WO2003067354A1

WO2003067354A1 - System for and method for performing a chemical reaction

Info

Publication number: WO2003067354A1
Application number: PCT/EP2003/001119
Authority: WO
Inventors: Peter John Van Den Brink; Maarten Bracht; Hans De Jonge
Original assignee: Avantium International B.V.
Priority date: 2002-02-05
Filing date: 2003-02-04
Publication date: 2003-08-14
Also published as: AU2003206839A1

Abstract

A system for performing a chemical reaction, in particular a chemical experiment, said system comprising: - a reactor (5) having an outlet (5b); - a first conduit (2; 14, 15) having an inlet (3) connected or connectable to said outlet (5b) of said reactor, said first conduit (2) further having an outlet (4), which first conduit (2; 14, 15) allows a discharge of fluid from said reactor (5); said system further including a back-pressure regulator assembly (1) comprising: - a first flow restrictor (7) arranged between the inlet (3) and the outlet (4) of the first conduit (2; 14, 15); and - pressure control fluid supply means (8) connected to the first conduit (2) between the inlet (3) and the first flow restrictor (7), said supply means (8) comprising a source (13) of a pressure control fluid and said supply means (8) being adapted to supply pressure control fluid to said first conduit (2; 14, 15) in order to obtain a substantially constant pressure in the first conduit (2; 14, 15).

Description

SYSTEM FOR AND METHOD FOR PERFORMING A CHEMICAL REACTION

The present invention relates to a system for performing a chemical reaction including a back-pressure regulator assembly.

Several back-pressure regulator assemblies are known in practice. Back-pressure regulator assemblies are used in industry in which it is desired to maintain a system at a certain pressure, whilst a reaction is carried out. Suitably, say in a hydrogenation process, high pressure hydrogen is available in a storage vessel at a pressure well above the working pressure required. The pressure of hydrogen emerging from the storage vessel, suitably a cylinder, containing hydrogen under high pressure, say initially at 100 bar, is normally reduced to a lower value, say 10 bar, to prevent pressure waves being formed and can be fine tuned to obtain the actual flow needed in the reactor by means of a flow control valve. Such pressure regulators can be used to control pressure in a closed or in a venting, one-phase system.

In order to keep the reactor environment at the required level (e.g. 5 bar) it is necessary to install a so-called back-pressure regulator assembly downstream of the reactor environment which is capable of maintaining the pressure in the reactor at the required level. In practice this means that such an assembly must be capable of reducing or even closing the passage of gas or liquid in a conduit downstream of the reactor until the pressure has come back to the required level or, conversely, is capable of relieving the pressure by opening the conduit downstream of the reactor to the extent that the passage of gas or liquid is such that the required pressure is maintained again. A back-pressure regulator assembly can also be used in systems, wherein reactants (e.g. hydrogen) will be consumed or in systems in which higher pressures may be created because of the production of gases or the exothermicity of the reaction contemplated, causing the pressure to increase above the required level.

In some processes, the operator will be faced with a fluid containing both gaseous and liquid components that need to be kept at a certain pressure. The amount of the gaseous and liquid components will be dependent on the type of process (es) envisaged. In the context of this invention the expression "fluid" is meant to comprise materials being either in the gaseous phase or in the liquid phase or mixtures of the two phases as the case may be.

Standard back-pressure regulator assemblies are operated by adjusting the flow through the conduit by increasing or decreasing the area of the (valve) opening through which the fluid travels by mechanical, pneumatic, electrical or any other means which will be capable of adjusting the flow to the required level. Assemblies based on springs or bellows are commonly applied. However, when the fluid contains both gaseous and liquid components these standard back-pressure regulator assemblies start to malfunction, both due to the limited dynamic range of such assemblies and due to their relative slow response. A large dynamic range (typically a factor 1000) is needed because of the significant difference in viscosity between the liquid and the gas phase. This asks for a wide dynamic range of resistance values of the regulator assembly. However most valves employed do not offer a dynamic range large enough to both control the flow of liquids and gases in a similar volumetric range. A fast response of the valve is needed to cope with very abrupt changes in viscosity in such systems. When a slug of liquid reaches the valve, because of its high viscosity it passes the area relatively difficult, which as it leads to build up of pressure results in a large opening of the valve. When in such a position suddenly a slug of gas reaches the valve control mechanism, most valves will not able to close fast enough to avoid loss of pressure. One known way to avoid these problems is by separating the gas and liquid before control of the pressure.

A well known problem in industry is that it is difficult to separate gaseous and liquid components in situations where it is required to maintain the total pressure at a required (pre-set) level, especially in systems in which a multitude of reaction vessels is involved or when dealing with systems in which rather small volumes are present. One solution is to introduce a sluice system in the conduit downstream of the reactor in order to drain off liquid which allows the use of a standard gas-phase back-pressure regulator assembly to deal with the setting of the pressure level by controlling only the gaseous component still present. Reference is made in this respect to US patent publications 4,682,622 and 4,971,104, respectively.

Turning to systems which are designed to operate with rather small reactor volumes, in particular for performing chemical experiments, suitably reactor systems operating with a throughput of 100 Nml/minute of gas and of 5 Nml/minute of liquid or less, in particular with systems operating under a gas flow regime of less than 10 Nml/minute of gas and 0,5 Nml/minute of liquid, it was found that, even for systems in which only one phase (either gaseous or liquid) is present it is already very difficult to reliably control the back-pressure, let alone for systems in which two phases (gaseous and liquid) are present. The option of introducing a sluice is no^' longer possible in that the size of the equipment is so small that fitting sluice devices is no longer feasible. Moreover, such systems suffer from the presence of so-called "dead volumes" which has a further disadvantage in that it is prone to a built-up of sludge which will hamper and eventually block the normal operation of the system.

Further, in the area of high throughput experimentation dead volumes lead to longer purging times when online analysis is used to analyse the effluent of the reactors or to collect a sample for offline analysis.

Moreover, in conditions of rather small reaction vessels, and, in particular in systems in which use is made of arrays of small reactors such as in arrays currently envisaged for high throughput experimentation such as in rapid catalyst screening, a number of additional problems needs to be addressed. In particular the consequences of operating at rather high pressures need to be taken into account and, together with the small volumes in the total system set stringent requirements in order to be able to operate leak-tight. Further, in small reactor systems the small volumes lead to much higher sensitivity of the pressure to fluctuations of the back pressure regulating system. These pressure fluctuations may cause large variations in the reaction kinetics of the individual reactors resulting in erroneous results. The pressure fluctuations also bring about variations in flow through the reactors causing different residence times in the reactor. This also leads to erroneous results.

Also, the so-called "dead-volume" which is nearly always present in valve systems becomes relatively large- when down scaling standard back-pressure regulator assemblies which has an undesired influence of the working of the device.

It is an object of the present invention to solve one or more of the above and other problems . It is a further object of the present invention to provide an alternative back-pressure regulator assembly having a surprisingly simple design.

It is a particular object of the present invention to provide an alternative and surprisingly simple back-pressure regulator assembly for regulating the pressure in the reactors of a high throughput experimentation apparatus .

To this end the present invention provides a system according to claims 1 and 23.

Herewith a very simple and effective back-pressure regulator assembly is obtained, which can be used both in a one-phase and in a two-phase fluid system allowing a substantially constant pressure upstream from the back-pressure regulator assembly to be maintained.

The person skilled in the art will understand that with "fluid container" any container or vessel is meant, downstream of which the pressure is to be regulated. In the preferred embodiment, the fluid container is a reactor for performing a reaction involving one or more reagents. In particular the reactor can be a flow-reactor having an inlet for one or more reagents. In a very advantageous application the reactor is a flow-reactor having an inlet for one or more liquid reagents and for one or more gaseous reagents.

The outlet of the first conduit may be connected to e.g. an analyser or a fluid sampling device, if desired.

The back-pressure regulator assembly of the present invention is in particular of use in a gas/liquid pressure environment which hitherto was impossible to control satisfactorily on a large scale, let alone on a small scale. The assembly is capable of operating reliable for a long time under severe reaction conditions, which has a tremendous advantage, in particular when used in rapid screening duty. Moreover, it can be manufactured at reasonable costs and it enjoys operational robustness.

According to a first preferred embodiment, the supply means comprise a pressure reducing regulator. A pressure reducing regulator is often also denoted "pressure reducer". This pressure reducer may be connected to a pressurised supply vessel, like for instance a gas cylinder. The pressure reducer reduces the pressure of the pressure control fluid to the desired pressure level. Pressure reducers are well known to those skilled in the art and may be mechanically or electronically controlled. Preferably, the pressure reducer is designed in this embodiment of the back-pressure regulator assembly according to the present invention, to supply and reduce an inert fluid, preferably nitrogen gas. Using an inert fluid, the analysis of the fluid samples in the analyser, if any, is not affected. Also due to it's inertness the fluid will not interact chemically with the fluid originating from the reactor.

According to a second preferred embodiment a first pressure detector is provided for measuring a fluid pressure value in the first conduit and control means are provided which are designed to compare the pressure value detected by the first pressure detector with a reference pressure value, and in response thereto, make the supply means supply a suitable amount of pressure control fluid to the first conduit if the pressure value detected by the first pressure detector is below, e.g. a pre-set amount, the reference pressure value. According to the present invention "a suitable amount of pressure control fluid" means such an amount of pressure control fluid needed to keep the pressure (compared to the reference pressure value) detected by the pressure detector at the required level.

Usually the reference pressure value used in the fluid pressure regulator according to the present invention will be a suitable preset value. If desired, the preference pressure value can be related to the pressure value in another conduit. To this end the present invention provides a back-pressure regulator assembly wherein the control means are designed to compare the pressure value detected by the pressure detector with the reference pressure value detected by a second pressure detector for measuring the fluid pressure in a second conduit.

According to a third preferred embodiment, the supply means for pressure control fluid are designed to keep the pressure control fluid in a vapour/liquid equilibrium. Herewith no moving constructional parts are present in the process fluid stream. Also no pressure detector is required to regulate the pressure. The person skilled in the art will understand that any means for keeping the pressure control fluid in a vapour/liquid equilibrium may be used, for example a reservoir containing the pressure control fluid provided with temperature control means, such as heating means, capable of maintaining the pressure control fluid at said equilibrium. Instead or in addition pressure control means may be used. In this case "a pressure control fluid" means a fluid not chemically interacting with the (process) fluid originating from the reactor. The pressure control fluid may e.g. be freon, water, propane, ethane, ...

Preferably, the supply means of the back-pressure regulator assembly according to the present invention are designed to supply an inert fluid, preferably nitrogen gas, helium gas or argon gas. Using an inert fluid, the analysis of fluid samples in the analyser, if^" any, is not affected. As supply means e.g. any controllable valve may be used. The person skilled in the art will readily understand that as an inert fluid any fluid may be used which does not have a significant influence on the optional analysis of fluid samples. Nitrogen gas is preferably used, as it is an inexpensive and easy usable gas. Preferably, the first pressure detector is placed between the pressure control fluid supply means and the first conduit. Herewith no pressure detector is present in the first conduit, thereby minimizing possible 'hold up¹ of (process) fluid contained therein. Also herewith the pressure detector will not be exposed to any harmful characteristic (corrosiveness, contamination) of the fluid originating from the reactor.

Further the system preferably comprises a pressure relief valve between the supply means and the first conduit. Herewith it is possible to prevent the occurrence of a pressure in the first conduit above a certain limit.

According to an advantageous embodiment of the back-pressure regulator assembly according to the present invention, the flow restrictor is adjustable. Herewith the upper limit of the flow of the fluid exiting the conduit of the back-pressure regulator assembly can be easily chosen.

According to a further preferred embodiment, the back-pressure regulator assembly comprises a buffer system, preferably placed between the pressure control fluid supply means and the first conduit . In a preferred embodiment the first conduit is connectable to the outlets of at least two reactors. Herewith the pressure in several reactors may be regulated using only one regulator. Of course, a selector valve may be present between the inlet of the first conduit and the outlet of each of the reactors .

In another aspect of the present invention the pressure control fluid supply means are connectable to more than one first conduits . With such an arrangement it is possible to control the back pressure of a multitude of reactors using only one pressure regulator. In a further aspect the present invention relates to a system for high throughput experimentation. Usually, in high throughput experimentation, the outlet of the first conduit will be connected to an analyser, and/or instead, to a fluid sampling device. In case of more than one first conduit, the (low pressure) outlets of the multitude of first conduits will either be collected or analyzed in parallel or led to a special type of multi-position valve to be collected or analyzed sequentially. Such multi-position valves are designed to select one stream from a multitude of fluid streams to flow to a selected stream outlet while combining the non-selected streams to flow to one common outlet. Such multi-position valves are commercially available and for instance described in the catalogue of VICI AG (Valco International) .

In a similar yet different embodiment of the present invention the back-pressure regulator assembly may be combined with the above mentioned multi-position selector valve. Now the selector valve may be positioned between the reactor outlets and the back-pressure regulator assembly. By connecting the pressure supply means of the back-pressure regulator assembly to both the common outlet and the selected stream outlet the pressure of all fluid streams leading to the selector valve can be controlled. The selected stream is led e.g. to an on-line analyser for analysis. Sampling to the analyser can take place at any point between the exit of the selector valve and the restrictor, but also at low pressure behind the restrictor.

The back-pressure regulator assembly according to the present invention is suitably used in small scale operations since it meets the critical parameters therefore, in particular under conditions of using a fluid containing both gaseous and liquid components as it has a large dynamic range. In particular, it can be used advantageously in situations wherein use is made of reactor vessel arrays in which a number of (different) physical and/or chemical operations can be performed, either simultaneously or sequentially.

The desire to perform a multitude of operations in a short time is well-known to those skilled in the art and a number of systems has already been proposed, and some are commercially available, to decrease the time in which, and possibly, the size which physical and/or chemical operations have to be performed. However, there is still room for improvement in carrying out operations at elevated temperature and pressure in reactor vessel arrays. It is also possible to make use of a number of back-pressure regulator assemblies (each back-pressure regulator assembly being connected to one reactor or a plurality of reactors) pre-set at different levels to operate at different pressure levels whilst providing the reactor vessels in the array with a fixed pressure. This allows the option to perform series of experiments at different pre-set pressure levels which is highly advantageous in combinatorial chemistry.

Further the present invention relates to a process for regulating the back-pressure in a conduit being connected to an outlet of a reactor, the conduit containing a flow restrictor, wherein a pressure control fluid is fed to the conduit, such that a substantially constant pressure is obtained in the conduit.

In one embodiment of the process according to the invention, the pressure of the pressure control fluid is kept constant by a pressure reducing regulator.

In an alternative embodiment, the pressure of a fluid originating from the reactor that is fed to the conduit is measured by a pressure detector obtaining a fluid pressure value, the measured fluid pressure value is compared with a reference pressure value, and a suitable amount of pressure control fluid is supplied to the conduit if the pressure detector measures a pressure value which is below, e.g. a pre-set amount, the reference pressure value.

In a further embodiment of the process according to the invention, the pressure control fluid is kept in a vapour/liquid equilibrium.

In yet another embodiment of the process according to the invention, the pressure control fluid is fed to a multitude of conduits, such that a substantially constant pressure is obtained in all conduits. In another preferred embodiment of the process according to the invention, the pressure control fluid is fed to two outlet conduits of a multi-position selector valve, such that a substantially constant pressure is obtained in both conduits and the selected stream exiting the valve is analysed.

The present invention will hereinafter be illustrated in more detail by a drawing. Same reference numbers refer to similar elements . Herein shows :

Figure 1 a schematic diagram of the back-pressure regulator assembly according to a first embodiment of the present invention;

Figure 2 a schematic diagram of the back-pressure regulator assembly according to a further embodiment of the present invention;

Figure 3 a schematic diagram of the back-pressure regulator assembly according to an alternative embodiment of the present invention; and

Figure 4 and Figure 5 a schematic diagram of an apparatus, in particular for high throughput experimentation, comprising the backpressure regulator assembly of the present invention.

Figure 1 shows a schematic diagram of system for performing a chemical reaction, in particular a chemical experiment, including a back-pressure regulator assembly 1.

The system includes a flow reactor 5 having an inlet 5a connected to a fluid feed means 30, in particular a feed means 30 for feeding a liquid and/or gaseous reactant to the flow reactor 5. The reactor 5 has an outlet 5b for discharging an effluent from the reactor 5. The outlet 5b is connected to a conduit 2 having an inlet 3 and an outlet 4.

The outlet 4 of the conduit 2 is connected to the inlet of an analyser 6 (such as a MS, GC, etc.) .

The system further includes a back-pressure regulator assembly 1 comprising a flow restrictor 7 arranged in the conduit 2 between the inlet 3 and the outlet 4 of the conduit 2. Suitably, as a flow restrictor 7 a needle valve, capillary, electronically adjustable valve, etc. may be used.

The back-pressure regulator assembly 1 further comprises supply means 8 for supplying a pressure control fluid to the first conduit 2 upstream of the flow restrictor 7 such that a constant pressure in said part of the first conduit 2 can be obtained. This allows for control of the pressure in the reactor 5.

The supply means 8 are preferably designed to supply an inert fluid, such as nitrogen gas. In the embodiment of Figure 1, the supply means 8 comprise a storage vessel 13 for storing a pressure control fluid, said storage vessel 13 having an outlet connected to a pressure reducing regulator 20. This pressure-reducing regulator 20 has internal control means designed to reduce the pressure of the pressure control fluid supplied from a storage vessel 13 to a constant pressure downstream of that pressure reducing regulator 20. As the flow and the supply of the storage vessel 13 is virtually unlimited in relation to the chemical reaction or experiment this pressure will determine the pressure of the downstream conduits, such as first conduit 2. Suitably, as a pressure reducing regulator 20 a mechanical system based on for instance membranes or cylinders can be used. These systems are often based on a spring. Also electronic systems with an internal feed-back mechanism can be used.

As an option the system can include one or more pressure detectors 9, a pressure relief valve 11 arranged between the pressure reducing regulator 20 and the conduit 2 and a one-way valve 10 arranged between the regulator 20 and the conduit 2.

Persons skilled in the art will recognise that analyser 6 can be connected to any position on the first conduit 2, such as directly downstream of the outlet 5b of the reactor vessel 5 or directly downstream of the inlet of the pressure control fluid into the first conduit 2.

Also shown is an optional buffer system 17. The buffer system 17 will attenuate sharp pressure changes that for instance can be caused by sharp changes in flows to or from the first conduit 2, or that can be caused by opening or closing valves leading to or from the first conduit 2. When due to such events the demand for pressure control fluid suddenly increases and the pressure control fluid supply means do not respond quickly enough, the volume of pressure control fluid already present in the buffer system 17 will moderate the drop in pressure in the first conduit 2. Vice versa, when the demand of pressure control fluid suddenly drops the buffer system 17 will be able to take up some pressure control fluid without drastic increase of pressure.

Such buffer system 17 is highly useful when dealing with fluids in the first conduit 2 that consist of two phases with different viscosity. The large difference in viscosity will cause abrupt changes in demand of pressure control fluid supply means 8.

The buffer system 17 will also be highly useful when the regulator 20 has a slow response.

As buffer system 17 any container with an internal volume may be used. As such for instance a vessel or a long tube will be suitable. The buffer system may be put in-line with the conduit that leads from the pressure supply means to the first conduit 2. However, it may also be connected with a T-connection to the conduit that leads from the pressure control fluid supply means 8 to the first conduit 2.

As the response time of a pressure reducing regulator 20 typically is in the order of one second, for an optimal buffering the volume of the buffer system 17 should be such that it should be able to supply pressure control fluid for at least a period of at least one second (s) . Therefore its volume (ml) preferably should exceed the average volume (ml) of all fluid flowing through the conduit 2 during the period of one second. For example, if the volumetric flow of the fluid through conduit 2 is 1 Nml/s the volume of the buffer system 17 preferably should be at least 1 ml. Persons skilled in the art will understand that preferably the buffer volume is significantly higher than that value, i.e. the volume of the buffer system is preferably larger than the total volume of fluid flowing through first conduit during the period of one second.

Figure 2 shows a system including n alternative embodiment of the back-pressure regulator assembly 1.

In this embodiment at least one pressure detector 9 is present. Further, the supply means 8 are in this embodiment in the form of adjustable supply means 8 for supplying pressure control fluid to the conduit 2. Also, control means 12 are provided. The pressure detector 9, supply means 8 and control means 12 co-operate as follows.

The control means 12 compare, in use of the back-pressure regulator assembly 1, the pressure value detected by the pressure detector 9 with a reference pressure value, and in response thereto make the supply means 8 supply a suitable amount of pressure control fluid to the conduit 2 if the pressure value detected by the pressure detector 9 is e.g. a pre-set amount below the reference pressure value. The pressure detector 9 may, and preferably will, be present between supply means 8 and the conduit 2. However the pressure detector 9 may also be present in other positions, as denoted with A and B in Figure 2. Also, more than one pressure detector 9 may be present, if desired, to monitor the pressure on different locations. In use of the back-pressure regulator assembly 1 according to Figure 2 a (process) fluid is transported from the reactor 5 to the inlet 3 of the conduit 2. If the pressure detector 9 detects a value which is (e.g. a pre-set amount) below the reference pressure value, then the control means 12 will make the supply means 8 supply a suitable amount of pressure control fluid, such as e.g. inert nitrogen gas. Hereby the occurrence of pressure variations in the conduit 2 are prevented.

If desired, the control means 12 may be designed to compare the pressure value detected by the pressure detector 9 with a pressure value detected by a second pressure detector (not shown) for measuring the fluid pressure in a second conduit (not shown) , instead of comparing it with a pre-set reference pressure value. In that case the system is useful for maintaining a constant pressure difference between two first conduits .

In the embodiment of Figure 3, the supply means 8 are designed to keep the pressure control fluid in a vapour/liquid equilibrium. To this end the supply means 8 comprise a reservoir 21 for pressure control fluid in liquid and gaseous form as well as temperature control means 22, such as heating means, so that a vapour/liquid equilibrium is obtained in reservoir 21 of the supply means 8. Further, although not required, a pressure detector 9, such as a pressure gauge, may be present for measuring a fluid pressure value in the conduit 2. The pressure detector 9 is preferably connected between the supply means 8 and the conduit 2 to minimize dead volume in the conduit 2, but may also be placed in other positions where the pressure in the first conduit 2 can be measured directly or indirectly. The person skilled in the art will also understand that further means may be present. For example, the system may comprise a pressure relief valve 11 between the supply means 8 and the first conduit 2. Also a one-way valve 10 may be present. Also a buffer system may be present.

In use of the back-pressure regulator assembly 1 according to Fig. 3, a (process) fluid is transported from the reactor 5 to the inlet 3 of the conduit 2. As the pressure control fluid is kept in a vapour/liquid equilibrium, any pressure variation in the conduit 2 will be balanced by the pressure control fluid.

A person skilled in the art will understand that the pressure to be maintained in the conduit 2 can be preset by selecting appropriate conditions in the supply means 8, e.g. using suitable temperature control means 22.

Figure 4 shows a schematic diagram of a system comprising multiple reactors 5, in particular a high throughput experimentation system, including a back-pressure regulator assembly.

The pressure control fluid supply means 8 are employed for controlling the pressure in said multiple reactors 5. Hereto a common pressure control fluid supply means 8, which can be similar to configurations as shown in figure 1-3 (i.e. comprising for example the pressure reducing regulator 20 according to Fig. 1) , is connected to the various first conduits 2 downstream of the reactors 5. Each conduit 2 has a restrictor 7.

Persons skilled in the art will recognize that analyser 6 can be connected to any position of first conduit 2, such as directly after the inlet of the pressure control fluid into the first conduit 2. The person skilled in the art will also understand that further means may be present.

Figure 5 shows another system wherein a back-pressure regulator assembly is employed for controlling a multitude of reactors 5.

The reactors 5 have their outlets 5b connected to a selector valve 18. The valve 18 has a selected outlet 18a and a common outlet 18b. The position of the valve 18 determines which reactor 5 is in communication with the selected outlet 18a, while all the other reactors are connected to the common outlet 18b. A conduit 14 is connected to the selected outlet 18a and to an analyser 6. A flow restrictor 7 is arranged in the conduit 14.

A conduit 15 is connected to the common outlet 18b and has its outlet connected to a waste 35. A flow restrictor 7 is arranged in the conduit 15.

A common pressure control fluid supply means 8 is employed, which can be similar to configurations as shown in figure 1-3. This supply means 8 is connected to the conduit 14 and the conduit 15. Each connecting conduit includes a one-way valve 10.

It has been found that a system including the back-pressure regulator assembly according to the present invention not only allows for quick and accurate control in situations in which the flow is essentially gaseous or essentially liquid (i.e. containing at most insignificant amounts of the other phase as the case may be) but also in situations in which the flow is in two-phase mode, i.e. in systems in which both gaseous and liquid components contribute to the fluid. The major advantage of the system including a back-pressure regulator assembly according to the present invention is that it is capable, also in situations operating at rather low flow regimes (e.g. flow regimes of 5 ml/minute, or even less) to deal with fluids containing both gaseous and liquid components. Operating at such low flow regimes in two-phase flow can not be achieved in such a surprising simple manner with existing equipment.

Claims

C A I M S

1. A system for performing a chemical reaction, in particular a chemical experiment, said system comprising: a reactor (5) having an outlet (5b) ; a first conduit (2; 14, 15) having an inlet (3) connected or connectable to said outlet (5b) of said reactor, said first conduit (2) further having an outlet (4), which first conduit (2; 14, 15) allows a discharge of fluid from said reactor (5) ; said system further including a back-pressure regulator assembly (1) comprising: - a first flow restrictor (7) arranged between the inlet (3)^' and the outlet (4) of the first conduit (2;14,15); and

- pressure control fluid supply means (8) connected to the first conduit (2) between the inlet (3) and the first flow restrictor (7) , said supply means (8) comprising a source (13) of a pressure control fluid and said supply means (8) being adapted to supply pressure control fluid to said first conduit (2; 14, 15) in order to obtain a substantially constant pressure in the first conduit (2;14,15).

2. System according to claim 1, wherein the supply means (8) comprise a pressure reducing regulator (20) between said source (13) and said first conduit (2;14,15).

3. System according to claim 1 or 2, wherein the back-pressure regulator assembly (1) comprises:

- a first pressure detector (9) for measuring a fluid pressure value in the first conduit (2;14,15); and

- control means (12) designed to compare the pressure value detected by the first pressure detector (9) with a reference pressure value, and in response thereto, make the supply means (8) supply a suitable amount of pressure control fluid to the first conduit (2) if the pressure value detected by the first pressure detector (9) is below the reference pressure value.

4. System according to claim 3, wherein the control means (12) are designed to compare the pressure value detected by the first pressure detector (9) with the reference pressure value detected by a second pressure detector for measuring the fluid pressure in a second conduit .

5. System according to claim 3 or 4, wherein the first pressure detector (9) is placed between the pressure control fluid supply means (8) and the first conduit (2;14,15).

6. System according to claim 1, wherein the pressure control fluid supply means (8,21,22) are adapted to keep the pressure control fluid in a vapour/liquid equilibrium.

7. System according to claim 6, wherein the supply means (8) comprise a reservoir (21) for pressure control fluid and associated temperature control means (22) for maintaining said vapour/liquid equilibrium.

8. System according to one or more of the preceding claims, wherein said pressure control fluid is an inert fluid.

9. System according to one or more of the preceding claims, wherein a pressure relief valve (11) is arranged between the supply means (8) and the first conduit (2) .

10. System according to one or more of the preceding claims, wherein a one-way valve (10) is arranged between the supply means (8) and the first conduit (2; 14, 15).

11. System according to one or more of the preceding claims, wherein the first flow restrictor (7) is adjustable.

12. System according to one or more of the preceding claims, wherein the back-pressure regulator assembly (1) further comprises a buffer system (17) to attenuate pressure changes.

13. System according to one or more of the preceding claims, wherein said system comprises multiple reactors (5) , each outlet (5b) being connected to an associated first conduit (2) , and wherein a pressure control fluid supply means (8) is connected to each of said first conduits (2) , preferably a common pressure control fluid supply means (8) .

14. System according to one or more of the preceding claims, wherein said system comprises multiple reactors, and wherein the outlets of at least two reactors are connected to a common first conduit .

15. System according to one or more of the preceding claims 1-12, wherein the system comprises multiple reactors (5) , the outlets (5b) of the reactors being connected to a selector valve (18) , said selector valve having an selected outlet (18a) connectable to a selected reactor and having a common outlet (18b) connected to all non-selected reactors, and wherein said selected outlet and said common outlet are each connected to an associated first conduit (14, 15), and wherein a pressure control fluid supply means (8) is connected to each of said first conduits (14,15), preferably a common pressure control fluid supply means (8) .

16. System according to one or more of the preceding claims, wherein said system comprises multiple reactors to be operated at different pressure levels, and wherein said system comprises a backpressure regulator assembly for each of said reactors.

17. System according to one or more of the preceding claims, wherein said reactor (5) is a flow reactor and has an inlet (5a) and wherein said system includes fluid feed means (30) for feeding fluid to said inlet of said reactor.

18. System according to one or more of the preceding claims, wherein said fluid comprises both a liquid and a gaseous component.

19. System according to claim 17, wherein the system comprises multiple reactors connected to a common fluid feed means (30) for feeding fluid into said reactors.

20. System according to one or more of the preceding claims, wherein the outlet of said first conduit (2) is connected to an analyser and/or sampling device.

21. System according to one or more of the preceding claims adapted for high throughput experimentation.

22. A method for performing a chemical reaction, wherein use is made of a system according to one or more of the preceding claims, and wherein pressure control fluid is fed to the first conduit (2;14,15), such that a substantially constant pressure is obtained in the first conduit (2;14,15).

23. A system comprising: a fluid container (5) : a first conduit (2; 14, 15) having an inlet (3) and an outlet (4) , the inlet (3) of the first conduit (2) being connected to an outlet of a fluid container (5) to allow discharge of fluid from said container; a back-pressure regulator assembly (1) comprising: - a first flow restrictor (7) between the inlet (3) and the outlet (4) of the first conduit (2;14,15); and pressure control fluid supply means (8) connected to the first conduit (2) between the inlet (3) of the first conduit (2) and the first flow restrictor (7), the supply means (8) being capable of obtaining a substantially constant pressure in the first conduit (2) .

24. A system according to claim 23 and also one or more of the claims 2-21.