CN106155123A - A kind of On-Line Control Method of sweat remaining sugar concentration - Google Patents

Abstract

Aiming at the problems such as large lag in online detection of residual sugar concentration in the fermentation process, the present invention expands the expert knowledge method, simulates the expert knowledge method by using a fuzzy control method, and proposes a real-time control method for sugar concentration. In this method, the concentration of residual sugar in the tank and its rate of change are taken as the input of fuzzy control, and the rate of sugar supplementation is taken as the output. By determining the input and output language variables of the model controller, the scope of domain and control method, quantification factor and proportional factor are determined. The input and output membership functions of the model controller, the fuzzy control rules and clear algorithm of the model controller are used to simulate the fuzzy control based on expert experience. In the online application, the computer controls the constant flow pump to extract the fermentation broth, dilutes it, and then controls the YSI2700 online analyzer for analysis, and then substitutes the hysteresis detection value into the designed fuzzy controller to obtain the compensation within the control period. sugar rate. This method is the optimization and universal expansion of the expert knowledge method, which can greatly improve the product quality and output of the fermentation process.

Description

An online control method of residual sugar concentration in fermentation process

technical field

The invention belongs to the field of application engineering, in particular to an on-line control method for residual sugar concentration in a fermentation process using a hysteresis detection value.

Background technique

In the fermentation process, sugar is usually used as a nutrient for bacterial growth, and its concentration directly determines the quality and yield of the product. If the sugar concentration is too low, the bacteria will be in a state of insufficient nutrition, and the growth will be slow; if the sugar concentration is too high, the growth of the bacteria will also be inhibited due to excess nutrition. Limited by the development of detection technology, the traditional method of off-line sampling and analysis is mostly used for the detection of sugar concentration at present, which has a long detection cycle and a long lag time. The residual sugar concentration control based on this detection technology is relatively extensive, and it is impossible to further realize the refined control of the fermentation process. Moreover, the traditional detection method involves manual participation, which is the bottleneck problem in realizing the comprehensive automation of the fermentation process. At present, pH-star and DO-star are often used as control methods for residual sugar concentration. According to the relationship between sugar consumption and pH and DO during the growth of fermentation broth, the current online pH and DO detection values are used to control the residual sugar concentration. , this method is an indirect control method, which is to control the accumulation of metabolic by-products at the expense of the growth rate of microorganisms, so that the microorganisms are in a state of lack of substrate for a long time, and due to the large fluctuations of pH and DO, it cannot reach a high bacterial growth rate. concentration. YSI2700 can detect the concentration of residual sugar online, which provides the possibility for real-time online control of residual sugar concentration. However, the detection range of YSI2700 is limited, and it is easily affected by external factors such as temperature, stirring, foam, etc., and the fermentation broth needs to be extracted for detection. However, the extraction process takes a long time, so there is a large lag in the detection value. Based on the detected hysteresis value, the present invention designs a fuzzy control strategy based on expert experience, which can be used in various fermentation processes and solves the shortcoming that the control of residual sugar concentration depends on expert experience.

Contents of the invention

The object of the present invention is to provide a kind of fuzzy control strategy in order to overcome the shortcomings such as relatively large hysteresis in the detection of residual sugar concentration in the existing fermentation process, and the control strategy based on expert experience relies on expert experience, narrow applicable range and difficult to popularize and apply. It is used to summarize expert experience and deduce it into a general formula expression, providing a new path for the control of residual sugar concentration in the fermentation process.

In view of the large lag in the detection of sugar concentration by the YSI2700 online sugar analyzer, fermentation experts judge the sugar consumption rate of bacteria in different growth stages based on experience, and thus propose a residual sugar concentration control strategy, which is based on expert experience control strategy. Aiming at the detection system, based on the hysteresis detection value of the YSI2700 instrument, the present invention summarizes and deduces the expert control experience through the fuzzy control algorithm, and proposes a fuzzy control strategy for the concentration of residual sugar in the fermentation process, so that the expert control experience can reduce the residual sugar concentration in the fermentation process. It has been widely promoted in the control of concentration.

To achieve the above object, the present invention comprises the following steps:

In order to realize the on-line detection of residual sugar by YSI2700, the computer is used as the core controller, and the auxiliary constant flow pump TBP1010 and TBP1002 are completed. The computer is connected with YSI2700 and the constant flow pump respectively through the serial port, and the communication is completed by the protocols that come with the YSI2700 and the constant flow pump. Using this detection system, first the computer controls the constant flow pump to extract the fermentation broth, and at the same time controls the constant flow pump to add water for dilution, and then controls the YSI2700 online sugar analyzer to detect the sugar concentration. The system is developed by VC, and has the functions of real-time data display, manual and automatic control of YSI2700 and constant flow pump, fuzzy control of sugar concentration displayed by historical data curve, etc.

The lag time of the detection is calculated according to the extraction rate of the fermentation broth, the length of the pipeline and the analysis time of the YSI2700.

The concentration of residual sugar in the tank and its rate of change are taken as the input of fuzzy control, and the rate of sugar supplementation is taken as the output. By determining the input and output language variables of the model controller, the range of domain and control method, quantitative factors and proportional factors are determined, and the model is controlled. The membership function of the input and output of the controller, the fuzzy control rules of the model controller, and the clear algorithm are used to simulate the fuzzy control based on expert experience, and adjust the fuzzy control parameters online to achieve the optimal residual sugar control effect;

The designed fuzzy control strategy is used in the fermentation process: firstly, the sugar concentration is analyzed through the detection system based on the YSI2700 online analyzer, and then the hysteresis detection value of the residual sugar concentration is substituted into the designed fuzzy controller to obtain the control The rate of glucose supplementation during the cycle.

Description of drawings

Figure 1 is a flowchart of sugar supplement control

Figure 2 (1) is a flow chart of residual sugar concentration control based on expert experience and knowledge method (the output detection value is less than the upper limit for the first time)

Figure 2 (2) is a flow chart of residual sugar concentration control based on expert experience and knowledge method (initial value of sugar supplementation rate)

Figure 2(3) is a flow chart of residual sugar concentration control based on expert experience and knowledge method (normal sugar supplementation)

Figure 3 (1) Flow chart of residual sugar concentration control based on fuzzy control algorithm (the output detection value is less than the upper limit for the first time)

Figure 3(2) Flow chart of residual sugar concentration control based on fuzzy control algorithm (initial value of sugar filling rate)

Figure 3 (3) Flow chart of residual sugar concentration control based on fuzzy control algorithm (normal sugar supplementation)

detailed description

Below in conjunction with accompanying drawing 1, the structure of the present invention will be further described.

As shown in Figure 1, the thick solid line is the pipeline, the thin solid line is the communication line, and the arrow indicates the transmission direction of the signal or liquid. The equipment involved in the present invention includes: constant flow pump 1 (TBP1010), constant flow pump 2 (TBP1002), online sugar concentration analyzer (YSI2700), fermenter, peristaltic pump, mixer (dilution), PC. The constant flow pump 1 extracts the reaction liquid from the fermentation tank through the pipeline, and the constant flow pump 2 is connected to pure water. The two liquids are fully mixed and diluted in the mixer according to a certain ratio, and sent to the online sugar concentration analyzer for online detection. At the same time, The liquid in the mixer overflows, and the detection value is sent to the PC through the communication line. After algorithm control, the opening of the peristaltic pump is adjusted to replenish sugar into the fermenter.

The residual sugar concentration control process of the expert experience knowledge method will be further explained in conjunction with Figure 2.

Set the flow rate of the constant flow pump and the sampling period of the online sugar analyzer, and run according to the following period: First, the system starts to run, and the initial value g=0, i=1 (g is used to judge whether the detection value Cn(i) is greater than The upper limit a, i represents the detection time). The function of the flow chart (1) is to output the moment g when the detection value is less than a for the first time. In the flow chart (2), when i<=g, Cn(i)>a always holds true, the sugar supplement rate is 0; once i>g occurs, the initial value of the sugar supplement rate F(i-1)=ΔF (ΔF is the fixed sugar supplement rate), end the process. Flowchart (3) shows the situation of normal sugar supplementation at time i>g. It can be clearly seen from the flow chart (3) that it is necessary to make logical judgments on the upper limit a, the expected value Cs, the lower limit b and the detected value Cn(i-1) at the previous moment, when F(i)=F( In the case of i-1)-ΔF, it is necessary to judge F(i) and 0, because the sugar supplement rate cannot be negative. In the case of the above-mentioned different logic judgments, the relative sugar supplement rate can be obtained, so that the value E(i) in the fermenter under different sugar supplement rates can be known, (E(i)=f[Fn(i)] , indicating the relationship between the sugar concentration in the fermenter and the rate of sugar supplementation), and finally judge whether the detection time i is greater than m (m represents the number of times to be detected), if less, the system will cycle at the next moment, otherwise, end the operation of the system .

The fuzzy control flow chart of residual sugar concentration will be further explained in conjunction with accompanying drawing 3.

Set the flow rate of the constant flow pump and the sampling cycle of the online sugar analyzer, and run according to the following cycle: First, the system starts to run, and the functions of the flow chart (1) and (2) are the same as those of the expert experience knowledge method, and will not be repeated , the only difference is that in the flow chart (2) when i>g occurs, the initial sugar supplement rate is different. In the flow chart (3), when the detection value Cn(i)>upper limit a, the sugar supplement rate is 0 (because the detection time of YSI2700 is short, the sugar concentration in the fermenter cannot be consumed instantly). And because the sugar supplement rate F(i) is related to the previous moment F(i-1), it must be counted, and n is used here to count (assuming that the detected value at time i is Cn(i)<a, and Cn(i-1)> a, F(i-1)=0, F(i-1) cannot be used to calculate F(i), and the value at the time of F(i-1-n) must be used for calculation to ensure that F(i- 1-n) > 0). In addition, in the case of the detection value Cn(i)<lower limit b, it is necessary to judge the detection value Cn(i-1) at the previous moment, and add the sugar supplement rate on the basis of the previous moment or the previous 1+n time. Upper ΔF (ΔF is consistent with the fixed sugar supplement rate of the expert experience method, of course, it can also be changed according to the on-site situation). When the detection value a<Cn(i)<b, the fuzzy processing is performed first, and then enters the fuzzy controller to output Δu (Δu is the sugar supplement rate value that needs to be changed). The internal rules of the fuzzy controller are summarizing the experience of experts It is formulated on the basis of the knowledge method, and finally it is also necessary to make a logical judgment on F(i) and 0, and the next operation steps are the same as the expert experience knowledge method.

Claims (4)

1. An online control system for residual sugar concentration in the fermentation process. The system consists of a computer, a residual sugar concentration detector YSI2700, and some auxiliary constant flow pumps. The computer, YSI2700 and the constant flow pump are connected by serial ports, and the control is by communication. The communication is completed by YSI2700’s own protocol and the constant flow pump’s own protocol. 2. Based on right 1, the control system software is developed by VC, which includes functions such as YSI2700, manual automatic control of constant flow pumps, field data display and storage, historical data curve display, and fuzzy control strategies. 3. Expert knowledge method control based on lagging sugar concentration detection value. The present invention aims at the problem of hysteresis in online sugar concentration detection during the fermentation process. Through a large number of fermentation production experiments, it is found that the expert knowledge method mentioned in the present invention can control the residual sugar within the range, and the output and quality of the product have been greatly improved. improvement. 4. The fuzzy control method based on the detection value of lagging sugar concentration. Based on the analysis of the expert knowledge method, the fuzzy control algorithm is used to simulate the expert knowledge method, and a general control strategy is proposed. In this strategy, the size of the control amount can be adjusted online by the detected value of the current sugar concentration.