JPS59119174A - Controller for combustion of burner in cereal grain 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] In conventional grain dryers, the hot air temperature of the burner is set appropriately according to the amount of grain, so there are differences in the water removal ability of the hot air due to differences in outside air humidity, and drying due to the type and quality of grain. Differences in ease of drying were not taken into account, and the drying speed varied widely, resulting in long drying times and drying too quickly, which sometimes resulted in cracking of the shell.

To overcome this drawback, it is necessary to control the combustion of the burner so as to keep the drying rate of the grain constant.

Since the drying rate is the decrease in the moisture content (%) of the grain per unit time, the moisture content at a certain time is a.

If the moisture content after unit time is b, then the drying rate P (37 hours) at that point is p = a - b
(Equation 1) When the drying speed is P, the weight of water evaporated from the grain per unit time, that is, the amount of water removed Q (Kg
7 hours), if the amount of grain at a certain time is A (Kg), and the amount of grain after that unit time is B (Kg), then Q = A - B (equation 2) By the way, the number of grains excluding water Since the weight of the material does not change before and after drying, the following formula holds true.

If b and B are determined from (Formula 1) and (Formula 3) and substituted into (Formula 2), the following is obtained.

Generally, the appropriate drying rate P for paddy and wheat is 0.6 to 1.2 (
%/hour M')t, but if p = o
, s″C is constant, and the amount of water removed Q that evaporates from the entire 1000 kg of grain every hour is determined from (Equation 4), A = 1
000Kg, so a=25C%), then Q=11 (Kg/hour) a=
When zo (%), Q=10 (Kg/hour) a=15
(%), Q = 9.3 (xg/hour). When the relationship between the moisture content a and the amount of water removed Q is plotted, the graph shown in FIG. 4 is obtained.

When the drying rate P is set to a certain value in this way, the amount of water removed Q can be determined from the moisture content a and the amount of grain A by calculating (Equation 4).

Therefore, the moisture content a and grain amount A of the grains during drying are measured, and based on the measured values, the amount of water removed Q that will give the optimum drying speed P is calculated sequentially. If the combustion of the burner is controlled so that the amount of water q is the same, the drying rate P can be maintained at a constant optimum value from beginning to end, and grain shell cracking will not occur.

Based on this knowledge, the present invention aims to keep the drying speed P constant by matching the actually measured water removal amount q to the reference water removal amount Q calculated from the amount of grain being dried. .

Referring to the drawings of the embodiment of the present invention, reference numeral 1 denotes a storage chamber of a dryer, and a chevron plate 2 having an inverted V-shaped cross section is provided at the center of the bottom of the storage chamber 1, and guiding swash plates 3, 3 are arranged opposite to each other on the left and right sides of the chevron plate 2. Install. Perforated plates 4 are connected to both side edges of the chevron-shaped plate 2 and the lower edges of the guiding swash plates 3, 3, respectively, and a set of two opposing perforated plates 4 are connected to each other.
The drying chambers 5, 5 are formed by this.

The discharge port at the lower end of the drying chamber 5.5 is connected to the gutter-like grain flow chamber 7 through the rotary valve 6, and the delivery end of the grain feeding helix 8 suspended horizontally in the concave groove in the center is connected to the grain raising machine 9. Connect to the bottom intake.

A hull helical lO is connected to the upper part of the grain raising machine 9, and its terminal end is opened above the diffusion plate 11 suspended from the center of the ceiling plate of the storage chamber 1.

Then, a burner 12 and a suction fan 13 are installed opposite to each other on the front and back sides of the dryer, and the burner 12 is connected to the left and right drying chambers 5 and 5.
The fan 13 is connected to the outside of the drying chambers 5, 5 and to the exhaust chamber 15 surrounded by the outer wall of the dryer. 16 is a shield plate that closes off the side of the hot air chamber 14 opposite to the burner 12.

The grains pass through the grain hoist 9 and the hull helix 10, are spread evenly into the storage chamber 1 by the diffusion plate 11, and flow down the drying chamber 5.

At this time, the hot air from the burner 12 enters the left and right drying chambers 5 from the central hot air chamber 14, dries the grains flowing down, and the exhausted air containing moisture passes through the exhaust chamber 15 and is sent to the 7-an 13. Exhaust outside.

After drying, the grains are passed through a rotary pulp mill 60 times and transferred to a flow grain chamber 7.
The grains fall into the storage room 1 through the grain feeding helix 8 and the grain elevator 9.

Since all the water evaporated from the grains is included in the exhaust air, the actual measured amount of water removed q is determined by the difference in absolute humidity between the hot air and the exhaust air and the air volume K (Kg) that passes through the drying chamber 5 during unit time. equals the product. Absolute humidity is the number of grams of water contained in every kilogram of air, so when this is converted into kilograms, the following formula holds true.

q = (Absolute humidity of exhaust air - Absolute humidity of hot air) X O, 00
1X K (Kg/hour) (Formula 5) Since the absolute humidity difference between hot air and exhaust air is proportional to the temperature difference between the two, let the ratio be k.

Therefore, when actually operating the dryer, the normal hot air temperature is between 40°C and 50°C, and now the absolute humidity of the hot air is 4 to 8 (g/Kg), temperature is 27°C
If the temperature is between 29° C. and 29° C., the absolute humidity at the exhaust air temperature at that time is determined as shown in Table 1, as shown by the broken line in the humidity diagram in FIG.

Table 1 Within this range, the value of k is found to be 0.42.

Therefore, from (Equation 5) and (Equation 6), q = (temperature of hot air - temperature of exhaust air) Xo, 42mXK (7
formula). Here, m is the efficiency obtained by subtracting the amount lost due to temperature rise between the dryer and the grain, and is a constant compensation coefficient determined by the model and specifications of the dryer, the type and quality of the grain, etc.

However, in the present invention, temperature sensors Sa and Sb are installed inside the hot air chamber 14 and the exhaust air chamber 15 of the dryer, respectively.
These sensors are connected to an arithmetic circuit E that calculates the actually measured water removal amount q according to the formula.

On the other hand, the support leg 17 at the bottom of the dryer has a built-in sensor, such as a resistance wire strain meter, that converts weight into electricity, and receives the sensor signal and calculates the amount of grain A (Kg) proportional to the amount of grain in the dryer. A grain amount measuring circuit W that outputs voltage is provided.

The grain amount measuring circuit W may be configured by arranging several pressure detection switches or photoelectric switches 18 vertically on the inner wall of the grain storage chamber 1 at equal intervals. In this case, as the drying progresses, the volume of the entire grain decreases and the upper switch 18 is exposed, converting this into a change in grain amount and outputting a voltage proportional to the weight A (Kg).

Then, the grain amount measuring circuit W is connected to the reference water removal amount calculation circuit N, and in this circuit N, the reference water removal amount Q is calculated according to the output value of the circuit W and the preset water content a.
Calculate the value of .

Next, the output sides of the circuits N and E are connected to a comparator C, and the output side of the comparator C7 is connected to the fuel valve V of the burner 12. Then, the measured water removal amount q is compared with the calculated standard water removal amount Q, which should be the standard. If q is larger than Q, valve V is closed, and if it is smaller, valve V is opened by burner 1.
2 combustion is automatically controlled.

In short, in the present invention, the weight of the grains to be dried is measured, the reference water removal amount Q that keeps the drying rate constant is calculated from the measured value, and the calculated reference water removal amount Q and the actual water removal amount are Combustion is controlled so that q is always the same, so even if the outside temperature and grain type and quality are different, there will be no difference in drying speed P and drying can be done at a stable speed.This prevents shell cracking and ensures good quality. This produces a drying effect on the grain.

Furthermore, in the present invention, the measured water removal amount q is determined from the temperature difference rather than from the absolute humidity difference between the hot air and the exhaust air, so there is no need for an expensive hygrometer, and highly accurate measurement can be performed using an inexpensive temperature sensor. .

[Brief explanation of the drawing]

Fig. 1 is a vertical front view of a grain dryer embodying the present invention, Fig. 2 is a cross-sectional plan view thereof, Fig. 3 is a block diagram of its control system, and Fig. 4 is a drying speed P of 1000 kg of grain. =
Standard water removal amount Q when drying at a constant rate of 0.8 (57 hours)
Graph showing the relationship between and moisture content. Figure 5 is a humidity diagram showing the relationship between temperature and absolute humidity of hot air and exhaust air. Agent Tetsube Maki (and 2 others) Figure 1 Figure 2

Claims (1)

[Claims] Measure the amount of grain to be dried, calculate the standard water removal amount Q to keep the drying speed constant from the amount of grain, and calculate the actual water removal amount measured from the standard water removal amount Q and the temperature difference between the hot air and exhaust air of the dryer. A burner combustion control device for a grain dryer, characterized in that the drying speed is kept constant by comparing q and combusting the burner so that the two match.