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Considering a Multi-stage-multi-hole Restriction orifice instead of diffusers in geo rock mufflers

Considering a Multi-stage-multi-hole Restriction orifice instead of diffusers in geo rock mufflers

Considering a Multi-stage-multi-hole Restriction orifice instead of diffusers in geo rock mufflers


I am a new engineer in our company and my first CAPEX is to install a new rock muffler on our plant station.
I have several design in mind already but I am considering multi-stage RO as a primary alternative since it is cost and maintenance effective.

My question is, is the multi-stage applicable to this application? I am to drop pressure near atmospheric since the steam is to be vented out to atmosphere.

I am considering this instead of a diffuser inside the sound chamber filled with rocks. I was thinking of using multi-stage RO before the steam is vented inside the sound chamber insteaed of using the diffuser for this job. The vented steam will be allowed to expand in the chamber on to the pile of rocks and to the atmosphere.


RE: Considering a Multi-stage-multi-hole Restriction orifice instead of diffusers in geo rock mufflers

What is the application?

You've given no sizes, no flow rates, no pressures, no velocities, no idea what the fluid is (guess steam), so how is anyone going to answer?

Also define rock muffler, it might be a term familiar to you or your company, but not to me.

What is your aim?, reduce noise, velocity, ? To what level?

Why is the current system being replaced?

Need a lot more info to provide any useful advice.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Considering a Multi-stage-multi-hole Restriction orifice instead of diffusers in geo rock mufflers

Does the current diffuser allow for even distribution of steam into the chamber holding the rocks - if so, how will you enable good distribution withe a multistage RO?

RE: Considering a Multi-stage-multi-hole Restriction orifice instead of diffusers in geo rock mufflers

Hi LittleInch,

Thank you for the reminders. I will keep them in mind. This is the first time I used a forum but what I just wanted to know is a general idea if what I posted will be possible based from history and experience if this has ever been used before.

Rock mufflers are used for venting out steam in cases of partial loading or tripping in geothermal applications. They are usually sized at maximum steam conditions. While venting out, it should attenuate noise and prevent ground fogging, as for noise, < 90dBa. It uses diffusers to reduce velocity and pressure of steam to near atmospheric since it is to be vented out to the atmosphere. The diffuser is a perforated pipe, sized to produce the desired pressure, velocity and estimated noise attenuation.I think the appropriate terms is a sparger which consists of primary and secondary diffusers. Conditions are as follows;

Maximum Steam Condition:
Flowrate: 500kph
Steam pressure: 100psig
valve dP 50psig
Inlet pressure to primary diffuser is 50psig (not accounting the total line pressure loss due to static and friction since I am still validating the data)

Primary Diffuser is an 18" sch 40 pipe, 3m length connected to inlet pipe of the system. this is sized to have 440 holes which is .75" in size.
outlet pressure is at 35.1 psig.
Secondary diffuser is a 30" std pipe, 13m length enclosing the primary diffuser. This has 600 holes of the same size, .75".
the pressure to be vented out is 0.9 psig

I am considering the multi-stage since it has the same function as the diffusers to some extent. What I would just like to know is if this will work for this application and if yes, what are the challenges in the design. I need help on professional experience on multi-stage RO. I appreciate your concern. Your inputs will be valuable since I am still an inexperienced engineer and I just graduated recently.

Our current mufflers are running to failure and it is getting expensive just to maintain them, so we are looking for design alternatives that could give us the best maintainability and cost-efficiency.

Hi georgeverghese,

This is a very good consideration and a bad oversight for me. I was so focused on the noise and pressure reduction that I didn't look at the distribution. But my initial idea was to use a cylinder type vessel filled with rocks like a cyclone muffler design to compensate for the distribution by expanding the steam in the cylinder like a weber type separator, directing the steam flow to an opening to the rock chamber. But now that this has been brought up, I think it's a complicated design. I still need more experience. Thank you for your input.

RE: Considering a Multi-stage-multi-hole Restriction orifice instead of diffusers in geo rock mufflers

Your conditions are not extreme ....

Why re-invent the wheel ? ..... Buy something from people with design experience.


Sr. Process Engineer

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