Steam generating device and steam generating method

Abstract

To provide a steam generating device and a steam generating method that can generate high-pressure steam from exhaust heat of low-pressure fluid with high efficiency.SOLUTION: A steam generating device comprises: a compressor for sucking and compressing steam; a condensate pipe for merging water separated from steam discharged from the compressor, with steam to be sucked by the compressor; and a pressure reducer provided in the condensate pipe, and for reducing the pressure of water flowing through the condensate pipe. Preferably, the steam generating device comprises an upstream compressor for compressing steam to be sucked by the compressor, and has a structure in which low-pressure steam is compressed by the two compressors.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a steam generation device and a steam generation method.

Background Art

[0002] Patent Document 1 discloses a technique of heating feed water by a heat exchanger using warm water as a heat source to generate low-pressure steam, and obtaining high-pressure steam by compressing the low-pressure steam with a compressor. In the technique of this document, a part of the high-pressure steam separated by a gas-liquid separator and high-temperature water are merged into the warm water that is the heat source of the heat exchanger to improve energy efficiency.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In factories and the like, low-temperature fluids such as steam and warm water after being used for process heating and the like are generally discharged without being utilized. Even if they are to be utilized, low-temperature fluids particularly below 100°C are limited to uses such as hot water supply and heating, and in fact, it is difficult to recover heat economically as the temperature becomes lower. If a high-temperature fluid exceeding 100°C can be obtained using a low-temperature fluid below 100°C as a heat source, an energy-saving measure by reusing waste heat that has not been utilized so far can be proposed.

[0005] In the technique of Patent Document 1 above, heat recovery is attempted by using a part of the high-pressure steam separated by a gas-liquid separator and high-temperature water as the heat source of the heat exchanger, but since a heat exchanger is used for heat recovery, the energy efficiency is restricted by the heat resistance of the heat exchanger.

[0006] The object of the present invention is to provide a steam generation apparatus and a steam generation method that can generate high-pressure steam with high efficiency from the waste heat of a low-pressure fluid. [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides a steam generating apparatus comprising a compressor that inhales and compresses steam, a condensate pipe that combines water separated from the steam discharged from the compressor with the steam inhaled into the compressor, and a pressure reducer provided in the condensate pipe that reduces the pressure of the water flowing through the condensate pipe. [Effects of the Invention]

[0008] According to the present invention, high-pressure steam can be generated with high efficiency from the waste heat of a low-pressure fluid. [Brief explanation of the drawing]

[0009] [Figure 1] Schematic diagram of an example of a steam generator according to one embodiment of the present invention. [Figure 2] Schematic diagram of another example of a steam generator according to one embodiment of the present invention [Figure 3] A flowchart illustrating an example of the control procedure for the pressure reducing valve by the computer installed in the steam generator shown in Figure 1. [Figure 4] A flowchart illustrating an example of the control procedure for the control valves of the steam generator shown in Figure 1. [Modes for carrying out the invention]

[0010] Embodiments of the steam generation apparatus and steam generation method according to the present invention will be described below with reference to the drawings.

[0011] (composition) Figures 1 and 2 are schematic diagrams of a steam generator according to one embodiment of the present invention.

[0012] In the steam generator and steam generation method of this embodiment, low-temperature water is heated using waste heat from low-temperature fluids such as steam or hot water that have been used for process heating in factories, etc. as a heat source, and the low-pressure steam generated is compressed to produce high-pressure steam which is then supplied to the user.

[0013] The steam generator shown in Figure 1 includes a low-pressure steam generator 40A, gas-liquid separators 4 and 5, a low-temperature water circulation pump 10, a low-temperature water supply pump 11, compressors 1 and 2, pressure reducing valves 7 and 8, control valves 12 and 13, a medium-temperature water heat recovery heat exchanger 9, a computer 50, and the like. In this embodiment, the low-pressure steam generator 40A is configured to include a waste heat recovery heat exchanger 6 and a gas-liquid separator 3. The steam generator illustrated in Figure 2 is configured in which the low-pressure steam generator 40A of the steam generator shown in Figure 1 is replaced with a low-pressure steam generator 40B, and is otherwise similar in configuration to the steam generator shown in Figure 1.

[0014] The following explains each element in turn.

[0015] -Low-pressure steam generators 40A, 40B- Low-pressure steam generators 40A (Figure 1) and 40B (Figure 2) each heat water flowing in from the gas-liquid separator 4 via the water supply pipe 20 to generate steam that is compressed by the compressor 1. A pressure reducing valve 7 is provided in the water supply pipe 20.

[0016] The low-pressure steam generator 40A illustrated in Figure 1 includes a heat recovery heat exchanger 6 and a gas-liquid separator 3, as described above.

[0017] Low-temperature water is supplied to the waste heat recovery heat exchanger 6 from the gas-liquid separator 3 via piping 23 and a low-temperature water circulation pump 10. The waste heat recovery heat exchanger 6 illustrated in Figure 1 is a plate heat exchanger that uses waste heat (for example, around 80°C) from low-temperature fluids such as steam or hot water used for process heating in factories, etc., as a heat source to heat the low-temperature water circulating between it and the gas-liquid separator 3. In the waste heat recovery heat exchanger 6, a portion of the heated low-temperature water vaporizes into low-pressure steam below atmospheric pressure. The low-pressure steam, along with the low-temperature water, is guided to the gas-liquid separator 3 through piping 24.

[0018] The gas-liquid separator 3 separates low-temperature water from the low-pressure steam introduced from the exhaust heat recovery heat exchanger 6. During the operation of the steam generation device, the inside of the gas-liquid separator 3 is evacuated. Therefore, the gas-liquid separator 3 is manufactured to have a strength that can withstand the state where its inside is evacuated. In the gas-liquid separator 3, by separating gas and liquid under vacuum, low-temperature water can be evaporated below atmospheric pressure. The low-pressure steam from which the low-temperature water has been separated in the gas-liquid separator 3 is led to the compressor 1 through the pipe 14. A part of the low-temperature water separated from the low-pressure steam in the gas-liquid separator 3 is sent back to the exhaust heat recovery heat exchanger 6 again by the low-temperature water circulation pump 10. Also, a part of the low-temperature water inside the gas-liquid separator 3 is sent to the compressors 1 and 2 by the low-temperature water supply pump 11.

[0019] In addition, in FIG. 1, the case where the low-pressure steam generation device 40A is configured including the exhaust heat recovery heat exchanger 6 which is a plate heat exchanger is illustrated, but the low-pressure steam generation device is not limited to the configuration illustrated in FIG. 1. The configuration illustrated in FIG. 2 is an example where the low-pressure steam generation device 40B is configured with a falling liquid film type shell and tube type exhaust heat recovery heat exchanger, and as an example, the low-pressure steam generation device 40A can also be replaced with the low-pressure steam generation device 40B.

[0020] The low-pressure steam generation device 40B (a shell and tube type exhaust heat recovery heat exchanger) includes a tube bundle 42 composed of a plurality of heat transfer tubes and a low-temperature water spraying device 41. In the low-pressure steam generation device 40B, the low-temperature water inside its body (container) is pumped up by the low-temperature water circulation pump 10 and led to the low-temperature water spraying device 41 through the pipe 23, and is sprayed by the low-temperature water spraying device 41 inside the body and flows down the surface of the heat transfer tubes of the tube bundle 42. During the operation of the steam generation device, it is also possible to adopt a configuration where the inside of the body of the low-pressure steam generation device 40B is in a vacuum state.

[0021] In the heat transfer tubes of the tube bundle 42, a low-temperature fluid that has been used for process heating or the like in a factory or the like flows through. The low-temperature water that flows down the surface of the heat transfer tubes is heated by the waste heat of the low-temperature fluid, and a part of the low-temperature water evaporates to generate low-pressure steam. The low-pressure steam generated by the low-pressure steam generator 40B is led to the compressor 1 through the pipe 14 as in the example of FIG. 1. The low-temperature water accumulated in the body of the low-pressure steam generator 40B is partly supplied to the low-temperature water spraying device 41 as described above, and partly sent to the compressors 1 and 2 by the low-temperature water supply pump 11 as in the example of FIG. 1.

[0022] Also, a water supply pipe 25 is connected to the gas-liquid separator 3 and the body of the low-pressure steam generator 40B. Low-temperature water (for example, tap water) is supplied to the gas-liquid separator 3 and the low-pressure steam generator 40B through this water supply pipe 25. In the examples of FIGS. 1 and 2, the water supply pipe 25 passes through the medium-temperature water heat recovery heat exchanger 9 that uses the medium-temperature water from the gas-liquid separator 4 flowing through the water supply pipe 20 as a heat source. The supply water flowing through the water supply pipe 25 recovers the heat of the medium-temperature water in the medium-temperature water heat recovery heat exchanger 9. However, the medium-temperature water heat recovery heat exchanger 9 can be omitted when not necessary.

[0023] Also, the gas-liquid separator 3 and the low-pressure steam generator 40B are provided with a water level sensor 30 for measuring the water level of the low-temperature water stored in the body of the gas-liquid separator 3 and the low-pressure steam generator 40B. There is no limitation on the method of the water level sensor 30. The measured value by this water level sensor 30 is transmitted to the computer 50.

[0024] -Compressor 1- The compressor 1 shown in FIG. 1 is a screw compressor including a male rotor and a female rotor. The compressor 1 sucks and compresses the low-pressure steam (for example, about 50 kPa) generated by the low-pressure steam generator 40A (in FIG. 2, the low-pressure steam generator 40B) and raises the pressure (for example, about 200 kPa). In the examples of FIGS. 1 and 2, since a multi-stage (two stages in this embodiment) of compressors 1 and 2 are adopted, the compressor 1 corresponds to the front-stage compressor that compresses the steam inhaled by the compressor 2 as the rear-stage compressor.

[0025] Furthermore, the compressor 1 is supplied with cold water, which is separated from the low-pressure steam by the gas-liquid separator 3 (a cold steam generator 40B in the example of Figure 2) and discharged from the cold water supply pump 11, via the injection pipe 21. The injection pipe 21 is equipped with a control valve (flow control valve) 12 that controls the amount of cold water supplied to the compressor 1.

[0026] The low-temperature water introduced via the water injection pipe 21 is injected into the casing of the compressor 1, sealing the gap between the male and female rotors of the compressor 1, and cooling the steam during the compression process so that the intermediate-pressure steam obtained by compressing the low-pressure steam in the compressor 1 becomes saturated steam. Meanwhile, the low-temperature water heated by cooling the steam during the compression process becomes medium-temperature water (e.g., around 120°C), which is hotter than the low-temperature water (e.g., around 80°C), and is discharged from the compressor 1. Some of it evaporates during the heating process to become intermediate-pressure steam. This intermediate-pressure steam is discharged from the compressor 1 together with the intermediate-pressure steam obtained by compressing the low-pressure steam from the low-pressure steam generator 40A (or 40B), and is led to the gas-liquid separator 4 via the pipe 15.

[0027] -Gas liquid separator 4- The gas-liquid separator 4 separates medium-temperature water from the medium-pressure steam discharged from the compressor 1 and drawn into the compressor 2. The medium-pressure steam, from which the medium-temperature water has been separated in the gas-liquid separator 4, is led to the compressor 2 through the piping 16. The medium-temperature water separated from the medium-pressure steam in the gas-liquid separator 4 is led to the gas-liquid separator 3 via the water supply pipe 20, and through the medium-temperature water heat recovery heat exchanger 9 and the pressure reducing valve 7. By passing through the water supply pipe 20, the medium-temperature water is supplied to the gas-liquid separator 3 at a temperature and pressure reduced to a level similar to that of cold water.

[0028] Furthermore, the gas-liquid separator 4 is equipped with a water level sensor 31 that measures the water level of the medium-temperature water stored in the body of the gas-liquid separator 4. The gas-liquid separator 4 is also equipped with a pressure sensor 35 that measures the pressure inside the body of the gas-liquid separator 4. In addition, the piping 16 connecting the gas-liquid separator 4 and the compressor 2 is equipped with a temperature sensor 33 that measures the outlet steam temperature of the gas-liquid separator 4. The measurements from the water level sensor 31, pressure sensor 35, and temperature sensor 33 are transmitted to the computer 50. The types of water level sensor 31, temperature sensor 33, and pressure sensor 35 are not particularly limited.

[0029] -Compressor 2- Compressor 2 is a screw-type compressor, similar to compressor 1, and consists of a male rotor and a female rotor. Compressor 2 draws in medium-pressure steam (for example, about 200 kPa) introduced from gas-liquid separator 4 via piping 16, compresses it, and increases its pressure (for example, to about 600 kPa).

[0030] Furthermore, the compressor 2 is supplied with cold water, which is medium-temperature water separated from the medium-pressure steam in the gas-liquid separator 4, via the gas-liquid separator 3, the cold water supply pump 11, and the injection pipe 22. The injection pipe 22 is equipped with a control valve (flow control valve) 13 that controls the amount of cold water supplied to the compressor 2.

[0031] The low-temperature water introduced via the water injection pipe 22 is injected into the casing of the compressor 2, sealing the gap between the male and female rotors of the compressor 2, and cooling the steam during the compression process so that the high-pressure steam obtained by compressing the medium-pressure steam in the compressor 2 becomes saturated steam. Meanwhile, the medium-temperature water, which is heated by cooling the steam during the compression process, becomes high-temperature water (for example, 150-160°C) with a higher temperature than the medium-temperature water and is discharged from the compressor 2, and a portion of it evaporates during the heating process to become high-pressure steam. This high-pressure steam is discharged from the compressor 2 together with the high-pressure steam obtained by further compressing the medium-pressure steam from the compressor 1, and is led to the gas-liquid separator 5 via the pipe 17.

[0032] -Gas liquid separator 5- The gas-liquid separator 5 separates high-temperature water from the high-pressure steam discharged from the compressor 2. The high-pressure steam from which the high-temperature water has been separated in the gas-liquid separator 5 is supplied to the user through the piping 18. The high-temperature water separated from the high-pressure steam in the gas-liquid separator 5 is supplied to the condensate piping 19, guided to the gas-liquid separator 4 via a pressure reducing valve 8 installed in the condensate piping 19, and joins with the steam drawn into the compressor 2. The high-temperature water flowing through the condensate piping 19 is depressurized via the pressure reducing valve 8, and a portion of it flashes and evaporates, becoming a temperature level similar to that of the medium-temperature water (i.e., medium-temperature water) and joining with the medium-temperature water inside the gas-liquid separator 4. Meanwhile, the steam generated by the flash evaporation of the high-temperature water joins with the medium-pressure steam inside the gas-liquid separator 4 and is supplied to the compressor 2.

[0033] Furthermore, the gas-liquid separator 5 is equipped with a water level sensor 32 that measures the water level of the high-temperature water stored in the body of the gas-liquid separator 5. The gas-liquid separator 5 is also equipped with a pressure sensor 36 that measures the pressure inside the body of the gas-liquid separator 5. In addition, the piping 18 that supplies high-temperature steam from the gas-liquid separator 5 to the user is equipped with a temperature sensor 34 that measures the outlet steam temperature of the gas-liquid separator 5. The measured values ​​from the water level sensor 32, pressure sensor 36, and temperature sensor 34 are transmitted to the computer 50. The types of water level sensor 32, temperature sensor 34, and pressure sensor 36 are not particularly limited.

[0034] -Computer 50- Computer 50 is a control device that controls the pressure reducing valves 7 and 8, control valves 12 and 13, etc. Computer 50 has a function to control the control valve 13 according to the measured values ​​output from the pressure sensor 36 and the temperature sensor 34, and adjust the amount of water injected into the compressor 2 to make the compressed steam from the compressor 2 saturated steam. Similarly, computer 50 also has a function to control the control valve 12 according to the measured values ​​output from the pressure sensor 35 and the temperature sensor 33, and adjust the amount of water injected into the compressor 1 to make the compressed steam from the compressor 1 saturated steam.

[0035] Furthermore, the computer 50 has a function to control the pressure reducing valve 8 according to the measurement value output from the water level sensor 32, thereby maintaining the water level inside the body of the gas-liquid separator 5. Similarly, the computer 50 also has a function to control the pressure reducing valve 7 according to the measurement value output from the water level sensor 31, thereby controlling the water level inside the body of the gas-liquid separator 4. The computer 50 also has a function to control a control valve (not shown) installed in the water supply pipe 25 according to the measurement value output from the water level sensor 30, thereby controlling the water level inside the body of the gas-liquid separator 3.

[0036] The following explanation will describe the water injection volume control for compressors 1 and 2, and the water level control for gas-liquid separators 3, 4, and 5, using Figures 3 and 4, respectively.

[0037] (Water flow rate control) Figure 3 is a flowchart showing an example of the control procedure for the control valve 13 by the computer 50.

[0038] The control procedure for the control valve 12 by the computer 50 is the same as the control procedure for the control valve 13. In the following explanation of the control procedure for the control valve 13, the compressor 2, control valve 13, pressure sensor 36, temperature sensor 34, and high temperature will be replaced with the compressor 1, control valve 12, pressure sensor 35, temperature sensor 33, and medium temperature, respectively, and this will serve as a substitute for the explanation of the control procedure for the control valve 12.

[0039] The control shown in Figure 3 is repeatedly performed by the computer 50 at a predetermined cycle time (e.g., a 1-second cycle) during the operation of the steam generator shown in Figure 1 or Figure 2.

[0040] Step S11 The computer 50 first receives the current measured values ​​P and T of the pressure and temperature of the high-temperature steam output from the pressure sensor 36 and the temperature sensor 34 (step S11).

[0041] Step S12 Next, the computer 50 calculates the saturation temperature T1 of the high-temperature steam discharged from the compressor 2 based on the measured value P (i.e., the actual pressure of the high-temperature steam) output from the pressure sensor 36 (step S12).

[0042] Steps S13-S15 The computer 50 compares the measured value T (i.e., the actual temperature of the high-temperature steam) output from the temperature sensor 34 with the saturation temperature T1 (step S13), and controls the control valve 13 so that the measured value T becomes equal to the saturation temperature T1 (steps S14, S15). Specifically, if the measured value T is higher than the saturation temperature T1, the computer 50 increases the opening of the control valve 13 and increases the flow rate of low-temperature water supplied to the compressor 1, thereby lowering the measured value T (step S14). Conversely, if the measured value T is lower than the saturation temperature T1, the computer 50 decreases the opening of the control valve 13 and reduces the flow rate of low-temperature water supplied to the compressor 1, thereby raising the measured value T (step S15). After performing the processes in steps S14 and S15, the computer 50 returns to step S11.

[0043] (Water level control) Figure 4 is a flowchart illustrating an example of the control procedure for the pressure reducing valve 8 by the computer 50. The computer 50 controls the pressure reducing valve 8 according to the procedure illustrated in Figure 4 so that the measured value L (i.e., the actual water level in the gas-liquid separator 5) output from the water level sensor 32 falls within the set range L1-L2. L1 is the lower limit of the set range, and L2 (>L1) is the upper limit of the set range, both of which are pre-set and stored in the memory of the computer 50.

[0044] The control procedure for the pressure reducing valve 7 by the computer 50 is the same as the control procedure for the pressure reducing valve 8. In the following explanation of the control procedure for the pressure reducing valve 8, replace "pressure reducing valve 8," "gas-liquid separator 5," "water level sensor 32," and "high temperature" with "pressure reducing valve 7," "gas-liquid separator 4," "water level sensor 31," and "medium temperature," respectively, to substitute for the explanation of the control procedure for the pressure reducing valve 7. Also, the control procedure for the control valve (not shown) installed in the water supply piping 25 is the same as the control procedure for the pressure reducing valve 8. In the following explanation of the control procedure for the pressure reducing valve 8, replace "pressure reducing valve 8," "gas-liquid separator 5," "water level sensor 32," and "high temperature" with "control valve (not shown)," "gas-liquid separator 3 (or low-pressure steam generator 40B)," "water level sensor 30," and "low temperature," respectively, to substitute for the explanation of the control procedure for the control valve (not shown).

[0045] The control shown in Figure 4 is performed in parallel with the control shown in Figure 3, and, like the control shown in Figure 3, is repeatedly executed by the computer 50 at a predetermined cycle time (e.g., a 1-second cycle) while the steam generator shown in Figure 1 or Figure 2 is in operation.

[0046] Step S21 The computer 50 first receives the current measured value L of the water level inside the gas-liquid separator 5, which is output from the water level sensor 32 (step S21).

[0047] Steps S22, S23 Next, the computer 50 compares the measured value L output from the water level sensor 32 with the lower limit L1 of the set range (step S22). If the measured value L is lower than the lower limit L1, the computer 50 increases the measured value L by reducing the opening of the pressure reducing valve 8 and decreasing the outflow rate of high-temperature water from the gas-liquid separator 5 (step S23). After performing the process in step S23, the computer 50 returns to the procedure from step S23 to step S21. If the measured value L is greater than or equal to the lower limit L1, the computer 50 moves the procedure from step S22 to step S24.

[0048] Steps S24, S25 When the procedure moves to step S24, the computer 50 compares the measured value L output from the water level sensor 32 with the upper limit L2 of the set range. If the measured value L is higher than the upper limit L2, the computer 50 decreases the measured value L by increasing the opening of the pressure reducing valve 8 and increasing the outflow rate of high-temperature water from the gas-liquid separator 5 (step S25). After performing the process in step S25, the computer 50 returns to step S21 from step S25. If the measured value L is less than or equal to the upper limit L2, the computer 50 maintains the opening of the pressure reducing valve 8 and returns to step S21 from step S24.

[0049] Note that in the flowchart of Figure 4, the steps S22 and S23 and the steps S24 and S25 may be reversed.

[0050] (effect) (1) As described above, the medium-pressure steam drawn into the compressor 2 has high-temperature water separated from the high-pressure steam discharged from the compressor 2 flowing into it via the pressure reducing valve 8. Comparing the inlet and outlet sides of the compressor 2 during operation of the steam generator, for example, gas-liquid separators 4 and 5, the internal pressure of gas-liquid separator 5 is higher than that of gas-liquid separator 4. In other words, the temperature level of the high-temperature water inside gas-liquid separator 5 is higher than that of the medium-temperature water inside gas-liquid separator 4. In this case, as the high-temperature water inside gas-liquid separator 5 flows into gas-liquid separator 4 via the pressure reducing valve 8, some of the high-temperature water flashes and evaporates, and the high-temperature water that has passed through the pressure reducing valve 8 cools down to become medium-temperature water and joins the medium-temperature water inside gas-liquid separator 4. On the other hand, the steam generated by the flash evaporation of the high-temperature water joins the medium-pressure steam inside gas-liquid separator 4 and is supplied to the compressor 2.

[0051] At this time, when the high-temperature water undergoes flash evaporation, the proportion of the high-temperature water that is joined by the flash steam inside the gas-liquid separator 4 (flash steam ratio) is calculated using the following equation (Equation 1). F=(h3-h2) / r2×100…(Formula 1) F: Flash vapor rate (weight %) h3: Specific enthalpy of high-temperature water (kJ / kg) h2: Specific enthalpy of medium-temperature water (kJ / kg) r2: Latent heat of vaporization of flash vapor (kJ / kg)

[0052] For example, if the high-temperature water is 150°C, the medium-temperature water is 120°C, and the absolute pressure inside the gas-liquid separator 4 is 200kPa, then h3 = 628kJ / kg, h2 = 502kJ / kg, and r2 = 2204kJ / kg, and the flash vapor rate F is 5.7% by weight. In other words, in this case, 5.7% by weight of the flow rate of high-temperature water flowing from the gas-liquid separator 5 into the gas-liquid separator 4 is recovered as medium-pressure steam.

[0053] Thus, according to this embodiment, by depressurizing the high-temperature water separated from the steam pressurized by the compressor 2 and returning it to the suction side of the compressor 2, the steam generated when the high-temperature water is depressurized can be directly combined with the steam drawn into the compressor 2. In other words, the heat energy other than that of the high-pressure steam supplied to the user—in the specific examples shown in Figures 1 and 2, the heat energy of the medium-temperature and high-temperature water—can be recovered within the thermal cycle of the steam generator, allowing for efficient generation of high-pressure steam relative to the heat energy of the heat source. Consequently, high-pressure steam can be generated with high efficiency even from the waste heat of low-pressure fluids below 100°C, such as steam or hot water used for process heating in factories, etc.

[0054] Furthermore, evaporation of hot water due to reduced pressure can also occur through the pressure reducing valve 7, similar to the evaporation of steam. In other words, when the medium-temperature water separated from the medium-pressure steam discharged by the compressor 1 is reduced in pressure by the pressure reducing valve 7, steam is generated, and this generated steam merges with the low-pressure steam drawn into the compressor 1. This also yields the same effect as described above.

[0055] Furthermore, in this embodiment, a configuration is used in which multiple compressors 1 and 2 are used to generate high-pressure steam from low-pressure steam. However, it is also conceivable to use a single high-compression-ratio compressor to generate high-pressure steam from low-pressure steam. For example, if compressor 1 has a compression ratio that can increase the pressure of low-pressure steam to the pressure level of high-pressure steam, it is possible to omit compressor 2, gas-liquid separator 5, and their associated equipment and piping, and supply high-pressure steam, from which high-temperature water has been separated by gas-liquid separator 4, to the user. In this case as well, when the high-temperature water flowing from gas-liquid separator 4 to gas-liquid separator 3 via the water supply pipe 20 is depressurized by the pressure reducing valve 7, flash evaporation occurs, and the flash steam can be combined with the low-pressure steam drawn into compressor 1.

[0056] (2) Since a gas-liquid separator 4 is provided on the suction side of compressor 2, medium-temperature water can be rationally separated from the medium-pressure steam supplied to compressor 2. At the same time, since a gas-liquid separator 5 is provided on the discharge side of compressor 2, high-temperature water for heat recovery can be rationally generated as medium-pressure steam. The same applies to the gas-liquid separators 3 and 4 before and after compressor 1.

[0057] However, it is possible to separate water from steam without using gas-liquid separators 4 and 5, and if it is not necessary to use gas-liquid separators 4 and 5, a configuration can be adopted in which at least one of the gas-liquid separators 4 and 5 is omitted or replaced with another element. The same applies to the gas-liquid separators 3 and 4 before and after the compressor 1.

[0058] (3) By providing injection pipes 21 and 22 that supply water separated from the steam by the gas-liquid separators 4 and 5 to the compressors 1 and 2 as sealing water to seal the gap between the male and female rotors, the compression efficiency of the compressors 1 and 2 can be improved by utilizing the low-temperature water obtained in the system. In addition, as the steam is cooled by the low-temperature water while being compressed in the compressors 1 and 2, the superheating of the compressed steam can be suppressed. This makes it possible to discharge saturated steam from the compressors 1 and 2. Furthermore, by adding low-temperature water to the steam during the compression process in the compressors 1 and 2, it is possible to discharge steam containing a large amount of water from the compressors 1 and 2. Therefore, high-temperature water that is vaporized by the pressure reducing valves 7 and 8 and used for heat recovery can be obtained in a rational manner.

[0059] (4) The amount of cold water supplied to compressors 1 and 2 is controlled so that the temperature of the discharge steam from compressors 1 and 2, as measured by temperature sensors 33 and 34, reaches the saturation temperature calculated based on the measurements of pressure sensors 35 and 36. This allows the amount of cold water supplied to compressors 1 and 2 to be flexibly adjusted in response to fluctuations in operating conditions, even if the operating conditions of the steam generator change, and the effect of saturating the discharge steam from compressors 1 and 2 can be obtained more rationally.

[0060] (5) The water levels of the gas-liquid separators 4 and 5 are controlled to be within the set range according to the measurements of the water level sensors 31 and 32. As a result, the water levels of the gas-liquid separators 4 and 5 are maintained, and steam leakage in the gas-liquid separators 4 and 5 can be prevented.

[0061] (6) The compressor is equipped with a compressor 1 that compresses the steam drawn into the compressor 2, and by increasing the pressure of the low-pressure steam with two-stage compressors 1 and 2, the low-pressure steam can be compressed to high-pressure steam at a high compression ratio without difficulty.

[0062] Furthermore, if the supply flow rate of high-pressure steam to the user is kept constant, the amount of low-pressure steam compression required of compressor 1 decreases by the combined flow rate of steam generated by the flash evaporation of high-temperature water. Since the shaft power W of compressor 1 is calculated by the following (Equation 2), the shaft power W can be reduced in proportion to the decrease in the amount of low-pressure steam D. W=(hv2-hv1)×D (formula 2) W: Shaft power (kW) hv2: Specific enthalpy (kJ / kg) of the discharged steam from compressor 1 hv1: Specific enthalpy (kJ / kg) of the intake steam of compressor 1 D: Low-pressure steam volume (kg / s)

[0063] (7) In the example shown in Figure 1, the low-pressure steam generator 40A heats the low-temperature water supplied from the gas-liquid separator 4 via the water supply pipe 20 and the pressure reducing valve 7 to generate low-pressure steam that is compressed by the compressor 1, and is equipped with a gas-liquid separator 3 that separates the low-pressure steam into gas and liquid under vacuum. Since the inside of the gas-liquid separator 3 is maintained in a vacuum state when the steam generator is in operation, a sufficient amount of low-pressure steam can be obtained by evaporating the low-temperature water at or below atmospheric pressure.

[0064] (modified version) In the examples shown in Figures 1 and 2, the pressure reducing valves 7 and 8 are controlled to control the water level of the gas-liquid separators 4 and 5. However, the amount of wastewater discharged from the gas-liquid separators 4 and 5 can be controlled by other types of control valves, such as flow control valves, instead of pressure reducing valves 7 and 8. Therefore, it is also possible to install other types of control valves, such as flow control valves, in the water supply pipe 20 and condensate pipe 19 instead of or in addition to the pressure reducing valves 7 and 8, and to control these control valves with a computer 50.

[0065] Furthermore, while Figures 1 and 2 illustrate an example in which pressure reducing valves 7 and 8 are used as pressure reducing devices to reduce pressure in the water supply pipe 20 and condensate pipe 19, the pressure reducing devices are not limited to pressure reducing valves 7 and 8, as long as the desired pressure reduction effect can be obtained. For example, other configurations that can achieve a pressure reduction effect, such as flow control valves or reverse flow channels, can be used instead of pressure reducing valves 7 and 8. [Explanation of Symbols]

[0066] 1... Compressor (compressor, pre-compressor), 2... Compressor, 3... Gas-liquid separator (first gas-liquid separator), 4... Gas-liquid separator (first gas-liquid separator, second gas-liquid separator), 5... Gas-liquid separator (second gas-liquid separator), 6... Heat exchanger for waste heat recovery, 7... Pressure reducing valve (control valve), 8... Pressure reducing valve, 12,13... Control valve, 19... Condensate piping, 20... Water supply pipe (condensate piping), 21,22... Injection piping, 30,31,32... Water level sensor, 33,34... Temperature sensor, 35,36... Pressure sensor, 40A,40B... Low-pressure steam generator, 50... Computer, L... Measured value (water level), L1... Lower water level limit (set range), L2... Upper water level limit (set range), P... Measured value (pressure), T... Measured value (temperature), T1... Saturation temperature

Claims

1. a compressor that sucks in and compresses steam; a condensate pipe for allowing water separated from the steam discharged from the compressor to merge with the steam drawn into the compressor; a pressure reducer provided in the condensate pipe to reduce the pressure of water flowing through the condensate pipe; a first gas-liquid separator for separating water from steam drawn into the compressor; a second gas-liquid separator that separates water from the steam discharged from the compressor and supplies the water to the condensate pipe; a water injection pipe that supplies water separated from the steam in the first gas-liquid separator to the compressor; a pressure sensor that measures the pressure of the second gas-liquid separator; a temperature sensor that measures an outlet vapor temperature of the second vapor-liquid separator; a first control valve provided in the water injection pipe; a computer that controls the first control valve in response to measurement values ​​output from the pressure sensor and the temperature sensor, The computer calculating a saturation temperature of the steam discharged from the compressor based on the measurement value output from the pressure sensor; comparing the measurement value output from the temperature sensor with the saturation temperature; The first control valve is controlled so that the measurement value output from the temperature sensor becomes the saturation temperature. Steam generator.

2. 2. The steam generating device of claim 1, a water level sensor that measures the water level of the second gas-liquid separator; a second control valve provided in the condensate pipe; The computer controls the second control valve so that the measurement value output from the water level sensor falls within a set range.

3. 2. The steam generating device of claim 1, a water level sensor that measures the water level of the first gas-liquid separator; a water pipe for sending water from the first gas-liquid separator; a third control valve provided in the water supply pipe; The computer controls the third control valve so that the measurement value output from the water level sensor falls within a set range.

4. 2. The steam generating device of claim 1, A steam generating device including a pre-stage compressor that compresses steam drawn into the compressor.

5. 2. The steam generating device of claim 1, a steam generating device including a front-stage compressor that compresses steam drawn into the compressor and supplies the steam to the first gas-liquid separator;

6. The steam generating device of claim 5, A steam generating device including a third gas-liquid separator for separating gas and liquid under vacuum.

7. 7. The steam generating device of claim 6, a water pipe for sending water from the first gas-liquid separator; a low-pressure steam generator including the third gas-liquid separator and configured to generate steam to be compressed by a front-stage compressor; a water supply pipe connected to the third gas-liquid separator; a heat exchanger that heats water supplied to the third gas-liquid separator through the water supply pipe by using heat recovered from the water flowing through the water supply pipe; A steam generating device comprising:

8. reducing the pressure of water separated from the steam discharged from the compressor to cause flash evaporation; The vapor produced by the flash evaporation is combined with the vapor drawn into the compressor, supplying water separated from steam drawn into the compressor to the compressor; calculating a saturation temperature of the steam discharged from the compressor based on the pressure of the steam discharged from the compressor; comparing the temperature of the steam discharged from the compressor with the saturation temperature; The amount of water separated from the steam drawn into the compressor and supplied to the compressor is controlled so that the temperature of the steam discharged from the compressor becomes the saturation temperature. Steam generation method.

Images