Setting New Production Records with Improved Control Performance

by Jim Cahill

I saw an email about a success at a northern U.S. paper maker that set a new production record. To whom did they attribute this success? Since this is a blog about the experts around Emerson Process Management, you might guess the answer. And you'd be correct. They attributed their new production record to the work of our Control Performance team and their process and control study process.

I caught up with Andrew Waite, a principal process control consultant on the Control Performance team. Andrew began the study by using the EnTech toolkit which collects data from a variety of sources including pneumatic controllers, 4-20mA analog values, and can import digital data from smart field devices and digital automation systems using the OSIsoft PI data historian. The toolkit performs analysis and tuning recommendations based upon the data it collects.

Andrew noted that he uncovered all of the typical problems: tuning, control strategy issues, control valve problems, and process design limitations. The mill's maintenance department went to work fixing the control valve issues while Andrew provided tuning recommendations and improvements that could be made to the existing control strategies.

The mill attributed the increased production to taking care of the basics and having a fresh set of eyes come in to audit the existing performance. Not too bad for a couple of weeks work.

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December 7, 2006 in Process Optimization, in Pulp & Paper, in Variability Management | Comments (0)

Chemical Recovery Boiler Performance Efficiency

by Jim Cahill

We discussed improvement of multi-fuel boilers in an earlier post. Similarly, pulp and paper manufacturers often wrestle with chemical recovery boilers because of the complexity of the combustion process. This complexity is largely driven by the variability in the "fuel" (black liquor) and often by swings in production rate.

The variation in the BTU content of the incoming black liquor can cause difficulty in meeting the emissions restrictions, can lead to fouling of the boiler, may impact boiler efficiency, and can limit liquor throughput. Safety is also a major concern around a recovery boiler process.

Bob Sabin, a consultant in Emerson's Industrial Energy Solutions organization described the challenge as maximizing liquor throughput while minimizing the fouling of the upper boiler and maintaining optimal unit thermal efficiency. This can be done if the boiler combustion controls are configured to compensate for liquor BTU changes.

The process Bob and the team follow with pulp and paper manufacturers typically begins with an analysis where they measure the mills operating performance and compare it with world class performance. Some benchmarks include: maintaining excess oxygen at 1.5% to maximize unit efficiency, maximizing liquor throughput to either permit or steaming limits, minimize fouling to require one water wash per year, and running the recovery boiler in fully automatic mode more than 95% of the time.

Through this benchmarking process deficiencies and mechanical design limits can be identified and corrected. The economic benefits of process improvements can also be calculated.

Next a detailed field audit of valves, instrumentation, wiring, and control system performance is performed to find areas requiring attention.

With this assessment completed a complete cost estimate and return on investment calculation and justification can be developed to improve the performance of the recovery boiler. The expertise of the team has been packaged into a SmartProcess Recovery boiler solution which encompasses design, installation, commissioning, start-up, and operations personnel training.

Pulp and paper manufacturers typically experience project payback in three to six months through increased liquor throughput, better thermal efficiency, water wash reductions, and reduced variability in green liquor reduction.

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June 13, 2006 in Energy Management, in Pulp & Paper | Comments (6)

Improving Multi-Fuel Boiler Performance

by Jim Cahill

As process manufacturers grapple with high fuel costs to create the steam for their processes, they often look to increase the use of biomass and alternate fuels in their boilers.

The key measurement is typically the cost per pound of steam. This can be reduced by maximizing the use of cheaper fuels like wood, stoker coal, and other forms of biomass while minimizing the use of natural gas and oil.

I spoke with Chip Rennie in Emerson's Industrial Energy Solutions organization on the control challenges of operating boilers when running non-fossil fuels. These fuels can vary in moisture, consistency of particle size, BTU content, combustion air requirements, and boiler emissions performance limits.

From Chip and the consulting team, well operating multi-fuel boilers can often generate 90% of the plant's steam, operate in automatic control over 95% of the time, minimize carbon in ash, and maintain emissions to specified levels.

Chip stresses the key to optimizing the operation of these boilers begins with an assessment of the mechanical components and instruments. Optimum business results cannot be achieved if these underlying components greatly limit performance. Examples of issues to be resolved include include fuel conveyor changes, fuel bins and distribution equipment, overfire or undergrate air system modifications, fan upgrades, or damper improvements.

Chip and his team have bundled their expertise on multi-fuel boilers into a SmartProcess application and call it SmartProcess Boiler. This application provides complete automatic control of the boiler at all times including start-up, automatically adjusts for changing fuel BTU per volume, and the system allows a multi-fuel boiler to be used as a swing boiler while burning least cost fuels.

The application automates many functions that are often done manually and allows a higher percentage of steam to be generated with biomass or alternate fuels.

Projects are typically done as a turnkey including design, installation, commissioning, start-up and training of the operations staff to run the boiler using the newly optimized equipment, firing methods, and control tools. Given the high costs of fossil fuels today, payback on the entire project is typically 3 to 6 months.

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June 1, 2006 in Boilers, in Energy Management, in Pulp & Paper | Comments (10)