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Waste Not

Published Monday, March 3, 2008
clientuploads/03 Literature/Genesee-Power-RW-144.jpgVolume 11, Issue 2 - Detroit Stoker Company is a leading supplier of stokers and related combustion equipment and systems for the production of steam used in heating, industrial processing and electric power generation around the globe. David Soyka reports on how the world’s largest manufacturer of industrial stokers generates a cost-effective and environmentally-friendly business by recycling biowaste.

Biomass fuels are all the rage these days, but Detroit Stoker installed its first “green” steam generating system back in 1940 in Charlestown, S.C., which continued in operation with 100 percent biomass fuel into the 1990s. Indeed, the company has been at the forefront of technology since its founding back in 1898, when it developed the first mechanical stoker, a device that made feasible the use of finely-divided, slack coal as a fuel source. In addition to making productive use of a material that had until then been discarded as waste, this early technology improved the efficiency of the coal-fired plants of the day by reducing the number of operators to manage the steam generation process from five to one.

This legacy of improving cost-efficiency through use of otherwise non-recyclable waste materials continues a century later. Detroit Stoker builds on a substantial legacy of unlocking the value of renewable energy sources in stokers and related steam combustion equipment and systems that power heating, industrial processing and electric power generation systems. Every day, more than 125,000 tons of biomass and refuse are burned on this company’s stokers, the largest of which produces more than 100 MWe (megawatts electrical). In addition, Detroit combustion systems around the world generate power from such diverse waste products as bark, sugar cane, sawdust, and sunflower hulls – even chicken litter! The advantage of using such biomass refuse for fuel is that they produce insignificant levels of acid gas compared to the fossil fuels they replace and are considered CO2-neutral because the carbon dioxide produced is used in the growth cycle of renewable fuel sources.

As the costs of conventional fuels rise, coupled with growing concerns about global warming and the need for more eco-friendly technologies, renewable fuels provide a sensible alternative. However, Tom Giaier, president, cautions, “This is a niche market, and while we all need to think about ways to implement green technology, the fact is that so-called alternative fuels make the most sense when they are located where there’s an abundant source of the recyclable materials. For example, we’ve done several systems that use chicken litter as a fuel source. This is a win/win for a poultry farmer because not only does he eliminate the expense of what he’d otherwise have to pay to buy fuel, he also eliminates the cost of having to cart off the waste material. But, if you’re not a poultry farmer, it doesn’t make much sense to buy chicken litter to power your boiler. Same with any biomass fuel. If you’re not generating the waste product that can be used as a fuel source, it really doesn’t pay to have a biomass stoker or combustion system.”

He adds, “It’s kind of the thing today to be green and all, but sometimes people jump on the bandwagon without thinking it through. We’ve actually turned down some jobs because we didn’t think a biomass fuel source was practical. As a kind of quiet company that gets work because of our reputation, we’re always looking to do what’s right for the customer. If it isn’t right, we’re not going to do it, for their sake as well as ours.

The company is headquartered in Monroe, Mich. and employs 90. While most product designs are custom, it out sources certain pre-built components that are assembled in various facilities in the Michigan and Ohio area. In some cases, final assembly takes place on-site, though Giaier says that in many cases the customer has the expertise to do the installation.

Detroit Stoker utilizes an international network of sales representatives who market its stokers and combustion systems to major boiler makers. “We team with the boiler companies to design and install a system for the end-user,” Giaier notes.

NICHE LEADER

He also points out, “Detroit Stoker is unique in this niche in that biomass stokers and combustion systems is all we do, and we aren’t part of a larger company. In fact, most of our competition is owned by the boiler companies, the very people we sell to. What typically happens is that even though the boiler company has its own biomass combustion products, it will turn to us because we have the technology or expertise for an application that it doesn’t have. We’re really the only player that concentrates exclusively in this niche, so we are well-positioned as the market leader.”

That’s not only because of its existing technology and history of success, but also the research and development it commits to biomass fuel. Detroit Stoker partners with the University of Utah to experiment with and test methods and technologies to improve performance results, from both cost and environmental standpoints.

One example is Detroit Hydrograte® Stokers, which combine advanced spreader stoker technology with automatic ash discharge and water-cooled grates. The spreader firing principle is the most widely accepted, proven and user friendly means of burning biomass fuels. Sized fuel is metered to a series of distribution devices which spread it uniformly over the stoker grate surface. Minimum fuel supply on the grate and automatic ash discharge reduce furnace upsets and provide better control of emissions. The high burning rates permissible with the spreader stoker concept minimize the grate area required – a prime consideration in retrofit applications.

Detroit Stoker burners are available in standard capacities ranging from 15 to 200 MBtu (million British Thermal Units) per hour and can be installed in multiples to meet virtually any requirement for input capacity or flame length. These low NOx (nitrogen oxide) burners combine high efficiency and reliability while meeting virtually all existing federal and state air quality standards, including tough California regulations. They are particularly suitable for co-firing solid fuel installations or as replacements for solid fuel boilers. They can be used as auxiliary units for start-up and continuous operation during low-load periods. Offered in both natural gas and oil-fired models, these advanced burners are available for replacement purposes, as retrofits or as turnkey combustion systems.

Detroit Stoker also manufactures ash handling systems for effective, economical and trouble free disposal of ash from units burning coal or solid refuse fuels. It also makes a line of rotary seal feeders that handle abrasive and high temperature materials.

In addition to new systems and products, Detroit Stoker provides worldwide repair and parts services. “The average life expectancy of this equipment is at least 30 years; in fact, it’s more likely a customer will replace one of our products because they’re replacing their boiler design, not because our product is failing from old age. So, service is also a large part of our business,” Giaier says.

Detroit Stoker repairs and rebuilds all types of combustion, ash and fuel handling systems, whether built by Detroit Stoker or other major manufacturers. The company also converts existing systems from solid fuel to gas or oil-firing using high-efficiency, low-emission Detroit manufactured low NOx burner systems. Detroit Stoker offers complete, turnkey burner installation in existing package boilers or fielderected systems for use in start-up or under low load conditions. The service group provides the necessary engineering, all major equipment, parts, installation labor and start-up supervision to ensure that the system is brought back on-line as quickly as possible.

Detroit Stoker’s field personnel perform complete inspection and combustion tune-ups on all systems. Our program includes full inspection of combustion equipment, testing of flue gasses, all necessary adjustments to optimize combustion efficiency, and full emission testing. “The technology of the product itself basically hasn’t changed much since the 1940s,” Giaier notes. “But what we offer are a set of advanced tools that not only make the best use of alternative fuels, but also responds to the needs of the marketplace. Because this is our focus, we have the resources and know-how to commit to solve any customer problem, from the tried and true to the very difficult. In fact, we like to say that the more difficult a customer need, the better we like it. Responding to challenges is how this company was built.”

Consequently, customers can be sure that when they choose Detroit Stoker, nothing will go to waste.

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