The present invention relates to a heat exchange reactor for carrying out endothermic or exothermic catalytic reactions. In particular, the present invention relates to a heat exchange reactor with improved fluid sealing for high temperature reactions. The heat exchange reactor may be part of a large apparatus, such as a production apparatus.

Catalytic reactors for carrying out endothermic or exothermic reactions are well known in the art, particular examples being reactors for the endothermic steam reforming of hydrocarbons and reactors for the exothermic methanol synthesis reactions (not limiting the scope of the invention to these reactions). The reactions are typically carried out in tubes loaded with a suitable solid catalyst through which a process gas stream comprising the reactants is passed at elevated pressure. A plurality of tubes is arranged vertically or horizontally in the reactor. The tubes run in parallel along the major axis of the catalytic reactor, while a heat-exchanging medium outside the tubes heats or cools the tubes. The solid catalyst inside the tubes provides a catalyst bed in which the required chemical reactions take place. The catalyst can be provided as solid particles or as a coated structure, for example as a thin layer fixed on the inner wall of the tubes in steam reforming reactors.

In another reactor configuration comprising a plurality of tubes the solid catalyst particles may be disposed outside said tubes, hereinafter also referred to as heat transfer tubes, whilst the heat exchanging medium passes inside. The solid catalyst outside the heat transfer tubes provides the catalyst bed in which the required chemical reactions take place.

Further types of heat transfer tubes and heat exchange reactors are known in the art. In the following, the invention is explained with reference to heat exchange reactors and heat transfer tubes with the catalysts arranged inside the tubes and where the tubes and reactor is arranged substantially vertically. However the scope of the invention is not limited to these type of tubes and reactors. The terms "catalytic reactor", "heat exchange reactor" and "reactor" are used interchangeably. By "catalyst bed" is meant the volume of solid catalyst forming said bed and which is inside the heat transfer tubes. The terms "heat transfer tubes" and "tubes" are used interchangeably and cover the tubes which are in contact with catalyst as well as a heat exchanging medium for the purpose of carrying out catalytic reactions. A process and reactor in which a catalyst is in indirect contact with a heat exchanging medium is known from EP0271299. This citation discloses a reactor and process that combines steam reforming and autothermal reforming. The steam reforming zone arranged in the lower region of the reactor comprise a number of tubes with catalyst dis- posed inside while on the upper region of the reactor an autothermal reforming catalyst is disposed outside the steam reforming tubes. EP-A-1 106 570 discloses a process for steam reforming in parallel connected tubular reformers (reactors) comprising a number of steam reforming tubes and being heated by indirect heat exchange. The catalyst is disposed in one reactor outside the steam reforming tubes and inside the steam re- forming tubes in the other reactor.

WO0156690 describes a heat exchange reactor including an outer shell provided with process gas inlet and outlet ports, a plurality of reactor tubes supported at their upper ends, header means for supplying process gas from said header inlet port to the upper ends of the reactor tubes, said means including two or more primary inlet headers disposed across the upper part of said shell, each primary inlet header having a depth greater than its width, whereby said tubes are supported, relative to the shell directly or indirectly by said primary inlet headers. EP1048343A discloses a heat-exchanger type reactor which has a plurality of tubes holding a catalyst, a shell section through which a heat-transfer medium is passed to carry out heat-transfer with a reaction fluid in said tubes, and upper and lower tube sheets, the upper ends of said tubes being joined to said upper tube sheet by way of first expansion joints fixed to the upper side of said upper tube sheet, the lower ends of said tubes being fixed directly to the floatable lower tube sheet, a floatable room being formed which is partitioned by said lower tube sheet and an inner end plate (inner head) joined to the lower side thereof and has an opening in the lower part, and said opening being joined by way of a second expansion joint to a tube-side outlet to the outside of the reactor.

Due to the conditions of the catalytic reaction process, the heat exchange reactor must have a structure which can absorb the differential thermal expansion between the tubes and the housing due to the temperature difference between them. Also the structure must be able to absorb the differential thermal expansion between the tubes, which is caused by the temperature difference between tubes, produced by the difference in reaction and heat-transfer conditions between tubes, the difference being due to the tolerance in tube inner diameter in the reactor, the difference in catalyst packing density in each tube, the difference being due to the tolerance in tube inner diameter in the reactor, the difference in catalyst packing density in each tube, the difference in catalyst activity, the uneven distribution of a reaction gas flowing through the tubes, the uneven distribution of a heat-transfer medium flowing through the shell section etc.

Conventional heat exchange reactors with tubes fixed in tube heads and the tube heads fixed to the reactor housing cannot meet these requirements because they cannot cope with the differential thermal expansion between the housing and the tubes or between the tubes. In EP 1048343 the thermal expansion can be absorbed by first expansion joints for each tube and a second expansion joint in connection to a floating lower tube head. Thus the solution to the expansion problems disclosed by EP 1048343 demands for both first and a second expansion joints and further the first expansion joints must have sufficient strength that can bear the load due to the weight of the tubes, catalysts and the lower tube head a well as the pressure difference between tube side and shell side. Further the second expansion joint of EP 1048343 are desirably isolated from the reaction fluid or the heat exchange fluid if these have temperatures of for example 500°C or above, because it is a problem to provide gas tight joints for such high temperatures. Another solution is to accept a slight leak of gas at the ex- pansion joint, by providing e.g. a labyrinth seal. This is however not acceptable for all applications.

It is an object of the present invention to provide a heat exchange reactor which solves the mentioned problems, especially the expansion problems. A further object is to pro- vide an improved heat exchange reactor which can operate at high temperatures but still have a gas tight sealing between the tubes and the tube heads.

Features of the invention 1. A heat exchange reactor (100) for carrying out endothermic or exothermic reactions comprising,

• a housing (101 ),

• said housing defining a reactor wall (102),

• a plurality of heat transfer tubes (103) arranged within said housing for the supply or removal of heat in catalyst beds (104) disposed inside or outside said heat transfer tubes, • a first tube head (105) located at the upper part of the housing for supporting the upper part of the heat transfer tubes,

• a second tube head (106) located at the lower part of the housing for supporting the lower part of the heat transfer tubes,

· at least a first fluid chamber (107), a second fluid chamber (108) and a third fluid chamber (109) located inside said housing, said first fluid chamber is located in the upper part of the housing above the first tube head, said second fluid chamber is located in the mid-section of the housing between the first and the second tube head, and said third fluid chamber is located in the lower part of the housing under- neath the second tube head,

• at least four fluid openings in said housing: at least one fluid opening (1 10) in the first fluid chamber, at least two fluid openings (111 , 1 12) in the second fluid chamber and at least one fluid opening (1 13) in the third fluid chamber,

the first and the second tube head have bores for each of the heat transfer tubes, wherein the lower part of each heat transfer tube is fixed supported both side-wards and up-wards by the second tube head and the upper part of each heat transfer tube is sliding supported to the first tube head, whereby the second tube head supports the load of the plurality of heat transfer tubes and prevents them from moving relative to the second tube head and the first tube head supports the plurality of heat transfer tubes in a side-wards direction allowing the heat transfer tubes to move up- and downwards relative to the first tube head.

2. A heat exchange reactor according to feature 1 , wherein said lower part of the heat transfer tubes comprise a bottleneck (114), whereby the cross-sectional area of the lower end of the heat transfer tubes and the cross sectional area of each bore in the second tube head is smaller than the cross-sectional area of the heat transfer tubes above the bottleneck.

3. A heat exchange reactor according to feature 2, wherein the catalyst beds are lo- cated inside the heat transfer tubes and said heat transfer tubes each comprise a support (115) located in the lower part of each of the heat transfer tubes above the bottleneck to support the catalyst beds.

4. A heat exchange reactor according to feature 3, further comprising a spacer (1 16) located between the bottleneck and the support to adapt the height of the support. 5. A heat exchange reactor according to feature 4, wherein said support and said spacer is one integrated unit.

6. A heat exchange reactor according to any of the preceding features, wherein at least one of the first and the second tube head has a concave shape.

7. A heat exchange reactor according to any of the preceding features, wherein the second tube head has an ellipsoidal shape, whereby the load of the heat transfer tubes are distributed to the edge of said second tube head.

8. A heat exchange reactor according to any of the preceding features wherein at least one of the first and the second tube head is insulated (1 17) on at least one side of the tube head. 9. A heat exchange reactor according to feature 8, wherein the insulation (1 17) is located on the side of the at least one of the first and the second tube head which faces the second fluid chamber and the thickness of the insulation is adapted so that the insulation has a substantially plane surface on the face of the insulation which is facing towards the second fluid chamber.

10. A heat exchange reactor according to any of the features 8 - 9, wherein the part of each of the heat transfer tubes which is located in the second fluid chamber between the first and the second tube head and the insulation is of substantially equal length. 11. A heat exchange reactor according to any of the preceding features, wherein the sliding support of the upper part of the heat transfer tubes to the first tube head comprises a sealing (1 18).

12. A heat exchange reactor according to feature 1 1 , wherein said sealing comprises for each heat transfer tube a stuffing box (1 19) with packing rope (120) which is compressed around the heat transfer tube by compression means (121 ).

13. A heat exchange reactor according to any of the preceding features, wherein a least one of the heat transfer tubes is provided with attachment means (122, 130) at the upper part, thereby enabling lifting at least all of the heat exchange tubes and the second tube head. 14. A heat exchange reactor according to any of the preceding features, wherein said reactor wall forms at least a first tubular section (124) arranged by the second fluid chamber upper part, a second tubular section (125) arranged by the second fluid chamber mid part and a third tubular section (126) arranged by the second fluid cham- ber lower part, said first and third tubular section have a larger diameter than the second tubular section to allow for at least two ring chambers to evenly distribute the fluid to and from the at least two fluid openings in the second fluid chamber and to and from the lower and upper surface part of the heat transfer tubes. 15. A heat exchange reactor according to any of the preceding features, further comprising a liner (127) arranged around the heat transfer tubes within the second fluid chamber, said liner has perforations (129) for evenly distribution of the fluid to and from the at least two fluid openings in the second fluid chamber and to and from the lower and upper surface part of the heat transfer tubes.

16. A heat exchange reactor according to feature 15, wherein at least a part of the area of said liner which is facing at least one of the at least two fluid openings in the second fluid chamber is without said perforations, whereby said area can act as a fluid impingement plate.

In an embodiment of the invention, a heat exchange reactor for carrying out endother- mic or exothermic reaction comprises a housing with a reactor wall, heat transfer tubes, tube heads, fluid chambers and fluid openings. The housing and the heat transfer tubes are arranged in a substantially vertical position which is advantageous for the structural strength of the components especially under operation at elevated temperature and pressure. The reactor is divided in at least three fluid chambers by the tube heads. In the first fluid chamber located in the upper part of the housing above the first tube head, a first fluid is let in through a fluid opening and is distributed to the heat transfer tubes. The first fluid flows inside the tubes downwards to the third fluid cham- ber located in the lower part of the housing underneath the second tube head, where the flow from each tube is collected and let out of a fluid opening. In the second fluid chamber located in the mid-section of the reactor housing, a second fluid is let in via one fluid opening located in the lower part of the mid-section. The second fluid flows upwards in the mid-section while it performs heat exchange with the first fluid through the heat transfer tube walls. In the upper part of the mid section, the second fluid is let out through another fluid opening. Catalyst beds can be arranged inside the tubes or outside the tubes in the second fluid chamber. The heat transfer tubes are supported by the two tube heads. The tubes are sliding supported in bores in the first upper tube head, hence while the upper part of each tube is supported and fixed against movement in horizontal directions they are free to move in vertical directions independent of each other. Particular for the present invention is that the tubes are fixed in the second lower tube head, they are not able to move in any direction relative to the second tube head. The lower part of each tube is fixed to the second tube head at the location of a corresponding bore in said tube head; it can be fixed with the lower end of each tube directly above the corresponding bore, fixed with the end of the tube inside the bore or fixed with the end part of the tube within the bore and the tube end underneath the tube head. Fixing the tube to the second tube head can be done in any known way as for instance welding, which is preferable because it is gas tight. It is important that the fixing method can withstand the operating temperatures. It is understood that since the tubes are only sliding fixed to the first tube head in vertical directions, it is the second tube head which supports the load of the plurality of heat transfer tubes.

The first fluid may flow in a downwards direction: via a fluid opening in the first fluid chamber it flows from the first fluid chamber, through the heat transfer tubes to the third fluid chamber and out of a fluid opening; or in an other embodiment it may flow in the opposite direction. In an embodiment the second fluid may flow in an upwards direction from a fluid opening in the lower part of the second fluid chamber, up through the second fluid chamber around the tubes and out of the second fluid chamber via a fluid opening in the upper part of the second fluid chamber. In the embodiment where the first fluid flows downwards, the second fluid flows upwards, the catalyst bed is placed inside the heat transfer tubes and the reaction is endothermic, the second fluid must transfer heat to the first fluid. Hence, it is advantageous that the tubes are fixed for instance by welding to the second tube head where the temperature is the highest.

In an embodiment of the invention the heat transfer tubes have a bottleneck at their lower part, whereby the outer and inner diameters of the tubes are reduced. Accordingly the lower end part of the tubes which is fixed to the second tube head need a corresponding bore in the second tube head which is only large enough to correspond to the reduced tube diameter, which in return increases the strength of the second tube head compared to a tube head perforated by bores of a larger diameter. In a further embodiment of the invention where the catalyst beds are located inside the heat transfer tubes, a support for the catalyst bed is located inside the tubes in the lower part of the tubes above the bottleneck. The support can be of any suitable construction, for instance a wire mesh on top of a support grid surrounded by a support ring. The bottleneck serves as a lower support stop for the catalyst support and a spacer can be placed between the bottleneck and the catalyst support to adjust the height of the catalyst bed in each tube. The support and the spacer can also be integrated into one single unit, the height of the unit can then be varied to adjust the height of the catalyst bed in each tube as mentioned.

In yet a further embodiment of the invention, at least one of the first and the second tube head has a concave shape. Especially for the second tube head, which supports the load of the heat transfer tubes and the catalyst bed, a concave shape, for instance an ellipsoidal shape is advantageous as it transfers the load on the centre part of the tube head out to the periphery of the tube head where the tube head can be supported by the reactor wall. The spacers which adjust the height of the catalyst supports in each tube can be adapted to compensate for the concave shape of the second tube head such that the bottom of the catalyst bed in each tube has the same height in the reactor. This is advantageous when an even catalytic activity in all tubes is desired.

In an embodiment, at least one of the first and the second tube head is insulated on the side of the tube head facing the second fluid chamber. In cases where the temperature in the second fluid chamber is higher than the temperature in the first and the third fluid chamber and within the tubes, the insulation protects the insulated tube head from the high temperatures and the tube head thickness can therefore be reduced for given strength requirements. This is especially advantageous for the second load bearing tube head. Further, the insulation thickness can like the catalyst support height be adapted to compensate for a given concave shape of the first and/or the second tube head, whereby the insulation surface is substantially plane and the length of the tubes between the opposing insulation surfaces or between the insulation surface and the opposing tube head can be substantially equal for all the tubes. In a further embodiment the top and the bottom of the catalyst beds in each heat transfer tube is located at the same or nearly the same height as the insulation surface. In an embodiment of the invention, the upper part of each heat transfer tube is sealed towards the upper tube head. The seal provides the side-wards support of the tubes in the bores of the tube head and a substantially fluid-tight connection, but allows for the described sliding movement of the tubes in the bores relative to the first tube head. In an embodiment, the seal comprises a stuffing box for each tube. The stuffing box can be fixed (for instance by welding or other known means) to the first tube head around each bore. The seal may be a ceramic packing rope which is compressed between the stuffing box and the outer wall of each tube around the tube by means of compression such as a threaded nut or any other known compression means. The stuffing box may further comprise locking means, such as a locking bolt to prevent the compression means from dismounting.

It is a particular advantage of the invention that in the embodiment where relative hot fluid enters the second fluid chamber via a fluid opening in the lower part of the second fluid chamber and relative cold fluid (to be heated by the relative hot fluid) flows through the heat transfer tubes, the seal located in the stuffing box in the first fluid chamber is exposed to temperatures considerably lower than the highest temperature of the relative hot fluid. This means that a substantially fluid-tight seal can be achieved even for processes where the hottest inlet gas is considerably above the maximum allowable for a given sealing material. In a further embodiment of the invention, at least one of the heat transfer tubes is provided with attachment means at the upper part of the tubes. This allows for the mounting of mechanical stops, which prevents the heat transfer tubes to slide out of the first tube head when it is lifted, for instance in lifting lugs fixed to the first tube head. The attachment means can be of any known art, such as a thread, bores through the tube, snap locks, barbs, couplings, unions, connectors or the like; and they can be mounted on the outside, inside or both the outside and inside of the tube. The attachment means provide a simple mounting of the heat transfer tubes and the tube heads in the reactor: A number of mechanical stops sufficient to carry the total weight of the tubes and the tube heads are mounted at the attachment means on top of a corresponding number of tubes, where after all the tubes and the first and the second tube head can be lifted. After mounting the tube heads and the tubes in the reactor, the mechanical stops are removed.

In an embodiment of the invention two fluid distribution ring chambers are provided in connection with the two fluid openings in the second fluid chamber. The ring chambers provides an even fluid distribution from the fluid inlet opening to the area around all the heat transfer tubes nearest one end and an even fluid distribution from the area around all the heat transfer tubes nearest the other end to the fluid outlet opening. Said ring chambers are constructed as sections of the reactor wall around the second fluid chamber with an enlarged diameter which allows for the fluid to flow around the tube bundle. These enlarged diameter sections of the reactor wall are located in the upper part and the lower part of the second fluid chamber, The mid part of the fluid chamber has a reactor wall diameter only slightly larger than the tube bundle outer diameter to minimize the material consumption. In one embodiment of the invention, the fluid inlet to the second fluid chamber is at the lower part of the second fluid chamber and the fluid outlet from the second fluid chamber is at the upper part of the second fluid chamber. Evenly distribution of the fluid in the second fluid chamber around all the heat transfer tubes as well as an even distribution of catalyst beds in even lengths of heat transfer tubes as mentioned earlier is all ensuring an even reaction level and even heat transfer between the fluid inside and outside the heat transfer tubes.

In an embodiment of the invention, even fluid distribution around all the heat transfer tubes is further ensured by a liner located inside the reactor wall in the second fluid chamber and surrounding all the heat transfer tubes (the tube bundle). At least in a part of the area of the ring chambers, said liner is provided with openings distributed around the liner which is otherwise formed as a sheet enclosing the tube bundle. Through the openings in the liner in the area of the ring chamber for the fluid inlet, the fluid in the second fluid chamber flows from the fluid inlet to the corresponding ring chamber and into the space around the heat transfer tubes nearest one end of the tubes. Likewise, through the openings in the liner in the area of the ring chamber for the fluid outlet, the fluid in the second fluid chamber flows from the space around the heat transfer tubes nearest the other end of the tubes, through the openings in the liner in the area of the ring chamber for the fluid outlet, to the corresponding ring chamber and out through the fluid outlet of the second fluid chamber. The liner can be seal tight fixed to the reactor wall to ensure that no fluid bypasses between the tube bundle and the reactor wall, be- cause fluid passing between the reactor wall and the tube bundle from the second fluid chamber inlet to the second fluid chamber outlet would lower the heat transfer efficiency.

In a further embodiment of the invention, the openings in said liner are evenly distrib- uted around the circumference of each end of the liner, except for the areas of the liner directly facing the fluid openings of the second fluid chamber. In these areas, at least a part of the liner has no openings, whereby this part of the liner acts as a fluid impingement plate which further provides an even fluid distribution around the heat transfer tubes. As well known in the art, the tube bundle can be provides with baffles, for instance of the disc and doughnut type to further enhance the heat transfer between the fluid outside and the fluid inside the tubes.

The present invention will be discussed in more detail with reference to some embodi- ments of the invention as shown in the drawings in which:

Fig. 1 is a cross section side view of one embodiment of a heat exchange reactor,

Fig. 2 is a cross section top view of the second fluid chamber fluid inlet and outlet,

Fig. 3 is a cross section side view of the heat exchange reactor before assemblage, Fig. 4 is a detail view of the insulated first tube head,

Fig. 5 is a detail view of the insulated second tube head,

Fig. 6 is a detail view of the liner and the first tube head with baffles and tie rods,

Fig. 7 is a detail view of the lower part of a heat transfer tube,

Fig. 8 is a detail view of the stuffing box at the upper part of a heat transfer tube, Fig. 9 is a detail view of an upper part of a tube including attachment means,

Fig. 10 is a detail view of the insulated second tube head and the third fluid chamber.

Position number overview

100. heat exchange reactor

101. housing

102. reactor wall

103. heat transfer tubes

104. catalyst bed

105. first tube head

106. second tube head

107. first fluid chamber

108. second fluid chamber

109. third fluid chamber

110. fluid opening, first fluid chamber

111. fluid opening, second fluid chamber upper part

112. fluid opening, second fluid chamber lower part 1 13. fluid opening, third fluid chamber

1 14. bottle neck

1 15. support grid

1 16. spacer

1 17. insulation

1 18. seal

1 19. stuffing box

120. packing rope

121. compression means

122. attachment means (thread)

123. lifting lugs

124. first upper tubular section of the reactor wall

125. second mid tubular section of the reactor wall

126. third lower tubular section of the reactor wall

127. liner

128. baffle

129. liner perforations

130. lock nut It is to be understood that the following are only some specific embodiments of the invention. One advantage of the invention is that it is scalable, therefore other dimensions and tube-numbers are a scope of the present invention.

The HTER as shown in Fig. 1 is a tubular heat exchange reformer. It is a heat ex- change reactor 100, comprising a housing 101 with reactor walls 102 and with catalyst 104 inside the heat transfer tubes 103. It has two separate flows; a process gas (PG) that flows on the tube side (inside the tubes) and an effluent gas (EG) that flows on the shell side (outside the tubes). There are 1300 tubes. In this embodiment, the catalytic reaction is an endothermic reaction. Therefore the process gas inside the tubes needs heat transferred from the effluent gas on the shell side of the tubes.

Process gas flow

The relative cold process gas (cold relative to the Effluent gas) enters the first fluid chamber 107 at the very top of the reactor through the fluid opening 110 in the first fluid chamber and distributes via the first tube head 105 to the heat transfer tubes. The PG flows through the tubes that are filled with catalyst and a reforming reaction takes place while receiving heat from the shell side. The PG leaves the tubes via the second tube head 106, flows to the third fluid chamber 109 and exits through the fluid opening 1 13.

Effluent gas flow

The relative hot EG (hot relative to the process gas) enters the second fluid chamber 108 on the shell side of the tubes through the fluid opening 1 12 in the lower part of the second fluid chamber. The flow passes by the tubes in a baffle configuration delivering the heat to the reaction inside the tubes. The EG exits through the fluid opening 11 1 in the upper part of the second fluid chamber. The baffles 128 are of the disc and donut configuration and cause a large degree of cross flow past the tubes. Distributing the EG flow to/from the tube bundle is done via a ring chamber in the first upper tubular section of the reactor wall 124 and the third lower tubular section of the reactor wall 126 and a liner 127 giving a desired radial inlet to and a radial outlet from the tube bundle as can be seen in fig. 2. When the EG enters the reactor it is distributed on the circumference in a ring chamber around the liner. The EG then flow through perforations 129 made in the liner. There are fewer perforations at the nozzle position. In this way the liner acts as an impingement plate. The liner that stretches from the bottom to the top of the reactor is also perforated in the top to obtain a radial flow when the EG exits the baffle configuration. The liner is welded to the reactor wall 102 to avoid by- pass of the EG. In the second mid tubular section of the reactor wall 125, the liner is near the tube bundle, as no fluid is indented to by-pass in this section.

The shell of the reactor including the liner and the tube bundle is shown in fig 3 separately as seen before the bundle is mounted inside the reactor. The load from the 1300 tubes is taken up by the ellipsoidal tube head in the bottom of the reactor. The tube head is insulated 1 17 above the tube head resulting in a tube head temperature of the process gas exiting the tubes. The load of the upper ellipsoidal tube head, the baffles and tie rods is taken up at the top shell flange. The upper tube head is insulated below the head giving it PG inlet temperatures. The load from the liner is taken up by the shell at the cone connection.

Thermal expansion

The tubes are fixed at the bottom tube head. The thermal elongations of the tubes are taken up by one mechanism - a stuffing box 119 pr tube at the upper tube head. This allows for individual differences in tube elongation as seen in fig. 4. The baffle configuration hangs from the top tube head with tie rods and moves downward when heated. The liner is welded to the shell. The two ends of the liner will from this point expand upwards and downwards respectively.

Upper tube head assembly

The upper tube head has a number of lugs 123 for lifting in the installation activity of the bundle. The head is insulated from below with a fibrous ceramic material which is held in place by a liner plate. The tube head is perforated for the 1300 tubes. At each perforation there is a stuffing box assembly above the head. Lower tube head assembly

The head is insulated from above with a fibrous ceramic material which is held in place by a metallic liner plate, see fig. 5.

Liner and baffle assembly

The liner is welded to a cone on the shell. It is perforated at the top and bottom.

The baffles are held in place by tie rods. The tie rods are connected to the upper tube head as can be seen on fig. 6.

Tube assembly

The tubes have varying length due to the ellipsoidal tube heads.

There is attachment means 122 such as a threaded section in the top of the tube in a part of the tubes. This is used for mounting of lock nuts 130 when lifting the bundle by the lifting lugs.

Wire mesh.

Referring to fig. 7, the catalyst rests on a support grid 115. Spacers 1 16 such as thin walled cylindrical tubes keep the catalyst support grid in correct height. The tube diameter is taken down in a bottleneck 114 at the bottom part of the tubes. This is done to gain a larger ligament and therefore a thinner tube head.

Stuffing box assembly

The 1300 stuffing boxes 119 are comprised of a stuffing box where a seal 1 18 comprising packing rope 120 is placed. As can be seen on fig. 8, there are compression means 121 such as a gland ring which works as a hollow bolt that rotates around the tube when the ropes are compressed. In between the ropes and the gland ring there is a fol- lower ring that protects the packing rope from friction forces when the box is tightened. The stuffing box assembly is welded to the tube head from inside.

Site assembly

To assemble the tube bundle into the shell you lift in the lifting lugs at the upper tube head. The lower tube head is lifted by the tubes that are held in place by a lock nut to the top head. Fig. 9: The Stuffing box assembly shown with lock nut 130 (left top). The lock nuts act as connections between the upper tube head where the crane is connected and the tubes and lower tube head. When the bundle is in place the seal weld is made between the lower tube head and the shell connection.

Fig. 10: Final assembly steps of bottom part of reactor. The bundle is lowered and the ellipsoidal tube head and the shell connection are seal welded. EXAMPLE

The ~410°C cold process gas enters at the very top of the reactor and distributes to the tubes. The PG flows through the tubes that are filled with catalyst and reforming reaction takes place while receiving heat from the shell side. The PG leaves the tubes at ~750°C and exits through the bottom outlet.

The ~1005°C hot EG enters on the shell side through the lower nozzle. The flow passes by the tubes in a baffle configuration delivering the heat to the reaction inside the tube. The EG exits through the upper shell side nozzle at a temperature of ~600°C. The top head has an inner diameter of 4250mm is 85mm thick and is made from SA- 387 gr22 cl2. The head is insulated from below with a fibrous ceramic material which is held in place by a 3 mm thick Inconel 693 liner plate.

The lower head is 50mm thick and has an inner diameter of 3600mm. The head is made from either Inconel 625 or Haynes 230. The head is insulated above with a fi- brous ceramic material which is held in place by a 3 mm thin Inconel 693 liner plate. The liner, baffles and tie rods are made from Inconel 693.

The tubes are approx. 11 meters long with an inner diameter of 50mm and an outer diameter of 60mm. All parts of the tube assembly are made from Inconel 693.