Summary: for the seasoned Laver production oven dry and wet temperature measurement and control problems, developed with single-chip at the core of smart dry and wet temperature control device for dry and wet temperature automatic control.
Highlighted control system consisting of hardware and software design, gives the system structure principle diagram.1 Introduction
Laver, also known as seaweed, is delicious nutritious edible seaweed, a natural green health food.
Seaweed production process mainly consists of three stages: the algae production, processing and secondary processing (i.e., seasoned seaweed processing). Seasoned seaweed processing core is the time for processing into dried laver can directly edible seaweed foodstuffs. Therefore, the oven of dry and wet temperature control is critical.Oven baked before and after the baking of two parts, the main front Grill is a process of dry seaweed baked, grilled aims after removal of the surface with water after the laver, porphyra resistant storage.
After the baking of technological requirements are based on the Laver of varieties to identify and control heating, insulation of wet and dry temperature (dry temperature is the temperature of air in the oven; wet temperature refers to the Laver in the oven with the temperature of the water after seasoning). The oven, the author uses quartz electric heating tube, in each root electric heating tube with stainless steel reflector, to ensure that the oven temperature field of uniform, avoid the Laver is not baked or roasted. In order to achieve the purpose of the desiccant, in each section of the oven on a row of wet chimney, throttle control row of wet size and close back the throttle (for row of wet, wet temperature control), into the throttle (control dry temperature). Due to the influence of Laver in baking in the oven in dry and wet temperature factors are, and random changes, you cannot establish a mathematical model to the conventional manual methods to achieve control objectives for the development of a seasoned Laver intelligent temperature control device for dry and wet. Basic realization of the seasoned Laver in wet and dry curing process of automatic control of temperature, baking process may randomly change, good promotional value.2 design
Practice shows that in the Laver baking process, no matter what species of seaweed, its temperature of heating rate to l ° c/30 min to best, and insulation of temperature and time according to the specific situation of the Laver.
If we can control the oven in dry and wet curing temperature in its ideal temperature of l ℃ baking quality is guaranteed. In accordance with the requirements, the Laver baking warming period settings for its heating rate l ° c/30 min, in order to adapt to different Laver of baking, set the ideal dry temperature curve as shown in Figure 1, by artificial press will the temperature set at 37 ° c ~ 70 ° c range internal control temperature stall is set to 6 stalls when initial set as ① stalls, roast from up to 37 ° c temperature of the heating rate of 1 ° c/30 min, and at any time of the ideal temperature determines the temperature rose to 37 ° c, and automatically enter the insulation control status, holding time to set the next stall; if the second set to ④ stalls, from 37 ° c ~ 48 ° c to 1 ° c warming up/30min 48 ° c and automatically enter the thermal insulation, other stalls, and so on. When used after power outage again calls, represented by the current actual temperature in the oven to the set temperature according to the above rule of stalls.
Control of humidity and temperature is an important part of baking quality, in order to adapt to the different varieties of seaweed, in 37 ℃ ~ 42 ° c temperature range control temperature stall is set to 6 stalls, humidity and temperature controlled zones curve as shown in Figure 2.
Stalls set and control the regularity and wet and dry.
3 system architecture
Control system hardware in part by the host, sensors, and implementation.
Hardware structure as shown in Figure 3. Control device accuracy requirements for level, under the control of 0.5 functional needs, the system selects the AT89C52 as CPU. AT89C52 is a low-power, high-performance on-chip programmable/8 KB quick erase read only memory for 8-bit CMOS microcontroller, and instruction system and 80C51 pin-compatible, use the high-density, non-volatile storage technology manufacturing, memory write/erase cycles 1000 times. A/D converter to choose United States TI company TLC1549 CMOS 10-bit A/D converter, the device resolution of 8-bit, with a total of non-alignment for l LSB, output level and TTL-compatible, single power supply + 5 V power supply, the analog input range is from 0V to 5 V.
This system has 3 output channels, 1 x alarm circuit, using buzzer alarm; 2 driver circuit control electric actuators and reverse.
In order to improve the system anti-interference ability, drive circuit adopts AC solid state relay. Temperature setting uses the BCD code stalls dial, use P1.O ~ P1.3 as numerical input, easy to operate. Temperature display with LCD display. In order to no longer extended parallel interface, use the serial port of the shift register functionality, extended three static display LCD interface circuit. P1.7 as output control when P1.7 = 1 allows the serial port output data to the shift register, otherwise, the display does not change.
According to the measurement and control precision requirements, the system selects PtlO thermal resistance as a temperature sensor.
Ptl0 measuring range O ¡æ ~ 100 ¡æ, high accuracy, linearity, sensitivity, high performance and affordable and can meet the technical requirements of the system.
In order to raise the temperature measurement accuracy in the design of the hardware, take measures in three areas:
(1) the measurement sensor connection using a new three-wire system, compensation error by wire;
(2) choose 0P07 as operation amplifier;
(3) measuring circuit adopts constant current power supply.
Implementation of part consists of electric actuators, into the throttle and the back door. Two electric actuators areDriving into the door, back door, the oven in dry and wet temperature adjustment. Electric actuator of speed is very low (90/90 s), to reverse and to be able to stop at any angle, the maximum angle is 90, its output can be directly connected to the ventilation shaft, convenient installation.4 system software design
System software is mainly composed of temperature detection module, temperature display modules, temperature setting module and temperature control modules.
System master and master the program shown in Figure 4 and Figure 5.
Temperature detection program function is continuous 7 times A/D conversion, the conversion results are saved in the beginning of the session 3BH, then digitally filtering, the end value stored in 33H unit.
A/d with query. Temperature setting program realization of the set temperature insulation and ideal temperature at any time. Such as the set temperature is at any time To that ideal temperature T01. For dry and warm, if first is set to ① stalls, if the second set to ② stalls, ② stalls set to the current time is, t = 40 ° c, To present the ideal temperature of 37 ° c + T0l = t/l800 ℃. Insulation control program flow shown in Figure 6.
Temperature control module to achieve on firing process dry and wet temperature control and overrun alarm.
Temperature of the subject into the throttle (dry temperature), back door (wet temperature) open angle control, due to the impact of changes in the factors within the oven temperature and temperature reaction of complexity to the lag, the system uses an intelligent program design, the computer automatically records latency ¡÷ t so section by entering the holding period of warming up before the actuator t time start ahead of △ action to ensure that the temperature overshoot does not exceed To0.5 ° c, thereby ensuring the control precision: 1 ¡æ £». Heating control program flow as shown in Figure 7, electric actuators for each action 5 s, throttle every time on or off automatic 5 and stop in the ideal location to minimize the internal temperature of the oven. When automatic control failure, the system alarm.
5. concluding remarks
Based on these designs, the author has developed the seasoned Laver dry temperature control device and Jiangsu Lianyungang hengfu food co., Ltd seasoned seaweed processing operation test, running well.
At the same time, the increase in the hardware manual/automatic conversion feature, the software has added a antijamming on measures to enable the device work more reliable and stable. Good promotional value.
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