Rectification equipment and rectification control method
Technical Field
The invention relates to the food processing industry, in particular to a rectification device and a rectification control method.
Background
Alcohol is separated by partial condensation and vaporization for many times by utilizing the different volatility of the alcohol and impurities in the alcohol, and the alcohol rectification process is usually carried out in a rectification tower. At present, the alcohol rectification in China is mainly performed by hand. Because a certain proportion of energy consumption is used for rectification operation in the alcohol treatment process, the rectification operation can also influence the alcohol quality to a great extent. Therefore, the improvement of alcohol rectification can improve the automation control level, save energy, improve the product quality and reduce the cost.
In the rectification process, because the mass transfer and the heat transfer are carried out simultaneously, the rectification device tower is usually a multi-channel complex object with capacity and cross connection among each other, the control method of the existing stage is simple, and the control on the rectification effect is poor. Since the controlled and controlled quantities of the rectification operation are interrelated and coupled to each other, a change in one controlled quantity will cause control of the other controlled quantity. The control inaccuracy not only has poor effect on the target controlled quantity, but also affects the controlled quantity change of other control loops, thereby causing the system to work abnormally, seriously affecting the product quality and even causing serious production accidents.
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide a rectification device which can realize automatic production, detection and control and improve the product quality and the production efficiency.
The rectifying equipment comprises a rough distillation tower, a rectifying tower, a preheater, a condenser, a cooler, a valve and a detection device; the top of the coarse distillation tower is connected with the preheater through a pipeline, the bottom of the coarse distillation tower is provided with a discharge pipeline and a bottom valve, the top and the bottom of the coarse distillation tower are provided with pressure detection devices, and the top, the middle and the bottom of the coarse distillation tower are provided with temperature detection devices; the top of the rectifying tower is connected with a preheater, the rectifying tower, the preheater, the first condenser, the second condenser and the third condenser form an industrial alcohol loop through pipelines, a middle tower plate of the rectifying tower is connected with a cooler through a pipeline, and the bottom of the rectifying tower is provided with a discharge pipeline and a bottom heating steam valve; pressure detection devices are arranged at the top, the middle and the bottom of the rectifying tower, and temperature detection devices are arranged at the top, the middle and the bottom of the rectifying tower; the pressure detection device and the temperature detection device are electrically connected with the computer.
Furthermore, a connecting pipeline of the cooler and a middle tower plate of the rectifying tower is provided with a discharge valve of an alcohol finished product, the preheater is provided with a control valve, and the condenser is provided with a master control valve.
Furthermore, the lower part of the preheater is connected with the upper part of the first condenser 4, the lower part of the first condenser is connected with the upper part of the second condenser, and the lower parts of the preheater, the first condenser and the second condenser are also provided with supply pipelines which are connected with the upper pipeline of the rectifying tower.
Further, the lower part of the second condenser is also connected with a third condenser. The preheater is also provided with a feed valve, and the feed valve is provided with a discharge passage.
The invention also provides a rectification control method by using the rectification equipment, and the computer is provided with 6 control loops, a control valve of the preheater is controlled according to the temperature and the pressure value at the top of the rough distillation tower, a control valve of the preheater and a bottom valve of the rough distillation tower are controlled in a linkage way according to the temperature at the middle part of the rough distillation tower, a bottom valve of the rough distillation tower is controlled according to the temperature and the pressure value at the bottom of the rough distillation tower, a master control valve of the condenser and a middle alcohol finished product discharge valve are controlled in a linkage way according to the temperature and the pressure value at the top of the rectification tower, a master control valve of the condenser, a middle alcohol finished product discharge valve and a bottom heating steam valve of the rectification tower are controlled in a linkage way according to the temperature and the pressure value at the middle part of the rectification tower, and a bottom heating steam valve of the rectification tower is.
Further, the computer control method comprises the following steps: firstly, initializing a computer; setting an interrupt mode and an interrupt program, and receiving an interrupt action according to the program setting; setting a count value of a control point; collecting parameters of control points at regular intervals, and comparing and judging the collected parameters by a computer through an out-of-tolerance program; if the judgment shows that the valve is out of tolerance, controlling the opening of the valve; if not, directly executing the next display program; and repeatedly executing the control process, and dynamically adjusting the states of all the acquisition points.
Further, the plus 1-level out-of-tolerance is calculated when the set temperature exceeds 0 to + n ℃ of the allowable temperature or the pressure is 0 to + m MPa; exceeding the allowable lower limit temperature of-n-0 ℃ or the pressure of-m-0 Mpa, and calculating to be-1 grade out-of-tolerance, wherein n and m are any numerical values; the computer calculates the temperature and pressure out-of-tolerance, and can drive the corresponding original position to generate an upward or downward displacement according to each stage of out-of-tolerance, so as to change the size of the controlled valve.
Furthermore, when the control point parameters are linkage control of a plurality of valves, a valve with priority control and a matched control valve are set; the valve opening value of the valve which is preferentially controlled is the difference of the product of the valve opening which is calculated by the computer and is controlled in a matched mode and the relative influence coefficient, and the valve size is adjusted firstly.
Furthermore, the sampling method of the computer is set to take 0.5min as the sampling period of the control parameter, carry out the amplitude limiting filtering amount, adopt the median filtering processing again, repeat 5-10 times in this way, take the average value as the result of each sampling period.
The invention can realize the following beneficial technical effects:
1. the rectifying device adopts two-stage rectifying equipment of a rough distillation tower and a rectifying tower, and the computer adopts 8-point temperature acquisition and 5-point pressure acquisition and simultaneously controls the opening of 5 valves. The rectifying device has high automation level, the acquired data is comprehensive and accurate, the temperature and the pressure are analyzed and controlled in multiple dimensions, and the product quality and the production efficiency are improved.
2. The control system adopts multipoint temperature acquisition and multipoint pressure acquisition and adopts a control model of a plurality of groups of control loops. The valve control among the control loops adopts a priority mode, the influence coefficient among the valves is set, and the opening degree of the priority valve is set according to the coefficient. By adopting the precise control mode, the mutual influence among all control loops is reduced. Compared with a single control loop, the controlled quantity of each control loop achieves high precision, and the influence of single system control on the whole system is eliminated. And further, the purposes of accurate control, yield improvement and product quality optimization can be achieved.
3. The invention reduces the mutual influence between the controlled quantity and the controlled quantity of the rectification operation, establishes the correlated and mutually coupled quantitative model between the controlled quantities to form a control loop capable of quantitative processing, realizes the calculation of the controlled quantity according to a function method, and realizes the optimized and accurate control.
4. The invention adopts the method of sampling period average value, and carries out amplitude limiting filtering treatment and median filtering treatment, thereby improving the accuracy of sampling data and avoiding single sampling error.
Drawings
FIG. 1 is a structural view of a rectifying apparatus according to the present invention;
FIG. 2 is a control flow diagram of the rectification process of the present invention.
Detailed Description
The invention is further described in detail with reference to the drawings and the specific embodiments.
As shown in FIG. 1, the top of the crude distillation column 1 is connected to the top of the preheater 3 through a pipe, and the bottom thereof is provided with a bottom valve and a discharge pipe. The top and the bottom of the coarse distillation tower are provided with pressure detection devices which are electrically connected with a central control system, and the top, the middle and the bottom of the coarse distillation tower are provided with temperature detection devices which are electrically connected with the central control system. The top of the rectifying tower is connected with the top of the preheater 3, and the rectifying tower, the preheater, the first condenser 4, the second condenser 5 and the third condenser 6 form an industrial alcohol loop through pipelines. The lower part of the preheater is connected to the upper part of the first condenser 4, and the lower part of the first condenser 4 is connected to the upper part of the second condenser 5. The bottom of the preheater is also provided with a raw material feeding valve. The lower parts of the preheater, the first condenser 4 and the second condenser 5 are also provided with a supply pipeline which is connected with an upper pipeline of the rectifying tower. The lower part of the second condenser is also connected with a third condenser. The middle tower plate of the rectifying tower is connected with the cooler 7 through a pipeline, and a valve is arranged on the pipeline. The bottom of the rectifying tower is provided with a waste water discharge pipeline. The bottom of the rectifying tower is provided with a bottom heating steam valve. The top, the middle and the bottom of the rectifying tower are provided with pressure detection devices which are electrically connected with the central control system, and the top, the middle and the bottom of the rectifying tower are provided with temperature detection devices which are electrically connected with the central control system.
The specific process of alcohol rectification by using double-tower rectification comprises the following steps: the fermented mash exchanges heat with alcohol vapor at the top of the rectifying tower 2 through a preheater 3, is heated to a certain temperature, then enters the top of the rough distillation tower 1, and the bottom of the rough distillation tower is heated by steam. Alcohol vapor with a certain volume fraction enters the middle part of the rectifying tower 2 from the top of the crude distillation tower 1. The distiller's grains are discharged from the bottom of the coarse distillation tower 1. The bottom of the rectifying tower is directly heated by steam. The alcohol vapor passes through a mash preheater 3 and first, second and third condensers 4, 5 and 6 in sequence. The condensate in the preheater 3 and the first and second condensers 4, 5 is all returned to the top of the rectifying tower 2 as reflux. The condensate in the third condenser 6 is taken out as industrial alcohol and the non-condensable gases are discharged to the atmosphere. And taking out the finished product alcohol from the liquid phase on the 4 th to 6 th tower plates at the top of the rectifying tower 2, and entering a wine storage through a cooler 7 and a wine detector. The wastewater is discharged from the bottom of the rectifying tower 2. And taking out the fusel oil from the liquid phase of the 2 nd to 4 th plates above the feeding layer and separating.
In the control process of the rectification process, the temperature acquisition method of the computer is 8-point temperature acquisition, and the temperature acquisition points comprise the bottom temperature, the middle temperature and the top temperature of the coarse distillation tower 1, the bottom temperature, the middle temperature and the top temperature of the rectification tower, the liquid temperature of the preheater 3 and the condensate temperature of the first condenser 4. The pressure acquisition method of the computer is 5-point pressure acquisition, and the pressure acquisition points comprise the bottom pressure and the top pressure of the coarse distillation tower, the bottom pressure, the middle pressure and the top pressure of the rectification tower. The number of the control loops is 6, namely the control valves of the preheater, the bottom valve of the coarse distillation tower, the bottom heating steam valve of the rectification tower, the discharge valve of the alcohol finished product and the opening degree of a master control valve of the cooling water flow of a condenser on the top of the rectification tower are respectively controlled according to the temperature and the pressure value on the top of the coarse distillation tower, the temperature in the middle of the coarse distillation tower, the temperature and the pressure value on the top of the rectification tower, the temperature and the pressure value in the middle of the rectification tower and the bottom of the rectification tower.
And the computer analyzes and judges the acquired information, and controls the opening of a bottom valve of the coarse distillation tower, a bottom valve of the rectifying tower, an alcohol finished product discharge valve and a master control valve of the cooling water flow of a condenser at the top of the rectifying tower respectively or in linkage according to the processing result of the information. The temperature and the pressure value at the top of the crude distillation tower are adjusted by controlling the flow of the liquid entering the crude distillation tower from the preheater, so that the temperature at the top of the crude distillation tower and the pressure value corresponding to the temperature value are controlled within a certain range, and the alcohol vapor with a certain volume fraction is ensured to enter the middle part of the rectifying tower. The temperature of the middle part of the rough distillation tower is controlled within a certain range by controlling the master control valve of the condenser and the bottom valve of the rough distillation tower in a linkage manner, preferentially adopting the control bottom valve and matching with the opening degree of the master control valve of the condenser. The bottom temperature of the crude distillation tower and the pressure value corresponding to the bottom temperature are in a certain range by controlling a bottom valve of the crude distillation tower. The top of the rectifying tower is in linkage control over the temperature at the top of the rectifying tower and the pressure value corresponding to the temperature at the top of the rectifying tower through a master control valve for controlling the condenser and an alcohol finished product discharge valve in the middle, and the master control valve for controlling the condenser is preferentially adopted to control the temperature at the top of the rectifying tower in cooperation with the alcohol finished product discharge valve. The middle part of the rectifying tower controls the middle temperature of the rectifying tower and the pressure value corresponding to the middle temperature through a master control valve for controlling the condenser, a middle alcohol finished product discharge valve and a bottom valve, and the middle alcohol finished product discharge valve is preferentially adopted to control the temperature in the rectifying tower by matching with the master control valve of the bottom valve and the condenser. The pressure and temperature value at the bottom of the rectifying tower are controlled by controlling the bottom valve at the bottom of the rectifying tower. The rectifying tower and the crude distillation tower control the tower bottom pressure through the steam quantity so as to ensure the heat required by the tower operation. In addition, the temperature of the condenser is controlled by adjusting the amount of cooling water in the overhead condenser. When the condensation temperature is controlled to be higher, the quality of the finished product alcohol can be improved, and the industrial alcohol content can be increased.
The upper and lower limits of the control point temperature and pressure are stored in the memory of the computer. When the computer works, the controlled parameter values of the control points are acquired in time-sharing and real-time manner and are compared and judged with the process parameters preset in the memory. If the out-of-tolerance occurs, the computer processes the classified out-of-tolerance according to the magnitude grade and the positive and negative of the out-of-tolerance to obtain the control quantity, namely the displacement quantity of the corresponding controller; the computer sends the control quantity to the actuating mechanism through the output channel, and the actuating mechanism controls the size of the corresponding feeding valve, steam valve or cooling water valve, adjusts the temperature or pressure in real time, and enables the temperature or pressure to be restored to a safe range, thereby realizing automatic control of the production process.
The control method of the computer is shown in fig. 2. Firstly, initializing a computer; setting an interrupt mode and an interrupt program, and receiving an interrupt action according to the program setting; setting a count value of a control point, wherein the count value is a certain set range, and the range is set by a technician according to actual process requirements; collecting parameters of control points at regular intervals, and comparing and judging the collected parameters by a computer, wherein the processing method can be a centering value filtering subprogram; if the judgment shows that the valve is out of tolerance, controlling the opening of the valve; if not, directly executing the next display program; and repeatedly executing the control process, and dynamically adjusting the states of all the acquisition points. In the out-of-tolerance grading treatment method adopted in the process, the computer sets plus 1-level out-of-tolerance every time the temperature exceeds the allowable temperature of 0 to plus 0.5 ℃ or the pressure of 0 to plus 0.05MPa according to the process requirements. The temperature exceeding the allowable lower limit is-0.5-0 ℃ or-0.05-0 MPa, and is set as-1-level out-of-tolerance. The computer system presets the out-of-tolerance grade, and after the collected several libraries are processed by program operation, it can produce output signal, so that every grade of out-of-tolerance can drive the correspondent original position to produce an upward or downward displacement to change the size of controlled parameter. Specifically, the allowable temperature range of the top of the coarse distillation tower is set to be 92-95 ℃, if the temperature of the control point is 90.5 ℃ at a certain sampling moment, the computer carries out-of-tolerance grading processing on the acquired information, and the temperature value is judged to be-3-grade out-of-tolerance; meanwhile, the pressure value of the control point is 0.08MPa, the calculation set carries out super-error grading processing on the pressure value, and the pressure value is judged to be + 1-grade super-error; and (3) analyzing the pressure value and the temperature value, and reducing the opening of a control valve of the preheater by calculating the control quantity to be two-stage displacement for driving downwards so that the temperature of the coarse distillation tower is quickly increased and the out-of-tolerance is reduced. Sampling temperature information at regular intervals, supposing that the temperature sampled at the top of the tower at a certain moment is 91.7 ℃, carrying out super-differential stage processing on the acquired information by a computer, judging that the temperature value is-1-stage super-differential, judging that the pressure value is not super-differential if the pressure value at a control point is 0Mpa, driving a first-stage displacement upwards at the moment, increasing the opening degree of a control valve of a preheater by one displacement, and enabling the temperature at the top of the coarse distillation tower to still continuously rise, wherein the temperature rising speed is slower than that before. The computer still samples the temperature information at regular intervals, supposing that the temperature sampled at the top of the tower at a certain moment is 92.1 ℃, and the pressure value at the point is 0Mpa, the computer carries out super-difference grading processing on the acquired information, the super-difference enters an allowable range, the super-difference is zero, at the moment, the first-stage displacement is driven upwards, and the normal position is recovered.
For the operation method of linkage control, for example, the allowable temperature range of the middle part of the coarse distillation tower is set to be 97-103 ℃, if the temperature of a control point at a certain sampling moment is 96 ℃, the computer performs out-of-tolerance grading processing on the acquired information, and the temperature value is judged to be-2-grade out-of-tolerance; the computer obtains the control quantity as two-stage displacement quantity of downward driving; at the moment, the control bottom valve and the pre-heater control valve need to be controlled in an interlocking manner, at the moment, the opening degree of the pre-heater control valve is kept to be determined by parameters at the top of the rough distillation tower, the opening degree of the pre-heater control valve at the moment is kept, and the opening degree of the bottom valve is adjusted on the basis of the opening degree. In combination with the above, at this time, the opening degree of the preheater control valve to the top of the crude distillation column is reduced by two opening degrees, and at this time, the opening degree of the preheater control valve to the top of the crude distillation column is (-2) × K (K is a relative influence coefficient), and the opening degree value to be adjusted by the bottom valve is further calculated and controlled.
The sampling method in this embodiment is set to take 0.5min as the sampling period of the control parameter. And in order to improve the reliability of the sampling data, firstly carrying out amplitude limiting filtering treatment, then adopting median filtering treatment, sampling the same control point once every 0.5min, sending the sampling into a memory after A/D conversion, repeating the sampling for 5-10 times, and taking the average value of the sampling as the result of each sampling period.
The present invention is not limited to the above embodiments, and various other modifications, substitutions and alterations can be made without departing from the basic technical concept of the present invention by the common technical knowledge and conventional means in the field according to the above content of the present invention.