WO2014193348A1

WO2014193348A1 - Heating jacket layer with electric heating and thermistor

Info

Publication number: WO2014193348A1
Application number: PCT/US2013/042968
Authority: WO
Inventors: Randall R. ROEPKE; David J. Nicholls; William R. Fleming; Jason B. ARRIAGA; Ian Samuel SPENCER
Original assignee: International Engine Intellectual Property Company, Llc
Priority date: 2013-05-29
Filing date: 2013-05-29
Publication date: 2014-12-04

Abstract

A heating unit and method for use in heating a canister containing a reductant, such as an ammonia storage material for use in an after-treatment device in an exhaust system, is disclosed. The heating unit or jacket includes two sections forming an interior for receipt of the canister. A controller for regulating the temperature of the heating unit can be incorporated into a heating source connected to the heating unit, or embedded into a heating element layer of the unit.

Description

HEATING JACKET LAYER WITH

ELECTRIC HEATING AND THERMISTOR

TECHNICAL FIELD

[0001] The present device and method relates to the storage and delivery of a reductant for use in the reduction of NO_x in the exhaust stream. Particularly, the device relates to a heating device or jacket for applying heat to a canister containing an ammonia

adsorbing/desorbing material, including regulating the temperature of the unit.

BACKGROUND

[0002] Compression ignition engines provide advantages in fuel economy, but produce both Οχ and particulates during normal operation. New and existing regulations continually challenge manufacturers to achieve good fuel economy and reduce the particulates and NO_x emissions. Lean-burn engines achieve the fuel economy objective, but the high

concentrations of oxygen in the exhaust of these engines yields significantly high

concentrations of NO_x as well. Accordingly, the use of NO_x reducing exhaust treatment schemes is being employed in a growing number of systems.

[0003] One such system is the direct addition of a reductant, such as ammonia, to the exhaust stream in conjunction with an after-treatment device. It is an advantage to deliver ammonia directly in the form of a gas, both for simplicity of the flow control system and for efficient mixing of reducing agent, ammonia, with the exhaust gas. The direct use of ammonia also eliminates potential difficulties related to blocking of the dosing system, which are cause by precipitation or impurities, e.g., in a liquid-based urea solution. In addition, an aqueous urea solution cannot be dosed at a low engine load since the temperature of the exhaust line would be too low for complete conversion of urea to ammonia (and CO₂).

[0004] Transporting ammonia as a pressurized liquid, however, can be hazardous if the container bursts caused by an accident or if a valve or tube breaks. In the case of using a solid storage medium, the safety issues are much less critical since a small amount of heat is required to release the ammonia and the equilibrium pressure at room temperature can be— if a proper solid material is chosen— well below 1 bar. An ammonia adsorbing/desorbing material in a granular or powder form can be contained within disks or balls formed from aluminum and loaded into the cartridge or canister. The canisters are then positioned in a heating unit, such as a heating jacket, which is then loaded into a housing or other storage structure and secured to the vehicle for use. Appropriate heat is applied to the canisters through the heating jackets, which then causes the ammonia-containing storage material to release its ammonia gas into an after-treatment device for use in the reduction of NO_x in an exhaust system. An efficient system requires that multiple canisters be heated sequentially, with one canister actively heated at a time. Therefore, regulating and maintaining the heat around the canisters is important for consistent and efficient release of ammonia into the exhaust stream, and more effective reduction of NO_x. The present heating device also includes a controller or temperature regulating device for maintaining an activating temperature within the unit at a predefined limit, to avoid overheating the canister and its contents.

SUMMARY

[0005] There is disclosed herein a device and method, each of which avoids the disadvantages of prior devices, systems and methods while affording additional structural and operating advantages.

[0006] Generally speaking, the present device is a heating unit or jacket having a temperature regulating element, for heating a canister containing a reductant, such as an ammonia storage material for use in releasing ammonia into an exhaust after-treatment device on a vehicle.

[0007] In one embodiment, a heating unit for use in heating a canister containing a reductant, is disclosed. The heating unit comprises a first section, a second section detachably connected to the first section, wherein the first section and second section define an interior space for the receiving the canister, a heating element located in one of either the first section and the second section, and a controller for maintaining an activating temperature within the unit at a predefined limit.

[0008] In yet another embodiment, a method for heating a canister containing an ammonia storage material for release of ammonia for use in an after-treatment exhaust system of a vehicle, is disclosed. The method comprises the steps of providing a heating unit having a first section and a second section, the sections being detachably connected to form an interior space for receiving the canister, heating the unit and the canister to a predetermined temperature for release of ammonia from the ammonia storage material into the after-treatment system, and regulating the temperature at a predefined limit.

[0009] These and other aspects of the device and method may be understood more readily from the following description and the appended drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is an perspective view of present device, including several ASDS components;

[0011] FIG. 2 is a perspective front view of the present heating device;

[0012] FIG. 3 is a perspective back view of the present heating device;

[0013] FIG. 4 is an exploded view of the present heating device; and,

[0014] FIG. 5 is a circuit diagram showing the temperature controller or thermistor.

DETAILED DESCRIPTION

[0015] Referring to FIGS. 1-4, there is illustrated a heating unit or jacket 10 for use in a system and method for storage and delivery of a reductant, such as ammonia, for use in the reduction of NO_x in an exhaust stream. Ammonia storage and dosing systems (ASDS), which are part of the exhaust gas NO_x reduction (EGNR) system used in vehicles, may be comprised of several components, including a start-up canister, at least one main canister contained within a housing or storage compartment, wherein the canisters contain an ammonia adsorbing/desorbing material, an ammonia control module (AFM), a peripheral interface module (PIM), and possibly other components depending on vehicle specifications. The specific components of the ASDS and EGNR will not be discussed in further detail with the exception of how it relates to the present unit. As the exhaust system of a vehicle, including that of a diesel engine, is well known, it will not be described in detail.

[0016] Referring to FIGS. 1-4 the heating unit or jacket is generally designated by the numeral 10. The heating jacket 10 initiates and maintains an activation temperature for a main canister 200 or cartridge containing the ammonia adsorbing/desorbing material (not shown). The heating jacket 10 is positioned within a storage compartment or housing 100, which would then be attached to the frame of a vehicle (not shown) using any holder (not shown) permitting easy installation and removal of the jacket and its cartridges. The heating unit 10 is designed to hold one or a plurality of canisters in a single unit. As well, the housing 100 for retaining the jackets and canisters may likewise be designed to hold one or a plurality of heating jackets. The housing 100 is typically a modular unit and can be arranged in various configurations on a vehicle. [0017] The heating jacket 10 is typically constructed of two, symmetrical halves or sections, a first housing section 12 and a second housing section 14, each of which are comprised of a plurality of materials. Each section has a generally semi-circular shape. The sections 12, 14 are detachably connected together, or movably connected together to define an interior space or chamber 16 for receiving the canister 200. Specifically, as shown in FIG. 3, the sections 12, 14 each include opposing side walls 12a, and 14a, which form a portion of the interior space or chamber 16. Each section also includes an end wall or panel 12b, 14b, such that when the sections are joined together, the two end walls form a common closed rear wall 18 of the unit, as well as enclosing the chamber 16. Additionally, the joined sections 12, 14 form an opening 20 opposite the rear wall (FIG. 2) for receiving the canister within the chamber 16.

[0018] The two end walls 12a, 14a may be connected together through any suitable attachment means, permitting the two sections to move together or apart. For example, a hinge 22 or a plurality of hinges or other pivotal devices may be used to pivotally join the end panels together. In this manner, the sections 12, 14 are joined together at the rear wall 18, opening and closing in a clamshell manner. Because the sections 12, 14 are semi-cylindrical or symmetrical in shape, they are designed to fit securely together for receiving and centering the canister therein. Centering the canister within the interior chamber 16 of the heating jacket provides maximum heat conduction to the canister.

[0019] The heating jacket 10 may also include at least one support 34, for resting the jacket within the housing 100. In the embodiments shown in FIGS. 2-4, the supports 34 may be positioned on one of the front portion or the rear portion of the second section 14. Alternatively, there may be two supports, one of both the front and rear portion of the section. The support 34 or supports function to raise the jacket slightly off the floor of the housing 100, providing air circulation around the jacket. Alternatively, the support 34 may include an adjustment means, such as a screw, which can be rotated to lift the support and change the pitch of the heating jacket.

[0020] Heating and cooling of the heating unit 10 during use may result in an accumulation of condensation within the unit, and in particular between the layers of the sections if the layers are separately constructed rather than molded as a single sheet. Depending on the number of supports used and their location, the supports change the pitch angle of the jacket from a horizontal starting position to an angled position. Varying the pitch of the heating jacket aids in the drainage of any resulting condensation accumulating in the jacket, through a drain hole 36 (FIG. 3). The drain hole 36 may be located in the outer shell layer 34 in one section 12, 14, in both sections, or within other layers of the sections 12, 14. Coordinating the location of the drain hole 36 with the pitch of the heating jacket 10, specifically locating the opening on the downward end when the jacket is in the angled position, provides an effective system to drain excess moisture from the jacket.

[0021] The sections 12, 14 are designed to open completely away from one another for seating or removing a canister. As mentioned, the sections may be pivotally attached to one another at the end panels to open and close in a clamshell manner. Alternatively, the sections may not be joined together, but rather the first section 12 can be lifted upwards completely detached from the second section 14 for insertion or removal of the canister. To aid in the opening of the unit in either manner, a handle 24 may be provided. In an embodiment, the handle 24 may also be configured for use in securing the canister within the jacket when the handle is in the downward position.

[0022] In conjunction with the handle 24, the two sections 12, 14 may be secured together using a tool-less locking mechanism. For example, as shown in FIG. 2, the handle 24 may be a pivotal lever or toggle lever, which is connected to a securing bolt 24a. The handle 24 is simply lifted upward without the need for any special tools, releasing the securing bolt 24a, and thus separating the two sections from one another. Once a canister is removed or loaded into the heating unit 10, the handle 24 can be pushed downward, wherein the securing bolt 24a locks the two sections together. Using this type of locking mechanism avoids the need for special tools or other devices.

[0023] Referring to FIG. 4, each half or section 12, 14 of the jacket is constructed from a plurality of layered materials. Specifically, the layers include: an inner surface layer 26 constructed of a suitable heat conductive and durable material, such as aluminum; a heating element layer 28 constructed of a silicone encased resistive wire mesh; an insulation layer 30 constructed of any suitable insulation material such as foam or fiberglass; and an outer shell layer 32 constructed of any suitable durable material, such as a glass-filled polymer (nylon). The individual layers may be coextruded together, or optionally, the inner layer, heating element layer and insulation layer may be formed as a single sheet composite, which is then secured to the outer layer. For example and referring to FIG. 4, the inner layer 26 and the outer shell layer 32 each include a lip or edge 26a and 32a respectively, on either lateral side of the layer. When the layers are joined together, the entire section can be created by using attachment means, such as bolts or screws through the respective edges 26a, 32a. The remaining layers, specifically the heating element layer 28 and the insulation layer 30, which are slightly smaller in width and length than the outer shell layer 32 and the inner surface layer 26, are completely sealed between the secured outer shell layer and the inner surface layer.

[0024] It should be understood this is a representative example of the layered constructions of the present device, and that the number of layers and materials used therein, and the overall construction may vary according to the requirements of the application. However, it is advantageous to have the inner layer 26 forming the interior 16 of the unit, as it also functions as a conductive layer for uniform heating of the canister 200. Additionally, the inner layer 26 functions as a durable wear plate as the canister is frequently loaded and unloaded from the unit. The layered material sections insulate and direct the heat energy toward the ammonia-containing material stored within the canister, while isolating the heat source from the surrounding environment and its temperature influences. In this manner, the heating jacket 10 provides a consistent temperature and duration of heating to effectively release the ammonia gas from the ammonia adsorbing/desorbing material in the canisters.

[0025] The ammonia adsorbing/desorbing material in the canisters is generally compressed powder or granules, which may be loaded into the canisters as aluminum disks or balls. The material may be formed using existing powder metal press technology. Regardless of the technology used to prepare the material, it is important to prevent the dissipation of ammonia during the formation of the material. Suitable material for use in the present application include metal-ammine salts, which offer a convenient storage medium for ammonia, and represent a safe, practical and compact option for storage and transportation of ammonia. Ammonia may be released from the metal ammine salt by heating the salt to temperatures in the range from 10°C to the melting point to the metal ammine salt complex, for example, to a temperature from 30° to 700°C, and preferably to a temperature of from 100° to 500°C. Generally speaking, metal ammine salts useful in the present device include the general formula M( H₃)_nX_z, where M is one or more metal ions capable of binding ammonia, such as Li, Mg, Ca, Sr, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, etc., n is the coordination number usually 2-12, and X is one or more anions, depending on the valence of M, where representative examples of X are F, CI, Br, I, S0₄, Mo0₄, P0₄, etc. Preferably, ammonia saturated strontium chloride, Sr(NH₃)Ci2, is used. While embodiments using ammonia as the preferred reductant are disclosed, the invention is not limited to such embodiments, and other reductants may be utilized instead of, or in addition to, ammonia for carrying out the inventions disclosed and claimed herein. Examples of such other, or additional reductants include, but are not limited to, urea, ammonium carbamate, and hydrogen. [0026] As noted, in order to effectively release ammonia gas from the ammonia adsorbing/desorbing material, the material must be heated to a specific temperature. Heating of the canister within the heating unit 10 may be accomplished using a heating element (not shown), such as a resistive element, which generates heat when an electrical current is passed through the element, or a conduit for a liquid, such as engine coolant. The heating element may be installed within the heating element layer 28 of the sections 12, 14. Although not shown, it should be understood that the heating element is connected to a power source (not shown) and control device, such as an electronic control module (not shown) to control the amount of heat generated by the heating jacket, as well as the duration of heating.

[0027] Regulating the temperature of the heating unit 10 is important to ensure the proper and consistent release of ammonia gas from the ammonia storage material contained within the canisters. In order to better regulate the temperature within the heating jacket 10, a controller 38 is included in the unit. The controller 38 is typically a temperature detection resistor or thermistor. FIG. 5 illustrates the circuitry involved in the ASDS system including the thermistor associated with each heating jacket. The controller 38 in the present system may be located in the circuitry outside of the heating jacket, or embedded within one of the layers of the heating jacket, for example, within the heating element layer 28. The heating jacket 10 may include a plurality of thermistors, in addition to pressure sensors (not shown) for sending appropriate signals to an electronic control module (not shown) for monitoring and controlling the heating element of the heating jacket, or even controlling the sequential heating of multiple jackets in the system. In this manner, the temperature applied to the canister can be controlled within predefined limits, such that it does not damage surrounding components or even the ammonia-containing material within the canisters.

Claims

CLAIMS What is claimed is:

1. A heating unit for use in heating a canister containing a reductant for use in a NO_x reduction system, the unit comprising: a first section; a second section detachably connected to the first section defining an interior space for the receiving the canister; a heating element located in one of either the first section and the second section; and, a controller for regulating the heating element and maintaining an activating temperature within the interior space at a predefined limit,

2. The heating unit of claim 1, wherein the controller is integrated in one of either the first section and the second section.

3. The heating unit of claim 2, wherein the controller is a themistor.

4. The heating unit of claim 1, wherein the first section comprises plurality of layers.

5. The heating unit of claim 4, wherein one of the layers is an inner heat conductive layer defining the interior space of the unit.

6. The heating unit of claim 4, wherein one of the layers is the heating element layer.

7. The heating unit of claim 4, wherein one of the layers is an insulation layer.

8. The heating unit of claim 4, wherein one of the layers is an outer shell layer.

9. The heating unit of claim 1, wherein the second section comprises plurality of layers.

10. The heating unit of claim 9, wherein one of the layers is a heat conductive layer defining the interior space of the unit.

1 1. The heating unit of claim 9, wherein one of the layers is the heating element layer.

12. The heating unit of claim 9, wherein one of the layers is an insulation layer.

13. The heating unit of claim 9, wherein one of the layers is an outer shell layer.

14. A method for heating a canister containing an ammonia storage material for release of ammonia for use in the after-treatment exhaust system, the method comprising the steps of: providing a heating device having a first section and a second section, the sections being detachably connected to form an interior chamber for the receiving the canister; heating the device and canister to a predetermined temperature for release of the ammonia from the ammonia storage material into the after-treatment system; and, regulating the temperature at a predefined limit.

15. The method of claim 14, wherein the step of regulating the temperature comprises a controller.