REFCONS CASE AT WASTE INCINERATION PLANT Country:Denmark Plant name:AffaldPlus, Næstved Boiler Type:Steam Power Capacity:- Main equipment supplier:Babcock & Wilcox Vølund ApS Number of boilers:2 Main Fuel:Waste.

REFCONS CASE AT THE WASTE INCINERATIONS PLANT AffaldPlus History: The Waste incinerator lines no. 2 and no. 3 were build by Vølund back in the 1994 as a furnace with 3 grates and a system of pre-casted plates with holes for cooling of the sidewall, the primary air inlet comes through the grates and the secondary air inlet came through tubes in the sidewalls. See drawing

Furnace as it was build in 1994

REFCONS CASE AT THE WASTE INCINERATIONS PLANT AffaldPlus History: The furnaces were upgraded in November 2009 by Vølund. As it is done in many furnaces in Denmark the wear zones above the grates were replaced with cooled tube wall in the burning zone. At the same time the secondary air inlet were moved from the sidewalls to the ceiling and the pre-casted plates were removed. Still the primary air inlet comes through the grates. The sidewalls above the new cooled wear zone still remain with a 520 mm thickness. See drawing B and B.

Upgraded furnace build in 2009

Construction of side wall to boiler, buttom 1st. pass.

REFCONS CASE AT THE WASTE INCINERATIONS PLANT AffaldPlus Problem: After the upgrade of the furnaces in 2009, the new secondary air inlet through the ceiling, consists of 2 tubes that guide the air in the wanted direction, the air blows at a speed of m/sec. The construction generates very high temperature, I don’t have an exact measurement from the area, but the clinker is flowing down the wall and my guess would be a temperature about °C. The walls were renewed and casted in Hasles D65TA back in the summer 2010, at the same time the tubes in the ceiling were redirected by Vølund, but after 9 months of operation the walls were very damaged and needed a quick temporary repair with gunning mass – just to operate 1 more month before the summer stop. See Photo sheet 1, 2, 3 and 4.

Photo sheet 1: Upper left wall before and after 9 months operation

Photo sheet 2: Mid left wall before and after 9 months operation. The damaged area is in line of the secondary air inlet direction.

Photo sheet 3: Mid left wall before and after 9 months operation. The damaged area is in line of the secondary air inlet direction.

Photo sheet 4: Mid right wall before and after 9 months operation. The damaged area is in line of the secondary air inlet direction.

REFCONS CASE AT THE WASTE INCINERATIONS PLANT AffaldPlus Problem: This summer 2011, Refcon renewed the walls again, casted in D65TA and Vølund has done some changes in the air inlet speed. There was an inspection after 6 weeks of operation, and it still seems that there is very high temperature in the area – and I fear that the walls will need to be renewed again next summer. The same problem is seen on other waste incineration plants in Denmark, the solution has so far been casting in the D65TA, which has given the best resistance to the flowing clinker problem, but clearly for Refcon and AffaldPlus a lifetime of 9 months isn’t good enough. See Photo sheet 5, 6 and 7.

Photo sheet 5: Mid left wall renewed this summer 2011 and after 6 weeks operation.

Photo sheet 6: Mid right wall renewed this summer 2011 and after 6 weeks operation.

Photo sheet 7: Mid right wall renewed this summer 2011 and chicane wall after 6 weeks operation.

REFCONS CASE AT THE WASTE INCINERATIONS PLANT AffaldPlus Refcons wishes for this case: It would be nice if Vølund would build a furnace that causes lower temperature in the furnace room. I can have my doubt if that is a realistic wish as Vølund already have done some changes to the secondary air inlet – but clearly we still have a very high temperature. It is the believe of Vølund that the problem comes from the diffusion of flowing clinker into the casted wall, that cause the wall to kind of “melt” away at lower temperature than the mass would without the pollution of clinker. And it would be nice if Hasle would design a mass that better can resist flowing clinker at high temperature.