Method for removing a sulfur-containing compound from a fuel stream in an internal combustion engine, a fuel filter for removal, and a system for extending periods of time between regeneration cycles of an emission control device
Patent Information
- Application Number
- BRPI0508845
- Authority / Receiving Office
- BR · BR
- Patent Type
- Applications
- Current Assignee / Owner
- Publication Date
- 2007-08-28
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing fuel filters and NOx adsorbents in internal combustion engines are inefficient in the presence of sulfur-containing compounds, leading to reduced efficiency and shorter lifespan due to frequent desulfation processes, which adversely affect nitrogen oxide emissions and catalyst life.
A fuel filter with an adsorbent capable of removing and storing sulfur-containing compounds, particularly aromatic compounds, integrated with a system to release these compounds during regeneration cycles of the NOx adsorbent, thereby extending the life cycle of the NOx adsorbent and reducing the frequency of desulfation without detrimental effects on engine emissions.
The fuel filter effectively reduces sulfur concentrations to 3 ppm or less, prolongs the regeneration cycle of NOx adsorbents, and maintains engine efficiency by minimizing the adverse impact on NOx adsorbents and exhaust emissions.
Abstract
Description
METHOD FOR REMOVING A SULFUR-CONTAINING COMPOUND FROM A FUEL STREAM OF AN INTERNAL COMBUSTION ENGINE, FUEL FILTER FOR REMOVAL, AND SYSTEM FOR EXTENDING TIME PERIODS BETWEEN REGENERATION CYCLES OF AN EMISSIONS CONTROL DEVICE TECHNICAL FIELD The present invention relates to a fuel filter, apparatus, and method for reducing, manipulating, and / or distributing sulfur-containing compounds in a fuel stream of an internal combustion engine. More particularly, the disclosed invention enhances the ability of post-combustion emission devices to reduce nitrogen oxide emissions from internal combustion engines, particularly automotive vehicle engines. BACKGROUND Nitrogen oxide or 'NOx' adsorbents are used to remove nitrogen oxides from the exhaust streams of both mobile and stationary internal combustion engines. However, the efficiency of these NOx adsorbents is reduced in the presence of sulfur-containing compounds. These sulfur-containing compounds, particularly aromatic sulfur compounds, 'poison' or react 'irreversibly' with the catalysts of the NOx adsorbents. NOx adsorbents possessing contaminated catalysts exhibit a reduction efficiency. As a result, the presence of sulfur-containing compounds in fuels used in internal combustion engines can have a detrimental effect on exhaust emissions, particularly with regard to nitrous oxide emissions. This problem is particularly concerning in motor vehicles and stationary systems employing diesel engines. NOx adsorbent catalysts are typically subjected to regeneration processes designed to extend the lifespan of the NOx adsorbent / catalyst. One type of regeneration process is intended to eliminate NOx in the form of... Nitrogen from the NOx adsorbent. In a second type of regeneration process, contaminants such as sulfur-containing compounds are released or removed. This latter process is sometimes referred to as desulfation and typically occurs at higher temperatures than the NOx regeneration process. Repeated exposure to these high temperatures can have adverse effects on the expected lifespan of the catalyst. The concentration of sulfur-containing compounds present in the fuel stream has a direct influence on how the NOx adsorbent should be desulfated. The higher the concentration, the more frequently the catalyst of an NOx adsorbent will need to be desulfated. Similarly, an NOx adsorbent will have an expectation of... The more frequently the product is subjected to desulfation, the shorter its lifespan. It would therefore be advantageous to provide a fuel filter capable of minimizing the adverse effect of sulfur contaminants on the NOx adsorbent. Prior art has attempted to provide devices for removing sulfur-containing fuels from fuel streams of internal combustion engines. For example, U.S. Patent Application Publication No. 2002 / 0028505 A1, the contents of which are incorporated herein by reference, discloses a desulfation apparatus intended to be mounted in automobiles, which is disposed between a fuel tank and an injector of an engine, the apparatus comprising a combination of a sulfur-containing compound adsorbent for adsorption and concentration of the sulfur-containing compounds and an oxidation catalyst or oxidizing agent for sulfur-containing compounds to oxidize the adsorbed sulfur-containing compounds, wherein the apparatus further comprises a means for recovering and removing the resulting sulfur-containing oxide. However, there remains a need for devices, particularly fuel filters, capable of reducing the amount of sulfur-containing compounds in an internal combustion fuel stream to a desirable concentration, particularly to concentrations of 3 ppm or less. It would be equally advantageous if such a filter were used. If fuel could be regenerated, that is, if it could distribute some or all of the stored sulfur-containing compounds in order to extend the lifespan or capacity of the fuel filter. It would be particularly advantageous if this regeneration could occur without imposing a detrimental effect on the NOx adsorbent or on engine exhaust emissions. It would be equally desirable if such a fuel filter could thus extend the lifespan of the NOx adsorbents by reducing the frequency of desulfation. SUMMARY OF THE INVENTION In one embodiment, a fuel filter is disclosed for removing sulfur-containing compounds from an internal combustion fuel stream, the fuel filter comprising at least one column comprising an adsorbent. In an exemplary embodiment, the adsorbent is capable of removing sulfur-containing compounds, particularly sulfur-containing aromatic compounds, from fuels used in internal combustion engines, particularly diesel-type fuels. Also disclosed is an apparatus for extending the service life of an afterburner emissions control device. In an exemplary configuration, the apparatus comprises a fuel filter for removing sulfur-containing compounds from an internal combustion fuel stream, an internal combustion engine, and an afterburner emissions control device. combustion, and a leaky duct connecting the filter, the engine, and the emissions control device. A sulfur removal filter capable of removing, storing, and releasing sulfur-containing compounds, wherein the filter is able to distribute some or all of the stored sulfur-containing compounds during a regeneration cycle of an emissions control device, in which the release of sulfur-containing compounds occurs during regeneration and occurs without imposing a detrimental effect on the NOx adsorbent or engine exhaust emissions. A system for extending the time periods between regeneration cycles of an emission control device, the system comprising: a fuel filter for removing, storing and releasing sulfur-containing compounds from a fuel stream; an internal combustion engine in fluid communication with the fuel system and the fuel filter; an emission control device in fluid communication with an exhaust stream from the internal combustion engine; and a means for controlling the release of the stored sulfur-containing compounds. Finally, a method for removing sulfur-containing compounds from an internal combustion fuel stream is disclosed. In an exemplary configuration, the method comprises passing a fuel through a fuel filter capable of removing compounds. containing sulfur, storage of compounds containing Sulfur is removed, releasing a portion of the stored sulfur-containing compounds, and sending the released portion through the engine and into a post-combustion emissions control device. DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of a published fuel filter configuration comprising a single column. Figure 2 illustrates another configuration of the disclosed fuel filter comprising a single column with a protective bed. Figure 3 illustrates an alternative configuration of the fuel filter disclosed in Figure 2 comprising a single column with a protective bed. Figure 4 is a schematic illustration of another configuration of the disclosed fuel filter comprising a single column with double protective beds. Figure 5 is a schematic illustration of yet another configuration of the disclosed fuel filter comprising double columns with a single protective bed. Figure 6 is a schematic illustration of another configuration of the disclosed fuel filter comprising double columns with double protective beds. Figure 7 illustrates an alternative configuration of fuel filter shown in Figure 6 comprising double columns with double protective beds. Figure 8 It's an illustrative graphic. from the mixture of intake gas Start of Stage 5. Figure 9 It's an illustrative graphic. from the mixture of Exit gas at the beginning of Stage 5. Figure 10 is an illustrative graph of the Lean NOx Trap (LNT) activity at the beginning of Stage 3. Figure 11 is an illustrative graph of the Lean NOx Trap (LNT) activity at the end of Stage 3. Figure 12 is an illustrative graph of the Lean NOx Trap (LNT) activity at the beginning of Step 5. Figure 13 is an illustrative graph of the Lean NOx Trap (LNT) activity at the end of Step 5. Figure 14 is a graph of percentage conversion efficiency relative to the number of steps at the start of normal operation for the baseline test sequence. Figure 15 is a percentage-efficiency graph of conversion relative to the number of steps at the end of normal operation for the line test sequence. basic. Figure 16 is a percentage graph of Conversion efficiency relative to the number of steps at the start of normal operation for the high sulfur content test sequence. Figure 17 is a graph of percentage conversion efficiency relative to the number of steps at the end of normal operation for the high sulfur content test sequence. Figure 18 is a schematic illustration of an internal combustion engine and NOx adsorber with a fuel filter according to exemplary configurations of the present invention. ---------- DETAILED DESCRIPTION OF EXEMPLARY CONFIGURATIONS--------- A fuel filter is disclosed that is capable of removing a sulfur-containing compound from the fuel stream of an internal combustion engine to a concentration equal to or less than 3 ppm and storing the sulfur-containing compound thus removed. The filter has regenerative capacity due to the fact that at least a portion of the stored sulfur-containing compound is released when the filter's storage capacity is reduced. As used herein, the term fuel filter is intended to describe a fuel filter for the removal and subsequent release of sulfur-containing compounds found in fuels. It is understood that according to exemplary configurations a separate fuel filter is provided for removing contaminants from the fuel (e.g., a typical fuel filter). or a fuel filter not designed to remove sulfur). Alternatively, a single fuel filter configured for both the removal and release of sulfur-containing compounds and the filtering of other contaminants is considered to be included within the scope of alternative configurations of the present invention. The singular forms "a," "an," and "the" or "the" include plural references unless the context clearly dictates otherwise. "Optional" or "optionally" means that the circumstance or event subsequently described may or may not occur, and that the description includes instances where the event occurs and instances where it does not occur. The term "about" used in relation to a quantity includes the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measuring the specific quantity). The advertised fuel filter can be used with internal combustion engines employed in both stationary systems and motor vehicles. Illustrative examples of stationary systems include generators and power generation plants. Illustrative examples of motor vehicles include automobiles, trucks, boats, personal watercraft, trailers, devices used in the construction industry such as loaders and cranes, small motorized devices such as lawnmowers and tractors, and the like, where the fuel filter The sulfur removal filter is part of an internal system. An exemplary configuration consists of a vehicle application in which the sulfur removal filter integrates an emissions control system where the filter releases captured sulfur-containing compounds into the fuel stream during a NOx adsorbent regeneration process, wherein the NOx adsorbent regeneration is performed according to technologies known to those skilled in the relevant techniques. Suitable internal combustion engines can be powered by any suitable organic fuel. In one configuration, the fuel will consist of gasoline or diesel oil. In an exemplary configuration, the fuel will be diesel oil. The sulfur-containing compounds removed by the disclosed fuel filter can generally be any sulfur-containing compounds normally found in fuels intended for use in internal combustion engines. In an exemplary configuration, the sulfur-containing compound removed by the disclosed filter will be an aromatic sulfur-containing compound. Illustrative sulfur-containing compounds removed by the disclosed fuel filter include benzothiophene, dibenzothiophene, and derivatives thereof. The disclosed fuel filters can remove one or more of these compounds from a fuel stream. The method and fuel filter disclosed may to be used with commercially available fuels, alternatively fuels with 'high' or 'low' sulfur content. In one configuration, the unfiltered fuel streams may comprise sulfur concentrations from about 6 ppm to 500 ppm. In another configuration, the disclosed method and filters may be used with unfiltered fuel streams having sulfur concentrations from about 15 ppm or less. In an exemplary configuration, the disclosed method and filters may be used with unfiltered fuel streams having sulfur concentrations from about 9 ppm or less. In one configuration, the disclosed method and filters may be used with unfiltered fuel streams having sulfur concentrations from about 6 ppm to about 15 ppm. In one configuration, the disclosed method will result in filtered fuel streams having a reduced sulfur concentration; particularly sulfur concentrations of 3 ppm or less. In an exemplary configuration, the fuel filter comprises at least one column comprising an adsorbent. As illustrated in Figure 1, at least one column 10 has a first opening 10 through which unfiltered fuel enters the column 10 and a second opening 14 through which filtered fuel leaves the column 10. During normal operation of the fuel filter, the concentration of The concentration of a sulfur-containing compound in the fuel exiting through port 14 will be lower than the concentration of the sulfur-containing compound in the fuel entering through port 12. Illustrative adsorbents include one or more of activated carbon, zeolites, clay, acid clay, activated clay, silica gel, silicon dioxide, alumina, aluminum oxide, mesoporous silica porous material (MSF), mixtures thereof, and the like. In one embodiment, the adsorbent comprises at least one of alumina or aluminum oxide. In an exemplary embodiment, the adsorbent consists of alumina. In another exemplary configuration, the disclosed fuel filter further comprises at least one protective bed 16 as illustrated alternatively in Figure 2 or Figure 3. As illustrated in Figure 2, at least one protective bed 16 may have a first opening. V 18 through which the fuel enters the protective bed, and a second opening 20 through which the fuel leaves the protective bed. In this configuration, The protective bed is connected to at least one column 10 via a perforated conduit 22, through which fuel can pass or be transferred. Alternatively, in another configuration As illustrated in Figure 3, at least one protective bed 16 can be attached contiguously to the spine. 10 in such a way that the fuel enters through a first opening 16, passes through the protective bed 16 and the column 10, and subsequently exits through the second opening 14 of the column 10. In another configuration illustrated in Figure 4, the disclosed fuel filter may comprise at least one column 10 that is connected to two protective beds 24 and 26 via conduits 28 and 30. In this configuration, the incoming fuel may enter one or both of the protective beds 24 and 26. After exiting one or both of the protective beds 24 and 26, the fuel is transferred to column 10 via conduit 30. In this configuration, the fuel entering column 10 passes through the first opening 12 and exits column 10 through the second opening 14. In another configuration illustrated in Figure 5, the fuel filter may comprise double columns 32 and 34 and a single protective bed 44. The double columns 32 and 34 have respectively first openings 36 and 38 through which fuel can enter, and second openings 40 and 42 through which fuel can exit. The single protective bed 44 is connected to the double columns 32 and 34 through the conduit 46. The conduit 46, in one configuration, has conduits 48 and 50 forming an assembly such that fuel can enter through one or both columns 32 and 34, alternatively sequentially or simultaneously. Finally, as illustrated in Figures 6 and 7 show that the disclosed fuel filter may comprise two protective beds 52 and 54 and two columns 56 and 58. As discussed above with respect to the configuration in Figure 2, the protective beds 52 and 54 may be connected to columns 56 and 58 respectively via conduits 60 and 62. Alternatively, the protective beds 52 and 54 may be connected directly to columns 56 and 58 without the use of any perforated conduits. As discussed above with respect to Figures 4 and 5, fuel may enter one or both of the protective beds 52 and 54 as well as one or both of the columns 56 and 58. In addition to the disclosed fuel filter, the invention also provides a method for removing a sulfur-containing compound from an internal combustion fuel stream. The disclosed method comprises removing a sulfur-containing compound from a fuel by passing the fuel through a fuel filter capable of removing a sulfur-containing compound, storing the sulfur-containing compound thus removed, releasing a portion of the stored sulfur-containing compound, and sending that portion to an emissions control device. A sulfur-containing compound is removed from a fuel stream when the fuel is passed through the disclosed fuel filter. In an exemplary configuration, the sulfur-containing compound is... removed when the fuel is passed through at least one column comprising an adsorbent as discussed above. The sulfur-containing compound removed from a fuel stream by the disclosed fuel filter will be stored by the fuel filter. In an exemplary configuration, the removed sulfur-containing compound is stored in at least one column comprising the adsorbent. In a particularly exemplary configuration, the removed sulfur-containing compound is stored in the adsorbent. It should be noted that over the lifespan of an internal combustion engine, the disclosed fuel filter will remove a quantity of sulfur-containing compounds. At a certain point, the adsorbent may become unable to store any additional sulfur-containing compounds, even if additional storage is desired. At this point, the disclosed fuel filter may need to be regenerated. Non-limiting examples of determining the point at which the fuel filter has become saturated with sulfur-containing compounds are: measuring the sulfur content of the fuel before and after the fuel filter using sensors, where a sulfur measurement equal to or close to the inlet measurements will indicate that the filter has stopped removing sulfur from the fuel; providing sensors to determine the amount of sulfur in the engine. Discharging into the discharge stream; provision of sensors. in the fuel storage tank for determining the baseline in parts per million of sulfur present in the vehicle's fuel; and provision of pressure sensors before and after the fuel filter, where any of the previously mentioned methods is facilitated by the microprocessor or controller and various sensors communicating with it, as illustrated in Figure 18. Fuel filter regeneration, as referred to here, means the release of at least a portion of the stored sulfur-containing compound. This release or regeneration can be achieved through one or more methods. In an exemplary configuration, fuel filter regeneration can be achieved by heating the fuel filter to an elevated temperature. In one configuration, at least one column of the fuel filter is heated by a heating element (illustrated in Figure 18) wherein alternatively the fuel filter adsorbent element, the fuel, or both, are heated to a temperature higher than the highest normal operating temperature of the fuel stream, at which point the captured sulfur-containing compounds will be released into the fuel stream. In an exemplary configuration, the heating element is a resistance-type heating element in which an application of Current or voltage from a power source is used to increase the temperature of the fuel or adsorbent material in order to release the trapped sulfur-containing compounds. As is evident, the use of other equivalent heating devices is contemplated in exemplary configurations of the present invention. In one exemplary configuration, at least one column of the fuel filter is heated to a temperature equal to or greater than about 100°C. In another configuration, at least one column of the fuel filter is heated to a temperature equal to or less than the boiling point of the fuel. In another configuration, the fuel filter can be regenerated by using a heated fuel stream or by displacement with a solvent other than the fuel, wherein the solvent is released from a solvent reservoir in fluid communication with the fuel stream and is able to release the sulfur-containing compounds captured from the adsorbent element. In an exemplary configuration, the solvent is released from the reservoir and is subsequently recaptured by a suitable filter, or alternatively the solvent consists of a material capable of being consumed by the internal combustion engine without damaging it or the associated emission control devices. The portion of the stored sulfur-containing compound released by fuel filter regeneration is sent through an internal combustion engine and into an emissions control device, particularly an afterburner emissions control device. The emissions control device, as used herein, refers to nitrogen oxide or 'NOx' adsorbents used for removing nitrogen oxides from the exhaust streams of both mobile and stationary internal combustion engines. In one configuration, the emissions control device is a Lean NOx Collector or LNT. 'Afterburner' means a device positioned to receive the combustion products of an internal combustion engine, i.e., located downstream of the internal combustion engine. In an exemplary configuration, the released portion is sent through the engine and into the emission control device in such a way that it enters the emission control device at a time or operation in the device's operating cycle when the effect of the increased sulfur concentration is minimized. A non-limiting example of such a time or operation is illustrated in the Example included herein and in the Figures. In another configuration, the released portion can be sent through the engine and into a post-combustion emission device such as a NOx adsorbent at a point in its cycle that is less sensitive to high sulfur levels. A non-limiting example of such a point or operation is illustrated in... Example included here and in the Figures. In a more preferred configuration, the sulfur-containing compound released by the regeneration of the disclosed fuel filter is sent to a NOx adsorbent at a time when the NOx adsorbent and / or the NOx adsorbent catalyst is undergoing a regeneration process alternatively for NOx or desulfation. Catalysts in NOx adsorbents are typically subjected to regeneration processes designed to increase the efficiency of the NOx catalyst / adsorbent. A first type of regeneration process is intended to convert nitrogen oxides into nitrogen. In a second type of regeneration process, contaminants such as sulfur-containing compounds are eliminated. This latter process is sometimes referred to as desulfation and typically occurs at higher temperatures such as those illustrated in the Example included herein. It should be understood, of course, that exemplary configurations of the present invention may include temperatures higher or lower than those illustrated in the Example included herein and in the Figures. In an exemplary configuration, the portion of the sulfur-containing compound released by the regeneration of the disclosed fuel filter is sent to a NOx adsorbent at a time when the NOx adsorbent and / or the NOx adsorbent catalyst is undergoing a regeneration process resulting in the removal or release of nitrous oxides through reduction. In another configuration, the portion of the sulfur-containing compound released by the regeneration of the disclosed fuel filter is sent to a NOx adsorbent at a time when the NOx adsorbent and / or the NOx adsorbent catalyst will be undergoing a regeneration process that results in the release of the sulfur-containing compounds, i.e., desulfation. In an exemplary configuration, the release of this part and its transmission to an emissions control device should occur within a short period of time relative to the regeneration period of the fuel filter. In an exemplary configuration, the regeneration period of the fuel filter approximates the regeneration period of the emissions control device. According to exemplary configurations of the present invention, the regeneration period of the emissions control device will be maximized to the extent that the fuel filter will reduce the amount of sulfur being deposited on the NOx adsorbent, and therefore the regeneration periods can be less frequent and can be carried out at longer intervals. Also disclosed here are a method and apparatus for extending the service life of an emissions control device 70 in fluid communication with the exhaust of an internal combustion engine 72. This apparatus or system includes the fuel filter disclosed for Removal and storage of sulfur-containing compounds from an internal combustion fuel stream is schematically illustrated in Figure 18. As illustrated, the internal combustion engine receives fuel from a fuel storage tank 74 through the fuel filter. A non-limiting example of an apparatus, method or means of monitoring and controlling the release of stored sulfur-containing compounds into the fuel stream is illustrated in Figure 18. In one configuration, the emissions control device is a post-combustion emissions control device that receives the gaseous combustion products from the combustion chamber of the internal combustion engine. In an exemplary configuration, the apparatus, method or means for monitoring and controlling the release of stored sulfur-containing compounds is an integrated control apparatus comprising a plurality of sensors 78 individually providing signals to a microprocessor or controller 80 comprising programmable logic that is configured to receive signals from the plurality of sensors and provide signals to the fuel filter and its associated heating element, to the internal combustion engine, to the fuel supply and ignition systems for varying the air-to-fuel mixture, if this is necessary (e.g., lean or rich operation for (increased discharge temperature) and heating elements of the emissions control device where, after receiving the appropriate signals (e.g., fuel filter sulfur capacity reached and emissions control device operating in desulfurization or regeneration mode), the microprocessor will instruct the release of sulfur into the fuel stream, which can be received by the emissions control device without adversely affecting it. It is understood that a controller device operating in response to a computer program may implement the processing described above. To perform the described functions and desired processing, as well as the respective computations, the controller may include, without limitation, one or more processors, computers, memory, storage media, registers, timing devices, interrupt devices, communication interfaces, and input / output signal interfaces, as well as combinations comprising at least one of the same. As described above, certain algorithms for implementing exemplary configurations of the present invention can be configured in the form of computer-implemented processes and devices for carrying out these processes. The algorithms can also be configured in the form of computer program code containing instructions configured on media. Tangible media, such as floppy disks, CD-ROMs, hard drives, or any other computer-readable storage media, wherein, when the computer program code is loaded into a computer and / or controller and executed by it, the computer becomes a device for practicing the invention. Existing systems with reprogrammable storage capacity (e.g., flash memories) can be upgraded to implement various aspects of command code, and algorithms can also be configured in the form of computer program code, for example, independently of whether they are stored on a storage medium, loaded into and / or executed by a computer, or transmitted through some transmission medium, such as through electrical wiring or cables, through optical fiber, or by electromagnetic radiation, wherein the computer program code is loaded into and executed by a computer.When implemented in a general-purpose microprocessor, computer program code segments configure the microprocessor to create specific logic circuits. These instructions may reside, for example, in the computer's RAM or controller. Alternatively, the instructions may be contained in a data storage device with computer-readable media, such as a computer floppy disk. Alternatively, the instructions may be stored in one magnetic tape, one hard disk drive conventional, a read-only electronic memory, an optical storage device, or other suitable data storage device. In an illustrative embodiment of the invention, the computer-executable instructions may consist of lines of compiled code compatible with the C++ language. In an exemplary configuration, the control device includes logic for evaluating signals from multiple sensors to determine whether sulfur from the fuel filter should be released into the fuel stream during a desulfurization or regeneration process of the emissions control device. In a non-limiting configuration, a means for controlling sulfur release comprises a circuit and sensor for identifying a predetermined temperature or pressure in the engine or emissions control device that signals the appropriate time for release. Although the invention has been described with reference to a preferred configuration, it should be understood by those skilled in the art that various alterations may be made to it and that certain elements may be substituted for equivalent elements without departing from the scope of the invention. Additionally, many modifications may be made to adapt to a specific situation or a specific material. The teachings of the invention are presented without departing from its essential scope. Thus, it is intended that the invention not be limited to the specific configurations disclosed as the preferred mold contemplated for practicing this invention, but rather that the invention include all configurations within the scope of the claims set forth in the appendix. EXAMPLE The following test was performed to determine whether purging stored sulfur from a fuel filter and injecting it back into the engine immediately before or during the desulfation of an LNT is detrimental to the LNT's lifespan. In theory, during desulfation the LNT is in a reduced state and may be at a high temperature, and therefore the high concentration of sulfur in the exhaust gas will not be... retained in the LNT and therefore will not be harmful to the LNT. A full-size LNT catalyst from the Johnson Matthey company was aged in a furnace in mode Hydrothermal reaction at 700°C for 24 hours. Two samples, one inch in diameter by two inches in length, were cut from the full-size catalyst. One sample was installed in a Universal Synthetic Gas Reactor™ (USGR™) at the Southwesp Research Institute (SwRI) in San Antonio, TX, USA. The catalyst was then tested according to the test plan sequences provided in Tables 1 and 2. The gas mixtures employed are... illustrated in Table 3. TABLE 1. BASELINE LNT PERFORMANCE TEST SCHEME STAGE DESCRIPTION 1 Normal LNT operation for one hour. 2. Desulfurization for five minutes. 3 Normal LNT operation for one hour. 4. Desulfurization for five minutes. 5 LNT operation with exposure to 75 ppm SO2 for one hour. 6. Desulfurization for five minutes. 7 Normal LNT operation for one hour. 8. Desulfurization for five minutes. 9 Normal LNT operation for one hour. 10. Desulfurization for five minutes. Normal operation = 400°C, Desulfurization = 650°C Velocity in Space = 40,000 hr⁻¹ 1 TABLE 2. LNT PERFORMANCE TEST SCHEME WITH EXPOSURE TO HIGH SULFUR CONTENT STAGE DESCRIPTION 1 Normal INT operation for one hour. 2 Desulfurization for fifteen minutes at 75 ppm SO2 + one minute at 0.6 3¾. (1) 3 Normal INT operation for one hour. 4 Desulfurization for fifteen minutes at 75 ppm SO2 + one minute at 0.6 3¾. (2) 5 INT operation with exposure to 75 ppm SQ for one hour. 6 Desulfurization for fifteen minutes with 75 ppm SQ + one minute at 0.6 3¾. (3) 7 Normal LNT operation for one hour. 8 Desulfurization for fifteen minutes with 75 ppm SQ + one minute at 0.6 3¾. (4) 9 Normal INT operation for one hour. 10 Desulfurization for fifteen minutes ccm 75 ppm of 3¾ + one minute at 0.6 3¾. (5) Normal operation = 400° C, Desulfurization = 650° C Velocity in Space = 40,000 hr' 1 Table 3. Gas Mixtures Used GAS COMPONENT CONCENTRATION POOR RICH NO, ppm 350 350 SO2, ppm 0.6 a (75 D ) 0.6 a (75 DCO, ppm 125 -6,700 H2, ppm 0 -4,640 CO2, percentage 6 6 H2O, percentage 6 6 C2H4, ppm 60 60 O2, percentage 6 0 n2 Remaining balance Remaining balance Calculated Fuel / Air Ratio 24.51 13.67 a derivative ccm in relation to NO concentration b 75 ppm of SC^ used to simulate ccm fuel. 1000 ppm of sulfur. Sulfur levels in the fuel were simulated. with SO2 in the USGR gas stream. For a target level of sulfur in fuel 15 ppm and an engine operating with an AFR reason 25:1 the level of sulfur in discharge fol defined to 0.6 ppm. The target concentration of SO2 no gas discharge he was obtained through use of one cylinder containing 10.3 ppm of SO2 with ppm of NODE. When the the concentration of NO was defined to 350 ppm it was known the concentration of SO2 as being 0.6 ppm. As concentrations for NO, CO, CO2, C2H4 H2O were defined and measured through the use of one analyzer Infrared Fourier Transformation (FTIR). the concentration of O2 was defined measure using one Polarographic analyzer standard. He was a cycle adopted of 23 seconds of mixing poor and seconds of mixing rich due to the fact that to provide NOx conversion efficiencies close to 90 percent with aged LNT. The first test sequence performed was the baseline sequence. In this sequence, a low sulfur content was always used, except for Step 5, in which the LNT was exposed to 75 ppm of SO2 for one hour. The main objectives of the baseline test sequence were: (i) to determine if the LNT performance could be maintained within acceptable limits over several cycles of normal operation / desulfation; (ii) to determine if the LNT performance was negatively affected by exposure to high sulfur content during a one-hour period of otherwise normal operation; and (iii) to determine if the LNT performance was effectively restored by the desulfation step after exposure to a high concentration of sulfur. Figure 8 illustrates the gas concentrations at the inlet at the beginning of Stage 5 as an example. Figure 9 illustrates the gas concentrations at the outlet, at the same point in the test sequence. Note the concentration of 75 ppm of SO2 at the inlet, or the conversion of SO2 to another form. The lean / rich cycle is also quite apparent. Measurements were taken at the beginning of each hour of normal operation, and also at the end of the hour. Figures 10 and 11 illustrate the nitrogen-containing species measured at the beginning and end of Stage 3. Stage 3 was a low-sulfur stage (0.6 ppm), and therefore a shutdown was not planned. A significant decrease in LNT catalyst performance is clearly observable. It is clearly observable that the LNT performed the same way at the end of the hour as it did at the beginning. Figures 12 and 13 illustrate the same nitrogen-containing species at the beginning and end of Step 5. Step 5 was the high sulfur concentration step (75 ppm), and catalyst deactivation was expected to become apparent at the end of this step. A significant decrease in deactivation can be observed in the graphs. Figure 14 is a summary graph of the calculated conversion efficiencies for NO, NOx, CO, and C2H4 at the beginning of each normal operating stage. Figure 15 is a summary graph of the calculated conversion efficiencies for NO, NOx, CO, and C2H4 at the end of each normal operating stage. There is no data for Stage 1 as this stage began with cycle times of 28 seconds lean mix / 2 seconds rich mix. The average NOx conversion efficiency was calculated for all five stages measured at the beginning of each hour. The standard deviation (o) was within a range of two percent. The graphs illustrate the average initial efficiency as well as the calculated 2o lines, illustrating that the catalyst did not deactivate during the course of the baseline sequence.At the end of each stage, it is clear that Stage 5, with its high sulfur exposure, reduced NOx conversion to a value well below the lowest line 2; however, activity fully recovered after desulfation in Stage 6. Thus, the three objectives of the test sequence... Baseline targets were achieved. The second test sequence performed was the high sulfur concentration sequence from Table 2. 0.6 ppm of SO2 was used for normal LNT operation in Steps 1, 3, 7, 9, and 11. 75 ppm of SO was used. 2 for normal operation in Step 5, and for the first 15 minutes of each 16-minute desulfation cycle. The main objective of this sequence was to determine if the LNT could be exposed to high levels of sulfur during desulfation and still maintain a reduction in NOx during normal operation. Figure 16 is a summary graph of the conversion efficiencies for NO, NOx, CO, and C2H4 at the beginning of each normal operating stage. Figure 17 is a summary graph of the conversion efficiencies for NO, NOx, CO, and C2H4 at the end of each normal operating stage. As with the baseline test sequence, the standard deviation for NOx conversion efficiency in all six measured stages was well within two percent. As predicted, all values were within the 2° lines. At the end of each stage, it is again clear that the high sulfur exposure stage 5 reduced the NOx conversion efficiency to a value well below the 2° line. The activity recovered at the end of the high sulfur test sequence. Thus, it was established that sulfur stored in the form of a sulfur-containing compound can be purged from a fuel filter and injected. into the interior of an internal combustion engine immediately before or during the desulfation of an emissions control device such as an LNT, without damage to the LNT.
Claims
- CLAIMS - 1. METHOD FOR REMOVING A SULFUR-CONTAINING COMPOUND FROM A FUEL STREAM OF AN INTERNAL COMBUSTION ENGINE, characterized by comprising removal of a sulfur-containing compound from the fuel stream by passing the fuel through a filter capable of removing the sulfur-containing compound; storage of the sulfur-containing compound in the fuel filter; and release of a portion of the sulfur-containing compound stored into the fuel stream during a regeneration cycle of an emissions control device.
2. A method according to claim 1, characterized in that the fuel filter comprises an adsorbent that removes, stores, and releases the sulfur-containing compound from the fuel, wherein the portion is released by heating the fuel or the adsorbent to a temperature that causes the release of the sulfur-containing compound from the adsorbent.
3. Method according to claim 1, characterized in that the emission control device is a NOx adsorbent.
4. Method according to claim 3, characterized in that the regeneration cycle results in a Reduction of nitrous oxides.
5. A method according to claim 3, characterized in that the regeneration cycle results in the release of sulfur-containing compounds from the emission control device.
6. Method according to claim 2, characterized in that the stored sulfur-containing compound is stored in or on the adsorbent.
7. Method according to claim 8, characterized in that the step for releasing a portion of the stored sulfur-containing compound comprises heating the adsorbent to a temperature higher than the normal operating temperature of the fuel.
8. Method according to claim 7, characterized in that the adsorbent is heated to a temperature equal to or greater than 100°C.
9. Method according to claim 7, characterized in that the adsorbent is heated to a temperature below the boiling point of the fuel.
10. Method according to claim 1, characterized in that the fuel consists of diesel oil.
11. FUEL FILTER FOR REMOVAL, storage and subsequent release of a sulfur-containing compound, characterized by comprising at least one column comprising an adsorbent and an element of Heating to warm the adsorbent.
12. Fuel filter, according with Claim 11, characterized by additionally comprising at least one protective bed.
13. Fuel filter, according to claim 12, characterized by comprising at least two columns comprising an adsorbent.
14. Fuel filter, according to claim 13, characterized by comprising at least two protective layers.
15. SYSTEM FOR EXTENDING TIME PERIODS BETWEEN REGENERATION CYCLES OF AN EMISSIONS CONTROL DEVICE, the system being characterized by comprising: A fuel filter for removing, storing, and releasing sulfur-containing compounds from a fuel stream. an internal combustion engine in fluid communication with the fuel system and the fuel filter; an emissions control device in fluid communication with an internal combustion engine exhaust stream; and a means of controlling the release of stored sulfur-containing compounds.
16. System according to claim 15, characterized in that the fuel filter comprises at least one column comprising an adsorbent.
17. System according to claim 15, characterized in that the fuel filter comprises at least one protective bed.
18. System according to claim 17, characterized in that the fuel filter comprises at least two columns comprising an adsorbent.
19. System according to claim 18, characterized in that the fuel filter comprises at least two protective layers.
20. System according to claim 15, characterized by further comprising a second fuel filter for filtering the fuel stream, wherein the second fuel filter is not configured to remove, store and release sulfur-containing compounds from the fuel stream and wherein the post-combustion emission control device is a NOx adsorbent.