Background

Veolia EfW Plant in Staffordshire generates 29MW of electricity from 340,000tpa of waste from its CNIM boiler. The plant was experiencing fouling in the third, fourth and fifth passes, leading to temperature problems in the exhaust.

The OEM solution was Mechanical Rappers in the 4th pass supported by manual on-load cleaning. However, this presented a range of challenges such as:

• Health & Safety, having to open ports to deliver on-load cleaning.
• Fretting to tubes caused by the Rappers at the support bracket connection, which resulted in tube leaks forcing shutdowns to repair, causing significant budgetary impact to the plant.

ECO 2 pass dimensions: 

• 6524mm width, 3318mm across.
• Bundle depth: 1734mm.
• Tube pitches: 96mm horizontal and 102mm vertical.
• Tube size: Diameter 38mm x 4mm.

Temperatures: 

• Flue gas temp approx. 370-230 degrees.

Project

KRR ProStream supplied, installed, and commissioned 2-off SPG-r10s and ancillary equipment. The SPG-r10s were Installed in Economiser 2 (pass4) between the top and bottom pair of bundles. Cycles were set at 6/day to eliminate the amount of on-load cleaning needed and remove the Rapper system from service.

Results

The SPGs were installed on the 4th pass of boiler 1, boiler 2 has not been modified and has been used as a comparison:

• Removal of Rappers in the 4th pass that were causing fretting on the tubes.
• No negative affect of removing the rappers from day 1 of commissioning.
• Full cleaning performance in the 4th pass with no debris removed from recent on-load cleaning.
• Additional (unexpected) cleaning performance noticed on the 5th pass, noticed during on-load cleaning compared to boiler 2.
• Overall reduction in fouling in the earlier passes since the SPGs have been in operation noticed during on-load cleaning compared to boiler 2.
• Exhaust temperatures now stable at 150 degrees helping to achieve targets of the latest environmental regulations. 

Iain Wilson Maintenance Manager commented:

“The performance of the SPG-R’s have surpassed my expectations and I am thoroughly pleased with the results.”