JP2010534785A - Oil removal from turbines in organic Rankine cycle (ORC) systems - Google Patents

Abstract

  In an organic Rankine cycle (ORC) system (10), a method and system for removing oil in the ORC system is used, particularly to avoid failures at start-up. The ORC system (10) includes an evaporator, a turbine, a condenser, and a pump, and is configured to circulate refrigerant in the ORC system. The oil removal system is used to remove oil from a specific area of the turbine (18) and comprises an eductor line (32) and an eductor system (20). The eductor line (32) is arranged upstream of the turbine (18) and is configured to receive a part of the refrigerant (22b) flowing out from the evaporator. The eductor line (32) sends the refrigerant (22b) to the eductor system (20), which removes oil from within the turbine (18) and stores the oil in a sump (58). Send to.

Description

  The present invention relates to an organic Rankine cycle (ORC) system, and more particularly to an improved method and system for recovering oil from a turbine of an ORC system.

  Rankine cycle systems are commonly used to generate electrical power. The Rankine cycle system is an evaporator or boiler that evaporates working fluid, a turbine that receives steam from the evaporator to drive a generator, a condenser that condenses the steam, and recirculates the condensed fluid to the evaporator. A pump or other recirculation means. The working fluid in the Rankine cycle system is usually water, in which case the turbine is driven by steam. The organic Rankine cycle (OCR) system operates in the same manner as a conventional Rankine cycle except that it uses an organic fluid rather than water as the working fluid.

  Oil may be used for lubrication of the ORC system, in particular for lubrication inside the turbine. For example, oil lubricates turbine bearings. However, during operation of the ORC system, this oil can move to areas in the OCR system where oil is not desired, such as the area surrounding the turbine impeller. It is difficult to recover oil from those areas where oil is undesirable when the OCR system is started. This unrecoverable oil may cause a failure when starting the OCR system.

  What is needed is an improved method and system for removing oil from a turbine upon startup of an OCR system.

  In an organic Rankine cycle (ORC) system, an oil removal system that removes oil from the interior of the turbine of the ORC system is used, particularly to avoid failures at start-up. The oil removal system includes an eductor line disposed upstream of the turbine and configured to receive a portion of the refrigerant exiting the ORC system evaporator. The eductor line carries refrigerant to the eductor system, which removes oil from the area surrounding the turbine impeller and sends the oil back to the sump.

1 is a schematic diagram of an organic Rankine cycle (OCR) system comprising a turbine and an eductor system for removing oil from the turbine. FIG. 2 is a schematic diagram of the turbine and eductor system of FIG. 1.

  Organic Rankine cycle (ORC) systems can be used for power generation. Oil is used in the ORC system to lubricate various parts of the equipment, particularly in the turbine of the OCR system. However, when the OCR system is in operation, this oil can move to other areas in the turbine that do not require oil, and this oil can be harmful to some parts of the equipment. There is. Furthermore, if oil is present in a particular area of the turbine, such as an impeller, at system startup, this oil can cause system failure. The present disclosure is directed to providing a method and system for effectively removing oil from a turbine upon startup of an OCR system.

  FIG. 1 schematically illustrates an OCR system 10 that includes a condenser 12, a pump 14, an evaporator 16, a turbine 18, and an eductor system 20 connected to the turbine 18. A refrigerant 22 is used to circulate through the system 10 and generate electric power. The liquid refrigerant 22a from the condenser 12 passes through the pump 14, thereby increasing the pressure. The high-pressure liquid refrigerant 22 a flows into the evaporator 16, and the evaporator 16 evaporates the refrigerant 22 using the heat source 24. Examples of the heat source 24 include, but are not limited to, various types of waste heat such as a fuel cell, a micro turbine, and a reciprocating engine, and other types of heat sources such as the sun, geothermal heat, and exhaust gas. The refrigerant 22 flowing out of the evaporator 16 is a vaporized refrigerant (22b), and flows from this point into the turbine 18 through the turbine inlet valve 26. The refrigerant vapor 22b is used to drive the turbine 18, and the turbine 18 powers the generator 28, which generates electric power. The refrigerant vapor 22b flowing out of the turbine 18 is returned to the condenser 12, where it is condensed so as to return to the liquid refrigerant 22a. Cooling water is supplied to the condenser 12 using a heat sink 30.

  The eductor system 20 is connected to the turbine 18 and is configured to remove oil from an area in the turbine 18 where oil is likely to collect. As will be described in detail below with reference to FIG. 2, the eductor line 32 receives a part of the refrigerant vapor 22 b flowing out of the evaporator 16 and sends this refrigerant 22 b to the eductor system 20.

  As shown in FIG. 1, the OCR system 10 further includes a bypass valve 36 and a bypass line 38 that can be used to prevent the refrigerant 22b from flowing into the turbine 18 during startup. Upon startup of the system 10, the turbine 18 temporarily operates in bypass mode, in which state the turbine 18 supplies refrigerant to the turbine 18 to reach predetermined operating conditions (ie, temperature and pressure). I do not receive it. In this case, the refrigerant 22b is caused to flow through the bypass line 38 and further guided through the bypass orifice 39 in order to increase the temperature of the refrigerant 22b, which is similar to the operating conditions in the turbine 18. . The refrigerant 22 b passes through the bypass orifice 39 and is then guided to the condenser 12. In some embodiments, the bypass valve 36 is closed when the turbine inlet valve 26 is open, and vice versa.

  FIG. 2 schematically illustrates a portion of the ORC system 10 of FIG. 1 that includes a turbine 18, an eductor system 20, an eductor line 32, a turbine inlet valve 26, a generator 28, a bypass valve 36 and a bypass line 38. The turbine 18 includes an impeller 40, a discharge housing 42 and a high pressure volute 44. (This volute 44 is referred to as a “high pressure volute” because it is in a high pressure state when the turbine 18 is operating. However, this volute 44 is referred to when the system 10 and the turbine 18 are in a bypass mode at start-up. The refrigerant vapor 22b (from the evaporator 16) flows through the inlet valve 26 into the high pressure volute 44 and further through the nozzle 46, thereby operating the impeller. A driving force is applied to 40, and the impeller 40 drives a shaft 48 in the gear box 50. A drive shaft 48 is connected to the generator 28 by a gear 52, which uses the energy from the shaft to generate electrical power. The gear box 50 further includes a bearing 54, an oil sump 56, and an oil pump 58.

  An eductor line 32 is disposed upstream of the turbine inlet valve 26 and is configured to receive a portion of the refrigerant vapor 22b that exits the evaporator 16 (and then flows to the turbine 18). This line 32 sends refrigerant 22b to an eductor system 20 configured to remove liquid (mainly oil) from the turbine 18. In the embodiment shown in FIG. 2, the eductor line 32 may be disposed downstream of the bypass line 36, and in an alternative embodiment, the eductor line 32 may be disposed upstream of the bypass line 36.

  By placing an eductor line 32 upstream of the turbine inlet valve 26, the eductor line 32 is continuously connected to the eductor system 20 whenever the refrigerant 22 is circulating in the system 10, regardless of the mode of the turbine 18. The refrigerant 22 can be supplied to the tank. The refrigerant 22 can continue to flow to the eductor system 20 even when the turbine 18 is in bypass mode at start-up and the refrigerant 22 from the evaporator 16 is branched to flow to the bypass line 36.

  In other designs of the ORC system, the eductor line is generally connected to the turbine so that the refrigerant source used in the eductor system is sent from the turbine. For example, the eductor line may be connected to the high pressure volute so that the eductor system uses the refrigerant after passing through the high pressure volute of the turbine. However, in this type of design, the eductor system can only operate when refrigerant from the evaporator is flowing to the turbine. As described above with reference to FIG. 1, refrigerant vapor from the evaporator is prevented from flowing into the turbine at system startup. Instead, the refrigerant flows to the bypass line and further to the condenser. Therefore, if the eductor system relies on refrigerant from the turbine, oil cannot be removed from the turbine when the turbine is in bypass mode, i.e., startup mode.

  However, the start-up mode can be a significant time for removing oil from the area of the turbine surrounding the impeller (ie, the high pressure volute and discharge housing). If the turbine starts up with oil remaining in these areas, some of the equipment in the turbine may be damaged. Furthermore, the oil in the turbine usually moves to the discharge housing and the high pressure volute when the ORC system is operating and particularly when shut down.

  Again, because the eductor line 32 of the system 10 is located upstream of the turbine inlet valve 26 and receives the refrigerant 22b directly from the evaporator 16, the eductor system 20 is in all modes of the operating system 10 in all modes. The oil can be removed from the turbine 18. Since the eductor line 32 receives only a small part of the refrigerant 22 from the evaporator 16, the effect on the operation and efficiency of the turbine 18 is small. For example, in one embodiment, less than 1% by weight of refrigerant 22 from evaporator 16 flows to line 32, and in the preferred embodiment, about 0.2% by weight of refrigerant flows to line 32. In the embodiment shown in FIG. 2, the eductor line 32 is configured to receive the refrigerant 22 whenever the refrigerant 22 is flowing in the ORC system 10, so that the eductor line 32 does not include a valve. However, it will be appreciated that the eductor line 32 may include a control valve. As shown in FIG. 2, the eductor line 32 may include a filter 60 configured to remove particulate matter from the refrigerant 22.

  In the embodiment of FIG. 2, the eductor system 20 includes a first eductor 62 and a second eductor 64 operating as a venturi device, each eductor having a main inlet and a secondary inlet. In each eductor, high pressure refrigerant from the evaporator 16 flows through the main inlet and creates a suction force sufficient to draw liquid from the turbine 18.

  The eductor system 20 further includes a first line 66 and a second line 68 that are both connected to the eductor line 32. The first line 66 is configured to send the refrigerant 22 to the main inlet 70 of the first eductor 62. A secondary inlet 72 of the first eductor 62 is connected to a line 74 and sends oil 76 removed from the discharge housing 42 of the turbine 18 to the first eductor 62. (It will be appreciated that the liquid drawn from the discharge housing 42 is primarily oil, but this liquid may contain some amount of refrigerant.) The second line 68 is the main flow of the second eductor 64. The refrigerant 22 is sent to the inlet 78. A line 80 is connected to the secondary inlet 82 of the second eductor 64 and carries the liquid removed from the high pressure volute 44 of the turbine 18. The liquid drawn from the high pressure volute 44 is mostly oil, but this liquid may contain some of the refrigerant flowing in the turbine 18. These refrigerant and oil flow out of the eductors 62 and 64, and then flow together through the line 84 to the oil sump 56. At this time, the refrigerant, which is vapor, can be recirculated from the oil sump 56 through the line 86 and back to the discharge housing 42.

  As shown in FIG. 2, the eductor system 20 includes two eductors, but it will be understood that the eductor system 20 can operate with only the first eductor 62. Since the eductor line 32 is disposed upstream of the turbine inlet valve 26, the eductor line 32 can always send refrigerant to the first eductor 62. Accordingly, the first eductor 62 is effective in removing oil from the turbine 18, particularly when the turbine 18 is started. Compared to an ORC system that has an eductor system that does not operate at start-up because it relies on refrigerant from the turbine, the present system 10 can be operated at start-up by removing oil from the discharge housing 42 prior to starting the turbine 18. Failure can be significantly reduced.

  Although the second eductor 64 is not essential, the use of the second eductor line 64 in combination with the first eductor 62 and the eductor line 32 may further enhance the effectiveness of the system 10 for removing oil from the turbine 18. It will be understood. As explained above, oil can collect in both the discharge housing 42 and the high pressure volute 44. The second eductor 64 can remove oil from the high-pressure volute 44, but this high-pressure volute 44 usually collects oil as soon as the oil and refrigerant vapor separate in the volute 44. By using a system with two eductors, the oil recovery can be improved because the oil can be removed from both areas where the oil around the impeller 40 can accumulate.

  Although the present disclosure focuses on the use of the eductor line 32 and the eductor system 20 when the turbine 18 is started, the oil removal system described herein may be used at any point in time when the ORC system is operating. It will also be appreciated that it is used to remove oil from the discharge housing and high pressure volute. This includes the mode of operation of the turbine when refrigerant from the evaporator is flowing into the turbine.

  Although the invention has been described with reference to preferred embodiments, those skilled in the art will recognize that several changes can be made in form and detail without departing from the spirit and scope of the invention.

Claims (20)

An oil removal system for avoiding a failure in an organic Rankine cycle (ORC) system comprising an evaporator, a turbine, a condenser and a pump and configured to circulate a refrigerant therein,
An eductor line disposed upstream of the turbine and configured to receive a portion of the refrigerant flowing out of the evaporator;
An eductor system configured to receive refrigerant from the eductor line and draw liquid from the turbine;
With oil removal system.   The oil removal system of claim 1, wherein the eductor system comprises a first eductor configured to receive refrigerant from the eductor line and draw liquid from a discharge housing of the turbine.   The oil removal system of claim 2, wherein the eductor system comprises a second eductor configured to receive refrigerant from the eductor line and draw liquid from a high pressure volute of the turbine.   The oil removal system of claim 1, further comprising an oil sump configured to receive the drawn liquid from the eductor system.   The oil removal system according to claim 1, wherein the refrigerant flowing out of the evaporator is in a vapor state.   The oil removal system according to claim 1, wherein the refrigerant flowing out of the evaporator includes oil.   The oil removal system according to claim 1, wherein the liquid drawn from the turbine includes oil, a refrigerant, and a mixture thereof.   The oil removal system of claim 1, wherein the eductor line comprises a filter configured to remove particulate matter from the refrigerant. A condenser configured to condense the refrigerant vapor;
A pump configured to increase the pressure of the condensed refrigerant;
An evaporator configured to receive the condensed refrigerant and vaporize the refrigerant;
A turbine configured to generate electric power upon receipt of refrigerant vapor, including an impeller, a discharge housing, a high pressure volute, and a sump;
An inlet valve configured to control the supply of refrigerant from the evaporator to the turbine;
A bypass valve configured to prevent refrigerant from flowing into the turbine and to branch to the condenser upon startup of the turbine;
An eductor line disposed upstream of the inlet valve and configured to receive a portion of the refrigerant from the evaporator;
An eductor system configured to receive refrigerant from the eductor line and draw liquid from the turbine;
An organic Rankine cycle (ORC) system for power generation.   10. The ORC system of claim 9, wherein the eductor system comprises a first eductor configured to receive refrigerant from the eductor line and to draw liquid from a discharge housing of the turbine.   11. The ORC system of claim 10, wherein the eductor system comprises a second eductor configured to receive refrigerant from the eductor line and draw liquid from a high pressure volute of the turbine.   The ORC system of claim 9, wherein the inlet valve is in a closed position when the bypass valve is in an open position.   10. The ORC system of claim 9, wherein the weight of refrigerant received by the eductor line is less than 1% of the total weight of refrigerant from the evaporator.   The ORC system of claim 9, wherein the eductor line includes a filter configured to remove particulate matter from the refrigerant. A method of operating an organic Rankine cycle (ORC) system having an evaporator, a turbine, and a refrigerant circulating through the evaporator and the turbine, comprising:
Prevent the refrigerant flowing out of the evaporator from flowing into the turbine when starting up the turbine;
Upon startup of the turbine, the refrigerant from the evaporator is sent to a bypass line configured to send the refrigerant to the condenser;
Send a portion of the refrigerant from the evaporator to the eductor system,
Drawing liquid from the turbine using the eductor system;
Including methods. Sending a portion of the refrigerant from the evaporator to the eductor system;
Sending a first portion of the refrigerant to a first eductor configured to draw liquid from a discharge housing of the turbine;
Sending a second portion of the refrigerant to a second eductor configured to draw liquid from a high pressure volute of the turbine;
The method according to claim 15, comprising:   The method of claim 15, wherein a portion of the refrigerant from the evaporator is sent to the eductor system via an eductor line located upstream of the turbine.   The method of claim 15, wherein a portion of the refrigerant sent to the eductor system is less than 1% of the total weight of refrigerant from the evaporator.   The method of claim 15, further comprising sending liquid drawn from the turbine to a sump of the turbine.   The method of claim 15, wherein the liquid drawn from the turbine comprises at least one of oil, refrigerant, and mixtures thereof.

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