JP5387263B2 - Steam reheating device - Google Patents

Description

  The present invention relates to a steam reheating apparatus that reheats low-temperature steam that has been lowered in temperature in a steam utilization process to form high-temperature steam and supplies the high-temperature steam again to the steam utilization process.

  In the steam process, generally, steam (water vapor) is generated in a boiler and is sent to a steam header (steam reservoir), and the steam is distributed from the steam header to each steam utilization process. The distributed steam releases heat in each steam utilization process to lower the temperature and pressure, and is finally discharged to the steam drain.

  Such a steam process uses a steam reheating device that reheats the low-temperature steam, which has been lowered (dryness decreased) in the steam utilization process, into high-temperature steam, and supplies the high-temperature steam again to the steam header or steam utilization process. It has been. By using the steam reheating device, the amount of steam generated by the boiler can be reduced, and energy saving can be realized.

  As a conventional steam reheating device, so-called steam re-compression (hereinafter referred to as VRC) steam reheating, in which low-temperature steam that has been lowered in the steam utilization process is recompressed (reheated) with a compressor. There is a device.

  As an example, in the VRC-type steam reheating device 41 shown in FIG. 4, steam generated in the boiling kettle 42 (for example, steam at 100 ° C.) is compressed by the compressor 43 into high-temperature steam (for example, steam at 136 ° C.), The high-temperature steam is heat-exchanged with a liquid (for example, wort) boiled in the boiling pot 42 by the heater 44, and the heated liquid is returned to the boiling pot 42 so that the boiling pot 42 can be efficiently boiled. I have to.

  In the case where auxiliary equipment such as a steam reheating device is not used, measures are taken to suppress a decrease in the dryness of steam in the steam utilization process by preliminarily increasing the steam flow rate and pressure.

  As prior art document information related to the invention of this application, there are Patent Documents 1 and 2.

JP 2007-71419 A JP 2008-45806 A

  However, when the incidental equipment is not used, an excessive supply of steam to the required amount of steam is uneconomical, which is not preferable from the viewpoint of energy saving.

  Therefore, it is desirable to use a steam reheating device, but in the conventional VRC type steam reheating device, the steam is compressed by a compressor, and the compressor that compresses the steam is currently about 130 to 135 ° C. Therefore, there is a problem that it can be applied only to a low-temperature steam process of about 130 to 135 ° C.

  Accordingly, an object of the present invention is to provide a steam reheating apparatus that solves the above-described problems and can be applied to a high-temperature steam process, and is economical and can realize energy saving.

  The present invention was devised to achieve the above-described object. The low-temperature steam that has been reduced in temperature in the steam utilization process is reheated to form high-temperature steam, and the steam re-supply for supplying the high-temperature steam to the steam utilization process again. A heating device that exchanges heat with a high-temperature heat source and evaporates the heat medium, a compressor that compresses the heat medium evaporated by the evaporator, and a compressor that compresses the heat medium A heat pump comprising: a condenser that heat-exchanges the heat medium with a low-temperature heat source and condenses the heat medium; and an expansion valve that expands the heat medium condensed by the condenser and supplies the heat medium to the evaporator; A low temperature steam introduction line for supplying the low temperature steam to the evaporator of the heat pump as the high temperature heat source, and the low temperature steam from the low temperature steam introduction line is condensed by exchanging heat with the heat medium in the evaporator. Hot water A booster line for supplying the condenser of the heat pump as the low-temperature heat source; a booster pump provided in the booster line for boosting the hot water to supply the condenser; and the heat from the booster line The steam reheating device includes a high-temperature steam supply line that supplies the high-temperature steam, which is evaporated by heat exchange with the heat medium in the condenser, to the steam utilization process.

  The temperature difference between the low temperature steam and the high temperature steam is preferably 5 to 30 ° C.

  The heat pump may further include a supercooler for supercooling the heat medium condensed by the condenser.

  The subcooler may be formed integrally with the condenser.

  Supplying water to the supercooler may cause the water to be exchanged with the heat medium in the supercooler so that the heat medium is supercooled and the water is heated to obtain hot water. .

  The low-pressure steam drain recovered in the steam utilization process is supplied to the supercooler, the low-pressure steam drain is heat-exchanged with the heat medium in the supercooler, and the heat medium is supercooled, and The low pressure steam drain may be heated to obtain low pressure steam.

  ADVANTAGE OF THE INVENTION According to this invention, the steam reheating apparatus which can be applied also to a high temperature steam process and can implement | achieve economical and energy saving can be provided.

It is a schematic block diagram which shows the vapor | steam utilization system using the vapor | steam reheating apparatus which concerns on one embodiment of this invention. In this invention, it is a figure which shows the thermal cycle of the heat medium of a heat pump. It is a schematic block diagram which shows the vapor | steam utilization system using the vapor | steam reheating apparatus which concerns on one embodiment of this invention. It is a schematic block diagram which shows the conventional steam reheating apparatus.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram of a steam utilization system using the steam reheating device according to the present embodiment.

  As shown in FIG. 1, a steam utilization system 1 includes a plurality of (two in FIG. 1) boilers 2 that generate high-temperature and high-pressure steam, a steam header 3 that stores high-temperature and high-pressure steam generated by the boiler 2, A steam supply pipe 5 that supplies high-temperature and high-pressure steam from the steam header 3 to the steam utilization apparatus 4 and a steam discharge pipe that discharges the steam that has been radiated by the steam utilization apparatus 4 and reduced in temperature and pressure (hereinafter simply referred to as low-temperature steam). 6, a steam drain 7 that recovers low-temperature steam discharged from the steam discharge pipe 6 as a low-pressure steam drain, and a steam reheating device 8 of the present invention.

  The steam reheating device 8 reheats the low-temperature steam that has been reduced in temperature and pressure in the steam utilization process (here, the steam utilization device 4) to form high-temperature and high-pressure steam (hereinafter simply referred to as high-temperature steam). It is again supplied (recirculated) to the utilization process (steam utilization device 4).

  The steam reheating device 8 mainly includes a heat pump 9, a low-temperature steam introduction line 10, a boost line 11, and a high-temperature steam supply line 12.

  The heat pump 9 exchanges the heat medium with a high-temperature heat source, evaporates the heat medium, the compressor 14 compresses the heat medium evaporated by the evaporator 13, and the heat medium compressed by the compressor 14. Is exchanged with a low-temperature heat source, the condenser 15 for condensing the heat medium, the supercooler 16 for supercooling the heat medium condensed by the condenser 15, and the heat medium from the subcooler 16 is expanded and evaporated. And an expansion valve 17 for supplying to the vessel 13.

  One end of the low-temperature steam introduction line 10 is connected to the steam discharge pipe 6 on the downstream side of the steam utilization device 4, and the other end is connected to the evaporator 13 of the heat pump 9. A part of the low temperature steam discharged to the heat pump 9 is supplied to the evaporator 13 of the heat pump 9 as a high temperature heat source.

  One end of the booster line 11 is connected to the evaporator 13 of the heat pump 9, the other end is connected to the condenser 15 of the heat pump 9, and the booster line 11 is provided with a booster pump 18. The booster line 11 boosts hot water (low-pressure hot water), which has been condensed into a liquid by heat exchange of the low-temperature steam with the heat medium in the evaporator 13, and is pressurized to high-pressure hot water by the booster pump 18. Water is supplied to the condenser 15 of the heat pump 9 as a low-temperature heat source. The booster pump 18 pressurizes the hot water so that the pressure is slightly higher than that of the steam header 3 to obtain high-pressure hot water.

  One end of the high-temperature steam supply line 12 is connected to the condenser 15 of the heat pump 9, and the other end is connected to the steam supply pipe 5 on the upstream side of the steam utilization device 4. High-temperature steam evaporated by heat exchange with the heat medium is supplied to the steam utilization device 4 via the steam supply pipe 5.

  A supercooling heat source supply line 19 for supplying a low-temperature supercooling heat source is connected to the supercooler 16 in order to supercool the heat medium condensed by the condenser 15. The supercooling heat source supply line 19 is provided with a control valve 20 for adjusting the flow rate of the supercooling heat source.

  The temperature difference ΔT between the low temperature steam and the high temperature steam is appropriately set in consideration of the efficiency of the heat pump 9 because the efficiency of the heat pump 9 decreases as the temperature difference ΔT increases. Specifically, it is considered that the practicality is high when the temperature difference ΔT between the low temperature steam and the high temperature steam is in the range of 20 to 30 ° C., but the temperature difference ΔT has a sufficient function if it is 5 ° C. or more.

  The temperature of the low temperature steam is desirably 100 ° C. or higher. This means that when the temperature of the low-temperature steam is less than 100 ° C., it means that the steam discharge pipe 6 is operating at a negative pressure, but there is almost no practical use and the efficiency of the heat pump 9 described above. This is because a sufficient amount of high-temperature steam may not be obtained in consideration. The temperature of the high-temperature steam is desirably 180 ° C. or less, and considering that the temperature difference ΔT between the low-temperature steam and the high-temperature steam is in the range of 20 to 30 ° C., the temperature of the low-temperature steam is 100 to 160 ° C. The temperature of the steam is preferably set to be in the range of 120 to 180 ° C. In this embodiment, the temperature of the low temperature steam is 140 ° C., the temperature of the high temperature steam is 160 ° C., and the temperature difference ΔT between the low temperature steam and the high temperature steam is 20 ° C.

  The heat medium used for the heat pump 9 is not particularly limited, but appropriate evaporation / condensation is performed in consideration of temperature conditions for regenerating low-temperature steam (140 ° C. here) into high-temperature steam (160 ° C. here). A heat medium having a temperature may be appropriately selected and used. Thereby, the heat pump 9 forms a heat pump cycle that maintains a heat medium low pressure temperature capable of condensing the low pressure steam and a heat medium high pressure temperature capable of evaporating the high pressure hot water.

  As a heat source for supercooling supplied to the supercooler 16, low-pressure steam drain recovered in the steam drain 7 or feed water may be used. Thereby, the low pressure steam drain is heated by the supercooler 16 and supplied to the low pressure steam line outside the system as low pressure steam, or the feed water is heated by the supercooler 16 and the hot water system outside the system is used as hot water. And it becomes possible to supply to the boiler 2 as boiler feed water, and it becomes possible to improve energy-saving property more.

  Next, the operation of the steam reheating device 8 will be described.

  A part of the low-temperature steam discharged from the steam utilization device 4 to the steam discharge pipe 6 is introduced into the evaporator 13 of the heat pump 9 through the low-temperature steam introduction line 10.

  The evaporator 13 heat-exchanges the low-temperature steam from the low-temperature steam introduction line 10 with the heat medium, applies the latent heat of the low-temperature steam to the heat medium to evaporate the heat medium, condenses the low-temperature steam to hot water (here, 140 ° C. hot water).

  The heat medium evaporated by the evaporator 13 is pressurized (heated) by the compressor 14 and supplied to the condenser 15. On the other hand, the hot water in which the low-temperature steam is condensed in the evaporator 13 is pressurized by the booster pump 18 to become high-pressure hot water, and is supplied to the condenser 15 via the booster line 11.

  In the condenser 15, the high-pressure hot water from the booster line 11 exchanges heat with the heat medium, the latent heat of the heat medium is given to the high-pressure hot water, the high-pressure hot water is evaporated, and high-temperature high-pressure high-temperature steam (160 ° C. here) And the heat medium is condensed.

  The heat medium condensed in the condenser 15 is further cooled by exchanging heat with the supercooling heat source in the subcooler 16, expanded in the expansion valve 17, and supplied to the evaporator 13. On the other hand, the high-temperature steam obtained by evaporating the high-pressure hot water in the condenser 15 is supplied to the steam supply pipe 5 via the high-temperature steam supply line 12 and is supplied again to the steam utilization device 4.

  Here, the heat cycle (heat pump cycle) of the heat medium in the heat pump 9 will be described.

  As shown in FIG. 2, the heat medium of the heat pump 9 repeats the cycle of evaporation, compression, condensation, and expansion.

  In the present embodiment, heat absorption (heat reception) in the evaporation process is performed by transferring the condensation latent heat of the low-temperature steam in the evaporator 13. At this time, the heat absorption amount (low-pressure side heat reception amount) and the heat release in the condensation process are performed. In terms of the amount of heat (high-pressure side released heat amount), the latter is larger. That is, in the heat pump 9, in addition to the amount of heat necessary for steam reheating (the amount of heat necessary to convert the low temperature steam into the high temperature steam), an excessive amount of heat can be released.

  This excess amount of heat is limited by the pressure temperature setting of the heat pump cycle and the type of the heat medium. For example, if studied at the above temperatures (low temperature steam 140 ° C, high temperature steam 160 ° C), low pressure steam or hot water is produced. The amount of heat is enough to do.

  More specifically, the condensation process in the heat cycle of the heat medium includes a latent heat heat release process that dissipates latent heat of condensation when the heat medium is condensed from gas (gas phase) to liquid (liquid phase), and heat that has become liquid. It can be divided into a subcooling process in which the sensible heat of the medium is further dissipated and cooled. In the present embodiment, the condenser 15 dissipates the latent heat of condensation of the heat medium, and the supercooler 16 dissipates the sensible heat of the heat medium that has become a liquid to supercool the heat medium.

  The high-pressure hot water supplied from the booster line 11 receives and transfers the latent heat of condensation of the heat medium (the latent heat of evaporation of the high-pressure hot water) in the condenser 15 and becomes high-temperature and high-pressure steam (high-temperature steam). Further, the supercooling heat source (for example, low-pressure steam drain or feed water) supplied from the supercooling heat source supply line 19 receives and heats the sensible heat of the heat medium in the supercooler 16 and is heated, for example, low pressure Steam or hot water.

  As described above, in the steam reheating device 8, in addition to the amount of heat necessary for the steam reheating, the heat amount that can generate low-pressure steam, hot water, and the like is generated from the heat pump 9, so that it also serves as a heat source other than the main process. be able to.

  The operation of the present embodiment will be described.

  In the steam reheating device 8 according to the present embodiment, low temperature steam is supplied to the evaporator 13 of the heat pump 9 in the low temperature steam introduction line 10, and the low temperature steam is condensed by exchanging heat with the heat medium in the evaporator 13. The hot water is boosted by the booster pump 18 and supplied as a low-temperature heat source to the condenser 15 of the heat pump 9 via the booster line 11, and the hot water is evaporated by exchanging heat with the heat medium in the condenser 15. The high-temperature steam supply line 12 supplies the steam using process.

  As described above, in the conventional VRC type steam reheating device, it is necessary to compress the vapor in the gas phase by the compressor, so that the current compressor performance is a low temperature steam process of about 130 to 135 ° C. Only applicable.

  On the other hand, in the present embodiment, the low-temperature steam is condensed by the evaporator 13 of the heat pump 9 into hot water, and the hot water is pressurized in the liquid phase by the booster pump 18. Although it is difficult to compress steam, it is relatively easy to increase the pressure in liquid phase compression (pump pressurization). By incorporating such liquid phase compression into the heat pump process, it is possible to achieve higher temperature steam processes. The steam reheating device 8 that can be applied and has a high degree of freedom in temperature design can be realized.

  Therefore, the steam reheating device 8 can be applied to a steam process at 150 ° C. or higher which cannot be handled by the conventional VRC type steam reheating device. VRC is mainly applied to the food field, but since the industrial field having a steam process of 150 ° C. or higher is diverse, the steam reheating device 8 of the present invention is widely used not only in the food field but also in fields other than the food field. Applicable.

Further, in the steam reheating device 8, the low temperature steam that has been lowered in temperature by the steam using device 4 is reheated by the heat pump 9 and recirculated to the steam supply pipe 5 on the upstream side of the steam using device 4. The amount of steam to be produced can be reduced, boiler fuel costs and CO ₂ emissions can be reduced, and an economical and energy-saving steam reheating device 8 can be realized.

  Moreover, in the steam reheating apparatus 8, since the temperature difference ΔT between the low temperature steam and the high temperature steam is set to 20 to 30 ° C., the steam reheating can be performed without reducing the efficiency of the heat pump 9. If the temperature difference ΔT is reduced, the steam reheating degree is lowered, but the efficiency of the heat pump 9 is further increased.

  Furthermore, in the steam reheating device 8, in addition to the amount of heat necessary for steam reheating by the heat pump 9, the amount of heat that can generate low-pressure steam, hot water, and the like is generated. By using it as a heat source other than the main process, for example, a heat source for heating the feed water to warm water, or a heat source for heating the low-pressure steam drain recovered by the steam drain 7 to low-pressure steam, energy saving is achieved. Can be increased.

  In the above-described embodiment, the condenser 15 and the supercooler 16 are separated, but the condenser 15 and the supercooler 16 may be integrated.

  The steam reheating device 31 shown in FIG. 3 is the same as the steam reheating device 8 described in FIG. 1 except that the supercooler 16 is omitted and a condenser 32 having a supercooling function is provided. The condenser 32 is obtained by integrating the condenser 15 and the supercooler 16 in the vapor reheating device 8, and condenses the heat medium and supercools it.

  The condenser 32 is connected with a heat source supply line 19 for supercooling in addition to the pressure boosting line 11 and the high-temperature steam supply line 12, and exchanges heat between the heat medium and high-pressure hot water, and for heat medium and supercooling. The heat source is configured to exchange heat.

  Thus, by integrating the condenser and the supercooler, the supercooler can be omitted and the number of heat exchangers can be reduced, so that the equipment cost can be reduced.

  Moreover, in the said embodiment, although the high temperature steam from the condensers 15 and 32 of the heat pump 9 was supplied to the steam supply piping 5 of the upstream of the steam utilization apparatus 4, it is not restricted to this, For example, high temperature steam May be supplied to the steam header 3.

  As described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Steam utilization system 2 Boiler 3 Steam header 4 Steam utilization apparatus 5 Steam supply piping 6 Steam discharge piping 7 Steam drain 8 Steam reheating apparatus 9 Heat pump 10 Low temperature steam introduction line 11 Boosting line 12 High temperature steam supply line 13 Evaporator 14 Compressor 15 Condenser 16 Supercooler 17 Expansion Valve 18 Booster Pump 19 Supercooling Heat Source Supply Line 20 Control Valve

Claims (6)

A low-temperature steam that has been lowered in temperature in the steam utilization process is reheated into a high-temperature steam, and the high-temperature steam is supplied again to the steam utilization process.
An evaporator that exchanges heat with a high-temperature heat source and evaporates the heat medium, a compressor that compresses the heat medium evaporated by the evaporator, and a low-temperature heat source that compresses the heat medium compressed by the compressor A heat pump comprising: a condenser that exchanges heat with the condenser; and an expansion valve that expands the heat medium condensed in the condenser and supplies the refrigerant to the evaporator;
A low-temperature steam introduction line for supplying the low-temperature steam as the high-temperature heat source to the evaporator of the heat pump;
A booster line for supplying hot water condensed from the low temperature steam from the low temperature steam introduction line by heat exchange with the heat medium in the evaporator as the low temperature heat source to the condenser of the heat pump;
A booster pump provided in the booster line, pressurizing the hot water and supplying the hot water to the condenser;
Steam provided with a high-temperature steam supply line for supplying the high-temperature steam evaporated from the hot water from the boosting line by exchanging heat with the heat medium in the condenser to the steam utilization process Reheating device.   The steam reheating apparatus according to claim 1, wherein a temperature difference between the low temperature steam and the high temperature steam is 5 to 30 ° C.   The steam reheating device according to claim 1, wherein the heat pump further includes a supercooler for supercooling the heat medium condensed by the condenser.   The steam reheating device according to claim 3, wherein the subcooler is formed integrally with the condenser.   The feed water is supplied to the subcooler, the feed water is heat-exchanged with the heat medium in the subcooler, the heat medium is supercooled, and the feed water is heated to obtain hot water. The steam reheating device according to 3 or 4.   The low-pressure steam drain recovered in the steam utilization process is supplied to the supercooler, the low-pressure steam drain is heat-exchanged with the heat medium in the supercooler, and the heat medium is supercooled, and The steam reheating apparatus according to claim 3 or 4, wherein the low pressure steam drain is heated to obtain low pressure steam.

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