SMELT X WASH -X Valmet Energy and Environmental (ENE) North America Mike Ward
SMELT-X
Smelt-X Overview Smelt is extracted by an ejector driven by pressurized air Simple design, No moving parts = Reliable, Reusable 200 + Smelt-X projects have been carried out in pulp mills in Europe, North and South America, Asia, Africa and Australia Smelt bed cooling time can be reduced to 4 6 hours from 15 35 hours. As a result, time spent in recovery boiler washing can be reduced by 10 30 hours Ejectors remove smelt directly into dissolving tank without exposing spouts to high smelt flow and temperature 3
Smelt-X Ejector Operates by entrainment and siphon effect Compressed air acts to shatter smelt Compressed air is preheated before entrainment of smelt Air Pipe Support Coil Air Connection 90 psi Suction Tube Smelt Spout Ejector Tube Mini Hood 4
Flexible Design 3 Standard designs are used Insures smelt removal from the deepest point of the furnace floor 5 3 Standard designs are used
Compressed Air Compressed air causes a Venturi effect which creates the suction to remove molten smelt The longer the air tube the more the air gets preheated and the less likely it is that the smelt will freeze inside the ejector Optimal distance between ejection tube exit end and air tube exit end Is 12 inches 6
Extension Hook & Latch type extension used for some hood styles 7
Smelt X Operations A smelt bed temperature of approximately 1600F is best to maintain the bed molten and flowing Firing black liquor is effective at maintaining the desired extraction temperature Smelt-X ejectors are installed into spouts and valves controlling air flow are opened Smelt extraction with ejectors is continued until the smelt pool is empty Thermocouples are used to monitor bed temperature Firing is stopped, pressure reduction and cooling begins 8
Benefits Reduced Time: - Faster cooling of bed - Less time for cleaning furnace bottom Inspection and maintenance can be started earlier Reduced Cost: Shorter outages Lower cleaning costs Less bed chemicals not recovered Better Inspection: Better inspections can be performed on areas where smelt would have otherwise been covering 9
Video 10
11 WASH-X
Wash-X Overview Water is sprayed to the floor as soon as safe bed temperatures have been reached Water can be sprayed to furnace floor through liquor guns or nozzles installed in various openings Several water sources can be used 0 0 Eductors are installed on the furnace floor and operated continuously throughout the whole boiler washing period Once superheaters are clean, the mixing devices are removed and floor is emptied from wash water using smelt ejectors 12
Wash-X Operations Salt concentration is used to monitor washing effectiveness Up to 8 eductors are inserted to start floor washing in parallel with superheater washing Hot water results in faster washing and may also be needed to dissolve large ash deposits which fall to the floor The wash pool volume protects the floor from large falling deposits Wash salt concentration density is periodically measured If the wash water density increases above 1.25, higher wash water flow is likely to be beneficial. Densities below 1.1 would indicate that wash water flow rate can probably be reduced without significant reduction in dissolving rate Page 13
Typical time schedule for Smelt-X & Wash-X h Bed reduction 8 00-08 Oil firing 76 02-09 Smelt-X 3 06-09 Depressurization 5 09-14 Economiser washing 4 14-18 Boiler bank washing 4 18-22 Superheater washing 8 22-06 Floor washing 16 14-06 Wash water removal 2 06-08 Drying 3 08-11 Safety roof installation 4 11-15 Scaffolding 15 - Total time spent on cooling and washing 23 09-08 Friday Saturday Page 14
The outage begins ahead of schedule Page 15
References Number of Smelt-X projects Total Smelt-X Projects S Am N Am EMEA 2007 1 1 2008 2 2 2009 6 6 2010 9 1 8 2011 21 10 2 9 2012 24 12 0 12 2013 24 13 2 9 2014 39 23 1 15 2015 55 27 5 23 Page 16 Total 181 86 10 85