An OGCT or open cycle gas turbine is a combustive plant. To rotate the generator and produce electricity, it’s fired up with natural gas. In this era of natural gas’s immense popularity as a power resource, the gas turbine service companies are facing high demands for both CCGT, i.e. Combined Cycle Gas Turbine and OCGT. However, OCGT’s mechanism is much simpler than CCGT’s. With the help of a compressor, it can generate power from the fresh air. To note, the adiabatic compression process notices enthalpy losses during internal friction. Yet, the compression efficiency can increase to 85% approximately.
Therefore, as a plant owner, one would have to make intelligent technological choices while choosing an efficient power inventor. To select one between these two gas turbines, some factors are important to consider. These factors are environmental effect, efficiency, and economy. If we consider efficiency, CCGT is much more efficient and environment friendly. However, if we consider economy or cost-effectiveness, the cost of setting up OCGT is much lower.
Therefore, choosing between these two can be a bit tricky. Because you may have to consider the logistics, demand profile, fuel efficiency, etc. as well. Following are some conditions when open cycle gas turbines would be the appropriate system to install for producing energy.
1. OCGT is best for peaking power
While choosing a power generating system, it’s very important to consider what type of power generation you require. For example, if the turbine is being utilized for peaking power, then OCGT is the better option because the start-up time of OCGT is much lower than that of CCGT.
This is the reason why the energy and climate change departments of various states and countries are giving legalization for installing the open cycle gas turbine for generating backup electricity in regions where a speedy response is required. Statistically, the OCGT machines do not have an isentropic turbine or expander; yet, it can reach around 90% efficiency rate during operation.
OCGT functions in a way which ensures that the temperature of the peak power demand remains within expectation. Therefore, OGCT serves to provide security for several electric grids that often face their integrity problems.
2. OCGT does operate mainly on atmospheric pressure
The functionality of OCGT is not dependent on atmospheric pressure. Hence, you may choose any type of energy to improve the output quantity as well as quality. Moreover, once any kind of pressure is applied to OCGT, the size of various components used for power generation can decrease.
3. If capturing waste heat is not your priority
If you do not require a combustion plant that consists of a heat-generating system, then OCGT would be a great option. The turbines that generally consist of such a system are capable of capturing the additional heat from the exhaust that goes to wastage.
This captured heat is then used in HRSG or Heat Recovery Steam Generator to produce steam. Then this steam is passed to the steam turbine. Using this steam turbine, the power plant produces additional electricity.
However, when there is no requirement for the production of such additional heat for the plant, OCGT is best to install. This is acceptable and effective instead of capturing wasted heat, OCGT rejects the heat and emits it back to the environment. Hence, if the power plant does not require additional power generation to uplift the total power output, you must select OCGT.
4. Low Thermal Stresses
As OCGT can control the extreme temperature of the system, the number of thermal stresses is lower than any other gas turbine system. Moreover, the overall temperature of the system remains stabilized.
5. Least space is required
For selecting a gas turbine for your power plant, various project parameters must be considered. One of the major among them is the availability of space.
Most of the gas turbine systems using CCGT require a huge space as, along with the main steam turbine system, they have an additional system to recover the wasted heat. Therefore, the entire system becomes very heavy, and huge space is required to install them.
But, in the case of OCGT, it does not consist of any additional system to recover the wasted heat. As a result, its weight is much lighter than any other gas turbine system. Besides, a small place is enough for installing it. Therefore, you don’t have to think about placing additional equipment, and you can save your precious time.
From the above discussion, it’s quite evident that the selection and installation of an open cycle gas system are entirely dependent on plant utilization. Therefore, you would have to choose whether you want to spend a fixed or marginal cost. To install OCGT, marginal cost is required because OCGTs are generally installed in those plants which utilize it for a short period.
In that case, the very high efficiency of the turbine plant is not necessary, and you can surely choose this cost-effective option. Also, by choosing OCGT, you would be confirmed that the money you had invested for the installation would get recovered within the lifetime of this turbine.