JPS61212613A - Energy conversion system - Google Patents

Abstract

PURPOSE:To improve energy efficiency by converting the intermediate or low pressure gas compressed after the completion of expansion process to the high- temperature and high-pressure liquid by a gas suction and mixing part formed in an auxiliary process and providing heat energy to a main process. CONSTITUTION:In an auxiliary process, the high-pressure fluid branch-intruduced at the B point from a circulation system passage is pressurized by a pressurizing pump P-2, and jetted out form the nozzle of a jet pump JP-1. Therefore, the intermediate or low pressure gas which is compressed in a compressor C-1 after the completion of expansion process is continuously inhaled from a flow passage connected to the low pressure side and mixed with the high-pressure liquid jetted out from the nozzle and forms high-temperature high-pressure liquid, and flows in the passage between A and B. Therefore, by raising the temperature after the completion of heat exchange higher than the temperature at the start of the heating and pressurization process in a main process, the heat of the fluid in the cooling liquefaction processes A-B-C naturally transfers to the fluid in the heating and vaporization process 3-5 in the main process through the high-pressure heat exchangers E-2 and E-1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an energy conversion system for extracting thermal energy in the form of rotation or electric power, such as a power generation system.

BACKGROUND OF THE INVENTION The most common form of energy use in Japan is electricity, and energy sources include thermal power such as nuclear power, oil, natural gas, and coal, and hydraulic power from rivers and dams. However, in Japan, domestically produced energy sources are far less than the demand, so large amounts of oil, LPG,
It imports LNG, 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 and p are LPG, etc., which are combusted in a U/Kin cycle boiler equipped with a turbine as fuel, or in a combined cycle gas turbine and Rankine cycle, and an expansion turbine rotated by the generated steam, etc. It is converted into electrical energy by a driven generator.

Here, I will briefly explain the Rankine cycle. Any fluid can be in a liquid phase, a gas-liquid mixed phase, or a gas phase depending on its pressure and energy state. Figure 6 is a series of general phase diagrams of gases, with enthalpy on the horizontal axis and pressure on the vertical axis.The left side of the mountain-shaped curve in the figure is the liquid phase, and the right side is the gas phase. The lower 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 the water pressure, binary, etc. state in that case is depicted in Figure 6 (this is called a Mollier diagram).

The steam expands in the expansion turbine, performs work, and becomes a state of l (enthalpy is 11, pressure is Pl, the same applies hereafter), and is cooled to the same pressure in a condenser, and becomes liquid in a state of 2. become (water). The pressure of this water is raised to a state of \3 while keeping the enthalpy constant using a pressure boosting pump, resulting in high-pressure water. This is heated under equal pressure in a boiler, passes through the vaporization state 4 and becomes high temperature, high pressure steam in state 5, which is introduced into an expansion turbine and
It performs work by expanding in stages or in multiple stages, the temperature and pressure decrease, and it returns to the 1 state again.

Such a cycle is called a Rankine cycle.

In the above-mentioned Rankine cycle, the enthalpy is reduced from 11 to 12 in the cooling and liquefaction process of low-pressure steam from 1 to 2, but the amount of heat (il-il) is dumped into seawater and is wasted without being used.

- In order to turn high-pressure water in state 3 to high-temperature, high-pressure steam in state 5, an enthalpy increment (iB
-il), and in actual thermal power generation, a boiler provides thermal energy to water by burning fuel. Therefore, the energy efficiency of the Rankine cycle is as follows. However, in reality, since the latent heat of vaporization when changing from ice to water vapor is large, the value of (iB-i3) is large, and as a result, the energy efficiency η is kept low.

For this reason, the pressure of 3 is made as high as possible to increase the enthalpy of 5 in order to increase the efficiency η by increasing ~(il-11). 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. The purpose of the present invention is to provide an energy conversion system that can convert various types of thermal energy, including solar heat and higher-quality high-temperature energy, into rotational energy and electrical energy.

In order to achieve the above object, the present invention utilizes a cycle including the steps of increasing the pressure of a liquid fluid, heating and vaporizing it, and then polytropically expanding it, and in the heating and vaporizing step, thermal energy from an external heat source is taken in. In an energy conversion system that converts into power energy in the expansion process and extracts it to the outside, the fluid that has become a low-pressure gas at the outlet side of the expansion process is heated by the auxiliary process using the same type of fluid as the main process. A high-pressure liquid with a temperature higher than that of the fluid in the vaporization process is formed, and heat is applied to the fluid in the heating vaporization process through a heat exchange means provided between the flow path of the high-pressure liquid and the flow path of the fluid in the heating vaporization process to achieve the above-mentioned high temperature. The cooling process is formed by cooling the high-pressure fluid, and the path of the above auxiliary process is
A gas suction mixing section in which high-pressure fluid circulates and the low-pressure gas on the outlet side of the expansion step of the main process is absorbed and liquefied by a booster pump and the circulating fluid pressurized by the booster pump, and a flow path of the heating vaporization step of the main process. A circulation system having a high-pressure heat exchanger installed in between, and a path branching from the circulation system at the outlet side of the heat exchanger, passing through an expansion valve to obtain a low-temperature and low-pressure state by the Joule-Thomson effect, and passing through a gas-liquid tank. A route for supplying the low-temperature, low-pressure liquid to the pump in the pressure increase step of the main process, and a compressor to compress the low-temperature, low-pressure gas generated as flash gas during expansion to medium-low pressure, and mix it with the low-pressure gas at the outlet of the expansion step of the main process before and after that. It is composed of an isenthalpic expansion system consisting of a path supplying the gas to the artificial side of the gas suction mixing section.

For production The operation of the present invention will be explained in detail below based on the drawings.

FIG. 1 is a Mollier diagram showing the cycle of the energy conversion system of the present invention, with enthalpy plotted on the horizontal axis and pressure plotted on the vertical axis.

1.2.3.4.5 in the figure correspond to the positions of the same sign in the Rankine cycle shown in FIG. In contrast to the Rankine cycle, the main process of the system of the present invention lacks a cooling liquefaction step that goes directly from 1 to 2. To compensate for this, this system is equipped with an auxiliary process consisting of an isenthalpic expansion system, where the high-temperature, high-pressure liquid is shown as A-+B-4B in the figure, and the circulation system of this auxiliary process is used to control the main process. Giritrope expansion process 5→l
The fluid that has become a low-pressure gas in the heating vaporization process 3 → 5 becomes a high-pressure liquid in the state A, which is higher temperature than the fluid in the heating vaporization process 3 → 5, and it progresses to A-+B (or C) with the fluid in the circulation m system, and during this time A heat exchanger provided between the flow path of the auxiliary process and the flow path of the heating vaporization step of the main process gives thermal energy to the fluid in the heating vaporization step, and the fluid is cooled by itself. Furthermore, the liquid fluid flowing through the auxiliary process is branched into a circulation system and an isenthalpic expansion system at B (or C), and the fluid in the circulation system passes through a boost pump and reaches the gas suction mixing section, where it returns to the above-mentioned low pressure from F to A. Gas absorption is performed, and the fluid in the isenthalpic expansion system passes through the expansion valve and becomes a low-temperature, low-pressure liquid and flash gas (gas) due to the Joule-Thomson effect, and the two phases are separated in a gas-liquid tank.

The liquid in the gas-liquid tank flows into the pump for the pressurization step of the main process via route D→2, while the gas in the gas-liquid tank is compressed to medium-low pressure by the compressor, and then reaches the inlet side of the gas suction mixing section. , D→E-+F-eA is absorbed into the circulating fluid of the auxiliary process.

That is, in the system of the present invention, the process is configured in step i in the example of FIG. 1, and is replaced by the cooling liquefaction step of the Rankine cycle.

FIG. 2 Fi is a system diagram showing a schematic configuration of the energy conversion system for the cycle shown in FIG. 1, with the auxiliary process system mainly shown on the left side of the figure and the main process system shown on the right side. The same fluid is used in both processes, and the 1, 2. ..., 5 and A, B,
. . , the position of the symbol F corresponds to the symbol on the gland diagram in FIG.

In the auxiliary process, high pressure fluid circulates and boost pump P-2
One of the high-pressure heat exchangers installed between the gas suction mixing section such as the jet pump JP-1 driven by the pressurized liquid and the flow path 3-44 of the heating vaporization step of the main process. A circulation system having E-2 and the heat exchanger E-
2, it branches off from the above circulation system, passes through an isenthalpic expansion valve (Joule-Thomson valve) JT-V, a gas-liquid tank V-1, and is connected to a boost pump P-1 in the pressure boost step of the main process. It consists of an isenthalpic expansion system having a low-pressure liquid path and a flash gas gas path connected to the low-pressure side (suction side) of the jet pump JP-1 by means of a medium-low pressure compressor C-1tU. In the illustrated example, one high-pressure heat exchanger E-1 is further provided downstream from the branch point. Gas liquid tank V
The 7 rough gas in -1 is made into medium and low pressure gas by compressor C-1, and then mixed with low pressure gas 1 in the expansion step of the main process, but the connection method between flow path 1 and the auxiliary process system is limited to this. The flow path l is once connected to the gas-liquid tank V-.
1, the two gases may be mixed and then introduced to the compressor C-1, or the flow path may be connected to an intermediate position between the gas-liquid tank V-1 and the compressor. .

At the bottom of the gas-liquid tank V-1 is the main process boost pump P-1.
A flow path is provided to connect to the gas-liquid tank, or the boost pump P-1 is installed as a submerged pump in the liquid of the gas-liquid tank.

In the main process system, the flow path on the discharge side of the booster pump P-1 is connected to the heating vaporization process, and the high-pressure heat exchanger E-1, E-
A heating heat exchanger E-3 for taking in thermal energy from an external heat source is provided between the four and five downstream thereof. During the expansion step 5.1, the gas flow path is provided with an expansion turret/turbine that supplies rotational energy to the source IEiG-1.
T-1 is provided.

The entire operation of this energy conversion system will be explained below.

The flow rate of the fluid flowing through the flow path from the bottom of the main process gas-liquid tank V-1 through 3°4.5 to become a low pressure gas of 1 is q07, and the auxiliary process circulation system flow path B, B', the flow rate of the fluid flowing through A is branched at q,, the flow rate of the fluid reaching the gas-liquid tank V-1 is ql, and the flow rate of the fluid flowing through the gas-liquid tank V-1 is ql, and the flow rate of the fluid flowing through the gas-liquid tank V-1 is transferred to the compressor C.
Let Δq be the flow rate of the fluid flowing through the flow path that passes through -1 and reaches the suction side of jet pump JP-1. Furthermore, this △q,
is the flow rate corresponding to the flash gas due to the Joule-Thomson effect in the expansion valve, and the flow rate of the main process q0
merges with q to become ◎, that is, −q, +Δq, w
In the jet pump JP-1, high-pressure circulating fluid (flow rate q,
) absorbs and liquefies medium and low pressure gas (flow rate q0+ΔQ,=Q,), and therefore, a liquid with a flow rate of a q, + q, flows between A and B.

Now, the high-pressure fluid with a flow rate q2 branched into the circulation system path at point B by an appropriate control valve (not shown) is transferred to the boost pump P-
, 2 to the pressure indicated by B' in the Mollier diagram, and is ejected from the nozzle of jet pump JP-1.

As a result, the medium and low pressure fluid in the pump chamber surrounding the nozzle opening of the jet pump JP-1 is attracted by the fluid ejected from the nozzle according to Bernoulli's theorem, and a flow path connected to the medium and low pressure side of the jet pump JP-1 is created. Medium and low pressure gas with a flow rate of q is continuously sucked in, and mixes with the high pressure liquid with a flow rate of q2 ejected from the nozzle, becoming a high temperature, high pressure liquid with an amount of q, +q2 as shown at point A. The fluid flows through the path between AB and cools itself by giving thermal energy to the fluid flowing through the path between heating and vaporization steps 3 and 4 of the main process via the high-pressure heat exchanger E-2. After separating the flow rate q into the circulation path at point B in Figure 2, thermal energy is further applied to the low-temperature fluid in the first stage of the heating vaporization step of the main process via another high-pressure heat exchanger E-1. After the temperature further decreases, isenthalpic expansion is performed by the isenthalpic expansion valve JT-V, resulting in a low pressure and low temperature state shown in the middle of FIG. 1, where there is only liquid and flash gas or liquid.

This style! The fluid of q1 enters the gas-liquid tank V-1, and the flow rate of qo is taken out from the lower part of the tank V-1, and the fluid is sent to the boost pump P--
It is pressurized to the state of 3 by 1 and supplied to the heating vaporization step of the main process, and during 3.4, heat energy is given from the high-temperature liquid in the auxiliary process system by high-pressure heat exchangers E-1 and E-2. and further between 4.5 and 4.5, the heating heat exchanger E-
Heat is input from an external heat source through 3, and the gas becomes high temperature and high pressure in the state 5, and is expanded by the expansion turbine T-1 to rotate the expansion turbine and drive the generator G-1. The gas Δq1, which is equivalent to the flash gas in the gas-liquid tank V-1, is compressed to medium-low pressure by the compressor C-1 and reaches F, but before and after that, it is mixed with the discharged gas q0 from the expansion step of the main process, and the jet pump JP -1, and is again sucked into the high-temperature, high-pressure liquid at a flow rate of q.

As described above, in the energy conversion system of the present invention, the medium and low pressure gas after the completion of the expansion process is brought into a high temperature and high pressure liquid state by the gas suction mixing section provided in the auxiliary process, and the temperature T0 after the completion of heat exchange is set to the temperature T0 of the main process. By setting the temperature of the fluid higher than T3 at the start of the heating vaporization process, the heat of the fluid in the cooling liquefaction process A-B-C naturally moves to the fluid in the heating vaporization process 3-5, resulting in a high temperature of state 1. Enthalpy is not wasted, but is utilized within the system. The energy required to drive the boost pump P-2 installed in the auxiliary process path is much less than the energy discarded into cooling water such as seawater in a conventional Rankine cycle energy conversion system, so the energy efficiency of the entire system is Improved compared to traditional systems.

Furthermore, in the energy conversion system of the present invention, the temperature, enthalpy, and pressure of all or part of the gas sucked into the jet pump are increased to a certain level by the compressor before being sucked. There is a degree of freedom in setting the pressure, enthalpy, and temperature levels of the fluid obtained by mixing with the high-pressure circulating liquid, which is highly effective in terms of functional and economical design.

In this system, the fluid flowing through the main process and the auxiliary process is the same fluid, and the temperature is raised or cooled by itself between different processes, so by selecting the type of fluid, it is possible to A low temperature heat source can be used as an external heat source. For example, by using ethylene, It also reduces NOx and Co, which are generated when these are burned, and is effective in maintaining the heat balance in nature.

In the system shown in Figures 1 and 2, two sets of high-pressure heat exchangers are installed, and the circulation system route for the auxiliary process is branched from between them. The heat exchanger may be housed in two casings and the circulation system path may be branched from the middle thereof, or the circulation system fluid may be flowed from the middle of a single heat exchanger. Also, as shown in Figure 3,
Point C after passing through one or more high pressure heat exchangers WE-1
The same effect can be obtained by branching the circulation system path that carries the air flow Jiq. FIG. 4 is a Mollier diagram in that case.

After the expansion process is completed, the medium and low pressure gas flow path l is connected between the compressor C-1 and the jet pumps P and -1 in the above row, but
Once connected to the gas-liquid tank V-1 as shown in Figure 7(a),
After the gas l after the completion of the expansion process is mixed with the flash gas in the gas-liquid tank, it may be introduced into the compressor to create a medium-low pressure. In this case, the Mollier diagram of the relevant part will be as shown in Figure 7 (b). become.

Similarly, the gas 1 after the completion of the expansion process may be connected between the gas-liquid tank V-t and the compressor C-1 as shown in FIG. 8. The Mollier diagram in this case is also shown in FIG. This is almost the same as (b). Also, as shown in FIG. 5, almost the same effect can be obtained even if the isenthalpic expansion channel is branched in the middle of the high-pressure heat exchange process.

Note that the system examples shown in each of the figures above illustrate the basic concept of the present invention, and descriptions of attached equipment on the system, such as buffer tanks, valves, meters, start amplifier equipment, etc., are omitted. .

In addition to the following configurations conceptually shown in the drawings of the present invention,
It also includes combinations of multiple of these systems and combinations with other energy conversion systems.

Effects As described above, according to the present invention, it is possible not only to improve the energy efficiency of a system that converts thermal energy into motive energy, such as a power generation system, but also to use various external heat sources that have not been used conventionally. Therefore, the amount of fossil fuels such as oil used can be reduced, and as a result, an effect can be obtained on the conservation of the natural environment.

[Brief explanation of drawings]

Figure 1 is a Mollier diagram of the system of the present invention, Ii diagram, Figure 2 is a system diagram showing the basic concept of the system, Figure 3 is a system diagram of another embodiment of the present invention, and Figure 4 is its Mollier line. figure,
FIG. 5 is a Mollier diagram of another embodiment of the present invention, FIG. 6 is a Mollier diagram of a known Rankine cycle, and FIG. 7(a)
(b) is a partial system diagram and Mollier diagram of a modified embodiment of the present invention, and FIG. 8 is a partial system diagram of another modified embodiment. 2→3→5→l... Main process, A-C... Cooling process, 2-3... Pressure increasing process, 3-4
-5... Heating vaporization process, 5-1... Expansion process, T-1... Expansion turbine, E
-1, E-2...High pressure heat exchanger (E-1 in Figure 3)
, E-3...Heat input means from an external heat source (E-3 in Figure 3)
2), P-1, P-2...boost pump, JP-1...jet pump, JT-V...expansion valve, V-1...-gas-liquid tank, C-1... Compressor Figure 1 Enthalpy i Figure 5 Enthalpy turtle

Claims (2)

[Claims] (1) Using a cycle that includes the steps of increasing the pressure of a liquid fluid, heating and vaporizing it, and then subjecting it to polytropic expansion, thermal energy is taken in from an external heat source in the heating and vaporization step, converted into power energy in the expansion step, and taken out to the outside. In an energy conversion system, the fluid that has become a low-pressure gas at the outlet side of the expansion process is converted into a high-pressure liquid at a higher temperature than the temperature of the fluid in the heating vaporization process by an auxiliary process using a fluid with the same polarity as the main process. None, the cooling process is formed by cooling the high-temperature, high-pressure fluid by applying heat to the fluid in the heating vaporization process via a heat exchange means provided between the flow path and the flow path for the fluid in the heating vaporization process. The above-mentioned auxiliary process path includes a gas suction mixing section in which high-pressure fluid circulates and absorbs and mixes low-pressure gas on the expansion stage outlet side of the main process with a boost pump and the circulating fluid pressurized by the boost pump, and a heating of the main process. A circulation system has a high-pressure heat exchanger installed between the flow path of the vaporization process, and the circulation system branches off from the above-mentioned circulation system at the outlet side of the high-pressure heat exchanger, and passes through an expansion valve and a gas-liquid tank to supply the low-temperature and low-pressure liquid to the above. It is characterized by an isenthalpic expansion system consisting of a path that supplies the pressure boosting step of the main process, and a path that compresses the flashed low-temperature, low-pressure gas to medium-low pressure using a compressor, and then supplies it to the inlet side of the gas suction mixing section. energy conversion system. (2) The energy conversion system according to claim 1, wherein the circulation system flow path and the isenthalpic expansion system flow path are branched at an intermediate portion of the high-pressure heat exchange step of the auxiliary process.