IT202000019945A1 - REACTOR FOR NON ISOTHERMAL REACTIONS - Google Patents

Description

"Reactor for non-isothermal reactions"

DESCRIPTION

Field of invention

The present invention ? relating to a reactor for non-isothermal reactions and used for chemical synthesis.

State of the art

As known from the state of the art, chemical syntheses take place in various reactor configurations. In particular, in the presence of exothermic or endothermic reactions, it becomes essential to find devices that are able to efficiently transfer the heat from one area of the reactor to another. A classic example? represented by the synthesis of methanol, one of the pi? interesting and promising molecules of organic synthesis, but also one of the most? complicated to obtain because of? exothermic? of the reaction, of the risk of activating methanation reactions, even more? exothermic and above all for the low yield in the single step. In this regard, countless technological solutions are known. In particular, the known reactor configurations can be classified into: gas phase technologies (adiabatic, isothermal, fluidized bed), liquid phase technologies and membrane technologies. In detail, for adiabatic gas-phase technologies, some examples are the multi-stage Quench Converter by Johnson Matthey, the spherical fixed bed reactor by Kellog, Brown and Root (KBR), the multi-stage reactor by Haldor-Topsoe/Udhe, the Haldor-Topsoe (Collect-Mix-Distribute reactor) and Halliburton reactors for the revamping of the quencher, the Casale ARC reactor and the MRF-Z reactor? of Toyo Engineering Corporation. As far as isothermal gas phase technologies are concerned, the Linde helical tube reactor, the Lurgi combined reactor (among the most widespread in the world), the Mitsubishi Superconverter, the axial and axial-radial reactors developed by Casale and the Steam Raising Converter (SRC) by Davy Process Technology. What about the other reactor types? it should be noted that they are also used in areas other than methanol, or wherever it is necessary to exchange heat efficiently.

? therefore felt the need? to find alternative solutions in order to improve the heat exchange efficiency during the non-isothermal reactions with the cooling/heating fluids, in order to maximize the reactor efficiency, increasing the conversions of the reactants and at the same time increasing the yields of reaction into the desired end products.

Summary of the invention

In order to overcome the aforementioned problems, the reactor object of the present invention was conceived.

It is a reactor for non-isothermal reactions in the gaseous phase comprising: - a tubular reactor comprising at least one tube through which reaction fluids pass (A), and in which tubular reactor ? defined as a portion where at least one non-isothermal reaction occurs;

- a shell external to said tubular reactor, in which passes a fluid which acts as a cooling/heating fluid for said reaction fluids.

in which:

(i) Do the reaction fluids enter the head of this tubular reactor and exit at the end of said tubular reactor and said portion where at least one isothermal reaction takes place? filled with a specific catalyst for said reaction, while the remaining portion of the tubular reactor ? empty

the coolant/heating fluid that flows in the mantle can? be introduced in the gas phase, in the liquid phase and/or a combination of both and acts as both a cooler and a heater for the reaction fluids in different portions of the same tubular reactor;

(iii) in said outer shell in which said cooling/heating fluid passes? at least one liquid-vapour separation zone is defined, in which at least one stage of liquid-vapour separation of the cooling/heating fluid takes place.

LIST OF FIGURES

Figure 1: schematic representation of a reactor for non-isothermal reactions in the gas phase according to an embodiment of the present invention;

Figure 2: schematic representation of the reactor zones for non-isothermal reactions in the gaseous phase according to the embodiment of figure 1;

Figure 3: schematic representation of a reactor for non-isothermal reactions in the gas phase according to an alternative embodiment of the present invention;

Figure 4: schematic representation of the reactor zones for non-isothermal reactions in the gaseous phase according to the embodiment of figure 3;

Figure 5: schematic representation of a first detail of the reactor for non-isothermal reactions in the gaseous phase according to the embodiment of figure 1 and figure 3;

Figure 6: schematic representation of a second detail of the reactor for non-isothermal reactions in the gaseous phase according to the embodiment of figure 1 and figure 3;

Figure 7: schematic representation of a third detail of the reactor for non-isothermal reactions in the gaseous phase according to the embodiment of figure 1 and figure 3; Figure 8: schematic representation of a reactor for non-isothermal reactions in the gas phase according to an alternative embodiment of the present invention.

DETAILED DESCRIPTION

For the purposes of the present invention, the reaction fluids A can be of different types and characterized by the fact that they reach the sufficient temperature and pressure conditions to carry out the non-isothermal reaction in correspondence with the portion of the tubular reactor containing the catalyst. The reaction fluids A comprise the reagents necessary for the synthesis of the desired product and, after passing through the portion of the reactor filled with the catalyst, they also comprise the desired reaction product(s).

For the purposes of the present invention, the fluid B introduced into the shell 20 can be inserted in the gaseous phase, in the liquid phase and/or a combination of both. Fluid B? configured to act both as a cooler and as a heater or vice versa for certain portions of the same tubular reactor according to the specific non-isothermal reaction.

The reactor? configured in such a way that in the liquid vapor separation area the fluid B, when ? in the vapor state it condenses, or if in the liquid state it evaporates, thus exploiting 2 times the latent heat of evaporation to cool or heat the reaction fluids according to the specification of the non-isothermal reaction. In addition to that? the reactor object of the present invention, in addition to exploiting the latent heat of evaporation twice, is also characterized in that, preferably, the vapor which condenses on the tubes forms a thin film which further increases the heat exchange.

Specifically, the reaction fluids A enter the head of the tubular reactor and leave the tail of the same. In accordance with a preferred embodiment, the tubular reactor comprises a plurality of of tubes which allow to maintain a uniform thermal profile in the entire tubular reactor, guaranteeing the heat exchange between the reaction fluids e and the fluid B.

The incoming reaction streams from the head 10a of the tubular reactor 10 comprise one or more? reactants configured to react with the catalyst inside the same at the reaction portion The at least partially reacted reaction fluids inside the tubular reactor leave the tubular reactor at the bottom and can contain, in addition to the reaction products, unconverted reactants intermediate products reactions comprise a mixture of synthesis gas and reagents.

The reactor object of the invention can? provide downstream a? unit? of separation of the reaction products from the reactants, which are subsequently recycled at the top of the reactor.

The shell of the reactor comprises at least one inlet of the cooling/heating fluid in the liquid or vapor phase and at least one outlet in the liquid or vapor phase.

For the purposes of the present invention, the reaction portion of the tubular reactor generally containing the specific catalyst for the non-isothermal reaction is also defined as a first heat exchange zone between the reaction fluids flowing in the tubular reactor and the coolant/ heater present in the outer shell. Similarly, by liquid-gas separation zone we mean a second heat exchange zone between the reaction fluids and the shell-side fluid. The reaction portion and the shell side separation zone are contiguous along the reactor object of the invention.

In accordance with a preferred embodiment, the liquid-gas separation zone comprises a staged liquid-gas separator arranged along said separation zone. Preferably, the stage separator comprises a distillation column, a rectification column, a packed column or a structured packed column disposed along the reactor.

Pi? preferably, the stage separator ? a distillation column or plate rectification arranged along the tubular reactor, arranged in the mantle near? of the remaining portion of the reactor not occupied by the catalyst.

Preferably, the plates are overflow. They are characterized by the fact that the liquid descends from the upper tray, travels the tray from one side to the other and then passes by gravity through pipes or down comers into the lower tray. Plates can be drilled, bell or valve. According to a particularly preferred solution as shown in figures 5-7, the weir plates are perforated each plate 42 comprises holes 42a for the passage of the cooling/heating fluid in the form of steam Furthermore, each plate 42 comprises holes 42b for the passage of the pipes which form the tubular reactor. Preferably, the tubular reactor occupies about 80% of the total surface area of each plate 42.

According to the aforementioned preferred embodiment shown in Figures 5-7, each tray 42 also comprises a dam 42c configured to maintain on the tray 42 at least one head of condensed liquid cooling/heating fluid and a downcomer 42d which directs the condensed liquid B to the lower plate facilitating the distribution of the condensed liquid.

Since we are dealing with weir plates, the weirs 42c and the downcomers 42d on superimposed plates are arranged alternately.

Each plate 42 can? comprise guides 42e which facilitate the removal of the respective plate 42 during any maintenance of the system.

For the purposes of the present invention, non-isothermal reactions are understood to mean endothermic reactions or exothermic reactions.

According to the type of reaction carried out inside the tubular reactor, is the catalyst? positioned at the head or tail of the same as detailed below.

Specifically, according to the type of non-isothermal reaction and the number of stages used for the liquid-gas separation, three variants can be identified in accordance with the present invention.

Reactor for single stage exothermic reactions

In accordance with the present embodiment illustrated in figure 8, the non-isothermal reaction carried out inside the tubular reactor 10 is an exothermic reaction.

Preferably, in this embodiment the catalyst 31 inside the portion 30 is? arranged at the end 10b of the tubular reactor 10. In this way, the portion 30 acts as a unit? heating of the cooling/heating fluid B in place of a conventional external reboiler.

In accordance with the present variant, the fluid B ? introduced inside the shell in a liquid stage BL at the tail of the reactor. In this way, the fluid B in the liquid state indicated by BL submerges the portion 30 of the tubular reactor 10. Preferably, in order to avoid overheating in the reaction zone and possible breakages of the tubular reactor 10, the fluid B submerges not only the portion of reaction 30 but also a contiguous part of the tubular reactor 10 in the direction of the head 10a.

In the present case, the reaction fluids A enter from the head 10a of the tubular reactor 10 at a lower temperature than the reaction temperature at the region portion 30. Preferably the tubular reactor ? equipped with a plenum 12 from which the reaction fluids A enter, reach a uniform pressure and temperature and are pushed inside one or more? pipes 11 towards the tail 10b of the tubular reactor 10 and from which they exit.

The reaction fluids A exchanging heat with the vapor state fluid B BV at the separation portion 40 gradually increase the temperature during the transition from the top to the tail of the tubular reactor 10. In other words, the vapor state fluid B BV occupies the empty volume of the shell 20 in correspondence with the liquid-gas separation portion 40.

Reaction fluids A reach reaction portion 30 where ? placed the catalyst 31 at a suitable temperature and react according to an exothermic reaction.

The heat produced by this ration? removed by the fluid B which externally wets the tubes 11 of the tubular reactor 10. In this way, the fluid B in the liquid state, acting as a refrigerant, removes the heat produced by the exothermic reaction, passing at least partially into phase. Specifically, the fluid B in the liquid state changes to the vapor state BV starting to migrate towards the reactor head 100.

The fluid B in the vapor state condenses at least partially in correspondence with the liquid-gas separation zone 40 defined by the shell 20. Specifically, the fluid B in the vapor state migrating towards the head of the reactor 100 impacting on the plurality of pipes 11 condenses and exchanges heat with the reaction fluids A at a lower temperature than the fluid B in the vapor state.

Advantageously, this way ? It is possible to exploit twice the latent heat of the fluid B. In fact, the fluid B in the vapor state by condensing releases the same latent heat, for the evaporation, to the fluids of reactants A.

Moreover, ? to note that the fluid B in the vapor state condensing on the plurality? of pipes 11 in correspondence with the liquid-gas separation zone 40 forms a thin film FS on the pipes themselves which improves the heat exchange between the fluid B and the fluids A with respect to a gas/gas exchange system (such as, for example, for Lurgi reactors or Davy Process Technology).

In accordance with a preferred embodiment, any incondensables deriving from the degradation of the fluid B in the liquid state and/or the dissolution of the fluid B in the gas state can be removed from the head of the shell 20 together with portions of vapor which are not suitably recondensed.

? to note that the fluid B can? be removed during the shutdown phase of the reactor in correspondence with a discharge channel CS1 arranged at the end 20b of the shell 20. it should also be noted that the reactor 100 comprises a further discharge channel CS2 for the fluid B in the liquid state BL arranged in correspondence with the reaction zone 20 on the shell side 20, usable for managing the liquid level on the shell side.

Furthermore, the shell side reactor 100 comprises a vent channel CS3 at the shell head 20a and configured to discharge the fluid B in the vapor state BV.

In accordance with the present variant, the catalyst 31 is loaded by the head 10a of the tubular reactor 10 by inserting it inside the tubes 11 and ? discharged from the tail 10b of the tubular reactor 10 itself.

Advantageously, the present variant allows the heat exchange to be intensified in order to preheat the fluids of reactants A in order to carry out an exothermic reaction.

In accordance with a preferred embodiment, the reactor 100 comprises a support grid 50 for the tubular reactor 10 at its tail.

During maintenance operations, the catalyst is discharged from the tail of the reactor.

Reactor for exothermic reactions to pi? stadiums

In accordance with the present embodiment illustrated in figures 1 and 2, the non-isothermal reaction carried out inside the tubular reactor is an exothermic reaction.

Preferably, in this embodiment the catalyst 31 is arranged at the end 10b of the tubular reactor 10 defining the portion 30. In this way, the reaction portion 30 acts as a unit? heater in substitution of a reboiler known to the person skilled in the art as shown in figure 2. Furthermore, it is it should be noted that this reactor, unlike the single-stage variant, comprises a stage separator 41 of the type described above.

Also in this case, the fluid B ? inserted inside the shell in the liquid state BL in order to keep the reaction zone 30 completely immersed.

As before, the reaction fluids A entering the head of the tubular reactor 10 are preheated along the separation portion 40 and subsequently react at the reaction portion 30. The heat produced by the exothermic reaction is removed from the fluid B in the liquid state which passes at least partially into the vapor state BV. The steam produced exchanges heat with the pipes 11, thus preheating the reaction fluids A. The heat exchange also in this case ? optimized by the fact that the latent heat of the fluid B is exploited twice and by the formation of a thin film on the shell side pipes 11.

In accordance with the present variant, the presence of the plate distillation column makes it possible to optimize the heat exchange in correspondence with each plate 42 between the fluid B and the reaction fluids A. In fact, the liquid B in the vapor state migrating from the tail 20a to the head 20b of the shell 20 tends to condense at least partially on each plate 42.

The reactor 100 comprises an outlet channel CU1 for the fluid B in the excess vapor state. This excess steam can be sent back to condensation.

Furthermore, in accordance with a preferred embodiment, part of the fluid B following the condensation outside the reactor ? reintroduced inside the shell-side reactor 100 at an inlet channel CI1 preferably at the top 20a of the shell 20. The reactor 100 comprises a further inlet channel CI2 shell-side to feed the fluid B in the liquid state BL.

? to note that the fluid B condensed in correspondence with each plate 42 ? directed by downcomer 42d to lower plates up to the tail 20b of the skirt 20.

Again, during shutdown ? it is possible to discharge the fluid B in the liquid state from the tail of the reactor 100 through a further outlet channel CU2 in the tail 20b of the shell 20.

At the same time, the catalyst 31 ? loaded in the head of the reactor and pu? be unloaded when exhausted at the tail end of the reactor.

In accordance with a preferred embodiment, the reactor 100 comprises a support grid 50 for the tubular reactor 10 at its tail.

Reactor for endothermic reactions to pi? stadiums

In figure 4 ? An embodiment of the reactor object of the invention for conducting the endothermic reactions is reported

Preferably, in this embodiment the catalyst 31 is arranged at the head 10a of the tubular reactor 10 defining the portion 30, in which the reaction takes place. In this way, the reaction portion 30 acts as a unit? refrigerant instead of a conventional external condenser.

In accordance with the present variant, the reaction fluids A after being uniformed in temperature and flow in a plenum 12 in the head 10a of the tubular reactor 10 enter the pipes 11 where they meet the catalyst 31 positioned at the head. In this way, the reaction fluids A react according to an endothermic reaction thus acting as condensers of the fluid (B) which passes on the shell side.

Fluid B? introduced inside the shell 10 in the gaseous state BV from the tail 20b of the shell 20. Specifically, the fluid B in the gaseous state BV ? introduced by means of an inlet duct CI3 arranged at the tail 20b of the shell 20. In accordance with a preferred embodiment, the fluid B ? introduced into the shell in the liquid state by means of an inlet channel C14 disposed between the head 20a and the tail 20b.

In this way, during the ascent from the tail 20b to the head 20a, the fluid B in the vapor state exchanges heat with one or more? tubes 11 of the tubular reactor 10 condensing on the shell side. Also in this case the fluid B forms a thin film on the external surface of each tube 11 of the tubular reactor 10 optimizing its heat exchange.

Fluid B, arriving at the head, condenses further by exchanging heat in correspondence with the reaction zone 30.

The excess vapor leaves the shell at the head 20a through an outlet channel CU3 while a part of the condensate BL in the reaction zone 30 comes out of the shell 20 in the form of distillate through a further outlet channel CU4. The latter ? preferably located below the reaction zone 30.

In accordance with the present variant, the reactor 100 comprises a tray distillation 41 which in this case collects the fluid B condensed in the various stages along the reactor 100 and discharges it from the tail 20b of the shell via an outlet channel CU5.

In accordance with the present invention, the catalyst 31 is loaded and unloaded from the head of the tubular reactor 10. In fact, at each tube 11 ? arranged a basket 60 containing the catalyst during operation of the reactor which then retains it at the top of the tubular reactor in order to carry out the endothermic reaction.

Claims (9)

1. Reactor for non-isothermal reactions in the gas phase (100) comprising: - a tubular reactor (10) comprising at least one tube (11) through which reaction fluids (A) pass and in which tubular reactor ? defined a portion (30) where at least one non-isothermal reaction takes place; - an outer shell (20) of said tubular reactor (10) in which a cooling/heating fluid (B) passes in which (i) The reaction fluids (A) enter the top of said tubular reactor (10) and exit at the end of said tubular reactor (10) and said portion (30) where at least one non-isothermal reaction takes place, ? filled with a specific catalyst for said reaction, while the remaining portion of the tubular reactor (10) is empty; (ii) the cooling/heating fluid (B) flowing in the shell can? be introduced into said reactor in the gaseous phase, in the liquid phase and/or a combination of both and acts both as a cooling fluid and as a heating fluid for the reaction fluids (A) in different portions of the same tubular reactor (10); (iii) in said outer shell (20) ? defined at least one gas-liquid separation zone (40), in which at least one gas-liquid separation stage of the fluid (B) takes place 2. Reactor for non-isothermal reactions in the gaseous phase (100) according to claim 1, wherein the fluid (B) in the vapor state condenses on the outer surface of said at least one tube (11) of said tubular reactor (10) in the form of thin film. The reactor for non-isothermal reactions (100) according to claim 1 or 2, wherein said non-isothermal reaction is exothermic and the portion (30) of said tubular reactor (10) filled with the catalyst, is located at the end of said tubular reactor (10), and, in the portion of the shell side near the of the portion (30) where the reaction takes place, the fluid (B) ? in the liquid state and completely covers said portion (30) where at least one exothermic reaction takes place and the entire portion (30) filled with catalyst acts as a reboiler for the fluid (B) which passes in the shell (20). The reactor for non-isothermal reactions (100) according to claim 1, wherein said non-isothermal reaction is endothermic, said reaction portion (30) of the tubular reactor filled with the catalyst, which is located at the head of the tubular reactor (10) acts as a condenser of said fluid (B) on the shell side. 5. Reactor for non-isothermal reactions (100), according to any one of claims 1 to 4, wherein said separation zone (40) comprises a staged gas-liquid separator (41). 6. Reactor for non-isothermal reactions in the gas phase (100), according to claim 5, wherein the stage separator (41) is selected from a distillation column, a rectification column, a packed column or a structured packed column arranged along all of said separation zone. The reactor for non-isothermal reactions (100) according to claim 6, wherein the separator (41) is? a distillation or plate rectification column. 8. Reactor for non-isothermal reactions according to claim 7, wherein the trays of the column are weir-shaped. 9. Reactor for non-isothermal reactions (100) according to claim 8, wherein each tray (42) comprises holes (42A) for the passage of the fluid (B) in vapor form, a dam (42c) to keep a head of fluid (B) condensed liquid on the plate and a downcomer (42d), which directs the condensed liquid (B) to the lower plate, housings (42b) for at least one tube (11) of said tubular reactor (10), which passes through said plates (42) and guides (42e) which facilitate the removal of said plate during maintenance of the reactor.