Denitration Device Air Bleeding Line Compressor

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Solution Overview

Problem

Existing denitration methods in gas turbine combined cycle power plants face challenges in stably supplying air for dilution to the ammonia injection grid, leading to potential clogging due to ammonium carbonate deposition, and result in energy loss from unnecessary compression and decompression of air.

Innovation Solution

A denitration device that connects an air bleeding line from the low compression portion of the compressor to the ammonia injection grid, supplying normal-temperature and low-compression air, which maintains a higher pressure than the exhaust gas duct, preventing exhaust gas inflow and eliminating the need for a separate fan, thus reducing energy loss and clogging risks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If air is compressed by the compressor and then decompressed to vaporize ammonia water, then ammonia vaporization is achieved, but energy loss occurs from unnecessary compression and decompression

Engineering Contradiction:

Improveammonia vaporization temperatureVSAvoidenergy loss from compression and decompression

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The patent applies preliminary action by bleeding air at an intermediate compression stage rather than after full compression. This allows the air to be at a suitable pressure and temperature for ammonia vaporization without requiring subsequent decompression, thereby avoiding energy loss while achieving the necessary conditions for ammonia evaporation in the denitration system.

Inventive Principle:

Principle #10Preliminary action

2Quantity of substance

If a fan is used to blow air into the ammonia injection grid, then dilution air can be supplied, but the ammonia injection grid pressure becomes lower than duct pressure causing exhaust gas inflow and ammonium carbonate deposition

Engineering Contradiction:

Improvedilution air supplyVSAvoidammonia injection grid pressure stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The system uses the compressor itself to supply dilution air through an intermediate stage bleed line, eliminating the need for a separate fan. The compressed air from the intermediate stage naturally maintains higher pressure than the duct, preventing exhaust gas inflow and ammonium carbonate deposition while providing sufficient dilution air to the ammonia injection grid.

Inventive Principle:

Principle #25Self-service

3Temperature

If high compression portion air is bled to vaporize ammonia water, then ammonia vaporization is achieved, but the compressed air energy is lost

Engineering Contradiction:

Improveair temperature for ammonia vaporizationVSAvoidcompressed air energy loss

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The patent applies local quality by selectively bleeding air from an intermediate compression stage rather than using high compression portion air. This provides air with appropriate temperature and pressure characteristics for ammonia vaporization while avoiding the excessive compression energy loss that would occur if high-stage compressed air were used.

Inventive Principle:

Principle #3Local quality

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

Stable and constant supply of dilution air prevents clogging in the ammonia injection grid, reduces energy loss by avoiding high-pressure air decompression, and simplifies control and maintenance by eliminating the need for a fan and associated peripherals.

Implementation Method 1

maintaining the pressure in the ammonia injection grid at a pressure higher than the pressure in the duct

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

an ammonia injection grid that sprays, into the duct, an ammonia mixed gas in which ammonia gas and dilution air are mixed with each other

Methodology Applied

Scientific EffectGas mixing: Diffusion

Implementation Method 3

a denitration catalyst that is installed on a downstream side of flow of the exhaust gas of the ammonia injection grid in the duct, and performs a denitration reaction between the exhaust gas and the ammonia mixed gas

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 4

an air bleeding line that is connected to a low compression portion of the compressor and supplies a low compression air bled of the compressor into the ammonia injection grid

Methodology Applied

Scientific EffectGas compression: Compression

Data Source

PatentUS11530628B2Denitration device, heat recovery steam generator having the same, gas turbine combined cycle power plant and method of denitration

Publication Date: 2022.12.20 MITSUBISHI HEAVY IND LTD

AI summary

A denitration device comprising a duct (22) that leads and distributes exhaust gas from a turbine (56) of a gas turbine (50) including a compressor (52) and the turbine (56), an ammonia injection grid (24) that sprays, into the duct (22), an mixed gas in which ammonia gas and dilution air are mixed with each other, and a denitration catalyst (26) that is installed on a downstream side of flow of the exhaust gas of the ammonia injection grid in the duct (22), and there is provided an air bleeding line (76) that is connected to a low compression portion of the compressor (52) of the gas turbine (50) and supplies air bled of the compressor (52) into the ammonia injection grid (24) as the dilution air.