Spirax Sarco – Amarinth designs Ci-Nergy, the standard variable speed condensate recovery unit

A challenging design brief

When saturated steam gives up its latent heat, a residual amount is retained in the resulting condensate. This is collected in a Condensate Recovery Unit. (CRU) and then pumped back to the system. Although Spirax Sarco Mk III CRUs had proved extremely popular and reliable for over 25 years, the design, which utilised Amarinth’s low NPSH pumps, did not take advantage of the latest technology or materials. The direct on-line motors were limited to just 10 motor starts per hour and so pumping of the condensate would occur only when the tank was full. This meant that condensate could sit in the tank for long periods, losing its energy and therefore requiring more re-heating by the boiler. The existing range had also expanded to include 59 product options, and so rationalisation was needed. A team comprising of Spirax and Amarinth staff therefore set about creating a specification for the new CRU. After considering various options, the final design brief was for a system with:

• Small foot print
• Variable speed technology
• Stainless steel tanks
• Simplex pump
• Better performance and greater
• reliability than competition
• Price competitive
• Low maintenance

The new CRUs had to also fit through a standard door used in industrial buildings so that the old units could be replaced easily and cost effectively. Amarinth took just 18 months to design and bring the Ci-Nergy range into production. Despite the higher specification, by reducing the number of components the cost of the new units are less than the old ones they replace. Rationalisation to just eight new products was achieved by using a plug and play concept with only two tank and pump sizes and eight motors to handle condensate between 500 and 35,000 kg/hour.