SE423896B - COMPACT CATALYTIC REACTION EQUIPMENT FOR THE PRODUCTION OF GAS PRODUCTS FROM THE HYDRAULIC FUEL - Google Patents

Description

7713226-4 i_2_ produced the heat energy of the furnace in the form of waste gas with high temperature (i.e. heat loss). Consequently, large amounts of fuel must be used to achieve a high degree of heating. If the heat energy is not used for a side-by-side process, such as steam production, it is lost. Even if the waste heat is used, it is not used for the production of hydrogen, and thus the thermal efficiency of the reactor is reduced, and the costs of hydrogen production rise.

In parallel with the development of the fuel cell power plant, the need for cheap hydrogen as a fuel arose, as well as the need for low construction costs, so that Bsbaæl 'uaftm fl äqn fi m fi m was able to compete with existing electric power plants. These needs further motivated the industry to reduce the size and cost of the fuel treatment equipment used in the conversion of hydrocarbon fuels to hydrogen. U.S. Pat. Nos. 3,144,312 and 3,541,729 both seek to reduce the size of the reaction apparatus while increasing thermal efficiency. The extent to which this succeeds, if successful, is not easy to determine, but in the following description, the disadvantages of these constructions will be highlighted in comparison with the present invention.

U.S. Pat. No. 3,909,299 discloses a steam conversion reactor construction having some advantageous properties, but it is also not as efficient or can be as compact as the apparatus of the invention as set forth below.

An object of the present invention is to provide a catalytic reaction apparatus which can operate at high thermal reactor efficiency.

Furthermore, it is intended to provide a compact catalytic reaction apparatus.

A third object of the invention is to provide a catalytic reaction apparatus which is not only compact but also exhibits high thermal reactor efficiency and which operates at high degrees of heating.

The catalytic reaction apparatus according to the invention consists of an annular reaction chamber in a furnace, where the heat of reaction is generated by l) hot furnace gas flowing in the opposite direction to the flow through the reaction chamber inside a narrow annular part coaxial with and arranged next to the outer wall of the annular reaction chamber and of 2) regeneration heat from the reaction products leaving the reaction chamber and flowing towards the flow through the reaction chamber inside a narrow annular part coaxial with and arranged next to the inner wall of the reaction chamber , where the annular part transporting the reaction products is mainly insulated from the heat action of the furnace gas. The invention is particularly suitable for mounting a large number of reactors in a compact furnace space.

In order to achieve high heating rates at low cost (i.e. the rate at which heat is transferred from the hot furnace gases to the reaction stream per wall unit, which separates the two streams), a compact application is required. High thermal reactor efficiency requires a high conversion of process fuel to hydrogen together with a minimal fuel consumption in the furnace. Intricate and expensive constructions in order to avoid extreme thermal loads arising from temperature differences between the connected parts, should not be necessary.

The above is achieved by means of the invention, in which two streams are used to heat the reaction stream. The main heat source comes from the countercurrent flow of furnace gases through a narrow annular portion along the outer wall of the annular reaction chamber, while the other heat source is regenerative heat from the reaction products leaving the reaction chamber and flowing opposite through a narrow annular portion along this inner wall. The utilization of opposite flows and narrow annular gas heating ducts is necessary to achieve optimum heating rate and optimum thermal reactor efficiency.

A high transfer efficiency of regeneration heat reduces the necessary furnace heat output per process fuel flow unit. Therefore, more fuel can be treated with the same fuel consumption in the furnace (i.e. the appliance works with an overall higher thermal efficiency). The magnitude of the annular gap in each of the two annular channels which conduct the hot gases in heat transfer relationship to the reaction chamber is critical in this connection, determining how much of the available heat in the heat streams is actually transferred to the reaction stream. .

In describing the present invention, it is expedient to consider the parameter called heat transfer efficiency (E).

The heat transfer efficiency corresponds to the enthalpy variation of the heat flow divided by the theoretically maximum enthalpy variation. In other words, if the heating stream has enthalphine E1 at its inlet temperature T1 and enthalphin E2 at the outlet temperature T2, and if the heated stream has an inlet temperature T3, then the heat transfer efficiency between the two streams is shown by the following function: - 7713226 - 1 2 E: El - E3 where E3 = enthalpy of heat flow at temperature T3.

It is also important to define the thermal efficiency of the reactor (?): N LHV (in H2) (H2) (F (LHvr) + åFf (LHvf) where NH2 = net amount of hydrogen produced, LHVH2 = lower hydrogen heating r) value, Fr = the amount of process fuel added to the reaction, and LHVr and LHVf = the lower heating values for the process and the furnace fuel respectively. The above assumes that hydrogen is the desired reaction product. The function can be easily changed to refer to other reaction products.

It is an advantage to remember that?>, Is almost proportional to E, with high efficiency requiring high heat transfer efficiency.

The main advantage of the reaction apparatus according to the invention is that it can give a high thermal reactor efficiency over a wide range of heating degrees (including very high ones), while the apparatus is compact. The result is a sustainable, compact, economical and efficient design, which allows high throughput of process fuel.

The invention will be described in more detail below with reference to the accompanying drawings, in which Figure 1 is a partially vertical cross-section through the catalytic reaction apparatus according to the invention, and Figure 2 is a cross-section through the apparatus according to Figure 1 and substantially along line 2-2.

An example of the catalytic reaction apparatus 10 according to the invention is shown in Figures 1 and 2. In this embodiment, the object of the apparatus is a conversion of convertible hydrocarbon fuel to hydrogen by means of suitable catalysts. The apparatus 10 comprises a furnace 12 with combustion nozzles 14, a fuel collecting pipe 16 and an air collecting pipe 18. A number of cylindrical reactors 20 are arranged in the furnace 12.

Each reactor consists of an outer cylindrical wall 22 and an inner cylindrical wall or inner tube 24, between which an annular reaction chamber 26 is defined. The reaction chamber is filled with conversion catalyst particles 28, which rest on a grid 30 mounted at the inlet 32 of the reaction chamber. Any suitable steam conversion catalyst, such as nickel, can be used to fill the reaction chamber from the inlet 32 to its outlet 36. The cylinder formed by the outer wall 22 is closed at the upper end 38 by a capsule nut 40. .

The inner tube 24 has an upper inlet end 42 and a lower outlet end 44. The inlet end opens below the capsule nut so that the inner tube is in gas communication with the outlet of the reaction chamber.

Arranged in the inner tube is a cylindrical plug 46, the outer diameter of which is slightly smaller than the inner diameter of the inner tube, forming an annular reaction chamber 48 with an inlet 49. The plug 46 may be a solid rod, but in the exemplary embodiment it is a tube which is closed at one end by a capsule nut 50 so that the reaction products leaving the reaction chamber 26 will flow around the plug through the regeneration chamber 48. The distance between the plug 46 and the inner tube 24 is obtained by means of projections 52 on the wall of the plug.

In the invention, the task of the regeneration chamber is to return heat from the reaction products leaving the outlet 36 to the catalyst bottom of the reaction chamber, so for the purposes of the invention, the outlet 54 of the regeneration chamber 48 is to be arranged in the immediate vicinity of the catalyst bottom inlet 32 instead. for at the outlet end 44 of the inner tube, despite the fact that the space formed between the plug 46 and the inner tube 24 extends to the outlet end 44. In the construction shown in Figure 1, there is a certain preheating of the process fuel before it is led into the catalyst bottom, but this is not critical to the invention. Furthermore, in the exemplary embodiment, the plug 46 extends the full length of the reaction chamber so that the inlet 49 of the regeneration chamber is arranged in the immediate vicinity of the outlet 36 of the reaction chamber, but although this is preferred, the inlet of the regeneration chamber can be arranged anywhere between the inlet by using a shorter plug.

Note that the regeneration chamber is mainly isolated from the hot furnace gases. In order to achieve maximum reactor efficiency, it is important to prevent the reaction products in the regeneration chamber from being heated by the heat energy of the furnace gas. Only noticeable heat in the reaction products already at the outlet 36 is transferred to the reaction chamber.

Each reactor 20 can be considered to comprise an upper part 56 and a lower part 58. The upper part is arranged in what is hereinafter referred to as the burner chamber 60. The burner chamber is the part of the furnace 12 where the combustion of the fuel and the air supply to the furnace takes place. This part of the furnace is characterized by very high temperatures, considerable radiant heating, as well as convection heating of the reactors 20, and axial (i.e. in the axis direction of the reactors) as well as radial mixing of the contained gases.

The lower portion 58 of each reactor is surrounded by a cylindrical wall or tube 62 spaced from the wall 22, forming an annular fuel gas passage 64 with an inlet 66 and an outlet 67. The outlet 67 is disposed in the immediate vicinity of the reaction chamber 26. inlet. The channel 64 is filled with a heat conducting material such as alumina balls 70 resting on a grid 68. The gap 72 between adjacent tubes 62 is filled with a heat insulating material such as ceramic fiber insulating material arranged on a plate 74 extending transversely through the furnace and having holes through which the reactors 20 pass. The plate 74 and the material in the gap 72 prevent the furnace gases from flowing around the outside of the tube 62.

In addition to the plate 74, the plates 76, 78 and 80 also extend across the furnace and form channels therebetween. The plate 80 rests on the bottom 82 of the furnace. A reaction product duct is formed between the plates 78 and 80, a process fuel inlet duct 86 is formed between the plates 76 and 78 and the plates 74 and 76 form a furnace gas outlet duct. The plugs 46 and the inner tubes 24 abut the bottom plate 80, the outer walls 22 of the reactors abut the plate 78 and the tubes 62 abut the plate 74.

During operation, a mixed stream of steam and convertible hydrocarbon fuel is passed from the duct 86 to the inlet 32 of the reaction chamber 26 via the holes 90 in the wall 22, the duct being supplied to the mixture from a tube 92. The mixture immediately begins to be heated by the hot furnace gases flowing in the opposite direction. fuel gas channel 64 and begins to react under the influence of the catalyst particles 28. As the fuel, steam and reaction products move up through the reaction chamber 26, they continue to react and collect additional heat. At the outlet 36, the temperature of the reaction products is maximum. The hot reaction products pass through the inlet 49 of the regeneration chamber 48. As the reaction products move through the annular regeneration chamber, the heat is transferred from there back to the reaction chamber 26. Thereafter, the reaction products are passed to the channel 84 through the holes 94 in the inner tube 24, and out of the reactor. 96 for either further processing, storage or consumption.

The fuel for the furnace is supplied to the duct 16 via a pipe 98 and then passes into the burner chamber 60 via nozzles 14. Air is supplied to the duct 18 via a pipe 100 and enters the burner chamber via annular passages 102 surrounding each nozzle 14. The fuel and air combustion takes place in the burner chamber 60. The hot gases from the burner chamber pass through the channels 64 to the channel 88 and transmitted via the tube 103.

Inside the burner chamber, the temperature is normally high enough to achieve high degrees of heating above the upper parts 56 of the reaction chamber, despite the relatively low heat transfer coefficient in this range. As the temperature of the furnace gases decreases as they move further away from the nozzles, the degree of heating will normally be unacceptably low, but this is not the case according to the invention through the use of annular fuel gas ducts over the lower parts of the reactors 58. These ducts increase when the correct size, the local heat transfer coefficient and thus the level of heat transfer efficiency. This results in high degrees of heating over both the upper and lower parts, despite the lower temperature of the furnace gases over the lower parts.

The size of the annular spaces on the combustion gas channel, the reaction chamber and the regeneration chamber are of primary importance for achieving high degrees of heating. According to the invention, the gaps are designed to allow the highest possible heat transfer efficiency, compatible with the desired outlet temperature of the furnace gases and the reaction products. Although heat transfer efficiency theoretically increases with narrower flue gas ducts and smaller regeneration chamber gaps, within a particular area of use, practical limitations such as maximum allowable wall temperatures and pressure drops in the gaps will be important factors in determining allowable minimum gaps. The gap size of the reaction chamber is chosen to together with the size of the gap of the fuel gas channel and the regeneration chamber produce a sufficiently high temperature over the entire catalyst bottom, without the furnace gases in the fuel gas channel heating the reaction products in the regeneration chamber on the other side of the bottom. In other words, as mentioned above, the regeneration chamber must be completely isolated from the heating effect of the furnace gases.

In this connection, it is interesting to compare the invention with the apparatus shown in the aforementioned U.S. Pat. patents 3,541,729 and 3,144,312.

In U.S. Pat. U.S. Pat. No. 3,541,729 flows the heating current of the furnace in the same direction as the flow through the annular catalyst bottom along its inner wall. This method is clearly less effective and differs from the opposite flow of the invention along the outer wall of the bottom. In addition, the highest furnace gas temperatures are in the vicinity of the inlet end of the catalyst bottom, which is the coldest end, so that the heat transfer in this area can become so large that a significant amount of heat from the furnace gases is transferred to the upper parts of the regeneration stream. in the annular part 113.

This heat leaves the furnace with the reaction products, thereby reducing the overall thermal efficiency of the reactor. This is done according to the invention, since the fuel gas is coldest at the inlet of the reaction chamber as a result of the opposing flow.

U.S. U.S. Pat. No. 3,144,312 differs from the invention in that the furnace gases are located in the vicinity of the inner annular catalyst bottom. Furthermore, the furnace gases flow in the vicinity of both the internal and the external reaction stream in contrast to the invention, in which the regeneration stream is substantially isolated from the hot furnace gases, which is an important condition for the invention. Note further that the relatively cool outer cylinder wall 10 is fixedly attached to the relatively hot inner cylinder wall 9. The loads resulting from differential thermal propagation between these two walls are likely to be unacceptably high and could cause operating error. In addition, none of the known apparatuses is intended to be used with a number of reactors in a single furnace.

To return to the invention, it has been established that a relatively narrow range of gap sizes provides good reactor thermal efficiencies at both high and low process fuel throughput. The heat conducting material 70 inside the ducts 64 further improves the heat transfer efficiency and a uniform heat distribution compared to an annular space of the same size but without heat conducting material. As the heat transfer efficiency is improved at less annular intervals, the heat conductive material in the present embodiment can be dispensed with if the size of the annular fuel gas duct is reduced. This change is considered to be within the scope of the invention, but a larger annular channel with thermally conductive material is preferred, as it is more difficult and expensive to maintain acceptable dimensional tolerances as the gaps become smaller. Acceptable gap sizes with and without thermally conductive materials are given in Table 1, and the best results are obtained if one stays within the preferred ranges given in Table 2. The ranges given are assumed calculations, which are mainly based on test results. It should be noted that for reactors with very large or very small diameters, the specified ranges must be extended. -9- 7715226-4 Table l Acceptable annular gap sizes Reaction chamber 7.62 - 50.8 mm Regeneration chamber 2.54 - 25.4 mm Flue gas duct (without heat-conducting material) 2.54 - 25.4 mm Flue gas duct (with heat-conducting material) 12 , 7 - 76.2 mm Table 2 Preferred annular gap sizes Reaction chamber 12.7 - 38.10 mm Regeneration chamber 3.175 - 12.7 mm Flue gas duct (without heat-conducting material) 6.35 - 12.7 mm Flue gas duct (with heat-conducting material) 12, 7 - 50.8 mm Some other factors that determine the choice of gap size are: the properties of the gases and the catalyst particles, thickness and thermal conductivity of the walls that separate the heating and the heated gas, and the Reynolds number of the different streams. With regard to the walls which separate the opposing currents, these are usually made as thin as possible, combined with structural strength, and of materials which are not violently expensive but which exhibit good thermal conductivity. The catalyst is normally selected due to its good reactivity and high durability. The catalyst particle size is normally chosen as small as possible to give maximum catalyst area, but not so small that an unacceptable pressure drop occurs in the reaction chamber.

Example 1

In a 19 tube steam conversion reaction apparatus similar to that shown in Figures 1 and 2, each reactor was 152.4 cm long, measured from the inlet 32 and had an outer wall 22.86 cm in diameter. Half the reactor (76.2 cm) extended into the burner chamber. The distance between the outer walls 22 of adjacent reactors 22 was 7.62 cm and the reactors on the side of the furnace wall were located 10.16-12.7 cm from this.

The gap between the outer wall 22 and the inner wall 24 was 27.9 mm, between the inner wall 24 and the plug 46 6.35 mm and between the tube 62 and the outer wall 22 31.75 mm. The flue gas duct was filled with 12.7 mm diameter alumina rush rings and the catalyst was used in the form of cylindrical particles. The process fuel consisted of naphtha which was introduced into the catalyst bottom in the form of a vapor mixture of 4.5 parts of steam per unit weight. The process fuel speed was about 11.3 kg / h per reactor with a total fuel speed of about 215 kg / h. A conversion rate of 95% was achieved and the overall thermal efficiency of the reactors was 90%.

Example 2.

In a steam conversion reaction apparatus with only one tube according to the invention, the reactor was 152.4 cm long, measured from the inlet 32 and showed an outer wall diameter of 22.86 cm. Half the reactor (76.2 cm) extended into the burner chamber. The distance between the outer wall of the reactor and the furnace wall was around 7.62 cm. The space between the outer wall 22 and the inner wall 24 was 27.9 mm, between the inner wall and the plug 46 '6.35 mm and between the tube 62 and the outer wall 22 31.75 mm. The fuel gas channel was filled with alumina spheres with a diameter of 12.7 mm, while the catalyst was in the form of cylindrical particles. The process fuel was naphtha, which was introduced into the bottom as a steam mixture with 4.5 parts of steam per unit weight. The process fuel flow rate was 27.7 kg / h. The conversion rate was 88% and the overall thermal efficiency of the reactor was 87%.

The manifold arrangement and burner construction according to the drawings are only examples and are not critical of or form part of the invention, the invention relating to both one and several reactions.

However, the invention is particularly suitable if several reactors are arranged in a single furnace, since the same allows close application of the reactors by ensuring both uniform and highly efficient heating of the lower parts of the reactors.

Tightly fitted reactors or reactor tubes involve a non-linear arrangement of at least three reactors, where the arrangement is mainly to fill the interior of the burner chamber and where the reactors are substantially evenly distributed and arranged at the same and rather small spaces inside the burner chamber. For example, provided the burner chamber is cylindrical, an arrangement of three tightly arranged reactors may consist of an equilateral triangle with a reactor in each corner, an arrangement of five tubes may consist of a centrally located reactor surrounded by four in a square placed reactors. Nine reactors can be arranged in a square arrangement consisting of three parallel rows with three reactors, respectively.

An arrangement of hexagonal type with 19 reactors is shown in Figure 2. At all times, at least a part of each reactor receives a significantly reduced amount of radiation from the wall of the burner chamber. For example, reactors closest to the wall receive significantly reduced radiation on the side facing away from the wall, and further, some of the reactors will

Claims (10)

_11- 7713226-4 receive a significantly reduced radiation due to other reactors in the arrangement blocking the radiation. It should also be noted that the invention is not limited to steam conversion of hydrocarbon fuels to produce hydrogen. The concept of heat transfer, on which the invention is based, can also be used for other endothermic, catalytic reactions. It will be apparent to those skilled in the art that the present invention may be modified and modified within the scope of the appended claims without departing from the spirit and spirit of the invention. Patent claims 1. l. Catalytic reaction apparatus, characterized by a means delimiting a burner chamber, in which fuel is burned to generate hot gases, and at least one tubular reactor with a first part extending into the burner chamber, the reactor having an outer wall and an inner wall, the inner wall being provided with a gap to the outer wall, so as to form an annular reaction chamber for a reaction catalyst, and the reaction chamber having an inlet and an outlet, the outlet being formed in the part of the reactor extending into the combustion chamber, and a wall member arranged relative to the outer wall of the reaction chamber so as to form a narrow, annular combustion gas channel extending coaxially with and beside the reaction chamber, said channel having an inlet end in gas connection to the burner chamber and an outlet end substantially at the side of the inlet end of the reaction chamber, and said combustion gas duct being assad to conduct hot gas from the burner chamber over the outer wall of the reactor in the flow through the opposite direction of the reaction chamber to conduct heat thereto, and partly a means arranged at intervals within the inner wall of the reactor so as to form a narrow annular regeneration chamber coaxially with and adjacent to the annular reaction chamber wherein the annular regeneration chamber has an inlet end and an outlet end, the inlet end of the regeneration chamber being adapted to receive all the reaction products from the outlet end of the reaction chamber and wherein the regeneration reaction means transfer appreciable heat already present in the reaction products at the outlet end of the reaction chamber back to the reaction chamber. 2. A catalytic reaction apparatus according to claim 1, characterized in that the inner wall of the reactor forms a cylindrical tube which is coaxial with the annular reaction chamber, the means inside the inner wall of the reactor being constituted by a 12 ... ~ 7v1s22e-4 spacing. plug, which is fitted in the tube and which has an outer wall surface fitted inside and at a distance from the inner wall of the reactor so that the annular regeneration chamber is delimited. Catalytic reaction apparatus according to any one of claims 1 or 2, characterized in that the space between the walls of the regeneration chamber is 0.254-2.54 cm, the space between the walls of the combustion gas channel is 0.254-7.62 cm and the space between the walls of the reaction chamber is 0.762-5 , 08 cm. Catalytic reaction apparatus according to any one of claims 1 to 3, characterized in that the reaction chamber contains a steam conversion catalyst and in that the catalytic reaction apparatus comprises means for introducing a marketable hydrocarbon fuel and steam into the inlet end of the reaction chamber and and oxidizing agents in the burner chamber. Catalytic reaction apparatus according to one of Claims 1 to 4, characterized in that the combustion gas duct is substantially filled with a heat-conducting material. Catalytic reaction apparatus according to any one of claims 1 to 5, characterized in that the space between the walls of the regeneration chamber is 0.317-127 cm, the space between the walls of the gas channel 1, 27-5.08 cm and the space between the walls of the reaction chamber is 1, 27-3.81 cm. Catalytic reaction apparatus according to one of Claims 1 to 6, characterized in that the reactor is arranged vertically inside the furnace and in that the outlet end of the reaction chamber is arranged at the upper end of the reaction chamber. Catalytic reaction apparatus according to one of Claims 1 to 7, characterized on the one hand by a furnace with a means which forms a combustion chamber for the combustion of fuel and for generating hot gases, and on the other hand by a number of tubular reactors arranged inside the furnace and comprising an inner and an outer wall, between which an annular reaction chamber is formed intended to contain a reaction catalyst, the respective reaction chamber consisting of a first part, a second part, an inlet end and an outlet end, the first part comprising the outlet end and is arranged inside the burner chamber while the second part is arranged outside the burner chamber, each reaction chamber having means connected thereto, which means form a narrow annular regeneration chamber coaxial with and beside and inside the reaction chamber separated therefrom. at a space, the regeneration chamber having an inlet end and an outlet end, where the inlet end n is adapted to receive all reaction products from the outlet end of the reaction chamber and the regeneration chamber is adapted to direct the reaction products in the opposite direction to the flow through the reaction chamber and to transfer only appreciable heat already present in the reaction products at the other end of the reaction chamber to the other end of the reaction chamber. the part of the respective reaction chambers has walls which are arranged around and at a space thereto, forming a narrow annular fuel gas channel which is coaxial with and arranged next to the reaction chambers along the entire second part and which has an inlet end in gas connection with the burner chamber and an outlet end, the combustion gas duct being adapted to conduct hot gas from the burner chamber to the outlet end of the duct in the opposite direction to the flow through the reaction chamber to supply this heat, and the furnace comprising means for preventing the hot gas in the burner chamber from t leave the same through other means than through the annular fuel gas ducts. Catalytic reaction apparatus according to claim 8, characterized in that the regeneration chamber extends substantially along the entire length of the reaction chamber. 10. l0. Catalytic reaction apparatus according to claim 8, characterized in that among the means indicated in connection with the reaction chamber, which form the regeneration chamber, there is a cylindrical plug, with an outer cylindrical surface separated from the inner wall of the reactor with a gap, whereby regeneration is formed. PUBLICATIONS MADE: