WO2022162632A1

WO2022162632A1 - A filtration system for removing contaminants from a gaseous media and a method thereof

Info

Publication number: WO2022162632A1
Application number: PCT/IB2022/050816
Authority: WO
Inventors: Dasappa SRINIVASAIAH; Anand M SHIVAPUJI
Original assignee: Indian Institute Of Science
Priority date: 2021-02-01
Filing date: 2022-01-31
Publication date: 2022-08-04

Abstract

A filtration system for removing contaminants from a gaseous media is disclosed. A gas inlet (Ig) and a gas outlet (Og) is fluidly connected to the housing (110). A compressor (120) and a blower (130) are connected to the housing (110). One or more filter cartridges (200) are arranged in the housing (110). The suction within the housing (110) coats the one or more filter cartridges (200) with at least one pre-coat material. The pre-coat material removes contaminants from the gaseous media passing from the gas inlet (Ig). Further, the gaseous media is re-directed to another housing (110) when pressure drops beyond a pre-determined threshold value across the one of the housings (110). Subsequently, compressed air dislodges the pre-coat material from the one or more filter cartridges (200) for de-coating the one or more filter cartridges (200).

Description

TITLE: “A FILTRATION SYSTEM FOR REMOVING CONTAMINANTS FROM A GASEOUS MEDIA AND A METHOD THEREOF”

TECHNICAL FIELD

Present disclosure relates in general to a filtration system. Particularly, but not limiting to the filtration system used for filtering gaseous media. Further, embodiments of the present disclosure discloses the filtration system having a pleated filter cartridge provided with different pre-coated materials for removing contaminants from gaseous media at low pressure conditions.

BACKGROUND OF THE DISCLOSURE

As conventionally known, downstream applications such as internal combustion engines, gas turbines, fuel cells, hydrogen generation plants, methanol production plants, ethanol production plants, etc., utilize gaseous media (such as producer gas, syngas, biogas, coal gas and a similar mixture of gases) as a fuel for combustion in case of energy conversion devices and as process feed in case of value-added chemical synthesis. Such gaseous media may be also called as raw gas. Typically, such raw gases include fine particles of carbon, ash, higher hydrocarbons, compounds of sulphur, tar molecules, H2S, and other unwanted particles designated as contaminants. If the designated contaminants in the fuel/feed stream are not controlled to within permissible limits, the downstream application/process can suffer significant performance deterioration. The contaminants can have implications ranging from simple performance degradation to catastrophic failure depending on the type and concentration of contaminant and the downstream application. While mechanical energy conversion systems generally tend to suffer performance degradation, catalytic and electrochemical systems are susceptible to more severe and permanent degradation.

Commercially, several filtration systems are available that are used for removing particulates or contaminants from the raw gas before letting it into the engine. For example, some commercially available systems are wet gas scrubber system, entrainment separator, dry dust collector, and active reaction-based systems.

In wet gas scrubber filtration system, the contaminated gas is brought into contact with pressurized water or other solvent with the liquid atomized through a fine spray. Therefore, mist agglomerates around the particulates, resulting in weight gain of the particulate matter which eventually settles down in the bottom sump while the gas moves on. Some of the typical wet scrubber varieties are spray tower, venturi scrubber, jet venturi scrubber, wet gas flusher, oil gas flusher, tar scrubber, and cyclonic scrubber. However, such wet gas scrubbers also trap some hydrocarbons depending on the solubility. Whereas, in the dry dust collector, particulates matter is separated from the gas under dry condition (unlike wet scrubbers wherein the particulate come in contact with a liquid). Typical approaches that are currently used as dry dust collectors are dry cyclones, electrostatic precipitator, grain bed filter, and parallel-operating ceramic fibre filters. However, due to the blocking of all holes of the filter in such dry dust collectors, they face difficulty in efficiency over a period of time/usage [In general, dry collectors choke up quickly depending on the particulate content in the gas, under hot conditions or under accumulated particles that can ignite, etc. Furthermore, such dry dust filters are impossible to clean if there is a presence of combustible particles in the gas. In the active reaction-based systems, the gas is subjected to chemical/thermal treatment ex-situ or in-situ of the reactor to remove compounds from the gas. Some of the typical approaches adopted for active reaction-based systems include catalysts media and 2-phase gasification. However, the active reaction-based filtration systems are not very safe, particularly from gasification of carbonaceous matter wherein combustible species are present.

Further, the costs associated with replacement of these filters for cleaning is very expensive, and thus increase the total production costs. Also, the time taken for replacement needs excess time, therefore, conventional filtration systems cannot meet the requirement of continuous operations. Furthermore, these filters are not able to identify the chemical compound of the gaseous media (raw gas) and remove them accordingly thereby failing to achieve selective filtration, which leads to increased deposition on the filter, and thus increases the pressure drop which affects engine performance. However, these filters may be used in various other applications such as Gas Turbines; Thermal Burners; Fuel Cells; Downstream value-added chemical synthesis applications (like Methanol; Ethanol; DME etc without limitation)

The present disclosure is directed to overcome one or more limitations stated above and any other limitations associated with the prior arts. SUMMARY OF THE DISCLOSURE

One or more shortcomings of the prior art are overcome by a method and a system and additional advantages are provided through the description described in the present disclosure.

In a non-limiting embodiment of the disclosure, a filtration system for removing contaminants from a gaseous media is disclosed. The system includes a housing bifurcated into a lower end housing and an upper end housing. A gas inlet is fluidly connected to the lower end of the housing for receiving gaseous media. A gas outlet is fluidly connected to the upper end of the housing for exhausting purified gas from the housing. Further, a compressor is connected to the housing for supplying compressed air into the housing and a blower is connected to the gas outlet of the housing for generating suction within the housing. One or more filter cartridges are arranged parallel to each other along a longitudinal axis of the housing and the filter cartridges includes a hollow cylindrical body. The suction within the housing coats the one or more filter cartridges with at least one pre-coat material and the compressed air supplied from a reverse direction dislodges the pre-coat material from the one or more filter cartridges. The pre-coat material removes contaminants from the gaseous media passing from the gas inlet.

In an embodiment of the disclosure, an air inlet fluidly connected to the lower end of the housing for allowing ambient air to enter the housing.

In an embodiment of the disclosure, an air outlet fluidly connected to the upper end of the housing for allowing ambient air to exit the housing;

In an embodiment of the disclosure, a dispenser unit to dispense the pre-coat material into the housing.

In an embodiment of the disclosure, the compressor supplies air into the housing in jet pulses.

In an embodiment of the disclosure, the dispenser unit is positioned proximal to the air inlet to inject the pre-coat material into the ambient air stream from the from the air inlet. Further, the ambient air stream with the pre-coat material is coated on the one or more filter cartridges. In an embodiment of the disclosure, the elongated cylindrical body of the one or more filter cartridge includes a top end cap with an aperture.

In an embodiment of the disclosure, the elongated cylindrical body of the one or more filter cartridge includes a bottom end cap that prevents gaseous media from entering and exiting a bottom end of the one or more filter cartridge.

In an embodiment of the disclosure, the plurality of pleats is at least one of non-woven polyester, fiber glass and polyester.

In an embodiment of the disclosure, a plurality of pleats accommodated on a circumference of the hollow cylindrical body of the one or more filter cartridge.

In an embodiment of the disclosure, a powder recovery valve positioned below the one or more filter cartridge for recovering the uncoated material.

In an embodiment of the disclosure, a filter cartridge in a filtration system for removing contaminants from a gaseous media is disclosed. The filter cartridge includes a hollow cylindrical body where, the one or more filter cartridges are coated with at least one pre-coat material to remove contaminants from the gaseous media.

In another non-limiting embodiment of the disclosure, a method of filtration for removing contaminants from a gaseous media is disclosed. The method includes aspects of directing a gaseous media through a first filter cartridge of one or more filter cartridges accommodated in a housing where, the one or more filter cartridges are coated with at least one pre-coat material to remove contaminants from the gaseous media. Further, a control unit detects a pressure drop across the first filter cartridge of the one or more filter cartridges and compares the pressure drop with a pre-set threshold value. Subsequently, the flow of gaseous media is re-directed through a second housing accommodating another filter cartridge of the one or more filter cartridge when the pressure drop across the first filter cartridge of the one or more filter cartridges is equal to or greater than the pre-set threshold value. Further, the first filter cartridge is de-coated of the one or more filter cartridges by directing a pulse jet flow of compressed air from a compressor onto the first filter cartridge of the one or more filter cartridges where, the pre-coat material on the first filter cartridge of the one or more filter cartridges is dislodged. Lastly, the first filter cartridge of the one or more filter cartridges is coated by dispensing the pre-coat material through a dispenser unit into an air stream directed through an air inlet onto the first filter cartridge of the one or more filter cartridges.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristics of the disclosure are set forth in the appended description. The disclosure itself, however, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

Figures. 1 A and IB illustrates a top view and a front view of a filtration system respectively, according to an exemplary embodiment of the present disclosure.

Figure.2 illustrates a perspective view of a pleated filter cartridge, according to an exemplary embodiment of the present disclosure.

Figure. 3 illustrates a schematic diagram of two filtration system arranged in parallel showing coating and de-coating, according to an exemplary embodiment of the present disclosure.

Figure. 4 illustrates coating and de-coating operation of the filter cartridge, according to an exemplary embodiment of the present disclosure. Figure. 5 illustrates a multiple housing configuration with multiple cartridges, according to an exemplary embodiment of the present disclosure.

Figures. 6, illustrates a schematic of the multiple housing configuration with multiple cartridges, according to an exemplary embodiment of the present disclosure.

Figure. 7a illustrates a graphical representation of filter pressure drop with respect to air flow rate, according to an exemplary embodiment of the present disclosure.

Figure. 7b illustrates a graphical representation of filter pressure drop for raw gas flow with respect to cumulative gas flow, according to an exemplary embodiment of the present disclosure.

Figure. 8 illustrates a thimble quality test on raw gas and filtered gas, according to an exemplary embodiment of the present disclosure.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the system and method illustrated herein may be employed without departing from the principles of the disclosure described herein.

DESCRIPTION

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the description of the disclosure. It should also be realized by those skilled in the art that such equivalent methods do not depart from the scope of the disclosure. The novel features which are believed to be characteristic of the disclosure, as to method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure. In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the disclosure.

The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a nonexclusive inclusion, such that a method that comprises a list of acts does not include only those acts but may include other acts not expressly listed or inherent to such method. In other words, one or more acts in a method proceeded by “comprises... a” does not, without more constraints, preclude the existence of other acts or additional acts in the method.

Embodiments of the present disclosure discloses a filtration system for removing contaminants from a gaseous media. The system includes a housing bifurcated into a lower end housing and an upper end housing. A gas inlet is fluidly connected to the lower end of the housing for receiving gaseous media. A gas outlet is fluidly connected to the upper end of the housing for exhausting purified gas from the housing. Further, a compressor is connected to the housing for supplying compressed air into the housing and a blower is connected to the gas outlet of the housing for generating suction within the housing. One or more filter cartridges are arranged parallel to each other and are parallel to a longitudinal axis of the housing. Further, the filter cartridges includes a hollow cylindrical body. The suction within the housing coats the one or more filter cartridges with at least one pre-coat material and the compressed air dislodges the pre-coat material from the one or more filter cartridges. Further, the pre-coat material removes contaminants from the gaseous media that enters from the gas inlet.

As used in the description below the term “control unit” refers to a hardware component such as at least one processor, volatile memory or non-volatile memory, software comprising instructions executable by a processor, or a combination of software and hardware. The control unit may include specialized processing units such as integrated system (bus) controllers, memory management control units, floating point units, graphics processing units, digital signal processing units, etc. The processing unit may include a microprocessor, such as AMD Athlon, Duron or Opteron, ARM’s application, embedded or secure processors, other line of processors, and the like.

Various embodiments of the filtration system are explained referencing Figures 1 to 8. Now referring to Figures 1A and IB, illustrate a filtration system (100). The filtration system (100) includes a housing (110), a compressor (120), and a blower (130). The compressor (120) and blower (130) are connected to the housing (110). The housing (110) may accommodate one or more pleated filter cartridges (such as a first pleated filter cartridge (PFC-1), and a second pleated filter cartridge (PFC-2)). The filter cartridges (PFC-1, PFC-2) are generally elongated and may be arranged parallel (e.g., along axes of elongation) to each other in a substantially vertical manner at centre of the housing (110). The filter cartridges (PFC-1, PFC-2) are arranged along a longitudinal axis (A- A) of the housing (110), The housing (110) further includes a lower end (102) and an upper end (104), wherein the lower end (102) is connected to a gas inlet (Ig), and the upper end (104) is connected to a gas outlet (Og). The gas inlet (Ig) allows the raw gas to enter the housing (110), and the gas outlet (Og) allows the purified gas to exit from the housing (110) of the filtration system (100).

Further, the housing (110) includes a compressed air inlet [not shown in figures] that is attached to one side of the upper end (104) of the housing (110). The compressed air inlet may be connected to the compressor (120) of the filtration system (100) for supplying compressed air. The blower (130) is connected to the gas outlet (Og) of the housing (110). The blower (130) is provided to create a suction in the housing (110). The housing (110) further includes an air inlet (la), an air outlet (Oa), a powder recovery valve (106), and a dispenser unit (108) to dispense a controlled quantity of pre-coat material. The air inlet (la) is placed near the dispenser unit (108), whereas the air outlet (Oa) is placed near the gas outlet (Og) of the housing (110).

Referring to Figure 2, illustrates a pleated filter cartridge (200). The pleated filter cartridge (200) (200) includes an elongated cylindrical body (202), a top end cap (204) and a bottom end cap (206). The elongated cylindrical body (202) is constructed to define a hollow inside for accommodating and passing the filtered gas through it. The elongated cylindrical body (202) includes a top end (208), a bottom end (210), and a plurality of pleats (215) that are incorporated along the circumference of the elongated cylindrical body (202). The plurality of pleats (215) are made of non-woven polyester. Both end caps (top and bottom (204, 206)) include an annular end cap body, wherein the top end cap (204) includes an aperture. The top end cap (204) is attached to the top end (208) of the elongated cylindrical body (202). The bottom end (210) of the elongated cylindrical body (202) is closed by the bottom end cap (206), that prevents air from entering and/or exiting the bottom end (210). The top end cap (204) and the bottom cap (206) are made of fibre.

The pleats of the filter cartridge (200) include an exterior surface and an interior surface, wherein the exterior surface is coated with an appropriate pre-coat material to trap contaminants and impurities of the gas. In one example, the pleats may be coated with an activated carbon material that is typically used for the removal of traces hydrocarbons. In another example, the pleats are coated with a carbon material that is used for removal of traces carbon, ash, alkali matter etc. In another example, the pleats are coated with a metal oxide that is used for removal of traces of Sulphur compounds.

In one embodiment, the specifically coated material is coated onto the exterior surface of the filter cartridge, wherein the filter cartridge (200) may be the first filter cartridge (PFC-1) or the second filter cartridge (PFC-2). Similarly, any number of filter cartridges may be placed based on the requirement of gas to be filtered. For coating the specifically coated material, a fresh cartridge [cartridge that is not coated with any material] may be mounted vertically in the housing (110) of the filtration system (100). After that, the gas inlet (Ig) is closed, and the air inlet (la) and the air outlet (Oa) are opened. The air inlet (la) is provided to allow ambient air to enter the housing (110) and the air outlet (Oa) is provided to allow the air out of the housing (110). The blower (130) is switched on, and the filtration system (100) is subjected to suction mode by connecting the gas outlet (Og) to the blower (130), so that the air can be sucked from the filter (200). During the suction, the dispenser unit (108) is filled with the appropriate pre-coat material, and through the dispenser unit (108) a controlled quantity of the pre-coat material is fed into the air stream (that is coming from the air inlet (la)). The pre-coat material laden air now flows towards the filter. Since the filtration system (100) is on suction mode, the pre-coat material laden air flows upward as well as moves from the exterior surface of the cartridge (200) to the interior surface, resulting in the pre-coat material filter settling on the exterior surface of the filter cartridge (200). After coating the cartridge (200), the powder recovery valve (106) is opened to collect the uncoated material.

In an embodiment, a control unit is connected to the dispenser unit (108), the air inlet (la), the air outlet (Oa), the gas inlet (Ig) and the gas outlet (Og). The control unit may simultaneously operate the dispenser unit (108), the air inlet (la) and the air outlet (Oa). Consequently, the pre-coat material from the dispenser unit (108) is carried by the flow of ambient air form the air inlet (la). In an embodiment, the control unit may operate the flow rate of the ambient air by adjusting or partially closing the inlet valve (la). In an embodiment, the control unit may operate the inlet valve (la) to match the quantity of the pre-coat material that is being dispensed from the dispenser unit (108).

In one embodiment, specific experiments have been designed towards ensuring that most of the powder drawn is coated on the filter cartridge. A scaled down version of the filter has been used as a basis for addressing the right air flow rate to carry the pre-coat material for depositing on the filter. Table 1 provided below lists the details pertaining to the estimation of superficial velocity for pre-coating the filters for a particular base material and coating mix. Based on the coating material properties and its settling velocity, several sets of experiments have been carried to arrive at the superficial velocity for maintaining the velocity in the house to ensure the air flow would carry the particulates on the filter surface. The controlled experiments have been carried out with the designated amount of powder per cartridge required. After each experiment, the amount of material coated on the surface and the collected at the bottom were obtained. One set of data is presented in the table, suggests that a minimum of 0.25 m/s is required for coating the powder on the filter surface.

Table 1 : Estimation of superficial velocity for pre-coating the filters

Based on the control experiments for estimating the superficial velocity, the following blower specifications (used for creation of suction in the filter system), as reported in Table 2 are also arrived at. The pressure requires is about 150 to 200 mm water column.

Table 2. Blower specifications for pre-coting the filters

In one embodiment, the housing (110) of the filtration system (100) may include one or more filter cartridges that are arranged in a geometrical pattern. The flow distribution of the filtration system (100) allows for uniform distribution of air through each cartridge (200), resulting in uniform coating on each of the cartridge.

In one embodiment, the raw gas enters the housing (110) through the gas inlet (Ig) and then moves radially around the entire length of the first filter cartridge (PFC-1). Due to pressure gradient, the gas comes in contact with the specifically coated material, causing the contaminants (present in the gas) to get accumulated on the exterior surface of the first filter cartridge (PFC-1) and the filtered gas enters the interior surface of the first filter cartridge (PFC-1). Subsequently, the filtered gas leaves the first filter cartridge (PFC-1) axially from the aperture of the top end cap (204) of the first filter cartridge (PFC-1), moving towards the gas outlet (Og) of the housing (110). In the course of continuation of operation, the gas contaminants continue to get accumulated on the exterior surface of the first filter cartridge (PFC-1), therefore over a period of time, resistance to gas flow increases, resulting in pressure drop across the cartridge surface. This pressure drop across the cartridge surface continues to increase (essentially between the exterior surface and the interior surface). The drop in pressure across each cartridge (200) including the first filter cartridge (PFC-1) may be measured by a pressure sensor. The housing (110) may accommodate the pressure sensor and the pressure sensor may be connected to a control unit. The control unit may receive signals from the pressure sensor which correspond to the pressure across the surface of the cartridge (200). The control unit may detect the pressure drop across the first filter cartridge (PFC- 1) and the detected pressure drop across the first filter cartridge (PFC-1) may be compared with a pre-set threshold value. Once the pressure drop reaches the pre-set threshold value, the first filter cartridge (PFC-1) indicates saturation of the coating material, and then the gas flow is redirected to the second filter cartridge (PFC-2) where the same process of gas filtering continues like the first filter cartridge (PFC-1), and then the first filter cartridge (PFC-1) (used filter) is operated for regeneration through online.

In an embodiment, the control unit may be connected to a modulator valve. The control unit may operate the modulator valve may be positioned inside the housing (110) for re-directing the gas flow to the second filter cartridge (PFC-2) from the first filter cartridge (PFC-1). Further, when the control unit detects that the pressure drop across the first filter cartridge (PFC-1) reaches the pre-set threshold value, the control unit may operate the modulator valve to re-direct the flow of air from the first filter cartridge (PFC-1) to the second filter cartridge (PFC-2).

The regeneration of the first filter cartridge (PFC-1) includes two online processes such as de- coating process and coating process, as shown in Figure 3. In de-coating process the pre-coated material is dispensed off from the exterior surface the filter cartridge, while in coating process a fresh pre-coated material is coated on the exterior surface the filter cartridge. However, before initiating the de-coating process, the filter cartridge is cleared from the combustible species.

In one embodiment, combustible species is cleared by online process. Once a particular filter is taken offline for regeneration, the filter is evacuated to drain out all the combustible gases and the drained-out gases are flared. In another embodiment, the combustible species is cleared by an offline process. In this process, the gas flow is diverted from the first filter cartridge (PFC-1) to the second filter cartridge (PFC- 2) (parallel filter cartridge), and then the first filter cartridge (PFC-1) (soiled/dirty filter) is taken up from the housing (110) for regeneration. Next, the first filter cartridge (PFC-1) is flushed with inert gas like Nitrogen or with a large amount air (as a standard practice) to evacuate any combustible species present in the filter cartridge (PFC-1) into an LPG supported burner as a safety precaution.

Once the first filter cartridge (PFC-1) is cleared of combustible species, the de-coating process may be initiated using pulse jet flow from the compressor (120). The air in the jet pulses, is made to move in reverse direction, such that the air jet enters the cartridge (PFC-1) in the axial direction (gas outlet direction) and exits the cartridge (PFC-1) in the radial direction (gas inlet (Ig) direction). For example, the jet of air (in pulses) moves towards the interior surface of the cartridge (PFC-1), and hits it at high pressure, resulting in dislodging of the coating material from the exterior surface of the filter cartridge (PFC-1), and finally, the dislodged coating material exits radially from the filter housing (110) of the filtration system (100). For example, the air requirement per filter cartridge per pulse is about 17 litres for dislodging the filter material of a particular coating. One pulse every 20 seconds, that is 3 pulses per minute, per cartridge. This works out to 51 litres per cartridge per minute. Towards optimizing the compressor requirements, the pulses are sequenced having a maximum of about 5 cartridges at a time, however the same shall not be considered to be limiting, any number of cartridges may be used based on requirement. The number of pulses and the location of the jet is designed to dislodge more than 90 % of the coated material. In the case of multiple cartridges, the dislodging of coated material is planned to use a certain number of jets each time, till all the cartridges are covered. The de-coated material is collected at the bottom through the powder recovery valve (106) of the filter housing (110). Subsequent to the de-coating process, the coating process is initiated again with the fresh coated material, as described above. Both, coating and de-coating processes are executed using either a Programmable logic controller (PLC) or a timer-based circuit.

In an embodiment, the control unit may be connected to the compressor (120) and the control unit may operate the compressor to generate air in pulse jets subsequent to operating the moderator valve for re-directing the flow of air from the first filter cartridge (PFC-1) to the second filter cartridge (PFC-2).

In an embodiment, each of the one or more filter cartridges (200) are accommodated in individual housings (110). Further, the gas may be re-directed from one housing (110) to another housing (110) when the pressure across one of the housings (110) drops below the pre-determined threshold value.

Different number of cartridge filters may be used to define different gas flow rates. For example, a single cartridge filter is used to handle 100 m3/h of gas flow rate. In another example, multiple cartridges filter configuration is used to handle 200 m3/h of gas flow rate, as shown in Figure, 4. In another example, multiple housing wherein each housing having multi cartridge configuration are used to handle 3000 m3/h of gas flow rate, as shown in Figure, 5. In an embodiment, valve position description for the three-housing configuration is presented in Table 3 below where in the changeover from PCF 2 to PCF 1 is described (PCF 2 has reached saturation condition as assessed from pressure drop).

Table 3. Changeover from PCF 2 during continuous operation and coating - de-coating

In one embodiment, the performance of the filters is described through following experiment. The controlled experiments have been carried out towards measuring the separation efficiency of the filters. The analysis has been carried out using Calcium Hydroxide and Charcoal powder mixture as the coating material (Calcium hydroxide 90 % and activated charcoal powder 10 % by weight). The cartridges are coated with coating material at 150 g/m2 of cartridge. The concentration of the particulates and condensable higher molecular weight compounds were measured using wet method at both inlet and outlet. The performance analysis general methodology is described as below:

• New filter was coated with mixture of calcium hydroxide and charcoal powder (in the ratio of 90: 10 by weight) with 150 g/m2 of coating density.

• Pressure drop characteristics of the filter cartridge using air were obtained before coating as a reference. Pressure drop was also measured using air after the coating. Comparison was made for pressure drop with and without pre-coat.

• In the course of testing with gas generated from the gasifier, gas samples were collected at two points; one before the filter (raw gas) and other was after the filter (filtered gas). The sampling was fixed to about 0.5m3/hr.

• The testing was carried out for exactly three hours under iso-kinetic condition.

• The biomass consumption was recorded at 50kg/hr.

• The initial pressure drop across the filter was about 24mm WC. The pressure drop increased gradually and at the end of 3hrs of run it had gone to 55mm WC.

• During the course of the experiment the flame colour was observed to be completely blue, clear indication of absence of any particulate and other higher hydrocarbon compounds.

• Totally about 1.490 m3 of raw sample and 1.475m3 of the filtered was collected through the entire duration of the experiment.

Referring to Figure 7A, which illustrates a graphical representation of the filter pressure drop that may be performed before and after the coating. The following graphical representations shows experimental analysis on the variation of pressure across the filter for air flow rate before and after the coating with respect to filter pressure drop (mm, SWG) and air flow rate (kg /hr). The lines in the graphical representation represent the pressure drop build-up before and after the filter coating. As shown in Figure 7A, along expected lines, the pressure drop increases with flow for the coated cartridge.

Now referring to Figure 7B, which illustrates a graphical representation of filter pressure drop for raw gas flow that may be performed before and after the coating. The following graphical representations shows experimental analysis on the variation of pressure drop across the filter cartridge as raw gas is passed through the same coating with respect to pressure drop (mm, SWG) and cumulative gas flow (m3). The presented data covers general gasifier operation with long duration operation and start and shut down operations for a nominal gas flow rate of 145m3/hr. The experimental analysis may be performed about 5 days of operation for varying duration at the rated flow rate conditions. The pressure drop gradually increases with time, as can be seen in Figure 7B. Several tests on the gas quality result indicates the cleaning efficiency > 99.5 %.

In one embodiment, gas quality is described with the help of a simple thimble filter test. The quality of gas in terms of tar and particulate content is quantified based on the simple thimble filter test. In this test, a known quantity of gas is passed through a thimble filter of known initial weight for a fixed time. After the fixed duration of time, the thimble is weighed again the difference in weight indicates the extent of tar and particulate collected. Analysis is carried out on both dry and wet basis. The results of the tar and particulate analysis are presented in Table 4 as below. As is evident, while the quantity of tar and particulate collected in the raw gas is 79 mg/m3, it drastically reduces to 2 mg/m3 after the filtration.

Table 4: P & T collected in thimble before and after pre-coat filter

The effect of filtration is more pronounced on visual inspection of the thimble filter as shown in Figure 8. It is clearly evident that the filter is performing a near perfect task with practically no accumulation perceivable in the thimble.

The disclosed online filtration system determines of an appropriated coated material for the respective contaminants of the gas based on the affinity of the individual chemical compound of the coated material. The online filtration system is designed to eliminant a range of particulates without affecting the filter surface using a specific coating material on the filter surface with large area at low pressure drops. Arrangement of cartridges in the filtration system ensures easy access to maintenance, uniform coating of the precoat material during each cycle of coating either single or multiple cartridges, and uniform flow distribution.

The filtration system has online cleaning facility during operations without removal of cartridges ensuring continuous operation.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding the description may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated in the description.

Referral Numerals

Claims

22 We Claim:

1. A filtration system (100) for removing contaminants from a gaseous media, the system (100) comprising: a housing (110) bifurcated into a lower end (102) housing and an upper end (104) housing; a gas inlet (Ig) fluidly connected to the lower end (102) of the housing (110) for receiving gaseous media; a gas outlet (Og) fluidly connected to the upper end (104) of the housing (110) for exhausting purified gas from the housing (110); a compressor (120) connected to the housing (110) for supplying compressed air into the housing (110); a blower (130) connected to the gas outlet (Og) of the housing (110) for generating suction within the housing (110); one or more filter cartridges (200) arranged parallel to each other along a longitudinal axis (A- A) of the housing (110), the filter cartridges (200) comprising: a hollow cylindrical body (202); wherein, the suction within the housing (110) coats the one or more filter cartridges (200) with at least one pre-coat material and the compressed air dislodges the pre-coat material from the one or more filter cartridges (200); and removes contaminants from the gaseous media passing from the gas mlet (Ig).

2. The system (100) as claimed in claim 1 comprises, an air inlet (la) fluidly connected to the lower end (102) of the housing (110) for allowing ambient air to enter the housing (110).

3. The system (100) as claimed in claim 1 comprises, an air outlet (Oa) fluidly connected to the upper end (104) of the housing (110) for allowing ambient air to exit the housing (110);

4. The system (100) as claimed in claim 1 comprises, a dispenser unit (108) to dispense the pre-coat material into the housing (110).

5. The system as claimed in claim 1 wherein, the compressor (120) supplies air into the housing (110) in jet pulses. The system (100) as claimed in claim 1 wherein, the dispenser unit (108) is positioned proximal to the air inlet (la) to inject the pre-coat material into the ambient air stream from the from the air inlet (la); wherein, the ambient air stream with the pre-coat material is coated on the one or more filter cartridges (200). The system (100) as claimed in claim 1 wherein, the elongated cylindrical body (202) of the one or more filter cartridge (200) includes a top end cap (204) with an aperture. The system (100) as claimed in claim 1 wherein, the elongated cylindrical body (202) of the one or more filter cartridge (200) includes a bottom end cap (206) that prevents gaseous media from entering and exiting a bottom end (210) of the one or more filter cartridge (200). The system (100) as claimed in claim 1 wherein, the plurality of pleats (215) is at least one of non-woven polyester, fiber glass and polyester. The system (100) as claimed in claim 1 comprises, a plurality of pleats (215) accommodated on a circumference of the hollow cylindrical body (202) of the one or more filter cartridge (200). The system (100) as claimed in claim 1 comprises, a powder recovery valve (106) positioned below the one or more filter cartridge (200) for recovering the uncoated material. A filter cartridge (200) in a filtration system (100) for removing contaminants from a gaseous media, the filter cartridge (200) comprises: a hollow cylindrical body (202); wherein, the one or more filter cartridges (200) are coated with at least one pre-coat material to remove contaminants from the gaseous media. The filter cartridge (200) as claimed in claim 12 wherein, the elongated cylindrical body

The filter cartridge (200) as claimed in claim 12 wherein, the elongated cylindrical body (202) of the one or more filter cartridge (200) includes a bottom end cap (206) that prevents gaseous media from entering and exiting a bottom end (210) of the one or more filter cartridge (200). The filter cartridge (200) as claimed in claim 12 wherein, the plurality of pleats (215) is at least one of non-woven polyester, fiber glass and polyester. The filter cartridge (200) as claimed in claim 12 comprises, a plurality of pleats (215) accommodated on a circumference of the hollow cylindrical body (202) of the one or more filter cartridge (200). A method of filtration for removing contaminants from a gaseous media, the method comprising: directing a gaseous media through a first filter cartridge (PFC-1) of one or more filter cartridges (200) accommodated in a housing (110) wherein, the one or more filter cartridges (200) are coated with at least one pre-coat material to remove contaminants from the gaseous media; detecting by a control unit, a pressure drop across the first filter cartridge (PFC-1) of the one or more filter cartridges (200) and comparing the pressure drop with a pre-set threshold value, re-directing the flow of gaseous media through a second filter cartridge (PFC-2) of the one or more filter cartridge (200) when the pressure drop across the first filter cartridge (PFC-1) of the one or more filter cartridges (200) is equal to or greater than the pre-set threshold value; de-coating the first filter cartridge (PFC-1) of the one or more filter cartridges (200) by directing a pulse jet flow of compressed air from a compressor (120) onto the first filter cartridge (PFC-1) of the one or more filter cartridges (200) wherein, the pre-coat material on the first filter cartridge (PFC-1) of the one or more filter cartridges (200) is dislodged; coating the first filter cartridge (PFC-1) of the one or more filter cartridges (200) by dispensing the pre-coat material through a dispenser unit (108) into an air stream directed through an air inlet (la) onto the first filter cartridge (PFC-1) of the one or more filter cartridges (200).