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Condition monitoring key reducing carbon emissions

Condition monitoring key reducing carbon emissions
Heinz will slice more than 4% from its energy consumption in the next three years at its Wigan factory after signing up for a steam trap management contract with Spirax Sarco. The decision to opt for the new contract followed great success with a previous, one-off steam trap survey, which saved enough energy and treated water to pay for itself in less than nine months.

The Heinz factory in Wigan is the largest food factory in Europe. The 55-acre site produces canned soups, baked beans, pasta and puddings for the UK and European market, and its on-site energy centre generates up to 140 tonnes of steam per hour to keep the canning lines running. 

Under the new deal, Spirax Sarco engineers will survey the site every six months, highlighting any traps that need maintenance from teams at Heinz. Spirax Sarco specialists will spend around 10 days on site each year, checking, tagging and recording the condition of each steam trap. 

"When Spirax Sarco carried out the original survey they put in a conservative estimate of savings and we ended up saving much more," says Barry Aspey, the Utilities Manager for Heinz. "That helped us decide to opt for the three-year contract. If the new savings estimates are correct, the contract offers excellent value for money and should help us reduce our carbon emissions by 200 tonnes a year." 

Spirax Sarco has also supplied two automatic pump traps to solve a serious control issue for Sembcorp one of the UK's leading industrial utilities and services companies. The pump traps prevent the company's gas heater from stalling, which was previously making it difficult to control the gas temperature. 

Dramatic improvement
Sembcorp uses gas to produce electricity in its own power generation plant on Teesside, as well as distributing gas to some of its industrial customers. The company must heat its gas supply to 40°C to prevent it freezing as it enters lower pressure lines downstream. "Since we've installed the pump traps the improvement has been dramatic," says Development Manager, Dr Michael Capstick. "Prior to the new systems being installed the gas temperature varied widely, but the temperature control is now within 2°C of the set point."

Sembcorp's shell and tube gas heater uses low pressure steam on the shell side to heat gas in the tubes. It handles around 20 tonnes of gas per hour on average, but demand can vary from just a few tonnes up to 40 tonnes per hour. This type of variable load can result in a pressure drop or even a vacuum forming inside the exchanger, preventing condensate from escaping. "Sometimes the condensate backed up until it filled the whole heat exchanger," says Dr Capstick. "This build-up sub-cooled the system until the only way to reach the required temperature was to open up the steam valve to let the steam surge in and push the condensate out."

This cycle led to temperature fluctuations in the gas, according to Dr Capstick. The gas sometimes reached almost the same temperature as the steam, while at other times it froze in the lower pressure pipes. In addition, the thermal shock caused by pushing sub-cooled condensate out of the heater with a surge of steam put extra strain on the equipment, potentially causing maintenance issues in the future. The two Spirax Sarco APT14 automatic pump traps eliminate all these problems by removing condensate in a controlled way, regardless of any back pressure.
 
Spirax Sarco

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