EP4311981A1 - Thermal oil biomass boiler - Google Patents

Abstract

Thermal oil biomass boiler 1 having a horizontally extending first train 10, at least one horizontally extending first coiled tubing 20 for conducting thermal oil 2, the first coiled tubing 20 being arranged within the first train 10 and forming a horizontally extending interior 22, a biomass burner 30 which generates a horizontal flame 32 which extends into the interior 22 of the first coiled tubing 20, the first coiled tubing 20 having lower coiled tubing sections 24, 26 and gaps 28 which are dimensioned in this way being present between two adjacent lower coiled tubing sections 24, 26 that ash 34 from the biomass burner 30 can fall through.

Description

1. Technical area

The present invention relates to a thermal oil biomass boiler for heating thermal oil by burning biomass, such as wood pellets, wood chips or other solid fuels, especially for oven systems. In particular, the present invention relates to a thermal oil biomass boiler, which is designed to be particularly safe due to its design.

2. State of the art

In larger craft and industrial oven systems, thermal oil can be used as a heat transfer medium. Thermal oil has the advantage that it can be heated without pressure to temperatures of 300°C and above, which are required in oven systems.

As a rule, the thermal oil is heated in a fired boiler by burning oil, gas or biomass, such as wood pellets or wood chips, and then fed to the thermal oil ovens using a ring line made up of flow and return lines and an electric pump. The heated thermal oil leaves the boiler through a flow line, flows through the ovens, heats them to the desired temperature and cools them down in the process. The cooled thermal oil is fed via a return line to the fired boiler, which heats the thermal oil again.

Oil- or gas-fired thermal oil boilers are known from the prior art. In Fig. 1 Such an oil- or gas-fired three-pass thermal oil boiler 100 is shown according to the prior art, which is designed in a so-called "lying" design. In this horizontal design, an oil or gas burner 130 produces a horizontal flame 132, which extends into a first flue 110 in order to heat thermal oil, which flows through a first coiled pipe 120, by radiation and convection. Here, the oil or gas burner 130 is attached to an end wall 172 of the thermal oil boiler 100. At the end of the first train 110, the flue gases are diverted through 180° into a second train 150, which passes through an annular gap between the first coiled pipe 120 and a second coiled tubing 140 located further out. At the end of the second train 150, the flue gases are again diverted by 180° into a third train 160, which is formed by an annular gap between the second coiled pipe 140 and an outer wall 170 of the thermal oil boiler 100. At the end of the third train 160, the flue gases flow to a flue gas outlet 174 of the thermal oil boiler 100. The thermal oil to be heated by the thermal oil boiler 100 flows through an inlet 123 into the second, outer, colder tube coil 140. It then flows from the second coiled tubing 140 into the first, inner, hotter coiled tubing 120. Finally, the heated thermal oil flows out of the thermal oil boiler 100 from the outlet 122 at the end of the first coiled tubing 120 and into the flow of a thermal oil circuit (not shown). The coiled tubing 120, 140, together with the three flues 110, 150, 160, heat the thermal oil according to the countercurrent principle in order to achieve an optimized heat transfer from the flame 132 and the flue gases to the thermal oil. However, such a horizontal oil- or gas-fired thermal oil boiler 100 cannot in principle be fired with biomass, for example using a biomass burner, since automatic ash removal is not possible due to the design. However, such ash removal is absolutely necessary for a thermal oil biomass boiler in order to ensure its uninterrupted operation in continuous fire mode. The combustion of biomass inevitably produces ash, which would quickly accumulate in a thermal oil boiler without automatic ash removal. After a short time, a classic 3-pass boiler, which is optimal for gas or oil burner operation, would be clogged with ash and would quickly have a performance deficit at the expense of efficiency due to heating surfaces covered with ash.

Conventional thermal oil biomass boilers therefore usually have a so-called grate combustion system, in which a certain amount of biomass, for example wood pellets, wood chips or other solid, preferably renewable fuels, is placed on a grate in the lower area of a vertically aligned, so-called "standing" Boiler burns under controlled air supply. Such a standing thermal oil biomass boiler with grate firing is, for example, from the publication DE 2020 10005458 U1 known. In such a vertical thermal oil biomass boiler, the thermal oil to be heated is guided in coiled pipes, which are usually aligned vertically around the combustion chamber in the boiler and thereby form a vertical channel for the flue gases. Due to the grate firing, such thermal oil biomass boilers have a large mass and require a large bed of currently burning biomass, which is why such a thermal oil biomass boiler can only be regulated comparatively slowly. Such thermal oil biomass boilers usually have a mass with a sufficiently large heat storage capacity, which continues to radiate onto the coiled tubing after the firing is switched off and could lead to an increase in the film temperature of the thermal oil when the thermal oil is standing. However, the film temperature of the thermal oil in the biomass boiler must not be exceeded, for example to prevent thermal decomposition of the thermal oil or cracking in the heat exchanger tubes.

A further complicating factor is that the ember bed of the burning biomass ensures additional heat input even after the thermal oil biomass boiler has been switched off.

Therefore, such a standing thermal oil biomass boiler with grate firing, especially with the thermal outputs required for commercial or industrial oven systems, requires an active emergency cooling system for safety reasons. This active emergency cooling system prevents the biomass boiler from overheating in the event of a malfunction in the system, e.g. if the pump for circulating the thermal oil fails, which could have fatal consequences. However, such an emergency cooling system is technically complex, cost-intensive and maintenance-intensive. It usually includes a redundant pump station, a thermal oil/water heat exchanger, a water tank for the heat exchanger to evaporate water and dissipate heat, appropriate piping systems for steam, water and thermal oil, an emergency power supply, a controller and other components. In the event of a malfunction, the emergency cooling system stops the biomass supply and cools the thermal oil and thus actively the combustion chamber using the water-cooled heat exchanger.

It is therefore the object of the present invention to provide a thermal oil biomass boiler that can be regulated more quickly than thermal oil biomass boilers according to the prior art and in particular offers greater security against overheating of the biomass boiler in the event of a malfunction of the thermal oil system.

3. Summary of the invention

The above-mentioned task is solved by a thermal oil biomass boiler according to claim 1.

In particular, the above-mentioned problem is solved by a thermal oil biomass boiler having a horizontally extending first train; at least one horizontally extending first coiled tubing for conducting thermal oil, the first coiled tubing being arranged within the first train and forming a horizontally extending interior space; a biomass burner that produces a horizontal flame that extends into the interior of the first coiled tubing; wherein the first coiled tubing has lower coiled tubing sections and there are gaps between two adjacent lower coiled tubing sections which are dimensioned such that ash from the biomass burner can fall through.

Due to the horizontal design of the thermal oil biomass boiler and the gaps between two adjacent lower coiled pipe sections for ash removal, a biomass burner with a horizontal flame can be used. Such a biomass burner with a horizontal flame does not have a large burning ember bed of biomass and does not produce large heated masses during operation, as is the case with grate firing. A biomass burner with a horizontal flame can therefore be regulated very quickly. When the supply of biomass is stopped, the heat input into the biomass boiler is very low compared to conventional grate furnaces. Therefore, an emergency cooling system can be dispensed with in a horizontal thermal oil biomass boiler with a biomass burner with a horizontal flame. Accordingly, a thermal oil biomass boiler according to the invention is particularly safe overall, technically less complex, more cost-effective and particularly low-maintenance.

One skilled in the art will understand that the terms "horizontal" and "lying" are used to distinguish vertical or standing boilers and corresponding flames and no mathematically precise alignment is required. Accordingly, the elements of a thermal oil biomass boiler according to the invention can also be at an angle of inclination of up to 45° to the horizontal in order to still be considered “horizontal”.

Due to the gaps between two adjacent lower coiled tubing sections, the ash produced during the combustion of biomass can fall downwards through the coiled tubing and automatically below the coiled tubing be dissipated. The thermal oil biomass boiler according to the invention can therefore be operated in continuous burning mode. Although the efficiency of the heat transfer of the first train decreases due to the gaps between two adjacent lower coiled pipe sections, this thermal disadvantage can be compensated for again by making the first train larger overall or by using additional downstream trains.

The first train preferably has a mechanical ash discharge in the lower region, which is arranged below the first coiled pipe. By arranging the ash discharge below the first coiled pipe, the firing is not affected and mechanical ash discharge is ensured. This enables continuous operation of the thermal oil biomass boiler.

The ash discharge preferably has an ash screw. An ash screw conveys the ash out of the biomass boiler along the first pass through a rotary movement. The ash auger is very robust and mechanically simple compared to other solutions, which increases its reliability.

The first train preferably tapers towards the lower area for ash discharge. Accordingly, a single ash screw can be used to discharge all of the ash from the first pass. By tapering the first train, the ash screw can be made comparatively small.

The thermal oil biomass boiler preferably also has a horizontally extending second train, which is downstream of the first train with regard to the flue gases and has a second coiled pipe for conducting thermal oil, the second coiled pipe being arranged within the second train.

The second puff uses the heat present in the flue gases after the first puff to further heat the thermal oil. With regard to the thermal oil, the second train is preferably connected upstream of the first train in order to preheat colder thermal oil with the colder flue gases before it enters the first coiled pipe of the first train.

The second coiled tubing preferably has lower coiled tubing sections and there are gaps between two adjacent lower coiled tubing sections through which ash from the biomass burner can fall through. Through the gaps between adjacent lower coiled tubing sections, the ash from the biomass burner can fall through the second coiled tubing, as in the first pass, and be automatically removed below the coiled tubing.

In an alternative embodiment, there are no gaps between two adjacent lower coiled tubing sections of the coiled tubing of the second or possibly further trains. In this embodiment, the second, and possibly additional trains, can be provided without automatic ash discharge. In this embodiment, most of the ash is separated in the first pass and the subsequent passes only need to be cleaned by hand from time to time. Due to the higher flue gas velocity in the second pass or subsequent passes, the ash can also preferably be conveyed out of the boiler and separated in subsequent systems, for example in a cyclone and/or a fine dust filter.

The thermal oil biomass boiler preferably also has one or more further trains which are fluidically connected downstream of the second train with regard to the flue gases and which are constructed in accordance with the second train. With a third or even further puffs, the residual heat of the flue gases can be used further to heat up the thermal oil. This is preferably done using the countercurrent principle, whereby the coldest thermal oil of the return is introduced into the coiled pipe of the last, coldest train and then flows through the other trains until it reaches the first, hottest train and is heated to the desired flow temperature.

The second train and further trains preferably each have an ash discharge. This means that the second train and the further trains can also be automatically cleaned of the resulting ash.

The ash discharge of the second or further trains is preferably arranged below or within the respective coiled pipe.

The ash discharge is preferably designed as an ash screw which is arranged within the respective coiled pipe. The ash screw could thus take over the function of the inner mandrel mentioned later and further increase the flue gas velocity. Wear-resistant supports would preferably have to be provided within the coiled tubing for the ash screw so that it can rotate within the coiled tubing without grinding through the coiled tubing.

Preferably, the coil diameters of the second coiled tubing and/or the further coiled tubing are smaller than the coil diameter of the first coiled tubing, preferably smaller than 50% of the coiled diameter of the first coiled tubing, more preferably smaller than 30% of the coiled diameter of the first coiled tubing. The smaller helix diameter increases the flow speed in the second and subsequent trains. This improves the heat transfer from the flue gas to the thermal oil.

Preferably, the first, second and/or further coiled tubing each consist of two or more separate coiled tubings with different diameters within a train, which are screwed into one another and whose upper coiled tubing sections are aligned horizontally to one another, the lower coiled tubing sections of which each have gaps between adjacent coiled tubing sections the ash from the biomass burner can fall through. This design of the coiled tubing improves in particular the radiation-related heat transfer from the flame of the biomass burner to the thermal oil. The radiation from the flame always hits a section of coiled tubing in the radial direction and can be absorbed by this as heat. Nevertheless, in the lower area of the coiled tubing, ash from the biomass burner can fall through the coiled tubing and be automatically transported away underneath for cleaning the train. When using appropriate coiled tubing in the second and subsequent passes, the heat transfer also improves, since a larger heat exchanger surface is available to the flue gas compared to a single-coiled coiled tubing. By using two or more (three, four, five, etc.) additional coiled tubing, the pressure loss for the thermal oil flowing through can also be reduced when the coiled tubing is connected in parallel.

Preferably, the upper coiled tubing sections of the two or more separate coiled tubing lie horizontally against one another. In the upper area of the coiled tubing there are no gaps between the coiled tubing sections, which also improves heat transfer.

Preferably, the coiled tubing of the second train or the coiled tubing of further trains each form a second or further interior space and the thermal oil biomass boiler also has a first or further inner mandrel which is arranged in the second or further interior space. The first and/or the further inner mandrels narrow the flow cross section of the flue gas in the second or further passes in order to increase the flow velocity there and improve the heat transfer.

Preferably, the first inner mandrel and/or the further inner mandrel are designed to be removable from the biomass thermal oil boiler. This allows the inner mandrels to be removed from the corresponding cable for easier cleaning.

The inner mandrels are preferably cylindrical and are formed at their ends in a flow-efficient manner. For example, the inner mandrels could have conical or ellipsoidal head ends.

The thermal oil biomass boiler preferably also has one or more compressed air lances, which are arranged in the flues in order to convey the ash from the biomass burner through the gaps. The ash produced in the trains can be blown from time to time through the gaps in the coiled pipes using the compressed air lances, in order to then be removed from the trains by the ash discharge from the train.

The thermal oil biomass boiler preferably also has a thermal oil flue gas heat exchanger, which is downstream of the first train in terms of flow with regard to the flue gases and which has straight smooth or finned tubes. Such a smooth tube or finned tube heat exchanger can replace the second or further cables or be arranged in addition to these cables. Compared to a coiled pipe, it has a significantly larger heat transfer surface. Could be detrimental more rapid contamination with ash and higher manufacturing costs. The thermal oil-flue gas heat exchanger has smooth tubes or finned tubes, with the finned tubes having an enlarged heat exchanger surface compared to smooth tubes. Smooth tubes, on the other hand, are easier to clean than finned tubes. The flue gas is passed through a chamber of the thermal oil flue gas heat exchanger, in which there is a bundle of essentially straight, smooth or finned tubes. Maintenance or cleaning openings and means for automatic cleaning can also be provided in the chamber.

The first train preferably has a length of 800 mm to 4000 mm.

The thermal oil biomass boiler preferably has a thermal output of more than 100 kW, preferably from 100 kW to 500 kW. The thermal oil biomass boiler is therefore suitable for commercial oven systems.

Preferably, the first and/or the second coiled tubing and/or further coiled tubing is designed for thermal oil temperatures of 300°C to 400°C.

4. Brief description of the characters

Fig. 1

eine dreidimensionale Schnittansicht eines liegenden Thermoölkessels mit Öloder Gasfeuerung nach dem Stand der Technik;

Fig. 2

eine schematische Querschnittansicht einer ersten Ausführungsform eines Thermoöl-Biomassekessels;

Fig. 3

eine schematische Längsschnittansicht des Thermoöl-Biomassekessels der Fig. 2;

Fig. 4

eine schematische Teil-Längsschnittansicht einer zweiten Ausführungsform eines Thermoöl-Biomassekessels;

Fig. 5

eine schematische Querschnittansicht von Rohrwendeln der Thermoöl-Biomassekessels der Fig. 4;

Fig. 6

eine schematische Querschnittansicht einer dritten Ausführungsform eines Thermoöl-Biomassekessels; und

Fig. 7

eine schematische Längsschnittansicht des Thermoöl-Biomassekessels der Fig. 6.

Preferred embodiments of the present invention are shown below with reference to the attached figures. Show:

Fig. 1

a three-dimensional sectional view of a horizontal thermal oil boiler with oil or gas firing according to the prior art;

Fig. 2

a schematic cross-sectional view of a first embodiment of a thermal oil biomass boiler;

Fig. 3

a schematic longitudinal section view of the thermal oil biomass boiler Fig. 2 ;

Fig. 4

a schematic partial longitudinal section view of a second embodiment of a thermal oil biomass boiler;

Fig. 5

a schematic cross-sectional view of coiled tubing of the thermal oil biomass boiler Fig. 4 ;

Fig. 6

a schematic cross-sectional view of a third embodiment of a thermal oil biomass boiler; and

Fig. 7

a schematic longitudinal section view of the thermal oil biomass boiler Fig. 6 .

5. Detailed description of preferred embodiments

Preferred embodiments of the present invention are described in detail below with reference to the accompanying figures.

The Figures 2 and 3 show a first embodiment of a thermal oil biomass boiler 1 with three trains 10, 50, 60. The trains 10, 50, 60 extend essentially horizontally, so that the thermal oil biomass boiler 1 is designed in a horizontal design. A first train 10 extends from the front side 3 of the thermal oil biomass boiler 1 to the back 4 of the same. The first train 10 can have a length of 800 mm to 4000 mm. The thermal oil biomass boiler 1 preferably has a thermal output of more than 100 kW, preferably from 100 kW to 500 kW.

The first train 10 has at least one horizontally extending first coiled tubing 20, which passes thermal oil 2 through the first train 10 in order to heat it up. The first coiled tubing 20 is essentially exposed in order to form the largest possible heat-transferring surface. The first coiled tubing 20 is arranged within the first train 10, preferably in the area of the wall of the first train 10, and forms a horizontally extending interior space 22. A biomass burner 30 is flanged to the front side 3 in order to burn biomass, preferably wood pellets or wood chips, with a controlled supply of air. This creates a substantially horizontal flame 32, which extends into the interior 22 of the first coiled tubing 20. The first coiled tubing 20 therefore preferably surrounds the flame essentially over its entire length in order to absorb the radiant heat generated by it and supply it to the thermal oil. In addition, the first coiled pipe 20 is also heated by convection by the flue gases flowing past.

At the end of the first train 10, the flue gases are deflected by 180° and flow into a second train 50, as shown by arrow 42. The second train 50 serves to further transfer heat from the flue gases to the thermal oil 2. Accordingly, the second train 50 has a second coiled pipe 52, which is arranged within the second train 50, preferably in the area of the wall of the second train 50. The second Coiled tubing 52 is essentially exposed in order to form as large a heat-transferring surface as possible. It can be advantageous here if the wall of the second flue 50, i.e. a casing pipe, is at a distance from the second coiled pipe 52, so that flue gas can also flow through this annular gap at the same time. As a result, the surface of the second coiled tubing 52 can be used even better for heat transfer. If necessary, an inner mandrel 55, as described below, could equalize the speeds inside and outside the second coiled tubing 52. The flue gases flow through the second train 50 from back to front, i.e. from the rear wall 4 to the front wall 3 of the biomass boiler 1. The second train 50 has a smaller cross-section compared to the first train 10, so that in the second train 50 the flow speed of the flue gas is significant is higher than in the first train 10. This increases the heat transfer to the thermal oil 2. The coil diameter D2 of the second coil tube 52 is therefore preferably significantly smaller than the diameter D1 of the first raw coil 20 and is preferably smaller than 50% or smaller than 30% of the coil diameter D1 of the first coiled tubing 20.

At the end of the second train 50, the flue gases are again deflected by 180° and flow into a third train 60, which in turn further cools the flue gases and supplies the heat to the thermal oil 2. This is indicated by arrow 44 in Fig. 2 indicated. The third train 60 has a third raw coil 62, which has a smaller diameter than the first coiled tubing 20. The third coiled tubing 62 can be dimensioned corresponding to the second coiled tubing 52. Preferably, the coil diameter of the third coiled tubing 52 is significantly smaller than the diameter D1 of the first raw coil 20 and is preferably smaller than 50% or smaller than 30% of the coil diameter D1 of the first coiled tubing 20.

The coldest thermal oil 2 of the return line of a thermal oil system (not shown) flows into the coiled pipe 62 of the third, coldest train 60, then through the coiled pipe 52 of the second, warmer train 50 and then through the coiled pipe 20 of the first train 10, which is the hottest is. As a result, the thermal oil 2 is heated to the desired flow temperature of the thermal oil system using the countercurrent principle.

At the end of the third train 60, the flue gases can be passed into further trains (not shown) for further cooling, or the flue gases leave the thermal oil biomass boiler 1 through a flue gas outlet 46 which opens into a chimney (not shown).

The thermal oil biomass boiler 1 has an automatic ash discharge 40, 51, 61, which is preferably arranged in the form of an electrically driven ash screw, each in an area 12 below the raw coil 20, 52, 62. The ash screw conveys the ash to a rotary valve. From there the ash is transported to a collecting container or falls directly into one. The rotary valve serves to seal the firebox from the atmosphere or the boiler house. The trains 20, 50, 60 are tapered towards their lower area 12 towards the ash discharge 40 in order to form an ash box or funnel and to concentrate the ash there. Ash that settles out of the flue gases in each train can fall down due to gravity through the respective coiled pipes 20, 52, 62 or by means of pneumatic compressed air lances 27, 57, 67 (in the Figures 3 and 7 not shown) can be blown down by compressed air introduced from time to time. Cleaning the coiled tubing 20, 52, 62 using sound is also possible. For this purpose, the coiled tubing 20, 52, 62 has lower coiled tubing sections 24, 26, 54, 56, which are spaced apart from one another so that they have gaps 28, 58 through which ash can fall, as indicated by arrow 34. The distance A ₁ of the lower coiled tubing sections 24, 26 of the first coiled tubing 20 is preferably 10 mm to 100 mm and can, for example, correspond to the tube diameter d of the heat exchanger tube of the first coiled tubing 20. The distance A2 of the lower coiled tubing sections of the second 52 and third coiled tubing 62 can also preferably be 10 mm to 100 mm and can, for example, correspond to the tube diameter of the heat exchanger tube of the second or third coiled tubing 52, 62.

Separating plates (not shown) arranged at certain intervals around the ash screw can prevent the flue gases from finding a more streamlined path via the ash pan/funnel. However, the ash should be able to settle in the lower area of the coiled tubing 20, 52, 62, which is why the separating plates should be guided at least to the lower edge of the coiled tubing.

In a further preferred embodiment, the coiled pipes 52, 62 of the second 50 or the further trains 60 can also be built without gaps and without automatic ash discharge. In this embodiment, most of the ash is already separated in the first train 20, so that the subsequent trains 50, 60 only have to be cleaned by hand from time to time. It is also possible that due to a higher flue gas velocity in the subsequent trains 50, 60, the ash remaining in the flue gas is conveyed out of the thermal oil biomass boiler 1 and is separated in subsequent systems, for example in a cyclone and/or a fine dust filter (not shown). .

In another preferred embodiment (not shown), the ash discharge of the subsequent trains 50, 60 is arranged within the respective coiled tubing 52, 62 and is preferably designed as a rotatable ash screw.

In addition to the automatic ash discharges 40, 51, 61, the thermal oil biomass boiler 1 is equipped with cleaning hatches 5, 6, 8 on each train 10, 50, 60, which are easy to open. This means that the trains 10, 50, 60 can also be easily cleaned or inspected manually.

The first 20 and/or second 52 and third coiled tubing 62 are preferably made of corrosion-resistant steel and are designed for thermal oil temperatures of 300 ° C to 400 ° C.

The coiled tubing 20, 52, 62 of the first embodiment are preferably designed to be single-start. They therefore each consist of a single coiled heat exchanger tube, which is bent at a distance A1, A2 so that the gaps 28, 58 are created for the automatic ash discharge.

In another embodiment, the coiled tubing 20, 52, 62 could be designed with two or more threads in order to reduce the pressure loss of the thermal oil flowing through. In particular in the second or third trains 50, 60, the coiled tubing could be provided with two or more threads, since due to the smaller coil diameter, small pipe diameters have to be used, which enable smaller bending radii but have a higher pressure loss. Double-start coiled tubing can also be manufactured in such a way that gaps are created between adjacent coiled tubing sections or not.

The coiled tubing 52 of the second train 50 or the coiled tubing 62 of the third or further trains 60 also each form a second 53, third 63 or further interior space. In these interior spaces 53, 63 removable inner mandrels 55, 65 (in the Figures 3 and 7 not shown) can be arranged in order to reduce the flow cross section for the flue gases in the trains 50, 60, to avoid a hot flow core and to allow the flue gases to flow as close as possible to the coiled pipes 52, 62.

The Figures 4 and 5 show a second embodiment of the thermal oil biomass boiler 1 in which the coiled tubing 70, 80 in the first train 10 - and possibly in the further trains 50, 60 - is designed with two flights, with one course having a smaller coil diameter than the other. Otherwise, the second embodiment corresponds to the first embodiment of the thermal oil biomass boiler 1 described above. The coiled tubes 70, 80 now consist of two coiled tubes 70, 80 twisted into one another, which have different coil diameters D3, D4. In the upper area of the coiled tubing 70, 80, i.e. above the flame 32, the coiled tubing 70, 80 are aligned horizontally to one another, so that gaps 76, 86 for ash removal are created in the lower area between two adjacent coiled tubing sections 72, 74, 82, 84 , as indicated by the arrows 34. The adjacent lower coiled tubing sections 72, 74, 82, 84 are preferably spaced apart from one another by a distance A3, which corresponds to the respective tube diameter d of the heat exchanger tubes of the coiled tubing 70, 80. In this way, the gaps 76, 86 are not created at the expense of the transfer area for the heat radiation of the flame 32, since the transfer area is maximized in this respect. The heat radiation from the flame 32 always hits a coiled tubing 70, 80 in the radial direction, although there are gaps 76, 86 for automatic ash removal available. The upper coiled tubing sections 75, 85 of the two separate coiled tubings 70, 80 preferably lie horizontally against one another in order to also not provide any gaps for the heat radiation of the flame 32. In terms of manufacturing technology, the coiled tubing 70, 80 are wound independently of one another and then twisted into one another so that they are aligned horizontally to one another in the upper region.

The principle of this second embodiment can also be transferred to three-, four-, five- or generally multi-start coiled tubing, with the coiled tubing having at least two different coil diameters, so that gaps for ash removal are formed in the lower region of the coiled tubing.

The Figures 6 and 7 show a further embodiment of a thermal oil biomass boiler 1. This embodiment essentially corresponds to the embodiment of the thermal oil biomass boiler 1 of Figures 2 and 3 , however, the second and third trains 50, 60 were replaced by a thermal oil flue gas heat exchanger 90. The thermal oil flue gas heat exchanger 90 essentially consists of a bundle of smooth or finned tubes 92, which are arranged in a chamber through which the flue gases flow. Here, the smooth or finned tubes 92 are flowed around by the flue gases. The smooth or finned tubes 92 are essentially straight and arranged horizontally in the chamber. They are preferably flowed perpendicular to their longitudinal direction with the flue gases and thermal oil 2 flows through them. Here, the smooth or finned tubes 92 can be fluidically connected to one another in series or parallel to one another or in mixed forms in order to ensure optimal heat transfer from the flue gases to the thermal oil 2. Like in the 6 and 7 shown, the thermal oil flue gas heat exchanger 90 is preferably arranged parallel to the first train 50 and above it. This results in a short, compact design of the thermal oil biomass boiler 1 and a reduction in heat loss.

Furthermore, several thermal oil-flue gas heat exchangers 90 can be arranged one behind the other or one above the other, which are then flowed through one after the other.

The flue gases that have flowed through the first train 10 are introduced into the thermal oil flue gas heat exchanger 90, as indicated by the arrow 42. In the Thermal oil flue gas heat exchanger 90, the flue gases are further cooled and give off their heat to the smooth or finned tubes 92. After flowing through the thermal oil-flue gas heat exchanger 90, the heavily cooled flue gases are introduced and discharged from the thermal oil-biomass boiler 1 via the flue gas outlet 46 into a suitable chimney (not shown).

The thermal oil flue gas heat exchanger 90 can have manual or automatic cleaning if necessary. For this purpose, the thermal oil-flue gas heat exchanger 90 has cleaning openings at suitable locations in order to be able to manually clean the interior of the thermal oil-flue gas heat exchanger 90 from ash. Furthermore, the thermal oil flue gas heat exchanger 90 can have an automatic ash discharge 94, which has, for example, rotating ash screws, pneumatic lances for compressed air introduced from time to time and/or cleaning using sound.

List of reference symbols:

1

Thermal oil biomass boiler

2

Thermal oil

5, 6, 8

Cleaning hatches

10

first move

12

lower area

20

first coiled tubing

24, 26

lower coiled tubing sections

27

Compressed air lance

28

Gaps

22

inner space

30

Biomass burner

32

flame

34

ash

40

Ash removal

42, 44

Arrow

46

Flue gas outlet

50

second move

51

Ash removal

52

second coiled tubing

53

second interior

55

first inner spine

54, 65

lower coiled tubing sections

57

Compressed air lance

58

Gaps

60

third move

61

Ash removal

62

third coil of tubing

63

third interior

65

second inner mandrel

67

Compressed air lance

70

coiled tubing

72, 74

lower coiled tubing sections

75

upper coiled tubing sections

76

Gaps

80

coiled tubing

82, 84

lower coiled tubing sections

85

upper coiled tubing sections

86

Gaps

90

Thermal oil flue gas heat exchanger

92

Smooth or finned tubes

94

Ash removal

100

Thermal oil boiler

110

first move

120

first coiled tubing

122

outlet

123

inlet

130

Oil or gas burners

132

flame

140

second coiled tubing

150

second move

160

third move

170

external wall

172

Front wall

174

Flue gas outlet

D1

Coil diameter of the first coil of tubing

D2

Coil diameter of the second coiled tubing or further coiled tubing

D3, D4

different coil diameters of the separate coiled tubing of the two-start first coiled tubing

d

Pipe diameter

Claims (15)

Thermal oil biomass boiler (1) comprising: a. a horizontally extending first train (10); b. at least one horizontally extending first coiled tubing (20) for conducting thermal oil (2), the first coiled tubing (20) being arranged within the first train (10) and forming a horizontally extending interior (22); c. a biomass burner (30) that produces a horizontal flame (32) that extends into the interior (22) of the first coiled tubing (20); d. wherein the first coiled tubing (20) has lower coiled tubing sections (24, 26) and gaps (28) are present between two adjacent lower coiled tubing sections (24, 26), which are dimensioned such that ash (34) from the biomass burner (30) can fall through . Thermal oil biomass boiler (1) according to claim 1, wherein the first train (10) in the lower region (12) has a mechanical ash discharge (40) which is arranged below the first coiled tubing (20). Thermal oil biomass boiler (1) according to claim 2, wherein the ash discharge (40) has an ash screw. Thermal oil biomass boiler (1) according to one of claims 1 to 3, wherein the first train (10) tapers towards the lower region (12) towards the ash discharge (40). Thermal oil biomass boiler (1) according to one of claims 1 to 4, further comprising a horizontally extending second flue (50). a. with regard to the flue gases, it is downstream of the first train (10) in terms of flow; and b. has a second coiled tubing (52) for conducting thermal oil (2), the second coiled tubing (52) being arranged within the second train (50). Thermal oil biomass boiler (1) according to claim 5, wherein the second coiled tubing (52) has lower coiled tubing sections (54, 56) and gaps (58) are present between two adjacent lower coiled tubing sections (54, 56) through which the ash (34) of the Biomass burner (30) can fall through. Thermal oil biomass boiler (1) according to one of claims 5 or 6, further comprising one or more further trains (60) which are fluidically connected downstream of the second train (50) with regard to the flue gases and which are constructed in accordance with the second train (50). . Thermal oil biomass boiler (1) according to one of claims 5 to 7, wherein the second train (50) and further trains (60) each have an ash discharge (51, 61), which is located below or within the respective coiled pipe (52, 62). is arranged. Thermal oil biomass boiler (1) according to one of claims 5 to 8, wherein the coil diameters (D2) of the second coiled tubing (52) and/or the further coiled tubing (62) are smaller than the coil diameter (D1) of the first Coiled tubing (20), preferably smaller than 50% of the coiled diameter (D1) of the first coiled tubing (20), more preferably smaller than 30% of the coiled diameter (D1) of the first coiled tubing (20). Thermal oil biomass boiler (1) according to one of claims 1 to 9, wherein the first (20), second (52) and / or further coiled tubing (62) each consists of two or more separate coiled tubing (70, 80) with different coil diameters (D3, D4) exist within a train, which are screwed into one another, with their upper coiled tubing sections (75, 85) being aligned horizontally to one another and their lower coiled tubing sections (72, 74, 82, 84) each having gaps (76, 86) between adjacent ones Have coiled tubing sections (72, 74, 82, 84) through which ash (34) from the biomass burner (30) can fall through. Thermal oil biomass boiler (1) according to claim 10, wherein the upper coiled tubing sections (75, 85) of the two or more separate coiled tubings (70, 80) abut one another horizontally. Thermal oil biomass boiler (1) according to one of claims 5 to 11, wherein the coiled tubing (52) of the second train (50) or the coiled tubing (62) of further trains (60) each form a second or further interior space (53) and the Thermal oil biomass boiler (1) further has a first (55) or further inner mandrel (65), which is arranged in the second (53) or further interior (63). Thermal oil biomass boiler (1) according to claim 12, wherein the first (55) and/or the second inner mandrel (65) are designed to be removable from the thermal oil biomass boiler (1). Thermal oil biomass boiler (1) according to one of claims 1 to 13, further comprising one or more compressed air lances (27, 57, 67) which are arranged in the flues (10, 50, 60) to remove the ash of the biomass burner (30). through the gaps (28, 58). Thermal oil biomass boiler (1) according to one of claims 1 to 14, further comprising a thermal oil flue gas heat exchanger (90), which is fluidly connected downstream of the first train (10) with regard to the flue gases and which has straight smooth or finned tubes (92). .

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