AU2018217864B2

AU2018217864B2 - Converter for converting SO2 into SO3

Info

Publication number: AU2018217864B2
Application number: AU2018217864A
Authority: AU
Inventors: Sayyed Ahmad FANI YAZDI; Peter NILL; Axel Schulze
Original assignee: Hugo Petersen GmbH
Current assignee: Hugo Petersen GmbH
Priority date: 2017-02-07
Filing date: 2018-02-07
Publication date: 2020-12-03
Anticipated expiration: 2038-02-07
Also published as: PE20191140A1; AU2018217864A1; BR112019015117A2; BR112019015117B1; CL2019002207A1; EP3580168A1; DE202017100630U1; EP3580168B1; RU2727602C1; ES2837581T3; WO2018146121A1; MX2019009313A

Abstract

The aim of the invention is to reduce the mechanical load of the casing and/or the central pipe of a tray of a contact kettle. To this end, a segment is provided for forming a membrane bottom for a contact kettle, particularly for the oxidation of SO

Description

CONVERTER FOR CONVERTING S02 TO S03

The invention relates to a segment for forming a membrane

bottom for a contact vessel, in particular for oxidation of

SO 2 to S03, and also relates to a membrane bottom and to a

contact vessel and to the use of such contact vessel for

the conversion of S02 to S03.

Background of the Invention

For the technical production of sulfuric acid, the so

called contact process is mainly used nowadays. In this

process, sulfur dioxide S02 is oxidized to sulfur trioxide

S03in the presence of at least one catalyst under release of heat, and in combination with water the S03 forms

sulfuric acid. The conversion of S02 to S03 takes place in

a so-called contact vessel. A contact vessel is a major

component in the sulfuric acid plant and is also referred

to as a "converter".

In a contact vessel, grates are arranged one above the

other, on which a catalyst bed is built. These grates are

also referred to as "trays" or "converter bottoms".

Strictly speaking, a complete "tray" consists of a membrane

bottom, inert random packing, catalyst, gas inlet and

outlet ports or openings, and bottom plate or separating

bottom, which ensures separation between two trays. One of

these aforementioned grates is a "membrane bottom". Cooling

zones may be arranged between the trays or membrane

bottoms. Permeability of the support surface of the

catalyst can be achieved in different ways, for example by

a pate that is provided with openings or holes (membrane) or by a grate. Thus, a tray consists of an outer boundary, the casing, and the support surface for receiving the catalyst. A tray may also have an inner boundary, in particular a central pipe. Furthermore, a tray has an opening for the supply of S02-containing gas. This opening may be located centrally, inside the tray, for example in the form of a central pipe. This opening may also be arranged in the outer boundary of the tray, for example in the form of a mouth.

The manufacture of the contact vessel is costly and

directly proportional to the weight of the contact vessel.

In prior art membrane trays, the tray plate is directly

connected to the central pipe and to the casing, to

transfer any loads and stresses to the casing and to the

central pipe. Such a tray membrane is schematically shown

in FIG. 16. In this way, the central pipe and the casing

not only have to accommodate the entire load of the tray's

contact mass from the catalyst bed and the forces resulting

from the pressure difference around the tray, but also have

to accommodate radial tensile stresses and radial forces

that are exerted on the casing and the central pipe from

the tray plate. Therefore, a so-called "proof of buckling"

must be provided for the casing and for the central pipe to

verify the structural safety of the respective

construction. Thus, a greater material thickness is used

for the casing and the central pipe in the construction of

the contact vessel, which is a drawback for such contact

vessels. The tray plate itself is made as a membrane

bottom, which hardly differs from the material thickness of

a tray plate in a contact vessel having a tray frame that is supported from below, which is the advantage of such other prior art contact vessel.

On the other hand, the contact vessels with tray frame

according to the schematic view of FIG. 17 have the

advantage of accommodating any forces from the tray

vertically and transferring them vertically to the casing

and central pipe. With vertically acting loads on the

casing and central pipe, no radial forces do arise, which

eliminates the need of a proof of buckling for the contact

vessel. Therefore, a smaller material thickness is

sufficient for the casing of the contact vessel and the

central pipe, which represents an advantage here. The

drawbacks of such a tray frame when compared to membrane

trays are additional tray weight due to the tray frame,

additional installation height of the tray by adding-up

tray frame heights and the total height of the contact

vessel resulting thereby, which contributes to a higher

total weight of the contact vessel.

A desirable outcome of the invention resulting therefrom is

to reduce the mechanical stress on the casing and/or on the

central pipe of a tray of a contact vessel. A particular

embodiment of the invention is to provide a way of avoiding

the radial forces and radial stresses without departing

from the membrane tray design on the one hand, and on the

other hand to keep the overall height of the contact vessel

as small as possible, despite retaining the design

advantages of trays frames.

(26257748_1):GCC

Inventive Solution

The invention achieves these objects in a surprisingly simple way by providing a segment for forming a membrane bottom for a contact vessel, in particular for the oxidation of SO 2 to SO 3 , which segment, seen in top view

parallel to a longitudinal axis L, has a projection surface which is a section of a circular ring about a center M, with the longitudinal axis L extending through the center M, wherein the segment has an inner edge facing the center, an outer edge opposite the inner edge seen radially from the center, and two side edges, the side edges laterally delimiting the projection surface of the segment from the inner edge to the outer edge in radial direction seen from the center.

Such a virtually loose segment according to the invention makes it possible to build a membrane bottom or a so-called "tray" in a manner so that forces acting on the membrane bottom during operation do not load the surface of the membrane bottom on which the catalyst is supported, neither circumferentially with respect to the longitudinal axis nor radially with respect to the longitudinal axis. Thus, the invention provides the possibility to reduce the mechanical load on the casing and/or on the central pipe of a tray of a contact vessel. By avoiding radial forces and stresses in the configuration of a contact vessel, it is possible to save material and thus weight and costs.

The invention furthermore provides a membrane bottom for a contact vessel, in particular for the oxidation of S02 to S03, which comprises at least two segments as described above, wherein in order to form the membrane bottom, the at least two segments are arranged adjacent to one another in a plane extending through their projection surfaces and are laterally supported on support surfaces along their radial side edges, in particular are firmly connected thereto, wherein the support surfaces are provided by a holding means which substantially has an outer shape of a T-beam or

Y-beam or cross profile beam, wherein the lateral

projections of the T-beam or Y-beam or cross profile beam

provide the support surfaces and the length of the T-beam

or Y-beam or cross profile beam corresponds to the length

of the holding means which is equal to or preferably longer

than that of the side edge of the segment.

A cross profile beam substantially has the profile of a

'plus' sign (+) seen in the direction of its major extent.

Due to the segmental design of the tray plate, the

circumferentially directed tensile stresses cancel each

other out with the tensile stresses resulting from the

adjacent segments during operation. In this way, it is

ensured in a structurally simple manner that there are

substantially no circumferential tensile stresses resulting

on the mounting means, in particular in the T-beam or

Y-beam or cross profile beam.

According to an advantageous embodiment of the invention it

is contemplated that the membrane bottom has two annular

ledges, one of which is formed so as to extend

circumferentially along the inner surface of a casing of a

contact vessel and the other one is formed so as to extend

circumferentially along the outer surface of a central body

of a contact vessel, wherein the two annular ledges lie in

the same plane, in particular seen in a direction perpendicular to the longitudinal axis, with at least one segment, preferably more than one segment, most preferably all segments bearing freely on the two annular ledges. The segments thereby define a circular ring, and the segments are attached, for example welded or screwed directly to the mounting means on their radial side, and bear freely on the annular ledges circumferentially along the casing or central body. In operation, they are covered by the catalyst mass.

In particular, one annular ledge closes the gap between the

casing and the tray segment plate, and/or the other annular

ledge closes the gap between the central body and the tray

segment plate. Thus, with the aid of the annular ledges, a

membrane bottom is created which is essentially completely closed in a direction parallel to the longitudinal axis, which permits passage of gas through the catalyst bed solely through the openings of the membrane and thus contributes to a defined flow around the catalyst particles in the bed on the membrane bottom and at the same time prevents the catalyst particles from trickling down through the annular gap.

According to a further advantageous embodiment of the invention it is contemplated that each pair of adjacent segments is arranged symmetrically to each other with respect to an axis radially to the longitudinal axis L. This makes it possible to cancel out the loads acting in the circumferential direction.

The invention moreover provides a contact vessel, in particular for oxidation of SO 2 to SO 3 , which has a substantially cylindrical shape extending about a longitudinal axis L and is delimited to the exterior by a rotationally symmetrical casing extending around the longitudinal axis and toward the center by a rotationally symmetrical central body extending around the longitudinal axis, namely a central pipe or a central rod, and the contact vessel comprises at least one membrane bottom as described above between the central body and the casing in a plane perpendicular to the longitudinal axis, wherein at least two holding means, each defining at least one mounting surface, are mounted between the central body and the casing such that stress resulting from a load on the segments in a direction perpendicular to the projection surface thereof is transferred via the mounting surface to the central body or to the casing substantially solely in a direction parallel to the longitudinal axis. In this way, the mechanical stress on the casing and/or on the central body of a contact vessel can be reduced. By avoiding radial forces and stresses in the configuration of the contact vessel, material and hence weight can be saved on the one hand, and on the other hand engineering effort and associated costs.

According to an advantageous embodiment of the invention,

it is contemplated that each segment is fastened, in

particular welded, screwed and/or anchored to one or each

adjacent T-beam or Y-beam or cross profile beam along one

or each radial side edge thereof through at least one of

the support surfaces. In this way, the stability in a

membrane bottom and hence the rigidity thereof can be

increased.

According to an advantageous embodiment of the invention,

it is contemplated that at least one holding means is integrated in the catalyst mass during the operation of the contact vessel. As will be explained in more detail below, this construction in which the T-beams and/or Y-beams and/or cross profile beams are completely integrated in the catalyst mass allows for a lower, i.e. less tall design of the contact vessel.

The invention offers different options for the constructive

design of the membrane bottom. These options can be

particularly easily implemented through the design of the

individual segments. Depending on which amount of catalyst

is to be provided on a membrane bottom and which shape and

size the catalyst particles have, each tray plate segment

may be substantially flat, for example. However, it is

likewise possible for each tray plate segment to have a

curvature.

Within the scope of the invention, the inlet and outlet

connections for the gas flowing through the contact vessel

during operation can be positioned in accordance with the

installation situation of the contact vessel on site. For

example, according to one embodiment of the invention it is

contemplated that the contact vessel comprises at least one

port for introducing gas and at least one port for

discharging gas during operation of the contact vessel,

wherein the one or more ports open into the casing of the

contact vessel in particular laterally.

However, it is also possible that the contact vessel

comprises at least one opening in the central pipe or in

the casing through which gas can be introduced during

operation of the contact vessel, and/or that the contact

vessel comprises at least one opening in the central pipe or in the casing through which gas can exit during operation of the contact vessel. Then, gas feed or gas discharge through gas inlets or gas outlets are embedded in the central pipe, and the gas flow can flow radially into the contact vessel and out of the contact vessel. This saves space on the outside of the contact vessel, since outwardly projecting ports are eliminated. This provides for a particularly compact design.

In the context of the invention, the contact vessel may in

particular consist of solely a single membrane bottom with

casing and central body. Through the number of membrane

bottoms, the contact vessel can be flexibly adapted to the

respective task in the application. For this purpose, it is

contemplated that the contact vessel comprises at least one

membrane bottom, in particular at least two membrane

bottoms, and in particular consists of one to six membrane

bottoms which are arranged vertically one above the other.

According to a preferred embodiment it is contemplated that

the contact vessel has four or five membrane bottoms and is

in particular intended for use in the conversion of SO 2 to

SO 3 according to the double contact process, or that the

contact vessel has two to four membrane bottoms and in

particular intended for use in the conversion of SO 2 to SO 3 according to the single contact process.

The single contact process is also referred to as a contact

process. The double contact process for the production of

sulfuric acid is a refinement of the single contact

process, in which the S03, after having passed through a

plurality of membrane bottoms, is partially or even

completely removed, and the remaining S02 is supplied to the next membrane bottom, where the further conversion to

SO 3 takes place.

In the context of the invention, the contact vessel is

advantageously designed for use in a temperature range

between ambient temperature and 650 0C and thus also allows

to use catalysts with a high efficiency range above 600 °C,

such as vanadium pentoxide.

The invention thus also relates to the use of a contact

vessel according to any of claims 5 to 13 for the

conversion of SO 2 to SO 3 . Here, the temperatures are in

particular in the range between ambient temperature and 500

0C during the heating phase and between 350 0C to 650 °C

during operation.

The invention will now be explained in more detail by way

of exemplary embodiments and with reference to the

accompanying drawings wherein the same and similar

components are designated by the same reference numerals,

and wherein the features of the different exemplary

embodiments can be combined. In the drawings:

FIG. 1 is a schematic three-dimensional view of a first

embodiment of the invention of the tray with radially

symmetrical membrane segment plates;

FIG. 2 is a schematic bird's eye view of a tray

according to the invention in the membrane segment

plate design;

FIG. 3 is a schematic view illustrating how a tray

segment plate is supported on the ledges provided on

the casing and on the central pipe;

FIG. 4 is a schematic side elevational view of the

converter without the casing;

FIG. 5 is a schematic perspective view illustrating the

connection of the ledges to the casing and a carrier

bottom of a segment of the membrane bottom freely

bearing thereon;

FIG. 6 is a schematic perspective view illustrating the

connection between the carrier bottom of a segment of

the membrane bottom, a T-beam, and the connection

between the T-beam and the casing as well as the

connection of the ledges on the central body and a

carrier bottom of a segment of the membrane bottom

freely bearing thereon;

FIG. 7 is a schematic perspective view illustrating the

connection between the T-beam and the carrier bottom

of two segments of the membrane bottom;

FIG. 8 is a schematic perspective view illustrating a

segment carrier bottom having a bulging carrier

bottom and the T-beam;

FIG. 9 is a schematic perspective view of an alternative

embodiment of a segment carrier bottom together with

a Y-beam;

FIG. 10 is a schematic perspective view of a tray with

gas inlet through radial openings in the central pipe

and gas outlet on the casing;

FIG. 11 is a schematic perspective view of another

embodiment of a tray with gas inlet in the casing and

gas outlet through openings in the central pipe;

FIG. 12 is a schematic perspective view of a further

embodiment of a tray with gas inlet and outlet on the

casing with rounded mouths;

FIG. 13 is a schematic view illustrating the cancellation

of circumferentially directed forces and tensile stresses due to the radially symmetrical configuration according to the invention;

FIG. 14 is a schematic exemplary view of a first

embodiment of a contact vessel comprising four trays;

FIG. 15 is a schematic exemplary view of a further

embodiment of a contact vessel comprising four trays

and an integrated gas-gas heat exchanger within the

central pipe;

FIG. 16 is a schematic perspective view of a prior art

tray membrane;

FIG. 17 is a schematic exemplary view of a section of a

prior art tray frame and tray bottom bearing thereon;

FIG. 18 is a schematic exemplary view of a segment of a

prior art tray frame;

FIG. 19 is a schematic view of an embodiment of the

holding means according to the invention in the form

of a T-beam; and

FIG. 20 shows two schematic views of embodiments of the

connection between cross profile beams and segments

of the membrane bottom.

Embodiments of the segment 1 according to the invention for

a membrane bottom 2 will be illustrated with reference to

FIGS. 8 and 9. The structure of a membrane bottom 2

according to the invention will be described below with

reference to FIGS. 1 to 7 and 10 to 13. Such membrane

bottom is sometimes also referred to as a "tray". A contact

vessel 6 is in particular formed by stacking a plurality of

such trays 2 on top of each other. Examples of contact

vessels 6 will be described below with reference to FIGS.

14 and 15. Figures 10 to 12 illustrate membrane bottoms 2

or trays which have openings 63, 64 for gas inlet or gas

outlet during operation of a contact vessel 6 comprising at least one such tray 2. Such openings may also be referred to as "mouths".

Each of FIGS. 8 and 9 schematically illustrates a segment 1

for forming a membrane bottom 2 for a contact vessel 6, in

particular for the oxidation of SO 2 to S03. Seen in a plan

view parallel to a longitudinal axis L (see FIG. 1, for

example), the segment 1 has a projection surface which is a

section of a circular ring about a center M (see FIG. 2,

for example), with the longitudinal axis L extending

through the center M. Segment 1 has an inner edge 12 facing

the center M, an outer edge 13 opposite the inner edge 12

seen radially from the center, and two side edges 14,

wherein the side edges 14 laterally delimit the projection

surface of the segment from the inner edge 12 to the outer

edge 13 in radial direction seen from the center.

The figures furthermore show a membrane bottom 2 for a

contact vessel 6, in particular for the oxidation of SO 2 to SO 3 , which comprises at least two of such segments 1 (see

FIG. 2, for example). To form the membrane bottom 2, the at

least two segments 1 are arranged adjacent to each other in

a plane through their projection surfaces and are laterally

supported on support surfaces 31 along their radial side

edges 14, in particular without being firmly connected

thereto. The support surfaces 31 are provided by a holding

means 3. The holding means 3 substantially has the outer

shape of a T-beam or Y-beam, as shown in FIG. 8 and FIG. 9,

and the lateral projections of the T-beam or Y-beam provide

the support surfaces 31 and the length of the T-beam or Y

beam corresponds to the length of the holding means 3 which

is equal to or preferably longer than that of the side edge

14 of the segment 1.

A contact vessel 6, in particular for the oxidation of SO 2

to S03, can be assembled using such a membrane bottom 2

with at least two segments 1 as described above. FIGS. 14

and 15 illustrate exemplary embodiments of such a contact

vessel 6. The contact vessel 6 has a substantially

cylindrical shape extending about a longitudinal axis L and

is delimited to the exterior by a rotationally symmetrical

casing 4 extending around the longitudinal axis, and toward

the center by a rotationally symmetrical central body 5

extending around the longitudinal axis, namely a central

pipe or a central rod. The contact vessel 6 has at least

one membrane bottom 2 as described above between the

central body 5 and the casing 4 in a plane perpendicular to

the longitudinal axis L. At least two holding means 3, each

defining at least one mounting surface 32 (see FIG. 6), are

fastened between the central body 5 and the casing 4 such

that any force and stress resulting from a load on the

segments 1 in a direction perpendicular to the projection

surface thereof is transferred via the mounting surface 32

to the central body 5 or to the casing 4 substantially

solely in a direction parallel to the longitudinal axis L.

The mounting surfaces 32 visible in FIG. 6 in contact with

the casing 4 are welding seams for connecting the mounting

means 3 to the casing. The mounting means 3 may similarly

be connected to the central body 5.

In order to prevent the radial forces and stresses from

being introduced into the casing 4 and the central pipe 5

of the contact vessel 6, the novel tray plate 2 according

to the invention consists of radially symmetrical membrane

segments 1. Each segment plate 1 is fastened only on the two radial sides 14 of the segment 1, on two supports 31 which are connected to two T-beams 3 (see FIG. 19). The flange width F of the T-beam 3 lies horizontally, below the profile height P of the T-beam 3 which extends vertically upward, while the span S of the T-beam 3 extends in the radial direction and is connected with the casing 4 and the central pipe 5. In this way, a kind of balcony is created on both sides of a T-beam so to speak, on which a radial side 14 of the tray plate segment 1 is bearing and is connected thereto (see FIGS. 8 and 9, also in conjunction with FIG. 7).

In this way, all loads and stresses and the forces

resulting from the pressure difference of the tray are

introduced into the casing 4 and the central body 5 solely

via the T-beam contact points. This cancellation of forces

in the circumferential direction according to the

invention, seen with respect to the longitudinal axis L,

and the associated introduction of forces into the casing

and the central body is likewise achieved in the context of

the invention, if Y-beam or cross profile beams are used as

a mounting means 3. For example, FIG. 20 shows two

embodiments of cross profile beams. According to FIG. 20A,

the cross profile beam 3 has a "+" profile (plus symbol)

seen in the direction of its main extent. According to FIG.

20B, the mounting surfaces 31 of a cross profile beam may

also enclose an angle smaller than 90° with the vertical

ridge extending parallel to the longitudinal axis L,

comparable to a Y carrier in relation to a T-beam.

FIG. 2 shows a plan view of a membrane bottom 2 according

to the invention, which is arranged between casing 4

(outside) and central pipe 5 (inside). The casing and the central pipe can be seen in cross section. The longitudinal axis L extends through the center M of the casing and of the central pipe. Holding means 3 in the form of T-beams are fastened on the casing 4 and on the central pipe 5. In the plan view, they can be seen spanning from the casing to the central pipe. Membrane segments 1 (dotted) are bearing on the supports 31 defined by the projections of the respective holding means in the form of "balconies". In the radial direction, as seen from the longitudinal axis L, the membrane segments 1 do not extend over the entire space between the casing 4 and the central pipe 5, so that a respective gap remains between the membrane segment 1 and the casing 4 as well as between the membrane segment 1 and the central pipe 5. In order to prevent the catalyst from falling through this gap during operation, a circumferential ledge 24, 25 is attached to the outer surface of and around the central pipe and to the inner surface of and along the casing.

In a longitudinal sectional view through a region left of

the longitudinal axis L, as shown in FIG. 3, these ledges

24, 25 can be seen at the left and at the right in the form

of projections from the casing 4 (left) and from the

central pipe 5 (right). Segment 1 together with the ledges

24, 25 forms gas-permeable gaps which, however, prevent

particles of a catalyst bed supported on the membrane

bottom 2 from falling through. The same ledges can also be

seen in FIG. 5 and FIG. 6.

Each holding means 3 in the form of the T-beam is connected

to the membrane segments by a joint along the span

extending between a side edge 14 of an adjacent membrane

segment 1 and the side of the profile height of the holding means 3 facing this segment (see FIG. 6). The membrane segments 1 are not connected to the casing 4. The membrane segments 1 are not connected to the central pipe 5 either.

The holding means 3 in the form of the T-beams are

connected along the height of the profile, on one side to

the casing 4 (see FIG. 6 left side, joints in the

longitudinal direction, shown in solid black) and on the

opposite side to the central pipe 5 (not visible in FIG.

6). Substantially all of the load is transferred to the

casing 4 and to the central pipe 5 via these joints in the

vertical direction, that is in parallel to the longitudinal

axis. The joint beyond the span, which can be seen in FIG.

6 in the upper left of FIG. 6 as a short section of the

joint extending from the top of the profile height of the

T-beam facing the viewer to the (non-visible) rear side

thereof is negligible here in comparison to the dimensions

of the vertical joint area in view of the possible

remaining transfer of stresses in the circumferential

direction.

The profile height of the T-beam is chosen such that the

maximum bending of the T-beam is smaller than a detectable

bulge of the casing and of the central pipe. Thus, radial

forces and stresses introduced into the casing and into the

central body are negligible (neutral in radial forces).

By simultaneously integrating the profile height of the

mounting means such as the T-beam in the catalyst mass that

is then provided on the membrane bottom during the

operation of the invention, the height of the tray and thus

the overall height of the contact vessel is reduced.

According to the invention, at least one mounting means 3

and preferably all mounting means 3 are located on the same side of the membrane bottom on which the catalyst bed is located during operation. In the figures, this is the "upper" side of the membrane bottom 2. By having no mounting means located on the opposite side of the membrane bottom 2, i.e. the "lower" side in the figures, as according to the invention, the corresponding height of such a mounting means on the other side can be eliminated with the invention. This becomes clear in comparison with the prior art arrangement shown in FIG. 17. The support elements for the tray plate are mounted below the tray plate, and the catalyst bed is provided on top of the tray plate. Both the height of the catalyst bed and the height of the support elements add up to the overall height in this case.

What is achieved with the centrally symmetrical design of

the tray plate 2 is that any weights, loads and the

resulting forces from the pressure difference of the tray

are transferred to the T-beams 3 as circumferentially

directed forces. These forces cancel out each other, as

illustrated in FIG. 13 (circumferential forces are

neutral). Thus, the mechanical functions of the contact

vessel are individually redefined.

• Casing and central pipe only have the function to carry

weight and vertical forces.

• The height of the profile of the T-beam provides for a

bend-free tray and for transfer of all weight loads,

stresses and loads resulting from the pressure

difference of the tray to the casing and to the central

pipe of the contact vessel.

• The width of the flange of the T-beam serves as

connection between tray plate segment and T-beam.

• The tray plate segment serves as a membrane bottom with

elastic, low plastic or large plastic deformation for

carrying the load resulting from the contact mass and

the pressure difference of the tray.

In this way, all advantages of a tray with tray membrane

and of a tray with tray frame and tray plate are being

retained without having to accept the drawbacks thereof.

FIGS. 1 as well as 10 to 12 show embodiments of the

invention which allow for introducing gas and discharging

gas during operation of the membrane bottom 2 with a

catalyst bed through which gas flows. In this case, the

membrane bottom 2 carries the catalyst bed. In the

embodiment shown in FIG. 1, the casing 4 has an opening 63

through which gas enters the tray during operation. In the

view, the opening 63 is located above the membrane bottom

2. A further opening 64 in the casing 4 is provided below

the membrane bottom 2, through which the gas exits from the

tray after having passed through the catalyst bed and

through the membrane bottom 2.

The shape of openings 63, 64 may be adapted to the

downstream components such as pipes, and/or may be designed

with regard to the flow behavior. Besides the rectangular

shape shown in FIGS. 1 and 10 to 11, the openings may in

particular have a rounded shape, as in the embodiment shown

in FIG. 12.

The flow direction could also be reversed within the

context of the invention, with the opening 64 as a gas inlet and the opening 63 as a gas outlet. This also applies to the embodiments according to the views of FIGS. 10 to

12.

In the embodiments illustrated in FIGS. 10 and 11, the

central pipe 5 has a plurality of openings 63 distributed

around the circumference thereof. For the sake of clarity,

only one of them has been designated by a reference

numeral. During operation, gas can be introduced from the

central pipe into the tray through these openings 63. The

gas exits through the opening 64 in the casing 4.

FIGS. 14 and 15 illustrate embodiments of contact vessels 6

which are constructed from 4 trays in each case. The trays

are shown schematically in hatching and are numbered by encircled numbers in the figures. The arrows illustrate the gas flow during operation of the contact vessel.

In the embodiment illustrated in FIG. 14, during operation, gas flows into the central pipe 5 from above and is directed through openings 63 into the first tray. After the gas has passed through the catalyst bed and through the membrane bottom 2, it flows out of the contact vessel 6 via an opening 64 in the casing 4. Through a further opening 63 in the casing 4 (left side in FIG. 14 between the first and second trays), gas is introduced into the contact vessel 6 above the second tray. After the gas has passed through the catalyst bed and through the membrane bottom 2, it flows out of the contact vessel 6 via an opening 64 in the casing 4. Through a further opening 63 in the casing 4 (right side in FIG. 14 between the second and third trays), gas is introduced into the contact vessel 6 above the third tray. After the gas has passed through the catalyst bed and through the membrane bottom 2, it flows out of the contact vessel 6 via an opening 64 in the casing 4. Through a further opening 63 in the casing 4 (right side in FIG. 14 above the fourth tray), gas is introduced into the contact vessel 6 above the fourth tray. After the gas has passed through the catalyst bed and through the membrane bottom 2, it flows out of the contact vessel 6 via an opening 64 in the casing 4 (left side in FIG. 14 below the fourth tray).

This principle also applies to the embodiment shown in FIG.

15 of the contact vessel, for the third and fourth trays.

In this embodiment, the first tray seen in the direction of

flow of the incoming gas into the contact vessel 6 in

operation is the second tray from above in the view of FIG.

15. The gas enters the central pipe 5 of the contact vessel

6 from above and is directed around the tubes of an

integrated shell and tube heat exchanger. The central pipe

5 defines the shell of the shell and tube heat exchanger in

this area. The gas enters the first tray through openings

63 in the circumference of the central pipe 5, flows

through the catalyst bed provided on the membrane bottom 2

and leaves the first tray to re-enter the central pipe

through openings 64 in the circumference of the central

pipe 5, which are located substantially centrally of the

overall height thereof. The gas then flows upwards in the

central pipe 5 and passes through the tubes of the shell

and tube heat exchanger. In the head space of the contact

vessel 6, after exiting the tubes of the shell and tube

heat exchanger, the gas is directed out through openings 64

and is passed through the catalyst bed of the second tray.

Such use of a heat exchanger brings several advantages for

the operation of the system. Since the heat exchanger in the converter keeps the temperature, i.e. remains warm even during short downtimes of the system, the heating phases can be shortened, and the system can go directly back into operation after a brief downtime. Moreover, with the increased temperature due to the aid of the heat exchanger there will be no or less corrosion caused by condensation compared to the operation without heat exchanger. Due to the integrated arrangement of the heat exchanger in the converter, it furthermore requires no insulation. The central pipe of the converter serves as the shell of the heat exchanger. Compared to a separate arrangement of converter and heat exchanger in series, the additionally required pipelines from the converter to the heat exchanger and back are also eliminated. In addition, with the arrangement of the heat exchanger integrated in the converter, the casing of the converter remains unaffected, resulting in a mechanical stability of the converter, since fewer "holes" are required in the casing of the converter for gas inlets and outlets.

The second tray is the uppermost one in the embodiment of

the contact vessel 6 shown in FIG. 15. After the gas has

passed through the catalyst bed and the membrane bottom 2,

it flows out of the contact vessel 6 via an opening in the

casing 4. In the illustrated embodiment, this opening opens

into a port 62.

Via a port 61, the gas is introduced into the contact

vessel 6 through a further opening in the casing above the

third tray (right side in FIG. 15 between the first and

third trays). After the gas has passed through the catalyst

bed and through the membrane bottom 2, it flows out of the

contact vessel 6 through a port 62. Through a further opening in the casing 4, gas is introduced into the contact vessel 6 above the fourth tray (right side in FIG. 15 above the fourth tray). After the gas has passed through the catalyst bed and through the membrane bottom 2, it flows out of the contact vessel 6 via an opening in the casing 4 and through a port 62 (left side in FIG. 15 below the fourth tray).

Preferred application fields:

Sulfuric acid plants are a major application area for the

present invention.

Exemplary fields of application include the use:

• for conversion of SO 2 to SO 3 for the production of the

sulfuric acid after sulfur combustion;

• for conversion of SO 2 to SO 3 for the production of the

sulfuric acid in metallurgical plants after roasting;

• for conversion of SO 2 to SO 3 for the production of the

sulfuric acid for reducing the SO 2 gas in exhaust gas

cleaning systems.

It will be apparent to those skilled in the art that the

invention is not limited to the examples described above,

but can rather be varied in multiple ways. The features of

the individually illustrated examples can in particular

also be combined or exchanged for each other.

List of Reference Numerals:

1 Segment

12 Inner edge of segment

13 Outer edge of segment

14 Side edges of segment

15 Curvature

2 Membrane bottom, tray, tray segment plate

24, 25 Annular ledge

3 Holding means, T-beam, Y-beam

31 Support surface, lateral projection of T-beam or Y

beam

32 Fastening area

4 Casing

5 Central body, central pipe, central rod

6 Contact vessel

61 Gas inlet port

62 Gas outlet port

63 Opening in the central pipe or in the casing, through

which gas can be introduced during operation of the

contact vessel, "mouth"

64 Opening in the central pipe or in the casing, through

which gas can exit during operation of the contact

vessel, "mouth"

F Flange width of T-beam

P Profile height of T-beam

S Span of T-beam

L Longitudinal axis

M Center

In the present specification and claims, the term 'comprising' and its derivatives including 'comprises' and 'comprise' is used to indicate the presence of the stated

integers but does not preclude the presence of other

unspecified integers.

The reference to any prior art in this specification is not

and, should not be taken as an acknowledgement or any form

of suggestion that the prior art forms part of the common

general knowledge.

According to a first aspect of the invention there is

provided a membrane bottom for a contact vessel, which

comprises at least two segments, wherein, each segment,

seen in top view parallel to a longitudinal axis L, has a

projection surface which is a section of a circular ring

about a center M, with the longitudinal axis L extending

through the center M; and wherein each segment has an inner

edge facing the center, an outer edge opposite the inner

edge seen radially from the center, and two side edges, the

side edges laterally delimiting the projection surface of

the segment from the inner edge to the outer edge in radial

direction seen from the center; wherein in order to form

the membrane bottom, the at least two segments are arranged

adjacent to one another in a plane extending through their

projection surfaces and are laterally supported on support

surfaces along their radial side edges, while being firmly

connected thereto, wherein the support surfaces are

provided by a holding means which substantially has an

outer shape of a T-beam or Y-beam or cross profile beam,

wherein the lateral projections of the T-beam or Y-beam or

cross profile beam provide the support surfaces and the

length of the T-beam or Y-beam or cross profile beam

(26257748_1):GCC corresponds to the length of the holding means which is equal to or longer than that of the side edge of the segment.

According to a second aspect of the invention there is

provided a contact vessel, which has a substantially

cylindrical shape extending about a longitudinal axis L and

which is delimited to the exterior by a rotationally

symmetrical casing extending about the longitudinal axis

and toward the center by a rotationally symmetrical central

body extending about the longitudinal axis, namely a

central pipe or a central rod; wherein the contact vessel

comprises at least one membrane bottom according to the

first aspect between the central body and the casing in a

plane perpendicular to the longitudinal axis; wherein at

least two holding means, each defining at least one

mounting surface, are fastened between the central body and

the casing such that stress resulting from a load on the

segments in a direction perpendicular to the projection

surface thereof is transferred via the mounting surface to

the central body or to the casing substantially solely in a

direction parallel to the longitudinal axis.

(26257748_1):GCC

Claims

Claims:

1. A membrane bottom for a contact vessel, in particular for oxidation of SO 2 to SO 3 , which comprises at least

two segments, wherein, each segment, seen in top view parallel to a longitudinal axis L, has a projection surface which is a section of a circular ring about a center M, with the longitudinal axis L extending through the center M; and wherein each segment has an inner edge facing the center, an outer edge opposite the inner edge seen radially from the center, and two side edges, the side edges laterally delimiting the projection surface of the segment from the inner edge to the outer edge in radial direction seen from the center; wherein in order to form the membrane bottom, the at least two segments are arranged adjacent to one another in a plane extending through their projection surfaces and are laterally supported on support surfaces along their radial side edges, while being firmly connected thereto, wherein the support surfaces are provided by a holding means which substantially has an outer shape of a T-beam or Y-beam or cross profile beam, wherein the lateral projections of the T-beam or Y-beam or cross profile beam provide the support surfaces and the length of the T-beam or Y beam or cross profile beam corresponds to the length of the holding means which is equal to or longer than that of the side edge of the segment.

2. The membrane bottom according to claim 1, wherein at least one segment is substantially flat and

(26257748_1):GCC extends substantially in a plane perpendicular to the longitudinal axis; and/or in that at least one segment has a curvature which bulges from a plane lying perpendicular to the longitudinal axis, seen in a direction along the longitudinal axis, from the side edges resting on the support surfaces towards the support surfaces.

3. The membrane bottom according to claim 1 or 2,

wherein the membrane bottom has two annular ledges,

one of which is formed so as to extend

circumferentially along the inner surface of a casing

of a contact vessel and the other one is formed so as

to extend circumferentially along the outer surface of

a central body of a contact vessel;

wherein the two annular ledges lie in the same

plane, in particular seen in a direction perpendicular

to the longitudinal axis;

wherein at least one segment is bearing freely on

the two annular ledges.

4. The membrane bottom according to claim 1 or 2, wherein

more than one segment is bearing freely on the two

annular ledges.

5. The membrane bottom according to claim 1 or 2, wherein

all segments are bearing freely on the two annular

ledges.

6. The membrane bottom according to any one of the

preceding claims, wherein each pair of adjacent

segments is arranged symmetrically to each other with

LI

respect to an axis radially to the longitudinal axis

L.

7. A contact vessel, in particular for oxidation of SO 2

to SO 3 , which has a substantially cylindrical shape

extending about a longitudinal axis L and which is

delimited to the exterior by a rotationally

symmetrical casing extending about the longitudinal

axis and toward the center by a rotationally

symmetrical central body extending about the

longitudinal axis, namely a central pipe or a central

rod; wherein the contact vessel comprises at least one

membrane bottom according to any one of claims 1 to 6 between the central body and the casing in a plane perpendicular to the longitudinal axis; wherein at least two holding means, each defining at least one mounting surface, are fastened between the central body and the casing such that stress resulting from a load on the segments in a direction perpendicular to the projection surface thereof is transferred via the mounting surface to the central body or to the casing substantially solely in a direction parallel to the longitudinal axis.

8. The contact vessel according to claim 7, wherein each segment is fastened, in particular welded, screwed and/or anchored to one or each adjacent T-beam or Y-beam or cross profile beam along one or each radial side edge thereof through at least one of the support surfaces.

9. The contact vessel according to claim 7 or 8, fU wherein at least one holding means is integrated within the catalyst mass during operation of the contact vessel, the catalyst mass being provided on the membrane bottom in the form of a catalyst bed during operation.

10. The contact vessel according to any one of claims 7 to

9, wherein each tray segment plate is substantially flat.

11. The contact vessel according to any one of claims 7 to

9, wherein each tray segment plate has a curvature.

12. The contact vessel according to any one of claims 7to

11, wherein the contact vessel comprises at least one

port for laterally introducing gas and at least one

port for discharging gas during operation of the

contact vessel, the one or more ports opening in

particular laterally into the casing of the contact

vessel.

13. The contact vessel according to any one of claims 7 to

12,

wherein the contact vessel comprises at least one opening

in the central pipe or in the casing, through which

gas can be introduced during operation of the contact

vessel; and/or in that

the contact vessel comprises at least one opening

in the central pipe or in the casing, through which

gas can be discharged during operation of the contact

vessel.

14. The contact vessel according to any one of claims 7 to

13,

wherein the contact vessel comprises at least one membrane

bottom.

15. The contact vessel according to claim 14, wherein the

contact vessel comprises at least two membrane

bottoms, which are arranged vertically one above the

other.

16. The contact vessel according to claim 14 or 15,

wherein the contact vessel consists of one to six

trays with membrane bottoms, which are arranged

vertically one above the other.

17. The contact vessel according to any one of claims 14

to 16,

wherein the contact vessel comprises four to five trays

with membrane bottoms and is in particular intended

for use in the conversion of SO 2 to SO 3 according to a

double contact process; or in that

the contact vessel comprises two to five trays

with membrane bottoms and is in particular intended

for use in the conversion of SO 2 to SO 3 according to a

single contact process.

18. The contact vessel according to any one of claims 7 to

17, wherein

the contact vessel is designed for use in a temperature

range between ambient temperature and 650 0C.

19. Use of a contact vessel according to any one of claims

7 to 18 for oxidation of S02 to SO 3 .

QJv

20. Use according to claim 19,wherein temperatures are in a range between ambient temperature and 500 0C during the heating phase and between 350 0C and 650 0C during operation.

Hugo Petersen GmbH

Patent Attorneys for the Applicant/Nominated Person

SPRUSON&FERGUSON