.0 to 1.25 bar.

5. Nozzle for injection of fluid directly into the fluidized bed, having: (a) at least one inlet for pressurized fluid; (b) at least one inlet for the spray gas; (b) mixing chamber for mixing the liquid and gas, and (d) at least one located circumferentially around the nozzle outlet through which consisting of a gas and liquid mixture is fed from the mixing chamber directly into the fluidized bed, characterized in that each outlet is made in the form of slits, with an area of from 300 to 600 mm2.

6. The nozzle on p. 5, characterized in that it has four outlets.

 

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