Sliding feed water control
The main points
- Very uniform steam pressure
- Reduces temperature change loading
- Prevents unnecessary burner starts
- Savings of up to 2% possible
- Easy to retrofit
- Short amortization time
Constant water level with sliding control
Feed water control on water-tube and flame-tube boilers is used to keep the boiler water level constant. In many cases, however, it wastes valuable fuel. Because these control systems are often poorly adapted or too simple, even small improvements can save considerable amounts of energy. Savings potential depends on the firing plant, but in some circumstances is as much as 2% of the fuel that is used: A new feed water control system reduces environmental pollution, quickly pays for itself and saves money.
In the worst case, unoptimized plants have a feed water pump with a two-point controller: That means the controller switches the pump on at the lowest water level and switches it off again at the highest water level. The pump runs during this time at full capacity, pumping a large amount of water into the boiler. If this water is not preheated, the boiler pressure and temperature immediately drop significantly. That affects the load controller, resulting in increased burner load or even in a burner restart.
In this way, simple discontinuous feed water control has a direct effect on the entire plant and causes significant fluctuations, frequent burner starts and compressed air losses. If the water level in the boiler is raised too much, there is also the danger that water will be carried along with the steam, lowering the quality of the steam considerably.
Sliding feed water control eliminates these fluctuations and keeps the water level within very narrow limits so that all the other boiler control systems work evenly. This simplifies operation, improves steam quality, saves fuel and reduces operating costs. The optimized technology consists mainly of an improved water level probe, a speed-controlled pump and a control valve. These components are individually customized for each task by SAACKE and significantly improve the efficiency of a firing system.
