System for detecting sulfuric acid

In one aspect, the present disclosure is directed to a system for reacting with sulfuric acid. The system may include a housing having an inlet and an outlet and may also include a component disposed downstream of the inlet and upstream of the outlet. The component may be configured to restrict a flow of fluid through the housing as a function of sulfuric acid present within the fluid.

TECHNICAL FIELD

The present disclosure relates generally to detection systems and, more particularly, to sulfuric acid detection systems.

BACKGROUND

Exhaust gas recirculation (EGR) systems are used for controlling emissions of undesirable pollutant gases and particulates during operation of an internal combustion engine. Such systems have proven particularly useful in internal combustion engines used in motor vehicles such as passenger cars, trucks, and other on-road machines. EGR systems generally recirculate exhaust gas into an intake air supply of the internal combustion engine. The exhaust gas reintroduced to the engine cylinder reduces the concentration of oxygen in the cylinder, which lowers the maximum combustion temperature, slows the chemical reaction of the combustion process, and decreases the formation of oxides of nitrogen (NOx). Furthermore, the exhaust gas typically contains unburned hydrocarbons which are burned after reintroduction into the engine cylinder further reducing the emission of undesirable pollutants from the internal combustion engine.

Sulfur, that may be present in fuel, may combine with oxygen at certain points in the EGR system to form sulfur trioxide. Relatively hot recirculated exhaust gas is cooled before being reintroduced into the cylinder by directing the exhaust gas through an air-to-gas or a water-to-gas heat exchanger. When the exhaust gas is cooled, water vapor in the exhaust gas may condense and combine with the sulfur trioxide to form sulfuric acid. Sulfuric acid can corrode the surface of the equipment and can lead to maintenance issues.

One system for detecting a corrosive compound in a system is described in U.S. Pat. No. 6,536,264 (the '264 patent), issued to Flammersfeld et al. Specifically, the '264 patent describes a liquid fluid system having a transparent component blocked by a corrodible barrier. Fluid flows through the system in such a way that the corrodible barrier is in contact with the fluid. If the fluid in the system becomes corrosive, the barrier may corrode and allow the fluid to flow into the transparent component. Fluid in the transparent component may then serve as a visual indication that the fluid in the system is corrosive.

While the system of the '264 patent may serve as a visual indication of corrosion in a liquid system, it may not be effective in a gaseous system. A corrosive compound in a liquid system may be in constant contact with the corrodible barrier and may be readily visible in the transparent component. Sulfuric acid in exhaust gas may not contact the corrodible barrier sufficiently to corrode the barrier quickly, and once the barrier corrodes the exhaust gas may not be readily visible in the transparent component.

The present disclosure is directed at overcoming one or more of the shortcomings set forth above or other shortcomings.

SUMMARY

In one aspect, the present disclosure is directed to a system for reacting with sulfuric acid. The system may include a housing having an inlet and an outlet and may also include a component disposed downstream of the inlet and upstream of the outlet. The component may be configured to restrict a flow of fluid through the housing as a function of sulfuric acid present within the fluid.

In another aspect, the present disclosure is directed to a method for altering the flow of fluid in the presence of sulfuric acid. The method may include directing a flow of flow into a housing having an inlet and an outlet and directing the flow into contact with a component disposed downstream of the inlet and upstream of the outlet. The component may be configured to restrict the flow through the housing as a function of sulfuric acid present within the fluid.

DETAILED DESCRIPTION

FIG. 1illustrates an exemplary power system10. Power system10is described herein as a diesel-fuel, internal combustion engine12for exemplary purposes only. However, it is contemplated that engine12may embody any other type of internal combustion engine, such as, for example, a gasoline or gaseous fuel-powered engine. Engine12may include an engine block14at least partially defining a plurality of cylinders16. Each cylinder16may be associated with a fuel injector, a cylinder liner, at least one air intake port22and corresponding intake valve (not shown), at least one exhaust port24and corresponding exhaust valve (not shown), a combustion chamber, and a reciprocating piston assembly moveable within each cylinder16. It is contemplated that engine12may include any number of cylinders16and that cylinders16may be disposed in an “in-line” configuration, a “V” configuration, or any other conventional configuration. A crankshaft20of engine12may be rotatably disposed within engine block14.

Power system10may be used with a machine. The machine may embody a mobile or stationary machine that performs some type of operation associated with an industry such as mining, construction, farming, transportation, or any other industry known in the art. For example, the machine may be an earth moving machine such as an off-highway haul truck, a wheel loader, a motor grader, a tracked vehicle, or any other suitable earth moving machine. The machine may alternatively embody an on-highway vocational truck, a passenger vehicle, or any other operation-performing machine.

An air induction system30may be associated with power system10and include components that condition and introduce compressed air into cylinders16by way of intake port22and the intake valves. For example, air induction system30may include an air filter32, a compressor34connected to draw inlet air through air filter32, and an air cooler36located downstream of compressor34. It is contemplated that air induction system30may include different or additional components such as, for example, inlet bypass components, a throttle valve, and other components known in the art.

Air filter32may be configured to remove or trap debris from air flowing into power system10. For example, air filter32may include a full-flow filter, a self-cleaning filter, a centrifuge filter, an electro-static precipitator, or any other type of air filtering device known in the art. It is contemplated that more than one air filter32may be included within air induction system30and disposed in a series or parallel arrangement. Air filter32may be connected to inlet port22.

Compressor34may be located downstream of air filter32and configured to compress the air flowing into power system10. Compressor34may embody a fixed geometry type compressor, a variable geometry type compressor, or any other type of compressor known in the art. It is contemplated that more than one compressor34may be included within air induction system30and disposed in parallel or in series relationship. Air cooler36may be configured to cool air within air induction system30upstream of cylinders16and may include a liquid-to-air heat exchanger, an air-to-air heat exchanger, or any other type of heat exchanger known in the art for cooling air.

An exhaust recirculation system40may also be associated with power system10, and include components that condition and direct exhaust from cylinders16by way of exhaust ports24and the exhaust valves. For example, exhaust recirculation system40may include a turbine42driven by the exiting exhaust, a regeneration system46, a particulate filter50, a flow control valve62and an exhaust outlet52configured to direct treated exhaust to the atmosphere, a flow meter54, an exhaust cooler56, and a filter60. It is contemplated that exhaust recirculation system40may include different or additional components than described above such as, for example, exhaust bypass components, an exhaust braking system, and other components known in the art. As illustrated inFIG. 1, exhaust recirculation system40may direct exhaust from downstream of turbine40towards intake ports22. Alternatively, exhaust recirculation system40may direct exhaust from upstream of turbine40towards intake ports22.

Turbine42may be located to receive exhaust leaving power system10via exhaust port24. Turbine42may be connected to compressor34of air induction system30by way of a common shaft to form a turbocharger. As the hot exhaust gases exiting power system10move through turbine42and act upon turbine42, i.e. expand against vanes (not shown) thereof, turbine42may rotate and drive the connected compressor34to pressurize inlet air. It is contemplated that more than one turbine42may be included within exhaust recirculation system40and disposed in parallel or in series relationship.

A regeneration system46may regenerate the particulate matter. Regeneration system46may include, among other things, a fuel-powered burner, an electrically-resistive heater, an engine control strategy, or any other means for regenerating known in the art. Particulate filter50may be disposed downstream of turbine42to remove particulates from the exhaust flow directed from power system10. It is contemplated that particulate filter50may include electrically conductive or non-conductive coarse mesh elements. It is also contemplated that particulate filter50may include a catalyst for reducing an ignition temperature of the particulate matter trapped by particulate filter50. The catalyst may support the reduction of HC, CO, and/or particulate matter, and may include, for example, a base metal oxide, a molten salt, and/or a precious metal. It is further contemplated that particulate filter50may be omitted. It is further contemplated that an additional particulate filter (not shown) may be located within exhaust recirculation system40.

Exhaust recirculation system40may also include mass flow sensor54and exhaust cooler56. Mass flow sensor54may be configured to measure exhaust flow. Mass flow sensor54may embody, for example, a thermal mass flow meter, a laminar flow element, a mass compensated positive displacement roots meter, or any other suitable device configured to measure gaseous flows. Exhaust cooler56may be disposed downstream of particulate filter50to cool the portion of exhaust flowing through exhaust recirculation system40. Exhaust cooler56may include a liquid-to-air heat exchanger, an air-to-air heat exchanger, or any other type of heat exchanger known in the art for cooling an exhaust flow. It is contemplated that exhaust cooler56may be omitted.

A recirculation valve arrangement64may be fluidly connected to exhaust cooler56to regulate the flow of exhaust through exhaust recirculation system40. Recirculation valve arrangement64may be configured to selectively pass or restrict the flow of exhaust therethrough. Although illustrated inFIG. 1as being located downstream of exhaust cooler56, it is contemplated that recirculation valve arrangement64may, alternatively, be located upstream of exhaust cooler56.

FIG. 2illustrates a filter60. Filter60may be disposed downstream of exhaust cooler56, seeFIG. 1. Filter60may include a housing70having an inlet72configured to receive exhaust from exhaust cooler56, a main chamber74, and an outlet76configured to direct exhaust to air induction system30. Filter60may include a filter assembly80. Filter assembly80may be disposed between inlet72and outlet76of housing70. Filter assembly80may include a filter medium82. Filter medium82may be constructed of glass microfibers, synthetic microfibers, a combination of synthetic and glass microfibers, or any other filter medium known in the art. Filter medium82may be chemically bound to better withstand acid that may be present in exhaust recirculation system40. Filter medium82may be configured to trap debris, including debris due to corrosion, and particulate matter in exhaust recirculation system40and may secure filter assembly80to outlet76. Filter medium82may be coated with a chemical composition that reacts with sulfuric acid to form a solid. Filter assembly80may also include a shell84. Shell84may be a metal mesh or screen, may fix filter medium82in place, and may secure filter assembly80to outlet76within housing70All or a portion of shell84may be constructed of zinc, a zinc alloy, or other metal known in the art that corrodes, i.e. has a low resistance to corrosion when contacted by sulfuric acid. Alternatively, shell84may be constructed of a metal resistant to sulfuric acid or may be constructed of a metal with an acid resistant coating. Filter60may include a screen86that may be disposed upstream of filter medium82. Screen86may be constructed of zinc, a zinc alloy, or other metal known in the art that corrodes, i.e. has a low resistance to corrosion when contacted by sulfuric acid. Filter60may be in communication with a control system90.

As illustrated inFIG. 3, control system90may include components that interact to notify an operator of a condition of filter60. In particular, control system90may include a differential pressure sensor92, a controller94, and an indication device96. Controller94may receive input from differential pressure sensor92, and in response, cause indication device96to provide an indication to the operator.

Differential pressure sensor92may be located in fluid communication with exhaust entering filter60and with exhaust existing filter60to determine a differential pressure between the two areas. For example, differential pressure sensor92may compare the pressure of exhaust within inlet72with the pressure of the exhaust within outlet76and generate a signal indicative of the differential pressure. An increase in differential pressure may be indicative of a flow restriction through filter60. This differential pressure signal may be communicated to controller94, and controller94may relate the differential pressure signal with a restriction value. Alternatively, it is contemplated that a first pressure sensor (not shown) may generate a signal indicative of the pressure of exhaust within inlet72and a second pressure sensor (not shown) may generate a signal indicative of the pressure of the exhaust within outlet76. Controller94may receive the signals from the first and the second pressure sensors to determine the differential pressure between inlet72and outlet76.

Controller94may include a single microprocessor or multiple microprocessors that include a manner for controlling an operation of indication device96. Numerous commercially available microprocessors can be configured to perform the functions of controller94. It should be appreciated that controller94could readily embody a general engine microprocessor capable of controlling numerous functions of power system10. Controller94may include a memory, a secondary storage device, a processor, and other components for running an application. Various other circuits may be associated with controller94such as power supply circuitry, signal conditioning circuitry, solenoid driver circuitry, and other types of circuitry.

Indication device96may be operatively coupled to controller94, and configured to provide one or more warning signals indicative of an increased differential pressure to a user of the machine. For instance, indication device96may include any component configured to provide a warning signal to a user associated with the machine such as, for example, a visual device or signal, e.g. a warning lamp, an LCD display, an LED lamp, or other visual device known in the art; an audible device, e.g. a speaker, a bell, a chime, or other audible device known in the art; a wireless device, e.g. a cell phone, a pager, or other wireless device known in the art; or any other output device known in the art. In addition to or alternatively indication device96may include a display component, for example, a computer, an operator panel, or an LCD for displaying the differential pressure or the warning signal.

INDUSTRIAL APPLICABILITY

The disclosed filter may be used with any power system where it is desired to monitor the content of sulfur in fuel. By providing an operator of a machine with an indication that excessive sulfur is present in the fuel, the operator may be able to refuel the machine or otherwise restore the power system to the proper operating conditions before damage occurs. The disclosed filter may also be used with any power system where it is desired to provide a back-up filter to catch debris from a failure in the system. A primary filter may fail and allow particulate matter to flow into the system or a component of the system, downstream of the primary filter, may fail and cause debris to flow into the system. The disclosed filter may act to trap debris and particulate matter that may enter into the system in this manner. The operation of power system10and, in particular, filter60is explained below.

Atmospheric air may be drawn into air induction system30via air filter32and directed through compressor34where it may be pressurized to a predetermined level before entering the combustion chamber of engine12. Fuel may be mixed with the pressurized air before or after entering the combustion chamber of engine12. The fuel and air mixture may be ignited by engine12to produce mechanical work and an exhaust flow containing gaseous compounds. The exhaust flow may be a fluid that may also contain solid particulate matter and sulfur. The exhaust flow may be directed from engine12to turbine42where the expansion of hot exhaust gases may cause turbine42to rotate, thereby rotating connected compressor34to compress the inlet air. After exiting turbine42the exhaust may flow through regeneration system46and flow through particulate filter50.

A fuel-powered burner in regeneration system46may cause the sulfur to combine with oxygen to form sulfur dioxide gas (SO2). Particulate filter50may have a base metal oxide catalyst that may oxidize the sulfur dioxide gas, i.e., add oxygen to form sulfur trioxide gas (SO3). The exhaust flow may then be divided into two substantially particulate-free flows, including a first flow redirected to air induction system30and a second flow directed to the atmosphere via flow control valve62and exhaust outlet52. The flow of the reduced-particulate exhaust may be directed through mass flow sensor54and then may be cooled by exhaust cooler56to a predetermined temperature. Exhaust cooler56may cause water in exhaust recirculation system40to condense. The sulfur trioxide may then dissolve in the condensed water and may form sulfuric acid (H2SO4).

The exhaust flow may pass through filter60and be directed back into air induction system30by compressor34. The recirculated exhaust flow may be mixed with the air entering the combustion chambers. The exhaust flow, which is directed to the combustion chambers of engine12, may reduce the concentration of oxygen therein, which may lower the maximum combustion temperature within engine12. The lowered maximum combustion temperature may slow the chemical reaction of the combustion process, thereby decreasing the formation of nitrous oxides. In this manner, the gaseous pollution produced by engine12may be reduced without experiencing the harmful effects and poor performance caused by excessive particulate matter being directed into engine12.

Sulfuric acid in the exhaust may be directed through filter60and may contact shell84, may cause shell84to corrode, forming debris which may flow into filter medium82. Filter medium82may trap the debris and the flow of exhaust through filter60may be restricted. Sulfuric acid in the exhaust gas may contact screen86, may cause screen86to corrode, forming debris which may flow into filter medium82. Filter medium82may trap the debris and the flow of exhaust through filter60may be restricted. Sulfuric acid in the exhaust gas may react with the chemical composition coating of filter medium82to form solids and subsequently be trapped, i.e. prevented from passing though filter medium82and through outlet76. This trapping may restrict the flow of exhaust through filter60. When flow through filter60becomes restricted, either by debris from shell84, debris from screen86, or solids formed from a reaction with the chemical coating, a differential pressure across filter60, i.e. the difference in pressure between inlet72and outlet76, may increase. As filter60becomes more restricted, the differential pressure increases to a greater degree. Differential pressure sensor92may generate a signal indicative of a differential pressure. Controller94may receive the signal from differential pressure sensor92and compare the signal with an expected differential pressure range. The amount the signal is outside of the expected range may relate to a restriction value. Controller94may cause indication device96to provide one or more warning signals, or other indication, including an indication of the restriction value, to the operator of the machine if the signal is outside of the expected range.

Several advantages of the disclosed filter may be realized. For example, the filter may be used with a power system, may monitor the content of sulfur in the fuel of the power system, and may provide an indication to the operator regarding the content of sulfur in the fuel by detecting sulfuric acid in the exhaust. The filter may also provide a large surface area for sulfuric acid in the system to contact and may cause a more rapid indication. The disclosed filter may also act as a back-up filter for the power system by traping debris and particulate matter that may not be filtered by a primary filter due to a failure of the primary filter or a failure of a component downstream of a primary filter. In this manner, the disclosed filter provide an indication of excessive particulate matter or debris in the system and may prevent damage to the engine.