Employees of the Severodvinsk Bakery (Arkhangelsk region) addressed the company "Northern Energy Systems" with a request to solve the issue of repair and modernization of the control system of three Rothoterm WP rotary kilns manufactured in Germany. Rototherm WP rotary ovens are used for baking bakery and confectionery products.

The factory control system of the furnace was built on printed circuit boards located in a special electrical cabinet built into the furnace. The information for the operator was output to a 5-inch touch panel connected via the CAN interface to the printed circuit board. During the long-term operation of the furnaces, serious malfunctions occurred in the electronic control system, namely: the failure of the control panels located on the front of the furnace. These panels were not subject to repair. The cost of new original panels was very high, and their delivery was possible directly from the manufacturer's factory in Germany. As it turned out, the failure of the panels of these modifications on the furnaces occurs systematically and is the main problem.

Together with the employees of JSC Severodvinsk Bakery, it was decided to develop and implement a new rotary kiln control system based on ARIES equipment.

The main executive mechanisms

  • Baking chamber. A trolley with future products is rolled into the chamber on a movable plate, during the baking process this trolley rotates to evenly distribute hot air over the products.
  • TEN zone. In the heating element zone located outside the baking chamber, there are heating elements with a capacity of 75 kW, distributed into 3 groups, the main air channel for heating air passes through the heating element zone.
  • Main fan (power 1.5 kW). Circulates air between the heating element zone and the baking chamber. Due to air circulation, heat is transferred from the heating element zone to the baking chamber and uniform hot air is blown through the products.
  • Steam generator. It is located in the heating element zone and is designed to humidify hot air during the baking process by supplying water to it.
  • The gate. Designed to redirect the air circulation inside the oven, it is used mainly at the end of the baking process to discharge "burning" into the ventilation system of the plant.
  • Temperature sensors. Pt100 thermal resistances, located in the heating element zone and the baking chamber, allow you to control the current and limit values of temperature.

The algorithm of the control system

The control system is developed on the basis of the following ARIES equipment:

  • Operator's touch panel SP310-B.
  • Frequency converter PCHV2.
  • Programmable logic controller PLK110-30 [M02].
  • The MV110-2A analog input module.
  • Power supplies for heavy duty BP60-24S and BP30-24S.
  • BP60B-12 power supplies.
  • Meyertec screw terminals.

Before starting the shift, the operator switches on the system (switching from sleep mode) with a button on the control panel and selects the desired baking program. After switching on and selecting the program, the system starts the main fan at the speed set in the settings menu (standby speed), and also heats up the furnace chamber by turning on and off the heating element group according to the setpoint of the selected program of the 1st cycle.

At the moment of heating up the oven, the operator will not be able to start the baking process if the temperature is very different from the setpoint (the start and stop buttons are blocked). After warming up the oven and reaching the setpoint temperature, you can start the process of baking products, the system informs the operator about this by giving an audible signal.

The operator places the cart with the future products into the furnace chamber on a rotating carriage and presses the "start" button on the touch screen of the panel. The baking process takes place according to a given program consisting of 5 routines and a baking mode.

The following values are set in each subroutine:

  • The time of each routine (the total time of the baking program consists of the time of 5 routines)
  • Temperature
  • Fan speed
  • The position of the gate (in %)
  • Humidification of PAR (the amount  is indicated in litres of water)

The number of routines used in the baking program is selected by installing process data into it (if there is no data, then this routine will not be executed).

The control system of the oven has many protective functions that do not allow the operator to disrupt the baking process. The total number of baking programs used is 100.

The implementation of a manual baking mode is provided. At the end of the baking process, the system prompts the operator to start the baking mode at certain settings. Also, at the end of the process, the control system gives a loud sound signal from the sound device about the end of the process.

Automation result

In general, the system turned out to be in no way inferior to the original furnace system, and even more perfect. The presence of a large touch screen makes it easier for staff to work with the oven. This control system can be used not only on Rothoterm WP furnaces, but also on rotary furnaces of other manufacturers, for example, Miwe.

The implementation of this project made it possible to get away from expensive imported equipment. As a result, the customer receives operational technical support for the management system, which was previously unavailable.

Illustrations of the project