A PROCESS TO MINIMIZING NITROGEN OXIDES EMITTION FROM GAS TURBINE EXHAUST DUCT APPLICATIONS AND MAXIMIZING GAS TURBINE EFFICIENCY

Abstract

The inventions applicable to industrial gas turbines at power plant to minimize nitrogen oxides from gas turbine exhaust and maximizing gas turbine efficiency done by replacing the standard air filter system by oxygen filtration system (O) to allow oxygen only and substituting the nitrogen by high-pressure water HPW injected in compressor (C) last stages only. The one unit of oxygen to be injected by 4 units of HPW, since air contains 5 units 4 units of nitrogen and 1 unit of oxygen, the 5 units of oxygen are to be injected by 20 units of HPW required for the process. A heat exchanger to be installed at gas turbine exhaust duct to heat the HPW injected into compressor (C) last stages, which is to be mixed with HPW at ambient/atmospheric temperature to cool compressor air outlet temperature to targeted temperature as shown in FIG. 1. A control system is essential to control the process.

Claims

1. The process wherein the normal air filtration system is replaced by oxygen filtration system to admit oxygen only into the gas turbine, Wherein the oxygen filter system capacity has equivalent or higher capacity to the replaced normal air filtration system and to fulfil compressor requirement capacity.

2. The process of claim 1, wherein said normal air filtration system is replaced by oxygen filtration system to admit oxygen only into the gas turbine, Wherein the atmospheric 4 units of rejected/expelled nitrogen are compensated by high pressure water injected only into the compressor last stationary/stator stationary blades, Wherein compressor outlet oxygen/high pressure mixture temperature to reduce to targeted temperature to provide superheated outlet mixture, with temperature and pressure of compressor outlet air reduced above saturation point.

3. The process of claim 2, wherein said normal air filtration system is replaced by oxygen filtration system to admit oxygen only into the gas turbine, Wherein the atmospheric 4 units of rejected/expelled nitrogen are compensated by high pressure water injected only into the compressor last stationary/stator stationary blades, Wherein the injected high pressure water can be injected at atmospheric temperature and/or raised within a range of temperature from atmospheric temperature up to compressor outlet air saturation point temperature. Wherein compressor outlet oxygen/high pressure mixture temperature to reduce to targeted temperature to provide superheated outlet air, with temperature and pressure of compressor outlet air reduced above air saturation point.

4. The process of claim 3, Wherein the atmospheric 4 units of rejected/expelled nitrogen are compensated by high pressure water injected only into the compressor last stationary/stator stationary blades, Wherein the high pressure water is injected by using injectors located only at compressor last stages between stationary blades, and the high pressure nozzles are connected to a high pressure water injecting system. Wherein compressor outlet oxygen/high pressure mixture temperature to reduce to targeted temperature to provide superheated outlet mixture, with temperature and pressure of compressor outlet air reduced above air saturation point.

5. The process of claim 4, wherein the process for injecting high pressure water into the compressor of a gas turbine: Wherein the injecting high pressure water is injected into only compressor last stages to reduce its outlet temperature to the targeted temperature to provide superheated outlet oxygen/high pressure mixture, with temperature and pressure of compressor outlet mixture reduced above saturation point. Wherein the high pressure water is injected by using injectors located only at compressor last stages between stationary blades, and the high pressure nozzles are connected to a high pressure water injecting system.

6. The process of claim 5, wherein the process for injecting high pressure water into the compressor of a gas turbine, Wherein the heated high pressure water is controlled by control valve and mixed with high pressure water at ambient temperature and controlled by control valve. Wherein the high pressure water is injected by using injectors located only at compressor last stages between stationary/stator blades, and the high pressure nozzles are connected to a high pressure water injecting system.

7. The process of claim 1, where the normal air filtration system is replaced by oxygen filtration system to admit oxygen only into the gas turbine and the oxygen filter system capacity has equivalent or higher capacity to the replaced normal air filtration system and to fulfil compressor requirement capacity, Wherein the 5 units of oxygen at the said compressor are injected by 20 units or higher of high pressure water injected only into the compressor last stationary/stator stationary blades, Wherein compressor outlet oxygen/high pressure mixture at compressor outlet to reduce the oxygen/high pressure mixture temperature to targeted temperature to provide superheated outlet mixture with temperature and pressure reduced above air saturation point.

8. The process in claim 1, wherein the normal air filtration system is replaced by oxygen filtration system to admit oxygen only into the gas turbine, Wherein the oxygen filter system capacity has equivalent or higher capacity to the replaced normal air filtration system and to fulfil compressor requirement capacity. Wherein the huge amount can be injected into compressor last stages since the superheated oxygen/high pressure mixture at compressor outlet is superheated and if injected by high-pressure water at compressor outlet air saturation temperature can be raised to infinity with no risk of blade pitting or erosion.

9. The process in claim 1, 2, 3, 4, 5, 6 and 7 wherein the overall process is controlled by a control system.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0078] FIG. 1 Represents invention diagram to minimize Nitrogen oxides emitted from gas turbine applications and maximizing gas turbine efficiency, showing Oxygen Filter system (OF), gas turbine Compressor (C), Combustion Chamber (CC), Turbine (T), Heat Exchanger (H), Control Valves (V) and High Pressure Water Injuction system (HPWI).

[0079] FIG. 2 showing the location of HPW injectors (I) within Compressor last stages.

DETAILED DESCRIPTION

[0080] The objective to be fulfill by the invention is to minimizing nitrogen oxides emitted from gas turbine applications and maximizing gas turbine overall efficiency continuously.

[0081] In gas turbine applications huge amount of air consumed, where atmospheric air is a composite of nitrogen and oxygen in the ratio of about 4:1. Therefore, 4 units of nitrogen is to be replaced by injected high-pressure water.

[0082] The normal air intake filter to be replaced by Oxygen filters (OF) to allow only oxygen into the gas turbine. The surface area of OF is to be capable to allow 5 units of oxygen alone to fulfill the compressor capacity.

[0083] As 4 units of HPW mass required to replace each one unit of oxygen drawn by the compressor to replace the expelled units of atmospheric nitrogen. Therefore, minimum 20 units of HPW required to mix with the 5 units of oxygen drawn by the compressor to ensure good combustion at combustor.

[0084] The HPW injection system using high pressure injectors/nozzles is to be capable to supply the required mass of HPW for the operation.

[0085] Compressor stationary blade carrier and compressor casing to be modified to incorporate HPW system and injectors.

[0086] Number of high-pressure injectors required to be calculated and installed between compressor stationary last stages blades as shown in FIG. 2.

[0087] The expelled nitrogen is to be substituted by HPW injected into compressor last stationary/stator blades and can be injected at ambient/atmospheric temperature to reduce compressor air outlet temperature to COTT to reduce the load consumed by the compressor and enhance gas turbine efficiency.

[0088] The HPW temperature is to raised ranging from atmospheric/ambient temperature up to COTT and injected into compressor last stages to reduce the load consumed by the compressor and maximize gas turbine efficiency.

[0089] In all cases the purpose of injecting HPW into the compressor to reduce compressor outlet superheated oxygen/high pressure water mixture to COTT above compressor outlet air saturation point.

[0090] A heat exchanger to be installed at gas turbine exhaust duct as shown in FIG. 1. to heat HPW fed into the compressor through control valve.

[0091] The heated HPW is to be mixed with HPW at ambient/atmospheric temperature through control valve. The mixed HPW is injected into compressor last stationary blades only to reduce compressor oxygen/high pressure mixture outlet temperature to CAOTT and maximize gas turbine efficiency.

[0092] A controlling system to control the process is to be adopted to control HPW temperature and mass injected into compressor outlet air at last stationary blades, COTT, and gas turbine overall efficiency.

[0093] Since specific volume of water is 1.5542 of Nitrogen specific volume, then the required HPW flow rate of 20/1.5542=12.8683 unit/min of injected high-pressure water. From table 1 this can be met if the injected high-pressure water temperature between 470° K and 475° K for the invention example.

[0094] The mass of injected HPW can be increased to attain best gas turbine efficiency.

General Notes.

[0095] As different turbines have different compressor, for each compressor the following guidelines can apply: — [0096] 1—From compressor outlet air pressure and temperature degree of superheat and air saturation point can be derived from steam table or any other means. [0097] 2—Target compressor aft outlet temperature COTT to be established above saturation point to avoid blade erosion. [0098] 3—Mass of HPW injected to lower compressor outlet air temperature targeted temperature to be calculated. [0099] 4—Number of high-pressure injectors required to lower compressor outlet aft temperature to targeted temperature to be calculated. [0100] 5—Compressor last stage blade carrier to be modified to allocate the high-pressure injectors and pipework and related control apparatuses. [0101] 6—Compressor outer casing modification to facilitate for high-pressure water injection pipework. [0102] 7—A heat exchanger to be installed at gas turbine exhaust duct to heat the HPW. [0103] 8—Compressor aft outlet temperature safety factor is decided for the process. For the above example it is 12° K. [0104] 9—Water injection rate required is to reduce compressor outlet temperature to Compressor Targeted Outlet Temperature and to be calculated and applied continuously. [0105] 10—Water injection rate required is to reduce compressor outlet temperature to Compressor Targeted Outlet Temperature and to be applied continuously.