JPH0125601Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spray dryer suitable for heat-sensitive materials.

(Prior Art and Purpose and Structure of the Present Invention) Liquid fine particles of a substance to be dried that are sprayed by a spray dryer generally have a minimum particle size of a fraction of the average particle size and a maximum particle size of about three times. By the way, in a spray dryer, liquid particles (droplets) with an average particle size are usually dried to a predetermined moisture content to form a powder, and at the same time, the droplets with a maximum particle size are dried to the extent that they do not stick to the drying chamber. It is designed to

Therefore, as a result, particles smaller than the average particle size are overdried, which often increases the temperature of the dried product and causes deterioration in quality.

In order to eliminate such defects, conventional methods have been used to reduce the average particle size by lowering the inlet gas temperature, using a large amount of gas, and increasing the residence time of the particles in the drying chamber by increasing the size of the drying chamber. The following steps were taken to prevent overdrying of the particles.

However, in such a method, first, the drying chamber must be enlarged.

Second, even if the residence time of the droplets in the drying chamber was increased, the residence time of particles with a small diameter equal to or less than the average particle size was long, so overdrying could not be avoided.

The present invention aims to solve these problems of conventional spray dryers.

(Explanation of Examples) Examples of the present invention will be described below.

Description of parts in the drawings 1: A drying chamber of a spray dryer consisting of a body part 1a and a cone part 1b.

2: Main exhaust duct 3: A sub-exhaust duct that penetrates the center of the cone part 1b and introduces small-diameter particles that reach the sub-cyclone 5. The protruding part 3a at the upper end of the main body 3b is 1/2 of the body part 1a. The protruding height shall be below.

Further, the protruding portion 3a protruding into the drying chamber 1 is a double pipe. Inside this double pipe, a blower b and a filter f are installed, via a fixed annular pipe 8,
Air is supplied for an air sweeper 7 that cools the protrusion 3a and blows off powder adhering to the wall surface.

The protrusion 3a is connected to the sub-exhaust duct main body 3 via a rotary joint 10, etc., and rotates together with the air sweeper 7.

The protruding portion 3a is integrally connected to the air sweeper 7 by a connecting conduit 9. Air is supplied to the air sweeper 7 from within the double pipe of the protrusion 3a via the connecting conduit 9.

4: Main cyclone that collects the large diameter dry liquid product introduced into the main exhaust duct 2. The main cyclone 4 is exhausted by a main exhaust fan.

5: A sub-cyclone that collects small-diameter dried products introduced into the sub-exhaust duct 3, and is exhausted by a sub-exhaust fan.

6: A spray device, a rotary atomizer or a nozzle type atomizer is used.

7: As described above, it is integrally connected to the protrusion 3a,
It is a rotatable air sweeper.

8: Fixed annular pipe that supplies air to the protrusion 3a as described above; 9: As described above, a connecting conduit that integrally connects the air sweeper 7 and the protrusion 3a; 10: As described above, a rotary joint; b: Blower; f: Filter (Description of function) The function of the present invention will be explained below.

Among the liquid particles sprayed from the spray device 6, those with a large diameter have a large inertial force and tend to fly far, while those with a small diameter fall to the center.

Therefore, in the spray dryer of the present invention, large-diameter dry particles are introduced into the main exhaust duct 2, while small-diameter dry particles are sucked into the protrusion 3a of the sub-exhaust duct 3.

The inhaled small-diameter particles are led to the sub-cyclone 5 and recovered as a product. In order to prevent over-drying of small-diameter particles, in the embodiment, the protrusion 3a is formed into a double pipe, and air is introduced into the double pipe to cool the introduced gas containing small-diameter particles. However, even if you do not necessarily use double pipes for cooling, if you use a secondary exhaust fan to quickly suck the air, overdrying will not occur.

Further, it is desirable that the ratio between the main exhaust amount and the auxiliary exhaust amount be from 1:1 to 4:1. Further, the protruding portion 3a of the sub-exhaust duct 3 is closer to the body portion 1b than the cone portion 1b.
It stands out. In addition, the protrusion height h is the body part 1
It is desirable that the height is 1/2 or less of the height of a. If the protruding height of the protruding portion 3a is too high, even insufficiently dried particles will be sucked into the sub-exhaust duct 3, which is not in accordance with the purpose of the present invention.

In the drawing, the air sweeper 7 is configured to rotate together with the double-pipe protrusion 3a. That is, the protrusion 3a and the air sweeper 7
is integrally connected with the connecting conduit 9, and the protruding portion 3a
can be rotated by a motor M via a rotary joint 10 on the sub-exhaust duct main body 3. Air from the air sweeper 7 is introduced into the double pipe of the protrusion 3a through the blower b, filter f, and fixed annular pipe 8.
Furthermore, it is guided to the air sweeper 7 via a connecting conduit 9. The air sweeper 7 rotates and blows out air to blow away particles attached to the inner circumferential wall of the drying chamber 1.

(Effects of the present invention) Particles of small diameter are introduced into the sub-exhaust duct 3 and separated, and dried products of large diameter and small diameter are produced separately.
Therefore, unlike the conventional method, there is no rise in product temperature due to overdrying of small-diameter particles, and a high-quality product without deterioration in quality can be obtained.

[Brief explanation of the drawing]

The drawing is a sectional view of the dryer of the present invention. 1...Drying room, 1a...Body part, 1b...Cone part, 2
...Main exhaust duct, 3...Sub-exhaust duct, 3a...Protrusion, 3b...Main body, 4...Main cyclone, 5...Sub-cyclone, 6...Spray plate, 7...Air sweeper, 8
...Fixed annular pipe, 9...Connecting conduit, b...Blower, f
...Filter, 10...Rotary joint.

Claims (1)

[Claims for Utility Model Registration] Drying chamber 1 consisting of body portion 1a and cone portion 1b
A spray device 6 is provided on the upper center surface, and a drying chamber 1 is provided.
A spray dryer equipped with a main exhaust duct 2 at the lower part of the cone part 1b, characterized in that a sub-exhaust duct 3 is provided in the center of the drying chamber 1 with a protruding part 3a extending up to the body part 1a. spray dryer. The spray dryer according to claim 1, wherein the height of the protruding portion 3a is not more than 1/2 of the height of the body portion 1a. The spray dryer according to claim 1, in which the displacement of the auxiliary exhaust duct 3 is from 25 to 100 when the displacement of the main exhaust duct 2 is 100. The spray dryer according to claim 1, which is a registered utility model, wherein the protruding portion 3a is a double pipe, and cooling air is introduced into the double pipe. The protruding part 3a and the air sweeper 7 are integrally connected by a connecting conduit 9, and the air in the double pipe of the protruding part 3a is introduced into the air sweeper 7, and the protruding part 3a is rotated with respect to the sub-exhaust duct main body 3b. The spray dryer according to claim 1 of the utility model registration claim.