RU2095707C1 - Device for drying capillary porous materials - Google Patents

Abstract

FIELD: drying biological and medical preparations, agricultural products; chemical, light and other industries. SUBSTANCE: acoustic radiator includes piston with rod, sound source and drying chamber located coaxially with it and made in form of sound channel. Containers provided with loading doors and adjustable unloading doors are arranged in this channel vertically at some distance from one another. Vertical walls of containers are made from metal screen whose mesh is lesser than minimum size of particles of material being dried. Length of sound channel greatly increases its transverse sizes. Sound absorber is mounted in outlet section of channel. EFFECT: enhanced efficiency. 2 dwg

Description

 The invention relates to a technique for drying capillary-porous bulk materials and can be used to dry biomedics, agricultural products, chemical, light and products of other industries.

 For the prototype, a recirculation grain dryer [1] was selected which contains a hopper with a feeder for feeding bulk material into a contact heat and mass exchanger, an intermediate cooling shaft connected to the heat and mass exchanger. Along the height of the intermediate cooling shaft, sound emitters with air flow reflectors are installed in perforated concentrators in the form of a truncated cone, facing a large base to the emitter. The simultaneous use of several sound emitters to intensify the drying of grain passing through a grain dryer leads to negative consequences: low productivity and high energy consumption.

 The objective of the invention is to increase the productivity and economic performance of the device, namely the reduction of energy consumption during operation and capital costs during construction.

 The problem is achieved in that the drying chamber is made in the form of a duct-sound duct. The longitudinal dimension of the sound duct is many times greater than its transverse dimensions. The device comprises a sound emitter, including a piston with a rod and a sound source. A drying chamber is arranged coaxially with the emitter, along which containers with loading gates and with adjustable gates for unloading the drained material are vertically located at a distance from one another. The vertical walls of the containers are made of metal mesh, the step of which is less than the minimum particle size of the material to be drained. A sound absorber is installed in the output section of the sound duct.

 These signs are not identified in other technical solutions when studying the level of this technical field and, therefore, the solution is new and has an inventive step.

 The proposed technical solution is industrially applicable, for example, in agriculture.

 Figure 1 shows a General view of the proposed device; figure 2 section aa in figure 1.

 A device for drying capillary-porous bulk materials contains a sound emitter 1, consisting of a piston with a rod 2 and a sound source 3, located coaxially with the drying chamber 4, made in the form of a sound duct, along which 5 s containers are vertically spaced from one another loading shutters 6 and adjustable discharge shutters 7. The vertical walls of the containers are made of metal mesh, the step of which is less than the minimum particle size of the drained material. A sound absorber is installed in the output section of the sound duct. 8. Wet air is vented from the drying chamber (not shown). The distance between the containers provides the necessary condition for the passage of sound from the emitter to the absorber without significant attenuation of sound. The length of the duct is many times greater than its transverse dimensions.

 The device is also equipped with loading and unloading devices in the form of a loading hopper 9 of the drained material and the conveyor 10 to remove the dried material.

Since the speed of acoustic drying of the material, ceteris paribus, depends on the intensity of sound, to ensure uniform drying of the material throughout the volume of the drying chamber, it is necessary to ensure a uniform distribution of sound intensity in it. This is achieved by creating a plane traveling wave in the drying chamber, which imposes restrictions on the dimensions of the drying chamber, and, ultimately, on its performance. The transverse dimensions of the chamber must satisfy the condition known from acoustics Δ <λ / 2, where λ is the wavelength, D is the largest transverse dimension of the drying chamber. The length of the drying chamber L _to must satisfy the condition
l _to ≲ (5-6) λ.
The experiments showed that the decrease in sound intensity along its length is not more than 5-6 dB for drying wheat with a distance between containers of 3 cm. With an increase in the allowable attenuation of sound and the distance between containers, the length of the drying chamber can be increased further. Due to the large length of the drying chamber and the high coefficient of its filling with the drained material (up to 50 or more), the mass of the material drained simultaneously by one sound source increases sharply, i.e. Increases device performance.

 A device for drying capillary-porous bulk materials works as follows.

 With the bottom 7 shutters closed and the top 6 open, wet material is loaded into containers 5 from hopper 9. Close the upper shutters 6 and turn on the sound source 1. At a fixed frequency of the emitted sound, the position of the piston 2 is selected so that the sound intensity is maximum. Sound passing through the drying chamber from the source 3 to the absorber 8 interacts with the material to be dried and extracts moisture from it. Moisture extracted from the material to be drained is removed from the drying chamber by the exhaust air when using the Hartmann jet generator as a sound source (the ratio of the exhaust air flow to the moisture input from the dried material per unit time ensures this automatically) or a fan when using other types of sound sources. When the time required for a given final moisture value of the material to be dried expires, the sound source is turned off. Open the lower shutters 7, the dried material comes from the containers 5 to the conveyor belt 10 and is fed to the storage. After that, the lower shutters 7 are closed, and the upper 6 open. The next portion of the wet material enters the containers and the process is repeated.

As an example, we evaluate the performance and energy consumption when using the described device designed for drying wheat. The drying chamber is made in the form of a channel 10 m long, its cross section is square with a side of 0.7 m. When operating at a frequency of 150 Hz, the conditions for the formation of a plane wave in it with acceptable attenuation along the length of the chamber will be ensured. We take the width of the containers equal to 5 cm, the distance between them is 3 cm. For one load, approximately 3 tons of wheat are placed in containers. Laboratory experiments have shown that to reduce grain moisture from 20 to 14% (the control value of the initial and final humidity, taken to estimate energy consumption during drying of wheat), 30 minutes of irradiation with its sound at an intensity of the last 165-170 dB is sufficient. Therefore, the productivity of such a plant will be approximately 5 tons per 1 hour. When assessing energy consumption, we will proceed from the specific sound power of 5 W / cm ² to ensure effective drying. Assuming the cross-sectional area of the drying chamber to be 0.7 mx 0.7 m, we obtain the required acoustic power equal to 25 kW.

 Putting the efficiency of the source equal to 20% and the compressor when using the Hartmann generator equal to 50%, we get energy consumption of 50 kWh per 1 ton of grain, which is several times lower than the same indicator for devices of the prior art. The above estimates are characteristic and typical of the proposed design of a device for drying materials.

Claims (1)

 A device for drying capillary-porous bulk materials containing a sound emitter, a drying chamber, a loading and unloading device, characterized in that the sound emitter comprises a piston with a rod, a sound source and a drying chamber arranged coaxially with it, made in the form of a sound duct, along which at a distance from one another, containers with loading gates and adjustable discharge gates of the drained material are vertically located, while the vertical walls of the containers are made of metal a mesh, the step of which is less than the minimum particle size of the material to be drained, and the length of the sound duct channel is many times greater than its transverse dimensions, and a sound absorber is installed in the output section.

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