CN103726882A - Oil supply system for organic Rankine cycle displacement expansion machine - Google Patents

Abstract

An oil supply system for an organic Rankine cycle volume expander belongs to the field of low-grade energy utilization. Connect the condenser (1), main pump (2), evaporator (3), oil separator (6), and expander (4) sequentially with the working fluid pipeline end to end to form a working fluid circulation loop, and the oil is separated The lubricating oil outlet of the device (6) is connected with the oil injection hole of the expander (4), and the pipeline is filled with a mixture of organic Rankine cycle working medium and lubricating oil. The innovation of the present invention is that the oil separator (6) is placed between the evaporator (3) and the expander (4), which can save the lubricating oil pump and reduce the influence of the pressure loss of the oil separator on the output of the expander .

Description

An Oil Supply System for Organic Rankine Cycle Volumetric Expander

technical field

The invention relates to an organic Rankine cycle volume expansion machine lubricating oil supply system, which belongs to the field of low-grade energy utilization.

Background technique

One of the ways to alleviate the current environmental pollution and energy shortage problems is to make full use of various waste heat resources and develop and utilize renewable energy such as geothermal energy and solar energy. Organic Rankine cycle technology is expected to be widely used due to its simple system and high heat transfer efficiency. The expander is a key component of the ORC, and its performance has an important impact on the efficiency of the ORC. The expanders used in organic Rankine cycle are generally divided into two categories, one is speed expander, such as radial turbine or axial turbomachinery, and the other is volumetric expander, such as scroll, screw type, reciprocating type and slide type etc. Because the volumetric expander has the advantages of large expansion ratio, high efficiency, low rotation speed and two-phase expansion, its development prospect is very promising. However, positive displacement expanders often require a reliable oil supply system for lubrication, cooling and sealing. There are usually two oil supply schemes for organic Rankine cycle positive displacement expanders, the first one is shown in Fig. 1 . In this scheme, an oil separator is installed at the outlet of the expander, and a lubricating oil pump is used to supply oil. The specific process is that after the oil-gas mixture from the expander enters the oil separator, the gas working medium enters the condenser to circulate, and the separated lubricating oil is pressurized by the oil pump, cooled and then re-enters the expander. The disadvantage of this solution is that the oil supply system is relatively complicated, the pressure loss of the oil separator has a great influence on the output of the expander, and because the ordinary oil pump cannot be fully sealed, this will aggravate the leakage of the organic Rankine cycle system. See accompanying drawing 2 for the second scheme. In this scheme, there is no oil separator, and the working fluid and lubricating oil are always in a mixed state. The disadvantage is that the internal bearings, mechanical seals and other meshing parts of the expander cannot get sufficient lubricating oil, and the corresponding positions lack effective cooling and lubrication, which may easily lead to problems such as increased leakage, severe wear and local overheating.

Contents of the invention

The object of the present invention is to design a simple and reliable lubricating oil supply system for an organic Rankine cycle positive displacement expander.

An oil supply system for an organic Rankine cycle positive displacement expander, in which a condenser 1, a main pump 2, an evaporator 3, an oil separator 6, and an expander 4 are sequentially connected end to end with working fluid pipelines to form a working Mass circulation loop, oil separator 6 lubricating oil outlet, and the oil injection hole of expander 4 are connected by oil pipes, and the pipeline is filled with organic working medium and lubricating oil mixture; organic Rankine cycle working medium and lubricating oil mixture The liquid mixture enters the evaporator 3 after being pressurized by the main pump 2, and the organic Rankine cycle working medium coming out of the evaporator 3 becomes gaseous, while the lubricating oil is in a liquid state; the gaseous organic Rankine cycle working medium and liquid lubricating oil enter the oil separation 6, the liquid lubricating oil separated from the oil separator 6 is injected into the expander 4; the gaseous organic Rankine cycle working medium and lubricating oil discharged from the expander 4 enter the condenser 1, and the organic Rankine cycle working medium is condensed into a liquid state Finally, it enters the main pump 2 to pressurize and recirculate together with the liquid lubricating oil.

An oil cooler 7 is also connected between the lubricating oil outlet of the oil separator 6 and the oil injection hole of the expander 4, and the liquid lubricating oil separated from the oil separator 6 is cooled by the oil cooler 7 and injected into the expander 4.

The oil cooler 7 is in the form of natural cooling in the pipeline, forced air cooling or water cooling.

The oil separator 6 is a cyclone separation type or a filter element separation type.

The expander 4 is volumetric expansion, including reciprocating, scroll, vane or screw.

The main feature of this system is to place the lubricating oil separator between the expander and the evaporator. That is, what comes out of the evaporator is a mixture of high-pressure organic working medium saturated gas and liquid lubricating oil. After entering the oil separator, the gaseous organic working medium enters the expander to do work, and the lubricating oil separated by the oil separator is in a high-pressure state. The oil pump can be directly injected into the internal mechanical seals, bearings and other positions requiring lubricating oil and cooling of the expander. An oil cooler can also be added on the lubricating oil circuit, so that the corresponding position can be cooled better. The mixture of low-pressure liquid lubricating oil and organic working medium (may be gaseous or gas-liquid two-phase) discharged from the expander enters the condenser, and all condensed into liquid, it is pressurized by the main pump and then enters the evaporator for recirculation.

The benefits of the invention in the oil supply system designed by the invention are: the oil supply system is simple, no oil pump is needed; the influence of the pressure loss of the oil separator on the output of the expander is greatly reduced.

Description of drawings

Attached drawing 1, a schematic diagram of the traditional oil supply method;

Attached drawing 2, the schematic diagram of the second traditional oil supply method;

Accompanying drawing 3, the system diagram of oil supply mode of the present invention.

In the figure: 1. Condenser, 2. Main pump, 3. Evaporator, 4. Positive displacement expander, 5. Working components, 6. Oil separator, 7. Oil cooler.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in FIG. 3 , the system includes a condenser 1 , a main pump 2 , an evaporator 3 , a positive displacement expander 4 , a working part 5 , an oil separator 6 and an oil cooler 7 . Connect the condenser 1, the main pump 2, the evaporator 3, the oil separator 6, and the expander 4 in sequence with the working medium pipeline, and then connect the oil separator 6 lubricating oil outlet, the oil cooler 7, and the oil injection hole of the expander It is connected by oil pipe, and the system is filled with a mixture of organic working medium and lubricating oil. What passes through the component condenser 1, main pump 2 and evaporator 3 is a mixture of lubricating oil and organic working fluid. After the mixture enters the component oil separator 6, the organic working fluid is separated from the lubricating oil, and the organic working fluid enters the expander 4. , and the separated lubricating oil is injected through the oil cooler 7 into the position that needs lubricating oil or cooling inside the expander. The expander 4 provides working power for the working part 5 .

There is no lubricating oil pump in the system, and the main pump 2 is used to increase the pressure of lubricating oil and liquid organic working medium at the same time.

The working part 5 is generally a generator.

The oil cooler 7 can be in the form of utilizing pipeline natural cooling, fan cooling or water cooling. When the internal mechanical seal, bearing, etc. of the expander 4 can allow higher temperatures, the oil cooler may not be provided.

Claims (5)

1. the oil supply system for organic Rankine circulation positive-displacement expansion engine, its feature is: condenser (1), main pump (2), vaporizer (3), oil separator (6), decompressor (4) are connected in turn from beginning to end and form working medium circulation loop with working medium pipeline in turn, between the oil hole of oil separator (6) lubricating oil outlet and decompressor (4), with oil pipe, connect, in pipeline, fill organic Rankine cycle working medium and oil mixture; The liquefied mixture of organic Rankine cycle fluid and oil mixture enters vaporizer (3) after main pump (2) pressurization, from vaporizer (3) organic Rankine cycle fluid out, becomes gaseous state, and lubricant oil is liquid; Gaseous state organic Rankine cycle fluid and liquid lubricant oil enter oil separator (6), and the liquid lubricant oil of separating from oil separator (6) injects in decompressor (4); Gaseous state organic Rankine cycle fluid and the lubricant oil of from decompressor (4), discharging enter condenser (1), and organic Rankine cycle fluid is condensed into after liquid state, enter main pump (2) pressurization circulation again together with liquid lubricant oil.

2. a kind of oil supply system for organic Rankine circulation positive-displacement expansion engine according to claim 1, its feature is: liquid lubricant oil injection decompressor (4) after oil cooler (7) is cooling of be also connected with oil cooler (7) between oil separator (6) lubricating oil outlet and the oil hole of decompressor (4), separating from oil separator (6).

3. a kind of oil supply system for organic Rankine circulation positive-displacement expansion engine according to claim 2, is characterized in that: oil cooler (7) is naturally cooling in pipeline, forced air cooling or water-cooled form.

4. a kind of oil supply system for organic Rankine circulation positive-displacement expansion engine according to claim 1, its feature is: oil separator (6) is cyclone separating or filter core separated type.

5. a kind of oil supply system for organic Rankine circulation positive-displacement expansion engine according to claim 1, its feature is: decompressor (4) is reciprocating for positive displacement expands, comprises, eddy type, sliding vane or screw type.

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