Syngas fermentation liquor cooling system

Abstract

The utility model relates to a syngas fermentation liquor cooling system, which comprises a circulating discharging unit (2) and a circulating feeding unit (3) which are connected with a biological reaction unit (1), the circulating feeding unit (3) comprises a circulating pipe A (31) and a circulating pipe B (32), the inlet end of the circulating pipe A (31) is connected with the circulating discharging unit (2), the outlet end of the circulating pipe A (31) is connected with the biological reaction unit (1), and the circulating pipe B (32) is connected with the biological reaction unit (1). The inlet end of the circulating pipe B (32) is connected with the circulating discharge unit (2), and the outlet end is connected with the biological reaction unit (1) through the heat exchange unit (4). Compared with the prior art, the fermentation activity of the synthesis gas biological reaction unit can be continuously and stably operated, the cleaning frequency of the heat exchanger can be reduced, or even if the heat exchanger is cleaned, the fermentation activity cannot be impacted, and the device has great significance in promoting the development of a synthesis gas fermentation technology.

Description

Technical Field

[0001] The utility model relates to the technical field of syngas fermentation, in particular to a syngas fermentation liquid cooling system. Background Art

[0002] Syngas fermentation is the reproduction and growth of anaerobic gas-eating bacteria using syngas (CO, CO2 and H2) as a carbon source and energy source. According to different types of strains, biofuels such as ethanol and butanol are metabolized. Anaerobic gas-eating bacteria exist in nature, and the strains can be artificially selected and domesticated; syngas is widely sourced from coal chemical industry, petrochemical industry, industrial waste gas (such as steel mill waste gas), municipal solid waste and biomass, etc. Currently, the bioreactors used in syngas fermentation include various types such as continuous stirred tank reactors, trickle bed reactors, hollow fiber membrane bioreactors, bubble column bioreactors and air-lift bioreactors. However, no matter what form of reactor is used, it is necessary to maintain the temperature of the reactor to create conditions for the fermentation activities of the strains.

[0003] Currently, the temperature of the reactor is mostly maintained by the external circulation heat exchange of a plate heat exchanger. When the syngas fermentation is running normally, chilled water (or circulating water) is used to cool the fermentation liquid to achieve the stability of the reactor temperature. Since the fermentation liquid contains bacteria (the main component is protein), and the gaps between the heat exchange plates of the plate heat exchanger are relatively small, after the plate heat exchanger operates for a period of time, the protein will adhere to the surface of the equipment in contact with it, ultimately resulting in the blockage of the heat exchanger and the decline of the mass transfer and heat exchange efficiency. Therefore, during the circulating cooling process of the fermentation liquid, it is necessary to stop the operation of the plate heat exchanger at intervals for CIP cleaning, which makes it difficult for the fermentation activities of the reactor to run continuously and smoothly. Content of the Utility Model

[0004] The purpose of the utility model is to provide a syngas fermentation liquid cooling system, which is beneficial to the continuous and stable operation of the fermentation activities.

[0005] The purpose of the utility model can be achieved by the following technical solutions: a syngas fermentation liquid cooling system, including a circulating discharge unit and a circulating feed unit connected to a biological reaction unit. The circulating feed unit includes a circulating pipe A and a circulating pipe B. The inlet end of the circulating pipe A is connected to the circulating discharge unit, and the outlet end is connected to the biological reaction unit. The inlet end of the circulating pipe B is connected to the circulating discharge unit, and the outlet end is connected to the biological reaction unit through a heat exchange unit.

[0006] Preferably, the heat exchange unit includes one or more groups of shell-and-tube heat exchangers.

[0007] More preferably, the heat exchange unit includes multiple groups of shell-and-tube heat exchangers connected in parallel, and each shell-and-tube heat exchanger is connected with a corresponding on-off valve and flow regulating valve.

[0008] Further preferably, the heat exchange unit includes five groups of shell-and-tube heat exchangers connected in parallel. The function of the shell-and-tube heat exchanger (group) is to cool the circulating fermentation broth (10% of the total circulation volume) with chilled water at 7°C. A total of 5 groups of shell-and-tube heat exchangers are configured, and the operating state during normal production of the biological reaction unit is 4 in use and 1 standby.

[0009] Further preferably, a switching valve is provided at the inlet end of each shell-and-tube heat exchanger, and a flow meter and a flow regulating valve are provided at the outlet end.

[0010] Preferably, the circulating discharge unit includes a circulating liquid discharge port, a circulating liquid discharge pipe, and a circulating pump;

[0011] The circulating liquid discharge pipe is connected to the biological reaction unit through the circulating liquid discharge port and is connected to circulating pipe A and circulating pipe B through the circulating pump.

[0012] The circulating pump is connected through the circulating liquid discharge pipe and the circulating liquid discharge port. The circulating pump outputs the fermentation broth. Most of the fermentation broth (90% of the total circulation volume) is fed into the total circulating pump pipe through circulating pipe A and then enters the biological reaction unit through the circulating liquid feed port; a small part of the fermentation broth (10% of the total circulation volume) is transported to the shell-and-tube heat exchanger (group) for cooling, and the cooled fermentation broth also flows into the total circulating pump pipe and enters the biological reaction unit through the circulating liquid feed port.

[0013] Preferably, the circulating feed unit further includes a total circulating pump pipe and a circulating liquid feed port. The outlet ends of circulating pipe A and circulating pipe B are connected to the biological reaction unit through the total circulating pump pipe and the circulating liquid feed port, that is, the uncooled circulating fermentation broth and the cooled circulating fermentation broth enter the biological reaction unit through the total circulating pump pipe.

[0014] Preferably, the biological reaction unit is connected to a syngas inlet unit.

[0015] Further preferably, the syngas inlet unit includes a syngas inlet pipe and a syngas inlet. The syngas inlet pipe is connected to the biological reaction unit through the syngas inlet, and syngas enters the biological reaction unit through the inlet.

[0016] Preferably, the biological reaction unit includes a fermentation tank and a gas-liquid mixing component provided in the fermentation tank. The fermentation tank is the place where the bacteria carry out fermentation activities, and a gas-liquid mixing component is installed inside it. The bacteria and syngas in the fermentation broth carry out a biological conversion reaction in the gas-liquid mixing component. The bacteria convert the introduced syngas into the target product - ethanol at one time. After the biological conversion reaction, the fermentation broth heats up and flows out from the bottom of the fermentation tank, and returns to the fermentation tank after being cooled by external circulation heat exchange.

[0017] Further preferably, the syngas intake unit and the circulating feed unit are connected to a gas-liquid mixing assembly. The circulating fermentation liquid and the syngas are mixed in the gas-liquid mixing assembly to generate microbubbles, so that the bacteria complete the conversion of the syngas. The bioreactor unit has requirements for the gas / liquid ratio and requires a fixed flow of circulating liquid.

[0018] More preferably, the gas-liquid ratio of the bioreactor is: (1-5):1, i.e. 1-5 Nm 3 of synthesis gas, corresponding to 1m 3 of fermentation broth.

[0019] Preferably, the bioreactor unit and / or the heat exchange unit is connected to a CIP cleaning unit.

[0020] Further preferably, the circulating fermentation liquid is routed through the tube side of the shell-and-tube heat exchanger, and the shell side of the heat exchanger is provided with an inlet pipeline and a return pipeline for chilled water, and a CIP cleaning unit is provided on each group of heat exchangers, and each heat exchanger can be cleaned separately and independently. The normal operating state of the shell-and-tube heat exchanger (group) is 4 on and 1 standby. When it is necessary to clean the 4 groups of heat exchangers in operation (tentatively referred to as the "original state"), stop the operation of one of the heat exchangers, close the cut-off valve (switching valve) at the inlet of the heat exchanger and the regulating valve at the outlet, and isolate the heat exchanger from the remaining groups of heat exchangers to facilitate independent CIP cleaning. At this time, the spare group of heat exchangers is put into use, and the current operating state of the heat exchanger is 4 on and 1 standby (the spare group 1 is to be cleaned), and the switching of the heat exchanger (group) is completed. Then, the 1 group of heat exchangers that just stopped running are CIP-washed, and the total flushing time is about 10-20 minutes. After the flushing is completed, the other 3 groups of heat exchangers that need CIP flushing in the "original state" are rotated in turn until the 3 groups of heat exchangers are CIP-washed. Finally, the operating state of the heat exchanger (group) is 4 on and 1 standby. After the fermentation tank is turned over, the CIP flushing system of the fermentation tank can also be used to CIP flush the shell-and-tube heat exchanger (group). The flushing liquid after cleaning the tank body is accumulated in the fermentation tank, and then the circulating pump is used to transport the flushing liquid to achieve CIP flushing of the heat exchanger (group).

[0021] A method for cooling syngas fermentation liquid, using the above system, comprises the following steps:

[0022] The fermentation liquid in the bioreactor unit is transported to the circulation pipe A and the circulation pipe B through the circulation discharge unit. The fermentation liquid in the circulation pipe A is directly returned to the bioreactor unit, and the fermentation liquid in the circulation pipe B is returned to the bioreactor unit after being cooled by the heat exchange unit. The flow rate of the circulation pipe A is greater than that of the circulation pipe B.

[0023] Preferably, the flow rate of the circulation pipe A accounts for 85-95% of the total discharge flow rate of the circulation discharge unit, and the flow rate of the circulation pipe B accounts for 5-15% of the total discharge flow rate of the circulation discharge unit.

[0024] Further preferably, the flow rate of the circulation pipe A accounts for 90% of the total discharge flow rate of the circulation discharging unit, and the flow rate of the circulation pipe B accounts for 10% of the total discharge flow rate of the circulation discharging unit.

[0025] Preferably, the fermentation broth in the circulation pipe B is cooled to 10 - 30 °C by the heat exchange unit and then returned to the biological reaction unit.

[0026] Preferably, the heat exchange unit uses chilled water at 7 - 12 °C.

[0027] Even further preferably, the heat exchange unit uses chilled water at 7 °C.

[0028] Compared with the prior art, the utility model has the following beneficial effects:

[0029] 1. Through the cooperative setting of the circulation pipe A, the circulation pipe B and the heat exchange unit, the utility model enables a small part of the syngas fermentation broth to achieve external circulation heat exchange and can maintain the temperature of the fermentation tank at the set temperature. This setting can reduce the investment and cleaning cost of the heat exchange unit.

[0030] 2. Through the setting of multiple groups of parallel shell - and - tube heat exchangers and corresponding valves in the heat exchange unit of the utility model, the probability of protein blockage can be reduced, and the heat exchanger can be cleaned in turn, enabling the normal operation of the biological reaction unit and facilitating the continuous and stable operation of the fermentation activity.

[0031] 3. In the cooling process of the syngas fermentation broth of the utility model, chilled water at 7 °C is used to cool a small part (10% of the total circulation volume) of the fermentation broth, eliminating the need to cool down all the circulating fermentation broth. This reduces the total heat exchange area of the heat exchanger and the equipment investment. Since the shell - and - tube heat exchanger (group) can also be cleaned by CIP together with the reactor, each group of heat exchangers does not require an independent CIP cleaning system, further reducing the investment in the CIP process.

[0032] 4. The utility model uses a shell - and - tube heat exchanger instead of a plate heat exchanger. Due to the different equipment structures of the two, the shell - and - tube heat exchanger can greatly reduce the probability of protein blockage. Compared with the plate heat exchanger, the shell - and - tube heat exchanger is more convenient for CIP cleaning. One of the four shell - and - tube heat exchangers is in standby, and they can be replaced and cleaned one by one without stopping all the heat exchange equipment. This reduces the frequency of the heat exchanger affecting the normal operation of the fermentation tank reactor due to fouling and the CIP flushing cost. Moreover, the CIP cleaning of the heat exchanger can be carried out during the cleaning of the fermentation tank, ensuring that the cleaning process does not affect the normal operation of the fermentation tank reactor.

[0033] 5. According to different seasons, the utility model can flexibly adjust the number of shell-and-tube heat exchangers used. Especially when the reactor operates in winter, the circulating fermentation broth may not need to be cooled. At this time, the circulating fermentation broth with all flow rates can directly return to the reactor, putting 5 shell-and-tube heat exchangers into standby state.

[0034] 6. The utility model is a process flow that can make the fermentation activities of the biological reaction unit operate continuously and stably, reduce the cleaning frequency of the heat exchanger, or even if the heat exchanger is cleaned, it will not cause an impact on the fermentation activities, which is of great significance to promoting the development of syngas fermentation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic structural diagram of a syngas fermentation broth cooling system of the utility model;

[0036] Figure 2 It is a schematic structural diagram of the biological reaction unit of the utility model;

[0037] Figure 3 It is a schematic structural diagram of the circulating discharge unit of the utility model;

[0038] Figure 4 It is a schematic structural diagram of the circulating feed unit of the utility model;

[0039] Figure 5 It is a schematic structural diagram of the syngas inlet unit of the utility model;

[0040] Figure 6 It is a schematic structural diagram of another syngas fermentation broth cooling system of the utility model;

[0041] In the figure: 1 - biological reaction unit, 11 - fermentation tank, 12 - gas-liquid mixing component, 2 - circulating discharge unit, 21 - circulating liquid discharge port, 22 - circulating liquid discharge pipe, 23 - circulating pump, 3 - circulating feed unit, 31 - circulating pipe A, 32 - circulating pipe B, 33 - total circulating pump pipe, 34 - circulating liquid feed port, 4 - heat exchange unit, 5 - syngas inlet unit, 51 - syngas inlet pipe, 52 - syngas inlet port, CHWS - chilled water inlet, CHWR - chilled water return, TE - thermometer, FE - flowmeter. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The following will describe the utility model in detail with reference to the drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the utility model, and gives the detailed implementation method and specific operation process, but the protection scope of the utility model is not limited to the following embodiments.

[0043] It should be noted that like reference numerals and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined or explained in subsequent figures.

[0044] The following will, with reference to the drawings, elaborate on some embodiments of the present utility model. Without conflict, the following embodiments and the features in the embodiments may be combined with each other.

[0045] Embodiment 1

[0046] A synthesis gas fermentation liquid cooling system includes a circulating discharge unit 2, a circulating feed unit 3, and a heat exchange unit 4.

[0047] Among them, both the circulating discharge unit 2 and the circulating feed unit 3 are connected to the biological reaction unit 1. The circulating feed unit 3 includes a circulating pipe A31 and a circulating pipe B32. The inlet end of the circulating pipe A31 is connected to the circulating discharge unit 2, and the outlet end is connected to the biological reaction unit 1. The inlet end of the circulating pipe B32 is connected to the circulating discharge unit 2, and the outlet end is connected to the biological reaction unit 1 via the heat exchange unit 4. The synthesis gas fermentation liquid in the circulating pipe A31 directly returns to the biological reaction unit 1, and the synthesis gas fermentation liquid in the circulating pipe B32 returns to the biological reaction unit 1 after being cooled by the heat exchange unit 4.

[0048] Embodiment 2

[0049] A synthesis gas fermentation liquid cooling system, as Figures 1 to 5 shown, the circulating discharge unit 2 includes a circulating liquid discharge port 21, a circulating liquid discharge pipe 22, and a circulating pump 23, and is connected to the circulating pipe A31 and the circulating pipe B32. The circulating feed unit 3 further includes a total circulating pump pipe 33 and a circulating liquid feed port 34. The heat exchange unit 4 includes five parallel shell-and-tube heat exchangers. Each shell-and-tube heat exchanger is connected with a corresponding on-off valve and flow regulating valve, and uses 7°C chilled water. The synthesis gas inlet unit 5 includes a synthesis gas inlet pipe 51 and a synthesis gas inlet port 52.

[0050] Specifically, the synthesis gas fermentation liquid in the biological reaction unit 1 is transported to the circulating pipe A31 and the circulating pipe B32 through the circulating liquid discharge port 21, the circulating liquid discharge pipe 22, and the circulating pump 23. The synthesis gas fermentation liquid in the circulating pipe A31 returns to the biological reaction unit 1 through the total circulating pump pipe 33 and the circulating liquid feed port 34. The synthesis gas fermentation liquid in the circulating pipe B32 returns to the biological reaction unit 1 after being heat-exchanged and cooled by the shell-and-tube heat exchangers of the heat exchange unit 4 and then through the total circulating pump pipe 33 and the circulating liquid feed port 34.

[0051] Moreover, in this embodiment, both the input and output ends of each shell-and-tube heat exchanger are connected with a CIP cleaning unit. The rest is the same as that in Embodiment 1.

[0052] Embodiment 3

[0053] A synthesis gas fermentation broth cooling system, as Figure 6 shown. Different from Example 2, each shell-and-tube heat exchanger is not connected to the CIP cleaning unit, but the biological reaction unit 1 is connected to the CIP cleaning unit.

[0054] Example 4

[0055] A synthesis gas fermentation broth cooling system, comprising:

[0056] A biological reaction unit 1, comprising a fermenter 11 and a gas-liquid mixing assembly 12 arranged inside the fermenter 11;

[0057] A synthesis gas inlet unit 5, comprising a synthesis gas inlet pipe 51 and a synthesis gas inlet 52;

[0058] A fermentation broth circulation cooling unit, comprising a circulation pump 23, a circulating liquid discharge port 21, a circulating liquid discharge pipe 22, a circulation pipe A 31, a circulation pipe B 32, a shell-and-tube heat exchanger (group), a total circulation pump pipe 33, and a circulating liquid inlet 34;

[0059] When the cooling system in this example operates, the shell-and-tube heat exchanger (group) is in an operating state of 4 in use and 1 standby when the biological reaction unit 1 is at normal load. The chilled water automatically controls the discharge temperature of the material side of each heat exchanger; the outlet flow regulating valve on the material side of the heat exchanger maintains a fixed flow rate of the circulating fermentation broth in each group. When the shell-and-tube heat exchanger (group) needs CIP cleaning, the idle heat exchanger gradually replaces the single heat exchanger to be cleaned, so that the CIP cleaning of the shell-and-tube heat exchanger does not affect the normal operation of the biological reaction unit.

[0060] And according to different seasons, the number of shell-and-tube heat exchangers used can be flexibly adjusted. When the biological reaction unit operates in winter, the circulating fermentation broth may not need to be cooled. At this time, all the circulating fermentation broth can be directly returned to the biological reaction unit, putting the 5 shell-and-tube heat exchangers into standby state.

[0061] Example 5

[0062] A synthesis gas fermentation broth cooling system, comprising:

[0063] A biological reaction unit 1, comprising a fermenter 11 and a gas-liquid mixing assembly 12 arranged inside the fermenter 11;

[0064] A synthesis gas inlet unit 5, comprising a synthesis gas inlet pipe 51 and a synthesis gas inlet 52;

[0065] A fermentation broth circulation cooling unit, comprising a circulation pump 23, a circulating liquid discharge port 21, a circulating liquid discharge pipe 22, a circulation pipe A 31, a circulation pipe B 32, a shell-and-tube heat exchanger (group), a total circulation pump pipe 33, and a circulating liquid inlet 34;

[0066] The heat exchange process in this Embodiment 5 is basically the same as that in Embodiment 4. The difference is that an independent CIP cleaning system is not configured for each group of shell-and-tube heat exchangers. Since the service life of the fermentation bacteria is limited, when the activity of the bacteria decreases, it is necessary to re-culture the bacteria and perform an operation of emptying the fermentation tank. After the emptying of the fermentation tank is completed, the shell-and-tube heat exchanger (group) can be cleaned by CIP together with the biological reaction unit.

[0067] The fermentation tank is provided with a CIP cleaning system, and a certain volume of cleaning liquid can be injected into the fermentation tank, and the circulation pump is started to perform circulating cleaning on the shell-and-tube heat exchanger (group), which further reduces the investment in the CIP process.

[0068] During the synthesis gas fermentation process, a plate heat exchanger is used to cool the fermentation broth. Since the cell protein will cause blockage of the heat exchanger, it is necessary to perform CIP cleaning on the heat exchanger 1-2 times a week. Cleaning the heat exchanger will affect the normal operation of the reactor. The present utility model designs a new process for cooling the synthesis gas fermentation broth, uses a shell-and-tube heat exchanger instead of a plate heat exchanger, cools the fermentation broth with 7°C chilled water, and adjusts the distribution flow rate of the circulating fermentation broth, which can meet the flow rate requirements of the biological reaction unit. Since the shell-and-tube heat exchanger is used, the probability of blockage of the heat exchanger is greatly reduced, and it can be cleaned once every 1-2 months during the normal operation of the fermentation tank or does not need to be cleaned during the normal operation of the fermentation tank. This process can not only maintain the temperature of the fermentation tank but also, when the heat exchanger needs to be cleaned, will not impact the normal fermentation activity in the fermentation tank.

[0069] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the utility model. Those skilled in the art can obviously make various modifications to these embodiments easily and apply the general principles described herein to other embodiments without creative labor. Therefore, the present utility model is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present utility model according to the disclosure of the present utility model should be within the protection scope of the present utility model.

Claims

1. A synthesis gas fermentation liquid cooling system, characterized in that: The invention comprises a circulating discharge unit (2) and a circulating feed unit (3) connected to a biological reaction unit (1); the circulating feed unit (3) comprises a circulating pipe A (31) and a circulating pipe B (32); the inlet end of the circulating pipe A (31) is connected to the circulating discharge unit (2), and the outlet end is connected to the biological reaction unit (1); the inlet end of the circulating pipe B (32) is connected to the circulating discharge unit (2), and the outlet end is connected to the biological reaction unit (1) via a heat exchange unit (4).

2. The synthesis gas fermentation liquid cooling system according to claim 1, characterized in that: The heat exchange unit (4) comprises one or more groups of shell-and-tube heat exchangers.

3. The synthesis gas fermentation liquid cooling system according to claim 2, characterized in that: The heat exchange unit (4) comprises a plurality of shell-and-tube heat exchangers connected in parallel, each of which is connected to a corresponding switch valve and a flow regulating valve.

4. The synthesis gas fermentation liquid cooling system according to claim 3, characterized in that: A switch valve is provided at the inlet end of each shell-and-tube heat exchanger, and a flow meter and a flow regulating valve are provided at the outlet end.

5. The synthesis gas fermentation liquid cooling system according to claim 2, characterized in that: The heat exchange unit (4) comprises five groups of shell-and-tube heat exchangers connected in parallel, including four groups of operating shell-and-tube heat exchangers and one group of spare shell-and-tube heat exchangers.

6. The synthesis gas fermentation liquid cooling system according to claim 1, characterized in that: The circulating discharge unit (2) comprises a circulating liquid discharge port (21), a circulating liquid discharge pipe (22) and a circulating pump (23); The circulating liquid discharge pipe (22) is connected to the bioreactor unit (1) via the circulating liquid discharge port (21), and is connected to the circulating pipe A (31) and the circulating pipe B (32) via the circulating pump (23).

7. The synthesis gas fermentation liquid cooling system according to claim 1, characterized in that: The circulating feed unit (3) further comprises a total circulating pump pipe (33) and a circulating liquid feed port (34); the outlet ends of the circulating pipe A (31) and the circulating pipe B (32) are connected to the bioreactor unit (1) via the total circulating pump pipe (33) and the circulating liquid feed port (34).

8. The synthesis gas fermentation liquid cooling system according to claim 1, characterized in that: The bioreactor unit (1) is connected to a synthesis gas intake unit (5); The synthesis gas intake unit (5) comprises a synthesis gas intake pipe (51) and a synthesis gas intake port (52), and the synthesis gas intake pipe (51) is connected to the biological reaction unit (1) via the synthesis gas intake port (52).

9. The synthesis gas fermentation liquid cooling system according to claim 1, characterized in that: The bioreactor unit (1) comprises a fermentation tank and a gas-liquid mixing component arranged in the fermentation tank.

10. The synthesis gas fermentation liquid cooling system according to claim 1, characterized in that: The bioreactor unit (1) and / or the heat exchange unit (4) is connected to a CIP cleaning unit.

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