Heat pump type steam generator

Abstract

The present invention provides a heat pump type steam generator that can suppress the decrease in output steam volume even when blowdown water is drained. [Solution] A heat pump type steam generator 1 comprises a heat pump unit 2, a steam separator 13 that separates the two-phase gas-liquid flow generated by heat transfer to the water to be heated in the condenser 23 into steam and hot water, a water level sensor L, a water circulation channel L10, a steam channel L4 that sends the steam separated in the steam separator 13 as output steam to an external steam utilization facility, a supply water channel L1, a water supply pump 10 that supplies supply water to the supply water channel L1 so that the water level of the hot water detected by the water level sensor L reaches a predetermined value, and a blowdown water channel L5 that extracts a portion of the hot water separated in the steam separator 13 and discharges the extracted hot water as blowdown water. A heat recovery unit 11 is provided to perform heat exchange between the blowdown water and the supply water and recover the heat from the blowdown water into the supply water.

Description

Technical Field

[0001] The present invention relates to a heat pump type steam generation device capable of suppressing a decrease in the output steam amount even when discharging blowdown water.

Background Art

[0002] In a boiler for steam generation, when steam is discharged from the boiler, impurities mixed in the feed water remain in the circulating water in the boiler. As these impurities are continuously added and steam with less impurities is discharged, the impurity concentration in the circulating water increases. To prevent the impurities in the circulating water from precipitating as scale when the impurity concentration in the circulating water exceeds the saturation state, the circulating water is blowdown to ensure that the impurity concentration in the circulating water does not exceed the saturation state.

[0003] For example, in Patent Document 1, in a heat pump type steam generation device, in order to suppress scale generation due to concentration of impurities in the feed water, the drainage amount of blowdown water is adjusted according to the pressure in the steam separator and the measured value of the scale concentration in the liquid flowing out from the lower part of the steam separator.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the blowdown water is at a high temperature, and there is a problem that the heat loss due to the drainage of this blowdown water reduces the output steam amount of the heat pump type steam generation device.

[0006] The present invention has been made in view of the above, and an object thereof is to provide a heat pump type steam generation device capable of suppressing a decrease in the output steam amount even when discharging blowdown water. [Means for solving the problem]

[0007] To solve the above-mentioned problems and achieve the objective, the heat pump type steam generator according to the present invention comprises a heat pump section in which a compressor for compressing a refrigerant, a condenser for transferring the heat of the refrigerant discharged from the compressor to a water to be heated and condensing the refrigerant, an expansion mechanism for reducing the pressure of the refrigerant condensed in the condenser, and an evaporator for recovering heat from a heat source hot water and evaporating the refrigerant are connected in a ring shape; a steam separator for separating the gas-liquid two-phase flow generated by heat transfer to the water to be heated in the condenser into steam and hot water; a water level sensor for detecting the water level of the hot water in the steam separator; and a water circulation channel for supplying the gas-liquid two-phase flow from the condenser to the steam separator and returning the hot water separated in the steam separator back to the condenser. The heat pump type steam generator comprises: a steam channel for sending the steam separated by the steam separator as output steam to an external steam utilization facility; a supply water channel connected to the water circulation channel between the steam separator and the condenser for supplying the water to be heated; a water supply pump for supplying the supply water to the supply water channel so that the water level of the hot water detected by the water level sensor reaches a predetermined value; and a blowdown water channel for extracting a portion of the hot water separated by the steam separator and discharging the extracted hot water as blowdown water, wherein a heat recovery unit is provided to perform heat exchange between the blowdown water and the supply water and recover the heat of the blowdown water into the supply water.

[0008] Furthermore, the heat pump type steam generator according to the present invention is characterized in that, in the above invention, it is provided with a flow control valve that is installed in the blowdown flow path upstream of the heat recovery unit and whose opening degree can be adjusted, and the opening degree of the flow control valve is set in advance in accordance with the chloride ion concentration of the supply water.

[0009] Furthermore, the heat pump type steam generator according to the present invention comprises, in the above invention, a chloride ion concentration sensor for detecting the chloride ion concentration of the hot water separated by the steam separator, and a flow control valve provided in the blowdown water flow path upstream of the heat recovery unit and whose opening degree can be adjusted, wherein the flow control valve increases its opening degree in accordance with the concentration difference from a predetermined chloride ion concentration when the chloride ion concentration detected by the chloride ion concentration sensor increases, and decreases its opening degree in accordance with the concentration difference from a predetermined chloride ion concentration when the chloride ion concentration decreases.

[0010] Furthermore, the heat pump type steam generator according to the present invention further comprises a scale concentration sensor for detecting the scale concentration of the hot water separated by the steam separator, and the flow control valve is characterized by performing a first opening adjustment, which increases the opening degree according to the concentration difference with a predetermined chloride ion concentration when the chloride ion concentration detected by the chloride ion concentration sensor increases, and decreases the opening degree according to the concentration difference with a predetermined chloride ion concentration when the chloride ion concentration decreases, and a second opening adjustment, which increases the opening degree according to the concentration difference with a predetermined scale concentration when the scale concentration detected by the scale concentration sensor increases, and decreases the opening degree according to the concentration difference with a predetermined scale concentration when the scale concentration decreases, and adjusting to the larger of the opening degree obtained by the first opening adjustment and the opening degree obtained by the second adjustment.

[0011] Furthermore, the heat pump type steam generating apparatus according to the present invention is characterized in that the condenser and the heat recovery unit are copper brazed plate type heat exchangers. [Effects of the Invention]

[0012] According to the present invention, even when blowdown water is drained, the decrease in output steam volume can be suppressed. [Brief explanation of the drawing]

[0013] [Figure 1]Figure 1 shows the overall configuration of a heat pump type steam generator according to an embodiment of the present invention. [Figure 2] Figure 2 shows the overall configuration of a heat pump type steam generator according to a modified example 1 of the present invention. [Figure 3] Figure 3 shows the overall configuration of a heat pump type steam generator according to a modified example 2 of the present invention. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments for carrying out this invention will be described with reference to the attached drawings.

[0015] (Overall structure) Figure 1 shows the overall configuration of a heat pump type steam generator 1 according to an embodiment of the present invention. The heat pump type steam generator 1 is a device that recovers waste heat from waste hot water (heat source hot water) such as factory wastewater and generates steam using the recovered waste heat. The generated steam is sent to external steam utilization equipment such as a drying device or a sterilization device.

[0016] As shown in Figure 1, the heat pump type steam generator 1 has a heat pump unit 2 and a steam generation unit 3. The steam generation unit 3 heats the water to be heated using the heat source generated by the heat pump unit 2 and generates steam.

[0017] The heat pump unit 2 is a device having a heat pump cycle in which a compressor 22 for compressing a refrigerant, a condenser 23 for condensing the refrigerant compressed by the compressor 22, a subcooler 24 for further cooling the liquid refrigerant condensed in the condenser 23, an expansion mechanism 25 for reducing the pressure of the refrigerant from the subcooler 24, and an evaporator 21 that recovers heat from waste hot water, evaporates the refrigerant from the expansion mechanism 25, and flows it out to the compressor 22 are connected in a ring. The subcooler 24 may be provided as needed.

[0018] The refrigerant compressed by the compressor 22 to become high temperature and high pressure exchanges heat with the water circulating in the steam generation section 3 of the condenser 23 and the water (heated water) supplied from the water supply pump 10, is cooled and condensed. The refrigerant sent out from the condenser 23 is further cooled by preheating the water flowing through the supply water flow path L1 in the subcooler 24. The refrigerant subcooled in the subcooler 24 is adiabatically expanded by the expansion mechanism 25, absorbs heat from the exhaust warm water in the evaporator 21, evaporates, and is sent to the compressor 22.

[0019] The steam generation section 3 includes a condenser 23 that generates steam by evaporating water using the refrigerant circulating in the heat pump section 2 as a heat source, a steam separator 13 that separates the gas-liquid two-phase flow containing water and steam generated by the condenser 23 into steam and water, a steam flow path L4 that supplies the steam separated by the steam separator 13 to external steam utilization equipment, and a water circulation flow path L10 that merges the hot water separated by the steam separator 13 with the supply water supplied from the water supply pump 10 via the supply water flow path L1 at the confluence point P2 and guides it from the condenser 23 to the steam separator 13.

[0020] The water circulation flow path L10 is composed of a water circulation flow path L2 that communicates from the lower end wall of the steam separator 13 to the condenser 23 and sends hot water to the condenser 23, and a water circulation flow path L3 that communicates from the condenser 23 to the upper side wall of the steam separator 13 and sends the gas-liquid two-phase flow to the steam separator 13. Hot water flows through the water circulation flow path L2, and a gas-liquid two-phase flow containing hot water and steam flows through the water circulation flow path L3.

[0021] The steam separator 13 is composed of a cylindrical container along the vertical direction, and stores water inside the container by replenishing supply water from the supply water flow path L1 connected to the confluence point P2 of the water circulation flow path L2 connected to the lower end wall. The supply water flow path L1 introduces water (feed water) from a water pipe or water tank (not shown) to the water circulation flow path L10 by the water supply pump 10. The steam separator 13 is provided with a water level sensor L, and the water supply pump 10 adjusts the water supply amount so that the water level is maintained at a predetermined water level (predetermined value) based on the water level detected by the water level sensor L.

[0022] The steam flow path L4 is connected to the upper end wall of the steam separator 13 and is a flow path for sending out the steam after the hot water is separated in the steam separator 13 to the outside. A steam pressure regulating valve 14 for adjusting the pressure of the flowing steam is installed in the steam flow path L4. The opening degree of the steam pressure regulating valve 14 is adjusted based on the steam pressure in the steam separator 13 measured by a pressure sensor (not shown).

[0023] At the separation point P1 on the water circulation flow path L2 from the lower end wall of the steam separator 13 to the confluence point P2, a blowdown water flow path L5 is connected to extract a part of the hot water separated by the steam separator 13 and discharge the extracted hot water as blowdown water.

[0024] Furthermore, a heat recovery device 11 for performing heat exchange between the supply water in the supply water flow path L1 between the feed water pump 10 and the subcooler 24 and the blowdown water in the blowdown water flow path L5 is provided. The heat recovery device 11 performs heat exchange between the blowdown water and the supply water and recovers the heat of the blowdown water to the supply water. The supply water with recovered heat is preheated by the subcooler 24 via the check valve 12, and the preheated supply water is led to the condenser 23 as the water to be heated via the confluence point P2. Since this heat recovery device 11 recovers the heat of the high-temperature blowdown water to the supply water, the heat loss due to the drainage of the blowdown water is reduced, and the decrease in the output steam amount of the heat pump type steam generation device 1 can be suppressed.

[0025] A flow rate regulating valve 15 is arranged in the blowdown water flow path L5 between the separation point P1 and the heat recovery device 11. The opening degree of the flow rate regulating valve 15 is preset corresponding to the chloride ion concentration contained in the supply water. Impurities such as silica contained in the supply water circulate between the condenser 23 and the steam separator 13 via the water circulation flow path L10 and are concentrated by the outflow of the steam. Therefore, the above-mentioned blowdown is performed to suppress the increase in the impurity concentration. However, since the chloride ions that corrode the condenser 23 and the like are also concentrated, they are diluted by the blowdown.

[0026] The condenser 23 uses a compact plate heat exchanger with high heat exchange performance. Plate heat exchangers come in two types: an inexpensive copper brazed type and an expensive all-stainless steel type that is highly corrosive. Regarding corrosion resistance, the copper brazed type has a low upper limit for chloride ion concentration, while the all-stainless steel type has a high upper limit for chloride ion concentration. In this embodiment, the chloride ion concentration of the supply water is obtained, and the opening of the flow control valve 15 is set in advance so that the amount of blowdown discharged in the heated water in the condenser 23 becomes less than a specified value, corresponding to the chloride ion concentration of the supply water. This allows the use of an inexpensive copper brazed plate heat exchanger. Furthermore, since the concentrated hot water also flows into the blowdown water channel L5, an inexpensive copper brazed plate heat exchanger can also be used for the heat recovery unit 11.

[0027] In this embodiment, by providing the heat recovery unit 11, heat loss due to the discharge of blowdown water is reduced, and the decrease in the output steam amount of the heat pump type steam generator 1 can be suppressed. Furthermore, by pre-setting the opening degree of the flow control valve 15 to an opening degree corresponding to the chloride ion concentration of the supply water, inexpensive copper brazed plate heat exchangers can be used for the condenser 23 and the heat recovery unit 11.

[0028] <Example 1> Figure 2 shows the overall configuration of a heat pump type steam generator 1 according to Modification 1 of the embodiment of the present invention. In the embodiment, the opening degree of the flow control valve 15 was set in advance to an opening degree corresponding to the chloride ion concentration of the supply water. However, in this Modification 1, as shown in Figure 2, a chloride ion concentration sensor S1 is provided in the water circulation channel L2 between the lower end wall of the steam separator 13 and the separation point P1. The flow control valve 15 increases its opening degree according to the concentration difference from a predetermined chloride ion concentration when the chloride ion concentration detected by the chloride ion concentration sensor S1 increases, and decreases its opening degree according to the concentration difference from a predetermined chloride ion concentration when the chloride ion concentration decreases.

[0029] This makes it possible to keep the chloride ion concentration of the hot water passing through the condenser 23 below a specified value, and allows the use of inexpensive copper brazed plate heat exchangers for both the condenser 23 and the heat recovery unit 11.

[0030] <Modification 2> Figure 3 shows the overall configuration of a heat pump type steam generator 1 according to Modification 2 of the embodiment of the present invention. In this Modification 2, in addition to the configuration of Modification 1, a scale concentration sensor S2 for detecting the scale concentration of hot water is provided in the water circulation channel L2 between the lower end wall of the steam separator 13 and the separation point P1. The scale concentration sensor S2 detects the concentration of scale (impurities) such as silica and calcium. Since silica and calcium precipitate and adhere inside the piping, it is necessary to keep the scale concentration low.

[0031] The flow control valve 15 performs a first opening adjustment, which increases the opening degree according to the concentration difference from a predetermined chloride ion concentration when the chloride ion concentration detected by the chloride ion concentration sensor S1 increases, and decreases the opening degree according to the concentration difference from a predetermined chloride ion concentration when the chloride ion concentration decreases. It also performs a second opening adjustment, which increases the opening degree according to the concentration difference from a predetermined scale concentration when the scale concentration detected by the scale concentration sensor S2 increases, and decreases the opening degree according to the concentration difference from a predetermined scale concentration when the scale concentration decreases. The valve is adjusted to the larger of the opening degree obtained by the first opening adjustment and the opening degree obtained by the second adjustment.

[0032] This makes it possible to keep the chloride ion concentration of the hot water passing through the condenser 23 below a specified value, allowing the use of inexpensive copper brazed plate heat exchangers for the condenser 23 and heat recovery unit 11, and also suppressing scale buildup in the piping.

[0033] It should be noted that the configurations illustrated in the above embodiments and each of the modified examples are functionally schematic and do not necessarily have to be physically arranged as shown. In other words, the distributed and integrated forms of each device are not limited to those shown, and all or part of them can be functionally or physically distributed and integrated in any unit according to various loads and usage conditions. [Explanation of symbols]

[0034] 1. Heat pump type steam generator 2. Heat pump section 3. Steam generation section 10 Water supply pump 11 Heat recovery unit 12 Check valve 13. Steam separator 14. Steam pressure regulating valve 15 Flow control valve 21 Evaporator 22 Compressor 23 Condenser 24 Supercooler 25. Expansion Mechanism L Water level sensor L1 Supply water flow path L2, L3, L10 Water Circulation Channels L4 Steam channel L5 Blowdown water channel P1 separation point P2 confluence S1 Chloride ion concentration sensor S2 Scale concentration sensor

Claims

1. A heat pump unit comprising a compressor for compressing a refrigerant, a condenser for transferring the heat of the refrigerant discharged from the compressor to a heated water to condense the refrigerant, an expansion mechanism for reducing the pressure of the refrigerant condensed in the condenser, and an evaporator for recovering heat from a heat source hot water and evaporating the refrigerant, all connected in a ring shape, A steam separator separates the two-phase gas-liquid flow generated by heat transfer to the heated water in the condenser into steam and hot water. A water level sensor for detecting the water level of hot water in the steam separator, A water circulation channel supplies the gas-liquid two-phase flow from the condenser to the steam separator and returns the hot water separated by the steam separator to the condenser, A steam flow path that sends the steam separated by the steam separator as output steam to an external steam utilization facility, A water supply channel connected to the water circulation channel between the steam separator and the condenser, which supplies the water to be heated, A water supply pump that supplies the supply water to the supply water channel so that the water level of the hot water detected by the water level sensor reaches a predetermined value, A blowdown water channel is provided for extracting a portion of the hot water separated by the steam separator and discharging the extracted hot water as blowdown water. In a heat pump type steam generator equipped with, A heat recovery device is provided to perform heat exchange between the blowdown water and the supply water, and to recover the heat from the blowdown water into the supply water. A chloride ion concentration sensor for detecting the chloride ion concentration of the hot water separated by the steam separator, A flow control valve with adjustable opening is provided in the blowdown water channel upstream of the heat recovery unit, A scale concentration sensor for detecting the scale concentration of the hot water separated by the steam separator, Equipped with, The flow control valve is characterized by performing a first opening adjustment, which increases the opening degree according to the concentration difference from a predetermined chloride ion concentration when the chloride ion concentration detected by the chloride ion concentration sensor increases, and decreases the opening degree according to the concentration difference from a predetermined chloride ion concentration when the chloride ion concentration decreases, and a second opening adjustment, which increases the opening degree according to the concentration difference from a predetermined scale concentration when the scale concentration detected by the scale concentration sensor increases, and decreases the opening degree according to the concentration difference from a predetermined scale concentration when the scale concentration decreases, and adjusting to the larger of the opening degree obtained by the first opening adjustment and the opening degree obtained by the second adjustment.

2. The heat pump type steam generator according to claim 1, characterized in that the condenser and the heat recovery unit are copper brazed plate type heat exchangers.

Images