The SHBV COCHRAN range of Economisers are designed to recover heat from Boiler exhaust gases, and transfer this to the incoming Boiler feed water, thus increasing the overall Boiler Thermal Efficiency.

 Economisers are normally fitted to Boilers fired with natural gas, although units of special design may be fitted to Boilers fired with liquid fuels. However, the degree of heat recovery may be limited as a result of possible “dewpoint” corrosion.

Design Features

Two standard ranges of Economisers are available, increasing the Boiler Thermal Efficiency by a nominal 3.5, and 5.0%. The resultant fuel saving will be in the order of 4.25, and 6.0% respectively.

For the 3.5% gain units, the Boiler Exhaust gases are cooled by a nominal 80 °C, with an associated feed water temperature rise of around 24 °C. For the 5% gain units, the values are 115 °C, and 34 °C respectively.

Both ranges are designed to limit the gas side pressure drop to less than 0.5 ² WG, and 0.5 bar on the waterside.

The Economisers are manufactured from extended surface tubing, within a carbon steel casing. Removable covers give access to the tubes, which can easily be removed if necessary.

They have a design pressure of 24 barg, and design temperature of 300 °C. They are CE marked in accordance with the Pressure Equipment Directive (97/23/EC).

For dual fuel firing, when prolonged firing on oil is likely, the Units may be supplied with an integral gas bypass. The alternative to this is to incorporate a water bypass in the feed pipe work, thus allowing the units to “run dry”.

The Economiser Units are ideally arranged for a vertical gas flow, but if used with a horizontal gas flow, then additional vent and drain connections are fitted.

Complete Package

 Each unit is supplied with the following equipment as standard: -

• Safety Valve.
• Vent Valve.
• Drain Valve.
• Outlet water temperature gauge.
• Auto Bleed Valve.
• This is supplied complete with an actuator switch, which is fitted to the Boiler feed water-regulating valve. At low operating loads, or whenever the regulating valve approaches its closed position, the Bleed Valve operates to ensure a flow of water at all times through the Economiser. This prevents “steaming” within the unit, and thus possible “vapour locking”. The outlet from the Auto Bleed valve should be piped back to the Boiler Feed tank.
• External insulation and Aluminium cladding.