Considering the fact that energy prices are ever rising, cost reductions for primary and secondary energy carriers are becoming even more important for the optimization of production costs.

Energy management systems allow producing companies to detect and utilize existing potential for improved energy efficiency. Weak points can be detected and energy costs reduced significantly.

Implementing an energy management system step by step

The implementation of an energy management system is a continuous process which includes the following steps:

• Development of a consistent network for the acquisition of all energy consumption counters
• Consumption analyses based on different parameters with detailed analysis of critical apparatuses or plants and also peak load analyses
• Simple energy management with automatic load shedding which is nevertheless not coordinated with the process
• Integrated energy management with automatic and technologically coordinated load shedding

The ideal solution - integration of the energy management into the process control system

Thanks to the integration of the energy management tool into the process control system, acquisition, analysis and optimization tasks can be performed on the same platform as the process control. This approach provides numerous benefits:

• consistent and uniform data pools
• accredited analysis tools
• process-oriented, consumption-optimized parameterization of all production units
• one common user interface for process control and energy management

The information which the process control system transmits from the process provides the basis for each energy management system. Energy management is integrated into the process control system in such a way that it is automatically linked to all consumption data acquired online. In existing plants in particular, for the most part not all energy counters are linked to the process system, and must therefore be captured offline.

Basically all consumption counters for

• primary energy carriers (electricity, oil, gas, water)
• secondary energy carriers (e.g. heating steam, sterile steam, hot water)

have to be captured. In addition, the consumption values of other media, such as cooling agents or CO2, must be captured and integrated in the combined data pool.

In order to also realize this comprehensive consumption data acquisition in existing plants, ProLeiT provides an acquisition system with modern PDAs.

The PDAs to be captured offline are identified via a barcode label using a scanner. Prior to saving, the manual input is checked for plausibility.

Using the energy management software, existing consumption data can be analyzed according to different aspects:

• Energy purchased from the provider
• Feeders with the highest consumption values
• High-consumption areas
• Detailed analysis of critical plants and production units
• Peak load analysis

Based on these analyses and combined with the planning data from the production plans, it is possible to

• create daily operation schedules with operating times, arrival and departure times for technical supply systems and auxiliaries
• detect production units or process stages which are critical with regard to energy consumption
• check the energetic state of technical supply systems

The approach enables the optimization of processes on a long-term basis.

Consumption analyses allow the plant operator to develop strategies for avoiding repeated peak loads and for load reduction:

• Consumers which are permanently running are checked in order to determine whether this is actually required
• Consumers which require high amounts of energy at the same time are connected in such a way that they can communicate with each other
• Power adaptation, e.g. partial disconnection of multiple-line plants
• Specific disconnection and coordinated reconnection of defined consumers

The simple load-oriented disconnection approach, which should always be strategically adjusted in such a way that it does not affect production, must nevertheless be considered as a "hard" load shedding strategy. Technology-oriented and coordinated disconnections allow much smoother load shedding.

Simple energy management - load-oriented disconnection

In this case, the energy data acquisition unit communicates with the controllers of the different auxiliaries in order to allow automatic load shedding. Since load shedding is not coordinated with the process, technical problems are possible.

Integrated energy management - coordinated disconnection

Since energy management is integrated in the process control system, automatic and technologically coordinated load shedding is possible. This avoids technical problems.

The Plant iT software family provides ideal prerequisites for integrated energy management because parameters for the entire plant structure, including all consumers and even actuators and sensors, can be defined. For each production unit, the relevant parameters can be defined in such a way that process requirements, along with load-based automatic disconnection strategies, can be taken into account. 

Energy management is performed on the same user interface as the process control. In the view which displays information about the process itself, plant operators are notified that peak loads might be reached soon and that defined plant sections will be shut off temporarily.