MicroCEM Continuous Emissions Monitoring System

---

Compact, accurate and powerful multi-channel emissions monitoring system Field-mountable, NEMA 4X (-30 to 50°C ambient temperature range) design eliminates the need for high-cost shelters Time-proven, highly accurate/sensitive gas detectors: paramagnetic O2, NDIR CO2, and chemiluminescence NOx detectors Electronics industry-standard PC-104 electronics Ultra-flexible pocket PC display/keypad HTML “web-browser” operator interface provides user display and interface from anywhere in the world via the world wide web Built-in data acquisition handling system 40 CFR Part 60/75-compliant Independent analysis and sample conditioning enclosures allow maximum installation flexibility Robust sample conditioning components; heated sample line not required

FEATURES AND APPLICATIONS Rosemount Analytical’s MicroCEM is a compact, field-mountable continuous emissions monitoring system that uses proven extractive monitoring technology, is coupled with state-of-the-art measurement detectors and uses a semiconductor industry-standard PC-104 electronics platform for maximum measurement, communications and processing capabilities. The MicroCEM system is designed to extract a sample gas, condition the sample, analyze the sample for the desired constituents and process the emissions data by utilizing the required calibration validation calculations/procedures and oxygen diluent corrections as stipulated in U.S. Environmental Protection Agency 40 CFR Part 60/75 regulations. The MicroCEM is also a data acquisition system that stores relevant raw/diluent corrected emissions, flags, calibrations and alarms for a period of three months. Note that emission reports as specified in the user’s particular state or federal regulations shall be configured andsubmitted by the user. An optional DAS can be provided by Rosemount Analytical. The housing is equipped with a weather-resistant NEMA 4X-rated enclosure and can handle ambient temperatures between -30 to 50°C. The housing is completely piped and wired and is accessible via bulkhead and terminal block termination points. All internal sample lines, fittings and valving are stainless steel, Teflon® and polypropylene. The components within the housing are completely accessible via front door access. A specially designed probe located on the sample conditioning enclosure extracts sample gas from the stack. The probe is constructed of 316 stainless steel. The probe tip is fitted with a sintered filter which can easily be changed and serviced. Calibration fittings are provided so that the system complies with guidelines for auto calibration as outlined in U.S. EPA 40 CFR Part 60/75 regulations.  Rosemount Analytical provides a solenoid-operated valve for automatic blowback of the probe. Instrument air supply must be provided by the user. A 4” mating flange is standard. The gas sample is cleaned by two levels of filtration: primary filtration is performed at the probe tip by using a 0.5 micron sintered filter. The secondary filtration occurs after the sample pump. The MicroCEM system provides a dry basis gas measurement. The sample gas is dried by a single-pass thermoelectric chiller. A dual pass chiller is optional for high-moisture samples. The chiller cools the sample to a temperature of 4°C, +/-1°. The moisture is continuously drained by a peristaltic pump while the dry sample gas is allowed to continue through the system.  The sample is then passed through a permeation-type, high efficiency dryer that cools the sample down to temperatures as low as -40°C. This low temperature cooling eliminates the need for heated sample line. Economical 1/4” size Teflon® tubing may be used for additional cost savings. The sample pump is a positive displacement pump with a moving diaphragm. All wetted parts are 316 stainless steel and Teflon®. In normal operation, the pressure at the pump outlet is set between 5 to 10 psi. The back pressure regulator is used to vent the sample gas flow in excess of that needed for analysis. This approach yields both minimum response time and higher analysis stability because of steady sample pressure. The ball valve assembly routes the stack sample into the sample conditioning stream. The calibration gas stream is routed through the probe and back into the sample-handling stream. Blowback air is routed through the probe. All vented gases or drained fluids are vented through bulkhead unions. The MicroCEM design includes an analysis enclosure which can be located at the sampling location at the bottom of the stack or in an environmental location. This enclosure is rated NEMA 4X and can be mounted beside the sample conditioning enclosure or remotely up to 250’ away. The oxygen measurement for diluent correction to determine emissions in the units is required by most regulations. To accomplish this, Rosemount Analytical uses a robust electrochemical oxygen detector. When sample gas is passed over a selective gas diffusion membrane, any oxygen present diffuses into an electrolyte. The oxygen is absorbed and is reduced to water. Lead oxide is developed at the anode. Electrons generated at the anode flow to the cathode of the cell producing a current that is proportional to the oxygen concentration. The principle offers a cost effective analysis with negligible interference, ease-of-maintenance and immunity from vibration. The standard range is 0 to 25%. The determination of oxygen is based on the measurement of the magnetic susceptibility of the sample gas. Oxygen is strongly paramagnetic, while other common gases are not. The detector is compact, has fast response (7 seconds) and a wide dynamic range. The long-life cell is corrosion-resistant and is easily cleaned. It has rugged self-tensioning suspension and is of welded, non-glued construction. The standard range is 0 to 25%. The non-dispersive infrared method is based on the principle of absorption of infrared radiation by the sample gas being measured. The gas-specific wavelengths of the absorption bands characterize the type of gas while the strength of the absorption gives a measure of the concentration of the gas component. The optical bench is employed using an infrared light source, analysis cell, a chopper wheel to alternate the radiation intensity between the reference and measurement side and a photometer detector. The detector signal alternates between concentration-dependent and concentration-independent values. The difference between the two is a reliable measure of the concen-tration of the absorbing gas component. The standard range capability between 100 to 1000 ppm is adjustable. The CLD consists of an ozone generator, chemiluminescence reaction chamber and a solid-state photodiode detector. The reaction chamber operates at atmospheric pressure, eliminating the need for the bulky vacuum pump found in other chemiluminescent instruments. The CLD reaction between ozone and nitric oxide is used to determine the presence of oxides of nitrogen (NOx in a sample gas. Nitric oxide and ozone readily react to form nitrogen dioxide in a electrically excited state. The excited NO immediately reverts to the ground state, emitting photons.The light intensity is measured by the photodiode detector. The standard range capability is between 10 to 1000 ppm and is adjustable. To minimize the effect of long-term zero and span drift in each analyzer detector, the PC-104 system controller periodically initiates a calibration cycle as specified by the user. This feature assures reliable, accurate data while minimizing the attention required by operating personnel. At adjustable intervals, the microprocessor will energize the appropriate valves which cause first zero, mid and then span gas to flow through each analyzer. When the analyzer readings stabilize, the microprocessor calculates the zero and span drift value for each detector. If a significant measurement deviation from the standard gas value exists, an alarm is generated and then reset. The PC104 is a standard, PC-based platform and performs all hardware control, as well as provides select data processing capabilities for the MicroCEM. Both analog and digital inputs and outputs are provided, including data correction and average values. The MicroCEM analysis enclosure internally employs a standard, robust pocket PC which runs on Microsoft® Windows CE.  The pocket PC is very flexible and allows the user to easily scroll through menus and view the data with the high resolution display. The pocket PC can also be removed from the enclosure and operated via a 4’ cable. Teflon® is a registered trademark of DuPont Films.