ICS019

Description

SSAB Tunnplåt AB is a part of SSAB Group a global producer of high strength steel sheets in different thicknesses. The products are produced in many variants like zinc protected, paint coated and raw steel sheets. The steelworks are located in Borlänge in Sweden. Project covered complete installation of the Nozzle Cooling Air System in Zone 1 and Zone 2, modification of Double Fuel Nozzle System (DFNS) into Single Fuel Nozzle System (SFNS) and revamp of furnace shell wall and refractory wall around three burners equipped with F1/F2 mode (low/high temperature mode) in Zone 2 in Furnace 301. Moreover, the fuel collector in Zone 2 was exchanged for a new one suitable for future work with natural gas. Revamped furnace is a part of steel sheet production plant where steel slabs are rolled. BeyondInvestor’s expectation was to install nozzle cooling air system in order to enhance the lifetime of the fuel nozzles reduce the NOX emission down to 62 ppm normalized to 5% of O2 (excepting Zone 5/6) to meet the current authorities demands without lowering in the same time the overall firing capacity of the furnace and production capacities.

Installation

The installation consists of 3 sets of HTB divided into 4 zones. All burners are propane or LPG fired and after certain changes can be Natural Gas fired as well. The recuperated combustion air is used with the temperature in the range of 590 – 640°C. Zone temperature is between 1100 – 1270°C.

ICS scope of supply

• Zone 3 – upper heating zone:
  8 x HTB-DL2.8 (2800 kW) – all burners equipped with hot condition mode only,
• Zone 4 – bottom heating zone:
  9 x HTB-DL2.7 (2675 kW) – 5 burners with cold and hot condition mode and 4 burners with hot condition mode only,
• Zone 7 and 8 – bottom soaking zones:
  9 x HTB-DL1.2 (1150 kW) – all burners with cold and hot condition mode,
• burner fittings,
• detailed engineering of combustion system,
• control system description,
• detailed documentation of burner and zone piping,
• engineering support during erection and commissioning.

Advantages

• NOX emission reduction down to less than 62 ppm compared to 125 ppm before any HTB burners installation,
• uniform temperature field and heat flux in the furnace,
• improvement in product quality due to very even temperature in the furnace in comparison to the previous combustion system,
• unit fuel consumption reduction due to longer lifetime of the refractory on the skid system (lower thermal loss, lower and stable waste steam production between yearly maintenance stops).