Electrode boilers are used in industrial applications, where large amounts of water must be converted to steam. Electrode boilers have a very quick delivery time, which makes them excellent for use in intermittent or cyclical operations.
Electrode boilers work by passing current through the water, between electrodes. They can be used to generate hot water or steam.
Extremely quick response time; flexibility for cyclical or intermittent operations Clean firing - no emissions of products of combustion No stack - with no combustion there is no venting or stack required Highly efficient with minimum losses Compact size - smaller volume and footprint than fossil fired boilers Available in wide range of sizes as boiler only or in tank-type models.
Demand and energy charges can result in higher operating cost.
Electrode boilers can be applied wherever there is a need for hot water at 75 to 80 psig pressure, and steam at 15 to 250 psig pressure and in capacities up to about 50 MW (170 Million BTUH) in a single unit.
Applications with load swings (daily, hourly, weekly) Areas with high gas prices, particularly with the DDC (the demand charge)
Applications to Avoid
High load factor installation where demand and energy costs outstrip the benefits.
Technology Types (Resource)
Electrode boilers use electrodes to pass current through the water to be heated. The resistance of the water produces heat, which converts the water to steam. Water treatment is extremely important for electrode boilers, but the electrode boilers typically require a lower quantity of chemicals. This translates to a lower overall water treatment cost.
Electrode boilers are about 100% efficient in converting power to heat (3,412 BTUH per kW or 293 kWh per million Btu) with only a minimal percentage of radiation loss from the exposed surfaces of the boiler.
This contrasts to fossil fuel boilers that have combustion efficiencies in the 60 to 80% range, depending on the boiler age and condition, plus other losses.
Combustion efficiency simply indicates the flue gas loss. Boiler efficiency also includes the blowdown and standby losses. Whether comparing new or existing boilers, their most efficient operating point is usually somewhere between 60-90% load. Typically, gas boilers exhibit larger standby loss because of the flue, which has a chimney effect for the heat in the boiler.
When you are evaluating a change in steam production due to a new steam use (which would increase steam generation) or steam conservation (which would obviously reduce steam production), be very careful to consider incremental boiler efficiency and incremental energy costs.