EUtech Reduces Coal Power Plant Emissions Using NI Hardware and Software

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"Combined with EUtech’s innovative laser-based technology, NI hardware and software formed a flexible, environmentally beneficial, and cost-saving system that provides high sampling rates, accurate measurements, and advanced processing capability. "

- Max Starke, EUtech Scientific Engineering GmbH

The Challenge:
Creating a mobile data acquisition and control system for a laser-based probe to measure coal particles in coal pipes under severe operating conditions, which helps optimize coal combustion efficiency and lessen the effects of coal burning on the environment by reducing greenhouse gases such as nitrous oxide and carbon dioxide.

The Solution:
Using the NI USB-5133 bus-powered digitizer, the NI USB-6009 multifunction data acquisition (DAQ) device, and NI LabVIEW software to acquire and process EUtech’s mobile, laser-based coal analyzer signals.

Author(s):
Max Starke - EUtech Scientific Engineering GmbH
Michael Schreiber - EUtech Scientific Engineering GmbH
Michael Haug - EUtech Scientific Engineering GmbH

Coal Particle Size in Combustion

Coal particle fineness is a key parameter in determining combustion efficiency and quality in thermal power plants. Coal particle size influences ignition delay, combustion efficiency, loss of ignition (LOI), emission levels, flow characteristics, furnace residence times, nitrous oxide and carbon dioxide emission levels, as well as slagging and fouling tendencies. However, determining particle size is difficult in these systems because the particle-size spectrum may undergo rapid changes that vary not only with the type of coal and composition, including water content, but also with the mill setup, operating conditions, and machine wear and tear.

Knowing the coal particle size and distribution helps optimize combustion and boiler performance. With modern coal burning techniques, coal-fired plants reduce nitrous oxide emissions up to 40 percent, increasing thermal efficiency and lowering overall coal combustion. In turn, this can lead to  significant negative greenhouse gas emission reduction.

Traditional Method for Measuring Particle Size

Coal particle size plays a significant role in combustion, but we lack a flexible and reliable online and in-line measuring system.

The traditional method to measure particle size is to collect samples from the coal pipe and then sieve in a laboratory to measure the particle size distribution. The resulting latency time between sample collection and results makes direct correlations between operational mill and boiler settings impossible. Furthermore, inherent variability in coal properties and measurements requires multiple analyses on the same sample to obtain accurate results.

Sampling and sieving seldom occurs because the method is cumbersome and costly, and the time delay between sampling and analysis makes it impossible to use the data for feedback control. If possible, optimization using this method is always limited to static settings.

Online Measurement Using NI USB-5133 Bus-Powered Digitizer and NI USB-6009 Multifunction DAQ Device

In response to the industry’s need for a mobile data acquisition and control system for a laser-based probe to measure coal particles, NI Silver Alliance Partner EUtech developed a unique suite of solutions to optimize operation, improve availability, and reduce fossil-fired steam generator emissions of fossil-fired steam. The system uses laser-based online technology, as well as the USB-5133, USB-6009, and LabVIEW for signal acquisition, processing, and control.

One of our solutions is the EUcoalsizer system, which uses a high-speed NI digitizer and multifunction DAQ device to measure coal pipe particle size, velocity distribution, and mass flow in-line and online as well as the temperature inside the coal pipe. Spatially resolved cross-sectional distributions become available as we move the probe through the coal pipe.

System Setup

We use an adapter to connect to the coal pipe and directly apply the system, removing any mechanical interaction with the particles that can bias the measurement. The system works continuously, delivers results online, and can integrate into an existing monitoring and control environment. An intuitive graphical user interface monitors handling.

The measuring system consists of the following:

•         Measuring probe inserted into the coal pipe

•         Pneumatic and electrical control unit that controls the purging and cooling air supply

•         USB-5133 and USB-6009 to control measuring probe data acquisition

•         Notebook with the control software developed in LabVIEW

The measuring probe needs to connect only to the pneumatic unit and to the EUcoalsizer control console to operate the system. We automatically monitor the system, and, if problems arise, the operator is immediately notified. The lance position is automatically recorded to facilitate system handling and data allocation. The PC, which uses LabVIEW for data processing and user interfacing, handles data analysis, evaluation, and data storage. The system setup also includes automatic reporting that we can calibrate according to user-defined requirements.

We applied a laser system using a time-of-transition technique to solve the accurate data acquisition problem. The EUcoalsizer system uses data collected from the USB-6009 to measure particle size distribution, density, velocity, and temperature within a measurement volume placed at the tip of an insertable probe. We traversed the lance through the pipe to measure a spatially resolved distribution along the cross section of the coal pipe.

Coal particles crossing this volume intersect a lattice formed by closely spaced laser beams. A correspondingly spaced array of fibre optical detector elements detects the intermittency pattern on the opposite side. We conducted simultaneous, straightforward particle velocity and size spectrum measurements with this arrangement. We determine the particle velocity (vp) using frequency analysis methods, and we determine the particle size (xp) by the time of flight (tp) and the particle velocity.

The procedure uses high-rate single particle measurements. Tunable statistical filtering methods, realized using LabVIEW, monitor double counts, particle coverage effects, and other elements. The system achieves high-measurement rates and is highly reproducible. Unlike other methods, including laser diffraction, the system does not require calibration.

We acquired the sensor signals with a USB-5133. The USB digitizer performance, which is two simultaneously sampled channels up to 100 MS/s with 8-bit resolution, measures the required high-data rates and the particle evaluation, typically 200,000 counts, in less than two minutes. In Figure 3, we integrated the complete electrics in the EUcoalsizer control box. The USB-6009 realizes the temperature, flow switch signals, and valve and switch control.

Using LabVIEW, EUtech developed a user interface for system control and monitoring. EUcoalsizer results are instantly available once we insert the lance in the pipe. Users adjust diagrams to their needs. Figure 4 shows examples of the user interface.

Optimizing Combustion Efficiency and Boiler Performance with NI Hardware and Software

This application demonstrates how we simplified and improved a formerly expensive and labor-intensive coal particle measurement process using National Instruments high-speed digitizers, multifunction DAQ devices, and LabVIEW. Combined with EUtech’s innovative laser-based technology, NI hardware and software formed a flexible, environmentally beneficial, and cost-saving system that provides high sampling rates, accurate measurements, and advanced processing capability. In accordance with the key values of NI, this application also helps optimize coal combustion efficiency to help reduce greenhouse gas emissions.

Author Information:
Max Starke
EUtech Scientific Engineering GmbH
Dennewartstr. 25-27
Aachen 52068
Germany
Tel: +49 241 963 2380
Fax: +49 241 963 2389
starke@eutech.de

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