EP1085264B1 - Process and apparatus for water cooling of a combustion grate - Google Patents

Abstract

A waste heat boiler (3) is connected in downstream of the fire chamber (2) and supplied with supply water (23) of which a part is removed after the water pump (25) and before the water regulating valve (26) from the water pipe (22) and directed through at least one pressure drop point (20) from where it is then supplied as cooling water (15) to the cooling channels (14). On passing through the cooling channels the cooling water is heated up to at least saturated steam temperature and is then supplied to the remote heat supply device or economiser.

Description

The invention relates to a method for the cooling of with cooling channels provided parts of a Feuerungsrostes, the be heated during operation of the Feuerungsrostes can. The invention relates to a furnace grate for a combustion plant for carrying out the method.

Water-cooled grates with one of the primary air separate cooling system are known, such as in EP 0 621 449 B1, EP 0 757 206, DE 44 00 992 C1 and WO 96/29544 A described.

All of these firing grates have a cooling system that by the water supply of the firing grate downstream Waste heat boiler is independent. These cooling systems have the Disadvantage that they need separate feed pumps and that at ambient pressure or at slightly elevated pressure work so that the grate bars and other parts of the grate, which must be cooled, a maximum of Boiling temperature of the cooling water corresponding, relatively low Have temperature, causing losses in the preheated Primary combustion air gives. It also gets through the relatively cool grate bars of the combustion process on the Rust disturbed. A heat utilization of the amount of heat dissipated is because of the low temperature level of the cooling water difficult or impossible at all. After all must to ensure the cooling of the combustion grate an emergency cooling system can be used, resulting in additional investment costs caused.

In DE 808263 C is still a rust for the combustion of solids discloses, in which a waste heat boiler is connected downstream, over a Feedwater line with feedwater pump and feedwater control valve Feed water is supplied. This will be additional pumping systems superfluous.

The object of the invention is a simple method for better Cooling a firing grate of an incinerator to create and cooling a firing grate in a plant to burn Feststeffen to improve.

Under a chilled firing grate, not only the Grate bars, but possibly also middle bars, side end plates and the crash of the grate to be understood.

According to the invention this is achieved in a method according to claim 1, with a portion of the feedwater after the feedwater pump and before the Feedwater control valve removed from the feedwater line and under Use of a defined pressure reduction is fed to the cooling channels, the control of the pressure of the cooling water and the Flow rate in the cooling channels is set so that the Cooling water when flowing through the cooling channels to saturated steam temperature is heated and thus a part of the cooling water is evaporated and subsequently supplied to a customer is to improve in an antitank to the burning of Feststeffen and then a customer.

Because for every boiler operation the perfect function of the water supply (Water treatment, water supply, boiler feed pump) is an indispensable condition, always becomes one much effort was made to ensure this water supply. By now the cooling water for the combustion grate tapped from this safe source, that is as Cooling water for rust demineralized, degassed boiler feed water is used advantageously ensures that always cooling water in sufficient quantity, with enough Printing and in perfect quality is available.

As the boiler feed water pump with high pressure and large Volume promotes what is necessary for the waste heat boiler, stands despite a lowering of the pressure a high pressure level Available, so that the cooling water to relatively high Temperatures can be heated before the boiling point is reached becomes. This leads to correspondingly high temperatures, especially the grate bars, so that an adverse effect the combustion process on the grate and a Cooling of preheated primary combustion air avoided can be. There are also additional pump systems superfluous. Another advantage is that the cooling water with high Pressure and high speed through the cooling tubes is pumped inside the grate parts to be cooled, so that one with relatively small pipe diameters of Cooling channels gets along, creating a segregation of water and steam can be avoided.

Further advantageous embodiments of the method result from the claims 2 to 5.

With regard to the design of a plant for the burning of Feststeffen is the Object of the invention, starting from the features of claim 6, solved according to the invention thereby, that the cooling channels have a comparatively small inner diameter, whose maximum size is designed so that no segregation of water and steam takes place, and that the lines to the cooling channels, which moved in Rostbelaginheiten lie, tubes are with an inner diameter, which is less than the inner diameter of the cooling channels, and wherein the Supply lines between feedwater pump and feedwater valve with the Feed water line are connected and in the supply lines at least one Valve is arranged, which controls the amount of cooling water to be supplied via a automatic temperature control system regulates.

This grate has the advantage that it has cooling channels having small diameter, which in larger numbers with uniform distribution within the grate bar and the further rust parts can be poured. Another Advantage is that the cooling system with little Water is operable, since all the sensible heat and a Part of the heat of evaporation can be used.

It is useful if as a buyer of the heated cooling water or cooling water / steam mixture either the Drum of the boiler is used (then the cooling takes place at the pressure and temperature level of the drum and the Coolant temperature and the material temperature in the Grate unit row is about constant), or else others Customers, such. B. district heating supplier, feedwater tank, Air preheater are used, in which the adjusting Vapor pressure can be lower than the drum pressure, which then correspondingly a lower grate unit temperature causes.

Furthermore, it is advantageous if the cooling water / steam mixture a Steam separator is fed, the vapor deposited in the drum is passed and the remaining saturated water in the feed water is returned. In addition, it can be used to preheat the cooling water.

It is advantageous if in the at least one pressure drop point, a pressure drop is generated in the cooling water, which is at least ¼ of the pressure drop between the exit from the feedwater pump and the entrance into the drum. In this way, an approximately constant in all cooling circuits Cooling water flow reached.

Furthermore, it is expedient if diaphragms, thin tubes as pressure drop points or valves are used, the latter having the disadvantage that they are expensive are.

It is advantageous if the supply and discharge lines for the cooling water with at least one expansion circle are executed. As a result of the small one Diameter of the lines and through the arranged expansion circles it is thus possible, without any problems, the thermal strains and the movements to compensate for the moving grate units or a partial grate.

Finally, it is expedient if more per row of grate rows parallel cooling circuits are provided, the number of the thermal Load on the parts to be cooled is dependent.

Short description of the drawing

In the drawing, several embodiments of the invention are shown.

Fig. 1

einen Längsschnitt einer schematisch dargestellten Müllverbrennungsanlage;

Fig. 2

eine schematische Darstellung des Kühlsystems eines wassergekühlten Rostes mit nachgeschaltetem Kessel in einer ersten Ausführungsvariante der Erfindung, bei welcher als Abnehmer des erwärmten Kühlwassers bzw. des Wasser/Dampf-Gemisches die Trommel des Kessels fungiert und Ventile als Druckabfallstellen eingesetzt sind;

Fig. 3

eine schematische Darstellung eines Kühlsystems, das nicht unter die Erfindung fällt, eines wassergekühlten Rostes mit nachgeschaltetem Kessel , bei welcher als Abnehmer des erwärmten Kühlwassers bzw. des Wasser/Dampf-Gemisches die Trommel des Kessels fungiert und Blenden als Druckabfallstellen eingesetzt sind;

Fig. 4

eine zweite Ausführungsvariante der Erfindung analog zu Fig.2, bei welcher als Abnehmer des erwärmten Kühlwassers bzw. des Wasser/Dampf-Gemisches der Speisewassertank fungiert;

Fig. 5

eine dritte Ausführungsvariante der Erfindung analog zu Fig.2, bei welcher als Abnehmer des erwärmten Kühlwassers bzw. des Wasser/Dampf-Gemisches der Luftvorwärmer fungiert;

Fig. 6

eine vierte Ausführungsvariante der Erfindung analog zu Fig.2, bei welcher als Abnehmer des Wasser/Dampf-Gemisches ein Dampfabscheider fungiert, von welchem den Dampf in die Trommel und das Sattwasser in das Speisewasser geführt wird;

Show it:

Fig. 1

a longitudinal section of a schematically illustrated waste incineration plant;

Fig. 2

a schematic representation of the cooling system of a water-cooled grate with downstream boiler in a first embodiment of the invention, in which acts as a buyer of the heated cooling water or the water / steam mixture, the drum of the boiler and valves are used as pressure drop points;

Fig. 3

a schematic representation of a cooling system, which does not fall under the invention, a water-cooled grate with downstream boiler, in which acts as a buyer of the heated cooling water or the water / steam mixture, the drum of the boiler and diaphragms are used as pressure drop points;

Fig. 4

a second embodiment of the invention analogous to Figure 2, in which acts as a buyer of the heated cooling water or the water / steam mixture of the feedwater tank;

Fig. 5

a third embodiment of the invention analogous to Figure 2, in which acts as a buyer of the heated cooling water or the water / steam mixture of the air preheater;

Fig. 6

a fourth embodiment of the invention analogous to Figure 2, in which acts as a buyer of the water / steam mixture, a vapor separator from which the steam is fed into the drum and the saturated water in the feed water;

Only the elements essential to the understanding of the invention are shown. The direction of flow of the media is indicated by arrows.

Way to carry out the invention

The invention will be described below with reference to exemplary embodiments and the FIG. 1 to 6 explained in more detail.

Fig. 1 shows a longitudinal section of a schematically illustrated Waste incineration plant, which essentially consists of a water-cooled Combustion grate 1, an overlying combustion chamber 2 and a downstream boiler 3 with vertical Leerzügen 4 and a horizontal Bundle 5 consists. The kiln 6, in this case waste, is on the grate 1 abandoned and burned with supply of primary air 7 and secondary air 8. The Resulting flue gases 9 enter the boiler 3, they flow under Release of heat through the vertical empties 4 and the horizontal Bundle 5 of the boiler 3 and then one not shown Flue gas cleaning system supplied. In that regard, such systems are known.

Fig. 2 shows a schematic representation of the cooling system of water-cooled grate 1 with downstream boiler 3 in a first Embodiment variant of the invention. The grate 1 consists essentially of several rows (10.1, 10.2, 10.3 ...) arranged side by side Rostbelaginheiten 11. In Fig. 2 are an example of a thermally highly stressed Row 10.1 and two thermally low loaded rows 10.2 and 10.3 are shown, where the 10.2 series has a fixed grate coating unit row and row 10.3 is to represent a moving row of grate units and the two rows 10.2 and 10.3 are connected by a flexible connecting line 38. The Rostbelaginheiten 11 may be narrow grate bars or wider grate plates. Adjacent rows overlap each other like a tile. It can be longitudinally be arranged alternately moving and fixed rows of the grate or all rows can be moved. The grate 1 also has side walls 12 on.

Are the Rostbelaginheiten 11 in several grate tracks next to each other arranged, then these grate webs are by means of central beams 13 from each other separated. In the Rostbelaginheiten 11, the side walls 12, the middle beam 13 and the crash of the grate, not shown, are cooling channels 14 for Be arranged with cooling water 15, which in Fig. 2 only in the Rostbelaginheitenreihe 10.3 is shown schematically. The cooling channels 14 are preferably in the Rostbelaginheiten 11 cast-in coils, which with supply lines 16 and discharge lines 17 are in communication, the Lines 16, 17 are thin tubes, each having a stretch circle 18th can have. The cooling channels 14 have a comparatively small Inner diameter, for example 14 mm. This is each designed so that There is no segregation of water and steam in the pipes. Of the Inner diameter of the supply lines 16 is substantially lower than that Inner diameter of the cooling channels 14, for example 8 mm. Of the Inner diameter of the discharge lines 17 is because of the forming Vapor phase slightly larger than that of the supply lines 16, but still much smaller than the diameter of the cooling channels 14 in the Grating units 11.

In each supply line 16 are a three-way valve 19 and at least one Valve 20 installed.

The supply lines 16 all branch off from a line 21, which in turn branches off from the feedwater line 22, in which boiler feedwater 23 from Feedwater tank 24 via the feedwater pump 25 and the Feedwater control valve 26 via the economizer 27 into the drum 28 of the Boiler 3 is passed. The branch of the line 21 from the line 22 takes place doing so after the feedwater pump 25 and before the feedwater control valve 26th

The discharge lines 17 of the cooling systems each have check valves 29 and open into a manifold 30, which to the drum 28 of the boiler. 3 connected. The drum 28 is further provided with an evaporator 31 and a superheater 32 with a water injection 33, which via a Injector 36 is controlled, in conjunction.

The cooling system of the grate consists of several parallel connected Subsystems. In Fig. 2 are exemplified a subsystem for cooling the side walls 12, a subsystem for cooling a Rostbelaginheitenreihe 10.1 in the thermally highly stressed part of the grate 1, a subsystem for the Cooling of two rows 10.2 and 10.3 of grate in thermally lower loaded part of the grate 1 and a subsystem for the cooling of the central beams 13th

For cooling the grate-covering units 11, the side walls 12 and the middle beams 13 cooling water 15 is used, which is a partial flow of demineralized degassing feedwater 23 for the operation of the boiler is 3. This cooling water 15 bypasst the economizer 27, it is after the feedwater pump 25 and before the feedwater control valve 26 is removed from the feed line 22 and flows via the line 15 in the supply lines 16 of the parallel subsystems of the Cooling system. By choosing this sampling point after the Feedwater pump 25 and before the feedwater control valve 26 is a ensures safe cooling water supply with largely constant pressure.

The grate cooling is thus parallel to the economiser operation. As part of the Boiler feed water is used as cooling water 15, stands for the grate cooling always enough water available, which also a flawless Quality and sufficient pressure.

The supply and removal of the cooling water 15 to be cooled to rust components 11, 12, 13 via the lines 16 and 17, which pipes with very small Diameter are. Thanks to this small diameter, these are so flexible that they the movement of Rostbelaginheiten or a sub-grate, the z. B. +/- 350 mm, without further participation. When shown in Fig. 2 Embodiment are expansion circuits 18 in the lines 16, 17 are provided to compensate for the movement or the thermal expansions. Of course, the lines 16, 17 without expansion circuits 18th be formed, as shown in Fig. 2 in the partial cooling system of the central bar thirteenth is shown.

In each subsystem is in the cooling water 15 on the at least one, in the Line 16 arranged throttle valve 20 causes a pressure drop, which at least ¼ of the pressure drop between the exit from the Feedwater pump 25 and the entry into the drum 28 is.

The cooling water 15 is in the cooling of Rostbelageinheiten 11, the Side walls 12 and the center bar 13 at least close to the Saturated steam temperature heated. Normally, the cooling water is 15 down to the Saturated temperature heated so that a portion of the water 15 evaporates. The Cooling water can also be completely or to a large extent (steam content> 0.3) evaporate, d. H. the cooling takes place according to the single-pipe boiler principle.

The heat from the rust components to be cooled with the water or removed from the water / steam mixture. Per subsystem of the cooling system flows only very little cooling water 15, so all the sensible heat and part of the Heat of vaporization is used. Therefore, the cooling channels 14, so the Cooling tubes only of relatively small diameter. There's the advantage that steam and water do not separate. Thanks to the always safe Water supply for the cooling is unnecessary the demand for the guarantee Of emergency running properties, so that as Rostbelagmaterial no expensive high-alloyed Cast steel are used, but cheaper low-alloyed material can be used.

On the outlet side, the heated cooling water or water / steam mixture over the lines 17 in a manifold 30 and from there into the drum 28th guided. The cooling is thus at a pressure and temperature level, the only slightly above the drum 28 is located. The advantage is that the delivery of the dissipated amount of heat in the drum 28 is always possible.

Since the amount of heat generated in different grate units 10.1, 10.2 can be very different, it is advantageous to automatic regulation provided. This is indicated by the dashed line in the middle of FIG. 2 clarified. A temperature control system TCA measures the outlet temperature of the heated cooling medium in line 17. The corresponding signals are directed to the valve 20, which depends on the respective Temperature level, the amount of the supplied cooling water 15 controls, d. H. at a high temperature value, the valve 20 will open further, so that more Cooling water 15 is passed into the respective cooling channels 14 than at a lower temperature. In this way, the cooling can be optimized in which case slightly superheated steam is generated (single-tube boiler principle).

Fig. 3 shows a schematic representation of the cooling system of a water-cooled grate with downstream boiler. This differs from that in FIG. 1 shown and described above only in that as Pressure drop points 20 apertures are used. Similarly, thin tubes or manually operated needle valves can be used.

It is possible, the heated cooling water or the resulting during cooling To pass steam to another customer. This is the heated Cooling water fed to a part of the steam network. In which the pressure is deeper is as the drum pressure. This is shown in FIGS. 4 to 6.

Fig. 4 shows a variant of the invention analogous to FIG. 2 at which as a buyer of the heated cooling water 15 and the water / steam mixture not the boiler 28, but the feedwater tank 24 acts.

In the variant shown in Fig. 5, however, the customer is the Air preheater (Economiser 27) or as shown in dashed lines, a District heating supply device 34.

With these variants described, the resulting vapor pressure can be lower be as the drum pressure, which is advantageously a deeper Grate unit temperature causes.

Finally, it is according to the further embodiment variant shown in FIG the invention also possible, the manifold 30 in a vapor separator 35th to lead, so that the water / steam mixture enters the vapor separator, the separated steam then into the drum 28 of the boiler 3 to guide and the remaining saturated water in the feedwater tank 24th attributed, which thus additionally the cooling water 15 via a Heat exchanger 37 can be preheated.

It is also advantageous if the water supply line 16 to a moving Rostbelaginheitenreihe 10.3 leads, this via a flexible connection line 38th is connected to a fixed grid row 10.2 and the Discharge line 17 from the fixed grid row 10.2 to Bus 30 leads. In this case, the discharge line 17 a have larger diameter, since they do not have to be flexible and that in it contained water / steam mixture produces only a small pressure drop.

Of course, the invention is not limited to those described Embodiments limited.

LIST OF REFERENCE NUMBERS

1

rust

2

firebox

3

waste heat boiler

4

empty train

5

bank pass

6

Kiln, solids (waste)

7

primary air

8th

secondary air

9

fumes

10

Grate-lining unit series

11

Grating unit, z. B. grate bar, grate plate

12

Side wall

13

center bar

14

Cooling channel in pos. 11, 12, 13

15

cooling water

16

Supply line to pos. 14

17

Discharge line from Pos.14

18

expanding circuit

19

Three-way valve

20

throttle valve

21

Line for pos. 15, diverted from pos

22

Feedwater line

23

feedwater

24

Feedwater tank

25

Feedwater pump

26

Feedwater control valve

27

economizer

28

Drum (customer)

29

check valve

30

manifold

31

Evaporator

32

superheater

33

water injection

34

District heating supply

35

steam separator

36

Injector

37

heat exchangers

38

flexible connection line

TCA

Temperature Control System

Claims (10)

1. Process for cooling a grate (1) for a combustion chamber (2) by means of water (15), a waste heat boiler (3) being arranged downstream of the combustion chamber (2), feedwater (23) being fed to this waste heat boiler (3) via a feedwater line (22) having a feedwater pump (25) and a feedwater control valve (26), and the grate (1) essentially comprising a plurality of grate lining units (11), arranged next to one another in rows (10), and side walls (12) and if need be centre beams (13) and drops, inside which the cooling water (15) is directed along in cooling passages (14), some of the feedwater (23) being extracted from the feedwater line (22) downstream of the feedwater pump (25) and upstream of the feedwater control valve (26) and being fed to the cooling passages (14) using a defined pressure reduction (20), the control of the pressure of the cooling water (15) and of the flow rate in the cooling passages (14) being set in such a way that the cooling water (15) is heated to saturated steam temperature when flowing through the cooling passages (14) and thus some of the cooling water (15) is evaporated and then fed to a receiver (24, 27, 28, 34, 35).
2. Process according to Claim 1, characterized in that the heated cooling water or cooling-water/steam mixture is fed to the drum (28) of the waste heat boiler (3).
3. Process according to Claim 1, characterized in that the heated cooling water or cooling-water/steam mixture is fed to a part of the steam network in which the pressure is lower than the drum pressure.
4. Process according to Claim 1, characterized in that the cooling-water/steam mixture is fed to a steam separator (35), the separated steam is directed into the drum (28), and the saturation water left behind is fed back into the feedwater tank (24).
5. Process according to one of Claims 1 to 4, characterized in that a pressure drop is produced in the cooling water (15) at the at least one pressure-drop point (20), this pressure drop being at least ¼ of the pressure drop between the discharge from the feedwater pump (25) and the inlet into the receiver (24, 27, 28, 34, 35).
6. Plant for burning solids (6), having a grate which is cooled according to the process according to one of Claims 1 to 5, the grate (1) essentially comprising a plurality of grate lining units (11), which are arranged next to one another in rows (10) and are designed to be alternately fixed and/or movable in the longitudinal direction of the grate, and side walls (12) and if need be centre beams (13) and drops, with in each case cooling passages (14) arranged therein for the admission of cooling water (15), and feed lines (16) and discharge lines (17) and also flexible connecting lines (38) for the cooling passages (14), and a waste heat boiler (3) being arranged downstream of the grate (1), it being possible for feedwater (23) to be fed to this waste heat boiler (3) via a feedwater line (22) having a feedwater pump (25) and a feedwater control valve (26), the cooling passages (14) having a comparatively small inside diameter, the maximum size of which is designed in such a way that no segregation of water and steam takes place, and the lines (16, 17, 38) to the cooling passages (14), which lie in moving grate lining units (11), being pipes with an inside diameter which is smaller than the inside diameter of the cooling passages (14), and the feed lines (16) being connected between feedwater pump (25) and feedwater control valve (26) to the feedwater line (22), and at least one valve (20) being arranged in the feed lines (16), this valve (20) regulating the quantity of cooling water to be fed via an automatic temperature control system (TCA).
7. Plant according to Claim 6, characterized in that the cooling passages (14) are integrally cast pipe coils.
8. Plant according to Claim 6, characterized in that the feed lines (16) and the discharge lines (17) for the cooling water (15) are designed with at least one expansion loop (18).
9. Plant according to Claim 6, characterized in that there are a plurality of parallel subsystems of the cooling system, the number of which depends on the thermal loading of the parts to be cooled.
10. Plant according to Claim 6, characterized in that the feed line (16) of the cooling water (14) is connected to a moving row (10.3) of grate lining units, which is in turn connected to a fixed row (10.2) of grate lining units via a flexible connecting line (38).

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