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[abdelkareem]

Good Day,

 

My name is Kareem, I am a mechanical engineer, working as a project engineer in CNG (compressed natural gas) company.

our gas has density= 0.717 kg/m3 and specific gravity= 0.6.

As well as, we are designing the PRS for our clients (pressure reduction station) has the following specializations:

 

- Inlet pressure: 250 bar.

- Outlet pressure: 7 bar.

- Flow Rate: 2,500 smch.

-  Inlet gas temperature (t1): 20 C°.

- Outlet temperature Required (t2) > 5C°. 

 

I assumed the drop in the temperature after regulation will be 0.3 C° for one bar drop ((250-7)*0.3)=72.9C°.

 

So add preheating system before the regulations and our heating system has the following specification:

 

- Water tank (flow of the water = 0m3/hr),

- Water temperature (t3)= 85C°.

- 4 nos. Spiral Coil for the CNG are connected as a series for CNG (Flow of the CNG = 2,500 m3/hr).

- Each spiral coil dimensions : ((H=50cm, R=17 cm, n=5))*4 nos.

- Electrical heating element to heat the water. (127 KW)

 

The Requirements:

I need to know what is the minimum volume of the water (the dimensions of the water tank) to keep the gas temperature not less than 5C° at flow 2,500 m3/hr and heating capacity equal 127 KW.

 

(Kindly find the attached photo)

 

does anybody have idea how can I design the water tank?

 

Regards,

 

Abdelkareem Abdelbari.

[DB Shah]

Dear Abdelmareem,

 

Your density of 0.717 kg/m3 seems incorrect for both inlet and outlet conditions.

 

As you have given 2500 m3/hr (I understand ACM/hr), heat load calculated based on volumetric flow may be wrong.

 

Kindly simulate temperature after pressure reduction.  With negative temperature, I will suggest you to use anti freezing fluid. Water freezing will be an issue in elect heating failure case.

 

You may ask some good process engineer in your team to work out the solution in totality.

 

Regards

DB Shah