Bypass Fuel Flow Control for Gas Turbine Load Rejection

Solution Overview

Problem

In gas turbines, low fuel supply pressure limits the ability to maintain sufficient fuel density for pilot flames during load rejection, leading to potential misfires due to insufficient fuel supply.

Innovation Solution

A fuel supply system with a bypass flow passage and a bypass fuel flow rate adjusting valve that increases fuel density and pressure to the first nozzle, independent of the main fuel supply flow passage, allowing for controlled fuel distribution and prevention of misfires during load rejection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If fuel supply pressure is limited to low pressure according to cost requests, then cost is reduced, but fuel density becomes insufficient for maintaining pilot flames during load rejection

Engineering Contradiction:

ImprovecostVSAvoidfuel supply reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The fuel supply system is divided into two independent flow passages: a main fuel supply flow passage (L1) that includes the fuel gas heater and is used during normal operation, and a bypass flow passage (L0) that supplies fuel directly to the pilot system without passing through the heater. This segmentation allows the system to maintain sufficient fuel density for pilot flames during load rejection by using the bypass passage, while the main passage continues to operate at low pressure as required for cost reduction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bypass flow passage acts as an intermediary pathway that provides an alternative route for fuel supply to the pilot system. During load rejection, this intermediary passage enables high-density fuel to reach the pilot nozzles directly, bypassing the restrictions of the main fuel supply system that operates at low pressure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If fuel supply pressure is limited to low pressure, then cost is reduced, but the ability to rapidly increase fuel flow rate to pilot system during load rejection is compromised

Engineering Contradiction:

ImprovecostVSAvoidfuel flow rate increase speed

Core Design Contradiction:

Ease of manufactureVSSpeed

Solution Approach 1:

The fuel supply system is divided into two independent flow passages: a main fuel supply flow passage (L1) that includes the fuel gas heater and is used during normal operation, and a bypass flow passage (L0) that supplies fuel directly to the pilot system without passing through the heater. This segmentation allows the system to maintain sufficient fuel density for pilot flames during load rejection by using the bypass passage, while the main passage continues to operate at low pressure as required for cost reduction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bypass flow passage is prepared in advance and remains ready to supply high-density fuel directly to the pilot system. During load rejection, this pre-prepared pathway enables immediate fuel flow rate increase to the pilot nozzles without the delay that would occur if fuel had to be heated or pressurized through the main supply system.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If a single fuel supply flow passage is used, then device complexity is reduced, but the ability to maintain sufficient fuel density for pilot flames during load rejection is lost

Engineering Contradiction:

Improvefuel supply system complexityVSAvoidpilot flame stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The fuel supply system is divided into two independent flow passages: a main fuel supply flow passage (L1) that includes the fuel gas heater and is used during normal operation, and a bypass flow passage (L0) that supplies fuel directly to the pilot system without passing through the heater. This segmentation allows the system to maintain sufficient fuel density for pilot flames during load rejection by using the bypass passage, while the main passage continues to operate at low pressure as required for cost reduction.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system ensures a necessary amount of fuel is supplied to prevent misfires even with decreased fuel pressure, effectively stabilizing flames and maintaining operation during load rejection.

Implementation Method 1

a fuel gas heater which heats fuel of a gas turbine and supplies the fuel heated by the fuel gas heater to a first nozzle and a second nozzle

Methodology Applied

Scientific EffectHeating: Heating

Data Source

PatentUS11181047B2Fuel supply system, gas turbine, electricity generation plant, control method, and program

Publication Date: 2021.11.23 MITSUBISHI POWER LTD

AI summary

A gas turbine fuel supply system includes a fuel supply flow passage that includes a fuel gas heater which heats fuel and supplies the fuel heated by the fuel gas heater to a first nozzle and a second nozzle, a bypass flow passage that supplies the fuel to the first nozzle without passing through the fuel supply flow passage, and a bypass fuel flow rate adjusting valve that adjusts a flow rate of the fuel flowing in the bypass flow passage.