Frequently Asked Questions (FAQ)
Does the turbine come with the generator? What else do I need?
What turbine types are currently available for purchase?
Currently for sale are the 1.5 kW and the 15 kW turbines.
Can you offer types with a different output?
We currently do not have any other output types available than the 1.5 kW and the 15 kW.
It is possible to use more than one 1.5 kW in a parallel setup to increase the output. The 15 kW can modulate depending on the available steam. Each of the six
nozzles is 2.5 kW. This will allow for an ouput of 2.5 kW to 15 kW.
What is the price for the 1.5 kW or the 15 kW?
The GREEN TURBINE 1.5kW: 5.550 EURO
The GREEN TURBINE 1.5 kW plus full set of components: 9.200 EURO
The GREEN TURBINE 15kW: 16.950 EURO
The GREEN TURBINE 15kW skid (without inverter): 37.000 EURO
The GREEN TURBINE 15kW skid (with inverter): 41.250 EURO
All prices are indicative and may vary.
Prices are EXW Sprang Capelle, the Netherlands.
How important is the dryness of steam?
Our turbines run on some 20 to 40 C superheated and thus dry steam. If in doubt, use a steam separator. It is very important that dry and slight superheated steam is used, because
wet steam damages the turbine quickly and has a negative influence on the turbine's efficiency.
What will happen if I use wet steam?
The turbine wheels will deteriorate very fast; this can happen in a matter of minutes.
How do I create and measure the dryness of the steam?
We can supply an installation manual for the different types. The last chapter of the installation manual explains how to create dry steam.
Can the turbine run on compressed air?
We have not tested our turbines with pressurized air. The turbine can,
theorectically, run on compressed air but the air must be heated. In expanding the air in the turbine, it cools down and could even freeze,
which will block the nozzle. In heating the air, you can get more energy out, but the power will be low. Also the nozzles and the generators must be redesigned, because
energy density is lower than steam.
Can I use ORC fluids, like ammonia?
We have not tested our turbines with ORC fluids. For our small type, the 1.5 kW, this does not seem a good option. The density at condenser temperature
of the fluids is high, so high ventilation losses will occur. Above 10 kW, ORC could be a valid option in theory, but this would require re-engineering of the turbine, depending on the fluid used.
Can I use the turbine with an existing wood (pellet) stove?
No, an exisiting pellet stove does not supply steam. You will need to develop a complete new system with a steam source.
What is the required steam temperature and pressure for the 1.5 kW turbine?
The ideal steam temperature for the 1.5 kW is 170°C - 190°C. The steam pressure is 5.2 bar abs. It is possible to use lower pressures, but then efficiency and output will be lower. - The maximum pressure for the 1.5 kW is set for 10 bar abs, but this will require the use of customized nozzles.
See the full specs for the 1.5 kW here.
What is the required steam temperature and pressure for the 15 kW turbine?
The ideal steam temperature for the 15 kW is 200°C - 220°C. The steam pressure is 10 bar abs. You can modulate the pressure between 1 bar abs and 10 bar abs. The maximum pressure for the 15 kW is set for 12 bar abs. See the full specs for the 15 kW here.
What size steam boiler do I need for the 1.5 kW?
For the 1.5 kW you will need a steam boiler of minimum 13 kW / 18 kg/h. Make sure the steam boiler produces dry, superheated steam and can work with the pressure of the 1.5 kW. When in doubt, show the boiler manufacturer the technical specs of the turbine.
Can I use higher steam temperatures?
Yes, you can but to a limit: for the 15kW you can go as high as 250°C (480°F), for the 1.5 kW 230°C (446°F). The maximum steam temperatures must not be exceeded as overheating of turbine components can occur.
What size steam boiler do I need for the 15 kW?
For the 15 kW you will need a steam boiler of minimum 150 kW / 160 kW / 180 kg/h. Make sure the steam boiler produces dry, superheated steam and can work with the pressure of the 15 kW. When in doubt, show the boiler manufacturer the technical specs of the turbine.
Can you recommend suitable steam boilers?
We are currently looking into suitable steam boilers. You can also send out the technical specs of the turbine to a local boiler manufacturer.
Every turbine has 2 integrated generators, they must be wired as shown in the manual. For proper operation you need a steam generator (boiler or other steam source), feed water pump, a condenser, a vacuum pump, cool water supply, an over speed controller, 2 bridge rectifiers, an inverter and piping and valves.
We can supply these components with the turbine. The components have been thoroughly tested by us. The 15 kW turbine can be offered built on a complete skid (excluding steam generator). The skid will be offered fully assembled with turbine, PLC, vacuum pump,
vacuum vessel, inverter, condenser, feed pump, rectifiers, speed control, piping, fittings, flanges, steam valve and coil and amp and voltmeter.
How much cooling water do I need?
Both turbine types have an electrical and a thermal efficiency. Together they make up for the total efficiency. If the heat released from the condenser is not used, you will need to cool it. For the 1.5 kW this is approx. 12 kW. For the 15 kW it comes to around 130 kW. The amount of cooling water depends on the temperature of the cooling water and the ambient temperature.
The temperature of the cooling water must not exceed 35 °C. In the tropics there is a maximum of 30 °C.
Can I buy a turbine without the generators?
No, the generators are an integral part of the machine.
Do I need a condenser?
Yes, the Green Turbine must operate with a condenser pressure of 0.1 bar abs. The pressure must not be higher than 0.2 bar abs. With 0.1 bar the condenser temperature is 45 C. Higher pressures will result in higher condenser temperatures and also higher turbine temperatures. This will shorten the life of the bearings and has a negative influence on efficiency due to less expansion and higher friction losses.
Why do I need an inverter?
Unless you only need DC, you need an inverter to get useful power. For the 1.5 kW a single phase (230 or 120 V, 50 or 60 Hz). For the 15 kW turbine a 3 phase (400V, 50 Hz or 60 Hz). The inverter also needs to have a programmable curve. Solar/PV are (usually) not suitable.
What happens if I exceed the maximum RPM?
The turbine wheels will get damaged due to high centrifugal stress, seizing up the turbine..
What are the dimensions of the skid you offer with the 15 kW turbine?
An estimate of the skid dimensions is: 1x1x2.5 (L-W-H) meter.
Are your turbine models certified?
We comply with the CE certification. The turbine itself is not a pressure vessel, so the certification requirements for steam boilers do not apply.
What about maintenance and life span?
If the operational instructions are followed, we only have one wear part; the bearings. The bearings have an estimated life span of 100 000 hrs. With full time running this can mount up to more than 10 years.
The bearings are lubricated for life. The turbine wheels have a life span that depends upon the quality of the steam. If the right steam quality is not used, erosion of nozzles and blades can occur. Until now we have not has any experience with worn out blades.
New wheels can be installed rather easily, this takes a few hrs work. The other parts of the skid will need some more care. Periodically, the quality of the feed water must be checked and if needed, the water must be treated (demineralized).
Pumps and valves must be checked for leakage and wear. Filters must be cleaned approx. every 2000 hrs.
When water is used of an inferior quality, expect more wear on pumps and valves and expect to treat the condenser at least once a year.
The oil in the vacuum pump must be renewed at regular intervals, all according to the maintenance instructions of the manufacturer.