Justifications for employing the HSS fully automated air heater and gas- gas heater restoration system.

This washing technique has successfully restored pressure drops to post commission restoration levels in virtually all cases in power stations throughout the world: proven technology developed and updated since 1984 :

HSS was instrumental in introducing computers and robotics to the restoration industry. This saves money, valuable downtime and most important of all reduces the risk to personnel in hazardous areas as unlike in the case of a hand-held operation all personnel remain outside the air heater and at a safe distance.

The automated restoration system employed by HSS is a highly effective method of recovering deep hot or cold end fouling in the shortest time possible, thus restoring pressure drops to their original commissioning levels even from almost complete blockage conditions. The nozzle is moved in steps and the speed of rotation is computer-controlled to maintain a constant relative velocity between  restoration element and thus a uniform restoration of the heater matrix. Because of the level of control achieved with this automated system, the complete surface of the heater is covered during one wash cycle. This level of restoration is near impossible to achieve with a hand-held operation owing to operator fatigue and/or inability on the part of the operator to maintain the jet at a constant 90-degree angle perpendicular to the element surface.

Elements in sound mechanical condition, including enamelled elements, do not suffer damage in the process even though pressures as high as 300 bar are employed owing to the unique HSS hydraulic restoration head and nozzle design producing a high-energy water “laser” rather than merely a thin stream of water at high pressure at a very low flow-rate, as is the case with a hand-held operation.

In order for a hand-held operation to be even partially successful it is often necessary to remove the entire heater matrix (or at the very least the top and mid-packs so as to gain direct access to the top-side of the cold-end baskets). This in turn involves several weeks of lost productivity and even if this work has been factored into a scheduled plant shut-down it involves intensive manual labour with the added risk of manual handling accidents.

The time allocated for each restoration can be discussed and agreed prior to the contract directly with the HSS engineer. A maximum restoration time can then be allocated with the HSS engineer basing the restoration time on a “worst-case fouling scenario” (unless detailed pressure drop information can be provided beforehand). This restoration time may be reduced depending on plant-specific situations thus allowing the station engineer to provide a realistic time schedule to the grid and thus avoid possible penalties through the incorrect declaration of plant availability. It is unlikely that such a detailed schedule would be provided in the case of a hand-held operation.

A detailed site survey is carried out when the location is receiving the first air heater restoration or has undergone plant modification. This survey provides HSS with a detailed record of the operating, safety and restoration requirements of the power station, complying with all current legislation and international safety standards in order to offer the most effective service in the shortest time possible.

Unlike general hand-held operations, the HSS automated restoration system is a bespoke service: the restoration procedure differs between air heater design, e.g. Ljungström, Howden, or Rothemühle air heaters, gas-gas heaters, and the type of elements fitted, especially FNC elements.

Justifications for employing the HSS fully automated air heater and gas- gas heater restoration system.

This washing technique has successfully restored pressure drops to post commission clean levels in virtually all cases in power stations throughout the world: proven technology developed and updated since 1984 :

HSS was instrumental in introducing computers and robotics to the restoration industry. This saves money, valuable downtime and most important of all reduces the risk to personnel in hazardous areas as unlike in the case of a hand-held operation all personnel remain outside the air heater and at a safe distance away from the high-pressure water nozzle.

The automated restoration system employed by HSS is a highly effective method of recovering deep hot or cold end fouling in the shortest time possible, thus restoring pressure drops to their original commissioning levels even from almost complete blockage conditions. The nozzle is moved in steps and the speed of rotation is computer-controlled to maintain a constant relative velocity between jet element and thus a uniform restoration of the heater matrix. Because of the level of control achieved with this automated system, the complete surface of the heater is covered during one wash cycle. This level of reastoration is near impossible to achieve with a hand-held operation owing to operator fatigue and/or inability on the part of the operator to maintain the jet at a constant 90-degree angle perpendicular to the element surface.

Elements in sound mechanical condition, including enamelled elements, do not suffer damage in the process even though pressures as high as 300 bar are employed owing to the unique HSS jetting head and nozzle design producing a high-energy water “laser” rather than merely a thin stream of water at high pressure at a very low flow-rate, as is the case with a hand-held operation.

In order for a hand-held operation to be even partially successful, it is often necessary to remove the entire heater matrix (or at the very least the top and mid-packs so as to gain direct access to the top-side of the cold-end baskets). This in turn involves several weeks of lost productivity and even if this work has been factored into a scheduled plant shut-down it involves intensive manual labour with the added risk of manual handling accidents.

The time allocated for each restoration can be discussed and agreed prior to the contract directly with the HSS engineer. A maximum restoration time can then be allocated with the HSS engineer basing the clean time on a “worst-case fouling scenario” (unless detailed pressure drop information can be provided beforehand). This restoration time may be reduced depending on plant-specific situations thus allowing the station engineer to provide a realistic time schedule to the grid and thus avoid possible penalties through the incorrect declaration of plant availability. It is unlikely that such a detailed schedule would be provided in the case of a hand-held operation.

A detailed site survey is carried out when the location is receiving the first air heater clean or has undergone plant modification. This survey provides HSS with a detailed record of the operating, safety and cleaning requirements of the power station, complying with all current legislation and international safety standards in order to offer the most effective service in the shortest time possible.

Unlike general hand-held operations, the HSS automated restoration system is a bespoke service : the restoration procedure differs between air heater design, e.g. Ljungström, Howden, or Rothemühle air heaters, gas-gas heaters, and the type of elements fitted, especially FNC elements.