System and method for producing biological protein feed by centrifugal concentration and evaporation of fermentation liquor

Abstract

The invention relates to a system and method for producing biological protein feed through centrifugal concentration and evaporation of fermentation broth, the system comprises a first centrifugal machine, a second centrifugal machine and a flash evaporation drying unit which are connected in sequence, and light phase outlets of the first centrifugal machine and the second centrifugal machine are respectively connected with a clear liquid tank through pipelines; the first centrifugal machine and the second centrifugal machine are different in type. Different types of centrifuges are used for secondary centrifugal separation, thalli in fermentation liquor can be effectively separated, biological protein feed is produced, and heat exchanger and tower blockage caused by protein temperature rise denaturation in the distillation process of thalli protein in the fermentation liquor is avoided to a certain extent.

Description

Technical Field

[0001] The present invention belongs to the technical field of synthesizing ethanol from syngas, and relates to a system and method for centrifugally concentrating and evaporating fermentation broth to produce bio - protein feed. Background Art

[0002] Syngas fermentation is a technology that uses anaerobic gas - eating bacteria as strains, and uses CO, CO 2 and H 2 in syngas as carbon sources and energy sources for reproduction and metabolism to produce renewable energy such as ethanol. 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. At present, the production of ethanol by syngas fermentation has achieved large - scale production, and this production technology will help China achieve "carbon peak" before 2030 and "carbon neutrality" before 2060.

[0003] Anaerobic gas - eating bacteria carry out metabolic activities in the fermenter to produce ethanol. When distilling and extracting ethanol from the fermentation broth, since the fermentation broth contains bacteria (mainly proteins), protein denaturation due to temperature rise will cause blockage of heat exchangers and trays, affecting the mass transfer and heat transfer of the equipment, resulting in interruptions in the entire production process. When the equipment is blocked, it is necessary to regularly carry out on - line cleaning of the heat exchangers and trays with lye to continue production. Therefore, according to Chinese patents CN111647496A "A continuous fermentation bacterial body circulation separation coupling system", CN113755534A "A method and system for preparing ethanol by coke oven gas fermentation", and CN217628354U "A fermentation system", the existing syngas - to - ethanol processes currently separate the bacteria (proteins) in the fermentation broth using a centrifuge or ceramic membrane before the fermentation broth enters the distillation system to avoid blockage of heat exchangers and trays. The separated bacteria are then returned to the fermenter to control the bacterial concentration and continue to utilize the nutrients in the fermentation substrate. By detecting the bacterial concentration in the fermenter, the excess separated liquid is sent to the distillation system for ethanol extraction. However, this separation method will cause damage and death to the bacteria, and there is a risk of contaminating the fermenter when the separated material comes into contact with air; and when the separated liquid is heated for ethanol separation and extraction, it will also cause blockage of heat exchangers and trays.

[0004] Therefore, studying a solution that can avoid blockage of heat exchangers and trays when extracting ethanol from fermentation broth, make the process of producing bio - protein feed smooth, and reduce pollution during the fermentation process is of great significance for promoting the development of the syngas - to - ethanol process. Summary of the Invention

[0005] The object of the present invention is to provide a system and method for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth. By using different types of centrifuges for secondary centrifugal separation, the bacteria in the fermentation broth can be effectively separated to produce biological protein feed, and to a certain extent, blockages of heat exchangers and towers caused by protein thermal denaturation of the bacterial protein in the fermentation broth during the distillation process can be avoided.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] One of the technical solutions of the present invention provides a system for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth, including a fermentation tank, a first centrifuge, a second centrifuge, and a flash drying unit connected in sequence. The light phase outlets of the first centrifuge and the second centrifuge are also respectively connected to a clear liquid tank through pipelines, and the types of the first centrifuge and the second centrifuge are different.

[0008] Furthermore, a pervaporation membrane module is also provided on the pipeline between the first centrifuge and the clear liquid tank, and a branch is additionally led on the pervaporation membrane module as a clear liquid pipeline for discharging the clear liquid generated by membrane separation. Specifically, pervaporation membranes in the pervaporation membrane module can use pervaporation membranes with high permeation flux and high separation coefficient such as Silicalite-1.

[0009] Furthermore, the first centrifuge is a disc centrifuge, and the second centrifuge is a horizontal scroll centrifuge.

[0010] Furthermore, a feed pump is also provided between the fermentation tank and the first centrifuge.

[0011] Furthermore, a diaphragm filter press is also arranged between the second centrifuge and the flash drying unit.

[0012] Even further, the light phase outlet on the diaphragm filter press is also connected to the clear liquid tank through a pipeline.

[0013] Even further, the diaphragm filter press and the flash drying unit are connected through a filter cake conveying line.

[0014] Furthermore, the clear liquid tank is also connected to an external distillation system through a second clear liquid pipeline.

[0015] Furthermore, a biological protein feed conveying line for externally outputting biological protein feed is also provided on the flash drying unit.

[0016] Another technical solution of the present invention provides a method for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth, which is based on the system for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth as described in any one of the above, and is characterized by including the following steps:

[0017] (1) The fermentation broth in the fermenter is transported to the first centrifuge for primary separation. The resulting light-phase liquid enters the pervaporation membrane module, and the heavy-phase liquid is sent to the second centrifuge.

[0018] (2) The clarified liquid produced by the pervaporation membrane module is sent to an external distillation system, and the retentate is sent to the clarified liquid tank.

[0019] (3) Secondary separation is carried out in the second centrifuge. The resulting light-phase liquid is sent to the clarified liquid tank, and the heavy-phase liquid is sent to the flash drying unit to produce bio-protein feed.

[0020] (4) The liquid collected in the clarified liquid tank is sent to an external distillation system. After ethanol is extracted, the bottom liquid is heated, sterilized, cooled, and then returned to the fermenter.

[0021] In order to better concentrate the microbial suspended solids in the fermentation broth, the present invention first uses a disc centrifuge to concentrate the solid content by 30 - 35 times, and then uses a scroll centrifuge to concentrate it by 3 - 5 times. Most of the diameters of the microbial suspended solid particles in the fermentation broth processed by the present invention are 1 μm. The disc centrifuge is suitable for separating and concentrating media with relatively small monomer particle sizes such as bacteria and yeast (such as particle sizes of 1 μm and below), and the scroll centrifuge is suitable for concentrating and separating media with solid-phase particle diameters of 5 μm - 5 mm. Regarding the particle diameters of different media suitable for the disc centrifuge and the scroll centrifuge, and the limited concentration ratio of a single type of disc centrifuge and scroll centrifuge, the present invention uses a disc centrifuge for primary separation and a scroll centrifuge for secondary separation. Compared with simply using two centrifuges of the same type, this can better improve the concentration multiple of the microbial suspended solid particles, increase the solid content of the solid phase, save steam after it enters the flash drying system, and reduce the steam energy consumption of the product bio-protein feed. And this design process is closed, and there will be no odor escaping during the production process, which is a clean and environmentally friendly production method.

[0022] In the currently existing synthesis gas to ethanol processes, before the fermentation broth enters the distillation system, centrifuges or ceramic membranes are used to separate the bacteria (protein) in the fermentation broth. The disc centrifuge operates under a centrifugal gravity of 1600G and higher, and the bacterial structure is easily damaged, even leading to the death of the bacteria. For example, in Chinese patents CN111647496A, CN113755534A, CN217628354U, etc., a disc centrifuge is used for solid-liquid separation of bacteria and ethanol / water mixture, and then the solid phase containing bacteria is recycled to the fermenter at a certain ratio. In the present invention, since the bacteria separated by the disc centrifuge and the scroll centrifuge are not recycled, even if the bacteria are damaged or dead, it will not affect the ongoing fermentation activity and can greatly reduce the risk of bacterial contamination in the fermenter.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) For the fermentation broth containing thalli, different types of centrifuges are used for secondary centrifugal separation. The light phase with extremely low solid content separated out can be sent to the crude distillation column of the distillation system for ethanol separation and extraction, and the bottom liquid of the column is sterilized at high temperature and then returned to the fermentation tank for reuse; for the solid phase generated by separation, after secondary concentration, it is directly sent to the flash drying unit to produce biological protein feed.

[0025] (2) The thalli in the fermentation broth are retained in the solid phase during the secondary centrifugal separation process and used to produce biological protein feed, making the clear liquid sent to the distillation system basically free of thalli protein. This reduces the probability of blockage of heat exchangers and trays, and there is no need to stop the machine for on-line flushing of the heat exchangers and trays with lye, making the entire production process smoother.

[0026] (3) The light phase generated by secondary separation, after ethanol is separated and extracted by the distillation system, is heated and sterilized and then returned to the fermentation tank for reuse, reducing the risk of bacterial contamination in the fermentation tank.

[0027] (4) The design process is closed, and no odor will escape during the production process, which is a clean and environmentally friendly production method. Description of the Drawings

[0028] Figure 1 is the process flow chart of Example 1;

[0029] Figure 2 is the process flow chart of Example 2;

[0030] Description of the Marks in the Figures

[0031] 1 - Fermentation tank, 2 - Fermentation broth input pipeline, 3 - Feed pump, 4 - Fermentation broth transfer pipeline, 5 - Disc centrifuge, 6 - Light phase one pipeline, 7 - Heavy phase one pipeline, 8 - Scroll centrifuge, 9 - Light phase two pipeline, 10 - Heavy phase two pipeline, 11 - Ethanol permeation membrane module, 12 - Clear liquid one pipeline, 13 - Retentate pipeline, 14 - Clear liquid tank, 15 - Clear liquid two pipeline, 16 - Flash drying unit, 17 - Biological protein feed transfer line, 18 - Heavy phase three pipeline, 19 - Filter cake transfer line, 20 - Light phase three pipeline, 21 - Diaphragm filter press. Detailed Embodiments

[0032] The present invention will be described in detail below with reference to the drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and the detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0033] In the following embodiments or examples, if there is no special description of functional components or structures, it means that they are all conventional components or structures adopted in the art to achieve corresponding functions.

[0034] In order to effectively separate the bacteria in the fermentation broth, produce biological protein feed, and to a certain extent avoid blockages in heat exchangers and towers caused by protein denaturation due to temperature rise during the distillation of the bacterial protein in the fermentation broth, the present invention provides a system for centrifugally concentrating and evaporating fermentation broth to produce biological protein feed, the structure of which can be seen Figure 1 or Figure 2 as shown, including a first centrifuge, a second centrifuge and a flash drying unit 16 connected in sequence. The light phase outlets of the first centrifuge and the second centrifuge are also respectively connected to a clear liquid tank 14 through pipelines, and the types of the first centrifuge and the second centrifuge are different.

[0035] In some specific embodiments, a pervaporation membrane group 11 is also provided on the pipeline between the first centrifuge and the clear liquid tank 14, and a branch is additionally led on the pervaporation membrane group 11 as a clear liquid pipeline 12 for discharging the clear liquid generated by membrane separation.

[0036] In some specific embodiments, the first centrifuge is a disc centrifuge 5, and the second centrifuge is a horizontal spiral centrifuge 8.

[0037] In some specific embodiments, a feed pump 3 is also provided between the fermentation tank 1 and the first centrifuge.

[0038] In some specific embodiments, a diaphragm filter press 21 is also arranged between the second centrifuge and the flash drying unit 16. Additionally, it should be noted that the flash drying unit 16 can adopt commonly used flash drying equipment in the art.

[0039] Furthermore, the light phase outlet on the diaphragm filter press 21 is also connected to the clear liquid tank 14 through a pipeline.

[0040] Furthermore, the diaphragm filter press 21 and the flash drying unit 16 are connected through a filter cake conveyor line.

[0041] In some specific embodiments, the clear liquid tank 14 is also connected to an external distillation system through a clear liquid pipeline 2.

[0042] In some specific embodiments, a biological protein feed conveyor line 17 for externally outputting biological protein feed is also provided on the flash drying unit 16.

[0043] The above embodiments can be implemented separately, or can be combined in any two or more combinations.

[0044] The above embodiments will be described in more detail below in conjunction with specific embodiments.

[0045] Embodiment 1:

[0046] As Figure 1 shown, the process flow equipment in this embodiment includes: a fermentation tank 1, a fermentation broth input pipeline 2, a feeding pump 3, a fermentation broth delivery pipeline 4, a disc centrifuge 5, a light phase I pipeline 6, a heavy phase I pipeline 7, a scroll centrifuge 8, a light phase II pipeline 9, a heavy phase II pipeline 10, a pervaporation membrane module 11, a clear liquid I pipeline 12, a retentate pipeline 13, a clear liquid tank 14, a clear liquid II pipeline 15, a flash drying unit 16, and a biological protein feed delivery line 17.

[0047] In this embodiment, when performing secondary centrifugal concentration on the fermentation broth to produce biological protein feed, the fermentation broth in the fermentation tank 1 is transported to the feeding pump 3 through the fermentation broth input pipeline 2 by its own pressure. The feeding pump 3 sends the fermentation broth to the disc centrifuge 5 through the fermentation broth delivery pipeline 4 for the first-stage separation. The disc centrifuge 5 generates light-phase liquid from the top through the light phase I pipeline 6 and enters the pervaporation membrane module 11; the heavy-phase liquid generated at the bottom enters the scroll centrifuge 8 through the heavy phase I pipeline 7 for the second-stage centrifugal separation. The clear liquid generated by the pervaporation membrane module 11 through membrane separation enters the distillation system through the clear liquid I pipeline 12, and the retentate generated enters the clear liquid tank 14 through the retentate pipeline 13. The light-phase liquid generated by the scroll centrifuge 8 through secondary centrifugal separation enters the clear liquid tank 14 through the light phase II pipeline 9, and together with the retentate generated by the pervaporation membrane module 11, is transported to the distillation system through the clear liquid II pipeline 15. After the distillation system extracts ethanol, the bottom liquid generated is reheated, sterilized, cooled, and then returned to the fermentation tank for replenishment of the liquid level and nutrients (not shown). The heavy-phase liquid generated by the scroll centrifuge 8 enters the flash drying unit 16 through the heavy phase II pipeline 10 to produce biological protein feed, and the product is stored and sold externally through the biological protein feed delivery line 17.

[0048] Embodiment 2:

[0049] As Figure 2 shown, the process flow equipment in this embodiment includes: a fermentation tank 1, a fermentation broth input pipeline 2, a feeding pump 3, a fermentation broth delivery pipeline 4, a disc centrifuge 5, a light phase I pipeline 6, a heavy phase I pipeline 7, a scroll centrifuge 8, a light phase II pipeline 9, a heavy phase III pipeline 18, a filter cake delivery line 19, a light phase III pipeline 20, a diaphragm filter press 21, a pervaporation membrane module 11, a clear liquid I pipeline 12, a retentate pipeline 13, a clear liquid tank 14, a clear liquid II pipeline 15,, a flash drying unit 16, and a biological protein feed delivery line 17.

[0050] In this embodiment, when producing biological protein feed by performing secondary centrifugal concentration on the fermentation broth, the fermentation broth in the fermentation tank 1 is transported to the feed pump 3 through the fermentation broth input pipeline 2 by its own pressure. The feed pump 3 sends the fermentation broth to the disc centrifuge 5 through the fermentation broth transport pipeline 4 for the first-stage separation. The disc centrifuge 5 produces a light-phase liquid from the top after separation and enters the pervaporation membrane module 11 through the light-phase one pipeline 6; the heavy-phase liquid produced at the bottom enters the scroll centrifuge 8 through the heavy-phase one pipeline 7 for the second-stage centrifugal concentration. The clear liquid produced by the pervaporation membrane module 11 through membrane separation enters the distillation system through the clear liquid one pipeline 12, and the retentate produced enters the clear liquid tank 14 through the retentate pipeline 13. The light-phase liquid produced by the scroll centrifuge 8 through the second-stage centrifugal separation enters the clear liquid tank 14 through the light-phase two pipeline 9; the heavy-phase liquid produced by the scroll centrifuge 8 enters the diaphragm filter press 21 through the heavy-phase three pipeline 18. The light phase produced by the diaphragm filter press 21 enters the clear liquid tank 14 through the light-phase three pipeline 20. Together with the retentate produced by the pervaporation membrane module 11 and the light-phase liquid produced by the scroll centrifuge 8, they are all transported to the distillation system through the clear liquid two pipeline 15. After the distillation system extracts ethanol, the bottom liquid produced is then heated, sterilized, cooled, and then returned to the fermentation tank for supplementing liquid and nutrients (not shown); the filter cake produced by the diaphragm filter press is transported to the flash drying unit 16 through the filter cake transport line 19 to produce biological protein feed, which is stored and sold externally through the biological protein feed transport line 17.

[0051] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A system for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth, characterized in that, it includes a fermentation tank, a first centrifuge, a second centrifuge and a flash drying unit connected in sequence. The light phase outlets of the first centrifuge and the second centrifuge are also respectively connected to a clear liquid tank through pipelines, and the types of the first centrifuge and the second centrifuge are different.

2. The system for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth according to claim 1, characterized in that, a pervaporation membrane module is also provided on the pipeline between the first centrifuge and the clear liquid tank, and another branch is led on the pervaporation membrane module as a clear liquid pipeline for discharging the clear liquid generated by membrane separation.

3. The system for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth according to claim 1, characterized in that, the first centrifuge is a disc centrifuge, and the second centrifuge is a horizontal screw centrifuge.

4. The system for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth according to claim 1, characterized in that, a feed pump is also provided between the fermentation tank and the first centrifuge.

5. The system for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth according to claim 1, characterized in that, a diaphragm filter press is also arranged between the second centrifuge and the flash drying unit.

6. The system for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth according to claim 5, characterized in that, the light phase outlet on the diaphragm filter press is also connected to the clear liquid tank through a pipeline.

7. The system for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth according to claim 5, characterized in that, the diaphragm filter press and the flash drying unit are connected through a filter cake conveying line.

8. The system for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth according to claim 1, characterized in that, the clear liquid tank is also connected to an external distillation system through a second clear liquid pipeline.

9. The system for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth according to claim 1, characterized in that, a biological protein feed conveying line for externally outputting biological protein feed is also provided on the flash drying unit.

10. A method for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth, which is based on the system for producing biological protein feed by centrifugal concentration and evaporation of fermentation broth according to any one of claims 1-9, characterized in that, it includes the following steps: (1) The fermentation broth in the fermentation tank is transported to the first centrifuge for primary separation. The generated light phase liquid enters the pervaporation membrane module, and the heavy phase liquid is sent to the second centrifuge; (2) The clear liquid generated by the pervaporation membrane module is sent to an external distillation system, and the retentate generated is sent to the clear liquid tank; (3) Secondary separation is carried out in the second centrifuge. The generated light phase liquid is sent to the clear liquid tank, and the heavy phase liquid is sent to the flash drying unit to produce biological protein feed; (4) The liquid collected in the clear liquid tank is sent to an external distillation system. After ethanol is extracted, the generated bottom liquid is heated, sterilized, cooled and then returned to the fermentation tank.

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