Method for operating a descending moving bed reactor with flowable granular material

Abstract

A method can be used for operating a descending moving bed reactor with flowable granular material. The method involves: (i) filling an upper lock-hopper with granular material and/or emptying a lower lock-hopper, (ii) purging the lock-hoppers with purging gas, and (iii) filling the reaction chamber containing a descending moving bed from the upper lock-hopper and/or emptying the reaction chamber into the lower lock-hopper. The pressure equalization between the reaction chamber and lock-hopper is achieved with product gas. The method then involves: (iv) optionally, relieving the lock-hoppers and conveying the product gas flow into the product line, and (v) purging the lock-hoppers with purging gas.

Claims

1-15. (canceled)

16: A reactor, comprising: a carrier storage hopper to deliver feed granular material to at least one upper lock-hopper, the at least one upper lock-hopper comprising a first inlet shut-off facility and a first outlet shut-off facility, an upper granular material feeder connected from the at least one upper lock-hopper to a reaction chamber, the reaction chamber comprising a reaction section and, optionally, at least one upper carrier hopper, at least one lower product hopper, and additional facilities for a granular material recycle, a lower granular material feeder connected from the reaction chamber to at least one lower lock-hopper, the at least one lower lock-hopper comprising a second inlet shut-off facility and a second outlet shut-off facility, a solid product collection hopper, a recirculation line that is outside the reaction chamber, in fluid communication with the at least one upper lock-hopper, the at least one lower lock-hopper, and a purge gas storage tank permitting circulation of purge gas from the purge gas storage tank to the at least one upper lock-hopper and/or the at least one lower lock-hopper, and back to the purge gas storage tank, at least one gas analyzer that is connected to a control valve for concentration-controlled gas discharge from a purge gas circuit, a product line outside the reaction chamber in fluid communication with the at least one upper lock-hopper, the at least one lower lock-hopper, and a main product line that connects a gas outlet of the reaction chamber with downstream units, and the purge gas storage tank that is connected to the recirculation line.

17: A method for operating a descending bed in the reactor according to claim 16 with flowable granular material, the method comprising: in the at least one upper lock-hopper: (i) filling the at least one upper lock-hopper with granular material, (ii) flushing the at least one upper lock-hopper with the purge gas and recirculating at least part of the purge gas in the purge gas circuit fed from the purge gas storage tank and recirculated to the purge gas storage tank, wherein (ii-a) a first effluent gas comprising a high concentration of oxygen is discharged, and (ii-b) a first purge gas comprising a low concentration of oxygen gas is recirculated in the purge gas circuit fed from the purge gas storage tank, wherein the concentration of oxygen is detected by the at least one gas analyzer, (iii) filling the reaction chamber, comprising a descending, pre-existing moving bed, with the granular material from the at least one upper lock-hopper, wherein a pressure equalization between the reaction chamber and the at least one upper lock-hopper is achieved with gas taken from a head space of the reactor chamber, (iv) optionally, relieving pressure of the at least one upper lock-hopper and conveying a product gas flow from the at least one upper lock-hopper into the main product line that connects the gas outlet of the reaction chamber with downstream units, and (v) flushing the at least one upper lock-hopper with the purge gas and recirculating at least part of the purge gas in the purge gas circuit fed from the purge gas storage tank and recirculated to the purge gas storage tank, and flushing the at least one lock-hopper with purge gas into the product line or discharging an effluent stream; and in the at least one lower lock-hopper: (i) emptying the granular material from the at least one lower lock-hopper, (ii) flushing the at least one lower lock-hopper with purge gas and recirculating at least part of the purge gas in the purge gas circuit fed from the purge gas storage tank and recirculated to the purge gas storage tank, wherein (iia) a second effluent gas comprising a high concentration of oxygen is discharged, and (iib) a second purge gas comprising a low concentration of oxygen gas is recirculated in the purge gas circuit fed from the purge gas storage tank, wherein the concentration of oxygen is detected by the at least one gas analyzer, (iii) emptying the reaction chamber into the at least one lower lock-hopper, wherein the pressure equalization between the reaction chamber and the at least one lower lock-hopper is achieved with the gas taken from the head space of the reactor chamber, (iv) optionally, relieving pressure of the at least one lower lock-hopper and conveying the product gas flow from the at least one lower lock-hopper into the main product line that connects the gas outlet of the reaction chamber with downstream units, and (v) flushing the at least one lower lock-hopper with purge gas and recirculating at least part of the purge gas in the purge gas circuit fed from the purge gas storage tank and recirculated to the purge gas storage tank, and flushing the at least one lock-hopper with purge gas into the product line or discharging the effluent stream; wherein (i) to (v) in the at least one upper lock-hopper and in the at least one lower lock-hopper are conducted synchronously or offset to each other in time.

18: The method according to claim 17, wherein a cycle period of one operation cycle of the at least one upper lock-hopper is equal to one tenth to ten cycle periods of an operation cycle of the at least one lower lock-hopper.

19: The method according to claim 17, wherein in the at least one upper lock-hopper and the at least one lower lock-hopper, a mode of operation is switched from (ii-a) to (ii-b) as an oxygen concentration in the purge gas circuit falls below 1 vol % O.sub.2 to 20 vol % O.sub.2.

20: The method according to claim 17, wherein the reaction chamber comprises the reaction section and a throughput of the granular material through the reaction section is 0.1 kg/min to 10,000 kg/min.

21: The method according to claim 17, wherein an absolute pressure of the reaction chamber is 0.1 bar to 100 bar.

22: The method according to claim 17, wherein a concentration of oxygen in the purge gas storage tank is in a range of 0.1 vol % to 10 vol %.

23: The method according to claim 17, wherein in the at least one upper lock-hopper and the at least one lower lock-hopper, a gas volume is exchanged 2 to 20 times in (ii) and optionally (iv).

24: The method according to claim 17, wherein in the at least one upper lock-hopper and the at least one lower lock-hopper, (v) comprises (v-a) and (v-b): (v-a) flushing a purge gas comprising a high concentration of product gas into the product line, and (v-b) recirculating a purge gas comprising a low concentration of product gas in the purge gas circuit fed from the purge gas storage tank, wherein a concentration of product gas is detected by a gas analyzer.

25: The method according to claim 24, wherein a mode of operation is switched from (v-a) to (v-b) as a hydrogen concentration in the product line falls below 0.2 vol % to 4 vol %.

26: The method according to claim 17, wherein the reaction chamber comprises at least one upper carrier hopper and at least one lower product hopper connected to the reaction section, and wherein part of the granular material is recirculated from the at least one lower product hopper to the at least one upper carrier hopper.

27: The method according to claim 17, wherein the at least one upper lock-hopper consists of one upper lock-hopper and the at least one lower lock-hopper consists of two lower lock-hoppers, wherein the two lower lock-hoppers are connected in parallel.

28: The method according to claim 17, wherein the reaction chamber comprises a descending moving bed.

29: The method according to claim 17, wherein an endothermic reaction is operated in the reactor chamber.

30: The method according to claim 28, wherein a gas feed is passed countercurrent to the descending moving bed.

Description

DESCRIPTION OF THE FIGURES

[0228]

TABLE-US-00001 10 Reaction chamber 101  Reaction section (descending moving bed reactor) 102  Upper carrier hopper 103  Lower product hopper 104  Granular material feeder to reaction section 105  Granular material feeder from reaction section 106  Facility (conveyor) for internal granular material recycle in reaction chamber 20 Upper lock-hopper for carrier feeding to the reaction chamber 21 Carrier storage hopper 22 Shutoff device in the line from upper lock-hopper to reaction chamber 23 Shutoff device in the line from carrier storage hopper to the upper lock-hopper 24 Granular material feeder from the upper lock-hopper to reaction chamber 30 Lower lock-hopper for product withdrawal from the reaction chamber 31 Solid product collection hopper 32 Shutoff device in the line from reaction chamber to lower lock-hopper 33 Shutoff device in the line from lower lock-hopper to product collection hopper 34 Product conveyor from reaction chamber to lower lock-hopper 40 Sieve device 41 Packaging device 50 Purge gas storage tank   51a, b Switch valve in the inlet line from gas storage tank to the upper/lower lock-hopper   52a, b Switch valve in the equalization line between reaction chamber and the upper/lower lock-hopper   53a, b Dust filter in the equalization line between reaction chamber and the upper/lower lock-hopper 55 Exhaust gas aftertreatment unit 60 Recirculation pump in the recirculation line from the lock-hoppers to the gas storage tank 61 Dust filter in the recirculation line from the lock-hoppers to the gas storage tank 62 Control valve for pressure controlled purge gas addition to the gas storage tank 63 Pressure transmitter 64 Shutoff device in the recirculation line from the lock-hopper to the purge gas tank 65 Gas analyzer in the recirculation line from the lock-hopper to the purge gas tank 66 Shutoff device in the connecting lines between lock-hoppers and exhaust after-treatment unit 67 Gas analyzer in the connection line between lock-hoppers and product line 68 Shutoff device in the connection line between lock-hoppers and product line 70 Compressor for charging gas to the product line   71a, b Switch valve in the line from the upper/lower lock-hopper to purge gas circuit 201  Recirculation line in the purge gas circuit  202a, b Feed line in the purge gas circuit connecting the gas storage tank to the upper/lower lock-hopper  203a, b Equilization line connecting the reaction chamber with the upper/lower lock-hopper 205  Gas feed line 206  Gas product line 206a Main gas product line coming off the reactor 206b Secondary product lines connectig the lock-hoppres with the main gas product line

[0229] FIG. 1: Filling and emptying of the lock-hoppers.

[0230] The reaction chamber is under pressure. The solid slide valves (22, 32) between the reaction chamber (10) and the lock-hoppers (20, 30) are closed. The lock-hoppers are pressure relieved and opened to the outside so that solids are filled in the upper lock-hopper (20) and emptied from the lower lock-hopper (30). The valves in the purge gas circuit (51a,b) and (71a,b) are closed.

[0231] FIG. 2: Purging of the lock-hoppers.

[0232] Both solid slide valves of the lock-hoppers are closed. The valves of the purge gas circuit (51a,b) and (71a,b) are open and the lock-hoppers are purged. The purge gas is recycled by circulation pumps (60). A partial flow of the purge gas is discharged in a concentration-controlled manner via valve (65, 66) and replaced by fresh purge gas in a pressure-controlled manner via valve (62, 63).

[0233] FIG. 3: Filling and emptying of the reaction chamber.

[0234] The valves of the purge gas circuit (51a,b) and (71a,b) are closed. The solid slide valves between the lock-hoppers and the reaction chamber (22, 32) are open and the reaction chamber is filled with solids from the at least one upper lock-hopper and the reaction chamber is emptied into the lower lock-hopper. The valves (52a, 52b) of the equalization gas line are open and the lock-hoppers are filled with reaction gas.

[0235] FIG. 4: Relaxing of lock-hoppers and conveying of the product gas of the lock-hoppers into the product line.

[0236] The switch valves (71a, 71b) in the purge gas circuit are open. The shutoff valve in the connection to the production line (68) is open. The purge gas is conveyed to the product line by a compressor (70).

[0237] FIG. 5: Purging of the lock-hoppers.

[0238] The solid slide valves of the upper lock-hoppers (22, 23) and of the lower lock-hoppers (32, 33) are closed. The valves of the purge gas circuit (51a,b) and (71a,b) are open and the lock-hoppers are purged. The purge gas is recycled by circulation pumps (60). A partial flow of the purge gas is discharged in a concentration-controlled manner to the exhaust gas line (65, 66) or to the product line (67, 68) and replaced by fresh purge gas in a pressure-controlled manner via valve (62, 63).

[0239] FIG. 6: Configuration with serial arrangement of the upper lock-hopper (20) with the upper carrier hopper (102) and of the upper lock-hopper (20) with the lower product hopper (103).

[0240] FIG. 7: Configuration with parallel arrangement of the upper lock-hopper (20) with the upper carrier hopper (102) and of the upper lock-hopper (20) with the lower product hopper (103).

[0241] FIG. 8: Configuration with a pair of lower lock-hoppers (30a,b), omitting the storage hoppers inside the reaction chamber (100).

[0242] FIG. 9: Activity pattern of the flow controllers connected to the upper lock-hopper

[0243] FIG. 10: Activity pattern of the flow controllers connected to the lower lock-hopper

[0244] Key FIG. 9 and FIG. 10: [0245] □: valve closed [0246] .square-solid.: valve open [0247] 1: valve open to recirculation loop [0248] 2: valve open to product line

[0249] FIG. 11: Sequence control of the configuration according to FIG. 6 in a synchronous operation of the upper and the lower lock-hopper.

[0250] FIG. 12: Sequence control of the configuration according to FIG. 6 in an asynchronous operation of the upper and the lower lock-hopper.

[0251] FIG. 13: Sequence control of the configuration according to FIG. 7 in a synchronous operation of the upper and the lower lock-hopper.

[0252] FIG. 14: Sequence control of the configuration according to FIG. 7 in an asynchronous operation of the upper and the lower lock-hopper.

[0253] FIG. 15: Sequence control of the configuration according to FIG. 8 with a pair of lower lock-hoppers activated in an alternating sequence.

[0254] Key FIGS. 11-15 [0255] 1 to 5: Stages of the operation cycle of the upper and the lower lock-hopper [0256] □: inactive metering feeder of granular material [0257] .square-solid.: active metering feeder of granular material

EXAMPLES

Reference Example (Following State of the Art CN 106 893 611 A)

[0258] Methane pyrolysis in a moving bed reactor is considered. The absolute pressure in the reaction chamber is 10 bar. The production rate of the reactor is 10000 (Nm3 H2)/h. The volumetric gas feed rate is about 31000 Nm3/h. The reactor is filled with 60 m.sup.3 of a granular coke carrier. The volumetric feed rate of the solid carrier is 30 m.sup.3/h. The volumetric capacity of the upper and the lower lock-hopper is 10 m.sup.3 each. The lock-hoppers are filled to a maximum filling level of 80% of their total volume. The carrier storage hopper and the product collection hopper are exposed to the atmosphere. In the state of the art following CN 106 893 611 A the purge gas is utilized as well for inertizing the lock-hoppers as for pressurizing the lock-hoppers. Inertizing means that after purging the lock-hoppers the residual volume ratio of oxygen and the residual volume ratio of hydrogen is lower than 1%. Pressurizing means that the pressure of the lock-hoppers is raised up to the pressure of the reaction camber, i.e. 10 bar absolute pressure. Following the state of the art disclosed in CN 106 893 611 A the exhaust gas streams of the lock-hoppers are not recirculated. Inertizing the lock-hoppers requires 860 Nm3/h of the purging gas nitrogen. Pressurizing the lock-hoppers requires 550 Nm3/h of nitrogen. About 550 Nm3/h of nitrogen is mixed with the product stream, leading additional dilution of the produced hydrogen. The volume of the nitrogen that contaminates the product stream is about 5.5% of the volume of the produced hydrogen. About 420 Nm3/h of the product gas is discharged. This is equivalent to a yield loss of hydrogen about 1.2%.

[0259] Example According to Invention:

[0260] Methane pyrolysis in a moving bed reactor is considered. The absolute pressure in the reaction chamber is 10 bar. The production rate of the reactor is 10000 (Nm3/h). The volumetric gas feed rate is about 31000 Nm3/h. The reactor is filled with 60 m3 of a granular coke carrier. The volumetric feed rate of the solid carrier is 30 m3/h. The volumetric capacity of the upper and the lower lock-hopper is 10 m.sup.3 each. The volumetric capacity of the purge gas storage tank is 20 m.sup.3 and the pressure is regulated to 3 bar. The carrier storage hopper and the product collection hopper are exposed to the atmosphere. After feeding the upper lock-hopper respectively emptying the lower lock-hopper the void space of the lock-hoppers contains air. The lock-hoppers are flushed with nitrogen from the purge gas storage tank (step ii). The recycle is activated in a concentration-controlled manner: It is completely closed when the volume ratio of oxygen at the outlet of the lock-hopper is higher than 5% (step ii-a) and it is completely open when the volume ration of oxygen at the outlet of the lock-hopper is less than 4% (step ii-b). Between 4% and 5% the position of the control valve is adjusted proportionally. The discharged amount of gas is replaced by nitrogen fed to the gas storage tank (50). The purge gas consumption is 20 Nm3/h for purging the lock-hoppers to a residual oxygen volume ratio below 1 vol %. During feeding the carrier to the reaction chamber respectively removing solid product from the reaction chamber, the lock-hoppers are filled with almost pure hydrogen at an absolute pressure of 10 bar. Subsequently, the gas hold-up of the lock-hoppers is expanded to 3 bar and conveyed to the product line by means of a compressor (step iv). Following that the lock-hoppers are purged with nitrogen from the gas storage tank (step v). The recycle is activated in a concentration-controlled manner: It is completely closed when the volume ratio of hydrogen at the outlet of the lock-hopper is higher than 3% (step v-a) and it is completely open when the volume ration of hydrogen at the outlet of the lock-hopper is less than 2 vol % (step v-b). Between 2% and 3% the position of the control valve is adjusted proportionally. The discharged amount of gas is replaced by nitrogen fed to the gas storage tank (50). The purge gas consumption is 40 Nm3/h for purging the lock-hoppers to a residual hydrogen volume ratio below 1 vol %. The volume of the nitrogen that contaminates the product stream is about 0.55% of the volume of the produced hydrogen. About 165 Nm3/h of the product gas is discharged. This is equivalent to a yield loss of hydrogen about 0.45%.

[0261] Omitting the purge gas storage tank (50) in the present invention implies that purge gas recirculation (steps ii-b and v-b) will be omitted. Accordingly, the gas purge gas consumption becomes 890 Nm3/h.

[0262] Omitting the compressor for charging gas to the product line (70) in the present invention implies that product gas contained in the lock-hoppers will be discharged during the expansion of the lock-hoppers (step iv will be omitted). Accordingly, the discharged amount of product gas becomes 610 Nm3/h. This is equivalent to a yield loss of hydrogen about 1.5%.

[0263] Comparison:

TABLE-US-00002 Present Invention, Present Present including Invention, Invention, step (iv), but including but omitting omitting steps State of step (iv) step (iv) (ii-b) & (v-b) the art Purge gas consumption for 60 Nm3/h 60 Nm3/h 880 Nm3/h 1410 Nm3/h purging the lock-hoppers to a residual oxygen and hydrogen volume ratio below 1% Purge gas mixed with the 55 Nm3/h 55 Nm3/h 55 Nm3/h 550 Nm3/h product gas Discharged product gas 165 Nm3/h 550 Nm3/h 165 Nm3/h 550 Nm3/h Contamination of product 0.55% 0.55% 0.55% 5.5% stream with purge gas Product yield loss 0.45% 1.5% 0.45% 1.2%