Dynamic Modeling and Simulation for Alstoms Supercritical Dual Fuel-Fired Boiler and Power/Desalination Cogeneration Plant

摘要

Alstom is one of the leading suppliers of supercritical boiler integrated steam power plants and their main components, including boilers, air quality control systems, steam turbines, generators and plant process control systems. This paper presents the development of dynamic modeling and simulation of a state-of-the-art large-scale engineering system design for a supercritical dual fuel (heavy oil and natural gas) -fired boiler, and cogeneration plant combining power generation and desalination. The dynamic simulation tool has proven to be effective for investigating the dynamic responses and performance of the integrated plant and subsystems, including boiler, steam turbine, water steam cycle and associated control designs against transient performance requirements in meeting load cycling and grid code requirements. The scope of the dynamic simulation model includes a supercritical steam generator, a steam turbine island, a desalination plant and key plant control systems. The steam generator model includes all the in-furnace and water/steam side heat exchangers and a comprehensive flue gas side model. The steam turbine island model covers all the HP/IP/LP steam turbines and the feedwater preheating trains with steam extractions. A simplified electrical generator has also been modeled for megawatts calculation. The desalination plant is also modeled with the key components such as brine heater heat exchanger, desuperheater and condensate pump included. In addition, a coordinated unit master control and component key closed-loop control systems are included to enable closed loop process control responses of the plant components during event transients and to highlight the capacity of controlling both electrical power and steam supply to desalination outputs. In order to ensure the dynamic simulation is representative of real unit operation, the dynamic model is validated against engineering design data at various steady state conditions. A series of dynamic control and operability case studies have been conducted using this integrated plant model to investigate steam to desalination source transfer, steam supply to desalination control stability, normal load ramping capabilities and low load operation stability. The integrated plant models will be further utilized to support future efforts for unit commissioning and identifying and developing plant control economic and optimization opportunities to improve base plant performances and provide operating cost improvements.