The boilers are elements in which heat is transferred from the combustion of a fuel fluid another heat transfer fluid responsible for the transfer of thermal energy to the facility. According
fuel type can be:
- solid fuel boilers, coal, wood ...
- liquid fuel boilers, oil boilers
- gaseous fuels: natural gas, butane, propane ...
- Multifuel boilers. The
case must be examined in each type of boiler used according to the application and needs.
One of the fundamental parameters in selecting the type of boiler used is the yield useful , which is defined as the ratio of useful power transmitted to the heat transfer fluid and thermal burn resulting available fuel at rated operating conditions:
useful
Performance (%) = 100 * Pu / Pc
The useful power is given by the amount of heat in kW transmitted to the heat transfer fluid is given by the following expression:
Pu = Q * (T -T s and ) * C and * P and
Where:
Q is the heat transfer fluid flow rate in l / h.
Ts: is the heat transfer fluid temperature at the exit of the boiler.
Te is the temperature of heat transfer fluid at the entrance to the boiler.
Ce: the specific heat transfer fluid.
Pe, is the specific weight of the circulating fluid. The
rated output is given by the type of fuel used by the boiler and the use of the same, according to the following expression: Pc =
PCI * C
Where:
PCI: is the lower heating value of fuel used.
C: is the amount of fuel consumed by the boiler.
In this performance standard boilers nominal service is reduced when operating at partial loads than the nominal power of it. This drop in performance should to be reduced despite the thermal power transmitted to the heat transfer fluid losses through the envelope remains constant, because tempeature must be maintained inside the boiler even though there is no demand.
The low temperature boilers able to improve part-load performance of diesel boilers. This improvement is achieved because the technology allows for adjustment of water temperature of production on demand, without having to maintain a minimum temperature inside. This will reduce the number of starting and stopping of the burner and substantially decreases diesel consumption.
The condensing boilers are those with better performance. The main difference with other types of boilers lies in harnessing the energy contained in the products of combustion gases, in particular energy uses steam condensation. The temperature of the combustion gases in standard boilers is about 150 º C, condensing boilers reduce the temperature to 65 º C by the use of latent heat in the flue gas.
The performance of the boiler combustion can exceed 100% because, as noted above, the performance tool is referred to PCI (calorific value). The PCI is defined as the total energy contained in the products of combustion of a fuel.
The following chart compares the distribution of energy losses in a low temperature boiler and a condensing boiler in relation to PCI.
When making an optimal choice from the point of view of energy efficiency be useful to consider both performance as a correct sizing of the nominal operating power in order to optimize performance and improve part-load performance season average. In
centralized facilities is also vital to make a proper control system programming of the facility.
The IDEA (Institute for Energy Diversification and Saving of Energy) provides a tool for accessing a database with various types of boilers on the market: http://www.idae.es/Calderas/Consulta . aspx
0 comments:
Post a Comment