JPH04207175A - Drying of laver sheet by automatically detecting dryness of laver sheet - Google Patents

Abstract

PURPOSE:To easily control the dryness of laver sheet in improved accuracy by detecting the dryness of a laver sheet and controlling the drying condition based on the detection result. CONSTITUTION:The surface temperature of a laver sheet in a drying stage and the wet-bulb temperature of the drying environment are detected in an automatic laver-drying machine. The detection results are inputted to a computer, the dryness is automatically judged by the difference between the detected values and the drying condition is controlled to the optimum level e.g. by controlling the transfer speed of a laver sheet screen, the flow rate of hot air or the temperature and/or the humidity of the hot air.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to detection of the degree of dryness related to fully automated drying of seaweed, and a method of drying seaweed based on the detected value.

[Prior Art] In current automatic seaweed dryers (hereinafter simply referred to as dryers), a seaweed mixture is sequentially shredded into a seaweed basin equipped on a chain via an automatic shredder. In this way, when the dried seaweed that has been sequentially drawn into a large number of seaweed cages passes through the drying chamber of the dryer (hereinafter simply referred to as drying chamber 0), it is heated by hot air heated by an oil burner heater. The structure is such that when the seaweed is dried and leaves the drying room, it is peeled off from the seaweed cage using an automatic peeling machine, thereby producing dried seaweed. At this time, depending on the degree of dryness of the seaweed, methods such as manually increasing or decreasing the temperature setting of the hot air or manually adjusting the humidity via a ventilation device are implemented. Specifically, at the manufacturing site, the method of measuring the degree of dryness is
At the rear of the dryer, the user inserts his/her hand through a hole in the reversible part of the screen frame, and directly touches the surface of the seaweed.The degree of dryness is determined by the sense of touch and the temperature and humidity inside the dryer are controlled. This is the usual method. The following technical documents include methods for drying seaweed and methods for controlling its temperature and/or humidity. Patent Publication No. 63-13665 and No. 63-13666, a method for drying seaweed; Patent Publication No. 63-60985, a humidity control device attached to seaweed drying equipment; Patent Publication No. 63-60986, a humidity control device for a seaweed drying room; Kosho 63-65303
Here and there, you will find information on how to adjust the temperature and humidity of continuous seaweed dryers. [Problems to be Solved by the Invention] As mentioned above, in the past, the degree of dryness was judged by the tactile sensation of the hands and intuition, which was very vague and caused various harmful effects, such as over-drying (described later). As described above, there are problems such as tearing and poor peeling caused by a decrease in moisture content (lower moisture content), and wetting and wrinkling caused by undrying (excessive moisture content, as described later), resulting in lower quality and lower costs. It has become a challenge. However, as will be explained in detail in the next problem analysis, it is better to actually dry the seaweed so that the final moisture content is 8% to 12%. Therefore, if the moisture content of the seaweed becomes less than the above value (decreased moisture content), the seaweed will become damaged, cracked, cracked, etc., and conversely, if it becomes more than the above value ( excessive moisture content), resulting in wetness, shrinkage, wrinkles, etc. As a result, this results in a decline in quality and product value. Therefore, the key to drying is to achieve a degree of dryness that contains an appropriate moisture content during the final drying process, and the current situation is to adjust the dryness through trial and error.

[Analysis of the issue]

The drying characteristics of seaweed are: - When a seaweed cage is transported into a dryer while fishing on a boat, the moisture content and surface temperature change depending on the drying time as shown in FIG. Moreover, FIG. 2 shows the drying rate at that time. That is, in this figure, the drying process is divided into three periods.
B: Preheating period, B: Constant rate drying period, C: Low rate drying period. Here, the characteristics of each period will be explained. First, the preheating period is a period during which the dried seaweed (hereinafter referred to as seaweed in principle) is preheated by dry hot air. Next, the constant rate drying period means that the water that evaporates from the surface of the seaweed is compensated for by the water that seeps out from inside, and a water film is formed on the surface, and the surface temperature becomes lower than that of hot air due to the latent heat of evaporation. , is approximately equal to the wet bulb temperature placed in that atmosphere (hereinafter simply referred to as equal). The moisture content during this period decreases almost linearly (hereinafter simply referred to as linear) as shown in FIG. 1 as time passes. Further, the evaporation rate is approximately constant (hereinafter simply referred to as constant) as shown in FIG. 2, and is an important part of the drying process. Furthermore, the lapse rate drying period means that the moisture content inside the seaweed decreases, and the moisture seeping out from inside the seaweed cannot catch up, and after the drying limit, the seaweed dries and at the same time its surface temperature rises, causing hot air to dry out. As the temperature approaches, the evaporation rate decreases rapidly. Finally, the equilibrium moisture content becomes 5% to 6%. Therefore, among the above-mentioned drying characteristics, the seaweed drying surface temperature will be explained in detail. That is, the seaweed surface temperature during the constant rate drying period is equal to the wet bulb temperature in a dry atmosphere due to the temperature and humidity of hot air. When the prudent limit in this constant rate drying period is passed and the decreasing rate drying period begins, the evaporation rate decreases, the temperature drop decreases accordingly, and the surface temperature decreases due to the humidity in the drying atmosphere, as shown in Figure 3. It gradually rises above the bulb temperature, and at the end of the drying period, it stops evaporating and absorbs the latent heat of evaporation, so it becomes equal to the hot air temperature. [Means for Solving the Problems] In view of the above, the present invention uses scientific means to more accurately and easily determine the degree of dryness, which was conventionally determined by the tactile sensation of the hand and intuition. It is intended to determine
The following method was adopted. That is, the present invention detects the surface temperature of seaweed during drying and the wet bulb temperature of the drying atmosphere in an automatic seaweed dryer, inputs the detected values into a computer, and calculates the detected values. Automatically determine the degree of dryness based on the difference in values, and use appropriate drying conditions, for example, by controlling the transport speed of the seaweed cage, by controlling the speed of hot air, or by controlling the temperature and/or humidity, This is a seaweed drying method that automatically detects the degree of seaweed dryness.

【Example】

In order to accurately detect the degree of dryness during the drying process, the present invention focuses on the fact that the prudent limit of drying characteristics is generally determined by the presence or absence of a temperature difference between the seaweed surface temperature and the wet bulb temperature. , to accurately detect the difference. Through this, we can understand the prudent limits of the constant rate drying period for seaweed, and
This is a method to control the degree of drying of the seaweed. Specifically, when observing the surface of seaweed during a period of constant drying, it is completely black and moist. This is evidence that the surface of the seaweed is covered with a film of water. The seaweed surface in this state is
When the cautious limit is exceeded, the surface color of the dried seaweed changes and its surface temperature gradually rises. For example, the surface temperature is detected by measuring infrared rays emitted from the surface of seaweed during a period of constant drying. That is, the surface temperature is measured using an infrared thermometer, and the measured value signal is simultaneously compared with the wet bulb temperature in the atmosphere, or the surface condition in a corresponding wet state, with the measurement signal measured using the infrared thermometer. , the degree of seaweed dryness is determined based on the presence or absence of a difference and the size of the difference (computer processing). In order to make a more accurate determination, the same measurement as above is carried out at the midpoint of the lapse rate drying period, and by knowing the changes in both, it is possible to determine which part on the drying characteristic curve the drying characteristic curve is passing through. Therefore, the degree of dryness of the seaweed can be determined even more accurately. By determining the degree of dryness according to the present invention, if the dryness is too dry (so-called overdrying), either lower the hot air or the temperature inside the dryer, humidify the dryer through ventilation or humidity control means such as a humidifier, or increase the humidity. Automatic processing such as increasing the conveyance speed of the seaweed cage to shorten the drying time, or reducing the speed of hot air. On the other hand, when the drying is insufficient (when the dryer is wet), increase the temperature of hot air or the inside of the dryer, dehumidify through ventilation or humidity control means of a dehumidifier, reduce the conveying speed, or reduce the speed of the hot air. Perform automatic processing such as speeding up. In the past, even automatic dryers often judged the degree of dryness using the tactile sensation of the hand and carefully monitored and adjusted the drying conditions to ensure proper drying. By automatically detecting the degree of dryness without bothering the user, and then automatically adjusting the drying conditions using a computer or the like based on the results to perform proper drying, it is possible to completely automate the drying of seaweed. With that,
This saves labor and makes it possible for unskilled people to operate the vehicle. Note that the thermometer is not limited to the above-mentioned infrared thermometer.

【Effect of the invention】

As explained above, the present invention is a method of detecting the degree of dryness and controlling drying conditions based on the detected value, and has the following effects. First, the present invention has the effect of making it possible to more accurately and easily determine the degree of dryness using scientific means, instead of the conventional method of determining the degree of dryness based on the tactile sensation of the hand and intuition. This also has the practical effect of enabling automatic operation through computer control of drying conditions. Furthermore, in the past, even with automatic dryers, the degree of drying was often judged by the touch of the hand, and drying conditions were changed to ensure proper drying, with careful monitoring and adjustment performed. However, according to the present invention, the degree of dryness is automatically detected without human intervention, and based on the results, the drying conditions are automatically adjusted using a computer etc. to perform proper drying, thereby completely drying the seaweed. It enables automation. It has excellent practical effects, such as saving labor and making it possible for unskilled people to operate the vehicle. Furthermore, there is an effect that high quality dried seaweed can be produced efficiently and relatively easily.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing changes in time, moisture content, and temperature during drying of seaweed.

FIG. 2 is an explanatory diagram showing changes in time and evaporation rate during drying of seaweed.

FIG. 3 is an explanatory diagram of the characteristics of seaweed surface temperature. Patent applicant: Furuta Electric Co., Ltd. Agent: Patent attorney: Takenaka - Nobuo 1tJ”

Claims (4)

[Claims] Claim 1: In an automatic seaweed dryer, the surface temperature of seaweed that is being dried and the wet bulb temperature of the drying atmosphere are detected, the detected values are input into a computer, and the detected values are A method of drying seaweed that automatically determines the degree of dryness based on the difference in seaweed and automatically sets and controls the appropriate drying conditions. 2. The method for drying seaweed by automatically detecting the degree of dryness of the seaweed according to claim 1, wherein the drying conditions according to claim 1 are controlled by the conveyance speed of the seaweed cage. 3. The method for drying seaweed by automatically detecting the degree of dryness of the seaweed according to claim 1, wherein the drying conditions according to claim 1 are controlled by the speed of hot air. 4. The method for drying seaweed by automatically detecting the degree of dryness of seaweed according to claim 1, wherein the drying conditions according to claim 1 are controlled by temperature and/or humidity.