DE2534092A1 - Solid fuel-fired horizontal boiler for heating oil - with complete combustion and higher flame temperature due to less excess air - Google Patents

Abstract

Solid fuel-fired horizontal boiler for heating oil in positive-feed circulation comprises an elongate housing divided by a baffle into main and post-combustion chambers. At one end are means for injecting airborne e.g. saw dust or wood chippings continuously, and a burner for liquid or gaseous fuel for producing a supporting flame. The walls of the main combustion chamber are lined and cooled by a pipe coil through which the oil flows. The larger fuel components are burnt on a grate in the main combustion chamber. In the post-combustion chamber are one or more pipe coils, and at its outlet is a suction fan. The gaps between the turns of the pipe coil in the main chamber are closed at the top and sides and open at the bottom so that the pipe coil forms the grate beneath which is an ash chamber with a secondary air inlet opening.

Description

"Horizontal Solid Fuel Boiler" The invention relates to one horizontal boiler for heating heat transfer fluid that does not boil during operation, in particular such oil, in forced circulation with a through a throttle constriction Elongated housing divided transversely into a main combustion chamber and an afterburning chamber, with a device for the continuous blowing in of that which can be transported in the air stream Solid fuel on one face, which also has a burner for liquid or carries gaseous fuels to generate a supporting and holding flame, with a the peripheral wall of this face then the main combustion chamber forming boiler compartment lining and cooling coiled tubing, which by the liquid flows through, with a grate in the main combustion chamber on which coarser parts of the fuel should burn out with one or more Coiled pipe coils in the afterburning chamber and with one downstream of the afterburning chamber Induced draft fan.

The boiler preferably has additional safety devices which ensure that if the forced circulation of the heat transfer fluid fails, so normally if the pump provided for this purpose fails, further combustion is interrupted, for example by interrupting the further blowing of fuel, any combustion air fan and the induced draft fan can be done. However, such safety devices are not the subject of Invention and therefore not explained in more detail here.

The solid fuel that can be transported in the air stream can, for example from wood flour, sawdust, enough fine chaff and whatever else is formed be. It can also contain larger components. The maximum size of coarse fractions is determined by the fact that it can still be transported perfectly by the air stream and into the main combustion chamber must be inflatable. If the Solid fuel, as preferred, from wood and vegetable waste of the above the species mentioned, for example, is formed, it should be sufficiently dry, so that not too large a proportion of the heat of combustion contained in it for evaporation the water content of the fuel must be used. If the fuel is too moist difficulties can arise with boilers of the type improved by the invention, unless the fuel is high enough in calories or it is supplied with additional liquid or gaseous fuel burned together.

Solid fuel stoves normally require a fireclay brick lining. In this case, you have to drive with a large excess of air so that the flame does not gets so hot that it destroys the brickwork relatively quickly. To this difficulty to eliminate, one already has boilers of the type improved by the invention a coiled tubing lined, which was tightly wound so that the entire Circumferential wall of the main combustion chamber by the circulating in this coiled tubing Heat transfer fluid is cooled. Good results can be achieved with this. The disadvantage of such a boiler, however, is that the fuel is not may contain larger particles. These then no longer burn on the fly but fall to the ground, where they remain unburned. This problem leaves You cannot avoid installing a grate in the main combustion chamber, as larger ones Particles (usually larger than 0.5 mm) then remain on the grate and 100% burnout is also not achieved. In addition, these are grate bars unrefrigerated and burn up over time.

The invention improves the boiler of the type outlined above to the effect that that there is practically 100% burnout, that there is a risk of burning is removed by grate bars and that eventually higher flame temperatures through less excess air can be made possible, thereby increasing the efficiency of the boiler is increased significantly.

This is achieved according to the invention in that the coiled tubing is wound in the main combustion chamber at a distance that the gaps so formed between the individual turns of the coil are closed at the top and at the sides, while they are open at the bottom and the coiled tubing here forms the grate that below the coil is provided with an ash chamber, and that the ash chamber has a secondary air inlet owns. With such a design, the walls of the main combustion chamber are at the top and protected on the sides against overheating by the flowing heat transfer fluid. Therefore, brickwork or the like is no longer required here. Here is enough for example an insulating pack made of rock wool. The grate bars themselves are also opposite to protected from heat, as it is protected from the heat transfer fluid are flowed through and also by the secondary air flowing in from below be cooled further. This secondary air has the further advantage of that they may have fallen on the grate larger parts of the at least predominantly Supply the required combustion oxygen to fuel burning on the fly and these parts, depending on their size, more or less upwards into the area of the Take the flame with you. The secondary air intake is easiest from one in the den Burner-bearing face provided ash flap formed below the grate, which can be opened more or less depending on the secondary air requirement. That Induced draft fan, which is connected downstream of the boiler, ensures that secondary air is here can occur to a sufficient extent, since the boiler is operated with negative pressure. Basically, the coiled tubing can in the area in which they the Grate bars form, run evenly. However, since this is relatively expensive to manufacture is, the roller coil runs in the main combustion chamber as well as in the afterburning chamber preferably along a helical line, that is, along one on a circular cylinder surface evenly rising line.

Basically, the can practically through the lining inside it helically delimited main combustion chamber laterally offset from the afterburning chamber, for example deeper be arranged as the latter. From constructive However, for reasons and simplicity of construction, it is preferred that both Combustion chambers run coaxially in alignment. In this case, the Ash chamber below that formed by part of the coil in the main combustion chamber The grate is deeper than the rest of the kettle.

The burner for the supporting and holding flame is preferably central arranged in its front wall. Its nozzle is preferably surrounded by a jacket, through which the combustion air supplied by a fan for the burner flame flows coaxially with the latter. Again, surrounding this jacket is advantageous a spiral inlet duct is provided for secondary combustion air which swirls spirally flows axially into the main combustion chamber. The spiral inlet channel forms advantageous at the same time the fuel inlet channel. In the invention, the throttle is preferred of a tightly wound, open in the middle, through which the liquid flows Formed coil spiral, which separates the main combustion chamber from the afterburning chamber. In this way, the throttle is also cooled and there is a risk of overheating of the same, which could occur in the manufacture of refractory material is avoided.

The gap between the individual turns of the helix in the main combustion chamber can be closed, for example, that the coil with a sufficient refractory sheet metal lining is deposited. They are preferred but closed by welded steel strips, which each to both Sides are welded to the corresponding pipe section of the helix. The width of the closed gap and thus also the grate gap is preferably about 1) - 20 mm.

Another option is the gaps between the turns of the helix to be closed on the sides and on the top of the main combustion chamber for example, that there the tube forming the helix is pressed in such an oval manner is that the largest extension of the pipe cross-section in the upper and lateral Areas of the coiled tubing in the longitudinal direction of the boiler, while there where the coil forms the grate, is perpendicular to the longitudinal direction of the boiler.

When the fuel to be burned has a relatively large proportion contains larger particles, their combustion is preferably promoted by that the top of the grate is covered with plates made of refractory mineral material, such as fireclay, is covered, each gap between them for the secondary air passage set free.

If you use flat plates for this, they are due to the curvature of the grate on each pipe is practically only punctiform, so that these plates are very can get hot without the cooled coiled pipe grate locally inadmissible much Apply heat. However, the hot plates have the advantage that they are conspicuous Material that is not or only partially burned quickly due to the addition of radiant heat bring to complete combustion. The gap between the individual plates can be ensured, for example, by appropriate ribs on the edges of the panels be. Equivalent versions for laying the panels with air passage gaps are for example the execution of the plates as slotted plates or as Perforated plates. Also, the outlines of the panels can be, which are normally rectangular are chosen so that they leave corresponding air passage channels free. This is the case, for example, with circular plates.

The following is based on the preferred embodiment of the invention of the drawings as an illustrative example.

Fig. 1 shows schematically a vertical longitudinal section through a boiler according to the invention, but with the sake of clarity from the coils only the cut surfaces are shown.

FIG. 2 shows the view from the left of FIG. 1.

The boiler according to the invention has an outer boiler shell 1, which has a sheet metal jacket on the outside and is filled with rock wool on the inside. in the The rock wool filling is sufficient in the main combustion part of the boiler shown on the left in FIG. 1 of the jacket to the coiled tubing 3 lining the main combustion chamber, which concentrically surrounds the axis 4 of the boiler. In the afterburn compartment shown on the right the rock wool insulation is limited to the inside by a further inner jacket 8. The rock wool insulation also extends over the left end wall 5 of the boiler, while the right end wall 6 of the boiler from a removable Ilohlblechdeckel is formed, which is also filled with rock wool. The boiler can be used for larger Designs may be composed of two parts, which are along the plane 7 in suitable Way connected to each other, for example are flanged together. The main combustion chamber surrounding part of the boiler rests on the ash chamber 9, while the afterburning chamber surrounding boiler part is supported on feet 10.

The left end wall 5 of the boiler carries a burner assembly centrally 11, which provides a supporting and holding flame.

The fuel injection nozzle of the burner 11 and the air supply for the burner flame are surrounded by a cylinder jacket 12, which extends over the center of the wall 5 out into a lining made of refractory ramming compound 13 in the left front wall protrudes. Surrounding the jacket 12 is an annular space in the end wall 5 and the lining 13 are provided.

This annular space can, for example, the fuel material through the nozzle 14 in the form of wood dust or wood shavings by means of a fuel carrying the fuel Air flow are supplied. This air flow then rotates around the jacket 12 and moves at the same time in the axial direction into the interior of the main combustion chamber 16. Here, the fuel carried by the air flow is inwardly through the edge 17 too distracted towards the flame of the auxiliary and holding burner. The annulus 18 through To which the fuel is also supplied, secondary combustion air can also be fed via a nozzle 20 are fed.

Through the end wall 5 and the lining 13 also extends a viewing opening 21 with a viewing flap 22. The main combustion chamber 16 is from the Surrounding coiled tubing coil 3 wound at a distance. In the top and side Areas are the individual turns of this pipe winding through welded joints Square iron bars in the format of, for example, 15 x 5 mm to form a rigid jacket connected with each other. In the lower area, that is to say in the lower area indicated in FIG. 2 Angle range of about 900, are the gaps between the individual tubes of the helix 3, as can be seen from the drawing, open. Since the boiler with a not drawn Induced draft fan is operated, it works with negative pressure, so that between the gaps between each Threads of the coiled tubing 3 in the lower area secondary air can be sucked through from the ash chamber 9 to which this air can again flow by opening the ash flap 24 to a greater or lesser extent. In the drawing, the grate area of the coiled tube coil 3 is with firebricks 26 designed with a low heat content. These stones are shaped and arranged that they leave gaps between them through which the secondary combustion air pour up and burn fuel lying on the hot stones and can swirl upwards into the exhaust gas flow.

Apart from the flap 24 and the gaps between the bars of the Coiled tube 3 is the ash chamber 9 on all sides, as well as through the wall 27 indicated, completed.

The afterburning chamber 30 extends to the right of the main combustion chamber 16, which the burning flue gases through a central opening 31 in the throttle wall 32 flock. The throttle wall 32 consists of a tightly wound from which to warming liquid flowed through coiled tubing spiral.

Thanks to its throttling effect, it ensures very good turbulence of the burned-out and still-burned-out flue gases, so that in the afterburning chamber 30 of the Fuel practical is completely burned. The combustion chamber 30 is surrounded by a tightly wound coiled pipe cylinder 35, which the flowing flue gases until just before the right end plate 6 of the boiler housing leads. There the flue gases are diverted so that they are on the outside of the coil cylinder 35 flow back until they pass through openings of the close to the throttle wall 32 at a distance, Otherwise, however, the outer coiled tube cylinder 36 wound radially without a spacing to the outside and then to the outside of the coiled tube cylinder 36 again flow to the right, where they exit through the flue gas vent 40. The latter is the one mentioned Induced draft fan, not shown, connected downstream.

In the case of the construction described, the inflowing from below Secondary air and, if necessary, also from the firebrick lining 26 outgoing thermal radiation, even relatively coarse components of the fuel are flawless be burned in the main combustion chamber, or at least to such a small size burn down so that they burn completely in the afterburning chamber 30.

The construction according to the invention thus combines the advantages of the previous usual arrangements with a separate main combustion chamber lined with firebrick the advantages of the construction with the heat transfer fluid flowing through it Tube cooled main combustion chamber.

Patent claims:

Claims (5)

Claims: 1. Horizontal boiler for heating during operation non-boiling heat transfer fluid, in particular such oil, in forced circulation with one through a throttle constriction transversely into a main combustion chamber and an afterburning chamber divided elongated housing, with a device for continuous blowing of solid fuel that can be transported in the air stream on one end face, which also a burner for liquid or gaseous fuel to generate a support and holding flame carries, with a peripheral wall of the adjoining this end face the boiler compartment lining the main combustion chamber and cooling the coiled tubing, through which the liquid flows, with a grate in the main combustion chamber which larger components of the fuel should burn out, with one or more Coiled pipe coils in the afterburning chamber and with one downstream of the afterburning chamber Induced draft fan, characterized in that the coiled tubing is in the main combustion chamber is wound at a distance that the gap thus formed between the individual turns of the coil are closed at the top and at the sides, while they are open at the bottom and the coiled pipe spiral here forms the grate, that below the spiral there is an ash chamber is provided, and that the ash chamber has a secondary air inlet. 2. Boiler according to claim 1, characterized in that the throttle of a tightly wound open in the middle, perfused by the liquid Coiled tubing spiral is formed. 3. Boiler according to claim 1 or 2, characterized in that the Gaps between the individual turns of the helix in the main combustion chamber through welded-in Steel strips are closed. 4. Boiler according to one of claims 1 to 3, characterized in that that the top of the grate is covered with sheets of refractory mineral material, each leaving gap between them for the passage of secondary air. 5. Boiler according to one of claims 1 to 4, characterized in that that the coil in the main combustion chamber is an axial extension of or one of the coils is arranged in the afterburning chamber.