Boiler feedtank systems

What is a feedtank? A feedtank, in a steam plant, is normally the meeting place for cold make-up water and condensate return. Cold make-up Flash steam loss At worst . . . ... make-up water and flashing condensate are fed into the tank above the water surface. Flash steam with all its heat is lost to atmosphere and the final mixture of cold make-up and remaining condensate is colder than it could be. Cold make-up Flash steam from blowdown Condensate return At best . . . ... both flows, together with blowdown flash steam are distributed through sparge pipes well below the water surface. The sparge...

The Spirax Sarco flash condensing deaerator head ... On larger boiler plants pressurised deaerators are sometimes installed and live steam is used to bring the feedwater up to above 100°C to 'drive off' the oxygen. This action is normally enhanced by the steam 'scrubbing' the feedwater. Freed oxygen and other gases are vented with some live steam to atmosphere. Pressure deaerators have to be treated as pressure vessels and with the necessary controls and safety devices they become expensive. As with most things there is a compromise - Spirax Sarco have developed a unit for fitting to any feedtank...

When a feedtank becomes an atmospheric Spirax Sarco can supply the complete package:- Austenitic stainless steel is used for all wetted parts. Boiler blowdown heat recovery Stainless steel feedtank. Flash condensing deaerator head. Vacuum breaker Steam injection system. Access cover All the necessary controls and fittings to create an atmospheric deaerator system. Recirculating feedwater spray systems When the condensate return rate is high and the cold make-up flowrate is intermittent it is likely that valuable flash steam will be lost through the vent. To improve the thermal efficiency and...

Vacuum breaker Vent head Recirculated water to spray head Condensate return Flash condensing deaerator head Water level control Temperature gauge Steam injector Level indicator Recirculating pump

The feedtank range The table below shows the standard range of feedtanks based on metric plate sizes and indicates the internal dimensions and the total nominal capacity. The working capacity will be reduced depending on the working level and control system chosen. The empty weights are typical and can be used together with the nominal capacity in kg (litre) to give a total weight to be used for support calculation purposes. * Excluding connections. Materials All wetted parts are in welded austenitic stainless steel. This material has proved to be ideal for most boiler feedtank applications and...

A flash condensing deaerator head consists of three parts, the mixing unit with a PN16 or Class 150 mounting flange, the immersion tube with a plate top flange, and two gaskets. The plate flange is sandwiched between the mixing unit and a mating flange welded to the top of the Spirax Sarco feedtank to act as a stiffener. All parts are manufactured from weldable austenitic stainless steel and held in place with stainless steel nuts and studs. The flash condensing deaerator head is easily fitted to other tanks. Deaerator head selection We recommend that selection of a deaerator head is carried...

Other controls and fittings Steam injection systems Spirax Sarco steam injectors are available in three sizes to cover most requirements. They ensure quiet but vigorous mixing of steam and feedwater to drive off the dissolved oxygen content down to approximately 2 ppm. This action minimises the amount of oxygen scavenging chemicals required. The temperature of the feedwater is maintained at a high steady level for smooth boiler operation. Feedtank level controls The design and operation of water softening plant calls for full flowrate and never a trickle. The flow is therefore normally controlled...