Contact Lars-Olof Larsson
Phone: +46 8 80 90 13
Production in many industries would be impossible without steam. In this context, the electric boiler can play a key role, while also reducing overall energy costs.
A ZETA hot water system offers great flexibility. The system is adaptable for use in combination with alternative energy sources such as biomass, heat pumps, etc. Combined operation with oil is already common, the actual method of heating varying with the price and availability of the different energy sources.
Electric boiler, overview
ZETA electric boilers save a lot of money by reducing oil imports
Apart from the cost savings and reduced dependence on oil imports, with an electric water boiler it lessens the impact on the environment.
Apart from the cost savings and reduced dependence on oil imports, this lessens the impact on the environment and alleviates land and water acidification.Electric boilers are also used as standby units for other boilers during shutdowns, overhauls, etc.
ZETA electric boilers are among the finest units available anywhere in the world – as our customers in Sweden and abroad can testify. ZETA boilers are available as both steam and hot water boilers, for use directly on-line or in combination with an accumulator. The basic design – which originated in the 1920s – has undergone continuous development to keep pace with market demands and general advances in technology.
Boilers used in combination with an accumulator enable cheap night-rate electricity to be used, thereby conserving more power for industrial use during the day. The accumulator is particularly useful when there are considerable fluctuations in peak demand for hot water.
Economic aspects must be considered in addition to the general advantages outlined above.
A ZETA electric boiler installation is characterized by low capital cost, high efficiency, minimum maintenance and extremly high reliability – all essentioal factors in evaluating the overall economy of the installation.
The ZETA boiler (steam or hot water) is a compact unit which can be installed in confined spaces. Since an existing building can often be used, the overall cost of the complete installation can be reduced to an absolute minimum, given the low cost of the boiler itself.
The boiler is extremely efficent. In the steam version, 98-99% of the input power is converted to steam, the exact efficency depending on feed water conductivity and system design. In hot water system the corresponding figure is also about 99%.
The ZETA boiler has been manufactured for more than 60 years, during which time it has demonstrated extremely high reliability, a feature attributable to the simplicity of the design. There are no pumps, motor or other complex components inside the boiler.
The current from the phase electrodes flows directly through the water, which is heated in the process. The current is a function of the active surface area of the electrodes and the water conductivity. The active area of the electrodes can be infinitely varied by operating the control screens, thus enabeling output to be controlled between a minimum load of 10-20% (depending on boiler size and voltage) and 100%. Water conductivity varies with temperature and salt content.
The temperature of the water returned to the boiler should, therefore, be maintained at a certain minimum value by the admixture of water from the boiler outlet. The thermostatically controlled valve in the return line ensures correct mixing.
The electrode principle
Electric current is conducted through the water by electrodes, and the water itself (which is heated without energy loss) provides the resistance whitch generates the heat. In the hot water boiler, current and therefore, output are controlled by operating electrode screens. In the boiler, however this function is achieved by regulating the water level. Neither type can run dry since the current will be interrupted if the electrodes are not immersed in water.
For all kinds of electrode boilers, troublefree steam or hot water production requires that the feed water meets certain specifications. The conductivity of the feed water supplied to a 10kV ZETA boiler should not exceed 5uS/cm. Fully demineralised water or pure condensate with a low conductivity should be used where possible. In addition, the pH of the water should be 8.5-9.5 and the oxygen content less than 0.02 mg/l.
|VOLTAGE||6 kV||10 kV||15 kV|
|Design temperature primary side||130°C||160°C|
|Design pressure primary side||5 Bar||10 Bar|
|Operating temperature primary side||120°C||145°C|
|Operating temperature secondary side||110°C||120°C|
| ZVPIZHPI – BOILERTYPE WITH HIGH RESISTANCE INSULATED NEUTRAL POINT.
ZVP/ZHP – BOILER TYPE WITH DIRECTLY EARTHED NEUTRAL POINT.
BOILERS TO SPECIFICATIONS OTHER THAN STANDARD CAN ALSO SUPPLIED.
|ZETA Steam boilers||ZETA Hot Water boilers|
|Output||2-70 MW||Output||1-40 MW|
|Voltage||Max 15 kV (20kV)||Voltage||Max 20 kV|