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Analyser Packaged Systems
Article used in ‘Instrumentation Review’
ABB ANALYSERS AT WORK IN THE POWER
AND WATER INDUSTRIES
The new legislative emphasis on policing the water environment and the increasing industrial requirement for high-purity process waters have provided major catalysts for intensifying the spotlight on reliable water quality monitoring. The impact on instrumentation manufacturers has, in a relatively short space of time, resulted in the development of new generations of increasingly sophisticated equipment in areas which had traditionally seen little change.
Meeting the new challenges has not only given impetus to technological advancements in monitoring instrumentation but has also driven the need to develop in close parallel greater versatility and flexibility in its application. The number of quality measurement parameters is increasing, as is the variety of applications for widely differing monitoring requirements. The quality criteria for water varies, for example, according to its intended use and can be based on environmental laws, commercial precepts, or both. Whereas the natural minerals retained in drinking (potable) water are essential to human health, they can lead to major problems in the water/steam cycle of a power generation plant. All ionic species, therefore, have to be removed to produce ‘high’ or ‘ultra high’ purity boiler feed water for optimum plant efficiency and product (steam) quality.
Similarly, industrial water waste discharges are required by law to meet the quality standard set by local discharge limits - expressed, for example, by a pH value and/or concentration of suspended solids. However, having left the outfall, the discharge becomes ‘raw water’ requiring much higher levels of quality monitoring when approaching the intake points of a public water treatment plant. Geographic location also enters the quality monitoring equation. In highly industrial areas, environmental monitoring for river water quality is likely to feature ammonia as one of the main measurement parameters while, in agricultural areas, nitrate will be a prime policing target.
Monitoring the various facets of water quality has led to the use of many measurement parameters beyond the traditional pH, dissolved oxygen and conductivity, and to the development of sophisticated instrumentation systems with the highest degree of reliability, repeatability and accuracy to promote greater confidence in continuous on-line analysis. Solutions can extend from a single, stand-alone pH meter measuring the final effluent discharge, through to a major power plant application where a special building is required to house an engineered multi-parameter system integrating various analysers with dedicated sample conditioning facilities.
ABB Instrumentation - one of the early pioneers of continuous on-line liquids analysis - has also been a prime mover in the development of integrated multi-parameter analyser systems. Today, the company’s capability covers the in-house manufacture of virtually all analyser system components and procurement of sample conditioning elements, through to engineering integrated packages to meet a customer’s specific monitoring requirements. Installed in water utility and power plant applications throughout the world, they provide water quality analysis using a wide range of measurement parameters. ABB analyser instruments available for integration into a multi-parameter packaged system include the 4600 Series of continuous on-line monitors for pH, conductivity, dissolved oxygen, turbidity and temperature; the 8230 Series of on-line ion-selective monitors for ammonia, nitrate and fluoride and the 8240 Series of colorimetric monitors for phosphate and silica. Sodium, chloride, and hydrazine analysers are also available.
Power Generation Monitoring.
For approximately 40 years, ABB has been supplying analytical packaged systems to the power generation industry. Here, instrumentation is employed primarily to monitor the quality and purity of the circulating water and steam so as to avoid scaling (similar to that found in the well-used kitchen kettle) and corrosion within the boiler and turbine mechanism. The operating pressures and temperatures of most plants are far too high for the analysers to be able to cope with samples taken direct from the water/steam process. Before being offered to the analyser, samples, therefore, need to be conditioned by reducing the pressures and temperatures to an optimum level for correct analysis.
ABB were one of the first instrument manufacturers to design and engineer complete analytical packaged systems, with integrated sample conditioning facilities, piped and wired prior to shipment. On enquiry from a prospective client, ABB engineers will overview the plant to ascertain the requirements specific to the application. Analysers, for example, may be limited to just conductivity monitoring, or combined with others for measuring sodium, silica, dissolved oxygen and pH. In addition, coolers and valves are selected for reducing operating pressures and temperatures to the correct levels, and then the package is sized according to the distance between the analysers and the process and installation space limitations. Sometimes completed systems are installed in separate buildings or on free-standing racks.
Basically, the analytical system in a power generation plant has two main functions. One is to ‘police’ the various dosing operations for creating the required water/steam purity levels and the other is to monitor for plant malfunctions, resulting, for example, from contaminants leaking into the clean process water, or air (oxygen) finding its way into the extraction pump glands.
The size of a power plant analytical packaged system will vary from an installation comprising a single conductivity loop, through to a fully equipped multi-parameter monitoring system with integrated sample conditioning facilities occupying several buildings and ready for linking in to the plant DCS. Large-scale analytical systems now tend to be less in demand with the passing of the big centralised power stations. However, the move towards privatisation and the use of more efficient ‘clean’ fuels, has led to the development of a larger number of smaller capacity plants. The market for analytical packaged systems is, therefore, shifting to open up new opportunities for suppliers who can match technical excellence with versatility and cost-effectiveness.
ABB is well placed to meet this challenge, having a comprehensive range of analytical instrumentation, with the sensors and electronics manufactured in- house, and a total capability in the design of sample conditioning systems to meet customers’ specific plant requirements. Added to this, the company has a complete ‘after care’ support and maintenance facility under the ABB ‘Assist’ customer services package which, in the UK, includes a team of engineers dedicated to power plant instrumentation maintenance. ABB analytical systems installed in power plants throughout the world include those operating in Taiwan, Portugal, South Korea, Czech Republic, China, Bahrain, Greece, Hungary, India, Indonesia, Malaysia, Mexico, The Netherlands, Poland, Saudi Arabia, South Africa, Sweden, Germany, the UK, New Zealand, Belarus and the USA.
Environmental Monitoring.
Within the hydrological cycle - abstraction, treatment, distribution, effluent and sewage treatment and the return of treated water to the rivers and seas - an enormous range of ABB analytical products is deployed to ensure that the highest standards of quality and efficiency are maintained at every stage. Packaged multi-parameter systems can be engineered for the continuous on-line measurement of a wide range of quality parameters normally associated with environmental monitoring. Equipment can be pre-assembled into custom designed units, including permanent water quality monitoring stations, mobile water analysis laboratories and unmanned stations. Data can be logged locally or transmitted to a central facility.
The integrated sampling conditioning facilities for these applications normally comprises ultra filtration to provide clean sample filtrate to the on-line analyser. Also, depending on the location, cabins housing the analytical systems are heated and air conditioned to provide reasonable ambient temperatures for optimum instrument performance.
For relatively simple applications, a system can comprise a small glass-reinforced plastic (GRP) cabinet containing a single pH meter for compliance monitoring of a final discharge from an effluent treatment plant with, perhaps, a single pen chart recorder. For more complex monitoring on final effluent or a river, ABB supplies large, walk-in cabinets equipped to monitor the five essential parameters (pH, conductivity, dissolved oxygen, temperature and turbidity) together with ammonia, nitrate and phosphate, plus all the ultra filtration and data logging equipment. Special monitoring requirements may also be included, such as Total Organic Carbon (TOC) monitoring, complete with automatic sampling facilities.
Principal applications comprise monitoring the outfall of waste water and for intake protection at a water treatment plant. ABB also supplies analytical multi-parameter systems to the Environment Agency in the UK for detecting pollution, maybe downstream of a large industrial site.
Analytical instrumentation for river monitoring is installed to provide information and alarm warnings. If contamination were detected at an abstraction point, treatment plant personnel would be alerted and may cease pumping operations until analysis showed that the contamination had passed. As well as providing safety assurance, such monitoring systems are also used for data collection on river quality for trend analysis.
Although environmental monitoring parameters have seen little change in 15/20 years, the instrumentation has become infinitely more sophisticated and reliable, with longer periods between attendance and lower cost of ownership. Instrumentation reliability is particularly important in river monitoring. If an instrument should fail in a power plant, a technician is usually close by. However, in a remote river monitoring situation, carrying out repairs could involve a significant amount of travelling time.
The installed base for ABB water quality monitoring stations is growing progressively broader as concern for the environment becomes more acute. As new laws become enacted so new and heavier demands evolve, many requiring radical change in perceptions and responsibilities. With its firm foundation of technical achievement and applications expertise, ABB is well placed to keep abreast with the new and emerging challenges.
END
Prepared by
Richardson Public Relations1560 words.
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