Powerhouse Energy Management
- Minimize a plant’s overall energy costs by controlling operations to achieve the optimum cost of purchased fuel and electricity
- Provide consistent process steam and electricity to the plant as needed and with minimum variation
- Immediately and reliably respond to any change in load demand
- Fully comply with operating regulations and constraints
Optimization of the powerhouse starts with control of pressures in the complete steam header system. Every structure needs a solid foundation! For powerhouse control, optimization of the operation can only be successful if built on the foundation of a sound steam header pressure control architecture. The control system can then be constructed using a building block approach. These building block control modules can be added for boiler load allocation, turbine load allocation, and utility tie line control. The result is a complete Energy Management System (EMS).
Introduction to AAI’s Energy Management System
A typical powerhouse can be more difficult to run and maintain than a much larger Utility Plant because of the diverse objectives, varying operating conditions and added process complexity. The AAI Energy Management System meets the steam and electrical requirements of a Plant at minimum cost subjective to the operating constraints established for the process and generation equipment.
The AAI control strategy provides dynamic response to energy demand at the Regulatory level in the Distributed Control System (DCS) and then slowly redistributes steam flows with the Energy Management System to the boilers and through the turbines.
Once an upset has been stabilized by the header pressure controls, the higher level Energy Management control function will make rule-based decisions continually and consistently to minimize the cost of energy. The EMS adjusts steam flows to improve cost efficiency by balancing steam loads and electrical generation to meet operating constraints at the lowest possible cost to the powerhouse.
The AAI Energy Management System is Modular:
- Steam Header Pressure Coordination is the system foundation.
- Power Boiler Optimization stabilizes heat release and enables maximum waste fuel burning.
- Boiler Load Allocation allocates the total plant steam demand between the various boilers based on minimum costs while observing boiler constraints.
- Turbine Load Allocation distributes steam among the turbines and pressure reducing valves (PRVs) to minimize the cost of incremental process steam demand while observing turbine constraints.
- Tie Line Control controls the quantity of energy purchased from the power company/utility.
These software modules work closely together to optimize the cost of operation of the powerhouse.
The AAI Energy Management System is a rare hybrid system. Part of the system resides in the DCS regulatory controls to provide the dynamic responses required. The other part can reside in either the DCS or a stand alone PC that downloads daily costing information and set points from the utility.
AAI furnishes guarantees of performance with installations of the Powerhouse systems based on a survey of existing powerhouse operations. Guarantees typically involve measurable system and process parameters such as percentage of time on full automatic, fuel use reduction, or reduced electricity costs. AAI is confident that installation of a this system will result tangible benefit for the end user and is willing to back installations with a firm warranty. For the benefit of the client as well as AAI, it is important that a set of precisely measurable parameters make up the boundaries for determining process performance before and after system installation.
AAI believes that competitive advantage can be gained by Pulp and Paper Industry Manufacturers through the proper application and use of today’s computer and control equipment. This is proved every day by AAI engineers who leverage their technical systems knowledge with process experience to provide clients with significant dollar savings through higher process throughputs and efficiencies. The AAI Powerhouse EMS system is a specific example of this.
With this installation a mill can expect reduced energy costs through improved fuel use, improved use of efficient equipment, optimal decisions for purchasing and/or producing energy and improved steam header control.