Circulation-type small hydro energy conversion system having open-to-atmosphere free water surface

Abstract

The present invention relates to a circulation-type small hydro energy conversion system for converting, into electric energy, head energy formed by a height difference in a gravitational field in a high-rise structure or a power generation facility. The present invention comprises: a drop pipe (10) that extends vertically to form a drop section; one or more pump pipes (20) that communicate with the drop pipe to form a liquid circulation structure; a pump (30) that is disposed above the pump pipes and transfers a fluid to the drop pipe, thereby generating or maintaining a circulation flow rate; a turbine (41) that is disposed below the drop pipe and rotated by an effective head (H_eff) formed between a turbine inlet and a turbine outlet; and a generator (40). A free water surface (a pressure reference surface) open to the atmosphere is formed in the upper portion of the liquid circulation structure, provides a pressure / head reference and boundary conditions for the system, and allows the pressure and head distributions in a pipeline to be defined on the basis of the reference surface during a circulation operation.

Description

Circulating small hydropower energy conversion system equipped with an open free surface

[0001] The present invention relates to a circulating small hydroelectric energy conversion system that converts the head energy of a fluid into electrical energy using a vertical drop section formed in a high-rise structure or power generation facility.

[0002] In general, due to the increase in electricity demand from data centers, artificial intelligence (AI), and electric vehicles (EVs), there is a growing need to reduce dependence on fossil fuel-based power generation and expand the use of eco-friendly and distributed energy sources.

[0003] Accordingly, a review is underway regarding distributed power supply structures, such as microgrids and self-generation, as well as energy self-sufficiency technologies at the building and facility level.

[0004]

[0005] Meanwhile, despite the increasing height of urban buildings, renewable energy sources applied to high-rise structures are often skewed toward methods dependent on external environmental conditions, such as solar and small-scale wind power; consequently, there are limitations in securing a stable, continuous power source due to output fluctuations (intermittency) and installation environment constraints.

[0006] Accordingly, attempts have been proposed to implement small-scale hydropower generation using the vertical head (water head) secured from high-rise structures; however, there is a need for improvement in terms of application scope and operational continuity, as these methods rely on limited flow sources (such as domestic sewage and wastewater) or are skewed toward storage and discharge methods based on external power sources.

[0007] Therefore, in order to stably achieve effective head in high-rise structures or power generation facilities, a circulating small hydropower energy conversion system is required that forms an atmospheric open free surface (pressure reference surface) at the top of the liquid circulation structure to clarify the reference and boundary conditions for pressure and head, and simultaneously forms and maintains a circulating flow rate (operating point) by pump operation, while controlling head distribution so that a differential pressure corresponding to the effective head (H_eff) is stably formed at the lower end of the drop pipe and before and after the turbine.

[0008] In conventional hydroelectric dam-based power generation systems, the upstream reservoir water surface naturally provides a pressure reference plane open to the atmosphere, and since the outlet boundary conditions on the downstream side of the turbine are provided externally by the spillway and downstream water level, the setting of the head (water head) and operating point (flow rate) is relatively clear.

[0009] On the other hand, when operating in a circulating manner by applying the principle of head drop to the vertical space of high-rise structures or power generation facilities, the downstream outlet boundary conditions and head loss distribution can be formed and fluctuate within the system along with the setting of the upper pressure reference plane; therefore, an engineering configuration is required to stably secure and maintain the effective head (H_eff) recoverable from the turbine. Furthermore, in systems including a circulating structure, due to the geometric characteristic that the turbine outlet is connected to the return path, there is a possibility that downstream pressure conditions may be interpreted as a factor limiting power generation performance.

[0010] Accordingly, the objective of the present invention is to provide a circulating small hydroelectric energy conversion system capable of stable securing of an effective head (H_eff) at the bottom of the drop pipe and continuous operation by forming an open free surface (pressure reference surface) at the top to provide a pressure reference inside the system and forming the downstream pressure conditions (outlet boundary conditions) of the turbine according to the operating point (flow rate) and head loss distribution.

[0011] Furthermore, the objective of the present invention is to provide scalability and applicability of the system configuration so that it can be applied not only within buildings but also to various installation environments, such as separate power generation towers and vertical drop structures within industrial facilities.

[0012] To achieve the above objective, a circulating small hydropower energy conversion system according to one embodiment of the present invention comprises a drop pipe (10) that extends in a vertical direction to form a drop section, and one or more pump pipes (20) configured to communicate with the drop pipe (10) to allow fluid to circulate, and a liquid circulation structure.

[0013] A free surface (pressure reference surface) open to the atmosphere is formed at the top of the above liquid circulation structure, and the free surface acts as a reference surface providing pressure and head references and outlet boundary conditions inside the system.

[0014] Accordingly, during circulation operation, the downstream pressure conditions (outlet boundary conditions) of the turbine (41) can be formed according to the distribution of the operating point (flow rate) and head loss (friction loss and local loss) based on the pressure reference plane, and as a result, the effective head (H_eff) formed at the front and rear ends of the turbine (41) can be stabilized.

[0015] Additionally, the liquid circulation structure can be configured to form a continuous flow when the fluid is filled inside the pipe (primed condition), and by standardizing the suction side pressure condition by the free surface and linking the pressure distribution and head loss distribution according to the downward flow in the drop pipe (10), the pump (30) can be designed to form and maintain a circulation flow rate in a range where the required head is reduced according to the pipe configuration and operating conditions.

[0016] The above pump (30) includes a pump body (31) and a drive motor (32).

[0017] A pump (30) is disposed in the above pump pipe (20) to transfer fluid to the drop pipe (10) to form or maintain a circulating flow rate, and a discharge pipe (23) may be connected to the discharge side of the pump (30).

[0018] At the lower part of the above drop pipe (10), a turbine (41) that rotates due to the total head difference, i.e., the effective head (H_eff), formed at the front and rear ends of the turbine with respect to the fluid passing through the drop pipe (10), and a generator (40) connected to the turbine (41) to generate power are arranged.

[0019] Depending on the embodiment, a section where the pipe diameter changes, for example, a speed increase section (11), may be optionally formed in the lower part of the drop pipe (10).

[0020] Additionally, an inlet pocket (12) providing an inlet space to allow fluid flowing from the discharge side of the pump (30) to flow smoothly into the drop pipe (10) may be optionally formed at the upper inlet of the drop pipe (10), and a sump (50) for temporary storage of fluid during maintenance or operation management may be optionally provided.

[0021] According to the present invention, since the head energy of a fluid can be converted into electrical energy by utilizing the vertical drop section of a high-rise structure or power generation facility, it is possible to configure self-generation at the facility level and reduce dependence on external power.

[0022] In addition, since the present invention can form and adjust the circulation flow rate (operating point) as needed through pump operation, it provides operational flexibility that enables operation, shutdown, or output adjustment according to load conditions and power demand.

[0023] Accordingly, it becomes easier to respond to power peaks, optimize self-consumption, and manage energy. By reducing unnecessary continuous operation, power consumption associated with pump driving can be directly reduced, thereby contributing to the reduction of energy usage and the associated greenhouse gas emissions.

[0024] In addition, since it can be installed by utilizing vertical space within the structure or existing structures, it reduces the burden of securing a separate large site and can contribute to cost reduction in terms of installation and maintenance.

[0025] In addition, since the drop pipe length, conduit configuration, and operation control conditions can be modified and applied according to the installation environment (high-rise structures, power towers, industrial facilities, etc.), it can be flexibly utilized in distributed power configurations of various sizes.

[0026] Figure 1 is a conceptual diagram showing (i) a state in which the water levels on both sides are in equilibrium with respect to a free surface open to the atmosphere in a U-shaped pipe structure, and (ii) a state in which a pressure head (hydrostatic pressure) equivalent to H is formed at the bottom by the height (H) of the vertical continuous water column, thereby providing a physical basis for utilizing the drop corresponding to the reservoir water level difference of a typical hydroelectric dam.

[0027] FIG. 2 is a schematic diagram showing the overall configuration of a circulating small hydropower energy conversion system according to one embodiment of the present invention.

[0028] FIG. 3 is a diagram showing the arrangement relationship of a drop pipe (10), a pump pipe (20), a pump (30), and a generator (40) according to one embodiment of the present invention.

[0029] FIG. 4 is a drawing showing an application example in which a system according to one embodiment of the present invention is installed in the core space of a high-rise structure.

[0030] FIG. 5 is a conceptual diagram illustrating the operating (flow state) principle of the present invention (pressure reference plane of the free water surface, formation of circulating flow rate, energy conversion at the bottom of the drop pipe).

[0031] In the following, preferred embodiments of the present invention will be described in detail based on the details illustrated in the drawings; however, specific descriptions of related known functions or configurations will be omitted if it is determined that such descriptions may unnecessarily obscure the essence of the present invention.

[0032] Conventional hydroelectric power generation (e.g., hydroelectric dams) uses the free surface of the reservoir (open to the atmosphere) as the pressure reference plane to form a drop (head) corresponding to the height difference between the upstream water level and the turbine installation height, and recovers power using the effective head realized as pressure head at the turbine inlet through a pressure pipe. In other words, in conventional hydroelectric power generation, the free surface provides the reference point for head calculation, and the drop section serves as the source of effective head recoverable by the turbine.

[0033] Furthermore, in conventional hydroelectric power generation, the outlet head conditions (pressure conditions) at the turbine outlet side are formed by the tailrace, downstream water level, and outlet structure, and are treated as design factors that affect the distribution of effective head and flow rate stabilization, along with head loss such as pipe friction and local losses.

[0034] Therefore, the pressure condition at the turbine outlet is understood not as a concept where the effective head is automatically eliminated solely by the shape, but as a boundary condition that determines the head distribution before and after the turbine while stabilizing the flow.

[0035] However, when applying the principle of utilizing head in conventional hydroelectric power generation to the vertical space of high-rise structures or power generation facilities, the effective head recoverable by the turbine may vary depending on the setting of the upper pressure reference plane, the formation of outlet head conditions (downstream pressure conditions) in the circulation or return path, and the distribution of head loss. In particular, in systems including a circulation structure, there is a possibility of misconception that the effective head is eliminated due to the geometric reason that the turbine rear end is connected to an upward path; however, in steady-flow fluid machinery analysis, the turbine recovery head is defined as the total head difference (ΔH_total) between the turbine inlet and outlet.

[0036] In this specification, the effective head (H_eff) refers to the total head difference (ΔH_total) between the turbine inlet and outlet, and ΔH_total is referred to as H_eff consistently below. The total head refers to the energy head expressed as the sum of the pressure head (p / ρg), velocity head (v² / 2g), and position head (z) defined with respect to a reference plane. The turbine reduces the total head and extracts energy equivalent to the reduction as mechanical work, which is then converted into electrical energy in a generator.

[0037] Therefore, the pressure conditions at the turbine outlet are outlet boundary conditions similar to the discharge or downstream water level conditions in conventional hydroelectric power generation, and are formed according to the operating point (flow rate) and head loss distribution, thereby determining the effective head (H_eff) formed at the turbine outlets.

[0038] In the present invention, the pump forms and maintains a pressure disequilibrium between the upper pressure reference plane and the downstream outlet boundary conditions through circulating flow, and accordingly, the operating point (flow rate) and head loss distribution are determined so that the effective head (H_eff) at the front and rear ends of the turbine is established.

[0039] Therefore, the present invention is not a configuration that generates or amplifies energy from the outside, but rather a device that recovers the reduction corresponding to the total head difference between the turbine's upstream and downstream ends, i.e., H_eff, among the energy head defined according to the steady-state energy equation, as mechanical work and converts it into electrical energy.

[0040] In addition, the circulating operation of the present invention is based on the premise that a circulating flow rate (operating point) is formed and maintained by a pump (30), and energy recovery in the turbine (41) is determined by the total head difference between the upstream and downstream ends of the turbine, i.e., the effective head (H_eff). The pump (30) includes a pump body (31) and a drive motor (32).

[0041] Accordingly, the present invention is a fluid machine system that converts head energy into electricity under operating conditions set by external power (pump input), and can be analyzed and designed to satisfy the relationship between pump head, turbine recovery head, and head loss in the steady-state energy equation.

[0042] Conventional pumped storage or pump transfer systems require pump power corresponding to the required head to transfer fluid upward, and pump operating limits (NPSH, cavitation, etc.) can become an issue depending on suction pressure conditions and pipeline losses.

[0043] In contrast, the present invention allows a liquid circulation structure formed by a drop pipe (10) and a pump pipe (20) to operate in a state filled with fluid (primed condition), and by forming a free surface (pressure reference surface) open to the atmosphere at the top, the pressure reference and boundary conditions of the system are clearly established. In this configuration, the section where the downward flow is formed on the drop pipe (10) side affects the pressure distribution and flow rate formation of the circulation system, and consequently, the pump (30) can be designed to form and maintain a circulation flow rate within a required head range determined by the operating point (flow rate) and head loss distribution, rather than overcoming the hydrostatic pressure corresponding to the entire vertical height in a single manner.

[0044] Accordingly, the present invention provides a system configuration that improves pump operation stability by utilizing upper free surface boundary conditions and head distribution of the circulation system, and can reduce the pump head required depending on the application environment.

[0045] The specific configuration of the present invention will be described below.

[0046] (1) Drop pipe (10) and speed increase section (11)

[0047] The drop pipe (10) is installed vertically within a structure or power generation facility and is preferably positioned to extend from the top to the bottom. The drop pipe (10) may be made of a cylindrical pipe, and depending on the embodiment, a section where the pipe diameter changes to change the flow characteristics of the fluid passing through the turbine (41), such as a speed-increasing section (11), may be optionally formed at the bottom of the drop pipe (10). However, the speed-increasing section (11) is not an essential component and may be omitted depending on the installation conditions and design purpose.

[0048] (2) Pump pipe (20), lower connecting pipe (22), inlet pocket (12)

[0049] The pump pipe (20) forms a liquid circulation structure together with the drop pipe (10), is arranged vertically to extend from the top to the bottom at an adjacent location to the drop pipe (10), and its upper and lower ends are respectively connected to the drop pipe (10) to enable the movement of liquid. The lower end of the pump pipe (20) is connected to the drop pipe (10) by a lower connecting pipe (22). Multiple pump pipes (20) may be installed radially around the drop pipe (10), or may be arranged symmetrically depending on the embodiment. The inlet pocket (12) is configured to provide an inlet space at the upper inlet of the drop pipe (10) so that fluid flowing in from the discharge side of the pump (30), for example, the discharge pipe (23), can be smoothly drawn into the inside of the drop pipe (10), and may be formed selectively depending on the embodiment.

[0050] (3) Upper free surface (pressure reference surface)

[0051] A free surface (pressure reference surface) open to the atmosphere is formed at the top of the liquid circulation structure. The free surface provides reference conditions and outlet boundary conditions for the internal pressure and head distribution of the system, and during circulation operation, the pressure conditions downstream of the turbine (41) can be formed according to the operating point (flow rate) and head loss distribution based on the reference surface.

[0052] Accordingly, operating conditions can be set so that a differential pressure corresponding to the effective head (H_eff) is formed at the front and rear ends of the turbine (41).

[0053] Depending on the embodiment, a cover may be installed on the upper part to prevent the ingress of foreign matter, but the upper space may be configured to be in communication with the atmosphere to maintain free water surface boundary conditions.

[0054] (4) Pump (30) and discharge pipe (23)

[0055] The pump (30) is configured to transfer fluid filled in the pump pipe (20) to form and maintain a circulating flow rate. The pump (30) includes a pump body (31) and a drive motor (32).

[0056] A discharge pipe (23) is connected to the discharge side of the pump (30) to guide the fluid transported by the pump (30) to the drop pipe (10), and a plurality of pumps (30) may be provided so that a pump (30) is installed in each of the plurality of pump pipes (20).

[0057] (5) Turbine (41) and generator (40)

[0058] The generator (40) produces electricity by converting the head energy of the fluid moving through the drop pipe (10) into electrical energy, and is configured to generate power by the rotational force of the turbine (41) by being connected to a turbine (41) located at the inner lower part of the drop pipe (10). The shaft extending from the turbine (41) can be configured to extend outward by penetrating the lower end of the drop pipe (10), and the rotational force of the shaft can be transmitted to the generator (40).

[0059] (6) Catch basin (50)

[0060] A sump (50) may be provided around or below the system to temporarily store internal fluid during inspection or maintenance.

[0061] (7) Installation example and operation description

[0062] The system can be installed in the core space of a high-rise structure, for example, an elevator hall, and the drop pipe (10) and pump pipe (20) extend from the top to the bottom, and the pump (30) can be installed in the upper part and the generator (40) can be installed in the lower part.

[0063] When the pump (30) operates and the fluid in the pump pipe (20) is transferred to the drop pipe (10) side through the discharge pipe (23), a difference in water level and pressure distribution can be formed and maintained between the drop pipe (10) and the pump pipe (20) while the pump operation continues, and accordingly, the fluid in the drop pipe (10) flows into the pump pipe (20) side through the lower connecting pipe (22), thereby forming a circulating flow.

[0064]

[0065] (Details of the circulation mechanism)

[0066] The circulation operation of this system can be explained by the head distribution of the circulation system formed by the upper free water surface (pressure reference surface) and the drop pipe (10) and pump pipe (20).

[0067] (a) Formation of the driving point

[0068] A circulating flow rate (operating point) is formed by the pump (30) transferring the fluid inside the pump pipe (20) to the drop pipe (10) side through the discharge pipe (23).

[0069] (b) Pressure criteria and boundary conditions

[0070] A free surface with its upper end connected to the atmosphere provides a reference for pressure within the pipeline, and during circulation operation, the pipeline pressure and head distribution are determined along with head loss (friction loss and local loss) based on the above reference surface.

[0071] (c) Interlocking of downdrafts and updrafts

[0072] A downward flow can be formed in the drop pipe (10) and an upward flow can be formed in the pump pipe (20), and the flow rate and pressure conditions of these are continuously maintained and controlled by the operating conditions of the pump (30) and the pipe configuration.

[0073] (d) Energy recovery

[0074] At the bottom of the drop pipe (10), a total head difference, i.e., an effective head (H_eff), can be formed between the inlet and outlet of the turbine (41), and the turbine (41) reduces the total head and converts mechanical work corresponding to the reduction into electrical energy through the generator (40). The turbine (41) at the bottom of the drop pipe (10) rotates due to the flow of fluid passing through the drop pipe (10) and the head energy, and the rotational force is transmitted to the generator (40) to produce electricity.

[0075] The system converts the head energy in the drop pipe (10) into electrical energy through the turbine (41) while forming or maintaining a circulating flow rate (operating point) by the pump (30), and when the operation of the pump (30) is stopped, the circulating flow rate and output conditions may change.

[0076] That is, in this system, the operation of the pump (30) acts as an external input to form and maintain the circulating flow rate, and the energy recovered from the turbine (41) is determined according to the effective head (H_eff) formed at the operating point and pipe loss conditions.

[0077] Therefore, the energy balance of the system, including pump input, turbine recovery, and pipeline losses, can be evaluated within a steady-flow fluid machinery analysis framework.

[0078]

[0079] The embodiments described above are exemplary, and those skilled in the art may implement the present invention in other specific forms without changing the technical concept or essential features of the invention.

[0080] Accordingly, the scope of the present invention should be determined by the claims set forth below rather than by the foregoing detailed description, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

Claims

1. A drop pipe (10) installed in a vertical position on a high-rise structure or power generation facility to form a drop section; One or more pump pipes (20) having their upper and lower ends respectively connected to the drop pipe (10) so as to be arranged around the drop pipe (10) to form a liquid circulation structure together with the drop pipe (10); One or more pumps (30) installed on the upper part of the pump pipe (20) to transfer the liquid of the pump pipe (20) to the drop pipe (10) through the discharge pipe (23) to form or maintain a circulating flow rate; and A turbine (41) that rotates by an effective head (H_eff) formed between the inlet and outlet of the turbine (41) with respect to the liquid passing through the above-mentioned drop pipe (10), and one or more generators (40) connected to the turbine (41) to generate power; comprising A circulating small hydropower energy conversion system characterized by having a free surface (pressure reference surface) open to the atmosphere formed at the top of the above liquid circulation structure, wherein the pressure and head distribution within the pipeline during circulation operation are set based on the above free surface, and the downstream pressure conditions of the turbine (41) are configured to be formed according to the operating point (flow rate) and head loss distribution.

2. In Paragraph 1, A circulating small hydropower energy conversion system characterized in that the plurality of pump pipes (20) are arranged radially around the drop pipe (10).

3. In Paragraph 1, A circulating small hydroelectric energy conversion system characterized in that the above-mentioned drop pipe (10) further includes a speed-increasing section (11) in which the pipe diameter narrows to increase the flow velocity of the liquid passing through the turbine (41).

4. In Paragraph 1, A circulating small hydroelectric energy conversion system characterized in that a free surface (pressure reference surface) open to the atmosphere is formed at the top of the above liquid circulation structure, and when the pump (30) is operated, the liquid in each pump pipe (20) is transferred to the drop pipe (10) through the discharge pipe (23).

5. In Paragraph 1, A circulating small hydroelectric energy conversion system characterized in that the above drop pipe (10) and the above pump pipe (20) are installed to extend from the top to the bottom within the core and elevator hall of a high-rise structure.

6. In Paragraph 1, The above liquid circulation structure is configured to form a continuous flow while the fluid fills the inside of the pipe, and the suction side pressure condition is standardized by a free surface (pressure reference surface) open to the upper atmosphere, and the downward flow in the drop pipe (10) and the upward flow in the pump pipe (20) are configured to be linked, thereby configuring the required head of the pump (30) during circulation operation to be set according to the operating point (flow rate) and head loss distribution.

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