Primary reformer with secondary inlet channels supplying the burner

Translation of description of equivalent WO 2008131832 A1

p0001Primary reformer with brennerzuführenden secondary inlet channels

p0002[0001] The invention relates to a reactor for the catalytic reforming of hydrocarbons with steam under elevated pressure and is produced by the synthesis gas. Such synthesis gas is used for example for the production of ammonia, hydrogen and methanol.

p0003[0002] Reactors for catalytic reforming of hydrocarbons with steam have been known and known in a variety of embodiments. For large plants, a design has prevailed, in which a cover-fired oven box comes with vertical reaction tubes or cracking tubes used. Here, the cracking tubes are arranged in rows. The tubes are flowed through by process gas, which forms the feed gas from top to bottom. The feed gas is subjected to a so-called split process.

p0004[0003] The gas outlet temperatures are usually at 850 ⁰C and above. The process gas is at the bottom - collected in so-called exit panels - inside or outside the furnace. In the lying between the rows of tubes "streets" are straight down firing burner arranged. This area is referred to as Ofenbox. The flue gas produced by the furnace passes from top to bottom and is drawn off by lying on the ground, so-called flue gas tunnel. Temperatures in the Ofenbox to average 1000-1250⁰C. The furnace walls are dressed for thermal insulation and protection from the prevailing by heating to high temperatures with a refractory protective layer off.

p0005[0004] The heated through the furnace reaction chamber typically has a plurality of gas-tight vertical tubes which are arranged in rows and suitable for filling with a catalyst. These are used for process control and hold means for supplying to be reformed hydrocarbon and up to 650⁰C heated water vapor to the reaction chamber and means for discharging the reformed synthesis gas from the reaction chamber.

p0006[0005] The furnace chamber in which the lighting devices are arranged sawn sits in the lower part of the room, a chamber for collecting the flue gases as well as a plurality of substantially horizontally disposed, parallel to each other and perpendicular to the vertical tubes running tunnels of masonry to Deduction of the flue gases. These brick have tunnel on the sides of openings to allow the withdrawal of the flue gases from the furnace chamber. The tunnels are usually built from masonry materials.

p0007[0006] WO2005 / 018793 A1 describes a typical furnace system and process for the catalytic reforming of hydrocarbons with steam to synthesis gas at elevated pressure. For better homogenization of the flue gas flow and a more uniform temperature distribution of firing a special design of the outer walls of the tunnel is applied. WO2006 / 119812 A1 describes a typical furnace system and process for the catalytic reforming of hydrocarbons with steam to synthesis gas with addition of oxygen to adjust the stoichiometry and a special downstream porous burner to avoid the formation of soot.

p0008[0007] All reforming systems described have in common that a firing device, which consists of a plurality of arranged between the process leading reaction tubes burners, the furnace chamber heated by leading by this reformer tubes. The firing of the furnace chamber serving burners are usually supplied via separate channels with fuel gas and air. The supply of the fuel gas in the burner chamber is in this case carried out separately from the air supply. The passage of the gas supply in the combustion chamber takes place through the refractory furnace lining or immediately before. In the constructions previously used the heating gas to air ratio of the burners by a throttle valve or a similar kind device for adjusting the Gasdurch- controlled flow of air supply. About this device allows the burner firing and therefore the furnace temperature control. This construction is effective but has the disadvantage that the local air supply to the burners can control bad and sometimes leads to unfavorable conditions for heating gas to air.

p0009[0008] The oxygen-fuel gas ratio can be described technically called Lambda (λ) value. When a stoichiometric molar ratio of oxygen to fuel gas a lambda value is obtained from 1 0th When using a lower ratio in the stoichiometric combustion oxygen content to obtain a lambda value which is lower than 1, the 0th When using a higher ratio in the stoichiometric combustion oxygen content gives a lambda value, which is higher than 1, 0th A combustion is therefore optimal when the lambda Value 1, 0 is. In conventional constructions is obtained at the individual burners lambda values ​​which vary for operational reasons and can have temporarily elevated levels.

p0010[0009] This has a disadvantageous effect on the combustion process. The result is a higher overall consumption of heating gas may be based on the conversion of the reforming process. When changing the fuel, the air supply can be adjusted only with difficulty to the change in stoichiometry. This may temporarily to an unwanted increase in the flame temperature and the increased inflow of air to an increased formation of nitrogen oxides of the type NO_x come. Nitrogen oxides contribute to the pollutants in the atmosphere to acid rain.

p0011[0010] The object of the invention is therefore to find a way to improve the air supply in the combustor system in that the air supply is optimally adjustable in the burner over the entire duration of the process. This improves Heizgasverbrennung and thus the Heizgasausbeute the reforming process. always optimal lambda values ​​should be adjusted to the individual burners so that the flame temperature always has the only necessary height. This allows the formation of harmful nitrogen oxides are significantly reduced or completely off presents.

p0012[0011] The invention achieves the object by a reactor for catalytic primary märreformierung of hydrocarbons with steam under elevated pressure with a device for ceiling lighting a Reformierprozessofens, wherein • the firing device heats a thermally insulated furnace chamber with the O- fenraum gastight process leading reformer tubes, which are to be charged with a suitable catalyst for reforming processes and is passed through the one Reformiergasgemisch, and

p0013• the firing device of a plurality of between reforms ming pipes arranged burners there, and

p0014• is the firing device supplied with fuel gas and air, and

p0015• in each of the burners separate both gases feeders exist, each arranged in alignment and individually or in pairs are jointly shut off, and • the mixture of the two gases in each burner or is carried out immediately before, and where • the feeder for air in each burner a main inlet channel and an additional secondary inlet channel, and

p0016• both inlet ducts are equipped with facilities that are adapted to adjust the gas flow, and • each secondary inlet channel is branched from the respective main inlet channel to the device for adjusting the gas flow, and the other, secondary channel forms a primary air duct, and

p0017• the ratio of the cross-sectional areas of the secondary inlet channel to the inlet of the main channel before the branching of the secondary inlet channel between view 1: 2 and 1: 100.

p0018[0012] Here, each burner is individually supplied with a fuel gas-air mixture, and for both gases exist separate feeders and the main air supply channel allows additional air supply to the Brennerkonstruk- tion through the refractory furnace lining ( "secondary inlet channel"). The mixture of fuel gas and burner is respectively made in the burner.

p0019[0013] In one embodiment of the invention devices are equipped secondary inlet channels and main inlet ducts with singly or in pairs in common lockable feeding.

p0020[0014] In a further embodiment of the invention, the secondary throttle valve can be operated in each case immediately adjacent to the associated main throttle. This allows the operator to set both feeders in one work step.

p0021[0015] Preferably, all the feeding channels are directed into the firing chamber downward and are arranged in alignment. The feed direction of the air inlet ducts may, depending on type of construction of the furnace tilted or paragraphs GE leads be to ensure the technical feasibility of firing. The devices for supplying the air into the combustion chamber can be configured via slots through the refractory furnace lining. This design allows a more accurate distribution of the air in a burning room. Optional and depending on the structural design of the furnace chamber this slot shape can be performed to optimize combustion via swirler or Y-pipes with distributors. [0016] In other embodiments of the invention are alternatively

p0022• the secondary intake passages branching out from the perpendicular guided downward in the combustion chamber, or

p0023• the secondary inlet channels are inclined or have a paragraph, or

p0024• the secondary inlet ducts in the burner entrance area are marked in the form of a slot or a swirler or a bifurcated tube.

p0025[0017] The invention also includes a process for the catalytic Primärrefor- optimization of hydrocarbons with steam under elevated pressure with a device for firing a ceiling Reformierprozessofens using the apparatus according to the invention. Here, it is provided that

p0026• the firing device a thermally insulated furnace chamber with fenraum in the O- gastight process leading reformer tubes heats, which are to be charged with a suitable catalyst for reforming processes and is passed through an Reformiergasgemisch, and

p0027• the firing device of a plurality of between reforms mierrrohren arranged burners there, and

p0028• is the firing device fed with a fuel gas and air, and

p0029• in each of the burners for both gases separate feeders exist, each arranged in alignment and individually or in pairs are jointly shut off, and

p0030• the mixture of the two gases in the burner or in each case is performed immediately before, and

p0031• the feeder for air in each of the burner has a Hauptein- outlet channel and an additional secondary inlet duct, and

p0032• both inlet ducts are equipped with facilities that are adapted to adjust the gas flow, and

p0033• each secondary inlet channel is branched from the respective main inlet channel to the device for adjusting the gas flow, and the other, secondary channel forms a primary air duct, and

p0034• the ratio of the cross-sectional areas of the secondary inlet channel to the inlet of the main channel before the branching of the secondary inlet channel is between 1: 2 and 1: 100, and

p0035• (Lambda (λ) value) of 1, 05-1, 15 used as a mixture ratio of air to fuel gas at the outlet of a constant stoichiometry Primäreinlasska- Nals provides is. The exit of the air-fuel gas mixture from the primary inlet channel is also referred to as a burner block.

p0036[0018] For the inventive embodiment of Primärreformierprozesses is preferred for heating a gas-air mixture used. In a further embodiment of the process the burner is instead heated by a natural gas-air mixture with a LPG air mixture. As LPG hydrocarbons commonly referred to a mixture of C₃- And C₄Hydrocarbons that are obtained from the corresponding petroleum fraction and are easy to liquefy. Suitable as heating gas are instead of natural gas or LPG, other hydrocarbons, preferably having lower then room temperature boiling point.

p0037[0019] The described type of supplying secondary air into the flame, the air supply is optimized in the burner. This achieves depending control of an optimum ratio of air to fuel gas and an optimal control of the flame. The maximum flame temperature can be kept relatively low by this measure in the oven.

p0038[0020] Ordinary constructions Reformiersynthese put to the burners typically a lambda value of approximately 1, 1 a. However, this figure may vary for operational reasons. In inventive embodiments of the construction of the secondary inlet channel can be opened in particular at higher air volume supply, so that the additional air is directed past the Primärauslasskanal. This allows the local lambda value in the burner block constant at 1, are held 05-1, 15, even if in the flame adjusting a lambda value of 1, 1 to 1; 5.

p0039[0021] In one embodiment of the method the adjustment of the mixing ratio of fuel gas to air at the outlet of the primary intake passage is effected by setting the disposed in the inlet region throttle in the feed channels.

p0040[0022] In a further embodiment of the method includes the reforming methane and heated water vapor. The reforming gas in the apparatus according to the invention by heat exchanging devices in the exhaust version tunnel outside the furnace chamber with the burner exhaust gas to a temperature 500-650⁰C are heated. [0023] In another embodiment is the method, the heating of the burner air required by heat exchanging devices with the burner exhaust gas to a temperature of 250 to 450 ⁰C heated. Here, the exhaust gases in the exhaust version tunnel behind the heat-exchanging device Einrich- be used for heating the reformate gas so that the temperature is about 150-200 ° C is usually at the tunnel relationship manner chimney outlet.

p0041[0024] The discharge of the combustion gases takes place via the above-mentioned flue gas tunnel made of masonry. The tunnel on the sides have openings to allow the withdrawal of the flue gases from the furnace chamber. By this measure, an efficient removal of the flue gases is ensured over the entire furnace space. The tunnels are usually built from masonry materials.

p0042[0025] The embodiments mentioned the advantage of an optimized setting of the air-fuel gas ratio at the burners and an optimal control of combustion in terms of setting an optimum lambda value. It is well known that the nitrogen oxide content NO_x an exhaust gas by using a favorable lambda value at the burner stone markedly lowered. It is also known that the content of nitrogen oxides NO_x an exhaust gas markedly reduced when setting a lower flame temperature. This can relevantly known reference works are taken. One example is the teaching of "The John Zink Combustion Handbook", CE Baukel Jr., CRC Press, London New York, 2001 called. Nitrogen oxides of the type NO_x contribute to acid rain.

p0043[0026] The inventive design of the burner and the delivery system for fuel gas and air is explained in more detail with reference to two drawings, showing a section of the reformer in side view, with the inventive method is not limited to these embodiments.

p0044[0027] FIG. 1 shows the schema of the air and Heizgaszuführung to the burner, starting from the main air supply duct 1. From that each individual feed channels for air 2 to the individual burners branch off, of which four are here exemplified. The individual main air supply channels can be con- trolled by individually lockable and independent regulatory bodies. 3 Of these, then the secondary inlet channel 4 of the invention for air branches off upstream of the burner feeder, which also has an individually blockable and independent control means 5th The main air supply duct is then used as primary märeinlasskanal the air supply discontinued. In this, the fuel gas 6 is fed immediately prior to the burner. The infeed occurs at the refractory O- fenauskleidung 7 through to ensure the flame guide 8 into the furnace chamber. then the funds earmarked for the reforming reactions are heated action pipes 9 By this firing.

p0045[0028] FIG. 2 shows the delivery system once in a reduced form. Shown is also the scheme of air and Heizgaszuführung am Brenner, starting from the main air supply duct 1. From this each branch each Alloca- guide channels (shown here fourfold example for clarity) for air 2 to the individual burners off. The individual main air supply channels can be controlled by individually lockable and independent regulatory bodies. 3 Of these, then the secondary inlet channel 4 of the invention for air branches off upstream of the burner feeder, which also has an individually blockable and independent control means 5th The main air supply channel is then passed as the primary inlet port of the air supply. In this, the fuel gas is fed over 6 control devices immediately prior to the burner. The infeed system passes through to the furnace refractory lining 7 to ensure the flame guide 8 into the furnace chamber.

p0046[0029] List of Reference Numbers

p00471 main air supply duct to the burner system

p00482 main air supply duct of each burner

p00493 air supply control means of the main inlet channel

p00504 secondary inlet channel

p00515 air feed control device of the secondary intake port

p00526 Heizgaszuführung

p00537 passage refractory furnace lining ( "burner block")

p00548 flame guide

p00559 Reformiergasrohre