Prepared byEagle Group S.A.E2013

Waste Heat RecoveryPower Generation

It is the technology that transfers the wasteheat of the flue gas coming from both thepre-heater and the clinker cooler at rearand front of the kiln respectively in toElectrical power.

Definitions and features of the first and secondgenerations of pure low-temperature WHR powertechnologies for cement kilns.

The construction of the first and secondgeneration of pure low-temperature WHRtechnologies for cement kilns.

Study on some key issues between 1st Generationand 2nd Generation Pure Low Temperature WasteHeat Recovery Power Generation Technology.

Impacts of WHR power plants on cement kilns.

Target of pure low temperature WHR powergeneration technology for cement kilns.

Contents

Pure Low Temperature Waste Heat RecoveryPower Generation Technology Configure andTargets

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The cooler has twoor more flue gasextraction outlets forpower generation.

An separate steam superheater is set at the cooler sothat the temperature of primarysteam from the turbine isadjustable but not going alongthe temperature fluctuation ofthe flue gas from the kiln.

Circulation air

Separate steamsuperheated, increase

running rate andstability of power plant

An adjustable unit is set inside SP boilerto regulate the temperature of the fluegas at the SP boiler outlet in order tomeet the drying requirement accordingto different.

Definition and features of the first generation of pure low-temperature WHR power technologies for cement kilns.

Definition:

The first generation of pure low-temperature WHR power technologyfor cement kilns:It is the technology that converts the flue gas waste heat below 350•°C from boththe pre-heater at the kiln bottom and the clinker cooler at the kiln top into powerenergy by using 0.69MPa~1.27MPa — 280 •°C ~ 340• •°C steam without impairingthe production quantity & quality of cement clinker, lowering the cement kilnoperation rate, changing cement production technology process & machines, orincreasing the consumption of power energy and heat as the premise.

Features:

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2The Construction of the 1st Generation Technology of purelow-temperature WHR power generation for cement kilns.

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Key Points of the Technology:

Construction Model for Thermodynamic System

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The features of this generation :1) Extract the total flue gas exhausted by the clinker cooler from the cooler as two segments.

2) The waste heat of the flue gas exhausted from the preheater is used for producing steam through SP boiler. The steam generated by SP boiler and the steam & hot water generated by AQC boiler respectively mix before converting into power energy through a set of steam turbine & generator.

3) As the most important characteristic, the parameters of the primary steam for power generation totally vary at range of 0.69~1.27MPa-280•~330••°C.

The differences among the three modes are shown as:1) while the AQC is producing the low pressure & low temperature steam at 0.69~1.27MPa-280~330•°C, it is reproducing either saturate low pressure & low temperature steam at 0.1~0.5MPa-saturated~160•°C or hot water at 105~180•°C.

2) Steam turbine is used as the type of either with or without secondary steam.

3) Due to the same flue gas parameter, the power generation capacity will be 100% if based on the first mode, about 101.5%~102% if based on the second mode and about 102~103% if based on the third mode.

4) The first mode is not affected by the relative location between the steam turbine house and the cooler. The second mode (i.e. combined flash evaporation with secondary steam) is proper for the case that the steam turbine house locates far away from the cooler. The third mode is proper for the case that the (dual-pressure with secondary steam) steam turbine house locates closely to the cooler.

Problem:the advantage is generating power with simple systems and low investments, whilethe disadvantage is:

1) Low theoretical calculated power generation capacity.2) Non-adjustable steam temperature so as to impact the lifetime of steam turbine.3) Non-adjustable drying temperature.4) Bad adaptability for the fluctuation of the cement kiln.5) Mutual influence between AQC boiler and SP boiler.6) High investment per KW.

Power generation capacitybasing on per tonnage of clinker

<140KJ/kg-35kW·h

WHR power generation

4000kW

8130kW

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2The Construction of the 2nd Generation Technology of pure low-temperature WHR power generation for cement kilns.

Waste heat distribution of cooler

56) The adjustable unit is set up at SP boiler.

The thermodynamic system of power plant adopts relative high temperature & pressureprimary steam parameter of 1.57~3.43MPa-340~435•°C so as to provide guaranteefor improving WHR power generation capacity.

Adjusting Unitfor Temperature

C2 Superheater

ASHSuper heater forAdjusting Steam Parameter

Multi-stage Waste Heat Extractionfor Cascade Utilization of Waste Heat

Air Circulation 1.57~3.43 MPa Relative High Pressure Steam Segment0.15~0.5 MPa Low Pressure Steam Segment100~130•°C Hot Water Segment Arranging Heat Surface

Multi-stage Mixed Pressure Admission(With Steam-additional) Steam Turbine

The premises: without impacting the heat consumption of cement clinker; meetingthe required temperature of 170~220•°C for raw meal & fuel drying. without changingcement production technology process & machines; without impacting the productionof cement kiln.

1) The waste heat is able to generate either sub-medium pressure or medium pressuresteam of saturated-overheat 450•°C, low pressure and low temperature steam of0.1~0.5MPa saturated-180•°C, and hot water of 85~130•°C at the same time.

2) That thermodynamic circulation system is able to use medium pressure and mediumtemperature parameters, to improve the thermodynamic circulation system efficiency,and to realize the principle of heat utilization in cascade as per the fluctuation oftemperature as well as making full use of the waste heat contributed by various fluegas temperature from the cement kiln.

3) The flue gas waste heat from cementkiln is converted by its quality into thepower energy to the maximum extentso that the WHR power generationcapacity is improved highly.

Power generationcapacity

12.5%~31.25%

Power generation3140KJ/Kg-38~45kW·h/t

4) It solves the problem of the lifetime of the steam turbine.

5) It creates the conditions for the steam turbine operation with smooth parametersof primary steam pressure and temperature in a large various range.

Actual permissiblevarious rangeof the turbine

Primary steampressure

& temperature

1.27~2.47MPa, 325•°C~400•°CThe 2nd Generation Technology

The 1st Generation Technology

2.29MPa-370•°C

0.689MPa-317°C 0.49~0.98MPa, 292•°C~330•°C

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7) A separate steam super heater is equipped inside the second stage of the preheater.

For example basing on a new type of dry cement kiln with capacity of5500TPD and outlet temperature of 330•°C of flue gas at the preheater:

Annual powergeneration 2.5%

Power capacity2.5%

Power GeneratingIndependently

Power GeneratingIndependently

Does equipping a C2 superheater increase the heat consumption of cement clinker?

8) Circulation air is used for FD fans of clinker cooler;

The waste heat utilization of the flue gas from the clinker cooler is further improved and the power capacity is further

improved more than 5~10%.

9) Combining the technology for WHR system for dry type of long kilns and the2ndGeneration Technology for pure low temperature WHR system can realize therecovery of the high temperature of waste heat ranging of 1000•~1250•°C from thebypass discharge at the preheater and change into power energy in high efficiency,thus reduce the added energy consumption due to the bypass discharge for the cementclinker production.

Technical Specifications (1ST Generation)

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Technical Specifications ( 2nd Generation )

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3Study on some key issues

1) Investment.

2) Safety, Stability, High-Efficiency & Adaptability of WHR System to Fluctuation ofCement Production.

3) Efficiency, Service Life and Adaptability of Steam Turbine to Emergent Interruptionof Cement Kiln.

4)WHR Utilization Rate of Hot Air of Clinker Cooler.

5)Simplicity & Convenience of Operation Control.

6)Regulation & Control of Flue Gas Temperature for Raw Meal & Coal Drying and Impact of WHR System on Deducting Effect of ESP for Preheater.

7)About the Weight of the Boilers (Heat-transferring surface of the boilers)

8)About Heat Efficiency of Waste Heat Recovery Boiler.

9)About the Reform ability of the WHRPP.

10)About the Evaluation & Acceptance of the WHRPP.

11)About the stability of power generation output of the WHRPP.

12)About some key points to focus on site visit in WHR power plant.

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Impacts of WHR power plants on cement kilns

1) HT ID Fan at SP: the load for HT Fan decreases after the power plant is put intooperation.

2) GCT: will adjust water spray quantity according to power plant’s operation or stopuntil water spray stops or totally opens.

4) ESP at SP: dust collection will be affected after the power plant is put into operation.

6) ESP at the cooler: the temperature of ESP will decrease greatly, and the dust loadcorrespondingly decreases.

7) Operation of kiln system: As two HRSGs are added to the kiln system, and the fluegas is both from and to the kiln.

The 3rdGeneration Technology of medium & low temperatureWHR power generation for cement kilns

The ultimate aim:In cement clinker production, besides the fuel consumption of 3140~3350Kj/kg incement clinker production, the electricity consumption is zero.

The premises:For new type dry kilns, guarantee the parameters of flue gas for raw material and coalmill drying, the cement production isn’t impacted, the heat and power consumptionof clinker aren’t increased, the heat source of raw fuel for cement production isn’tchanged and the cement production process isn’t changed

The power of generating setsfora cement kiln with real outputof 5500t/d 12000•~15000kW.

the power generation capacitybasing on per tonnage of clinker3140kJ/kg-48•~52.5kW·h