Due to their hygienic properties and their dead space-free design, twin screw pumps have so far been a preferred choice in the food and beverage industry. The newly developed Chemspin series from Jung Process Systems is aimed at a completely different sector. This special stainless steel twin screw pump was developed for demanding applications in the chemical industry.
Gentle pumping and excellent cleanability make these pumps to be an attractive solution for a wide range of hygienic applications. An advantage of this kind of pump technology is that twin screw pumps can be used both for the actual production and for subsequent rinsing processes. Additional, separate (centrifugal) pumps are not required for these cleaning processes.
With the Chemspin series, these properties can be utilised in a different environment and under different conditions. All components in contact with the product are manufactured in-house from particularly resistant austenitic stainless steel and are subject to strict quality controls. In order to achieve particularly high durability and wear resistance – not only for use in chemical industry – the feed screws are diffusion-hardened. The pumps are equipped with a wide range of features that make the Chemspin a multifunctional pump for industrial use.
Displacement pumps
Twin screw pumps belong to the group of rotating positive displacement pumps. Unlike rotary lobe pumps for example, where the product is rotating with the rotors, at twin screw pumps the medium is pushed very gently axially through the pump. This allows the product to reach the next process stage almost pulsation-free without degenerating. Unwanted foaming or strong shearing of the fluid is reliably prevented by this gentle transfer principle. The feed screws work completely contact-free. They are synchronized outside the pumping chamber thus there is no contamination of the product by debris from constant wear rates. At other technologies like gear pumps or progressive cavity pumps which pump under contact, there is always the risk of contamination entering the product due to abrasion, resulting in rejects and costs. In addition to that these pumps may be damaged due to dry run. With an appropriate shaft seal, the Chemspin is also suitable for dry running. As the bearing support is externally lubricated and not lubricated with pumped media, dry-running damage can be reliably prevented.
Designed for replacement
The Chemspin series was designed as a replacement series to enable the user to switch to a different pump technology easily and without complications. Connections and sizes can be flexibly selected and implemented. As an advantage existing pipelines and connection flanges can be reused without major modifications. The pumps can be installed both, horizontally and vertically. Wall mounting or installation on a mobile cart is also possible.
Due to the characteristics of the pumps, a wide control and speed range is available. Depending on the application and size, flow rates from 0.1 to 350 m3/h can be achieved. There are currently 5 pump sizes available.
Irrespective of the pump technology, cavitation causes severe damage and wear to pump components, resulting in a loss of efficiency. Due to the design of the Chemspin, only low NPSHR values occur, which reduces the risk of cavitation to a minimum. Typical values are below 1 m, values of up to 0.5 m can also be achieved with appropriate modifications. The NPSHR value remains low even at flow rates close to zero and increases only moderately with increasing speed and product viscosity. The pump is therefore particularly low-wear and guarantees high availability and process reliability. The suction behavior of Chemspin pumps is similar to that of side channel pumps. Suction heights of up to 9 m can be achieved if the internal clearances are sealed by the pumped liquid.
For users who want to pump fluids containing gas or particles this pump is of particular interest. Chemspin pumps are able to handle gas contents of up to 60 % without creating problems in the pump. Particles, e.g. glass beads as a component in underbody coating formulations, are also transported gently and without degeneration.
The dead space-free design is an advantage for applications with sticky or critical media. Thanks to the pump‘s excellent cleaning options, quick batch changes can be carried out with little effort and only small product loss. Cross-contamination of different batches is avoided by flushing the pump in place. Easy cleaning is also crucial for safe servicing of a pump in the event of an inspection or repair. Especially with critical media, flushing in the system offers tremendous benefits. With a suitable cleaning and rinsing procedure, no additional manual decontamination is required after removing the pump from the system. The pump can thus be serviced safely and without risk to personnel.
Different shaft seal types
Depending on the requirements, the application, the fluid and the process the Chemspin can be equipped with different shaft seal types. To enable dry running of the pump, double acting and flushed mechanical seals or lip seals are used. For the shaft seals particular attention was paid to a user-friendly design. All seals types are of a semi-cartridge design. Within a pump size the mounting space is always the same. Shaft seal modifications can be simply and easily done via plug & play.
In addition, feed screws with different characteristics can also be interchanged within one pump size. This flexibility makes it possible to adapt the pump to changed process and operating conditions without the need of expensive modifications. Usually, it is not required to replace a pump unit completely.
Author:
Henning Grönwoldt-Hesse,
Sales and technical
management
Jung Process Systems
Achema: Hall 8.0, Stand F27
