Over 7% efficiency increase after abradable sealing modification on GHH axial/radial air compressor

Maintenance Partners - Abradable Sealing Upgrade - GHH Axial Air Compressor - 3D Scanning of Rotor for re-engineering 920Maintenance Partners has recently applied an abradable sealing modification to a GHH axial/radial air compressor in combination with one expander wheel. The compressor is used in a nitric acid train of a Turkish fertilizer plant. This upgrade has resulted in an efficiency increase of 7,36%. Our customer faced a growing demand for fertilizer products and contacted us to increase the efficiency of a GHH axial/radial air compressor.

The GHH axial/radial compressor runs at 5250 RPM and was manufactured in 1967. The compressor has been running for almost 50 years and is one of the plant’s most critical machines for the production of various nitrogen- and urea based fertilizer products.


Abradable Sealing Modification

A turbo compressor’s overall efficiency is greatly influenced by the internal recirculation of the compressor gas, or Internal Recycle Flow. To solve this, Maintenance Partners offers a modified sealing system on the radial impeller balance piston location to significantly reduce internal recirculation.

Maintenance Partners - Abradable Sealing Upgrade - GHH Axial Air Compressor A 920The reduction in recycle flow is the result of minimizing the clearances between the labyrinth and the rotor. This is achieved by removing the existing stator labyrinths, installing new labyrinth seal strips on rotor parts and installing abradable seal rings in the casing on impeller eye and balance piston location.

All parts required for the modification were re-engineered and manufactured by Maintenance Partners.

The new sealing system was installed onsite during a planned three-week shutdown of the fertilizer plant. During the installation, the team found severe alignment problems which lead to high vibrations. The rotor was re-aligned which solved vibration problems.

As the compressor was partly disassembled during the shutdown, the occasion was utilized to scan the blade carrier in 3d for re-engineering and manufacturing later.

Other improvements:

Coating of rotor

Besides the application of the abradable sealing system, the rotor was also coated (radial impeller & axial blades) to be protected against corrosion and to reduce fouling. The coating used is an aluminium filled chromate / phosphate bond coating that can withstand temperatures up to 260 °C.

This specific coating has a very smooth surface that contributes to performance improvement and fouling rate reduction.Maintenance Partners - Abradable Sealing Upgrade - GHH Axial Air Compressor rotor high speed balancing 920

250kW Booster fan becomes optional

To increase flow, the compressor’s inlet was fitted with 250kW booster fan in the past. Thanks to the abradable sealing modification, the booster fan is no longer required and can be shut off, allowing our customer to reduce electricity consumption. The plant is operating 24/7 all year round this means that an energy reduction of 2 190 000 kWh per year can be achieved (250kW * 24 hours * 365 days) when the booster fan is not in use.


Result for customer: Significant Production Increase

Measurements conducted and provided by our customer show an efficiency increase of 7,36% after the abradable sealing modification. This increase results in an increase of discharge flow from 89 134m³/hour to 95 700m³/hour. The discharge flow measurements were taken at the same inlet temperature and running speeds:

DISCHARGE FLOW m3/h 89.134 95.700 7,36%

As shown in the table above, the modification has allowed our customer to increase production significantly without altering the operating parameters of the compressor or its driver. In addition, our customer was even able to reduce energy consumption as the booster fan is not required anymore.

Needless to say, our customer is very happy with the results, as the maintenance manager’s quote shows:

“We are grateful for your improvements to our compressor which is of great interest to us”

Moreover, there is room left for further improvement to the compressor, as the current discharge flow increase was achieved without altering the blade carriers.


Contact us

Are you interested in compressor upgrades to increase output or reduce energy consumption? Call us at +32 (0) 3 541 71 40 or send us a message:

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