CN105941616A - Vacuum grain dryer and drying method - Google Patents

Abstract

The invention discloses a vacuum grain dryer and a drying method, comprising a drying chamber, the inner space of which is used for drying grain; Dry hot air; a vacuum machine, which is connected to the other side of the drying bin, is used to adjust the vacuum degree in the drying bin; wherein, when the vacuum machine is turned on, the drying bin and the hot air blower are turned off until the hollowness in the drying bin Reach the lower limit; after a period of time, turn off the vacuum machine and drying chamber, turn on the hot air blower, and when the vacuum reaches the upper limit, turn on the vacuum machine to complete a drying cycle. Under the condition that the energy consumption of the vacuum grain dryer of the present invention is basically the same, the drying speed can be increased by an average of 30% compared with the existing dryer.

Description

A kind of vacuum grain dryer and drying method

technical field

The invention relates to the field of grain drying. More specifically, the present invention relates to a vacuum grain dryer and a drying method.

Background technique

Drying after grain harvest is an important link in the process of grain processing. The existing drying equipment has low drying efficiency and slow drying speed. Every year, a large amount of grains become mildewed because they cannot be dried in time and quickly after harvesting, especially in the rainy season after the harvest of summer grains in southern my country. If they cannot be dried in time, it will cause great economic losses to farmers and grain processing enterprises.

Contents of the invention

The object of the present invention is to provide a grain dryer. A hot air blower is used to input hot air into the drying bin, and a vacuum machine is used to evacuate the drying bin so that the drying bin can be dried under vacuum to improve the drying efficiency.

Another object of the present invention is to provide a grain dryer, which adopts a control module to adjust the air volume of the hot air blower and the vacuum machine, so as to improve the drying efficiency.

Another object of the present invention is to provide a drying method for a grain dryer, which adopts a circulation drying method for drying and avoids over-drying.

Another object of the present invention is to provide a drying method for a grain dryer, which uses a fuzzy controller to adjust the process coefficients such as the vacuum drying time, the upper limit and the lower limit of the vacuum degree in the cyclic drying process, and improves the drying efficiency. Dry control precision to avoid over-drying.

In order to achieve these objects and other advantages according to the present invention, a vacuum grain dryer is provided, comprising:

Drying bin, the space in which is used for drying grain;

A hot air fan, which is connected to one side of the drying bin, is used to provide drying hot air to the drying bin;

A vacuum machine, which is connected to the other side of the drying chamber, is used to adjust the vacuum degree in the drying chamber;

Among them, when the vacuum machine is turned on, turn off the drying chamber and the hot air blower until the hollowness in the drying chamber reaches the lower limit; after a period of time, turn off the vacuum machine and the drying chamber, turn on the hot air blower, When the value is reached, turn on the vacuum machine to complete a drying cycle.

Preferably, the drying bin also includes:

The feed port is connected to the grain feed conveyor, and the feed port is used to introduce grain to the drying bin;

The discharge port is connected to the grain discharge conveyor, and the discharge port is used to discharge the grain in the drying bin.

Preferably, the drying bin also includes:

A vacuum pipeline, one end of which is fixed on the drying bin, and the other end is connected to the vacuum machine;

One end of the hot air pipeline is fixed on the drying bin, and the other end is connected with the hot air blower.

Preferably, it also includes:

The first temperature and humidity sensor, which is installed on the vacuum pipeline, is used to detect the temperature and humidity of the drying medium discharged from the drying chamber;

The second temperature and humidity sensor, which is installed in the hot air duct, is used to detect the temperature and humidity of the drying medium entering the drying chamber;

A moisture detector, which is connected to the drying bin, is used to detect the moisture value of the grain in the drying bin.

Preferably, it also includes:

The control module is connected to the drying chamber, the hot air blower, the vacuum machine, the first temperature and humidity sensor, the second temperature and humidity sensor and the moisture detector, and the control module receives the first temperature and humidity sensor, the second temperature and humidity sensor and the moisture detector The data of the instrument is processed and processed, and the air volume of the hot air blower and vacuum machine is adjusted.

The purpose of the present invention is also achieved by a drying method of a vacuum grain dryer, comprising the following steps:

Step 1. Turn off the drying chamber and the hot air blower, turn on the vacuum machine to vacuum until the vacuum degree in the drying chamber reaches the lower limit Wherein, the first temperature and humidity sensor detects the temperature T ₁ ′ and humidity H ₁ ′ of the drying medium discharged from the drying chamber;

Step 2. After _t1 time of vacuum drying, close the vacuum machine and the drying chamber, and turn on the hot air blower to make the vacuum degree in the drying chamber reach the upper limit value P ¹ _max , wherein, during the vacuum drying process, the second The temperature and humidity sensor detects the temperature T ₁ and humidity H ₁ of the drying medium entering the drying bin, and the moisture detector detects the moisture value W ₁ of the grain in the drying bin, and a drying cycle process is completed at this time;

Step 3: Stop drying when the moisture value W _i detected by the moisture detector is equal to the target moisture value during the i-th drying process.

Preferably, it also includes:

The fuzzy controller in the control module collects the grain moisture value W _i and the ideal grain moisture value of the i-th drying process

Enter ideal grain moisture value and the deviation e and the deviation change rate ec of the grain moisture value W _i , the deviation and the deviation change rate are divided into 7 grades in the fuzzy controller;

Output the additional upper limit value of the vacuum degree of the i+1th drying process Additional lower limit And the constant time Δt _i+1 of the additional vacuum degree, the output is divided into 7 levels;

The fuzzy sets of input and output are {NB, NM, NS, 0, PS, PM, PB}.

Preferably, the fuzzy control rules are:

When the ideal grain moisture value The deviation e from grain moisture value W _t1 is less than zero, the constant time Δt _i+1 of the additional vacuum degree is not greater than zero, and the additional upper limit of the vacuum degree Negative, additional lower limit value positive;

When the ideal grain moisture value The deviation e from grain moisture value W _t1 is greater than zero, the constant time Δt _i+1 of the additional vacuum degree is not less than zero, and the additional upper limit of the vacuum degree Positive, additional lower limit value is negative.

Preferably, the fuzzy universe of the deviation e and the deviation change rate ec is [-4,4], which is [-9,9], and the additional upper limit of the output vacuum degree The domain of discourse is [-20,20], and the additional lower limit value The domain of discourse is [-20,20] and the domain of discourse of the additional vacuum constant time Δt _i+1 is [-3,3].

Preferably, the additional upper limit of input deviation e and deviation change rate ec, output vacuum degree in the fuzzy controller Additional lower limit And the constant time Δt _i+1 of the additional vacuum degree adopts the triangular membership function.

The present invention at least includes the following beneficial effects: 1. Under the condition that the energy consumption of the vacuum grain dryer of the present invention is basically the same, the drying speed can be increased by an average of 30% compared with the existing dryer; 2. The drying process of the present invention Methods Fuzzy control was adopted to improve the precision of drying control and prevent the energy consumption problems caused by too fast drying and too slow drying.

Other advantages, objectives and features of the present invention will partly be embodied through the following descriptions, and partly will be understood by those skilled in the art through the study and practice of the present invention.

Description of drawings

Fig. 1 is a schematic structural view of the vacuum grain dryer of the present invention.

Fig. 2 is a schematic diagram of connection of the control modules of the vacuum grain dryer of the present invention.

Figure 3 is the ideal grain moisture value The triangular membership function diagram of the deviation e of grain moisture value W _i .

Figure 4 is the ideal grain moisture value The triangular membership function diagram of the deviation change rate ec of grain moisture value W _i .

Figure 5 is the additional upper limit of vacuum The triangular membership function diagram of .

Figure 6 is the additional lower limit of vacuum The triangular membership function diagram of .

Fig. 7 is a triangular membership function graph of the constant time Δt _i+1 of the additional vacuum degree.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings, so that those skilled in the art can implement it with reference to the description.

It should be understood that terms such as "having", "comprising" and "including" as used herein do not entail the presence or addition of one or more other elements or combinations thereof.

Figure 1-2 shows an implementation form according to the present invention, a vacuum grain dryer includes a drying bin 110, a hot air blower 120 and a vacuum machine 130, as shown in Figure 1, the drying bin 110 is a tower The lower end of the drying bin is off the ground and is fixed on the ground through brackets; wherein, the drying bin 110 can also be designed in the form of a rectangular, pointed top-shaped drying bin. The interior of the drying bin 110 is hollow, and the interior space is used for placing grain and performing drying operations. The drying bin 110 comprises: a feed port 111, a discharge port 112, a vacuum duct 113 and a hot air duct 114, wherein the feed port 111 is arranged on the top of the drying bin 110, and it is connected to a grain conveyor for feeding to the drying bin. Enter the grain to be dried in the dry warehouse 110 . The discharge port 112 is arranged at the bottom of the drying bin 110 and is connected to a grain discharge conveyor for discharging the dried grain in the drying bin 110 . The vacuum pipeline 113 is arranged on one side of the drying bin 110 and is close to the feed port 111, and the other end of the vacuum pipeline 113 is connected to the vacuum machine 130; The material opening 112, the other end of the hot air duct 114 is connected to the hot air blower 120. There is a heating wire inside the hot air blower 120, and the drying medium enters from the air inlet of the hot air blower 120, and is preheated to the drying temperature inside, and is pumped into the drying chamber 110 through the hot air pipeline 114 by the internal gas pump, and the heat is The fan 120 is used for providing hot drying air to the drying chamber 110 . The vacuum machine 130 is a vacuum pump, which is connected to the vacuum pipeline 113 of the drying chamber 110, and the vacuum degree in the drying chamber 110 reaches a set value through its vacuuming operation. Wherein, when the vacuum machine 130 is turned on, the drying chamber 110 and the hot air blower 120 are closed, and the vacuum machine 130 draws the hot air from the upper end of the drying chamber 110 until the hollowness in the drying chamber 110 reaches the lower limit value; the vacuum drying operation is carried out , so that the grain is in full contact with the hot air and conducts mass and heat transfer, so that the moisture in the grain enters the hot air and increases the temperature of the grain to facilitate the diffusion of water to the outside. After a period of vacuum drying, close the vacuum machine 130 and the drying bin 110, turn on the hot air blower 120 to make the hot air enter the drying chamber 110 from the bottom, make the vacuum degree reach the upper limit, and then turn on the vacuum machine, and complete a drying cycle process at this time.

In another embodiment, as shown in FIG. 2 , the drying device further includes a sensor group, and the sensor group includes a first temperature and humidity sensor, a second temperature and humidity sensor, and a moisture detector. The first temperature and humidity sensor is installed in the vacuum pipeline 113 to detect the temperature and humidity of the drying medium discharged from the drying chamber 110. The first temperature and humidity sensor is a high-precision measurement module, which has the advantages of small size and accurate measurement. . The second temperature and humidity sensor is installed in the hot air pipeline 114, and is used to detect the temperature and humidity of the drying medium entering the drying bin 110; the moisture detector is connected to the drying bin 110, and the drying bin 110 discharges grain into Moisture detector, the moisture detector uses the capacitive sensing probe inside to detect the grain moisture signal, and converts it into moisture content after being processed by the amplification circuit, and then returns the detected grain to the drying bin 110 .

In another embodiment, as shown in FIG. 2, the dryer further includes: a control module connected to the drying chamber 110, the hot air blower 120, the vacuum machine 130 and the sensor group, and the control module receives the first temperature and humidity sensor , The data of the second temperature and humidity sensor and the moisture detector are processed, and the air volume of the hot air blower and the vacuum machine is adjusted.

The dryer shown in Figures 1 and 2 adopts the drying mode of grain going in and out at the top and hot air going in and out at the bottom. 110, turn on the vacuum machine 130, close the drying chamber 110 and the hot air blower 120, and the vacuum machine 130 will extract the hot air from the upper end of the drying chamber 110 until the hollowness in the drying chamber 110 reaches the lower limit; carry out vacuum drying operation, so that The grain is in full contact with the hot air for mass and heat transfer. After a period of time, turn off the vacuum machine 130 and the drying chamber 110, and turn on the hot air blower 120 to allow the hot air to enter the drying chamber 110 from the bottom to make the vacuum degree reach the upper limit. value, and then turn on the vacuum machine. At this time, a drying cycle process is completed. During the drying process, the first temperature and humidity sensor is used to detect the temperature and humidity of the drying medium discharged from the drying chamber 110, and the second temperature and humidity sensor detects the temperature and humidity of the drying medium that enters The temperature and humidity of the drying medium in the drying bin 110, the moisture detector detects the moisture content of the grain in the drying bin 110, and transmits the data to the control module, which adjusts the air volume of the hot air blower and vacuum machine to speed up the drying process , when the i-th drying process is carried out, it is detected that the moisture content of the grain in the drying bin 110 is equal to the set target moisture content, and the control module controls the dryer to stop the drying operation.

A drying method of a vacuum grain dryer, comprising:

The grain with mass M and moisture value _H0 is input into the dryer, and the target moisture value for drying is input to the control module.

Step 1. Turn off the drying chamber and the hot air blower, turn on the vacuum machine to vacuum until the vacuum degree in the drying chamber reaches the lower limit Among them, the first temperature and humidity sensor detects the temperature T ₁ ′ and humidity H ₁ ′ of the drying medium discharged from the drying chamber, and keeps the vacuum degree constant at the lower limit After _t1 time of vacuum drying, close the vacuum machine and the drying chamber, turn on the hot air blower to make the vacuum degree in the drying chamber reach the upper limit value P ¹ _max , wherein, during the vacuum drying process, the second temperature and humidity sensor Detect the temperature T ₁ and humidity H ₁ of the drying medium entering the drying bin, and the moisture detector detects the moisture value W ₁ of the grain in the drying bin. At this time, the first drying process is completed; at this time, the first drying process is completed. Ideal Grain Moisture Value for Process Compare with the moisture value W1 _of the grain detected by the moisture detector, if it is equal, the next drying will be carried out with the current process, if not, then the next drying process will be adjusted;

Step 2. Use a fuzzy controller to control the drying process during the drying cycle, and the fuzzy controller will set the ideal grain moisture value The deviation e and the deviation change rate ec of the grain moisture value W _i are input into the fuzzy controller, and the additional upper limit value of the vacuum degree of the i+1th drying process is output Additional lower limit and the constant time Δt _i+1 of the additional vacuum degree to adjust the next drying process.

The fuzzy controller adopts a layered control structure, including a signal processing layer and a decision-making control layer, specifically:

Signal processing layer:

In the i-th drying process, the fuzzy controller collects the grain moisture value W _i detected by the moisture detector, and calculates the ideal grain moisture value based on the material balance

${\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; W</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; G</span>}}{\frac{\mathrm{<span\; class="notranslate">\; G</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>}$

Among them, G is the absolute dry weight of the grain entering the drying bin, that is, the weight of the grain after removing all moisture, KG; Q _i is the amount of hot air entering the drying bin during the i-th drying process, kg/s; W _{i -1} is the moisture content of the grain after the i-1 drying process, %; t _i is the vacuum drying time of the i drying process, s; H _t ′ _i is the vacuum machine in the i drying process Humidity of the discharged drying medium, %; H _ti is the humidity of the drying medium that the hot air blower enters the drying chamber during the i-th drying process, %.

Decision control layer:

The fuzzy controller inputs the ideal grain moisture value of the ith drying process The deviation e and the deviation change rate ec of the grain moisture value W _i output the additional upper limit value of the vacuum degree of the i+1 drying process Additional lower limit and the constant time Δt _i+1 of the additional vacuum degree; when there is no control, the ideal grain moisture value The variation range of the deviation e from the grain moisture value W _i is [-4,4], the deviation change rate ec is [-9,9], and the quantization factor is set to 1, so its fuzzy domain is [-4, 4], [-9,9], the additional upper limit of the output vacuum The domain of discourse is [-20,20], and the additional lower limit value The domain of discourse is [-20,20] and the domain of discourse of the additional vacuum constant time Δt _i+1 is [-3,3]. In order to ensure the accuracy of the control, so that it can track the control well under various working conditions, according to trial and error, the input and output are finally divided into 7 levels, and the fuzzy sets are {NB, NM, NS, 0, PS, PM, PB}; the membership functions are triangular membership functions, as shown in Figure 3-7.

The selection experience of fuzzy control rules is:

When the ideal grain moisture value The deviation e from grain moisture value W _t1 is less than zero, the constant time Δt _i+1 of the additional vacuum degree is not greater than zero, and the additional upper limit of the vacuum degree Negative, additional lower limit value positive;

When the ideal grain moisture value The deviation e from grain moisture value W _t1 is greater than zero, the constant time Δt _i+1 of the additional vacuum degree is not less than zero, and the additional upper limit of the vacuum degree Positive, additional lower limit value is negative;

The fuzzy control rules for the constant time Δt _i+1 of the additional vacuum degree are shown in Table 1, and the additional upper limit of the vacuum degree The fuzzy control rules are shown in Table 2, and the additional lower limit of the vacuum degree The fuzzy control rules are shown in Table 3.

Table 1 Fuzzy control rules for constant time Δt _i+1 of additional vacuum degree

Table 2 Additional upper limit of vacuum degree fuzzy control rules

Table 3 Additional lower limit of vacuum degree fuzzy control rules

Step 3. The fuzzy controller outputs the constant time Δt _i+1 of the additional vacuum degree, and the additional upper limit of the vacuum degree Additional lower limit The process parameters for the control module to control the i+1th drying process are:

Vacuum constant time t _i+1 = t _i +Δt _i+1 ;

Upper limit of vacuum degree for:

Vacuum lower limit for:

The ideal grain moisture value for the i+1 drying The deviation e from the grain moisture value W _i+1 is reduced, so that the drying process can be controlled more precisely, and the energy consumption problem caused by the high degree of grain gelatinization caused by too fast drying and too slow drying can be prevented.

Step 4. When it is detected that the grain moisture value is equal to the set grain moisture value, the control module stops the drying operation.

Although embodiments of the present invention have been disclosed above, it is not limited to the applications set forth in the specification and examples. It can be fully applied to various fields suitable for the present invention. Additional modifications can readily be made by those skilled in the art. Therefore, the invention should not be limited to the specific details and examples shown and described herein, without departing from the general concept defined by the claims and their equivalents.

Claims (10)

1. A vacuum grain dryer, characterized in that it comprises: Drying bin, the space in which is used for drying grain; A hot air fan, which is connected to one side of the drying bin, is used to provide drying hot air to the drying bin; A vacuum machine, which is connected to the other side of the drying chamber, is used to adjust the vacuum degree in the drying chamber; Among them, when the vacuum machine is turned on, turn off the drying chamber and the hot air blower until the hollowness in the drying chamber reaches the lower limit; after a period of time, turn off the vacuum machine and the drying chamber, turn on the hot air blower, When the value is reached, turn on the vacuum machine to complete a drying cycle. 2. The vacuum grain dryer according to claim 1, wherein the drying bin further comprises: The feed port is connected to the grain feed conveyor, and the feed port is used to introduce grain to the drying bin; The discharge port is connected to the grain discharge conveyor, and the discharge port is used to discharge the grain in the drying bin. 3. The vacuum grain dryer according to claim 1 or 2, wherein the drying bin further comprises: A vacuum pipeline, one end of which is fixed on the drying bin, and the other end is connected to the vacuum machine; One end of the hot air pipeline is fixed on the drying bin, and the other end is connected with the hot air blower. 4. The vacuum grain dryer according to claim 3, further comprising: The first temperature and humidity sensor, which is installed on the vacuum pipeline, is used to detect the temperature and humidity of the drying medium discharged from the drying chamber; The second temperature and humidity sensor, which is installed in the hot air duct, is used to detect the temperature and humidity of the drying medium entering the drying chamber; A moisture detector, which is connected to the drying bin, is used to detect the moisture value of the grain in the drying bin. 5. The vacuum grain dryer according to claim 3, further comprising: The control module is connected to the drying chamber, the hot air blower, the vacuum machine, the first temperature and humidity sensor, the second temperature and humidity sensor and the moisture detector, and the control module receives the first temperature and humidity sensor, the second temperature and humidity sensor and the moisture detector The data of the instrument is processed and processed, and the air volume of the hot air blower and vacuum machine is adjusted. 6. A drying method for a vacuum grain dryer, comprising: Step 1. Turn off the drying chamber and the hot air blower, turn on the vacuum machine to vacuum until the vacuum degree in the drying chamber reaches the lower limit Wherein, the first temperature and humidity sensor detects the temperature T ₁ ' and humidity H' ₁ of the drying medium discharged from the drying bin; Step 2. After _t1 time of vacuum drying, close the vacuum machine and the drying chamber, and turn on the hot air blower to make the vacuum degree in the drying chamber reach the upper limit value P ¹ _max , wherein, during the vacuum drying process, the second The temperature and humidity sensor detects the temperature T ₁ and humidity H ₁ of the drying medium entering the drying bin, and the moisture detector detects the moisture value W ₁ of the grain in the drying bin, and a drying cycle process is completed at this time; Step 3: Stop drying when the moisture value W _i detected by the moisture detector is equal to the target moisture value during the i-th drying process. 7. The drying method of the vacuum grain dryer according to claim 6, further comprising: The fuzzy controller in the control module collects the grain moisture value W _i and the ideal grain moisture value of the i-th drying process Enter ideal grain moisture value and the deviation e and the deviation change rate ec of the grain moisture value W _i , the deviation and the deviation change rate are divided into 7 grades in the fuzzy controller; Output the additional upper limit value of the vacuum degree of the i+1th drying process Additional lower limit And the constant time Δt _i+1 of the additional vacuum degree, the output is divided into 7 levels; The fuzzy sets of input and output are {NB, NM, NS, 0, PS, PM, PB}. 8. The drying method of the vacuum grain dryer according to claim 7, wherein the fuzzy control rule is: When the ideal grain moisture value The deviation e from grain moisture value W _t1 is less than zero, the constant time Δt _i+1 of the additional vacuum degree is not greater than zero, and the additional upper limit of the vacuum degree Negative, additional lower limit value positive; When the ideal grain moisture value The deviation e from grain moisture value W _t1 is greater than zero, the constant time Δt _i+1 of the additional vacuum degree is not less than zero, and the additional upper limit of the vacuum degree Positive, additional lower limit value is negative. 9. The drying method of vacuum grain dryer according to claim 8, characterized in that, the fuzzy domain of the deviation e and the deviation change rate ec is [-4,4], which is [-9,9 ], the additional upper limit of the output vacuum The domain of discourse is [-20,20], and the additional lower limit value The domain of discourse is [-20,20] and the domain of discourse of the additional vacuum constant time Δt _i+1 is [-3,3]. 10. The drying method of vacuum grain dryer as claimed in claim 9, characterized in that, in the fuzzy controller, the input deviation e and the deviation change rate ec, the additional upper limit of the output vacuum degree Additional lower limit And the constant time Δt _i+1 of the additional vacuum degree adopts the triangular membership function.