Study of thermodynamic performance of an integrated gasification combined cycle power plant

Author(s):  
P K Nag ◽  
S De

Computational analysis is performed to investigate the effects of the pressure ratio of the gas cycle (Rp) and the temperature ratio across the combustion chamber (RT) on the thermodynamic performance of an integrated gasification combined cycle (IGCC) power plant with single pressure power generation for both the gas and steam cycles. The gases are assumed to be real ones that follow the Redlich-Kwong equation of state. The overall efficiency of the cycle (η) is found to be maximum at an optimum pressure ratio of the gas cycle for a given temperature ratio. The second law analysis indicates that maximum exergy is destroyed in the process of gasification and is not at all affected by the temperature ratio, while the effect of the pressure ratio on it is also not very significant. The exergy loss in the combustor is found to decrease with an increase in either of the ratios. For the heat recovery steam generator (HRSG), it increases with a higher temperature ratio and decreases with a higher pressure ratio. The total exergy loss of the cycle is found to decrease with either of these two ratios while the other is held constant.

Author(s):  
S De ◽  
P K Nag

The effect of supplementary firing on the performance of an integrated gasification combined cycle (IGCC) power plant is studied. The results are presented with respect to a simple ‘unfired’ IGCC power plant with single pressure power generation for both the gas and the steam cycles as reference. The gases are assumed as real with variable specific heats. It is found that the most favourable benefit of supplementary firing can be obtained for a low temperature ratio R T only. For higher R T, only a gain in work output is possible with a reverse effect on the overall efficiency of the plant. The second law analysis reveals that the exergy loss in the heat-recovery steam generator is most significant as the amount of supplementary firing increases. It is also noteworthy that, although the total exergy loss of the plant decreases with higher supplementary firing for a low R T (= 3.0), the reverse is the case for a higher R T (= 6.0).


2021 ◽  
Author(s):  
Silvia Ravelli

Abstract This study takes inspiration from a previous work focused on the simulations of the Willem-Alexander Centrale (WAC) power plant located in Buggenum (the Netherlands), based on integrated gasification combined cycle (IGCC) technology, under both design and off-design conditions. These latter included co-gasification of coal and biomass, in proportions of 30:70, in three different fuel mixtures. Any drop in the energy content of the coal/biomass blend, with respect to 100% coal, translated into a reduction in gas turbine (GT) firing temperature and load, according to the guidelines of WAC testing. Since the model was found to be accurate in comparison with operational data, here attention is drawn to the GT behavior. Hence part load strategies, such as fuel-only turbine inlet temperature (TIT) control and inlet guide vane (IGV) control, were investigated with the aim of maximizing the net electric efficiency (ηel) of the whole plant. This was done for different GT models from leading manufactures on a comparable size, in the range between 190–200 MW. The influence of fuel quality on overall ηel was discussed for three binary blends, over a wide range of lower heating value (LHV), while ensuring a concentration of H2 in the syngas below the limit of 30 vol%. IGV control was found to deliver the highest IGCC ηel combined with the lowest CO2 emission intensity, when compared not only to TIT control but also to turbine exhaust temperature control, which matches the spec for the selected GT engine. Thermoflex® was used to compute mass and energy balances in a steady environment thus neglecting dynamic aspects.


Author(s):  
M. Nakhamkin ◽  
M. Patel ◽  
L. Andersson ◽  
P. Abitante ◽  
A. Cohn

This paper presents the results of a project targeted at developing cost effective power plant concept with integrated Coal Gasification System (CGS) and with Compressed Air Energy Storage (CAES) plant. The developed concepts, denoted as CGS/CAES, provide for continuous operation of CGS and the reheat turboexpander train which are high temperature components, thus improving their operation and extending life resource. A parametric thermodynamic analysis is performed for several CGS/CAES concepts differentiated by their turbomachinery parameters, CGS arrangements, operating cycles, and hours of daily generation. A qualitative cost estimate is made using a variety of sources including published EPRI reports and extensive in-house cost data. A technical and cost comparison is made to the Integrated Gasification Combined Cycle (IGCC) plant.


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