Reducing the load consumed by gas turbine compressor and maximizing turbine mass flow

Abstract

The invention is applicable to industrial gas turbines to reduce the load consumed by the gas turbine compressor and to maximize the turbine mass flow.

Claims

1. A process for injecting water into the compressor of a gas turbine, comprising the steps of: injecting high pressure water into an outlet of a compressor to provide superheated outlet air, with the temperature and pressure of the outlet air of the compressor is reduced above a saturation point; wherein the high pressure water is injected by using injectors located only at air compressor last stages between stationary blades or only at last rows between stationary blades, and the high pressure nozzles are connected to a high pressure water injection system.

2. A process for injecting water into the compressor of a gas turbine, comprising the steps of: injecting high pressure water into an outlet of a compressor to provide superheated outlet air, with the temperature and pressure of the outlet air of the compressor is reduced above a saturation point; and adjusting the temperature of the injected high pressure water by using a temperature adjusting means; wherein the high pressure water is injected by using injectors located only at air compressor last stages between stationary blades or only at last rows between stationary blades, and the high pressure nozzles are connected to a high pressure water injection system.

3. The process of claim 2, wherein said injecting high pressure water comprises injecting high pressure water within a range of temperature from atmospheric temperature up to compressor outlet air saturation point temperature into said compressor outlet air.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic view of the system of the present invention including a gas turbine main parts, air compressor, combustion chamber, turbine, electrical generator, and high pressure water injection system.

DETAILED DESCRIPTION OF THE DRAWINGS

(2) FIG. 1 shows gas turbine main parts and contains, an air compressor (C), a combustion chamber (C/C), a turbine (T), a temperature adjustment means (E/H) and, a high pressure water injection system (HP Injection water).

(3) For the invention implementation the High-pressure water is introduced into the gas turbine (T). The temperature controlling device (E/H) is connected to the high pressure injection system (HP Injection water). The temperature controlling means controls the temperature of the water being injected into the compressor (C).

(4) FIG. 2 shows the water injection WI high pressure nozzles at and between the blades of the last stages or rows near the outlet of an exemplary turbine Compressor according to one embodiment of the present invention.

DESCRIPTION OF ONE SPECIFIC EXAMPLE OR EMBODIMENT OF THE INVENTION

(5) For a Gas turbine having the followings:

(6) T1: Compressor-air inlet temperature K=283 K

(7) T2: Compressor-air outlet temperature K=547 K

(8) P2: compressor air outlet pressure=12 bar

(9) T3: Gas turbine inlet temperature K=1258 K

(10) T4: Gas turbine outlet temperature K=768 K

(11) nad: adiabatic efficiency

(12) Calculation

(13) 1.sup.st: improving gas turbine efficiency by reducing energy consumed by air compressor.

(14) From steam table the following can be extracted:

(15) Water vapor at 12 bar and compressor outlet temperature of (274 C.)=547 K is in the superheated zone.

(16) Saturation Temperature=192 C.=465 K

(17) Degree of Superheat=547465=82 degree

(18) Therefore compressor air outlet temperature can be reduced by 70 degrees from 547 K to 477 K without de-superheating it.
Turbine adiabatic efficiency ad=1(T4T1)/(T3T2)(Brighton cycle)

(19) The adiabatic efficiency of the gas turbine ad=32%

(20) Table below shows the improvement in the adiabatic efficiency from 32% to 38% in relation to drop in compressor outlet temperature from 547 K to 477 K.

(21) TABLE-US-00001 T2 K 547 537 527 517 507 497 487 477 ad % 32 33 34 35 35 36 37 38

(22) 2.sup.nd: Improvement gas turbine overall efficiency by increasing turbine mass flow.

(23) From gas turbine overall thermal efficiency equation where

(24) t: Turbine thermal efficiency

(25) Wt: Work done by gas turbine=(Ma+Mf) (h3h4)

(26) Wc: Load consumed by compressor=Ma (h2h1)

(27) h: air specific heat

(28) Ma: Air mass flow rate from compressor

(29) Mf: Fuel mass

(30) Mw: Mass of high pressure water injected in compressor
t=[(WtWc)/Wt]100=1[Ma(h2h1)/Ma+Mw+Mf(h3h4)]100

(31) From the above equation it can be seen that the increase in injected water mass (Mw) will increase gas turbine overall efficiency.

(32) 3.sup.rd: Improving gas turbine overall efficiency by maximizing turbine mass flow.

(33) From fluid mixture equation
Taw=(Ma Ta+Mw Tw)/(Ma+Mw)
Therefore Mw=Ma(TaTaw)/(TawTw)

(34) Where:

(35) Taw: Required air water mixture temperature=477 K

(36) Ta: Compressor air outlet temperature=547 K

(37) Tw: Injected water temperature=288 K

(38) Mw/Ma=Water mass to air mass

(39) Therefore the required mass of high pressure water injected to reduce compressor outlet temperature from 547 K to 477 K is Mw=0.37 Ma.

(40) The below table shows the increase in injected water mass rate in relation to air mass flow rate corresponding to increase in injected water inlet temperature.

(41) TABLE-US-00002 Tw K 288 300 350 400 450 460 470 475 477 Mw/ 0.37 0.40 0.55 0.91 2.59 4.11 10 35 Infinity Ma