Process and apparatus for the generation of a hydrogen-containing gas

The present invention relates to a method and apparatus for producing a hydrogen-rich gas. The invention refers in particular to a method for starting a gas generating device.

Hydrogen can be made of suitable fuels by exothermic partial oxidation, hereinafter referred to as POX, corresponding to equation<st32:che xmlns:st32="http://www.matrixware.com/ns/st32/">- (CH2) - + 1 / 2O₂ (Air) ⇒ H₂ + CO</st32:che>and / or endothermic steam reforming according to the equation<st32:che xmlns:st32="http://www.matrixware.com/ns/st32/">- (CH₂) - + 2H₂O ⇒ 3H₂ + CO₂</st32:che>be generated. It is also a combination of the two processes possible, which can lead to auto-thermal operation. Suitable fuels are particularly methanol, and other Hydrocarbon derivatives, such as higher alcohols, gasoline, diesel, LPG (Liquid Petroleum Gas) or NG (natural gas).

From US 3,982,910 is a hydrogen generator and a method for generating a soot-free hydrogen-rich gas known by partial oxidation. To start is in the generator Air with a spray of liquid hydrocarbon fuel mixed and ignited. With the heat of combustion is air to be supplied to a predetermined temperature preheated. After reaching this temperature, which the boiling temperature of the liquid fuel is located, is at Normal operation changed. In normal operation the fuel is evaporated, mixed with preheated air, and then the hydrogen-rich gas from the fuel mixture means partial oxidation generated in a combustion chamber of the generator. The air / fuel ratio upon starting the generator is set such that it above the normal operation, lies with vaporized fuel.

From EP 0646093 is a method for starting a Wasserdampfreformierungs- / partial oxidation process to convert a methane-containing feed gas into a hydrogen-rich Gas with a fluidized bed or colliding fluidized bed catalyst is known in which the tendency to clump together of the is the catalyst material is reduced. In this case, in a first Step a fluidized bed of inert particles, preferably Aluminum, of in an oxidizing atmosphere in the presence of Oxygen and in the absence of a reforming catalyst heated to the reaction temperature. Then a reducing Atmosphere generated before the reforming catalyst, preferably a nickel-containing catalyst, in the Fluidized bed is introduced. The feed gas is then the catalyst in the presence of oxygen in a hydrogen-rich Gas converted.

From EP 0887306 of the applicant is a method for Starting a gas generating device with downstream Gas purification step known, by means of partial oxidation and / or steam reforming of a fuel, a hydrogen-rich Gas is generated. For gas cleaning is a CO selective-oxidation stage, the platinum-containing generally a Catalyst comprises, used. During start up, the gas purification stage temporarily as catalytic Burners used by the fuel admixed oxygen and the flow direction is reversed such that first the gas purification stage and then the gas generating device flow through. About operated as a burner gas purification stage the device when you start is up to operating temperature heated.

From EP 0924163 of the applicant is a method for Start steam reforming by means of a reforming reactor, an evaporator, a catalytic burner and a membrane module for hydrogen separation known. For cold starts, a heating process is carried out, in a first operating phase, the reforming reactor and Evaporators are heated by the burner. In a second Operating phase, the reforming reactor with an opposing Normal operation increased water / hydrocarbon ratio operated and the reformate gas is the catalytic burner supplied through the membrane module. In a third phase of operation the heating, the supply of hydrogen or hydrocarbon reduces the catalytic burner. with increasing Operating temperature of the membrane module is the hydrocarbon portion the hydrocarbon / steam mixture in Evaporator up to the mixture ratio increases during normal operation.

From EP 0924161 of the applicant is a method for Operating a plant with both for the steam reforming and for partial oxidation suitable reactor an evaporator and a membrane module known. A catalytic Burner is provided to the reactor, the vaporizer and to bring the membrane module to operating temperature. At the Starting the plant, the reactor is in a first operating phase as a partial oxidation reactor with an opposite Normal operation lower operating pressure and operated in a second phase of operation of the reactor to a reforming operation changed and the pressure from Aufheizbetriebsdruck increased to normal operating pressure.

Furthermore, from the WO 99/31012 of the Applicant a method for operating a plant for steam reforming of a Hydrocarbon, in which a portion of a reforming reactor configured as a multi-function reactor unit is. During a cold start, the multi-function reactor unit is in a first operating phase with the same fuel supplied and oxygen-containing gas as a catalytic burner and in a second operating phase as a partial oxidation reactor (POX reactor) operated. During the transition from first to second Operating phase is also provided, the fuel / oxygen mixture hinzuzudosieren water and / or the amount of fuel flow with increasing temperature of the multi-function reactor unit to increase and / or the flow rate of the oxygen-containing Gas already during the first phase of operation substoichiometric adjust. By stoichiometric to adjust the production of fission products, such as Hydrogen, favored by thermal decomposition of fuel will. To appropriate conditions for the partial oxidation adjust the fuel, in the second Operational phase, the ratio of oxygen-containing gas and Fuel towards the first phase of operation is reduced. Of the remainder of the reactor part, that is not a multi-function reactor unit provided area, while the second operating phase, as Nachreformierungseinheit and CO shift converter stage used. In normal operation, the multi-function reactor unit at least temporarily, as a reforming unit used for hydrogen production.

In contrast, the invention has the object, a hydrogen-rich gas by means of a reactor for the to produce oxidation and a steam reformer, wherein counteracts aging of the catalyst the steam reformer shall be.

To achieve this object is firstly a process with the Features of claim 1 and, secondly, a device proposed with the features of claim fifth

By the method according to the invention ensures that the percentage of oxygen in the product gas of the POX reactor in each Operating phase is minimized. Unburned oxygen levels would oxidize the catalyst and the steam reformer so lead to increased aging of the catalyst.

In an advantageous development of the method is the Steam reformer heated by heating means. The heat of combustion of the fuel can thus essentially for heating the POX reactor used. Thereby, the POX reactor rapidly to the operating temperature for the partial brought oxidation, so that hydrogen-rich in a short time Gas on the partial oxidation available stands.

In a further advantageous embodiment of the invention is provided that generated in the POX reactor product gas is passed through an adiabatic, catalytic post-stage, unburned components of the fuel / oxygen or the Fuel / oxygen / water mixture in the product gas in the implement post stage so that the proportion of oxygen in the product gas minimizing the steam reformer before feeding. At the Combusting fuel in the POX reactor and in particular in low temperatures can in the product stream of the POX reactor unburnt components of the fuel / oxygen mixture occur. By reacting these remaining shares in the post- prevents this aging of the catalyst of the can cause reformer.

A gas generating device according to the invention comprises at least a POX reactor with a downstream steam reformer, wherein between the POX reactor and the steam reformer an adiabatic, catalytic post stage is arranged. about the POX reactor can when starting after a short time, hydrogen-rich Gas produced. With appropriate design the POX reactor can also the starting materials for the steam reforming heated and vaporized in POX reactor. In the post-stage catalytic unburned oxygen levels reacted POX the product stream, so that a minimal Oxygen content in particular at the beginning of Start phase is ensured and at low temperatures counteracted and an aging of the catalyst of the reformer becomes.

In an advantageous further development comprises the adiabatic, catalytic post stage a noble metal catalyst. Precious metals such as platinum are already at low temperatures catalytically active and are therefore particularly suitable.

In a r further advantageous development comprises the adiabatic, catalytic post stage a catalyst support with low heat capacity. The post-stage can thereby quickly and low thermal energy requirements to operating be heated.

In an advantageous further heating means for heating the steam reformer and / or the adiabatic, catalytic Post stage provided. This heating up is independent possible from the heat of combustion of the POX reactor. Especially the post stage can at the very beginning of the start-up phase Operating be brought, so that a minimization the proportion of oxygen in the product gas of the POX reactor already is ensured at the onset of combustion.

The invention is now based on an embodiment in the drawing and with reference explained to the drawing.

The single figure shows a schematic block diagram of a A gas generating apparatus according to the invention.

The gas generating device of the invention shown in the figure 1 comprises a reactor for the partial oxidation (POX reactor), a steam reformer 2 adiabatic, catalytic post-stage 3, between POX reactor 1 and steam reformer 2 and is connected (not shown) Heating means for heating the steam reformer 2 and / or As the post-3rd POX reactor and steam reformer are in particular conventional, known to those skilled reactors or reformer usable. Catalysts which can be, for example, used copper-containing and / or platinum-containing catalysts will. The adiabatic, catalytic post-stage 3 includes a Catalyst support with a low heat capacity and a noble metal-containing Catalyst, for example on the basis of of platinum. The post-stage 3 may preferably not in the ( shown in detail) collector passage of the POX reactor 1 or be integrated in the distribution channel of the reformer. 2

Starting materials for the production of hydrogen-rich gas are Fuel, oxygen-containing gas and / or water. preferred Fuel is methanol. However, other hydrocarbon derivatives, such as higher alcohols, gasoline, diesel, used LPG (Liquid Petroleum Gas) or NG (natural gas) will. The oxygen-containing gas is preferably used for air Use. All starting materials can of gas generating device are supplied via an input side 4 of the POX reactor first Here is a supply 5 for the liquid reactants such as fuel and water and a feed 6 for metering Air provided.

To start the gas generating device is first fuel dosed in the POX reactor 1 and then air for Combustion of the fuel admixed. This sequence it is ensured that when starting the device no unburned air from the POX reactor 1 into the reformer 2 arrives. The amount of air is adjusted so that this most the stoichiometric ratio of a full Combustion with the respective amount of fuel supplied equivalent. This is a complete conversion of the air in promoted the POX reactor 1, ie, oxygen levels in the POX product gas be minimized. The generated heat of combustion the POX reactor 1 is warmed up. The heat of combustion can also be used to additional system components such as the catalytic post-stage 3 or the Reformer 2 at least supportive to operating temperature to heat. For a quick start of the gas generating device but are separate heating means such as burners or electrical preferable heaters.

In the next phase of operation when reaching the operating temperature the partial oxidation in the POX reactor 1, the supplied Amount of air is reduced because the partial oxidation of the Fuel significantly less oxygen than the Combustion. At the same time water is added to a prevent overheating in the catalytic combustion and a transition for the steam reforming of fuel prepare. The air and / or amount of water is controlled so that a complete conversion of the fuel / oxygen / water mixture takes place to form hydrogen. Also in this phase of operation are characterized oxygen levels in the POX gas minimized due to unburnt air constituents.

Upon reaching the operating temperature of the steam reforming in the steam reformer 2, the amount of air supplied further reduced or interrupted, the air supply. In POX reactor 1 is thereby only a part of the supplied Fuel implemented. The major portion of the fuel is in the downstream steam reformer 2, the better a System efficiency than the POX reactor 1 has, under appropriate Water dosage converted to hydrogen. maintaining of the POX operation is advantageous because on the Dosing liquid fuel in the POX reactor 1 faster can respond to load changes as a quantity change the fuel / steam mixture of the reformer. 2 Through the use of the adiabatic, catalytic post stage 3 is achieved that is still present in the product gas of the POX reactor Oxygen levels, as especially at low occur temperatures due to unburnt air constituents can be catalytically reacted and thus a deterioration of the Reforming catalyst 2 is counteracted.