our site fuel oil system is as

1- Fuel oil forwarding skid two centrifugal pumps take fuel from storage tank and send towards Gt

2- Heating skid-electric heater for heating if temp of oil is low

3- filtering skid regulate and filter the oil

I paste the system description below. since the site is in commissioning, first psv at filtering skid was operating continuously, setting of psv is 12 bar while forwarding pump discharge is 8 bar. installed new psv it was also doing same

there is a pressure regulating valve which reduce pressure around 5 bar with reference pressure of air (PRV is differential pressure type). there is a gauge at which measure outlet pressure of skid. there is pressure variation continuously around 4 to 6 bar.

following have been checked but no final result

1-accumulator pressure
2-PRV
3-Saytems NRV
4-forwarding pump suction stainer
5-Air bleeding

another, when there is hunting in system, Same time fuel flow at local flow counter stops but there is no trouble inside GT operation. This equipment is subject to European directive 97/23/EC (pressure equipment directive (PED) and 94/9/EC (Equipment for use in potentially explosive atmospheres).

* One safety valve (PSV351) protects the upstream circuit against an eventual over pressure if isolating valves are closed at the same moment and the fuel temperature increases.
Adjustment: 12-bar g ( +0/-1,2bar) / 174PSI . (+0/-17,5)

* One skid isolating valve (HV302).

* One regulating system to control the Distillate fuel oil pressure at GT inlet. It is constituted of one main regulating valve (PCV 355 piloted by air pressure reference), one needle valve (HV 355), two reverse mounted spring loaded check valves (NV355A, NV355B).

* One air pressure regulating valve (AFRG355) with filter automatic drain and pressure gauge gives a pressure reference to the regulation valve PCV355. Setting: 4.5 barg.

* One pneumatic valve (FV363), normally open, is necessary to insure a minimum flow for pump pressure regulating valve, and heater if any, during the start up with fuel oil (when the stop of valve FV359 and PCV355 are closed ).

* Two filters (FLT 301,FLT 302), one in operation and the other in stand-by, equipped with:

- Four isolating valves (HV303, HV304, HV311, HV312),

- One balancing valve (HV306)

- One drain valve or each body (HV308, HV310)

- One vent valve for each body (HV307, HV309)

- One safety valve for each body (PSV361, PSV362), only for thermal expansion Adjustment: 10-bar g ( +0/-1bar)

For TG type, each filter body contains:

- 9 synthetic cartridges, ß17 = 200, Ref: PH.718.01.CN.
* One accumulator (ACC 301) absorbs sudden fuel pressure variations at GT inlet. Typ of TG Distillate fuel oil
9E 2,5 bar g / 36 PSI

* One pressure accumulator isolating valve (HV318). since site is in commissioning,

 

KA,

You say the turbine is being commissioned. You need to allow the commissioning engineers to work through the issues at the site and deliver a working system. This is all part of normal commissioning activities. A <b>LOT</b> of components have to work together, and to be adjusted and tuned to work together, for the liquid fuel system to work properly. It is a very complicated system, and a <b>LOT</b> of the components are <b>NOT</b> directly controlled or monitored by the Speedtronic, so they all have to be adjusted together as a system to get the system to work as a whole.

It's like organizing a team; everyone on the team needs to know their function and how to execute their function in harmony with every other person on the team. Sometimes, it takes a lot of time to get all the team members working together to get the desired output.

Two things to know about liquid fuel systems: Air in the piping can cause all manner of problems, and oscillating pressure is the biggest indication of air trapped in the fuel piping between the fuel forwarding skid and the turbine liquid fuel stop valve. A <b>LOT</b> of fuel oil piping systems are not designed to have slopes to allow any trapped air to rise to a high point, and the high point needs a vent to allow the air to be removed.

Many times the pressure regulator on the fuel forwarding skid has (or should have) a manual needle valve in the sensing line, and the purpose of that valve is to help try to dampen the pressure pulsations <b>AFTER</b> as much of the air as possible has been removed. Air can be trapped in the tops of filter canisters and they need to be bled of any air. But air is a big problem, and it's not generally properly accounted for in the design of fuel supply piping and so makes commissioning and operations very problematic.

The second thing is that flushing the liquid fuel system <b>all the way to the fuel nozzles</b> is very important. A lot of cigarette butts and weld slag and metal shavings and dirt get into the piping and tubing during assembly, and these can cause check valves to not seat properly.

You have several threads open at the same time on control.com about problems with the liquid fuel system. Allow the commissioning personnel the time they need to get all the components working together. And, you will likely be happy with the results.

Patience is a virtue that has some very nice rewards.