JPH02192583A - Drying of fine particle and drying device for fine particle - Google Patents

Abstract

PURPOSE:To disperse aggregated fine particles easily and permit the drying of the fine particles having the grain size of 30mum or less by a method wherein wet fine particles are supplied into a fluidized bed, in which rough particles are fluidized by heated gas. CONSTITUTION:The temperature of the main body 9 of a drier is kept by temperature keeping material 16 and the main body 9 is heated by a heater 18. Medium particles 15, charged into the main body 9 of the drier, are fluidized by gas supplied from a compressor 1. The gas passes through a stop valve 2 and an oil filter 3 and moisture in the gas is removed in a drying agent filled column 4 while the flow rate of the gas is regulated by a pressure regulating valve 5, an orifice meter 6 and a valve 7 and the gas is supplied while heating it to a proper temperature by a preheater 8. On the other hand, fine particles, held in a hopper 14 to dry them, is supplied to the lower part of a fluidized bed by a particles supplying pipe 17 while regulating the supplying speed thereof by a particle supplier 13. Wet particles, dispersed in a medium particle fluidized bed, are dried further while ascending through a fluidized bed drier together with fluidized gas and are collected in a cyclone 10 and a bug filter 11 while the particles are taken out of a particle collector 12.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a fluidized bed drying method in which hot air is sent from below to the surface of a solid material on a gas distribution plate such as a perforated plate to form a fluidized bed and dry it thoroughly. And [conventional technologies] The conventional liquid layer of drying device, which is related to the liquid layer drying device, supplies only particles that try to dry in the dryer body, and forms a hot air in this particles to form a fluid layer. It was something to do.

[Problem to be solved by the invention]

For this reason, fine powder with a particle size of 30μ or less has strong interparticle adhesion and is extremely prone to agglomeration, making it difficult to stably fluidize or form secondary particles and tertiary particles to be fluidized. There was a risk that drying would be insufficient. Especially when the particles are wet, the water content in the particles significantly affects the cohesiveness of the particles, and it is considered impossible to uniformly dry such fine particles using a normal fluidized bed. I was there.

[Means to solve problem S]

In the present invention, relatively coarse heat-resistant particles, for example, 300 μm silica particles, are filled with an appropriate layer height f, and this layer of particles (hereinafter referred to as media particles) is heated to an appropriate temperature, and the media particles are The gas is fluidized at a gas flow rate that is not discharged to the outside of the layer, and moist fine particles are supplied into the fluid and mixed with the medium particles to be fluidized, and the self in the fine particles is evaporated.

Heating of the fluidized bed is done by providing a heating device on the inner wall of the fluidized bed device, in the middle stage for heating and supplying the gas for fluidization,
There is a means for heating the fluidized bed apparatus by providing an inner tube through which a boosting medium such as steam is passed.

As the medium, heat-resistant inorganic JJ1 particles such as alumina, mullite, silica, zircon sand, etc. are preferable. The particle size of the media particles is selected so that their terminal velocity is somewhat larger than the terminal velocity of the fine particles to be dried. Otherwise, media particles will fly out of the fluidized bed and mix with the dry particulates. Usually, the density of most particles falls in the range of 0.8 to &Og/an',
Particle size affects terminal velocity. Therefore, 30μ
In order to dry the following fine particles, the average particle size is 100 to 6.
00μ is better. Such particles are 5~
Fluidize at a gas flow rate of about 150 Cffl/sec.

The filling amount of the media particles is preferably from the height of the static layer to 2 m.

[Effect]

Wet fine particles often aggregate to form secondary particles and tertiary rice grains, but while they are mixed with media particles and flow, they are dispersed into primary particles. When fine particles are dispersed, their specific surface area increases, so the rate of transfer of heat and substances between the particles and the fluid increases, which increases the drying rate. The dried fine particles rise inside the device along with the gas and are collected by a cyclone or bag filter. The drying rate of the fine particles can be changed by changing the temperature of the fluidized bed and the flow rate of the gas, and the residence time of the fine particles in the dryer 1'5 can also be changed by changing the static interlayer spacing of the media particles and the recitation of freeboard. can be changed significantly.

Therefore, the water content of the feed particles can be changed arbitrarily.

〔Example〕

First, the device will be explained.

FIG. 1 is a configuration diagram for explaining the apparatus of the present invention.

The dryer main body 9 is kept warm by the heat insulating material 16 and the heater 18
It is heated by This dryer body 9
The medium ladle 15 filled inside is fluidized with the gas supplied from the compressor 1.

This gas passes through a stop valve 2, an oil filter 3, removes moisture in a desiccant packed tower 4, and adjusts the flow rate with a pressure regulating valve 5, an orifice meter 6, a pulp 7, and a preheater 8.
It is heated to an appropriate temperature and then supplied. On the other hand, Hotsuba 14
Trying to dry held inside 9! The particles are supplied to the lower part of the fluidized bed through a particle supply pipe 17 with the supply rate fully adjusted by a particle supply device 13. The wet particles dispersed in the medium particle fluidized bed are further dried while rising in the fluidized bed dryer together with the fluidizing gas, the cyclone 10, and the bag filter 11.
The particles are collected in the particle collector 12 and finally taken out from the particle collector 12.

Example 1 Silica powder with a particle size of 150A-250μ was used with an inner diameter of cL08
A tube with a height of 2 m was filled with 0.6 m of light and fluidized with air at 60° C. and 1 atm at a standard gas velocity of 0.5 m/sec. The height of the fluidized bed was 0.65 to 0.8 m. In this fluidized bed, the average particle size is 3μ, the water content is o, s (kgwater/kg
10 (g/g/dry 5 solid) powder
minutes). The average moisture content of the particles collected in the cyclone and bag filter is (108 (kg w
ater/kg dry solid). The equilibrium moisture content of this ladle is 0.05 (kg wt
er/kg dry 5olid).

Implementation M 2 River sand particles with a particle size of 250 to 350 μ were made into a 0.5 m light mound with an inner diameter of 0.08 m and a height of 2 m, and the cylinder was heated at 70°C and 1 atm with air at a standard gas velocity of Q and 6 m/sec. did. The height of the fluidized bed was 0.45-0.6 m. In this fluidized bed, the average particle size was 10μ, and the water content was [1! l (kgwater/k
Fly ash fine particles of 25 g dry solid id) were fed at a rate of 25 g/min. The average moisture content of particles collected in the cyclone and bag filter is 0.0
5 (kg water/kg dry 5 solid). The equilibrium moisture content of these particles is 0.03 (kg
water/kg dry 5 solid).

〔Effect of the invention〕

As described above, according to the present invention, since moist fine particles are supplied into coarse particles kept in a fluidized state, aggregated fine particles can be easily dispersed.
20μ microparticles can be dried in a fluidized bed.

[Brief explanation of the drawing]

FIG. 1 is a composition diagram showing an example of the present invention. Explanation of symbols 9 Dryer main body 15 Media particle flow @) fi13
Grooved particle feeder 14 Hopper 13...-Wet rice q6 (X and old yarn 2 puller 14--Hopper 15...-Medium particle fluidized bed

Claims (1)

[Claims] 1. A method for drying fine particles, which comprises feeding wet fine particles into a fluidized bed in which coarse particles are fluidized with heated gas. 2. Heat-resistant coarse particles are placed on a dispersion plate, and heated gas is supplied from below to keep the coarse particles in a fluidized state.The main body of the fluidized bed dryer keeps the coarse particles in a fluidized state, and moist fine particles are supplied to the bottom of the coarse particle fluidized bed. A particulate drying device consisting of a particulate feeder. 3. A fluidized bed dryer body that places heat-resistant coarse particles on a dispersion plate and keeps the coarse particles in a fluidized state by supplying gas from below, a device that heats the dryer body, and a lower part of the coarse particle fluidized bed. A particulate drying device consisting of a particulate feeder that supplies wet particulates to a particulate matter.