EP0663565B1 - Grate bar and grate with cooling device and cooling method - Google Patents

Abstract

Fluid-cooled grate bars and grates for use in a combustion furnace such as a garbage incineration plant and a process for cooling the grate bars and grates. The grate bar has a duct defined therewithin for guiding a coolant supplied by a fluid-cooling apparatus. The primary coolant is preferably water. Steam formation is prevented by pressurizing the water. Additional or replacement coolant such, for example, as air may be employed for the grate bars and grates.

Description

The invention relates to a grate bar and grate Cooling device and a method for cooling for Incinerators, especially from Waste incineration plants. A grate with cooled grate bars is already known from document DE-U-9 309 198.

A grate for incinerators is usually formed by rows of grate bars that lie one above the other and extend transversely to the transport direction of the firing material.
Grate firing is also used as a tried and tested apparatus for domestic waste incineration. The individual grids are covered with grate bars. These have the task of transporting the garbage, mixing (so-called stoking) and taking over the burnout. The processes of drying, preheating, degassing, gasification and C-burnout run on the grate, and thus the grate bars, one after the other.

The grate bars are provided with openings (slots, Gaps, holes, etc.) through the combustion air is blown.

The grate bars are particularly stressed by mechanical Abrasion as well as thermal and chemical wear. Corresponding wear leads to changes in the Fire management, the burnout qualities and ultimately too Business interruptions. The wear of the grate bars is essentially temperature-dependent.

Appropriate measures will become part of the supplied combustion air - so-called primary air - used to cool the grate bars. The cooling effect depends primarily on the amount of air. Of the remaining part is used for further combustion of the gases added as secondary air in the combustion chamber.

Due to changes in household waste, primarily with regard to to higher calorific values (recycling of glass, from Biological substances / green waste, increased proportion of Plastics) as well as increased fluctuations in the Range of high calorific values, take the grate bar temperatures to, on the one hand due to more intensive combustion, on the other hand, however, also due to lower air volumes below the rust (decreasing cooling effect). The high calorific value requires a redistribution of the entire combustion air in such a way that a higher proportion of the Combustion of the gases becomes necessary.

The invention has for its object grate bars and to create a grate that burns when burning high-calorie fabrics are wear-resistant, their shape do not change and thus also the combustion behavior as well as the transport and mixing behavior in the oven change. In addition, good emergency running properties are said to Water loss and a relatively low warming of the Water to less than 100 degrees Celsius is preferred less than 50 degrees Celsius can be reached. About that In addition, steam formation is to be effectively prevented will.

According to the invention, the problem is solved by claims 1, 7 and 12 solved. Advantageous developments of the invention are specified in the subclaims.

The grate bar according to the invention with a cooling device on which at least one inlet and one outlet opening are arranged has at least one channel for guidance in the grate bar of cooling water, essentially in the longitudinal direction of the Rust bar, on. Since the longitudinal direction of the grate bar This corresponds to the material feed device particularly good cooling of the individual grate bars reached. By cooling every single grate bar the heating of the cooling medium can be relatively low being held. This increases the operational safety of the Cooling and the service life of the grates respectively Cooling system. Water is preferred as the cooling medium used. Other, higher-boiling cooling media are for special applications can also be used.

The channel arranged in the grate bar preferably has two, substantially parallel sections with each other opposite flow direction, this with one arranged in the head area of the grate bar Redirection are connected. The sections of the canal with opposite flow direction can in the horizontal or vertical plane side by side or lie on top of each other. The channels are in the With regard to the heat to be dissipated fluidically optimized so that the heating of the coolant is not more than about 50 degrees Celsius, preferably about 20 degrees Celsius is. Especially with superimposed, approximately parallel sections of the cooling channel can this different cross-sectional shapes and areas exhibit. The one arranged in the head area of the grate bar Redirection can lie in the plane caused by the Central axes of the approximately parallel sections of the Cooling channel goes.

The deflection is preferred up to the range of an adjacent row of grate bars resting on the edge of the Grate rod head led. It is in the area of The grate bar head is approximately U-shaped.

In a special embodiment, the inlet and outlet openings for the coolant are arranged at the foot of the grate bar in the area of the coolant at the foot of the grate bar in the area of the grate bar support.
Air outlet openings for combustion air are further preferably arranged in the head part. This further improves the cooling of the grate bar.
According to a special design, recesses for the exit of combustion air are also arranged in the long sides of the grate bar.

In another special case there is one on the grate closed cooling device operated with overpressure arranged, the vapor formation in an advantageous manner within the cooling circuit and thus also within individual grate bars or grates prevented. This Cooling system advantageously consists of one Expansion or compensation vessel (32), the cooled Grate bars (34), a recooler (35) and a pump (36) and a connection (31) for filling or Draining of the cooling system together with the pressure control valve (33).

When using water, the cooling medium is in one Cooling system under pressure, preferably between 1 and 6 bar operated. This will cause steam to form avoided and e.g. a two-phase flow or formation of "steam pillows" with correspondingly worse Prevents heat transfer.

The grate according to the invention for incinerators, especially of waste incineration plants, with juxtaposed rows of alternating fixed and movable rows of grate bars, which from the above This is due to rust bars characterized that inlet and outlet openings of all Grate bars in parallel with one Main inlet line and a main outlet line connected are. This makes the same for all grate bars Cooling effect achieved. For each grate bar also essentially the same temperature distribution on (assuming the same heat load), so that each grate bar also about the same temperature-related Shows stretch.

For individual applications, however, several, in Grid bars lying next to each other in the direction of the grate width be connected in series so that, for example in adaptation to the different heat load in An adapted center and edge areas of the grate Cooling effect of the grate bars is achieved. In a special version with fourteen side by side Grate bars are, for example, the first, sixth and eleventh Grate bar with its inlet opening to the Main supply line connected. The fifth, tenth and fourteen grate bars are with their drain opening to the Main drain line connected. The rest of the procedure Inlet openings of neighboring grate bars are interconnected. It is special provided both the fixed grate bar rows as also to cool the moving grate bar rows.

According to a particularly preferred feature of the invention are between the main inlet and outlet and inlet and Drain opening of the first or last grate bar a row of grate bars or a section of one Row of grate bars in which the inlet and outlet openings of the individual grate bars are connected in series, Valves for the supply or discharge of another Cooling medium, especially air, and Interruption of the main inflow or outflow line arranged. This has the advantage that in the event of a leak in one or more grate bars in a row of grate bars air cooling is used instead of water cooling and thus the operation until the next planned Downtime can be maintained. About that In addition, rows of grate bars with low thermal loads can be with cheaper cooling media, such as. B. air, cooled will. The combination of several rows of grate bars in Parallel connection to rust zones with common connection or Drain pipe and valves for supply or discharge another cooling medium, in particular air, and Shut-off to the main inlet or outlet line discloses a particularly economical variant.

Using an exemplary embodiment Design of the grate bar according to the invention described.

Figur 1

eine Seitenansicht der Roststablängsseite;

Figur 2

einen Schnitt II nach Figur 1, für eine Umlenkung, die bis in den Bereich der auf einer benachbarten Roststabreihe aufliegenden Kante des Roststabes geführt ist;

Figur 3

einen Schnitt II nach Figur 1, für eine Ausführung der Umlenkung, bei der die Umlenkung etwa in der Mittelebene der parallelen Abschnitte des Kühlkanals liegt;

Figur 4

ein Fließschema eines Rostes, bei dem Ventile zur Zu- und Abfuhr eines weiteren Kühlmediums angeordnet sind.

Figur 5

zeigt ein Schema des Kühlsystems, mit dem die Roststäbe bzw. der Rost gekühlt werden.

Show it:

Figure 1

a side view of the grate bar side;

Figure 2

a section II of Figure 1, for a deflection, which is performed in the area of the resting on an adjacent row of grate bar edge of the grate bar;

Figure 3

a section II of Figure 1, for an embodiment of the deflection, in which the deflection lies approximately in the central plane of the parallel sections of the cooling channel;

Figure 4

a flow diagram of a grate, in which valves are arranged for the supply and discharge of a further cooling medium.

Figure 5

shows a schematic of the cooling system with which the grate bars or the grate are cooled.

In Figure 1 is a grate bar 1 with grate bar support 2 in Area of the grate bar base 3 shown. The grate bar head 4 lies with the edge 5 on a grate bar adjacent row of grate bars. The grate bar consists of Cast iron. It has a channel 6, which is approximately parallel Has sections (one behind the other in Figure 1). This parallel sections are by a deflection 7th connected with each other. Channel 6 is related Provide drain openings 8. This feed and Drain openings are preferably located directly on the foot side End of the channel 6 attached.

In Figure 2 is a section II-II of Figure 1 through the Grate bar head 4 shown. The roughly parallel Sections of channel 6, here referred to as 6 'and 6' ' open into a deflection 7, which is in the plane of Section II is approximately U-shaped down to the bottom Edge 5 of the grate bar head 4 is guided. In the grate bar head 4 between and next to the legs of the U-shaped Deflection 7 air outlet openings 9 are provided.

In Figure 3 is a section II of Figure 1 for a Execution shown, in which the deflection is not in the area of the edge 5 is drawn. The redirection 7 forms here together with the channel sections 6 'and 6' ' in their plane also an approximately U-shaped Cross-section. The sections 6 'and 6 '' can also be arranged one above the other.

A flow diagram of a grate is shown in FIG.

There is between the main inlet and the main outlet line 11 of a cooling medium, in particular water, and 12 and drain opening 13 of the first 14 and last 15 Grate bar of each row of grate bars, their addition or Drain openings of the individual grate bars in a row are connected to one another, valves for supply or Removal 17 of a further cooling medium, in particular air, as well as to interrupt the main inlet 18 or Main drain line 19 arranged. The feed of the second Cooling medium takes place via the main supply line 20 or Main discharge line 21. A preferred direction of waste flow arrow 22 indicates.

The grate according to the invention and the grate bar have the Advantage that the grate bars without changing the Incinerator can be used. It stays therefore with the previous combustion technology. That too mechanical transport and mixing behavior (forward / return stroke) stay unchanged. This applies to both the weight also the stroke length and so on. The rust is also extremely wear-resistant, as the grate bars are made as before Cast. Therefore, the grate bar according to the invention and rust also have excellent emergency running properties Malfunctions, for example in the event of water failure. The grate bars preferably have the hitherto known Form on, with the width of the grate bars approximately doubled is, so that in one half, that is, so far usual grate bar width, the cooling water forward to in head is headed and in the second half again is returned. The parallel channel sections face a clear height of about 15 to 25 mm and a clear Width of about 40 to 60 mm. The flow rate is between 0.5 and 2 m per second. The temperature the grate bar is approximately in the middle between head and Foot area around 100 degrees Celsius. This will make one Corrosion caused by condensation avoided. In the area of Headboard will have a temperature of about 150 degrees Celsius adhered to so that with regard to the burnout behavior no disadvantage arises.

In a special embodiment, the Grate bars or the grates in a closed, under Pressure water-cooled cooling system integrated and operated. The temperature of the water is for example 90 ° C, but increased to 120 ° C and the system pressure is 1 to 6 bar, preferably 5 bar.

Here the cooling system pressure is via a compressor, the air in via a bubble from the water side separated outside space of an expansion vessel or Compensation vessel promotes, adjusted. The system pressure in the cooling water circuit is via one in the expansion tank integrated automatic expansion set: On Contact manometer starts the compressor of the Expansion machines as soon as a lower limit pressure in the System is achieved. The compressor is switched off as soon as the pressure reaches an upper limit. At Exceeding an adjustable top Limit pressure value, e.g. 6 bar, air is through a valve blown off. The two switching points are adjustable between 1.0 and 6.0 bar. By separating air, which are within the stretchable bladder, preferably a rubber bladder, the expansion vessel, and Water that is outside the bladder will advantageously prevents the cooling water Absorbs oxygen and thus signs of corrosion feeds the grate bars.

In Figure 5 is the diagram of a cooling device shown. Through the connection 31 water is in the Cooling device fed, the Pressure control valve 33 the system before pressing on Grate entry protects over 2 bar. The pump 36 promotes this Water through one or more grate bars or grate 34 and the cooling device. The expansion or Compensation vessel 32 with a Provide level measuring device, with the help of Automatically falls below a lower limit fresh water is fed into the system and at the same time a message is sent to the control room. At the The infeed will reach an upper limit level automatically interrupted by water. By the frequency the message to the control room about the water feed leaks in the system can be recognized, so that appropriate measures can be initiated. Everyone The grate bar or each row of grate bars can be locked separately. In addition, are as measuring devices Water mass flow measuring device 37, a Temperature measuring device, 38, 39 and one Cooling system pressure measuring device 40 is provided. Of the Fan 41 cools the recooler 35.

Reference symbol list:

31:

Water supply

32:

Expansion vessel

33:

Pressure control valve

34:

Rust, chilled

35:

Recooler

36:

pump

37:

Water mass flow measuring device

38:

Temperature measuring device

39:

Temperature measuring device

40:

System pressure measuring device

41:

fan

Claims (13)

1. Grate bar formed from cast iron with a cooling apparatus for the manufacture of a combustion grate with a plurality of grate bars situated adjacent one another over the width of the grate, wherein a supply aperture and a discharge aperture for cooling water are located in the grate bar, and at least one duct (6) extends in the grate bar (1) substantially in the longitudinal direction of the grate bar (1) for ducting the cooling water.
2. Grate bar according to claim 1, characterised in that the duct (2) has substantially parallel portions (6', 6") with opposite directions of flow, said portions being connected to a deflection (7) situated in the upper region (4) of the grate bar.
3. Grate bar according to claim 2, characterised in that the deflection (7) extends into the region of the edge (5) of the grate bar upper region (4) resting on an adjacent row of grate bars, said deflection being substantially U-shaped, more especially in the region of the grate bar upper region (4).
4. Grate bar according to claim 3, characterised in that supply and discharge apertures (8) are located in the base (3) of the grate bar (1) in the region of the grate bar support (2).
5. Grate bar according to one of claims 1 to 4, characterised in that air outlet apertures (9) are located in the upper region (4).
6. Grate bar according to one of claims 1 to 5, characterised in that recesses for the emission of air are located in the longitudinal sides of the grate bar (1).
7. Grate for combustion furnaces, more especially of refuse incinerators, with adjacently situated rows of alternately fixed and moving rows of grate bars formed from grate bars of claims 1 to 6, characterised in that supply and discharge apertures (8) of all of the grate bars are connected, in parallel connection, to a main supply line or respectively to a main discharge line.
8. Grate for combustion furnaces, more especially of refuse incinerators, with adjacently situated rows of alternately fixed and moving rows of grate bars formed from grate bars of claims 1 to 6, characterised in that supply and discharge apertures (8) of a plurality of adjacent grate bars are interconnected in series connection.
9. Grate for combustion furnaces, more especially of refuse incinerators, with adjacently situated rows of alternately fixed and moving rows of grate bars formed from grate bars of claims 1 to 6, characterised in that a closed cooling apparatus, operated with excess pressure, is located on the grate, more especially with a compressor and an expansion vessel.
10. Grate for combustion furnaces, more especially of refuse incinerators, with adjacently situated rows of alternately fixed and moving rows of grate bars formed from grate bars of claims 1 to 6, characterised in that valves for the respective supply (16) or discharge (17) of an additional cooling medium, more especially air, and for the interruption of the respective main supply line (18) or the main discharge line (19) are located between main supply line (10) and main discharge line (11) and supply aperture (12) and discharge aperture (13) of the first grate bar (14) or respectively of the last grate bar (15) of a row of grate bars, wherein the respective supply and discharge apertures of the individual grate bars are connected in series with one another.
11. Grate for combustion furnaces, more especially of refuse incinerators, with rows of grate bars situated adjacent one another and formed from grate bars according to claim 10, characterised in that a plurality of rows of grate bars are interconnected in parallel connection to form grate zones and have a common supply and discharge line, in which valves for the respective supply or discharge of an additional cooling medium, preferably air, are located.
12. Method for the direct cooling of grate bars and grates of combustion furnaces corresponding to one of claims 1 to 11, characterised in that the cooling medium flowing through the grate bar or the grate is guided in a cooling system under excess pressure.
13. Method according to claim 12, characterised in that the excess pressure of the cooling apparatus is adjustable by means of an expansion vessel coupled with a compressor.

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