Emissions Control in the North Sea
Diesel & Gas Turbine Worldwide - March 20007
Controlling the emissions from a diesel generator set is a fairly straightforward proposition, even given that the level of control gets more and more precise with every new tier or regulation. However, when the generator sets are 150 miles offshore in the North Sea, the project takes on a whole different and extreme set of challenges.
CleanAIR Systems, Santa Fe, NM, recently finished an installation of its regenerating catalytic units on a pair of diesel gen-sets on a BP oil platform located 150 miles north of Aberdeen, Scotland.
According to CleanAIR Systems’ Project Coordinator, Daniel Serrando, the company was contacted by BP to install its catalytic units on two Caterpillar 3516-powered diesel gen-sets.
The platform in question is part of the Eastern Trough Area Project (ETAP). BP, Serrano said, was concerned that diesel exhaust produced by the platform’s two stationary generators would enter the crew’s living and office space through the ventilation intake during ETAP’s annual.
Turn Around (TAR). TAR is a brief period each year when essential maintenance and modifications are made to the platform.
During these few weeks, stationary diesel-powered generator sets are used for power for the platform and its 100-person crew, rather than the platform’s larger gas turbines, saving BP a considerable amount in operating costs.
According to Ross Lloyd, BP project coordinator, “the aim was to provide a permanent solution to the risk of hydrocarbon exhaust entering the accommodations during TAR. CleanAIR was chosen because they were the only supplier with the ability to manufacture regenerating catalytic units of this size that were approved and tested on our Caterpillar 3516 engines.”
According to Serrano, CleanAIR engineers in tandem with engineers at BP and Wood Group designed a filter/silencer system for the ETAP stationary generators to reduce emissions of particulate matter, hydrocarbons and carbon monoxide by 90%.
Size was critical in designing this one-of-a-kind system. The generator sets have been used as auxiliary power for the platforms for a number of years. The CleanAIR systems were replacing existing silencer-only packages, and the new silencer/catalytic unit had to fit into an existing envelope of roughly 150 in. long by 111 in. wide and 56 in. high.
The silencer/catalyst is housed in a 316 stainless-steel enclosure, with every weld requiring a non-destructive test. The entire 4000 lb. Package, in essence, became a pressure vessel and had to pass both a pressure test and pressure decay test. Skin temperature also had to be kept below 150 degrees F to meet platform fire safety regulations.
Further, Serrano said, the entire package required things not normally found in a diesel gen-set installation. The lifting lugs, for example, had to be able to withstand 80% of the weight of the package. He also noted that the entire installation was inspected by an independent team of examiners, which required extensive documentation of all the tests and design features of the system.
Using an integrated manufacturing approach, CleanAIR’s Permit diesel particulate filters were installed within a silencer. Due to the compact installation area, which also limited access to the internal filters housed within the exhaust silencer, an application-specific design was the only solution, Serrano said. This was not an off-the-shelf product and in the end, an unusual one-of-a-kind design allowed for the front end of the silencer to be removed for direct contact with the CleanAIR PERMIT™ Filters.
The CleanAIR’s PERMIT™ system is a catalyzed diesel particulate filter that regenerates when the exhaust temperature is above 572 degrees F for 30% of the operating time when operating on ultra-low sulfur diesel fuel. Typically, the system is supplied as a muffler or silencer replacement unit to fit in the exhaust system.
With higher sulfur fuels, the regeneration temperature requirements rise to between 620 degrees and 680 degrees F. Higher sulfur fuel, greater than 50 ppm, will not damage the catalyst coating or the ceramic filter, CleanAIR said.
The PERMIT™ Filter is made of a ceramic honeycomb with hundreds of parallel channels. To control the flow of exhaust gas, 0.5 in. long plugs are placed in the end of 50% of the channels, which form a checkerboard pattern. Plugs are also placed in the other end of the filter to form the same checkerboard pattern, but offset by one. This checkerboard arrangement of plugs forces the exhaust gases through the porous, thin ceramic honeycomb walls. When the gases carrying the carbon particles flow through the fine pores of the walls, the carbon particles are filtered out.
The process of diesel particulate matter collection begins as soon as the engine is started and continues while the engine is operating. As the carbon particles are collected on the ceramic walls, the backpressure of the system increases.
When the temperature of the exhaust is equal to or greater than 572 degrees F for 30% of the duty cycle, the catalyst interacts with the collected particulate to burn the particulate into carbon dioxide, a gas and water vapor that passes through the filter. This regeneration process is dependent upon exhaust temperature and fuel sulfur content. While the exhaust temperature does not have to be above 572 degrees F all the time, the more time above this temperature, the cleaner the filter will be and the lower the back pressure.
CleanAIR said carbon monoxide and hydrocarbon reductions are achieved when the exhaust gases interact with the catalyst on the ceramic filter. As the exhaust gases come in contact with the catalyst, a chemical reaction takes place that oxidizes the gases. The oxidation process turns carbon monoxide into carbon dioxide, and hydrocarbons into water and carbon dioxide.
For the BP installation, timing was also a critical parameter as the units had to be operational for the short TAR window. Serrano said it took eight months from initial discussions to design, manufacture, shipping and installation, with final installation taking place in July of 2006.
Controlling the emissions from a diesel generator set is a fairly straightforward proposition, even given that the level of control gets more and more precise with every new tier or regulation. However, when the generator sets are 150 miles offshore in the North Sea, the project takes on a whole different and extreme set of challenges.
CleanAIR Systems, Santa Fe, NM, recently finished an installation of its regenerating catalytic units on a pair of diesel gen-sets on a BP oil platform located 150 miles north of Aberdeen, Scotland.
According to CleanAIR Systems’ Project Coordinator, Daniel Serrando, the company was contacted by BP to install its catalytic units on two Caterpillar 3516-powered diesel gen-sets.
The platform in question is part of the Eastern Trough Area Project (ETAP). BP, Serrano said, was concerned that diesel exhaust produced by the platform’s two stationary generators would enter the crew’s living and office space through the ventilation intake during ETAP’s annual.
Turn Around (TAR). TAR is a brief period each year when essential maintenance and modifications are made to the platform.
During these few weeks, stationary diesel-powered generator sets are used for power for the platform and its 100-person crew, rather than the platform’s larger gas turbines, saving BP a considerable amount in operating costs.
According to Ross Lloyd, BP project coordinator, “the aim was to provide a permanent solution to the risk of hydrocarbon exhaust entering the accommodations during TAR. CleanAIR was chosen because they were the only supplier with the ability to manufacture regenerating catalytic units of this size that were approved and tested on our Caterpillar 3516 engines.”
According to Serrano, CleanAIR engineers in tandem with engineers at BP and Wood Group designed a filter/silencer system for the ETAP stationary generators to reduce emissions of particulate matter, hydrocarbons and carbon monoxide by 90%.
Size was critical in designing this one-of-a-kind system. The generator sets have been used as auxiliary power for the platforms for a number of years. The CleanAIR systems were replacing existing silencer-only packages, and the new silencer/catalytic unit had to fit into an existing envelope of roughly 150 in. long by 111 in. wide and 56 in. high.
The silencer/catalyst is housed in a 316 stainless-steel enclosure, with every weld requiring a non-destructive test. The entire 4000 lb. Package, in essence, became a pressure vessel and had to pass both a pressure test and pressure decay test. Skin temperature also had to be kept below 150 degrees F to meet platform fire safety regulations.
Further, Serrano said, the entire package required things not normally found in a diesel gen-set installation. The lifting lugs, for example, had to be able to withstand 80% of the weight of the package. He also noted that the entire installation was inspected by an independent team of examiners, which required extensive documentation of all the tests and design features of the system.
Using an integrated manufacturing approach, CleanAIR’s Permit diesel particulate filters were installed within a silencer. Due to the compact installation area, which also limited access to the internal filters housed within the exhaust silencer, an application-specific design was the only solution, Serrano said. This was not an off-the-shelf product and in the end, an unusual one-of-a-kind design allowed for the front end of the silencer to be removed for direct contact with the CleanAIR PERMIT™ Filters.
The CleanAIR’s PERMIT™ system is a catalyzed diesel particulate filter that regenerates when the exhaust temperature is above 572 degrees F for 30% of the operating time when operating on ultra-low sulfur diesel fuel. Typically, the system is supplied as a muffler or silencer replacement unit to fit in the exhaust system.
With higher sulfur fuels, the regeneration temperature requirements rise to between 620 degrees and 680 degrees F. Higher sulfur fuel, greater than 50 ppm, will not damage the catalyst coating or the ceramic filter, CleanAIR said.
The PERMIT™ Filter is made of a ceramic honeycomb with hundreds of parallel channels. To control the flow of exhaust gas, 0.5 in. long plugs are placed in the end of 50% of the channels, which form a checkerboard pattern. Plugs are also placed in the other end of the filter to form the same checkerboard pattern, but offset by one. This checkerboard arrangement of plugs forces the exhaust gases through the porous, thin ceramic honeycomb walls. When the gases carrying the carbon particles flow through the fine pores of the walls, the carbon particles are filtered out.
The process of diesel particulate matter collection begins as soon as the engine is started and continues while the engine is operating. As the carbon particles are collected on the ceramic walls, the backpressure of the system increases.
When the temperature of the exhaust is equal to or greater than 572 degrees F for 30% of the duty cycle, the catalyst interacts with the collected particulate to burn the particulate into carbon dioxide, a gas and water vapor that passes through the filter. This regeneration process is dependent upon exhaust temperature and fuel sulfur content. While the exhaust temperature does not have to be above 572 degrees F all the time, the more time above this temperature, the cleaner the filter will be and the lower the back pressure.
CleanAIR said carbon monoxide and hydrocarbon reductions are achieved when the exhaust gases interact with the catalyst on the ceramic filter. As the exhaust gases come in contact with the catalyst, a chemical reaction takes place that oxidizes the gases. The oxidation process turns carbon monoxide into carbon dioxide, and hydrocarbons into water and carbon dioxide.
For the BP installation, timing was also a critical parameter as the units had to be operational for the short TAR window. Serrano said it took eight months from initial discussions to design, manufacture, shipping and installation, with final installation taking place in July of 2006.
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