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Contenido archivado el 2022-12-27

DESALINATION PLANT USING RECYCLED HEAT IN SAINT-MARTIN, DOM-GUADELOUPE

Objetivo

The aim of the project is to recuperate the heat from the exhaust gases of two 3 MW diesel generators in an existing power station in order to operate a high efficiency seawater desalination unit producing 450 m3/day. The desalination unit uses the ejectocompression low temperature distillation process. Its eight cells and especially designed thermocompressor give a particularly low energy consumption; 55.6 kcal/kg of produced water. In order for it to permanently operate at its normal capacity, the unit will be supplied by one of two recuperation boiler plants, depending on which of the diesel motors is in operation.
The equipment was considered as being operational on 10th January 1987 and the recuperation boilers on 16th February 1987. The evaluation period was from then until end February 1989.
During two years of operation, the desalination unit operated in a highly satisfactory manner with only one noteworthly breakdown which occured when one of the vanes of the vacuum pump was damaged by water entering the unit. The intake circuit was modified to avoid a recurrence of this problem.
Some difficulties were encountered with the recuperation boilers. In particular problems were encountered adjusting the water circuits and in the soot removal washing system. Modifications were carried out to overcome these problems.
Another breakdown was then the shutter control shaft that directs the exhaust gasses towards the tube bundle broke in two places due to metal fatigue caused by vibrations in the exhaust system.
Two diesel motors, each producing 3 MW, are installed in the Saint-Martin EDF electric power station in Guadeloupe (French Overseas Terretories). These motors were installed with the aim of possible future heat recuperation. This is limited to the exhaust gases and excludes the sleeve cooling water in order to avoid operational complications.
In order to ensure an adequate continuous supply of heat, both diesel will be equipped with recuperation boilers connected to a single steam tank to produce 1.6 t/h of saturated vapour at 10 bar. This arrangement permits great operational flexibility since the nominal consumption of the desalination unit can be supplied from one motor and so is unaffected by variable electrical supply requirements and maintenance shutdowns.
The innovative aspect of the project is the specially designed desalination unit itself. The unit will consist of :
- very low divergence heat exchangers and a very high thermal exchange coefficient for sprayed bundle andhorizontal tube evaporators.
- A particularly high performance ejectocompressor, despite the wide temperature divergence between the first and last evaporator cell.
- A multiple-effect evaporator.
The operation of the unit is as follows. The ejectocompressor allows 2,575 t/h of 63 deg. C saturated vapour to be discharged into the first cell tubular bundle. The steam then condenses inside the tubes whilst an equal quantity of seawater sprayed onto the outside of the tubes evaporates. Because the evaporation takes place at a low temperature, problems of scale and corrosion are avoided. The evaporated water from the first cell enters the tubes of the second cell for condensation, permitting the evaporation of seawater on the outside of the tubes. This process is continued up to the 8th cell. The net production from all the cells is 450 t/day after deduction of 1.575 t/h which is returned to the boiler.

Convocatoria de propuestas

Data not available

Régimen de financiación

DEM - Demonstration contracts

Coordinador

SIDEM
Aportación de la UE
Sin datos
Dirección
RUE DE CLICHY 54
75009 Paris
Francia

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Coste total
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