Rotary thermal engine

Abstract

The challenges to be addressed are to simplify the operation control of the device and to improve output by eliminating losses and back pressure that occur in sections where the intake and exhaust are connected. [Solution] In this invention, when a Wankel-type rotary expander is installed as the expander in a Rankine cycle device, the output is adjusted by controlling the amount of steam supplied from the evaporator by detecting the liquid level in the evaporator. Furthermore, by controlling the intake with a rotary valve that opens and closes the supply path by rotating the supplied steam, the losses caused by the intake and exhaust being in communication are eliminated.

Description

Technical Field

[0001] The present invention relates to the Rankine cycle of a heat engine.

Background Art

[0002] A Rankine cycle device equipped with a rotary expander is registered as Patent No. 4614290. The device of this invention adopts a configuration in which a rotor in a cylinder rotates by the supply of steam from an evaporator to obtain power.

[0003] The vane type expander shown in FIG. 4 in the drawings of the previous patent specification is composed of two intake systems and two exhaust circuits, and is a mechanism in which pressure is always applied to two chambers, and the exhaust volume is twice that of a vane type engine of the same size. In short, it is small and has high output. However, there is a problem in that a large loss occurs due to a section where the supply of steam, that is, the intake and exhaust communicate.

[0004] Solving the above problems is extremely difficult. The vane type cylinder is a cocoon shape drawn by a peritrocoid curve, and it seems that the loss can only be reduced by methods such as narrowing the distance between the constricted part in the center of the cocoon and the bottom surface of the rotor to minimize the gap in the communication section.

[0005] However, this method may cause the cylinder and the rotor to come into contact due to linear expansion due to heat load or a very slight inclination of the shaft. Usually, between the cylinder and the rotor, a spring arranged in the seals keeps the apex of the cylinder from contacting, but there is no such structure between the bottom surface of the rotor and the constricted part in the center of the cocoon of the cylinder, and contact may cause an increase in the vibration and friction of the rotor.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

[0007] The challenges to be addressed are to simplify the operation control of the device and to improve output by eliminating losses and back pressure that occur in sections where the intake and exhaust are connected. [Means for solving the problem]

[0008] This invention adjusts the output of a Rankine cycle system by controlling the amount of steam supplied from the evaporator by detecting the liquid level in the evaporator, when a Wankel-type rotary expander is installed as the expander. Furthermore, by controlling the intake with a rotary valve that opens and closes the supply path by rotating the supplied steam, losses caused by the intake and exhaust being in constant contact are eliminated. [Effects of the Invention]

[0009] The Wankel-type expander of the present invention intermittently draws in air, and since the air intake is stopped in the connecting section, no back pressure is generated. This eliminates factors that hinder rotation, and the output of the expander is greatly increased. Furthermore, by detecting and controlling the liquid level of the evaporator's working fluid, the output can be easily controlled, making it possible to supply the necessary power according to the situation. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 shows a diagram of a Rankine cycle apparatus (Example 1). [Figure 2] Figure 2 shows the rotary expander cylinder and rotor (Example 2). [Figure 3] Figure 3 shows the rotary valve case (Example 2). [Figure 4] Figure 4 shows a rotary valve (Example 2). [Modes for carrying out the invention]

[0011] Rotary valve intake ports are connected to the first intake port [7] and second intake port [9] of the cylinder of the Wankel rotary expander [1] to allow intake, and the rotary valve disc

[14] rotates to open and close as steam is drawn in from the rotary valve intake port

[11] by the rotation of the rotary valve rotating shaft

[13] . Since the Wankel rotary expander is eccentric, the rotor rotates 120° for every one rotation of the shaft, so the intake opening and closing alternate every 60°, and the intake from the first intake port [7] of the cylinder is closed when the first exhaust port is opened by the rotation of the rotor, so back pressure and leak losses do not occur, and a significant improvement in output can be expected. The rotary valve rotating shaft

[13] may be directly controlled by an electric motor, or the rotation may be synchronized by connecting the output shaft of the expander and the rotary valve rotating shaft

[13] with a timing belt. [Examples]

[0012] Figure 1 shows a rotary thermal engine of the present invention, which consists of a power generation unit section comprising a Wankel-type rotary expander [1] and a generator [2] coupled to its output shaft, and a heat circulation section comprising an evaporator [3], a condenser [4], and a liquid transfer pump [5] connected by piping. The first intake port [7] and second intake port [9] of the Wankel-type rotary expander [1] in the power generation unit section are connected to the evaporator [3], and the first exhaust port [8] and second exhaust port

[10] are connected to the condenser, forming a Rankine cycle.

[0013] The rotary thermal engine of the present invention measures the liquid level of the working fluid held in the evaporator by installing a liquid level sensor [6] in piping arranged in parallel with the evaporator and sending the measured signal to a control device. Based on this signal, the liquid transfer pump [5] is inverter-controlled so that the liquid level in the evaporator is maintained at an arbitrary position between approximately 50% and preferably 70% of the evaporator's height. The output can be increased or decreased depending on what percentage of the condenser's height the liquid level is controlled to. Therefore, the output can be adjusted by the liquid level.

[0014] Furthermore, the Wankel rotary expander can operate even when the supplied steam is highly humid, and does not require a preheating circuit or control for the piping to prevent the steam from becoming damp during operation. It can be configured as a very simple device that stops when the hot water supply is interrupted and starts operating again when the supply is resumed. [Examples]

[0015] The first intake port [7] and second intake port [9] of the cylinder of the Wankel rotary expander [1] are connected to an evaporator [3]. A rotary, openable and closable intake valve is placed in the path between the evaporator [3] and the first intake port [7] and the second intake port [9] to allow control of the intake timing. Specifically, rotary valve intake ports are connected to the first intake port [7] and second intake port [9] of the cylinder of the Wankel rotary expander [1] so that steam drawn in from the rotary valve intake port

[11] is opened and closed by the rotation of the rotary valve rotating shaft

[13] which causes the rotary valve disc

[14] to rotate. The Wankel rotary expander is eccentric, so when the shaft rotates once, the rotor rotates 120°, causing the intake to alternate between open and closed every 60°. The rotary valve disc

[14] has an opening angle of 135° and the rotary valve intake port

[12] has an opening angle of 45°, so the opening and closing alternate every 180° rotation, and the rotary valve rotation axis

[13] rotates 180° for a rotor rotation angle of 60°. The intake of the cylinder's first intake port [7] is closed when the first exhaust port opens due to the rotation of the rotor and becomes exhaust, so back pressure and leak losses are eliminated, and a significant improvement in output can be expected. The valve of the second intake port [9] is 180° out of phase, so when the rotary valve installed in the first intake port [7] is open, the second intake port [9] is closed. The rotary valve rotating shaft

[13] may be directly controlled by an electric motor, or its rotation may be synchronized by connecting the output shaft of the Wankel rotary expander [1] and the rotary valve rotating shaft

[13] in a 1:1 ratio with timing belts via timing pulleys installed on each shaft.

[0016] A communication groove is dug in the cylinder between the first exhaust port [8] and the second intake port [9] of the cylinder of the Bankel type rotary expander [1], and the first exhaust port [8] and the second intake port [9] are communicated. The openings of the first exhaust port [8] and the second intake port [9] are blocked, and the steam supplied from the first intake port [7] is supplied from the first exhaust port [8] to the second intake port [9] through the communication groove and exhausted from the second exhaust port

[10] . By configuring it in this way, not only can a configuration with one system of input / output ports be achieved, but the adiabatic expansion ratio is significantly larger than that of a Bankel type rotary expander having two systems of intake ports, and the fuel consumption is improved. Furthermore, by installing the rotary valve described above, the performance is further improved. The width of the communication groove is about 5 mm to 15 mm, the depth is about 3 mm to 8 mm, and it is preferably made to have the same cross-sectional area as the opening of the first intake port [7]. The rotary valve rotating shaft

[13] may be directly rotationally controlled by an electric motor, or the output shaft of the expander and the rotary valve rotating shaft

[13] may be connected by a timing belt to synchronize the rotation.

Industrial Applicability

[0017] The device of the present invention can be used in the fields of regeneration of industrial waste heat into electric energy, geothermal energy, biomass power generation, etc., and also greatly contributes to environmental maintenance such as CO2 reduction.

Explanation of Signs

[0018] 1 Bankel type rotary expander 2 Generator 3 Evaporator 4 Condenser 5 Liquid feed pump 6 Liquid level sensor 7 First intake port 8 First exhaust port 9 Second intake port 10 Second exhaust port 11 Rotary valve intake port 12 Rotary valve intake communication port 13 Rotary valve rotation shaft 14 Rotary valve disc

Claims

1. A Rankine cycle device comprising an evaporator, which is a heat exchanger for evaporating a working fluid; a mechanism that converts power into electricity via a generator connected via a shaft to a Wankel-type rotary expander, which converts pressure into power by the expansion of the working fluid supplied after evaporation in the evaporator, causing the rotor to rotate; a condenser, which is a heat exchanger for returning the steam exhausted from the Wankel-type rotary expander back into liquid; and a pump that transfers the liquid working fluid to the evaporator, all connected by piping, is a Rankine cycle device characterized by having a device for detecting the liquid level of the working fluid remaining in the evaporator, and a control device that inverter-controls the pump based on the signal indicating the height of the liquid level.

2. The rotary thermal engine according to claim 1, characterized in that it is provided in the intake path with an electrically operated valve that rotates to open and close for intermittently supplying steam evaporated in an evaporator.

3. The rotary thermal engine according to claim 1, characterized in that a rotary valve is installed in the intake path, in which the output shaft of the rotary expander and the rotary valve rotation shaft are linked in a 1:1 ratio by a timing belt, in order to intermittently supply the steam evaporated in the evaporator.

4. The rotary thermal engine according to claims 1 to 3, characterized in that a groove is cut in the cylinder of the Wankel-type rotary expander so that the first exhaust port and the second intake port of the cylinder are connected within the cylinder, and the first exhaust port and the second intake port are closed to constitute the Wankel-type rotary expander as a single input / output device.

5. The rotary thermal engine according to claims 1 to 4, characterized in that a resin tube for appropriately controlling the amount of working fluid injected is connected in parallel to the evaporator and the condenser by piping, allowing for visual monitoring.

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