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Effective water treatment regimes: where to start
hile most process managers and engineers already have a broad knowledge of their system
requirements and have a water treatment
Although the benefits of water treatment are clear to those working in the process industries, treatment regimes are not always reviewed as regularly as they could be. Martin Smith, Managing Director of adi Environmental (pictured), says that regular
benchmarking and in‐depth reviews of requirements could help
companies achieve long‐term cost and efficiency savings.
programme in place, it is recommended that this is reviewed on a frequent basis, particularly when there are changes in water quality, legislation or the plant’s operation. Conducting a thorough benchmark audit before making any adjustments to a water treatment programme is highly beneficial. Not only does this provide transparency over process operations,
challenges and drivers but it also allows manufacturers to identify opportunities for improvement.
For example, many perceived issues within a water treatment system – whether it be a steam raising plant or a cooling process – can be engineered out, rather than requiring a change in chemistry. In many cases, a correctly designed system from a mechanical perspective will alleviate a majority of issues from a chemical perspective. Taking this approach can reduce ongoing maintenance costs and improve water quality by reducing the need for chemical water treatment. Take a steam raising plant, for example; this could involve ensuring that the pre- treatment plant is fit for
purpose based on the site’s steam process requirements; the hot well design is in keeping with legislation; the boilers are operating as near to design pressure as possible; and the boiler’s control philosophy adheres to BS2486/BG01 standards. Guidance for the Safe Operation of Boilers (Ref: BG01) is a guidance document intended to assist the managers, designers, operators, maintenance personnel and Competent Persons (CP) of new and existing boiler systems in addressing a number of issues, including: the safe use and operation of the boiler installation; adequate supervision and
maintenance (levels and competence); and reducing the likelihood of explosion, or other dangers, from events such as loss of feedwater or low water level.
It also advises engineers on how use the proper
treatment and monitoring of the feedwater and condensate can minimise corrosion and scale, and avoid carry-over of water with the steam which, in turn, can cause water-hammer. The document assists with compliance to the various legal requirements, particularly for periodic examination by a CP in accordance with a written scheme of examination (WSE).
Identifying the correct Total Dissolved Solids (TDS) set
INDUSTRY COMMENT BSEE Ask the Expert
Synchronous reluctance motors – the right choice for HVAC pumps and fans
point based on the limitations within the feedwater quality is also crucial, and regular calibration of the TDS controller should form part of the treatment regime. It is also important to inspect and analyse the whole system, not just the boiler itself. Condensate analysis and interpretation is a key factor in ensuring that a boiler water treatment regime is being managed effectively. Often, problems that are not always picked up within the boiler itself may be transported into the steam and condensate lines via priming or foaming. Generally, the amount of steam trap failures give a good initial indication as to whether the boiler water treatment regime is
performing effectively so it is advisable to include this as part of the regime.
At adi Environmental, we apply these principles to all our projects, which incorporate a vast number of systems including cooling towers, closed systems, effluent, process or even domestic water treatment. The principle behind conducting the initial benchmark audit is to develop a deep understanding of the client’s needs early on, which then allows us to work in partnership. This way, we can utilise the specific skill sets and knowledge of both parties in the most effective manner.
By Carl Turbitt, HVAC Drives – UK Sales Manager, ABB UK
pecific fan power (SFP) is a measure of how much electric power is required by a fan to move a given air volume. The SFP is influenced by flow rate, resistance of the ventilation system and efficiency of the fan system. By stipulating a maximum SFP, it is possible to limit the power requirements for transporting air throughout an entire building, air handling units (AHUs) and individual fans. To meet the requirements of the SFP, as stipulated in Part L of the building regulations, a system design is needed. The HVAC market generally recognises three scenarios: uBrushless DC motor, or electronically commutated motor (ECM) uPermanent magnet (PM) motor instead of induction motor uConventional fan controlled by conventional induction motor and VSD
ECMs are combined with a brushless controller onto the fan assembly. However, if one component fails, the entire unit – including fan, motor and controller - has to be replaced. ECM fans have a poor harmonic signature, typically do not come with building management system (BMS) fieldbus protocols and cannot catch spinning loads, a requirement for data centres.
ECMs are only available in low powers, so several units must be combined into a fan array in order to reach the desired power. However, this adds components into the system, thereby increasing the probability of failure. If a unit fails, increasing the speed to maintain the flow will take more power, thus not maintaining specific fan power requirements. PM motors are expensive, difficult to handle (they magnetise themselves to any ferrous surface), have non- standard motor shapes and fixing dimensions and generate dangerous back EMF voltages when freewheeling. This latter challenge means that the common practice of opening a motor isolator to perform maintenance is no longer adequate. The fan shaft needs to be locked in place to avoid electric shock.
Xpelair issues warning as air pollution hits the headlines
Xpelair is highlighting the importance of ensuring adequate ventilation.
uXpelair’s Natural Air 180 – a new Mechanical Ventilation with Heat Recovery Unit (MVHR), designed to improve air quality.
According to a new study – ‘Can Clean Air Make You Happy?’ – exposure to nitrogen dioxide can have the same negative impact on the human body as ‘big-hitting’ life events, such as losing a job or partner. With the likelihood of being exposed to air pollution much greater than such unforeseen circumstances, the consensus is thereby that reducing emissions would greatly benefit society and people’s wellbeing. As a manufacturer and developer of ventilation systems, Xpelair has championed the importance of improving indoor air quality. Lee Stones, Category Manager, said: “The results of this report are shocking. As a nation, we are generally well versed when it comes to the physical
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ith new research revealing some grave repercussions of air quality pollution,
health implications that exposure to unhealthy levels of air pollution can pose, but for it to be put into the context of losing a job or the death of a partner clearly shows the sheer gravity of the situation.”
Most recently, Xpelair launched Natural Air 180 – a new Mechanical Ventilation with Heat Recovery Unit (MVHR) which has been designed to improve the nation’s air quality. It features a carbon filter ancillary, which filters outdoor air, giving a method of exchanging air in the building whilst filtering out the harmful nitrogen dioxide.
Stones adds: “The current air pollution situation presents a very real threat – contributing to around 40,000 early deaths a year in the UK. It is vital that, as an industry, we take a considered and holistic approach to the specification of ventilation products which can improve air quality and thus improve health and wellbeing for all.”
BUILDING SERVICES & ENVIRONMENTAL ENGINEER JUNE 2017 11
A new and more appealing option is to use a synchronous reluctance motor (SynRM). Compared to an equivalent induction motor, this design offers 40 percent fewer losses, is 50 percent lighter, 50 percent quieter and costs the same. The SynRM needs a variable speed drive (VSD) to operate. The VSD may be slightly larger for high load requirements. As such it may be more expensive than a conventional induction motor selection, due to higher excitation current. However, the cost penalty is countered by additional savings from the guaranteed package efficiencies. The IE4 package, for instance, gives super premium efficiency that allows SFPs to be achieved. A high output variant which is two frame sizes smaller, allows for easy mounting within a duct. SynRM operates very efficiently when partially loaded, or when operating super-synchronous (above 50 Hz). The fan design, therefore, can be tailored to meet SFPs at speeds not normally considered. “Efficiency islands” can be identified to ensure all of the components are selected optimally, making the packages perform best in class.
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