Condenser in Ammonia plant

WATER-COOLED CONDENSERS• More efficient than air-cooled condensers• Water temperature can be maintained• Water temperature directly affects system pressures• Three types of water-cooled condensers– Tube within a tube condenser– Shell and coil condenser– Shell and tube condenser

Shell and tube Condenser

• Methanator discharge gas is piped into the shell

• Water flows through the tubes in the condenser

• The ends of the shell are removed for cleaning• The shell acts as a receiver• Most expensive type of condenser

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Condensation inside horizontal tubes

stratified flow

annular flow

RECIRCULATED WATER

• The water flowing through the condenser is pumped to a remote location, cooled and reused

• Design water temperature is 25oC• A water flow rate of 416 kg/s of refrigeration is

required to absorb the heat rejected by the system condenser

• The water leaving the condenser is about 40°C

Shell and Tube design procedure

• Kern’s Method

• Bell’s method

This method is designed to predict the local heat transfer coefficient and pressure drop by incorporating the effect of leak and by-passing inside the shell and also can be used to investigate the effect of constructional tolerance and the use of seal strip

This method was based on experimental work on commercial exchangers with standard tolerances and will give a reasonably satisfactory prediction of the heat-transfer coefficient for standard designs.

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Kern’s Method

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Pressure drop inside the tubes

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Pressure drop inside the shell

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Four Condenser Configuration are Possible

1) Horizontal with condensation in shell side and cooling medium in the tubes.

2) Horizontal with condensation in tube side cooling medium in shell side.

3) Vertical with condensation in the shell.

4) Vertical with condensation in the tubes.

DESIGN CALCULATIONS OF CONDENSER

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1.3 kpa

ΔP = 53 kpa