Use of OptiBlendTM system gave customers a solution to reduce per unit electricity costs by displacing diesel with other alternate fuels available at site.
Eden Energy India Pvt. Ltd. is a multinational company based in Ahmedabad, Gujarat, India. Their parent organization is M/s Eden Energy Ltd., based in Perth, Australia and they have a sister concern company in Denver, Colorado, USA, namely Hythane Company LLC.
Eden´s OptiBlendTM system (OB Kit) is a dual fuel, or sometimes referred to as bi-fuel, retrofit kit. The principal operation of the technology is to burn natural gas or any other alternative fuel gas in place of diesel, taking advantage of the high differential pricing between natural gas or any other alternative fuel available at site w.r.t diesel fuel.
The natural gas, primarily methane, is simply pipeline gas provided by the local gas distribution company. Alternative fuels include renewable biogas from landfills, digesters and waste water treatment facilities, as well as syngas made from sawdust, wood chips or similar carbon-neutral agricultural waste in gasification equipment. Both the diesel and fuel gas are burned simultaneously to create the same amount of power as originally achieved with 100 per cent diesel.
The logistics of the system
The modification to the existing diesel generator can be accomplished in one to two days. The natural gas is fumigated into the engine through a custom-designed air/gas mixer mounted between the air intake cleaner and turbocharger. This allows the natural gas to mix completely with the intake air before the combustion chamber. As in any diesel engine, the cylinder compression and diesel injection create the initial combustion, which also ignites the pre-mixed natural gas. While operating with natural gas, the engine is quieter and has less vibration. The natural gas combustion provides a more complete and homogeneous burn, leading to lower oil contamination and longer engine maintenance schedules.
In order to achieve the maximum reduction in diesel fuel usage, and to maintain the safety and durability of the engine, constant control of the inlet gas is necessary. This is accomplished through a PLC controller and a dynamic air/fuel ratio throttle, which optimises gas flows at all load points.The PLC monitors numerous engine par The PLC monitors numerous engine parameters to determine the optimum air/fuel ratio for the engine. Among the signals being watched by the PLC are engine vibration, exhaust gas temperature, electrical frequency and electrical load. Since the PLC has a reaction time in the tune of milliseconds and the air/fuel throttle valve can completely open or close in 30 milliseconds, the system is able to respond immediately to changing demands and conditions.
This fast reaction time allows the engine to deliver the same performance as it would if it were running on 100 per cent diesel fuel. There is no loss of engine power when running on dual fuel.
Another benefit of this system is that there are no modifications made to the OEM controller. By not altering the controller, it allows the generator set to instantly return to 100 per cent diesel operation if there is an interruption in natural gas supply or other system fault.
If any unusual situation causes a parameter to go out of the calibrated range, such as a high exhaust temperature, the air/fuel throttle will reduce the gas delivery to the engine until conditions return to normal.
No operator supervision or system reset is necessary, unless the fault condition persists and causes the system to revert to 100 per cent diesel and completely shutoff the gas supply. The OptiBlend system automatically maximises the displacement of diesel with gas at any operating condition while still protecting the engine during unexpected circumstances.
In November 2009, Mcleod Russel India Ltd. installed their first OB Kit on a 320 kVA Caterpillar 3406B model at their Bogapani Tea Estate. The system was able to reduce the diesel usage up to 70 per cent in the load range between 60-80 per cent. Across the normal range of plant operations, Mcleod Russel India Ltd. is averaging a 70 per cent reduction in diesel usage, which translates into a 60 per cent reduction in power costs (considering fuel prices of November 2009 i.e. Diesel price INR 40/ltr. and natural gas price INR 6/M3). Apart from this, OB kit was also installed in other tea estates of Mcleod Russel India Ltd namely Mahakali and Phillobari Tea Estates having same engine ratings and model i.e. 320 KVA and MWM TBD2 V12 engine.
In January 2011, Escorts Limited installed their first OB Kit on a 1010 kVA Cummins KTA 3067 model at their Faridabad unit. The system was able to reduce the diesel usage by up to 65 per cent in the middle of the electrical load range (load between 60-85 per cent). This translates into a 20 per cent reduction in power costs and save INR 29, 09, 485/- on their fuel cost during their first year of operations considering diesel price of INR 34/ltr (for bulk user of diesel) and natural gas price INR 21/M3 (in Jan´11).
Based on the successful performance of the first OB kit installation, Escort Ltd. had given three more repeat orders, all of which got installed before March 2012 on 1010 kVA rated Cummins KTA 3067G model in Escorts Ltd, Faridabad plant, India.
Similarly in July 2013, Parle Biscuits Pvt. Ltd. installed OB kit on a 1250 kVA Cummins KTA 50 G3 model at their Neemrana plant. The system was able to reduce the diesel usage by up to 50 per cent in the middle of the electrical load range (load between 50-80 per cent). In October 2013 Parle Biscuits Pvt. Ltd. have faced power problem due to transformer failure near their plant. During this failure, they ran their DG set for 24 hrs/ day for almost a week´s period. Considering fuel prices of diesel INR 57/ltr and natural gas price INR 32/M3 (in Oct´13) this translates into a 20 per cent reduction in power costs and they save INR 3,69,550.00 on their fuel cost during this one week period itself. This kit is generically designed to work on different OEM models worldwide and it's been appreciated for its performance and reliability all over the world. We have installations in many continents including Asia, Europe and the USA, running without any issues for thousands of hours till date.
´These systems have been very beneficial because these systems allowed customer to reduce their operating cost without affecting engine rating, maintaining engine power equivalent to 100 per cent diesel operation,´ says Manish H. Dixit, President, Eden Energy India Pvt. Ltd.
Dual fuel vs. Natural gas gensets
Since the capital cost of dual fuel kits are negligible compared to the natural gas genset, it is more advisable to use existing DG set with dual fuel kit rather than to buy a new gas genset. As compared to a diesel generator set, a dedicated natural gas genset is approximately 200-300 per cent more expensive and requires a significantly larger footprint area for its operations. Additionally the dual fuel system maintains the original DG set´s power capacity in the event of failure of required natural gas supplies &/or natural gas line pressure drops.
In regards to the installation time, since removing the diesel system and installing a dedicated natural gas system would have been very time consuming, the OB system can be in-stalled over a weekend and therefore does not affect the plant production schedule.
Dedicated natural gas gensets create dependence on a single fuel, leaving the operator without power if the natural gas supply is lost or the line pressure drops beyond the threshold values. Using a dual fuel system provides the security of having power in case the gas supplies fails as it can revert back to the diesel fuel stored onsite and instantly switches to 100 per cent diesel operations to get the required power. Thus, allows the operator to take advantage of the cost savings by using natural gas when it is available without compromising to its power requirements. Dedicated natural gas gensets require skilled labor for its operation, but in case of running the existing DG set with a dual fuel kit, the same unskilled labor will run the DG set, as the OB kit optimizes gas flow automatically thro´ the PLC system for safe operations (a fit-and-forget type configuration).
There is also a large environmental benefit to the project. The key emissions created from a diesel generator set, NOx and particulate matter (PM), are reduced by up to 50 per cent when running in dual fuel mode. NOx is one of the main components in the formation of smog, making this a critical pollutant to reduce. The CO2 in the engine exhaust, a greenhouse gas associated with climate change concerns, is also reduced by about 10 per cent, which is another welcome benefit to the environment at no extra cost.
Heavy duty OptiBlendTM System
Engine performance is especially crucial in the oilfields because of the large variances in load demand, as well as the critically of continuous drilling and pumping. Given the large revenue generated by these companies, high reliability and superior performance are essential from the drilling and pumping equipment. These requirements make oilfield drilling and hydraulic fracking an excellent application for the Heavy duty OptiBlendTM units, which are designed to withstand extremes of climatic conditions (temperatures) and large engine vibrations.
(This article has been authored by Manish H Dixit, President, Eden Energy India Pvt. Ltd).