Water Power Cogeneration System

Water Power Cogeneration System

Part 02: Application Combination of desalination plant with gas turbine, heat recovery boiler and steam turbine

Explain the system of cogeneration

With the term Cogeneration is the simultaneous production of electricity (and / or mechanical) and thermal energy through a single builds process. The energy optimization in a single build process allows significant advantages compared to the generation of the same amount of energy produced by separate processes (Spiewak 2007).

This advantage is evident from the simple comparison reported in the following two figures, in which, compared with equal amounts of energy to be made available at the thermal and electrical loads, the CHP system uses a lower amount of fuel (in many cases quite marked) with respect to the total quantity required for the separate generation. The latter considers the park for electricity generation for the national and local generation of heat a system of conventional type (conventional boiler).



Figure 1. Energy efficiency of the conventional system.



Figure 2. Energy efficiency of the CHP system.

Working

In the cogeneration the heat produced by the machines for electric generation is recovered, in the form of hot water or steam or other (eg, thermal oil, through suitable exchange systems), and is used as process heat (for industrial processes such as drying and heating) for both the environmental conditioning and the production of ACS (Pearce 2009). 

Further waste heat or heat production redundancies can be used in absorption refrigeration machines for the production of cold or air handler. The cold production can be achieved with compression refrigeration systems powered by electricity produced by the CHP system. If there is simultaneous production of cold is also talk of trigeneration.

The compression refrigeration systems, if reversible (heat pump operation), may provide additional quantities of thermal energy.

The use of cogeneration systems installed at the end users allows the following advantages:

high overall efficiency ? g

low maintenance costs (variabli depending on the technology used cogeneration)

low levels of total emissions (CO 2, NO X, etc..) (Orlando 2001)

High system availability due to the maturation of CHP technologies

independence (partial or total) from the mains, with consequent reduction of production losses due to interruptions in electricity supply

Overall efficiency ? g of the CHP system 

? g = ? + and ? t = (E + E t) / E c

where and electrical efficiency ? = E = / E c = thermal efficiency ? t = E t / E c E = electrical energy produced E t = thermal energy produced E c = energy contained in the fuel consumed

Essential conditions for a convenient application of cogeneration are the following:

simultaneous application of thermal energy (and / or cooling) and electrical and / or the possibility of accumulation of heat / cold exchange / sale of electricity to the grid; (Nosrat 2011)

suitable ratio load electric / thermal load of the utilities to be matched to the index electric (ratio between the electric power and the thermal power generated by the machine);

commercial availability of machines of power corresponding to the calculated power that optimizes the energy savings.

ces

CHP traditional technologies, developed in the industrial field are:

Reciprocating internal combustion engines (ICE)

gas turbines (GT)

steam turbines (TV)

combined cycle: gas turbine + steam turbine (CCC)

fuel cells (FC)

The table and figure below show the various fields of application of cogeneration technology: you can see that in the civil service ...