3 replies to this topic

[zaidanamir]

Hello,

 

Currently, I'm in the middle of a project involving the addition of a reciprocating compressor. The compressor is intended to supply hydrogen from the SMR plant to the tube trailer, which will then be used to provide hydrogen to sections operating in a batch configuration. The capacity is 300 Nm³/h under normal conditions and 400 Nm³/h at maximum capacity. The supply pressure is around 29-30 barg, while the discharge pressure is 150 barg.

 

The issue causing me headaches so far is the compressor vendor's statement, and I'm quoting: "the pulsation device is not required since the equipment is too small." Already had several discussions with this vendor and asked them to provide proof of a pulsation study to support their statement, but I have received no results. The vendor is actually from China, and they claim to adopt API 618-2007 & SH/T 3143-2012. The latter is a Chinese engineering technical specification for reciprocating compressors. I believe they are not fully adhering to API 618 in their design.

 

Do any of you have experience regarding the pulsation device? Is it possible to determine the necessity of the pulsation device solely based on compressor capacity? From what I know (referring to API 618), the pulsation study is categorized based on discharge pressure and rated power. Regardless of size, if the specifications fall within the range, it will require a pulsation device. The only difference would be the complexity of the pulsation study, right?

 

I hope someone can shed some light on this.

 

Thanks!

[krishnasagar.atluri]

Hi, As per API 618, we need a pulsation dampener irrespective of the motor rating. Based on the final discharge pressure and kW/cylinder rating, API 618 classifies which type of approach study is to be performed. Default is approach 1 which is pulsation dampener sizing. Minimum size of pulsation dampener on suction and discharge side shall be at least 0.03 m3 or else as per the formula stated in 618 whichever is greater. Theoretically, If the suction and discharge pipe sizes are very much higher, then the pipes can be considered as dampeners with orifices before and after the compressor cylinders to reduce the pulsation limits within API 618. However, this practice is not followed for API compliant machines.

[zaidanamir]

Hi Krishnasagar,

 

Thank you for your reply. I understand the design approach specified in API 618. However, could you clarify your statement, "If the suction and discharge pipe sizes are very much higher"? How much larger do the pipes need to be to allow orifice installation as a replacement for dampeners?

 

At the specified flow rate, both my suction and discharge pipes are sized at 1". Is it possible to install an orifice plate to replace the dampeners with this pipe size?

 

Anyway, my understanding is that the decision to install pulsation devices needs to be based on the results of a pulsation study, correct? The determination should not be solely based on the size of the compressor, as the vendor suggests."

[krishnasagar.atluri]

Hello The amount that the pipe size must increase to absorb the pulsations is beyond my knowledge. Vendors typically take into account the pipeline's orifices to limit pulsation in the initial phase only. However, following the pulsation study, these orifice requirements will be verified. Higher rod loads will result from the installation of orifices since they will increase power consumption and differential pressure across the machine. Therefore, we typically ask vendors to ensure that all of these are already taken into account in their design at initial phase. Pulsation dampeners are mandated by API 618, as Approach 1 is default, which says the minimum size of the dampener as 0.03 m³. With respect to the study, the vendor will lower the pulsations by installing an orifice on the lines, considering internals inside the dampener, etc.