Imperial Chemical Industries Limited

Warwick J Lywood

Peter J Davidson

Martin Fowles

Peter J Carnell

Martyn V Twigg

David G Shipley

Jeremy C Hunns

A process for the production of a hydrogen containing gas stream comprises partially reforming a feed stream containing hydrocarbon feedstock to be reformed together with a steam and/or carbon dioxide as reforming gas by passage of said feed stream over a steam reforming catalyst disposed in heated auxiliary tubes, thereby forming a partially reformed gas stream; subjecting the partially reformed gas stream, optionally together with a further quantity of said feedstock and/or reforming gas, to further reforming by passage over a steam reforming catalyst disposed in furnace reformer tubes heated by combustion of a fuel, thereby forming a reformed product gas stream; and passing the reformed product gas stream past the exterior of the auxiliary tubes, thereby supplying heat to said auxiliary tubes and cooling the reformed product gas stream.

Steam reforming

A combustion process, e.g. for a gas turbine, comprises catalytically combusting part of a fuel/air feed in a preliminary catalyst body which has through passages and supports, or is composed of, a catalyst active for the combustion of the fuel. The resultant heated gas stream is then mixed with the remainder of the feed, and that mixture is combusted, e.g. catalytically in a main catalyst body. The amount of combustion occurring in the preliminary catalyst body is sufficient that combustion of the mixture of the heated gas stream and the remainder of the feed can be sustained at the desired operating conditions. Under those desired operating conditions combustion of the feed could not be sustained in the absence of the heating given by the combustion in the preliminary catalyst body. There may be more than one preliminary catalyst body. The preliminary catalyst body or bodies may also be provided with passages wherein combustion does not take place under the desired operating conditions so that those passages act as a bypass. Preferably the combustion passages of at least the first preliminary catalyst body are of such size, that at the normal operating conditions, the flow therethrough is laminar, whereas the flow through the passages of the main catalyst body, where employed, is turbulent.

Catalytic combustion process

At least during some part-load operation of a gas turbine wherein a fuel gas is combusted with air with the formation of a flame and the combustion products are let down through a turbine, the fuel gas comprises the product of a stage of catalytic autothermal steam reforming of a light hydrocarbon feedstock gas and the amount of air fed to the gas turbine combuster, relative to the amount of hydrocarbon fed to the catalytic autothermal steam reforming stage, is greater than the maximum amount of air that enables a flame to be sustained in said combustor if that amount of hydrocarbon were to be fed directly to the combustor.

Method of operating gas turbines with reformed fuel

A gas stream containing hydrogen, carbon monoxide, and steam, and having a steam to dry gas molar ratio below 0.5 and a steam to carbon monoxide molar ratio above 0.5, and that has been formed at a temperature above 700.degree. C., is passed, at a temperature within the range 550.degree. to 650.degree. C., over an iron-free catalyst effective at such temperatures to catalyze the shift reaction. This effects some shift reaction thus increasing the amount of high grade heat that can be recovered from the gas. Also the hydrogen content of the gas is increased and the carbon monoxide to carbon dioxide ratio of the gas is decreased, thus decreasing the risk of hydrocarbon formation if the gas is subsequently subjected to a further shift reaction using an iron-oxide containing catalyst. Suitable catalysts comprise palladium and/or an oxide of an alkali, or alkaline earth, metal on a refractory support.

Hydrogen production

A process for the production of a hydrogen containing gas stream comprises catalytic steam reforming of a major hydrocarbon/steam stream in tubes heated by means of a fired furnace and catalytic steam reforming of a minor hydrocarbon/steam stream in auxiliary tubes heated by the reformed major stream, and mixing the reformed minor stream with the reformed major stream.

A mixture (34) of a hydrocarbon feedstock with steam and/or carbon dioxide is preheated and adiabatically steam reformed giving a partially reformed gas (26) which is then, optionally after reheating, further steam reformed inannular catalyst regions (32) of a double tube reformer (14). The outer tubes (28) of the double tube reformer are heated by a hot gas stream (12), e.g. in a fired furnace or by the hot gas stream produced by subjecting the reformed gas withdrawn from the inner tubes (30) of the double tube reformer to secondary reforming. The preheating (18), and the reheating (20), if any, is effected by indirect heat exchange with a hot gas after the latter has heated the outer tubes of the double tube reformer and/or with the reformed gas.

Production of hydrogen-containing gas streams

A single pressure process for the production of methanol wherein the make-gas is produced by steam reforming a hydrocarbon feedstock, in admixture with recycled purge gas from the synthesis loop, at such a pressure that the make-gas can be fed without further compression, to the synthesis loop at a pressure no lower than the pressure at the inlet to said circulator. The reforming is effected by primary steam reforming followed by partial oxidation with oxygen and secondary reforming, without any bypass of the feedstock of the primary reforming stage, so as to give a make-gas of approximately stoichiometric composition for methanol synthesis. The primary reforming is effected at above 55 bar abs. over a catalyst disposed in tubes heated by passing the secondary reformed gas stream past the external surfaces of the reformer tubes in a direction counter-current to the flow of reactants undergoing primary reforming in said reformer tubes. In this way heat is transferred from said secondary reformed gas stream through the walls of said tubes to supply the endothermic heat of the steam reforming reaction. In preferred forms of the process the steam is incorporated into the feed to the reformer by saturation and the excess of steam is removed from the reformed gas by direct contact with cold water: in this way a high pressure steam system recovering power from the reformed gas is not needed.

Methanol

Desulphurization of a feedstock using a regenerable sorbent to give a desulphurized stream, regeneration of the sorbent by heating, feedstock, and during at least the initial part of the cooling, at least part of the effluent from the sorbent is contacted with a non-regenerable particulate sorbent. The desired desulphurized product comprises the effluent from the regenerable sorbent that has bypassed the particulate sorbent. Preferably the heat for regeneration is obtained by heat exchange with the products of combustion of the sulphur laden regeneration fluid. In an alternative process using a particulate sorbent for a 'polishing' operation, the regenerable sorbent is replaced by a membrane separation unit giving a desulphurized stream and a sulphur laden stream, which is combusted to heat, by heat exchange, the desulphurized stream before it passes through the particulate sorbent.

Desulphurization

A heat and mass exchange, pressure and/or thermal swing adsorption process using an adsorbent bed which consists of at least one unit having substantially parallel passages through it. Each unit has at least 20 passages per cm.sup.2 of its cross-sectional area, the number and cross-sectional area of the passages being such that each unit has a geometric void of not more than 0.45. The bed may be random packed or a close packed assembly or stack of units.

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Yarm, United Kingdom

Warwick J Lywood