GEA demonstrated its ability to apply its process refrigeration expertise to meet the requirements of Linde Engineering North America - as part of a United States-based project - from the production stage to refrigeration and boil-off.

The customer

Linde Engineering North America Inc. (LENA) is a member of The Linde Group, a world-leading gases and engineering company. LENA delivers technology, engineering, procurement, and construction for synthesis gas, air separation, and petrochemical plants as well as its Selas Fluid Processing refinery and petrochemical fired equipment.

Refrigeration systems - a key industry requirement

Refineries, petrochemical plants and integrated chemical complexes rely on large-scale refrigeration systems for the smooth and safe running of their day-to-day operations. These system often utilize ammonia (NH3) - a natural, thermodynamically efficient and cost-effective refrigerant. 

The customer challenge

Linde requested the design and execution of a full-scale refrigeration unit with the functionality to provide cooling duty at three temperature levels (-37°/-5/+5 °C) for different process applications in an ammonia production plant.

Considerations

Industrial processes require the storage of ammonia in large, low-pressure tanks at low temperatures. In locations which experience high temperature seasons in particular, the transfer of ambient heat to the storage tank is an important consideration for plant operators. One sign of heat transfer is the formation of vapor, known as boil-off gas (BOG). Tank insulation plays a vital role in limiting boil-off levels to a standardized benchmark.

The solution

Linde inside view

GEA’s technologically advanced solution includes the design of a boil-off unit, specially designated for the boil-off stream from the ammonia tank and the flash gases, which are generated when the re-liquefied ammonia of the boil-off unit is returned to the ammonia tank. The solution has been proven in extremely low and high ambient temperatures and to the specifications of technically demanding projects. The processing capacity of the refrigeration unit of the ammonia plant unit is 40 t/h, while the associated boil-off unit provides cooling duty to condense boil-off flow from the ammonia tank during shut-down periods. The role of the boil off unit is to safely deal with the boil-off stream from the ammonia tank, as well as the flash gas generated when the re-liquefied ammonia from the boil-off unit is returned to the ammonia tank.

The refrigeration unit of the ammonia plant consists of three oil-flooded screw compressors at three different pressure levels in order to process different process vapor streams and the relevant heat exchangers and drums separators to complete the process of refrigeration. The ammonia BOG package which was delivered to the customer consisted of an ammonia screw compressor to compress the ammonia gas and send it to the condenser. Through the work of the compressor the refrigeration effect is achieved and the heat load is transferred from the low temperature level to the high temperature level.

This GEA solution is an example of how our expertise in ammonia-based refrigeration processes delivers highly efficient customized systems to customers worldwide. GEA’s commitment to flexibility means its engineers are able, if necessary, to devise solutions with third-party compressor technologies. 

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