Furnaces

Furnaces

50T Heat treatment Furnace

Working with Goodwin Steel Castings to supply a new 50 tonne heat treatment facility within the Stoke-On-Trent Jubilee Building, Northern Combustion Systems turnkey supply was to incorporate a new 50 tonne heat treatment furnace for the heat treatment of large complex alloy castings. The facility included a charging machine and 500,000 litre water quench tank designed and installed by Goodwin Steel Castings.

The furnace was designed for a load capacity of 50 tonnes plus an 8 tonnes hearth tray, heated in a working survey volume of 5.0m³.

The temperature range of the furnace 200°C to 1250°C was achieved with a temperature uniformity of ±5°C in the range 400°C to 749°C and ±10°C in the range 750°C to 1250°C meeting the requirements of AMS 2750. Minimum heating rate at 10°C per hour and a maximum heating rate at 200°C.

The furnace is fired in 8 zones using four high velocity low NOX hot air burners mounted in the side wall at high level and four in the opposite side wall at low level, suppling a 3.5MW burner rating. Exhaust gas is extracted using eight flue gas recuperators, four each side mounted at low level. This proven firing pattern sets up a high velocity flow of combustion products which circulate the furnace load, resulting in a high degree of temperature uniformity throughout the combustion chamber. The wate gas recuperators provided an overall fuel saving of 36% compared to the existing cold air burner system operating under the same conditions at 1250°C.

The furnace control methodology incorporates, Fixed high air with modulated fuel, Excess Air and Stoichiometric. The system designed to meet with current European safety standards EN746-2 2010.

The furnace design included a 10 Tonne door operated in the vertical plane, counterbalanced driven by a motorised gearbox. A pneumatic door clamping and guide system included to allow quick access of the charging machine to withdraw the heat-treated load for rapid water quenching achieving the crucial grain structure of the maximum 50 tonne load.

Slab Pre-Heating Furnace

Another furnace supplied to a client in North East of England, Northern Combustion Systems carried out a turnkey project for a new Slab Pre-Heating Furnace

The new furnace was designed to operate at 1320°C with a temperature uniformity of ±25°C at soak temperature. The furnace duty to reheat reference slabs in less than 400 minutes – hot furnace / cold slabs. To reheat reference slabs in less than 600 minutes – cold furnace / cold slabs.

The reference load at 73 Tonnes of slabs comprising 3 stacked slabs 270mm x 2050mm x 5600mm.

The hearth size at 6.8m wide x 3.2m deep. The door opening size at 6.8m wide x 1.8m high

The furnace is fired using 4 ultra-low nox medium velocity regenerative burners mounted at high level in the rear wall of the furnace. The burners controlled in 2 equal zones.

Included is rapid cooling, providing maximum airflow through the burners.

The furnace door operated in the vertical plane, counterbalanced and driven by a motorised gearbox. A pneumatic door clamping and guide system is included to guide and seal the door against substantial heat resistant castings. The furnace designed to allow removal of large slabs using customer forklift trucks.

Full operation of the furnace is monitored and controlled via the Siemens 12” colour touch screen HMI and Siemens S7-1200 PLC. Associated controls include:

  • Temperature Recorder Eurotherm 6100A
  • Overtemperature Alarms Eurotherm 2216E
  • Flame Programmers Kromschroder BCU4800
  • Control Actuators Kinatrol

Roller Hearth Tempering Furnace

Another furnace supplied to a regular client in South Yorkshire, Northern Combustion Systems carried out a turnkey project for a new Roller Hearth Tempering Furnace.

The new furnace was designed to operate in a range of 440°C to 800°C with a temperature uniformity of ±5°C throughout the operating range in accordance with Nadcap class 2 & AMS 2750. Computational Fluid Dynamics (CFD) Modelling was provided to simulate uniformity and thermal heat loss to discuss possible countermeasures to optimise the furnace prior to manufacture.

The survey volume furnace chamber size at (W)2.3m x (L)13m x (H)1.8m

The maximum load at 38 Tonnes comprises a single layer of bars in the range Ø70mm to Ø381mm with a 11 meter maximum roll length.

The furnace door and a roller table are operated via an operator control console. A batch load is transferred by the external roller table through the inlet furnace door operated in the vertical plane, counterbalanced and driven by a motorised gearbox. A pneumatic door clamping and guide system is included to guide and seal the door. 16 Internal furnace rollers were specifically designed to perform at maximum furnace temperature and load driven by individual synchronised gear motors with integral speed invertors. Fast speed for loading and unloading of the furnace and slow speed for continuous oscillation of the rollers during the furnace cycle.

The furnace hearth was lined with fire brick and the furnace side walls roof and doors refractory lined with fibre modules. High grade stainless barriers above the rollers were fitted to prevent damage to the lining by lateral movement of the bars in the furnace.

A rear hinged door was included for internal maintenance access.

The furnace is fired using 8 high level burners in one side wall and 8 low level burners in the opposite wall to provide a connected burner rating at 2320kW. The burners firing at 45° target walls to assist recirculation of combustion products around the load. The burners are controlled in eight equal zones down the length of the furnace capable of operating in two control modes:

Fixed Air and Fuel Modulation – to maintain close temperature uniformity when soaking at low temperatures, by providing a high mass flow of high velocity combustion products at a time of low thermal input demand.

Stoichiometric Ratio – This is the most thermal efficient mode and is used for high temperature operation.

Thermocouples in each zone are fed directly to a Yokogawa DX2020 recorder and transmit to the furnace Eurotherm T2550 controller through a modbus link. Hard

Heat treatment facility for heat treating forklift forks

With the use of a clamshell style furnace with an outdated and inefficient burner system Northern Combustion Systems worked with the client to increase production with a new efficient burner system for hardening and tempering cycles. The replacement furnace style installed included a door operated in the vertical plane, counterbalanced and a motorised gearbox. A pneumatic door clamping and guide system included to allow quick access for rapid polymer quenching achieving the crucial grain structure of the maximum 4 tonne load.

The furnace is fired using four high velocity hot air burners mounted at high level. Exhaust gas is extracted using two flue gas recuperators mounted at low level below the burners. The well proven firing/fluing system used to provide optimum temperature uniformity. The waste gas recuperators provided an overall fuel saving of 20% compared to the existing cold air burner system operating under the same conditions.

Hardening at 925°C the burners operate in the stoichiometric mode. Tempering at 450 – 550°C the burners operate with fixed air & fuel only modulation to ensure a high mass flow of low temperature combustion products circulate within the furnace.

The system designed to meet with current European safety standards EN746-2 2010.

Accompanying the first furnace installation a second furnace installed complete with the facility remote access (Industrial VPN) to provide offsite backup.

Walking Beam Furnace for Coil Spring Manufacturing

Full turnkey, design, manufacture and installation of two furnaces to walk spring steel through to pre-heat bars up to 1000°C delivering the bars on demand to a robotic arm, accurately positioning the bars in the coiling machine in the manufacture of coiled springs.

Furnace 1 capacity – Bars in length up to 5 meters ranging from Ø16mm – Ø35mm. Throughput of 1.5 tonnes per hour.

Furnace 2 capacity – Bars in length up to 6 meters ranging from Ø33mm – Ø65mm. Throughput of 1.5 tonnes per hour.

Stockpiled bars at the inlet are automatically collected by the indexing loading mechanism from the loading table. Bars are then in turn collected by the hydraulic operated walking beams to be walked through for heating by Furnace 1: Eight 90kW; Furnace 2: Ten 90kW, medium velocity natural gas burners in 4 control zones down the length of the furnace. The system designed to meet with current European safety standards EN746-2 2010.

The furnace incorporates dense refractory hearth, ceramic fibre lined side walls and roof, hinged side access doors and a pivoted hydraulic operated roof for maintenance access to the furnace chamber.

The furnace is operated via interactive screens on the HMI with the PLC used to sequence the operation of loading machine, walking beams and the discharge diablo roller table.

Bogie Hearth Heat Treatment Furnace

The clients existing furnace had served its purpose for several years and in need of an upgrade. Awarded to Northern Combustion Systems for a technical and competitive tender a new bogie hearth heat treatment furnace was acquired with the inclusion of various existing free issue refurbished furnace components.

The furnace new specification was to guarantee a 3.5 heating time to 900°C with a 27.5 tonne load based upon a hot furnace being loaded with a cold load. Temperature uniformity achieved was better than ±10°C following a soak all complying with European Standard BSEN 742-6.

The scope of work included removal and refurbishment of a select critical parts and components. Dismantling and disposal of the existing furnace structures. Supply and erection of new furnace structure and bogie. Supply of the refractory installation, New combustion control system and a rewire.

PLC controlled burners and combustion controls included 6 existing hot air burners mounted at high level in the side wall and controlled in 3 equal zones. Exhaust products extracted into 3 compact recuperators mounted at low level in the same wall. Combustion and educator air control valves modulate in unison with direct mounted motors to the control valves to eliminate the need for troublesome valve linkages.

Clam Shell Furnace

One of two furnaces designed and built for a large Sheffield industrial group.

The furnaces are mainly for annealing and heat treatment of steel ingots.

The furnace operates in the range 400ºC to 1250ºC and temperature uniformity meets Rolls Royce Aerospace Specification RPS953

High velocity burners fire the furnaces which are capable of temperatures up to 1180ºC and are on a pulse fired control system.  Temperature uniformity conforms to Rolls Royce Specification.

Forge Furnaces

Illustrated is one forging furnace, of which two were designed and built for Firth Rixson Rings at Rotherham.

Furnace operating range is 500ºC to 1250ºC with a choice of stoichiometric or oxidising atmospheres.  Temperature uniformity is to Rolls Royce specification RPS953.

Each furnace is fitted with three 20-therm, hot air, energy saving burners and Nu-way separate recuperators.  These systems can result in fuel savings of up to 35% over conventional, cold air burner systems.

Fully modulating temperature control is fitted, along with continuous temperature monitoring.

Homogenising Furnace

This furnace was supplied to a world leading UK producer of high-nickel, high-performance alloys as part of a larger project involving new equipment and the refurbishment of existing plant.

The furnace uses high velocity hot air natural gas burners and separate recuperators at hearth level to enable uniform heating of the furnace load and lower maintenance compared to other hot air burner systems.

All instrumentation used on the furnace was supplied with serial communications to suit the customers’ existing SCADA system.

Maximum Furnace Load:
17 tonnes

Temperature Uniformity:
RPS953 in the range 950ºC to 1250ºC

Control Modes:
Fixed Air & Fuel Modulation, Stoichiometric Ratio, Reducing Atmosphere, Rapid Cooling

Expected Fuel Savings:
35% over a cold air system operating under the same conditions

Lift-Off Cover Furnace

These furnaces are becoming ever more popular with our heat-treatment customers who have overhead cranes, as it obviates the need for expensive car bottom (bogie hearths) and attendant drive units.

The combustion fired hoods can serve one or more bases, and can work at temperatures in excess of 1250ºC.

Northern Combustion Systems’ innovative hearth flueing arrangement allows temperature uniformity to meet with Rolls Royce, aerospace, and petroleum industries tight specifications of ± 5ºC.

Control varies from simple high/low to the most sophisticated P.L.C and computer linked systems.

The photograph shows a large 7 metres square x 4 metres high unit, serving two bases.  It is for the heat treatment of steel rolls and satisfies a total charge weight of 150 tons.

Having 2 bases also allows the 1st to be fired whilst the second base is to be prepared. Simply swap the hood to the 2nd and unload / re-load the 1st etc, this gives continuation of production / heating.

Rotary Furnaces

Rotary Furnaces have been supplied with throughput rates from 0.5 tonnes/hour to 5 tonnes/hour.

This unit was supplied to a client in Sheffield, England for the heating of steel billets.

Operating Temperature:
1280ºC

Throughput:
5 tonnes/hour

Maximum Load on Hearth:
15 tonnes

Temperature Uniformity:
Better than ±10ºC at 1280ºC

Burner System:
Self Recuperative