|Recovery Boiler Performance Analysis||Fuel Carryover and Gas Emissions Analysis||Combustion Air Analysis and Optimization|
Recovery boilers are used in pulp and paper mills to produce process steam and electrical power by burning black liquor fuel. In times of high demand, recovery boilers are often a bottleneck for mill production. Operating a boiler above the design load often leads to problems such as excess carryover, high combustion gas emissions, elevated thermal stresses, and fuel bed instabilities. Most boiler designs and modifications are based on experience and simple physical modeling. The complex nature of the turbulent gas flow and combustion in the boiler limits this type of approach, often leading to unsatisfactory results. Many pulp and paper companies have spent millions of dollars on modifications that have not fulfilled their expectations or the contractor's promises.
The advent of high-speed, cost effective computing has produced a new and powerful analysis tool, process modeling. PSL and research partners have invested millions of dollars in the development of a sophisticated recovery boiler analysis tool that can simulate the complex details of an operating recovery boiler. This tool can be used to predict, in advance, the performance increase/decrease of any boiler modification. These modifications can include combustion air and fuel changes, or even a complete retrofit of the air and fuel delivery systems. Process modeling is an effective tool for helping mill managers to make informed decisions on proposals from recovery boiler manufactures and retrofit contractors.
PSL works closely with mill personnel to collect information necessary to set up and run the recovery boiler model. We then set up and run a baseline and one or more modified cases. Detailed results of the simulation are presented in the form of images and graphs showing gas flow velocities, gas temperatures, combustion gas species distributions, fuel and carryover distributions, wall heat transfer distributions, and a host of other relevant information. Computer animations of the combustion air and fuel particulate may also be included for operational training. Simulation results allow for a thorough understanding of the boiler operation, and provide the basis for optimizing the existing air and fuel system. In some cases it may be sufficient to improve the boiler's operating practices, in other cases it may be beneficial to retrofit the boiler with a new air or fuel delivery system. The decision depends on the severity of the operational problems and the budget available for the boiler upgrade. Any of these changes can be evaluated in advance by our recovery boiler analysis tool, helping to minimize risks in the decision making process.