Styrsystem för ångpannor med PTC

As the practice shows, the implementation of such complexes results in increasing of the efficiency of a boiler unit approximately for 20% and reducing its shutdown time. In addition, industrial emissions are reduced, conversion from one type of fuel to the other one is simplified, production and operational costs are reduced, fuel is used more effectively.

The main body of PTC is programmable logic controller of CS1 type, which executes all operations on realisation of control algorithm. Several Omron proprietary and open network solutions are utilised for connection of the controllers in the system. Ethernet, Controller Link and DeviceNet are used for control of large objects with large amount of controlled parameters and executive mechanisms. Besides controllers connected in several network levels, such Omron components as NT terminals, frequency inverters, contactors, relays and solid-state relays are used for assembling of PTC "Om-mega".

Basic functions of Boiler control systems

Automatic (automated) control of a boiler unit during kindling, long operation with set parameters to be maintained, a regular or emergency shutdown. The possibilities to set parameters for an automatic mode by an operator and remote control of individual devices.

The guaranteed operation of all required safety devices and interlocks as per standard specifications. Database organisation and management required for an operator's job. Data display in the form of mnemonic diagrams, tables, graphs and trends, printouts of reports in the format agreed with a Client.

Control of process parameters with use of simply and multiply program controllers the number of which is defined for each specific automation project.

Records updating and archive information review for a specified period of time. Realisation and keeping of a separate archive by the principle of "an emergency cut-off".

Support of protocols for data exchange with networks of a high level (the level of plant automated control system). Data access is defined on stages of development and implementation of SPC. Keeping of calendar and realisation of the real-time hours. When SPC is connected to the data network of the station process control system, the built-in clock is synchronised with the time for the whole station. Realisation of protection from an unauthorised access to set-up parameters and data stored.

Continuous diagnosis of the connected equipment and self-diagnosis

As an option, the following specific modes may be implemented: kindling of a boiler with outlet to the "cold" or "hot" main line; a boiler unit running under control of "the main controller" controlling several boilers at the same time which are connected to one main line; the mode for reading the parameters of controls, etc. Structure and design features As a complete set PTC includes the following components:

• one or several control cabinets,
• one or several electrical cabinets,
• the operator's work station.

As a rule, the control cabinets and operator's work station are located in a control room, and the electrical cabinets - in immediate proximity to a boiler. The buttons provided to control shut-off valves "on site" are installed on the doors of electrical cabinets. Individual push-button stations may be installed for the valves which are positioned out of a visibility range from electrical cabinets. Depending on the specific conditions of the station, the control cabinets may be positioned far from the operator's work station at a distance of several hundreds of meters.

Additional measures to increase reliability

The backup of the SPC components may be provided depending on the requirements for a specific project. The backup of the information networks, computers and terminals is applied in some implemented systems. In addition, a stand-by controller is used which duplicates the protection functions.

• Communication interfaces supported by PTC "Om-mega"
• Data computer network of a plant - Ethernet TCP/IP
• Data management network - SysmacLink, ControllerLink, DeviceNet
• Remote input/output network - DeviceNet, Compobus/SFreely programmable interfaces - RS232C, RS485/RS422. Types and number of interfaces are defined in the specifications for an order.