8 replies to this topic

[pasquale]

Hi to all;

I would like to know if there are general guidelines for the maximum value of rho*v^2 at nozzle equipment (inlet and outlet).

Thanks in advance

[muchlis nugroho]

Hi,
I usually use 3000 for gas and 1500 for 2-phase in SI unit.

Rgds,
MNG

Hi to all;

I would like to know if there are general guidelines for the maximum value of rho*v^2 at nozzle equipment (inlet and outlet).

Thanks in advance

[Zauberberg]

Hello,

I recall this question has been raised in one of the Eng-Tips threads, followed by discussion about necessity of impingement plate installation. If this is the subject of your concern, TEMA recommends that inlet impingement protection be installed under the following conditions:

• When the rho*V2 through the inlet nozzle exceeds 2232 kg/(m*s2) or 1500 lb/(ft*s2) for non-corrosive, non-abrasive, single phase fluids
• When the rho*V2 through the inlet nozzle exceeds 744 kg/(m*s2) or 500 lb/(ft*s2) for corrosive or abrasive liquids
• When there is a nominally saturated vapor
• When there is a corrosive gas
• When there is two phase flow at the inlet

I guess these numbers can be used as a guideline for maximum Rho*V2 values for equipment nozzles without impingement baffles.

[Art Montemayor]

Zauberberg (or Sylvester, as I like to think of him) is on the right trail. If the equipment in question is a shell & tube heat exchanger, The Standards of the Tubular Exchanger Manufacturrers Association (TEMA) state:

"An impingement plate, or other means to protect the tube bundle against impinging fluids, shall be provided when entrance line values of rV2 (in lb/ft2-s) exceed the following:

Non-corrosive, non-abrasive, single phase fluids = 1,500
All other liquids, including a liquid at its boiling point = 500

For all other gases and vapors, including all nominally saturated vapors, and for liquid vapor mixtures, impingement protection is required.

In no case shall the shell or bundle entrance or exit area produce a value of rV2 in excess of 4,000 lb/ft2-s.

Consideration shall be given to the need of special devices to prevent erosion of the tube ends under the following conditions:

1. Use of an axial inlet nozzle;
2. Liquid rV2 is in excess of 6,000 lb/ft2-s."

Additionally, the NorSok P-100 Process Standards for Offshore applications state:

"Typically the following maximum inlet momentum for the inlet stream should be used on scrubbers:

• No inlet device: rV2 <= 1,000 kg/m2s
• Half pipe: rV2 <= 1,500 kg/m2s
• Inlet vane: rV2 <= 6,000 kg/m2s"

Pasquale has not revealed what type of equipment he is referring to and all we can do is guess. We need specifics basic data in order to generate specific, correct answers to the query.

[pasquale]

I have a xilenes splitter and I would like to know the maximum value of rho*v^2 on the vapor line nozzle (top of column) and for the nozzle that joints the reboiler (it's a furnace in my case) with the column.

this line is very critical in our design because there is two-phases flow (I have checked there is a spray flow). The size is 30inch then near the column there is an enlargement to 48 inch (so nozzle column is 48 inch).

I'm checking the hydraulics of this system but the mixed phase 30 inch line has a
value of rho*v^2 of 18500 Pa that seems too high for me.

Maybe it's better to change the diameter of this line ?

Any comments is appreciate

Pasquale

[process equipment]

hi.

i'm kind of confusing which r-v-sq to use from TEMA:
RCB-4.61 shell side impingement protection
RCB-4.62 shell or bundle entrance and exit
RCB-4.63 tube side

which one should be taken into account (design criterion) ?

thanks

[muchlis nugroho]

Hi,

Seems that I should revise my standard.

Rgds,
MNG

[refundycom@yahoo.com]

Hi all...

I have some enquiries regarding the momentum criterion for nozzle in separator (2 phases).

If we look to the DEP, the pv2 value is pv2>2100. May I know how this 2100 value is derived... is there any method to determine it? how they get that value...what happen if the pv2 is exceeded the max value...please kindly advice and thank you for helping.

HEY SORRY AGAIN FOR JUNPING IN BETWEEN

TEMA SPECIFIES THE VALUE OF ROWV2 VALUE ABOUT 2200 THATS TRUE, DOES ANY ONE KNOW WHAT VALUE DOSE HEI CODES CONVEY.

CERTAINLY I BELIEVE IT WILL BE VERY HIGH BUT DONT KNOW EXACTLY IF ANY ONE CAN GET IT.