GB2201903A

GB2201903A - Apparatus and process suitable for producing hydrogen

Info

Publication number: GB2201903A
Application number: GB08704959A
Authority: GB
Inventors: Johannes Didericus De Graaf
Original assignee: SHELL INT RESEARCH; Shell Internationale Research Maatschappij BV
Current assignee: SHELL INT RESEARCH; Shell Internationale Research Maatschappij BV
Priority date: 1987-03-03
Filing date: 1987-03-03
Publication date: 1988-09-14
Anticipated expiration: 2007-03-03
Also published as: GB2201903B; DE3806536A1; KR880011009A; CA1336531C; JP2787773B2; GB8704959D0; JPS63230502A; KR960005505B1; DE3806536C2; MY103066A

Description

1 - APPARATUS AND PROCESS SUITABLE FOR PRODUCING HYDROGEN 2"' 0 1907 2 J T

5763 GBR de The invention relates to an apparatus suitable for producing hydrogen and to a process for producing a hydrogen-containing gas.

It is well known to prepare a hydrogen-containing gas such as synthesis gas (which mainly consists of hydrogen and carbon monoxide, and in addition carbon dioxide, nitrogen and (unconverted) hydrocarbons and steam) by means of endothermic steam reforming of a hydrocarbonaceous feed in an apparatus in which heat is exchanged between flue gas and product gas in order to recover heat which is required to maintain an adequate reaction temperature. However, the heat is not recovered in such an apparatus where it is needed most i.e. in the reaction section wherein a usually highly endothermic reaction is to be carried out.

It is furthermore known to make use of the heat-content of product gas emanating from a reaction zone by employing a reaction section comprising two concentrical tubes forming an annular space which contains catalyst particles and removing product gas through the central tube, thus exchanging heat directly between the hot product gas and the catalyst.

A major problem associated with the use of a reaction section comprising concentrical tubes is the degree of heat exchange which can be attained therewith, in particular when product gas with a temperature of 800 C or even 1000 C is to be cooled.

Surprisingly, it has now been found that helically wound tubes arranged inside catalyst containers provide excellent heat transfer between hot product gas removed via said tubes and surrounding catalyst particles which are further heated by convective heat exchange.

The invention therefore relates to an apparatus suitable for producing hydrogen which comprises 1 - (i) a housing containing a convection section having inlet- and outlet means for a heating medium, and (ii) a reaction section having inlet- and outlet means for process fluid, which reaction section comprises (a) catalyst container(s) extending into the convection section and comprising a plurality of helically wound open-ended tubes wherein the process fluid inlet means are in communication with the catalyst container(s) and wherein the process fluid outlet means are in communication with the upper end parts of the tubes.

The invention further relates to a process for producing a hydrogencontaining gas which comprises contacting a hydrocarbonaceous feed in the presence of steam at elevated temperature and pressure with a reforming catalyst which is heated by means of convective heat transfer and removing hydrogen-containing product gas through helically wound tubes extending in the reforming catalyst.

The apparatus and process according to the invention will be elucidated hereinafter with the use of the Figures in which various preferred embodiments have been incorporated without having the intent of limiting the invention to those particular embodiments as depicted in the Figures. Reference numerals relating to corresponding parts are the same for Figures 1-3.

Figure 1 relates to a longitudinal section of an apparatus according to the invention.

In Figure 2 a cross section is shown at AA' of the apparatus depicted in Figure 1.

Figure 3 represents a longitudinal section of an apparatus which contains Aditional heat exchange means, compared with the apparatus depicted in Figure 1.

The apparatus depicted in Figure 1 comprises a housing (1) containing a convection section (2) having inlet means (3) for a beating medium e.g. a hot liquid or gas or even particulate solids, preferably combustion gas, and outlet means (4) therefor.

The housing furthermore contains a reaction section comprising one or more catalyst containers (8) and a distribution section (5) a f' 3 - having inlet means (6) for process fluid such as a feed mixture of steam and a hydrocarbons-containing gas (preferably natural gas or methane) and outlet means (7) for process fluid such as a mixture of hydrogen- containing product gas and unconverted feed gas. 5 The catalyst containers (8) are preferably tubular shaped and enclose at least the major part of a plurality of at least partly helically wound open-ended tubes (9). Preferably, a plurality of tubular catalyst containers (8), which are suitably arranged in one (as depicted in Figure 2) or more (concentrical) circular patterns in the housing (1), extend downwardly into the convection section (2).

The distribution section (5) is preferably separated from the convection section (2) by means of a tube sheet (10) in order to avoid contamination of product gas emanating through outlet means (11) with heating gas. Moreover, by suspending the tubular catalyst containers by means of tube sheet (10) the containers can expand freely during start up of the apparatus according to the invention, without causing problems such as cracking of the tubes or tube connections which can easily occur when the tubes are connected at both ends to in- or outlets means.

In order to ensure as uniform heating of the catalyst containers as possible, the convection section preferably contains means (12) for preventing radiant heat transfer, such as the disc-shaped insulation means e.g. containing refractory material depicted in Figures 1 and 3.

Process feed gas can enter a catalyst container only through inlet opening (13) in the upper end part (14) thereof and proceeds downwardly through the particulate catalyst which is preferably used in order to be able to operate at a relatively low temperature from 400 to 1200 C at a pressure from 2 to 200 bar in the reaction section Preferably, the catalyst containers (8) are provided with catalyst support means (14) in their closed lower end parts in order to avoid entrainment of catalyst particles into the open lower end parts (15) of the two helical coil tubes which are preferably present in each catalyst container. The catalyst support means (14) may additionally serve as positioning means for said lower end parts (15) of the helical coil tubes.

During operation hot process gas centers tubes (9) through end parts (15) as depicted in Figures 1 and 3 and flows upwardly, thus ensuring optimal heat exchange with the surrounding catalyst.

Heat exchanged process gas (which still may have a temperature of e.g. 500-1000 C) enters the annular-shaped channel (16) present in the upper end part (29) of catalyst container (8) and communi- cating with a pair of helically wound tubes. The annular channels (16) are in open communication with product outlet means (7) via manifold tubes (17).

In the above-described manner the upper parts of each pair of helically wound tubes (9) are connected to a single outlet manifold (7) for process fluid arranged substantially centrally in the upper part of the housing (1). Such an arrangement is very advantageous from a constructional point of view because the use of a plurality of individual outlet means for each catalyst tube, with the associated sealing and expansion problems, can thus be avoided; moreover, the pressure in all manifold tubes (17) will be substantially equal, thus ensuring optimal distribution of process gas over all catalyst containers.

In the bottom section (18) of housing (1) one or more combustor outlet means may be present as depicted in Figures 1 and 3 which function as inlet means (3) for heating medium. In a preferred embodiment of the apparatus according to the invention a plurality (e.g. three) of combustor outlet means are (e.g. tangentially) arranged in the housing in a rotation-symmetrical manner (not depicted in the Figures) in order to ensure optimal distribution of combustion gas throughout the combustion section (2).

The combustion means depicted in Figures 1 and 3 comprise inlet means (19) for (e.g. oxygen-enriched) air, inlet means (20) for a combustible fluid (e.g. hydrocarbonaceous gas, liquid and/or coal) and, optionally, inlet means (21) for recycled gas such as n (. -I.

carbon monoxide-containing gas separated off from hydrogen- and carbon monoxide containing product gas e.g. by means of pressure swing adsorption (not shown in the Figures), or recycled flue gas.

In Figure 3 a more complex, even more heat-efficient embodiment of the apparatus according to the invention is depicted wherein the outlet manifold (7) comprises a plurality of concentrically arranged tubes forming at least one annular space (22) which is in open communication with inlet means (23) and outlet means (24) for heat exchange fluid (e.g. relatively cold expanded and/or heat-exchanged flue gas) extending outside the housing (1).

Product outlet means (7) now comprise a tubular housing (24) extending through tube sheet (10) into convection zone (2). The closed bottom end part (25) of housing (24) is connected to heat exchange fluid inlet means (23), preferably by means of expansion bellows (not shown in Figure 3). Product manifold tubes (17) are in open communication with tubular heat exchange means (26) having a closed lower end part (27) in order to reverse the downward flow of product gas during operation through the annular space (28) into the open-ended tubular product outlet means (11) which extend through manifold (17) into said tubular means (26).

With the above-described product outlet means a substantial part of the thermal energy still present in the product gas emanating from manifold tubes (17) can be recovered.

Claims

C L A I M S

T 5763 GBR Apparatus suitable for producing hydrogen which comprises (i) a housing containing a convection section having inlet- and outlet means for a heating medium, and (ii) a reaction section having inlet- and outlet means for process fluid, which reaction section comprises (a) catalyst container(s) extending into the convection section and comprising a plurality of helically wound open-ended tubes wherein the process fluid inlet means are in communication with the catalyst container(s) and wherein the process fluid outlet means are in communication with the upper end parts of the tubes.
2. Apparatus according to claim I wherein the convection section contains means for preventing radiant heat transfer to the catalyst containers.
3. Apparatus according to claim I or 2 wherein the convection- and the reaction sections are separated by a tube sheet.
4. Apparatus according to claim 3 wherein a plurality of tubular catalyst containers extend downwardly through the tube sheet into the convection section.
5. Apparatus according to any one of the preceding claims wherein the upper end parts of each pair of helically wound tubes are connected to a single outlet manifold for process fluid arranged substantially centrally in the upper part of the housing.
6. Apparatus according to claim 6 wherein the outlet manifold comprises a plurality of concentrically arranged tubes forming at least one annular space which is in communication with inlet- and outlet means for heat exchange fluid extending outside the housing.
7. Apparatus substantially as described hereinbefore with reference to the Figures.

1 c a 1 I_ -1
8. Process for producing a hydrogen-containing gas which comprises contacting a hydrocarbonaceous feed in the presence of steam at elevated temperature and pressure with a reforming catalyst which is heated by means of convective heat transfer and removing hydrogencontaining product gas through helically wound tubes extending in the reforming catalyst.

Published 1988 at The Patent Office, State House, 68171 High Holborn, London WC1R 4TP. Further copies may be obtained from The Patent 0Mce,