System Solutions for Optimizing Exhaust Emission Control Systems
This paper was presented at Power Gen Asia, November 2nd, 2010
There is a growing percentage of Decentralized Energy (DE) systems globally and with it comes an increased need to minimize the exhaust emissions produced by these sources. Modern exhaust emission control systems are very effective in reducing gaseous and particulate emissions when applied properly. However, competing system objectives such as cost, backpressure, packaging space, serviceability and noise control often present serious challenges to system designers. This paper provides a brief overview of the challenges associated with integrating exhaust emission control in reciprocating engine stationary power generation systems and offers potential system level solutions and design considerations for integration of efficient and cost-effective exhaust emission control systems.
Combined Cycle Systems for the Utility Industry
Combined Cycle systems are efficient low cost systems that provides assurances of performance and operating objectives. Combined Cycle systems can be customized to the utility needs and preferences. They offer attractive economical reliable power generation. Operating flexibility of Combined Cycle power generating warrant their consideration for most power generation applications.
High Temperature Quiet Flow Test Facility
Universal has developed a high temperature, quiet flow test facility for the testing and evaluation of exhaust silencers and silencer materials. This facility is driven by a rotary positive displacement blower delivering up to 110 m3/min [4000 cfm] of airflow. This airflow is put through both a passive and active silencer to achieve minimal uncontrolled noise in the test stream. Controlled sound is injected into the airflow by a set of loudspeakers in a mixing/settling chamber. The airflow is heated up to 540C [1000F] by a 144Kw electric heater just prior to entering the test section. The test section is rated for a 10 cm [4 in] diameter flow path and up to 1.8 m [6 ft] long sample. The outlet of the test section exhausts outside the test building and a microphone measurement system measures the radiated sound level. This facility allows tests to be run with flow, sound level and temperature controls to obtain in situ measurements of silencer performance including insertion loss.
Low Outer Skin Temperature Turbine Exhaust System Design
Universal's internally lined turbine exhaust systems provide a low skin temperature exhaust system while reducing size and weight. Internal insulation protected by a stainless steel liner provides a thermal barrier to the hot exhaust gas. Thermal conduction between the inner liner and the outer skin are prevented with the use of Universal's scallop bar design.
Noise Sources and Solutions for Mobile Vacuum Trucks
Data are presented on the noise sources of mobile vacuum trucks as they are used as a stationary source, especially the rotary positive displacement blowers used to create the vacuum. These are straight lobe blowers manufactured by several companies. In addition to the expected intake and discharge noise, the bypass or jet port noise must be considered and may be the dominant noise source. Several solutions are discussed as well as limitations on space and weight. Once the blower noise is reduced, more traditional noise reduction of the engine, transmission and cooling fan noise must also be done.
Universal’s Exhaust Stack Recommendations
It is common for the industry to refer to noise in terms of frequency, while the science of noise control engineering is more a function of the wavelength of noise. Low frequency noise is characterized by long wavelengths that are difficult to attenuate by conventional noise control techniques. The high gas turbine exhaust temperatures exacerbate the problem (wavelength increases as the speed of sound increases, which increases with temperature). Additionally, these techniques create an energy loss (pressure drop) that results in loss capacity (power output). The task is then to provide the required DIL while creating the minimum pressure drop possible.