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Contenu archivé le 2022-12-27

INCREASE IN ELECTRICAL ENERGY PRODUCTION BY CONDENSATION OF FUMES, WITH ELIMINATION OF POLLUTANTS

Objectif

The project consists in :
a) the recovery of energy from an incineration plant of Urban Wastes. This recovery is achieved by cooling the fumes and by condensating one part of the pollutant contained in the fumes. The heat recovered is used to increase the plant electrical energy production or to supress the plume usually seen at the stack outlet.
b) the removal of the main pollutant contained in the fumes and its neutralization before disposal.
The advantages of this process are :
- a 6% increase of the electrical power available at the turbo-alternator,
- a better integration of the plant in its environment with minimizing the energy expenditure.
The energy recovery process induces in return an additionnal cost, counterbalanced by a rapid pay off.
1. LINE NR. 3
As per design, the condensates should be reheated from 60 deg. C to 120 deg. C. In operating conditions, the condensates are reheated from 48 deg. C to 98 deg. C. The maximum recovery potential is therefore not reached because the fumes flow is slightly inferior to the design flow and the boiler is slightly more effective than expected (outlet temperature : 200 deg. C instead of 210 deg. C : recovery power is therefore 143 kW instead of 164 kW). The very stable operation has been obtained on the 8th, 9th and 10th of February in 1996. In the future, the boiler will be coated by soot and therefore will become less effective so that the fumes temperature at the outlet of the electrostatic precipitator will become close to 210 deg. C, then it will be possible to reach the 164 kW as expected at the design stage.
2. LINES nR. 2 and NR. 1
* The fumes re-heaters are in fact the first condensates-chlorine remover modules. They transfer the calories present in the incoming fumes (before the condenser-chlorine remover) to these same fumes, dried of their water vapour content, downwards the condenser-chlorine remover.
* In operating conditions, these exchangers gas-gas allow to recover 2564 therms per hour, compare to the 2500 therms/hour as per design stage.
The recording period for fumes temperature is from 01/11/1996 to 22/11/1996.
The average temperatures inlet and outlet are 272 deg. C and 166 deg. C for the upstream fumes.
The average temperature inlet and outlet of the downstream fumes are : 38 deg. C and 197 deg. C.
3. PROJECT SUCCESS
3.1 The positive or negative results of energy recovery are the following :
- Today, the additionnal exchangers (gas-gas or gas-water) did not bring any supplementary maintenance work. No maintenance, no cleaning, stable exchange capacity with the time.
- If the exchanger gas-water of line nr. 3 does not give the expected 130 deg. C, the exchangers gas-gas on lines nr. 1 and nr. 2 are more effective than expected and allow the complete removal of the stack plume.
3.2 In general way, the energy recuperators allow positive results both on technical and economical ground :
- Economically, there is an earning of 143 kW, which means 6% more power on the turbo-alternator of line nr. 3.
- For the lines nr. 2 and nr. 1, there is a saving of 1867 TOE per year.
The incineration plant of Urban Wastes at Chambery consists in three different incineration lines, described as follows :
a) The new line nr. 3 is of 6 tons/hour capacity; this line is made of the main following equipments : furnace, IBISOC tower, boiler, electrostatic precipitator, condenser reheater, chlorine-condenser, exhaust fan and stack.
The vapour produced in the boiler is converted into electrical energy by a turbo-alternator with under vacuum condensation; at the discharge, the 150 mbar vapour is condensed in an aerocondenser; the 54 deg. C condensates are recycled through the boiler feeding tank; on this loop is installed the condenser reheater above mentionned.
b) The two retrofitted incineration lines, nr. 1 and 2 are of 5 tons/hour capacity; these lines are made of the following equipments : furnace, IBISOC tower, cooling tower, electrostatic precipitator, fume reheater, chlorine condenser, exhaust fan and stack.
The heat recuperators on each line are installed downwards the electrostatic precipitator. They are built into the chlorine-condenser, they are its first module. On this module, the fumes transfer one part of its sensible heat without any condensation, this latter is taking place in the condenser inferior modules.
CONDENSATES REHEATER ON LINE Nr. 3
The equipment is a tubular heat exchanger gas liquid with cross-flow arrangement. The pipes are laid horizontally, the hot fumes circulate vertically in the housing from top to bottom around the pipes, and the condensates circulate inside the pipes, they are re-heated. In a classic system with boiler, the vapour is also condensed at the turbo-alternator outlet, and the condensates are directly recycled through the boiler feeding tank. In our system with reheating of condensates, these last are heated from 54 deg. C to 120 deg. C, within an HASTELLOY heat exchanger, before to be recycled through the feeding tank. They end up to a temperature close to the one prevailing in the tank which isin normal operation :
- pressure : 2,13 bar effective,
- temperature : 135 deg. C
Thus, the calorie gain is about 66 deg. C. The preheater allows to increase the vapour production of the boiler, therefore the electrical production is also increased from 2391 kW up to 2534 kW, equal to a bonus of 6%
FUMES REHEATERS ON LINES NR. 1 and NR. 2
Hot fumes coming out from the grid furnaces are cooled from 875 deg. C to 310 deg. C by water injection in the cooling towers and they pass through the electrostatic precipitator. Then, in the heat exchangers-condensers the gaseous pollutants are trapped, the temperature being lowered from 300 deg. C to 59 deg. C. Saturated, these fumes contain 19% of water vapour, which generates important plumes at the stack.
As the plant is established in an urban context, it is therefore very important to improve its environmental aspect. In order to suppress these plumes, the fumes are heated to 175 deg. C by the means of an heat exchanger gas/gas.

Appel à propositions

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Régime de financement

DEM - Demonstration contracts

Coordinateur

SOGEA
Contribution de l’UE
Aucune donnée
Adresse
3 COURS FERDINAND DE LESSEPS
92851 RUEIL-MALMAISON
France

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Coût total
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