A New Gas Turbine Cycle for Economical Power Boosting

Abstract

A Moisture Air Turbine (MAT) cycle is proposed for improving the characteristics of land based gas turbine by injecting atomized water at inlet to compressor. The power boosting mechanism of MAT is understood as composits of those of following existing systems: inlet air cooling system, inter-cooling and steam injection. Experiments using a 15MW class axial flow load compressor have been carried out to reveal that water evaporation in compressor could reduce compressor work in an efficient manner. Moreover, this technology has been demonstrated by means of 130MW class simple cycle gas turbine power plant to show that a small amount of water consumption is sufficient to increase power output. Very efficient evaporation could be achieved provided the size of water droplet is controlled properly. The amount of water consumption is much less than that of conventional inlet air cooling system with cooling tower for heat rejection. Incorporating water droplet evaporation profile into consideration, realistic cycle calculation model has been developed to predict power output with water injection. It has been shown that this technology is economically achievable. It should be stressed that contrary to well known evaporative cooler, MAT cycle could provide power output at a desired value within its capability regardless of ambient humidity condition.

Evaluation of water injection effect on compressor and engine performance and operability

“…Twin spool with power turbine RR Olympus performance boost by Utamura et al [16]. Wet compression allows the continuous evaporation during compression thus thermodynamically the compression is approaching the isothermal one resulting to a significant reduction of compressor specific work [19].…”

“…Utamura et al [16] have reported a gain on thermal efficiency equal to 1.84% and on power equal to 8% for high humidity conditions and water injection of 0.65% mass flow fraction. The effect of 1% overspray on the performance of the Tornado engine calculated by the model is shown in Fig.…”

“…The level of spraying technology at the time along with the fact that other techniques were used for the engine performance augmentation resulted in abandoning the wet compression idea. Wet compression was proposed again in 1997 by Utamura et al [16] by presenting measurements from a 130 MW engine. The results indicated that overspray can produce a significant gain on both power and engine efficiency.…”

Aero engine compressor cooling by water injection - Part 1: Evaporative compressor model

“…Deliberate compressor water injection, however, is substantially different. The most important difference is that for this approach, atomised droplets of typically small diameters (5-10m) are injected into the engine and have been observed to follow the flow path [8][9][10][11]. These droplets usually begin to evaporate in the initial/front stages of the compressor that brings about the cooling of the air flow (drop in temperature), increased density and moisture content.…”

“…These droplets usually begin to evaporate in the initial/front stages of the compressor that brings about the cooling of the air flow (drop in temperature), increased density and moisture content. This procedure has been studied extensively through compressor analytical methods [11][12][13][14], through-flow approach, CFD approach [8,[15][16][17][18], and experimental investigations [9,[19][20][21] that have mostly focused on stationary gas turbines. For the analytical methods, Kim et al [22] categorise the models into: natural convection model, diffusion model and Stokes model.…”