Virtual Environmental Lab Monitors Harsh Emissions
Oak Ridge National Laboratory (ORNL; Oak Ridge, TN; 423-576-8380) needed an Internet-based system to monitor and control harsh environmental experiments. Using National Instruments (Austin, TX) LabVIEW, ORNL met this need by creating a PC-based virtual instrument system called the Harsh Environment Laboratory (HEL) to simulate industrial stacks and steam vents.
ORNL's Environmental Solution
HEL Technology
Remote Access
Benefits Of Virtual Labs
ORNL's Environmental Solution (Back to Top)
Online sampling and analysis are extremely difficult in harsh environments that contain incinerator stacks or exhaust vents, primarily because these environments can include corrosive high temperatures, steam, and aerosols. These traits present a variety of problems from simple water vapor condensation in sampling lines, to sensor failure or instrument performance degradation, to a lack of fundamental understanding regarding the samples' physical states.
To enhance core capabilities related to process and emissions monitoring, ORNL constructed the HEL. A virtual laboratory, the HEL simulates industrial stacks or steam vents that have high-humidity and elevated-temperature gas streams. The HEL can demonstrate stack models and can serve as an experimental platform on which to address fundamental issues such as materials stability and particle-phase/vapor-phase equilibrium in harsh environments. HEL experiments also address continuous emissions monitoring issues that relate to next-generation instrumentation.
Because the test bed demonstrates the virtual laboratory concept, instrument manufacturers, researchers, and other users can remotely conduct experiments.
The HEL test bed consists of a vapor generator flanged to a stack section. The vapor generator has six inlet ports, a quartz heater, a water nebulizer, auxiliary heating, and a waste drain and collector. Gas flow through the generator has remote on/off control and is metered through individual mass-flow meters. The stack portion is outfitted with flanges that have ports through which samples may be drawn, probes can be inserted, or the stack interior can be viewed. Stack effluent gas is collected and purified before being exhausted from the building.
The data acquisition and control system (DACS) for the local experiment is comprised of a server computer, LabVIEW software interfaces, and data-acquisition hardware. Client applications communicate through the Internet, allowing users to remotely control experiment parameters and work with real-time data such as stack temperatures, relative humidity, pH, flow rates, gas concentration, and prototype sensor outputs. Data are viewed and stored at both the server and client locations. Video teleconferencing helps remote users to feel that they are at the test bed.
HEL Technology (Back to Top)
The HEL DACS server used in the test bed features a 100 MHz Pentium PC running Windows 95. This is interfaced to a Phoenix Contact InterBus-R command and control module (CCM) with a National Instruments AT-485/2 serial interface board for RS-485. Analog signals from sensors and monitors are interfaced to the CCM through analog and thermocouple input modules. Digital input and output modules control gas and vapor selection and status indication.
Three video cameras are used at the HEL. A Canon VCC1 color video camera views the test bed area, while the pan-tilt-zoom functions are remote controlled and interfaced to the server through the onboard CCM RS-232 serial interface. The second and third cameras (both are color CCD telecameras from Howard Enterprises Inc.) are used to view the interior of the test chamber and conduct video conferences. Camera output can be locally or remotely selected. Full duplex video transfer over the Internet is accomplished using CU-SeeMe software from White Pine Inc. (Nashua, NH) or through a public offering from Cornell University (Ithaca, NY).
The LabVIEW server application controls test-flow parameters; collects, converts, displays, and stores data; transfers data via the Internet to client applications; and selects video outputs. The server application also receives remote commands from the client application via the Internet. These verify client authenticity, transfer encrypted real-time test data on request, execute test-flow parameter changes, transfer feedback indicators, select video output, control camera pan/tilt/zoom functions, and verify safe test conditions in real time.
Remote Access (Back to Top)
When the client application links to the server application through the Internet, it transfers an authentication code. Upon validation, the server transfers encrypted data, camera selection, triaxial camera positions, and valve control status. The client decrypts the data and displays it in graphical and digital formats, including a status indicator for camera selection, tri-axis camera position, and valve control.
Validated users can store data, select data points, choose from six graphical and digital displays to present the data, and request control of the remote system. If control is granted, the remote user can change test-flow parameters, video-display selection, and triaxial camera position. The selected video image is displayed using CU-SeeMe software.
A successful HEL data-acquisition system relies on two types of connectivity. Because the environment that is being monitored is quite harsh, it is necessary to isolate the signal conditioning and data-acquisition hardware from the server computer. This challenge was met with Phoenix Contact front-end equipment with a RS-485 communication link to each PC via the National Instruments AT-485/2 board. Reliable command handlers between the server program and the data-acquisition equipment were developed using serial-port LabVIEW virtual instruments (VIs).
To make data available to client computers at remote sites, the system required Internet connectivity. To meet this need, the LabVIEW-supplied VIs for TCP/IP were expanded to provide necessary services for both the server and client software. Now, several clients can make socket connections to the server to monitor HEL data. Only one client at a time can control the server output capabilities to change experimental conditions and/or to control the video returned by the CU-SeeMe connection.
Benefits Of Virtual Labs (Back to Top)
Using the Internet for data reporting, experiment control, and video conferencing gives remote users access to the HEL for a low cost. Even clients without direct Internet attachments can use dial-in Internet connections to access the HEL.
By creating a virtual facility, the DOE fosters collaboration and allows researchers around the country to conduct experiments at the same facility—without leaving their desks. Because of this, the HEL solves the challenges of remote operation and control while giving users a "presence" at the facility.
Scientists, engineers, instrument developers, manufacturers, and end-users can remotely operate and control performance-monitoring experiments, transfer and view data, and perform teleconferencing simultaneously. Most importantly, all of these functions can be performed in real time. Through this research, the DOE hopes to reduce costs, accelerate the acquisition of scientific knowledge, and improve final products.
For more information, call William Holmes Jr. of ORNL at 423-576-8380, or e-mail holmeswjr@ornl.gov.
Written by W. Holmes Jr., D. E. McMillan, and R. R. Smith of Oak Ridge National Laboratory.