ES3049238T3 - A system for generation of usable pressure steam using low temperature waste heat from internal combustion engines - Google Patents

Abstract

The invention relates to a system for generating usable pressure steam, in particular by compressing low-pressure steam generated by recovering low-temperature waste heat from an internal combustion engine. The high-pressure motive steam required to compress the low-pressure steam is generated by recovering high-temperature waste heat from the exhaust gases of the same engine. The amount of low-temperature waste heat from the internal combustion engine is significant compared to the total heat supplied to the engine and comparable to the high-temperature waste heat from the exhaust gases. With the proposed system, the utilization of low-temperature waste heat and the generation of usable pressure steam reduce overall fuel consumption compared to generating the same amount of steam with conventional fuel-consuming systems.

Description

[0001] DESCRIPTION

[0003] A system for generating usable pressure steam, using low-temperature waste heat from internal combustion engines

[0005] Technical field

[0007] The invention relates to a steam generation system at a usable pressure level, in particular by compressing low-pressure steam generated by recovering low-temperature waste heat rejected from an internal combustion engine, while the high-pressure motive steam required to compress the low-pressure steam is generated by recovering high-temperature waste heat from the exhaust of the same internal combustion engine. The amount of low-temperature waste heat rejected from the internal combustion engine is significant when compared to the total heat input to the internal combustion engine, and comparable to the high-temperature waste heat from the exhaust. With the proposed system, the utilization of low-temperature waste heat and the generation of steam at a usable pressure level reduce overall fuel consumption compared to generating the same amount of steam with conventional fuel-consuming systems.

[0009] State of the art

[0011] Internal combustion engines are widely used to generate electricity and heat, primarily in land-based applications and less frequently in marine applications. They use fuel and combustion air to generate power. These engines are used as prime movers to drive electric generators for electricity production. The intensive use of internal combustion engines is employed in industries where both the generated power and the engine's waste heat are utilized. The utilization of this heat, a byproduct, makes the localized use of internal combustion engines even more economical. Less than half of the fuel entering the internal combustion engine is converted into electricity, while the remainder is rejected as waste heat.

[0013] The primary heat dissipation of the internal combustion engine is achieved using the exhaust gas stream. After the internal combustion engine extracts thermal energy from the combustion gases, the expanded, high-temperature combustion gas stream is discharged as exhaust gas. This hot exhaust gas stream is primarily used in heat recovery steam generators to produce steam at the pressure and temperature levels required by the specific heat consumers of that facility.

[0015] Secondary heat rejection from the internal combustion engine comes primarily from the engine's lubricating oil, engine cylinders, and combustion air charge, which are converted into a coolant stream circulating within the engine's cooling circuits. This heat is largely unusable due to its low temperature, typically below 100 °C.

[0017] The third heat rejection from the internal combustion engine comes from surface losses to the environment and is generally not used for further use.

[0019] In installations where steam is consumed, the steam requirements of heat consumers may exceed the amount of steam available from the heat recovery steam generator downstream of the internal combustion engine exhaust stream. In such cases, to meet the increased steam demand, the steam generation of the heat recovery steam generator is increased by injecting supplemental fuel (and air as required) into the exhaust gas stream to induce additional combustion, or the additional steam requirement is supplied by an auxiliary boiler where both systems consume fuel. Sometimes both systems are used as required. The combustion of additional fuel results in higher fuel costs and a greater quantity of gaseous emissions.

[0021] The secondary heat rejection of the internal combustion engine is used for engine cooling, with the primary sources being the engine's lubricating oil, engine block, and combustion charge air. This heat is removed from the internal combustion engine by a coolant stream, typically an antifreeze and water solution, which generally operates below 100°C. The heated coolant stream downstream of the internal combustion engine dissipates heat primarily to the atmosphere in air-cooled radiators, and the cooled fluid is then recirculated back to the internal combustion engine. The amount of heat in the secondary heat rejection stream is significant and comparable to the usable amount of heat contained in the high-temperature exhaust gases in the primary heat rejection of the internal combustion engine. Due to the low temperature of the refrigerant fluid, which is mostly below 100 °C, both the pressure and temperature of the vapor generated from this source are not sufficient for most heat consumers for direct use, and therefore this secondary heat is wasted in most cases by dissipating into the atmosphere.

[0022] Document CN111441837B describes a waste heat recovery device and a method for recovering waste heat from an internal combustion engine, wherein the waste heat recovery device comprises: an internal combustion engine cylinder body, a flue gas heat exchanger, an expander, a pressurized air preheater, a high-temperature heat regenerator, a low-temperature heat regenerator, a cooling unit, a pressurization unit, and a working medium tank, wherein the internal combustion engine waste heat recovery device uses supercritical/subcritical CO₂ as the circulating working medium. The invention uses supercritical/subcritical CO₂ and fully recovers waste heat from various heat sources with different qualities in the internal combustion engine, such as flue gases, cylinder liner water, and pressurized air.

[0024] Document CN107542556A refers to generating energy from the waste heat of tail gases from the automotive sector, more particularly to a type of electricity generation system for recovering the latent heat of an IC engine with automatic tuning and to its method of assessing fitness for service.

[0026] Document CN110905619A describes a system for generating pressurized steam usable according to the preamble of claim 1.

[0028] Summary

[0030] An object of the invention, as defined by the features of claim 1, is to provide a system that overcomes the aforementioned disadvantages by reducing the total amount of fuel used to generate steam. This is achieved by recovering the low-temperature heat source from the secondary heat rejection circuit of the internal combustion engine, generating low-pressure steam from this source, and further compressing it to usable pressure levels as required by heat consumers. The proposed systems for compressing low-pressure steam are mechanical compression, using an expander compressor, and, alternatively, thermal compression, using a thermocompressor.

[0032] The internal combustion engine is an earlier technique used to generate power by consuming fuel and combustion air. The expanded combustion gases leave the internal combustion engine at a fairly high temperature but still contain large amounts of energy and oxygen. The exhaust from the internal combustion engine is connected to a waste heat boiler that generates steam at a higher pressure and temperature than required by heat consumers. The waste heat boiler is equipped with a duct burner that adds energy to the exhaust stream, making it possible to generate a greater quantity of steam at higher temperatures and pressures as needed.

[0034] In mechanical compression, a compressor-expander is used to compress low-pressure steam while expanding high-pressure steam. The input of mechanical energy to the compressor causes the steam to be compressed to low pressure; therefore, this system is specified as mechanical compression. The high-pressure steam generated by the waste heat boiler after the internal combustion engine is sent to the expander section of a compressor-expander package, and the expansion of the steam to the pressure level required by the heat consumers causes the extraction of thermal energy and the generation of work on the rotating output shaft of the expander. The expanded steam is supplied to the heat consumer. This generated work is transmitted by transmission to the rotating input shaft of the compressor. The low-pressure steam at the compressor inlet is generated in a low-pressure boiler that produces steam at a relatively low pressure and temperature. The source of this boiler is the coolant stream, into which the secondary heat dissipated by the internal combustion engine is transformed, while the coolant stream operates primarily below 100°C. This low-pressure steam is compressed in the compressor-expander section, consuming work, while the expander supplies the necessary work through the transmission. This compressed, low-pressure steam is also supplied to heat the consumer. The heat required to generate low-pressure steam is supplied from a waste heat source, and no fuel is consumed in its generation. As a result, the proposed system for generating high-pressure steam from the heat recovery steam generator and also low-pressure steam from the low-pressure boiler consumes less fuel overall when compared to generating the same amount of steam with conventional systems using a heat recovery steam generator or with the addition of an auxiliary boiler, where both require additional fuel combustion.

[0035] In thermal compression, a thermocompressor is used to compress low-pressure steam while expanding high-pressure steam. Within the thermocompressor, the conversion of the static pressure of the high-pressure steam to dynamic pressure, the heat transfer from the high-pressure steam to the low-pressure steam in direct contact and mixing, and the conversion of the dynamic pressure to static pressure of the mixture are thermal processes; therefore, this system is specified as thermal compression. The high-pressure steam generated by the waste heat boiler after the internal combustion engine is sent to the nozzle section of the thermocompressor, which increases the velocity of the incoming high-pressure steam while decreasing its static pressure, creating a low-pressure environment in the suction chamber section of the thermocompressor. Low-pressure steam is generated in a low-pressure boiler, which produces steam at a relatively low pressure and temperature. The source of this steam is the coolant stream, which contains the secondary heat dissipated by the internal combustion engine. This coolant stream operates primarily below 100°C. This low-pressure steam is connected to the suction chamber of the thermocompressor, and the lower pressure in this chamber draws the low-pressure steam into the thermocompressor. Both streams flow into the mixing chamber, transferring energy from the high-pressure steam generated by the waste heat boiler to the low-pressure steam generated by the low-pressure boiler through direct contact and mixing. An expansion chamber with an increased cross-section follows the mixing chamber, resulting in a decrease in velocity and an increase in the static pressure of the mixture. The mixture leaving the thermocompressor is at a pressure level between the two inlet streams: below the high-pressure steam and above the low-pressure steam. The thermocompressor's outlet stream is supplied to the heat consumer and/or process user. The heat required to generate low-pressure steam is supplied from a waste heat source, and no fuel is consumed in its generation. As a result, the proposed system for generating high-pressure steam from the heat recovery steam generator and low-pressure steam from the low-pressure boiler consumes less fuel overall compared to generating the same amount of steam with conventional systems using a heat recovery steam generator or with the addition of an auxiliary boiler, where both require additional fuel combustion.

[0036] Brief description of the drawings

[0037] Figure 1, a block diagram of the process arranged with an apparatus according to and implementing the present invention with a mechanical compression.

[0038] Figure 2, a schematic illustration, in greater detail, of the single-stage pressure casing compressor expander package given in Figure 1.

[0039] Figure 3, a schematic illustration, in greater detail, of the multi-stage pressure casing compressor expander package with multiple drive given in Figure 1.

[0040] Figure 4, a schematic illustration, in greater detail, of the common drive multi-stage pressure housing of the expander compressor package given in Figure 1.

[0041] Figure 5, a block diagram of the process arranged with an apparatus according to and implementing the present invention with thermal compression.

[0042] Figure 6, a schematic illustration, in greater detail, of a single-stage thermocompressor given in Figure 5.

[0043] Figure 7, a schematic illustration, in greater detail, of a multi-stage thermocompressor given in Figure 5.

[0044] Figure 8, a block diagram of a hybrid compressor package, a combination of mechanical compression and thermal compression.

[0045] List of references

[0046] 1 internal combustion engine

[0047] 2 electric generator

[0048] 3 combustion air

[0049] 4 fuel

[0050] 5 exhaust gas stream

[0051] 6 Engine coolant flow

[0052] 7 Hot engine coolant

[0053] 8 Cold engine coolant

[0054] 9 circulation pump

[0055] 15 low pressure boiler

[0056] 16 low pressure condensate

[0057] 17 Low pressure steam

[0058] 18 Low pressure compressor discharge current

[0059] 19 compressor discharge current

[0060] 20 heat consumer

[0061] 25 waste heat recovery boiler

[0062] 26 supplemental fuel

[0063] 27 waste heat recovery boiler exhaust gas stream

[0064] 28 high pressure steam

[0065] 29 High pressure expander exhaust current

[0066] 30 expander exhaust current

[0067] 32 high pressure condensate

[0068] 35 compressor expander package

[0069] 36 expander

[0070] 37 transmission

[0071] 38 compressor

[0072] 40 low pressure compressor

[0073] 41 high pressure compressor

[0074] 43 high pressure expander

[0075] 44 low pressure expander

[0076] 45 first transmission

[0077] 46 second transmission

[0078] 48 common transmission

[0079] 50 thermocompressor pack

[0080] 51 Thermocompressor exhaust current

[0081] 55 thermocompressor

[0082] 56 nozzle

[0083] 57 suction chamber

[0084] 58 mixing chamber

[0085] 59 expansion chamber

[0086] 64 multi-stage thermocompressor package

[0087] 65 1st stage of thermocompressor

[0088] 66 2nd stage of thermocompressor

[0089] 67 steam motive

[0090] 68 Output current of the 1st stage of the thermocompressor

[0091] Detailed description of the invention

[0092] With reference to Figure 1, an internal combustion engine (1) uses combustion air (3) and fuel (4) to create combustion. The increase in pressure and temperature from combustion is transformed into kinetic energy through the expansion of the hot combustion gases, causing movement and/or rotation of internal components that are used to drive an electric generator (2). After the expansion is complete, the hot combustion gases are expelled from the internal combustion engine (1) as the exhaust gas stream (5). The exhaust gas stream (5) contains high levels of energy due to its high temperature. To utilize the energy of the exhaust gas stream (5), a waste heat recovery boiler (25) is used to cool the exhaust gas stream (5) while generating high-pressure steam (28) by heating, evaporating, and superheating the high-pressure condensate (32) with heating surfaces of the economizer, evaporator, and superheater. The type of high-pressure condensate fluid (32) used to generate high-pressure steam (28) is determined by the heat consumer's (20) requirements. Supplemental fuel (26) is supplied to the waste heat recovery boiler (25) for additional combustion, resulting in increased steam generation. Air may also be supplied along with the supplemental fuel (26), if required. An exhaust gas stream (27) from the waste heat recovery boiler is used to extract steam from the waste heat recovery boiler (25).

[0093] The engine coolant stream (6) removes heat dissipated from various sources within the internal combustion engine (1) for cooling purposes. The cold engine coolant (8) is sent by the circulation pump (9) to the internal combustion engine (1) and forces the engine coolant stream (6) through the cooling circuits where heat rejection from the heating surfaces occurs. The hot engine coolant (7) flows to a low-pressure boiler (15). The low-pressure boiler (15) is an evaporator where the hot engine coolant (7) flows into one side of the heating surface while transferring its heat to the low-pressure condensate (16) on the other side, causing the condensate to evaporate and generating low-pressure steam (17). The type of low-pressure condensate fluid (16) used to generate the low-pressure steam (17) is according to the heat consumer's (20) requirement and may be the same or a different type of fluid as the high-pressure condensate (32).

[0095] Both high-pressure steam (28) and low-pressure steam (17) flow to the compressor-expander package (35) through separate streams. The compressor-expander package (35) comprises a compressor (38), an expander (36), and a drive (37). High-pressure steam (28) flows to the expander (36), while low-pressure steam (17) flows to the compressor (38) of the compressor-expander package (35).

[0096] The expander (36) is a machine that extracts thermal energy from high-pressure steam (28) by expanding it and uses it to perform mechanical work on a rotating output shaft connected to the transmission (37), while the expanded high-pressure steam (28) leaves the expander (36) from the expander's exhaust stream (30) at lower pressure and temperature and therefore lower thermal energy compared to the input.

[0098] The compressor (38) is a machine that increases the pressure and consequently the thermal energy of the low-pressure steam (17) by reducing its volume or increasing its speed or a mixture of both, while consuming the required mechanical work from a rotating input shaft connected to the transmission (37), while the compressed low-pressure steam (17) leaves the compressor (38) from the compressor discharge stream (19) with higher pressure and temperature and consequently higher thermal energy when compared to the input.

[0100] The transmission (37) mechanically or hydraulically connects the rotating output shaft of the expander (36) to the rotating input shaft of the compressor (38). The energy extracted from the expander (36) by the expansion of the high-pressure vapor (28) is transmitted through the transmission (37) to the compressor (38), where the compression of the low-pressure vapor (17) consumes the power generated by the expander (36). The compressor discharge stream (19) and the expander exhaust stream (30) are supplied to the heat consumer (20). The heat consumer (20) extracts internal energy from both the expander exhaust stream (30) and the compressor discharge stream (19), causing them to condense. The heat consumer (20) supplies the high-pressure condensate (32) to the waste heat recovery boiler (25) and the low-pressure condensate (16) to the low-pressure boiler (15).

[0102] For simplification, the single-stage pressure-cased compressor expander package (35) is illustrated in Figure 1, and further details of the single-stage pressure-cased compressor expander package (35) are given in Figure 2. The compressor expander package (35) may be of the multi-stage pressure-cased type, and details of such a configuration are given in Figure 3 and Figure 4.

[0104] With reference to Figure 2, a single-stage pressure-casing compressor/expander package (35) shown in Figure 1 is explained in more detail. The expander (36) may be of a single-stage or multi-stage axial type, a single-stage or multi-stage radial type, a multi-stage axial-radial mixture turbine type, or a single-stage or multi-stage positive displacement expander type. The expander (36) is packaged in a single pressure casing. The compressor (38) may be of a single-stage or multi-stage axial compressor type, a single-stage or multi-stage radial compressor type, a multi-stage axial-radial mixture turbine compressor type, or a single-stage or multi-stage positive displacement compressor type. The compressor (38) is packaged within a single pressure casing. The transmission (37) can be of a mechanical shaft type, a gearbox type, a hydraulic type, or a continuously variable type.

[0106] With reference to Figure 3, a multi-stage pressure housing of the multi-drive compressor expander package (35) referred to in Figure 1 is explained. For simplicity, only the two-stage pressure housing compressor expander is explained, whereas the number of pressure housings may increase for both the compressor and expander sections. The function of each high-pressure expander (43) and low-pressure expander (44) given in Figure 3 is the same as the function of the expander (36) given in Figure 1 and Figure 2. The function of each low-pressure compressor (40) and high-pressure compressor (41) given in Figure 3 is the same as the function of the compressor (36) in Figure 1 and Figure 2. The function of each of the first transmission (45) and the second transmission (46) given in Figure 3 is the same in principle as the transmission (37) given in Figure 1 and Figure 2.

[0108] The high-pressure steam (28) expands inside the high-pressure expander (43) to an intermediate pressure level and exits through the high-pressure expander's exhaust stream (29), flowing into the low-pressure expander (44) and expanding further inside, before exiting through the expander's exhaust stream (30) at a lower pressure. As the steam stream decreases in pressure, the temperature and thermal energy also decrease.

[0110] The total work by the expansion of the high-pressure steam (28) into the expander's exhaust stream (30) is generated by two expanders connected in series on the steam side, where each high-pressure expander (43) and low-pressure expander (44) extracts some portion of the total extracted thermal energy and generates a corresponding amount of work.

[0112] The low-pressure vapor (17) is compressed within the low-pressure compressor (40) to an intermediate pressure level and exits through the discharge stream of the low-pressure compressor (18), flowing into the high-pressure compressor (41) and being compressed further inside, and exiting through the compressor's discharge stream (19) at a higher pressure. As the vapor stream increases in pressure, the temperature and thermal energy also increase.

[0114] The total work consumed in compressing the low-pressure vapor (17) to the compressor discharge stream (19) is consumed by two compressors connected in series on the vapor side, where each of the low-pressure compressor (40) and the high-pressure compressor (41) transfers some portion of the energy to the vapor stream and consumes the corresponding amount of work.

[0116] The energy extracted from the high-pressure expander (43) by the expansion of the high-pressure vapor (28) to the high-pressure expander exhaust stream (29) is transmitted through the first transmission (45) to the high-pressure compressor (41) where the compression of the low-pressure compressor discharge stream (18) to the compressor discharge stream (19) consumes the energy generated by the high-pressure expander (43).

[0117] The energy extracted from the low-pressure expander (44) by expanding the high-pressure expander exhaust stream (29) to the expander exhaust stream (30) is transmitted through the second transmission (46) to the low-pressure compressor (40) where the compression of the low-pressure vapor (17) to the low-pressure compressor discharge stream (18) consumes the energy generated by the low-pressure expander (44).

[0119] The high-pressure expander (43) and/or the low-pressure expander (44) may be of the single-stage or multi-stage axial turbine type, the single-stage or multi-stage radial turbine type, the multi-stage axial-radial mixture turbine type, or the single-stage or multi-stage positive displacement expander type. Each of the high-pressure (43) and low-pressure (44) expanders is packaged in individual pressure housings. The high-pressure compressor (41) and/or the low-pressure compressor (40) may be of the single-stage or multi-stage axial compressor type, the single-stage or multi-stage radial compressor type, the multi-stage axial-radial mixture turbine type, or the single-stage or multi-stage positive displacement compressor type. Each of the high-pressure compressor (41) and the low-pressure compressor (40) is packaged in individual pressure housings. The first transmission (45) and/or the second transmission (46) can be of a mechanical shaft type, a gearbox type, a hydraulic type, or a continuously variable type.

[0121] For each compressor pressure housing, an expander pressure housing and an individual transmission interconnecting them are required in this type of configuration.

[0123] The requirement to move from a single-stage pressure-casing compressor expander shown in Figure 2 to a multi-stage pressure-casing compressor expander shown in Figure 3 may arise for several reasons. There may be cases where expansion in the expander or compression in the compressor may require the physical separation of the compressor or expander stages into separate pressure casings due to requirements or limitations such as rotational speed, pressure ratio, volumetric flow rate increase or decrease, construction capacity, etc. In such cases, the compressor and expander stages are physically separated into pressure casings. The expander pressure casings start from the high-pressure casing to the low-pressure casing, connected in series on the vapor side, and the compressor pressure casings start from the low-pressure casing to the high-pressure casing, connected in series on the vapor side. The number of pressure shells is calculated and optimized according to the technical requirements. For simplicity, only two pressure shells are implemented in Figure 3: a "high-pressure" shell and a "low-pressure" shell. As an example of a three-stage pressure shell configuration, the arrangement would comprise a high-pressure expander connected to a high-pressure compressor with a drive, an intermediate-pressure expander connected to an intermediate-pressure compressor with a drive, and a low-pressure expander connected to the low-pressure compressor with a drive. The compressor pressure shells are connected in series on the vapor side, and the expander pressure shells are connected in series on the vapor side, as explained for the configuration in Figure 3 above.

[0125] With reference to Figure 4, a common multi-stage drive pressure housing type of the compressor-expander package (35) given in Figure 1 is explained. The descriptions of the compressor and expander sections in Figure 3 are valid for Figure 4, whereas in Figure 4, the compressor input shafts and the expander output shafts are connected to a common drive (48).

[0127] The high-pressure expander's (43) rotating output shaft, the low-pressure expander's (44) rotating output shaft, the high-pressure compressor's (41) rotating input shaft, and the low-pressure compressor's (40) rotating input shaft are all connected to the common transmission (48). The common transmission (48) may be of a gearbox type, a hydraulic type, a continuously variable type, or a combination thereof for each connection.

[0129] The reason behind moving from a multi-stage, multi-drive pressure-casing compressor-expander package (35) in Figure 3 to a common-drive, multi-stage pressure-casing compressor-expander package (35) in Figure 4 is to match the total work generated by the expanders with the total work consumed by the compressors while allowing each compressor pressure-casing and expander pressure-casing to operate at spin speeds and tasks that do not need to match each other.

[0131] For simplicity, only two expander pressure housings and two compressor pressure housings are illustrated, where the number of both may increase due to reasons such as those explained in Figure 3. The number of compressor pressure housings and expander pressure housings need not necessarily match each other.

[0133] With reference to Figure 5, the type of low-pressure condensate fluid (16) used to generate low-pressure steam (17) is the same as the high-pressure condensate (32) used to generate high-pressure steam (28). Both the high-pressure steam (28) and the low-pressure steam (17) flow to the thermocompressor pack (50) through separate streams. The thermocompressor pack (50) comprises either a single-stage thermocompressor (55) or several thermocompressors (55) connected in series. For simplicity, the single-stage thermocompressor (55) is illustrated in Figure 5. The details and operation of the thermocompressor (55) are given in Figure 6, while the arrangement and further description of the multi-stage thermocompressor (55) are given in Figure 7.

[0135] The thermocompressor (55) is a device that uses high-pressure steam (28) to create a high-velocity, low-static-pressure stream. This stream draws in low-pressure steam (17), and further mixing of the two streams occurs in the downstream section of the device. Meanwhile, the outlet section of the thermocompressor (55) slows the mixing velocity, causing an increase in static pressure. The exhaust stream from the thermocompressor (51) leaves the thermocompressor (55) at a pressure level between that of the high-pressure steam (28) and the low-pressure steam (17). The exhaust stream from the thermocompressor (51) is supplied to the heat consumer (20). The heat consumer (20) extracts internal energy from the exhaust stream of the thermocompressor (51), causing condensation of the stream. The heat consumer (20) delivers the high-pressure condensate (32) to the waste heat recovery boiler (25) and the low-pressure condensate (16) to the low-pressure boiler (15), which are both the same fluid at different pressure levels.

[0137] With reference to Figure 6, the operation of the thermocompressor (55) is explained. High-pressure steam (28) flows into a nozzle (56). The high-pressure steam (28) supplied to the nozzle (56) is called motive steam (67). The nozzle (56) increases the velocity of the high-pressure steam (28), creating a jet flow, while simultaneously decreasing its static pressure to a point lower than that of the low-pressure steam (17). The velocity of the steam exiting the nozzle (56) can be subsonic or supersonic; the higher the velocity, the greater the compression ratio of the low-pressure steam (17). The compression ratio is given as the pressure of the thermocompressor's exhaust stream (51) divided by the pressure of the low-pressure steam (17). The outlet stream from the nozzle (56) flows into the mixing chamber (58) while creating a lower pressure environment in a suction chamber (57), causing the low-pressure steam (17) to flow into the suction chamber (57) and subsequently mix the streams in the mixing chamber (58). In an expansion chamber (59), the mixing velocity decreases due to the increased cross-sectional area, while the static pressure of the mixture increases. The exhaust stream from the thermocompressor (51) is at a pressure level between the high-pressure steam (28) and the low-pressure steam (17).

[0139] With reference to Figure 7, the multi-stage thermocompressor package (64) is explained. For simplicity, only two-stage thermocompressors (55) are implemented, while the number of thermocompressors (55) connected in series can be increased as required. The compression ratio of the thermocompressor (55) is limited; therefore, when a higher compression ratio is required, several thermocompressors (55) are connected in series to achieve higher compression ratios. The compression ratio is given as the pressure of the thermocompressor exhaust stream (51) divided by the pressure of the low-pressure steam (17). The motive steam (67), which can be supplied from either the high-pressure steam (28) or the thermocompressor exhaust stream (51), is supplied to the nozzle section of a first-stage thermocompressor (65). The first thermocompressor stage (65) compresses the low-pressure steam (17) to an intermediate pressure level below the thermocompressor exhaust stream (51) and above the low-pressure steam (17). The high-pressure steam (28) is supplied to a second thermocompressor stage (66) to compress the outlet stream (68) from the first thermocompressor stage and delivers the thermocompressor outlet stream (51) at a pressure point between the high-pressure steam (28) and the outlet stream (68) from the first thermocompressor stage.

[0141] With reference to Figure 8, a hybrid compression system comprising the expander compressor package (35) and the thermocompressor package (50) is illustrated. The expander compressor package (35) and the thermocompressor package (50) can be connected in series as required. In a hybrid configuration, the sequence, number of compression stages, and compressor types can be arranged as required. For simplicity, the thermocompressor package (50) is implemented followed by the expander compressor package (35). High-pressure vapor (28) flows to the thermocompressor (55), compresses the low-pressure vapor (17), and delivers the thermocompressor exhaust stream (51) to the compressor suction (38). The compressor (38) compresses the inlet stream and delivers the compressor discharge stream (19). The power required for the compressor (38) is supplied by the expander (36) through the transmission (37) and generated by the expander (36) by the expansion of the high-pressure steam (28). The compressor discharge steam (19) and the expander exhaust stream (30) are supplied to the heat consumer (20), and the pressure level of these streams may be the same or different.

Claims (21)

1. CLAIMS 1. A system for generating usable pressurized steam using low-temperature waste heat from internal combustion engines (1) that utilize combustion air (3) and fuel (4) to create combustion, wherein the hot combustion gases are expelled from the internal combustion engine (1) in an exhaust gas stream (5), wherein the system comprises: • a waste heat recovery boiler (25) used to cool the exhaust gas stream (5) while generating high-pressure steam (28) by heating, evaporating, and superheating the high-pressure condensate (32) with heating surfaces of the economizer, evaporator, and superheater, • a low-pressure boiler (15) that is an evaporator where the hot engine coolant (7) flows into one side of the heating surface while transferring its heat to the low-pressure condensate (16) that is inside the other side of the heating surface, causing the condensate to evaporate and generating low-pressure steam (17), the system being characterized in that it comprises: • one (35) compressor expander package, ° where both high-pressure steam (28) and low-pressure steam (17) flow, and ° which includes: - an expander (36) within which high-pressure steam (28) flows, and which extracts thermal energy from the high-pressure steam (28) by expansion and uses the thermal energy to perform mechanical work on a rotating output shaft connected to a transmission (37), while the expanded high-pressure steam (28) leaves the expander (36) from the expander's exhaust stream (30) at lower pressure and temperature and, consequently, lower thermal energy compared to the inlet, - a compressor (38) within which low-pressure steam (17) flows and which increases the pressure and, consequently, the thermal energy of the low-pressure steam (17) by reducing the volume or increasing the velocity or a mixture of both, while consuming the required mechanical work from a rotating input shaft connected to the transmission (37), while the compressed low-pressure steam (17) leaves the compressor (38) as a compressor discharge stream (19) with higher pressure and temperature and, consequently, higher thermal energy compared to the inlet, and - the transmission (37) mechanically or hydraulically connecting the rotating output shaft of the expander (36) to the rotating input shaft of the compressor (38), wherein the energy extracted from the expander (36) by the expansion of the vapor (28) at high pressure is transmitted through the transmission (37) to the compressor (38) where the compression of the vapor (17) at low pressure consumes the energy generated by the expander (36), • a heat consumer (20), ° to which the compressor discharge stream (19) and the expander exhaust stream (30) are supplied, ° which extracts internal energy from both the expander exhaust stream (30) and the compressor discharge stream (19) and causes condensation of the expander exhaust stream (30) and the compressor discharge stream (19), and ° that delivers the condensate (32) at high pressure to the waste heat recovery boiler (25) and the condensate (16) at low pressure to the low pressure boiler (15). 2. The system according to claim 1, characterized in that the compressor-expander package (35) is selected as a multi-stage pressure housing with multiple drives, wherein the multi-stage pressure housing of the compressor-expander package (35) comprises: • a high-pressure expander (43) and a low-pressure expander (44), ° where the high-pressure steam (28) expands inside the high-pressure expander (43) to an intermediate pressure level and exits through the exhaust stream (29) of the high-pressure expander, flowing into the low-pressure expander (44) and expanding further inside, and exits through the exhaust stream (30) of the expander at a lower pressure, • a low-pressure compressor (40) and a high-pressure compressor (41), ° where the low-pressure vapor (17) is compressed within the low-pressure compressor (40) to an intermediate pressure level and exits through the discharge stream of the low-pressure compressor (18), flowing into the high-pressure compressor (41) and being further compressed within it, and exiting through the discharge stream (19) of the compressor at a higher pressure, • a first transmission (45) and a second transmission (46), ° where the energy extracted from the high-pressure expander (43) by the expansion of the high-pressure vapor (28) to the high-pressure expander exhaust stream (29) is transmitted through the first transmission (45) to the high-pressure compressor (41) where the compression of the low-pressure compressor discharge stream (18) to the compressor discharge stream (19) consumes the energy generated by the high-pressure expander (43). 3. The system according to claim 2, characterized in that the rotating output shaft of the high-pressure expander (43), the rotating output shaft of the low-pressure expander (44), the rotating input shaft of the high-pressure compressor (41), and the rotating input shaft of the low-pressure compressor (40) are all connected to a common transmission (48). 4. The system according to claim 1, characterized in that the expander compressor package (35) is selected as a thermocompressor package (50), • into which both high-pressure steam (28) and low-pressure steam (17) flow, • which is a device that uses high-pressure steam (28) to create a high-speed, low-static-pressure stream that causes the suction of low-pressure steam (17) and further mixing of both streams occurs in the downstream section of the device while the outlet section of the thermocompressor (55) decreases the speed of the mixture causing an increase in static pressure, while the exhaust stream (51) from the thermocompressor leaves the thermocompressor (55) at a pressure level between the high-pressure steam (28) and the low-pressure steam (17). 5. The system according to claim 4, characterized in that the thermocompressor package (50) is a single-stage thermocompressor (55) or a multi-stage thermocompressor package (64) connected in series. 6. The system according to claim 4 or 5, characterized in that the thermocompressor package (50) further comprises: • a nozzle (56), through which the high-pressure steam (28) flows, causing an increase in the speed of the high-pressure steam (28) by creating a jet flow while decreasing the static pressure to a point lower than that of the low-pressure steam (17), ° where the outlet stream from the nozzle (56) flows into the mixing chamber (58) while creating a lower pressure environment in a suction chamber (57) that causes the low-pressure steam (17) to flow into the suction chamber (57) and the subsequent mixing of streams in a mixing chamber (58), • an expansion chamber (59), where the speed of the mixture decreases due to the increase in cross-section as the static pressure increases. 7. The system according to claim 6, characterized in that the high-pressure steam (28) supplied to the nozzle (56) is a motive steam (67). 8. The system according to claim 6 or 7, characterized in that the speed of the steam exiting the nozzle (56) can be subsonic or supersonic, the higher the speed the higher the compression ratio of the low-pressure steam (17) that can be achieved. 9. The system according to claim 5, characterized in that the multi-stage thermocompressor package (64) comprises: • a 1st stage (65) of thermocompressor, ° where the motive steam (67), which can be supplied from the high-pressure steam (28) or from the exhaust stream (51) of the thermocompressor, is supplied to the nozzle section of, ° that compresses the low-pressure vapor (17) to an intermediate pressure level below the exhaust stream of the thermocompressor (51) and above the low-pressure vapor (17), • a 2nd stage (66) of thermocompressor, ° where the steam (28) is supplied at high pressure, ° that compresses the outlet stream (68) from the 1st stage of the thermocompressor and delivers the outlet stream (51) from the thermocompressor at a pressure point between the high-pressure vapor (28) and an outlet stream (68) from the first stage of the thermocompressor. 10. The system according to claim 4, characterized in that the compressor expander package (35) is selected as a combination of the compressor expander package (35) and the thermocompressor package (50), wherein • The compressor-expander package (35) and the thermocompressor package (50) can be connected in series, • High-pressure steam (28) flows into the thermocompressor (55) and compresses the low-pressure steam (17), and delivers the thermocompressor exhaust stream (51) to the compressor (38) suction, • the compressor (38) compresses the inlet stream and delivers the compressor discharge stream (19), • the energy required for the compressor (38) is supplied by the expander (36) through the transmission (37) and generated by the expander (36) by the expansion of the high-pressure vapor (28), • The compressor discharge steam (19) and the expander exhaust stream (30) are supplied to the heat consumer (20). 11. The system according to claim 1, characterized in that the type of condensate fluid (32) at high pressure is used to generate steam (28) at high pressure. 12. The system according to claim 1, characterized in that supplementary fuel (26) is supplied to the waste heat recovery boiler (25) for supplementary combustion resulting in greater steam generation. 13. The system according to claim 1, characterized in that in mechanical compression, the type of low-pressure condensate fluid (16) used to generate the low-pressure steam (17) is according to the heat consumer's (20) requirement and may be of the same or a different type of fluid as the high-pressure condensate (32). 14. The system according to claim 1, characterized in that in thermal compression, the type of low-pressure condensate fluid (16) used to generate the low-pressure steam (17) is according to the heat consumer's (20) requirement and is the same type as the high-pressure condensate (32). 15. The system according to claim 1, characterized in that the expander (36) is selected as a single-stage or multi-stage axial turbine type, a single-stage or multi-stage radial turbine type, a multi-stage axial and radial mixing turbine type, or may be a single-stage or multi-stage positive displacement expander type. 16. The system according to claim 1, characterized in that the compressor (38) is selected as a single-stage or multi-stage axial type compressor, a single-stage or multi-stage radial type compressor, a multi-stage mixture of axial and radial type compressor, or may be a single-stage or multi-stage positive displacement type compressor. 17. The system according to claim 1, characterized in that the transmission (37) is selected as a mechanical shaft type, a gearbox type, a hydraulic type, or a continuously variable type. 18. The system according to claim 2, characterized in that the high-pressure expander (43) and/or the low-pressure expander (44) are selected as a single-stage or multi-stage axial turbine type, a single-stage or multi-stage radial turbine type, a multi-stage axial and radial mixing turbine type, or a single-stage or multi-stage positive displacement expander type. 19. The system according to claim 2, characterized in that the high-pressure compressor (41) and/or the low-pressure compressor (40) is selected as a single-stage or multi-stage axial compressor type, a single-stage or multi-stage radial compressor type, a multi-stage mixture of axial and radial compressor type, or may be a single-stage or multi-stage positive displacement compressor type. 20. The system according to claim 2, characterized in that the first transmission (45) and/or the second transmission (46) are selected as being of a mechanical shaft type, a gearbox type, a hydraulic type, or a continuously variable type. 21. The system according to claim 3, characterized in that the common transmission (48) is selected as a gearbox type, a hydraulic type, or a continuously variable type, or a mixture thereof, for each connection.