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The SHOCKSystem™ developed and designed by Pratt & Whitney, is an online detonation cleaning product that provides cleaning of backpass regions found in coal-fired power generating stations.
Opportunity Seized: Power Plants continue to switch to and be built for PRB coal use. This specific type of coal has higher ash content than other types, but is less expensive to mine, transport and burn. Therefore power plants are burning this coal to achieve their electrical output. The higher ash content causes more fouling and ash deposits to form and accumulate in the backpass gas lanes. This negatively effects power production. The plugged gas lanes reduce the plants load capability, overall productivity and profitability of domestic coal-fired power generation stations.
Innovative Solution:
A) The design and development of the SHOCKSystem™ allows for the continuous removal of accumulated fly-ash deposits while the boiler remains in operation (online). This new technology is being sought after because existing technologies are unable to provide the additional cleaning and environmental capabilities. Pratt & Whitney's solution is the SHOCKSystem™. The SHOCKSystem™ creates high pressure blast waves, accelerating from sub to supersonic speeds. The simple process of creating these detonations consists of: mixing, containing and sparking fuel within a chamber. The shock wave that ensues travels the length of the combustor reaching supersonic speeds before existing. This detonation wave has a force which is measurable both in speed but also in pressure. The created pressure waves have the energy required for removing the sintered and unsintered ash deposits.
B) The SHOCKSystem™ is unique in that it has many built-in cost-saving attributes over products that have been around for decades.
- The combustor contains the detonations and directs the force as pressure pulses to specific fouled regions. The system combines the strength of supersonic blast waves with the blow-down jet for effective and non-eroding cleaning.
- A small installation footprint is achieved by installing parallel to boiler walls. Conventional sootblowing products are installed perpendicular to boiler walls.
- Perpendicular installations require wide open deck spaces, whereas installing parallel to the boiler wall minimizes these requirements, cutting steel costs.
- Maintenance costs are drastically reduced, because the SHOCKSystem™ has very few moving parts. Competing technologies require extensive lubrication and replacement of moving components.
- The SHOCKSystem™ is designed to operate in parallel with boiler operations, thus eliminating outage time and the associated outage costs.
Results: Since first publicly presenting in December of 2005, two (2) major utility companies have purchased economizer cleaning systems. Dating back to 2002, ten different utility companies have partnered with Pratt & Whitney, requesting demonstrations in over 20 individual boiler units.
In an economizer demonstration, at a 500+ MW PRB boiler, a single combustor decreased economizer exit gas temperature by 50°F. This was verified by plant and B&W engineers who stated that boiler efficiency improved by 0.24%, from just cleaning one side of the economizer. In a separate 500+ MW staggered fin-tube economizer demonstration, the economizer gas temperature differential also increased by 50°F. In a 600+ MW horizontal reheater, a 20% increase in reheater cleanliness factor was verified by plant engineers. A 45°F decrease in primary superheater exit gas temperature was achieved in a primary superheater demonstration. Yet another economizer demonstration, this time in an 800+ MW boiler, saw a 30°F - 40°F increase in economizer gas temperature differential, confirmed by plant engineers. In 75% of all demonstrations, the power plants have requested an installation proposal.
The flagship installation site, a 1300 MW boiler, has five combustors that were installed. A 10% increase in economizer heat transfer co-efficient, a 15°F increase in economizer gas temperature differential and
320,000 pounds of ash were removed over a five day period. That unit has eliminated its annual ash removal outage because of the continuous online detonation cleaning provided by the SHOCKSystem™.
For ongoing details about the award and the Conference, see www.ctqualityaward.org.
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