JPH0751502A - Drum dryer - Google Patents

Abstract

PURPOSE:To precisely set drying temperature corresponding to desired drying temperature of a raw material even if a drum temperature is in a low temperature range and to make the apparatus compact and lower the cost by heating the drum with a low pressure steam by decreasing the pressure of the inside of the drum by a pressure decreasing system. CONSTITUTION:The steam introduced into drums 3a, 3b from a steam introducting part 21 heats the drums 3a, 3b and itself is condensed by heat exchange between it and drums 3a, 3b. Meanwhile, the inner pressure of the drums 3a, 3b is measured with a pressure detector 34 and the open degree of the pressure adjusting valve 23 is so adjusted as to set the measured pressure value to be a previously set indicated pressure value in order to keep the insides of the drums at a prescribed vapor pressure and keep the drum temperature to be a prescribed temperature. At that time, since the pressure of the insides of the drums is decreased by an evacuating vacuum system 10, the drums 3a, 3b can be heated with the low pressure steam and the drum temperature can be set precisely even if the temperature is in a low temperature range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum dryer preferably used for producing dried products.

[0002]

2. Description of the Related Art The above-mentioned drum dryer is for producing dried products such as chemical products, chemicals, foods, dye products, etc.
Some of these products deteriorate in quality when they are subjected to an abnormally high heat during the drying process.

Therefore, in recent years, vacuum type drum dryers have been attracting attention, in which raw materials are dried at a low temperature under a low vapor pressure under a low pressure so as not to give a harmful heat history during manufacturing. .

The vacuum type drum dryer sets the inside of the chamber to a vacuum region by an evacuation mechanism, rotates the drum in a heated state by introducing steam into the chamber, and causes liquid material to adhere to the surface of the drum. It is dried and solidified, and the solidified raw material is scraped off with a scraper knife.

[0005]

In such a drum dryer, when the drum temperature becomes considerably higher than the drying temperature of the raw material, the dry raw material is dried by heat conduction from the drum after the raw material is dried and before scraping with a knife. High heat is applied to the product, which may deteriorate the dried product. Therefore, when performing low temperature drying, it is desirable to lower the drum temperature, but the conventional drum dryer has a problem that the drum temperature cannot be set to a low temperature range.

On the other hand, conventionally, there is also one that adjusts the drum temperature by introducing hot water into the drum.

[0007] However, since hot water has a low heat transfer coefficient and is likely to have an uneven temperature distribution, it is necessary to circulate the hot water at a high speed in order to eliminate temperature unevenness, and large-scale equipment is required. As a result, the size of the device is increased and the cost is increased. For this reason, in small-scale drum dryers such as experimental equipment, hot water may be used for heating the drums, but in medium-sized or larger drum dryers used in general factories, warm water is used for drum heating. It is currently not used.

The present invention solves the above-mentioned problems of the prior art, can accurately set the drum temperature according to the drying temperature of the raw material even in a low temperature range, and can make the apparatus compact and reduce the cost. The purpose is to provide a drum dryer that can.

[0009]

In order to achieve the above object, a drum dryer of the present invention heats a drum housed in a chamber capable of depressurizing by introducing steam into the drum dryer, and at the same time, forms a liquid on the drum surface. The gist of the present invention is to provide a drum dryer in which the raw materials are adhered and dried and solidified, and a depressurizing mechanism for depressurizing the inside of the drum is provided.

[0010]

The drum dryer of the present invention is provided with a pressure reducing mechanism for reducing the pressure inside the drum. Therefore, when the steam is introduced into the drum, the pressure in the drum is reduced by the pressure reducing mechanism, so that the drum can be heated by the low pressure steam.

Further, since hot water that accompanies large-scale equipment is not used for heating the drum, the apparatus can be made compact and the cost can be reduced.

[0012]

1 is a schematic view showing a vacuum type double drum dryer according to an embodiment of the present invention, and FIG. 2 is a schematic front sectional view showing an apparatus main body of the drum dryer. As shown in both figures, the drum dryer includes an apparatus main body (1) having a vacuum chamber (2), a vacuum exhaust mechanism (10) constituting a decompression mechanism, and steam introduction for introducing steam into the drum. It has a mechanism (20) and a drain discharge mechanism (30) for discharging the drain inside the drum.

In the vacuum chamber (2) of the apparatus main body (1), two drums (3a) and (3b) are arranged in parallel with each other.

The drums (3a) and (3b) and the rotary shaft portions (4a) and (4b) thereof are each formed in a hollow structure,
These interiors communicate with each other. Rotating shaft (4a)
Both side portions of (4b) are arranged in a hermetically sealed manner through the chamber wall, and are rotatably supported by the chamber wall. Further, the rotary joints (5) are attached to both ends of the rotary shafts (4a) (4b) pulled out of the chamber.
a) (5b) (6a) (6b) are externally fitted. The rotary joints (5a) (5b) (6a) (6b)
Is rotatably attached to each of the rotating shaft parts (4a) and (4b), and is designed not to rotate regardless of the rotation of the drums (3a) (3b) and the rotating shaft parts (4a) (4b). ing.

On the other hand, one end of the exhaust pipe (11) in the vacuum exhaust mechanism (10) is connected to the vacuum chamber (2), and a condenser (12) and a condensate are provided at the other end of the exhaust pipe (11). A tank (13) is provided, and the vapor phase outlet of the condensate tank (13) is a vacuum pump (1
In 4), the liquid phase outlet is connected to the condensate extraction pump (15).

In the vacuum evacuation mechanism (10), when the pumps (14) and (15) are operated, the gas in the chamber is introduced into the condenser (12) by the suction action and cooled by the cooling water there, Only the vapor component in the gas is condensed and liquefied and sent to the condensate tank (13). Further, the gas phase component in the condensate tank (13) is discharged by the vacuum pump (14),
The liquid phase component will be discharged by the condensate extraction pump (15). The pressure in the chamber is reduced by the condensation and discharge actions at this time.

The steam introduction mechanism (20) for introducing steam (steam) into the drums (3a) (3b) includes:
A steam introduction part (21) is provided, and the steam introduction part (21) and the rotary joints (5a) (5b) are connected by a steam introduction pipe (25). As a result, the steam introduced from the steam introducing section (21) is divided into two parts, and the drum (3) passes through the rotary joints (5a) (5b) respectively.
a) It is designed to be introduced into (3b).

The steam introducing pipe (25) is provided with a steam main valve (22) for stopping / allowing the introduction of steam and a pressure adjusting valve (23) for adjusting the amount of steam introduced. ing.

The drain discharge pipes (35a) (35) are provided inside the other ends of the rotary shafts (4a) (4b) along the axis thereof.
b) is arranged and this drain discharge pipe (35a)
One end of (35b) is bent downward in the drum, and the other end is open inside the rotary joints (6a) and (6b).

The drain discharge pipes (35a) (35b)
Is fixed to the rotary joints (6a) (6b),
Regardless of the rotation of the drums (3a) and (3b), the bent end portion is arranged so as to be immersed in the upper layer portion of the condensed liquid liquefied in the drum.

The rotary joints (6a) (6b) are connected to the drain tank (32) by a drain pipe (31). The drain pipe (31) has a rotary joint (6
a) and the drain tank (32) between the automatic opening / closing valve (31a) for interrupting / permitting the conduction in the pipe, and the rotation joint (6b) on the other side and the drain tank (32) for the conduction in the pipe. Automatic open / close valve that shuts off / allows (3
1b) are provided.

The liquid phase outlet of the drain tank (32) is connected to the drain discharge pump (33), and the gas phase outlet is connected to the exhaust pipe (11) of the vacuum exhaust mechanism (10) via the suction pipe (40). ) Is connected to. Further, the suction pipe (40) is provided with a flow rate adjusting valve (41), and the bypass pipe (42) arranged so as to bypass the valve (41) is provided with a bypass valve (43). There is.

Further, the drum dryer in this embodiment is provided with a pressure detector (34) for detecting the internal pressure of the rotary joints (6a) (6b) and a pressure control device (50). The pressure control device (50), based on the output signal from the pressure detector (34), will be described in detail later.
The opening of the pressure regulating valve (23) is controlled.

On the other hand, as shown in FIG. 2, the drum (3a)
A central portion of the scraper body (60) is rotatably provided on both upper sides of (3b). Scraper body (6
The scraper knife (61) is fixed to one piece of (0) and the lower end of the spindle (62) is attached to the other piece. Further, the spindle (62) is screwed into the spindle support (63) outside the chamber, and when the spindle (62) is moved up and down by rotating the handle (64) attached to the upper end of the spindle,
The scraper body (60) rotates so that the scraper knife (61) comes into contact with and separates from the drums (3a) and (3b).

Further, above the space between the drums in the chamber (2), a raw material supply mechanism (6) for supplying a liquid raw material is provided.
5), and a transport mechanism (66) for transporting the dry raw material scraped from the drum surface to a predetermined location on both sides of the drum (3a) (3b).

In this drum dryer, when the liquid raw material is dried, the inside of the chamber is depressurized by the vacuum exhaust mechanism (10) as described above. At the time of this pressure reduction, the flow control valve (4) of the suction pipe (40) is
1) and the bypass valve (43) and the automatic open / close valves (31a) (31b) of the drain discharge mechanism (30) are opened, and the steam source valve (22) of the steam introduction mechanism (20) is closed. As a result, the inside of the drain discharge mechanism (30) is connected to the inside of the vacuum exhaust mechanism (10) through the suction pipe (40), and the insides of the drums (3a) and (3b) are sucked together with the inside of the chamber. The Rukoto.

In this way, when the inside of the chamber (2) and the inside of the drums (3a) (3b) are lowered to the predetermined vacuum regions, respectively, the drums (3a) (3b) are rotated while the bypass valve (43) is closed. The steam main valve (22) is opened to introduce steam into the drums (3a) and (3b) from the steam introducing section (21).

The steam introduced into the drum is transferred to the drum (3
A) (3b) is condensed by heat exchange with (3b) to heat the drums (3a) and (3b). Furthermore, the condensate in the drum, that is, the drain (D), is
The pressure difference between the inside of b) and the inside of the drain tank (32) is guided to the drain tank (32) of the drain discharge mechanism (30) through the drain discharge pipes (35a) (35b), and through the drain discharge pump (33). Is discharged. In these operations, the pressure inside the drum is reduced due to the condensation of the steam, and the steam is introduced into the drum so as to compensate for the reduced pressure. Will be discharged from.

On the other hand, the pressure detector (34) detects the internal pressure of the rotary joints (6a) (6b) and outputs a signal corresponding to the detected value. Then, based on the output signal, the pressure control device (50) obtains the internal pressure of the drums (3a) (3b) that is correlated with the internal pressure of the rotary joints (6a) (6b),
The opening of the pressure regulating valve (23) is adjusted so that the measured pressure value becomes equal to the instruction pressure value preset by the operator. For example, when the measured pressure value is higher than the preset instruction pressure value, the opening degree of the pressure adjusting valve (23) is adjusted so that the amount of steam introduced is decreased, and the detected pressure value is When the pressure is lower than the predetermined instruction pressure value, the opening degree of the pressure control valve (23) is adjusted so that the steam introduction amount increases.

Thus, the inside of the drum is maintained at a predetermined vapor pressure and the drum temperature is maintained at a predetermined temperature.

On the other hand, when the drum temperature stabilizes, full-scale operation is started. That is, the liquid material is supplied from the material supply mechanism (65) and adhered to the drum surface. The adhered raw material is dried and solidified while the drums (3a) and (3b) rotate, and the solidified raw material is scraped off by a scraper knife (61) which is brought into contact with the drum surface by a handle operation. The scraped dry raw material is collected at a predetermined location by the raw material transport mechanism (66).

Even during this full-scale operation, the pressure control device (50) adjusts the opening of the pressure adjusting valves (23a) and (23b) to maintain the inside of the drum at a predetermined pressure and keep the drum temperature at a predetermined level. There is no change in maintaining the temperature.

The drain tank (3
It is not preferable to excessively reduce the gas pressure of 2). That is, if the gas pressure in the drain tank (32) is too low, steam is sucked together with the drain (D) in the drum, resulting in heat loss. Therefore, it is preferable to appropriately adjust the opening of the flow rate adjusting valve (41) of the suction pipe (40) and set the gas pressure of the drain tank (32) to the extent that vapor is not sucked.

According to this drum dryer, when the drums (3a) and (3b) are heated by introducing steam into the drums, the interior of the drums is depressurized by the vacuum exhaust mechanism (10). The drums (3a) and (3b) can be heated, and the drum temperature can be set even in a low temperature range.

Further, by appropriately changing the indicated pressure value preset in the pressure control device (50), the internal pressure of the drums (3a) (3b) can be set to an arbitrary pressure, and the drum temperature Can be accurately set according to the drying temperature of the raw material.

Further, in this embodiment, since the inside of the drum is depressurized by utilizing the vacuum exhaust mechanism (10) for sucking inside the chamber, it is not necessary to separately provide a depressurizing mechanism dedicated to the drum. Therefore, the cost can be reduced and the device can be made compact accordingly. However, in the present invention, the mechanism (1
It is not necessary to depressurize the inside of the drum by using 0), and a depressurizing mechanism dedicated to the drum may be separately provided.

Further, of the heat quantity required for the drying process of the drum dryer, the steam quantity (heat quantity) sucked to depressurize the inside of the drain tank is a very small quantity, so that running cost etc. may increase. Nor.

By the way, when the present invention is applied to the double drum dryer as in the above-described embodiment, in the drain discharge mechanism (30), due to the difference in the pipe resistance due to the pipe shape and the like, one side drum, for example, The drain (D) may be sucked and discharged only from the drum (3a), and the drain (D) may not be sucked and discharged from the other drum, for example, the drum (3b). However, as in this embodiment, the drain valves (31) are provided with automatic opening / closing valves (31a) (31b).
Is provided and the automatic opening / closing valves (31a) (31b) are automatically opened and closed alternately by using a timer or the like, a sufficient suction force is alternately applied to any of the drums (3a) (3b). Thus, the drain (D) in the drum can be reliably discharged.

In the above embodiments, the case where the present invention is applied to the double drum dryer has been described, but the present invention can also be applied to the single drum dryer.

[0040]

According to the drum dryer of the present invention,
Since the decompression mechanism for decompressing the inside of the drum is provided, when the steam is introduced and the drum is heated, the inside of the drum is decompressed by the decompression mechanism, so that the drum can be heated by the low pressure steam. Even if the drum temperature is in the low temperature range, the drum temperature can be accurately set according to the drying temperature of the raw material. Further, since hot water accompanied by a large-scale facility is not used for heating the drum, it is possible to obtain an effect that the apparatus can be made compact and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic view showing a drum dryer which is an embodiment of the present invention.

FIG. 2 is a schematic front cross-sectional view showing an apparatus main body of the drum dryer of the above embodiment.

[Explanation of symbols]

 2 ... Chamber 3a, 3b ... Drum 10 ... Vacuum exhaust mechanism

Claims (1)

[Claims] 1. A drum dryer in which a drum housed in a chamber capable of depressurization is heated by introducing steam into the chamber and at the same time a liquid material is attached to the surface of the drum to dry and solidify, A drum dryer, which is provided with a decompression mechanism for decompressing the inside.