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SCIENCE CHINA Technological Sciences, Volume 59 , Issue 7 : 1065-1070(2016) https://doi.org/10.1007/s11431-016-6074-6

Numerical simulation of heat transfer process in cement grate cooler based on dynamic mesh technique

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  • ReceivedFeb 17, 2016
  • AcceptedApr 30, 2016
  • PublishedJun 20, 2016

Abstract

A grate cooler is key equipment in quenching clinker and recovering heat in cement production. A two-dimensional numerical model based on a 5000 t/d cement plant is proposed to for a study on the gas-solid coupled heat transfer process between the cooling air and clinker in a grate cooler. In this study, we use the Fluent dynamic mesh technique and porous media model through which the transient temperature distribution with the clinker motion process and steady temperature and pressure distribution are obtained. We validate the numerical model with the operating data of the cooling air outlet temperature. Then, we discuss the amount of mid-temperature air outlet and average diameter of clinker particles, which affect the heat effective utilization and cooling air pressure drop in clinker layer. We found that after adding one more mid-temperature air outlet, the average temperature of the air flowing into the heat recovery boiler increases by 29.04°C and the ratio of heat effective utilization increases by 5.3%. This means heat recovery is more effective on adding one more mid-temperature air outlet. Further, the smaller the clinker particles, the more is the pressure drop in clinker layer; thus more power consumption is needed by the cooling fan.


Acknowledgment

This work was supported by the Horizontal Subject (Grant No. 11471501), and the National Basic Research Program of China (“973” Project) (Grant No. 2013CB228305).


References

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  • Figure 1

    Geometry model of grate cooler.Table 1 Air inlets boundary condition*

  • Figure 2

    Secondary air temperature Vs. Mesh quantity.

  • Figure 3

    Transient temperature distribution with flow time. (a) 20 s; (b) 60 s; (c) 120 s; (d) 180 s; (e) 186 s; (f) 200 s.

  • Figure 4

    Pressure distribution under steady state.

  • Figure 5

    (Color online) Heat flow of grate cooler.

  • Figure 6

    (Color online) Pressure drop comparison with different clinker diameters in different wind chambers. (a) Chamber 1 to 5; (b) chamber 6 to 9.

  • Table 2   Air outlets boundary condition

    Outlet

    Pressure (Pa)

    Temperature (°C)

    Secondary air

    -100

    1000

    Tertiary air

    -100

    900

    High-Tem air 01

    -100

    427

    High-Tem air 02

    -100

    427

    Mid-Tem air

    -100

    427

    Low-Tem air

    -100

    80

  • Table 3   Outlets temperature comparison between simulation and operating data

    Outlet

    Simulation

    values (°C)

    Operating

    values (°C)*

    Secondary air

    1013.08

    1097.68

    Tertiary air

    899.64

    880.43

    High-Tem air 01

    697.87

    634.43

    High-Tem air 02

    616.02

    Mid-Tem air

    496.13

    410.80

    Low-Tem air

    286.23

    259.09

  • Table 4   Heat efficiency comparison between different models*

    Model

    Heat utilization by heat recovery boiler (J/s)

    9.09×107

    9.96×107

    Heat net increment of cooling air (J/s)

    1.37×108

    1.39×108

    Rate of heat effective utilization (%)

    66.31

    71.62

    Average temperature of air flowing to heat recovery boiler (°C)

    313.16

    342.20

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