DE3119372C3 - System for the transmission of the sensible heat of coke - Google Patents

Abstract

In a system for transferring the sensible coke heat of a coke dry cooling chamber (1, 2, 3) in a heat transfer circuit to a coal preheating unit (4, 5, 6) and a waste heat boiler (7, 8, 9) connected in parallel to it, control options are to be created for economical use of waste heat. At least two coke dry cooling chambers (1, 2, 3), coal preheating units (4, 5, 6) and waste heat boilers (7, 8, 9) are provided in each heat transfer circuit. The heat transfer circuits are connected and a shut-off device (17, 18) is provided in front of each of the coke dry cooling chambers (1, 2, 3), coal preheating units (4, 5, 6) and waste heat boiler (7, 8, 9).

Description

a) at least two coke dry cooling chambers (1, 2, 3), coal preheating units (4, 5, 6) and waste heat boilers (7, 8, 9) are provided,

b) each coke dry cooling chamber (1, 2, 3) is assigned a coal preheating unit (4, 5, 6) and a waste heat boiler (7, 8, 9) and the heat transfer circuits connecting the coke dry cooling chambers (1, 2, 3) to the coal preheating units (4, 5, 6) and the waste heat boilers (7, 8, 9) are connected to one another (15, 16) and in each heat transfer circuit a shut-off device (17, 18) is provided for each coal preheating unit (4, 5, 6) and each waste heat boiler (7, 8, 9),

c) the coal preheating units (4,5,6) as a whole and the waste heat boilers (7, 8,9) as a whole are each designed to be at least large enough to cover the heat generated by the coke dry cooling chambers (1,2,

3) absorb the amount of heat that can be released,

d) the coke dry cooling chambers (1, 2, 3) are connected via at least one flow manifold (15, 16) and at least one return manifold (15', 16*).

2. Plant according to claim 1, characterized in that gate valves (19, 20, 21, 22) are provided for shutting off the coke dry cooling chamber (1, 2, 3).

3. Plant according to one of claims 1 and 2, characterized in that the waste heat boiler (7, 8, 9) has two stages (23, 24), one of which is connected upstream of the coal preheating unit (4, 5, 6) via the shut-off device (17) and the other of which is connected to the coke dry cooling chamber (1, 2, 3) via the shut-off device (18).

4. Plant according to one of claims 1 to 3, characterized in that the heat transfer circuit between the coke dry cooling chamber (1,2,3), the waste heat boiler (7,8,9) and the coal preheating unit (4, 5, 6) is closed.

5. Plant according to one of the preceding claims 1 to 4, characterized in that the heat transfer circuit between the coke dry cooling chamber (1, 2, 3), the waste heat boiler (7, 8, 9) and the coal preheating unit (4, 5, 6) is open.

6. System according to claim 6 and 7, characterized in that the heat transfer circuit can be operated both openly and closed.

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The invention relates to a system for transferring the sensible coke heat from the coke dry cooling to waste heat boilers and coal preheating units with a heat transfer circuit.

Such a system is described in the literature reference »Heat«, Volume 85, Issue 6, page 119 (see Figure 8 a). In this system, the heat recovered during the dry coke cooling is used to preheat the coal. To use the residual heat not required for the coal preheating, a waste heat boiler is provided for generating steam. This is therefore only designed to be large enough to absorb the residual heat. This eliminates the possibility of switching off the coal preheating system and still using all of the waste heat generated in the dry coke cooling chamber.

In the documents CH-98 509, DE-AS 1096 861 and US-14 67 506, systems are described in which the waste heat from the coke is only ever used in the waste heat boilers, i.e. to generate steam. Coal preheating does not take place in the known systems. The system described in JP-52-38 503 has one more waste heat boiler than the total number of coke cooling chambers. Coal preheating also does not take place

In the document DE-OS 23 17 348, several coke oven cooling chambers connected in parallel are provided, the waste heat from which is fed to a single waste heat boiler and a single coal preheating system, with the waste heat boiler and the coal preheating system being connected in series. Due to this series connection, it is not possible to adjust the waste heat fed to the waste heat boiler or the coal preheating system. In addition, it is not possible to switch off one unit independently of the other unit.

To transfer the heat from the coke dry cooling chamber to the coal preheating system, the proposal in the literature mentioned provides for a closed heat transfer circuit. DE-AS 27 38 442 describes a system for utilizing the sensible coke heat for steam generation and coal preheating, in which a steam generator and a coal preheating system are connected in series. An open flue gas stream is used as the heat transfer gas. The waste heat is used for steam generation and coal heating. Control options are not provided.

As is well known, coal preheating not only improves the quality of the coke but also leads to a significant increase in the throughput of coal or coke. Compared to the use of wet coal, throughput increases of up to 50% can be achieved by preheating coal. In principle, this is advantageous, but in practice it is desirable to adapt the throughput to the respective market situation when the market situation changes. It would be uneconomical not to use the waste heat from the dry coke cooling chamber.

The economic efficiency of the entire system is also reduced if an interruption in operation is necessary for maintenance purposes.

The object of the invention is to propose a system of the type mentioned at the beginning, which can be controlled in the manner of waste heat utilization and whose operation does not have to be interrupted in the event of maintenance.

According to the invention, the above object is achieved in a system of the type mentioned at the beginning in that

a) at least two coke dry cooling chambers (1, 2, 3), coal preheating units (4, 5, 6) and waste heat boilers (7, 8, 9) are provided,

b) each coke drying cooling chamber (1,2,3) is assigned a coal preheating unit (4,5,6) and a waste heat boiler (7,8,9) and the coke drying

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cooling chambers (&iacgr;, 2, 3) are connected to each other (15, 16) by heat transfer circuits connecting the coal preheating units (4, 5, 6) and the waste heat boilers (7, 8, 9), and in each heat transfer circuit a shut-off device (17, 18) is provided for each coal preheating unit (4, 5, 6) and each waste heat boiler (7, 8, 9),

c) the coke preheating units (4, 5, 6) as a whole - and the waste heat boilers (7, 8, 9) as a whole are each designed at least large enough to absorb the amount of heat that can be given off by the coke dry cooling chambers (1, 2, 3),

d) the coke dry cooling chambers (1,2,3) are connected via at least one flow manifold (15, 16) and at least one return manifold (15', 160).

The system can thus be controlled in such a way that, depending on the respective requirements, the coal preheating units are working and the waste heat boilers are switched off, or vice versa, the waste heat boilers are working and the coal preheating units are switched off. It is also possible for only one coal preheating unit and one waste heat boiler to be working. In any case, all of the heat recovered in the coke dry cooling chambers is used. If necessary, a switched off coal preheating unit or a switched off waste heat boiler can be serviced without interrupting operations. Likewise, one of the coke dry cooling chambers can be switched off and serviced without having to interrupt operations.

The invention therefore allows the coal or coke throughput to be adapted to the respective market situation within wide limits without reducing the efficiency of the plant by not using the heat available in the coke dry cooling chamber. In addition, one of the units can be used as a reserve unit.

The system can be set up, for example, with two coke dry cooling chambers, coal preheating units and waste heat boilers. More coke dry cooling chambers, or coal preheating units or waste heat boilers can also be provided. Another advantage is that the system can be easily expanded at a later date according to the respective requirements.

Further advantageous embodiments of the invention emerge from the subclaims.

The following is a description of an example of implementation. The drawing shows

Fig. 1 a combined plant with three coke dry cooling chambers, coal preheating units and waste heat boilers,

Fig. 2 a heat transfer circuit of the combined plant between a coke dry cooling chamber, a coal preheating unit and a waste heat boiler with a closed gas circuit,

Fig. 3 another heat transfer circuit of the combined plant with a closed gas circuit between a coke dry cooling chamber, a coal preheating unit and a waste heat boiler, and

Fig. 4 shows a heat transfer circuit according to Fig. 3 with an open gas circuit.

Three coke dry cooling chambers 1, 2 and 3, three coal preheating units 4, 5 and 6 and three waste heat boilers 7, 8 and 9 are provided. Hot coke from a coke oven 10 is fed into the coke dry cooling chambers 1, 2 and 3 and discharged from them in a cooled state.

The coal preheating units 4, 5 and 6 are fed with wet coal. Hot coal is fed from them to the coke oven 10

Water is fed into the waste heat boilers 7, 8 and 9. Steam leaves them.

The three stages shown in Fig. 1 are each constructed with regard to the heat transfer circuit as shown in Fig. 2, 3 or 4

In Fig. 2, a heat transfer gas is fed to the coke dry cooler 1, 2 or 3 by means of a blower 11. The heat transfer gas leaves the coke dry cooler 1, 2 or 3 through lines 12 or 13. Line 12 leads to the coal preheating unit 4, 5 or 6. There, the heat transfer gas releases the heat absorbed in the coke dry cooler 1, 2 or 3 to wet coal. The heat transfer gas is returned to the blower 11 via a water vapor condenser 14.

Line 13 leads to the waste heat boiler 7, 8 or 9. There, the heat transfer gas water evaporates. The heat transfer gas is also returned from the waste heat boiler 7, 8 or 9 to the fan 11.

All lines 12 are connected to one another via a collecting line 15 and all lines 13 via a collecting line 16. Viewed in the direction of flow behind the connection points there are shut-off devices 17 in the lines 12. Correspondingly there are shut-off devices 18 in the lines 13. The collecting lines 15 and 16 form the flow section. Corresponding return collecting lines are provided. They are designated 15' and 16' in Fig. 2

By means of the shut-off devices 17 and 18, the heat transfer gas can either be directed to the coal preheating unit 4, 5 or 6 or to the waste heat boiler 7, 8 or 9 or partially fed to these system components.

With the system described, the following operating modes are possible:

If it is initially assumed that all three coke dry cooling chambers 1, 2 and 3 are in operation, then all shut-off valves 17 can be open and all shut-off valves 18 can be closed. Coal preheating then takes place at maximum power. If reduced coal preheating is desired, then one of the shut-off valves 17 is completely or partially closed and one of the shut-off valves 18 is completely or partially opened. This means that part of the heat transfer gas passes through the collecting line 16 into the waste heat boiler 7, 8 or 9, whose shut-off valve 18 has been opened. In addition to reduced coal preheating, steam is generated.

To further reduce the coal preheating, a second or shut-off valve 17 can be closed and another of the shut-off valves 18 can be opened. This means that the waste heat from the coke dry cooling chambers 1, 2 or 3 is used to a greater extent to generate steam.

Finally, if no coal preheating is to take place, all three waste heat boilers 7, 8 and 9 can be connected to line 13. The entire waste heat from the coke dry cooling chambers 1, 2 and 3 is now used to generate steam.

The three coal preheating units 4, 5 and 6 are designed so that they can absorb the entire waste heat from the three coke dry cooling chambers 1, 2 and 3. The same applies to the waste heat boilers 7, 8 and 9.

The coal preheating units and waste heat boilers that are not switched on can be serviced without interrupting operations.

If one of the coke dry cooling chambers 1, 2 or 3 is to be serviced, its heat transfer circuit must be switched off. For this purpose, gate valves 19 and 20 are provided in line 12 and gate valves 21 and 22 in line 13. The other coke dry cooling chambers as well as all coal preheating units 4, 5 or 6 and waste heat boilers 7, 8 or 9 can continue to operate.

In the embodiments according to Fig. 3 and 4, the system parts that are the same as in Fig. 1 and 2 are marked with the relevant reference numerals. In the heat transfer circuit according to Fig. 3 and 4, a waste heat boiler 7, 8 or 9 with two stages 23 and 24 is provided (two-zone boiler). The first stage 23 is located between the line 13 and the shut-off device 17. The second stage !5 24 is connected downstream of the first stage 23 and is connected to the return manifold 16' via the shut-off device 18. The coal preheating unit 4, 5 or 6 is connected to the return manifold 16' via the shut-off device 20.

Fig. 3 shows the connection of the units with a closed gas circuit. The coke dry cooling chamber and the first stage of the waste heat boiler are connected in series with the coal preheating units in parallel between the collecting lines 16 and 16'. The line between the shut-off devices 20 and 18 serves here to return the gas from the coal preheating unit to the coke dry cooling chamber or the return collecting line 16'.

Fig. 4 shows the connections of the units with an open gas circuit. The coke dry cooling chambers 1, 2 and 3, waste heat boilers 7, 8 and 9 and coal preheating units 4, 5 and 6 are each connected in series between the flow manifold 16 and the return manifold 16'. The line between the shut-off device 18 and the shut-off device 20 serves to bypass the coal preheating unit 4, 5 and 6 when it is not in operation.

The functioning of the heat transfer circuit according to Fig. 3 with a closed gas circuit is approximately as follows:

The coke dry cooling chamber 1, 2 or 3 receives heat transfer gas via the fan 11 from the return manifold 16'. If the shut-off device 17 is open, hot heat transfer gas from the coke dry cooling chamber 1, 2 or 3 or the flow manifold 16 enters the first stage 23 of the waste heat boiler 7, 8 or 9 at a temperature of approx. 800 ⁰ C and generates steam there. At a temperature of approx. 600 ⁰ C, the heat transfer gas then reaches the coal preheating unit 4, 5 or 6 via the shut-off device 17. The cooled heat transfer gas is fed to the return manifold 16' via the shut-off device 20. Part of the heat transfer gas can be fed directly to the return manifold 16' or the blower 11 via the shut-off device 18, bypassing the coal preheating units 4, 5 and 6. Depending on the setting of the shut-off devices 17 and 18, a greater or lesser part of the heat energy can be used for coal preheating or steam generation. When the coal preheating unit 4, 5 and 6 is switched off, the entire heat transfer gas flows through the two stages 23 and 24 of the waste heat boiler 7, 8 and 9.

The functioning of the heat transfer circuit according to Fig. 4 with an open gas circuit is approximately as follows:

Heat transfer gas is fed to the coke dry cooling chamber 1, 2 or 3 via the blower 11 from the collecting line 16 shown with a solid line. In the coke dry cooling chamber 1, 2 or 3, this heats up and reaches the waste heat boiler 7, 8 or 9 via the line 13. Steam is generated in the first stage 23 of the latter. The residual heat of the heat transfer gas is used in the coal preheating unit 4, 5 or 6. The heat transfer gas, which has then cooled down, leaves the combined system via the collecting line 16' shown with a solid line. The residual heat of the heat transfer gas can also be used in the second stage 24 of the waste heat boiler 7, 8 or 9 if the shut-off devices 17 and 18 are positioned accordingly. The coal preheating unit 4, 5 or 6 is then completely or partially bypassed.

Numerous other embodiments are within the scope of the invention. These can, for example, consist of a combination of the heat transfer circuits according to Figs. 2 and 3 or 3 and 4.

4 sheets of drawings

Claims (1)

Patent claims: 1. Plant for transferring the sensible coke heat from the dry coke cooling to waste heat boilers and coal preheating units with a heat transfer circuit, characterized in that