2 replies to this topic

[Dhams]

Hi Forum,

 

I would appreciate your views on the appropriate discharge location for PSVs installed on a Heating Medium (Hot Water) System, which includes equipment such as expansion vessels, filters, heat exchangers, and associated piping.

Although the heating medium system is designed as a closed-loop circuit, there is a foreseeable risk of hydrocarbon contamination due to potential leakage across heat exchanger tubes or other exchanger failures. In such a scenario, the heating medium could become contaminated with process hydrocarbons.

Considering this possibility, I am evaluating the PSV discharge philosophy and would like to understand whether routing the PSV outlets to the flare header would be the preferred design approach for all PSVs associated with the heating medium system, rather than discharging to atmosphere or a safe drain system.

Could you please share your experience and recommendations regarding:

• Typical industry practice for heating medium hot water systems.
• Criteria used to determine whether PSV discharge should be routed to flare.
• Considerations related to hydrocarbon contamination risk, environmental requirements, and operational safety.
• Applicable standards or project-specific philosophies that influence this decision.

Thank you in advance for your insights.

 

Best regards,
Dhams

 

[latexman]

I assume the HC side and water side are not very corrosive, right? If one side is very corrosive then I might change my advice.

I would take some extra design and operational precautions to enhance the separation between HC streams and hot water streams to eliminate this concern.

Most shell-and-tube heat exchangers for our plants today are fabricated with seal-welded tube-to-tubesheet joints. The cost of the seal-welded joint is justified through increased reliability, reduced maintenance costs, and fewer process leaks.

Periodic testing of the water for HC should be inexpensive and indicate leakage. Frequent testing (weekly to monthly) after start-up for infant mortality failures, and switch to less frequent testing once the system has proven leak free (yearly). Think risk based maintenance.

[breizh]

Hi,

Just to clarify which stream is passing in tubes? HC?

What is the pressure inside the HX? water side, HC side to confirm HC will be able to contaminate water. 

Consider talking with supplier of specific analyser to measure HC in water, continuous monitoring.

HydroSense 4410-OCM | Arjay Engineering

 

My view.

Breizh