Measuring the pipe wall temperature in power stations

It is therefore increasingly necessary for base-load power stations to be able to cover not only full-load operation, but also low-load fluctuations with sometimes steep load gradients.

Coal-fired power stations were never designed for low-load operation. To ensure optimum firing and the even load on the system parts this entails, new methods of control are needed.

For example, the evaluation of pipe wall temperatures with up to 2,000 thermocouples at the boiler is an important indicator of constant firing and load on the boiler. By evaluating this information and forwarding it to the main automation system, the manager of the block-unit is provided with important parameters in the control room.

Distributed solution

Phoenix Contact does not just offer all the necessary components for the distributed collection of measuring points using Ni-CrNi thermocouples; it can, if required, also supply pre-assembled and ready-to-use I/O stations equipped according to your requirements. These I/O stations are used to provide signals directly to the main automation system via PROFIBUS DP, and they can be installed immediately in the field. All the relevant ambient conditions, such as temperatures up to around 60°C, have been taken into consideration in the optimized control cabinet design.

Central solution

In addition to components, Phoenix Contact also offers a complete solution for rebuilding central stations. All measured values are acquired in the pre-assembled, pre-wired, ready-to-use central cabinets, and mean values are generated and sent to the main automation system.

For example, the new central cabinets consist of:

• Bus couplers for PROFIBUS DP with temperature measurement terminals (type UTH)
  with internal cold junction
• Bus couplers for PROFIBUS DP and temperature measurement terminals (type RTD)
  for recording compensation measurement via PT100
• Separate supply of the PROFIBUS stations via 24 V power supplies
• Separate protection of the stations via device circuit breakers with PT connection technology
• Central controller for evaluating measurements and forwarding them to the main automation system
• On-site visualization via operator panel with touch screen display and visualization software
• Industrial firewall/router for secure communication via the Internet