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Process Design Relief Calculation

The document outlines the determination of a fire scenario for a pressure safety valve (PSV) associated with a natural gas vessel, R-1001, using API-521. It includes calculations for relief load and parameters such as diameter, height, and set pressure, resulting in a relief load of 3874 kg/hr. Additionally, it notes that the relieving temperature for PSV design is assumed to be 400°C due to inconsistencies with maximum vessel wall temperature for carbon steel.

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70 views3 pages

Process Design Relief Calculation

The document outlines the determination of a fire scenario for a pressure safety valve (PSV) associated with a natural gas vessel, R-1001, using API-521. It includes calculations for relief load and parameters such as diameter, height, and set pressure, resulting in a relief load of 3874 kg/hr. Additionally, it notes that the relieving temperature for PSV design is assumed to be 400°C due to inconsistencies with maximum vessel wall temperature for carbon steel.

Uploaded by

mohmmadkhawja
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Educational Institute for Equipment and Process Design

2.PSV-1031
1.Determine the scenario, using API-521
Since it is R-1001 and exposed to fire then a fire scenario is defined

Parameters Value Parameters Value

Diameter 4.45 m M 16.54

Height 3.1 m Set Pressure 55 barg

Fluid Natural Gas Relieving Pressure 67.55 bara

Z 1.01 Accumulation 0.21

Cp/Cv 1.18 Material CS

2.Calculate the relief load, using API-520 Part1


Educational Institute for Equipment and Process Design
Educational Institute for Equipment and Process Design

Calculation

Parameters Value Parameters Value

Aw 65 m2 KD 0.975

C9 0.2772 116

C10 0.0395 Relief Load 3874 kg/hr

C 0.0254

Note : Relieving Temperature Calculation

since the ratio between operating pressure and PSV relieving pressure is very high, the relieving
temperature calculated is not consistent (it would exceed the maximum vessel wall temperature
for carbon steel, &o). The relieving temperature for PSV design has been assumed equal to 400°C
(considered the max allowable value for carbon steel). The actual relieving mass flow has been
calculated keeping the discharge capacity of the valve (volumetric flow rate) constant and scaling
the temperature down to 400°C.

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