11-08-2011 10:19 AM
To the group:
I am modeling natural gas genset response to land-based drilling loads. To complete this accurately I need transient load response data for G3516B natural gas gensets (480 Vac, 3 phase, 1800 rpm). Detailed information is requested including block loading specifications, power loss profiles, and power recovery times. Both undershoot as well as overshoot transients are desired.
I found that SpecSizer has some of this information for diesel gensets, but none for gas gensets.
Any help on locating these data is appreciated.
11-30-2011 11:45 AM
G3516B's have been used very successfully in land drilling applications since 2004.
As I am sure you know by your question the transient response characteristics for spark ignited gensets will require some special considerations for land drilling use.
Caterpillar has released an Application and Installation guide that is available from your local dealer (publication# LEBW0005)
This document will have some more detailed information on applying spark ignited engines into your application.
Drilling duty frequently has long periods where the engines are loaded less than 50% of their rated power This can cause non-optimal combustion if low loads are maintained long term. This will likely require a ballast load to maintain load on running spark ignited engines, which can also be used to enhance the block load capabitly of the genset/load bank system.
Your direct questions on load step and response depend greatly on your rig's electrical response needs...ie....are you shooting for ISO 8528 G1, G2, or just +/- 2Hz? Your dealer can help you with getting factory support of the load cases you are studying.
12-04-2011 10:31 PM
Thank you for the information. You mentioned that a ballast load is used for G3516B natural gas gensets to boost their operating load point. So another question: What is the recommended minimum %load point for the G3516B to avoid this non-optimum combustion, for long-term operation?
12-04-2011 10:41 PM
Ryan - my question is really addressing the 50% load point. Is there a significant reduction of the harmful combustion effects if the G3516B is allowed to operate at lower load points (for example, 20% or 30% of load), compared to %50%? The question is motivated by fuel economy, since power directed to the ballast load is only generating heat.
01-13-2012 08:23 AM
The 50% load point is the minimum for prime power or continuous operation, this is not an issue for diesels as they typically dont see the low intake pressures at low loads. This low pressure can draw contaminants from the crankcase up into the combustion chamber. Although it will not destroy the engine by any means, it will create shorter overhaul lives and could impact spark plug life. If the engine is running at 0 to 30% load we would recommend a 1/2 hour time limit, at 31-50% load we would recommend a 2 hr time limit.
I understand the ineffeiciency of the ballast loads, but the environmental benefits and the fuel savings are substantial are still substantial.
Some drillers set the ballast load up to 70%, as their preference is more power being produced at any given instant and they use this to help manage transient load response.
04-11-2012 10:47 PM
If you find that a G3516B natural gas genset (480 Vac, 3 phase, 1800 rpm) will work for your application please be aware that there is a CAT rental option available (in case you didn't already know). We also have 600v options available utilizing a transformer or transformers. If you would like any information on these options please let me know. Thanks.