JPS63232801A - Device for drying liquid material - Google Patents

Abstract

PURPOSE:To produce dry powder with high heat efficiency by the title compact device by pulverizing a liq. material into dry powder in the fluidized bed wherein many fluidization mediums are blown up by hot air in the device for pulverizing the liq. material into dry powder using the fluidization medium. CONSTITUTION:The air cleaned by an air filter 1 is heated by an air heater 2, and introduced into a fluidization vessel 4. The liq. material M from a raw material tank 3 is brought into contact with the air in the vessel 4 through fluidization medium 16, and the liq. material is dried and pulverized into dry powder. The dry powder is sent out into a bag filter 6 through a cyclone 5, and recovered. The fluidization vessel 4 charged the liq. material M is provided with a hot-air chamber 11 and a fluidization chamber 12, a perforated diffusion plate 13 is furnished between both chambers, and a heat exchanger 25 is placed above the plate 13 and embedded in the fluidized bed. With respect to the heating by the heat exchanger 25, the exhaust loss is diminished to zero, only the heat quantity to be effectively used in drying is supplied, and hence the heat efficiency is improved.

Description

[Detailed description of the invention] a. Industrial fields of application The present invention relates to a suspension of particulate matter in water or other solutions (solvents) that are used in various industrial fields (hereinafter referred to as slurry). Alternatively, a substance dissolved in water or other solution (solvent) (hereinafter referred to as a solution, and hereinafter this slurry and this solution will be collectively referred to as a liquid substance) is heated in advance in a fluidized bed using hot air. While adhering to the surface of the fluidized medium particles in a (fluidized) state, at the same time the medium particles are forcibly heated by being brought into direct contact with the heating surface of a heat exchanger installed in the fluidized bed. The present invention relates to a drying device capable of drying and continuously drying this liquid substance to obtain a powder.

b. Prior Art Conventionally, a spray dryer has been used as a drying method to directly obtain dry powder by drying the liquid substance, but this equipment has a very low initial cost and running cost. As a drying method to solve this problem, a fluidized bed drying method using media particles has been developed in recent years. All drying equipment uses organic materials.

This is a fluidization method using media particles of any inorganic material, and the configuration of an apparatus for drying a liquid substance to directly obtain a dry powder is shown.

Literature-1 Literature name: FLUI[1IZAT[ON device description page: 5
Page 88 Figure 12.16 (DRIERWITHFLUE mouth IZ[!D BED OF INBRT GR
ANULARllATERIAL) Editor: J, F, DAV [DSON D, HARRISON Publication year? 1971 (Showa 46) Publisher: AC
AD[! Old CPIIESS-LONDON AN [l
NEW YORKOR-2 Title of document: Japanese Patent Publication No. 54-43747 Title: Grinding fluidized drying method for chemicals C1 Problems to be solved by the invention However, none of the problems of the drying technology shown in the above-mentioned document However, it relies only on hot air to supply the necessary amount of heat for drying.

In general, one of the characteristics of the drying technology using a fluidized bed is that the heat exchange performance between the blown gas and the fluidized particles (N) is excellent, but the solid content in the liquid material When drying a substance (for example, an organic substance such as a synthetic resin), the temperature of the hot air used for drying should be kept at a low level (for example, below 100°C) due to the thermal properties of the substance itself.
Therefore, in many cases, only a relatively small proportion of the amount of heat is effectively utilized for drying.

For example, when drying a vinyl chloride emulsion polymer product, the temperature of the hot air blown into the fluidized bed is limited to a low level of 80°C due to the thermal properties of the vinyl chloride resin. The moisture content of the fluid must be maintained at 0.1% or less, and as an operating condition for this purpose, the air temperature immediately after passing through the fluidized bed must be maintained at 55°C.

Since the weight velocity and specific heat of the air passing through the fluidized bed are almost unchanged, in this case, the amount of heat effectively used for drying can be simply calculated (using a simple calculation method of thermal efficiency): -X100-31. 3%, which is a very low utilization rate. In other words, if there is a limit to the temperature of the hot air that can be used (this is the case in most cases when drying organic matter), it is possible to
Since the amount of heat used to evaporate is small, the supply of heat to dry a certain amount of liquid material must be compensated for by increasing the amount of air (air volume), and the drying container itself , hot air generator, powder collection device.

All ancillary equipment such as blowers and exhaust fans! The size of the space a will increase, which naturally leads to an increase in costs.

For this reason, for example, in the prior art shown in the above-mentioned document 1, just before supplying the liquid substance to the medium particle fluidized bed, this liquid substance is sprayed to form droplets, and this liquid substance is It has been shown that pre-drying is carried out by contacting droplets with hot air (this is the very principle of spray drying), but it is clear that this prior art technique is becoming increasingly thermally inefficient. be.

Furthermore, the apparatus of Document 1 has the disadvantage that there is a risk that the dried powder that has flown out of the fluidized bed of medium particles collides with the sprayed droplet particles and leaks again.

Further, even in the device shown in Document-2, the device shown in Document-2
As in case 1, since the supply of heat required for drying relies only on hot air, the drying speed of the entire fluidized bed of media particles is slow, and therefore the liquid substance attached to the surface of the fluidized media particles In other words, it is necessary to prevent the agglomeration and agglomeration phenomenon of the media particles, and for this reason, a forced mechanical stirring means is used to constantly stir and disintegrate the entire media particles to form a stable fluidized bed. It has been shown that there is a need to form and maintain it. However, installing a forced stirring device in the fluidized bed has disadvantages such as not only is the mechanical stirring device itself a complicated and expensive mechanical element, but also agitation causes abrasion of the inner walls of the device and media particles. There is.

d. Means for Solving the Problems The present invention has been made in view of the above-mentioned circumstances, and does not require the spraying of a liquid substance as in the prior art, and does not require forcible stirring means in the fluidized bed. At the same time, this liquid substance is deposited on the surface of a real number of media particles in a fluidized state in a drying container without any drying process.
The solid substance contained in the liquid substance is continuously dried by rapidly heating and evaporating the solution by bringing it into direct contact with the heat transfer surface of the heat exchange device installed in the fluidized bed. The object of the present invention is to provide a drying device that can obtain the powder as a powder.

That is, the present invention provides a fluidization container equipped with a gas distribution plate, in which a large number of fluidization medium particles are filled on the distribution plate, and hot air is blown up to form a fluidized bed of the medium particles. Drying of a liquid substance, characterized in that a heat exchange device is provided in the fluidized bed, a supply port for the liquid substance is provided that opens on the side surface of the fluidized bed, and the liquid substance is dried while being attached to the fluidizing medium particles. It is a device.

Typical substances that can be dried with the apparatus according to the present invention are #
powder, vinyl chloride, polyethylene, polypropylene resin,
Slurries or solutions of organic substances such as organic chemicals, slurries of inorganic substances such as titanium dioxide, lime, calcium carbonate, and inorganic chemicals, and slurries of fine metal particles such as iron oxide, lead oxide, and zinc oxide, etc. The present invention is not limited to the substances described here, and can be applied to various liquid substances such as contact materials, inorganic materials, and five metals.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 to 4 show an outline of a drying device for liquid substances according to the present invention, in which 1 is an air filter, 2 is an air heater that heats the air purified by the air filter 1, and 3 is a liquid substance to be dried. A raw material tank 4 for storing the material MM is a fluidization container for performing fluidization drying. M is fluidized and dried, and this is passed through a cyclone 5. The dry powder is sent to a back filter and finally recovered.

The fluidization container 4 includes a hot air chamber 11 and a fluidization chamber 12, and a perforated distribution plate 13 is disposed between the compartments. Note that the distribution plate 13 is not necessarily limited to a perforated plate structure as long as it can efficiently disperse the hot air blown up from the hot air chamber 11 below. lla is an inlet for heated air provided in the hot air chamber 11; 12a is a supply port for the liquid 'fM opened on the side wall of the fluidization chamber 12; 16 is a large number of inlets filled in the fluidization chamber 12 on the distribution plate 13; 12b is a supply port for supplying media particles 16 to the fluidization chamber 12; 12c is a discharge port for the media particles 16 that is opened when necessary; 12d is a fluidization chamber 1;
In the space above 2, 12g is a delivery port for the dried and separated fine powder, and 17 is external heating means provided around the outer wall of the fluidization container 4.

This fluidization container 4 further has a heat exchange device 125 disposed directly above the dispersion plate 13 in the fluidization chamber 12 so as to be embedded in a fluidized bed formed by the medium particles 16 filled in the greenhouse.

This heat exchange device 25 is constructed as follows.

That is, in FIGS. 2 to 3, 26 is a heat medium, for example, a hot water inlet pipe, 27 is an inlet pipe, 28 is a branch pipe,
29 is a collection pipe, 30 is a ladder to the outlet, 31 is an exit pipe, and a large number of heat exchange pipes 32 are connected to the branch pipe 28 and the collection pipe 29.
The inlet pipe 2 is erected in parallel with a predetermined interval between the
6, the hot water enters from the branch pipe 28 to a large number of heat exchange pipes 32.
29. Outlet pipe 31 via outlet header 30
It is now sent to.

The heat exchange tubes 32 are configured as a group of a large number of vertical tubes, and are arranged over the entire area of the fluidized bed from directly above the distribution plate 13 to just above the fluidized bed formed by the medium particles 16. Depending on the material and diameter of the medium particles to which the properties of the liquid substance are applied, the arrangement and spacing of the heat exchange tubes 32 may be arranged in other manners, for example, in a staggered horizontal tube group. Further, when the heat medium passed through the heat exchange device 25 is a gas such as water vapor, the inlet and outlet of the hot water may be in an exactly opposite relationship for reasons such as awM water discharge.

Reference numeral 36 denotes a heat medium adjustment tank, in which hot water (or steam) whose temperature is adjusted in the tank is forcibly circulated to the heat exchange device 25 by a circulation pump 37.

Note that 40 is a supply pipe for a heating medium (such as water vapor), and the supply pipe 40 branches to supply the heating medium to the air heater 2 and the adjustment tank 36, respectively. Reference numerals 41 and 42 designate temperature control devices provided in the respective branched supply pipes 40a and 40b, which control the opening and closing of valves provided in each supply pipe in response to detected temperatures.

Reference numeral 45 denotes a quantitative supply pump, which is installed in a supply pipe provided between the raw material tank 3 and the fluidization chamber 12 of the fluidization container 4, and is connected to the liquid material WM in the raw material tank 3.
is delivered to the fluidization chamber 12.

In addition, 5a is a rotary pulp provided at the bottom of the cyclone 5, 6a is a rotary valve provided at the bottom of the back filter, 46 is an exhaust fan, 47 is a supply pipe connected to a compressed air source, and 48 is a timer side m device. Each is shown below.

The shape and material of the medium particles 16 are selected depending on the properties of the liquid substance to be dried, operating temperature, abrasion resistance, packed weight, etc.; Most preferred are fin grains, and ellipsoids and squares with the same size range.

Particles of rectangular, cylindrical, irregularly shaped bodies, and other shapes suitable for the treatment of the present invention, as well as mixtures of particles of each of the above shapes, may be used.As for the material, inorganic materials such as various ceramics, Rubber, Teflon.

Particles made of organic materials such as nylon, metals such as stainless steel and carbon steel, and other materials suitable for the treatment of the present invention, as well as particles made of mixtures of the above-mentioned materials, may be used.

e. Function The liquid substance drying apparatus according to the present invention is constructed as described above, and is operated in the following manner.

First, a predetermined amount of media particles 16 are stored in advance in the fluidization chamber 12 from the supply port 12b of the fluidization container 4, that is, so that the height of the top surface of the fluidized bed is higher than the top of the heat exchange tube group 32. Next, from filter 1 to air heater 2
The heated air is sent to the hot air chamber 11 through the inlet 11a, and the hot air is blown up from the lower part of the dispersion plate 13 to transform the medium particles 16 in the fluidization chamber 12 into a fluidized state, that is, a fluidized bed of the medium particles 16. Heat while forming. At the same time, the heat exchange device 25 is activated.

That is, a heating medium is supplied through the supply pipe 40b, and the hot water in the hot water adjustment tank 36, which has been adjusted to a predetermined temperature, is transferred from the inlet pipe 26 of the heat exchange device 25 to the branch pipe 28. Heat exchange tube 32.
The hot water is sent to the outlet pipe 31 via the collection pipe 29, and the hot water is circulated to directly heat the fluidized bed.

When the temperature of the medium particles 16 reaches a predetermined level and stabilizes as described above, the liquid substance M to be dried in the raw material tank 3 is forced at a constant rate by operating the metering pump 45. Send it out. The liquid substance M is in the fluidization container 4
is forcibly pushed out into the fluidization chamber 12 from the supply 012a opening on the side wall of the fluidization chamber 12, where it is successively deposited on the surface of each of the true number of media particles 16 in a state of fluidization while maintaining an active boiling motion. It adheres and is continuously distributed and dispersed on the surface of the media particles 16. The solution and solid content (generally containing many fine particles) constituting the liquid substance M are exposed to both the hot air blowing up from the hot air chamber 11 below on the surface of the medium particle 16 and the heat transfer surface of the heat exchange tube 32 of the heat exchange device 25. This heating means allows for faster and more efficient heating and drying.

In addition, at this time, the temperature of the heat medium such as hot water passed through the inside of the heat exchange device 25 is set to several degrees to several tens of degrees (') below the temperature of the hot air.
e) By increasing media particle 16 as well as media particle 1
The liquid substance attached to the surface of 6 can be heated more quickly and more efficiently.

The water and other solutions in the liquid substance M subjected to the drying action on the surface of each medium particle 16 are rapidly evaporated by the heating action, and the dried solid content is absorbed by the medium particles 16 and the medium in the fluidized bed. The particles 16 are detached from the surface of the medium particles 16 due to a peeling action due to collision and friction between the heat exchange tubes 32 (group) and the inner wall of the fluidization chamber 12, and are sequentially transferred from the fluidized bed to the upper space in the state of dry powder particles. Continuously pops out on 12d. Then, the powder particles flying out of the fluidized bed pass through the fluidized bed and are carried by the rising air to the upper delivery port 1.
Cyclone 5 from 2e. sent to back filter 6,
There, it is separated, collected, and recovered as a dry powder.

The medium particles 16 forming the fluidized bed peel off and release the adhering dry powder as described above, and due to the intralayer convection phenomenon of the fluidized bed special development, the supply port 12a in the fluidized bed is produced as a so-called stochastic result. The extruded liquid substance M adheres to the surface of the medium particles 16 one after another, and the same operation is repeated thereafter.

The solid content in the liquid substance to be dried separates from the surface of the media particles as a uniform fine powder due to the above-mentioned action, but there is a large difference in particle size between the dry powder and the media particles ( In general, the average particle size of the dry powder is 10 to 100 times larger, so
In other words, since there is a large difference in the terminal velocity between the two, the dry powder is easily carried out of the fluidization chamber 12 along with the air that has passed through the fluidized bed, but the fluidization medium particles 16 themselves are There is no possibility of it jumping out of the chamber 12.

f. Effects of the Invention As detailed above, the liquid substance drying apparatus according to the present invention provides the following effects that are not available in conventional apparatuses.

Namely, ■ Heat exchange device! 25 for direct heating of the media particles 16 and the liquid substance adhering to the surface of the media particles, the heat exchange tube 321 branch tube 2B of the device.

Since only the amount of heat given to the fluidized bed from each heat transfer surface of the collecting pipe 29 is consumed (that is, the exhaust loss is zero), only the amount of heat effectively used for drying needs to be replenished, resulting in high thermal efficiency. This is a drying operation.

■ Therefore, of the total heat required for drying, only the proportion of heat directly heated by the internal heat exchange device is used (usually equivalent to 20% to 60% of the total heat required for drying). Since the amount of air (hot air M) can be reduced, the equipment can be downsized not only for the fluidization container itself, but also for all ancillary equipment such as hot air generators, cyclones, powder collection devices such as bank filters, and blowers/air blowers. can do. Therefore, initial costs and running costs can be reduced.

■ In addition, the heat transfer surfaces of the heat exchanger, as well as the main parts inside the fluidization vessel, are constantly rubbed by the fluidization medium particles, which prevents the adhesion of treated substances (furthermore, this self-cleaning property improves the inner surface of the fluidization vessel). This improves the heat receiving performance from the heat exchange device.On the other hand, the surface of the media particles is constantly exposed to the processing material (powder).
Since the medium particles themselves, the heat exchange tubes, and the inner walls of the fluidization vessel are covered with water, wear of the media particles itself, the heat exchange tubes, and the inner walls of the fluidization vessel hardly poses a problem.

As described above, the apparatus of the present invention can be widely and efficiently used for drying various liquid substances such as organic substances, inorganic substances, and metals that are handled in various industrial fields.

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention, FIG. 1 is a conceptual diagram showing the entire liquid substance drying device according to the present embodiment, and FIG. 2 shows the configuration of the heat exchange device. A conceptual diagram, FIG. 3 shows a view taken along the line A-A in FIG. 2, and FIG. 4 shows a view taken along the line B-B in FIG. 2. 4...Fluidization container, 11...Hot air chamber, 1
1a... Heated air inlet, 12... Fluidization chamber,
12a... Liquid substance supply port, 13... Dispersion plate,
16... Medium particles, 25... Heat exchange device, 32... Heat exchange tube. Figure 2 "8 Figure 4B Figure 3

Claims (1)

[Claims] 1) In a fluidization container equipped with a gas distribution plate, a large number of fluidization medium particles are filled on the distribution plate and are blown up with hot air to form a fluidized bed of the medium particles. In addition, a heat exchange device is provided in the fluidized bed, and a liquid material supply port opening on the side surface of the fluidized bed is provided, and the liquid material is dried while adhering to the fluidizing medium particles. Equipment for drying substances. 2) The liquid substance according to claim 1, wherein the heat exchange device disposed within the fluidized bed is comprised of a large number of heat exchange tubes arranged with gaps throughout the fluidized bed. drying equipment.