SU1537991A1 - Method of drying granulated materials - Google Patents

Abstract

The invention relates to the technique of drying granulated materials in a fluidized bed and allows to intensify the drying process due to the fact that the fluidized bed is simultaneously affected by opposing vertical acoustic flows and an additional acoustic flow in the horizontal plane, which makes it possible to evenly distribute the intensity of acoustic fields the time of the drying process at the height of the fluidized bed and 3-4 times reduce the time of drying. An apparatus for carrying out the method comprises a fluidized bed chamber connected to fan 2 with air ducts, which are made in the form of acoustic waveguides tuned to the fan blade frequency taking into account the Doppler effect (waveguides 8 and 15), and to the vortex sound frequency of the fan 2 (waveguide 5), which allows this method to be implemented without additional energy consumption for the creation of acoustic fields. 1 il.

Description

The invention relates to a technique for drying bulk materials, relates to a method for drying granulated materials in fluidized bed apparatus using acoustic energy and can be used in the chemical and other industries.

The purpose of the invention is to intensify the drying process.

The drawing shows an installation for implementing the method of drying granular materials.

The installation includes a boiling bed drying chamber 1, a fan 2, a discharge channel 3 with a damper k, an acoustic waveguide 5 with a damper 6, a heat exchanger 7 connected to the outlet nozzle of the fan 2 by means of a channel made in the form of an acoustic waveguide 8, starting from language 9 of a fan equipped with a valve 10. A drying chamber 1 is adjacent to a bunker 11 connected to it via a loading channel (not shown), blocked by a valve 12. A return channel 13 is connected to the bunker 11 with a valve 1. Outlet of the drying chamber 1 with A recirculation channel made in the form of an acoustic waveguide 15 with a flap 16 is connected with an inlet pipe of the fan 2. A gas distribution grid 17 is placed in the drying chamber 1 above the heat exchanger 7, and the loading channel 18 with the damper 19 is attached to the cover of the drying chamber 1 the fan 2 is connected to an air intake with a filler 20. In the chamber 1, a temperature sensor 21 is connected to the steam flow controller 22 (choke) in the heat exchanger 7

The characteristic dimensions of acoustic waveguides 8 and 15 correspond to the inequalities:

WITH

L 2 ™ n (7-v7c);

(one)

L, Ј

 2 Z, n- (HV / C)

(2)

those. calculated for the frequency Z "n generated by the operating fan 2 due to the interaction of unsteady flow from the interscapular space with the tongue 9 of the fan 2 corrected for the Doppler effect, which allows for making the waveguides 8 and 15 hard to flow almost no loss. The characteristic size of the waveguide 5 corresponds to the condition

С & / 2 -К. -ft- D-n,

(3)

5 1-1 0

five

five

calculated for the vortex frequency of the fan 2, generated by it due to the vortex formation at the gathering of the flow from the impeller blade with the thickness S.

The implementation of channels in the form of waveguides in accordance with the above dependences makes it possible to efficiently transfer acoustic energy from the fan 2 to the fluidized bed in the drying chamber 1. For example, in a dryer with a fan 2 operating at a frequency of 1700 rpm and having 12 blades 2 mm thick on an impeller with a diameter of 900 mm, the sound pressure level reaches 101 dB at a frequency of Zin 340 Hz at a cross section of the language 9, and 98 dB at a vortex frequency of x-ft-D -p / / 8090 Hz. The acoustic flow propagating through the waveguide 8, the characteristic size of which for these conditions is La 300 mm, almost without (weakening (since the walls of the waveguide are rigid) reaches the drying chamber 1, the lower part of which is designed as a rotary acoustic horn and acts on a bale bottom layer. The characteristic size of the waveguide 1 i for these conditions L, 400 mm ensures the effective transfer of acoustic energy from fan 2 to the fluidized bed in chamber 1 from top to bottom. Acoustic waveguide 5 is made oskim and resonantly tuned to the impeller vortex frequency of the sound of the fan 2 for these conditions (L3 20 mm), which provides a layer of acoustical

There is a mass transfer of moisture from the pores of the material to the heating gas across the entire thickness of the fluidized bed. The gas then flows through the gas outlet to the waveguide 15, where it is mixed with the cold gas flowing through the valve 20 from the environment. Next, the gas flow passes through the flow valve 97 dB at a frequency of 8090 Hz into month 2 torus, and the mass flow of moisture from the pores of the material to the heating gas throughout the entire thickness of the fluidized bed is ejected. The gas then flows through the gas outlet to the waveguide 15, where it mixes with the cold gas flowing through the valve 20 from the environment. Next, the gas flow passes through the valve

Those entering the horizontal acoustic flow into the fluidized bed.

The method of drying granular materials is as follows.

The unit operates in the following cycles: pneumatic material loading; acoustic drying of the material; pneumatic material unloading.

When the first cycle is performed, the shutters 4, 16 and 19 are opened, and the shutters 6,10,20 and And close, the shutter 12 is closed during loading and drying. Fan 2 creates a vacuum in the loading channel 18 ,. and the source material is sucked into the drying chamber 1.

When the material is dried (second cycle), the shutters 6 and 19 are closed, the shutters 10 and 16 are fully open, and the shutters and 20 are slightly opened to ensure renewal of the drying agent. The gas injected by the dentor 2 enters the heat exchanger 7, is heated and passes through the gas distribution grid G / and the drying chamber 1, where a layer of wet granulated material, such as polystyrene, liquefies. At the same time, opposite acoustic flows with a frequency (1 + V / C) affecting the fluidized bed from above and below propagate through the acoustic waveguides 8 and 15. An additional acoustic stream propagates along the waveguide 5 and acts on the fluidized bed in a plane perpendicular to the opposing acoustic streams. As a result, acoustic fields of sufficiently high power (up to 1 µW / cm2) and intensification of channel 3 and cleaning devices (not shown) to the atmosphere are uniformly distributed in the fluidized bed, and the rest of the stream enters the heat exchanger 7,

When the temperature in the fluidized bed of the drying chamber I, fixed by the temperature sensor 21, changes, the command is given to an adjustable choke 22, which changes the flow rate of the coolant so as to maintain the temperature of the drying agent in the chamber 1 at a predetermined level.

When the moisture content of the material decreases to a predetermined value, the third cycle is turned on - pneumatic unloading of the material, for which the shutters 10, 16 and 20 are closed, and the shutters 6,14 and 12 are opened and the dried granules of the material are blown out of the drying

chambers 1 into the hopper 11 by the flow of gas from the waveguide 5. Then the cycles are repeated.

The proposed method allows the in-h to tensify the drying process without adding additional energy to the creation of acoustic fields.

Claims (1)

Invention Formula The method of drying granulated materials in a fluidized bed by simultaneously exposing the material to coolant and acoustic energy flows, characterized in that, in order to intensify the drying process, the material is applied in vertically directed acoustic energy flows with an additional supply of acoustic energy in the direction perpendicular to oncoming flows.