Process and system for biomethanization

Abstract

A method and system for biomethanization, the system comprising: a biomethanization reactor; a heat exchanger connected such that it receives biocatalyst-rich water from the biomethanization reactor via a first fluid line and receives cooling fluid from a cooling fluid source via a second fluid line, and configured to cool the biocatalyst-rich water by heat transfer to the cooling fluid and return the cooled biocatalyst-rich water to the biomethanization reactor via a third fluid line; at least one cooling fluid valve arranged to control the supply of cooling fluid to the heat exchanger; a heating fluid source that can be controllably coupled to the second fluid line or the heat exchanger; at least one heating fluid valve arranged to control the supply of heating fluid to the second fluid line or the heat exchanger.to the heat exchanger; a first temperature sensor configured to monitor the temperature of the biocatalyst-rich water during a start-up process of the biomethanization reactor and to close at least one heating fluid valve when the biocatalyst-rich water has risen to or exceeded a desired or preselected start-up temperature; and a second temperature sensor configured to monitor the temperature of the biocatalyst-rich water during operation of the biomethanization reactor and to maintain the biocatalyst-rich water at a desired or preselected operating temperature or within a desired or preselected operating temperature range during operation of the biomethanization reactor by controlling at least one cooling fluid valve.

Description

Field of invention

[0001] The present invention relates to a method and system for biomethanization, in particular a method and system for heating the biocatalyst therefor. Background of the invention

[0002] Fig. Figure 1 is a schematic representation of a known biomethanization system 10. The system 10 comprises a biomethanization reactor 12, which includes an internal agitator 14, a circulation pump 16, and a cooling device in the form of a first heat exchanger 18. The circulation pump 16 and the first heat exchanger 18 are located in a fluid line 20, so that during normal operation of the reactor 12, they draw biocatalyst-rich water 54X, 56X, 57X from the bottom of the reactor 12, cool it, and return it to the reactor 12 as cooled biocatalyst-rich water 58X, 62X, approximately at the vertical center of the reactor 12. The system 10 can include at least one nutrient feed 22 located downstream of the first heat exchanger 18 and configured to supply the cooled, biocatalyst-rich water 62X before it enters the reactor. The return to reactor 12 is controllable, adding sulfide, ammonium, a 1000X nutrient and a 100X nutrient.(In addition, an antifoam supply 30 is provided in the direction of the head of reactor 12 in order to introduce an antifoam agent directly into reactor 12.

[0003] System 10 also includes a cooling water supply 32 (connected via a first line in the form of a cooling water supply line 33 to an inlet of the first heat exchanger 18) and a cooling water return 34 (connected via a second line in the form of a cooling water return line 35 to an outlet of the first heat exchanger 18). The cooling water supply 32 carries cooling water to the first heat exchanger 18 (so that the first heat exchanger 18 can cool the biocatalyst-rich water 56X, 57X), and the cooling water return 34 carries the heated cooling water out of the first heat exchanger 18. A temperature sensor in the form of a temperature controller 36 serves to monitor the temperature of the cooled biocatalyst-rich water 58X and to control a temperature control valve 38, which is located between the first heat exchanger 18 and the cooling water return 34, as well as between the cooling water supply 32 and the cooling water return 34.The temperature controller 36 is configured to control the temperature control valve 38, regulating the cooling provided by the first heat exchanger 18 and thus maintaining the temperature of the cooled, biocatalyst-rich water 58X at a desired temperature. The temperature control valve 38 is configured to regulate the amount of cooling water bypassing the heat exchanger 18 along the bypass line 31 and increases this amount when the temperature controller 36 detects that the biocatalyst-rich water 58X in the fluid line 20 is lower than desired.

[0004] A heating circuit 40 is provided to facilitate the start-up, as the biocatalyst must first be heated to a temperature suitable for biomethanization without damaging the archaea and microorganisms of the biocatalyst. Therefore, the circuit 40 comprises a start-up circulation pump 42 for circulating a heating medium consisting of a mixture of water and glycol, a start-up heating device 44 for heating the heating medium (which may, for example, be in the form of an electric heating device with a power output of 1 MW, a steam heat source, or recovered exhaust gas heat), and a start-up heat exchanger or secondary heat exchanger 46.The starting heating device 44 is configured or operated in such a way as to heat the heating medium to a temperature suitable for increasing the temperature of the biocatalyst-rich water 57X by heat transfer within the second heat exchanger 46 in order to raise the temperature of the biocatalyst-rich water to an operating temperature (of, for example, about 55 to 60 °C) so that the biocatalyst is not damaged.

[0005] The circuit 40 also includes an expansion tank 48 (which accommodates the expansion and contraction of the fluid in the closed circuit) upstream of the circulation pump 42 and an inlet 50, which introduces the heating medium into the circuit 40 and is located between the expansion tank 48 and the circulation pump 42.

[0006] The initial circulation pump 42 pumps the mixture through the initial heating device 44, which then directs the heated mixture into the second heat exchanger 46. After leaving the second heat exchanger 46, the heating medium returns to the circulation pump 42.

[0007] The second heat exchanger 46 is also arranged in a fluid line 52, which directs biocatalyst-rich water 57X in fluid line 20 (via a flow control valve 54 controlled by a flow controller 56) through the second heat exchanger 46 to a point in fluid line 20 immediately upstream of the at least one nutrient feed 22, thus bypassing the first heat exchanger 18. A further temperature sensor in the form of a temperature controller 58 is located in fluid line 52 downstream of the second heat exchanger 46 and is configured to monitor the temperature of the biocatalyst-rich water leaving the second heat exchanger 46. The further temperature controller 58 is configured to control a further temperature control valve 60. The further temperature control valve 60 is located in the circuit 40 downstream of the second heat exchanger 46 and has an outlet connected to the circulation pump 42.The temperature control valve 60 is also coupled to a second bypass line 62, which can divert the flow of the heating medium from the start heater 44 to bypass the second heat exchanger 46. Thus, the additional temperature controller 58 controls the flow of the heating medium through the second heat exchanger 46 and therefore the temperature of the heating medium by opening and closing the outlets of the additional temperature control valve 60; consequently, the additional temperature controller 58 can control the amount of heat supplied to the biocatalyst-rich water in the fluid line 52.

[0008] Thus, the starting heating device 44 directly heats the heating medium and not the biocatalyst, so that this approach avoids the starting heating device 44 directly heating and possibly damaging the biocatalyst.

[0009] System 10 also includes a reactor level controller 64, a reactor level control valve 66, and an on / off valve 68 for the biocatalyst drain. The on / off valve 68 for the biocatalyst drain has an outlet that forms a drain for the biocatalyst and is controlled to be open during normal operation. The reactor level controller 64 monitors the biocatalyst level in the reactor 12 and responds to the detection of a biocatalyst level above a nominal or operating level by adjusting the reactor level control valve 66 to divert and discharge a portion of the biocatalyst-rich water flow 54X from the reactor 12 as a biocatalyst-rich water drain 55X until the reactor level controller 64 detects that the biocatalyst level has dropped to its nominal level.The reactor level controller 64 then reacts with a further adjustment of the reactor level control valve 66, for example by resetting it to its previous setting.

[0010] System 10 also includes a feed gas stream 10X with feed gas from a booster compressor to reactor 12, a raw product gas stream 11X with raw product gas from reactor 12 for treatment, and a reactor fill stream 12X from a fill pump. The raw product gas stream 11X is monitored by a gas analyzer 69, which is positioned downstream of a foam trap (not shown) to prevent fouling and is configured to detect any power loss of reactor 12.

[0011] System 10 also includes a pressure regulator 70 and a reactor pressure control valve 72. The pressure regulator 70 is configured to monitor the pressure in reactor 12 and to control the reactor pressure control valve 72 to maintain a nominal pressure in reactor 12. The reactor pressure control valve 72 is located in the raw product gas stream 11X and can be controlled by the pressure regulator 70 to maintain the pressure in reactor 12 within a nominal operating range through negative feedback resulting from the production of product gas.

[0012] During startup, the circulation pump 16 circulates the biocatalyst through the fluid line 52, with the flow controller 56 being controlled to open the flow control valve 54 to introduce the biocatalyst into the fluid line 52. Heat exchange takes place in the second heat exchanger 46, where the biocatalyst is heated by heat transfer from the heating medium circulating in the heating circuit 40. Once the reactor temperature is detected to have reached approximately 55–60 °C, the biocatalyst is ready for use, and the flow controller 56 controls the flow control valve 54 to close. Heating up a 25 MW reactor during a cold start can take approximately 3 hours or more.

[0013] Biomethanization is an exothermic reaction process that generates heat. To dissipate this heat and maintain the reactor temperature at 55–60 °C to prevent the biocatalyst from overheating, the cooling system—first heat exchanger 18, cooling water supply 32, cooling water return 34, etc.—is activated. As described above, the hot, biocatalyst-rich water from reactor 12 is returned by the circulation pump 16 to the first heat exchanger 18, which cools the biocatalyst-rich water by transferring heat to the cooling water from the cooling water supply 32. The cooled biocatalyst-rich water 58X, 62X is then returned to reactor 12, and the heated cooling water is discharged to the cooling water return 34.

[0014] It should be noted that if the temperature of the biocatalyst-rich water falls below the required operating range, the second heat exchanger 46 can be used to raise its temperature. This can be supported by reducing or discontinuing the cooling through the first heat exchanger 18, while diverting at least part of the biocatalyst flow (with the control valve 54 under the control of the temperature controller 36, which monitors the temperature of the biocatalyst during normal operation, instead of the flow controller 56) to the second heat exchanger 46, where the biocatalyst can be heated as described above in connection with the start-up.

[0015] One object of the present invention is to mitigate at least one of the disadvantages of known biomethanization systems, such as their size, high energy consumption and complexity. Summary of the invention

[0016] In a first aspect, the invention offers a biomethanization system comprising the following: a biomethanization reactor; a heat exchanger connected in such a way that it receives biocatalyst-rich water from the biomethanization reactor via a first fluid line and receives a cooling fluid (advantageously cooling water or another fluid with high heat capacity or specific heat capacity) from a cooling fluid source via a second fluid line, and is configured to cool the biocatalyst-rich water by transferring heat to the cooling fluid and to return the cooled biocatalyst-rich water to the biomethanization system via a third fluid line; at least one coolant valve arranged to control the supply of coolant to the heat exchanger; a source of heating fluid (e.g. a gas, a liquid or a vapor) that can be controlled to connect to the second fluid line (so that the heating fluid and the cooling fluid can be mixed before or at the entry into the heat exchanger in some embodiments, if desired) or to the heat exchanger (i.e. directly, at an inlet separate from the cooling fluid inlet); at least one heating fluid valve arranged in such a way as to control the supply of the heating fluid to the second fluid line or to the heat exchanger; a first temperature sensor configured to monitor the temperature of the biocatalyst-rich water during a start-up process of the biomethanization reactor and to close at least one heating fluid valve when the biocatalyst-rich water has risen to or exceeded a desired or preselected start-up temperature; and a second temperature sensor configured to monitor the temperature of the biocatalyst-rich water during operation of the biomethanization reactor and to maintain the biocatalyst-rich water at a desired or preselected operating temperature or within a desired or preselected operating temperature range during operation of the biomethanization reactor by controlling at least one cooling fluid valve.

[0017] For example, the desired or operating temperature (e.g., 55 to 60 °C or approximately 60 °C) is typically below the temperature at which the biocatalyst is damaged. For archaea, this is approximately 69 °C. It should also be noted that the heat exchanger can be of any suitable type, such as a conduction heat exchanger or one that relies on a change of state of the heating or cooling fluid (e.g., a heat pump for use with a refrigerant that boils during operation). In some embodiments, the heat exchanger includes a control system that comprises or controls the at least one refrigerant valve.

[0018] It is also pointed out that in embodiments where the heating fluid is a gas, it may be undesirable to mix the heating fluid with the cooling fluid (e.g. water), notwithstanding the fact that such a mixture is considered according to the invention.

[0019] Thus, the biocatalyst is heated using the heating fluid (which in many cases is readily available as a waste stream from another or a separate industrial process), without requiring either the heating circuit or the second bypass fluid line of the prior art. It should be noted that the cooling fluid (or cooling fluid stream) can consist of the same fluid as the heating fluid (or heating fluid stream).

[0020] In one embodiment, the at least one heating fluid valve is controllable to control the flow rate of the heating fluid to the heat exchanger, and / or the at least one cooling fluid valve is controllable to control the flow rate of the cooling fluid to the heat exchanger, thereby allowing the temperature of the cooling fluid and heating fluid mixture to be controlled.

[0021] This means that in an embodiment with "two circuits," the cooling fluid and the heating fluid can be mixed before or upon entering the heat exchanger, so that the temperature of the resulting mixture can be controlled by adjusting the flow rate of the cooling fluid and / or the heating fluid. This allows the heating rate of the biocatalyst-rich water to be controlled. This can be compared to embodiments with "three circuits," in which the cooling fluid and the heating fluid enter and exit the heat exchanger via separate inlets and outlets.

[0022] The first and second temperature sensors can be located in a single location or as a single sensor.

[0023] These sensors (which may be designed as temperature controllers) can advantageously be provided as a single sensor or controller in the flow of biocatalyst-rich water leaving the heat exchanger. This essentially means that the prior art temperature sensor or controller, designed to monitor the flow of biocatalyst-rich water leaving the heat exchanger, can perform two functions: it can be configured to monitor when the flow reaches the operating temperature during a start-up phase and respond by controlling the termination of the start-up phase; and it can monitor when the flow deviates from an operating temperature or temperature range during an operating phase and respond by increasing or decreasing the flow of cooling water accordingly.

[0024] The second temperature sensor is advantageously arranged to monitor the temperature of the biocatalyst-rich water in the third fluid line.

[0025] The starting temperature can be the same as the operating temperature or within the operating temperature range.

[0026] The at least one cooling fluid valve can include a variable control valve arranged to divert cooling fluid from the second fluid line to a cooling fluid return in response to the second temperature sensor during operation of the biomethanization reactor. This allows the second temperature sensor to control the cooling fluid flow to the heat exchanger. In one example, the at least one cooling fluid valve includes another variable control valve arranged in the second fluid line to control the flow of cooling fluid in the second fluid line to the heat exchanger during the start-up process. This second variable control valve responds to the first temperature sensor, allowing the first temperature sensor to control the mixture ratio of cooling fluid and heating fluid introduced into the heat exchanger during the start-up process, and thus the temperature of the mixture.

[0027] The heating fluid can, for example, include hot condensate or hot water.

[0028] In one embodiment, the system comprises a further heat exchanger which can be controllably coupled to the heating fluid source and controllably to the second fluid line, wherein the further heat exchanger is controllable to transfer heat from the heating fluid to the cooling fluid from the second fluid line.

[0029] In a second aspect, the invention provides a method for operating a biomethanization system comprising a biomethanization reactor and a heat exchanger, wherein the method comprises: a start-up phase, comprehensive: Heating of biocatalyst-rich water by introducing biocatalyst-rich water from the biomethanization reactor and a heating fluid (e.g., a gas, a liquid, or a steam) from a heating fluid source into the heat exchanger, so that the biocatalyst-rich water is heated by heat transfer from the heating fluid; Returning the biocatalyst-rich water from the heat exchanger to the biomethanization reactor; Monitoring the temperature of the biocatalyst-rich water leaving the heat exchanger with a first temperature sensor and Terminating the supply of heating fluid to the heat exchanger under the control of the first temperature sensor when the first temperature sensor detects that the temperature of the biocatalyst-rich water has risen to or exceeded a desired or preselected starting temperature; and an operational phase, comprehensive: Cooling the biocatalyst-rich water by supplying biocatalyst-rich water from the biomethanization reactor and a cooling fluid (advantageously cooling water or another fluid with a high heat capacity or specific heat capacity) from a cooling fluid source to the heat exchanger, so that the biocatalyst-rich water is cooled by heat transfer to the cooling fluid; Returning the biocatalyst-rich water from the heat exchanger to the biomethanization reactor; Monitoring the temperature of the biocatalyst-rich water; and Maintaining the temperature of the biocatalyst-rich water under the control of the second temperature sensor at a desired or preselected operating temperature or within a desired or preselected operating temperature range by controlling a flow of the cooling fluid to the heat exchanger.

[0030] It should be noted that the cooling fluid (or cooling fluid stream) can consist of the same fluid as the heating fluid (or heating fluid stream). As mentioned above, in embodiments where the heating fluid is a gas (e.g., a single gas or a gas mixture), mixing the heating fluid with the cooling fluid (e.g., water) is generally undesirable, even if it is possible, particularly in embodiments with a closed cooling water circuit.

[0031] The start-up phase can include pumping the biocatalyst-rich water from the biomethanization reactor into the heat exchanger, for example using a circulation pump.

[0032] In one embodiment, the method includes controlling the temperature of the heating fluid entering the heat exchanger with a portion of the cooling fluid.

[0033] The method may involve providing the first and second temperature sensors in a single location or as a single sensor.

[0034] The method may advantageously include the arrangement of the second temperature sensor to monitor the temperature of the biocatalyst-rich water leaving the heat exchanger.

[0035] The method can include the controllable diversion of cooling fluid to a cooling fluid return during the operating phase in response to the second temperature sensor, thereby enabling the second temperature sensor to control the cooling fluid flow to the heat exchanger. In one example, the method includes controlling the flow of cooling fluid from the cooling fluid source to the heat exchanger during the start-up phase in response to the first temperature sensor, thereby enabling the first temperature sensor to control the ratio of a cooling fluid and heating fluid mixture introduced into the heat exchanger during the start-up phase, and thus the temperature of the mixture.

[0036] In one embodiment, the method includes transferring heat from the heating fluid to the cooling fluid from the second fluid line using a further heat exchanger.

[0037] The heating fluid can, for example, consist of hot condensate or hot water.

[0038] It should be noted that all the various individual features of each of the above-mentioned aspects of the invention and all the various individual features of the embodiments described herein, including the claims, can be combined as needed and desired. Brief description of the drawings

[0039] The invention is explained in more detail below with reference to the drawings. In the following detailed description, the same reference numerals denote the same elements unless otherwise specified.

[0040] The following detailed description describes certain embodiments of the invention in more detail. However, it should be noted that features described only in connection with one of the embodiments are nevertheless intended to be available in connection with or in combination with any other embodiment of the invention, regardless of whether they are described in the detailed description or not, unless such a combination of features would lead to nonsensical results. The following detailed description is not intended to limit the invention in any way to the specific embodiments and combinations of features described therein; rather, the invention is limited and defined exclusively by the accompanying claims. Fig. Figure 1 is a schematic representation of a state-of-the-art biomethanization system; Fig. Figure 2 is a schematic representation of a biomethanization system according to an embodiment of the present invention; Fig. Figure 3 is a flowchart of the start-up process of a biomethanization system according to an embodiment of the present invention; Fig. Figure 4 is a schematic representation of a biomethanization system according to a further embodiment of the present invention; Fig. Figure 5 is a schematic representation of a biomethanization system according to yet another embodiment of the present invention; and Fig. Figure 6 is a schematic representation of a biomethanization system according to yet another embodiment of the present invention. Detailed description

[0041] Fig. Figure 2 is a schematic representation of a biomethanization system 74 according to an embodiment of the present invention. The system 74 comprises many components that it has in common with the system 10 from the prior art, and identical components are designated with the same reference numerals.

[0042] With reference to Fig. 2 System 74 comprises a biomethanization reactor 12 with an internal agitator 14, a circulation pump 16, and a cooling device in the form of a heat exchanger 18. The circulation pump 16 and the heat exchanger 18 are located in a fluid line 20, so that during normal operation of the reactor 12, they draw in biocatalyst-rich water from the bottom of the reactor 12, cool it, and return it to the reactor 12 as cooled biocatalyst-rich water 58X, 62X, approximately at the vertical center of the reactor 12. System 74 includes at least one nutrient feed 22 in the fluid line 20 downstream of the heat exchanger 18 and an antifoam feed 30 towards the top of the reactor 12.

[0043] System 74 comprises a cooling fluid supply in the form of a cooling water supply 32' and a cooling fluid return in the form of a cooling water return 34', which are connected via a first line in the form of a cooling water supply line 33' and a second line in the form of a cooling water return line 35' to an inlet and an outlet of the heat exchanger 18, respectively. The cooling water supply line 33' and the cooling water return line 35' each include on / off valves 76 and 78.

[0044] The cooling water supply 32' carries cooling water to the heat exchanger 18 (so that the heat exchanger 18 can cool the biocatalyst-rich water 56X, 57X), and the cooling water return 34' transports the heated cooling water from the heat exchanger 18. A temperature controller 36' monitors the temperature of the cooled biocatalyst-rich water 58X and is configured to control a variable temperature control valve 38, which is located between the heat exchanger 18 and the cooling water return line 34', as well as between the cooling water supply line 32' and the cooling water return line 34'. The temperature controller 36' is configured to adjust the temperature control valve 38 to control the cooling provided by the heat exchanger 18 and thus maintain the temperature of the cooled biocatalyst-rich water 58X at a desired temperature.

[0045] System 74 comprises a reactor level controller 64, a variable reactor level control valve 66, and an on / off valve 68 for biocatalyst discharge. The on / off valve 68 for biocatalyst discharge has an outlet that forms a drain for the biocatalyst and is controlled to be open during normal operation. The reactor level controller 64 monitors the biocatalyst level in reactor 12 and responds to the detection of a biocatalyst level higher than a nominal or operating level by adjusting the reactor level control valve 66 to divert a portion of the biocatalyst-rich water flow 54X from reactor 12 as biocatalyst-rich water discharge 55X until the reactor level controller 64 detects that the biocatalyst level has been reduced to its nominal level.The reactor level controller 64 then reacts by further adjusting the reactor level control valve 66, for example by returning it to its previous, less open setting.

[0046] As in System 10 in Fig. 1 includes System 74 in Fig. 2. A feed gas stream 10X with feed gas from a booster compressor to reactor 12 (TP-05X), a raw product gas stream 11X with raw product gas from reactor 12 to treatment (TP-06X), and a reactor fill stream 12X from a fill pump (TP-07X). The raw product gas stream 11X is monitored by a gas analyzer 69, which is positioned downstream of a foam trap to prevent fouling (not shown) and is configured to detect any reduction in reactor 12 power. The system 74 includes a pressure regulator 70 and a reactor pressure control valve 72. The pressure regulator 70 is configured to monitor the pressure in reactor 12 and to control the reactor pressure control valve 72 to maintain a nominal pressure in reactor 12.The reactor pressure control valve 72 is located in the raw product gas stream 11X and can be controlled by the pressure regulator 70 to maintain the pressure in the reactor 12 within a nominal operating range due to the production of product gas by means of negative feedback.

[0047] System 74 further comprises a heating fluid source 80 for a heating fluid and a return line 82 for cooled heating fluid. The heating fluid can be in any suitable form, for example, as hot condensate or hot water, such as from another industrial process. In this context, "hot" means a temperature suitable for use as a heating fluid to raise the temperature of the biocatalyst-rich water 57X, which is introduced into the heat exchanger 18 from ambient or stagnant temperature, to the operating temperature (or temperature range) of the reactor (e.g., about 55 °C, 60 °C, or 65 °C) so as not to damage the archaea.

[0048] The return 82 for cooled heating fluid can be a reservoir or an outlet, but - in an alternative arrangement - the return 82 for cooled heating fluid (and also the on / off valve 86) may not form part of the system 74.

[0049] The heating fluid source 80 is connected to the cooling water supply line 33' (i.e., between the cooling water supply 32' and the heat exchanger 18) via a control valve 84 and a heating fluid line 81, and the return line 82 for cooled heating fluid is connected to the cooling water return line 35' between the temperature control valve 38 and the cooling water return line 34' via an on / off valve 86. The temperature controller 36' is additionally configured to control the valve 84. This embodiment can therefore be described as a "dual-loop embodiment" because the cooling water and the heating fluid enter the heat exchanger 18 through the same inlet (where the cooling water and the heating fluid are mixed and exit the heat exchanger 18 through the same outlet), thus forming one loop, while the biocatalyst-rich water circulates through the heat exchanger 18 as a second loop.It should be noted that the cooling water and the heating fluid can be mixed before being introduced into the heat exchanger 18 (e.g. if the heating fluid is water) or can be introduced alternately into the heat exchanger 18.

[0050] It should be noted that in Fig. 2 The temperature controller 36' is shown to be in data communication with the control valves 38 and 84. This does not mean that in this and all other embodiments of the invention such communication via a direct, wired and / or wireless communication channel with the control valves 38, 84 is required – although this is an option. In this and other embodiments of the invention, such communication can be mediated by a control system (not shown) that receives temperature information from the temperature controller 36' and – by wired and / or wireless communication – controls one or more of the control valves 38, 66, 84 and on / off valves 68, 76, 78 of the system 74. Likewise, the control system can receive the output signals of other controllers (e.g., reactor level controller 64, gas analyzer 69, and / or pressure controller 70) and control some or all of the other valves and components (e.g.,Control the circulation pump 16 and / or reactor pressure control valve 72) of system 74.

[0051] System 74 is configured to implement a startup procedure during a startup phase, as schematically shown in flowchart 100 in Fig. 3 is shown. With reference to Fig. 3. When system 74 (and in particular reactor 12) is in a cold or preparatory operating state 102, the control valve 84 and the on / off valves 76, 78, 86 are closed. In step 104, the circulation pump 16 is started so that biocatalyst-rich water 57X flows from reactor 12 into heat exchanger 18 and the temperature controller 36' begins monitoring the temperature of the (heated) biocatalyst-rich water 58X.

[0052] In step 106, the control valve 84 and the on / off valve 86 are opened, allowing heating fluid from the heating fluid source 80 to enter the heat exchanger 18 via the cooling water supply line 33'. In step 108, the heat exchanger 18 heats the biocatalyst-rich water 57X entering the heat exchanger 18 using the heat from the heating fluid, so that the biocatalyst-rich water 58X exiting the heat exchanger 18 is hotter than the biocatalyst-rich water 57X. The heating fluid, which has now cooled slightly due to its flow through the heat exchanger 18, is transported via the cooling water return line 35' to the return line 82 for cooled heating fluid.

[0053] In step 110, the temperature controller 36' determines whether the temperature of the biocatalyst-rich water 58X is the desired operating temperature T. operational (e.g., 65 °C) has been reached (or exceeded). If this is not the case, processing continues in step 108.

[0054] When the temperature controller 36' detects in step 110 that the temperature of the biocatalyst-rich water 58X has reached (or exceeded) the desired operating temperature, the process continues in step 112, where the temperature controller 36' responds by sending a "close" command to the control valve 84 and the on / off valve 86. In step 114, the control valve 84 and the on / off valve 86 respond by closing. At this point, the reactor 12 has reached the desired conditions for the start of the biomethanization process.

[0055] The temperature controller 36' can also throttle the flow of heating fluid from the heating fluid source 80 by controlling the control valve 84. Therefore, if the temperature controller 36' detects an alarm condition in which the temperature of the biocatalyst-rich water 58X is rising too rapidly, indicating that the heating fluid is overheating the biocatalyst-rich water (either due to an excessively high heating fluid temperature or an excessively high rate of temperature rise), the temperature controller 36' can also throttle the flow of heating fluid from the heating fluid source 80 by controlling the control valve 84 to partially close. This allows the system 74 to prevent overheating and damage to the biocatalyst.Similarly, the temperature controller 36' can increase the flow rate of the heating fluid from the heating fluid source 80 by further opening the control valve 84 when the temperature controller 36' determines that the biocatalyst-rich water 57X entering the heat exchanger 18 can be heated more quickly without damaging the biocatalyst.

[0056] Once the desired conditions for the start of the biomethanization process are reached, system 74 controls the on / off valves 76, 78 so that the cooling of the biocatalyst-rich water 57X with cooling water from the cooling water supply 32' can begin (as in connection with system 10 in Fig. 1 described), i.e. the temperature of the biocatalyst-rich water 58X (and thus of the reactor 12) is controlled by the temperature controller 36'.

[0057] Fig. Figure 4 is a schematic representation of a biomethanization system 120 according to a further embodiment of the present invention. The system 120 is largely identical to the system 74 from [reference missing]. Fig. 2, and identical components are designated with the same reference numerals.

[0058] However, system 120 includes a control valve 76' in the cooling water supply line 33' (cf. the on / off valve 76 of system 74 in Fig. 2) The temperature controller 36' is further configured to control the control valve 76'. This allows the temperature controller 36' to introduce a controlled quantity of cooling water from the cooling water supply 32' into the cooling water supply line 33' and thus into the heating fluid from the heating fluid source 80 (which is supplied via the heating fluid line 81) during the start-up process (see figure). Fig. 3) This approach can replace or supplement the temperature control mechanism provided by the control valve 84 under the control of the temperature controller 36'.

[0059] In an alternative arrangement, the return line 82 for cooled heating fluid is not integrated into the system 120 (as is the optional on / off valve 86).

[0060] Fig. Figure 5 is a schematic representation of a biomethanization system 130 according to a further embodiment of the present invention. The system 130 is largely identical to the system 74 from [reference missing]. Fig. 2, and identical components are designated with the same reference numerals. However, system 130 is an embodiment with three circuits: The cooling fluid and the heating fluid are in separate circuits and enter and exit the heat exchanger 18 via separate inlets and outlets. System 130 therefore has three circuit loops that run through the heat exchanger 18: a heating circuit, a cooling circuit for the biomass, and a circuit for the biocatalyst-rich water.

[0061] Referring to Fig. Thus, the heating fluid source 80 can be controlled via a control valve 84 and coupled to the heat exchanger 18 to provide heating fluid during the start-up phase. This configuration differs from that of system 74 in Fig. 2 by feeding the heating fluid directly into the heat exchanger 18 (thus creating a third circuit) and not into the fluid line that connects the cooling water supply 32' to the heat exchanger 18. However, the heat exchanger 18 of this embodiment is essentially identical to the one described in Fig. 4, except that the connection of the two inlet lines is made at or within the heat exchanger 18 of this embodiment, but before the heat exchanger. This can be implemented, for example, by the heat exchanger 18 of this embodiment having an inlet nozzle (not shown) with two connections, so that the inlet nozzle can be connected to both the heating fluid line 81 and the cooling water supply line 33'.

[0062] In system 130, this heating fluid can leave the heat exchanger 18 via a line 132 for cooled heating fluid, which extends from the cooling water return line 35' (see Fig. 2) differs, for example, by the arrangement according to Fig. 4 or, as in Fig. 5, by providing an outlet nozzle (not shown) with two connections, one for the cooling water return line 35' and the other for the cooled heating fluid line 132, and a three-way valve (not shown) which can be controlled to direct the fluid exiting the heat exchanger 18, as required, either into the cooling water return line 35' or into the cooled heating fluid line 132.

[0063] Line 132 for cooled heating fluid transports the cooled heating fluid out of system 130 (e.g., to a return line 82' for cooled heating fluid via an on / off valve 86'). In an alternative arrangement, the on / off valve 86' and the return line 82' for cooled heating fluid are integrated into system 130.

[0064] Fig. Figure 6 is a schematic representation of a biomethanization system 140 according to a further embodiment of the present invention. System 140 is largely identical to system 74 from [reference missing]. Fig. 2, and identical components are designated with the same reference numerals. However, system 140 is a "closed-loop" embodiment that can be switched between a "closed cooling water loop" and a "closed hot water loop". The closed-loop configuration is used to transfer heat indirectly from a heat source (such as hot water, steam, flue gases, or electricity) to the biocatalyst without a significant risk of damaging the biocatalyst.

[0065] System 140 thus avoids the mixing of fluids coming from heating and cooling sources by using cooling fluid to cool the biocatalyst during reactor operation and heating fluid to heat during start-up, with the cooling fluid serving as an intercooler in the closed-loop configuration.

[0066] With reference to Fig.6. The heating fluid from the heating fluid source 80 is controlled by the valve 84 in response to a control signal from a temperature controller 156, which reacts to the temperature in a fluid line 142. The heating fluid is thus directed into a further heat exchanger in the form of a second heat exchanger 146, where it heats the fluid from a closed circuit in a fluid line 144. The cooled heating fluid leaves the second heat exchanger 146 and is directed to the return line 82 for cooled heating fluid. The hot fluid from the closed circuit leaves the second heat exchanger 146 via the fluid line 142, passes through the three-way valve 147, and is then reconnected to the cooling water supply line 33'.

[0067] Fluid line 144 may include an optional on / off valve (not shown) because, when the cold closed circuit is open, stationary fluid is present in the second heat exchanger 146; even if this fluid does not exit the second heat exchanger 146, it may be exposed to the hot components of the closed circuit (e.g., during maintenance of the second heat exchanger 146). This can be avoided by closing this optional on / off valve.

[0068] The three-way valve 147 is configured so that it does not allow bypassing of the second heat exchanger 146 during heating mode and completely bypasses the second heat exchanger 146 during cooling mode. Furthermore, the three-way valve 147 is configured so that it does not allow bypassing of the cooling water supply line 33' to the heat exchanger 18, but as mentioned above, stationary fluid is expected to be present in the second heat exchanger 146.

[0069] Hot fluid from the closed circuit enters the heat exchanger 18 via the cooling water supply line 33'. Here, the biocatalyst fluid of the reactor circuit is heated and returned to the reactor 14 as in the embodiments described above. The cooled fluid from the closed circuit leaves the heat exchanger 18 via the cooling water return line 35', where it mixes with the bypass fluid supplied via the bypass line 31. The three-way valve 38 functions as in other embodiments and regulates the outlet temperature of the heat exchanger 18 during start-up by dividing the flow of the hot fluid from the closed circuit in the cooling water supply line 33' between the main heat exchanger 18 and its bypass, thereby regulating the temperature of the biocatalyst-rich water.

[0070] The cooled fluid of the closed circuit is pumped by the circulation pump 150 to compensate for pressure drops in the closed loop. The circulation pump 150 can also be used in system 140 during normal operation, so that in this embodiment no further such circulation pump is required.

[0071] The pumped fluid of the closed circuit is diverted through the further fluid line 152 by controlling the status of the valves 78 and 154 (in the further fluid line 152), whereby the first valve 78 is closed during operation in the closed circuit and the second valve 154 is open.

[0072] The expansion tank 148 compensates for the expansion and contraction of the fluid in the closed circuit due to temperature changes.

[0073] As soon as the temperature of the biocatalyst fluid, measured by the temperature sensor of the temperature controller 36', reaches the setpoint or the minimum value within the desired range, the temperature controller sensor 156 controls the flow of water in the closed circuit so that the heat exchanger 18 is completely bypassed. This is implemented in a cascade effect by the temperature controller 156 closing the valve 84 and thereby stopping the supply of the heating fluid.

[0074] The resulting temperature increase from the reactions taking place in reactor 14 is detected by the temperature sensor of the temperature controller 36', and the closed system is automatically switched to open cooling mode (a process that can also be controlled manually by an operator).

[0075] The switch to cooling mode includes closing the valve 86 on the return line for cooled heating fluid, deactivating the heating medium control circuit (by the temperature controller 156, which controls the valve 84), changing the position of the three-way valve 147, allowing the fluid to bypass the second heat exchanger 146, closing the valve 154, and opening the valves 78 and 76, effectively restoring an open circuit from the cooling water supply 32' to the cooling water return 34' - identical in operating principle to the arrangements of other embodiments.

[0076] Pump 150 is configured to switch off when a sufficient pressure differential is detected between the cooling water supply 32' and the cooling water return 34'. It should be noted that pump 150 can also serve as a circulation pump for open-loop operation if required, as it can replace any other pump in the cooling water circuit (not shown).

[0077] Modifications to the invention can readily be made by those skilled in the field. It is therefore understood that this invention is not limited to the exemplary embodiments described above.

[0078] In the following claims and in the preceding description of the invention, unless the context requires otherwise due to express formulations or necessary implications, the word "comprise" or variations such as "includes" or "comprehensive" are used in an inclusive sense, i.e. to specify the presence of the stated features without, however, excluding the presence or addition of further features in different embodiments of the invention.

[0079] Furthermore, a reference to the state of the art in this description should not imply that this state of the art is part of the general technical knowledge in any given country.

Claims

[1] A biomethanization system comprising: a biomethanization reactor; a heat exchanger connected in such a way that it receives biocatalyst-rich water from the biomethanization reactor via a first fluid line and cooling fluid from a cooling fluid source via a second fluid line, and is configured to cool the biocatalyst-rich water by transferring heat to the cooling fluid and to return the cooled biocatalyst-rich water to the biomethanization reactor via a third fluid line; at least one coolant valve arranged to control the supply of coolant to the heat exchanger; a heating fluid source that can be coupled to the second fluid line or the heat exchanger in a controllable manner; at least one heating fluid valve arranged in such a way as to control the supply of the heating fluid to the second fluid line or to the heat exchanger; a first temperature sensor configured to monitor the temperature of the biocatalyst-rich water during a start-up process of the biomethanization reactor and to close at least one heating fluid valve when the biocatalyst-rich water has risen to or exceeded a desired or preselected start-up temperature; and a second temperature sensor configured to monitor the temperature of the biocatalyst-rich water during operation of the biomethanization reactor and to maintain the biocatalyst-rich water at a desired or preselected operating temperature or within a desired or preselected operating temperature range during operation of the biomethanization reactor by controlling at least one cooling fluid valve. [2] A system according to claim 1, wherein the at least one heating fluid valve is controllable to control the flow rate of the heating fluid to the heat exchanger, and / or the at least one cooling fluid valve is controllable to control the flow rate of the cooling fluid to the heat exchanger, thereby enabling control of the temperature of the cooling fluid and heating fluid mixture. [3] A system according to claim 1 or 2, wherein: the first and second temperature sensors are located at a single location or are designed as a single sensor; and / or The second temperature sensor is positioned to monitor the temperature of biocatalyst-rich water in the third fluid line. [4] A system according to any of the preceding claims, wherein the starting temperature includes the operating temperature or is within the operating temperature range. [5] A system according to any of the preceding claims, wherein: the at least one cooling fluid valve comprises a variable control valve arranged in such a way that, during operation of the biomethanization reactor, it diverts cooling fluid from the second fluid line to a cooling fluid return in a controlled manner in response to the second temperature sensor, the second temperature sensor controlling a cooling fluid flow to the heat exchanger. [6] A system according to claim 5, wherein: which includes at least one cooling fluid valve and another variable control valve. The additional variable control valve is arranged in the second fluid line to control the flow of cooling fluid in the second fluid line to the heat exchanger during the start-up process, the additional variable control valve responding to the first temperature sensor, whereby the first temperature sensor controls a ratio of the mixture of cooling fluid and heating fluid that is admitted into the heat exchanger during the start-up process, and thereby controls the temperature of the mixture. [7] A system according to one of the preceding claims, comprising a further heat exchanger which can be coupled controllably to the heating fluid source and controllably to the second fluid line, wherein the further heat exchanger is controllable to transfer heat from the heating fluid to the cooling fluid from the second fluid line. [8] A system according to any of the preceding claims, wherein the heating fluid comprises hot condensate or hot water. [9] A method for operating a biomethanization system comprising a biomethanization reactor and a heat exchanger, wherein the method comprises: a start-up phase, comprehensive: Heating of biocatalyst-rich water by supplying biocatalyst-rich water from the biomethanization reactor and a heating fluid from a heating fluid source into the heat exchanger, so that the biocatalyst-rich water is heated by heat transfer from the heating fluid; Returning the biocatalyst-rich water from the heat exchanger to the biomethanization reactor; Monitoring the temperature of the biocatalyst-rich water leaving the heat exchanger with a first temperature sensor; and Terminating the supply of heating fluid to the heat exchanger under the control of the first temperature sensor when the first temperature sensor detects that the temperature of the biocatalyst-rich water has risen to or exceeded a desired or preselected starting temperature; and an operational phase, comprehensive: Cooling of the biocatalyst-rich water by supplying biocatalyst-rich water from the biomethanization reactor and cooling fluid from a cooling fluid source into the heat exchanger, so that the biocatalyst-rich water is cooled by heat transfer to the cooling fluid; Returning the biocatalyst-rich water from the heat exchanger to the biomethanization reactor; Monitoring the temperature of the biocatalyst-rich water and Maintaining the temperature of the biocatalyst-rich water under the control of the second temperature sensor at a desired or preselected operating temperature or within a desired or preselected operating temperature range by controlling a flow of the cooling fluid to the heat exchanger. [10] A method according to claim 9, comprising controlling the temperature of the heating fluid entering the heat exchanger during the start-up phase by mixing the heating fluid with a portion of the cooling fluid. [11] A method according to claim 9 or 10, comprising: Providing the first and second temperature sensors in a single location or as a single sensor; and / or Arrange the second temperature sensor to monitor the temperature of the biocatalyst-rich water exiting the heat exchanger. [12] A method according to any one of claims 9 to 11, wherein the starting temperature includes the operating temperature or is within the operating temperature range. [13] A method according to any one of claims 9 to 12, comprising: Controlled diversion of coolant to a coolant return during the operating phase in response to the second temperature sensor, wherein the second temperature sensor controls a coolant flow to the heat exchanger; and optionally Controlling a flow of cooling fluid from the cooling fluid source to the heat exchanger during the start-up phase in response to the first temperature sensor, wherein the first temperature sensor controls a ratio of a mixture of cooling fluid and heating fluid that is admitted into the heat exchanger during the start-up phase, and thereby controls the temperature of the mixture. [14] A method according to any one of claims 9 to 13, comprising transferring heat from the heating fluid to the cooling fluid from the second fluid line using a further heat exchanger. [15] A method according to any one of claims 9 to 14, wherein the heating fluid comprises hot condensate or hot water.

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