Natural Gas Prices And Emissions Prompt Installations

In February, the Energy Information Administration, which is the official energy statistics from the U.S. government, projected a 2.7 percent decline in U.S. real gross domestic product (GDP), which would trigger decreases in domestic energy consumption for all major fuels.

The downturn is also contributing to a decline in natural gas consumption, particularly in the industrial sector, which has led to lower natural gas prices. The Henry Hub natural gas spot price is projected to decline from an average of $9.13per thousand cubic feet (Mcf) in 2008 to about $5 per Mcf in 2009. However, it is projected to increase in 2010 to almost $6 per Mcf.

Specifically, while consumption growth in 2010 remains largely dependent upon the timing and pace of economic recovery, some projections estimate a 2.2 percent growth in the electric power sector, combined with slight growth in the residential and industrial sectors in 2010. Increased consumption, combined with a continued decline in drilling activity (currently, there are only 970 working rigs), will likely cause significant increases in demand.

In addition, more public facilities are expected to make moves toward natural gas solutions this year. In February, Speaker of the House Nancy Pelosi and Senate Majority Leader Harry Reid released a letter asking the Capitol Architect to switch the Capitol Power Plant from coal to 100 percent natural gas by the end of 2009.

Since manufacturing plants are currently saving money on natural gas prices, the best time to retrofit boilers and improve efficiency might be right now, prior to natural gas increases next year. In addition to meeting the definition of best available technology, Benz Air Engineering solutions successfully exceed all federal emission guidelines.

Many solutions qualify for rebates, including up to 50 percent of the installation cost. Some projects may qualify for additional funds under the terms of the federal stimulus package.

The Combustion Air Flow Control Strategy Is Flawed

After reviewing many boilers with the nearly identical control strategy, I believe there are some substantial issues relating to the simultaneous fan speed and damper control for the control of combustion air flow, not the least of which is a scenario where an explosion can occur. And, while the likelihood of an explosion may be unknown, the use of the strategy for combustion air flow control is fundamentally flawed.

Exploring The Phenomenon

The boiler burner is a parabolic system, pressure drop increasing to the square of the flow through the boiler. A damper will merely increase the pressure drop which pushes the system operating point up that curve, increasing the pressure on the fan while reducing the flow from that fan.

This is true so long as the operating point is on the right of the maximum pressure point of the pressure versus flow fan curve. The control air flow by a damper to the left of this point is nearly impossible since the slope is positive, which means opening the damper will result in a decrease in flow from the fan and closing the damper will result in an increase in flow. Operation in this range typically results in a flame out at synchronous speed which is set as the limit of operation (otherwise known as turndown ratio).

Closing the damper a full speed to cause a pressure drop of 5"wc will decrease the air flow by 18kCFM. To reduce the flow by that same 18kCFM requires the damper to impart just 1.7"wc of pressure drop on a fan running at 50 percent speed. Therefore, the attempt to control air flow by simultaneously controlling fan speed and damper opening is tenuous at best.

Assuming that the opening of the damper is repeatable (the linkage slop making that assumption unreasonable), the control of flow at lower fan speeds is exponentially more sensitive to damper opening, which means that the smallest of damper movement will result in incredible increases or decreases in air volume flow.

Moreover, the flat curve of a slowed fan, makes the transition into the positive slope of the fan curve substantially more likely than that of a synchronous fan. The propensity of the damper to cause operation near or at the maximum pressure point of the fan curve increases the likelihood for the fan to operate on the positive slope portion of the pressure versus flow curve.

In exploring the affects of this phenomenon within a boiler, let's assume that the boiler is operating below its setpoint O2 AND the fan operating point fell on the left side of the curve during the ramp down of the boiler. The O2 trim signal would kick in, opening up the damper (increasing the fan speed would result in the point maintaining its location on the positive slope). However, because the operating point was initially at the left of the maximum pressure point of the fan curve, the volume flow rate of combustion air is reduced.

The lower combustion air results in filling the firebox with CO and unburned fuel. The damper continues to open to a point where the opinion would allow the greatly higher air flow on the negative slope of the fan, instantaneously filling the combustible filled firebox with enough air to cause an explosion.

Please bear in mind that most low NOx burners have a tendency to produce vibrations regardless of the combustion control.

When the burner is a stage fuel burner, the design of which injects fuel through opposing spuds into the firebox in the attempt to lower NOx by stretching the flame over a longer path within the firebox. This design is predisposed to flame detachment, which is exasperated by stratification of recirculated flue gas which reduces flame speed.

As the flame detaches from the burner front, fuel is injected into the firebox accumulating in pockets which combust instantaneously upon reaching the detach flame. We typically redesign the burners to sharply reduce the tendency for flame detachment. (The stage fuel approach for lowering NOx is just one of many approaches sold which have no basis in fact, as a old ring burner will actually get lower NOx with the same amount of FGR.)

*Boiler operators are encouraged to request a fan analysis and supporting documents from Benz Air Engineering.

Providing A Solution

There seems to be an increasing number of installations that have similar control schemes. After reviewing several boilers that have experienced furnace explosions, it seems most likely that the combustion air flow strategy is the cause. If the combustion air flow strategy using a simultaneous fan speed and damper control is not the cause, then it seems to be, at the very least, a contributing factor.

We recommend that any such installations be evaluated before other flawed solutions are implemented to alleviate the symptoms of a considerable problem. For example, one operator had installed buckstays in an attempt to alleviate the noise from combustion vibration, which resulted in concentrating the vibration within the boiler. It was our conclusion that this concentration most likely contributed to the fatigue fractures of their superheater tubes.

Energy And Environment Focus Leads To Rapid Regulation

With the Obama Administration's emphasis on energy and the environment, more people are wondering what this might mean for manufacturing. From what Benz Air Engineering has gleaned from several meetings and presentations, most industry insiders seem to be pointing to the Western Climate Initiative, launched in 2007, and the Regional Greenhouse Gas Initiative (RGGI) as the regulatory drivers for a future national model.

For environmentalists and the energy industry, the most notable feature is that 2012 projections include revenues from a source that does not yet exist: a carbon dioxide cap-and-trade system. Currently, there are two cap-and-trade models being implemented in the Northeast and West.

Some other key points for consideration at Western Climate Initiative meetings:

• Reduce CO2, CH4,N2O, HFCs, PFCs, SF6 emissions to 15 percent below 2005 levels, by 2020.
• Priority reductions, including facilities that emit 10,000 metric tons of C02e by 2010
• Mandatory reporting by all emission producers by 2011
• Future regulations for manufacturers that emit > 25,000 MTCO2e/year by 2012
• Future regulations for electrical generators at the point of first delivery by 2012
• Future regulations for emission sources at the point of emission by 2012
• Future regulations on transportation gasoline and diesel combustion by 2015
• Mandatory implementation of GHG Inventory Management Plan

Benz Air Engineering is already working with several sites to meet future emission mandates while improving efficiencies that result in an immediate fuel cost savings. Most engineering solutions, which optimize efficiency and minimize emissions for industrial, utility and district energy and steam generation facilities, realize an payback in approximately two years. Many qualify for rebates, including up to 50 percent of the installation cost.

Quick Plant Energy Profiler Evaluates Energy Management

Developed by the U.S. Department of Energy (DOE), the Quick Plant Energy Profiler Software Tool is one of several free web-based programs developed by the DOE to help U.S. industry improve energy management at industrial facilities. The software is designed for industrial plant managers and personal who have access to basic information about major energy-consuming systems at their industrial plants.

Simple to use, energy managers or boiler operators can complete a plant profile in about an hour. The Quick PEP tool asks for:


• Average utility bill information
• Average production information
• Major energy-using systems
• Score cards (optional)
• Average energy usage information


Once the information is input, Quick PEP tool can produce a profile that includes:

• The Quick PEP tool will provide the following:
• Energy use and cost per unit of production
• Annual purchased energy graphs and tables
• Potential annual energy savings graphs and tables
• Customized list of next steps, including recommended ITP software tools for further analysis of specific systems

Once registered, the Quick PEP case Quick PEP provides a customized, printable report that shows the details of energy purchases at the plant, how energy is consumed at the plant, potential cost and energy savings at the plant, and a list of next steps that you can follow to get you started saving energy at your plant. There is also an online tutorial, which provides key definitions and step-by-step instructions.

One of the most compelling portions of the report is how much energy each major systems in your plant use on an annual basis. Even if you are unsure of percentages of total electricity or total fuel/steam that each system uses, Quick PEP is equipped with industry averages.

In addition to evaluating the savings opportunities provided by the software, Benz Air Engineering can help your plant review the information and prioritize energy management systems around your boiler. Or, simply fill out and return a brief one-page questionnaire.

A Two-Part Equation: Renewables And Efficiencies

According to The International Renewable Energy Agency (IRENA), energy consumption has doubled between 1971 and 2005 and fossil fuels provide approximately 79 percent of the global supply. But what IRENA, a new intergovernmental organization for renewable energy with 75 member countries, does not spell out is that the majority of the world's population doesn't rely on this supply.

Specifically, it is estimated that 1.6 billion people do not have access to electricity and 2.4 billion people rely on traditional biomass (wood and dung). As people in developing countries require more energy, most will turn to fossil fuels much like China and India have since 1971. (China and India doubled their energy demand since 1990 and are expected to match or surpass OECD countries by 2030.)



Solution: Renewables

IRENA aims to become a driving force in a rapid transition toward the widespread global use of renewable energy. Specifically, the new agency will facilitate access to reliable data on the potential of renewable energy, as well as information about best practices, effective financial mechanisms, and the state of the art in renewable energy technologies. The agency will also develop and promote renewable energy policies on the local, regional, and national level. You can learn more about IRENA goals here.

While the United States has not yet joined the agency, it was represented at the founding meeting by an observer from the U.S. Embassy in Berlin. And, in recent weeks, the United States will join as it moves toward tighter emissions standards and renewable energy. ON Jan. 30, the U.S. Department of Energy (DOE) and the U.S. Department of Agriculture (USDA) announced they will invest up to $25 million over the next four years for the research and development of processes that produce biofuels, bioenergy, and high-value biobased products.

Solution: Efficiencies

Of course, renewable energy is only part of the equation for sustainability. The other component is making more efficient use of the energy we have on hand. For example, one of Benz Air Engineering's recent retrofits in Modesto, Calif., reduced the nitrogen oxide (NOx) emissions of one boiler from 30 parts per million to 6 parts per million. And, because the boiler is operating more efficiently and burning less fuel while delivering the same output, CO2 was reduced 20 percent. Four areas for consideration:

• Efficiency: Solutions require less fuel to produce a given energy output.
• Reliability: Solutions typically retrofit on proven, reliable steam boilers.
• Environmental: Solutions reduce CO2 by requiring less fuel, and reduce NOx.
• Economic: Solutions save manufacturing plants on their energy bills.

For example, if every manufacturing plant in the United States was retrofitted to provide for better efficiency, the United States could reduce its energy demand by as much as 20 percent. It makes sense for companies to consider reducing their energy needs as quickly as possible because most estimates project the global population will reach 9 billion people by 2030.

Considering the combined rate of population growth and the rapid pace of growth among developing countries, supply and demand will likely increase energy prices exponentially. In addition, there seem to be clear indicators that stricter emissions standards will be forthcoming under the new administration.