Method and device to fabricate pellets

FIELD: process engineering.

SUBSTANCE: invention relates to method and devices for making pellets of crystalline salts. At least, one injection zone is created in fluid bed and, at least, one pelletising zone. Pellets are extracted from one pelletising zone to separated them into three fractions. Fraction of preset size pellets is directed to processing to target product pellets. Fraction with pellets with size exceeding preset one is removed from pelletising process. Fraction with size under preset one is directed into feeder flow of germ particles to cause heat exchange from fluidisation zone in classifier. Proposed method is implemented in pelletiser comprising reactor 10 with fluid bed formed above air distribution grating 11 when fluidising air 17 is forced through grating 11. Pelletiser reactor represents vertical rectangular cross-section column converging to funnel at its top section, said funnel making fluidised air outlet. Separation web 18 divides pelletiser reactor into injection section 12 and pelletising section 13. Pelletising section houses classifier 21 including seat of heat exchanger tubes 20.

EFFECT: pelletising by spraying, higher efficiency and quality.

10 cl, 6 dwg, 4 tbl

 

The present invention relates to a method and apparatus for producing granules crystallized salts.

Background of the invention

The material crystallized salts in the form of particles is widely used in various fields, for example, in agriculture as fertilizer, as additives in industrial chemical processes, as an anti-icing roads, etc. For many tasks the user is required material in the form of particles with a particular size distribution, which, after storage and transport has essentially free flowing.

Granulation by spraying fluidized bed is a standard technology to obtain a homogeneous granules of the same shape, the raw material for which is a liquid product or products, such as solutions, suspensions, slurries, melt and emulsion. However, in the processes of granulation fluidized bed at the outlet of the granulator are usually obtained granules of various sizes, some sizes of granules are outside the required range of sizes. Granules with acceptable sizes are often referred to as "granules of nominal size", i.e. corresponding to the sizes required for the final product. Granules with sizes greater than required, often referred to as "large fraction", while ka the granules are too small are called "small fraction". Granules nominal size are subjected to further processing, while the coarse and fine fractions are usually recycled back to the granulator, which ultimately is involved in a cycle of re-processing (recycling).

Typically, the fine fraction may be directly sent back to the granulator (or after, for example, cooling or, if required by the drying process)to further the size of the granules increased and went into the interval required diameter (granules nominal size); while the coarse fraction is generally subject to fragmentation and re-submission in the granulator in solid form (after other intermediate operations, or without such, or can be melted/dissolved for re-submission in the granulator in the form of a liquid to be atomised.

The product in solid form, returned to the granulator of sorting sieves, hereinafter referred to as the product of external recycling.

Such recirculation may sometimes be necessary for technological reasons, for example, to maintain a state of "balance" in the system (heat balance, water balance, etc). However, in most cases, external recirculation is the result of imperfect process of granulation and the fact that all particles are of an inappropriate size, and therefore, there are unnecessary costs and limitations of the process.

Generally is Evora, the need for recirculation means increase in the investment costs and operating costs. Recycling involves processing, handling (conveyors, elevators and the like), energy consumption (electricity consumption, for example, for transporting equipment or heat consumption, for example, reheating of the product that it has reached the temperature required for operation of the granulator and the like). Thus, the volume of recirculated air should be minimized, which is one of the important objectives of the present invention and the solution to this problem is the dignity of the invention.

For example, in the case of granulation of urea for fertilizer consumer usually requires granules with a diameter of from 2 to 4 mm Particles coming out of the pellet mill and having a size less than 2 mm will be fine fraction, while particles larger than 4 mm will be considered a large fraction. Part of a large fraction (e.g., pieces) will be subjected to melting or dissolution, while most will be subjected to crushing, to submit to the pellet mill grain desired degree of grinding. In some cases, when the external recirculation typical ratio is from 0.5:1 to 1:1, i.e. for 1 kg of product nominal size coming out of the path of the pellet back into the granulator is returned material (chalk is Aya and coarse) in an amount of from 0.5 to 1 kg

Traditional granulators continuous action spray fluidized bed usually have a simplified process diagram, shown in figure 1 (for simplicity not shown auxiliary fluid environment, such as environment, providing fluidization, energy, etc. as well as specific operations, for example, heating, cooling, air conditioning, cleaning etc). Position 1A indicated the stage of pellet feed product or other germ particles, if any, which are to be covered with liquid product or products. Position 1b marked phase flow of the liquid product(s). Position 2 marked the stage at which in the zone of granulation germ particles is brought into contact with the dispersed liquid product, give them to acquire the initial shape and dried. Position 3 marked the post-processing step granules, which typically includes further drying and/or forming or cooling granules. Stages 2 and 3 are the granulating process, and both can occur in General, the fluidized bed. Stage 4 - this is an optional stage before the screening, such as cooling, drying, etc. of the Stage 5 is sorted by sieving the granules coming out of the process of granulation, with 5A is a fraction of granules with the size above the nominal, 5b - fraction of granules with a size below the batteries is th, and 5C - fraction of granules nominal size that is passed to step 6 postranslational processing to obtain the final product 7.

Granules 5b below the nominal size from step 5 sorting pass to step 9 processing and return to the zone 2 injection. Stages 5/8/9 constitute a cycle of recirulation. Pellets 5A size above the nominal transmit on stage 8 processing in order to return to the zone of injection. Step 8 is a step of the processing unit 5A size above the nominal. This treatment may be to reduce the size of the granules by crushing, melting of the granules with the aim of producing a liquid product for dispersion in the injection zone, or in their production, as large pellets for other applications. Step 9 - this is an optional step for processing granule size below par before their re-entry into the stream of germ particles.

An example of a process of granulation fluidized bed can serve as a model process for the granulation of urea and the circuit of the urea granulator described in the publication Fertilizer Manual fertilizers), IFDC, Kluwer academic publishers, edition 1998, Ch.9, pp.269-270 or in the publication of Nitrogen and Syngas (Nitrogen and synthesis gas), July-August 2006, p.42.

The level of technology

Examples of spray granulation fluidized bed is shown in the patent of school is 5213820, as examples of granulation spray fluidized bed using classifier is shown, for example, in international application WO 01/43861.

In the international application WO 01/43861 described spray granulator, fluidized bed, which includes a classifier for sorting pellets containing a set of contiguous zones of the fluidized bed, separated by sloped walls. The design of the granulation chamber is asymmetric, i.e. the chamber is divided into several compartments sloping reflective plates (baffles). The separation is due to the circular motion of the particles, while larger particles tend to move towards the exit of the fluidized bed, while the lighter particles tend to move toward the entrance of the fluidized bed is back in the growth zone, where they can become larger. The basic idea of the invention is that the required return is made by the classifier without external recirculation.

In the international application WO 97/02887 disclosed classifier fluidized bed containing a set of baffles in the fluidized bed for the implementation of vertical separation when the operation occurs when the gas velocity, causing the appearance in the fluidized bed gas bubbles. Deflectors hold particles, allowing them to follow Pazyryk the mi gas, rising from the fluidized bed, which would violate the effect of separation.

The objective of the invention

The main task of the present invention is to provide a method for granulating spray fluidized bed liquid products with increased performance obtain granules.

The second objective of the present invention is to provide a method for granulating spray fluidized bed liquid products with increased performance producing granules and/or improved quality of pellets.

Another object of the present invention is to provide a granulator for implementing the method corresponding to the primary and secondary objectives of the invention.

These tasks can be achieved by the features set forth in the following description and/or in points of the attached claims.

Disclosure of inventions

The invention is based on the idea that high performance obtain pellets, achieved through the use of the classifier in the fluidized bed, can be improved through the use of the classifier of the heat exchanger, having thus increased the rate of heat transfer. Increased rate of heat transfer can be useful both for the supply of heat to the fluidized layer and drainage Talaat fluidized bed. For example, in the case of crystallization of the melt, it is useful to take more heat, while in the case of, for example, an aqueous solution useful to bring more heat to evaporate water from the solution. The subsequent description of the invention based on the system in which the potential interest is the extra heat, but the present invention can also be applied to systems in which the interest is the application of heat.

In its first aspect the present invention relates to a method for producing granules by granulation liquid product spraying, fluidized bed, comprising the following operations on them:

- create at least one zone of injection into the fluidized bed, in which germ particles of the feed stream is brought into contact with liquid product/cover liquid product through the simultaneous introduction of the feed stream germ particles and the supply flow of liquid product in the form of a stream disbelieving drops of liquid,

- create at least one zone of granulation in the fluidized bed, which came into contact with the liquid product is covered with a liquid product embryonic particles may be subjected to drying and/or shaping and/or cooling with obtaining granules

- extract granules at least one zone Gras is lirovaniya, and sort the extracted granules into three fractions: granules with a size lower than the nominal diameter which is too small compared with the required interval sizes, granules, nominal size, the diameter of which falls within the desired size range, and granules of higher nominal diameter which is too large compared with the desired interval size,

- direct the fraction of granules nominal size for subsequent processing to obtain pellets of the final product,

- direct the fraction of granules with the size above the nominal in the means to remove them from the process of granulation, and

- direct the fraction of granules with a size below par in the supply stream of germ particles,

moreover, the granules pass at least one classifier, placed at least in one area of the granulation in the fluidized bed, and made with the possibility of separation of the granules according to their size, and direction of at least part of the separated granules with a size below the nominal back to the area of injection for the subsequent escalation.

Under "removing granules size above the nominal of the granulating process" means that the granules with the size above the nominal does not give the opportunity to get into the zone of injection. This can be achieved through one or more of th is blowing technological operations: crushing of large granules until the granules with a size below par and their subsequent direction of the supply flow germ particles, areas of large pellets in the melt of urea and, thus, recirculation of the granules with the size above the nominal in the form of a liquid product, or release of granule size above nominal for end use by external equipment. Process flow diagram corresponding to the present invention in its first aspect, is shown in figure 2. This scheme is identical to the scheme of figure 1, representing the existing prior art, except that the input stage 3A and technology branch 10. Stage 3A is a step in the classification of the granules in the granulator, and the branch 10 - direction of at least part of the separated granules with a size below the nominal back into the zone of injection of the pellet mill. Branch 10 represents an internal transfer of granule size below nominal in contrast to the external circuit, indicated by the positions 5, 8 and 9. The arrow from block 8 is shown with a dashed line, indicating that this branch transmission is optional.

In its second aspect the present invention relates to a method, which includes the way to the first aspect of the invention, but which also contains a stage of removal of heat from the fluidized zone in the classifier (or, respectively, the supply of heat to the specified zone) through the use of one or more heat exchangers. The classifier and the heat exchanger can the be combined in a single device, i.e. made in the form of heat exchanger tubes, which are arranged horizontally at a distance from each other, crossing the cross-sectional area of the classifier, and at the same time performing the function of the classifier. Not necessarily positioning the heat exchanger in the classifier on the same level, on the contrary, it can be placed on the height at several levels.

The use of the classifier, which is made with the possibility of separation of the granules in the fluidized bed according to their size, and transferring at least part of the fraction of granules with a size below the nominal back to the area of injection for further consolidation has several advantages.

One advantage is the reduction of the amount of material returned by the external contour that allows to unload the external equipment recycling, and reduce investment and operating costs on production installation. This characteristic makes it possible to increase the performance compared to traditional pellet of the same size as the unloading external recirculation circuit can increase the flow of product through the granulator. When testing the resulting reduction of the volume of the external recirculation, approximately 1/3 that demonstrated that the presence of internal recycling can significantly reduce the amount of the refund is through an external circuit, and, thus, to reduce the load on the equipment that is involved in recycling (fridge, sorting screens, crushers, elevators and so on).

In General, granulators fluidized bed temperature in the zone of the spray should be optimal and possibly more homogeneous, that is, the temperature must be so high as to promote drying (for example, the evaporation of water or solvent from the precipitated liquid product), but not too high to avoid delamination of the membrane and subsequent clogging of the equipment. However, when the external recirculation and re-entry of the granules, the temperature in the injection zone near the inlet tends to be lower than in the rest of the zone of injection, which leads to inhomogeneity of the temperature profile in the zone of injection. The trend of obtaining inhomogeneous temperature profile in the system with an external recirculation can be suppressed due to internal recirculation, namely due to both reduce the amount of external recycling relatively cold product, and due to the fact that the internal recirculation makes it possible to supply participating comparatively cold granules to other parts of the zone of injection, but not in the region of the inlet. Control of a cooling medium of the heat exchanger allows you to adjust the temperature internally is recycling at the required level. Thus, the disturbances at the entrance to the granulator, caused by external recirculation, can be reduced, and the temperature in the injection zone as a whole may be more homogeneous. This provides an opportunity to increase and the quality of pellets and/or drying capacity of the pellet mill.

An unexpected effect of the invention in its second aspect is that the use of heat exchanger tubes in the classifier does not lead to a significant reduction of the temperature of the granules of nominal size and granule size above par, leaving through the outlet of the granulator. It is noted that, on the contrary, the separated granules below par at the top of the granulator have a significant degree of cooling. This unexpected effect leads to a leveling effect on the temperature profile in the zone of injection can be enhanced by the use of a coil in the classifier, and the heat in the classifier cools the granules, so that the temperature in the injection zone may be more homogeneous. Also use a heat exchanger to increase the heat from the zone of granulation in the fluidized bed in addition to the usual selection of heat, for example, by evaporation of water from the dispersible liquid or the environment, creating a fluidized bed, for example, air. In a dependent is ti, what is critical in the granulator: heat balance or as a function of increasing heat may increase, respectively, performance or quality. This function can also be used to obtain a combination of productivity and improve product quality.

In its third aspect the present invention relates to a granulator for granulating liquid product by spraying in a fluidized bed containing:

- a reactor with a fluidized bed containing i) one or more zones 2 injection, where germ particles in the form of a stream in contact with liquid product covered by the liquid product, and ii) one or more zones 3 granulation, where these particles are subjected to drying and/or shaping and/or cooling with getting solid granules

- means for introducing a supply of thread 1b of liquid product into one or more injection zones in the form of a stream of dispersed liquid droplets,

- means for introducing feed stream 1A germ particles in one or more zones 2 injection, such that the particles are in contact with the specified liquid product covered by the specified liquid product,

means 5 for extracting granules of one or more zones 3 granulation and sorting the extracted granules into three fractions by size: granules 4 size below nominal, iameter which is too small compared with the required interval sizes, granules 4b nominal size, the diameter of which falls within the desired size range, and 4A granules with a size higher than the nominal diameter which is too large compared with the desired interval size of one or more zones 3 granulating

means 6 for directions granules 4b nominal size in the equipment further processing to obtain pellets 7 ultimate product

- means for removing the fraction of granules with the size above the nominal of the granulating process, and

means 5A for mixing fractions of granules 4 with a size lower than the nominal input power stream 1A

moreover, the fluidized bed contains a classifier 3A in one or more zones of granulation made with the possibility of separation of the granules according to their size and direction of at least part of the separated granules with a size below the nominal back into one or more zones of granulation.

Means for removing the fraction of granules with the size above the nominal can contain one or more of the following devices: device fragmentation of large granules until the granules with a size below the nominal and future trends in the supply stream of germ particles, a device for the direction of the granules with the size above the nominal in the urea melt and, thus, recirculation of the granules with the size above the nameplate the CSOs in the form of a liquid product, or device release granules size above the nominal end-use external objects.

In its fourth aspect, the present invention relates to a pellet, which contains the granulator according to a third aspect of the invention, but which also contains a classifier, in turn, contains one or more heat exchanger tubes, which are located at a distance from each other across horizontally oriented cross-section of the classifier. While the tubes of the heat exchanger does not have to be located in the classifier on the same level, on the contrary, they can be placed at a height at several levels.

The classifier corresponding to the present invention in its fourth aspect, has the advantage consists in the fact that the pipes of the heat exchanger and create the effect of retention of the particles/granules carried by gas bubbles that rise in the fluidized bed. This is useful because the bubbles contribute too intense vertical mixing, leading to a reduction of the effect of separating the particles by the classifier. In many tasks, for example, the problem of obtaining granules of urea for fertilizer particles have a tendency to acquire the size and density corresponding to the groups b or D classification Geldart (D.Geldart, Powder Technology, 7, 285 (1973);19, 153 (1961)), i.e. can achieve fluidized state only in terms of the fluidized bed, which does not contribute to the classification process. Such particles typically reach fluidized state only in thin layers with the formation of large exploding bubbles or blowout.

Thus, for pellet groups b and D on Geldart advantageous to equip the next classifier elements in the form of rods, arranged at a distance from each other so that they are more or less overlaps the cross-section of the classifier, when viewed from above. Air bubbles rising from the fluidized bed, with high probability on your way will meet with one or more core elements that will lead to retention of particles captured by these bubbles. Thus, the vertical mixing action of the air bubbles is weakened, and the remains of classifying the effect of the classifier.

The term "injection zone" in this description is called a certain area in the fluidized bed reactor, where the germ particles supplied in the specified area, result in suspension and mix with the environment, creating fluidization, and where these particles come in contact with the input liquid product, and, thus, are covered with tiny drops of liquid p is oduct. Thus, the injection zone is a place of course of the initial phase of the granulating process.

The term "granulation" in this description means a specific area in the fluidized bed, which occurs when covered with liquid product granules, leaving the zone of injection, coming in suspension and mixed with the medium, creating fluidization, and in which the temperature of the fluidized bed is reduced so that the coating on the particles is solidified or dried up environment, creating fluidization, and the particles take the form of granules due to numerous collisions with other particles.

The term "embryonic particle or fetus" in this description means any solid particle, smaller than the desired final size of granules consisting of a material which can be wetted and, thus, be covered with liquid product dispersible in the area of injection. Usually, the germ particles are small particles of the material of the final product, however, as the germ particles can act and other material.

The term "granule" in this description means a particle that has already been covered with liquid product, and then subjected to curing/drying and acquired the form in the fluidized bed granulator, becoming a solid particle core is th (germ particle) and an outer coating layer (the product).

The term "the size of the particles or granules" in this description means the average mass of the particle diameter.

The term "liquid product" in this specification means any chemical substance or mixture or substances or mixtures, which can be dispersed in the liquid state into the region of the fluidized bed, and put into contact with germ particles to form a coating that, overdiv, forms a hard outer layer on embryonic particles during drying and/or cooling while present in the fluidized bed granulator. As the liquid product can be solutions, suspensions, pastes, melts and emulsion salts, polymers, waxes, etc.

The term "external recirculation" in this description refers to a loop recycling granules that are outside of the granulator. That is, the external recirculation loop configured to retrieve pellets from the zone of granulation granulation and re-enter into one or more injection zones for further Assembly by applying a new layer of coating. External recirculation loop may contain auxiliary equipment for the screening of granules, crushing of granules larger than the target size of the granules of the final product, means for removal of agglomerates, means additional drying granules, means of transport is irowiki granules, etc. The invention involves the use of any known and conceivable recirculation loops that are familiar to specialists in the field of spray granulation in the fluidized bed.

The term "classifier" in this description means any device/machine, able to work in the area of granulation in the fluidized bed and to separate the granules in a fluidized bed state, respectively, their difference in size and/or density.

Typical means of overcoming the negative effects of boiling fluidized bed are bundles of horizontal pipes (see the classifier corresponding to the present invention) or bundles not horizontal pipes or baffles (set of deflectors, a set of perforated horizontal baffles, grids and the like), or a system for creating selective circulation of the product (for example, with inclined baffles, as in the international application WO 01/43861).

The term "heat exchanger" in this description means any plate-type heat exchanger or a tubular type, placed in the fluidized bed, so that the working medium of the heat exchanger could be inside it, and to participate in the exchange of heat with the environment, providing fluidization, which flows outside the heat exchanger. Pipe heat exchanger in cross section can be of any shape from perfectly round to any wrong is correct. The pipe section can take the form of, for example, square, rectangle, ellipse, wing or other form. Thus, the heat exchanger and the classifier can be combined in one device, as described in the examples of the present invention: a set of heat exchanger tubes of square cross-section, also functioning as a classifier (see figure 4).

The implementation of the invention

Hereinafter the invention will be described in more detail in the variant example of implementation, designed to obtain granules of urea. This variant of implementation should not be regarded as a variant of limiting the invention. The invention is a General method and a pelletizer to obtain pellets of a liquid product, including and the fertilizer granules, but that the invention is not limited.

A variant example of implementation is the pellet, corresponding to the invention in its fourth aspect, and is designed to obtain pellets of fertilizer - urea liquid urea melt. This granulator is schematically presented in figure 3. Figure 3 shows a view of the pellet from the side, shows a reactor 10 with a fluidized bed formed above the air distribution grille 11, when through the grate 11 miss pseudoviruses air 17. The reactor-granulator is made in the form of ver is icalneu mine rectangular cross-section in a horizontal direction, which narrows in a funnel at its upper part, with a funnel forms the output for pseudoviruses air. Through the partition 18 of the reactor, granulator is divided into two sections: the injection zone 12 and zone 13 of the granulation. In the area of granulation posted by classifier 21, containing a set of pipes 20 of the heat exchanger.

Germinal granules of urea injected into the injection zone 12 through inlet port 14 and is brought into contact with the dispersed liquid urea, which is fed through the inlet channel 15, which covers the germinal granules. After germinal granules are covered with liquid urea initially time and get the form, they then pass through the opening between the baffle 18 and the classifier 21 and fed to the zone 13 granulation, where are in suspended state and then divided by the classifier 21. The smallest and the lightest pellets will tend to gather in the upper part of the classifier 21, at least a portion of these pellets will flow through the upper edge 19 of the classifier and re-enter the zone 12 of the injection, where the granules will be in contact with the liquid product and covered them. The upper part of the classifier from the side adjacent to the zone of injection, it is useful to equip the overflow. Granules nominalizer and granules of higher nominal tend to gather in the lower part of the classifier and through the exhaust channel 16 go outside, where they are directed to equipment for sorting into three fractions: the granules below the nominal granule size and granule size above the nominal (hardware not shown). The classifier is equipped with six rows of tubes 20 of the heat exchanger in which the coolant temperature is lower than the temperature pseudoviruses air for the purpose of recovering heat from this air flow over the tubes 20 of the heat exchanger.

Test test

The effect of the invention is tested by a series of control tests pellet corresponding to figure 3. In all tests we used the following parameters:

The temperature of the air injection
Granulator
The water concentration in the melt[wt.%]4,5
Temperature[°C]109
Level/Delta (layer + bottom)[mm Vogt]500/550
Stream pseudoviruses air[kg/h]8000
The pressure of the melt[bar]0,9
[°C]132
Air pressure injection[bar]0,45
The granulator scrubber
Densitykg/m31110

And:

Granulator
Type injectorsbrand
The number of nozzles13
Screen baskets
The size of the cells of the upper sieve[mm]4,40
The size of the bottom sieve[mm]2,50
Crusher
The clearance for the bottom of product[mm]1,60
The backlash on top of product[mm] 2,20
The gap value for a product bypass[mm]3,60

Water used as cooling water comes from the granulator scrubber and is returned to the scrubber. The scrubber acts as a tower cooler on the principle of evaporation. Typical temperatures at the inlet and outlet, respectively, 50 and 56°C.

Structural data of the granulator-classifier with heat exchanger the following:

SETTLEMENT CONDITIONS
AnnulusIn-line space
Working pressure[bar]-5

(gauge redundant)
Design pressure (gauge redundant)[bar]1,1 6
Working environment temperature input[°C]13020
The temperature of the output[°C]9050
CONDITIONS for HEAT transfer
AnnulusIn-line space
FluidPellets/airCooling water
Value of consumption (total)[kg/h]10000/9 t/(h m2)5000:10000
The pressure drop (maxtaptime)[bar]0,2060,034
Thermal resistance scale[m2 °C/W]0,0005280,000176
The number of passes in each space14
A SET of TUBES of the heat EXCHANGER
The number of pipespieces320
Outer diameter × Thicknessmm20×20×2
Lengthmm500

In the classifier described above experimental pellet was provided by the possibility of adjusting the height of the wall of the classifier, drawn to the area of injection. This adjustable wall further in the tables is referred to as a barrier. The size of the granulator of the experimental setup were as follows:

Length: 3,09 m

Width: 0,54 m

The area of injection: 1,13 m2

Cooling zone: 0,54 m2

The total height above the bottom of the fluidized bed to the roof: 3,55 m

On the ache air: side

Venting: the Central vertical

The drawing of the experimental pellet mill is presented in figure 4.

Conducted the following tests:

The number of trials
(each periodDescription test
the test was equal to 1 week)
Tests with different values of air flow in the cooling chamber and different consumption values
1the water in the pipes of the classifier and the heat exchanger
granulator with a height adjustable barrier of 850 mm from the bottom.

Air consumption: Fair=7000, 8000 and 9000 kg/m2h
Water flow rate: Fw=0 and 5000 l/h
2The first part of a 2-week trials using cooling water at the height adjustable barrier of 800 mm from the bottom.
3The second part of a 2-week trials using cooling water at the height adjustable barrier of 800 mm from the bottom.
4Standard test without the use of cooling water, with a height adjustable barrier of 850 mm from the bottom.
51-week comparative tests without pipes classifier and a heat exchanger.
62-week comparative tests without pipes classifier and a heat exchanger.

During the test were measured by the following parameters:

Analysis of sorting on the Sith
The output of the granulator[mm, wt.%] - Dp50
The upper chamber area of the classifier fluidized bed (FBCC)[mm, wt.%] - Dp50
The final product[mm, wt.%] - Dp50
Chemical analysis
The moisture content (Karl-Fisher)[wt.%]
BiuretFormaldehyde[wt.%]
Physical tests
The point of crystallization[°C, wt.%]
Resistance to crushing PQR[kg]
Bulk density[g/l]

The test results are summarized in table 1

The classification results

The classification results shown in figure 5, which shows the distribution of particle sizes in the upper part of the classifier and at the outlet of the granulator. From the graph we see that Dp50 in the upper part of the classifier differs from Dp50 on the bottom of the granulator (i.e. output). Parameter Dp50 is a mean mass diameter of the particles. The influence of internal recycling external recycling is calculated as follows:

From the condition of energy balance in the granulator-classifier and the heat exchanger can be calculated stream flow of particles from the cooling chamber into the chamber of the injection (the internal recirculation flow). To calculate the internal recirculation flow uses the following equation (Foverflow, g):

where Q is the energy [kJ/h], F - mass flow [kg/h], Cpis the coefficient of specific heat [kJ/(kg·K)], T - temperature [K].

Table 2 shows some of the calculated values of the internal recirculation flow:

Table 2
The calculated values for the internal recirculation flow
The week of the test date/time : FEXT. recirc.[kg/h]The week of the test date/time : FEXT. recirc.[kg/h]
2/19 October105154/30 October7322
2/20 October71604/31 October8462
3/21 October88034/31 October9308
3/23 October81994/1 November 7948
4/30 October9387

The share of the flow of external recirculation is calculated from the condition of mass balance for the whole chain recirculation (granulator, sorting screens, crusher and so on). Streams of particles at the exit section of the sorting sieves are manual weighing. On this basis, the calculation of the percentage of recirculation flow. Thus F is the mass flow [kg/h].

where F. - pellet flow,

F. thread large granules

F. the product stream of the final product.

The effect of classification is useful in the sense that "smaller" particles are transferred back to the camera injection (overflow particles). Thus, the "internal" recycling affects the distribution of particle sizes and the amount of external recycling. Table 3 presents the influence of "internal" recycling "external":

Here FEXT. recirc.mass flow internal recirculation, FEXT. recirc.mass flow internal recirculation, RR is the ratio of flow recirculation, Dp50G- the average mass diameter of particles in the granulator, a SdG- the standard deviation in the granulator.

From table 3 it can be seen that the use of the classifier with the heat exchanger in the chamber granulation influence the classification of the particles in the chamber granulation, and reduces the amount of external recycling.

Results cooling

During testing at 1 week were undertaken various actions (for example, changing the flow of air and water)in order to see the impact of these actions on energy balance. The results of these various actions (in relation to air flow and water flow) are graphically shown in figure 5 and explained in table 4.

Due to the overflow of the particles (internal recirculation) from the camera granulation and to reduce the volume of external recirculation, "cold" embryonic material received in the chamber of injection, has better size distribution. So it turns out better temperature profile. Temperature profiles of the air in the part where it extends to situations classifier with heat exchanger and without the classifier is presented on Fig.6.

As for testing the classifier, the heat generated in the first chamber caused by lower flow external recirculation. Usually, in a situation without the classifier, an increased flow of external recycling has a strong influence on the temperature in the first chamber. A small decrease in temperature in the third chamber caused by the flow of particles from the cooling chamber.

tr>
Table 4
Testing cooling
Day 1 of weekTimeActionResult
203:30The classifier without cooling waterThe temperature in the cells injection 109°C; the temperature at the outlet of the granulator 87°C
212:30Increased flow rates up to 5000 l/h; remotely specified temperature granulator(109°C)Temperature in the granulator (109°C) and outlet (86°f) remain the same. Air temperature, creating fluidization increases (104°C)
217:00Reduced air flow in the cooling zone to 7000 kg/(m2h)"Overflow" is reduced. Lower cooling chambers injection. Air temperature, creating fluidization chambers injection decreases (104°C to 85°C)
223:00 Increased air flow in the cooling zone to 9000 kg/(m2h)"Spillover increases. More cooling chambers injection. Air temperature, creating fluidization chambers injection increases (from 85°C to 108°C)
305:00Reduced water consumption to 0 l/hReduction of cooling water gives a more warm stream of "overflow". Air temperature, creating fluidization chambers injection decreases (from 108°C to 101°C).
311:00Reduced air flow in the cooling zone to 7000 kg/(m2h)"Overflow" is reduced. Lower cooling chambers injection. Air temperature, creating fluidization chambers injection decreases (from 101°C to 65°C)

When used by the classifier with the heat exchanger, the main effect is the movement of particles in chamber injection. The temperature of stream overflow becomes smaller. This means that the cells of injection required to supply more energy from the melt (increase performance) or warm air to maintain adequate temperature granulation. When used, the cooling water temperature at the outlet of the cooling chamber will be approximately 10°C below while the temperature of the product exiting the granulator will be only slightly lower.

The effect, which was expected, i.e. the cooling of the pellets at the outlet of the granulator was not obtained. Possible cause is that the residence time of the particles "proper" size in the cooling chamber is small, and the particles not passing through the refrigerator, use only the lower part of the pellet mill.

Results in flaking of the coating

In the process of testing did not notice any peeling of the coating particles in the granulator or the classifier. Even after 11 days of work have not observed any problems.

The results in the emission of dust

No differences were not found.

The figures in the dust resulting from control of the water that enters the pellet mill and at the outlet of the scrubber:

Week, which was held testThe dust content (GLF) [%]
22,0
32,8
42,2
52,7
62,2

Results on the quality of the product

the who lists the average results on the quality of the product for testing the classifier in the cell pellet and without the classifier.

AnalysisUnitThe classifier with the barrier 800 mm, with cooling waterThe classifier with the barrier 850 mm, without cooling waterWithout classifier
The moisture content (KF)[wt.%]0,230,240,23
Biuret[wt.%]0,850,760,80
Formaldehyde[wt.%]0,500,480,51
Resistance to crushing[kg]3,02,83,3
Bulk density[g/cm3]1,161,161,17
Bulk density[g/l]695 701703
The content of abrasive dust[mg/kg]421538440

The increase in the concentration of the melt

Due to the fact that when using the classifier with the heat exchanger it is possible to choose a larger amount of heat conducted the test with more concentrated melt: used concentration of the melt 97% instead of 95.5 percent. The other parameters were kept identical to the previous experiments.

The results showed the improvement of the quality of the product granulation at a concentration of urea melt 97%:

ConcentrationH2OResistanceBulkVolume
melt urea [%][%]crushing [kg]density [g/l]density [g/cm3]
95,50,213,37031,17
97,00,194,27191,20

Results on the stability of the process

It is noted that when using the classifier process stability is improved. When you start recycling solid particles is stabilized faster than in the situation without the classifier. When testing classifier amount of material of large particle size was smaller compared to the tests without the classifier (see the table below). The classifier has a great influence on the stability, because of the material coming from the crusher, there were very few (as mentioned previously):

The classifier with the barrier 800 mm, with cooling waterThe classifier with the barrier 850 mm, without cooling waterWithout classifier
F (droblem.) [kg/h]4073131

1. A method of producing granules from a liquid product, comprising the following steps are:
- create at least one zone of injection into the fluidized bed, in which germ particles of the feed stream Pref is changed in contact with liquid product/cover liquid product through the simultaneous introduction of the feed stream germ particles and the supply flow of liquid product in the form of a stream of dispersed droplets of liquid
- create at least one zone of granulation in the fluidized bed, which came into contact with the liquid product is covered with a liquid product embryonic particles may be subjected to drying and/or shaping and/or cooling with obtaining granules,
- extract granules at least one zone of granulation and sort the extracted granules into three fractions: granules with a size lower than the nominal diameter which is too small compared with the required interval sizes, granules, nominal size, the diameter of which falls within the desired size range, and granules of higher nominal diameter which is too large compared with the desired interval size,
- direct the fraction of granules nominal size for subsequent processing to obtain pellets of the final product,
- remove the fraction of granules with the size above the nominal of the granulating process,
- direct the fraction of granules with a size below par in the supply stream of germ particles, and
- carry out the transfer of heat from the zone of fluidization in the classifier by using one or more heat exchangers,
moreover, the granules pass at least one classifier, placed at least in one area of the granulation in the fluidized bed, and made with the possibility of RA the division of granules according to their size, and direction of at least part of the separated granules with a size below the nominal back to the area of injection for the subsequent escalation.

2. The method according to claim 1, characterized in that the removal of the granules with the size above the nominal implemented by one or more of the following operations, which are:
- carry out the crushing of the granules with the size above the nominal to the state of the granule size below par, which is directed to the feed stream of germ particles,
- direct the granules above par in the urea melt, thus recycling the granules above par in the form of a liquid product, or
- release granules size above the nominal end-use external objects.

3. The method according to claim 2, characterized in that the heat transfer processes and the classification of the combine through the use of one or more tubular heat exchanger located at a distance from each other across horizontally oriented cross-section of the classifier.

4. The method according to claim 1 or 2, characterized in that the recirculation fraction of the smallest granules back to the area of injection is carried out by placing the classifier is near the injection zone in the fluidized bed, and allowing the pellets in the upper part of the classifier to pass through the overflow, which directs the ranula in the area of injection.

5. The pelletizer to obtain pellets of a liquid product containing:
the reactor (10) with a fluidized bed containing i) one or more zones (12) injection, where the flow of germ particles in contact with the liquid product is covered with a liquid product, and ii) one or more zones (13) granulation, where these particles are subjected to drying, shaping and cooling with getting solid granules
- means (15) to enter the supply stream of liquid product into one or more zones (12) injection in the form of a stream of dispersed liquid droplets,
- means (14) to enter the supply stream of germ particles in one or more zones (12) injection, such that the particles are in contact with the specified liquid product covered by the specified liquid product,
- means (16) to retrieve pellets from one or more zones (13) granulating and sorting the extracted granules into three fractions by size: granules with a size lower than the nominal diameter which is too small compared with the required interval sizes, granules, nominal size, the diameter of which falls within the desired size range, and granules of higher nominal diameter which is too large compared with the desired interval size of one or more zones (13) granulating
means for directing granules nominal size in the equipment further education is otci to obtain pellets of the final product,
means for removing the fraction of granules with the size above the nominal of the granulating process,
means for mixing fraction of granules with a size below par with the feed stream (14),
characterized in that the fluidized bed contains a classifier (21) in one or more zones (13) granulating made with the possibility of separation of the granules according to their size and direction of at least part of the separated granules with a size below the nominal back into one or more zones (12) injection, and the classifier (21) further comprises one or more heat exchangers.

6. The granulator according to claim 5, characterized in that the means for removing the fraction of granules with the size above the nominal can contain one or more of the following devices:
device fragmentation of the granules with the size above the nominal obtaining granules with a size below the nominal and future trends in the supply stream of germ particles,
device direction of granules with the size above the nominal in the urea melt and, thus, recirculation of the granules with the size above the nominal in the form of a liquid product, or
device release granules size above the nominal end-use external objects.

7. The granulator according to claim 5, characterized in that the classifier is equipped with one or more pipes (20) of the HEA is a, spaced from each other transversely horizontally oriented cross-section of the classifier.

8. The granulator according to claim 7, characterized in that the pipes (20) of the heat exchanger are located in the classifier on several levels in height.

9. The granulator according to claim 5 or 6, characterized in that the classifier (21) contains overflow (19), is made with the possibility of sending granules very small fraction back into one or more zones (12) injection.

10. The granulator according to claim 5 or 6, characterized in that the reactor (10) is made in the form of a vertical shaft of rectangular cross-section in the horizontal direction, which tapers in a funnel at its upper part, with a funnel forms the output for pseudoviruses air,
the zone of fluidization is formed over the diffusion grating (11) through the transmission pseudoviruses air (17) through the grille (11), and the zone of fluidization separated by a dividing wall (18) to (12) injection and (13) granulation.



 

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20 cl, 16 dwg

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20 cl, 4 ex, 4 tbl, 37 dwg

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9 cl, 2 dwg

FIELD: chemistry.

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21 cl, 4 dwg

FIELD: chemistry.

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1 dwg, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention can be used in production of detergents and bleaching agents. Granular sodium percarbonate is obtained through granulation in a fluidised bed which contains sodium percarbonate particles, into which aqueous hydrogen peroxide solution and aqueous sodium carbonate solution are sprayed through at least one multi-component nozzle with external mixing, with simultaneous evaporation of water. The sodium carbonate solution additionally contains sodium carbonate and/or sodium percarbonate in suspended form. Before feeding into the multi-component nozzle, the sodium carbonate solution is passed through a mechanical disperser to disperse solid substances using shearing force created between the stator and the rotor.

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16 cl, 4 ex, 1 dwg

FIELD: machine building.

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4 dwg

FIELD: technological processes.

SUBSTANCE: invention relates to the field of chemical technology and may be used to produce granulated sodium arsenite in processing of reaction mass produced at the stage of alkaline hydrolysis of lewisite. Liquid reaction mass is exposed to continuous convective spraying drying in fluidised bed. Process is carried out at the temperature of layer 70÷150°C and at underpressure of 10÷200 mbar, and nitrogen is used as fluidised and spraying agent.

EFFECT: invention provides for hardware and structurally simple, technologically and ecologically safe process applicable for large-capacity production of granulated sodium arsenite suitable for long-term storage.

3 cl, 1 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to device (10) intended for processing powder materials that incorporates work chamber (16) to process material therein. Device bottom (18) is formed by several overlapping circular guide plates (22-24) arranged one above the other. Circular slots (25, 26) formed there between allow work air to flow there through. At the center of said bottom (18) there is circular-slot-like nozzle (30) with its sprayer can spray fluid in the form of flat jet (44), approximately, parallel to bottom plane.

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9 cl, 2 dwg

FIELD: production processes.

SUBSTANCE: invention refers to method of substance granulation in fluidised layer and granulator for its implementation. Method consists in the following: by means of fluidising air fluidised layer of granules of granulated substance which is supplied to fluidised layer in the form of inoculating seeds is formed and substance or liquid for granules growing are continuously supplied to fluidised layer. Fluidising air flow is divided into many flows which are supplied to various zones of fluidised layer with different rate within limits from minimum in first zone, enough for maintaining fluidised layer, to maximum in second zone, required for formation of circular motion, actually, eddy motion of granules of granulated substance in fluidised layer and its maintaining around horizontal axis.

EFFECT: method of granulation in fluidised layer and granulator for its implementation (versions) is described.

10 cl, 6 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to production of granular calcium chloride, which can be used in communal and road facilities. The method of producing granular calcium chloride involves preparation of a concentrated solution of calcium chloride from evaporated clarified still waste liquid from ammonia-soda production and subsequent dehydration and crystallisation. Non-ionic surfactant is added to the clarified still waste liquid and then evaporated to concentration of calcium chloride of 35-45%, after which it is taken for dehydration and crystallisation in a boiling-spouting drier-granulator. The spouting bed in the drier-granulator is created by a stream of furnace gases, fed through a central inlet at a rate of 50-55 m/s at temperature 700-750°C, and the boiling bed is created by an air stream at temperature 20-60°C, which is fed at a rate of 3-5 m/s.

EFFECT: intensification of the drying process, recycling still waste liquid, obtaining granular calcium chloride.

6 cl, 1 dwg, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention refers to granulation process in fluid bed of various substances, e.g., carbamide, ammonium nitrate, ammonium chloride and other similar granulated substances. Substance granulation process in fluid bed (F1) involves cooling finishing granules in the second fluid bed (F2). Herewith the same cooling air flow is used consistently for continuous generation and maintenance of cooling (F2) and granulating (F1) fluid beds arranged in tandem relative to the specified running cooling air flow. Granulator for fluid bed granulation includes container-shaped self-supporting structure limiting internal cavity wherein granulation process takes place and there is a partition mounted as a support for granulating fluid bed (F1). Granulator is provided with a plate arranged in the internal cavity of self-supporting structure, spaced under the partition and forming the base being a support for cooling fluid bed (F2), consisting of hot granules produced in granulating fluid bed (F1). The beds are connected through perforated, latticed, mesh or otherwise gas-permeable partition. The internal cavity is equipped with vertical downpipe to pour finished granules from granulating fluid bed (F1) to cooling fluid bed (F2). Under base-forming plate sheet, there are fluidising air feeder and deliverer to the internal cavity of self-supporting structure and cooling and granulating fluid beds forming and maintenance units.

EFFECT: reduced air consumption required to complete granulation process.

7 cl, 2 dwg

FIELD: technological processes.

SUBSTANCE: invention concerns granulation method in fluidised layer for various substances, such as carbamide, ammonium nitrate, ammonium chloride and similar substances viable to granulation. Particularly invention concerns method of granulation in fluidised layer with temperature adjusted by hot air feed, and to granulation plant for implementation of the method. During granulation of a certain substance in fluidised layer at adjustable temperature, finished hot granules are selected from fluidised granulation layer and cooled down in fluidised cooling layer continuously formed and sustained by fluidising air flow. At least a part of fluidising air leaving cooling fluidised layer of finished granules is fed to fluidised granulation layer. Cooling and granulation fluidised layers are positioned in sequence against air flow passing through them. Granulation plant used in the described method includes self-carrying construction with partition serving as support for fluidised granulation layer. Under the partition a step away from it, a base-forming sheet serving as support for fluidised cooling layer is located. Fluidised granulation and cooling layers interface over a perforated, grid, mesh or other gas-permeable partition. Finished granules are poured from fluidised granulation layer into fluidised cooling layer over transition stack. Devices of fluidised air feed and distribution in internal cavity of self-carrying construction are located under base-forming sheet.

EFFECT: reduced total energy expenditure required to maintain fluidised layer temperature at specified level sufficient for optimal granulation process finish.

10 cl, 2 dwg

FIELD: production of powdery materials.

SUBSTANCE: the invention presents an installation with a fluidized layer and with a complex spray drying and a method of production of the powdery materials dried with the help of a spray drying, whose properties can be varied purposively depending on the application. The installation contains a spraying column, a fluidized layer, a module of a spray drying, one or several of additional spraying or pulverizing nozzles for a liquid component located in a fluidized layer, a batching gear for a powder and a powder returning gear with a fan. The module of a spray drying includes a spraying system consisting of a heated doublet spraying nozzle in which a liquid) component and sputtering air are merged. The installation contains also a dynamic filter integrated in it used for clearing of the gas of from a part of a powder. The spraying column is located above the fluidized layer. The latter for giving direction of motion of the stream of a powder it is supplied with a perforation in Conidur base. The module of a spray drying is located in the spraying column above a fluidized layer. The doublet spraying nozzle is supplied with the coaxially located powder returning gear and an enveloping stream of hot air. The spraying system is made in the form of an integrated module. In the method of production of a powdery material at the first stage the following components are combined: a liquid component, a spraying gas, a powdery material and hot air. The formed powdery product falls on a fluidized later, is caught up, fluidized and transported further. At one or more stages of granulation it is pulverized with an additional liquid component, dried and transported with the fluidized layer to the powder batching gear, from which a part of the powdery material is returned in the process. The invention ensures fast removal of surface moisture, prevention of granules adhesion and production of particles of the given size.

EFFECT: the invention ensures fast removal of surface moisture, prevention of granules adhesion and production of particles of the given size.

14 cl, 2 dwg

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