Hi
GE uses a Chemetron 8-ton CO₂ tank for fire protection in the 9FA gas turbine. However, the GE manual does not specify the required CO₂ level, instead referring to NFPA standards. According to both the NFPA and Chemetron manuals, the acceptable CO₂ level must be greater than the minimum amount required for the application. My question is: What is the sufficient CO₂ level for the GE 9FA gas turbine?

 

@ABDULLAH ENGINE,

Have you read the NOTES section of Fire Protection P&ID to see if there is any indication of the suggested level there? The NOTES section of GE P&IDS is typically on the first page of system’s P&ID and is often overlooked as a source of important information.

The philosophy for the fire protection systems using a large tank was always that the tank would contain at least twice the amount required for extinguishing a fire. This would allow the unit to be re-started shortly after a CO2 discharge event and still be able to extinguish a fire if the tank couldn’t be refilled immediately after a CO2 discharge.

If the machine was built and packaged by GE Belfort you should really ask GE Belfort what their philosophy is and what their recommendation is. Since you are working on a GE-design Frame 9FA machine you likely have some kind of contractual service agreement with GE Belfort that allows you to request information. GE Belfort has generally not always followed the philosophy of GE Greenville (USA) and have decided to re-engineer many long-standing philosophies and practices so it would be best if you require a specific answer for the 9FA to consult GE Belfort to obtain the answer they deem appropriate.

The safest immediate answer would be the tank should be full (8 tons of CO2 in an 8-ton CO2 tank?) prior to STARTing the machine to have the highest level of protection when STARTing the machine.

My experience is that GE doesn’t always publish the volumetric sizes of the compartments protected with fire extinguishing equipment so one would most likely need to know that information and be able to calculate the amount of CO2 required for quickly bringing the concentration in the compartments to a high level and then maintaining that level for a safe period of time (that was usually approximately 20 to 30 minutes) to quickly extinguish a fire and to prevent a reignition until such time as a fire-fighting crew could be deployed to site to assist with maintaining the situation the possibility of reignition was determined to be very low and it’s safe to enter the compartments to assess the situation.

Finally some areas of the world have very strict requirements and/or regulations about fire suppression systems for industrial equipment which may have figured into the sizing of the fire protection system and which may be more restrictive than the manufacturer’s or packager’s typically supplied equipment. Again, GE Belfort would probably have such information if that is the case.

 

@ABDULLAH ENGINE,

Have you read the NOTES section of Fire Protection P&ID to see if there is any indication of the suggested level there? The NOTES section of GE P&IDS is typically on the first page of system’s P&ID and is often overlooked as a source of important information.

The philosophy for the fire protection systems using a large tank was always that the tank would contain at least twice the amount required for extinguishing a fire. This would allow the unit to be re-started shortly after a CO2 discharge event and still be able to extinguish a fire if the tank couldn’t be refilled immediately after a CO2 discharge.

If the machine was built and packaged by GE Belfort you should really ask GE Belfort what their philosophy is and what their recommendation is. Since you are working on a GE-design Frame 9FA machine you likely have some kind of contractual service agreement with GE Belfort that allows you to request information. GE Belfort has generally not always followed the philosophy of GE Greenville (USA) and have decided to re-engineer many long-standing philosophies and practices so it would be best if you require a specific answer for the 9FA to consult GE Belfort to obtain the answer they deem appropriate.

The safest immediate answer would be the tank should be full (8 tons of CO2 in an 8-ton CO2 tank?) prior to STARTing the machine to have the highest level of protection when STARTing the machine.

My experience is that GE doesn’t always publish the volumetric sizes of the compartments protected with fire extinguishing equipment so one would most likely need to know that information and be able to calculate the amount of CO2 required for quickly bringing the concentration in the compartments to a high level and then maintaining that level for a safe period of time (that was usually approximately 20 to 30 minutes) to quickly extinguish a fire and to prevent a reignition until such time as a fire-fighting crew could be deployed to site to assist with maintaining the situation the possibility of reignition was determined to be very low and it’s safe to enter the compartments to assess the situation.

Finally some areas of the world have very strict requirements and/or regulations about fire suppression systems for industrial equipment which may have figured into the sizing of the fire protection system and which may be more restrictive than the manufacturer’s or packager’s typically supplied equipment. Again, GE Belfort would probably have such information if that is the case.

Yes I read the P&ID notes it's also not mention any details about the exact or minimum level.
The only information I found is a sticker on the tank stating to always keep the tank full.
In reality, it is difficult to keep the tank full throughout the year with temperature variations and relief valves.
The insurance found the level between 70-80% and asked for certified documents indicating the required level.

 

@ABDULLAH ENGINE,

I had a strong suspicion it was something very similar...!

So, if the CO2 tank is sitting in the open sun in a normally sunny and hot part of the world at the installation where you work it's entirely possible that the refrigeration compressor on the top of the tank is not working well or can't keep up with the rate of evaporation--which increases as the tank level decreases (and the surface area of the liquid increases so more evaporation occurs). It should be rare for the relief valve(s) to be venting CO2 to the atmosphere--in fact, it shouldn't really happen.

You can make a quick test if the tank is exposed to the sun during the day--create some kind of temporary shade using one or two pieces of plywood or OSB (Oriented Strand Board). Or even one or two opaque fiberglass roof panels to provide some shade. Give it a few days or a couple of weeks in the hottest time of the year to observe how it's working.

It might also be that the refrigerant in the compressor is low and/or the compressor is not working very efficiently. The refrigeration compressors are OFTEN overlooked when it comes to regular maintenance.

It could also be that the relief valve isn't working properly or is improperly adjusted.

Again, venting should not be a regular occurrence--and if it is, then there is a reason for it. It's also entirely possible that the refrigeration compressor on the CO2 tank is not properly sized (I witnessed that on two Chemtron CO2 tanks in different parts of the world). Several sites I worked at erected shades for the CO2 tanks to virtually eliminate venting by the relief valves.

Again, the typical GE heavy duty gas turbine control philosophy from the USA regarding large CO2 storage tanks was that there should be enough CO2 in the tank when it's "full" to more than adequately extinguish two fires while also maintaining a high CO2 concentration for some period of time after the fire has hopefully been extinguished. The elevated concentration of CO2 is to hopefully prevent any reignition caused by an ignition source (such as sparks or embers or hot metal) and combustible material (Lube Oil; Hydraulic Oil (which is Lube Oil); Seal Oil (which is Lube Oil); liquid fuel; gas fuel leak, etc.,for example) until such time as a firefighting group is on site to help with any possible reignition.

This philosophy allowed for a turbine to be re-STARTed after a fire OR a false detection of a fire (which happens way more often that it should) while maintaining sufficient CO2 in the event that another CO2 discharge is required or occurs before the CO2 tank can be refilled.

[I want to mention that in my 40+ year career I never witnessed a GE-designed fire protection system actually put out a real fire. More often than not, some alarms were ignored that led to a false fire detection and a subsequent release of the fire extinguishing agent. On the occasions where there were actually fires the fire protection system didn't actually sense the fires and it was outside personnel who witnessed heavy smoke concentrations from inside the protected compartments and they manually discharged CO2--often into the WRONG compartment (when there were multiple zones of detection and discharge). Also, overzealous people would run to open a compartment door to have a look inside the compartment while the fire extinguishing agent was still being discharged and the fire inside would flare up and the door would be left open--feeding air into the compartment.... There were turbine installations that ran with the compartment doors--all of them--blocked open or removed because there were so many hot gas leaks in the compartment that the compartment temperature was too high and wire insulation would melt. If there was ever a fire there's no way the fire extinguishing agent could "kill" the fire. Those sites also seemed to run with the manual isolation valves of the initial- and extended discharge CO2 piping closed (instead of open) because there had been so many false fire detections and discharges they didn't want to "waste" CO2 (or Halon back in the day). Scary--and sad--but true.]

And, again, since GE Belfort has long had responsibility for packaging GE-design Frame 9FA heavy duty gas turbines and they have a reputation for not following long-established controls philosophies and practices--they really should be the ones who provide the definitive answer to this question. I know other companies package turbines built by GE Belfort, but they usually closely follow whatever GE Belfort does or recommends. There has long been a move in GE to 'reduce cost' by any means necessary so there's that aspect to consider as well. Ask the packager of your machine(s)--which may or may not be GE Belfort.

We would be very interested to hear what you receive from GE in the way of guidance and any explanation for the CO2 tank level.

Since you will likely be sharing that information with the insurance company please share it with us if you would. Thanks in advance!

 

@ABDULLAH ENGINE,

I had a strong suspicion it was something very similar...!

So, if the CO2 tank is sitting in the open sun in a normally sunny and hot part of the world at the installation where you work it's entirely possible that the refrigeration compressor on the top of the tank is not working well or can't keep up with the rate of evaporation--which increases as the tank level decreases (and the surface area of the liquid increases so more evaporation occurs). It should be rare for the relief valve(s) to be venting CO2 to the atmosphere--in fact, it shouldn't really happen.

You can make a quick test if the tank is exposed to the sun during the day--create some kind of temporary shade using one or two pieces of plywood or OSB (Oriented Strand Board). Or even one or two opaque fiberglass roof panels to provide some shade. Give it a few days or a couple of weeks in the hottest time of the year to observe how it's working.

It might also be that the refrigerant in the compressor is low and/or the compressor is not working very efficiently. The refrigeration compressors are OFTEN overlooked when it comes to regular maintenance.

It could also be that the relief valve isn't working properly or is improperly adjusted.

Again, venting should not be a regular occurrence--and if it is, then there is a reason for it. It's also entirely possible that the refrigeration compressor on the CO2 tank is not properly sized (I witnessed that on two Chemtron CO2 tanks in different parts of the world). Several sites I worked at erected shades for the CO2 tanks to virtually eliminate venting by the relief valves.

Again, the typical GE heavy duty gas turbine control philosophy from the USA regarding large CO2 storage tanks was that there should be enough CO2 in the tank when it's "full" to more than adequately extinguish two fires while also maintaining a high CO2 concentration for some period of time after the fire has hopefully been extinguished. The elevated concentration of CO2 is to hopefully prevent any reignition caused by an ignition source (such as sparks or embers or hot metal) and combustible material (Lube Oil; Hydraulic Oil (which is Lube Oil); Seal Oil (which is Lube Oil); liquid fuel; gas fuel leak, etc.,for example) until such time as a firefighting group is on site to help with any possible reignition.

This philosophy allowed for a turbine to be re-STARTed after a fire OR a false detection of a fire (which happens way more often that it should) while maintaining sufficient CO2 in the event that another CO2 discharge is required or occurs before the CO2 tank can be refilled.

[I want to mention that in my 40+ year career I never witnessed a GE-designed fire protection system actually put out a real fire. More often than not, some alarms were ignored that led to a false fire detection and a subsequent release of the fire extinguishing agent. On the occasions where there were actually fires the fire protection system didn't actually sense the fires and it was outside personnel who witnessed heavy smoke concentrations from inside the protected compartments and they manually discharged CO2--often into the WRONG compartment (when there were multiple zones of detection and discharge). Also, overzealous people would run to open a compartment door to have a look inside the compartment while the fire extinguishing agent was still being discharged and the fire inside would flare up and the door would be left open--feeding air into the compartment.... There were turbine installations that ran with the compartment doors--all of them--blocked open or removed because there were so many hot gas leaks in the compartment that the compartment temperature was too high and wire insulation would melt. If there was ever a fire there's no way the fire extinguishing agent could "kill" the fire. Those sites also seemed to run with the manual isolation valves of the initial- and extended discharge CO2 piping closed (instead of open) because there had been so many false fire detections and discharges they didn't want to "waste" CO2 (or Halon back in the day). Scary--and sad--but true.]

And, again, since GE Belfort has long had responsibility for packaging GE-design Frame 9FA heavy duty gas turbines and they have a reputation for not following long-established controls philosophies and practices--they really should be the ones who provide the definitive answer to this question. I know other companies package turbines built by GE Belfort, but they usually closely follow whatever GE Belfort does or recommends. There has long been a move in GE to 'reduce cost' by any means necessary so there's that aspect to consider as well. Ask the packager of your machine(s)--which may or may not be GE Belfort.

We would be very interested to hear what you receive from GE in the way of guidance and any explanation for the CO2 tank level.

Since you will likely be sharing that information with the insurance company please share it with us if you would. Thanks in advance!

Thanks a lot for your great information.
Of course I will reply with any details I get.
Best regards