The CFB boiler demonstration project with low NOx technology · Under this new Emission standard, CFB boilers are also faced with the challenge. The NOx emission of most CFB boiler

工程热物理研究所 Institute of Engineering

中国科学院 Chinese Academy of Sciences

The CFB boiler demonstration project with low NOx technology

ZHOU TUO

Institute of Engineering Thermophysics, CAS

68th IEA –FBC meeting



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Content

1. Background 2. CFB Pilot Plant 2.1 Introduction of pilot plant 2.2 SNCR and Semi-Dry FGD system 2.3 Experimental Results 3. Industrial Demonstration Boiler 3.1 Introduction of Boiler 3.2 Design of SNCR system 3.3 Field testing Results 4. summary



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Background

The number of NOx emission in China is large, the majority is from coal-fired power plants. For limit value of NOx emission conc., the new emission standard of nation atmosphere pollutant is 100 mg/Nm3 Under this new Emission standard, CFB boilers are also faced with the challenge.

The NOx emission of most CFB boiler is about 200~300mg/m3 Decrease the NOx initial emission by optimizing boiler design; Using such a cost effective DeNOx solution.



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Control NOx Emission

Combustion Optimization

Bed Temperature

Excess Air

Secondary Air

SNCR

Temparature

Reagent Distribution

Residence Time

Boiler Design

DeNOx System

Control NOx initial generation

Using DeNOx system(SNCR)

Control initial NOx emission by optimizing boiler design

SNCR is a DeNOx technology fit for CFB boliers

Background



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Introduction of pilot plant

CFB pilot plant

Thermal power: 2MW

Furnace height: 15m

Two cyclones and EHE(symmetric)

Four levels of Secondary Air

Fuel: Coal or Semicoke (300kg/h)

Dry/Semi-Dry DeSO2 system

DeNOx system (SNCR)



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SNCR and Semi-Dry FGD system

To FGD reactor

To cyclone inlet

Solution Tank

Water Injection Pumps Reagent

Injection Pumps PLC system

Delivery Pump

SNCR and Semi-Dry FGD

CFB Pilot Plant



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Experimental Results

CFB Pilot Plant

Control NOx below 150mg(Lower bed temperature, increasing secondary Air ratio and height ). DeNOx efficiency 70% under NSR=1.8, reagent utilization rate about 50% under NSR=1

NOx initial emission

DeNOx efficiency Reagent utilization rate

NH3 slip

DeNOx efficiency

NH3 slip



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Demonstration Boiler

No. Item Unit Value

1 Steam Flow t/h 300

2 Steam Pressure Mpa 13.7

3 Steam Tem ℃ 540

4 Feed water Tem ℃ 225

5 Exhaust Tem ℃ 139

6 Boiler heat efficiency % 91.1

7 Fuel consumption t/h 47.5

8 Manufacturer / WUXI HUAGUANG BOILER CO.,LTD

9 Location / Dalian, Liaoning Province

Introduction of Boiler



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Item Datong bitumite

(Design Coal )

Neimeng lignite

(Common Coal)

Cad 60.55% 42.52% Had 3.36% 2.86% Oad 8.96% 8.64% Nad 0.99% 0.87% Sad 1.05% 0.46% Mad 7.50% 31.50% Aad 17.59% 13.15% Vad 33.99% 46.85%

Qnet.ar 22170kJ/kg 15790kJ/kg

Ultimate analysis of the fuel (bitumite and lignite)

Item Unit Value

Flue gas Nm3/h 380000

NSR / 1.4

Initial NOx conc. mg/m3 300

Target NOx conc. mg/m3 <100

Urea solution % 16.6

Consumption of reagent L/h 420

SNCR Parameter

Urea solution is used as reagent in

this demonstration boiler;

Designed DeNOx efficiency is 60~70%.




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Urea solution tank

Pumps

Metering Distributing and Mixing Module Injection point

(Inside of the Cyclone inlet)


Pictures of equipment and installation

5 Nozzle of each cyclone;

Nozzles installed inside of the

cyclone inlet;

Sectorial air atomizing nozzle;

Droplets size 50um



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Field testing Result

Reagent Injection

Reagent Injection

Increasing Reagent

Bitumite BMCR

Lignite BMCR

DeNOx efficiency about 55%; Reagent consumption 200L/h; Reagent Utilization rate about 40%

DeNOx efficiency about 70%; Reagent consumption 450L/h; Reagent Utilization rate about 50%




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Field testing Result

Reagent Injection Lignite 50%BMCR

Under 50% BMCR load, initial NOx emission is less than BMCR load;

DeNOx efficiency of SNCR is also lower;

Increasing the reagent, but it seems not useful;

How to increase the DeNOx efficiency under boiler low load is next

key point.




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Summary

Pilot Plant research On the pilot plant, NOx initial emission could be controlled in lower level With the increasing of NSR, the DeNOx efficiency increased The SNCR DeNOx efficiency could be over 70% and the ammonia slip less than 2mg, while NSR is 1.8 Demonstration Boiler Testing NOx initial emission less than150mg when using bitumite, the SNCR DeNOx efficiency is about 55% NOx initial emission conc. using lignite is obviously higher than bitumite The DeNOx efficiency increases while increasing the reagent , the final NOx emission below 100mg/m3

Under the lower boiler load , NOx initial emission is about 160mg/m3, SNCR efficiency is sharply decreased



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Documents

The CFB boiler demonstration project with low NOx technology · Under this new Emission standard, CFB boilers are also faced with the challenge. The NOx emission of most CFB boiler