Heat recycling system based on aspergillus niger fermentation

Abstract

The invention provides a heat recycling system for producing citric acid based on aspergillus niger fermentation and a matched production process thereof, the system comprises a seed culture tank, a fermentation raw material saccharifying tank, a fermentation tank, a fermentation mash storage tank, a circulating water storage tank, a hot water storage tank, a circulating cold well, a cooling pipeline, a centrifugal pump and a reservoir, the waste heat of cooling water is recycled in the process of producing citric acid through continuous fermentation of aspergillus niger, and meanwhile the recycled waste heat is used for the saccharification process of cheap agricultural byproduct fermentation raw materials. According to the invention, the energy required by heating in the saccharification process of the fermentation raw material is saved, the cooling energy consumption of the fermentation tank is reduced, the cyclic utilization of cooling water is realized, the cost of the fermentation raw material is reduced, and the method is suitable for the requirement of large-scale industrial fermentation production of citric acid by aspergillus niger.

Description

Technical Field

[0001] The invention relates to the technical field of fermentation engineering, and in particular to a waste heat recovery system and a continuous fermentation process for producing citric acid by fermentation with Aspergillus niger. Background Art

[0002] The production of citric acid is generally obtained by continuous fermentation of Aspergillus niger, and the main fermentation raw materials traditionally used include starchy substances such as corn flour, potato flour, etc. However, the prices of these traditional raw materials have continued to rise in recent years, resulting in a significant increase in the cost of citric acid production.

[0003] Various agricultural byproducts, such as corn cobs, rice husks, bagasse and fruit peels, are considered as potential alternative raw materials due to their high carbohydrate content and low cost. However, the complex polysaccharide components such as cellulose and hemicellulose in these raw materials need to undergo longer saccharification before they can be converted into fermentable sugars by Aspergillus niger. This conversion step requires longer heating treatment, which increases energy consumption and production costs.

[0004] In addition, the fermentation of Aspergillus niger needs to be stabilized at a suitable temperature, but the fermentation process will accumulate bioheat, causing the temperature of the fermentation tank to continue to rise, and a large amount of energy is consumed for cooling. Therefore, if the waste heat of cooling water in large-scale fermentation can be recovered and used in the saccharification process of cheap raw materials such as agricultural by-products, production energy consumption can be significantly reduced, cooling water consumption can be reduced, and raw material utilization and production efficiency can be improved. Summary of the invention

[0005] In view of the problem of long saccharification heating time when agricultural by-products are used as fermentation raw materials, and the need to recover and reuse the waste heat of the fermentation tank cooling water, a waste heat recovery and utilization system is proposed. The purpose is to recover the waste heat generated during the fermentation process of Aspergillus niger and use it for the saccharification of the fermentation raw materials, thereby reducing the demand for heat source for saccharification of the fermentation raw materials and the cooling energy consumption, and realizing efficient recycling of resources.

[0006] In order to achieve the above object, the present invention provides the following technical scheme: a heat recovery and utilization system based on Aspergillus niger fermentation, comprising a seed culture tank, a fermentation raw material saccharification tank, a fermentation tank, a fermentation mash storage tank, a circulating water storage tank, a hot water storage tank, a circulating cold well, a cooling pipeline, and a water reservoir;

[0007] The circulating water storage tank is connected to the water reservoir through a pipeline, and the water reservoir is connected to an external water source and stores cold water therein, so that the cold water in the water reservoir is pumped into the circulating water storage tank through the insulation pipeline. A valve is installed on the insulation pipeline between the circulating water storage tank and the pump to control the unblocking and closing of the insulation pipeline.

[0008] The circulating water storage tank is connected to the cooling pipeline of each fermentation tank through an insulated pipeline, so that the water in the circulating water storage tank is circulated and pumped into the cooling pipeline of each fermentation tank through the insulated pipeline to remove the heat generated during the fermentation process of the fermentation tank.

[0009] The seed culture tank is provided with a valve and a pump at the bottom, and is connected to each fermentation tank through an insulation pipe, and is used to culture Aspergillus niger fermentation strains, and the strains are pumped into each fermentation tank through the insulation pipe;

[0010] The output end of each cooling pipeline is also connected to a hot water storage tank through an insulation pipe, so that when the temperature of the cooling water in the fermentation tank rises to a set threshold after absorbing biological heat, the hot water is automatically pumped into the hot water storage tank;

[0011] The hot water storage tank is connected to the insulation pipe of the saccharification tank through an insulation pipe, so that the hot water in the hot water storage tank is pumped into the insulation pipe of the saccharification tank to increase the temperature of the saccharification tank. Then the hot water in the insulation pipe flows back to the hot water storage tank through the other end opposite to the hot water pumping end, forming a circulation.

[0012] Furthermore, the circulating water storage tank is connected to the hot water storage tank through an insulated pipe, so that after the water in the circulating water storage tank reaches a set temperature, the water in the circulating water storage tank is pumped into the hot water storage tank through the insulated pipe.

[0013] Furthermore, the hot water storage tank is equipped with a heating pipe and a temperature sensor, which can further heat the circulating water to the temperature required by the saccharification tank.

[0014] Furthermore, the system also includes a circulating cold trap, which is connected to the cooling pipeline of each fermentation tank through an insulated pipe, so that water in the circulating cold trap can be circulated and pumped into the cooling pipeline of each fermentation tank through the insulated pipe, which is used to cool the fermentation tank under special circumstances.

[0015] Furthermore, the system also includes a fermentation mash storage tank, which is connected to the fermentation tank through an insulated pipe, and the fermentation mash storage tank is also connected to a saccharification tank through a pipe, so that the fermented liquid in the fermentation tank can be introduced into the fermentation mash storage tank through a valve and an insulated pipe. After the citric acid in the fermentation liquid is extracted, the remaining residual sugar that has not been completely fermented and utilized can be transported to the saccharification tank through a pipe by a pump for further saccharification utilization. The saccharification tank can dynamically add feed matrix to each fermentation tank during the fermentation process to ensure the continuity of the entire fermentation process.

[0016] Furthermore, the fermentation tank is provided with an automatic control valve, and the fermentation mash storage tank is connected to the valve on the fermentation tank through an insulated pipe.

[0017] Furthermore, the insulated pipes are wrapped with heat-insulating materials to reduce heat loss during waste heat recovery; and pumps are provided on the insulated pipes between the fermentation mash storage tank and the saccharification tank.

[0018] The specific method for producing citric acid by continuous fermentation of Aspergillus niger is as follows:

[0019] 1. Wash the Aspergillus niger spores cultured on the PAD plate medium with sterile saline to make 4×10 5 CFU / mL of bacterial suspension was transplanted into a seed culture tank, into which a seed culture medium was added, wherein the total sugar content of the seed culture medium was 12% and the total nitrogen content was 0.4%;

[0020] 2. After culturing in the seed culture tank at 32℃ for 36h, the mature seed liquid was obtained. During the process, the stirring speed was 200r / min, the pH was 4.0, and the ventilation volume was 8-10m 3 / h.

[0021] 3. Pre-culture medium was introduced into each fermentation tank, with a total sugar content of 15% and a total nitrogen content of 0.2%. Then, the seed liquid in the seed culture tank was inoculated into each fermentation tank at a rate of 15% (v / v). During the fermentation process, the stirring speed was 200 r / min, the fermentation temperature was 37-43°C, the pH was 4.0, and the ventilation volume was 8-10m 3 / h.

[0022] 4. After crushing, cleaning and sterilizing agricultural and sideline products such as corn cobs, rice husks, bagasse and fruit peels, place them in a fermentation raw material saccharification tank, add sterile water and 0.5% of the weight of the raw materials, cellulase and hemicellulase, and perform enzymolysis at a temperature of 50° C. and a pH of 4.5 for 48 hours.

[0023] 5. When the citric acid concentration in the fermentation tank reaches 130g / L, the fermentation liquid is discharged to the fermentation mash storage tank. At the same time, the feed matrix is ​​continuously added from the fermentation raw material saccharification tank to the fermentation tank at the same speed to keep the volume of the fermentation liquid balanced.

[0024] 6. Extract the citric acid from the fermentation liquid in the fermentation liquid storage tank. If the extracted waste liquid contains a large amount of residual total sugar, it can be re-introduced into the fermentation raw material saccharification tank for continued enzymatic hydrolysis.

[0025] The PAD plate culture medium and pre-culture medium are culture mediums with a fixed ratio of glucose and nutrient salts, including nitrogen salts, sodium salts, potassium salts, and magnesium salts. The Aspergillus niger strain is Aspergillus niger 3.316, which is purchased from the China General Microbiological Culture Collection Center and is a heat-resistant strain that can withstand higher fermentation temperatures.

[0026] The beneficial technical effects of the present invention are:

[0027] The traditional Aspergillus niger continuous fermentation method requires a large amount of cooling energy, has high cost of fermentation raw materials, and has high saccharification heating energy consumption when using agricultural byproducts as fermentation raw materials. The advantages of the present invention are:

[0028] 1. Save energy consumption. The waste heat collected during the fermentation process is used for saccharification of fermentation raw materials, which reduces the demand for additional energy, reduces the consumption of cooling water, and significantly improves energy efficiency.

[0029] 2. Save raw material costs and use cheap agricultural by-products as fermentation raw materials to continuously replenish sugar during the continuous fermentation process of Aspergillus niger.

[0030] 3. Improve production efficiency, use continuous fermentation technology with a high degree of automation, and improve the environmental protection and sustainability of the overall production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0032] Figure 1 A system structure diagram provided for an embodiment of the present invention.

[0033] Description of reference numerals:

[0034] 1. Circulation tank; 2. Circulation cold trap; 3. Saccharification tank; 31. Insulation pipe; 4. Hot water storage tank; 5. Fermentation mash storage tank; 6. Seed culture tank; 7. Fermentation tank; 71. Cooling pipe; 8. Water reservoir; 9. Pump. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0038] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] Example embodiments will be described more fully below with reference to the accompanying drawings, but the example embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. On the contrary, the purpose of providing these embodiments is to make the present disclosure thorough and complete and to enable those skilled in the art to fully understand the scope of the present disclosure.

[0040] In the absence of conflict, the various embodiments of the present disclosure and the various features therein may be combined with each other.

[0041] The embodiments described herein may be described with reference to plan views and / or cross-sectional views by means of idealized schematic diagrams of the present disclosure. Therefore, the example illustrations may be modified according to manufacturing techniques and / or tolerances. Therefore, the embodiments are not limited to the embodiments shown in the accompanying drawings, but include modifications of the configurations formed based on the manufacturing process. Therefore, the regions illustrated in the accompanying drawings have schematic properties, and the shapes of the regions shown in the figures illustrate the specific shapes of the regions of the elements, but are not intended to be limiting.

[0042] See also Figure 1 Because the Aspergillus niger fermentation process will accumulate biological heat and need to be dissipated, the saccharification treatment of the fermentation raw materials in the previous step of the fermentation process needs to be heated. The overall idea is to set up a heat recovery device in the fermentation tank cooling system to transfer the heat to the storage system, and then use the stored heat for the saccharification process according to the saccharification requirements.

[0043] A heat recovery and utilization system based on Aspergillus niger fermentation, comprising a circulation tank 1, a circulation cold trap 2, a saccharification tank 3, an insulation pipe 31, a hot water storage tank 4, a fermentation mash storage tank 5, a seed culture tank 6, a fermentation tank 7, a cooling pipeline 71, a water reservoir 8, and a pump 9;

[0044] The system adopts a continuous fermentation mode of multiple parallel fermentation tanks 7, and each fermentation tank 7 is integrated with a precisely designed cooling pipeline 71 for controlling and adjusting the temperature during the fermentation process. These cooling pipelines 71 are interconnected through a main circulation system (i.e., circulation tank 1) to form a closed-loop cooling network.

[0045] The circulation tank 1 is connected to the water reservoir 8 through an insulated pipe. The water reservoir 8 is connected to an external water source and stores cold water (tap water). A pump 9, such as a centrifugal pump, is installed on the insulated pipe between the circulation tank 1 and the water reservoir 8, so that the cold water in the water reservoir 8 can be pumped into the circulation tank 1 through the insulated pipe. A valve a is installed on the insulated pipe between the circulation tank 1 and the pump 9 to control the unblocking and closing of the insulated pipe. When the cold water in the water reservoir 8 is pumped into the circulation tank 1 through the insulated pipe, the valve a opens.

[0046] The circulation tank 1 is connected to the cooling pipeline 71 of each fermentation tank 7 through an insulated pipeline. A pump 9 is provided between the insulated pipelines connecting the circulation tank 1 and each cooling pipeline 71, so that the water in the circulation tank 1 can be circulated and pumped into the cooling pipeline 71 of each fermentation tank 7 through the insulated pipeline, and is used to take away the heat generated during the fermentation process of the fermentation tank 7. In addition, valves b and valves c are provided on the insulated pipelines between the circulation tank 1 and each cooling pipeline 71. When the water in the circulation tank 1 is circulated and pumped into the cooling pipeline 71 of each fermentation tank 7 through the insulated pipeline, valves b and valves c are opened, and valve g is closed. The water in the circulation tank 1 enters the cooling pipeline 71 after passing through valve b, and then returns to the circulation tank 1 through valve c.

[0047] Among them, the number of fermentation tanks 7 can be two or more, and the specific number can be set according to actual production needs. Multiple fermentation tanks 7 are connected in parallel to achieve continuous fermentation and carry out industrial large-scale fermentation production. The more parallel fermentation tanks 7 there are, the higher the waste heat utilization rate and recovery rate.

[0048] The circulation tank 1 is connected to the hot water storage tank 4 through an insulated pipe. A valve d and a pump 9 are provided on the insulated pipe between the circulation tank 1 and the hot water storage tank 4. When the water in the circulation tank 1 reaches the set temperature and the cooling effect decreases, the valve d can be opened to pump the water in the circulation tank into the hot water storage tank 4 through the insulated pipe. At this time, the valve g is closed.

[0049] A valve h and a pump 9 are provided at the bottom of the seed culture tank 6, and are connected to each fermentation tank 7 through an insulation pipe for cultivating Aspergillus niger fermentation strains. After the strains are cultivated, the valve h is opened and pumped into each fermentation tank 7 through the insulation pipe for fermentation.

[0050] Waste heat recovery mechanism

[0051] Heat collection and storage: The output end of each cooling pipeline 71 is also connected to the hot water storage tank 4 through an insulation pipe, and a valve g is provided on the insulation pipe between the cooling pipeline 71 and the hot water storage tank 4, so that when the temperature of the cooling water in the fermentation tank 7 rises to a set threshold after absorbing biological heat, the valve g opens and the hot water is automatically pumped to a special hot water storage tank 4. The storage tank is wrapped with insulation material and has a built-in heating pipe and thermometer, which can further heat the water to the temperature required for saccharification.

[0052] Heat energy transfer and application: The hot water storage tank 4 is connected to the insulation pipe 31 of the saccharification tank 3 through an insulation pipe, and a pump 9 is provided on the insulation pipe between the hot water storage tank 4 and the insulation pipe 31, so that the hot water in the hot water storage tank 4 is pumped into the insulation pipe 31 of the saccharification tank, so that the saccharification tank 3 is heated to the saccharification temperature, and then the hot water in the insulation pipe 31 flows back to the hot water storage tank 4 through the other end relative to the hot water pumping end. In the saccharification stage, these preheated hot water are used to heat the fermentation raw materials, promote their decomposition and saccharification process, thereby reducing the additional energy required for heating the saccharification process. The hot water accumulated in the hot water storage tank 4 can also be used for other purposes.

[0053] Auxiliary cooling system

[0054] In order to deal with the problem of insufficient cooling capacity of the circulation tank 1 in extreme cases, the system is also equipped with an independent circulation cold trap 2. The circulation cold trap 2 is connected to the cooling pipeline 71 of each fermentation tank 7 through an insulation pipe. A pump 9 and a valve f are arranged between the insulation pipes connecting the circulation cold trap 2 and each cooling pipeline 71, so that when the valve f is opened, the water in the circulation cold trap 2 can be circulated and pumped into the cooling pipeline 71 of each fermentation tank 7 through the insulation pipe. When the temperature of a fermentation tank 7 exceeds the set fermentation tank temperature threshold and needs to be cooled quickly during the fermentation process, the water refrigerated in the circulation cold trap 2 is taken from the circulation cold trap 2 for circulation cooling, providing additional cooling capacity for each cooling pipeline 71, and ensuring the accuracy and stability of the temperature control during the fermentation process. The circulation cold trap 2 is also connected to the water reservoir 8 through an insulation pipe provided with a valve e, so that when the valve e is opened, the water reservoir 8 can pump cold water into the circulation cold trap 2 through the insulation pipe to replenish the water in the circulation cold trap 2.

[0055] Residual sugar recovery and reuse:

[0056] After the citric acid extraction is completed, the remaining fermentation liquid often contains a certain amount of residual sugar. In order to further improve the resource utilization rate, the system is designed with a residual sugar recovery process, that is, these fermentation liquids rich in residual sugar are reintroduced into the raw material saccharification tank 3 after appropriate treatment, so as to achieve full reuse of sugar, reduce production costs, and reduce waste emissions. A valve is provided on the fermentation tank 7, and the fermentation mash storage tank 5 is connected to the valve on the fermentation tank 7 through an insulated pipe, and a pump 9 is provided on the insulated pipe between the fermentation mash storage tank 5 and the fermentation tank 7. When there are two fermentation tanks 7, a valve i and a valve j are provided at the bottom of the two fermentation tanks 7 respectively. The fermentation mash storage tank 5 is also connected to the saccharification tank 3 through an insulated pipe provided with a valve k, and a pump 9 is provided on the insulated pipe between the fermentation mash storage tank 5 and the saccharification tank 3. A valve l is provided on the top of the saccharification pipe. A valve m is provided at the bottom. Valve i and valve j are opened so that the fermented fermented liquid in the fermentation tank 7 can be introduced into the fermented mash storage tank 5 through the valve and the insulation pipe. After the citric acid in the fermentation liquid is extracted, valve k and valve l are opened to pump the remaining fermented liquid into the saccharification tank 3 through the insulation pipe for further saccharification to obtain raw materials. Valve m is opened to allow the saccharification tank 3 to dynamically replenish fermentation raw materials to each fermentation tank 7 during the fermentation process to enable it to continue fermentation. The fermentation tank 7 is connected to the saccharification tank 3 through an insulation pipe, and a pump 9 is provided on the insulation pipe. Valves, such as valve n and valve o, are provided on the pipe connecting each fermentation tank 7 and the saccharification tank 3. The valve switches are controlled separately according to the different conditions of each fermentation tank 7 to replenish materials to different fermentation tanks 7.

[0057] Specific example: The Aspergillus niger spores successfully cultured on the PAD plate medium were washed with sterile saline to prepare a 4×10 5 CFU / mL of bacterial suspension. The bacterial suspension was transferred to a seed culture tank and seed culture medium containing 12% total sugar and 0.4% total nitrogen was added. The stirring speed was maintained at 200r / min at 32°C, pH 4.0, and ventilation was maintained at 10m 3 / h, and culture continuously for 36 hours to obtain mature seed liquid. The pre-culture medium is added to each fermentation tank, the total sugar content of the pre-culture medium is 15%, and the total nitrogen content is 0.2%, and then the seed liquid is inoculated into the fermentation tank at an inoculation amount of 15% (v / v).

[0058] During the fermentation process, the stirring speed was maintained at 200r / min, the fermentation temperature was controlled at 43℃, the pH value was maintained at 4.0, and the ventilation volume was 9m 3 / h. After crushing, cleaning and sterilizing agricultural and sideline products such as corn cobs, rice husks, bagasse and fruit peels, they are placed in a saccharification tank, and sterile water and 0.5% cellulase and hemicellulase by weight of the raw materials are added. Enzymatic hydrolysis is carried out for 48 hours at 50°C and pH 4.5. When the citric acid concentration in the fermentation tank reaches 130g / L, the fermentation liquid is discharged to the fermentation mash storage tank, and at the same time, the feed matrix is ​​continuously added from the saccharification tank to the fermentation tank to maintain the volume balance of the fermentation liquid.

[0059] During the fermentation cycle of a batch of strains, the sugar conversion rate of the fermentation tank can exceed 98.2%, the fermentation cycle is less than 72 hours, the citric acid fermentation level is normal, and the enzymatic conversion rate of the saccharification tank reaches 67%.

[0060] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A heat recovery system based on Aspergillus niger fermentation, characterized in that: Including seed culture tanks, fermentation raw material saccharification tanks, fermentation tanks, fermentation mash storage tanks, circulating water storage tanks, hot water storage tanks, circulating cold wells, cooling pipelines, and water reservoirs; The circulating water storage tank is connected to a water reservoir through a pipeline, and the water reservoir is connected to an external water source and stores cold water therein, so that the cold water in the water reservoir is pumped into the circulating water storage tank through the pipeline; The circulating water storage tank is connected to the cooling pipeline of each fermentation tank through the insulation pipeline, so that the water in the circulating water storage tank is circulated and pumped into the cooling pipeline of each fermentation tank through the insulation pipeline; The seed culture tank is connected to each fermentation tank through a pipeline, and is used to culture Aspergillus niger fermentation strains, and the strains are pumped into each fermentation tank through an insulation pipeline; The output end of each cooling pipeline is also connected to a hot water storage tank through an insulation pipe, so that when the temperature of the cooling water in the fermentation tank rises to a set threshold after absorbing biological heat, the hot water is automatically pumped into the hot water storage tank; The hot water storage tank is connected to the insulation pipe of the saccharification tank through an insulation pipe, so that the hot water in the hot water storage tank is pumped into the insulation pipe of the saccharification tank, and the hot water in the insulation pipe flows back to the hot water storage tank through the other end opposite to the hot water pumping end.

2. A heat recovery system based on Aspergillus niger fermentation according to claim 1, characterized in that: The circulating water storage tank is connected to the hot water storage tank through an insulation pipe. After the water in the circulating water storage tank reaches a set temperature, the water in the circulating water storage tank is pumped into the hot water storage tank through the insulation pipe.

3. A heat recovery system based on Aspergillus niger fermentation according to claim 1, characterized in that: The hot water storage tank is equipped with a heating pipe and a temperature sensor, which can further heat the circulating water to the temperature required by the saccharification tank.

4. The heat recovery system based on Aspergillus niger fermentation according to claim 1, characterized in that: The system also includes a circulating cold trap, which is connected to the cooling pipeline of each fermenter through an insulated pipeline, so that water in the circulating cold trap can be circulated and pumped into the cooling pipeline of each fermenter through the insulated pipeline to cool the fermenter under special circumstances.

5. The heat recovery system based on Aspergillus niger fermentation according to claim 1, characterized in that: The system also includes a fermentation mash storage tank, which is connected to the fermentation tank through a pipeline, and the fermentation mash storage tank is also connected to the saccharification tank through a pipeline, so that the fermented liquid in the fermentation tank can be introduced into the fermentation mash storage tank through a valve and a pipeline, and the residual sugar that is not completely fermented in the fermentation mash storage tank can be pumped into the saccharification tank through the pipeline for further saccharification.

6. The heat recovery system based on Aspergillus niger fermentation according to claim 4, characterized in that: The fermentation tank is provided with an automatic control valve, and the fermentation mash storage tank is connected to the valve on the fermentation tank through a pipeline.

7. The heat recovery system based on Aspergillus niger fermentation according to claim 5, characterized in that: The pipelines are all wrapped with heat-insulating materials to reduce heat loss during waste heat recovery; pumps are provided on the heat-insulating pipelines between the fermentation mash storage tank and the saccharification tank; pumps are provided on the heat-insulating pipelines between the fermentation tank and the saccharification tank.

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