Steam Engineering

THE STEAM ENGINEERING TEAM
SUCCESSFUL STEAM SYSTEM IMPROVEMENT PROJECTS

This section of our web site describes projects we have completed that made a dramatic difference in the performance of our clients' steam systems.

Boiler Controls are Tools

For years, we have been explaining to our clients and prospective clients that electronic boiler controls are the tools to improve boiler performance. Knowing how to use the tools is the important key to successful improvement.

Recently we had a valued client purchase a new Moore Process Automation Solutions control system from a competing engineering company. They actually purchased two control systems for two of their facilities. The Moore control system uses a Windows operating system and has brilliant graphics. The technicians installing the system were very skilled but, unfortunately, the client failed the environmental source test at both facilities, because the technician really did not know how to control solid fuel boilers.

The client has failed the source test and been fined by the State environmental agency. We are now working with the client to re-configure the control system and to try to negotiate a re-test with a State agency that is convinced that the only solution is new and expensive air pollution controls.

It would have been much less expensive (and much less painful) to have installed a Steam Engineering-designed control system initially, to avoid the failure, fines, and the chance that we will be required to install the very expensive air pollution controls. The Moore control system is a good tool, but it is just a tool, and the key to success is knowing how to apply the tools to a solid fuel boiler.

Steam Load Management

To the left is a section of a steam flow chart that shows the steam load swings of many processes. We have used a simple technique to reduce these plant steam load swings, and the results are demonstrated with these before and after images.

Steam Engineering has long advocated three axioms to optimize steam system performance. The first axiom is to generate and transmit steam at the highest practical pressure, and the second axiom is to use the steam at the lowest practical pressure. This improvement embraces two of these axioms. 

At Guy Bennett Lumber in Clarkston, Washington, we increased the boiler operating pressure from 115 psig to 175 psig, and we installed a pressure-reducing station at the dry kilns to reduce the boiler pressure from 175 psig to 70 psig. The pressure-reducing controller is an electronic single loop controller with an output rate feature. By slowing the output rate of increase, we are able to eliminate the spikes and oscillations of the dry kiln steam load.

THE RESULTS

SUMMARY
The feedwater balance is better, there is less air pollution, the boiler is easier to fire, and the supply of steam to the dry kilns is steadier. The key to the success of this improvement is the device used as the pressure-reducing valve controller. We utilized a Honeywell single loop electronic controller with an output rate feature. When the steam demand of the dry kilns increases rapidly, the pressure-reducing controller increases the amount of steam available to the dry kilns at a slow and controlled rate.

Engineering Retainer Agreements

We have demonstrated to many clients that Steam Engineering Inc. is a very specialized consulting engineering firm. We are so specialized that we often provide steam system and solid fuel combustion consultation to other mechanical engineering companies.

Companies using our water treatment programs receive these specialized engineering services as part of our chemical treatment program, and several companies have purchased engineering retainer agreements to supplement their engineering departments with our specialized team.

International Paper Company at New Boston, Texas recently purchased an engineering retainer with the following results: The engineering and management group at New Boston reported that water softener regeneration has been extended to 22 days from 10 days, that chemical treatment has been reduced by half, that they are able to sell as many as five truck loads per day of excess hog fuel(they were previously buying some fuel), and that the environmental source test results were better than anyone had dared to expect. These savings are especially rewarding, because we have increased the plant drying capacity by adding one additional single track dry kiln (more dry lumber production using less fuel).

The New Boston facility values the knowledge and experience of Steam Engineering and they have entered into an engineering retainer agreement with our company. Our agreement includes unlimited phone consultations and engineering evaluations and a minimum of two trips to the facility each year to review operating procedures, to insure that the steam system is being operated optimally, and to provide operator recurrent training. The cost for this program is $800.00 per month plus expenses.

We have had engineering agreements with Champion International, Stimpson Lumber Company, Weldwood of Canada, and Columbia Forest Products.

Increased Production Using Less Steam

McKenzie Forest Products in Springfield, Oregon operates two waste wood-fired boilers at its plywood facility.

McKenzie was challenged to meet the requirements of the facility's air discharge permit, and they had trouble generating a consistent supply of steam to the production facility.

Steam Engineering designed a boiler and steam system improvement plan to achieve reliable air permit compliance and helped negotiate its acceptance with the air pollution regulatory agency. We designed and installed new electronic boiler controls that enable the operators to deliver a constant supply of steam to the plywood plant, while minimizing air pollution. We also installed steam load management controls on the plant veneer dryers and a new high temperature boiler feedwater system.

The result is that with balanced steam loads, improved condensate return, and vastly improved combustion control, McKenzie is able to dry more veneer, while burning less fuel and generating fewer emissions. The impact was so great that we are currently evaluating a single boiler operation for even greater efficiency at this facility.

More Drying Capacity Using Less Fuel

International Paper Company in New Boston, Texas operates a lumber mill with two high temperature double track dry kilns. They wanted to install an additional multizone single track dry kiln to increase the plant drying capacity. The existing boiler was challenged to provide the required steam for two dry kilns, and Steam Engineering was hired to design steam system improvements, so the facility could obtain full production from the third dry kiln.

THE DESIGN

To obtain the needed increase in steam capacity without over-firing the existing boiler, we needed to identify and capture all of the wasted heat in the boiler and steam system. We modified the combustion air distribution system to increase combustion efficiency, installed blowdown heat recovery, added a feedwater economizer, and installed a high temperature feedwater system that used the heat in the high temperature dry kiln condensate to heat feedwater.

We increased the boiler operating pressure to 175 psig. A steam load management system that includes a pressure-reducing station at the dry kilns was added, and the dry kiln steam pressure was reduced to 125 psig. Finally, we collect the dry kiln condensate in a flash tank that is operated at 60 psig.

THE RESULT

Roger Chitwood, the plant manager, and Bruce McKeever, the boiler and dry kiln supervisor, report the following results: The water softener regeneration has been extended to 22 days from 10 days, the chemical treatment consumption has been reduced by 50%, and they are able to sell as many as five truck loads per day of excess hog fuel. Before the improvements, they were buying some hog fuel. Because they increased production while reducing the amount of hog fuel burned in the boiler, the source test results were better than anyone had expected.

The facility is drying more lumber and burning less fuel. The techniques used at New Boston have been implemented by Steam Engineering for many years on various process steam systems. We have enjoyed similar success in corrugated box, plywood, food processing, and particle board facilities.

Raise Pressure to Increase Production

THE CHALLENGE
The Nestle facility in Othello, Washington was challenged to meet production goals. They wanted to raise the boiler pressure to increase the production from the fryer heat exchangers, but the existing condensate system could not return the condensate to the boilers when the pressure was increased.

The efficiency of a steam system depends on the performance of the return condensate equipment. If the system is not properly designed, heat is lost, boiler capacity is reduced, and steam quality often deteriorates. Steam Engineering has extensive experience and has enjoyed significant success in designing high temperature condensate and feed water systems for many facilities in many industries.

At the Othello facility, there were three fryer heat exchange systems, and each had its own pair of condensate pumps trying to return hot condensate to three boilers. The condensate pump system had not been installed with sufficient net positive suction head to achieve reliable pump performance, and the result was high maintenance, wasted condensate, wasted boiler capacity, and if the boiler pressure was raised to increase log mean temperature difference across the heat exchangers, the condensate pumps could not overcome the higher boiler pressure.

THE SOLUTION
Steam Engineering designed a new condensate system, making use of as much of the existing equipment as possible. We elevated one of the condensate receivers to provide adequate net positive suction head to a new high temperature, high pressure condensate pump, and we return the condensate from the other two fryer heat exchangers directly to this elevated tank. The boiler pressure was increased to 290 psig, the condensate receiver is regulated at 120 psig, and we went from four condensate pumps to one.

THE RESULT
In the words of Randy Carvo, Plant Maintenance Supervisor, "Plant production is at record levels at this time. We have replaced four inefficient condensate pumps with a system that is using only one pump. We have been able to raise the plant steam header pressure and still return the high pressure condensate directly to the boiler. The concept of using the flash steam for the plant low pressure steam requirements has reduced the temperature of the high pressure condensate and solved the problems of seals leaking on the high pressure condensate pumps.