Until February 2020, an oil depot in a Brazilian seaport used two centrifugal pumps to transport heavy oil from storage tanks to tanker trucks or ships. This requires diesel fuel injection to reduce the high viscosity of the medium, which is expensive. Owners earn at least $2,000 per day. In addition, centrifugal pumps often fail due to cavitation damage. The owner decided to first replace one of the two centrifugal pumps with a NOTOS® multiscrew pump from NETZSCH. Thanks to its very good suction capacity, the selected 4NS four-screw pump is also suitable for high-viscosity media up to 200,000 cSt, delivering flow rates of up to 3000 m3/h. After commissioning, it became clear that the multiscrew pump can operate without cavitation even at significantly higher flow rates compared to other centrifugal pumps. Another advantage is that it is no longer necessary to add large quantities of diesel fuel. Based on this positive experience, in February 2020 the customer also decided to replace the second centrifugal pump with NOTOS ® . In addition, it is clear that energy consumption can be significantly reduced.
“These pumps are used to transport heavy oil from tank farms to tanker trucks or ships in the seaports of north-eastern Brazil, mainly during periods of drought,” explains Vitor Assmann, Senior Sales Manager at NETZSCH Brazil. “This is because the country’s hydroelectric power plants produce less energy during these periods, which increases the demand for heavy oil. Until February 2020, this transfer was carried out using two centrifugal pumps, however this centrifugal pump struggled with high viscosity.” environment. “Conventional centrifugal pumps have poor suction capacity, which means that some oil remains in the reservoir and cannot be used,” explains Vitor Assmann. “In addition, incorrect technology can lead to cavitation, which will lead to pump failure in the long term.”
Two centrifugal pumps at a Brazilian tank farm are also suffering from cavitation. Due to the high viscosity, the NPSHa value of the system is low, especially at night, which leads to the need to add expensive diesel fuel to heavy oil to reduce the viscosity. “About 3,000 liters need to be added every day, which costs at least $2,000 a day,” Asman continued. To improve process reliability and efficiency and reduce energy costs, the owner decided to replace one of the two centrifugal pumps with a NOTOS ® multiscrew pump from NETZSCH and compare the performance of the two units.
The NOTOS ® range typically includes multiscrew pumps with two (2NS), three (3NS) or four (4NS) screws, which can be flexibly used to handle different viscosities and even high flow rates. An oil depot in Brazil required a pump capable of pumping up to 200 m3/h of heavy oil at a pressure of 18 bar, a temperature of 10–50 °C and a viscosity of up to 9000 cSt. The tank farm owner opted for a 4NS twin screw pump, which has a capacity of up to 3000 m3/h and is suitable for highly viscous media up to 200,000 cSt.
The pump is highly reliable, can withstand dry running and can be manufactured from materials specifically selected for the application. Modern manufacturing technologies allow tighter tolerances between dynamic and static components, thereby reducing the need for reflow. In combination with the flow-optimized pump chamber shape, high efficiency is achieved.
However, in addition to efficiency, the flexibility of the pump in terms of the viscosity of the pumped medium is especially important for owners of Brazilian tank farms: “While the operating range of centrifugal pumps is narrow and as the viscosity increases, their efficiency decreases sharply. The NOTOS ® multi-screw pump works very efficiently across the entire viscosity range,” explains Senior Sales Manager. “This pumping concept is based on the interaction between auger and housing. It forms a transport chamber in which the medium moves continuously from the inlet side to the discharge side under stable pressure – almost regardless of the consistency or viscosity of the medium.” The flow rate is affected by the pump speed, diameter and pitch of the auger. Consequently, it is directly proportional to the speed and can be smoothly adjusted through it.
These pumps can be adapted to the current application to achieve optimal performance. This concerns mainly the dimensions of the pump and its tolerances, as well as accessories. For example, overpressure valves, various sealing systems and bearing monitoring devices using temperature and vibration sensors can be used. “For the Brazilian application, the viscosity of the media combined with the speed of the pump required a double seal with an external sealing system,” explains Vitor Assmann. At the client’s request, the design complies with API requirements.
Because the 4NS can operate in high-viscosity environments, there is no need to inject diesel fuel. This, in turn, reduced costs by $2,000 per day. In addition, the pump operates more efficiently when pumping such viscous media, reducing energy consumption by more than 40% to 65 kW. This saves even more energy costs, especially after a successful test phase in February 2020, the second existing centrifugal pump was also replaced with a 4NS.
For over 70 years, NETZSCH Pumps & Systems has been serving the global market with NEMO® single screw pumps, TORNADO® rotary vane pumps, NOTOS® multiscrew pumps, PERIPRO® peristaltic pumps, grinders, drum emptying systems, dosing equipment. and accessories. We provide customized, comprehensive solutions for applications in various industries. With more than 2,300 employees and a turnover of €352 million (fiscal year 2022), NETZSCH Pumps & Systems is the largest business unit in the NETZSCH Group with the highest turnover, along with NETZSCH Analysis & Testing and NETZSCH Grinding & Dispersion. Our standards are high. We promise our customers “Proven Excellence” – outstanding products and services in all areas. Since 1873, we have proven time and time again that we can keep this promise.
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Post time: Jul-31-2024