Patent Application
20160040927
1. Field of the Invention
The embodiments disclosed herein relate to processes and systems for liquefying natural gas.
2. Description of the Related Art
Natural gas is becoming an increasingly important source of energy. In order to allow transportation of the natural gas from the source of supply to the place of use, the volume of the gas must be reduced. Cryogenic liquefaction has become a routinely practiced process for converting the natural gas into a liquid, which is more convenient, less expensive and safer to store and transport. Transportation by pipeline or ship vessels of liquefied natural gas (LNG) becomes possible at ambient pressure, by keeping the chilled and liquefied gas at a temperature lower than liquefaction temperature at ambient pressure.
In order to store and transport natural gas in the liquid state, the natural gas in an embodiment is cooled at around −150 to −170° C., where the gas possesses a nearly atmospheric vapor pressure.
Several processes and systems exist in the prior art for the liquefaction of natural gas, which provide for sequentially passing the natural gas at an elevated pressure through a plurality of cooling stages whereupon the gas is cooled in successively lower temperatures in sequential refrigeration cycles until the liquefaction temperature is achieved.
Prior to passing the natural gas through the cooling stages, the natural gas is pre-treated to remove any impurities that can interfere the processing, damage the machinery or are undesired in the final product. Impurities include acid gases, sulfur compounds, carbon dioxide, mercaptans, water and mercury. The pre-treated gas from which impurities have been removed is then cooled by refrigerant streams to separate heavier hydrocarbons. The remaining gas mainly consists of methane and usually contains less than 0.1% mol of hydrocarbons of higher molecular weight, such as propane or heavier hydrocarbons. The thus cleaned and purified natural gas is cooled down to the final temperature in a cryogenic section. The resulting LNG can be stored and transported at nearly atmospheric pressure.
Cryogenic liquefaction is usually performed by means of a multi-cycle process, i.e. a process using different refrigeration cycles. Depending upon the kind of process, each cycle can use a different refrigerating fluid, or else the same refrigerating fluid can be used in two or more cycles.
The propane is processed in a second or pre-cooling cycle. The second cycle comprises a line including a gas turbine 13, which drives a multi-stage compressor 15. The compressed propane delivered by compressor 15 is condensed in a condenser 17 against water or air. The condensed propane is used to pre-cool the natural gas down to −40° C. and to cool and partially liquefy the mixed refrigerant. The natural gas pre-cooling and the mixed refrigerant partial liquefaction is performed in a multi-pressure process, in the example shown 4-level of pressure.
The stream of condensed propane from condenser 17 is delivered to a first set of four, serially arranged heat exchangers to cool and partly liquefy the mixed refrigerant and to a second set of four, serially arranged, pre-cooling heat exchangers to cool the natural gas. A first portion of the compressed propane stream from condenser 17 is delivered through pipe 19 to the first set of heat exchangers and is sequentially expanded in serially arranged expanders 21, 23, 25 and 27 to four different, gradually decreasing pressure levels. Downstream each expander 21, 23 and 25 a portion of the expanded propane flow is diverted to a respective heat exchanger 29, 31, 33. The propane flowing through the last expander 27 is delivered to a heat exchanger 35.
The compressed mixed refrigerant delivered from the heat exchanger 11 flows in a pipe 37 towards a main cryogenic heat exchanger 38. The pipe 37 sequentially passes through the heat exchangers 29, 31, 33 and 35, such that the mixed refrigerant is gradually cooled and partly liquefied against the expanded propane.
A second fraction of the condensed propane flow from condenser 17 is delivered to a second pipe 39 and expanded sequentially in four serially arranged expanders 41, 43, 45 and 47. A part of the propane expanded in each expander 41, 43 and 45 as well as the propane flowing from the last expander 47 is diverted towards a corresponding pre-cooling heat exchanger 49, 51, 53 and 55, respectively. A main natural gas line 61 flows sequentially through the pre-cooling heat exchangers 49, 51, 53 and 55, such that the natural gas is pre-cooled before entering the main cryogenic heat exchanger 38. Heated propane exiting the pre-cooling heat exchangers 49, 51, 53 and 55 is collected with the propane exiting the heat exchangers 29, 31, 33 and 35 and is fed again to the compressor 15, which recovers the four evaporated propane side streams and compresses the vapor to e.g. 15-25 bar to be condensed again in condenser 17.
The subject matter disclosed herein concerns an improved natural gas liquefaction system comprising at least a pre-cooling circuit or loop wherein a first refrigerant is caused to circulate, and at least one cooling or liquefying loop, wherein a second refrigerant is caused to circulate. A natural gas in the gaseous state is caused to flow through a heat exchangers arrangement of the pre-cooling loop and subsequently in a heat exchangers arrangement of the cooling or liquefying loop. The natural gas is pre-cooled, cooled and finally liquefied by exchanging heat against the first refrigerant and at least the second refrigerant. Additional third or further cooling and/or liquefying circuits or loops can be arranged in a cascade or sequence arrangement to gradually chill and finally liquefy the natural gas. The loops contain respective compressor arrangements for processing the respective refrigerants, as well as at least one condenser and one or more expansion elements, e.g. turboexpanders and/or throttling valves. At least the pre-cooling loop comprises an integrally-geared turbo-compressor for processing the first refrigerant. The first refrigerant can be divided into two or more side streams, used to exchange heat at gradually decreasing pressure values, against the natural gas and/or the refrigerant circulating in the subsequent cooling or liquefying loop.
According to some embodiments, a natural gas liquefaction system is provided, comprising: at least a pre-cooling loop, through which a first refrigerant is adapted to circulate, the pre-cooling loop comprising: at least one compressor for pressurizing the first refrigerant; at least one prime mover for driving the compressor; at least one condenser for removing heat from the first refrigerant; at least a first expansion element for expanding the first refrigerant; at least a first heat exchanger for transferring heat from natural gas to the first refrigerant; and at least a cooling loop, downstream of the pre-cooling loop, where through a second refrigerant circulates, the natural gas being adapted to be sequentially cooled in the pre-cooling loop and in the cooling loop; wherein the compressor is an integrally-geared turbo-compressor comprising a plurality of compressor stages each one being provided with an independent set of movable inlet guide vanes for autonomously regulating flows entering in the compressor stages.
According to some embodiments, additional compressor stages can be provided, which are not provided with movable inlet guide vanes. When a plurality of compressor stages are disposed in series, a single set of movable inlet vanes is enough, since the downstream stages are regulated by the set of movable inlet vanes of the more upstream stage. Compressor stages disposed in series could be equipped with respective set of movable inlet vanes when the first refrigerant stream is divided in two or more side streams and successively re-united in an intermediate position between two subsequent compressor stages.
According to another aspect, a method of liquefying natural gas, is provided, wherein a flow of natural gas is cooled and liquefied by heat exchange against at least a first refrigerant circulating in a pre-cooling loop and a second refrigerant circulating in a cooling and/or liquefying loop. The first refrigerant is divided into a plurality of side streams at gradually decreasing pressure values. The side streams exchange heat against the natural gas flow and/or against the second refrigerant. The side streams are returned at respective compressor stages of an integrally-geared turbo-compressor.
According to one embodiment, a method is provided, comprising: providing a pre-cooling loop comprising: an integrally-geared turbo-compressor having a plurality of compressor stages, at least one condenser, at least one expansion element, and at least one heat exchanger; driving the integrally-geared turbo-compressor with a prime mover; circulating a first refrigerant through the integrally-geared turbo-compressor; condensing the first refrigerant delivered by the integrally-geared turbo-compressor in the condenser; dividing the first refrigerant in a plurality of partial flows; expanding the condensed first refrigerant in the expansion element; circulating the expanded refrigerant through the heat exchanger to remove heat from the natural gas, to pre-cool the natural gas; controlling independently movable inlet guide vanes to regulate the partial flows at the suction side of the compressor stages; providing at least one cooling loop; circulating a second refrigerant in the at least one cooling loop; remove heat from the pre-cooled natural gas by heat exchange against the second refrigerant.
Features and embodiments are disclosed here below and are further set forth in the appended claims, which form an integral part of the present description. The above brief description sets forth features of the various embodiments of the present invention in order that the detailed description that follows may be better understood and in order that the present contributions to the art may be better appreciated. There are, of course, other features of the invention that will be described hereinafter and which will be set forth in the appended claims. In this respect, before explaining several embodiments of the invention in details, it is understood that the various embodiments of the invention are not limited in their application to the details of the construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
The flow rates of first refrigerant elaborated by the present system and method are controllable acting not only to the rotational speed of compressor stages. In this way, a more efficient and reliable LNG circuit is provided.
As such, those skilled in the art will appreciate that the conception, upon which the disclosure is based, may readily be utilized as a basis for designing other structures, methods, and/or systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
A more complete appreciation of the disclosed embodiments of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
The following detailed description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Additionally, the drawings are not necessarily drawn to scale. Also, the following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims.
Reference throughout the specification to “one embodiment” or “an embodiment” or “some embodiments” means that the particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrase “in one embodiment” or “in an embodiment” or “in some embodiments” in various places throughout the specification is not necessarily referring to the same embodiment(s). Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.
In some embodiments the first refrigerant circulating in the pre-cooling loop can include or consist of propane. The first refrigerant can have a mean molecular weight of at least 35, for example between 35 and 41. In some embodiments the second refrigerant circulating in the second loop can include a mixed refrigerant, for example comprising nitrogen, methane, ethane and propane.
More specifically, in the embodiment of
The pre-cooling loop 103 comprises a multi-stage, integrally-geared turbo-compressor 109. The integrally-geared turbo-compressor can be configured as shown in more detail in
At least one, some, or more particularly all the stages of the integrally-geared turbo-compressor are comprised of movable inlet guide vanes, to adjust the operative conditions of the stage(s) according to the actual operative needs of the system 101. Each set of movable inlet guide vanes can be adjusted independently of the other, for instance in order to take into account flow rates which differ from one stage to the other.
In some embodiments the integrally-geared turbo-compressor comprises a number of stages comprised between two and eight. For example, the integrally-geared turbo-compressor can comprise from three to six stages. As will be described in more detail later on, one or more inter-coolers can be provided between one or more pairs of sequentially arranged stages of the integrally-geared turbo-compressor. Moreover, in some embodiments, at least one, some, or preferably all the stages of the integrally-geared turbo-compressor are comprised of movable inlet guide vanes, to adjust the operative conditions of said stage(s) according to the actual operative needs of the system 101. Each set of movable inlet guide vanes can be adjusted independently of the other, for instance in order to take into account flow rates which differ from one stage to the other.
In some embodiments the multi-stage, integrally-geared turbo-compressor 109 can be driven by a prime mover, which can include an internal combustion motor, such as a gas turbine, for instance an aeroderivative gas turbine. In some embodiments, the integrally-geared turbo-compressor 109 is driven by an electric motor 111.
In
A flow of compressed first refrigerant is delivered by the integrally-geared turbo-compressor 109 to a condenser 115. The flow of first refrigerant delivered through the condenser 115 is cooled, e.g. against water or air, and condensed.
In some embodiments, the condensed first refrigerant is circulated in the pre-cooling loop 103 to pre-cool the natural gas and to cool and optionally partially liquefy the second refrigerant circulating in the cooling loop 105.
In some embodiments, the process is divided into four pressure levels. The number of pressure levels can correspond to the number of stages of the integrally-geared turbo-compressor 109. In some embodiments, the flow of first refrigerant delivered through the condenser 115 is divided into a number of partial flows, which are then sequentially expanded at a number of progressively reducing pressure levels. Each partial refrigerant flow circulates in a sub-cycle and is returned as a side flow to the integrally-geared turbo-compressor at the inlet of a corresponding one of the plurality of compressor stages.
A delivery line 117 delivers a first part of the condensed first refrigerant flow to a plurality of serially arranged first expansion elements 119A-119D. A second delivery line 118 branched-off the delivery line 117 delivers a second part of the condensed first refrigerant flow to a plurality of serially arranged second expansion elements 121A-121D.
The first part of the condensed first refrigerant from condenser 115 is sequentially expanded in the four expansion elements 119A-119B at four different, gradually decreasing pressure levels. Downstream each expansion element 119A-119C a portion of the flow of partly expanded first refrigerant is diverted to a respective one of first, pre-cooling heat exchangers 123A-123C. The remaining part of the partly expanded first refrigerant is caused to flow through the next expansion element 119A-119C and so on. The residual first refrigerant flowing through the most downstream one (119D) of the first expansion elements 119A-119D is delivered to a most downstream pre-cooling heat exchanger 123D.
In each one of the first heat exchangers 123A-123D the first refrigerant exchanges heat against the natural gas flowing in pipe 107, thus pre-cooling and optionally partly liquefying the natural gas.
A part of the first refrigerant expanded in each second expansion elements 121A, 121B, 121C is diverted towards a corresponding one of a plurality of second heat exchangers 125A-125D. The part of refrigerant flow delivered by each one of the second expansion elements 121A-121C and which is not caused to flow through the respective heat exchanger 125A-125C is delivered through the subsequent expansion element. The most downstream one (125D) of the second heat exchangers receives the entire residual fraction of first refrigerant expanding in the most downstream (121D) of the second expansion elements 121A-121D. In each one of the second heat exchangers 125A-125D the first refrigerant exchanges heat against the second refrigerant, circulating in the cooling or liquefying loop 105, so that at the delivery side of the heat exchanger 125D the second refrigerant is cooled and at least partly liquefied.
Heated first refrigerant exiting the first, pre-cooling heat exchangers 123A-123D is collected with the heated first refrigerant exiting the second heat exchangers 125A-125D and is fed again to the integrally-geared turbo-compressor 109.
In some embodiments the heated first refrigerant exiting each second heat exchanger 125A-125D is at around the same pressure as the heated first refrigerant exiting the corresponding first heat exchanger 123A-123D. The refrigerant collected at corresponding pressure levels is delivered at the inlet of corresponding stages of the integrally-geared turbo-compressor 109. A plurality of refrigerant side streams are thus returned at gradually decreasing pressures at the inlet of the serially arranged stages of the integrally-geared turbo-compressor 109.
In
In some embodiments, the cooling or liquefying loop 105 comprises a compressor train. In some embodiments the compressor train can be comprised of a first compressor 131 and a second compressor 133 arranged in series. In other embodiments a single compressor can be provided. Each compressor can be a multi-stage compressor, for example a multi-stage centrifugal compressor.
In some embodiments the compressor(s) of the cooling loop 105 are driven by a prime mover, which can include an internal combustion engine. The prime mover can be a gas turbine 135, for instance an aeroderivative gas turbine.
An inter-stage cooler (inter-cooler) 137 can be arranged between the first compressor 131 and the second compressor 133, to reduce the temperature and the volume of the second refrigerant delivered by the first compressor 131 before entering the second compressor 133. The compressed second refrigerant delivered by the second compressor 133 is condensed in a condenser 139. The condenser 139 can be an air condenser or a water condenser, where the second refrigerant is condensed by exchanging heat against air or water. The condensed second refrigerant is subsequently delivered by a delivery line 141 through the sequentially arranged second heat exchangers 125A-125D, where the second refrigerant is cooled and possibly liquefied by exchanging heat against the first refrigerant circulating in the pre-cooling loop 103, as described above.
The cooled, and optionally partly liquefied second refrigerant delivered from the heat exchangers 125A-125D flows through a pipe 143 towards a main cryogenic heat exchanger 145, where the second refrigerant removes further heat from the pre-cooled and optionally partly liquefied natural gas, completing the liquefaction process. The entirely liquefied natural gas exits the system at 149, and the heated second refrigerant is returned through a line 151 to the compressor(s) or compressor train 131, 133.
In
More particularly, each compressor stage 109A-109D is provided with movable inlet guide vanes, schematically shown at 110A-110D for the four stages 109A-109D. In other embodiments, movable inlet guide vanes are provided at the inlet of only some or none of the compressor stages. As can be appreciated from
Each compressor stage 109A-109D comprises at least one impeller supported on a rotary shaft.
The impellers can be paired, each pair of impellers being supported by a common rotary shaft. In the embodiment of
Each rotary shaft 159, 161 comprise a pinion 159A, 161A keyed thereon. The pinions 159A, 161A mesh with a central toothed wheel or crown 163 which is driven in rotation by the electric motor 111 through a driving shaft 165. The two rotary shafts 159A, 161A and therefore the respective impellers mounted thereon can rotate at different rotary speeds.
The structure of the integrally-geared turbo-compressor 109 is particularly suitable for processing the different side streams of the first refrigerant circulating in the pre-cooling loop 103. The position of each set of movable inlet guide vanes 110A-110D at the inlet of the compressor stages can be adapted to the flow conditions of each side stream, i.e. each refrigerant stream delivered to the respective suction side of the compressor stages, so that the operative conditions of the compressor stages can be adapted to the temperature conditions and flow rates through the different heat exchangers 123A-123D, 125A-125D. The compressor efficiency and operability can thus be maximized. One or more intercoolers, such as intercoolers 153, 155, 157 easily integrated in the structure of the integrally-geared turbo-compressor 109 further increase the efficiency of the compressor and thus of the whole LNG system.
A further embodiment of the subject matter disclosed herein is illustrated in
The system of
Inlet guide vanes 228C, 228B, 228A can be provided at the inlet of some, and more particularly of each compressor stage. Intercoolers can be arranged between pairs of sequentially arranged compressor stages, for example a first intercooler 230 can be arranged between the delivery side of the first compressor stage 229C and the suction side of the second compressor stage 229B. A further intercooler 231 can be arranged between the delivery side of compressor stage 229B and the suction side of compressor stage 229A.
The delivery side of the last compressor stage 229A, i.e. the most downstream one in the pressure-increasing flow direction, is connected to a condenser 233. The first refrigerant circulating through the integrally-geared turbo-compressor 229 is condensed in the condenser 233 and delivered through a line 235 to the first heat exchanger 209. The compressed and condensed refrigerant flow can be expanded through one or more expansion elements, one of which is shown at 237. In a way similar to
Each compressor stage processes, therefore, a different refrigerant flow rate at variable and gradually increasing pressures from the most upstream compressor stage 229C through the most downstream compressor stage 229A.
The integrally-geared turbo-compressor 229 can be driven by a prime mover. In some embodiments the prime mover can be an electric motor, not shown, similarly to motor 111 described with reference to
The second loop 203 comprises compressor arrangement 241. The compressor arrangement 241 can comprise a single compressor or a plurality of sequentially arranged compressors. One or more of the compressors of the compressor arrangement 241 can be a multi-stage compressor, e.g. a multi-stage centrifugal compressor. The compressor arrangement 241 can be driven by a second prime mover 243. In some embodiments the second prime mover 243 can comprise a gas turbine, for instance an aeroderivative gas turbine. In other embodiments the prime mover can comprise an electric motor. Combinations of different engines or motors can be envisaged as well.
The second loop 203 comprises a condenser 245 through which the compressed second refrigerant delivered by the compressor arrangement 241 is condensed. A delivery line 247 delivers the compressed and condensed second refrigerant through the first heat exchanger 209 and through the second exchanger 211. In the first heat exchanger 209 the condensed second refrigerant is cooled by exchanging heat against the first refrigerant circulating in the first loop 201. In the second heat exchanger 211 the second refrigerant is expanded in one or more sequentially arranged expansion elements, one of which is shown at 249. In a manner known per se, the streams of second refrigerant at different and gradually reducing pressures can thus be generated, the side streams being returned through return lines 251, 253, 255 at decreasing pressures to the second compressor arrangement 241. In some embodiments, each side stream is injected at the inlet of a respective one of a plurality of serially arranged compressors forming the compressor arrangement 241. Movable inlet guide vanes can be provided at the inlet of each such compressors. In the second heat exchanger 211 the second refrigerant cools and/or partly liquefies the natural gas flowing through gas line 207.
The third loop 205 comprises a further compressor arrangement 261. The compressor arrangement 261 can be comprised of a single compressor or a plurality of sequentially arranged compressors. The compressor(s) of the compressor arrangement 261 can be centrifugal compressors, e.g. multi-stage centrifugal compressor. A further prime mover 263 is provided for driving the compressor arrangement 261 into rotation. In some embodiments, the prime mover 263 can comprise a gas turbine, for instance an aeroderivative gas turbine. In other embodiments the prime mover 263 can comprise an electric motor. Combinations of different motors and engines can be provided as well.
The compressed third refrigerant delivered by the compressor arrangement 261 is condensed in a condenser 265 and delivered in the liquid state through a delivery line 267 through the first, the second and the third heat exchangers 209, 211, 213. In the first and second heat exchangers 209, 211 the third refrigerant flows in the liquid state and is cooled by exchanging heat against the first refrigerant and the second refrigerant, respectively. In the last section of the loop, the third refrigerant is expanded in one or more sequentially arranged expansion elements 269. The vaporized third refrigerant exchanges heat against the natural gas in the third heat exchanger 213, until the natural gas is liquefied when delivered from the third heat exchanger 213. In some embodiments, the third refrigerant can be subdivided into side streams at gradually reducing pressures and each side stream is returned to the compressor arrangement 261 through respective return line 271, 273, 275. Also in this case, side streams can be injected at the inlet of sequentially arranged compressors forming part of the compressor arrangement, each compressor being possibly provided with movable inlet guide vanes.
The LNG process described so far and illustrated in
Processing the first refrigerant in the pre-cooling loop through the integrally-geared turbo-compressor has several advantages as already described in connection with the embodiment of
In some embodiments the integrally-geared turbo-compressor can be driven at a power ranging from about 12 MW to about 40 MW. In some embodiments, the integrally-geared turbo-compressor can have a rated power ranging between about 14 MW and 40 MW and more specifically between about 25 MW and 30MW.
In some embodiments a first refrigerant flow rate ranging from about 10,000 m3/h to about 70,000 m3/h can be processed by the integrally-geared turbo-compressor.
As disclosed above, the first refrigerant in the LNG system is usually expanded at gradually reducing pressure values and divided into side streams, each stream being returned to a respective one of several compressor stages of the integrally-geared turbo-compressor. In some embodiments, the delivery pressure of the most downstream compressor stage, i.e. the compressor stage at the highest pressure, ranges from about 45 bar absolute to about 65 bar absolute and in some embodiments the delivery pressure can range between about 52 bar absolute and about 56 bar absolute. In some embodiments, the respective suction pressure, i.e. the pressure at the inlet of the most upstream compressor stage, can range between about 2.5 and about 15 bar absolute, and more specifically e.g. between about 3 and about 10 bar absolute, for instance at around 3-3.5 bar absolute.
In other embodiments, the delivery pressure (discharge pressure) of the last stage in the integrally-geared turbo-compressor can range between about 10 bar absolute and 30 bar absolute, and in some specific embodiments between 15 and 25 bar absolute. The respective suction pressure at the most upstream compressor stage can range between about 1 and about 2.5 bar absolute, more specifically between about 1.5 and about 2 bar absolute, for instance at around 1.6-1.9 bar absolute.
The use of an integrally-geared turbo-compressor in the precooling cycle results in enhanced efficiency of the compressor and thus reduced power consumption, and finally in considerable cost savings when compared with a current art centrifugal multi-stage compressor.
To fully appreciate the important advantages in terms of increased efficiency and reduced energy consumption and the cost savings achieved thereby, the following comparative example shall be considered.
In a system according to
inlet pressure 1.13 bar absolute
inlet volumetric flow 56,000 m3/h
rotary speed 6,100 rpm
the compressor would absorb 21,108 kW at design condition. An arrangement according to
The total cost saving with the integrally geared configuration is 5%.
The use of an integrally geared compressor is even more attractive considering a configuration wherein an electric motor is used, instead of a gas turbine, due to the removal of the gearbox. In a standard solution according to the prior art using an electric motor as a driver, a fixed speed electric motor is drivingly connected to the compressor through a gearbox. Conversely, if an integrally geared compressor is used, the compressor can be designed at the optimum speed without the additional gearbox. The compressor will reach an efficiency up to 104.1%. Under the above mentioned operating conditions this would result in an absorbed power of 20,102 kW, which results in a reduction of power consumption of 1006 kW. In term of cost a solution with an integrally geared compressor and an electric motor is 14% less expensive than a standard solution with electric motor, gearbox and compressor, mainly thanks to the removal of the gearbox.
While the disclosed embodiments of the subject matter described herein have been shown in the drawings and fully described above with particularity and detail in connection with several exemplary embodiments, it will be apparent to those of ordinary skill in the art that many modifications, changes, and omissions are possible without materially departing from the novel teachings, the principles and concepts set forth herein, and advantages of the subject matter recited in the appended claims. Hence, the proper scope of the disclosed innovations should be determined only by the broadest interpretation of the appended claims so as to encompass all such modifications, changes, and omissions. In addition, the order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| FI2013A000076 | Apr 2013 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/056693 | 4/3/2014 | WO | 00 |
