Traditional Chinese medicine extraction process control system design and application

1 Introduction

Traditional production of a critical process of traditional Chinese medicine extraction, to ensure the quality of the extraction of substances, and to improve the efficiency of the extraction process and economics, for different herbs, choice and ensure proper extraction, strict and automatically follow the correct procedures for extraction of herbal extracts, is the traditional process of production and a vital link.

Our University and Tianjin Daming pharmaceutical equipment factory to build the "r" in traditional Chinese medicine equipment, the construction of the project, according to the process of actual demand, in the spirit of nature, reliability, relevance, complete natural medicine pilot production process each unit of computer process control system design and development, the successful implementation of a natural medicine pilot production process all important process parameters of your computer to automatically detect and control, including extraction unit for a variety of ways to extract the entire process computer control, thus contributing to the scientific research personnel in the future on natural medicine extraction and extraction equipment research provides a reliable and effective means. [1]

2 extraction of the main process flow and control requirements

2.1 extraction process control

(1) the feeding control

Extraction of crude into the tank by adding ingredients of 5-l0 times the solvent.

With level control method to control the amount of solvent joined, the flowchart shown in Figure 1.

Figure 1 level control flowchart

(2) dynamic extraction

Dynamic extraction is the core of traditional Chinese medicine extraction process, requiring control tank liquid temperature, the pressure to keep the tank to atmospheric pressure, and manages the liquid circulation channel electromagnetic valve and manual valves on, off and liquid circulation pump and heat pump starts and stops.

Extraction tank control charts as shown in Figure 2.

Figure 2 extraction tank control chart

Traditional Chinese medicine extraction process usually uses the solvent (solvents) with water or alcohol.

Extraction solvent, the demand for control. Water as a solvent, the valve to the extraction process always is opened, that is, the tank pressure is constant, only in the event of accidents (such as exhaust pathway jams), the alarm can be. Alcohol as solvent, venting valve should always be turned off, to maintain the tank pressure is constant, their regulation and water as solvent is different.

2.2 control parameters

Test parameter: extraction tank temperature, the pressure inside the tank extraction, extraction tank level, cooler cooling water inlet temperature and outlet temperature, heat pump of oil temperature and oil temperature, etc.

Control parameters: extraction tank temperature, pressure, feed extraction tank control, material control, circulation pump, heat pumps, self-priming and out pump start and stop control, etc.

2.3-controlled requirements

Under this item in process uncertainty characteristics, extract parts of automatic design requirements are limited and fixed equipment, pipelines, convenience and flexibility to implement different extraction mode of the whole process of automatic control, which can "extract" or "extracts"; either the "single tank extraction", or "double tank extraction"; can be either "cycle extraction", or "non-circular extraction."

Extraction tank with liquid rehydration, extraction tank heating and temperature, drug extraction, the cycle of extract, extract of the material, until the end of the extract or the entire process again to extract are reliable, automated complete.

Extract part of an automatic control circuit includes the extraction tank temperature automatic control; quantitative extraction tank and liquid automatic control; extraction tank discharge automatic control; Extractor, extract the tank's temperature automatic detection; extract the tank level automatic detection.

A number of herbal extraction, extraction temperature and cycle time is determined by the process. This programme uses the heat oil in a jacket of extraction tank heating, boiling pot of herbs, while circulating pump spray.

3 system features

In the system's overall design, selection and maintained, thus ensuring system synchronization using computer control system is technically advanced and with international standards.

In consideration of domestic and foreign-related systems such as: Honeywell control system, Yokogawa µ L X D C S and SIEMES control systems, the decision to select a SIEMENS control system-thus ensuring that the maturity of the system. Select the Siemens system another reason is the system easy to maintain, easy to scale. On the traditional production process, often occurring "foam liquid" is thrown away. Use of CTN-XM series dual-level automatic elimination of foam control unit, which according to the principle of resistance response in the foam probe electrodes with strong anti-fouling, serious pollution and scaling, still be able to detect the location of liquid to achieve reliable and effective elimination of bubbles, to control the "escape valve". [2]

4 the system's structure and configuration

This article adopts PROFIBUS-DP build Chinese medicine extraction process monitoring system of the underlying network.

New fieldbus control system broke through the DCS system communication from private network closure system to achieve the result of defects, based on closed, proprietary solutions into openness, standard-based solution, fieldbus standard there are dozens. Each bus standard has its own characteristics and specific application area displays its advantages. Process PROFIBUS as an international, open, not dependent on the device manufacturer's fieldbus standards as a fully integrated process and factory automation fieldbus solutions, has been widely used in process control and process industry. PROFIBUS with the physical layer of the OSI model, the data link layer. When the transmission speed of 12Mbps 9.6Kbps ~, the transmission distance can reach 100m. When the transmission rate is 1.5Mbps, the transmission distance can achieve 400m. PROFIBUS transmission medium can be twisted pair or fiber-optic cable. You can hook it up to 127 subweb. PROFIBUS using features a modular design, different applications using different module Design. The underlying system structure as shown in Figure 3. At the same level in the system is divided into two levels i.e. device control and monitoring layers.

Figure 3 PROFIBUS underlying network architecture

3.1 device control layer

The device control layer using Siemens PROFIBUS-DP various solenoid valves, pumps, motors, temperature sensors, pressure sensors, as well as ET200 sub-station etc functional unit connection.

Temperature sensor selection Pt1O0 platinum resistance temperature sensor output 4-20mA, strong anti-interference ability, easy-to-signal transmitter. Pressure sensor selection isolated sensor components and IC module technology production of high-temperature resistant to vapour pressure sensor, with linear, temperature drift is small, the time good stability.

It involves on-site equipment: water Extractor, alcohol extraction tank, tank, recycling solvent tanks, evaporating tank, distillation columns, filters, heaters, condensers, and so on.

Control the device of actuator with control switch valve, PID control valves, electromagnetic flow-meter and level meter, temperature transmitters, pressure transmitter, self-priming, a pump and heat pump, etc. The underlying hardware configuration: PLC Siemens S7-300 series PLC, CPU type, using CPU315-2DP ET200M module 6ES7 l53-2AA02 — 0XB0, power module 6ES7 307-1KA00-0AA0, 32 point 24V digital input module 6ES7 321 — 1BL00-0AA0, 16-point relay output module 6ES7 322 — 1HH00-0AA0, 8-channel analog input module 6ES7 331 — 7KF01 — 0AB0, 8-channel RTD input module 6ES7 331-7PF00-0AB0, 4-channel PID module 6ES7 355 — 0VH10-0AE0, etc.

In this system uses electric furnace for heating, furnace heating and insulation by resistance wire heating, cooling is relying on the natural environment of cooling, when the temperature once the overshoot was unable to use the control means that cooling with heat up one-way, non-linear, not even gain and delay, and other characteristics, the mathematical model is difficult to establish.

Because the system has a large delay and warming of unidirectional characteristics, using normal PID control methods, it is easy to cause integral saturated, it is difficult to be satisfied with the results of the control. To this end, the first step response curve method furnace of mathematical model for its approximate amplification coefficient K, time constant T and latency r; and then use the Ziegler-Nichols method of PID parameters, piecewise constant coefficient incremental PID control strategies for the control of the furnace. Specific method as shown in Figure 4, to A point before you can give the maximum amount of control, so that the system fast warming; AB use PD control between two points; steady state in critical areas, in order to eliminate the need for steady-state error system, join the integral role in PID control; when the overshoot is greater than 5%, the output is 0 to stop the heating. In this system adopts Siemens S7-300 series of function module FM-355-2C realization of PID control.

Figure 4 step response curve diagram

3.2 monitoring layer

Monitoring layer position machine parts: Server uses the Windows 2000 Server operating system, monitor software adopts Siemens SIMATIC WINCC6.0 SP1.

WINCC (Windows Control Center) configuration software is Siemens and Microsoft joint development, it assumed the data management and acquisition, alarm, historical trends, data, records and reports, etc. [3-5] its multi-level permissions management, electronic records, such as FDA 21 CFR PART 11 requirements. Extract parts of the picture are: extraction of static flowchart, dynamic flowchart, control instrument loop, heated, cooled, cycle control, event alert, parameter setting, report printing, real time curve and historical curve display, user management, OPC Server, remote monitoring and management and help section. WINCC can call MicroSoft 0DBC technology to build the database, SQL Server database with the query, delete, modify, backup, import, export, and other powerful features. WINCC can also call Excel DDE data report.

Monitoring layer lower computer parts: lower computer programming software adopts Siemens STEP 7 software through the function block FC programming separation equipment, technology, modular, so that the control procedures relatively independent and process clear.

Block-ordered classification DB so that the data structure is more reasonable, data read and write more secure. The entire system is set up automatically and manually run the two sets of options in programming the system movement divided into multiple actions section, making the system in operation at any time to "pause", maintained in its current state; then through the "continue" feature enables the system to a previous state continues to run indefinitely. To make the system ready to respond in running some incidents, reduce accidents caused by the program to run, improve security and reliability of the system running. [6, 7]

5 conclusions

This article describes the monitoring system of traditional Chinese medicine extraction, the use of PROFIBUS technology to build the underlying network, for each key process data monitoring, control, implement the entire process

Tracking. The system can be unit operations and to finding the best working conditions, the system has become a centre of scientific research personnel engaged in the production process of natural substances, in the development of effective tools and in practice to obtain good results.

Innovation: the author of this article will introduce the "Chinese PROFIBUS technology equipment research and Development Center" laboratory project construction, the use of the construction of traditional Chinese medicine extraction process control system of the underlying network, making lab research staff can be more convenient and efficient in the production process of traditional Chinese medicine research and development in the discussion.