The world’s largest CHW plant: Pearl of Qatar

The Pearl of Qatar is a 130,000-ton district chilled water (CHW) plant that serves the cooling needs for all buildings on the island.

By Randy Schrecengost, PE, CEM, Stanley Consultants, Austin, Texas September 16, 2014
The Pearl of Qatar is a 400-hectare manmade island located off the eastern coast of Qatar. The island’s name comes from its shape, which resembles a string of pearls. The air conditioning needs of the island’s existing and future facilities are intended to be handled by the Pearl’s integrated district cooling plant (IDCP).
Stanley Consultants provided design services for the nominal 130,000-ton district CHW plant that serves the cooling needs for all buildings on the island. The IDCP has a guaranteed capacity of 125,000 tons expandable to 130,000 tons using 23 pairs of 2,500 nominal electric motor-driven centrifugal chillers. Each chiller unit is 26 ft long, 11 ft wide, 14 ft tall, and weighs 2,500 tons. The chillers are in a series, counter flow arrangement with each pair providing a zero tolerance capacity of 4,850 tons. 
At 130,000 tons, the IDCP is the world’s largest district cooling plant. It has at least twice the capacity of the next largest chiller plant in the Middle East. By comparison, the largest district cooling plant in Phoenix has an approximately 20,000-ton capacity. 
A district CHW plant of this size has an unquenchable thirst for water, which is scarce and valuable in the Middle East. To compensate, the plant was designed with makeup from three sources: potable water from the local water utility, treated sewage effluent from the nearby sewage treatment plant, and permeate from a 14,000 cubic meter per day desalination plant. The IDCP is one of the first district chiller plants in the region to be equipped with a desalination plant.
The plant was designed with a constant speed primary pumping system that circulates 180,000 gpm of CHW in a closed system that includes the reticulation network and heat exchangers in each CHW user location. Due to the number of chillers in the plant, this system operates as a variable flow system by turning chiller modules (chillers and pumps) on and off based upon load. As a result, variable frequency drives were not needed.

Randy Schrecengost is a project manager/senior mechanical engineer with Stanley Consultants. He has extensive experience in design and project and program management at all levels of engineering, energy consulting, and facilities engineering. He is a member of the Consulting-Specifying Engineer editorial advisory board.

Author Bio: Randy Schrecengost is the Stanley Consultants Austin mechanical department manager and is a principal mechanical engineer. He is a member of the Consulting-Specifying Engineer editorial advisory board.