EP0815396B1 - Combustion grate and process for optimising its operation - Google Patents

Abstract

A combustion grate including fire bars which are either wholly or partially cooled by a fluid circulating in a closed regulating circuit. The flow lines which conduct the fluid have thermal expansion capability. In particular, windings are provided in the shape of a helical spring in these flow lines. The fire bars include corrugated exchangers and can be replaceable rods.

Description

The present invention relates to a combustion grate according to the preamble of claim 1.

It is known that different combustion Fuels such as household waste, industrial waste, wood waste, solid, porous and liquid fuels as well as fuels with high and low ignitability, preferably fireboxes for use come through a mechanical grate and through chilled or uncooled refractory sidewalls formed are.

Such systems have the disadvantage that their operation cannot be optimally designed for each of the fuels and therefore certain, especially rust parts of such systems Disorders and short lifetimes.

Rust coating cooling systems are also known, such as the Cooling of the grate by the air flowing past in the air funnels Combustion air or the forced cooling of the Rust deposits from the combustion air, which is caused by a Space made up of the grate bar and a baffle, is pressed into the firebox.

These known types of cooling are based on the amount of combustion air dependent, whereby the air exits in the combustion chamber through ash, solid metals or slag can be clogged. Consequently is the cooling of the corresponding covering no longer secured. This can lead to malfunctions. At the same time, these are Types of cooling with the disadvantage that the amount of combustion air primarily a procedural one Has a function and does not have to perform a cooling function. A Change in the amount of combustion air depending on the cooling effect is not always feasible. In this case too the cooling effect of the grate covering is not guaranteed.

Water cooling of the grate is also known the amount of water intended for cooling the grate covers the grate at an approximately constant temperature, independently on the calorific value of the fuel. Again, this is a Disadvantage when burning fuels with lower Calorific value because heat is extracted from the combustion chamber. In this The case would be a higher casting surface temperature for the combustion advantageous.

From the document DE-U-93 09 198 is now a combustion grate known in which a liquid or gaseous medium be passed through the grate bars for tempering can. The grate should either be cooled as required or be warmed. The rust shows the general Shape of a board, i.e. a largely flat exterior Surface. Baffles can form inside the grate a labyrinth for the temperature control medium.

It has now been shown, however, that the very high temperature fluctuations problems regarding the Expansion of the temperature medium occur, especially if a larger number of grate bars tempered together should be.

The object of the present invention is now one to further improve such rust and in particular a to ensure reliable tempering to the Optimize combustion of the fuel.

According to the invention, this object is achieved by a grate with the features of claim 1. Preferred Embodiments result from the dependent claims 2 to 7.

The features of the invention make it possible, too with large temperature fluctuations a large number of To temper the grate bars by the supply lines for the Medium compensate for the thermal expansion directly.

The invention is then based on, for example Drawing explained.

Fig. 1 ein Kühlschema für einen Luft/Wasser gekühlten Verbrennungsrost mit Regelkreis,

Fig. 2 eine seitliche Darstellung eines Vorschubrostes,

Fig. 3 eine Darstellung analog Fig. 2 einer Rostzone, in vergrössertem Massstab,

Fig. 4 einen Schnitt gemäss Schnittlinie IV - IV der Fig. 3,

Fig. 5 eine perspektivische Darstellung eines Luft/ Wasser gekühlten Roststabes in Seitenansicht von vorne, mit weggebrochenen Teilen,

Fig. 6 eine perspektivische Darstellung des Luft/Wasser gekühlten Roststabes gemäss Fig. 5, in Seiten-/ Hinteransicht,

Fig. 7 einen Wenderoststab mit weggehobener Seitenwand und Metallschlauch-Verbindungsleitungen.

Show it:

1 is a cooling diagram for an air / water cooled combustion grate with control loop,

2 is a side view of a feed grate,

3 shows a representation analogous to FIG. 2 of a rust zone, on an enlarged scale,

4 shows a section along section line IV - IV of FIG. 3,

5 is a perspective view of an air / water cooled grate bar in a side view from the front, with parts broken away,

6 is a perspective view of the air / water cooled grate bar according to FIG. 5, in side / rear view,

Fig. 7 a turning grate bar with lifted side wall and metal hose connecting lines.

The invention is shown in FIGS. 1 to 7 on an air / water cooled combustion grate, which explains how it works is designed as a moving grate. It can be done the invention but without problems on other grate designs apply, such as pyrolysis grate, degassing grate, gasification grate, Incineration grate, high temperature incineration grate, cooling grate, Transport grate, counter-running grate, counter-moving grate, back-moving grate, Roller grate u. the like

The feed grate 1 shown schematically in FIG. 1 serves to the fuel and that from combustion To transport slag through the firebox and at the same time to function as a combustion air distribution device.

The grate consists of several zones that are horizontal or inclined are arranged. The individual zones can be on the lie on the same level or be separated by a fall.

Each individual grate zone consists of fixed and movable Grate levels with fixed grate bars 3 and movable grate bars 2. The movable stages are with variable number of strokes pushed back and forth, which transports the fuel and is turned. The number of strokes is from the fuel and depending on the combustion process. The combustion takes place in the fuel layer through which the combustion air, So-called underwind, from below through gaps in the rust covering 22 (Fig. 2) is blown into the combustion chamber. The serves Combustion air, which is connected to the control circuit via a heat exchanger is operatively connected, at the same time cooling the Grate covering 22. The gap between the individual grate bars 2 or 3 must be so small that as little unburned as possible Small parts can fall through. These are columns all evenly distributed over the entire grate surface.

The stroke length and the stroke speed of the movable grate covering 22 of the individual rust zones 20 is dependent on the Heat release set on grate 1 or in the combustion chamber.

Der Rostbelag 22 fördert den Brennstoff durch den Feuerraum.

Der Rostbelag 22 dient als Luftverteilvorrichtung für den Unterwind.

Der Rostbelag 22 ist einer hohen thermischen Belastung ausgesetzt und hat aufgrund der hohen Anschaffungskosten und grossen Stillstandszeiten bei eventuellen Reparaturen eine lange Lebensdauer und grosse Betriebssicherheit aufzuweisen.

The function of the grate covering 22 is thus defined as follows:

The grate covering 22 conveys the fuel through the combustion chamber.

The grate covering 22 serves as an air distribution device for the downwind.

The rust covering 22 is exposed to a high thermal load and, due to the high acquisition costs and long downtimes during possible repairs, has a long service life and great operational reliability.

The coolant for the feed grate 1 is via distributor 5 fed and after flowing through the grate bars 2 or 3 collected in collectors 6 and returned. As a coolant not only water can be provided, but in particular also liquids with higher boiling points, for example certain oils. But it is also possible with help the control system shown in Fig. 1 the liquid heat up and thus when the feed grate flows through 1 if necessary, give off heat to the grate.

It can be seen from the cooling water diagram according to FIG. 1 that this water or the liquid flowing through the grate in can be cooled or heated in a heat exchanger.

Another heat exchanger in the water network is used for heating or cooling the underwind. By attaching a temperature sensor or a temperature measuring point can be a desired one Temperature in the firebox, especially the temperature of the downwind after leaving the grate 1. By appropriate regulation of the flowing through the grate Liquids can raise the temperature of the downwind or be reduced, depending on the control program envisaged, to adapt this in particular to the specific type of fuel is.

This creates the great advantage that with the Flow medium the underwind temperature in the intended Limits can be changed without affecting the underwind amount being affected.

1 are also the necessary ones Flow fittings provided to bypass accordingly (Bypass) of control parts and this turn off.

The coolant flow is indicated by corresponding arrows.

2 shows the feed grate 1, which has three grate zones 20 having. The grate bars 2 and 3 are on grate slides 21 stored and have a grate facing the firebox 22 on. On the underside of the feed grate 1 are air funnels 23 provided which air zones 24 define.

3 shows an enlarged side view a grate with fixed grate levels 27 and movable grate levels 28. For the supply of coolant to the solid A grate serves a grate 30 and for the supply of the Coolant in the movable grate 28 a feed line 31. FIG. 3 also shows a feed water cylinder 33, which the displacements of the movable grate steps 28th Takes into account.

4, which shows a section through the grate according to FIG. 3 according to section line IV - IV, are the two supply lines 30 and 31 can also be seen. In addition, they are Drain lines 35 and 36 shown for the flow medium.

5 and 6 show details in perspective an air / water cooled grate bar in simple Execution. It can be a movable grate bar 2 or a fixed grate bar 3 act. This grate bar with the grating 22 has a partition 40 in its interior so that a first cooling chamber 41 and a second cooling chamber 42 lying parallel thereto is created. At the There is a water flow opening at the front end of the grate bar 2 or 3 43. This establishes the connection between the two cooling chambers 41 and 42 ago. In each of these cold rooms there is a parallel to the partition 40 corrugated baffle 45, which is the heat exchange elevated.

The grate bars 2, 3 can be pivoted on a grate shaft 46 stored. Immediately below the grate shaft 46 a distributor 48 supporting the grate shaft 46 and under this a collector 47, which in connection with the cooling water supply 50 and the hot water return line 51 den Ensure the coolant flows through the grate rod.

Due to the large temperature differences that occur on the grate in use and non-use condition and as a result the movements of the grate bars 2 are the cooling water supply and Return lines 50 and 51 with helical spring turns, So-called temperature compensation elements 52 provided.

Because of this arrangement, the system of cooling both at rest and in the operating state at the connection points kept tight.

Fig. 7 shows a turning grate bar 60, which on a grate bar support 61 is pivotally mounted. Below this grate bar support 61 is also a supporting coolant distributor 62, combined with a collector 63. One cooling chamber 65 has a corrugated baffle 66 equipped. In this case, one is made of a metal hose existing connecting line 68 is provided, which Thermal stress-free connections for the flow medium ensures.

Since it is a so-called turning grate 60, is on a bearing shell 70 is also provided at its front end, so that, according to any uneven wear of the grate 22, the turning grate bar 60 rotated and the front bearing shell 70 are placed on the grate bar support 61 can. Corresponding connection and connection points are at the front end of the turning grate bar 60, as can be seen, intended.

With the system described and the intended control loop is the influence of the air / water cooled grate thermal overload of the combustion grate restricted locally or on the entire grate surface, that the known malfunctions and wear and tear of the rust coating can be largely excluded. This is due to the air / water cooling of the grate, as shown and explained in FIG. 1. Here cooling takes place depending on the amount of cooling water and the cooling water temperature and heat release the rust. For this purpose, as explained, the temperature control achieved by means of a temperature sensor or temperature measuring system.

Another special feature of the invention is that Incineration of low calorific value from the liquid cycle heat removed from the grate bar by means of heat exchange between grate bar and combustion air, which very intense due to the geometric shape of the grate bar is released into the combustion air and thus the combustion of the rubbish lying on the grate is accelerated.

When burning waste with a high calorific value, the corresponding one Grate parts through the coolant a larger Amount of heat removed, whereas with the incineration of garbage low calorific value in the grate covering dissipates less heat that, in any case, to speed up the combustion process, used for heating the combustion air becomes. The greater transfer of heat to the combustion air and thus the increase in air temperature is achieved by the amount of cooling water due to the combustion chamber side occurring smaller specific heat release stronger reduced as the heat release on the grate and thus the Cooling water temperature increased more. With that one finds Increased heat emission from the grate bar to the combustion air instead of.

In this way, the cooling creates advantages in the Incineration of waste with high, but also with low calorific value, since the heat extracted is used by the combustion air can be fed again.

In this sense, it is new, the cooling function and the Sensibly separate process function and execute it in such a way that with a procedural change the amount of combustion air under the grate (underwind) Effect of the rust coating cooling is influenced in such a way that largely no interference can occur.

Claims (7)

1. Combustion grate which is fully or partly gas and liquid-cooled via a control circuit, having grate bars (2, 3) incorporating lines (50, 51) for respectively supplying and discharging coolant, characterised in that the lines (50, 51) are equipped with heat expansion compensating means (52) in the form of helical spring-type windings.
2. Combustion grate according to claim 1, characterised in that the grate bars (2, 3) have undulated exchangers (45).
3. Combustion grate according to claim 1 or 2, characterised in that the grate bars (2, 3) are in the form of alternating bars (60).
4. Combustion grate according to any of claims 1 to 3, characterised in that the control circuit is closed.
5. Combustion grate according to any of claims 1 to 4, characterised in that the manipulated variable for the control circuit is the cooling water flow rate per unit time and/or the cooling water temperature.
6. Combustion grate according to any of claims 1 to 5, characterised in that the control circuit has at least one heat exchanger for the cooling fluid and preferably one for the combustion air.
7. Combustion grate according to any of claims 1 to 6, characterised in that a bypass is provided in the control circuit.

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