No compromises are made when draining houses and properties – not in efficiency, not in performance and most certainly not in reliability.
The new Wilo-Rexa MINI3 proves uncompromising in this demanding drainage application whether in wastewater, sewage, in the house, in the garden or in the excavation. Rainwater, ground water and sewage occur again and again around houses and on properties. In the future, these can be reliably and efficiently transported away with the Wilo-Rexa MINI3. Thanks to its optimised hydraulics, the sewage pump achieves maximum efficiency with simultaneously minimised maintenance requirements: “The Wilo-Rexa MINI3 enables considerably extended maintenance intervals thanks to its oil chamber with two oil seals and mechanical seal in addition to its robust, rubberised cable connections” explains Wilo Product Manager Olivier Armbruster. “Apart from this, it minimises the time required for maintenance thanks to the direct access to both the sealing chamber and pump housing.”
Highest operational safety and reliability
In addition to the pump housing, which is made from especially durable grey cast iron with a G 1½ pipe connection, the flexible float switch and a specially-developed vortex impeller ensure excellent reliability: “We decided to produce an innovative plastic version during construction which, compared with the stainless steel impellers which are frequently used, has the advantage of being completely corrosion-free” said Mr Armbruster. Furthermore, the use of plastic enables transport of a wide range of fluids, even aggressive substances. “The reliable vortex impeller also prevents the pump from being blocked, which can result in flooding in some cases.” The Wilo-Rexa MINI3 is also completely unaffected by fluids with a high solids content or larger particles thanks to the large free ball passage of 40 mm, which is unrivalled in its class. The pump sets additional standards in the compact sewage pump class with a delivery head of 13 metres and a flow rate of 22 m3/h.
Simple installation and huge flexibility
Despite its high performance, the Wilo-Rexa MINI3 has an extremely compact construction and low weight: “For this reason it is suitable for both stationary installation, for example in house wastewater shafts, and also for flexible use in applications such as excavation dewatering, even in extremely tight excavations” explains Olivier Armbruster. “With its protection class IP68, it is also completely suitable for wet well installation and also for flexible usage in pump sumps.”
Green efficiency in Dublin’s Central Bank
High performance, long-lasting sustainability and energy efficiency: The central bank campus in dublin unites these three aspects. Located in north wall quay in Dublin Ireland, the modern building provides a state-of-the-art workplace, facilitating open communication and promoting teamwork at every level. Germany-based technology expert Wilo has equipped the new campus with green pumps, and thus contributes to the building’s environmental efficiency.
The Dublin Docklands is spread over 520 hectares north and south of the Liffey. High employment prospect possibilities have attracted people and businesses since the late 18th century. What used to be a landscape of ship funnels, cranes, pubs and stables, has been transformed into a gleaming, modern business hub due to urban regeneration over the past years. North Wall Quay is located on the northern side of Dublin, including the International Financial Services Centre (IFSC). Since 2017, the new headquarters of the Central Bank of Ireland have been located here. The sculptural profile of the new building reflects the maritime setting and new civic identity of the Dockland area. The building is wrapped in a glass skin, which is shielded from glare and solar heat gain by an outer layer of anodized aluminium triangular mesh panels. Those panels contribute significantly to the overall energy performance by reducing the impact of solar heat and thus also reducing the energy needed for heating and cooling. The façade is broken down into a number of elements: a double glazed unitised inner skin, an outer solar shading skin, the unique glazing system and a rain screen cladding. North Wall Quay is the first office building in Ireland to achieve the Building Research Establishment’s Environmental Assessment Method (BREEAM) ‘Outstanding’ rating at design stage. The building energy rating (BER) is targeted to A2, which equates to a 72 % improvement in energy consumption over previous building regulation baselines. Effective insulation also reduces the energy consumption, the environmental impact is held on a low level by using energy from renewable sources. Annual energy savings according to the BER A2 rating is 209 tonnes of CO2.
Covering the complete life cycle
Green Wilo pumps also contribute to the overall efficiency of the new headquarters – from heating and cooling to cold water supply and products for rainwater harvesting. “Central Bank campus is a green building, certified by BREEAM, the world’s leading sustainability assessment method. The bank itself had set a number of objectives when it came to the sustainability of the building – one of our main requirements was to only provide high-efficient pumps with efficiency class IE4 to ensure compliance with BREEAM criteria”, says Derek Elton Managing Director from Wilo Ireland. The Wilo-Stratos GIGA series included for example is an electronically controlled glanded single pump in Inline-design using EC motor technology for increased operation efficiency along with the Wilo-IL-E series used for pumping the heating and chilled water systems. The Wilo-SiBoost Smart 3 Helix EXCEL series are in operation for cold water applications including rain water harvesting. The compact high efficiency pressure boosting system consists of vertically-mounted stainless steel high-pressure multistage centrifugal glanded pumps for which each pump has an integrated frequency converter for maximum efficiency of operation. These packaged booster systems include ready for connection stainless steel pipework base frame mounted and an automatic control system with all necessary measurement and adjustment facility. For a reliable operation in the HVAC applications several Wilo-Stratos models are used. Recently, Wilo Ireland has also been awarded with the service contract for the new campus: “As a global specialist for pumps and pump systems, we offer a wide variety of services to help our clients optimising and securing their processes”, explains Derek Elton. “Caring about our customer is an ongoing process. It is our understanding that our services cover the complete life cycle of our Wilo products – to live up to the sustainable requirements of our customers.” The Central Bank of Ireland also takes a pro-active approach to managing environmental obligations, which results in e.g. rainwater harvesting at North Wall Quay campus. This method is a simple and smart way to collect rainfall for further usage. Capturing the water can help recharge local aquifers or avoid urban flooding and thus create a sustainable water management.
The dockland campus
The building provides a modern workplace facilitating open communication, promoting teamwork and interaction at every level. The heart of North Wall Quay is the atrium, featuring collaboration spaces. More than 1,400 people work at the eight floor building. Central Bank set a number of objectives for the design of the building: apart from establishing a productive workplace, it was of outmost importance to ensure the environmental sustainability.
First industrial scale cMIST™ unit on the way
Sulzer is supplying the first ever industrial scale cMIST™ system for natural gas dehydration with start-up scheduled for the second half of 2020. The unit will be installed at an onshore ExxonMobil facility in the U.S.
The cMIST™ unit is to be delivered to ExxonMobil’s facility by Sulzer Chemtech, the leader in separation and mixing technology, and will be the world’s first commercial application of the cMIST™ technology in place of conventional glycol contactors. The project will be executed by Sulzer’s specialized engineering centers in Tulsa, Oklahoma, U.S., Arnhem, the Netherlands, and Pune, India.
The equipment will showcase how this innovative gas processing solution can support companies in the oil and gas sector in meeting stringent requirements for water content in natural gas with a compact and lightweight solution.
ExxonMobil’s patented technology relies on a proprietary cMIST™ droplet generator and Sulzer’s patented HiPer™ Inline separator to deliver the same performance and efficiency as conventional gas dehydration systems based on glycol contactors, while greatly reducing their weight and footprint. As a result, cMIST™ is particularly beneficial for onshore and offshore facilities, where space is limited. The technology is equally applicable for greenfield or brownfield and can address dehydration capacity and/or efficiency bottlenecks in existing production facilities.
This new project builds on a longstanding partnership between Sulzer and ExxonMobil. ExxonMobil developed cMIST™ technology for gas dehydration, with the assistance of Sulzer, and subsequently offered Sulzer an exclusive license for the design and supply of cMIST™ units for onshore and offshore gas dehydration applications.
Ken Dowd, Technology Development Manager at ExxonMobil, comments: “This project will leverage the combined expertise of Sulzer and ExxonMobil in delivering cutting-edge process technologies for gas treating. We have collaborated with Sulzer’s specialized teams on this technology from the development phase and now look forward to deploying the first industrial-scale cMIST™ field-based unit.”
Danny Thierens, Head of Sales & Market Development – Upstream Systems at Sulzer, concludes: “We look forward to completing the installation of the first industrial scale cMIST™ gas dehydration system in close cooperation with our partner ExxonMobil. This innovative plant will demonstrate the benefits of the system to the upstream oil and gas market and will strengthen the confidence of customers that are considering the deployment of this technology, on the basis of the numerous design concepts that Sulzer has helped to develop since the licensing agreement came into effect.”
Hydraulic retrofit meets increased demand
Productivity targets are a key performance measure in any process industry and the refining business is no exception. Increasing output from a large refinery to meet market demand does present its challenges, however, dealing with the pumps does not need to be one of them. Sulzer has proved that a retrofit can provide the most cost-efficient solution, when carried out by a provider with the right design experience and manufacturing expertise.
Matt Kinney, Hydraulic Retrofit Specialist, at Sulzer, discusses a good example of a successful retrofit project.
Due to changes in Government regulations over the past several years, the demand for ultra-low sulfur diesel (ULSD) has increased significantly. As a result, refineries across the country have been forced to adapt and find innovative solutions to meet increasing capacity. A refinery located in Texas found themselves in this situation and reached out to Sulzer’s Odessa Service Center to investigate possible solutions. In a focused effort to address this issue, the two pumps of interest are 6x8x10.5 BB5 10 stage units in diesel charge service. The American Petroleum Institute (API) BB5 is a barrel pump that encloses a multi-stage axial split inner bundle with an opposed impeller configuration (see figure 1). Being that the pressure boundary is radially split, these pumps are typically designed for high-temperature and/or high-pressure applications. With the capability of handling pressures and temperatures up to 6’250 psi (431 bar) and 800 °F (427 °C) respectively, the API BB5 is an excellent pump selection for applications such as water injection, oil export, boiler feed, and charge service.
The subject pumps were originally sold in 2006 at a rated point of 1’110 gpm (252 m3/hr) @ 4’014 ft (1’223 m). However, with the change in ULSD demand the reliability engineers at the refinery were interested in a capacity increase to 1’628 gpm (370 m3/hr) @ 3’450 ft (1’052 m) (see figure 2). The goal for Sulzer was to find the most economical and timely solution to meet the customer’s needs.
When in this situation, there are three possible options:
Purchase a new pump that is designed to deliver the desired capacity Hydraulically modify or “re-rate” the existing pumps Operate their two existing 100% pumps in parallel (depending on customer system curve) Each of these options above have their own advantages and disadvantages. For example, parallel operation would clearly be the least costly to achieve the increase in flow. However, the lack of system redundancy in the event of a failure is risky and can often be very costly in terms of lost production. A new pump selection to fit the application could be advantageous with regards to efficiency but long lead times, the cost to reroute pipework, and baseplate/foundation modifications may make this option less attractive. There is really no downside to re-rating pumps other than the fact that the desired performance may not always be achievable in the given frame size, if feasible, re-rating is often faster and more economical.
Based on the criticality of this service for the overall success of the refinery, the possibility of re-rating was of great interest in this example. To support the customer, Sulzer engineers conducted a thorough feasibility study both hydraulically and mechanically to determine whether the goal was possible. A specific speed (Ns) based search through Sulzer’s vast hydraulic database revealed an existing proven design that would meet the client’s needs – provided the impellers were able to physically fit, and the inner-case volute nozzle areas were able to be increased enough to allow the impeller to meet as-designed performance. A review of the volute development drawings provided confidence that both items could be fulfilled.
The Sulzer approach was to keep it simple:
Select an existing standard Sulzer impeller hydraulic design that is suitable for the desired performance and has been proven by at least two factory tests. Ensure that case modifications can be made to fit the new impeller. Confirm the nozzle area can be increased enough to mimic the reference pump performance.
With a massive array of impeller hydraulic designs available, Sulzer engineers were able to select an existing design that would meet the new desired head and capacity of the application.
A mechanical cutback was done (see figure 3) to achieve both an increase in nozzle area and lip diameter. Based on empirical data, the increase in nozzle area would allow the new impeller selection to runout to the new design point. The increase in volute lip diameter enabled the designers to achieve sufficient lip clearance. This, and the fact that the cutback was ‘angled’, helped with the reduction of vane pass pulsations and overall vibration amplitudes.
The outlet vanes of the impeller were underfiled to increase the outlet area between vanes (OABV) and help flatten the performance curve. This also pushed the best efficiency point (BEP) to achieve higher flows.
The design process highlighted the fact that the new performance level did not require all 10 stages. One stage was removed so that the impeller trim could be near-full diameter. This benefitted both the efficiency and the BEP location for the pump. With the stage reduction, the effect on axial thrust direction and magnitude was analyzed; the internal bushings were resized to ensure the axial load was acceptable for the thrust bearing.
Challenges and drawbacks
With a major re-rate such as this, it can be rather difficult to fit a new, relatively large, high capacity impeller within the existing volute. This is because multi-stage pumps such as this are designed with the shortest possible stage spacing to limit overall pump length. Fortunately, the pumps in this example were originally equipped with a relatively low flow rotor compared to its frame size, which offered more room to work. In order to accommodate the increased impeller outlet width, the volute side walls required widening or “slabbing” to ensure adequate side-room clearance, which is extremely important to centrifugal pumps.
In addition, the inner-case line bore diameter was increased to accommodate the larger impeller eye diameter. The bore was increased to the maximum allowable value while maintaining enough wall thickness between it and the waterways and maintaining structural integrity of the inner bundle.
The increased pump performance required more power than the original 1’250 hp (932 kW) motor could deliver, so a new motor was required to meet this demand. However, no baseplate modifications were required as the frame size for the higher rated motor remained the same.
The Net Positive Suction Head Required (NPSHR) had increased with the new selected suction impeller. However, this was not a problem as the Net Positive Suction Head Available (NPSHA) was adequate.
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