System and method for operating parallel reactors

Abstract

A system for operating parallel reactors includes a plurality of reactor assemblies, each reactor assembly including: a flow-through reactor, a reactor feed line, a reactor effluent line, a primary fluid source, and a flow splitter which is arranged downstream of the primary fluid source and upstream of the reactor assemblies. All passive flow restrictors have an substantially equal resistance to fluid flow. A feed line pressure measurement device and a pressure control arrangement controls backpressure regulators such that the measured feed line pressure becomes substantially the same as a feed line pressure setpoint in the reactor assemblies.

Claims

1. A system for operating parallel reactors, which system comprises: a plurality of reactor assemblies, each reactor assembly comprising: a flow-through reactor, said flow-through reactor comprising a reactor inlet and a reactor outlet, a reactor feed line, which reactor feed line has a first end and a second end, said second end being connected to the reactor inlet of the flow-through reactor, said reactor feed line being adapted to supply a fluid to the flow-through reactor, a reactor effluent line, which reactor effluent line has a first end, which first end is connected to the reactor outlet of the flow-through reactor, said reactor effluent line being adapted to discharge reactor effluent from the reactor, a primary fluid source, which primary fluid source is adapted to provide a pressurized fluid to the flow-through reactors, a flow splitter which is arranged downstream of the primary fluid source and upstream of the reactor assemblies, said flow splitter having an inlet and multiple passive flow restrictors, wherein the inlet of the flow splitter is connected to the primary fluid source and each passive flow restrictor is in fluid communication with said inlet, and wherein each passive flow restrictor has an outlet, which outlet is connected to the first end of the reactor feed line of its own dedicated reactor assembly, and wherein all passive flow restrictors have an substantially equal resistance to fluid flow, wherein the system further comprises a feed line pressure measurement device, said feed line pressure measurement device being adapted to measure the pressure in the fluid flow in the reactor feed lines, wherein in each reactor effluent line an individually controllable backpressure regulator is provided, said backpressure regulator being adapted to regulate the pressure in each reactor effluent line individually, wherein further a pressure control arrangement is provided, said pressure control arrangement being linked to said feed line pressure measurement device and said backpressure regulators, said pressure control arrangement comprising an input device allowing to input at least a feed line pressure setpoint into the pressure control arrangement, said feed line pressure setpoint representing a desired feed line pressure, said desired feed line pressure being the same for all reactor assemblies, wherein said pressure control arrangement is adapted and/or programmed to individually control the backpressure regulators such that for each reactor assembly the pressure measured in the reactor feed line by the feed line pressure measurement device is compared to said feed line pressure setpoint and in case of a difference between the measured feed line pressure and the feed line pressure setpoint, the corresponding backpressure regulator being adjusted such that the measured feed line pressure becomes substantially the same as the feed line pressure setpoint, and therewith substantially the same as the feed line pressures in the other reactor assemblies; and wherein the system further comprises a secondary fluid source and a dilution line, said secondary fluid source being adapted to provide a pressurized purge fluid or pressurized dilution fluid via said dilution line to at least one reactor assembly.

2. The system according to claim 1, wherein the feed line pressure measurement device comprises a plurality of feed line pressure sensors, said plurality of feed line pressure sensors being arranged such that in each reactor feed line a feed line pressure sensor is provided.

3. The system according to claim 1, wherein the feed line pressure measurement device comprises a single feed line pressure sensor, said single feed line pressure sensor being arranged to sequentially measure the pressure in the reactor feed lines.

4. The system according to claim 3, wherein the feed line pressure measurement device further comprises a dead end selection valve, said dead end selection valve comprising a valve housing, a valve body inside said valve housing, multiple inlet channels and one outlet channel, the valve body connecting one inlet channel with the outlet channel, the valve body being moveable inside the valve housing such that sequentially, each inlet channel can be brought into fluid communication with the outlet channel, wherein each inlet channel is connected to and in fluid communication with its own dedicated reactor feed line and wherein the outlet channel is connected to the single feed line pressure sensor.

5. The system according to claim 1, wherein the backpressure regulators are continuously adjustable.

6. The system according to claim 1, wherein the feed line pressure is measured at or adjacent to the reactor inlet, such that the measured feed line pressure corresponds to the reactor inlet pressure.

7. The system according to claim 1, wherein a backpressure regulator comprises: a flow channel for the fluid flow of which the pressure is to be controlled, said flow channel having a cross sectional area, a movable valve member, said moveable valve member being adapted to control the size of the cross sectional area of the flow channel in order to control the pressure of the fluid flow in the flow channel, a valve actuator, said valve actuator being adapted to control the position of the valve member, said valve actuator comprising a control chamber having a fluid under a reference pressure therein, said fluid engaging a pressure surface of the valve member for exerting a control force thereon, and a reference pressure controller, said reference pressure controller being adapted to control the reference pressure in said control chamber.

8. The system according to claim 7, wherein the reference pressure controller of the back pressure regulator comprises: a first restrictor channel, said first restrictor channel having an inlet and an outlet, a second restrictor channel, said second restrictor channel having an inlet and an outlet, a fluid passage, which fluid passage extends between the outlet of the first restrictor channel and the inlet of the second restrictor channel, said fluid passage allowing fluid communication between the first restrictor channel and the second restrictor channel, a pressure control fluid source, said pressure control fluid source being adapted to provide a flow of pressure control fluid through the first restrictor channel, the fluid passage and the second restrictor channel, said flow of pressure control fluid having an entrance pressure at the inlet of the first restrictor channel and an exit pressure at the outlet of the second restrictor channel, said entrance pressure being higher than said exit pressure, said flow of pressure control fluid experiencing a first pressure drop p1 over the first restrictor channel and a second pressure drop p2 over the second restrictor channel, a connector connecting the fluid passage to the control chamber of the valve actuator, said connector being in fluid communication with said control chamber, the pressure control fluid at the connector having an intermediate pressure which is lower than the entrance pressure but higher than the exit pressure, said intermediate pressure being determined by the ratio between the first pressure drop p1 and the second pressure drop p2, and a controllable thermal device, said thermal device being adapted to heat and/or cool the first restrictor channel and/or the second restrictor channel, therewith influencing the ratio between the first pressure drop p1 and the second pressure drop p2, said thermal device comprising a thermal controller for controlling the thermal output of the thermal device.

9. The system according to claim 1, wherein the passive flow restrictors of the flow splitter are capillary tubes and/or channels in microfluidic chips.

10. The system according to claim 1, wherein the system further comprises a plurality of filters, each filter being arranged in a reactor effluent line downstream of a reactor outlet, and wherein each backpressure regulator is arranged downstream of such filter.

11. The system according to claim 1, wherein at least one flow-through reactor comprises a fixed bed.

12. The system according to claim 1, wherein the dilution line is arranged to feed pressurized purge fluid or pressurized dilution fluid into a reactor effluent line, or wherein at least one flow-through reactor comprises a fixed bed, and the dilution line is arranged to feed pressurized purge fluid or pressurized dilution fluid into said reactor downstream of the fixed bed and upstream of the reactor outlet of said reactor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The drawing shows in:

(2) FIG. 1: a general set-up of a system with parallel reactors,

(3) FIG. 2: a first embodiment of a system according to the invention,

(4) FIG. 3: a second embodiment of a system according to the invention,

(5) FIG. 4: a possible embodiment of a backpressure regulator that can be used in the system and method according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows a general set-up of a system with parallel reactors, which for example can be used for performing high throughput experiments or as microreactors for the production of chemical compounds.

(7) In the system of FIG. 1, a fluid source 100 is present, which is connected to a flow splitter 105. The flow splitter 105 comprises one inlet 106 and multiple outlets 112A, 112B, 112C, 112D. Each outlet 112A, 112B, 112C, 112D of the flow splitter 105 is connected to an associated reactor assembly 150A, 150B, 150C, 150D.

(8) Just upstream of each flow splitter outlet 112A, 112B, 112C, 112D, a passive flow restrictor 110A, 110B, 110C, 110D is present.

(9) Each reactor assembly 150A, 150B, 150C, 150D comprises a reactor feed line 115A, 115B, 115C, 115D, a flow-through reactor 125A, 125B, 125C, 125D and a reactor effluent line 130A, 130B, 130C, 130D.

(10) The elements of the system of FIG. 1 are in fluid communication with each other in such a way that the reactors 125A, 125B, 125C, 125D receive pressurized fluid (either gas, liquid or a combination of gas and liquid) from fluid source 100. Each reactor 125A, 125B, 125C, 125D discharges its effluent via the associated reactor effluent line 130A, 130B, 130C, 130D.

(11) At some point in time during operation, the pressure in the fluid source, for example measured by pressure gauge 101, is p1. This pressure p1 generally is well above atmospheric pressure.

(12) At this same point in time during operation, the pressure in reactor feed line 115A, for example measured by pressure gauge 120A, is p2A. At this same point in time during operation, the pressure in reactor feed line 115B, for example measured by pressure gauge 120B, is p2B. At this same point in time during operation, the pressure in reactor feed line 115C, for example measured by pressure gauge 120C, is p2C. At this same point in time during operation, the pressure in reactor feed line 115D, for example measured by pressure gauge 120D, is p2D. The reactor feed line pressures p2A, p2B, p2C, p2D can for example be measured close to the flow splitter outlets 112A, 112B, 112C, 112D or close to the inlets of the reactors 125A, 125B, 125C, 125D. In case the reactor feed line pressures p2A, p2B, p2C, p2D are measured close to the inlets of the reactors 125A, 125B, 125C, 125D, the measured pressures p2A, p2B, p2C, p2D are the same or substantially the same as the reactor inlet pressures.

(13) If the resistance to fluid flow in the flow path between the fluid source 100 and the pressure gauge 120A is different from the resistance to fluid flow in the flow path between for example the fluid source 100 and the pressure gauge 120B, p2A is different from p2B.

(14) At this same point in time during operation, the pressure in reactor effluent line 130A, for example measured by pressure gauge 135A, is p3A. At this same point in time during operation, the pressure in reactor effluent line 130B, for example measured by pressure gauge 135B, is p3B. At this same point in time during operation, the pressure in reactor effluent line 130C, for example measured by pressure gauge 135C, is p3C. At this same point in time during operation, the pressure in reactor effluent line 130D, for example measured by pressure gauge 135D, is p3D.

(15) The reactor effluent line pressures p3A, p3B, p3C, p3D can for example be measured close to the outlet of the reactors 125A, 125B, 125C, 125D. In case the reactor feed line pressures p3A, p3B, p3C, p3D are measured close to the outlets of the reactors 125A, 125B, 125C, 125D, the measured pressures p3A, p3B, p3C, p3D are the same or substantially the same as the reactor outlet pressures.

(16) If the resistance to fluid flow in the flow path between the fluid source 100 and the pressure gauge 135A is different from the resistance to fluid flow in the flow path between for example the fluid source 100 and the pressure gauge 135B, p3A is different from p3B.

(17) When in systems of the type shown in FIG. 1 the pressure is controlledfor example to control the distribution of fluid flow over the individual reactors 125A, 125B, 125C, 125D, is is known to use a he pressure control system that is adapted to keep the pressures p3A, p3B, p3C and p3D (so: the pressures just downstream of the reactors 125A, 125B, 125C, 125D) the same. This can for example be done by using pressure controllers that are arranged just downstream of the reactor and all have the same set point for the desired pressure, or by collecting the reactor effluent flows in a single common exit control volume (as e.g. is disclosed in WO99/64160).

(18) However, according to the invention, it is not these pressures p3A, p3B, p3C and p3D that should be kept the same by the pressure control system, but the pressures p2A, p2B, p2C and p2D (so: the pressures in the reactor feed lines, upstream of the reactors 125A, 125B, 125C, 125D).

(19) Experiments have been conducted to demonstrate the effects obtained by the invention. In the experiments, the system of FIG. 1 was used. The reactors 125A and 125D were provided with inert particles with a size of about 1 m. This caused a pressure drop over the reactors 125A and 125D. The reactors 125B and 125C were empty during the experiments.

(20) The pressure gauges 120A, 120B, 120C, 120D were arranged to measure the reactor inlet pressures of the reactors 125A, 125B, 125C, 125D. The pressure gauges 135A 135B, 135C, 135D were arranged to measure the reactor outlet pressures of the reactors 125A, 125B, 125C, 125D.

(21) A total H2-gas flow of 36.8 Nml/min was fed into the system by fluid source 100. The fluid flow was kept constant over the course of the experiment. The aim was to distribute the flow equally over the four reactors 125A, 125B, 125C, 125D, so about 9.2 Nml/min for each reactor. A flow splitter 105 comprising was passive flow restrictors 110A, 110B, 110C, 110D was used to divide the fluid flow over the four reactors 125A, 125B, 125C, 125D.

(22) In one experiment, the conventional way of reactor flow control was applied. In this experiment, the pressure control system was adapted to keep the pressure reactor outlet pressures (so: just downstream of the reactors; say p3A, p3B, p3C, p3D), equal. In this experiment, the reactor outlet pressures were set at 8 barg.

(23) In the experiment, several parameters were measured. The measurement results are shown in table 1. The Pressure drop over restrictor as is mentioned in table 1 relates to the pressure drop over the restrictors 110A, 110B, 110C, 110D respectively.

(24) TABLE-US-00001 TABLE 1 flow control by controlling pressure downstream of reactors Pressure Pressure Flow Reactor Reactor Restrictor drop drop through Inlet Outlet Inlet over over reactor Reactor Pressure Pressure pressure restrictor reactor (Nml/ no. (barg) (barg) (barg) (barg) (barg) min) 125A 8.44 8 27.62 19.12 0.44 9.08 125B 8.02 8 27.62 19.54 0.02 9.35 125C 7.99 8 27.62 19.57 0.01 9.35 125D 8.66 8 27.62 18.90 0.66 9.02

(25) As is clear from the measurement results in table 1, in the experiment in which the pressure control system is adapted to keep the reactor outlet pressures the same, the flow rate through the reactors varied between 9.02 Nml/min and 9.35 Nml/min, which is a variation of about 3.5%.

(26) In a second experiment, the reactor flow control according to the invention was applied. In this experiment, the pressure control system was adapted to keep the pressure reactor inlet pressures (so: just upstream of the reactors; say p2A, p2B, p2C, p2D), equal. In this experiment, the reactor inlet pressures were set at 8 barg.

(27) In the experiment, several parameters were measured. The measurement results are shown in table 2. The Pressure drop over restrictor as is mentioned in table 2 relates to the pressure drop over the restrictors 110A, 110B, 110C, 110D respectively.

(28) TABLE-US-00002 TABLE 2 flow control by controlling pressure upstream of reactors Pressure Pressure Flow Reactor Reactor Restrictor drop drop through Inlet Outlet Inlet over over reactor Reactor Pressure Pressure pressure restrictor reactor (Nml/ no. (barg) (barg) (barg) (barg) (barg) min) 125A 8 7.52 27.56 19.56 0.48 9.16 125B 8 8 27.56 19.56 0 9.20 125C 8 8.2 27.56 19.56 0.2 9.18 125D 8 7.28 27.56 19.56 0.72 9.20

(29) As is clear from the measurement results in table 2, in the experiment in which the pressure control system is adapted to keep the reactor inlet pressures the same, the flow rate through the reactors varied between 9.16 Nml/min and 9.20 Nml/min, which is a variation of about 0.4%. This is considerably less than when the known method of reactor outlet pressure control is applied.

(30) FIG. 2 shows a first embodiment of a system according to the invention.

(31) The system comprises a plurality of reactor assemblies 30. In FIG. 2, four reactor assemblies 30 are shown, but any number higher than one is possible. Each reactor assembly 30 comprises a flow-through reactor 31 with a reactor inlet 32 and a reactor outlet 33. A reactor feed line 34 extends between a primary fluid source 25 and the reactor inlet 32. The primary fluid source 25 provides a pressurized reaction fluid to the reactors 31, via the reactor feed lines 34. The reactor 31 optionally contains a fixed bed 37.

(32) The reactor assembly 30 further comprises a reactor effluent line 35. The reactor effluent line 35 is connected to the reactor outlet 33. Reaction products that are formed in the reactor leave the reactor as reactor effluent via the reactor outlet 33 and are discharged further via the reactor effluent line 35.

(33) The system shown in FIG. 2 comprises a flow splitter 26 for dividing the fluid flow from the primary fluid source over the reactor assemblies 30. The flow splitter 26 has an inlet 65 and multiple passive flow restrictors 27. The inlet 65 of the flow splitter 26 is connected to the primary fluid source 25. Each passive flow restrictor 27 is in fluid communication with the inlet 65. The flow restrictors 27 are passive flow restrictors, which means that they have a fixed resistance to fluid flow. Each passive flow restrictor 27 has an outlet 66, which outlet 66 is connected to the first end of the reactor feed line 34 of its own dedicated reactor assembly 30. All passive flow restrictors 27 have a substantially equal resistance to fluid flow

(34) The system shown in FIG. 2 further comprises a feed line pressure measurement device. This feed line pressure measurement device is adapted to measure the pressure in the fluid flow in the reactor feed lines 34.

(35) In the system of FIG. 2, the feed line pressure measurement device comprises a plurality of feed line pressure sensors 40. The feed line pressure sensors 40 are arranged such that in each reactor feed line 34 a feed line pressure sensor 40 is provided.

(36) In the system of FIG. 2, in each effluent line an individually controllable backpressure regulator 50 is provided, said backpressure regulator 50 being adapted to regulate the pressure in each reactor effluent line 35 individually.

(37) Furthermore, in the system of FIG. 2, a pressure control arrangement 45 is provided. The pressure control arrangement 45 is linked to the feed line pressure measurement device and to the backpressure regulators 50. More in particular, the pressure control arrangement 45 is linked to the feed line pressure measurement sensors 40 and to the backpressure regulators 50. The pressure sensors 40 provide a measurement data signal to the pressure control arrangement 45 via links 41. The backpressure controllers receive a control signal from the pressure control arrangement 45 via links 42.

(38) The pressure control arrangement 45 comprises an input device 46. The input device 46 allows to input at least a feed line pressure setpoint into the pressure control arrangement 45. This feed line pressure setpoint represents a desired feed line pressure. The desired feed line pressure is the same for all reactor assemblies 30.

(39) The pressure control arrangement 45 is adapted and/or programmed to individually control the backpressure regulators 50 such that for each reactor assembly 30 the pressure measured in the reactor feed line 34 by the feed line pressure measurement device is compared to said feed line pressure setpoint. In case of a difference between the measured feed line pressure and the feed line pressure setpoint, the corresponding backpressure regulator 50 is adjusted such that the feed line pressures are substantially the same in all reactor assemblies 30.

(40) When the feed line pressures as measured by the pressure sensors 40 are all the same, the pressure drop between the primary fluid source 25 and the outlet 66 of each flow restrictor of the flow splitter 26 is the same. When the pressure drop between the primary fluid source 25 and the outlet 66 of each flow restrictor of the flow splitter 26 is the same, the flow rates in the reactor feed lines 34 of all reactor assemblies 30 are the same. Therewith, the fluid coming from the primary fluid source 25 is apportioned equally over the reactor assemblies 30, and therewith over the flow-through reactors 31.

(41) This is the desired situation in the system according to the invention. If somehow the feed line pressure in one or more of the reactor feed lines 34 deviates from the desired feed line pressure, the pressure control arrangement 45 will act by adjusting the setting of the backpressure controller or backpressure controllers 50 in the reactor assembly or reactor assemblies 30 in which the deviating feed line pressure occurs such that the feed line pressure in that reactor assembly becomes (substantially or exactly) the same again as the feed line pressure setpoint. Therewith, the feed line pressure also becomes (substantially or exactly) the same as the feed line pressure in the other reactor assemblies.

(42) Such a deviation in desired feed line pressure can for example occur when a different pressure drop occurs over one or more of the reactors 31. This can occur right from the start of the reaction, but it can also happen over time, during an experiment or production run. This can for example be caused by a filter or fixed bed slowly becoming a bit clogged up. The system according to the invention prevents that such a situation would influence the flow rates of the fluid to the reactors 31 and/or the apportionment of the fluid over the reactors 31.

(43) In a situation when the pressure drop over one or more reactors 31 is different from the pressure drop over other reactors 31, in the system according to the invention the backpressure regulators 50 associated with those reactors 31 that have a different pressure drop will have a different setting from the backpressure regulators 50 that associated with the other reactors 31. For example, assume that the pressure at the primary fluid source is 15 bar, and the desired feed line pressure is 10 bar. The feed line pressure setpoint as entered into the pressure control arrangement 45 will be then be 10 bar.

(44) Assume that in that situation, for example, the pressure drop over all four reactors is 0.5 bar over each of the reactors 31 at the start of the experiment or production run. The backpressure regulators will then all be adjusted at 9.5 bar.

(45) Assume now that during the experiment or production run, the fixed bed 37, of example a glass frit, of one reactor 31 will start to clog up somewhat. As a consequence of that, the pressure drop over that reactor will for example increase from 0.5 bar to 0.8 bar. Initially, this will lead to a deviation in the feed line pressure in the feed line 34 connected to this particular reactor, for example from 10 bar to 10.3 bar. As a consequence, this particular reactor will receive less fluid form the primary fluid source than the other reactors, therewith disturbing the equal distribution of the fluid flow from the primary fluid source 25.

(46) The pressure sensor 40 that measures the feed line pressure in this particular feed line 34 will measure this deviating feed line pressure. Via link 41, the information about the deviating feed line pressure will reach the pressure control arrangement 45. The pressure control arrangement 45 will detect the deviation from the desired feed line pressure and will take action: it will adjust the setting of the backpressure controller 50 that is associated with the reactor 31 with the different pressure drop to 9.2 bar. As a consequence, the feed line pressure will return to 10 bar for that particular reactor assembly, and the fluid flow from the primary fluid source is again apportioned equally over all reactors 31.

(47) Optionally, a diluent line 36 is provided in the system according to FIG. 2. This diluent line 36 can be used to add a diluent to the reactor effluent. It can alternatively be used for purging. In the embodiment of FIG. 2, the diluent line 36 is connected to the reactor effluent line 35 downstream of the reactor outlet 33 and upstream of the backpressure regulator 50. However, alternative arrangements are possible, for example, in which the diluent line 36 is connected to the reactor effluent line 35 downstream of the backpressure regulator 50 or in which the diluent line 36 is connected to the reactor 31, adjacent to the reactor outlet 33 or at least between the fixed bed 37 (if present) and the reactor outlet 33.

(48) FIG. 3 shows a second embodiment of a system according to the invention. This embodiment is different from the embodiment of FIG. 2 with respect to the feed line pressure measurement device. In the other components and in its functioning, the embodiment of FIG. 3 is the same as the embodiment of FIG. 2.

(49) In the embodiment of FIG. 3, the feed line pressure measurement device comprises a single feed line pressure sensor 40, instead of multiple feed line pressure sensors as shown in FIG. 2. Furthermore, in the embodiment of FIG. 3, each reactor feed line 34 is provided with a branch line 71. Each branch line 71 has a first end that is connected to its associated feed line 34, and a second end, that is connected to an inlet of dead end selection valve 70.

(50) The dead end selection valve has multiple inlets and one outlet. The outlet is connected to the single feed line pressure sensor 40.

(51) The dead end selection valve 70 further comprises a valve housing and a valve body inside said valve housing. The valve body allows to connect one inlet channel with the outlet channel. The other inlet channels are dead ends. The valve body is moveable inside the valve housing such that sequentially, one after the other, each inlet channel can be brought into fluid communication with the outlet channel. There is never more than one inlet channel in fluid communication with the outlet channel of the dead end selection valve 70. This way, sequentially, each inlet channel can be brought into fluid communication with the outlet channel.

(52) The reactor feed lines 34 are connected to the inlet channels of the dead end selection valve 70 via the branch lines 71. The feed line pressure sensor 40 is connected to the outlet channel of the dead end selection valve 70. With this arrangement, the feed line pressure sensor 40 can measure the pressure in one reactor feed line 34 after the other, so in a sequential way.

(53) In particular in situations where pressure changes are rather gradual this setup of the feed line pressure measurement device offers a good alternative for the feed line pressure measurement device as shown in FIG. 2.

(54) Optionally, a diluent line 36 is provided in the system according to FIG. 3. This diluent line 36 can be used to add a diluent to the reactor effluent. It can alternatively be used for purging. In the embodiment of FIG. 3, the diluent line 36 is connected to the reactor 31, adjacent to the reactor outlet 33 or at least between the optional fixed bed 37 and the reactor outlet 33.

(55) However, alternative arrangements are possible, for example, in which the diluent line 36 is connected to the reactor effluent line 35 downstream of the backpressure regulator 50 or in which the diluent line 36 is connected to the reactor effluent line 35 downstream of the reactor outlet 33 and upstream of the backpressure regulator 50.

(56) FIG. 4 shows a possible embodiment of a backpressure regulator 50 that can be used in the system and method according to the invention.

(57) The backpressure regulator 50 of FIG. 4 comprises a flow channel 2. The fluid flow of which the pressure is to be controlled passes through this flow channel 2 as indicated by the arrows in FIG. 4. The flow channel 2 has a cross sectional area indicated by arrows A in FIG. 4. Flow channel 2 can be connected to or arranged in a reactor effluent line 35 of a reactor assembly 30 of the system according to the invention.

(58) The backpressure regulator 50 of FIG. 4 further comprises a movable valve member 3. The moveable valve member 3 is adapted to control the size of the cross sectional area of the flow channel 2. This has the effect that the pressure of the fluid flow in the flow channel 2 is controlled. In the embodiment of FIG. 4, the moveable member 3 is a membrane that forms part of the wall of the flow channel 2. In this case, the membrane is in the form of a tube.

(59) The backpressure regulator 50 of FIG. 4 further comprises a valve actuator. The valve actuator is adapted to control the position of the valve member 3. The valve actuator comprises a control chamber 4. In this control chamber 4, a fluid under a reference pressure is present. This fluid engages a pressure surface 5 of the valve member 3 for exerting a control force thereon in order to influence the cross sectional area of the flow channel 2. In the embodiment of FIG. 4, the pressure surface 5 is the outside of the wall of the tube-shaped membrane. The fluid in the control chamber 4 can for example squeeze the tube-shaped membrane to reduce the cross sectional area of the flow channel 2, making the pressure in the flow channel 2 increase.

(60) The backpressure regulator 50 of FIG. 4 further comprises a reference pressure controller 10. This reference pressure controller is adapted to control the reference pressure in the control chamber 4.

(61) There are many alternatives for the reference pressure controller. If space allows, a conventional pressure controller may be used as a reference pressure controller. However, in the backpressure controller of FIG. 4, a special kind of reference pressure controller is used. This reference pressure controller is in particular suitable for use in high throughput experimentation and production of compounds using parallel microreactors, as it allows accurate and fast control of the reference pressure, and therewith of the feed line pressure, and it requires only little space.

(62) This reference pressure controller 10 as shown in FIG. 4 comprises a first restrictor channel 11. The first restrictor channel 11 has an inlet 12 and an outlet 13. The reference pressure controller 10 further comprises a second restrictor channel 14. The second restrictor channel 14 has an inlet 15 and an outlet 16.

(63) Furthermore, a fluid passage 17 is provided. This fluid passage 17 extends between the outlet 13 of the first restrictor channel 11 and the inlet 15 of the second restrictor channel 14. The fluid passage 17 allows fluid communication between the first restrictor channel 11 and the second restrictor channel 14. Depending on the specific embodiment, the fluid passage 17 can be very short (for example if only little space is available) or rather long (for example to allow the pressure fluid to change temperature back to the initial temperature after being heated or cooled in the first restrictor channel).

(64) A pressure control fluid source (not shown in FIG. 2) is provided for providing a flow of a pressure control fluid through the first restrictor channel 11, the fluid passage 17 and the second restrictor channel 14, as indicated by the arrows in FIG. 2. The pressure control fluid can be a gas or a liquid. For example, nitrogen gas is a suitable pressure control fluid.

(65) The flow of pressure control fluid has an entrance pressure at the inlet 12 of the first restrictor channel 11 and an exit pressure at the outlet 16 of the second restrictor channel 14. As there is a flow of pressure control fluid from the inlet 12 of the first restrictor channel 11 to the outlet 16 of the second restrictor channel 14, the entrance pressure is higher than the exit pressure.

(66) The flow of pressure control fluid experiences a first pressure drop p1 over the first restrictor channel 11 and a second pressure drop p2 over the second restrictor channel 14.

(67) The reference pressure controller 10 further comprises a connector 19 that connects the fluid passage 17 to the control chamber 4 of the valve actuator. The connector 19 is in fluid communication with the control chamber 4. The connector 19 can for example comprise a channel and/or a connection element such as a snap-fit connection element or a threaded connection element. The connector 19 could be welded or soldered to control chamber 4. The connector 19 can be permanently fixed to the control chamber 4 or it can be mounted in a detachable way.

(68) The pressure control fluid has an intermediate pressure at the connector 17 which is lower than the entrance pressure but higher than the exit pressure. The value of the intermediate pressure is determined by the ratio between the first pressure drop p1 and the second pressure drop p2. For example, the resistance to fluid flow of the first restrictor channel 11 is the same as the resistance to fluid flow of the second restrictor channel 14, the entrance pressure at the inlet 12 of the first restrictor channel 11 is 150 bar and the exit pressure at the outlet 16 of the second restrictor channel 15 is 100 bar, the intermediate pressure will be 125 bar.

(69) The intermediate pressure corresponds to the pressure in the control chamber 4.

(70) The reference pressure controller 10 further comprises a controllable thermal device 20. Thermal device 20 is shown only schematically in FIG. 4. The thermal device 20 can be realized in many different ways: comprising a Peltier element, comprising electric heat tracing, comprising a pair of electrodes with a voltage thereon, comprising a system for circulating a thermal fluid for heating and/or cooling, comprising a housing for accommodating the first or second restrictor channel, the temperature of the interior of the housing being controllable.

(71) The thermal device 20 is adapted to heat and/or cool the first restrictor channel 11 and/or the second restrictor channel 14. The thermal device can arranged and adapted to just heat and/or cool the first restrictor channel 11. Alternatively, the thermal device may be arranged and adapted to heat and/or cool just the second restrictor channel 14. Alternatively, the thermal device 20 may be arranged and adapted to heat and/or cool both the first restrictor channel 11 and the second restrictor channel 14.

(72) Changing the temperature of a restrictor channel 11, 14 makes that the temperature of the pressure control fluid in that restrictor 11,14 also changes. This results in a change in pressure drop over the restrictor channel 11,14 of which the temperature has been changed.

(73) Therewith, the thermal device 20 can be used to influence the ratio between the first pressure drop p1 and the second pressure drop p2, and therewith to change the intermediate pressure and the pressure in the pressure control chamber 4.

(74) For example, initially the resistance to fluid flow of the first restrictor channel 11 is the same as the resistance to fluid flow of the second restrictor channel 14, the entrance pressure at the inlet 12 of the first restrictor channel 11 is 150 bar and the exit pressure at the outlet 16 of the second restrictor channel 15 is 100 bar, the intermediate pressure will be 125 bar.

(75) For example, nitrogen gas is used as a pressure control fluid. And for example, the thermal device 20 is used to heat the first restrictor channel 11. No heating or cooling is applied to the second flow restrictor channel 14. Due to the heating of the first restrictor channel 11, the first pressure drop p1 that occurs over the first restrictor channel 11 increases, while the second pressure drop p2 over the second restrictor channel 14 does not change or at least does not change substantially. In general, the volume of fluid passing through the restrictor channels is so small that the pressure control fluid has cooled again when it passes through the second restrictor channel 14, so the resistance to fluid flow of the second restrictor channel 14 remains the same.

(76) If not the first restrictor channel 11 but (only) the second restrictor channel 14 is heated and/or cooled is by the thermal device 20, only the second pressure drop p2 will change, and not the first pressure drop p1 over the first restrictor channel 11.

(77) The increase in the first pressure drop p1 while the second pressure drop remains substantially the same results in a decrease of the intermediate pressure because the ratio between the first pressure drop p1 and the second pressure drop p2 has changed. Therewith, the corresponding pressure in the control chamber 4 has also decreased, for example to 122 bar.

(78) With the reference pressure controller as used in the backpressure regulator 50 according to the FIG. 4, it is possible to continuously vary the reference pressure over a certain pressure range.

(79) The thermal device 20 comprises a thermal controller for controlling the thermal output of the thermal device 20, so the reference pressure can be controlled actively.

(80) The reference pressure controller as shown in FIG. 4 comprises a pressure control fluid reservoir 18. The pressure control fluid reservoir 18 is arranged upstream of and in fluid communication with the inlet 12 of the first restrictor channel 11.

(81) The pressure control fluid reservoir 18 is adapted to contain pressurized pressure control fluid. The pressure in the pressure control fluid reservoir 18 is (somewhat) higher than the entrance pressure at the inlet 12 of the first restrictor channel 11, so that a flow of pressure control fluid is established from the pressure control fluid reservoir 18, via the first restrictor channel 11, the fluid passage 13 and the second restrictor channel 14 to the outlet 16 of the second restrictor channel 14. From there, the pressure control fluid may flow to a collection reservoir or it can be transferred to waste (not shown). Or it can be transferred back to the pressure control fluid reservoir, for example by a return line 23 and a pump 24, as is shown in FIG. 4.

(82) The reference pressure controller as shown in FIG. 4 comprises a return line 23 that extends from the outlet 16 of the second restrictor channel 14 to the inlet 12 of the first restrictor channel 11. Furthermore, a pump 24 is present to provide circulation of the pressure control fluid through the first restrictor 11, the fluid passage 17, the second restrictor 14 and the return line 23. The presence of the pressure control fluid reservoir 18 helps to level out any pressure waves in the system that may occur due to the action of the pump 24. In an alternative embodiment (not shown) a pressure control fluid reservoir 18 may be present between the outlet 16 of the second restrictor channel 14 and the pump 24, as an alternative or in addition to the pressure reservoir as shown in FIG. 4.

(83) The pressure control fluid reservoir 18, the return line 23 and the pump 24 are optional features. It is possible that the reference pressure controller 10 does not comprise any of these three features, and that the flow of pressure control fluid through the first restrictor channel 11 and the second restrictor channel 14 is realized in a different manner.

(84) Alternatively, it is possible that the reference pressure controller 10 comprises pressure control fluid reservoir 18, but not the return line 23 and the pump 24. The pressure control fluid then flows from the pressure control fluid reservoir 18 via the first and second restrictor channel 11,14 for example to a collection reservoir or it can be transferred to waste.

(85) In another alternative embodiment, just the return lie 23 and the pump 24 are present, and not the pressure control fluid reservoir 18.