Space on the plant floor is valuable and engineers are under increased pressure to make the most efficient use of the area available.  Pumps used in a variety of chemical applications can often be bulky, but Edwards has developed a compact dry pump package, with space saving of typically halving the footprint over alternative designs.

Dry pumping is well established as a vacuum pump technology in the chemical and pharmaceutical industries, and its benefits of reducing environmental waste, improved processing and reduced maintenance are well understood by the industry.

A dry vacuum pump eliminates oil from the swept volume, resulting in a number of significant advantages. Primarily, it reduces the effluent – oil or water, that traditional vacuum pumps can produce, and this minimises disposal or treatment costs. Using dry vacuum pumps minimises potential contamination of the process that can occur which can affect the quality of the final product. Dry pumps are not affected by vapor, or dust particles in the same way as oil-sealed pumps so they last longer and require less maintenance

Used in applications such as biofuel production and distillation processes, a key requirement for dry vacuum pumps has been their ability to handle liquid carryover from the process – a common result of process upset, for example, a blocked inlet condenser.  For this reason the more robust designs were vertically orientated so that they were self draining in the event of liquid entering the pump.

However, many process industry applications require either a higher pumping speed, or a lower operating pressure than can be achieved with a single dry pump. To achieve this the dry pump is typically combined with a mechanical booster to give capacities in excess of 5,000 m3/hr, or to reach pressures below 0.01mbar. With a vertically oriented pump this usually means that the booster is mounted on a separate frame alongside the pump. While this combination gives a high capacity pumping system, it will significantly increase the floor space occupied by the pumping system.

A compact package

Now, there is a more compact package available with space savings of typically 50% over alternative designs.  The new CPH™ series is a horizontal pump that has been designed so that the mechanical booster mounts directly on top of the dry pump, with the booster exhaust connected directly into the inlet of the dry pump.

The CPH series is a horizontal version of the well-established Edwards ‘claw’ chemical dry pumps. When combined with a high capacity mechanical booster the CPH series has a much smaller footprint than alternative designs. They are designed to offer a compact pumping package for applications and the high pumping speeds are required, where more advanced functionality of alternative vertical pumps is not needed.

There are two pumps in the range, the CPH250™ chemical dry pump, with a 250m³/hr throughput, and the CPH400™ chemical dry pump, with a 400m3/hr capacity. Both offer excellent pumping speeds from atmospheric pressure down to an ultimate pressure of less than 0.5mbar.  They are available as pre-engineered pump and booster combinations with Edwards’ popular EH range of mechanical boosters to give a compact package with pumping speeds up to 4,000 m³/hr and a low ultimate pressure which is well suited to applications such as biodiesel production.

The CPH series has also been designed with ‘plug and play’ installation in mind. All the utility connections are placed on a single service panel so that they can be easily connected up on installation. There are a number of standard purging options available to meet the process requirements:

• Nitrogen shaft seal purge for use when flammable vapours or gases are being pumped.
• Gas ballast for applications where high vapour loads are being pumped, and condensation in the pump or exhaust line is to be prevented.
• Inlet purges where corrosives are being pumped and start up and shut down purge routines are recommended, or where there are high dust loads which need to be kept from accumulating in the pump.

A key consideration for safe working in the chemical industry is that the pumps comply with the European ATEX legislation.  The CPH pumps have been designed to be compliant for the safe pumping of flammable vapours.  At the core of the Edwards safety policy for ATEX is ‘constructional safety’. This means that the design of the pump has been independently certified as being inherently safe, and that failure modes that could result in the pump mechanism causing a spark leading to a fire or explosion have been designed out. As a result both 50 and 60Hz versions have been certified to Ex II 2 c IIB T4. Although there is no equivalent yet in the US, many of the global chemical and pharmaceutical companies are adopting the principles of ATEX legislation world wide as part of their risk management process.

Space saving solution

Developments in pumping technology are bringing a new level of efficient, compact dry systems to the chemical industry’s plant floor, which is resulting in a space saving of typically 50% over alternative designs. The CPH chemical dry pump series is a simple solution compared to traditional vertical alternatives, where functions such as advanced liquid handling and temperature management applications are not necessary.  The range builds on Edwards’ long history of developing innovative dry pumping solutions, and the experience gained from having over 100,000 pumps installed worldwide.