1. No category

ORC/Green
Machine
GTE INTERNATIONAL s.r.o.
SNP 29,
990 01 Veľký Krtíš
Slovenská republika
1 Conversion of waste heat into electricity - ORC machine
1.1.1 Waste heat recovery
In technological processes of energy and heat production heat is generated in many
places which will not be utilized, that the so-called waste heat. This generated heat energy
that could be utilized in several ways goes to the environment. This waste heat decreases the
system efficiencies of different heat productions since there it is not utilized. The efficiency of
a traditional fossil fuel power plant is about 40%. Combined heat and power plants (CHP), cogeneration, tri-generation units are further utilize the produced heat (district heating,
domestic hot water production, cooling, HVAC etc.) therefore their efficiency can reach 90%.
One such waste heat utilizing technology called ORC, that operation and structure is
described below.
1.1.2 Working principle of the Green Machine
The system of conversion of heat into electrical current using the Green Machine works
on the principles of a closed Organic Rankine Cycle (ORC). The principle is similar to a
conventional steam engine, where boiling water is converted into steam, which is then
transformed into mechanical energy. The Green Machine uses the unnecessary heat for
heating-up the operating fluid to its boiling point and converts it into gas.
The Green Machine is an equipment which can generate electric energy from waste heat.
This thermodynamic conversion process is carried out via a closed cycle (ORC - Organic
Rankine Cycle) the principle of organic Rankine cycle. That's why it is called ORC machine or
equipment. The conventional thermal power plants and steam-engines work on this principle,
where the hot water vaporizes turn to steam then produce mechanical work, and then
electrical energy. The Green Machine utilizes the waste heat for heating their medium of
working fluid, which is then converted into gas and flow through a twin-screw expander. The
expander drives a generator, which produces electricity. The operating principle of Green
Machine is shown in the following figure.
1. The operating principle of Green Machine
www.gte-international.com
1
ORC/Green
Machine
o
o
o
o
GTE INTERNATIONAL s.r.o.
SNP 29,
990 01 Veľký Krtíš
Slovenská republika
1.1.3 The cycle steps or the operation of ORC machine
Heat is passed through the evaporator into the working fluid, heats the working fluid
to boiling point and converts it into steam.
Steam enters in the screw expander, which converts the steam energy into
mechanical energy.
Steam is further cooled by using a source of cold water in the condenser and
condenses back into a liquid state.
The working fluid is pumped back into the evaporator. Then the cycle is repeated.
This ORC machine can be used at several place, mainly at the technological processes for
the production of heat, recovering waste heat of internal combustion engines and CHP units,
improve their efficiency and utilization.
We can call this ORC machine as a micro thermal power plant, because it uses the organic
Rankine cycle for power generation as well as fossil fuel fired (coal, oil, natural gas and
nuclear fuel) power plants. The difference between these power plants and the Green
Machine is the cycle using working fluid medium. These plants use the energy of water
(boiling - vaporizing - condensation - cooling) to mechanical work and power generation; the
Green Machine uses a special organic material called Penta-fluor-propane. It is a nonflammable, non-toxic, environmentally friendly liquid working fluid which does not damage
the ozone layer and its boiling point is much lower (15.5 ° C) than the water, so it works
effectively in Rankine cycles.
1.1.4 Technical advantages of the Green Machine
Emission-free, environmentally friendly technology
Production of electrical energy without a combustion process
Low operation and maintenance costs
Flue gases are not used, only hot water is used as a medium
Designed for 20 years
Remote control and monitoring
Contains only three main components with moving parts
Automatic Start / Stop system
Modular and scalable design (outdoor version)
Automated system of control and inspection
Easy integration into the hydraulic circuit of warm (hot) water CHP
Simple installation (max. 4 days to launch)
o Cooling by the use of air or water
o
o
o
o
o
o
o
o
o
o
o
o
1.1.5 The structure of Green Machine
The components of Green Machine can be shown in the following two figures. The ORC
unit includes a simple and compact design, only three major components with movable parts
which are as follows: circulating pump, twin-screw expander and power generator.
www.gte-international.com
2
ORC/Green
Machine
2. Components of Green Machine (rear view)
3. Components of Green Machine (front view)
www.gte-international.com
3
GTE INTERNATIONAL s.r.o.
SNP 29,
990 01 Veľký Krtíš
Slovenská republika
ORC/Green
Machine
GTE INTERNATIONAL s.r.o.
SNP 29,
990 01 Veľký Krtíš
Slovenská republika
It is applied adiabatic cooling with water spraying for cooling the condensers to provide
stable system temperature even at high ambient air temperature. Over 22 degress °C of air
temperature, sprayed water cooling being used and the reverse flow temperature is
controlled by a maximum of 27 degrees °C. It can be achieved a stable operation between the
forward and reverse temperatures.
Electricity consumption for cooling depends on the current ambient temperature (the
average annual temperature is 11,1 degrees °C in Hungary and even this temperature the
cooling system consume only 2 kW/h). When the cooling system of Green Machine works, the
cooling system of CHP unit does not works and it consume less electricity which can also
energy efficient. The schematic connection diagram of Green Machine can be seen in the
following figure.
4. Schematic connection diagram of Green Machine
www.gte-international.com
4