DOUBLE-SCREW LIQUID PUMP

BACKGROUND OF THE PRESENT INVENTION

1. Field of Invention

The present invention relates to the field of Organic Rankin Cycle (ORC) technology, specifically to an ORC power generation system, and more specifically to a double-screw liquid pump of the ORC power generation system.

2. Description of Related Arts

Referring to FIG. 1, FIG. 1 is a typical ORC, which includes an expander 1′, a generator 2′, an evaporator 3′, a liquid pump 4′ and a condenser 5′.

A low-temperature and low-pressure liquid refrigerant is pressurized in the liquid pump 4′, and then enters the evaporator 3′ to be evaporated through heating until the refrigerant becomes an overheated gas (high temperature and high pressure). The overheated gas enters the expander 1′ to work through expansion, so as to drive the generator 2′ to generate power. After working, the low-temperature and low-pressure gas enters the condenser 5′ and is condensed to liquid, and then flows back into the liquid pump 4′, thus completing a cycle.

Most of the existing liquid pumps are open-type gear pumps or centrifugal pumps. The gear pump has the following defects: in the gear pump, one gear always drives another gear, and half of the consumed work is consumed during a driving process; meanwhile, in the ORC cycle, liquid viscosity is usually low, and the gear wears easily. The centrifugal pump has the following defect: after the centrifugal pump sucks the liquid, a pressure during the suction process is decreased, and the liquid evaporates easily, which causes efficiency of the centrifugal pump to decrease, thereby affecting efficiency of the entire ORC cycle. The open-type liquid pump has the following defect: the refrigerant leaks easily through a shaft seal.

SUMMARY OF THE PRESENT INVENTION

The technical problem to be solved by the present invention is to provide a double-screw liquid pump, in which a resistance torque of a female rotor is very small, and the liquid pump does not wear even when the liquid viscosity is very low, contributing to good reliability.

In order to solve the above technical problem, the present invention adopts the following technical solution.

A double-screw liquid pump is provided, comprising a semi-sealed or fully sealed shell, wherein the shell comprises a first cavity and a second cavity isolated from each other; a motor is disposed in the first cavity, and a main body part of a double-screw is disposed in the second cavity; at least one rotor of the double-screw is fixedly connected to a rotor of the motor, and the double-screw rotates through driving of the motor; a liquid refrigerant injection inlet and a refrigerant outlet are disposed on the first cavity, and the motor is cooled through evaporation of the liquid refrigerant; a liquid inlet and a liquid outlet are disposed on the second cavity.

As a preferential solution of the present invention, the double-screw comprises a male rotor and a female rotor, and a first end of the male rotor is fixedly connected to the rotor of the motor.

As a preferential solution of the present invention, the male rotor comprises a rotor part and a connection part which are integrally designed; the rotor part is disposed in the second cavity and coordinates with the female rotor; the connection part extends into the motor in the first cavity; the first cavity and the second cavity are isolated from each other through an isolation mechanism, so that a hole is formed between the first cavity and the second cavity; the connection part passes through the hole and enters the first cavity, and an end of the connection part away from the rotor part is fixedly connected to the rotor of the motor.

As a preferential solution of the present invention, a first male rotor bearing is disposed at a second end of the male rotor away from the motor, and female rotor bearings are separately disposed at two ends of the female rotor.

As a preferential solution of the present invention, a second male rotor bearing is disposed at the connection part and between the rotor part of the male rotor and the rotor of the motor.

As a preferential solution of the present invention, the connection part and an end of the second male rotor bearing close to the rotor of the motor are sealed through a shaft seal.

As a preferential solution of the present invention, the motor is an inverter motor or a motor with a fixed rotating speed.

The present invention has the following beneficial effects: in the double-screw liquid pump applied to the ORC provided in the present invention, since a resistance torque of the female rotor is very small, the liquid pump does not wear even when the liquid viscosity is very low, contributing to good reliability, and thereby improving power generation efficiency of the ORC. In addition, the semi-sealed or fully sealed shell can effectively prevent leakage of the refrigerant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of composition of an ORC power generation system.

FIG. 2 is a schematic view of composition of an ORC power generation system using the present invention.

FIG. 3 is a sectional view of a double-screw liquid pump in a vertical direction consistent with the present invention.

FIG. 4 is a sectional view of a double-screw liquid pump in a horizontal direction consistent with the present invention.

FIG. 5 is a sectional view of the male and female motors of a double-screw liquid pump consistent with the present invention.

LIST OF REFERENCE NUMERALS

• 1′ Expander
• 2′ Generator
• 3′ Evaporator
• 4′ Liquid pump 5′ Condenser
• 1 Expander
• 2 Generator
• 3 Evaporator
• 4 Liquid pump
• 5 Condenser
• 401 Motor
• 402 Male rotor
• 403 Female rotor
• 4041 First male rotor bearing
• 4042 Second male rotor bearing
• 405 Female rotor bearing
• 406 Seal ring
• 407 Liquid inlet
• 408 Liquid outlet
• 409 Refrigerant injection inlet
• 410 Refrigerant outlet
• 411 Shaft seal

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention are described in detail with reference to the accompanying drawings below.

Embodiment 1

Referring to FIG. 2, FIG. 2 shows an ORC power generation system using the present invention. The ORC power generation system includes a condenser 5, a liquid pump 4, an evaporator 3, an expander 1, and a generator 2. The main improvement of the present invention is the liquid pump 4. In this embodiment, the liquid pump 4 is a double-screw liquid pump 4.

Referring to FIG. 3 and FIG. 4, the double-screw liquid pump 4 includes a semi-sealed or fully sealed shell. The shell is formed of multiple components, and a seal ring 406 is disposed at each gap between components. The shell includes a first cavity and a second cavity isolated from each other. A motor 401 is disposed in the first cavity, and a main body part of a double-screw is disposed in the second cavity. At least one rotor of the double-screw is fixedly connected to a rotor of the motor. The double-screw rotates through driving of the motor 401. A dynamic source of the motor 401 may be from electric energy generated by the ORC power generation system. A liquid refrigerant injection inlet 409 and a refrigerant outlet 410 are disposed on the first cavity, and the motor 401 is cooled through evaporation of the liquid refrigerant. A liquid inlet 407 and a liquid outlet 408 are disposed on the second cavity. The motor may be an inverter motor or a motor of a fixed rotating speed, and definitely may be an ordinary motor.

The double-screw liquid pump includes a male rotor 402, and a female rotor 403. A first end of the male rotor 402 is fixedly connected to the rotor of the motor 401. The male rotor 402 includes a rotor part and a connection part which are integrally designed. The rotor part is disposed in the second cavity and coordinates with the female rotor 403. The connection part extends into the motor 401 in the first cavity. The first cavity and the second cavity are isolated from each other through an isolation mechanism, so that a hole is formed between the first cavity and the second cavity; the connection part passes through the hole and enters the first cavity, and an end of the connection part away from the rotor part is fixedly connected to the rotor of the motor 401.

A first male rotor bearing 4041 is disposed at a second end of the male rotor 402 away from the motor 401. Female rotor bearings 405 are separately disposed at two ends of the female rotor 403. A second male rotor bearing 4042 is disposed at the connection part and between the rotor part of the male rotor and the rotor of the motor. The connection part and an end of the second male rotor bearing 4042 close to the rotor of the motor are sealed through a shaft seal 411.

In conclusion, in the fully sealed or semi-sealed double-screw liquid pump applied to the ORC power generation system provided in the present invention, since a resistance torque of the female rotor is very small, the liquid pump does not wear even when the liquid viscosity is very low, contributing to good reliability, and thereby improving power generation efficiency of the ORC. In addition, the semi-sealed or fully sealed shell can effectively prevent leakage of the refrigerant.

Herein, the description and application of the present invention are illustrative, and the scope of the present invention is not intended to be limited to the above embodiments. Variations and changes to the embodiments disclosed herein are possible. Replacement made to the embodiments and equivalent parts are well-known to persons skilled in the art. It should be known to persons skilled in the art that, the present invention can be implemented in other forms, structures, arrangements, ratios and through other components, materials, and parts without departing from the script or essential features of the present invention. Other variations and changes may be made to the embodiments disclosed herein without departing from the scope and script of the present invention.