JPS58214776A - Controller for combustion of burner in cereal 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 depending on the amount of grain, so there is a difference in the water removal ability of the hot air due to differences in outside air humidity, and there is a difference depending on 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 value of the moisture content of grain per unit time, if the moisture content at a certain time is a1 and the moisture content after a unit time is b, then the drying rate at that point P (%/hour ) is p = a - b (Equation 1) Now, when the drying rate is P, the mass of water evaporated from the grain per unit time, that is, the amount of water removed Q (Kg/hour), is the quality of the grain at a certain time tA1 If the mass of the grain after unit time is B, then Q = A - B (equation 2) By the way, since the mass of the grain excluding water does not change before and after drying, the following formula holds true.

b (Formula 3) %Formula% 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 (
37 hours), but hypothetically P = 0.
Assuming that 8, the amount of water removed Q that evaporates from the entire 1000 kg of grain every hour is determined from (Equation 4), A = 1000 kg
Therefore, when a=25c%), Q=11 (Kg/hour) a=
When 20 (%), Q = 10 (Kg/hour) a = 15
(%), Q = 9.3 < Kg/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.

From this, it is clear that even if the moisture content a is different, the value of Q is only slightly different to the extent that it can be ignored in practical terms. Even if the drying rate is increased, the drying rate P remains constant at approximately 6.8 (37 hours).

In this way, in general, if drying is performed with a constant water removal amount Q per unit time, the drying rate P will also be constant.

Therefore, by calculating in advance the amount of water removed Q that will give the optimum drying speed P, and controlling the combustion of the burner so that the actual amount of water removed q matches this, the drying speed can be maintained at the optimal value from beginning to end. No cracking of the body occurs.

Based on this knowledge, the present invention aims to make the drying rate P constant by making the actual water removal amount q match the preset water removal amount Q.

An embodiment of the present invention will be described based on the drawings. Reference numeral 1 denotes a storage chamber of a dryer, and a chevron plate 2 with an inverted V-shaped cross section is provided at the center of the bottom of the storage chamber 1. A perforated plate 4 is connected to both side edges of the chevron-shaped plate 2 and the lower edge of the guiding swash plate 3.30, and a drying chamber 5.5 is formed by a pair of opposing perforated plates 4.

The outlet at the lower end of the drying chamber 5.5 looks through the rotary pulp 6 into the gutter-like grain flow chamber 7, and the feed end of the grain feeding helix 8 suspended horizontally in the groove in the center is connected to the grain hoist 9. Connect to the bottom intake.

A grain feeding helix 10 is connected to the upper part of the grain elevating machine 9, and its terminal end is opened above a diffusion plate 11 suspended from the center of the ceiling plate of the storage chamber 1.

Then, the burner 12 and suction fan 13 are installed opposite to the front and back of the dryer, and the burner 12 is attached to the left and right drying chambers 5.
While looking into the hot air chamber 144C inside the fan 13
is connected to the outside of the drying chamber 5.5 and to the exhaust chamber 15 surrounded by the outer wall of the dryer. 16 is the room 12 of the hot air chamber 14
and a shielding board that closes off the opposite side.

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

At this time, the hot air from the burner 12 enters the drying chambers 5 on the left and right from the hot air chamber 14 in the center, dries the grains flowing down, and the exhausted air containing moisture passes through the fresh air chamber 15 and exits the drying chamber 5 on the left and right sides. Exhaust.

After drying, the grains flow into the grain chamber 7 through the rotation of the rotary valve 6.
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 amount of water removed q is the product of the absolute humidity difference between the hot air and the exhaust air and the air volume K (Kg) that passes through the drying chamber 5 during unit time. be equivalent to. 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 immersion degree of hot air)X O,00
１ Kazeyō ``(It becomes 65゜.

Therefore, when actually operating the dryer, the normal hot air temperature is between 40°C and 51J0C, and now the absolute humidity of the hot air is 4 to 8 (gKg), and the exhaust air temperature is 21 to 27°C. ℃, the absolute humidity at the exhaust air temperature at that time can be determined as shown in Table 1 according to the humidity air diagram in Figure 5.

Table 1 From this, it turns out that the value of k within that range is 0.42.

Therefore, from (75 formula) and (6 formula), q = (hot air temperature - exhaust air temperature) Xo, 42mXK (7
formula). Here, m is the efficiency obtained by subtracting the amount lost due to temperature rise of the dryer and 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 actual water removal amount q according to Equation 7).

On the other hand, the calculated water removal amount Q according to the total mass of grains is set by adjusting the variable resistance of the standard water removal amount setting circuit N.
The output side of the circuit E is connected to a comparator C, and the output side thereof is further connected to the fuel pulp V of the burner 12. Then, compare the actual amount of water removed q with the amount of water removed (η) above, which should serve as a reference, and if q is larger than Q, the valve V is closed, and if it is smaller, the pulp V is opened and the burner 12 is combusted. control automatically.

In this way, in the present invention, the amount of water removed Q that will give the optimum drying speed P is calculated in advance according to the amount of grains to be dried. Since the combustion is controlled, there is no difference in the drying speed P even if the outside temperature and grain type and quality are different, and the effect is that it can dry at a stable speed, prevent shell cracking, and dry to produce grains of good quality. will occur.

Furthermore, in the present invention, the actual amount of water removed q is determined from the temperature difference rather than the absolute humidity difference between the hot air and the exhaust air, so an expensive hygrometer is not necessary and high-precision measurement can be performed using an inexpensive temperature sensor.

[Brief explanation of drawings]

Figure M1 is a vertical front view of a grain dryer embodying the present invention, Figure 2 is a cross-sectional plan view thereof, Figure 3 is a block diagram of its control system, and Figure 4 is ioo. A graph showing the relationship between water removal amount Q and water content when Kg of grain is dried at a constant drying rate p = o, s (57 hours). Figure-5 is a humidity diagram showing the relationship between temperature and absolute humidity of hot air and exhaust air. Agent Tetsu Maki (2 idiots) Figure 1 Figure 2 Figure 3 Figure 4 Moisture content ('A)

Claims (1)

[Claims] The amount of water removed, Q, calculated according to the amount of grain to be dried, is compared with the amount of water removed, Q, measured from the temperature difference between the hot air and exhaust air of the dryer, and the burner is ignited so that the two match, keeping the drying speed constant. A combustion control device for a burner in a grain dryer, characterized in that: