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Content archived on 2022-12-27

HEAT RECOVERY IN THE PRODUCTION OF PHOSPHORIC ACID

Objective

The combustion of yellow phosphorus generates 24,350 kJ of heat per kg of the substance.
The large-scale production of phosphoric acid involves the combustion of yellow phosphorus. The considerable amounts of heat generated in this process have been evacuated by means of cooling water. The project suggests to utilize this heat, in the future, for the generation of steam and to have it converted into electric power. This process-heat recovery enables considerable savings of primary energy (coal, oil, gas).
The project cannot be carried on, for the following reasons :
- The capital expense (investment), in view of the actual cost level, will be approx. 30-40 % higher than estimated at the time of submission.
- The capital payback period, due to the price decline for primary energy, will be excessively long (7 years); longer than there is an assured supply of phosphorus.
- Since 1985, in view of a modified strategy, our company has increased its efforts to manufacture speciality products rather than to produce mass phosphates (commodities); this will lead to a reduced demand of phosphorus in the future.
- A drastic collapse, since early 1986, in the sale of phosphate salts used in washing powers, detergents, and cleaning agents, will further reduce the amounts of phosphorus needed in the manufacture of our product line.
- A major aspect of the project was the purchase of energy by Joh. A. Benckiser, with whom we have a joint network. Joh. A. Benckiser are no longer prepared to purchase any such energy.
The heat generated by the large-scale combustion of phosphorus is absorbed, in an acid tower, by recirculating acid. The recirculating acid then releases the heat previously absorbed into a heat exchanger (cooling water). The amounts of heat thus transferred are subsequently released, mainly in the form of steam, from the cooling tower into the atmosphere.
Now, the new method suggests an upstream combustion chamber before the acid tower, thus utilizing a major part of the heat generated in the combustion of yellow phosphorus for the production of energy.
The new method represents an energy-recovery process on a very high temperature level, with the possibility to produce high-pressure to medium-pressure steam with subsequent power/heat coupling.
The estimated energy generation, at 8000 hours, would be as follows :
Steam 15 t/h = 120,000 t/a
with steam-pressure reduction
from 80 bars/550 deg. C to 40 bars/450 deg. C.
Electric power : 550 kWh = 4,400 mWh/a.

Call for proposal

Data not available

Coordinator

BK LADENBURG GMBH
EU contribution
No data
Address
DR. ALBERT REINMANN STRASSE 22
6802 Ladenburg - Neckar
Germany

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Total cost
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