Plasmatron having an air jacket and method for operating the same

BACKGROUND

[0001] The present disclosure relates generally to a fuel reformer, and more particularly to a plasmatron having an air jacket and method for operating the same.

[0002] Hydrogen has been used as a fuel or fuel additive for an internal combustion engine in an effort to reduce emissions from the engine. One manner of producing hydrogen for use with an internal combustion is by the operation of a plasmatron. A plasmatron reforms hydrocarbon fuel into a reformed gas such as hydrogen-rich gas. Specifically, a plasmatron heats an electrically conducting gas either by an arc discharge or by a high frequency inductive or microwave discharge. The internal combustion engine combusts the hydrogen-rich gas from the plasmatron either as the sole source of fuel, or in conjunction with hydrocarbon fuels.

[0003] A plasmatron may also be utilized to supply hydrogen-rich gas to devices other than internal combustion engines. For example, hydrogen-rich gas reformed by a plasmatron may be supplied to a fuel cell for use by the fuel cell in the production of electrical energy.

[0004] Systems including plasmatrons are disclosed in U.S. Pat. No. 5,425,332 issued to Rabinovich et al.; U.S. Pat. No. 5,437,250 issued to Rabinovich et al.; U.S. Pat. No. 5,409,784 issued to Brumberg et al.; and U.S. Pat. No. 5,887,554 issued to Cohn, et al., the disclosures of each of which is hereby incorporated by reference.

SUMMARY

[0005] According to one aspect of the disclosure, there is provided a plasmatron. The plasmatron reforms hydrocarbon fuels so as to produce a reformed gas which is supplied to an external device such as an internal combustion engine or a fuel cell. The plasmatron includes an air jacket which removes heat from the reaction chamber of the plasmatron and supplies heated air to the plasma-generating assembly of the plasmatron.

[0006] A method of operating a plasmatron is also disclosed herein. The method includes the step of reforming a fuel in a reaction chamber defined in a plasmatron housing so as to produce a reformed gas. The method also includes the step of advancing air through a jacket and into the reaction chamber. The jacket is positioned around a portion of the periphery of the housing.

[0007] According to another aspect of the disclosure, there is provided an apparatus for reforming hydrocarbon fuel into a reformed gas. The apparatus includes a housing having a reaction chamber defined therein and a jacket having an air chamber defined therein. The jacket is positioned around a portion of the periphery of the housing. The air chamber is in fluid communication with the reaction chamber.

[0008] The above and other features of the present disclosure will become apparent from the following description and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The detailed description particularly refers to the accompanying figures in which:

[0010]FIG. 1 is a cross sectional view of a first embodiment of a plasmatron, note that the fuel injector is not shown in cross section for clarity of description; and

[0011]FIG. 2 is a view similar to FIG. 1, but showing a second embodiment of a plasmatron.

DETAILED DESCRIPTION OF THE DRAWINGS

[0012] Referring now to FIGS. land <b>2</b>, there is shown a fuel reformer. The fuel reformer is embodied as a plasmatron <b>10</b> which uses a plasma—an electrically heated gas—to convert hydrocarbon fuel into a reformed gas such as a hydrogen-rich gas.

[0013] Hydrogen-rich gas generated by the plasmatron <b>10</b> may be supplied to an internal combustion engine (not shown) such as a diesel engine or spark-ignition gasoline engine. In such a case, the internal combustion engine combusts the reformed gas as either the sole source of fuel, or alternatively, as a fuel additive to a hydrocarbon fuel. Alternatively, hydrogen-rich gas generated by the plasmatron <b>10</b> may be supplied to a fuel cell (not shown) such as an alkaline fuel cell (AFC), a phosphoric acid fuel cell (PAFC), a proton exchange membrane fuel cell (PEMFC), a solid oxide fuel cell (SOFC), a molten carbonate fuel cell (MCFC), or any other type of fuel cell. In such a case, the fuel cell utilizes the hydrogen-rich gas in the production of electrical energy.

[0014] The plasmatron <b>10</b> includes a plasma-generating assembly <b>12</b>, a reactor <b>14</b>, and an air jacket <b>16</b>. As shown in FIG. 1, the reactor <b>14</b> includes a reactor housing <b>18</b> having a reaction chamber <b>20</b> defined therein. The plasma-generating assembly <b>12</b> is secured to an upper portion <b>22</b> of the reactor housing <b>18</b>. Specifically, the plasma-generating assembly <b>12</b> includes an upper electrode <b>24</b> and a lower electrode <b>26</b>. The electrodes <b>24</b>, <b>26</b> are spaced apart from one another so as to define an electrode gap <b>28</b> therebetween. An insulator <b>30</b> electrically insulates the electrodes from one another. Collectively, portions of the electrodes <b>24</b>, <b>26</b>, the insulator <b>30</b>, a gasket <b>36</b>, and a cap <b>38</b> define a plasma housing <b>40</b>.

[0015] The electrodes <b>24</b>, <b>26</b> are electrically coupled to an electrical power supply (not shown) such that, when energized, a plasma arc <b>32</b> is created across the electrode gap <b>28</b> (i.e., between the electrodes <b>24</b>, <b>26</b>). A fuel input mechanism such as fuel injector <b>34</b> injects a hydrocarbon fuel <b>44</b> into the plasma arc <b>32</b>. The fuel injector <b>34</b> may be any type of fuel injection mechanism which produces a desired mixture of fuel and air and thereafter injects such a mixture into the plasma housing <b>40</b>. In certain configurations, it may be desirable to atomize the fuel mixture prior to, or during, injection of the mixture into the plasma housing <b>40</b>. Such fuel injector assemblies (i.e., injectors which atomize the fuel mixture) are commercially available.

[0016] As shown in FIG. 1, the configuration of the plasma housing <b>40</b> defines an annular air chamber <b>42</b>. Pressurized air in the air chamber <b>42</b> is directed radially inwardly through the electrode gap <b>28</b> so as to “bend” the plasma arc <b>32</b> inwardly. Such bending of the plasma arc <b>32</b> ensures that the injected fuel <b>44</b> is directed through the plasma arc <b>32</b>. Such bending of the plasma arc <b>32</b> also reduces erosion of the electrodes <b>22</b>, <b>24</b>.

[0017] As shown in FIG. 1, the lower electrode <b>24</b> extends downwardly through an air inlet <b>46</b> defined in the reactor housing <b>18</b>. As such, reformed gas (or partially reformed gas) exiting the plasma arc <b>32</b> is advanced into the reaction chamber <b>20</b>. One or more catalysts <b>78</b> are positioned in reaction chamber <b>20</b>. The catalysts <b>78</b> complete the fuel reforming process, or otherwise treat the reformed gas, prior to exit of the reformed gas through a gas outlet <b>48</b>.

[0018] The aforedescribed configuration of the plasmatron <b>10</b> is exemplary in nature, with numerous other configurations of plasmatron being contemplated for use in regard to the present disclosure. Specifically, the herein described air jacket <b>16</b> (including features thereof) is contemplated for use in regard to any particular design of a plasmatron.

[0019] The air jacket <b>16</b> envelops the reactor <b>14</b>. Specifically, the air jacket <b>16</b> is positioned around a portion of the periphery of the reactor housing <b>18</b>. It should be appreciated that the configuration of the air jacket <b>16</b> depicted in FIGS. 1 and 2 is exemplary in nature and that other configurations of the air jacket <b>16</b> are contemplated for use. For example, the lower portion of the jacket <b>16</b> may be extended downwardly (as viewed in the orientation of FIGS. 1 and 2) so as to also envelop the lower portion <b>50</b> of the reactor housing <b>18</b>. The jacket <b>16</b> may also be extended upwardly (as viewed in the orientation of FIGS. 1 and 2) to envelop a larger portion of the plasma-generating assembly <b>12</b>. The jacket <b>16</b> may also be configured to more closely or less closely “conform” to the outer shape of the reactor housing <b>18</b> or the components of the plasma-generating assembly <b>12</b>.

[0020] The air jacket <b>16</b> has an air chamber <b>52</b> defined therein. In the case of the air jacket <b>16</b> depicted in FIG. 1, structures of the air jacket <b>16</b>, along with certain structures of the reactor housing <b>18</b>, cooperate to define the air chamber <b>52</b>. Specifically, the air jacket <b>16</b> has a side wall <b>54</b> which has an inner wall surface <b>56</b> and an outer wall surface <b>58</b>. Similarly, a side wall <b>60</b> associated with the reactor housing <b>18</b> has an inner wall surface <b>62</b> and an outer wall surface <b>64</b>. As such, the air chamber <b>52</b> is defined by the area between the outer wall surface <b>64</b> of the reactor side wall <b>60</b> and the inner wall surface <b>56</b> of the jacket side wall <b>54</b>. In such a configuration, a short wall extension <b>80</b> may be utilized to “bridge” the distance between the upper edge of the reactor housing <b>18</b> and the plasma housing <b>40</b>.

[0021] Alternatively, as shown in FIG. 2, the jacket <b>16</b> may be configured with both an inner wall and an outer wall such that the air chamber <b>52</b> is defined entirely by structures associated with the jacket <b>16</b>. Specifically, the air jacket <b>16</b> may include an outer jacket wall <b>66</b> and an inner jacket wall <b>68</b>. The air chamber <b>52</b> is defined by the area between the two walls <b>66</b>, <b>68</b>. Such a configuration of the air jacket <b>16</b> (i.e., use of two walls as opposed to one) is particularly useful in the design of certain configurations of the plasmatron <b>10</b>. For example, as shown in FIG. 2, it may be desirable to utilize an air jacket <b>16</b> constructed with both an inner and outer side wall when the design of the plasmatron include a sleeve of thermal insulation <b>70</b> interposed between the reactor housing <b>18</b> and the air jacket <b>16</b>.

[0022] In either configuration of the air jacket <b>16</b>, air is advanced through the jacket <b>16</b> and into the annular air chamber <b>42</b> of the plasma housing <b>40</b>, and ultimately into the reaction chamber <b>20</b>. Specifically, the air jacket <b>16</b> includes one or more air inlets <b>72</b> and one or more air outlets <b>74</b>. The inlets <b>72</b> and the outlets <b>74</b> may be configured as orifices which are defined in the walls of the jacket <b>16</b>, or, alternatively, may include a tube, coupling assembly, or other structure which extends through the wall of the jacket <b>16</b>. In any case, air, typically pressurized air, is advanced through the air inlets <b>72</b>, through the air chamber <b>52</b> of the jacket <b>16</b>, through the outlets <b>74</b> of the air jacket <b>16</b>, into an air inlet <b>76</b> of the plasma housing <b>40</b>, and into the annular air chamber <b>42</b>. As described above, pressurized air in the annular air chamber <b>42</b> is directed radially inwardly through the electrode gap <b>28</b> so as to “bend” the plasma arc <b>32</b> inwardly thereby ensuring that the injected fuel <b>44</b> is directed through the plasma arc <b>32</b>. From there, the pressurized air, along with the reformed gas (or partially reformed gas), is directed through the air inlet <b>46</b> of the reactor housing <b>18</b>, and into the reaction chamber <b>20</b> such that the gas may be further treated by the catalysts <b>78</b> prior to exhaust of the reformed gas through the gas outlet <b>48</b>.

[0023] It should be appreciated that air is heated during advancement thereof through the jacket <b>16</b>. Specifically, the reactions in the reactor chamber <b>20</b> are exothermic in nature. As such, heat generated by the reactions in the reactor chamber <b>20</b> is transferred to the air advancing through the air chamber <b>52</b> of the jacket <b>16</b> via a thermal path which includes the side wall <b>60</b> of the reactor housing <b>18</b> (in the case of the plasmatron of FIG. 1), or a thermal path which includes the side wall <b>60</b> of the reactor housing <b>18</b>, the sleeve of thermal insulation <b>70</b>, and the inner jacket wall <b>68</b> of the air jacket <b>16</b> (in the case of the plasmatron <b>10</b> of FIG. 2).

[0024] Such removal of heat from the reaction chamber <b>20</b> is particularly useful in certain applications of the plasmatron <b>10</b> in which it is desirable to cool the reformed gas prior to delivery thereof to another device (e.g., an internal combustion engine or a fuel cell). Moreover, in certain configurations, it may be desirable to maintain a certain temperature within the reactor chamber <b>20</b> in order to enhance the efficiency of the catalytic reactions being performed therein. In such a case, the thickness and material type of the sleeve of thermal insulation <b>70</b> may be varied in order to maintain a desired temperature within the reaction chamber <b>20</b>, with any residual heat transferred from the thermal insulation <b>70</b> to the air advancing through the air jacket <b>16</b>.

[0025] Moreover, heating the air advancing through the air jacket <b>16</b> also enhances the plasma generation process of the plasma-generating assembly <b>12</b>. Specifically, the plasma reforming process of the plasmatron <b>10</b> is enhanced as a result of the generation of a relatively hot plasma (e.g., 1,000°-3,000° C.). As such, the introduction of heated air into the plasma process facilitates the creation and maintenance of a hot plasma. Hence, by heating air in the air jacket <b>16</b> prior to the introduction thereof into the plasma process, heat for facilitating the creation of the high temperatures associated with the plasma process may be created without having to utilize an additional heating device such as heat exchangers which are distinct from the plasmatron <b>10</b>. This enhances the overall operating efficiency and lowers the cost of the system (e.g., engine or fuel cell system) into which the plasmatron <b>10</b> is integrated.

[0026] In operation, the plasmatron <b>10</b> is operated to reform a hydrocarbon fuel into a reformed gas such as hydrogen-rich gas. To do so, a fuel <b>44</b> is injected into a plasma arc <b>32</b> which alone, or in concert with one or more catalysts <b>78</b>, reforms the fuel into the reformed gas which is then exhausted or otherwise advanced through a gas outlet <b>48</b> and thereafter supplied to an external device such as an internal combustion engine or a fuel cell.

[0027] Heated air is utilized during the above-described reforming process. Specifically, air is advanced through the air inlets <b>72</b> of the air jacket <b>16</b> and into the air chamber <b>52</b>. Once inside the air chamber <b>52</b>, heat is transferred from the reactor chamber <b>20</b> to the air as it is advanced through the chamber <b>52</b>. The heated air is then advanced out the air outlets <b>74</b> of the jacket <b>16</b>, through the air inlet <b>76</b> of the plasma housing <b>40</b>, and into the annular air chamber <b>42</b>. Air is then directed through the electrode gap <b>28</b>, impinged upon the plasma arc <b>32</b>, and then advanced, along with reformed gas (or partially reformed gas) through the inlet <b>46</b> of the reactor housing <b>18</b> and into the reaction chamber <b>20</b>.

[0028] While the disclosure is susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and has herein be described in detail. It should be understood, however, that there is no intent to limit the disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.

[0029] There are a plurality of advantages of the present disclosure arising from the various features of the apparatus and methods described herein. It will be noted that alternative embodiments of the apparatus and methods of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of an apparatus and method that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the present disclosure.

[0030] For example, additional layers of thermal insulation may be utilized. Specifically, a sleeve of thermal insulation may be positioned around the air jacket <b>16</b> of the plasmatron <b>10</b> of FIGS. 1 and 2.