COMBUSTION GAS PURIFICATION SYSTEM
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Utility models
- Current Assignee / Owner
- VALMET TECH OY
- Filing Date
- 2025-04-29
- Publication Date
- 2026-05-22
AI Technical Summary
Existing bag filters for cleaning flue gases require significant foundation work, high investment costs, and have a large footprint, with limited flexibility in capacity variation and catalyst replacement during operation.
A flue gas cleaning arrangement with parallel cleaning compartments, incorporating an SCR unit between the filter bag chamber and outlet damper, and optimized ammonia injection and heat exchanger placement, allowing for modular design, reduced space usage, and extended catalyst life.
The solution reduces foundation work and investment costs, enables smaller footprint, facilitates capacity variation, and extends catalyst life without disrupting the cleaning process, while enhancing reaction efficiency and thermal energy recovery.
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Abstract
Description
Title of the invention: BACKGROUND COMBUSTION GAS PURIFICATION ARRANGEMENT
[0001] The invention relates to a combustion gas purification arrangement.
[0002] Bag filters or baghouse dust collectors are commonly used in the cleaning of flue gases from various power plants, reactors, boilers, etc. Generally, bag filters use long cylindrical bags made of woven or felted fabric as the filter medium. A dust-laden flue gas enters the bag filter and flows through the bags, either inwards or outwards, depending on the cleaning method. A layer of dust accumulates on the surface of the filter medium, causing a progressively increasing pressure drop. When a sufficient pressure drop or a predetermined time interval occurs, a cleaning process begins. The cleaning process can be based, for example, on mechanical agitation, reverse gas flow, or high-pressure air pulses. BRIEF DESCRIPTION
[0003] According to a first aspect, a flue gas cleaning arrangement may be proposed comprising at least two parallel cleaning compartments, in which each of said parallel cleaning compartments comprises an inlet damper, an outlet damper, a filter bag chamber and a selective catalytic reduction (SCR) unit, in which, in the cleaning compartment, the SCR unit is arranged between the filter bag chamber and the outlet damper.
[0004] Thus, a flue gas cleaning system requiring less foundation work and having a lower investment cost can be obtained. Furthermore, a smaller footprint may be required. Moreover, the system's modular structure can simplify its production. This is particularly advantageous for the production of systems with variable cleaning capacity, since the capacity can be varied by selecting the number of cleaning compartments. Furthermore, the operating time of the catalyst or catalytic elements in the SCR unit can be extended and exhausted without compromising the cleaning process, as they can be easily replaced, cleaning compartment by cleaning compartment, while the flue gas cleaning system continues to operate in the remaining cleaning compartments.
[0005] Inventive embodiments are also disclosed in the description and drawings of this patent application. The inventive content may also consist of several separate inventions, particularly if the invention is examined in light of explicit or implicit subtasks or in view of the advantages or groups of advantages obtained. The features of the various embodiments of the invention may, within the framework of the basic inventive idea, be applied to other embodiments.
[0006] Various embodiments of the first aspect may include at least one feature of the following paragraphs:
[0007] In one embodiment, the ammonia injection unit is arranged between the filter bag chamber and the selective catalytic reduction (SCR) unit in the purification compartment.
[0008] One advantage lies in the fact that, since the reactant is introduced into the combustion gas just before the SCR unit, the percentage of the reactant entering the SCR unit and thus participating in the reactions taking place there can be maximized. Furthermore, the flow characteristics of the reactant in the arrangement do not need to be modeled or simulated, as the flow path of the reactant to the SCR unit can be very simple.
[0009] In one embodiment, the ammonia injection unit is arranged between the inlet register and the filter bag chamber in the purification compartment.
[0010] One advantage is that the reactant has sufficient time to mix with the combustion gas before the reactions take place in the SCR unit, which can intensify said reactions and the purification of the combustion gas.
[0011] In one embodiment, the ammonia injection unit is arranged in front of the inlet register.
[0012] One advantage is that the reactant has sufficient time to mix with the combustion gas before the reactions take place in the SCR unit, which can intensify said reactions and the purification of the combustion gas.
[0013] In one embodiment, the purification compartment includes a heat exchanger arranged after the filter bag chamber and before the ammonia injection unit.
[0014] One advantage lies in the fact that an optimal temperature for the reactions taking place in the SCR unit can be reached, and therefore the purification of the combustion gas can be stimulated or optimized.
[0015] In one embodiment, the arrangement includes a second heat exchanger arranged after the outlet register.
[0016] One advantage lies in the fact that the thermal energy of the combustion gas can be recovered and thus the environmental and economic efficiency of the arrangement can be increased.
[0017] In one embodiment, the second heat exchanger is configured to receive the combustion gas from at least two parallel purification compartments, possibly from all parallel purification compartments in the arrangement.
[0018] One advantage lies in the fact that the number of secondary heat exchangers and therefore the related investment cost can be reduced.
[0019] In one embodiment, the ammonia injection units and the SCR units are arranged on the same support structure as the bag filter compartments.
[0020] One advantage lies in the fact that a smaller footprint of the plant may be required compared to solutions in which the bag filter compartments are located on a support structure separate from that of the ammonia injection units and the SCR units.
[0021] In one embodiment, the ammonia injection units and the SCR units are arranged at least partly above the upper horizontal level of the bag filter compartments.
[0022] One advantage lies in the fact that the size of the arrangement can be reduced.
[0023] In one embodiment, the ammonia injection units and the SCR units are arranged at least partly below the upper horizontal level of the bag filter compartments.
[0024] One advantage lies in the fact that the use of space in the support structure can be improved.
[0025] In one embodiment, the ammonia injection units and the SCR units are arranged at least partly below the lower horizontal level of the bag filter compartments.
[0026] One advantage lies in the fact that the size of the arrangement can be reduced.
[0027] In one embodiment, the bag filter compartments are grouped into at least two groups of filter bag chambers, and the ammonia injection units and the SCR units are arranged at least in part between said groups of bag filter chambers of bag dust collector.
[0028] One advantage lies in the fact that the use of space in the support structure can be improved.
[0029] In one embodiment, the input register is a blade register, such as a single blade register.
[0030] One advantage lies in the fact that the blade register has a simple structure and can provide improved flow characteristics.
[0031] In one embodiment, the output register is a poppet register, such as a single poppet register.
[0032] One advantage lies in the fact that an output register with a long-term life cycle and robust construction can be obtained.
[0033] Based on the foregoing, it should be noted that different embodiments mentioned in the paragraphs above can be combined in any appropriate way to implement the present invention. BRIEF DESCRIPTION OF THE FIGURES
[0034] Certain embodiments illustrating this disclosure are described in more detail in the accompanying drawings, in which
[0035] [Fig. 1] illustrates a combustion gas purification arrangement,
[0036] [Fig.2] illustrates another arrangement for purifying combustion gases,
[0037] [Fig.3] illustrates a third arrangement for purifying combustion gases, and
[0038] [Fig.4] is a schematic view of a combustion gas cleaning arrangement in partial cross-section.
[0039] In the figures, some embodiments are shown in a simplified manner for clarity. Similar parts are marked with the same reference numbers in the figures. DETAILED DESCRIPTION
[0040] Figure 1 illustrates a flue gas cleaning arrangement. The flue gas cleaning arrangement 100 is intended to clean the flue gases created in any combustion furnace or industrial application. The source of the flue gas may be a combustion plant, such as a coal, wood, gas, or oil-fired combustion plant; a reactor, such as a fluidized bed reactor or grate furnace; or a boiler, such as a waste heat boiler, for example.
[0041] The flue gas cleaning arrangement 100 comprises three parallel cleaning compartments aa, 1b and le. Each of the cleaning compartments aa, 1b, le comprises an inlet register 2, an outlet register 3, a filter bag chamber 4 and a selective catalytic reduction (SCR) unit 6.
[0042] The filter bag chamber 4 comprises a plurality of bags 11 (shown in [Fig. 4]), generally from 50 to 500 bags. The length of the bag 11 is generally from 6 to 10 meters and its diameter is from 100 to 200 mm.
[0043] The purification compartment la, 1b, le is configured so that the SCR unit 6 is arranged between the filter bag chamber 4 and the outlet register 3, i.e. of a clean gas side of the scrubbing compartment. In one embodiment, as shown in [Fig. 1], the arrangement includes an ammonia injection unit 5 which is provided between the filter bag chamber 4 and the SCR unit 6. In other words, each of the three scrubbing compartments a to b includes, in the direction of combustion gas flow, the inlet damper 2, the filter bag chamber 4, the ammonia injection unit 5, the SCR unit 6 and the outlet damper 3.
[0044] It should be noted that the number of parallel-arranged purification compartments can vary from two to dozens of compartments, generally being selected in a range of 3 to 10. The meaning of "parallel-arranged purification compartments" does not necessarily mean that the purification compartments are arranged or fit physically side by side, but that the combustion gas to be purified by the arrangement 100 is divided into parts and that each of the parallel-arranged purification compartments purifies one of said parts.
[0045] The ammonia injection unit 5 is configured to add and mix a reagent to the combustion gas to be introduced into the SCR unit 6. The reagent generally comprises anhydrous ammonia (NH3), aqueous ammonia (NH4OH), and / or urea (CO(NH2)2). The reagent reacts with nitrogen oxides (NOx) in the combustion gas with the aid of a catalyst in the SCR unit 6 and produces diatomic nitrogen (N2) and water (H2O).
[0046] In some embodiments, the ammonia injection unit 5 comprises one or more nozzles, arranged perforated pipes, etc. through which the reagent is injected into the combustion gas.
[0047] In one embodiment, as shown in [Fig.1], the ammonia injection unit 5 is arranged after the filter bag chamber 4 and before the SCR unit 6.
[0048] In one embodiment, a heat exchanger 7 is arranged after the filter bag chamber 4 and before the ammonia injection unit 5 in the purification compartment 1a, 1b, arranged parallel to it. In another embodiment, the heat exchanger 7 is arranged between the ammonia injection unit 5 and the SCR unit 6. The heat exchanger 7 is configured to heat the combustion gas to a sufficient or optimal temperature for the reactions taking place in the SCR unit 6.
[0049] In one embodiment, the SCR 6 unit comprises one or more banks of honeycomb catalytic blocks through which the combustion gas is to flow. It should be noted, however, that other structures and shapes known in the art are also possible.
[0050] In one embodiment, the arrangement 100 includes a second heat exchanger 8 which is arranged after the outlet damper 3 to receive the purified combustion gas in the SCR unit 6. In one embodiment, each of the compartments The parallel-arranged purification compartments 1a, 1b, and 1b include their own second heat exchanger 8. In another embodiment, a second heat exchanger 8 receives the combustion gas from at least two parallel-arranged purification compartments 1a, 1b, and 1b. In yet another embodiment, as shown in [Fig. 1], a second heat exchanger 8 is configured to receive the combustion gas from all the parallel-arranged purification compartments 1a, 1b, and 1b of arrangement 100.
[0051] In one embodiment, the inlet damper 2 is a reed damper, such as a single-reed damper, also called a butterfly damper or wafer damper. However, another type of damper may be used as the inlet damper. By closing and opening the inlet damper 2, the flow of combustion gas into the corresponding scrubbing compartment 1a, 1b, and 1e can be stopped and allowed, respectively.
[0052] In one embodiment, the outlet damper 3 is a flapper damper, such as a single flapper damper. However, another type of damper may be used as the outlet damper. By closing and opening the outlet damper 3, the flow of combustion gas from the corresponding scrubber compartment la, 1b, le can be stopped and allowed, respectively. The scrubber compartment la, 1b, le can be isolated from the rest of the arrangement 100 by closing both the inlet damper 2 and the outlet damper 3. This may prove useful during certain inspection and maintenance work.
[0053] In one embodiment, all the purification compartments arranged in the combustion gas purification arrangement have an identical or at least substantially identical purification capacity.
[0054] Figure 2 illustrates another flue gas cleaning arrangement. In one embodiment, such as that shown in Figure 2, the ammonia injection unit 5 is located upstream of the filter bag chamber 4, but downstream of the inlet damper 2 in the cleaning compartment 1a, 1b, 1e. Thus, the flue gas introduced into the filter bag chamber 4 is already mixed with the reagent. The heat exchangers 7 arranged between the BHF compartments 4 and the SCR units 6 may be included in the embodiment shown in Figure 2, but this is not mandatory in all embodiments.
[0055] Figure 3 illustrates a third arrangement for cleaning combustion gases. In one embodiment, the ammonia injection unit 5 is provided upstream of the inlet registers 2.
[0056] In one embodiment, the ammonia injection unit 5 is configured to introduce and mix the reagent with the combustion gas, which is then divided and introduced into at least two purification compartments.
[0057] In one embodiment, as shown in [Fig. 3], the ammonia injection unit 5 is configured to introduce and mix the reagent with the combustion gas, which is then divided and introduced into all the cleaning compartments 1a, 1b, 1e of the arrangement. In other words, a single ammonia injection unit 5 can supply the reagent necessary for the combustion gas cleaning process carried out in the arrangement 100.
[0058] In one embodiment, each of the purification compartments la, 1b, le of the arrangement is provided with an ammonia injection unit arranged in front of the corresponding inlet register 2.
[0059] In one embodiment, the purification compartment la, 1b, le is provided with a first ammonia injection unit 5 arranged before the filter bag chamber 4, as shown in Figures 2 and 3, and a second ammonia injection unit 5 arranged after the filter bag chamber 4, as shown in [Fig.1].
[0060] In one embodiment, the ammonia used in the flue gas cleaning arrangement 100 is at least partly already introduced into the flue gas source, i.e. before the flue gas enters the flue gas cleaning arrangement 100. Despite this, the flue gas cleaning arrangement 100 may include ammonia injection units 5 as described in this description, if necessary.
[0061] Fig. 4 is a schematic view of a combustion gas cleaning arrangement in partial cross-section.
[0062] In one embodiment, the parallel purification compartments are arranged on the same support structure 9 as the filter bag chambers 4. The term "support structure" here refers to assemblies and structures, such as beam structures, whose main or secondary function is to support the filter bag chambers 4. It should be noted that only a part of the support structure 9 is shown in [Fig.4].
[0063] In some embodiments, as shown in Figures 1 to 3, the bag filter compartments 4 are arranged in a row. In one embodiment, the bag filter compartments 4 are grouped into at least two groups of filter bag chambers. In one embodiment, as shown in [Fig. 4], the bag filter compartments 4 are grouped into two groups of filter bag chambers 10a, 10b which are inverted relative to each other on either side of an imaginary dividing plane D. The embodiment shown in [Fig. 4] comprises six purification compartments in total, such that each of the groups of filter bag chambers 10a, 10b comprises three purification compartments. It should be noted that the number of purification compartments arranged in filter bag chamber groups can vary depending on, for example, capacity requirements and available space.
[0064] An intermediate conduit 14 is located between the groups of filter bag chambers 10a, 10b to provide space for various components, such as the outlet register 3. In one embodiment, the ammonia injection units 5 and the SCR units 6 are arranged at least partly between said groups of filter bag chambers 10a, 10b, for example, at least partly in the intermediate conduit 14.
[0065] In another embodiment, the intermediate conduit 14 is located on the side of the filter bag chamber groups.
[0066] In one embodiment, the ammonia injection units 5 and the SCR units 6 are arranged at least partly above the upper horizontal level U of the bag filter compartments 4. In one embodiment, said components are placed above said upper horizontal level U.
[0067] In one embodiment, the support structure 9 includes a roof structure 12, under which is a technical room 13, and the ammonia injection units 5 and the SCR units 6 are arranged at least in part in said technical room 13.
[0068] In one embodiment, the ammonia injection units 5 and the SCR units 6 are arranged at least partly below the upper horizontal level U of the bag filter compartments 4. In one embodiment, said components are placed below said upper horizontal level U.
[0069] In one embodiment, the ammonia injection units 5 and the SCR units 6 are arranged at least partly below the lower horizontal level L of the bag filter compartments 4. In one embodiment, said components are placed below said lower horizontal level L, for example, below the bags 11.
[0070] In the embodiment shown in [Fig.4], the ammonia injection unit 5 is arranged to introduce the reagent into the combustion gas F just after the heat exchanger 7. In one embodiment, the ammonia injection unit 5 is arranged to introduce the reagent into the combustion gas F just before the SCR unit 6, as on or above the SCR unit as shown by the dotted line 5 in [Fig.4].
[0071] In addition to the ammonia injection units 5 and the SCR units 6, at least one of the inlet registers 2, outlet registers 3, heat exchangers 7 and the second heat exchanger(s) 8 may be arranged at least partly above the upper horizontal level U, at least partly below the upper horizontal level U and / or at least partly below the lower horizontal level L.
[0072] In a solution, the ammonia injection units 5 and the SCR units 6 are arranged in another support structure (not shown) which is separate from the support structure 9 of the bag filter compartments 4. However, this solution is not an embodiment of the invention.
[0073] The invention is not limited to the embodiments described above, but many variations are possible within the framework of the present inventive concept. Within the framework of the inventive concept, the attributes of the different embodiments and applications may be used in conjunction with, or in place of, the attributes of another embodiment or application.
[0074] The drawings and associated description are solely intended to illustrate the idea of the invention. REFERENCE SYMBOLS
[0075] 1 purification compartment
[0076] 2 input register
[0077] 3 output register
[0078] 4 filter bag chamber
[0079] 5 ammonia injection units
[0080] 6 SCR units
[0081] 7 heat exchanger
[0082] 8 second heat exchanger
[0083] 9 support structure
[0084] 10 group of filter bag chambers
[0085] 11 bags
[0086] 12 roof structure
[0087] 13 technical room
[0088] 14 intermediate conduit
[0089] 100 arrangement
[0090] D division plan
[0091] F combustion gas
[0092] The lower horizontal level
[0093] U upper horizontal level
Claims
Demands
1. A flue gas cleaning arrangement (100) comprising at least two parallel-arranged cleaning compartments (la, 1b, le), wherein each of said parallel-arranged cleaning compartments (la, 1b, le) comprises an inlet damper (2), an outlet damper (3), a filter bag chamber (4), and a selective catalytic reduction (SCR) unit (6), where, in the cleaning compartments (la, 1b, le), the SCR unit (6) is arranged between the filter bag chamber (4) and the outlet damper (3), the flue gas cleaning arrangement (100) further comprising an ammonia injection unit (5), characterized in that the ammonia injection unit (5) and the selective catalytic reduction units (6) are arranged in the same structure support (9) than the bag filter compartments (4),and that - the ammonia injection unit (5) and the selective catalytic reduction (SCR) units (6) are arranged at least partly above the upper horizontal level (U) of the baghouse filter compartments (4).
2. Arrangement as claimed in claim 1, wherein - the ammonia injection unit (5) is arranged between the filter bag chamber (4) and the selective catalytic reduction (SCR) unit (6) in the purification compartment (the - If).
3. Arrangement as claimed in claim 1, wherein - the ammonia injection unit (5) is arranged between the inlet register (2) and the filter bag chamber (4) in the purification compartment (the - If).
4. Arrangement as claimed in claim 1, wherein - the ammonia injection unit (5) is arranged in front of the input register (2).
5. Arrangement as claimed in one of the preceding claims, in which - the purification compartment (the - If) arranged in parallel includes a heat exchanger (7) arranged after the filter bag chamber (4) and before the ammonia injection unit (5).
6. Arrangement as claimed in the preceding claim, comprising - a second heat exchanger (8) arranged after the outlet register (3), optionally configured to receive the combustion gas from at least two scrubbing compartments (the - If) arranged in parallel.
7. Arrangement as claimed in any one of the preceding claims, wherein - the ammonia injection units (5) and the selective catalytic reduction (SCR) units (6) are arranged at least partly below the upper horizontal level (U) of the bag filter compartments (4), possibly at least partly below the lower horizontal level (L) of the bag filter compartments (4).
8. Arrangement as claimed in any one of the preceding claims, wherein - the purification compartments (the - If) are grouped into at least two groups of filter bag chambers (10a, 10b), and - the ammonia injection units (5) and the selective catalytic reduction (SCR) units (6) are arranged at least in part between said groups of filter bag chambers (10a, 10b).
9. Arrangement as claimed in any one of the preceding claims, wherein - the ammonia injection unit (5) is configured to add to the combustion gas - anhydrous ammonia (NH3), aqueous ammonia (NH4OH), urea (CO(NH2)2)