Waste-to-energy plant, CHP
In October 2006 we handed over one of the most modern and efficient waste-to-energy plants in Denmark to I/S Reno Nord in Aalborg.
The new furnace line 4 replaced the two old furnace lines 1 and 2, which were supplied in 1981. The existing furnace line 3, supplied in 1991, was kept as a replacement.
We supplied the furnace/boiler line complete with auxiliary equipment, And our sub-supplier provided a complete turbine/generator set.
What does our customer say? Managing director of Reno-Nord, Henrik Skovhaug tells:
“Since signing the agreement with B&W Vølund, we have been very pleased with the professional and cooperative attitude that characterises the team of employees who has met us at Reno-Nord.
“The process of establishing the new line was successful as well as on time.
“Additionally, we are very satisfied with the product which we consider superior.
“Each step of the process operates perfectly including B&W Vølund’s complete furnace/boiler line with auxiliary equipment. There is no doubt that we have chosen the right supplier.”
Our scope of supply
Our supply included a furnace/boiler with economiser, an ash/clinker system, a DeNOx system (dosing of ammonium to the boiler first pass), an electrical and DCS system, and an electrostatic precipitator after the economiser. Furthermore, the steel structure of the building was supplied as an integrated part of the boiler’s steel frame.
The fuel feeding and combustion technology
The plant is equipped with an air-cooled DynaGrate®, prepared for later conversion to water-cooling and with feeding of waste by a so-called pusher, which ensures homogenous feeding without the risk of backfire.
Water-cooled wear zone reduces refractory volume and maintenance costs
The Reno-Nord plant is equipped with a water-cooled wear zone. The wear zone reduces uncooled refractory lining and thereby the build-up of slag. This reduces maintenance costs.
Many advantages of the water-cooled wear zone:
A water-cooled wear zone absorbs approx. 80-120KW per m2. A typical system can receive 1.5-2.8 MW’s of extra energy - energy which is absorbed as radiant heat.
- There are no slag deposits as the wear zone is a relatively cold 200-300° C. The system therefore retains its active grate area throughout the operational period.
- Operational stoppages for slag removal aren’t required. Heat absorption in the wear zone is five to 10 times higher than in the boiler’s two radiation passes
- Heat absorption in the wear zone reduces the furnace temperature and therefore allows increased heating value and maintains waste capacity.
- The water-cooled wear zone replaces the refractory lining in the system’s most heavily used area. Experience shows that a water-cooled wear zone has a longer life than refractory lining.
- The water-cooled wear zone works actively as an expansion segment between boiler and grate.
Reno-Nord’s water-cooled wear zone is directly connected to the boiler circuit. This mean that the wear zone is connected in natural circulation with the boiler drum and constitutes an integrated part of the boiler. This coupling increases the overall efficiency of the plant. Due to the high operational temperature, the wear zone must be covered with Inconel®.
Superior performance: thermal efficiency of 100%
The nominal capacity of the plant is 20 t/h waste at a calorific value of 12 MJ/kg, corresponding to approx. 160,000 t/year. The boiler generates 80 t/h steam at 50 bar, 425°C.The turbine generates approx. 18 MW of electricity, which was fed into the main grid. Furthermore, the plant supplies approx. 43 MW of heat to the district heating network in Aalborg, Denmark. The efficiency is approx. 100%, and the energy produced supports approximately 16,000 houses with electricity, and approximately 30,000 houses with district heating.
|Calorific value, lower
|TOC, bottom ash
|Flue gas temperature before superheater
|Outlet temperature boiler
The values are before flue gas cleaning.
The plant limit values complies with the EU directive on waste incineration. Naturally the plant is equipped with a modern flue gas cleaning system.