NEW JCM Successfully Performed
World’s Largest CO2 Compressor / Turbine String Test
for Wulan Urea Project (4000 MTPD)

Introduction:

Wulan Coal Group is constructing one of the world’s largest urea plants at Inner Mongolia, China. Considering the extensive experience of NEWJCM in SYNGAS based plant compressors, the Wulan Group chose NEWJCM as the manufacturer for two of their critical compressors: SYNGAS and CO2 trains.

Both these compressors are among the most critical equipment in any Ammonia and Urea plant, and NEWJCM was the only domestic company having the necessary experience with such Mega Fertilizer’s compressors. Another advantage of NEWJCM for the client was NEWJCM’s capability of manufacturing both compressor and steam turbine which enables NEWJCM to perform the critical String Test of the Compressor Train.

String Test (or whole train test), is an optional test based on API 617, but nowadays, to minimize the installation and commissioning risks, customers demand it as a mandatory test. In this test, the whole Compressor Train operates with the contract Steam Turbine. All skid mounted equipment like couplings, gearbox, machine monitoring sensors and instruments are ALL contract equipment (Not shop owned items).

Having one of the most advanced Turbo Machinery Test Centers in Asia and a unique one in China, NEWJCM is able to conduct API 617 and API 612 run tests, ASME PTC-10-II Performance Test as well as API 613 and API 614 running tests for Gearbox and Lubrication Units.

CO2 Compressor Design Features:
NEWJCM design of CO2 compressor consists of a horizontally split LP casing with back to back design rotor (8H-6B) and a vertically split HP casing of back to back arrangement (3V-7B). 

CO2 Compressor process design data are as below:

The Steam Turbine Driver was an Extraction/Condensing type using HP steam (39 BarG) at inlet. Rated power of the turbine is 17,605 KW. The arrangement for this compressor is LP Casing, Steam Turbine, Gear Box, and HP Casing. 

NEWJCM CO2 compressor has some special design features which are not used by, nor exist in the design of, most other OEM. Using 3D impellers, improved internal sealing (especially in the HP casing) and a design without tie-rods in the HP casing are among the mentioned specific features. For the sealing, NEWJCM uses combined Labyrinth and Swirl Breaker as well as Honeycomb sealing between the 3rd and 4th stages. Considering the high density of the CO2 in the last stages (approximately 1/3 that of water) and high gas exciting force, special consideration is required to stabilize the rotor vibration and using this kind of advanced seals improves the rotor stability as well as the sealing efficiency.

As to the HP casing design, NEWJCM uses a design without any tie-rod or heavy bolts for the casing. This special feature appreciably facilitates and eases the disassembly / reassembly of the compressor for maintenance purposes. 

Other OEM HP Casing Design with large size bolting(Left), NEWJCM HP casing design (No large size bolt)

Wulan CO2 String Test

The Wulan Project in China is Saipem’s largest single line urea complex with a design capacity of 4,000 mtpd.

The Compressor Train String Test was conducted on 24th June 2016 at NEWJCM Turbomachinery Test Center (TTC). The String Test was carried out to study the mechanical integrity of the train as well as the dynamics behavior of the whole train. The Compressors, Steam Turbine and the Gearbox as well as all other skid mounted piping and instruments were tested together like the arrangements in the plant. 

Wualn CO2 Train mounted on Test Bed No.3: from left to right LP Casing – Steam Turbine – Gear Box – HP casing

During the run at trip speed, the vibration and temperature levels were better than API requirements (Maximum vibration detected was 20 Micrometer, and mostly below 15Micrometer)

After running at trip speed, the machine had to be run at Maximum Continuous Speed for another four hours. During this four-hour test, the supply oil temperature had to be varied to study the effect of oil temperatures on bearings behaviour. Again, this four-hour test passed successfully while the machine vibrations for most of the probes were below 10 Micrometer which was much better than API requirement. Generally, the machines worked smoothly in all operating speeds as well as of design condition like critical speeds and overspeed condition.

This test was witnessed by Wulan’s Engineering Company (Beijing Huafu Engineering Co. Ltd), Owner’s Third Party inspector as well as NEWJCM’s honorable guest from STAMICARBON B.V.

The Test Results were found to be absolutely satisfactory as per API and Test Procedure and it were released by inepctors for the next manufacturing step which is on-skid piping arrangement and Painting.