TurbineCMS

Archive for the ‘Gas Turbine’ Category

A lot of hype has been going around the gas turbine powered engines found on high-end RC toy jets. These new breed of RC toys promise to dominate the skies in the coming years since the interest on these latest radio controlled aircraft seem to be gaining ground. This is despite the fact that these particular types of toys also seemed poised to cause a huge dent in everyone’s wallet. It appears now that RC enthusiasts and hobbyists cannot seem to get enough of the new gas turbine powered engines on toy jets. So what is really all the excitement about? How do these gas turbine engines on RC toy jets work anyway?

For several decades, men have been fascinated by RC toy planes and helicopters. They love to watch it lift off the ground, play tricks in the air, and perform a perfect landing. Most of RC toy planes in the past are propeller driven because they are seen to be the most practical approach to make the plane fly. So it would be not surprising back then if you see a scaled down model of a jet fighter with a propeller on its nose tip. This went on for a long time until July 30, 1988, the first flight of an toy jet running on micro-turbojet engines was made with considerable success. From then on, micro-turbojets underwent a series of evolutions and finally, the modern gas turbine engines, which are being mounted on RC toy jets that you now see, emerged.

Gas turbine engines on RC toy jets work in a manner similar to that of real jet turbine engines. There are three divisions on the gas turbine engines and these are the compressor, the combustion chamber, and the turbine. The compressor is responsible for sucking incoming air and compressing them inside the cylindrical shroud. Extreme compression results in the heating up of air which then makes its way down into the combustion chamber where a fine spray of fuel, along with a glow plug, will be introduced in the area.

Just as expected, the fuel, mixed with hot compressed air and lit by a glow plug, will explode, forcing the exhaust gases out through the turbine and the small nozzle found at the rear of the jet turbine. This chain reaction produces the enormous thrust that enables the RC toy jet to take off and fly. Since the turbine and the compressor are linked by a common shaft, the expelled gas which turns the turbine is also the one that drives the compressor. This is why the gas turbines must be powered at the outset by an external source until the air inside the combustion chamber is sufficient and adequately heated.

So you see, gas turbine engines on RC toy jets work just like their real and full scale counterparts. It might just differ in size but the principle on how they work is basically the same.

Gas turbines are more popular in Nigeria when compared to Hydro, Coal and steam-driven turbines, due to the abundance gas reservoir in Nigeria and coupled with the fact that they are easier to maintain when compared to other turbines. One of the major challenge facing these power plants in Nigeria however, is that of high ambient temperature which can go up to as high as 38 degree Celsius

The challenge of high ambient temperature to a developing country like Nigeria therefore is to identify areas of potential losses and minimize them. It is also essential to harness her strengths to ensure that the efficiency of the entire plant is improved.

With regards to Generation mix, we presently have Steam, Gas and Hydro turbines in Nigeria. Each of these plants runs efficiently at different periods in the year. For example Hydro stations run few of their units in the month of February, March and April, while all Hydro turbines are completely shut down during the months of June/July when the water level is so low. It is therefore recommended that:

All available units are kept on spinning reserve during hot periods of the year when the ambient temperature is high, and when needed at such periods, not all the units should be put on the grid, to avoid loss in power output due to the effect of high ambient temperature on the machine It is recommended that single Gas turbine power plants be integrated into to achieve a Combined Cycle system. This will increase the Thermal efficiency of the turbines by utilizing the waste heat of the Gas turbine to operate an absorption refrigeration unit to cool the gas turbine inlet air. Combined cycles have a higher thermal efficiency than the gas turbine cycles operating alone For the effective utilization of these power plants, it is recommended that Annual maintenance of the machines be scheduled within the periods when ambient temperature is on the high side Future plans by the Federal Government and Independent Power Producers in constructing Gas Turbines should include exhaustive feasibility studies of the ambient temperature of the location where the Gas turbine will be sited. This will greatly increase their efficiency, Net Power Output and life-span Modifications can be made on the air intake system to enable it compensate for decreased air density by increasing air velocity and ensuring that the amount of oxygen required to burn the quantity of Gas necessary for peak operation is made available At high ambient temperature between 36 and 37°C, cold de-mineralization water spray can be introduced into the air duct to reduce the ambient temperature to about 30°C so as to enable the Gas turbine achieve higher load capacity

The need to provide stable power supply is a major priority of any Government. To ensure that this objective is fully implemented, there is need to ensure that power plants are adequately maintained. I would be sharing some maintenance tips for Gas turbine Machines in this article.

The term maintenance has to do with the services rendered to ensure that a machine does not go out of service due to one fault or the other. The essence of carrying out maintenance on a machine is to ensure that it performs at the optimum.

In a Gas turbine power plant, each department has a role to play in maintenance process.

It is the duty of the operator to detect a fault in a machine and write a defect to the maintenance department who will in turn carry out a preliminary check before working on the faulty equipment. A defect report is normally written to the Plant Maintenance department. Below are five forms of maintenance normally carried out in a Gas Turbine Machine:

Daily Routine Checks
There are six major department involved in maintenance process in the power plant. These are: Operations, Electrical, Mechanical, Instrumentation and Control, Protection Control and Metering and Environmental Health and Safety. Personals in these departments normally carry out daily routine checks on all major plant items. The essence is to ensure that the plant items are working accurately. The present readings of the auxiliary items are checked with previous reading to ensure accuracy. Early detection of faults on equipment is a major key to preventing damage. Daily routine is thus a form of preventive maintenance technique.

Bi-Annual Plant Maintenance
Each unit of the Gas turbine is normally shut down twice in a year to carry out maintenance on major parts of the turbine. The parts that are critical in this maintenance include: The air intake system, the transformer system, the generator, the combustion chamber, the lube oil system and the compressor/turbine blades. The Bi-Annual inspection normally has 21 days duration with each department undertaking their own separate task. This is a form of planned outage.

Minor Inspection
The Gas turbine is normally shut down after making 8000 operating hours, for the purpose of carrying out minor inspection on major parts of the turbine. The inspection comprises of entry into the accessible regions of the machine and it involves a largely visual inspection.

Hot Gas Path Inspection (HGPI)
After carrying out a minor inspection on the machine, the machine is again due for Hot Gas Path Inspection when it attains 25000 operating hours. This inspection is restricted to the hot gas path items including the combustion chamber and the compressor blade region, which is not opened during the inspection process. Inspection of stationary blades is carried out and replacement is made on any defective item discovered.

Major Inspection
This is the most extensive type of maintenance carried out on the machine after it has attained 50000 running hours. This inspection includes extensive dismantling of the machine, detailed visual inspection as well as repair measure based on condition of the plant item.