20 Power Plant Open Cooling System in the Context of the Objectives …
407
20.3.5 Assessment of the Economic, Energy
and Environmental Aspects of Current
and Alternative Solutions
Taking into account environmental issues and WFD requirements, the feasibility of
alternative solutions which could be used in order to reduce the temperature of the
spent cooling water discharged has been considered. When considering changes to
the cooling system, the impact of these changes on the overall efficiency of the power
plant must be taken into account. If possible, efficiency should increase. In the case
of temperature-sensitive processes, it must be checked whether the technology used
can deliver lower final temperatures while maintaining the same level of safety.
Financial outlays are always among the most important factors influencing the
choice of a cooling system, and they can only be estimated for an individual design.
The most important types of costs include:
• Investment costs;
• Maintenance costs;
• Operating costs related to the demand for energy (and water);
• Environmental costs such as taxes, fees and waste management costs.
The power plant in question has an open cooling system. In terms of economic,
energy and environmental considerations, the existing system has been described as
Option 0 (status quo). Two alternative options were analysed as well whose implementation would enable: Option 1 – lowering the temperature and discharging spent
cooling water back into the power plant canal; Option 2 – no further discharge of
water into the river by replacing the open cooling system with a closed system that
uses cooling towers. The options listed above meet BAT requirements.
20.3.5.1 Option 0 – Status Quo
Figure 20.1 shows the technological diagram of the power plant circuit including
the indication of characteristic points. The specific enthalpy of steam at point 1
is 3470 kJ/kg. The condensation of water vapour behind the turbine takes place
(according to data obtained from monitoring the operation of turbine sets) within
the pressure range of approximately 2.5 to 4 kPa, which more or less corresponds to
vapour condensation temperatures in condensers ranging from 65 to 80 °C.
Figure 20.2 shows points at which, on the basis of actual data, the efficiency of
conversion of chemical energy of fuel into electricity was determined for the power
plant in question.
Using actual data, on the basis of the graph presented in Fig. 20.2 and with
the use of linear interpolation, the equation which makes it possible to determine the
efficiency of conversion of chemical energy of fuel into electricity for the power plant
as a function of coolant temperature after turbine set condensers (t”) was determined.
This relationship is presented below:
407
20.3.5 Assessment of the Economic, Energy
and Environmental Aspects of Current
and Alternative Solutions
Taking into account environmental issues and WFD requirements, the feasibility of
alternative solutions which could be used in order to reduce the temperature of the
spent cooling water discharged has been considered. When considering changes to
the cooling system, the impact of these changes on the overall efficiency of the power
plant must be taken into account. If possible, efficiency should increase. In the case
of temperature-sensitive processes, it must be checked whether the technology used
can deliver lower final temperatures while maintaining the same level of safety.
Financial outlays are always among the most important factors influencing the
choice of a cooling system, and they can only be estimated for an individual design.
The most important types of costs include:
• Investment costs;
• Maintenance costs;
• Operating costs related to the demand for energy (and water);
• Environmental costs such as taxes, fees and waste management costs.
The power plant in question has an open cooling system. In terms of economic,
energy and environmental considerations, the existing system has been described as
Option 0 (status quo). Two alternative options were analysed as well whose implementation would enable: Option 1 – lowering the temperature and discharging spent
cooling water back into the power plant canal; Option 2 – no further discharge of
water into the river by replacing the open cooling system with a closed system that
uses cooling towers. The options listed above meet BAT requirements.
20.3.5.1 Option 0 – Status Quo
Figure 20.1 shows the technological diagram of the power plant circuit including
the indication of characteristic points. The specific enthalpy of steam at point 1
is 3470 kJ/kg. The condensation of water vapour behind the turbine takes place
(according to data obtained from monitoring the operation of turbine sets) within
the pressure range of approximately 2.5 to 4 kPa, which more or less corresponds to
vapour condensation temperatures in condensers ranging from 65 to 80 °C.
Figure 20.2 shows points at which, on the basis of actual data, the efficiency of
conversion of chemical energy of fuel into electricity was determined for the power
plant in question.
Using actual data, on the basis of the graph presented in Fig. 20.2 and with
the use of linear interpolation, the equation which makes it possible to determine the
efficiency of conversion of chemical energy of fuel into electricity for the power plant
as a function of coolant temperature after turbine set condensers (t”) was determined.
This relationship is presented below: