3 replies to this topic

[Dev 009]

Dear All, Its been long I am back here, I need a help in finding out the best way to minimize the sludge formation inside a crude oil storage tanks. My Client is ready to adopt BLABO (Tank cleaning method) but i feel it will be too costly afair. I would prefer to go for mixers ( except propellers which are not effective), but sure about best design, alignment inside the tank, to achieve effective sludge removal (in case of formation).

Your suggestions are highly appreciated.

Thanks

[Qalander (Chem)]

Dear All, Its been long I am back here, I need a help in finding out the best way to minimize the sludge formation inside a crude oil storage tanks. My Client is ready to adopt BLABO (Tank cleaning method) but i feel it will be too costly afair. I would prefer to go for mixers ( except propellers which are not effective), but sure about best design, alignment inside the tank, to achieve effective sludge removal (in case of formation).

Your suggestions are highly appreciated.

Thanks

Dear Rohit Hello/Good Evening, Firstly You are Most Welcomed on re-entry.

As Regards Your query I feel this is not at all simple question but very complicated in most of the refinery plants, off-sites and utilities.

Depending upon(Sludge formation reduction)

• the way we feed the plants, design crude tanks raised pads (grade elevations)
• in relation to the Feed Pumps Minimum NPSH Required fulfilment.
• Ensure crude tanks emptying to the minimum levels without making Floating roof stuck
• Avoid extra ordinary settling time
• Ensure mixing/agitating means regular efficient usage(Whether) side entry propellers 3 to 5 for larger diameters or Jet-mixing branch off usage while top up
• Control of very heavy/dirty slops and so on....

For Cleaning there are many more informations needed about

resources and piping

machinery, equipments available at disposal and

the type of Crude storage tanks involved

Crude type, physical/chemical characteristics of sludge and

levels and topography inside crude tank etc. etc...,

without all that it is indeed very difficult to guide right now,you should appreciate and realize.

feel free to provide more explicit details and info for rendering any possible help.
Best of luck

Edited by Qalander (Chem), 04 March 2010 - 01:18 PM.

[Dev 009]

[/quote]

Dear Rohit Hello/Good Evening, Firstly You are Most Welcomed on re-entry.

As Regards Your query I feel this is not at all simple question but very complicated in most of the refinery plants, off-sites and utilities.

Depending upon(Sludge formation reduction)

• the way we feed the plants, design crude tanks raised pads (grade elevations)
• in relation to the Feed Pumps Minimum NPSH Required fulfilment.
• Ensure crude tanks emptying to the minimum levels without making Floating roof stuck
• Avoid extra ordinary settling time
• Ensure mixing/agitating means regular efficient usage(Whether) side entry propellers 3 to 5 for larger diameters or Jet-mixing branch off usage while top up
• Control of very heavy/dirty slops and so on....

For Cleaning there are many more informations needed about

resources and piping

machinery, equipments available at disposal and

the type of Crude storage tanks involved

Crude type, physical/chemical characteristics of sludge and

levels and topography inside crude tank etc. etc...,

without all that it is indeed very difficult to guide right now,you should appreciate and realize.

feel free to provide more explicit details and info for rendering any possible help.
Best of luck
[/quote]

Dear Qlander , appriciate your reply,

Here we are talking about
1. 50000 m3 Crude storage Tank of 79m dia.
2. Crude Oil Types are Kuwait Export, Maya, Oman Export, Basara Light etc. The refinery design is based on three slate options
a. 100% Kuwait Crude
b. 60% Kuwait, 40% Maya
c. 50% Oman & 50% Basara Light.
but either 100% crude of any type or blend or max three type of crude is also possible.

Tank pad hight is appx 1.0 m & & NPSH for Pumps are varying based on type of crude , its 1.16m for Basara light but 4 m for Kuwait. Also I am struggling to find a solution for Pump for the same which can pump all variety of crude.

The settling time for tanks is 24 hrs appx. The tanks are of floating roof type with 13.5 m height.

We are thinking of providing Jet mixers to achieve required suspension, thereby avoiding sludge formation at regular interval. But our client is insisting on Propeller mixers which we came to know from one of operating companies experience that they are not much efficient. Also side entry propeller will decrease the effective capacity of tanks.

The tank is sloped prepherially also heating coil arrangement is provided inside the tanks.

I was thinking of providing a horizontal nozzle arrangement with piping inside the tank which will scoope out the sludge if any with recirculation of light crude oil. but for that I need a proper layout of mixing nozzle with minimum piping inside tanks.

The client is ready to pay for BLABO which is a automatic tank cleaning system (non man entry) for sludge removal & tank cleaning, but the frequrency of such operation will be determined by sludge formation rate. If we minimize the sludge formation the same can be avoided for a larger period of time.

I hope this would atleast somehow clarify your understanding about system.

Thanks

[Qalander (Chem)]

[quote name='Rohit Namdev' date='05 March 2010 - 04:41 PM' timestamp='1267789860' post='36850']
[/quote]

Dear Rohit Hello/Good Evening, Firstly You are Most Welcomed on re-entry.

As Regards Your query I feel this is not at all simple question but very complicated in most of the refinery plants, off-sites and utilities.

Depending upon(Sludge formation reduction)

• the way we feed the plants, design crude tanks raised pads (grade elevations)
• in relation to the Feed Pumps Minimum NPSH Required fulfilment.
• Ensure crude tanks emptying to the minimum levels without making Floating roof stuck
• Avoid extra ordinary settling time
• Ensure mixing/agitating means regular efficient usage(Whether) side entry propellers 3 to 5 for larger diameters or Jet-mixing branch off usage while top up
• Control of very heavy/dirty slops and so on....

For Cleaning there are many more informations needed about

resources and piping

machinery, equipments available at disposal and

the type of Crude storage tanks involved

Crude type, physical/chemical characteristics of sludge and

levels and topography inside crude tank etc. etc...,

without all that it is indeed very difficult to guide right now,you should appreciate and realize.

feel free to provide more explicit details and info for rendering any possible help.
Best of luck
[/quote]

Dear Qlander , appriciate your reply,

Here we are talking about
1. 50000 m3 Crude storage Tank of 79m dia.
2. Crude Oil Types are Kuwait Export, Maya, Oman Export, Basara Light etc. The refinery design is based on three slate options
a. 100% Kuwait Crude
b. 60% Kuwait, 40% Maya
c. 50% Oman & 50% Basara Light.
but either 100% crude of any type or blend or max three type of crude is also possible.

Tank pad hight is appx 1.0 m & & NPSH for Pumps are varying based on type of crude , its 1.16m for Basara light but 4 m for Kuwait. Also I am struggling to find a solution for Pump for the same which can pump all variety of crude.

The settling time for tanks is 24 hrs appx. The tanks are of floating roof type with 13.5 m height.

We are thinking of providing Jet mixers to achieve required suspension, thereby avoiding sludge formation at regular interval. But our client is insisting on Propeller mixers which we came to know from one of operating companies experience that they are not much efficient. Also side entry propeller will decrease the effective capacity of tanks.

The tank is sloped prepherially also heating coil arrangement is provided inside the tanks.

I was thinking of providing a horizontal nozzle arrangement with piping inside the tank which will scoope out the sludge if any with recirculation of light crude oil. but for that I need a proper layout of mixing nozzle with minimum piping inside tanks.

The client is ready to pay for BLABO which is a automatic tank cleaning system (non man entry) for sludge removal & tank cleaning, but the frequrency of such operation will be determined by sludge formation rate. If we minimize the sludge formation the same can be avoided for a larger period of time.

I hope this would atleast somehow clarify your understanding about system.

Thanks
[/quote]

Thanks for the valuable updates on the system in question, this will definitely help in analyzing and possible solution's finding.

I will further request if any sketch showing various views describing the nozzles on shell throughout circumference near bottom including man ways etc

Similarly are there any stilling well pipes/anti-rotating columns on either side of floating roof?

What are the Floating roof 'Normal operation' and 'clean-out setting' values;what is present setting.

What are the typical assays or physical property data for your referred crude especially 1) viscosities, 2) Pour points,3) Specific Gravity and any water of high asphaltine presence?

Having said that.Now about your query and solutions pros and cons.

Jet mixing;depending upon the Filling-in or Circulating pumps excess head/pressure availability for high velocity jet forming forming the option can't be viable.

Hazards; the Jet mixing induces strong agitating currents and may produce highly rotating condition for floating roof and unless strong enough doubly strengthened anti-rotating system is available

damages to floating roof and rolling ladder can not be ruled out.

Side Entry Propeller type;multiple mixers might prove effective if the angles are religiously adjusted,with sufficient Electric power, spare/additional shell nozzles near bottom are available for mixers installation.

Hazards;possible floating roof blade damages unless proper design, low level alarms& Low Low level agitator shut-off are provided in-place. Seals Leakage of these agitators sometimes pose problems if selected type has inferior quality/poor design.

Hope this shows way forward.

Further help is possible subject to the requested above data provision in the beginning of today's post.
Best of luck