Field of the invention

The present invention refers to a method for drying of solid bulk materials with gas in a fluidized bed and a speed dryer, which carries into effect the method, that can be applied in the construction area, in the chemical industry, in the metallurgy, in the mining industry, in the coal output area, in the food-processing industry and in other industries, where solid bulk materials such as sand, limestone, coals, ores, fertilizers etc. are required to dry.

Background of the invention

From literature and from practice it is known that the most commonly used method to dry solid bulk material with gas is the thermal one. The main hydro-dynamic regimes when interacting within the system "gas-solid bulk substance" are: a thick layer of solid bulk material (mobile or static), through which and/or out of which the gas phase is in motion; and in a fluidized layer in the two phases - pneumatic transportation and fluidized bed.

It is considered that drying with gas through a solid bulk material is a process with relatively low effectiveness. The fluid drying processes are more effective and they face an increasing practical implementation. The pneumatic regime is intensive and effective for execution of transportation processes and in particularly in heat-mass exchange processes in drying of damp bulk solid material with hot dry gas, but its implementation in practice in view of the pneumatic transportation is limited because of the high material and energy costs for its realization. Similar to the efficiency of the pneumatic regime is the mode of a fluidized bed in which energy and material costs are relatively low. In practice, however, well established groups of structures operate in modes, or in a combination of these basic modes or their characteristics are close, but not enough to achieve these fundamental modes. Such groups are: tubular dryers, vibration dryers, dryers with fountaining in a stream layer, Vortex dryers etc.

On the other hand, dryers with the system "gas-solid bulk substance" working with gas in a fluidized bed are more widely spread in the recent years. In a patent US 6, 189, 234 Bl a continuous fluidized bed dryer is described, which consists of trough shell, on the top with lid closed. The bottom of the body is perforated and it acts as a supporting grid for establishing and maintaining a fluidized bed through which the drying gas passes, thus adjusting the solid bulk material in a fluidized layer. At a certain height above the bottom, in the fluidized bed area a shaft is mounted with perforated flat shovels attached to the shaft with a slight tilt in the direction of material ejection. The purpose of the shaft is to support the passage of the dry solid material in the two-phase fluidized bed from the entrance to the exit of the dryer with constant slow rotation, thus supporting further the destruction of the large bubbles in the fluidized bed and limiting the bonding of the material on the walls surrounding the fluidized bed.

It is known that the regime of the fluidized bed is characterized with high efficiency of the heat-mass exchange processes, by intensity of mixing and movement of the phases with strong turbulent motion of the gas boundary layer on the border "gas-solid substance", with high mobility of the entire fluidized layer as well, resembling that of a fluidized bed, and due to that, an approximate alignment of the phase parameters is taking place.

However, there are certain specific features in the system "gas-solid bulk substance" when it is in regime of fluidized bed, that should be considered in the drying process. Above all, it is implemented in a certain range of the gas velocity - from the boiling point of the solid layer to the point of their haunting movement. If the gas velocity is higher than the haunting point, the system goes into pneumatic transportation, if below the boiling point - the system goes to a regime with a thick layer of solid bulk material.

When, for the establishment of the fluidized bed, only the energy of the participating phase flows and foremost that of the gas phase is used, it is a requisite a supporting grid to be used for even distribution in the fluidized bed of the incoming gas phase, and for maintaining the fluidized layer itself, and also for transforming part of the kinetic energy of the gas phase into an energy of the fluidized bed.

The disadvantage of using the supporting grid is that it is characterized with high hydraulic resistance, which leads to a general increase in the hydraulic resistance realized in the fluidized bed. The latter is due to the transformation of part of the kinetic energy of the gas phase in energy of the fluidized bed, which leads to energy losses and generation of hydraulic resistance of the supporting grid, representing the majority of the total hydraulic resistance ot the fluidized bed as a whole.

Another type of dryers used in practice are those working in the so-called "vortex mode", in which heat-mass exchange surfaces are created as in the fluidized bed, but can not achieve the same degree of strong turbulent motion of the gas in the gas boundary layer.

A known Vortex dryer is a model of the German company HAZEMAG (V. Duda, Tzement, Moscow, Stroyizdat, 1981 , p.1 13-1 15), in which an external energy is imported for propulsion (dispersion) of the solid bulk material. The drying agent are flue gases, but can be also used other gaseous drying agents. Vortex dryer is made of an iron body with rectangular cross section, fitted on top with a rounded lid, and on the bottom are two trough-shaped grooves where are mounted shafts with their blades, ending with hammer-shaped bumps. The body is divided by vertical walls into several parts - working sections, the bulkheads start from the lid and finish just above the space ot the shafts. In the fast rotation of the shafts, their shoulder blades throw up in the operating sections the dehydrated solid material, and as it reaches a certain height, depending on the size of the particles, it is directed into the sides of the work area and drop down to the shaft area. Simultaneously with ejection up of the solid material, the thick layer of it, remaining on the bottom, is pushed towards the exit of the dryer for its removal. From the first working section, the hot gas enters the second and the following sections through holes formed under the vertical walls of them, increasing its speed as the intersection of the flow decreases. It is alleged that the gas which enters through the above-mentioned holes in the front end of the working section, is rapidly expanding, striving to fill the entire space above the shaft section and at the end of the working section, the gas is compressed again and passes through a hole under the bulkhead for the next working section.

In our opinion, in this movement and spontaneous expansion and compression of the gas in each working section, filling of the entire workspace of the section with gas cannot be achieved evenly, as far in height less quantity of gas should reach. Furthermore, the gas movement is hindered by the interaction of ascending and descending flows of the two-phase system, which results in uncontrollable vortical zones. In order to compensate this and to improve the gas supply at the top of the workspaces, additional holes in the vertical walls between the working sections are cut. Through them hot gas is also supplied, entering into the extra hole which spreads up and down in the working volume of each working section, however this amount of gas is relatively very small portion of the total supply with gas and does not alter the above-described picture of chaotic hydro-dynamic interaction between the gas and the solid phase. Due to the uneven distribution of the amount of gas moved in the distinct sections, a strong turbulent motion is formed at the boundary layer between the gas and solid particles in various degrees, which worsens the overall speed. of drying. The above-described movement of gas between the working sections, with its irregular and chaotic motion is the reason for the uneven movement of ejected particles, in which there is not enough good contact between gas and solid particles, and hence deteriorates the overall process.

Based on the above-said, it can be summarized that the main disadvantage of this type of vortex dryer is in the inability strong turbulent motion in the gas boundary layer to be achieved.

SUMMARY OF THE INVENTION

Problem of the present invention is to create a method and device for drying of damp bulk solid materials with hot dry gas through which to overcome both the deterioration in efficiency of the drying in the vortex dryer as a result of inadequate turbulent motion of the gas in the gas boundary layer in the workspace, and also the high hydraulic resistance of the fluidized bed, conditioned by the supporting grid, that is necessary for establishing and maintaining of the fluidized bed.

The problem of the invention is solved by a method for drying of solid bulk materials with hot dry gas, in which the interaction between the gas and solid bulk material proceeds in hydrodynamic regime of fluidized bed, with the introduction of external energy needed for the generation of the fluidized bed. To reduce the hydraulic resistance in the gaseous phase, instead of supporting grid a system with shafts with attached to them blades is used, and the blades finish with tips, thus to submit additional, kinetic energy for achieving a circulation of solids in the fluidized bed. In doing so, are created and implemented fluidized layers with straight and with opposite direction of movement of the phase flows of gas and solid bulk substance.

The method set, according to the invention, is achieved by a speedy dryer, which includes: a body consisting of two walls, sloping in different directions toward the perpendicular to the horizontal plane, still connected at the bottom, with a rectangular box, opened from the bottom, and forming the upper part of the shaft space; vertical metal walls forming volumetric workspaces and a separation space inside the case of the dryer; an upper lid of the shell; a cover of the inlet side of the dryer section with a channel tor the supply of damp solid bulk material, with channel for hot gas submission, a side cover of the output section of the dryer with a channel for the exhaust gas; a bottom of the body, with two shafts in it with blades and outlet for dried solid material and supporting structure of the dryer.

LIST OF FIGURES

Figure 1 - General view of the dryer;

Figure 2 - Bottom of the body;

Figure 3 - Shaft with attached blades with tip endings;

Figure 4 - Longitudinal section of the dryer in reference to the movement of the phase flows from input to exit;

Figure 5 - Cross section of the dryer in A-A;

DETAILED DESCRIPTION OF THE INVENTION

In order the essence of the method and the speed dryer to be realized, and in accordance with the invention to be reduced the hydraulic resistance in the gaseous phase, instead of a supporting grid, a system of shafts with attached to them blades with tip endings is applied, thus two-phases boiling fluidized bed to be created.

Unexpectedly for the skilled person, it was found that, at a certain interval of the velocity of the supplied to the system gaseous phase and at certain angular velocity of the shafts' revolutions, by which additional kinetic energy is introduced, necessary for the layer solid phase circulation, it is possible fluidized beds to be created and to be supported, sustainable and effective in reference to the heat-mass transfer processes, and what's more, they are realized in both straight and opposite direction movements between the gas and the raising particles in the solid phase of the fluidized bed.

For the realization of the method, according to the invention, the hot gaseous phase and the solid bulk material (representing a poly-disperse system) are supplied in straight direction flow, and as depending on the type of the dried material, the velocity of the supplied in the dryer hot gas is above the point of the haunting movement of the average diameter of the particles, the temperature varies from 100 C to 800 C, and the throwing out of the solid particles of dried material in the volumetnc working spaces is carried out by a shaft system, at sharts rotation velocity from 150 to 780 revolutions per minute.

On their way of motion of the gas and the solid bulk material from dryer's input to dryer's exit, three successive, sustainable and effective in reference to the heat-mass transfer process, fluidized beds are carried out. In the first and in the third fluidized beds the gas moves in the same direction with the ejected from the shaft blades solid particles, while in the second fluidized bed the direction of the gas motion is opposite to the direction of movement of the solid particles.

The method of drying, according to the invention, is realized by a speed dryer, which consists of four rigidly connected structural parts - inlet section, body (working section), exit section and supporting section.

The supply with damp bulk material at the entry section takes place in a rectangular channel 1. The larger wall of the channel 1 is oriented perpendicularly to the main direction of gas and solids motion from input to exit of the dryer. The hot dry gas enters the inlet section through a rectangular channel 2, which is open to the dryer body and inclined at an angle of 60° to 70° to the horizontal plane. Side cover 3 of the inlet section, connects the afore-mentioned structures and pressurizes the dryer from the supplied flows, as its connection with the corps is stationary, in particular - flange.

The body provides the speed dryer with basic workspaces for conducting the heat-mass transfer process in drying of damp solid bulk material with hot dry gas in the mode of fluidized beds by using external energy for their (the fluidized beds) generation and support.

The body is sealed on top with rounded top cover 4. The two opposite walls 5 of the body are inclined to the horizontal plane at an angle of 60° to 85°, so that the distance between them in the upper body is larger than at the bottom, where the walls 5 are rigidly connected in particular with weld to an opened with its fundamentals ectangular box 6, which forms the upper shaft area. At the bottom of the body 7 (Fig. 2), there are two trough-shaped grooves with shafts 8 installed into them, powered by electric motors, to which stationary blades 9 are connected, which end with replaceable tips 10 (Figure 3), attached moveably to them and slightly inclined in the direction of the solid drying material. Vertical bulkheads 11a, 11B, 11c and l id (Figure 4) are still attached to the walls 5 of the body at an equal distance to each other and staggered in height so as to form openings through which the gas passes consecutively in the bottom and in the top parts of the body. The bulkhead lie is located at the end of the body, and torms an integral part, i.e. inner wall of the side cover 12- of the exit section of the dryer, and part of the wall of a rectangular channel 15 for removal of the exhaust gas from the dryer.

The side cover 12 of the exit section is designed to pressurize the back side of the body by attaching it permanently, in particular through the flange connection, as well as to ensure separation and removal of exhaust gas and the dried solid bulk material from the dryer. The above-mentioned bulkhead lie and the side cover 12 refer constructively to the exit section of the dryer. At the back, the bottom the body 7 forms a rectangular outlet for the dried solid material 13, which is still connected, in particular welded to a rectangular channel 14 for removal of the dried solid bulk material. At the top of the side cover 12 of the output section a rectangular channel 15 is formed, used for removal of the exhaust gas from the dryer. The back side of the rectangular channel 15 is sloping outwards to the level of the lower edge of the vertical bulkhead l ie, hence tapering inwards at an angle of 45° until reaching the box 6.

Bulkheads 11a, 11B, 11C and lid form with the walls 5 of the body three consecutive volumetric workspaces with the shape of a polyhedron, which has a structure similar to that of a truncated pyramid, with two rectangular bases, that are open, two opposite side walls, that are parallel and trapezoidal, and the other two opposite side walls are rectangular and slanted in different directions in relation to the perpendicular to the horizontal axis. Thus, the volumetric formed workspaces are facing with their small bases to the shafts' space above the box 6, as three sustainable two-phase fluidized beds are developed in them.

One final - fourth workspace is created in the body of the dryer, which is formed between the walls 5, the bulkhead lid, and the vertical bulkhead lie, located in the side cover 12 of the output section of the dryer. The last working volume has the shape of polyhedron with structure similar to the above-described volumetric workspaces, and is turned again with its little base toward the shaft's space, and in fact is an inertial separator for the solid particles of the two- phase system.

The bulkhead 11a starts at just under the top cover the body 4 and ends at a height of the shafts' space, forming into the walls 5 of the housing an opening through which hot gas and damp bulk solid material are supplied from the inlet section into the body.

The bulkhead 11B starts from the shafts' space, and is so high, that the area of the hole formed by the vertical bulkhead 11a, the top cover 4 of the body and the bulkhead 11c allows the gas anu ine small parucies oi suiiu material aincu away vvuii me gas ιυ ss uuuugn mc s a c with no speed change and to proceed in the second volumetric workspace.

The vertical bulkhead 11c starts at just under the top cover 4 of the body and its height is such, that the area formed at the level of its, lower : edge, the bulkhead 11B and the walls 5 of body to be equal to the area formed by the bottom edge of the vertical bulkhead 11c, the walls 5 of the body and the shafts' space to the bottom of the bulkhead l id.

The vertical bulkhead lid starts very close to the shaft, as far as that part of it is corresponding to the fourth volumetric working space in the body, and here no blades 9 are mounted on the shafts 8. The upper edge of the bulkhead lid is on the level with the upper edge of the vertical bulkhead 11B.

Bulkhead l ie is forming an internal wall of the side cover 12, and is rigidly connected thereto by welding, in such a way, that also appears to be a natural continuation of the front side of the rectangular channel 15 for removal of the exhaust gas from the dryer.

Blades 9 are successively set on the shafts 8, at an equal distance from each other, with a lateral displacement, providing their deployment in a spiral around the shaft 8, and thereby, the upper edges of the sloping tips 10 form in movement of the shafts 8 a stretched spiral line.

Blades 9 are mounted on the shafts 8 by washers, and in turn the replaceable tips 10 are connected to the replaceable blades 9 by bolts.

The purpose of the supporting section is to absorb and transmit to the foundation on which the dryer is mounted its weight and pressure of the dynamic load during operation of the device. The supporting section consists of a rectangular frame 16 with four load bearing legs, and its connection with the dryer is still through four welded to the bottom 7 hells 17.

The dryer works in hydro-dynamic regimes of two-phase fluidized beds of the system "gas-solid material," as for their creation an external kinetic energy is used. On the way of movement of the gas and that of the solid bulk material from input to exit in the dryer, three consecutive, sustainable and efficient fluidized beds are realized in relation to the heat-mass transfer process. In the first and in the third of these layers, the gas moves in the same direction with the discharged from blades 9 (mounted on the shafts 8) solid particles, as in the second fluidized bed, the direction of the gas motion is opposite to the movement of solid particles. The dryer operates as follows:

The damp bulk solid material is supplied into the dryer through the rectangular channel 1. From channel 1, the bulk solid material enters the volume between the side cover 3 of the input section and the vertical bulkhead 11a, where it forgathers with the hot dry gas entering through the rectangular channel 2. Due to the high velocity of the gas movement, which is close to the point of the haunting movement of solid particles with an average for the poly-disperse system diameter, the particles of the same material with a smaller size form with it (the gas) a solid- gaseous mixture, which passes through the rectangular opening of the vertical bulkhead 11a, and enters into the first volumetric workspace of the body, that is formed between the walls 5 and bulkheads 11a and 11B. Larger particles of solid material fall onto the bottom of the channel 2 and slide down on the inclined wall in the shaft's space corresponding to the first volumetric workspace in the body.

The first volumetric workspace is shaped like a polyhedron, with a structure similar to that of a truncated pyramid, the two opposite side walls are trapezoidal and parallel, and the other two opposite roundabout walls are rectangular, equal and are inclined in different direction in relation to the perpendicular to the horizontal axis, as the latter are part of the inclined walls 5 of the body. The tetragonal bases of the above-described polyhedron are open, as its small base is on level with the bottom edge of the vertical bulkhead 11B, and the large base - at the upper edge of the same bulkhead.

The solid-gaseous flow enters through the opening, formed close to the small base of the first volumetric workspace with velocity of the haunting movement of the particle with an average for the solid bulk material diameter. Together with the discharged from the shaft area solid particles, the incoming solid-gas flow is directed upward to the large volume of the workspace to the expanding up intersection, where the gas velocity decreases due to the increased cross-section of flow, to the speed of boiling the particle with an average diameter of solid bulk material.

Shafts 8 are rotated with high angle speed - from 150 to 780 revolutions per minute, and as a result from the opening between the shaft and the small base of the first volumetric working space, in the central part of the last a solid material is discarded continuously from the blades 9, mounted on the rotating shafts 8. The lifting in volumetric workspace of the discarded solid material is also supported by the rising gas ana witn tneir interaction a stable fluidized bed is rormea wnose neigm varies, aepenamg on me type or me sona OUI maienai, on uic uuw raie, and on the shaft's angle speed, but does not exceed the upper base of the volumetric workspace. At a certain height, the rising solid particles (depending on their size), lose their kinetic energy, and under the influence of their weight are directed down to the walls of the volumetric workspace. Those of them that slide, friction on the walls of the workload space, lose extra kinetic energy and, if their diameter is above the average for the poly-disperse system, fall back into the shafts space. Part of the falling particles that do not reach the walls of the volumetric workspace, especially those with a diameter smaller than the average for the poly-disperse system are covered by the ascending two-phase flow in the center of the fluidized bed and thereby ensure the circulation of the solids in the fluidized bed.

The specific constructive positioning of the provided with inclined tips 10 blades 9 on the shafts 8 allows gradual ejection of the thick layer of the dried material in the shaft's space to the rectangular outlet 13 for removal of the dried solid material.

Evolved above the first fluidized bed hot gas, drifts off with it very small particles of solid material through the opening over the vertical bulkhead 11B, advances to the next second volumetric workspace, that is formed between the walls 5 of the body and bulkheads 11B and 11c. It has the same form as the first volumetric working space in the body. Since the vertical bulkhead 11B can not be positioned below the upper level of the shaft space formed below the hole, beneath it (vertical bulkhead 11B) an opening is formed with cross-section that lets a small part of the gas to enter through the shaft's space from the first into the next second volumetric workspace. The intersection of this opening is further reduced to a maximum by the thick layer of solid bulk material in the shaft's space, and therefore the gas passed through the opening does not affect the structure of the created in the second volumetric workspace fluidized bed. Furthermore, the increased gas velocity at the base of the second fluidized bed, inhibits further the passage of the gas between the two volumetric workspaces in the shaft's area.

In the second volumetric workspace gas flows from top to bottom and due to the friction between it and the discharged up solids, it prevents to some extent their upward movement. But as the kinetic energy of the ejection is much larger, they overcome this extra resistance and rise again, and unexpectedly for the skilled person, forms a second stable fluidized bed with direction of movement, opposite to the phase flows, albeit at less elevation level than that achieved in the first volumetric workspace of the body. Once the solid particles leave the area of the second iiuiaizea oea, tney turn aown, wnere some oi mem move oacit into me cir uiauuii υι uic sunu phase, while another part of them, engaged in the formed solid-gaseous flow of the second fluidized bed, through the hole in the vertical bulkhead 11c pass into the third volumetric workspace body formed between the walls 5 and bulkheads 11c and lid.

The third volumetric workspace has the same shape and structure as the first volumetric workspace, and therefore the traffic flows and the formation of the fluidized bed by them have the same characteristics with those in the first fluidized bed.

The last, fourth volumetric working space is formed between the walls 5 of the body and bulkheads l id and l ie, where the vertical bulkhead l ie is a part of the anterior wall of the rectangular channel 15 for exhaust gas removal from the dryer. This volumetric workspace represents an inertial separator for solid particles from the gas, which leave the third fluidized bed. After passing through the hole above the bulkhead l ie, the tilted-down two-phase flow reaches the lower edge of the vertical bulkhead lie, where sharply changes its movement direction and through the rectangular channel 15 leads out from the dryer. In this reverse movement of the exhaust gas, the larger particles fall, by sliding on the walls of the fourth volumetric workspace and on the angled downward part of the channel 15 to the bottom hole 13, which is connected to channel 14 for dried solid material removal. Only solid particles with very small diameter remain in the exhaust gas, which leaves the dryer through the rectangular channell5.

The placement of the shafts 8 blades 9 with inclined tips 10 installed on them is such as, when the shafts 8 are rotating, the upper edges of the tips 10 form a stretched spiral line, ensuring the movement to the outlet 13 of the remaining in the shaft's space thick layer of the dried solid material.

The supporting rectangular frame 16 assumes the burden of the dryer through the base heels 17, lying on it, and via the four legs to the frame carries the weight to the foundation on which the dryer is mounted.

The advantages of the method and of the speed dryer according the invention are:

- the drying process in the speed dryer is conducted with maximum use of the heat-mass transfer surface of the particles and strong turbulence of the gas in the gas boundary layer on the same surface, which confirms the high value of intensity coefficients of the dryer; - introduction oi external Kinetic energy inruugn uie unary suan system icuuuca uic hydraulic resistance in the gas phase;

- imported through the shaft system kinetic energy for the circulation of solid phase in the fluidized bed makes it possible to create and maintain sustainable and effective in terms of heat- mass transfer processes fluidized beds, moreover it is realized in straight direction and in opposite direction of the movement between the gas and the rising from the solid phase particles in fluidized bed.

EXAMPLES FOR THE INVENTION PERFORMANCE

The invention is illustrated with the following examples, which explain it without limiting its range of protection.

Example 1

Drying of limestone

In the speed dryer according to the invention a damp cut into small pieces limestone is supplied with density ς = 2600 [kg/m ³ ] and starting moisture C ^B = 19.7 mass%. (C ¹ = 19.7 mass %)

The drying agent are flue gases with starting temperature t = 720°C.

The rotation velocity of the shafts in the drying process is 520 revolutions per minute. The average diameter of the particles of the drying limestone is Dcp = 3.4 mm (Dav = 3.4 mm).

Each of the volumetric working spaces, where the two-phase fluidized bed process is developed has a volume V = 1.437 m ³ or for the three volumetric working spaces of the dryer is Vgeneral = 4.31 1 m ³ (Vtotal = 4.31 1 m ³ ).

The velocity of the flue gases at the small base (upturned to the shaft area) in each of the working polyhedral shaped volumes of the dryer varies from 5 to 8 m/s, and the velocity of the same gases at the large base in each of the working polyhedral shaped volumes of the dryer varies from 0.8 to 2.6 m/s.

When the dryer works with damp cut into small pieces limestone with an average size of the particles as shown above, the velocity of the gas at the lower base in each of the working polyhedral shaped volumes of the dryer is close to the point of particles' haunting movement, wnne ai ine larger oase or me poiyneurai snapea volumes me gas veio ny is auuvc ic uimuig point.

At the output of the dryer, the moisture of the dried limestone is C ^B _0U t ⁼ 0.97 mass % (COut ⁼ 0-97 mass%), and the quantity of the evaporated from the limestone dampness is M ^evp = 780 kg/h (M ^evp = 780 kg/h).

The dryer productiveness related to the damp cut into small pieces limestone is MB = 4193 kg/h (Ml = 4193 kg/h).

The effectiveness of the dryer work is characterized with a coefficient of intensity, which is the quantity of water evaporated for one hour from one cubic meter of the working volume of the dryer.

The dryer's coefficient of intensity for limestone is I =181 kg H ₂ 0/ (m . h).

Example 2

Drying of sand

In the speed dryer according to the invention a damp sand is supplied with density ς t, ⁼ 1500 [kg/m ³ ] and starting moisture C ⁿ = 14.8 mass%. (C ^s = 14.8 mass %)

The drying agent are flue gases with starting temperature t = 690°C.

The rotation velocity of the shafts in the drying process is 440 revolutions per minute. The average diameter of the particles of the drying sand is Dcp = 3.1 mm (Dav = 3.1 mm).

The total volume of the three volumetric working spaces of the dryer is Vgeneral = 4.31 1 m ³ (Vtotal = 4.31 1 m ³ ).

The velocity of the flue gases at the small base (upturned to the shaft area) in each of the working polyhedral shaped volumes of the dryer varies from 5 to 8 m/s, and the velocity of the same gases at the large base in each of the working polyhedral shaped volumes of the dryer varies from 0.8 to 2.6 m/s.

When the dryer works with damp sand with an average size of the particles as shown above, the velocity of the gas at the lower base in each of the working polyhedral shaped volumes of the dryer is close to the point of particles' haunting movement, while at the larger base of the polyhedral shaped volumes the gas velocity is above the boiling point. At the output ot the dryer, the moisture ot the dried sand is ⁽ J ^" _ou t ⁼ U.su mass. ^u /o ( U ^" ₀ ut = 0.80 mass%), and the quantity of the evaporated from the sand dampness is M ^evp = 61 1 kg h (M ^evp = 61 1 kg/h).

The dryer productiveness related to the damp sand is Mn = 4150 kg/h (Ms = 4150 kg/h). The dryer's coefficient of intensity for sand is I =142 kg H ₂ 0/ (m ³ . h).