JPS62227402A - Method for operating centrifugal thin film dryer - Google Patents

Abstract

PURPOSE:To quench a heat transfer surface to contract it and to remove a solid material stuck thereon by controlling the return flow rate of heated vapor heating the heat transfer face by means of the temp. thereof. CONSTITUTION:A thin film of raw liquid is allowed to flow down along the inner face of a cylinder 8 for evaporation and a heating jacket 13 is provided to the outside of this cylinder 8. When evaporation of the liquid progresses, an evaporated residue is stuck on the inner face of the cylinder 8 and the temp. of a heat transfer surface rises and therefore in such a case that it is detected by a temp. detector 17 and exceeds the preset temp., the aperture of a vapor control valve 16 is adjusted via a controller 18 and thereby the title dryer is constituted so that the temp. of the heat transfer surface can be quenched by increasing the amount of return vapor. The heat transfer surface is contracted by this quenching and the evaporated resue stuck thereon is separated therefrom and deterioration in heat transfer performance can be prevented by such action.

Description

Detailed Description of the Invention (8 Chapters of glAB) (Industrial Application Field) The present invention relates to a method of operating a centrifugal thin film dryer that enables continuous operation over a long period of time.

(Prior art) In conventional centrifugal thin film dryers that use steam, in order to effectively utilize steam heat, a method is adopted in which a used steam return pipe trap is installed and the steam is discharged as is. There is.

Therefore, the steam will flow vigorously only when the trap is opened.Other than installing this trap, the centrifugal thin film dryer can be controlled by keeping the supply amount constant, or by controlling the process to obtain a constant concentration of evaporated residue. The extent of this is to control the amount of liquid supplied.

In such conventional centrifugal thin film dryers, if the processing liquid adheres to the heat transfer surface or rotor inside the machine and gradually grows as a solid, or if this happens during processing, In the case of materials that change in properties, there is a problem in that it is not possible to remove the deposits by scraping the heat transfer surface using centrifugal force and rotary blades at a predetermined rotation speed.

Therefore, deposits on the heat transfer surface and the rotor blade may reduce heat transfer performance, or heat may be generated due to friction between the deposits and the rotor blade. Especially in the case of the scraped υ type,
In order to form a minute gap between the heat transfer surface and the rotor blade,
The occurrence of deposits was inevitable.0 One possible way to remove the deposits is to increase the rotational speed of the rotor. If the rotational speed is increased, the centrifugal force of the rotor blades and the scraping force will be increased, and as a result, the effect of removing deposits will be increased. However, if the number of deer to be scraped increases too much, the treatment liquid will be concentrated on the rotor blades, causing the rotor blades to become unbalanced, and an excessive load will be applied to the rotor blades.

In view of these points in the past, after operating for a certain period of time, operation is stopped to clean and remove deposits, which makes continuous operation for a long period of time impossible, resulting in a decrease in operating efficiency. was.

(Problems to be Solved by the Invention) In this way, in the past, removal of deposits often forced a reduction in the operating rate.The present invention was made based on these points, and its purpose is to An object of the present invention is to provide a method of operating a centrifugal thin film dryer that enables continuous operation over a long period of time.

[Structure of the invention]

(Means for solving the problem) That is, the method of operating a centrifugal thin film dryer according to the present invention is as follows:
The return flow rate of the heated steam that heats the heat transfer surface to the evaporation temperature is controlled by the temperature of the heat transfer surface.

(Function) By controlling the return steam flow rate according to the temperature of the heat transfer surface, for example, if the heat transfer surface becomes high temperature, the return steam flow rate is increased to rapidly cool the heat transfer surface, thereby cooling the heat transfer surface. Try to shrink and remove attached solids.

(Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a diagram schematically showing an apparatus for carrying out the operating method according to the present embodiment, and reference numeral 1 in the figure is a storage tank for storing a processing liquid 2. As shown in FIG. The processing liquid 2 in the storage tank 1 is pumped by a processing liquid pressure pump 3 to a centrifugal thin film dryer 5 via a processing liquid piping 4. A processing liquid control valve 6 is inserted into the processing liquid piping 4 .

The centrifugal thin film dryer 5 is constructed as shown in FIG. Reference numeral 2 7 in the figure indicates a cylindrical body having a double wall structure, and a rotating shaft 8 is disposed within this cylindrical body 7 . A distribution ring 9 is attached to the upper part of the rotating shaft 80 in the drawing. The processing liquid 2 supplied through the processing liquid piping 4 and the liquid supply nozzle 10 flows down uniformly through the distribution ring 9. A plurality of rotary blades 11 are attached to the queen rotating shaft 8 at a predetermined pitch in the axial direction. I'm getting beaten up. Further, the double wall space of the cylinder 7 serves as a heating jacket 12, into which heated steam is supplied via a steam port 13 shown in FIG. This supplied steam flows out through the steam return pipe 1a. A trap J5 is inserted into this steam return pipe 24, and a steam control valve groove is installed in parallel with this trap 15FC.A temperature detector 17 is installed in the cylinder body 7. , the detection signal 817 is input to the control device 18. The control device 18 controls the steam control valve 16 based on the detection signal 817.
In the figure, reference numeral 19 is a paper outlet, and reference numeral 20 is a discharge port. Further, reference numeral 21 in FIG. 2 indicates a heat transfer surface.

The operation will be explained based on the above configuration. The processing liquid 2 is stored in a storage tank 1 and is supplied to a centrifugal thin film dryer 5 by a processing liquid pressure pump 3 via a processing liquid control valve 6 . The supplied processing liquid 2 is introduced into the cylinder 7 through the liquid supply nozzle 10 and is uniformly distributed by the distribution ring 9. and rotor blade 1
The processing liquid 2 flows down in a thin film form along the heat transfer surface 2 due to the centrifugal force of the heating jacket 12. On the other hand, heated steam is supplied into the heating jacket 12, so that the processing liquid 2 is heated. The steam generated by the heating is discharged through the paper outlet 19.

On the other hand, the evaporation residue of the processing liquid adhering to the heat transfer surface 21 is
! It is removed by the scraping action of L11, and is discharged through the discharge port 20 in the form of slurry or powder.

In this action, the evaporation residue adhering to the heat transfer surface 21 gradually increases in thickness, and as a result, the temperature of the heat transfer surface 2 increases due to a decrease in heat transfer performance and heat from wear. In this embodiment, the temperature of the heat transfer surface 21 is constantly monitored by the temperature detector 17, and if the temperature exceeds a preset evaporation temperature, the opening degree of the steam control valve 16 is controlled via the control device 18. It's being adjusted. This is specifically shown in FIG. First, heat transfer surface 2
When the temperature at t is t, the opening degree of the control valve 16 is 0. And the temperature is 1. When the temperature rises to this level, the control valve 16 is opened to the opening degree A. When the temperature further rises to t, the control valve 16 is opened to the opening degree B'. This operation increases the return steam flow rate and rapidly cools the heat transfer surface 2 to the heated steam temperature.

As a result, the heat transfer surface 21 contracts, and the attached solid matter is broken and peeled off, and is removed by the scraping action of the rotor blade 11. Due to such an action, the solid matter is not concentrated in a part of the rotation 1izl, and it is possible to effectively prevent a decrease in heat transfer performance and an imbalance in the rotation 1tL11. The steam control valve 16 is closed when the temperature of the body heat surface 21 drops to t.

According to this embodiment, the temperature of the heat transfer surface 21 and the opening degree of the steam control well 16 are set to l! Heat transfer surface 21
The attached solid matter can be effectively removed by shrinking the material. Therefore, it is possible to prevent a decrease in the heat transfer ability, a loss of balance in the rotation g J 7, etc. As a result, there is no need to stop the operation to remove deposits as in the past, and continuous operation for a long period of time (specifically, about one week) is possible, and the operating rate can be improved.

As a method of detecting the temperature of the heat transfer surface 21, for example, as shown in FIG. Alternatively, it may be attached to the steam return pipe 14 as shown in FIG. 5, and the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described in detail above, according to the operating method of the centrifugal thin film dryer according to the present invention, it is possible to effectively remove the solid matter adhering to the heat transfer surface. There is no need to stop operation at any time, allowing continuous operation for long periods of time, and improving the operating rate.

[Brief explanation of drawings]

1 to 3 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a diagram showing a centrifugal thin film dryer and its surrounding structure, FIG. 2 is a sectional view of the centrifugal thin film dryer, and FIG. The figure is a characteristic diagram showing temporal changes in the heat transfer surface temperature and the opening degree of the control valve, and FIGS. 4 and 5 are cross-sectional views of a centrifugal thin film dryer according to another embodiment. 2... Processing liquid, 5... Centrifugal thin film dryer, 16...
Steam control valve, 17... temperature detector, 18... control device. Applicant's representative Patent attorney Takehiko Suzue @ 1 figure, 4 figures, 5 figures

Claims (2)

[Claims] (1) A rotating shaft with rotary blades rotates with a small gap formed between the rotary blade and the heat transfer surface on the inner surface of the cylinder, and the processing liquid is introduced and heated to the evaporation temperature by centrifugal force and heated steam. It evaporates by flowing in a thin film along the heat transfer surface, and
1. A method of operating a centrifugal thin film dryer in which evaporation residue is scraped off by rotary blades, characterized in that the return flow rate of the heated steam is controlled by the temperature of the heat transfer surface. (2) The centrifugal thin film according to claim 1, characterized in that when the temperature of the heat transfer surface exceeds a preset steam temperature, the return flow rate of the heated steam is increased in accordance with the exceeded temperature. How to operate a dryer.