The ZGH-300 ECO is a low temperature boiler fuelled with wood chips with the maximum size of 30 mm and maximum humidity of 40%. Its innovative design and advanced control algorithms ensure high efficiency and conformity with Class 5 requirements according to EN 303-5:2012 standards and the Ecodesign Directive. It also offers easy operation, reliability and stable work.
The heating unit comprises a furnace and a heat exchanger. Ceramic fuel chamber is a heat accumulator, while the use of two exhaust gas passes reduces emission of harmful substances to the natural environment. The lower part of the chamber is equipped with travelling grates. The chamber below them is divided into three zones to improve the combustion process. The air supplied to the chamber is divided into primary passage (combustion process) and secondary passage (aftercombustion process). The body of the heat exchanger is a pressure vessel with a bent and welded structure, with a return chamber and combustion tubes.
Boiler exhaust gas goes to a cyclone dust separator where a thicker fraction of dust is separated and exhaust gas is cooled down. Cyclones are characterised by high efficiency of operation with good resistance to erosion and drag. In the standard version, the maximum acceptable operating temperature is 350°C. Cyclones can operate with increased and lowered pressure.
Exhaust gas pre-treated in the cyclone dust separator goes to a bag filter for further cleaning. Dustiness level after treatment is 1 to 10 mg/m3.
The exhaust gas dust filter is most efficient with higher temperatures and corresponds to the growing need for effective exhaust gas dust separation. It is a steel design with thermal insulation and bottom scraper to facilitate removal of dust accumulated in the filter. Round bag filters installed in the vertical axis are cleaned with a compressed air impulse.
The ZGH-300Eco controller is used with the heating unit and fuel feeding system. The controller adjusts the operating parameters of the entire unit based on the user's configuration. It uses a modulated operation program and a binary operation program: intensive combustion and sustained combustion. The difference between these programs consists in the amount of fuel fed to the furnace.
With the modulated operation program, the controller adjusts fuel feeding time, fan efficiency and grate operation on an ongoing basis. With the binary mode, switching between programs depends on the water temperature inside the boiler. If water temperature reaches a setpoint, the unit will switch from intensive combustion to the sustained combustion mode. It will return to intensive combustion when water temperature decreases by the hysteresis value.
The control automation is based on a PLC controller supported with a 7" control panel installed on the cabinet door. Operating parameters can be viewed and adjusted using the control panel or mobile devices (if the controller is connected to a LAN network). An emergency status is indicated by a message on the control panel.
The controller allows:
measuring boiler water temperature
measuring exhaust gas temperature
measuring feeder temperature
measusring return temperature
measuring brickwork temperature
adjustment of primary air volume using throttle by a mechanical actuator
adjustment of secondary air volume using an inverter, based on the indicated oxygen content in exhaust gas
control of exhaust fan operation using an inverter, based on the indicated negative pressure in the chamber
control of the fuel feeding system.
The controller has a two-stage boiler overheating protection. When the temperature reaches a level defined by the "maximum boiler temperature" parameter, the unit will switch to the overheat mode in which feeder operation is paused (fuel ejection) and blow-in fans stop. Another protective device is the STP temperature limiter, operating separately from the automation system. Upon triggering, the protective device must be manually reset.