JPS5934270B2 - Burner combustion control device in grain dryer - Google Patents

Description

Detailed Description of the Invention When grains are dried with hot air from a burner, if the hot air temperature is high and the drying time is too fast, the grains will crack, and conversely, if the hot air temperature is low and the drying time is slow, the dryer will dry. Conventionally, there have been methods that automatically control the flow rate of fuel sent to the burner to an optimal steady flow rate to efficiently dry grains with high quality.

In the conventional type, the initial flow rate of fuel is constant regardless of the size of the steady flow rate, so depending on the value of the steady flow rate, the difference between the initial flow rate and the steady flow rate may become too large, or conversely, the initial flow rate may exceed the steady flow rate. The drawback is that it takes a long time for the flow rate to stabilize to a steady state.

The present invention provides such a dryer in which the initial flow rate of the fuel is reduced by a predetermined amount from the steady flow rate so that the fuel flow rate approaches the steady flow rate in a short time.

To explain this based on the embodiment shown in the drawings, K is a grain dryer with a drying chamber 2 in which grains flow down to the left and right of 1 in a hot air chamber in the center, and a ventilation chamber outside. form 3.

The boundaries between the drying chamber 2, the hot air chamber 1, and the exhaust chamber 3 are partitioned with a perforated plate.

B is a burner connected to the hot air chamber 1, and the hot air is sucked by a suction fan F connected to the exhaust chamber 3.

The hot air passes from the hot air chamber 1 to the drying chamber 2 to dry the grains, and then is discharged from the exhaust chamber 3 to the outside of the machine.

A pump P that communicates with a fuel tank N is connected to a burner B via a solenoid valve (■).

M indicates a motor that drives a suction fan F, an elevator (not shown) for the dryer, and the like.

Grain sensor Q detects the amount of grain loaded into the machine (for example, a microswitch covered with a rubber membrane is installed in the grain storage chamber whose bottom connects to the drying chamber 2, and this is switched based on the weight of the grain. The amount of grains piled up inside the room is detected by measuring the height of the grains piled up inside the room.

), a temperature sensor T (for example, a thermocouple thermometer or a thermistor thermometer) that measures the outside air temperature, and a humidity sensor H (for example, a wet-and-dry bulb electric hygrometer) that measures the humidity of the outside air are connected to the input side of the calculator C, and the output side Connect the solenoid valve■ to.

Note that an A-D converter (not shown) is interposed between the sensors Q, T, and H, the input/output equipment of the valve (1), and the computer C.

Based on the data signals from sensors Q, T, and H, the amount of filling at that time, the temperature and humidity of the outside air, and the type of grain stored in the program circuit of computer C, its initial moisture content, and the internal circulation of grain are determined. The temperature of the hot air of the speed burner, the intake/exhaust air volume of the fan F, etc. are all recommended, and the optimal steady flow rate A of the fuel is set by the computer C.

Next, the initial flow rate a is determined to be a predetermined amount smaller than the steady flow rate A, and the solenoid valve (2) is opened in accordance with this value to send fuel to the burner B.

By the way, in general, the hot air temperature has not risen to the reference value in the initial stage of drying immediately after burner ignition, so the fuel flow rate is controlled to increase.

In the present invention, the fuel flow rate gradually shifts from the initial flow rate a to the steady flow rate A by automatic control, but conventionally, the initial flow rate a is constant regardless of the magnitude of the steady flow rate, so when the steady flow rate A is large, The difference from the initial flow rate a becomes large, and the rate of increase in flow rate cannot exceed a certain level due to flow resistance in the pipe, and it takes 5 to 8 minutes to reach a steady flow rate. (See the opening in Figure 2).

In contrast, in the present invention, the initial flow rate a is determined to be a predetermined amount smaller than the steady flow rate A, so even if the flow resistance, that is, the slope of the rise of the graph is the same as before, the steady flow rate can be reached in about 3 minutes shorter than before. (See Figure 2).

Here, how much the predetermined amount should be, that is, how much the initial flow rate a should be determined compared to the steady flow rate A, is determined by determining the flow rate during a transient process in which the fuel flow rate is increased in order to raise the hot air temperature of the burner B. The amount is determined so as not to exceed the steady flow rate A. Specifically, the initial flow rate a is preferably set to 70% to 80% of the steady flow rate A.

Even when the steady flow rate A is small, the fuel flow rate is generally controlled to increase in the early stage of drying as described above. , it decreases toward steady flow rate A, so it takes a long time to reach a steady state, and burner B
Since the flow rate of fuel is reduced at a time when combustion is unstable immediately after ignition, there is a drawback that the combustion state becomes even more unstable (see Figure 3).

In contrast, in the present invention, the initial flow rate a never becomes larger than the steady flow rate A, so even when the steady flow rate A is small, the flow rate increases gradually after ignition, resulting in stable combustion (see Figure 2). .

In short, in the present invention, since the initial fuel flow rate a is adjusted to be a predetermined amount lower than the steady flow rate A, the fuel can be quickly shifted to the steady flow rate after burner ignition, and the combustion at the initial stage of ignition is stabilized. will occur.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a grain dryer embodying the present invention, Fig. 2 is a graph showing changes in flow rate in the present invention, and Fig. 3
Please refer to the figure below, which is a graph showing the change in flow rate in the conventional example.
A indicates a case where the value of the steady flow rate A is large, and a indicates a case where the value of the steady flow rate A is small.

Claims (1)

[Claims] 1. In a grain dryer that automatically controls the steady flow rate of fuel to an optimum value based on outside air temperature, outside air humidity, charging amount, etc., an optimum steady flow rate setting means for setting the optimum steady flow rate of fuel, and the setting means an initial flow rate determining means for determining an initial flow rate that is a predetermined amount lower than the optimum steady flow rate set by the operator; and a flow rate control means for controlling the fuel supply flow rate to the burner based on each output signal from the optimum steady flow rate setting means and the initial flow rate determining means. A burner combustion control device comprising: