JPS61212611A - Energy conversion system - Google Patents

Abstract

PURPOSE:To provide for oneself a considerable part of the enthalpy increase in a Rankine cycle heating caporization process by the heat transfer between a Rankine cycle and the cooling and heating cycles installed outside the Rankine cycle. CONSTITUTION:In cooling and temperature raising cycle, the fluid which flows in a circulation passage is pressurized by a compression pump P-2 and jetted out of the nozzle of a jet pump JP-1. Therefore, the low-pressure gas which recovers heat from the fluid on a Rankine cycle side by a low-pressure heat exchanger E-1 and is heated by a superheater E-5 is inhaled through a conduit connected to the low pressure side, and mixed with the high-pressure liquid jetted out of the nozzle and forms high-pressrue liquid. Since heat is transferred to the Rankine cycle side fluid by high-pressure heat exchangers E-3 and E-2, the input calorific heat of the external energy by a heat exchanger E-4 for temperature rise can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to energy conversion systems for extracting thermal energy in the form of rotation or electrical power, such as power generation systems.

Prior Art The most common form of energy use in Japan is electricity, and energy sources include nuclear power, oil and natural gas,
Thermal power, such as coal, and water power, such as rivers and dams, are used. However, in Japan, domestically produced energy sources are far less than the demand, so large amounts of oil and LPGSLNG are used.
Japan also imports uranium, etc. from overseas. Many of these energy sources are used for electricity, city gas, and industrial fuel.

Now, in energy conversion, where power is extracted from the thermal energy obtained by burning fuel, and then electricity is generated by operating a generator, oil, coal, LN,
G or LPG is burned as fuel in a Rankine cycle boiler equipped with a turbine, or in a combined cycle gas turbine and Rankine cycle gas turbine, and the generated steam is used to generate electricity driven by an expansion turbine. It is converted into electrical energy by a machine.

Here, I will briefly explain the Rankine cycle. Any liquid can be in a liquid phase, a gas-liquid mixed phase, or a gas phase depending on the pressure and energy state. Figure 5 is an example of a general gas phase diagram. If we take enthalpy on the horizontal axis and pressure on the vertical axis, the left side of the Yamabushi curve in the diagram is the liquid phase, and the right side is the gas phase, surrounded by the curve. The remaining part is a gas-liquid mixed phase. For example, when converting thermal energy obtained by burning fuel such as oil into electricity at a thermal power plant, a boiler is used to heat water with the above thermal energy, pressurize it and turn it into high-temperature, high-pressure steam. Steam is expanded in an expansion turbine, which rotates the turbine and drives a generator, which generates electricity.

In this case, energy is converted using water as a medium,
The cycle of changes in water pressure and enthalpy in that case is depicted in Figure 5 (this is called a Mollier diagram).
. The steam expands in the expansion turbine, performs work, and reaches the state of ■ (enthalpy is 11, pressure is pl, the same applies hereafter), and is cooled at the same pressure in the condenser and becomes liquid in the state of ■. become (water). The pressure of this water is increased using a boost pump to a state where the enthalpy is constant, creating high-pressure water. This is heated under equal pressure in a boiler, passes through the vaporization state (■), and becomes high-temperature, high-pressure steam in the state (■).This is then introduced into an expansion turbine where it is expanded in one or more stages to do work, and the temperature and pressure are decreases and returns to the state of ■.

Such a cycle is called a Rankine cycle.

In the above Rankine cycle, in the low-pressure steam cooling and liquefaction process from ■ to ■, the enthalpy is reduced from 11 to 12, but the amount of heat (il-iz) is dumped into the sea without being used. . On the other hand, in order to turn high-pressure water in the state of ■ into high-temperature, high-pressure steam in the state of This provides heat energy from the combustion of fuel to the water. Therefore, the energy efficiency of the Rankine cycle is
Energy extracted by expansion turbine i 5-
However, in reality, the latent heat of vaporization when changing from water to steam is large, so the value of (is is) is large,
As a result, the energy efficiency η can be kept low.

For this reason, in order to increase (i5-il) and thereby increase the efficiency η, the pressure of Including the mechanical loss of the turbine and the friction loss of the piping, the efficiency of the entire power generation system is at most 40 to 4.
It only amounts to about 2%.

For Japan, which spends a large amount of money importing energy sources, it is extremely important to improve their efficiency, or in other words, increase the amount of recovered energy.

Purpose of the Invention In view of the above-mentioned problems of energy conversion systems such as power generation systems using the conventional Rankine cycle, the present invention makes it possible to improve energy efficiency and utilizes low-temperature sensible heat energy such as seawater, which has not been available in the past. Of course,
The purpose of the present invention is to provide an energy conversion system capable of converting various types of thermal energy, such as solar heat or higher-quality high-temperature energy, into rotational energy and electrical energy.

In order to achieve the above object, the present invention provides an energy conversion system using the above-mentioned Rankine cycle.
A cooling/boosting subcle is provided that has a series of isenthalpic expansion steps accompanied by the Joule-Thomson effect after cooling, and in the cooling liquefaction step of the Rankine cycle, the heat of the Rankine cycle fluid is transferred through a low-pressure heat exchanger. It is recovered as the fluid in the heating vaporization process of the cooling/temperature raising cycle, and in the heating vaporization process of the Rankine cycle, heat is transferred from the fluid in the cooling process of the cooling/temperature raising cycle to the fluid in the Rankine cycle through a high-pressure heat exchanger. In order to give (il
-i2) is supplied to the heating vaporization process of the Rankine cycle,
It is characterized by self-sufficiency of a considerable part of the enthalpy increment (is) of the heating vaporization process.

In addition to this, thermal energy is supplied from an external heat source to the heating vaporization step of the Rankine cycle to ensure a predetermined enthalpy i5, and this external thermal energy is converted into rotational energy or electrical energy through an expansion turbine.

Further, at a position after passing through at least a part of the fluid flow path on the cooling/temperature raising cycle side of the high-pressure heat exchanger, a part of the fluid flows into the path leading to the isenthalpic expansion process and the heating vaporization process. The route leading to the circulation line is branched, and the circulation line is provided with a boost pump and a fluid suction mixing means operated by the fluid pressurized by the boost pump, and a flow path for the vaporized fluid exiting the heating vaporization process. A superheater is provided in the , and the fluid whose enthalpy and temperature have been raised to a certain value by the superheater is sucked by the fluid suction mixing means, mixed with the fluid passing through the circulation line, and then converted into the original high-pressure liquid fluid into the cooling liquefaction process. It is characterized in that it is designed to be discharged.

action The operation of the present invention will be explained in detail below using the drawings.

FIG. 1 shows the Rankine cycle diagram previously explained with reference to FIG. 5 and the Mollier diagram of the above-mentioned cooling/temperature raising cycle on the same coordinates for convenience of explanation.

The cycle of flow rate qo of ■→■→■→■→■→■ shown by the broken line in the figure is the aforementioned Rankine cycle, and the cycle of the flow rate qo of ■→■→■→■→■→■ shown by the solid line and the two-dot chain line is →［F］→■
is a cooling/heating cycle. A schematic diagram of the Rankine cycle and the cooling/heating cycle is shown in Figure 2. ■,■,... written along the flow path of each cycle
The symbols (2), (2), (2), . . . , [F] indicate positions corresponding to the states of the symbols in the Mollier diagram of FIG.

The fluid in the cooling/temperature raising cycle is a high-pressure, high-temperature liquid in the state of ■, and as it progresses from ■ to ◎, it is cooled, and between O → ■, it isenthalpically expands to become a low-pressure, low-temperature liquid and gas, which is When heated, it becomes a low-pressure gas in the [F] state.

This gas is brought to a state of high temperature and enthalpy [F] by the super heater E-5 using an external heat source, and is then absorbed and mixed with the fluid in the circulation line by the above-mentioned fluid absorption and mixing means, resulting in the high-pressure liquefaction state of (2). return. In other words, although the configuration of this cooling/heating cycle is different, the process is reversed from that of the Rankine cycle.

The temperatures TA, TB, and To of the fluid in the cooling process of ■→■→O of the cooling/temperature raising cycle are the same as those of the Rankine cycle.
The temperature of the fluid at the starting point of the heating vaporization process between → and ■ is set to be higher than T3, and high-pressure heat exchangers E-2 and E-5 are provided between the flow paths of this process in both cycles. ing. Also, the temperature Tr of the fluid in the heating vaporization step between ■ and [F] of the cooling/temperature raising cycle is set to be lower than the fluid temperature TI in the cooling liquefaction step between ■ and ■ of the Rankine cycle. , and a low pressure heat exchanger E-1 is provided between the flow paths of this step of both cycles.

In addition to the heat exchanger mentioned above, the flow path of the Rankine cycle includes ■,
Between ■, there is a boost pump P-1, between ■ and ■, there is a heating heat exchanger E-4 for inputting external energy;
, (2) is provided with an expansion turbine T-1 for extracting rotational work to the outside. On the other hand, the above-mentioned heat exchanger and super heater E-5 are installed in the flow path of the cooling/heating cycle.
In addition, there is an adiabatic expansion valve (Joule-Thomson valve) between ◎ and ■
TV is provided. Two more high pressure heat exchangers E
A branch pipe is provided from a point between -2 and E-3, and a boost pump P-2 is provided in the branch pipe. By adjusting the flow rate of the boost pump P-2 and the flow rate of the expansion valve JT-V, the flow rate of the fluid flowing between ■ and ■ becomes ql and ql.
The branch pipe with boost pump P-2 has ql
flow rate is flowed. The fluid whose pressure has been increased to the state shown in (2) by the boost pump P-2 is connected to the high-pressure nozzle inlet of the jet pump JP-1, while the gas whose temperature has been raised to some extent by the super heater E-5 is connected to the jet pump JP-1.
1, and the outlet is connected to a high pressure heat exchanger E-3.

Since this system is configured as described above, the heat of the fluid is transferred between the cooling and liquefaction steps (1) and (2) of the Rankine cycle through the low-pressure heat exchanger E-1 to the fluid q1 of the heating and vaporization step of the cooling/temperature raising cycle. The fluid that has recovered heat passes through ■ and becomes a gas in the [F] state, but the jet pump JP
Fluid q in the circulation line by fluid suction mixing means such as -1.
After that, during the cooling process (■) and O, the recovered heat is returned to the fluid between the heating and vaporizing processes (■) and (2) of the Rankine cycle via high-pressure heat exchangers E-2 and E-3. Therefore, the amount of external energy input by the temperature increasing heat exchanger E-4 can be reduced.

In the cooling/temperature raising cycle of the system of the present invention, the circulation line path with the flow rate q2 and the expansion and heating vaporization process path with the flow rate q1 are branched between the high-pressure heat exchangers E-3 and E-2. , the fluid q2 in the path of the circulation line is a booster pump P
-2, the pressure is increased to [stock], and it is ejected from the high-pressure nozzle of jet pump JP-1 to suck in the fluid with a flow rate of q1 of low-pressure gas in the state of [F], and mix it with the high-pressure liquid with a flow rate of q2.
can be discharged as a high-pressure liquid at the beginning of the cooling process. The energy required to drive the pressure boosting pump is much less than that required in the case where a compressor is provided to boost the pressure of the low-pressure gas [F] to the same pressure as (2). Moreover, in this system, the low-pressure gaseous fluid in the state [F] of the cooling and heating cycle is heated by the superheater E-5, and by maintaining the enthalpy and temperature slightly high, the jet pump JP- The enthalpy and temperature conditions of the mixed liquid after suction mixing can be set appropriately, which increases the degree of freedom in functional design and reduces the energy required to operate the boost pump P-2. Economical design flexibility is provided.

As a result, the energy required to operate the cooling/heating cycle is reduced, and the energy efficiency of the entire system can be significantly improved.

Embodiment The fluids flowing through the Rankine cycle and the cooling/temperature raising cycle may be different types of fluids or may be the same type of fluid. The type of fluid and the temperature at which it is used can be appropriately selected depending on the type of external energy input and the temperature level. For example, ethane is used as a fluid in the Rankine cycle to cool and
If ethylene is selected as the fluid used in the heating cycle, it is also possible to use natural energy as an external heat source, such as low-temperature heat sources that could not be used conventionally, such as the sensible heat of seawater, solar heat, and Joule heat from wind power. It becomes possible.

High-pressure heat exchangers E-2 and E-5 may be housed in one casing, and a branch pipe may be provided in the middle of the flow path on the cooling/heating cycle side, or a single heat exchanger may be housed in a branch pipe. It may be branched from the middle.

In addition, as shown in FIG. 5, one or more high pressure heat exchangers E
Why not branch the circulation path that flows the flow rate q2 from point C after passing through -2? Similar effects can be obtained. In this case, the enthalpy pressure diagram of the cooling/heating cycle is as shown in FIG. 4 by a solid line and a two-dot chain line.

In addition, as shown in Figure 6, the route leading to the isenthalpic expansion step and heating vaporization step is branched in the middle of the cooling step of the cooling/temperature raising cycle, and even if the circulation line is formed after the cooling step is completed, almost no Similar effects can be obtained.

The system examples shown in each of the above figures illustrate the basic concept of the present invention, and the attached equipment on the system, for example,
Descriptions of buffer tanks, valves, instruments, start-up equipment, etc. are omitted.

In addition to the configuration conceptually shown in the drawings, the present invention also includes combinations of a plurality of these systems and combinations with other energy conversion systems.

Effects As described above, according to the present invention, not only can the energy efficiency of a Rankine cycle energy conversion system such as a power generation system be improved, but also it is possible to utilize various types of external thermal energy that have not been used conventionally. Therefore, it is possible to reduce the amount of fossil fuels such as oil used and to maintain the balance of the natural environment.

[Brief explanation of drawings]

Fig. 1 is an enthalpy pressure diagram of the system of the present invention, Fig. 2 is a system diagram showing the basic concept of the system, Fig. 3 is a system diagram of another embodiment of the invention, and Fig. 4 is the enthalpy pressure thereof. FIG. 5 is an enthalpy pressure diagram of a known Rankine cycle, and FIG. 6 is an enthalpy pressure diagram of another embodiment of the present invention. ■→■→■→■→■・・・Rankin cycle 0→■→◎
→■→［F］→［F］・・・Cooling/heating cycle■→
■, 0→O... Cooling process ■→■, D-+E... Heating vaporization process T-1... Expansion turbine E-1... Low pressure heat exchanger E-2, E-3...・High pressure heat exchanger (E-2 in Figure 4)
) E-4...Heat input means from an external heat source (E in Figure 4)
-3) P-1, P-2... Boost pump JP-1... Jet pump (fluid suction mixing means) -
→ Enthalpy i Figure 4 Enthalpy i -Yu- Enthalpy i Figure 6 Enthalpy i June 26, 1985

Claims (5)

[Claims] (1) In an energy conversion system using the Rankine cycle, which has a series of steps in which a fluid is cooled and liquefied, pressurized, heated and vaporized, and then work is extracted by an expansion turbine, in addition to the above Rankine cycle, the fluid is heated and vaporized, pressurized, and vaporized.
A cooling/boosting cycle is provided which has a series of steps of isenthalpic expansion after cooling, and the heat of the fluid in the Rankine cycle is transferred to the cooling/temperature-boosting cycle via a low-pressure heat exchanger in the cooling liquefaction process of the Rankine cycle. is recovered in the fluid of the heating vaporization step, and gives heat to the fluid of the Rankine cycle in the heating vaporization step of the Rankine cycle from the fluid of the cooling step of the cooling/temperature raising cycle through a high-pressure heat exchanger;
In addition, a high-pressure heat exchanger and a low-pressure heat exchanger are installed between each part of both cycles to provide heat energy from an external heat source via a temperature-raising heat exchanger, and a temperature-raising heat exchanger is installed in the flow path of the Rankine cycle. A heat exchanger is provided, and at a position after passing through at least a part of the fluid flow path on the cooling/temperature cycle side of the high-pressure heat exchanger, a path leading to the isenthalpic expansion step and a heating vaporization step and a fluid flow path are provided. The circulation line is provided with a pressure pump and a fluid suction mixing means operated by the fluid pressurized by the pressure pump, and the flow of the fluid exiting the heating vaporization process is A super heater is provided in the passage, and the fluid whose enthalpy and temperature have been increased to a certain value by the super heater is sucked by the fluid suction mixing means and mixed with the fluid passing through the circulation line, and is used as the original high-pressure liquid fluid in the cooling process. An energy conversion device characterized in that the energy is discharged into the air. (2) The circulation line branches off from the route leading to the isenthalpic expansion step and heating vaporization step at a position after passing through the entire cooling/temperature raising cycle side fluid flow path of the high-pressure heat exchanger. The energy conversion system according to claim 1, characterized in that: (3) The first or second claim characterized in that the fluid used in the Rankine cycle and the fluid used in the cooling/heating cycle are different types of fluids. The energy conversion system described in section. (4) Claim 1 or 2, characterized in that the fluid used in the Rankine cycle and the fluid used in the cooling/heating cycle are the same type of fluid. Energy conversion system described in. (5) Any one of claims 1 to 4, characterized in that the maximum operating temperature of the fluid used in the Rankine cycle and the cooling/heating cycle is lower than the thermal energy temperature of the external heat source. The energy conversion system according to item 1.