Orifices are used for lots of different things, not just to develop a differential pressure in order to be able to measure flow-rate. They are also commonly used to reduce flow-rates to protect equipment. In this system, they are used for both purposes.

The "bleed" valve you speak of, fabio9, is on the manifold block to which the hydraulic accumulator is affixed. Under normal operation, the "bleed" valve (it should really be called a drain valve) should be closed--and that ensures the hydraulic accumulator has a chance of working correctly. The isolation valve on the other side of the hydraulic accumulator (which is often called the "block valve" (block and bleed--get it?)) should be OPEN at all times when the unit is running (and even when it's not) so the hydraulic accumulator has a chance of working correctly. What does the hydraulic accumulator do? Well, if the IGVs have to move suddenly and quickly, the accumulator will provide additional hydraulic oil to the system to prevent a lag in IGV movement/operation. And, it also helps to prevent dips in hydraulic system pressure when high flows do occur. To do that, the hydraulic accumulator has to be properly charged (usually with an inert gas, such as nitrogen), AND the isolation (block) valve has to be fully open, and the drain (bleed) valve has to be fully closed. Otherwise, the accumulator will not function properly. MANY people do not learn how to properly check the accumulator charge and end up losing the charge, and then when they try to add nitrogen they don't actually get any nitrogen into the accumulator bladder. Finally, a LOT of people misidentify the block (isolation) and bleed (drain) valves, and they both either get opened or closed. It would appear to me that GE Belfort has tried to mitigate the possibility that the bleed valve was inadvertently left open by putting a very small orifice in the outlet of the bleed (drain) valve. The purpose of the drain valve is to remove pressurized hydraulic oil from the accumulator (AFTER the isolation (block) valve has been closed). They are sneaky little devils, those French.... ;-)

The hydraulic oil (from line OH (Oil-Hydraulic) see how they did that?) then goes to one side of VH3-1--which is a hydraulic dump valve assembly. In order to get high-pressure hydraulic oil from the electro-hydraulic servo valve (90TV-1)), through the hydraulic dump valve, and into the double-acting piston of the IGV actuator, HM3-1, the hydraulic dump valve has to be in the proper position. Trip Oil (from the line OLT (Oil-Lube, Trip)--see how that works??!?!!) pressure moves the hydraulic dump valve spool piece to allow high-pressure hydraulic oil to get from the electro-hydraulic servo valve to the IGV actuator piston to make it move. OIL IS ONLY FLOWING TO/FROM THE IGV ACTUATOR WHEN THE IGVs NEED TO MOVE--otherwise, it is a static system (no oil movement to or from). (The electrohydraulic servo-valve controls that--on order from the Mark*.)

There appear to be two 0.156" diameter orifices, one in each line to/from each side of the IGV actuator double-acting piston. GE Belfort must believe this is necessary to dampen any excessive IGV movement due to excessive high-pressure hydraulic oil flow-rates. (Never personally seen this before, but, as we know, those French are NEVER satisfied to leave decades-old engineering practices and principles alone. They are, after all, French--so, their way is (and MUST BE) better. And because they can change things, they will. No other reason required--if possible, it will be unnecessarily and needlessly complicated without explanation. Because they can.)

The last thing of note in the P&ID is the IGV solenoid valve, 20TV-1. In order to get OLT (Trip Oil) to the hydraulic dump valve, VH3-1, 20TV-1 has to be energized ("excited" as ControlsGuy25 said--gotta love that word: excited).

The one thing I'm not sure about on that P&ID is the device with the LITTLE, TINY 0.03" diameter orifice which is just after the 40 micron hydraulic supply filter, FH5-1, on the left of the drawing and just before the bleed (drain) valve. I believe that might be a check valve with a very small orifice drilled in it to allow flow in the reverse direction. In TRUE GE Belfort fashion, it is NOT identified on the drawing with a device number.... But sometimes these check valves with orifices drilled in them (they are often gravity-operated, swinging check valves) are used to help relieve pressure quickly in the event of an emergency trip, but allow full flow, otherwise. Again, GE Belfort is consistently inconsistent in not properly identifying the device, and the drawing of the device is also suspect and unusual. But--it's French, so it MUST be better, right. Even if it isn't (or can't be!) described.

Gotta run. Hope the shish tawuk is good in Tabuk!!! Man I miss the shish tawuk in Umm Al Quwain in the UAE....! (And the hummus, and the fatayer, and the onions, and the tabouleh, and just about everything else on the menu there! Simply AMAZING!!!)

 

this is really very helpfull , thank you both ControlsGuys25 and CSA .

 

fabio9,

By the way, I don’t intend to go into this kind of detail on every P&ID. (And I didn’t cover the LVDTs. And since ControlsGuy25 has worked on many GE Belfort-designed machines, I am hoping he can explain that device between the filter and the accumulator—from a Belfort perspective (something I will never achieve!).)

You will need to post how you understood the intent of the System Description of the system for the P&ID you post and then describe any issue(s) you have. That doesn’t mean, “How does this or that device work?” will get you an explanation (from me!), or that, “This is the P&ID for the Heating & Ventilation system; what does it mean?” will get a meaningful reply, either. You’re going to have to demonstrate some understanding and for any device you need help with you’re going to need provide your description of operation.

If this goes the way it might, you can expect some questions about device settings (such as the High L.O. Temperature alarm switch setting…) because just understanding the P&ID DOES NOT mean you know what actions devices may initiate or perform.

I would also STRONGLY SUGGEST you speak to any persons who were at the site during commissioning and/orthe Operations Manager to obtain the training manuals which were provided with the unit when new, or possibly additional training after commissioning. You will possibly find some good information in those training manuals, also, to supplement the System Descriptions in the Operation & Maintenance Manuals originally provided with the unit.

Finally, please remember two things: Many of your questions have probably been answered several times on Control.com, and the Search feature at the top of every page can be used to find key words and terms. Also, the turbine—while a very critical and important piece of equipment—serves to provide torque to the generator, which the generator converts to amperes (at a fairly constant voltage) and which get converted back into torque by electric motors and does “meaningful” other types of work (light; heat; computers; televisions; etc). The purpose of the turbine is to provide the power which the generator converts to electric power which earns money for the power plant owners. (Some plants really care more about the steam which might be produced by the gas turbine exhaust heat for a process, and the electricity is just a by-product—but it’s really about the generator, truth be told.)

You want help, you need to be involved in the process—use the resources you have, and ask questions when your understanding doesn’t seem to be correct (explaining what your understanding is). “Give a man to fish, feed him for a day; teach him to fish—feed him for life.”

 

fabio9,

By the way, I don’t intend to go into this kind of detail on every P&ID. (And I didn’t cover the LVDTs. And since ControlsGuy25 has worked on many GE Belfort-designed machines, I am hoping he can explain that device between the filter and the accumulator—from a Belfort perspective (something I will never achieve!).)

You will need to post how you understood the intent of the System Description of the system for the P&ID you post and then describe any issue(s) you have. That doesn’t mean, “How does this or that device work?” will get you an explanation (from me!), or that, “This is the P&ID for the Heating & Ventilation system; what does it mean?” will get a meaningful reply, either. You’re going to have to demonstrate some understanding and for any device you need help with you’re going to need provide your description of operation.

If this goes the way it might, you can expect some questions about device settings (such as the High L.O. Temperature alarm switch setting…) because just understanding the P&ID DOES NOT mean you know what actions devices may initiate or perform.

I would also STRONGLY SUGGEST you speak to any persons who were at the site during commissioning and/orthe Operations Manager to obtain the training manuals which were provided with the unit when new, or possibly additional training after commissioning. You will possibly find some good information in those training manuals, also, to supplement the System Descriptions in the Operation & Maintenance Manuals originally provided with the unit.

Finally, please remember two things: Many of your questions have probably been answered several times on Control.com, and the Search feature at the top of every page can be used to find key words and terms. Also, the turbine—while a very critical and important piece of equipment—serves to provide torque to the generator, which the generator converts to amperes (at a fairly constant voltage) and which get converted back into torque by electric motors and does “meaningful” other types of work (light; heat; computers; televisions; etc). The purpose of the turbine is to provide the power which the generator converts to electric power which earns money for the power plant owners. (Some plants really care more about the steam which might be produced by the gas turbine exhaust heat for a process, and the electricity is just a by-product—but it’s really about the generator, truth be told.)

You want help, you need to be involved in the process—use the resources you have, and ask questions when your understanding doesn’t seem to be correct (explaining what your understanding is). “Give a man to fish, feed him for a day; teach him to fish—feed him for life.”

hello sir , sorry for late response , its hard week

anyway , i knew mybe its hard for you to explain every P&ID and discuss something should be discrepped in every power plant but let me tell you something about my plant .

in my plant i work as a mechanical maintenance engineer there is also 3 engineers with me , the oldest one having 4 years experince in the plant and its also his first jop so we are all not having enough experince beside never went for training course we all never done a training course in plant , we work by our self and study the units from A to Z alone and without any training courses , its really very hard because there is always something you dont knew .

do you knew that i really get happy when i found something discrebed from A to Z , mybe its nothing for you but its a big thing for me and finding such an expertise engineer like you is really big thing for me .



thank

best regards

 

fabio9,

Ohhhh, I see untrained, inexperienced people working on multi-million Euro power plants very frequently. In today’s world, where automation sales people say the control systems will and do protect the equipment, owners and supervisors are not spending money for training or experience because they believe what the automation sales people say. AND, if they do spend money on training for their employees most of them will use the certification they receive to get a new, better-paying job—so owners and managers believe their training money was wasted. When they could increase the salary/wages of their newly trained employees to account for their new knowledge—and maybe the employees would not leave, and maybe become better employees because of their prior experience in the plant.

Yes; most gas turbine manufacturers/suppliers do a poor job of documenting their systems and equipment—to the detriment of their employees (who get less and less training all the time, too!) and their Customers. But, they believe that Customers will call them for service and support and they will make more profit. (The problem with that is that the manufacturers don’t have or retain experienced, knowledgeable field service employees so the Customers are often unhappy with OEM (Original Equipment Manufacturer) support.

I don’t mind answering a few questions, fully documenting and explaining systems on this forum is not easy or rewarding (we get paid EXACTLY THE SAME as the amount you paid to ask your question(s): Nothing. We do appreciatehearing if our responses were helpful—or not (because most of us want to provide good information and use the feedback to improve when we can). And, it is satisfying to hear when our efforts were helpful.

But, the more you dive into and dig for the information you want the better you will retain it. And that brings its own satisfaction and reward. We can answer specific questions and clarify things (not doubts!!!). But it’s unreasonable to expect a stranger to train you for free. And a lot of your questions have probably been asked and answered before on Control.con, and you can use the ‘Search’ feature to look—and probably learn more than you thought you would. There’s 20 years or so of GE-design heavy duty gas turbine controls-related stuff (including mechanical stuff) in the archives of Control.com.

Best of luck!