N3-ER – System Description
The sensing system
The system utilises either EMS6 AC Coupled Technology or ET301 DC technology, comprising a duct/stack-mounted IP65 electronics housing with integral sensing element protruding into the duct. As particles travel through the process they develop a charge which is transferred as the particle passes or impacts the sensing element. The resulting current is amplified, filtered, rectified and further filtered looking only at the AC component. This gives a linear representation of the concentration in the gas stream. The reason for measuring the AC component is that compared to the DC component, the electronics are more sensitive. The AC signal is substantially less affected by influences such as amplifier noise and process parameters which includes the build-up of process dust on the sensing element. The EMS6 totally filters out 50Hz and 60Hz frequencies related to the mains supply. The EMS6 linear representation of concentration has been validated by independent laboratories and has also been tested and certified for monitoring dust emissions according to the UK Environment Agencies ‘MCERTS’ standards.
Data Transfer, Processing & Storage
The main user interface of the system comprises an advanced PLC with integrated HMI panel. The PLC is connected to one or more EMS6 using an RS485 multi-drop serial communications line and utilises the industry standard MODBUS TRU protocol. Data from the EMS6 monitoring heads is transmitted in response to routine requests by the PLC. The PLC applies calibration factors, averages and displays the data as well as storing it to a removeable data storage card. The HMI panel provides operators with a simple yet comprehensive and convenient interface that allows them to readily observe real-time and historical data as well as alarm conditions for each of the monitoring points. The panel also provides a mechanism for initial configuration of the system and ongoing diagnostic information. Stored data can easily be transferred to a remote PC for secure backup storage, analysis and reporting purposes. A user at the remote PC can also directly view and control the PLC.
Like all particulate monitoring systems for accurate quantitative measurement, the system must be calibrated against a standard reference method. There are many accredited laboratories who can perform such calibrations and upon completion of the calibration exercise these laboratories supply calibration reports identifying calibration factors for each point concerned. The HMI panel provides a simple user interface to automate this calibration process. The function removes the need for customers to get bogged down logging data and calculating new calibration factors.
Configuration and Reporting
The system is extremely flexible and can be configures to suit specific application requirements. Systems are supplied with MS Excel templates that automatically access data files and produce fully formatted reports suitable for submissions to environmental regulators. Reports are generated with just a few keystrokes, saving a considerable amount of valuable time.
Configuration extends to:
- The number of sensing heads connected to the system
- Alarm level and ranges
- Operator displays
- Hardware configurations
EMS6 Monitoring Heads
Each head is self-contained monitoring until with a 1” BSPT male thread, allowing connection to a duct-mounted 1” BSPT socket. Various sensing elements exist to suit different applications, including solid probes, flexible probes and even grid type arrangements for large areas. Each head is totally self-contained and has a single electrical connection which includes 12V DC power and the RS485 signal. All heads include internal selection of the MODBUS address and gain setting uses to optimise the measurement for the particular application. For very dirty applications a compressed air purge can be connected to minimise contamination at the base of the sensing element.
Network Junction Boxes
RS485 communications systems provide a very simple and cheap installation method for interconnecting instrumentation systems. The specification does, however, dictate that all devices are connected in a simple bus arrangement, which can sometimes be difficult to implement in practice. The ANJ1 Network Junction Box simplifies wiring layouts, easing compliance with the wiring requirements and reducing installation costs. They also provide an extremely useful diagnostic function when fault finding is required.
PLC/HMI Operator Panel
The PLC can be located almost anywhere in relation to the monitoring heads, subject to the total length of the cabling not exceeding 1km and as such can be conveniently located for operations personnel.
The units monitor status inputs enabling the system to discriminate between online and offline plant. This reduces false alarms and improves the accuracy of reporting.
There is also an option to provide integral or remote visual and audible alarms to raise attention when emission limits have been breached.
Furthermore a remote internet based support service is offered, providing remote software support and upgrades.
Complete off-the-shelf emissions compliance
Applications / Industries
Brochure / Data sheet