Automation of a sugar processing plant

Sugar production is a complex multi-stage automated process

A sugar factory is a technology that allows you to process organic raw materials grown in the fields into a full-fledged food product - sugar.

First, the beets are brought to the sorting point, laboratory measurements are taken, the qualitative composition is determined, then the beets go to the sink. After separating the dirt, tops and washing, the sugar beet is sent for cutting. The beets are cut into chips of a given size and enter the diffusion apparatus. Chips go to one side of the apparatus, and water, according to the ratio of the amount of chips, to the other side of the apparatus. The diffusion apparatus has an inclined structure. With the help of augers, the chips rise from the bottom up, and the water falls down under the action of gravity. The whole process, from chip feeding to unloading, takes approximately 2.5 hours. The diffusion apparatus is divided into 4 zones, in each of which the set temperature is maintained with the help of steam in thermal jackets. During this time and at the optimum temperature, diffusion occurs - the process of transition of juice from chips into water. Depending on the sugar content of the beets and other parameters, the technologist selects the optimal temperature parameters and the water/chip ratio.

After extraction of sugar from sugar beet chips in the process of diffusion, diffusion juice and desugared chips are obtained. Chips (pulp) come out of diffusion with dry matter (SW) 8-12% and through transport systems (TS) enter the deep-pressed chip presses (PGO) ZhSK. ZhSK consists of PGO (3 pcs), two pulp dryers and a set of vehicles. In the PGO, pulp is squeezed to obtain pulp with a DM of 18-30% and pulp-pressed water (JPV). The pressed pulp enters the pulp dryer drum. In pulp drying plants (JSU), water is evaporated from the pulp up to 88-92% DM. Next, dry pulp enters the granulation department to obtain pulp granules.

As can be seen from the above, the sugar production process is very energy- and labor-intensive. The overall connectivity of all processes depends on the quality of the implemented functions of automated control systems. Prevention of emergencies in the early stages allows you to improve the quality of the product at each phase of the process.

Most sugar refineries are old factories built or rebuilt during the Soviet era. What are automated control systems at any of the sugar plants in Russia?

Usually, parts of the production process are automated locally and not always by equipment from one manufacturer. The described solution is no exception. In this case, the Schneider Electric distributed control system is taken as a basis, the top level of CitectSCADA, all other used brands, such as Siemens, B&R, OWEN, are used as slave nodes and, if possible, do not perform logical functions.
By a stroke of luck, the possibility of using Schneider Electric equipment was agreed upon. This makes the system very flexible with a certain programming approach.
So, for example, one PLC can serve from one to five stations. The station is understood as a technological production site: diffusion, evaporation, carbonation, bagasse drying, and others.

In the visualization system, each analog parameter has a task.: Let's talk a little about the functions of the system by video frames: The bolding approach is a great solution. More important decisive parameters stand out from the general list. Process control systems use PID controllers (PID) for analog control. To calculate the regulatory impact, the PID formula is used, which involves:
- exercise. Required parameter value;
- current measured value of the controlled parameter;
- coefficients of the regulator. Set by the user.

In practice, the use of regulators was found to be insufficient. To increase the flexibility of the controller settings, a mechanism for adjusting the reference using corrective parameters (CP) is used. The mechanism allows you to change the structure of the controller without reprogramming the PLC and PC.
Any controller can be logically reassigned from the scada without having to reprogram the controller. This is achieved through the use of a special architecture of the program code, which has structural redundancy and the ability to configure and switch embedded in it.

Next, it is worth noting the quality and configuration of cabinets. Sugar factories, despite the fact that they have a pronounced seasonality and usually process raw materials from the end of summer to the end of spring, are located in the southern regions of our country and the usual temperature inside the workshop can reach 40C, respectively, there are increased climatic requirements for placing equipment inside the cabinet.
this is how the cabinets look like:

Let's talk a little about the functions of the system by video frames::

Water treatment station. Milk of lime, acid, water of different pH, squeezed juice enter the general collection, and all this is sulphated with sulfuric gas. The task is to prepare water of a given pH. An extremely difficult process due to the large inertia and the constant clogging of pipes and valves with milk of lime. We have to come up with mechanisms for "juggling" the valves.

Evaporation station. The station thickens the juice into syrup. It is important to accurately maintain the levels due to the "burning" of the overgrowth of the heat exchange surface. Difficulties cause control levels (boiling juice with foam). For convenience, the condensate in the residue collectors (blue columns) is displayed as collector widgets.

Lime kiln. The task is to evenly dose limestone and coal into the skip for even distribution in the skip, lift it to a height of 30 meters and pour it into the oven, evenly distributing the pour. The goal is to get milk of lime and gas for production. Difficulties - in time and smoothly stop a heavy skip and make an even distribution algorithm.

Diffusion department. The task is to cut a given amount of chips, apply in diffusion, mixing with water in a given proportion. Difficulties - in inertial processes, different behavior of the system in different situations and uniform production of pumping.

Bag-drying department + bag-pressing department. The task is to press the pulp and feed the pulp dryer for drying and obtaining marketable granules as a result. One of the most complex stations in the plant. A very inert process. The work is affected by the pH of the pulp, the means of water treatment in water treatment (acid or gas, milk or gypsum and their quantity), the speed of the presses, the size and thickness of the chips, the freshness of the beets, the uniformity of unloading from diffusion. We often have to select control options with switching to the optimal mode.

Filtration station. The task is to filter the juice. Implemented auto-tuning of pressure on the filtration station depending on the "clogging" of filters and auto-tuning of performance depending on the flow. For ease of perception, the filters in different modes blink and change colors.

 
Signal settings window. You can name the signals, change the physical units and the number of decimal points to display. Change current and physical scales. Switch between PLC modules. Immediately take the desired values from any addresses and convert. All changes are at runtime and are immediately accepted throughout the system.

Elevator. Granary. The goal is to make a route from point A to point B in any combination. After selection, the route of the type is highlighted as in the Yandex navigator. If the route suits, we start the chain from the end automatically.

Project author:
Maximum Automation
Individual Entrepreneur Davidyuk Maxim Alexandrovich

Tel.: +7 961 599 6154
e-mail: maximumautomation@yandex.ru

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