The transfer of heat to and from process fluids is critical to the operation of most process plants. Cooling medium and heating medium systems are generally robust but there are a number of problems which can occur if these systems are not designed carefully.
- Buckling of underground piping due to sub-atmospheric pressures following a “low pressure” event such as trip of one or more pumps.
- Full vacuum in the highest elevation heat exchangers following pump trip.
- Excessive surge pressures when the pump is restarted and the vapour pockets collapse.
- Surge pressures in excess of the piping design pressure, caused by:
emergency shut down of a heat exchanger
rupture of a heat exchanger tube
pump trip
pump start-up
check valve slam - Fatigue failure caused by high piping vibration or excessive piping loads.
- Poor controller tuning.
What Can Hydraulic Analysis Limited Offer?
- Verification of the correct “steady state” hydraulic performance of the cooling water system. For example:
accurate sizing of flow balancing devices (restriction orifices, trim valves etc)
confirm if there is enough available pressure drop across the heat exchangers
confirm if there is enough supply pressure to the heat exchangers
optimise the size of supply and return piping to each heat exchanger - Surge analysis to specify the optimum size, type and location of vacuum breaking devices which may be needed (e.g. air admission/ release valves, surge tower).
- Specification of shutdown valves.
- Verification of the proposed start-up procedure.
- Accurate sizing of air release valves.
- Specification of the required minimum and maximum design pressure.
- Calculation of the maximum out-of-balance piping loads imposed during an upset condition, for use in designing the piping supports.
- Dynamic simulation to calculate and verify the required controller tuning constants.
- Specification of the optimum type of check valve.
