Flue gas cleaning system

Abstract

The present application relates to a system or method for removing solid particles and / or gaseous components from a flue gas, said system comprising: two or more filtration chambers (10) comprising a plurality of filtration bags, each filtration bag having a filtration surface at which the particles are separated from a flue gas flow passing through said filtration surface; at least one header comprising clean air at a controlled pressure, the header connected to a clean air supply and in fluid communication with the at least one flow valve; and a first controller configured to control opening and closing of the flow valve in response to a data input indicating that a differential pressure across all filtration chambers of the system has reached a predetermined setpoint. The system uses a first or second controller to control the residence time of the flue gas by: i. Adjusting the pressure of clean air in the header based on the measured time between two consecutive pulses to maintain a constant average residence time of the flue gas across all filtration chambers; and / or ii. Adjusting the individual cleaning frequency of each filtration chamber based on the measurements of the pressure differential and gas flow of each chamber to balance the residence time of the flue gas across all filtration chambers within the filtration system.

Description

[0001] The present application relates to a system and a method for removing solid particles and / or gas components from flue gases by means of a fabric cleaning filter.

[0002] Fabric filter systems (also called bags) are air pollution control devices that remove particulate and gaseous components from air or gases released by industrial plants (e.g. incineration plants, power plants, food processing plants). A typical fabric filter system consists of one or more chambers, each of which includes multiple rows of filters used as filter media - usually called filter bags (or simply "bags"). Particle-laden gas or air enters the fabric filter and is drawn through the bag, either internally or externally, depending on the cleaning method, and accumulates to form a dust layer called a filter cake. The filter cake itself acts as a filter element, where the particles that make up the filter cake capture incoming fine particles from the gas before releasing the gas into the environment. In so-called dry flue gas cleaning systems, absorbents (e.g., slaked lime or sodium bicarbonate) are used in the filter cake to absorb acidic gas components present in the flue gas, such as SO 2 or HCl.

[0003] As the filter cake accumulates on the filter fabric, it becomes increasingly difficult for air or gas to move through the filter, which at a certain point reduces the filter's ability to continue filtering particles. For this reason, it is necessary to clean the fabric filter by removing at least a portion of the filter cake. There are different cleaning methods that can be applied for this purpose, the most common being mechanical vibrators, reverse air and pulse jets.

[0004] Cleaning can be performed "offline" or "online".

[0005] It is usually necessary to have multiple filter chambers so that they can be cleaned one by one. When a filter chamber needs to be cleaned, the filter chamber is isolated from the main air flow. US4500326 discloses such an offline cleaning system, which relates to a method for cleaning fabric filters in each filter chamber of a multi-chamber fabric filter device (especially a dust collector). The filter chambers are cleaned in a fixed order: whenever the pressure difference on the dust collector reaches an upper limit, one of the filter chambers will be isolated, the filter elements therein will be cleaned, and then the isolated filter chamber will be put back into use. When the pressure difference on the dust collector reaches the upper limit again, another filter chamber will be isolated and cleaned. This allows the dust collector to operate continuously and keeps the pressure difference of the dust collector within a relatively narrow pressure difference band. A major disadvantage of offline cleaning is that it usually involves removing the entire filter cake of the chamber, which results in flow resistance losses and poor absorption of fine particles and / or acid gas components over a longer period of time.

[0006] In-line cleaning systems do not require isolation of the filter chamber that needs to be cleaned. The present invention relates to in-line cleaning. In particular, the present application relates to pulse jet filtration systems in which pulses of high pressure air are used to remove filter cake that has accumulated on the filter fabric. In operation, these pulses or bursts of pressurized air cause the filter fabric, which is generally positioned on a cage or frame, to initially dynamically expand, thereby rupturing the particle layer and displacing it from the filter fabric. The discharged particles are generally collected in a hopper at the lower end of the bag filter chamber. Such in-line systems are well known in the art. An example of this general type of filtration system is disclosed in U.S. Patent No. 3,726,066 to Colley et al.

[0007] While it is well established in the art how to clean filter fabrics by pulse jets, there is no consensus on how to best determine the point in time when a particular filter or row of filters should be cleaned - or in other words, determine the optimal time period between subsequent activations of a pulse jet cleaning system for cleaning the filters - which is typically done row by row.

[0008] Some pulse jet cleaning systems employ a periodic cleaning regimen and therefore simply activate pulse jet cleaning at preset intervals. Other systems utilize the pressure differential across the filter media within the baghouse or filter chamber to determine the point in time for activating pulse jet cleaning. The more particles accumulate on the filter media, the more difficult it is to force air through the particle layer (filter cake) and, therefore, the higher the pressure differential created across the filter media. Therefore, systems have been developed to monitor the pressure drop across the fabric filter and institute a periodic cleaning process each time the pressure drop reaches a certain level.

[0009] KR20190081124A discloses a bag filter chamber pulse control system, which includes a pressure measuring unit for measuring the pressure in an inlet pipe, a discharge pipe, a single filter chamber, and a supply pressure. A controller is used to control the pulse according to the information measured by the pressure measuring unit. Therefore, the user can select and apply various operation modes.

[0010] US4507130A discloses a method for controlling the cleaning of a multi-bag fabric filter system, particularly a reverse airflow type, a system and method for controlling the cleaning of an industrial filter system. The cleaning cycles of the various bag filter chambers are staggered in a predetermined manner so that the peak resistance of each bag filter chamber occurs simultaneously with the lower resistance of another bag filter chamber. Due to the deviation of the resistance peak, the pressure drop peak is reduced.

[0011] Independent of the cleaning frequency, the typical operation of pulse jet cleaning is to thoroughly clean the filter by applying a pressure wave strong enough to remove all the cake dust, i.e. the residual cake after the pulse is very small and close to zero. However, as mentioned above, the filter cake also acts as a filter element and a certain amount of particles on the filter medium is required to capture incoming fine particles and absorb gas components that would not otherwise be captured by the bag itself. For example, in a dry flue gas cleaning system, a filter bag with a low residual cake thickness after cleaning absorbs only a small amount of acid gas and it has almost no flow resistance, which means that the residence time of the flue gas is almost zero. As a result, the total acid gas slip through the newly cleaned multi-row bag is very high compared to the multi-row bag that has accumulated thick filter cake since the last cleaning. On the other hand, if the filter cake is too thick, the filtering performance is also impaired. Therefore, the filtration efficiency in the bag filter house depends on the optimal dust layer present on the filter fabric, but for the reasons mentioned above, the nature of the pulse jet cleaning system used in the field is to always operate the filter cake thickness between the minimum value after the pulse and the maximum value just before the next cleaning pulse.

[0012] Furthermore, pulse jet cleaning systems known in the art typically operate at a constant air pressure to clean a row of filters. The main disadvantage of systems using constant air pressure is that they tend to reduce the wear life of the filter fabric and often use excessive energy. This is because the greater the pulse pressure used, the more wear the filter fabric experiences. Therefore, if a constant air pressure is used, it is likely that the air pressure is set too low and the cleaning performance is reduced, or the air pressure is set greater than the pressure required to effectively clean the filter fabric, which places excessive stress on the filter media. Additionally, in the latter case, the system utilizes more energy than is required to complete the cleaning task and is therefore inefficient.

[0013] Finally, in bag filter houses with multiple chambers, there is typically no uniform distribution of gas and particles among the chambers. This results in differences in the filter cake formation rate, average filter cake thickness, and gas velocity (i.e., residence time) of a single filter cake traveling through each chamber. In addition, the residence time of the flue gas in the filter cake also varies for each filter bag or row of filter bags within the filter chamber. These differences in residence time are problematic because some components, especially acid gas components, require a certain amount of time to make contact with the absorbent material. If the residence time varies among all filter rows or filter chambers, full and adequate absorption of these substances cannot be guaranteed.

[0014] Therefore, there is a need for a baghouse pulse jet cleaning method or system that achieves optimal cleaning efficiency, reduces slippage of components absorbed by the filter cake, and increases the wear life of the filter media.

[0015] This problem is solved by the system defined in claim 1 and the method defined in claim 12 of the present application. Preferred embodiments belong to the dependent claims.

[0016] Specifically, the present invention provides a system and method for cleaning flue gas from particulate and / or gaseous components by means of a textile filter in a filter chamber, which maximizes absorption performance while reducing energy consumption and extending the life of the filter. The system and method of the present invention are also well suited for removing and minimizing acid gas components (such as SO 2 ) gas leakage.

[0017] Throughout this application, the following definitions apply:

[0018] The term "flue gas" refers to any kind of gas stream released from an industrial plant, which contains solid particles (such as dust or fly ash) and / or gaseous components that need to be removed before the flue gas is released into the environment. To remove these components, the flue gas passes through conventional or membrane filtration elements, such as filter bags or filter cartridges, which may incorporate permanent or replaceable absorbents in the filter material or in the filtrate (i.e., filter cake), which accumulate on the upstream side of the filter.

[0019] "Residence time" refers to the time required for the gas to pass through the filter cake. This residence time depends on the thickness of the filter cake and the speed of the gas flow.

[0020] The cleaning system used according to the invention comprises a plurality of filters, which may be referred to as "filter bags", "filter fabrics" or "filter media", which are usually arranged in rows. Typically, such a system comprises several cleaning chambers, each of which comprises a plurality of rows of filters. Each filter is cleaned by a cleaning pulse, i.e. a pressurization of compressed air. Typically, the filter bags in a row are pulsed simultaneously.

[0021] The term “cycle time” is used to describe the time required to pulse all the filter bags in a filtration system.

[0022] Particles in the flue gas that cannot pass through the filter will accumulate on the filter surface on the upstream side of the filter. This accumulated mass of particles is called filter cake. In pulse jet cleaning, the intensity of the pulse can be set so that not all filter cake is removed by the pulse. In this case, the filter cake has a static part and a dynamic part: the static part remains on the filter bag after the pulse, while the dynamic part is removed by the pulse and accumulates in the time between two cleaning pulses.

[0023] According to the present invention, there is provided a flue gas cleaning system for removing solid particles and / or gas components from flue gas, the system comprising:

[0024] - two or more filter chambers comprising a plurality of filter bags, each filter bag having a filter surface at which particles are separated from the flue gas flow passing through the filter surface, wherein particles accumulated on the filter surface on the upstream side aggregate into a filter cake;

[0025] at least one header comprising clean air at a controlled pressure, connected to a clean air supply and in fluid communication with at least one flow valve,

[0026] wherein opening of the flow valve causes a pulse of clean air to flow through at least one pulse air conduit to a group of filter bags in a particular filter chamber to expel particles from the filter surface; and

[0027] - a first controller configured to control the opening and closing of the flow valve in response to a data input indicating that a drop in the differential pressure across all filter chambers of the filtration system or across a single filter chamber of the filtration system has reached a predetermined set point.

[0028] Opening of the flow valve will thus trigger a cleaning pulse.Preferably, the flow valve is controlled in response to the occurrence of a pressure drop in the total pressure difference, ie the pressure difference across all filter chambers.

[0029] The key element of the present invention is that the first controller or the second controller is configured to control the residence time of the flue gas by adjusting:

[0030] i. adjusting the pressure of the clean air in the header based on the measured time between two consecutive pulses to maintain a constant average residence time of the flue gas in the filter cake across all filter chambers; and / or

[0031] ii. Adjusting the individual cleaning frequency of each filter chamber based on measurements of differential pressure and airflow in each chamber to balance the residence time of the flue gas in the filter cake as it traverses all the filter chambers within the filtration system.

[0032] Thus, the present invention has identified two aspects which allow improving the cleaning efficiency or "performance" of a flue gas cleaning system in which the cleaning can be performed "online", i.e. during normal operation:

[0033] The first aspect is to adjust the clean air pressure in the header according to the time between two consecutive cleaning pulses (i.e., the cleaning frequency). If the pressure difference on all filters in the filter chamber reaches a given set point, it is common practice to start a cleaning pulse. Although systems in the art have proposed changing the pulse width to achieve a constant pressure difference, the system of the present invention is intended to maintain a constant average residence time of flue gas across all filter chambers by modifying the pressure of the clean air in the header independently of the pressure difference set point. The method is based on the following discovery: for a given total pressure difference set point that triggers the next pulse and a given particle concentration in the flue gas (i.e., upstream of the filter), there is a defined relationship between the clean air pressure and the cleaning frequency. Simply put: in the case of high cleaning pressure, all filter cakes will be removed from the filter bag, resulting in high cleaning efficiency. After the filter cake is completely removed, it will take a long time to gather new (total) filter cakes, which leads to a sufficiently high pressure difference to trigger the next cleaning pulse. Therefore, the cleaning frequency is low. On the other hand, in the case of low cleaning pressure, not all filter cakes are removed (i.e., there will be residual filter cakes on the filter after the pulse), and the pressure difference set point will be reached after a shorter time. In this case, the cleaning efficiency is low and the cleaning frequency is high.

[0034] In view of the above, the system of the present invention uses a controller which is designed to adjust the pressure of the cleaning air in the cleaning tank until the time between two cleaning pulses has reached a given set point. This ensures that in each cleaning cycle (in which each filter bag is cleaned once), the average time that the flue gas spends in a particular filter cake (i.e. the residence time) is constant. There is no need to adjust the pulse width (although it still can, if desired). The above-mentioned disadvantages of a pulse jet cleaning system when operating at a constant air pressure to clean a row of filters can therefore be avoided.

[0035] To improve the quality of control, the pressure of the clean air in the header is preferably further adjusted according to the determined particle concentration in the flue gas and / or the estimated cake bulk density. The cake bulk density can be estimated from cake samples taken from the hopper, ie the location where the particles to be removed are collected.

[0036] The second aspect is to adjust the individual cleaning frequency of each filter chamber according to the pressure difference and gas flow measured for the corresponding chamber. It was found that the ratio between the measured pressure difference and the measured gas flow of a specific filter chamber implicitly indicates the particle concentration in the flue gas ("flue gas load"). Based on this and further based on the knowledge that the speed of cake formation increases with the flow rate of flue gas through the filter chamber and the concentration of particles in the flue gas, the cleaning frequency can be adjusted so that the chamber with fast cake formation will be cleaned more frequently than the chamber with slow cake formation. The average residence time and the cleaning frequency are inversely proportional to each other. Therefore, by controlling the cleaning frequency of a single chamber, the average residence time of the flue gas in the filter of each chamber can also be controlled. This allows balancing the residence time of the flue gas across all filter chambers, which means that the residence time difference between two filter chambers is reduced. Thereby, the cleaning performance of each cleaning chamber can be optimized. In particular, in dry or semi-dry gas cleaning systems, in which absorbent is injected into the flue gas upstream of the filter to absorb acid gas components, the balanced residence time improves the overall acid absorption because chambers with low absorption are avoided.

[0037] Preferably, the pressure of the clean air in the header and the cleaning frequency of each filter chamber are controlled. This results in an optimal residence time for optimal cleaning efficiency and maximum absorption efficiency.

[0038] To regulate the pressure of the clean air in the header, the controller preferably controls the opening and closing of at least one pressure control valve.A preferred type of pressure control valve is a proportional pressure control valve which operates by regulating the pressure set point of the valve, preferably in a continuous manner.

[0039] Therefore, the pressure of the clean air in the header can be adjusted independently of the total pressure difference.

[0040] The system of the present invention is particularly suitable for removing particulate and acid gas components from flue gases. Therefore, it is preferably a dry or semi-dry gas cleaning system, in which an absorbent is injected into the flue gas upstream of the filter to absorb the acid gas components. The absorbent is capable of absorbing acid gas components, such as SO, under the operating conditions of the filter system employed. 2 and HCl. Preferred absorbents are hydrated lime and sodium bicarbonate. After the cleaning pulse, the dynamic filter cake containing the absorbent can be recycled. It is worth noting that the residual (static) filter cake usually does not contain much absorbent and is therefore almost inert with respect to acid gas absorption.

[0041] In order to adjust the individual cleaning frequency of each filter chamber, it is necessary to know the pressure difference and gas flow rate of each chamber. Regarding the latter, in prior art systems, one flow measurement device is usually used to measure the sum of all chamber flows. It is usually assumed that a higher pressure difference across the chamber tube sheet is produced by a higher gas flow rate through the chamber.

[0042] However, this assumption is only correct when the particle distribution is balanced and all chambers receive the same amount of particles at the chamber inlet. Furthermore, this is only true when the filter cleaning is operated with the same cleaning frequency for all chambers. In order to improve the accuracy of the gas flow measurement, in the system of the present invention, it is preferred that each chamber comprises a chamber outlet connected to the clean gas duct, wherein the gas flow measuring device is installed downstream of each chamber outlet.

[0043] Preferably, each gas flow measuring device is mounted in a separate outlet channel portion which fluidly connects the chamber outlet of the associated filter chamber with the clean gas duct. This further improves the equal distribution of gas from a particular filter chamber to the inlet of the associated gas flow measuring device.

[0044] After measuring the gas flow of each chamber individually, there is no benefit in keeping the gas flows from the chamber outlets separate. It is therefore preferred that, downstream of the gas flow measuring device, the individual outlet channel portions of all filter chambers converge into a common clean gas duct.

[0045] In view of the significant fluctuations in gas velocity at the chamber outlet, preferably a gas flow measurement device is provided for overall gas flow measurement.Preferably, the gas flow measurement device is a venturi tube.

[0046] In addition to the above system, the present invention also provides a method for removing solid particles and / or gas components from flue gas. The method comprises the following steps

[0047] a) Providing a filtration system as claimed in any one of the preceding claims, the system comprising:

[0048] two or more filter chambers, each filter chamber including a plurality of filter bags, each filter bag having a filter surface at which particulates are separated from a flue gas flow passing through the filter surface;

[0049] at least one header containing clean air at a controlled pressure, the header connected to a clean air supply and in fluid communication with at least one flow valve, wherein opening of the flow valve causes pulses of clean air to flow through at least one pulse air conduit toward the filter bags to expel particulates from the filter surface; and

[0050] at least one pressure control valve configured to control the pressure of the air in the header;

[0051] a first controller configured to control the opening and closing of the flow valve in response to a data input indicating that the differential pressure drop across the filter bag has reached a given set point; and

[0052] means for measuring the cleaning pulse frequency and / or means for measuring the pressure difference and gas flow rate in each filter chamber;

[0053] b) Determine the particle concentration in the flue gas and measure the cleaning pulse frequency; and / or measure the pressure difference and gas flow rate in each chamber.

[0054] The method is characterized in that the method further comprises the following steps

[0055] c) by means of the first or second controller,

[0056] adjusting the pressure of the clean air in the header based on the measured cleaning pulse frequency to maintain a constant average residence time of the flue gas across all filter chambers; and / or

[0057] The cleaning frequency of each filter chamber is adjusted based on measurements of differential pressure and gas flow across each filter chamber to balance the residence time of the flue gas across all filter chambers within the filtration system.

[0058] Preferably, the pressure of the clean air in the header is further adjusted according to the determined particle concentration in the flue gas and / or the estimated filter cake density. This improves the control of the pressure of the clean air.

[0059] The method of the invention is preferably used in a dry flue gas cleaning system for removing particulates and acid gas components from flue gases.

[0060] In order to achieve high precision of air flow measurement, the gas flow of each filter chamber is preferably measured by means of a corresponding air flow measuring device (preferably a venturi tube) installed downstream of the relevant chamber outlet. In other words, there are preferably an equal number of filter chambers and air flow measuring devices.

[0061] Preferred features of the individual airflow measurements are described in more detail with reference to the accompanying drawings, wherein

[0062] Figure 1A shows a part of an embodiment of a filtration system according to the invention, the system comprising six filter chambers arranged in two filter rows, each filter chamber having a chamber outlet connected to a respective flow measuring device;

[0063] Figure 1B Shown through Figure 1A a cross section of a row of chamber outlets and airflow measuring devices of the system; and

[0064] Figure 1C Shows Figure 1A A perspective view of two rows of chamber outlets and the associated airflow measurement device.

[0065] Figure 1AA part of a flue gas cleaning system according to an embodiment of the invention is shown. In the example shown, the system comprises six filter chambers 10 inside a respective tubular housing 12 having a main upper section 14 of rectangular cross section and a conical lower collecting section 16 ("hopper") for collecting particles filtered from the flue gases. Internally, each filter chamber comprises several rows with a plurality of filter bags (the interior of the filter chambers is not shown). The system shown is designed for dry flue gas cleaning, in which an absorbent (such as slaked lime or sodium bicarbonate) is injected into the flue gases upstream of the filters to absorb acid gas components from the flue gases. The injection of the absorbent takes place from a reactor 17 which, in the embodiment shown, is in the shape of a gas duct. However, other shapes and designs of the reactor are of course possible.

[0066] At predetermined time intervals, the accumulated particles (filter cake) are cleaned from the upstream surface of the cleaning bag by pulse injection of compressed clean air. Clean air is released from the header at a defined pressure and supplied to all filter bags or a group of filter bags, such as multiple rows of filter bags, in a particular filter chamber via a pulse air duct. The filter bags, header and pulse air duct are not shown in the figure. These parts of the pulse jet filter cleaning system are well known in the art, for example from U.S. Patent No. 3,726,066.

[0067] The particles separated from the filter surface by the pulses are collected in the collection section 16 for later removal. If an absorbent is used to absorb gas components from the flue gas, the absorbent will accumulate in the filter cake. It is common practice to recirculate at least a portion of the absorbent-containing filter cake separated from the filter surface and collected in the collection section. In the embodiment shown, the absorbent-containing filter cake material will be reinjected through the reactor 17. Each filter chamber has a chamber inlet 18 fluidly connected to a flue gas supply conduit 20 for conveying flue gas containing solid particles and acid gas components that need to be removed. In Figure 1AIn the embodiment of the present invention, only one flue gas supply duct is visible. Each filter chamber 10 also includes a corresponding chamber outlet 22 for releasing clean flue gas after passing through the filter bags inside the filter chamber. Each chamber outlet 22 is fluidly connected to an associated individual outlet channel section 24, in which a corresponding flow measurement device 26 is installed for measuring the overall gas flow of the associated filter chamber. The individual outlet channel sections 24 of all filter chambers 10 further converge downstream to a common clean gas duct 28. Providing each filter chamber 10 with an individual flow measurement device 26 and its placement in an individual channel section 24 ensures that there is a uniform gas distribution of gas from a specific filter chamber to the inlet of the associated flow measurement device. This enables accurate measurement of the gas flow from a single filter chamber. The flow measurement device can be a venturi tube or a row of instruments (such as a pitot tube or a prandtl tube) that measures the dynamic pressure of the gas flow. The overall measurement gives a robust and accurate measurement regardless of the fluctuating gas velocity distribution.

[0068] The system also includes a controller (not shown) for adjusting the cleaning frequency of each chamber based on the measurements of the individual pressure differential and gas flow through each filter chamber. More specifically, the measured pressure differential of each chamber and the measured individual chamber flow rate are used as data inputs to the controller to adjust the cleaning frequency of each filter chamber with the goal of setting a constant residence time for each chamber.

[0069] Figure 1B Shown separately through Figure 1A FIG. 2 is a cross-section of a row of chamber outlets 22 and an airflow measuring device 26 of a system of FIG. 2 . It can be clearly seen here that each filter chamber outlet 22 is fluidly connected to a respective separate outlet channel segment 24 containing a corresponding airflow measuring device 26. It is further shown how further downstream all outlet separation channel segments converge and merge into a common clean gas duct 28. In the embodiment shown, three filter chambers are arranged in a row, and the outlet channel segments 24 of these three filter chambers extend in parallel and at a vertical distance relative to each other before they merge into the common clean gas duct 28.

[0070] Figure 1C Two rows of chamber outlets 22 are shown in perspective view, wherein the associated individual outlet channel segments 24 and the related gas measuring devices 26 are isolated. The individual outlet channel segments 24 of all six filter chambers converge into a common clean gas duct 28.

Claims

1. A flue gas cleaning system for removing solid particles and / or gas components from flue gas, the system include: Two or more filter chambers (10) comprising a plurality of filter bags, each filter bag having a filter surface where particles are separated from a flue gas flow passing through the filter surface, wherein the particles accumulate on an upstream side of the filter surface to form a filter cake; at least one header containing clean air at a controlled pressure, the header being connected to a clean air supply and in fluid communication with at least one flow valve, wherein opening of the flow valve causes a pulse of clean air to flow through at least one pulse air conduit to a group of filter bags in a particular filter chamber to expel particles from the filter surface; as well as a first controller configured to control the opening and closing of the flow valve in response to a data input indicating that the pressure differential across all filter chambers of the system has reached a predetermined set point; Characterized in that the second controller or the first controller is configured to control the residence time of the flue gas by adjusting: i. adjusting the pressure of the clean air in the header based on the measured time between two consecutive pulses to maintain a constant average residence time of the flue gas in the filter cake across all filter chambers; and / or ii. Adjusting the individual cleaning frequency of each filter chamber based on measurements of pressure differential and gas flow across each chamber to balance the residence time of the flue gas in the filter cake as it traverses all filter chambers within the filtration system.

2. The system according to claim 1, It is characterized in that The controller allows adjustment of both the pressure of the clean air in the header and the cleaning frequency of each filter chamber.

3. The system according to claim 1 or 2, It is characterized in that The controller is a PID controller.

4. A system according to any one of the preceding claims, It is characterized in that The pressure of the clean air in the header is regulated by opening and closing of at least one pressure control valve controlled by the controller.

5. The system according to claim 4, It is characterized in that The pressure control valve is a proportional pressure control valve which is operated by adjusting the pressure set point of the valve, preferably in a continuous manner.

6. A system according to any one of the preceding claims, It is characterized in that The pressure of the clean air in the header is regulated independently of the total pressure differential.

7. A system according to any one of the preceding claims, It is characterized in that The pressure of the clean air in the header is further adjusted depending on a determined concentration of particles in the flue gas and / or an estimated filter cake density.

8. A system according to any one of the preceding claims, It is characterized in that Each filter chamber (10) comprises a chamber outlet (22) connected to a clean gas duct, wherein a gas flow measuring device (26) is installed downstream of each chamber outlet (22).

9. The system according to claim 8, It is characterized in that Each gas flow measuring device (26) is mounted in a separate outlet channel section (24) which fluidly connects the chamber outlet (22) of the associated filter chamber (10) with the clean gas duct.

10. The system according to claim 9, It is characterized in that The individual outlet channel sections (24) of all filter chambers (10) converge into a common clean gas duct (28).

11. A system according to any one of claims 8 to 10, It is characterized in that The gas flow measurement device (26) is equipped for overall gas flow measurement and is preferably a venturi tube.

12. A method for removing solid particles and / or gas components from flue gas, the method comprising the following steps a) Providing a filtration system according to any one of the preceding claims, said system include: two or more filter chambers (10), each filter chamber comprising a plurality of filter bags, each filter bag having a filter surface where particles are separated from a flue gas flow passing through the filter surface; at least one header containing clean air at a controlled pressure, the header connected to a clean air supply and in fluid communication with at least one flow valve, wherein opening of the flow valve causes a pulse of clean air to flow through at least one pulse air conduit to all filter bags or a group of filter bags in a particular filter chamber to expel particulates from the filter surface; as well as at least one pressure control valve configured to control the pressure of the air in the header; a first controller configured to control the opening and closing of the flow valve in response to a data input indicating that the pressure differential across all filter chambers within the filtration system has reached a given set point; means for measuring the cleaning pulse frequency and / or means for measuring the pressure difference and gas flow rate in each filter chamber; b) determining the particle concentration in the flue gas and measuring the time between two consecutive pulses; and / or measuring said pressure differential and gas flow rate in each chamber; c) by means of a second controller or said first controller, adjusting the pressure of the clean air in the header based on the measured cleaning pulse frequency to maintain a constant average residence time of the flue gas across all filter chambers; and / or The cleaning frequency of each filter chamber is adjusted based on measurements of differential pressure and gas flow across each filter chamber to balance the residence time of the flue gas across all filter chambers within the filtration system.

13. The method of claim 12, used in a dry flue gas cleaning system to remove particulate and acid gas components from the flue gas.

14. The method according to claim 13, It is characterized in that An absorbent is injected into the flue gas upstream of the filter to absorb acid gas components.

15. The method according to any one of claims 12 to 14, It is characterized in that The gas flow rate of each filter chamber is measured by means of a respective gas flow measuring device (26), preferably a venturi tube, mounted downstream of the associated chamber outlet (22).

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