# Thermal load impact on steam parameters for cooling the shaft furnace.

1. INTRODUCTION

The cooling system by evaporation based on the level of the temperature and the amount of heat released out of process. The proposed outline for the furnace cooling as shown in Fig. 1, consist of part of manifolds (TL1, TL2), from the part pipelines composite of the lower cooling (FP), medium (FM) and on top (FS), from exonerative pipes (TSH1, TSH2) and steam cylinder-separator (CS). In outline are including connection pipes (TLDH1, TLDH2) and collectors (KO1, KO2). Manifolds, connection and exonerative of outline are the diameter, length, height and certain number ([d.sub.L1], [d.sub.L2], [d.sub.1], [d.sub.2], [d.sub.SH1], [d.sub.SH2], [L.sub.L1] [L.sub.L2], [L.sub.SH1], [L.sub.SH2], [H.sub.L1], [H.sub.N], [H.sub.FP], [H.sub.FM], [H.sub.FS], [H.sub.SH1], [H.sub.SH2], [H.sub.KTH], [n.sub.L1], [n.sub.L2], [n.sub.1], [n.sub.2], [n.sub.SH1], [n.sub.SH2]) as well as the corresponding coefficient of hydraulic resistance [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]. The impact of thermal loads, thermal-physical parameters (p, [T.sub.N, [rho'], [rho''], [rho], h', h", h, [c.sub.p], v, [mu], [beta], a, [sigma], [lambda], [P,sub.r] [DELTA]h'/[DELTA]p) of steam-water mixture, then geometric parameters and hydro mechanical of communications of outlines circular in consumptions circular ([G.sub.o]), in speed of the circulation ([[omega].sub.o]) and mass content of steam consumption ([x.sub.D]) is in interest to assess the cooling system by evaporation in Trepca shaft furnace.

2. THERMAL LOAD IMPACT, ON DYPHASIC BRINGING OF OUTLINE

For practical calculations of heat transmission between gas and cooling medium in the furnace coolant (FP, FM, FS), should be designate the amount of heat per unit surface area according to the formula (Michael & Howard, 2004) as the following:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (1)

Where [[alpha].sub.G], [[alpha.sub.AU]--are coefficients of gas heat transmission (Gordon, 1993) and steam- water composite (Sacadura, 1993) Who are determined by the following equation:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (2)

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (3)

Whereas [t.sub.G], [t.sub.AU]--is gases temperature in the lower coolant level, and temperature of steam--water composite, [degree]C; [[delta.sub.GA], [[delta.sub.M], [[delta.sub.K] then [[lambda.sub.GA], [[lambda.sub.M] [[lambda.sub.M]--thickness and heat conductivity coefficients for protective layer, coolant wall and calcium carbonates layer in level of FP, FM and FS. Amount of heat transmitted to the unit surfaces area of FP, FM and FS is determined according to equation:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (4)

Where are: [A.sub.P], [A.sub.M], [A.sub.s]--overall coolant surfaces of the lower, medium and of the top level, [m.sup.2].

[FIGURE 1 OMITTED]

To determine the height from which come of the movement effort, it is necessary to determinate the scission this begins the regime of steam (Kutepov, M. 1983). This scission determined by the length of the economizer part [l.sub.EK] as follows:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (5)

Where are: [h.sub.LSH]--water enthalpy incoming the manifolds, kJ/kg; [q.sub.p]--heat density flux in the economizer scission, kW/[m.sup.2]; d--Internal diameter of tube, m. Speed of circulation can be determined by the gradual approximation method (equation 8). The first designated the total coefficient of hydraulic resistance to water line under the equation:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (6)

Where are: [Z.sub.L1], [Z.sub.L2], [Z.sub.EK]--overall coefficient of hydraulic resistance in not heated manifolds with diameter dL1 and [d.sub.L2] likewise in economizer part. The complex [[SIGMA][DELTA].sub.ML] is determined by expression:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (7)

Where are: [[DELTA].sub.P.sub.PTF], [[DELTA].sub.P.sub.TSH], [[DELTA].sub.P.sub.LL]--total loss of pressure in the hered of half-pipes in the ranks of furnace coolants in manifold and in the part of manifold (in up lift of composite above than free surfaces of liquid in cylinder).

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (8)

Mass content of steam consumption at the exit of tubes herd of the furnaces coolants determined by the following equation:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (9)

3. CALCULATIONS AND RESULTS

Incoming data (Agolli, 1985) for calculation are: [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]. Calculations are done according to the respective program.

[FIGURE 2 OMITTED]

Variables of the model, in this paper are calculated for several levels of incoming values of thermal loads, meanwhile the presented results above are obtained for average values of thermal loads: [q.sub.P]=17653 W/[m.sup.2], [q.sub.M]=9655 W/[m.sup.2] and [q.sub.S]= 2669 W/[m.sup.2].For example, in fig. 2, fig. 3. and fig. 4. is shown dependence [G.sub.o] = f ([Q.sub.F]), [[omega].sub.0] = f ([Q.sub.F]) and [x.sub.D] = f([Q.sub.F]), for a wider range of change of quantity of heat (1/5, 1/2, 1, 2, 5, 10, 12, 15 and 20 x [Q.sub.F])

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

4. CONCLUSION

Dependence [G.sub.o] = f ([Q.sub.F]) and [[omega].sub.0] = f([Q.sub.F]) is characterized with circulation consumption and speed low circulation for small thermal loads.

By increasing of thermal loads we have consumption increase ([G.sub.o]) and circulations speed ([[omega].sub.0) up to a certain level. In addition, with further increase of thermal loads appears reduce of consumption ([G.sub.o]) and speed ([[omega].sub.0]) because the other factors who act in the opposite direction affect on this.

By increasing the thermal load increases the content of steam ([x.sub.D]) in the outline, and moving effort where at once increases the circulation consumption ([G.sub.o]) and on the other hand, increases hydraulic resistance in upper parts outline, that have steam content.

For the average parameters of the work regime in the furnace, is generated a considerable amount of steam in the furnaces coolant (FP, FM, FS) as: [D.sub.AP] = 0.168 kg/s, [D.sub.AM] = 0.150 kg/s, [D.sub.AS]' = 0.057 kg/s and [D.sub.AF]' = 0.375 kg/s.

5. REFERENCES

Agolli, F. (1985). Metallurgy of ferrous metals, Faculty of mining and metallurgy, Mitrovice

Kutepov, M. & Sterman, S. (1983). Hydrodynamics and heat transfer in the creation of steam, BBK 31. 31 K95 YDK 621.1.7, Moskva

Gordon, M. (1993). Thermal calculations of metallurgical furnaces, Metallurgy, ISBN5-229-00711-7, Moskva

Michael, J. & Howard, N. (2004). Fundamentals of Engineering Thermodynamics, John Wiley, ISBN 0-47127471-2, Hoboken

Sacadura, J. (1993). Knowledge for thermal transfer (Initiation aux transferts thermiques, TEC&DOC, ISBN 2-85206-6181, Paris

The cooling system by evaporation based on the level of the temperature and the amount of heat released out of process. The proposed outline for the furnace cooling as shown in Fig. 1, consist of part of manifolds (TL1, TL2), from the part pipelines composite of the lower cooling (FP), medium (FM) and on top (FS), from exonerative pipes (TSH1, TSH2) and steam cylinder-separator (CS). In outline are including connection pipes (TLDH1, TLDH2) and collectors (KO1, KO2). Manifolds, connection and exonerative of outline are the diameter, length, height and certain number ([d.sub.L1], [d.sub.L2], [d.sub.1], [d.sub.2], [d.sub.SH1], [d.sub.SH2], [L.sub.L1] [L.sub.L2], [L.sub.SH1], [L.sub.SH2], [H.sub.L1], [H.sub.N], [H.sub.FP], [H.sub.FM], [H.sub.FS], [H.sub.SH1], [H.sub.SH2], [H.sub.KTH], [n.sub.L1], [n.sub.L2], [n.sub.1], [n.sub.2], [n.sub.SH1], [n.sub.SH2]) as well as the corresponding coefficient of hydraulic resistance [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]. The impact of thermal loads, thermal-physical parameters (p, [T.sub.N, [rho'], [rho''], [rho], h', h", h, [c.sub.p], v, [mu], [beta], a, [sigma], [lambda], [P,sub.r] [DELTA]h'/[DELTA]p) of steam-water mixture, then geometric parameters and hydro mechanical of communications of outlines circular in consumptions circular ([G.sub.o]), in speed of the circulation ([[omega].sub.o]) and mass content of steam consumption ([x.sub.D]) is in interest to assess the cooling system by evaporation in Trepca shaft furnace.

2. THERMAL LOAD IMPACT, ON DYPHASIC BRINGING OF OUTLINE

For practical calculations of heat transmission between gas and cooling medium in the furnace coolant (FP, FM, FS), should be designate the amount of heat per unit surface area according to the formula (Michael & Howard, 2004) as the following:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (1)

Where [[alpha].sub.G], [[alpha.sub.AU]--are coefficients of gas heat transmission (Gordon, 1993) and steam- water composite (Sacadura, 1993) Who are determined by the following equation:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (2)

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (3)

Whereas [t.sub.G], [t.sub.AU]--is gases temperature in the lower coolant level, and temperature of steam--water composite, [degree]C; [[delta.sub.GA], [[delta.sub.M], [[delta.sub.K] then [[lambda.sub.GA], [[lambda.sub.M] [[lambda.sub.M]--thickness and heat conductivity coefficients for protective layer, coolant wall and calcium carbonates layer in level of FP, FM and FS. Amount of heat transmitted to the unit surfaces area of FP, FM and FS is determined according to equation:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (4)

Where are: [A.sub.P], [A.sub.M], [A.sub.s]--overall coolant surfaces of the lower, medium and of the top level, [m.sup.2].

[FIGURE 1 OMITTED]

To determine the height from which come of the movement effort, it is necessary to determinate the scission this begins the regime of steam (Kutepov, M. 1983). This scission determined by the length of the economizer part [l.sub.EK] as follows:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (5)

Where are: [h.sub.LSH]--water enthalpy incoming the manifolds, kJ/kg; [q.sub.p]--heat density flux in the economizer scission, kW/[m.sup.2]; d--Internal diameter of tube, m. Speed of circulation can be determined by the gradual approximation method (equation 8). The first designated the total coefficient of hydraulic resistance to water line under the equation:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (6)

Where are: [Z.sub.L1], [Z.sub.L2], [Z.sub.EK]--overall coefficient of hydraulic resistance in not heated manifolds with diameter dL1 and [d.sub.L2] likewise in economizer part. The complex [[SIGMA][DELTA].sub.ML] is determined by expression:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (7)

Where are: [[DELTA].sub.P.sub.PTF], [[DELTA].sub.P.sub.TSH], [[DELTA].sub.P.sub.LL]--total loss of pressure in the hered of half-pipes in the ranks of furnace coolants in manifold and in the part of manifold (in up lift of composite above than free surfaces of liquid in cylinder).

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (8)

Mass content of steam consumption at the exit of tubes herd of the furnaces coolants determined by the following equation:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (9)

3. CALCULATIONS AND RESULTS

Incoming data (Agolli, 1985) for calculation are: [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]. Calculations are done according to the respective program.

[FIGURE 2 OMITTED]

Variables of the model, in this paper are calculated for several levels of incoming values of thermal loads, meanwhile the presented results above are obtained for average values of thermal loads: [q.sub.P]=17653 W/[m.sup.2], [q.sub.M]=9655 W/[m.sup.2] and [q.sub.S]= 2669 W/[m.sup.2].For example, in fig. 2, fig. 3. and fig. 4. is shown dependence [G.sub.o] = f ([Q.sub.F]), [[omega].sub.0] = f ([Q.sub.F]) and [x.sub.D] = f([Q.sub.F]), for a wider range of change of quantity of heat (1/5, 1/2, 1, 2, 5, 10, 12, 15 and 20 x [Q.sub.F])

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

4. CONCLUSION

Dependence [G.sub.o] = f ([Q.sub.F]) and [[omega].sub.0] = f([Q.sub.F]) is characterized with circulation consumption and speed low circulation for small thermal loads.

By increasing of thermal loads we have consumption increase ([G.sub.o]) and circulations speed ([[omega].sub.0) up to a certain level. In addition, with further increase of thermal loads appears reduce of consumption ([G.sub.o]) and speed ([[omega].sub.0]) because the other factors who act in the opposite direction affect on this.

By increasing the thermal load increases the content of steam ([x.sub.D]) in the outline, and moving effort where at once increases the circulation consumption ([G.sub.o]) and on the other hand, increases hydraulic resistance in upper parts outline, that have steam content.

For the average parameters of the work regime in the furnace, is generated a considerable amount of steam in the furnaces coolant (FP, FM, FS) as: [D.sub.AP] = 0.168 kg/s, [D.sub.AM] = 0.150 kg/s, [D.sub.AS]' = 0.057 kg/s and [D.sub.AF]' = 0.375 kg/s.

5. REFERENCES

Agolli, F. (1985). Metallurgy of ferrous metals, Faculty of mining and metallurgy, Mitrovice

Kutepov, M. & Sterman, S. (1983). Hydrodynamics and heat transfer in the creation of steam, BBK 31. 31 K95 YDK 621.1.7, Moskva

Gordon, M. (1993). Thermal calculations of metallurgical furnaces, Metallurgy, ISBN5-229-00711-7, Moskva

Michael, J. & Howard, N. (2004). Fundamentals of Engineering Thermodynamics, John Wiley, ISBN 0-47127471-2, Hoboken

Sacadura, J. (1993). Knowledge for thermal transfer (Initiation aux transferts thermiques, TEC&DOC, ISBN 2-85206-6181, Paris

Printer friendly Cite/link Email Feedback | |

Author: | Terziqi, Avni Kahriman; Haxhiaj, Ahmet Bajram; Kamberaj, Naim Sokol; Bajraktari, Bekim Veli |
---|---|

Publication: | Annals of DAAAM & Proceedings |

Article Type: | Report |

Geographic Code: | 1USA |

Date: | Jan 1, 2010 |

Words: | 1145 |

Previous Article: | Improving the classify user interface in WEKA explorer. |

Next Article: | The analysis of influencing factors on combustion time of the lignite in TC "Kosova A". |

Topics: |