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Content archived on 2022-12-27

GAS EXPANSION MOTOR WITH SCREW-TYPE AIR COMPRESSOR

Objective

Natural gas is piped into the glass works at an average of 50 bars. Pressure in the network is 3.2 bars absolute. Is was the aim of the project to transform the unused exergetic pressure gradient released during pressure reduction into useful energy.
The plant has run three years under load. During this period the average quantity of compressed air was 5 180 m3 STP/h with a required power of 440 kw. This gives an energy saving of 3.34x10.6 kwh/year as compared with an electric motor drive operating 8 000 hours per year.
The plant availability is above 90%.
The capital payback period is 1,6 years. This type of plants can be recommended in the case of comparable preconditions. This means at continous natural gas supply at constant pressure.
Natural gas is piped into the works at an average pressure of 50 bar. The pressure in the operating network is 3.2 bar. Two pressure reduction units, operating in parallel, were previously used, each with an average throughput of 7500 m3 STP/h.
In order to transfrom the unused exergetic pressure gradient into useful energy a gas expansion motor was installed to drive a screw-type air compressor. This motor fulfills the function of the pressure reduction units which now serve only for reserve.
The gas expansion motor, which has a nominal rating of 610 kW, is a four-cylinder double-acting double-expansion steam-piston machine manufactured by Spillingwerk, Hamburg. The screw-type air compressor is a series-production unit, fitted with a gear of appropriate ratio (air input of 6550 m3/h at 1 bar, 40 deg.C : output after cooler 3 bar at 60 deg.C).
The total system includes a waste heat recovery system which consists of a closed water circuit with a freezing mixture heat exchanger (426kW, 30 deg.C) for the air suction cooling unit (in Summer), the compressed air cooler (426 kW, 82 deg.C) a steam/water heat exchanger (155 kW, 105 deg.C) and the high and medium pressure preheaters by which the gas streams entering the motor are heated up to 100 deg.C and the water cooled down to 25 deg.C.

Call for proposal

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Coordinator

HEYE GLASFABRIK
EU contribution
No data
Address
POSTFACH 1220
3063 OBERNKIRCHEIN
Germany

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Total cost
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