KR101553196B1 - Power generation system of organic rankine binary cycle - Google Patents

Abstract

The present invention relates to an organic rankine binary cycle power generation system capable of improving thermal efficiency through an ORC system, and comprising: a superheater for heating a fluid by heat exchanging with waste heat; a turbine for generating mechanical energy by receiving the fluid from the superheater; a generator connected with a power shaft of the turbine for generating electrical power; a condenser for accommodating the fluid in the state of gas and liquid passing through the turbine; a pump for pumping the fluid in the state of liquid inside the condenser; a buffer tank installed on a fluid line between the pump and the superheater for accommodating the fluid in the state of gas and liquid; a compressor connected with the power shaft of the turbine, connected with each branch line with respect to each of the condenser and the buffer tank, to suck in the fluid from the condenser by power of the turbine, and to supply the fluid to the buffer tank by pressing and heating the inhaled fluid; and an expansible valve installed in a bypass line for connecting the buffer tank and the condenser to forcibly vaporize the fluid flowing due to the pressure difference between the buffer tank and the condenser. The fluid is a single fluid for sharing a first cycle line where the turbine, the condenser, the pump, the buffer tank, and the superheater are followed in order, and a second cycle line where the compressor, the buffer tank, the expansion valve, and the condenser are followed in order.

Description

[0001] The present invention relates to an organic Rankine binary cycle generator system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic Rankine binary cycle power generation system, and more particularly, to an organic Rankine binary cycle power generation system in which an ORC and a heat pump cycle are shared by a single fluid to improve thermal energy efficiency.

The environment and energy industry in modern society is recognized as the most promising industry in the 21st century, and it is recognized as a major measure for evaluating national competitiveness.

In addition, modern society is aware of the necessity of developing and expanding renewable energy to replace fossil fuel energy as a way to solve the global warming problem faced.

Therefore, many countries recognize the new and renewable energy industry as a high value-added next-generation industry and continue to support the development of related industries.

Particularly, in the utilization of renewable energy, improvement of system efficiency is a major concern, and development of the technology is also attracting attention as a preliminary task.

As a part of these efforts, the technology of organic Rankine cycle technology using industrial waste heat or renewable energy has been studied for improving efficiency.

A typical Rankine cycle power generation system is a system that transforms shaft power generated by rotating a turbine into electric energy through a high pressure steam passing through an evaporator.

Conventional Rankine cycles use water as a working fluid and water is an efficient working fluid for high temperature heat sources. However, when the temperature of the heat source is moderate (70 ~ 400 ℃) It was difficult to apply it because of economic problems.

Organic Rankine Cycle (ORC) to overcome the problem of efficiency reduction of existing Rankine cycle which occurs when application of low-temperature heat source uses organic compound instead of water as fluid.

That is, the organic Rankine cycle power generation system is the same as the thermal power generation system but the power generation system using the organic mixture as the fluid.

The organic Rankine cycle is a system that produces electricity using a relatively low exergy low energy source unlike the existing Rankine cycle. Since it has to operate at a low energy source, the fluid must have a low boiling point and a high vapor pressure And it is relatively advantageous that the latent heat is small and the density is large in order to increase the mass flow rate of the inlet of the turbine.

In addition, the organic Rankine cycle is used as a bottoming cycle for recovering waste heat or arrangement generated mainly in an industrial process because the cycle efficiency is as low as about 10% by using a low-temperature heat source.

Since the organic mixture used as the fluid of the organic Rankine cycle has a low boiling point and is vaporized at a low temperature, it should be able to operate using a low-temperature arrangement, a solar heat, a geothermal heat, etc. The organic mixture mainly used is a freon- And hydrocarbon series materials such as propane and the like.

A typical organic Rankine cycle configuration may include a pump 18, a superheater 10, a turbine 12, and a condenser 16, as shown in the configuration of FIG. 1 and the operational diagram of FIG. Consists of.

The cycle of the fluid cycle consists of a compression process by the pump 18, an endothermic process in the superheater 10, an expansion process in the turbine 12, and a circulation cycle in the condenser 16.

More specifically, the superheated organic mixture at the outlet of the turbine 12 is condensed (②-③) in the condenser 16, as can be understood from FIGS. 1 and 2, (③-④) by a pump 18 in a saturated liquid phase.

Subsequently, the organic mixture, which has been subcooled by the compression of the pump 18, reaches the saturated vaporization temperature through the heat exchange with the heat source in the superheater 10 (④-⑤) ⑤-① process). The saturated steam organic mixture at the outlet of the superheater 10 is expanded in the turbine 12 and the expansion work resulting therefrom is converted into mechanical energy and the converted mechanical energy is supplied to the turbine 12 12 to generate electric power by driving the generator 14 connected thereto. The organic mixture at the outlet of the turbine 12 flows into the condenser in an overheated state and has a circulation process of repeating the process of condensing again.

The organic mixture is maintained in a superheated steam state, as opposed to being held in a two-phase state at the turbine outlet when water, the working fluid of the existing Rankine system, is expanded through the turbine at the point of saturation vapor. Therefore, the organic mixture can constitute a saturated cycle system in which less liquid droplets are generated in the turbines of the organic Rankine system, so that the stress on the rotating blade is reduced and the superheating area is not required at the outlet of the superheater.

However, to date, the organic Rankine cycle has not yet achieved such efficiency, and many studies and efforts have been focused on overcoming this.

Korean Registered Patent No. 10-1375536 (published on Mar. 17, 2014) Korean Registered Patent No. 10-1358309 (Announced on April 02, 2014)

As described above, the present invention has been devised to further increase the efficiency of the organic Rankine cycle. Specifically, the present invention can be shared by the organic Rankine cycle and the heat pump cycle in a single fluid, thereby reducing waste of heat, Thereby improving the efficiency of the power generation.

According to an aspect of the present invention, there is provided an organic Rankine binary cycle power generation system comprising: a superheater for heating a fluid by heat exchange with an array; A turbine that receives the fluid from the superheater and generates mechanical energy; A generator connected to a power shaft of the turbine to generate electric power; A condenser for receiving the gas passing through the turbine and the fluid in a liquid state; A pump for pumping the fluid in a liquid state in the condenser; A buffer tank installed on a fluid line between the pump and the superheater to receive the gas and the fluid in a liquid state; The condenser is connected to the power shaft of the turbine and connected to each of the condenser and the buffer tank through branch lines. The fluid is sucked from the condenser by the power of the turbine. The sucked fluid is compressed and heated, ; And an expansion valve installed at a bypass line connecting the buffer tank and the condenser to forcibly vaporize the fluid flowing at a pressure difference between the buffer tank and the condenser, The first cycle line, which is followed by the pump, the buffer tank, and the superheater, is a single fluid that shares the second cycle line that runs in the order of the compressor, the buffer tank, the expansion valve, and the condenser.

In addition, the turbine may be selected from a screw turbine, a positive displacement turbine, and a turbo turbine.

The generator and the compressor are connected to the power shaft of the turbine and are driven together.

In addition, it is preferable that the condenser is further connected to a cooling line for cooling the fluid in the gaseous state by heat exchange.

In addition, the condenser and the buffer tank may be configured such that a plurality of separation plates having a plurality of through holes are arranged in each of them in the vertical direction, and the plurality of separation plates delay the convection phenomenon of the received fluid It is preferable that the temperature distribution of the fluid in a gas and liquid state is divided into a plurality of layers.

According to the configuration of the present invention, a first cycle line of an ORC system in which fluid circulates in the order of a turbine, a condenser, a pump, a buffer tank, and a superheater; The second cycle line, which is a heat pump cycle circulating in the order of a compressor, a buffer tank, an expansion valve, and a condenser, is shared by a single medium. The buffer tank and the condenser, which are common components of the first and second cycle lines, In addition to reducing the losses, the compressor is also connected to the power shaft of the turbine to drive the turbine together to increase the efficiency of the mechanical energy, thereby improving the efficiency of the power generation.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow diagram of a conventional organic Rankine cycle according to the prior art.
Fig. 2 is a driving diagram of a general organic Rankine cycle. Fig.
3 is a schematic diagram for explaining a driving relationship of the organic Rankine binary cycle generation system according to an embodiment of the present invention.
4A to 4C are operation diagrams for explaining the energy efficiency relationship according to the organic Rankine binary cycle generation system of FIG.
FIG. 5 is a cross-sectional view for explaining the relationship in which a separator is installed in each of the condenser and the buffer tank based on the buffer tank of FIG. 3, and a working relationship therebetween.
FIG. 6 is a table showing the characteristics of fluids applied to the present invention. FIG.

The terms and words used in the present specification and claims should not be construed to be limited to ordinary or dictionary meanings, but the inventor may appropriately define the concept of the term to describe its invention in the best way Can be interpreted as meaning and concept consistent with the technical idea of the present invention.

It should be noted that the embodiments described in this specification and the configurations shown in the drawings are merely preferred embodiments of the present invention and do not represent all the technical ideas of the present invention, It should be understood that various equivalents and modifications may be present.

Prior to the description of the present invention, the organic Rankine binary cycle power generation system according to the present invention intends to improve the efficiency of power generation by recovering thermal energy from an arrangement discharged from an internal combustion engine or an industrial facility.

That is, the present invention contemplates to reduce the heat loss by suppressing the cooling for the condensation of the fluid as much as possible in comparison with the prior art, and to reuse the heat for power generation.

Therefore, the present invention excludes the application of the technique for cooling and cooling at room temperature or below, and the application to the technology for heating air-conditioning at room temperature or higher can be performed in parallel, but a detailed description thereof will be omitted.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 3, the organic Rankine binary cycle generation system according to the present invention includes a superheater 10 for recovering heat from an external facility to heat a fluid; A turbine 20 for converting the expansion energy of the heated fluid through the superheater 10 into mechanical energy for driving the generator 24; A condenser (28) for receiving the fluid passing through the turbine (20) in a gas and liquid state; And a pump 30 for supplying the liquid phase fluid in the condenser 28 to the superheater 10; Which is an ORC system sequentially connected in that order.

The organic Rankine binary cycle generation system according to the present invention further includes a buffer tank 32 connected to the fluid lines L5 and L5 'between the pump 30 and the superheater 10 to receive a predetermined amount of fluid )Wow; The turbine 20 is connected to the power shaft of the turbine 20 and connected to the condenser 28 and the buffer tank 32 by branch lines L6 and L7 respectively and is driven by the power of the turbine 20 to discharge the fluid from the condenser 28 A compressor 26 which sucks and compresses the refrigerant to a high temperature and a high pressure and supplies the compressed refrigerant to the buffer tank 32; And an expansion valve 34 installed in the bypass line L8 connecting between the buffer tank 32 and the condenser 28 and controlling the amount of fluid flowing from the buffer tank 32 to the condenser 28, ; And a second cycle section that is a heat pump cycle that follows the first cycle section in parallel with the first cycle section.

The fluid circulating through the first and second cycle intervals is not only the same but also mixed in each of the condenser 28 and the buffer tank 32 in which the first and second cycle sections share each other, And the buffer tank 32 are divided and separated according to the liquid-gas state and the temperature deviation.

Accordingly, the present invention provides a binary cycle structure by connecting the first and second cycle sections in parallel and in a mixed relationship to form respective circulation structures.

Hereinafter, each configuration of the present invention will be described in more detail.

First, the superheater 10 is connected to an arrangement line H which is discharged from an internal combustion engine or an industrial facility, and receives heat from the arrangement line H by heat exchange to take charge of the fluid received therein.

Here, it is assumed that the heat source flowing through the above-described array line H among the operating conditions for the application of the present invention is equal to or higher than the heating temperature of the fluid already set in the superheater 10. For example, as described later, it is presumed that the heating temperature of the fluid in the superheater 10 is in the range of 85 to 120 ° C, and that the abnormal temperature condition is satisfied. The temperature shown as an example is based on the fluid R245fa having the characteristics identified in Fig.

The turbine 20 functions to expand the saturated fluid supplied through the fluid line L1 connected to the superheater 10 and convert the fluid into mechanical energy.

In this case, the pressure deviation in the first and second cycle sections is small and the temperature deviation due to the phase transformation of the fluid in the first and second cycle sections is also small, so that the operation in the first and second cycle sections including the turbine 20 Phase transformation of fluid as a medium can coexist.

Therefore, it is preferable that the turbine 20 be applied to a screw type inflator (screw type turbine) or a positive type inflator (positive type turbine) rather than a turbo type inflator (turbo type turbine) using a blade.

That is, as described later, the fluid to be applied to the present invention has a saturated vapor pressure in the range of 2.5 to 6.0 bar, a liquid enthalpy in the range of 250 to 295 kJ / kg and a vapor enthalpy in the range of 430 - In an organic fluid having a saturation vapor pressure ranging from 9.0 to 19.0 bar, a liquid enthalpy ranging from 320 to 370 kJ / kg and a gas enthalpy ranging from 470 to 485 kJ / kg in the temperature range of 45 to 455 kJ / kg, It is a selected type.

Accordingly, the fluid in the high temperature range of 85 to 120 DEG C in the turbine 20 can coexist in a liquid state.

When the fluid in the liquid state expands at a high pressure together with the fluid in the gas state, the fluid collides with the blade of the turboexpander, and the shock may cause problems in the durability and drive stability of the turbine including the blades to be.

Of course, if the fluid can maintain a sufficiently dry steam condition at the inlet of the turbine 20, a turboexpanding inflator with higher efficiency than a screw type inflator or a positive displacement inflator can be applied.

In addition, a generator 24 is connected to the power shaft 22 of the turbine 20 to generate electric power using the mechanical energy generated by the driving of the turbine 20.

Since the generator 24 may have various applications, a detailed description thereof will be omitted.

The power shaft 22 of the turbine 20 described above is driven by the mechanical energy generated by the drive of the turbine 20 in addition to the generator 24 so that it is connected to the condenser 28 And sucks the fluid in the condenser 28 through the branch pipe L6 and compresses and heats the sucked fluid and transfers it to the inside of the buffer tank 32 through the branch pipe L7 connected to the buffer tank 32, A compressor 26 is connected.

As described above, this compressor 26 performs a series of processes of sucking gaseous fluid in the condenser 28, compressing and heating the sucked fluid, and supplying the compressed fluid to the buffer tank 32.

The turbine 20 and the generator 24 and the compressor 26 are connected by the power shaft 22 of the turbine 20 and the generator 24 and the compressor 26 are driven by the turbine 20 And is supplied with power.

On the other hand, the condenser 28 receives and receives the gaseous state and the heated liquid state fluid from the turbine 20 from the condenser 28.

The condenser 28 in the present invention does not require a cooling line (C) or fan (not shown) configuration for forcibly removing the condensation heat to condense the fluid in the gaseous state.

In other words, the inside of the condenser 28 forms a low pressure by discharging the gaseous fluid through the branch line connected to the compressor 26 described above, and the applied organic fluid has a boiling point in the range of 40 to 70 ° C And the natural condensation takes place in the course of flow through the fluid line L2 between the turbine 20 and the condenser 28 as well as the temperature deviation is smaller than the expansion temperature of 85 to 120 ° C It is because.

Above all, the direct cooling action for condensing the fluid in the condenser 28 is such that the expansion valve 34, which will be described later, forces the fluid flowing from the buffer tank 32 to the condenser 28 along the bypass line L8, .

Therefore, the basic configuration for forcibly recovering the condensation heat of the fluid in the condenser 28 is the expansion valve 34, and the above-described cooling line C or the fan assists the expansion valve 34 for condensing the fluid, It is preferable to install it for accurate control.

The temperature inside the condenser 28 is controlled by the temperature of the refrigerant flowing through the expansion valve 34 through the cooling operation resulting from the forced vaporization of the fluid through the expansion valve 34 and the driving control of the cooling line C or the fan It is preferable to adjust the boiling point to be in the range of 40 to 70 占 폚.

As shown in Fig. 5, the condenser 28 is formed by arranging a plurality of plate-shaped separator plates 28a having a plurality of through holes therein in the vertical direction.

The plurality of separator plates 28a delays the flow of the liquid phase fluid in the condenser 28 through the through holes and smoothes the flow of the gas phase fluid so as to prevent convection of the liquid phase fluid contained in the condenser 28 So that the temperature distribution of the fluid is differentiated by the position interval of the separation plates 28a.

The fluid in the gaseous state in the fluid flowing from the turbine 20 through the fluid line L2 into the condenser 28 is located at the top of the condenser 28 and the fluid in the liquid state is introduced into the lower portion of the condenser 28 And a temperature deviation is formed in units of intervals of the separation plates 28a.

The branch line L6 connected to the compressor 26 described above corresponds to the position of the fluid in the gaseous state above the condenser 28 at the end thereof and is connected to the inside of the condenser 28 So that the pressure inside the condenser 28 is relatively lower than that of the fluid line L2.

In the present invention, the pump 30 sucks the condensed liquid fluid inside the above-described condenser 28 and pressurizes the liquid to a predetermined pressure in the direction of the superheater 10.

A buffer tank 32 is provided between the pump 30 and the fluid lines L4 to L5 leading to the superheater 10 for temporarily storing the flow of the fluid.

In the buffer tank 32, as in the condenser 28 described above with reference to FIG. 5, the fluid contained therein is separated into a gas and a liquid state, and at the same time, a difference in the temperature distribution of the fluid in the up- The separation plate 32a is provided.

According to the separation plate 32a inside the buffer tank 32, the gaseous fluid is located at the upper portion of the buffer tank 32 and the liquid-phase fluid is positioned at the lower portion of the buffer tank 32 by its own weight.

The high temperature and high pressure fluid supplied from the compressor 26 is supplied to the buffer tank 32 through the connection of the connected branch line L7 and flows into the buffer tank 32 through the connection of the connected branch line L7, Diluted and heat exchanged.

The portion of the buffer tank 32 where the fluid supplied from the compressor 26 and the fluid supplied from the pump 30 are exchanged is located at the upper portion of the fluid tank in the fluid tank, As shown in Fig. 5, since the convection is suppressed by the separation plates 32a, it is preheated to a higher temperature than the liquid in the upper or lower liquid state.

The fluid line L5 leading from the buffer tank 32 to the superheater 10 is installed in correspondence with the fluid in the relatively high temperature state through the above described preheating process among the buffer tanks 32. [

The preheating temperature of the fluid supplied to the superheater 10 is used to stably form the heating efficiency of the fluid through the superheater 10 and is set so that the saturation before the expansion by the superheater 10 The fluid temperature is in the range of 85 to 90% of the temperature of the fluid in the saturated state of the fluid.

Such a preheating temperature of the fluid creates an effect of forming and maintaining more stably in the case where the heating temperature of the fluid through the superheater 10 is unstable.

Further, the pressure of the fluid introduced by the pump 30 and the compressor 26 is increased in the buffer tank 32, and the gaseous fluid coexists.

Therefore, the buffer tank 32 needs to be adjusted so that the pressure is already set. To this end, a bypass line L8 (hereinafter, referred to as " L8 ") for guiding the liquid in the buffer tank 32 to the condenser 28 ) Is installed.

The bypass line L8 is provided with an expansion valve 34 for forcibly vaporizing the fluid flowing in the buffer tank 32 and the pressure difference in the inside of the condenser 28 to inject the fluid into the condenser 28, Respectively.

That is, the fluid forced to be vaporized by the expansion valve 34 cools the inside of the condenser 28 to condense the fluid flowing from the turbine 20.

As described above, the present invention includes a first cycle line, which is an ORC system connected in the order of a turbine 20, a condenser 28, a pump 30, a buffer tank 32 and a superheater 10, a compressor 26, The second cycle line, which is a heat pump system that continues in the order of the buffer tank 32, the expansion valve 34 and the condenser 28, shares a single fluid and the turbine 20 and the compressor 26 are connected by a power shaft The first and second cycle lines are interlocked with each other.

Further, the condenser 28 described above functions as a general condenser for condensing the fluid in the first cycle line, and the condenser 28 in the second cycle line functions as an evaporator.

The buffer tank 32 functions as an evaporator for assisting the superheater 10 in the first cycle line to evaporate the fluid and simultaneously functions as a condenser in the second cycle line.

Accordingly, the organic Rankine binary cycle power generation system according to the present invention simultaneously operates the ORC system and the heat pump system using a single organic fluid to reduce heat energy loss.

The power generation efficiency relation therebetween can be calculated as shown in FIG. 4A by using the efficiency (W1) according to the first cycle line which is the organic Rankine cycle (ORC system) with reference to the saturated steam curve as the dotted line, , The efficiency W2 according to the second cycle line as the heat pump cycle is made. Considering that these efficiencies W1 and W2 overlap with each other, as shown in Fig. 4C, do.

10: superheater 12, 20: turbine
14, 24: generator 16, 28: condenser
18, 30: Pump 22: Power shaft
26: compressor 32: buffer tank
34: Expansion valve

Claims (5)

A superheater for heating the fluid by heat exchange with the array;
A turbine that receives the fluid from the superheater and generates mechanical energy;
A generator connected to a power shaft of the turbine to generate electric power;
A condenser for receiving the gas passing through the turbine and the fluid in a liquid state;
A pump for pumping the fluid in a liquid state in the condenser;
A buffer tank installed on a fluid line between the pump and the superheater to receive the gas and the fluid in a liquid state;
The condenser is connected to the power shaft of the turbine and connected to each of the condenser and the buffer tank through branch lines. The fluid is sucked from the condenser by the power of the turbine. The sucked fluid is compressed and heated, ; And
And an expansion valve installed on a bypass line connecting the buffer tank and the condenser to forcibly vaporize the fluid flowing due to a pressure difference between the buffer tank and the condenser,
Characterized in that the fluid is a single fluid that shares a first cycle line that runs in the order of the turbine, the condenser, the pump, the buffer tank, and the superheater, and the second cycle line that runs in the order of the compressor, buffer tank, expansion valve, Rankine binary cycle generation system. The method according to claim 1,
Wherein the turbine is one of a screw turbine, a positive turbine, and a turbo turbine. The method according to claim 1,
Wherein the generator and the compressor are connected to a power shaft of the turbine and are driven together. The method according to claim 1,
Wherein the condenser is further connected to a cooling line for cooling the fluid in a gaseous state by heat exchange. The method according to claim 1,
Wherein the condenser and the buffer tank are formed by arranging a plurality of separating plates having a plurality of through holes in each of them in the vertical direction at an interval,
Wherein the plurality of separation plates delays convection of the received fluid and separates the temperature distribution of the fluid in a gas and liquid state into a plurality of layers.

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