Coal fired power plants need to measure various pressures associated with the coal pulverising mills. The red dots in Figure 1 show the typical locations for these measurements for a Raymond Bowl type mill:
Figure 1.
1. The pulverising mill section.
2. The ductwork from the classifier carrying coal fines to the exhauster.
3. The exhauster: the fan and ductwork carrying pulverised coal and fines to the boiler burners.
A certain ‘sweet spot’ of pressure indicates smooth and proper operation of the mill, as well as the exhauster ductwork. If the pressure drops, the mill could be plugged or the fuel supply cut short; higher than normal pressure may indicate plugging of downstream coal ducts leading to the furnace. Incorrect pressures often lead to flame instability, productivity losses and pollution.
Plant maintenance operations often have to deal with problems associated with the long impulse lines that run to the pressure transmitters. The lines may plug as often as once a week, or even once a shift in some cases. A small air purge in the sensing line may be present to provide positive pressure to keep the coal out of the line, but wet coal following a rainstorm, for example, invariably leads to plugged lines. In the worst cases, maintenance technicians will have to drill out these plugged impulse lines.
Ideally, pressure would be sensed directly with the transmitter mounted on the mill, exhauster or ductwork. This arrangement eliminates the need for long, narrow impulse lines, but the pressure sensing diaphragm must withstand the abrasive effects of the pulverised coal travelling at high velocity.
The ABB solution: Diaflex coated sensor diaphragm
This application calls for a transmitter with a direct mount seal and nonstandard pressure diaphragm that can withstand severe abrasion. ABB’s 2600T direct mount seal pressure transmitters are available with diaphragms protected by a patented Diaflex coating of nano-structured material with hardness similar to diamond.
Diaflex consists of a quaternary coating based on titanium and silicon of the nitrides class. Using a process of physical vapour deposition, ABB coats the transmitter’s 316L stainless steel diaphragm seal to a thickness ranging from 3 to 5 µm. This deposition technique and thickness provide the necessary flexing sensitivity to measure pressure, while protecting the diaphragm from the abrasive effects of fast-moving coal particles. ABB’s all-welded remote seal technology adds superior performance and reliability.
The physical characteristics of Diaflex remain stable between -100 and 700°C, but the transmitter’s maximum working process temperatures are limited by the fill fluid. Diaflex coated diaphragms have proved their durability in this application and have resulted in significant savings in maintenance hours and more efficient burner management.
Water under pressure VEGA Controls SA
Pressure Measurement & Control
The need for real-time monitoring and precise control over water distribution has never been more critical. VEGA’s range of pressure sensors and level instruments plays an important role in ensuring that water systems operate efficiently.
Read more...Paper might carry the message, but pressure carries the process VEGA Controls SA
Pressure Measurement & Control
VEGABAR pressure transmitters are designed to address the unique challenges faced by the pulp and paper industry. Built for durability and precision, they ensure reliable pressure monitoring in aggressive environments.
Read more...Capsules, steam and cream VEGA Controls SA
Pressure Measurement & Control
African cosmetic brands are increasingly outsourcing production to specialised contract manufacturers who use automation and high-precision tools to ensure quality and adapt quickly to regulatory changes. VEGA’s suite of level and pressure measurement solutions offers a robust foundation for profitability and quality assurance.
Read more...World-class hoist maintenance ABB South Africa
Motion Control & Drives
In underground mining, hoists are among the most significant investments a company can make. ABB has developed ABB Care for Hoisting, designed to help mining companies transition from reactive or even preventive maintenance approaches to a truly predictive model, maximising hoist performance, extending asset life, and safeguarding operational continuity.
Read more...Differential pressure measurement made simple VEGA Controls SA
Pressure Measurement & Control
The VEGADIF 85 serves as an exemplary model of a differential pressure sensor. It combines universal applicability with high operational dependability and integrated overload protection, ensuring consistent performance even in the harshest conditions.
Read more...A milestone in electrical safety ABB South Africa
Electrical Power & Protection
Celebrating a milestone in electrical safety, ABB proudly marks the 100-year anniversary of its revolutionary Miniature Circuit Breaker.
Read more...Smart pressure monitoring drives energy efficiency ifm - South Africa
Pressure Measurement & Control
The ifm PG17 electronic pressure gauge is part of the company’s next-generation PG series. It integrates IO-Link technology, enabling seamless, loss-free data transmission via a 24 V signal.
Read more...Leading the way to the all-electric mine ABB South Africa
Editor's Choice IT in Manufacturing
Decarbonising the mining sector requires more than just new technology. ABB eMine provides a strong portfolio of electrification and automation solutions, consulting, partnerships and technology applications to support mining operations to reduce emissions and achieve operational cost savings and superior efficiency.
Read more...Electronic manometer with LED display ifm - South Africa
Pressure Measurement & Control
The new generation of PG type manometers are equipped with IO-Link and modern display units. Illuminated LED markings provide a quick overview of the current measured value. In addition to the various setting options for the display unit, IO-Link offers other advantages such as easy commissioning, quick sensor replacement and remote access options.
Read more...Family of analysers for smart and efficient chlorine measurement ABB South Africa
Sensors & Transducers
ABB has launched ChloroStar, a family of sensors, transmitters and accessories for accurate and reliable chlorine measurement and analysis that enable users in the water, wastewater and other industries to control chlorine more efficiently, enhancing treatment and increasing process uptime.
While every effort has been made to ensure the accuracy of the information contained herein, the publisher and its agents cannot be held responsible for any errors contained, or any loss incurred as a result. Articles published do not necessarily reflect the views of the publishers. The editor reserves the right to alter or cut copy. Articles submitted are deemed to have been cleared for publication. Advertisements and company contact details are published as provided by the advertiser. Technews Publishing (Pty) Ltd cannot be held responsible for the accuracy or veracity of supplied material.
printer friendly version