Pulsation dampeners - reg

[vjr0512]

For one of the OFfshore project, we have chemical injection pumps for which the operating range is 29 bar to 750 bar. Vendor is using bladder type pulsation dampener. Here is the problem what vendor says.

Quote

Currently we are procuring the pulsation dampers for the chemical injection packages. The pulsation dampers have to comply with the specifications. However the operating pressure has a large range and pulsation dampers are not suitable for such large range. To make the pulsation damper operate properly, the maximum possible ratio will be four. This is the ratio between the minimum and maximum operating pressure. Below de minimum pressure the pulsation dampers will not function properly and above the maximum pressure the pulsation damper can be damaged. Taken this into account with the suggested operating range will the pulsation dampers not function correctly.

Therefore please check if the large range of the pressure injection points are correct. An alternative solution is that the pulsation damper starts to function at a higher pressure than the minimum operating pressure.

Unquote

For the above pump , vendor says that the between 29 bar to 190 bar the pulsation dampener will not function and will start functioning only from 190 bar upto 750 bar.

Thanks to provide us a solution for this. If we change the type of Pulsation dampener from Bladder type to Volume bottle type, will this solve this problem but will the size of the item be bigger??

 

[LittleInch]

Wow. 29 to 750 bar range is huge, 1:25. I'm far from surprised that a damper won't work at mor ethan 1:4 and to be frank I wouldn't actually expect it to work that well at the extrem ends of that range. I doubt any type of damper would work effectively at more than 1:4 or 1:5, but ask the vendor.

Only you know your system and what impact pulsation has on your system so if the pulses are quite small then at lower pressures the pulses should be easily accomadated in the pressure capacity of the system. By the way, the 190 bar figure is just a guide, basically its anything less than about 200 bar it won't work as well, not that it will suddenly work at 191 and not at 189.

Have a good think about why you need pulsation dampers in the first place or has someone just put it in becauses it's "standard" or " a good idea". Type, size, speed and number of injection pumps will also have a big impact on pulsation.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[vjr0512]

Little Inch,

Thank you for your prompt response and your informative reply.

The pump is of diaphragm type for process scale inhibitor. There are two pumps ( one working + 1 standby). Each pump is of multi head ( 6 heads) each head [pumping 3.1 lit / hr. I will also check with the vendor for the requirement of the Pulsation dampener and also the process guys on the range of operation.

Thanks

 

[Pumpsonly]

With 6 head pump, the pulsation would not be that of a great concern. You need to provide the pump data to the vendor for dampener sizing. You did not mention why is there such a wide range of working pressure. Normally the dampener is precharge to about 60% of the working pressure. 60% of 750bar is 450 bar precharge pressure. It definitely will not work if your working pressure is below this pressure.

 

[micalbrch]

A bladder type dampener only works as long as the pre-charge gas pressure is lower than the pump's operating pressure. And even if it is lower it will not dampen equally over the entire pressure range. So, what the vendor tells you is correct. You can install several bladder type dampeners, pre-charged to different pressures. But that only makes sense if the pressure will not vary that much every day because you must isolate (by shut-off valves) the dampeners which are not correctly charged for the actual pressure.

A volume bottle type (air over liquid) dampener is much better for different operating pressures but:
- it will be pretty big and thus very expensive for 750 bar
- you need probably a high pressure compressor to charge it if your liquid tends to absorb oxygen (or you use nitrogen for charging)

What Pumpsonly already mentioned: What applications is that where the pressure varies between 29 and 750 bar?

 

[vjr0512]

Dear all

Thanks so much for your replies. I am checking with the process guys on the operating range with respect to pressure. I will revert back with the findings and resolution .