The STIRLING MK7 steam boiler is a modern and efficient packaged unit. It is a three pass shell boiler design, coal fired with a fully water cooled combustion chamber. The twin flue boilers all have separate “Walker type” combustion chambers, allowing single flue firing. The boiler, which has been developed over many years, comes in eight models ranging from 1000 kg/hr  to 21,000 kg/hr, with a standard working pressure of 1000kPa. Boilers of a higher working pressure can also be offered.

A complementary range of Stirling Mk7 Dual fired (HFO or Gas) boilers are available

The boilers are manufactured in our Tilbury Road Works in Willowvale, Harare under the supervision of international third party Inspection Authorities, ensuring compliance with the latest British Standard and/or European codes and the Factories & Works Boiler Regulations of the country for which the boiler is destined.

We can custom design our boilers to any capacity or pressure. Contact Us for more information.

Chaingrate Stoker

The boiler is fitted with our proven chaingrate stoker with wide links for improved combustion performance. Being one of the hardest worked components of any shell boiler the stoker is of rugged design. Combustion air is provided by means of balanced draught equipment controlled by either a single lever control unit, or as an optional extra, a solid state type electronic controller.

These devices correctly adjust the induced draught dampers, forced draught damper and stoker motor speed for the most efficient combustion conditions. Efficiencies at full rated capacity of up to 79% are attainable with washed pea coal having a gross calorific value of 29000 kJ/kg (29 MJ/kg). The burning of fibrous fuels can also be accommodated.

A specially developed high efficiency low power input Induced Draught Fan is fitted to the STIRLING MK7 range of boilers. It has curved radially tipped blades for minimum fly ash build up. The fan impellor is statically and dynamically balanced at the assembly stage for smooth operation in service, with low fan speeds ensuring longevity. The forced draught fans fitted to the stoker are of the motor mounted type and are fitted with silencers

Direct coupled twin multistage boiler feed pumps are mounted on the boiler sub-frame, ensuring 100% standby for boiler feedwater.

The Control Panel houses all the associated electrical equipment, and is mounted on the boiler sub-frame in accordance with the packaged boiler concept. The Mountings and Level Control equipment fitted are of the highest quality supplied by reputable manufacturers. Sootblowing equipment is fitted as a standard feature to lengthen the intervals between tube cleaning, thus extending the boiler availability in service.

1. Chaingrate Stoker – has been developed to efficiently burn a wide range of fuel available in Southern Africa. It is built on a rugged fabricated steel frame, which houses the undergrate air distribution system. The links are of wide design for maximum strength and service life and are made up of only two types, a drive link and a common link. Link rods are of the fully floating type and do not require belling or fitting of washers and split pins but are retained by guide strips and can be easily changed.
The drive links engage with solid high grade cast iron drive sprockets keyed to the drive shaft. Side seals are in heat resisting cast iron or carbofrax as preferred.

2. FD Fan – this is flanged mounted off the stoker frame and is fitted with a direct mounted impellor onto a flanged motor, with a silencer unit attached to the inlet duct to reduce noise and improved operational environment.

3. Boiler Feedpumps – twin boiler feed pumps of the Stork horizontal multistage type directly coupled to the drive motor. The pumps are mounted off the boiler frame.

4 Control Panel – housing all the electrical equipment,
indicator lamps, gauges and meters is mounted off the boiler frame in accordance with the packaged boiler concept.

5. Sootblowers – are fitted as standard to our Stirling MK7 boiler for in-service sootblowing of the tubes.

6. Induced Draught Fan – this is generally mounted off the boiler and has curved radially tipped blades, and has been developed for high efficiency with low power inputs