RU2159403C1 - Suspended layer drier at active hydrodynamic mode - Google Patents

Abstract

FIELD: drying technology; drying of thermolabile materials; chemical, medical and food-processing industries. SUBSTANCE: proposed drier includes cylindrical-taper chamber with material inlet branch pipe mounted tangentially, reflector mounted for axial motion ands confuser for introducing the main flow of drying agent; mounted in cylindrical portion of chamber along its axis is hollow insert made in form of hyperboloid whose upper shear is rigidly secured on cylindrical surface of chamber above inlet branch pipe mounted tangentially; circular clearance is provided between lower shear of chamber and its lateral surface; passages for removal of used drying agent are provided on outer surface of hollow insert from center to upper shear; flow area of these passages is adjustable. EFFECT: intensification of drying process; avoidance of caking of material; improved quality of dried product. 3 dwg

Description

 The invention relates to a drying technique, namely to drying heat-sensitive materials, and can be used in the chemical, medical, food industries, for example for drying dietary fiber.

 In industry, the technique of suspended (boiling, fluidized, flowing) bed is widely used as one of the most effective means of intensifying the drying process of materials.

 A known dryer for bulk and fibrous materials (A.S. N 1305513, F 26 B 17/10, BI N 15, 1987), comprising a housing with a loading nozzle in the lower part connected to a gas supply manifold, and a gas suspension outlet port axial displacement of the upper part of the casing, a hollow insert coaxially placed inside the casing, forming an annular cavity with it, divided by radial partitions into sector sections, while the casing and the insert are made in the form of truncated cones with different tapers, facing more and bases up and the pie section connected to the feed conduit and the output conduit gas suspension parallel.

 However, the known design does not provide for an organized trajectory of the movement of particles of the material, which leads to their uneven drying and increase the duration of the process.

 The closest in technical essence is a suspended layer dryer (A.S. N 1372165, F 26 B 17/10, BI N 5, 1988), containing a cylindrical chamber with a material inlet pipe connected to its cylindrical wall, placed along the axis the chamber is a recirculation device of the ejection type in the form of two conical sections connected by means of a cylindrical adapter, and an axially movable reflector located above the cut of the upper conical section, while the cylindrical adapter is located in the lower conical part of the chamber and is made with slits of adjustable cross-section, the upper conical section is located in the cylindrical part of the chamber and is made in the form of a bell rigidly connected to the reflector for their joint movement, and the material outlet pipe is installed tangentially under the cut of the bell.

The known design has a number of significant disadvantages:
1. It is not possible to ensure the production of a dried material of high quality due to the return of part of it by a swirling flow to a recirculation device, which leads to overheating of large dried particles having a mass equal to the mass of small but wet particles.

 2. Removal of the dried material is carried out after the supply of the drying agent is stopped, which greatly complicates the maintenance procedure of the installation.

 3. It is possible clumping of the dried material due to its recycling and mixing with wet.

 An object of the invention is the intensification of the drying process, preventing clumping of the material, improving the quality of the dried product.

 The essence of the invention lies in the fact that the dryer is a suspended layer with an active hydrodynamic regime, comprising a cylindrical chamber with a tangentially mounted material inlet pipe, a reflector mounted with the possibility of movement in the axial direction, and a confuser for introducing the main flow of the drying agent, while along the camera axis of its cylindrical part, a hollow insert made in the form of a hyperboloid is installed, the upper cut of which is rigidly fixed on the cylindrical surface of the chamber over the tangential tanovlenii input pipe material and between its lower edge and the side surface of the chamber an annular gap, wherein on the outer surface of the hollow insert from the middle to the upper edge disposed channels for exhaust drying agent arranged to regulate their flow cross section.

 In FIG. 1 schematically shows the proposed dryer; in FIG. 2 is a section AA, in FIG. 3 - section BB.

 The dryer consists of a cylinder-conical chamber, to the cylindrical part 1 of which there is connected a material inlet pipe in the form of a gas suspension 2, a chamber for unloading dry material 3, a conical part 4 of the chamber, to the top of which a confuser 5 is coaxially connected to enter the main flow of the drying agent.

 Along the axis of the installation in the cylindrical part 1 there is a hollow insert 6 in the form of a hyperboloid. On the outer surface of the hollow insert 6, channels of adjustable cross section are located 7 for outputting a part of the spent drying agent, shown by lines 17. Above the upper cut of the hollow insert there is a reflector 8, which moves axially with a screw drive 9. A pipe 11 is provided for the chamber cover 10 for withdrawal of the spent drying agent.

 The trajectory of the swirling flow formed by the tangential introduction of the drying agent is shown by line 12, the direction of movement of the material in the conical part 4 of the chamber is shown by lines 13. The path of movement of particles of material through the hollow insert 6 is indicated by lines 14, and in the discharge chamber by lines 15. The boundary between the fountain core and a falling swirling flow of material and coolant is shown by dashed lines 16.

 The dryer operates as follows.

 The source material is fed into the cylindrical part 1 of the chamber in the form of a gas suspension through the pipe 2, where it is dried in a swirling stream. Partially dried material is lowered into the lower conical part 4 of the chamber. The amount of tangentially twisted drying agent entering through the annular gap formed by the cylindrical surface of the chamber and the lower cut of the hollow insert 6 is controlled by changing the passage section of the channels 7. The magnitude of the annular gap depends on the properties of the processed material. In the lower part of the conical part 4 of the chamber, the material is captured by the main stream of the drying agent supplied through the nozzle 5. The drying process continues in the active hydrodynamic mode. In the core of the stream, a layer of material is gushing out, and particles twisted by a tangential flow are lowered around the periphery, while the core of the fountain rotates around a vertical axis. The direction of rotation of the fountain core coincides with the direction of movement of the tangential flow. Drying, particles of material rise up and are captured by the flow of a drying agent, the speed of which increases due to a decrease in cross section due to the configuration of the hollow insert. As the drying agent moves through the hollow insert, its speed drops to the particle whirling speed due to an increase in the cross section due to the configuration of the insert, and a suspended layer is formed in which the material is dried. The reflector 8 deflects the material particles in the radial direction, as a result of which the light dried particles enter the discharge chamber 3, in which the material and the drying agent are separated, and the under-dried particles are returned to the suspended layer. The spent drying agent is removed from the discharge chamber 3 through the nozzle 11. Using the screw drive 9, the distance from the reflector to the upper cut of the hollow insert is adjusted.

Thus, the proposed dryer, suspended layer with an active hydrodynamic regime has the following advantages:
- the implementation of the hollow insert in the form of a hyperboloid and its location in the cylindrical part of the chamber can improve the quality of the dried material by ensuring the necessary duration of the presence of particles of the material in suspension
- the presence of an annular gap between the lower cut of the hollow insert and the side surface of the chamber provides unimpeded movement of material particles into the core of the fountain,
- the location on the outer surface of the hollow insert from the middle to its upper cut of the channels for the withdrawal of part of the drying agent and made with the possibility of regulating the flow area allows to eliminate the entrainment of particles of material from the chamber and to ensure the necessary flow rate of the drying agent.

Claims (1)

 A hydrodynamic active bed dryer containing a cylindrical chamber with a tangentially mounted material inlet, a reflector mounted for axial movement and a confuser for introducing the main flow of the drying agent, characterized in that a hollow insert is installed along the chamber axis in its cylindrical part made in the form of a hyperboloid, the upper slice of which is rigidly fixed on the cylindrical surface of the chamber above the tangentially mounted nozzle of the input terial, and between its lower slice and the side surface of the chamber an annular gap is provided, and on the outer surface of the hollow insert from the middle to the upper slice there are channels for withdrawing the spent drying agent, made with the possibility of regulating their passage section.

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