Incineration plant for solid fuels

Abstract

The invention relates to an incineration plant for solid fuels and a method for operating an incineration plant, the incineration plant having a combustion chamber (1) with opposing side walls (2) and a roller grate (3) arranged within the combustion chamber (1), the roller grate (3) comprising multiple grate rollers (3.1, 3.2, ..., 3.6), the grate rollers (3.1, 3.2, ..., 3.6) being arranged adjacent to one another, axes (4) of the grate rollers (3.1, 3.2, ..., 3.6) being parallel to each other along a preferably inclined plane (5) and extending between the opposing side walls (2), wherein adjacent grate rollers (3.1, 3.2, ..., 3.6) delimit an intermediate space (6) between them, wherein an intermediate space section (2.2) of at least one side wall (2) being arranged adjacent to at least one intermediate space (6) is connected to a cooling device (8) for providing a coolant to the intermediate space section (2.1).

Description

[0001] The present invention relates to an incineration plant for solid fuels, in particular to an incineration plant for waste or biomass and specifically to a system and method involving a combustion chamber with a roller grate composed of multiple grate rollers.

[0002] In the field of incineration plants for solid fuels, it is common to utilize combustion chambers equipped with grates to facilitate the burning process. Known systems typically involve fixed or moving grates that support the solid fuel as it burns, allowing for the collection of ash and the removal of combustion gases. These grates can be designed in various configurations, such as flat, inclined, or stepped, to optimize the combustion process and ensure efficient fuel consumption.

[0003] A combustion grate may be arranged within the combustion chamber for transporting the solid material and the residues of the combusted solid material (i.e. ash and slag) through the combustion chamber. The solid material and the residues of the combusted solid material form a so-called combustion bed during combustion on top of the combustion grate. The combustion grate is usually arranged within a lower section of the combustion chamber, wherein the combustion grate conveys the combustion bed from an end of a combustion material inlet shaft to a slag container downstream of the combustion grate. The solid fuel is usually supplied to the combustion material inlet shaft by a crane as supply device, wherein the preferably vertically aligned material inlet shaft is arranged above the front of the combustion grate.

[0004] Combustion grates embodied as reciprocating grates are known, but it is also possible that the combustion grate is embodied in a different way, for example as vibrating grate, traveling grate. The present invention relates to incineration plants with a roller grate. The roller grate may comprise multiple grate rollers. Primary air as oxidant gas may be supplied from below the combustion grate to the combustion bed arranged on top of the roller grate, so that the solid material arranged on the roller grate is combusted with the primary air. For example, a wind box for supplying oxidant gas may be arranged below the roller grate for embodying the device, with which the oxidant gas is supplied to the roller grate. The oxidant gas advances from the wind box through or along the grate roller and intermediate spaces between the grate rollers e to the combustion bed on top of the roller grate.

[0005] The main process steps on the grate (in the direction of travel of the solid waste) are: drying of the waste or biomass, devolatilization, combustion, afterburning of the solid residues (mainly ash and slags). Additionally, nozzles may be arranged above the combustion grate within the combustion chamber and / or within at least one path, with which nozzle(s) secondary oxidant gas, tertiary oxidant gas for afterburning or an oxygen-poor carrier gas can be provided to the combustion gases.

[0006] Despite these advancements, several challenges persist, particularly in managing the high temperatures within the combustion chamber and ensuring the longevity and efficiency of the grate system.

[0007] One of the primary issues with existing incineration plants is the thermal stress experienced by the components within the combustion chamber. The intense heat generated during combustion can lead to significant wear and tear on the grate and the surrounding structures. This thermal stress can cause deformation, cracking, and other forms of damage, which necessitates frequent maintenance and replacement of parts. Additionally, the high temperatures can lead to the formation of slag and clinker, which can obstruct the grate and reduce the efficiency of the combustion process. These issues not only increase operational costs but also result in downtime and reduced overall efficiency of the incineration plant.

[0008] Another challenge faced by traditional incineration plants is the effective management of heat energy produced during combustion. While some systems incorporate heat recovery mechanisms, such as heat exchangers or boilers, to capture and utilize the heat energy, these systems are often not optimized for maximum efficiency. The heat recovery process can be hindered by the uneven distribution of heat within the combustion chamber and the difficulty in extracting heat from certain areas.

[0009] Despite the substantial advances in the field of incineration technology, there remains a need for improved systems that can effectively manage thermal stress, enhance the durability of the grate and surrounding structures, and optimize heat recovery processes to increase overall efficiency and reduce operational costs. It is therefore a technical problem underlying the present invention to provide an incineration plant for solid fuels that at least partially overcomes the disadvantages of known systems.

[0010] It is an object of this invention to provide incineration plants that overcomes one or more of the disadvantages of known systems.

[0011] A possible solution for this object is given by the incineration plant and the method with the features of the respective independent claim. Further solutions and preferred embodiments are given in the sub claims and in the preceding and following description, wherein features of the preferred embodiments can be combined with each other in a technical meaningful manner. In particular, features and effects described with regard to the incineration plant can be applied to the method, and vice versa.

[0012] The object is in particular solved by an incineration plant designed for burning solid fuels. This plant includes a combustion chamber, which is the primary area where the burning process occurs. The combustion chamber is defined inter alia by opposing side walls, which are the vertical boundaries on either side of the combustion chamber.

[0013] Within the combustion chamber, there is a roller grate. The roller grate is a mechanical assembly that supports and moves the solid fuel as it burns. The roller grate is composed of multiple grate rollers. These grate rollers are cylindrical components that rotate to facilitate the movement and mixing of the fuel, ensuring efficient combustion.

[0014] The grate rollers are arranged adjacent to one another, meaning they are placed next to each other in a sequence. The axes of the grate rollers are parallel to each other and are aligned along a plane that is preferably inclined. This inclined plane helps in the movement of the fuel through the combustion chamber. The axes extend between the opposing side walls, indicating that the rollers span the width of the combustion chamber. Between each pair of adjacent grate rollers, there is an intermediate space. This intermediate space is the gap or opening that exists between the grate rollers, allowing for the passage of air from below.

[0015] An intermediate space section of at least one side wall, which is the portion of the side wall adjacent to at least one intermediate space, is connected to a cooling device. The cooling device provides a coolant to the intermediate space section. The coolant helps to manage the temperature within the intermediate space section of the side wall and therefore within the combustion chamber, preventing overheating and enhancing the durability and efficiency of the incineration plant.

[0016] The advantages of this design include improved temperature control within the combustion chamber, which can lead to more efficient combustion of the solid fuel and longer lifespan of the plant components due to reduced thermal stress.

[0017] A possible solution for the object is also provided by a method for operating an incineration plant, comprising the following steps: Providing solid fuel onto a roller grate arranged in a combustion chamber of the incineration plant, Advancing the solid fuel through the combustion chamber by rotating multiple grate rollers of the roller grate, Cooling an intermediate space section of a side wall of the combustion chamber with a coolant, wherein the intermediate space section is adjacent to an intermediate space delimited by adjacent grate rollers of the roller grate.

[0018] Accordingly, the method begins by providing solid fuel onto a roller grate arranged in a combustion chamber of the incineration plant. This step ensures that the solid fuel is appropriately positioned for subsequent processing. The solid fuel is then advanced through the combustion chamber by rotating multiple grate rollers of the roller grate. This movement mechanism ensures that the fuel is evenly distributed and continuously fed through the combustion chamber, promoting efficient combustion. The method further includes cooling an intermediate space section of a side wall of the combustion chamber with a coolant. This intermediate space section is adjacent to an intermediate space delimited by adjacent grate rollers of the roller grate. The cooling mechanism helps to manage the temperature within the combustion chamber, preventing overheating and potential damage to the plant's components, thereby directly impacting the durability and longevity of the incineration plant.

[0019] With other words: The present invention proposes that at least one section of the side wall, which is adjacent to the space between the grate rollers, is connected to a cooling device. This cooling device supplies a coolant to the section of the side wall, thereby cooling it. This feature helps in maintaining the temperature of the side wall and prevents overheating, which can enhance the durability and efficiency of the incineration plant.

[0020] In order to even further maintain the temperature of the side wall(s) and prevent overheating, an intermediate section of each of the two side walls arranged adjacent to at least one intermediate space is connected to the cooling device for providing the coolant. According to a preferred embodiment the intermediate space sections of both side walls arranged adjacent to all intermediate spaces are connected to the cooling device, wherein each intermediate space section can be separately connected to the cooling device in parallel or wherein all intermediate space sections of at least one side wall can be connected commonly to the cooling device in series.

[0021] According to an embodiment the cooling device provides a fluid, such as water, as coolant to the intermediate space section. The use of a fluid coolant, particularly water, can effectively absorb and dissipate heat from the intermediate space section, thereby preventing overheating and potential damage to the side walls and other (adjacent) components. This can improve the overall efficiency and longevity of the incineration plant. Furthermore, the introduction of a fluid coolant (instead of a coolant in its steam phase) can facilitate better temperature control within the combustion chamber, ensuring optimal combustion conditions for the solid fuels. This can lead to more complete combustion. Additionally, the use of water as a coolant is advantageous due to its high heat capacity and availability, making it a practical and cost-effective. The specific mechanism of providing a fluid coolant to the intermediate space section also implies the presence of a fluid delivery system, which may include pumps and pipes to ensure the efficient and controlled distribution of the coolant.

[0022] According to a further embodiment the cooling device is part of a heat energy conversation unit. The heat energy conversion unit could be provided by a heat pump and / or a heat exchanger. This embodiment enhances the functionality of the incineration plant by integrating the cooling device into a broader system for heat energy conversion. By doing so, the cooling device not only serves its primary purpose of providing coolant to the intermediate space section of the side wall adjacent to the intermediate space between the grate rollers but also contributes to the overall energy efficiency of the plant. The heat energy conversion unit can utilize the heat extracted by the cooling device, thereby converting it into useful energy, which can be reused within the plant or for other purposes. This integration implies a more efficient use of resources, as the heat that would otherwise be wasted is now captured and repurposed. This embodiment provides a dual function for the cooling device, enhancing the overall sustainability and operational efficiency of the incineration plant.

[0023] According to a further embodiment the heat energy conversion unit is connected at least to one of the following: a heat energy distribution network, a feedwater supply, a combustion gas supply, a flue gas line, a recirculation gas line, a heating installation, a drinking water installation.

[0024] Accordingly, connections between the heat energy conversion unit and various components within the incineration plant is proposed. These connections facilitate the transfer and utilization of heat energy generated within the plant, enhancing its operational efficiency and integration with other systems. The connection to a heat energy distribution network allows for the efficient distribution of generated heat energy to external systems or facilities, optimizing energy use. The feedwater supply connection ensures a continuous supply of temperature controlled water necessary for steam generation or other processes within the plant, maintaining operational stability and efficiency. The combustion gas supply connection provides a steady flow of temperature controlled gases, ensuring consistent fuel burning and energy production. The flue gas line connection enables the safe and controlled removal of temperature controlled exhaust gases produced during combustion, reducing environmental impact and adhering to regulatory standards. The recirculation gas line connection allows for the reuse of certain gases within the plant in a temperature controlled way, improving fuel efficiency and reducing emissions. The heating installation connection facilitates the direct use of generated heat for heating purposes within the plant or connected facilities, enhancing overall energy utilization. Lastly, the drinking water installation connection ensures that heat energy can be used to provide hot water for drinking purposes, adding a practical and beneficial feature to the plant's capabilities. The specific mechanisms of communication between the heat energy conversion unit and these components ensure that the plant can effectively manage and utilize the heat energy generated, leading to improved performance and sustainability.

[0025] According to a further embodiment a main side wall section of at least one of the opposing side walls arranged above the roller grate is connected to a second cooling device. The second cooling device is distinct from the cooling device that is connected to the intermediate space section. By having a separate cooling device for the main side wall section above the roller grate, the plant can achieve more effective and targeted cooling. This separation allows for independent control of the cooling processes in different sections of the incineration plant, which can be crucial for maintaining optimal operating temperatures and preventing overheating in specific areas. The differentiation between the cooling devices also enables that each device can be tailored to the specific cooling requirements of its respective section. For instance, the cooling device connected to the intermediate space section may be designed to handle the intense heat generated in the spaces between the grate rollers, while the second cooling device connected to the main side wall section above the roller grate may focus on dissipating heat from the upper regions of the combustion chamber. This targeted approach can enhance the overall efficiency and longevity of the incineration plant by reducing thermal stress on the components.

[0026] In a further embodiment the heat energy conversion unit and the second cooling device or cooling devices for further sections of the incineration plant, preferably downstream of the combustion chamber are at least indirectly connected to a heat energy distribution network. This connection facilitates the transfer of heat energy from the combustion process to the heat distribution network, enhancing the overall efficiency of the plant. The indirect connection implies that there may be intermediary systems or components that facilitate this transfer, ensuring that the heat energy is effectively utilized and distributed. This integration can lead to a more sustainable and energy-efficient operation, as the excess heat is not wasted but rather repurposed. By incorporating a heat energy distribution network, the plant can achieve better thermal balance and reduce the risk of overheating or thermal stress on the components.

[0027] In a further embodiment the second cooling device is connected to / embodied by a boiler drum or heat accumulator. This connection facilitates the transfer of heat from the cooling device to the boiler drum or heat accumulator, enabling efficient heat management within the plant. The second cooling device, which usually provides water steam to the main side wall section, is designed to enhance the cooling efficiency of the incineration plant. By being connected to a boiler drum or heat accumulator, the second cooling device can effectively utilize the heat generated during the incineration process, converting it into steam or storing it for later use.

[0028] In a further embodiment the intermediate space section is formed by concrete (forming the side wall in the intermediate space section) comprising tubes connected to the cooling device. These tubes can be directly connected to the cooling device, facilitating the provision of coolant to the intermediate space section. The introduction of (refractory) concrete as the material for the intermediate space section offers several advantages, including enhanced structural integrity and durability, which are critical for the operational longevity of the incineration plant. The inclusion of tubes within the concrete ensures efficient and uniform distribution of the coolant, thereby optimizing the cooling process. Alternatively, the intermediate space section of the sidewall may comprise refractory products which are flown through by the coolant. Respective channels or tubes for the coolant may be embodied within the refractory products.

[0029] In a further implementation of the method, the solid fuel is waste or biomass.

[0030] Figure 1 shows a schematic side view of an incineration plant with a combustion chamber, roller grate, cooling device, and heat energy conversion unit.

[0031] Figure 1 illustrates an incineration plant for solid fuels, comprising a combustion chamber 1 with opposing side walls 2. Within the combustion chamber 1, a roller grate 3 is arranged, consisting of multiple grate rollers 3.1, 3.2, 3.3, 3.4, 3.5, and 3.6. These grate rollers .1, 3.2, 3.3, 3.4, 3.5, and 3.6 are positioned adjacent to one another, with their axes 4 parallel to each other along an inclined plane 5, extending between the opposing side walls 2. The adjacent grate rollers 3.1 to 3.6 delimit intermediate spaces 6 between them.

[0032] An intermediate space section 2.1 of at least one side wall 2, adjacent to at least one intermediate space 6, is connected to a cooling device 8. This cooling device 8 is designed to provide a coolant to the intermediate space section 2.1. The cooling device 8 is part of a heat energy conversion unit 7, which includes components such as an evaporator 11, an expansion valve 12, a compressor 13, and a condensor 14. The heat energy conversion unit 7 is connected to a heat energy distribution network 15.

[0033] The cooling device 8 supplies a fluid coolant, such as water, by a pump 10 thorugh a feed line 16 to the intermediate space section 2.1. The coolant absorbs heat from the intermediate space section 2.1 and is then circulated back through return line 17 to the heat exchanger 11, where the absorbed heat is transferred to the heat energy distribution network 15. The cooled fluid is then recirculated back to the intermediate space section 2.1.

[0034] Additionally, a main side wall section 2.2 of at least one of the opposing side walls 2, arranged above the roller grate 3, is connected to a second cooling device 9. This second cooling device 9 is distinct from the cooling device 8 connected to the intermediate space section 2.1. The second cooling device 9 is connected to a boiler drum or heat accumulator, which stores the heat energy collected from the main side wall section 2.2.

[0035] The figure also shows that the intermediate space section 2.1 is formed by concrete comprising tubes 18 connected to the cooling device 8. These tubes 18 facilitate the transfer of coolant through the intermediate space section 2.1, ensuring efficient cooling of the side wall adjacent to the intermediate spaces 6.

[0036] The combustion chamber 1 is designed to advance solid fuel through the chamber by rotating the grate rollers 3.1 to 3.6. The rotation of the grate rollers 3.1 to 3.6 moves the solid fuel along the inclined plane 5, facilitating its combustion. The heat generated from the combustion is partially absorbed by the coolant in the intermediate space section 2.1 and the main side wall section 2.2, which is then utilized by the heat energy conversion unit 7 and the second cooling device 9, respectively.

[0037] In summary, Figure 1 provides a detailed schematic view of an incineration plant with a roller grate system, highlighting the cooling mechanisms integrated into the side walls of the combustion chamber to enhance heat recovery and operational efficiency.Bezugszeichenliste

[0038] 1Combustion chamber 2Side wall 2.1Main side wall section 2.2Intermediate space section 3Roller grate 3.1, 3.2, ..., 3.6Grate rollers 4Axis 5Plane 6Intermediate space 7Heat energy conversation unit 8Cooling device 9Second cooling device 10Pump 11Evaporator 12expansion valve 13Compressor 14Condenser 15Heat Energy distribution network 16Feed line 17Return line 18Cooling pipes

Claims

1. Incineration plant for solid fuels, having - a combustion chamber (1) with opposing side walls (2) and - a roller grate (3) arranged within the combustion chamber (1), the roller grate (3) comprising multiple grate rollers (3.1, 3.2, ..., 3.6), • the grate rollers (3.1, 3.2, ..., 3.6) being arranged adjacent to one another, • axes (4) of the grate rollers (3.1, 3.2, ..., 3.6) being parallel to each other along a preferably inclined plane (5) and extending between the opposing side walls (2), wherein • adjacent grate rollers (3.1, 3.2, ..., 3.6) delimit an intermediate space (6) between them, characterized in that an intermediate space section (2.2) of at least one side wall (2) being arranged adjacent to at least one intermediate space (6) is connected to a cooling device (8) for providing a coolant to the intermediate space section (2.1).

2. Incineration plant according to claim 1, wherein the cooling device (8) provides a fluid, such as water, as coolant to the intermediate space section (2.2).

3. Incineration plant according to claim 1 or 2, wherein the cooling device (8) is part of a heat energy conversation unit (7), in particular a heat pump or heat exchanger.

4. Incineration plant according to claim 3, wherein the heat energy conversion unit (7) is connected at least to one of the following: - to a heat energy distribution network (15), - a feedwater supply, - a combustion gas supply, - a flue gas line, - a recirculation gas line, - a heating installation, - a drinking water installation.

5. Incineration plant according to one of the preceding claims, wherein a main side wall section (2.1) of at least one of the opposing side walls (2) arranged above the roller grate (3) is connected to a second cooling device (9), the second cooling device (9) being different than the cooling device (8) connected to the intermediate space section (2.2).

6. Incineration plant according to claim 3 and 5, wherein the heat energy conversion unit (7) and the second cooling device (9) or cooling devices (8) for further sections of the incineration plant downstream of the combustion chamber (1) are at least indirectly connected to a heat energy distribution network (15).

7. Incineration plant according to claim 5 or 6, the second cooling device (9) being connected to a boiler drum or heat accumulator.

8. Incineration plant according to one of the preceding claims, wherein the intermediate space section (2.2) is formed by concrete comprising tubes connected to the cooling device (8).

9. Method for operating an incineration plant, comprising the following steps: - Providing solid fuel onto a roller grate (3) arranged in a combustion chamber (1) of the incineration plant, - Advancing the solid fuel through the combustion chamber (1) by rotating multiple grate rollers (3.1, 3.2, ..., 3.6) of the roller grate (3), - Cooling an intermediate space section (2.2) of a side wall (2) of the combustion chamber (1) with a coolant, wherein the intermediate space section (2.2) is adjacent to an intermediate space (6) delimited by adjacent grate rollers (3.1, 3.2, ..., 3.6) of the roller grate (3).

10. Method according to claim 9, wherein a fluid, such as water, is supplied to the intermediate space section (2.2) as coolant.

11. Method according to claim 9 or 10, wherein the heat energy obtained from the intermediate space section (2.2) is used to operate a heat energy conversion unit (7).

12. Method according to claim 11, wherein the heat from the heat energy conversion unit (7) is supplied at least to one of the following: - a heat energy distribution network (15), - boiler feedwater, - combustion gas, - flue gas, - recirculation gas, - heating installation, - drinking water.

13. Method according to one of claims 9 to 12, wherein a main side wall section (2.1) of at least one of the opposing side walls (2) arranged above the roller grate (3) is cooled with a different coolant system than used for cooling the intermediate space section (2.2).

14. Method according to claim 11 and 13, wherein the heat from the heat energy conversion unit (7) and the heat from the main side wall section (2.1) or further sections of the incineration plant downstream of the combustion chamber (1) are provided to a heat energy distribution network.

15. The method according to any one of claims 9 to 14, wherein the solid fuel is waste or biomass.

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