Patent Description:
The present invention relates to diesel reforming using a liquid desulfurizer.

Fuel cells are power generation systems that convert the chemical reaction energy of hydrogen and oxidant contained in hydrocarbon-based materials such as hydrogen, methanol, and ethanol into direct electrical energy. Since a fuel cell uses hydrogen as a fuel, the hydrogen for the fuel cell can be obtained through steam reforming from a hydrocarbon-based fuel such as methane, methanol, natural gas, gasoline and diesel. A fuel reformer can be classified into steam reforming, partial oxidation reforming and autothermal reforming according to a reforming method.

Steam reformers are suitable for fuels with a high hydrogen content in the reformed gas and short carbon chains such as methane and natural gas. In addition, the steam reforming reaction is suitable for a Solid Oxide Fuel Cell (SOFC) system having a high operating temperature, because the reformed gas contains a high temperature. However, the steam reformer consumes a large amount of heat to generate steam, thus heat recovery is complicated and the manufacturing costs of the reactor are increased due to these reasons.

Partial oxidation reforming is the process in which the feed fuel, such as methane or a suitable hydrocarbonaceous fuel, reacts exothermically in the presence of a small amount of air. However, the partial oxidation process cannot be used for gasifying gasoline, diesel, methanol, or ethanol, because of the decrease in energy content of the fuel.

<CIT>, <CIT> and <CIT> disclose methods for desulfurizing liquid fuels to be used in fuel cells.

Diesel has high volumetric hydrogen density and gravimetric density. This makes diesel reforming an attractive option for a Solid Oxide Fuel Cell (SOFC) system. Accordingly, there is a continual need for diesel reformers using diesel fuel, which yields improved system efficiency. Some diesel reforming processes may remove sulfur compounds in diesel fuel downstream of reforming diesel fuel. The operating temperature range of desulfurizing diesel fuel may be lower than the operating temperature range of reforming diesel fuel. Thus, to remove sulfur compounds from diesel fuel, the reformed diesel fuel may be cooled prior to being desulfurized. Also, to use this reformed and desulfurized diesel fuel for a SOFC system, desulfurized diesel fuel may be heated to fit an operating temperature range of a SOFC system.

The presently-described systems and processes of diesel reforming may eliminate these cooling and heating steps. Therefore, the systems and process for reforming diesel fuel may enable efficient and cost effective converting diesel fuel into hydrogen and methane for a Solid Oxide Fuel Cell.

A method of diesel reforming according to the present invention is defined in claims <NUM> to <NUM>.

Additional features and advantages of the described embodiments will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the described embodiments, including the detailed description which follows and the claims.

The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the following drawing in which:.

Embodiments of the present disclosure are directed to a diesel reformer system and a method of diesel reforming. Referring to <FIG>, an embodiment of a diesel reforming system <NUM> is shown. The diesel reforming system <NUM> comprises a diesel autothermal reformer <NUM>, a liquid desulfurizer <NUM> disposed upstream of the diesel autothermal reformer <NUM>.

In operation, the diesel reforming system <NUM> may conduct the following diesel reforming method as shown in <FIG>. As shown in <FIG>, the method of diesel reforming includes introducing a first diesel fuel feed <NUM> to a combustor <NUM>, wherein the combustor <NUM> generates heat <NUM> from combustion of the first diesel fuel feed <NUM>. The heat delivered to the liquid desulfurizer <NUM> raises the temperature of the liquid desulfurizer <NUM> to operating temperature. A second diesel fuel feed <NUM> is then fed to the liquid desulfurizer <NUM>. At the operating temperature, the liquid desulfurizer <NUM> removes sulfur compounds to produce desulfurized diesel fuel <NUM>. Referring again to <FIG>, the desulfurized diesel fuel <NUM> as well as air feed 42A and steam <NUM> are passed to a diesel autothermal reformer <NUM> wherein the desulfurized diesel fuel <NUM> is at least partially converted to a diesel reformate <NUM>. Next, the diesel reformate <NUM> is passed to a post-reformer <NUM> disposed downstream of the diesel autothermal reformer <NUM>, wherein the post-reformer <NUM> selectively decomposes low carbon (C<NUM>-C<NUM>) hydrocarbons in the diesel reformate into hydrogen and methane.

Referring again to <FIG>, the diesel reforming system <NUM> may include a diesel fuel tank <NUM> which contains the diesel fuel <NUM> used in the diesel reforming system <NUM>. The diesel fuel <NUM> may be pumped from the diesel fuel tank <NUM> using pump <NUM>. In the embodiment of <FIG>, the diesel fuel <NUM> may be fed to a regulating valve <NUM>, which splits the diesel fuel <NUM> into the first diesel fuel feed <NUM> that is fed to the combustor <NUM> and the second diesel fuel feed <NUM> that is fed to the liquid desulfurizer <NUM>. The regulating valve <NUM>, which may be a three way valve as depicted in the embodiment of <FIG>, regulates the amount of diesel fuel supplied to the liquid desulfurizer <NUM> and the amount of diesel fuel supplied to the combustor <NUM>, which enables the regulating valve <NUM> to supply diesel fuel to the combustor <NUM> while also heating up the liquid desulfurizer <NUM>. Various algorithms and control methodologies are contemplated for use with the regulating valve <NUM> that controls the ratio of the first and second diesel fuel feeds supplied to the combustor <NUM> and the liquid desulfurizer <NUM>, respectively.

Moreover, the diesel reforming system <NUM> also includes an air source 40B for the combustor <NUM>. An air feed 42B from the air source may be delivered by a blower <NUM> to the combustor <NUM>. In one embodiment, the combustor <NUM> may include an atomizer nozzle <NUM> at the inlet of the combustor <NUM>. As shown, the first diesel fuel feed <NUM> and air feed 42B is delivered to the atomizer nozzle <NUM>, and then the atomized diesel fuel and air are injected into the combustor <NUM> through the atomizer nozzle <NUM>. The amount of diesel fuel supplied in the first diesel fuel feed <NUM> to the combustor <NUM> may vary depending on the operation of the diesel autothermal reformer <NUM>. In one embodiment, all of the first diesel fuel feed <NUM> supplied to the combustor <NUM> may be completely burned at the time of startup so that the temperature of the liquid desulfurizer <NUM> rapidly increases. The first diesel fuel feed <NUM> may have a lesser volume compared to the second diesel fuel feed <NUM>, because a lesser amount of diesel fuel is required for the combustor <NUM>, since the liquid desulfurizer <NUM> may be heated with the small amount of diesel in a steady state.

Various structural embodiments are contemplated for the combustor <NUM>. In one embodiment, the combustor <NUM> is a diesel combustor comprising a diesel combustion catalyst. Various diesel combustion catalysts would be considered suitable and familiar to the skilled person, for example, metallic or organometallic catalysts comprising one or more of iron, ceria, or platinum.

The combustor <NUM> may have an operating temperature range of from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>. The combustor <NUM> may be operated in these temperature ranges to prevent damage to the combustion catalyst. In one embodiment, these operating temperature ranges of the combustor <NUM> may be controlled by supplying the additional air.

As stated previously, the liquid desulfurizer <NUM> removes the sulfur components contained in the second diesel fuel feed <NUM>. Various structures are contemplated for the liquid desulfurizer <NUM>. For example, the liquid desulfurizer <NUM> may be formed of a porous support (including a support having through-pores along a fluid conveying direction) through which the fluid is passed and which impregnates a desulfurizing catalyst. Various catalysts are considered suitable for the desulfurizing catalyst. In one or more embodiments, the desulfurizing catalysts for the liquid desulfurizer <NUM> may include multi-component catalysts such as cobalt/molybdenum (CoMo) or nickel/molybdenum (NiMo). As the liquid desulfurizer <NUM> is upstream of the diesel autothermal reformer <NUM>, the catalysts are different than the catalysts typically used in a downstream desulfurizer, which may often use zinc oxide (ZnO). While the present embodiments do not depict a downstream desulfurizer, it is contemplated that a further downstream desulfurizer could be included.

From an operating standpoint, the liquid desulfurizer <NUM> may have an operating temperature range of <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>. The temperature of the liquid desulfurizer <NUM> may be increased and maintained by the heat <NUM> generated by the combustor <NUM>.

The pressure of the liquid desulfurizer <NUM> may be a pressure of <NUM> bars or more. The pressure of the liquid desulfurizer <NUM> may be a pressure of from <NUM> bars to <NUM> bars, or from <NUM> bars to <NUM> bars, or from <NUM> bars to <NUM> bars, or from <NUM> bars to <NUM> bars, or <NUM> bars to <NUM> bars, or <NUM> bars to <NUM> bars.

Referring again to <FIG>, the pressure may be maintained by one or more valves <NUM>, <NUM> proximate the liquid desulfurizer <NUM>. The present embodiments may include a front valve <NUM> positioned upstream of the liquid desulfurizer <NUM> and a rear valve <NUM> positioned downstream of the liquid desulfurizer <NUM>. The front valve <NUM> controls the injection of the second diesel fuel feed <NUM> into the pressure while the rear valve <NUM> is closed to build up the requisite pressure in the liquid desulfurizer <NUM>. Subsequently, the desulfurized diesel fuel <NUM> is discharged at a pressure while the rear valve is at least partially opened. In one embodiment, the pressure of the desulfurized diesel fuel <NUM> may act on an atomizer nozzle <NUM> disposed upstream of the diesel autothermal reformer <NUM> to help atomize the diesel fuel.

Referring again to <FIG>, the diesel autothermal reformer <NUM> includes an air feed 42A and at least one steam feed <NUM>. The air feed 42A is delivered by air blower <NUM>, which is in communication with the air source 40A. The steam feeds are produced from water source <NUM>, which may be a water reservoir, water tank, or the like. Water <NUM> is pulled via pump <NUM> from the water source <NUM> and may then pass to distributing valve <NUM>. As shown, the distributing valve <NUM>, which may be a three way valve as shown in the embodiment of <FIG>, may direct a first water feed <NUM> to a first heat exchanger <NUM>, wherein the first water feed <NUM> is converted into a first steam feed <NUM> via heat exchange with combustion product <NUM>, a high temperature gas discharged from the combustor <NUM>. The high-temperature gas discharged from the first heat exchanger <NUM> may be expelled to the atmosphere as a vent stream <NUM>. Moreover, the distributing valve <NUM> may also direct a second water feed <NUM> to a second heat exchanger <NUM>, wherein the second water feed <NUM> is converted into a second steam feed <NUM> via heat exchange with post-reformer product <NUM>, a high-temperature gas discharged from the post-reformer <NUM>. The high temperature reformed gas stream <NUM> discharged from the second heat exchanger <NUM> may be injected into a Solid Oxide Fuel Cell stack (not shown).

While various heat exchanger types are contemplated, the first heat exchanger <NUM> and second heat exchanger <NUM> are shell and tube heat exchangers in the present embodiment. The amount of steam supplied to the diesel autothermal reformer <NUM> through the first heat exchanger <NUM> and the amount of steam supplied to the diesel autothermal reformer <NUM> through the second heat exchanger <NUM> may vary depending on operating conditions of the system. Like the regulating valve <NUM> discussed previously, various algorithms and control methodologies are contemplated for use with the distributing valve <NUM> that controls the ratio of the first steam feed <NUM> and second steam feed <NUM> supplied to the diesel autothermal reformer <NUM>.

From an operational standpoint, the diesel autothermal reformer <NUM> performs a reforming reaction that converts the desulfurized diesel fuel <NUM> to produce a diesel reformate <NUM>, a hydrogen-rich fuel. The diesel reformate <NUM> comprises syngas (i.e., hydrogen and carbon monoxide). The reforming reactions conducted by the diesel autothermal reformer <NUM> are as follows:.

CnHm + aO<NUM> + bH<NUM>O → cH<NUM> + dCO + eCO<NUM> + fH<NUM>O (each n, m, a, b, c, d, e, and f could be a rational number and controlled by changing the reaction conditions).

As stated previously, an atomizer nozzle <NUM> is disposed proximate the inlet of the diesel autothermal reformer <NUM>. The desulfurized diesel fuel <NUM> and air feed 42A are introduced into the diesel autothermal reformer <NUM> through the atomizer nozzle <NUM>, and the diesel fuel is consequently atomized. Moreover, the desulfurized diesel fuel <NUM> flows into the atomizer nozzle <NUM> with sufficient pressure for easier atomization.

The diesel autothermal reformer <NUM> utilizes high pressure and high temperature operating conditions. For example, the diesel autothermal reformer <NUM> may have an operating temperature of at least <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>. Moreover, the diesel autothermal reformer <NUM> may have an operating pressure of at least <NUM> bar, or from <NUM> to <NUM> bars, or from <NUM> to <NUM> bars, or about <NUM> bar at atmospheric condition.

Various structural embodiments are contemplated for the diesel autothermal reformer <NUM>. The internal and external partition walls of the diesel autothermal reformer <NUM> may be formed of any material having high durability at a high temperature (about <NUM>° C. ) and an excellent heat transfer efficiency. For example, the internal and external partition walls can be substantially formed of stainless steel. In another embodiment, the diesel autothermal reformer comprises a porous support (including a support having through-pores along a fluid conveying direction) through which the fluid is passed and which impregnates the catalyst. In one or more embodiments, the catalyst comprises a noble metal catalyst. Various catalysts suitable for performing the autothermal reforming reactions among the supplied diesel fuel, water and air are contemplated herein. The noble metal catalyst may include Pt, Rh, Ru and a mixture thereof. The catalysts may be supported or unsupported. In supported catalyst embodiments, the catalyst support may comprise alumina, silica, ceria, or combinations thereof. While various amounts of noble metal catalyst are considered suitable, the amount of the noble metal catalyst may be controlled according to a kind of hydrocarbon-based fuel to be reformed, an amount of the supplied fuel and the like.

Referring again to <FIG>, the diesel reformate <NUM> is introduced to a post-reformer <NUM> disposed downstream of the diesel autothermal reformer <NUM>. Here, the post-reformer <NUM> selectively decomposes low carbon (C<NUM>-C<NUM>) hydrocarbons in the diesel reformate <NUM> into a post-reformer product <NUM> comprising hydrogen and methane. In detail, by the post-reforming catalyst, the low carbon hydrocarbon material (C<NUM>-C<NUM>) in the diesel reformate <NUM> is reacted with hydrogen and vapor contained in the diesel reformate <NUM> to be selectively decomposed into hydrogen and methane.

The inlet of the post-reformer <NUM> utilizes high temperature and high pressure operating conditions. For example, the inlet of the post-reformer <NUM> may have an operating temperature range of from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or about <NUM>. Moreover, the inlet of the post-reformer <NUM> may have an operating pressure of at least <NUM> bar, or from <NUM> to <NUM> bars, or from <NUM> to <NUM> bars, or about <NUM> bar at atmospheric condition.

The outlet of the post-reformer <NUM> utilizes high temperature and high pressure operating conditions. For example, the outlet of the post-reformer <NUM> may have an operating temperature range of from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>. Moreover, the outlet of the post-reformer <NUM> may have an operating pressure of at least <NUM> bar, or from <NUM> to <NUM> bars, or from <NUM> to <NUM> bars, or about <NUM> bar at atmospheric condition.

The post-reformer product <NUM>, which is a high temperature reformed gas discharged from the post-reformer <NUM> is used as a heat source for the second heat exchanger <NUM>, and the discharged product of the second heat exchanger <NUM> may then be supplied to the solid oxide fuel cell stack (not shown).

In one or more embodiments, the post-reformer <NUM> comprises a post-reforming catalyst formed of a transition metal, a noble metal, or a mixture thereof. In one or more embodiments, the transition metal of the post-reforming catalyst includes Ni, Mg and a mixture thereof, and the noble metal thereof includes Pt, Rh, Pd, Ru and a mixture thereof. Like the diesel autothermal reforming catalysts, the post-reforming catalysts may be supported or unsupported. In supported catalyst embodiments, the catalyst support may comprise alumina, silica, ceria, or combinations thereof. Like the diesel autothermal reformer <NUM>, the post-reformer <NUM> can be formed of a porous support (including a support having through-pores along a fluid conveying direction) through which the fluid is passed and which impregnates the post-reforming catalyst.

The system and method of diesel reforming of the present disclosure may heat diesel fuel prior to reforming diesel fuel. The system and method of diesel reforming may not require additional heating, cooling diesel fuel, or both. Therefore, the systems and process for reforming diesel fuel may enable efficient and cost effective converting diesel fuel into hydrogen and methane for a SOFC.

The following examples illustrate one or more additional features of the present disclosure. It should be understood that these examples are not intended to limit the scope of the disclosure or the appended claims in any manner.

Example <NUM> was conducted at a pilot plant having the configuration and characteristics of the system <NUM> illustrated in <FIG>. In Example <NUM>, diesel fuel, which qualifies for the fuel quality standards set by Ministry of Environment of South Korea, was introduced to the liquid desulfurizer at the flow rate of <NUM>/min. At the liquid desulfurizer, the temperature of diesel fuel was changed from <NUM> (the inlet of the liquid desulfurizer) to <NUM> (the outlet of the liquid desulfurizer) in liquid state. To heat up the diesel fuel, <NUM> W energy was required for 1kW electric generation (<NUM> % energy loss) in the SOFC. The liquid desulfurizer removed sulfur compounds (from <NUM> ppm (the inlet of the liquid desulfurizer) to <NUM> ppb (the outlet of the liquid desulfurizer)) from the diesel fuel to produce desulfurized diesel fuel. The content of sulfur compounds was measured by using a gas detecting tube manufactured by Gastec Co. The desulfurized diesel fuel was introduced to the diesel autothermal reformer with air and steam to convert desulfurized diesel fuel to a diesel reformate. The temperature of desulfurized diesel fuel was changed from <NUM> (the inlet of the diesel autothermal reformer) to <NUM> (the outlet of the diesel autothermal reformer). The content of sulfur compounds of the diesel reformate was less than <NUM> ppb at the outlet of the diesel autothermal reformer. The diesel reformate was sent out of the diesel autothermal reformer and introduced to the post-reformer. The post-reformer decomposed C<NUM>-C<NUM> hydrocarbons in the diesel reformate into hydrogen, carbon monoxide, carbon dioxide, and methane, as shown in Table <NUM>. The temperature of the diesel reformate was changed from <NUM> (the inlet of the post-reformer) to <NUM> (the outlet of the post-reformer). Without any cooling or heating process, hydrogen and methane was directly introduced into SOFC system.

Comparative Example <NUM> was conducted at a pilot plant having the autothermal reformer, a post-reformer disposed downstream of the autothermal reformer, and the desulfurizer disposed downstream of the post-reformer. The autothermal reformer, post-reformer, and desulfurizer were incorporated into a single reactor unit. In Comparative Example <NUM>, diesel fuel, which qualifies for the fuel quality standards set by Ministry of Environment of South Korea, was introduced to the autothermal reformer with air and steam to convert the diesel fuel to a diesel reformate. The flow rate was measured at the inlet of the autothermal reformer. The temperature of diesel fuel was changed from <NUM> (the inlet of the autothermal reformer) to <NUM> (the outlet of the autothermal reformer). In Comparative Example <NUM>, compositions of each stream are shown in Table <NUM>. The diesel reformate was introduced to the post-reformer to produce the post diesel reformate. The temperature of diesel reformate was changed from <NUM> (the inlet of the post-reformer) to <NUM> (the outlet of the post-reformer). The post diesel reformate was sent out of the post-reformer and cooled down by water (from <NUM> to <NUM>). To cool down the post diesel reformate, <NUM> W energy was required for 1kW electric generation (<NUM> % energy loss) in SOFC. The cooled post diesel reformate was introduced to the desulfurizer to remove sulfur compounds (from <NUM> ppm to less than <NUM> ppb) from the cooled post diesel reformate. The temperature of cooled post diesel reformate was changed from <NUM> (the inlet of the desulfurizer) to <NUM> (the outlet of the desulfurizer). After removing sulfur compounds, the desulfurized post diesel reformate was heated to fit an operating temperature range (<NUM>-<NUM>) of the SOFC system and introduced into the SOFC system.

Comparing the process of Example <NUM> to the process of Comparative Example <NUM>, the process of Example <NUM>, which utilizes a liquid desulfurizer and avoids post-reformate cooling and heating steps, enables more efficient conversion of diesel fuel into hydrogen and methane (<NUM>% energy loss for Example <NUM> vs <NUM> % energy loss for Comparative Example <NUM>). Moreover, in Example <NUM>, without any cooling or heating process, hydrogen and methane was directly introduced into SOFC system because the temperature of hydrogen and methane at the outlet of the post-reformer (<NUM>) fit an operating temperature range (<NUM>-<NUM>) of the SOFC system. In contrast, in Comparative Example <NUM>, prior to introducing into the desulfurizer, the post diesel reformate was cooled down by water. In addition, prior to introducing into the SOFC system, the desulfurized post diesel reformate was heated to fit an operating temperature range (<NUM>-<NUM>) of the SOFC system.

It should be understood that any two quantitative values assigned to a property may constitute a range of that property, and all combinations of ranges formed from all stated quantitative values of a given property are contemplated in this disclosure. It should be appreciated that compositional ranges of a chemical constituent in a composition or formulation should be appreciated as containing, in one or more embodiments, a mixture of isomers of that constituent. It should be appreciated that the examples supply compositional ranges for various compositions, and that the total amount of isomers of a particular chemical composition can constitute a range.

It is noted that one or more of the following claims utilize the term "wherein" as a transitional phrase. For the purposes of defining the present technology, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce a recitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term "comprising.

Claim 1:
A method of diesel reforming comprising:
introducing a first diesel fuel feed to a combustor, wherein the combustor generates heat from combustion of the first diesel fuel feed;
passing the heat to a liquid desulfurizer wherein the heat raises the temperature of the liquid desulfurizer to operating temperature;
introducing a second diesel fuel feed to the liquid desulfurizer, wherein the liquid desulfurizer at operating temperature removes sulfur compounds to produce desulfurized diesel fuel;
introducing the desulfurized diesel fuel, as well as air and steam to a diesel autothermal reformer to at least partially convert the desulfurized diesel fuel to a diesel reformate; and
introducing the diesel reformate to a post-reformer disposed downstream of the diesel autothermal reformer, wherein the post-reformer selectively decomposes low carbon (C<NUM>-C<NUM>) hydrocarbons in the diesel reformate into hydrogen and methane.