JP2011064441A - Powder drying method and powder drying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently dry powder by simply and easily controlling hot air gas used in the drying of the powder in a predetermined temperature range. <P>SOLUTION: In the powder drying method, raw material powder P dried in a dryer 3 is separated by a separator 5 and extracted. A gas temperature of an outlet of the dryer 3 is detected, and when the gas temperature of the outlet of the dryer 3 reaches a set value or higher, water is supplied to the dryer 3, control is carried out so that the gas temperature in the dryer 3 is maintained at a proper value within a predetermined range, and the drying of the raw material powder P is carried out in a state that the temperature of gas at the proper value is within the predetermined range. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for drying powder with a gas generated by hot air generating means and an apparatus for drying the powder.

In order to dry powders such as light calcium carbonate and titanium oxide, there are drying methods using an air dryer, a fluidized bed dryer, a pulverizer, and a classifier.
As a drying method using the hot air, a hot air generating means, for example, a hot air generator for extracting hot air extracted from various heat generating sources through a heat exchanger, a method of burning gas, and electric heat are used. Drying is performed by generating hot air by the method and exposing the powder to this hot air gas.

  Such a method is performed by, for example, the system (apparatus) shown in FIG. As shown in FIG. 2, the hot air generator 1 is configured to burn separately supplied fuel 2, and a dryer 3 is connected to this by a duct 4, and the powder as a raw material is connected to the dryer 3. A predetermined amount is supplied by a feeder 7, and the dryer 3 is connected to a bag filter type separator (dust collector) 5 through a duct 4, and a wind fan 6 is connected to the dust collector 5 and separated by a bag filter. The exhaust is discharged to the atmosphere.

  Such a system is operated as follows. First, when the system other than the hot air generator 1 and the supply device 7 is operated and it is confirmed that there is no problem, the hot air generator 1 is operated. An outlet temperature sensor 8 is provided at the outlet of the dryer 3. When the generated hot air gas reaches a predetermined temperature, the supply unit 7 is operated to supply raw material powder to the dryer 3. As the hot air gas rises, the amount of powder is increased for a while. This is usually performed by automatic control, but is also configured to be performed by manual control.

  In addition to the outlet temperature sensor 8, an inlet temperature sensor 9 for detecting the temperature of the hot air gas from the hot air generator 1 is also provided on the inlet side of the dryer. The supply amount of the powder is increased until the inlet temperature sensor 9 reaches the set temperature. Then, after the temperature reaches the set temperature, the controller 10 performs control to adjust the powder supply amount. This adjustment is configured such that it can also be performed by adjusting the amount of powder supplied and the method of adjusting the amount of heat of the hot air generator 1.

  The operation of this system is stopped by stopping the operation of the hot air generator 1, reducing the amount of powder supplied in accordance with the temperature of the outlet sensor 8 of the dryer, and reaching a predetermined problem-free temperature. By the way, the supply of powder is stopped, and after it is sufficiently cooled, it is stopped.

Examples of the powder drying method and apparatus include the following techniques.
JP 2003-4377 and Japanese Utility Model Publication No. 5-54985.

  The above conventional method (system) has the following problems. First, when trying to dry as much powder as possible, there is a problem with the balance between the amount of powder and the amount of heat generated by the hot air generator. As one of the countermeasures, the amount of generated heat is adjusted according to the amount of powder. Although it is controlled, it is difficult to control the amount of heat of the hot air generator severely.

  In addition, as another countermeasure (or combination), there is a method of controlling the amount of powder to be supplied with a feeder. However, it is difficult to quantitatively supply moisture-containing powder, and a stirrer is provided. However, even in such a case, it is difficult to adjust the quantitative supply, and it is difficult to perform an appropriate amount of drying corresponding to the hot air gas at a predetermined temperature, but it is currently necessary to adjust the powder supply amount.

  The present invention has been made in view of such problems, and an object of the present invention is to easily and easily control a hot air gas used for drying a powder in a predetermined temperature range so that the powder can be efficiently dried. To do.

In order to achieve the above object, the method for drying powder according to the present invention,
A dryer for drying the raw material powder with the gas generated by the hot air generating means is connected via a duct, a separator is connected to the dryer via a duct, and the separator is discharged to the separator via the duct. In the drying method of the powder that is connected to the air blower, the raw material powder dried by the dryer is separated by the separator, and is taken out,
Detect the gas temperature at the outlet of the dryer,
When the gas temperature at the outlet of the dryer reaches a set value or more, supply water to the dryer,
Control so that the gas temperature in the dryer is maintained at an appropriate value within a predetermined range,
The raw material powder is dried in a state where the temperature of the gas is within an appropriate value within a predetermined range.
It is characterized by that.

In order to achieve the above object, the powder drying apparatus according to the present invention provides:
A dryer for drying the raw material powder with the gas generated by the hot air generating means is connected via a duct, a separator is connected to the dryer via a duct, and the separator is discharged to the separator via the duct. In the powder drying apparatus, which is connected to a fan and separated from the raw material powder dried by the dryer by the separator,
A supply means for supplying the raw material powder to the dryer;
Provide a sensor for detecting the gas temperature at the outlet of the dryer,
Providing a water supply means for supplying water to the dryer based on a result of detecting that the sensor detects a gas temperature at the outlet of the dryer that is equal to or higher than a set value;
The water supply means controls the gas temperature in the dryer to be maintained at an appropriate value within a predetermined range, and the raw material powder is dried in a state where the gas temperature is at an appropriate value within the predetermined range. Configured
It is characterized by that.

The powder referred to in the method and apparatus of the present invention is, for example, light calcium carbonate, titanium oxide or the like, and is used for foods, pharmaceuticals, cosmetics and the like.
In addition, as described in the embodiment, the hot air generating means may be a hot air gas generator provided with a combustion means (burner) itself, but other hot air generating means, for example, another boiler heat source ( You may use a heat exchanger suitably).

  According to the method for drying powder according to the present invention, the temperature of the hot air gas generated by the hot air generating means is detected by the temperature sensor, and the temperature of the hot air gas is obtained by supplying water to the dryer and using the heat of vaporization. Is controlled within a predetermined range, and an optimal amount of powder can be efficiently dried at all times, and the drying efficiency can be increased while being a simple method. In addition, although it is the heat amount control by water, if necessary, the supply amount control by the powder supply device can be used together, and the convenience of the control of the heat generation amount by the hot air generator is also possible. is there. Thereby, quality (moisture etc.) of powder (product) can be stabilized.

In addition, the apparatus has the above-mentioned effects, but if the air volume and gas temperature by the hot air generating means are set, the water volume is controlled based on the detection of the temperature sensor (for example, opening of the valve). Therefore, it can be easily implemented without requiring a particularly expensive control device.
Other advantages of the present invention will become apparent from the following description.

  In the method of the present invention, in the method according to claim 1, the amount of water supplied as the amount of raw material powder supplied to the dryer is increased while the amount of heat generated by the hot air generating means is constant. It is preferable to control the gas temperature at the outlet of the dryer to be equal to or lower than the set value so as to dry the maximum amount of raw material powder while minimizing the amount of water supplied.

  In the apparatus of the present invention, the dryer according to claim 3 is interlocked with the raw material powder supply means and the water supply means so that the gas temperature at the outlet of the dryer is equal to or lower than the set value. It is preferable to control so that the supply amount of the water is decreased as the supply amount of the raw material powder is increased.

  Preferred embodiments of the powder drying method and drying apparatus according to the present invention will be described below in detail with reference to the drawings. At this time, the members having the same functions as the members of FIG. 2 showing the prior art are not confused, and the same member numbers are used. Further, in this embodiment, the case where light calcium carbonate (in other cases, titanium oxide or the like) is used as the powder will be described.

  As shown in FIG. 1, in this drying method, a dryer 3 for drying the raw material powder P by the gas generated by the hot air generating means 1 is connected through a duct 4 and separated into the dryer 3. As a machine, a bag filter type separator (dust collector) 5 is connected through a duct 4, and an air blower (blower) 6 is connected to the bag filter type separator 5 through a duct 4. The raw material powder P dried in step 1 is separated by the bag filter type separator 5 and taken out. The separator 5 may be a cyclone type.

As the apparatus, here, the hot air generating means 1 has a so-called cylindrical structure for burning a burner of liquid fuel. Of course, gaseous fuel may be used, or hot air drawn from a heat source installed in another factory or a heat exchange system (electric heater, steam) may be used.
The dryer 3 has a structure having an agitator 11 inside. However, it may be a chamber structure with a simple duct.

The bag filter type separator (dust collector) 5 may have a structure generally configured for a dust collector, and the raw powder P dried from the bag filter 12 is separated by a pulse jet, dropped, and dropped from below. It is configured to be taken out by the screw feeder 13.
In addition, the wind exhauster 6 is configured to be laid on a bag filter type separator (dust collector) 5 of this type.

  Then, the gas temperature at the outlet of the dryer 3 is detected, and when the gas temperature at the outlet of the dryer 3 reaches a set value or more, water is supplied to the dryer 3, and the gas in the dryer 3 is The raw material powder P is dried in a state in which the temperature is controlled to be kept at an appropriate value within a predetermined range and the temperature of the gas is at an appropriate value within a predetermined range.

  As an apparatus, an outlet sensor 8 is provided in the duct 4 in order to detect the gas temperature at the outlet of the dryer 3. An inlet sensor 9 is provided to detect the gas temperature at the inlet. These sensors are commonly used temperature sensors. And in order to supply water with respect to the said dryer 3, the water supply means 14 is laid. The water supply means 14 includes a function having a function of adjusting the amount of water, here, a control valve 14A. Instead of the control valve 14A, for example, as a pump having a variable discharge amount such as an axial pump, the water amount may be adjusted by controlling the pump.

  And the controller 10 (control circuit) which inputs the detection result of the said inlet sensor 9 and the outlet sensor 8 is provided, the gas temperature of the exit of the said dryer 3 is detected, and the gas temperature of the exit of this dryer 3 is set. When a value, for example, 85 ° C. or higher is reached, a predetermined amount of water corresponding to the amount of heat is supplied to the dryer 3 so that the gas temperature in the dryer 3 is maintained at an appropriate value within a predetermined range. To control.

Furthermore, the amount of heat generated by the hot air generating means 1 is kept constant, and the amount of water supplied is decreased as the amount of the raw material powder P supplied to the dryer 3 is increased. The outlet gas temperature is controlled to be equal to or lower than the set value, and the maximum amount of raw material powder is dried while minimizing the supply amount of water.
The method for drying a powder according to claim 1.

Further, a supply means 15 for supplying the raw material powder P to the dryer 3 is provided as an apparatus. A normal screw feeder is used for this, but it may have a function of quantitatively cutting out a belt conveyor.
And the outlet sensor 8 as a sensor which detects the gas temperature of the exit of the said dryer 3, and the water supply means 14 which supplies water with respect to the said dryer 3 are as above-mentioned.

Further, the supply means 15 for the raw material powder P and the water supply means 14 are linked via the controller 10 so that the gas temperature at the outlet of the dryer 3 is not more than the set value, for example, 85 ° C. or less. Thus, the supply amount of the raw material powder P to the dryer 3 can be controlled so as to decrease the supply amount of the water as the supply amount of the raw material powder P increases.

The operation of the drying apparatus (system) is performed as follows.
The inlet temperature and the outlet temperature corresponding to the inputs of the inlet sensor 9 and the outlet sensor 8 are set.
The supply means 15 is stopped. The air volume of the exhaust fan 6 is set.
Here, the hot air generator 1 is operated, and the temperature of the gas is increased until the inlet temperature reaches a set temperature.

Then, based on the detection result of the outlet temperature by the outlet sensor 8, the water supply means 14 is operated and the amount of water is adjusted.
Next, as the inlet temperature rises, the outlet temperature naturally rises. However, when the outlet temperature reaches a set value, the control valve 14A is activated and the water volume gradually increases. The outlet temperature is held at the set value.

Even after the inlet temperature reaches the set value, the amount of water will increase for a while due to the temperature rise of the entire apparatus, but will gradually converge.
Here, the supply of the raw material powder P is started when the predicted required water amount reaches 90%, and the supply means 15 is gradually increased to the set rotational speed.
Due to the heat of evaporation due to the increase in the amount of water and the loss of heat due to the heating of the raw material powder P, the supply amount of water for a while will be reduced.

Then, while watching the change in the amount of water, the supply amount of the raw material powder P is gradually increased so that the operation is performed with the amount of water as small as possible.
In such an operation, even if the supply amount of the raw material powder P decreases due to a trouble, the temperature of the gas rises due to that, so the temperature is detected by the outlet sensor 8 to increase the amount of water. Thus, stable operation can be performed.

Industrial application fields

  Since the powder drying method and apparatus according to the present invention controls and maintains the temperature of the gas in a stable state by supplying water, an existing drying apparatus is used to perform powder drying efficiently. It can be easily implemented by improving it, and its application range is wide.

1 is a schematic view of a powder drying apparatus according to the present invention. Schematic of the drying apparatus of the powder concerning a prior art.

1: Hot air generator 2: Fuel 3: Dryer 4: Duct 5: Separator 6: Ventilator 7: Feeder 8: Outlet sensor 9: Inlet sensor 10: Controller P: Raw material powder G: Gas

Claims (4)

A dryer for drying the raw material powder with the gas generated by the hot air generating means is connected via a duct, a separator is connected to the dryer via a duct, and the separator is discharged to the separator via the duct. In the drying method of the powder that is connected to the air blower, the raw material powder dried by the dryer is separated by the separator, and is taken out,
Detect the gas temperature at the outlet of the dryer,
When the gas temperature at the outlet of the dryer reaches a set value or more, supply water to the dryer,
Control so that the gas temperature in the dryer is maintained at an appropriate value within a predetermined range,
The raw material powder is dried in a state where the temperature of the gas is within an appropriate value within a predetermined range.
A method for drying a powder characterized by the above. The amount of heat generated by the hot air generating means is kept constant, the amount of water supplied is decreased as the amount of raw material powder supplied to the dryer is increased, and the gas temperature at the outlet of the dryer is Control to be below the set value and dry the maximum amount of raw material powder while minimizing the amount of water supply,
The method for drying a powder according to claim 1. A dryer for drying the raw material powder with the gas generated by the hot air generating means is connected via a duct, a separator is connected to the dryer via a duct, and the mold separator is connected via a duct. In the powder drying apparatus, which is connected to an exhaust fan, and the raw material powder dried by the dryer is separated by the separator, and taken out.
A supply means for supplying the raw material powder to the dryer;
Provide a sensor for detecting the gas temperature at the outlet of the dryer,
Providing a water supply means for supplying water to the dryer based on a result of detecting that the sensor detects a gas temperature at the outlet of the dryer that is equal to or higher than a set value;
The water supply means controls the gas temperature in the dryer to be maintained at an appropriate value within a predetermined range, and the raw material powder is dried in a state where the gas temperature is at an appropriate value within the predetermined range. Configured
A powder drying apparatus characterized by that. As the raw material powder supply means and the water supply means are interlocked, the supply amount of the raw material powder to the dryer is increased so that the gas temperature at the outlet of the dryer is not more than the set value. And configured to control to reduce the supply amount of the water,
The powder drying apparatus according to claim 3.

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