Case Studies

Case Study 1

German Power plant, 300 MW Unit

2 x Ljungström 2CXS 275/2600

Element depth 2,100mm (700mm x1)

Cleaning Process before using Hydrotech prior to 2001:

Remove entire element layer, top side; transport to ground floor to be washed by conventional

hand-held means. In situclean of middle and cold side elements by conventional hand-held

means. Subsequentreinstatement of hot-endelements once satisfactory clean of remaining

elements has been carried out by labour-intensive wash. Alternatively, in situ clean of entire

preheater matrix from top-side only, incorporating the in-built soot-blowing mechanism.

Total duration of shut-down: 3 weeks

Clean Process since 2001 employing the Hydrotech System automated cleaning:

Day 1:

Arrival on site, preparatory work undertaken (Unit still generating/cooling down)

Day 2: 08:00

Scaffold underside of preheater: Commence internal set-up of cleaning equipment, cold-side

under; Low-pressure, high-bore flush from above. Additional measures: Gas ductwork above

and below preheater matrix to be protected so as to avoid water/moisture ingress past the

dampers above preheater or into the electrostatic precipitators below air preheaters

16:00

Commence HP wash of baskets: 26 hour clean envisaged in two passes.Constant monitoring

of drainage and effluent created during the wash including subsequent introduction of Sodium hydroxide solution as and when necessary

Day 3: 18:00

End wash of baskets; removal of equipment; commence forced-drying of preheater matrix

Unit declared available for generation

Case Study 2

Dutch Power plant, 600 MW Unit

2 x Rothemühle twin-flow Vu 14.5

Primary air element depth 2,200mm (950x2; 300x1)

Secondary air element depth 2650mm (1175x2; 300x1)

Cleaning Process before using Hydrotech prior to 2002:

Remove entire element layer, top side; transport to ground floor to be washed by conventional hand-held means. In situ clean of middle and cold side elements by conventional hand-held means. Subsequent reinstatement of hot-end elements once satisfactory clean of remaining elements has been carried out by labour-intensive wash.

Total duration of shut-down: 3 – 4 weeks

Clean Process since 2002 employing the Hydrotech System automated cleaning:

Day 1:

Arrival on site, preparatory work undertaken (Unit still generating/cooling down)

Day 2:

Commence internal set-up of cleaning equipment; removal of compensator to allow fixture of rotary joint; scaffold underside of preheater; Additional measures: Gas ductwork above and below preheater matrix to be protected so as to avoid water/moisture ingress past the dampers above preheater or into the electrostatic precipitators below air preheaters

Day 3: 08:00

Commence HP wash of baskets: 30 hours envisaged in two passes. Constant monitoring of drainage and effluent created during the wash including subsequent introduction of Sodium hydroxide solution as and when necessary

Day 4: 14:00

End wash of baskets; removal of equipment; reinstatement of compensator; commence forced-drying of preheater matrix

Day 5:

Unit declared available for generation