MXPA01003225A - Method and apparatus for increasing the efficiency of a multi-stage compressor - Google Patents

Abstract

A multi-stage compressor, including a system for the injection of a cooling liquid into at least a portion of the compressor stages to increase the efficiency of the multi-stage compressor by reducing the temperature of the compressed gas produced in the multi-stage compressor. A cleaning solution may also be injected through nozzles used for the injection of the cooling liquid.

Description

METHOD AND APPARATUS FOR INCREASING THE EFFICIENCY OF A COMPACTOR OF MULTIPLE STAGES FIELD OF THE INVENTION This invention relates to an improvement in the manufacture and operation of multi-stage compressors to achieve an increased efficiency by cooling the compressed gas in at least a portion of the stages and by cleaning the rotors in at least a portion of the stages by the injection of chemical cleaning substances by means of the nozzles used for the injection of a cooling fluid in at least a portion of the stages.

PREVIOUS ART In many industrial applications such as the use of turbines to generate electrical power and the like, it is necessary that large volumes of gas, such as air, be compressed at relatively high pressures. Although various types of gases such as hydrogen, natural gas, and the like are frequently compressed, the present invention will be described primarily by reference to air compression, although Ref.128423 with other gases is also useful. Typically, large amounts of air are compressed for use in the combustion of natural gas or the like to provide a gaseous stream for use in driving turbines to generate electricity. When the gases are compressed, it is well known that the temperature of the compressed gas increases when the pressure increases. In some cases, when high pressures are desired, it has been necessary to use a first compressor followed by interstage cooling and subsequent compression in a second compressor to achieve the desired compression levels within the temperature limitations of the compressors. In some cases, more than two compression stages have been required. The use of such intercooler steps has not been considered feasible for multi-stage compressors, particularly axial compressors comprising a plurality of stages with each stage comprising a set of rotor blades or vanes and a set of vanes or vanes of the rotor. stator, which have been used to compress the air for use in the generation of electricity. Axial compressors have been the preferred types of the compressor for this application. An additional problem in the maintenance of the capacity of the compressors used for such purposes has been the tendency of the blades or blades of the compressor to get dirty. This leads to a substantial loss of power in the compressor. Several techniques have been used in attempts to clean the blades and prevent the loss of power. Some of such techniques are described in "Gas Turbine Compressor Washing State of the Art - Field Experiences" by Jean Pierre Stadler, The American Society of Mechanical Engineers, 98-GT-420, 1998. In this article several techniques have been described for cleaning the deposits of the blades or blades of the compressors. It seems that the cleaning solutions were introduced by means of the air inlet to the compressors. As a result of the large amount of air required for the generation of electrical power as well as the requirements of large volumes of other gases, a continuous search has been directed to the development of a method and design of the compressor, which can compress the more efficient way gases.

BRIEF DESCRIPTION OF THE INVENTION According to the present invention, the increased efficiency in such compressors can be achieved by a method to increase the compression efficiency in a multi-stage compressor by injecting a finely divided amount of mist of a selected liquid in at least one stage of the compressor to reduce the temperature of a compressed gas in at least one stage, whereby compression is allowed at an increased efficiency. The invention further comprises a multi-stage compressor which includes a plurality of nozzles positioned to inject a quantity of a finely divided mist of a selected liquid in at least one stage of the compressor to reduce the temperature of a compressed gas stream in at least one stage whereby more efficient compression is possible of compressed gas and a reduction in the compressor power requirement. The invention further comprises a multi-stage gas compressor comprising: an external housing having an internal part and an external part, an inlet and an outlet and supporting on its inner surface a plurality of rows of vanes or stator vanes distributed around the inner part of the outer housing; a rotor rotatably disposed within the outer housing, having an outer side, a first end near the entrance of the outer housing and a second end near the outlet of the outer housing and a plurality of rows of the stator vanes or vanes distributed around on the outer side of the rotor with at least a portion of the rows of blades or rotor blades that are between the rows of blades or blades of the stator, each row of the blades or blades of the rotor with a subsequent row of blades or blades of the stator forming a single stage of the compressor; and at least one mist injection nozzle positioned to inject a selected amount of a finely divided mist of a selected liquid into the compressor between at least a pair of the stator vanes or vanes in at least one of the rows of the vanes or stator blades in at least one stage to enable more efficient compression of a compressed gas. The invention further comprises a method for increasing the efficiency of the compressor in a multi-stage gas compressor comprising: an external housing having an internal side and an external side, an inlet and an outlet supporting on its internal surface a plurality of rows of vanes or stator vanes distributed around the inner side of the outer housing; a rotor rotatably disposed within the outer housing, having an outer side, a first end near the entrance of the outer housing and an outlet near the outlet of the outer housing and a plurality of rows of the rotor blades or vanes distributed around the outer side of the rotor, each row of the blades or vanes of the rotor taken with a subsequent row of the vanes or blades of the stator forming a single stage of the compressor; and, at least one nozzle for injecting the mist placed to inject a selected amount of a mist finally divided from a selected liquid within the compressor between at least a pair of the stator vanes or blades and at least one of the rows of the vanes or blades of the stator.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of an axial multi-stage compressor; Figure 2 is a cross-sectional view of the compressor of Figure 1 taken on line AA; Figure 3 is a cross-sectional view of a nozzle installed through an external housing of the compressor shown in Figure 1; Figure 4 is a cross-sectional view of a nozzle suitable for use in the practice of the present invention; and, Figure 5 is a schematic diagram of the pipe used to inject the selected liquid into the compressor shown in Figure 1.

DESCRIPTION OF THE PREFERRED MODALITIES In the description of the Figures, the same numbers that will be used from start to finish will refer to the same components or similar components. The additional details of the construction and operation of the compressors not necessary for the description of the present invention have not been shown or described. In Figure 1 an axial compressor 10 having a central shaft 11 is shown. The compressor 10 comprises an outer housing 12 having an outer side 68 and an inner side 70. A rotor 14 is axially positioned within the outer housing 12 for rotation and includes an outer side 76. The rotor 14 as shown is rotationally driven by an axis 16 which can be coupled by any convenient power source. An outer liner 12 further includes an inlet 18, which is typically covered by a screen or screen 20, or the like, to prevent passage of the particulate materials toward the compressor 10. An arrow 21 shows the flow of air to the compressor 10. with the flow of air inside the compressor 10 to the compression that is shown by the arrows 22. The compressor 10 includes a plurality of rotor blades or vanes 24R placed in a row generally around the outer side 76 of the rotor 14 to interact with the vanes or blades of the 24S stator. The vanes or rotor blades rotate when the rotor 14 is rotated to drive the gas to a discharge from the compressor 10 as shown by the arrows 23. The discharged air can be passed for use in any of a variety of desired applications . In the previously mentioned applications, when the gas is air, it can be passed for combination with a combustible gas so that the combustion produces a hot gas to drive a turbine or the like. A plurality of pairs of vanes or vanes of the rotor and stator are shown. The combinations of the rotor and stator 24R and 24S form a stage of the compressor 10. In a similar manner the combinations 26R and 26S, 28R and 28S, 30R and 30S, and 32R and 32S form stages. Not all blades or vanes of the rotor and stator have been numbered. When the gas is driven by the blades or rotor blades, the blades or blades of the rotor tend to maintain a relatively smooth flow along the axial length of the compressor 10. As shown by the arrows 34, according to the present invention, a cooling liquid is desirably injected into the compressor 10 between the blades or blades of the stator in the rows formed by the stators 24S, 26S, 28S, etc. The cooling liquid can be injected in any or all of the stages and is desirably injected at the locations or sites uniformly spaced around each of the injected rows of the blades or blades of the stator. In Figure 2, a more detailed view of the injection system is shown. A final view is taken at the front of the rows of the vanes or vanes 24S of the stator as indicated by the line AA. An extreme view of the stator 14 is shown. For reasons of simplicity, the stator 14 has been shown as a solid body considering in fact that it is typically of a hollow element construction which is of sufficient strength to support the rotor vanes or vanes and the like. Such details do not form part of the present invention. The vanes or vanes 24 of the stator are shown with a feed line 34 of the nozzle extending to the spaces between each pair of the vanes or vanes of the stator. As it is shown, lines 34 are flexible hose lines which extend from a manifold pipe 32 to a nozzle assembly 38 (shown in Figure 3) at each injection site. The nozzle assemblies 38 are supplied with a liquid from a feed line 36 by means of a pipe 32 of the manifold as will be described in greater detail here below.

As previously noted, a cooling liquid can be injected between any or all of the pairs of the stator blades or vanes, but it is preferably injected at evenly spaced locations around each injected row of the stator vanes or blades . The determination as to whether an injection should be made between a selected number or all of the stator blades or blades, is a function of the amount of cooling desired in the particular stage and the like. In Figure 3, a more detailed construction of a nozzle positioned through the outer housing 12 is shown. The two vanes or vanes 24S of the stator are shown with the assembly 38 of the nozzle which is positioned to inject a mist of a liquid between the two vanes or blades of the stator. The nozzle 40 is designed to be normally recessed a slight distance away from the inner side of the outer housing 12. Details of the construction of the nozzle will be described below but generally the nozzle 40 is formed of a relatively thick wall material which includes a feed line 34 which extends to a junction with manifold pipe 32. Although the feed lines 34 of the nozzle have been shown as a pipe in Figure 3, the feed line of the nozzle upstream of the tubular lines 34 can be, and desirably is, a flexible hose as is known to those skilled in the art to transmit liquids under high pressure. The flexible hose can in effect extend from line 32 to and to be connected with a connector 42, which is used to sealingly place the nozzle assembly 38 through the outer housing 12. The connector 42 as shown , includes an element which can be screwed into position and includes a ring seal at 0 44. Alternatively, the connector 42 could be welded in its position or otherwise sealed in its position by other known mechanical means by those skilled in the art and sufficient to prevent leakage of compressed air from inside the outer housing 12 around the nozzle 40. The nozzle assembly 38 is shown in greater detail in Figure 4 and comprises a nozzle 40 which is a thick-walled section which has apertures 50 drilled to spray a mist finely divided from the nozzle in a selected configuration and which is sealed in a sealed manner with line 34 by any suitable connection, shown in Figure 4 as welds 55. Openings 50 are desirably drilled by a laser beam or other means to produce an extremely small passageway desirably less than about 0.0381 cm ( 0.015 inches) in diameter. The nozzle assembly 38 in an opening 51 positioned through an external wall of the outer housing 12, dimensioned to tightly contain the nozzle assembly 38 and having a section 53 of reduced diameter smaller than an outer diameter 57 from the nozzle 40 at its outlet end inside the compressor 10. The section 34 of the pipe is a thick-walled pipe section which extends upwardly to the connector 42 and may extend beyond the connector 42 if desired. As previously indicated, it is desirable that at least a portion of the line 34 above the connector 42 comprises a flexible hose for ease of placement and operation. The nozzle 40 is sized to fit snugly in the opening 51 and has an outer diameter larger than the section 53 of reduced diameter. The nozzle 40 is made of a thick wall material and since it is larger in diameter than the reduced diameter section 53, it can move through the reduced diameter section and prevents the entry of any particulate materials. , the component parts and the like, inside the compressor 10 through the opening 51.

The manifold 32 shown in Figure 2 may be a pipe and may be placed around the outer shell 12 by any convenient method. In Figure 5, a schematic diagram of the flow lines for at least a portion of the nozzles is shown. Line 36, as shown in Figure 3, includes upstream from line 32 a check valve 46. This check valve is effective to prevent any loss of compressed gas from compressor 10 in the event that there is no flow of liquid inside the compressor 10 through line 36. The check valve 46 prevents the flow of liquid or gas through line 36 from line 32 and outer shell 12. Upstream from check valve 46 , a measuring hole 52 of any suitable design known to those skilled in the art, is positioned on line 36. A differential pressure meter 54 is connected to measure the differential pressure through the orifice 52 and determines the flow rate through line 36. The differential pressure meter 54 includes a connection 56 to a computer (not shown) which is used to control the injection to the compressor 10 as will be described further. In addition, upstream of the measurement orifice 52, a control valve 58 is placed on the line 36. The control valve 58 is activated and regulated by a control connection 60 which can be actuated by a computer signal. The computer functions to regulate the flow of liquid through the valve 58 for each injection stage so that the controlled quantities of liquid can be injected into the compressor 10 when desired from line 36 through line 32 of the manifold , the flexible hoses 34 and nozzle assemblies 58 for controlling the temperature of the compressed gas flowing through the compressor 10. The amount of the finely divided mist is a fraction of a percentage of the total gas flow through the compressor. The additional mass flow as a result of the addition of water is so small that it can be neglected in the calculations of the power required to drive the compressor. Also in Figure 5, a line 62 is shown for the addition of a chemical cleaning stream to line 36. The flow of the liquid through this line is controlled by a control valve 64, which is regulated by a line 66 to a control computer. The control computer acts on the information collected from lines 56, 60, 66 and other information such as the discharge temperature of the compressed gas, the temperature of the gas in at least a portion of the stages, and the like, to determine the amount of liquid that will be loaded through each nozzle to each stage. Although not shown, the temperature sensors may be positioned to detect the temperature in at least a portion of the stages and the like. In addition, the gas pressure can be measured in a portion of the stages and the inlet and outlet temperatures of the compressor 10 can be measured, as well as the outlet pressure. In general, it is believed that the temperature in an axial compressor of the type shown will be such that any water injected into the compressor after approximately step 8 will be completely vaporized in the stream immediately. The liquid is injected as a finely divided mist which can remain as a vaporous mist in the stages at a temperature below the boiling point of the water when the air moves along the length of the compressor 10 to stage 8. Air velocity axially along the compressor 10 is difficult to determine but is estimated to be from about 152.4 meters per second (500 feet per second) to about 167.64 meters per second (550 feet per second) during normal operation. In consecuense, the residence time of the average air in the compressor 10 is a small fraction of a second. As a result, the finally divided mist is present in a highly turbulent air stream and is probably vaporized at least partially when it moves through the stages prior to the stages which operate at a temperature above the boiling point of the water . As a result of the injection of the liquid, which is desirably water when the air is compressed gas, the air temperature is reduced in each stage by a small amount with the net result that the amount of work for gas compression up to The desired pressure is reduced. If the liquid is injected in the stages close to the discharge of the compressor, it may be necessary to preheat the liquid prior to the injection to avoid thermal shock with the equipment. Not only is the amount of work required reduced, but also as a result of the reduction of temperature a larger mass of compressed gas can be produced from a compressor of a given size at a desired pressure. As is well known to those skilled in the art, temperature and air density increase rapidly when the gas is compressed. Since the increased temperature makes it more difficult to compress the gas, the cooling of the gas in at least a portion of the stages leads to the production of a given mass of compressed gas at a given pressure at a lower temperature. Accordingly, the efficiency of the compression is increased by the use of the progressive injection of the cooling liquid along the length of the axial compressor 10.

Similarly, it is known that the fouling of the vanes or vanes in the axial compressors is very detrimental to the efficiency of the compression operation. As a result, considerable effort has been developed to determine how contaminants can be removed from the vanes or vanes in axial compressors and other compressors. In the article "Gas Turbine Compressor Washing State of the Art-Field Experiences" ("State of the Washing of the Compressors with Gas Turbine of the Experiences of the Field of the Technique"), by Jean Pierre Stalder, referred as previously, it is recognized that the contamination on the blades or blades of the compressor is very detrimental to the operations of the compressor. It seems from the article that the attempts described to remove the contamination injected cleaning solutions only in the incoming gas. Not only have previous attempts been made to clean the contamination of the vanes or vanes of the injector by injecting cleaning materials with the inlet gas, but also attempts have been made to improve the efficiency of the compressor by cooling the inlet gas charged to the compressor. An attempt to achieve such cooling is the use of water spray mists, which are discharged into the incoming gas. The use of cooling mists in this way does not cool the compressor over some substantial portion of its length. The net result is simply an addition to the humidity of the gas at the inlet with a small effect on the discharge temperature of the gas. In contrast, the use of the present invention to inject a cooling liquid along the length of the compressor 10 leads to a substantial reduction in the amount of work required to compress the gas. Having thus described the invention by reference to certain of its preferred embodiments, it is respectfully pointed out that the described embodiments are illustrative rather than limiting in nature and that many changes and variations are possible within the scope of the present invention. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based on a review of the prior description of the preferred embodiments.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.

Claims (19)

1. K. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. A multi-stage gas compressor, characterized in that it comprises: a) an external housing having an internal side and an external side, an inlet and an outlet and supporting on its inner surface a plurality of rows of vanes or blades of the stator distributed around the inner side of the outer housing; b) a rotor rotatably positioned within the inner housing having an outer side, a first end near the entrance of the outer housing and a second end near the outlet of the outer housing and a plurality of rows of the rotor blades or vanes distributed around the outer side of the rotor, each row of the blades or rotor blades taken with the subsequent row of the blades or stator blades forming a single stage of the compressor; and c) at least one mist injection nozzle positioned to inject a selected amount of the finely divided mist of a selected liquid into the compressor between at least a pair of the stator blades or blades in at least one of the rows of the vanes or blades of the stator. The compressor according to claim 1, characterized in that a plurality of the mist injection nozzles are positioned to inject a finely divided mist of a selected liquid into the compressor at a plurality of locations between the pairs of the blades or Stator blades in at least one row of blades or stator blades. The compressor according to claim 1, characterized in that at least one mist injection nozzle is positioned to inject a finely divided mist of a selected liquid into the compressor between at least a pair of the stator vanes or vanes in a plurality of rows of blades or blades of the stator. The compressor according to claim 3, characterized in that a plurality of mist injection nozzles are positioned to inject a finely divided mist of a selected liquid into the compressor at a plurality of sites between the pairs of the vanes or vanes of the stator in a plurality of rows of blades or blades of the stator. 5. The compressor according to claim 1, characterized in that at least a portion of the injection nozzles comprises an outlet of the injection nozzle positioned to inject a finely divided mist into the compressor and a nozzle feed line, the nozzle Injection is in fluid communication with a high pressure liquid source outside the outer housing by means of the nozzle feed line. The compressor according to claim 5, characterized in that the nozzle feed line includes a check valve. The compressor according to claim 5, characterized in that at least a portion of the nozzle feed line comprises a flexible hose. The compressor according to claim 5, characterized in that the nozzle feed line includes a device for flow measurement and a flow regulating valve. The compressor according to claim 8, characterized in that the compressor includes a computer in operative communication with at least one of the flow measuring devices and the flow regulation valve to control the amount and the injection site of the liquid injected. The compressor according to claim 5, characterized in that the compressor includes a source of a cleaning chemical and a chemical feed line in fluid communication with at least a portion of the nozzle feed lines to make possible the injection of at least one cleaning chemical into the compressor. 11. A method to increase the capacity of a gas interceptor of mixed stages, characterized in that it is an external housing having an internal side and an external side, an inlet and an outlet and supporting on its internal surface a plurality of rows of vanes or stator vanes distributed around the inner side of the outer housing; a rotor rotatably positioned within the outer housing having an outer side, a first end near the entrance of the outer housing and an outlet near the outlet of the outer housing and a plurality of rows of the rotor vanes or vanes distributed around the side external of the rotor, each row of blades or blades of the rotor that is taken with the subsequent row of the blades or blades of the stator forming a single stage of the compressor; and, at least one mist injection nozzle positioned to inject a selected amount of a finely divided mist of a selected liquid into the compressor between at least a pair of the stator vanes or blades in at least one of the rows of the blades or blades of the stator, by injection of a finely divided amount of mist of a selected liquid into the compressor between at least a pair of blades or blades of the stator. 12. The method in accordance with the claim 11, characterized in that the liquid injected is water. 13. The method according to the claim 12, characterized in that the water is injected into at least a portion of the steps in the compressor in an amount sufficient to reduce the temperature of a stream of compressed gas discharged from the compressor at a selected temperature. The method according to claim 12, characterized in that a second stream of liquid containing a cleaning chemical is injected into the compressor to clean at least a portion of the stator vanes or blades and at least a portion of the paddles or rotor blades. 15. The method according to claim 14, characterized in that the cleaning chemical is injected into at least one of the first three stages. 16. A multi-stage compressor, characterized in that it includes at least one nozzle positioned to inject an amount of a finely divided mist of a selected liquid in at least one stage of the compressor to reduce the temperature of a compressed gas stream in at least one stage, whereby the compression of an increased amount of the gas at a selected discharge pressure becomes possible. The compressor according to claim 16, characterized in that the compressor is an axial compressor wherein the compressor comprises: a) an external housing having an internal side and an external side, an inlet and an outlet and supporting on its internal surface a plurality of rows of blades or blades of the stator distributed around the inner side of the outer housing; b) a rotor rotatably positioned within the inner housing having an outer side, a first end near the entrance of the outer housing and an outlet near the outlet of the outer housing and a plurality of rows of the rotor vanes or vanes distributed around on the outer side of the rotor, each row of the blades or rotor blades taken with the subsequent row of the blades or blades of the stator forming a single stage of the compressor; and c) at least one mist injection nozzle positioned to inject a selected amount of the finely divided mist of a selected liquid into the compressor between at least a pair of the stator blades or blades in at least one of the rows of the vanes or blades of the stator. 18. The compressor according to claim 16, characterized in that the compressor is a centrifugal compressor. 19. A method for increasing the capacity of a multi-stage compressor by injecting a quantity of finely divided mist of a selected liquid in at least one stage of the compressor to reduce the temperature of a compressed gas in at least one stage so which allows the compression of an increased amount of the compressed gas at a selected discharge temperature.