JPS61138085A - Moisture controller for drier - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a moisture control device for a dryer used in a sugar refinery to dry powder products having increased moisture content, such as sugar.

<Prior art> The conventional technology of countercurrent drying will be explained based on Fig. 3. 1 shows the input container and par into which the product P to be dried such as white sugar is put, 2 shows the product P' after the drying process has been completed. 3 is a dryer which connects the input cap and output hopper and is rotatably driven, and 4 is a belt conveyor means for conveying the discharged product P' to the next process. .

Reference numeral 5 designates a blower fan, which sucks dry air A to the outlet part 2 side, moves the dryer 3 in the opposite direction to the moving direction of the product P, and introduces moisture-containing air A' to the inlet part 1 side. Let it be exhausted to the outside air.

6 is a heater for heating the dry air inlet, and the temperature of the drawn dry air is adjusted by the flow rate of the steam S.

7 is a temperature controller for controlling the temperature of the air on the side of the input hopper 1 to be constant, and the measured value BT and the temperature target setting/value ST receiver of the temperature control valve 9 are for regulating the flow rate of the steam S. Sends the operation output to.

Reference numeral 10 denotes a moisture meter that detects the moisture content of the product P' on the belt conveyor, and an infrared surface moisture meter or the like is used. 11 is a delay circuit that applies a time delay to the measured value E□ of this moisture meter, and 12 is a motor 13 that uses the output EHL of this delay circuit as a measured value and receives the moisture target set value SH to rotate the blower fan 5.
The moisture content in the product P' is controlled to a target set value sHK by a moisture controller that transmits an operational output.

However, with this type of control system, there is a large time delay from when the product is put into the input hopper until it is measured by the moisture meter 10, and it is only possible to achieve accuracy under the limited conditions of a constant supply of product and a constant dew point temperature of the outside air. It is possible to make dried products.

However, in actual sugar refining operations, the amount of sugar fed into the dryer is batchwise due to the operating intervals of the separator, crystallizer, etc., and the amount of sugar fed fluctuates greatly, making it almost impossible to keep it constant. Operators are forced to frequently check the moisture content of the product whenever the load fluctuates, set the moisture controller to manual mode, change the speed of the blower fan, and change the set value of the temperature controller. was.

In general, it is ideal for products that require drying to be dried to meet their moisture specifications while avoiding excessive drying. In other words, it is essential to reduce the number of defective products due to over-drying or under-drying, as well as to provide an appropriate energy supply for drying, in order to reduce production costs and maintain product quality. is difficult to realize.

<Problems to be Solved by the Invention> The present invention solves the above-mentioned problems of conventional equipment, and can improve quality and reduce defective products by controlling the moisture content of products to a target value regardless of load fluctuations. The purpose of this invention is to realize a nine-drying control device that eliminates the amount of steam used to heat the drying air and energy loss in the power consumption of the blower fan.

Means for Solving the Problems> The structural feature of the present invention is that the products to be dried are moved in the dryer toward the input hopper, the output hopper, or the opposite direction, and the blower fan In a dryer that sucks and discharges heated air from the output ho and bar sides to the input hopper side, a humidity sensor measures the humidity of the discharged air on the input hopper side, and a humidity sensor measures the temperature of the discharged air. When the temperature is set, a humidity converter calculates the maximum set humidity at that temperature based on the output signal of the sensor based on the moisture saturation line; a humidity corrector corrects the output of the humidity converter; The present invention further comprises an adjusting means for generating an operational output for controlling the rotational speed of the blower fan, with the output of the correction means as a set value and the output of the humidity sensor as a measured value.

Function> Input the dryness (moisture) of the product, calculate the discharge from the hopper side according to the moisture saturation level, correct this calculation result manually or by the dew point temperature of the intake air, and set the humidity as the set value. By controlling the rotation speed of the blower fan so that the output of the sensor becomes the set value, the dryness of the product (humidity of the discharged air) is controlled to the target set value.

<Example> Description will be made based on the configuration diagram in FIG. 1 and the characteristic diagram in FIG. 2. Same configuration as the conventional device shown in Figure 3! The same reference numerals are given to the elements and the explanation is omitted.

In FIG. 1, 14 is a sensor that measures the temperature of the air at the output point of the heater 6, that is, the air taken into the output hover 2;
15 is the output KTI of the temperature sensor 14 and the temperature set value STl
The receiver is a temperature controller that controls the steam S flow rate control valve 9. If heated air with a relatively stable temperature is obtained from another facility, the temperature control system described above can be omitted.

16 is a humidity sensor that measures the humidity of the discharged air in the input hopper 1@, and measures the absolute humidity in real time with a high-response hygrometer such as a Nluconia hygrometer, and its output Ex is sent to the humidity controller 17. is supplied as a measured value to The humidity controller 17 receives the measured value Ex and the set value Sx, and the limiter 1
8, an operation signal for controlling the rotation speed of the motor 130 of the blower fan 5 is transmitted.

The present invention is characterized in that the drying state of the product is controlled based on the humidity of the discharged air A' by measuring the humidity of the discharged air A'. In the case of a hygrometer type, the degree of saturation is defined by temperature and absolute humidity, so the humidity setting value needs to be corrected based on a signal related to temperature. c119 measures the temperature of exhaust air A'. With a temperature sensor, its output E
T2 is led to humidity converting means 20.

Figure 2 is a conversion characteristic diagram of the humidity conversion means, where the X-axis is the temperature and the y-axis is the absolute humidity (kg/kg).
The curve indicated by the dotted line ψ0 indicates the saturation line (humidity 1001). The maximum value of the humidity setting is below this saturation line, for example 8.
Let the curve ψ1 be 0.

When operating on this curve ψ1, it means that the saturation level is set at 80°C, and when the temperature is T°C, the humidity setting value is 5xl = "When the temperature is 2°C, the setting value is Sx2," The humidity setting changes depending on the temperature.

Reference numeral 21 denotes a humidity correction means, and this correction means uses a manual signal MK and a curve ψ below the maximum humidity setting curve Ipl.
2. It can be shifted by ψ3, and the dryness (humidity) setting of the product can be changed arbitrarily. The output Sx of this correction means is transmitted as the set value Sx of the humidity controller 17.

22 is a dew point sensor that measures the dew point temperature of the air taken into the heater 6, and this output ED is guided to the correction means 21, and when ψ2 is selected as the curve that gives the set value, this curve ψ2 is used as the dew point temperature. Based on the temperature signal ED, a shift correction is performed as shown by the curve lljψ6 indicated by a dashed line.
Humidity changes in the air being drawn in can also be compensated for. This dew point correction means does not necessarily need to be provided if the humidity of the air taken in is stabilized by other means.

Next, sequence control of the system corresponding to the product P that is supplied virtually will be explained. If the product to the dryer is interrupted, the humidity in the exhaust air will drop rapidly and the temperature will rise. As a result, the operational output for controlling the rotational speed of the blower fan with a large deviation in the humidity controller 17 decreases, but since it is better not to lower the rotational speed of the blower fan below a certain value, the lower limit lB is used to control the operational output. The lower limit of is restricted.

23 is a sequence circuit that transiently regulates the operating output of the temperature controller 15, and when no product is supplied, the steam valve 9 is throttled to a certain opening degree from the standpoint of energy conservation.

When product supply starts, the humidity in the exhaust air intake on the output hopper side rises rapidly, so this sudden rise is detected by the output Ex of the humidity sensor 16, and the opening degree of the steam valve 9 is changed for a certain period of time to the opening degree during steady operation. Controller 15 after forcibly regulating
Switch to automatic fixed value control.

24 is a sequence circuit that transiently regulates the operation output of the humidity controller 17, and when there is no product supply, the output of the controller 17 is regulated so that the rotation of the blower fan is at the lower limit value, and the product supply is stopped. If it starts, the humidity sensor output E
This is detected at x and the rotational speed of the blower fan is maintained at a value close to the steady value for a certain period of time, and then automatic control is entered to prevent overflow and overflow caused by large deviations during the transition period.

Although the sequence circuits 23 and 24 are not essential requirements for the apparatus of the present invention, they are effective means when products are supplied in batches.

The embodiment shown in Fig. 1 is a so-called countercurrent type dryer in which the inflow direction of the air inlet is opposite to the moving direction of the product P, but if the dryness of the product is not required to be high, the air inflow direction is A forward flow type in which the products move in the same direction is also used, and the present invention can be similarly applied to the ll1Ijff type.

Effects> As explained above, according to the present invention, the following effects can be expected.

(1) Economic effect It is possible to reduce the number of defective products due to excessive drying, and also to reduce the amount of steam consumed for heating the air and the amount of power consumed by the blower.

(2) Improved quality It is possible to prevent product caking caused by high moisture content, and to achieve product dryness close to the maximum moisture content.

(3) Improved controllability A sequence circuit that sufficiently follows load fluctuations, and can be expected to achieve highly accurate control by incorporating dew point correction of the intake air, and is suitable for transient phenomena at start, stop, and stop times. This can be easily prevented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of humidity converting means and humidity correcting means, and FIG. 3 is a block diagram showing an example of a conventional device. 1... Input hopper 12... Output hopper, 3...
- Dryer, 5... Blower fan, 6... Heater, 14, 19... Temperature sensor, 15... Temperature controller, 16... Humidity sensor, 17... Humidity controller,
20... Humidity conversion means, 21... Humidity correction means, 2
2...Dew point sensor, 23.24...Sequence circuit.

Claims (1)

[Claims] A dryer in which a blower fan sucks heated air from the output hopper side to the input hopper side and discharges the product to be dried, which moves in the dryer from the input hopper toward the output hopper or in the opposite direction. A humidity sensor that measures the humidity of the discharged air on the input hopper side, a temperature sensor that measures the temperature of the discharged air, and the maximum set humidity at that temperature is calculated based on the moisture saturation line based on the output signal of this sensor. a humidity converting means, a humidity correcting means for correcting the output of the humidity converting means, and an operation output for controlling the rotation speed of the blower fan with the output of the humidity correcting means as a set value and the output of the humidity sensor as a measured value. A moisture control device for a dryer, comprising means for regulating moisture generation.