3 replies to this topic

[Muhammad farhan]

Dear All

 

Greetings

 

I need expert advice, suggestion and opinions regarding sour water stripping operation.

 

We have commissioned sour water stripper unit in June 2017. It was designed by STP and EPCC by Hualu china. Since start up we face so many issue regarding its stripped water quality. It was design to treat sour water coming from DHT and NHT units and its stripped water again recycle back 40 % to DHT and NHT as wash water while remaining 60% as effluent. In general operating manual the specifications of stripped water provided as as follows

 

01. H2S <100 ppm

02. NH3 <100 ppm

 

Both of the above parameters are meeting and within limits. Issue is that the quality required by DHt and NHT unit (UOP) have some requirements to use stripped water as wash water.

01. TDS < 3 ppm

02. Cl < 1 ppm

03. TSS < 1 ppm

 

Stripped water producing from our stripper has following parameters

01. TDS 50-80 ppm

02. TSS 10-20 ppm

03 Cl       5-15 ppm

04 H2S    5-10 ppm

 

With these specifications we unable to recycle back as wash water and all the stripped is discarded as effluent. Some time we only able to use blend of stripped water and condensate (20:80 ratio) to meet results but most of the time we are wasting our water. Management has serious concern about water shortage and continuously forcing us to reuse it. Please comment how we can reduce TDS, TSS, Sulphides in stripped water. Can TDS remove through stripping means where the will go as we have one output which is stripped water and other output is sour acid gas. So where this TDS going still confused. We don't have any technical support from designer and expertise inside refinery as well. 

 

Please comment where we can reuse this water within refinery other than wash water in hydro processing units. How we can improve the quality of stripped water. 

 

 

 

 

[gegio1960]

Hi.

A Sour Water Stripper is not made to reduce TDS, TSS and Cl.

It is made to reduce H2S and NH3 and it seems to perform very well (5-10 ppm of H2S instead of the design figure of 100 ppm).

Subject to other verifications, maybe you can recycle your stripped water to a non catalytic process (typically to the Desalting section of Crude Distillation Unit).

Otherwise, in order to recycle it, you have to purify your water in a water treatment plant (either downstream or upstream).

Good luck!

[Muhammad farhan]

Dear gegio 

 

Sour water feed has 4000-6000 TDS. I just want to understand where this all TDS are going. Because we only have stripped water outlet and gas outlet. 

 

Does TDS include H2S or not. our laboratory report Sulphides, So H2S in form sulphide or part of TDS?

[gegio1960]

this question is totally different from the initial one....

i have no answer but, of course, a volatile part of the TDS is going to the gas, if the analysis is correct.

if you want an answer, you can try to make an S balance around the column