Steam generating device and steam generating method

Abstract

To stably supply high pressure steam even when a heat exchange amount from a heat source varies in a steam generating device for generating high pressure steam using, as a heat source, hot waste water or the like of which temperature is low and of which temperature and flow rate easily vary, without using a refrigerant.SOLUTION: A steam generating device includes a heat exchanger, a compressor, and a control unit. The heat exchanger includes a heat source medium flow passage, water supply piping for supplying water, and an electric heater. The heat source medium flow passage has a constitution for heating water, and the compressor has a constitution for compressing low pressure steam generated from water in the heat exchanger so as to obtain high pressure steam. The control unit adjusts output of the compressor and the electric heater, and the control unit determines whether heating by the electric heater is necessary or not.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a steam generating apparatus and a method for generating steam. [Background technology]

[0002] Reducing the use of fossil fuels is a social issue, and measures are being sought for production lines that use steam boilers. As a result, alternatives to combustors that use heavy oil, etc., have been developed as heat sources for steam boilers.

[0003] Patent Document 1 discloses a heat pump type steam generating device that generates steam by recovering exhaust heat from factory wastewater, etc., and has a heat pump section that recovers heat from hot water in an exhaust heat recovery device (evaporator) to heat a refrigerant, compresses the refrigerant using a compressor, and heats water to be heated in a refrigerant condenser to generate steam.

[0004] Patent Document 2 discloses a process steam control device that can convert the pressure value of process steam not only from low pressure to high pressure, but also from high pressure to low pressure, and that uses a screw rotor to reduce the pressure of medium-pressure steam and increase the pressure of low-pressure steam. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-161248 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-19812 Summary of the Invention [Problem to be solved by the invention]

[0006] In the heat pump steam generator described in Patent Document 1, steam is generated via a heat pump that uses a refrigerant. Therefore, two heat exchangers are required to transfer heat. In addition, a refrigerant is required for the heat pump. Although the refrigerant is not specified, a fluorocarbon-based refrigerant is usually used as the refrigerant.

[0007] In the process steam control device described in Patent Document 2, steadily supplied low-pressure steam is converted into high-pressure steam.

[0008] The object of the present disclosure is to provide a steam generating device that generates high-pressure steam without using a refrigerant and uses a heat source such as warm wastewater, which has a low temperature and is susceptible to fluctuations in temperature and flow rate, and that can stably supply high-pressure steam even if the amount of heat exchange from the heat source fluctuates. [Means for solving the problem]

[0009] The steam generating device of the present disclosure includes a heat exchanger, a compressor, and a control unit, the heat exchanger having a heat source medium flow path, a water supply pipe for supplying water, and an electric heater, the heat source medium flow path being configured to heat water, the compressor being configured to compress low-pressure steam generated from water in the heat exchanger to form high-pressure steam, and the control unit adjusting the output of the compressor and the electric heater, and determining whether heating by the electric heater is necessary. [Effects of the Invention]

[0010] According to the present disclosure, in a steam generating device that generates high-pressure steam without using a refrigerant and uses warm wastewater or the like, which has a low temperature and is prone to fluctuations in temperature and flow rate, as a heat source, it is possible to stably supply high-pressure steam even if the amount of heat exchange from the heat source fluctuates. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing a steam generating device according to an embodiment. [Figure 2] 2 is a flow chart showing a control method for the steam generating device of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0013] FIG. 1 is a schematic diagram showing the configuration of a steam generating device according to an embodiment.

[0014] In this figure, the steam generating device 100 includes a heat exchanger 10, a compressor 20, and a control unit 30.

[0015] The heat exchanger 10 incorporates a heat source medium flow path 12 and an electric heater 14. A water supply pipe 18 having a pressure reducing valve 16 is connected to the heat exchanger 10. The heat source medium flow path 12 and the electric heater 14 are arranged so as to come into contact with water (liquid) supplied to the heat exchanger 10. The water supplied to the heat exchanger 10 via the water supply pipe 18 is heated by at least one of the heat source medium flow path 12 and the electric heater 14. In this case, the water may be supplied in a shower-like dispersion from above the heat exchanger 10. The heat source supplied to the heat source medium flow path 12 is warm wastewater of less than 100°C, which has little use in factories and the like.

[0016] In addition, in order to prevent the formation of scale on the heat exchange surface of the water supplied to the heat exchanger 10, it is desirable to install a water quality control device such as an ion-exchange water production device upstream of the water supply pipe 18 to remove impurities.

[0017] The compressor 20 is configured to suck in low-pressure steam generated in the heat exchanger 10 and discharge high-pressure steam. The compressor 20 is also configured to increase or decrease its rotation speed in response to a control signal from the control unit 30. The output (heat generation amount) of the electric heater 14 is also configured to be adjusted by the control unit 30. The control unit 30 may be realized by hardware such as an IC or CPU built into the steam generator 100, or may be realized by a program stored in a computer installed externally or in a remote location.

[0018] The pressure inside the heat exchanger 10 is reduced by suction from the compressor 20. Therefore, the water inside the heat exchanger 10 boils at temperatures below 100°C. The pressure reducing valve 16 on the water supply pipe 18 is provided to maintain the reduced pressure inside the heat exchanger 10. Therefore, when boiling occurs at, for example, approximately 60°C, the low-pressure steam has a pressure equivalent to the saturated vapor pressure corresponding to that water temperature. Furthermore, although the high-pressure steam can be adjusted to a desired pressure by the compressor 20, it is usually set to a pressure equivalent to the saturated vapor pressure corresponding to a water temperature of approximately 100°C to 200°C.

[0019] The electric heater 14 is disposed below the heat source medium flow path 12. The height difference between the horizontal center line of the heat source medium flow path 12 and the horizontal center line of the electric heater 14 is represented by d in the drawing. Here, the horizontal center line refers to a horizontal center line that is equidistant from the top and bottom of the object.

[0020] By arranging the electric heater 14 below the heat source medium flow path 12 with respect to the horizontal center line, it is highly likely that the electric heater 14 will be covered with water even if the amount of water supplied decreases, so it is possible to prevent dry heating. Furthermore, when the electric heater 14 is energized (turned on), it is desirable that the amount of water supplied inside the heat exchanger 10 be sufficient to at least cover the entire electric heater 14.

[0021] FIG. 2 is a flow chart showing a control method for the steam generating apparatus of FIG.

[0022] 2, water supplied to the heat exchanger 10 is heated by heat exchange with the heat source medium flow path 12 through which the heat source medium flows (step S110). Then, steam (low-pressure steam) generated by heating is compressed by the compressor 20 (step S120). It is determined whether heating by the electric heater 14 is necessary (step S130). If it is determined that heating is necessary, the electric heater is turned on (step S140). Then, the pressure of the high-pressure steam is adjusted (step S150).

[0023] On the other hand, if it is determined in step S130 that heating by the electric heater 14 is not necessary, the process proceeds to step S150 without turning on the electric heater.

[0024] With the above-described configuration, high-pressure steam can be stably supplied even when the heat from the heat source medium is insufficient.

[0025] The present disclosure is not limited to the above-described embodiment, but includes various modifications. Furthermore, the present disclosure is not necessarily limited to an embodiment having all of the above-described configurations.

[0026] Preferred embodiments of the present disclosure will be described below.

[0027] In the steam generating device, the control unit adjusts at least one of the outputs of the compressor and the electric heater based on at least one of the heat source history, which is the history of changes in the amount of heat supplied to the heat source medium flow path, the low-pressure steam pressure history, which is the history of the pressure of the low-pressure steam, and the high-pressure steam pressure history, which is the history of the pressure of the high-pressure steam.

[0028] In this way, by using historical information such as the past external environment and steam pressure as feedforward information for control, high-pressure steam can be supplied stably.

[0029] The control unit adjusts the output of the electric heater based on the output history of the electric heater.

[0030] By using such past operation history information as feedforward information for control to control the electric heater, high-pressure steam can be supplied stably.

[0031] The control unit adjusts at least one of the outputs of the compressor and the electric heater based on at least one of predicted information on the amount of heat supplied to the heat source medium flow path and predicted information on demand for high-pressure steam.

[0032] In this way, for example, by using forecast information on future heat demand and supply obtained from an external production management system as feedforward information for control, the compressor and electric heater can be controlled to ensure a stable supply of high-pressure steam.

[0033] The control unit adjusts the output of the compressor so that the pressure of the high-pressure steam is maintained at a value higher than the target pressure.

[0034] As a result, for example, when a shortage of high-pressure steam supply is predicted based on historical information and future prediction information, the pressure drop of the high-pressure steam can be minimized and high-pressure steam can be supplied stably.

[0035] The electric heater is disposed below the heat source medium flow path with respect to the horizontal center line.

[0036] The control unit adjusts at least one of the outputs of the compressor and the electric heater based on at least one of the temperature and flow rate of the heat source medium in the heat source medium flow path, the temperature and volume of water stagnating in the heat exchanger, the temperature of water flowing through the water supply pipe, the temperature and pressure of low-pressure steam, and the temperature and pressure of high-pressure steam.

[0037] The heat source medium in the heat source medium flow path is heated wastewater.

[0038] The steam generation method is a method of generating steam using a steam generating device comprising a heat exchanger, a compressor, and a control unit, wherein the heat exchanger has a heat source medium flow path, a water supply pipe for supplying water, and an electric heater, wherein the heat source medium flow path heats the water, the compressor compresses low-pressure steam generated from the water in the heat exchanger to produce high-pressure steam, the control unit adjusts the output of the compressor and the electric heater, and the control unit determines whether heating by the electric heater is necessary.

[0039] The effects of the technology of the present disclosure will be summarized below.

[0040] Even if the heat quantity of the exhaust heat (heated wastewater, etc.) fluctuates, the amount of low-pressure steam generated can be maintained, allowing for a stable supply of high-pressure steam.

[0041] Since the water supplied to the heat exchanger is directly heated, heat loss can be reduced compared to when a heat source medium is heated.

[0042] Because the water supplied to the heat exchanger is heated directly, it is highly responsive to load fluctuations and enables stable control.

[0043] There is no need for a heat pump that uses a refrigerant, and only one heat exchanger is required as a component. [Explanation of symbols]

[0044] 10: heat exchanger, 12: heat source medium flow path, 14: electric heater, 16: pressure reducing valve, 18: water supply pipe, 20: compressor, 30: control unit, 100: steam generator.

Claims

1. The system includes a heat exchanger, a compressor, and a control unit. the heat exchanger includes a heat source medium flow path, a water supply pipe for supplying water, and an electric heater; the heat source medium flow path has a configuration for heating the water, the heat source medium in the heat source medium flow path is hot wastewater; The compressor has a configuration in which low-pressure steam generated from the water in the heat exchanger is compressed to generate high-pressure steam, the control unit adjusts the outputs of the compressor and the electric heater, The control unit determines whether heating by the electric heater is necessary.

2. The control unit a heat source history, which is a history of changes in the amount of heat supplied to the heat source medium flow path; A low-pressure steam pressure history, which is a history of the pressure of the low-pressure steam; and a high-pressure steam pressure history, which is a history of the pressure of the high-pressure steam. The steam generating apparatus according to claim 1 , wherein at least one of the outputs of the compressor and the electric heater is adjusted.

3. The steam generating device according to claim 1 , wherein the control unit adjusts the output of the electric heater based on a history of the output of the electric heater.

4. The control unit includes: prediction information of the amount of heat supplied to the heat source medium flow path; and the forecast information of the demand for high-pressure steam, The steam generating apparatus according to claim 1 , wherein at least one of the outputs of the compressor and the electric heater is adjusted.

5. The steam generating apparatus according to claim 1 , wherein the control unit adjusts the output of the compressor so that the pressure of the high-pressure steam is maintained at a value higher than a target pressure.

6. The steam generating apparatus according to claim 1 , wherein the electric heater is disposed below the heat source medium flow path with respect to a horizontal center line.

7. The control unit the temperature and flow rate of the heat source medium in the heat source medium flow path; The temperature and volume of the water remaining in the heat exchanger; the temperature of the water flowing through the water supply pipe; the temperature and pressure of the low-pressure steam; and the temperature and pressure of the high-pressure steam, The steam generating apparatus according to claim 1 , wherein at least one of the outputs of the compressor and the electric heater is adjusted.

8. The system includes a heat exchanger, a compressor, and a control unit. the heat exchanger includes a heat source medium flow path, a water supply pipe for supplying water, and an electric heater; A method for generating steam using a steam generator, wherein the heat source medium in the heat source medium flow path is hot wastewater, the heat source medium flow path heats the water; The compressor compresses low-pressure steam generated from the water in the heat exchanger to generate high-pressure steam, the control unit adjusts the outputs of the compressor and the electric heater, The steam generating method, wherein the control unit determines whether heating by the electric heater is necessary.

Images