Basic Electronics for diploma students as per technical education Kerala Syll...
CSHM
1.
2. Virtual Look inside separation process
By:
Dirk Glaser
Business Development Manager for Radiometric Measurement
Endress+Hauser GmbH & Co. KG
Germany
11. Pro / Con
Pro
• one measuring point
• one nozzle
• one cross section
• less property used
Con
• No distinguished
measurement
• All in one place –not
where required
• No information before
and after the
measuring point
Common measurement:
12. Valuable Information in Separation
• Sand jettingSand Accumulation
• Demulsifier
• Throughput
Separation Progress
• Throughput
• Quality
Water cut
17. ROI – Chemicals +…
6,000 barrels / day 9.36 Mio. l / day
Optimized use safes 7ppm demulsifier / l
savings: 65 liters a day.
Average price of 7 CAN$ / liter
ROI 13 month
Savings: 13,759.00CAN$ / month
Costs: ~180.000,00CAN$
This presentation is about separation process. Any type of separator FWKO, treater, desalter, …… has more or less the same task: to separate the oil from others.
To know what this presentation is about this is an introduction.
Through the inlet the mixture of oil water and sand is fed to the separator. This is separated by gravity. However there are additional methods to accelerate and optimize the separation process. Such as adding chemicals to solve the emulsion faster.
Sand is accumulating and is reducing the volume over time which is used for separation. So getting rid of the sand in an effective way is important to run the separation process efficient.
At the end of the separation process ideal wise there is pure oil and pure water drained off.
The cleaner the water less effort is required when recycling the water. This also means less energy = less costs.
To be able to monitor and optimize these process measurement is required. Since the separation takes places through different densities it is necessary to measure these. To most detailed view is given with a profiling system using Gamma radiation.
The working principle is as followed.
One or more radioactive sources are inserted into a protection tube. Outside the vessel detectors are installed to measure the radiation coming from the source but attenuated by the media. The higher the density the lower the radiation measured by the detectors.
With this information and measurement now a density profile can be established. Shown on the right side.
There are several options of how to implement a profiling system.
Arrangement of detectors
Immersion tube, straight, bended, curved
Measuring range – covering the entire vessel; a specific measuring range
Resolution = distribution and numbers of detectors.
Typically this is a measuring point in one location - spot measurement.
Most picutres show the separators as narrow vessel. With the profiling system in place and the short vessel it suggests the profiling offers a good view. However in reality the vessels are much longer 20m and more. Normally the measurement is placed close to the outlet to monitor the oil overspill or the water drainage.
But what happens during the 15m before the measurement?
No matter where a profiling system is placed. As long as it it’s a pot measurement it will only provide a look inside the separation process in that one spot.
Control of sand jetting or demulsifer is limited possible.
Just have a look to sand accumulation. Of course there is sand accumulation through the entire bottom of the separator. However the closer to the inlet the more it will be. But when the sand accumualtion is detected before the water outlet and Or weir there is already quite a bit of sand in the separator. It reduces the usable volume and increases the weight.
To get rid of this sand sand jetting is used. Either the sand jetting is done on a regular base whether it is required or not. Or it is done when the sand is detected by the profiling system.
Both options have a limitation: 1) sand jetting is done too often
2) sand jetting is done too late and reduces usable volume.
What if this could be optimized? To measure the sand level in earlier stage of the separation process – closer to the inlet.
It would allow to detect sand earlier but also avoids too much of sand in the vessel once it was detected.
It makes more sense to measure the sand level /accumulation closer to the inlet to detect the amount earlier and to monitor it. From there the decision can be made sand jetting is done.
Now having a look to the position of a spot measurement and considering what happens in the separation process before?
To monitor the emulsion layer at the end of the separation process is quite late.
At the end of the separation it is more of an interest to monitor the oil going over the weir or into the oil box.
For the emulsion layer it more beneficial to be monitored in the center area. Here the thickness can help to control the additives like demulsifieres and also the throughput
What is really interesting to be monitored is the oil overspill. This ensured the oil quality. And the emulsion layer which should be quite small at this stage. Underneath the emulsion layer water is drained of and only water. If there is oil in it it will increase the necessary recycling costs.
Summarize the pro and the cons of such a system.
When looking to installation it requires one nozzle. There is one cross section where and it requires less property.
However there are limitations.
There is no distinguished measurement for the different tasks.
There is no information before that measuring point (also not after).
Let’s put it in perspective what is important for the separation process to be measured
Sand accumulation
Emulsion layer
Separation of Oil/water at the outlet
Only by measuring these parameters it possible to influence them. And the measurement needs to be taken where it most useful.
A multiple spot measurement is the best way of getting transparency to the separation process.
Measuring points placed where required and designed to measure specific area.
Close to the inlet a measurement for sand
In the middle one for the separation = emulsion
And at the end one for monitor the oil quality.
Three sections providing three sectional profiles. Each section is not anymore covering the entire vessel but the area which is of interest. All together can give a 3 dimensional profile of the separation process.
It requires 3 nozzles or more depending on the numbers of sections. But three is what gives way more information than a spot measurement but is still not too oversized.
This sectional or 3D profiling offers now more potential to the operators to improve the efficiency of the separation process.
Next slides will give an indea of what a profiling system can do.
It might seem to be complicated and a lot of effort to install a profiler. The next slides will give an idea of what is required but it will also show that the effort is limited.
The earlier the system is considered the better and easier the installation will be.
First about the nozzles. For each dry well a nozzle is required. The number of nozzles is equal to the no. of sections.
Important is the position of the nozzle. The source position is fixed by the profiling system. In order to make the design and installation easy ideal wise the nozzle is position straight above the source position. For new planning's this can be considered upfront and is not complicated.
For existing vessels where an upgrade should done mostly the nozzle is not straight above the source position. This is not a limitation then a bended dip tube is required. As before said the source position is given by the profiling design and is essential.
Coming to the dry well. It is the protection of the source the dry well is the separation of process and environment. The dry well is mounted to the nozzle directly. The spool piece is the adaptation to the source containers – if required.
Having a spool piece in place the nozzle can have a different flange than the container itself.
A big advantage regarding saftey is that with a dry well ther source(s) can be retrieved back any time. The container with the source can be dismounted without a shut down.
On the other hand if there is a shutdown also then the source can be pulled back into the container and is safe. The separator is free of radiation.
Mounting of FMGs.
Basically there are two different options of mounting the detectors.
1) free stand: the detectors are mounted to a frame which is not in contact with the vessel.
2) the detectors are mounted to a frame which is attached to the vessel.
Free stand:
The free stand is a frame which stands on the ground. The detectors are mounted to that frame. The frame is not in contact with the vessel. However to avoid movements usually the frame has a fixation at the top.
This solution is usually used for brown field applications – retrofit; upgrading an existing vessel.
But this solution usually requires more space / property.
The brackets which are attached to vessel need clamps which are welded to the separator. Therefor this for new applications where the welding is done before the testing.
The clamps are in place right up front. But the frame with the detectors is mounted when the site is ready for it. The frame is bolted to the clamps and the detectors are mounted to the frame. Both frame and detectors still have a certain flexibility for adjustment.
These frames need to be considered in the design but require less space.
Examples for free stands.
Left: Straight stand. Concrete foundation where the stand is mounted to. Fixation at the top to the wall of the building behind and to the beam where the leader is attached to. The detecors are mounted on horzintal pipes. The pipes and the brackets for the detectors are adjustable.
Right: also the frame stand on a concrete foundation. Due to the size and design there is not fixation the top required. With this design the detectors are adjustable the pipes not.
The frame is not attached to the vessel. For the design of the profiling system the detectors are arranged along the vessel – follow the vessel shape.
Attached to the separator:
Left: The frame shown here is bolted on to the clamps which are welded to the separator. The horizontal bars are also adjustable. Also the cable tray was mounted to the frame.
Right: Another frame with a different design. The blue pipes are welded to a plate this plate is bolted to the clamp which is welded to the Separator. Everything is adjustable here too.
Monitoring the Separation process is very important. It offers a huge potential for optimization and therefore for efficiency which leads to cost control and cost reduction.
To be able to do this the right system in place is essential. Splitting density profiling in to sections gives a vertical but also a horizontal profile. With this information costs optimization is possible. Installation is not of an huge effort. If it is considered from the beginning it is even easier.
3D profiling: It allows to have a virtual look into the separation process.
