JPH0670540B2 - Waste heat recovery equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Object of the invention Industrial field of application The present invention relates to a technique for recovering energy from a large amount of steam or high temperature water discharged from a factory or the like in a form that can be reused.

Conventional technology As one of the means to recover waste heat and reuse it,
For example, the following technologies are known.

That is, a chlorofluorocarbon refrigerant is used as a heat medium, and this refrigerant is heated by a waste fluid through a heat exchanger to be gasified, and the gas pressure is used to extract energy, or the latent heat when liquefying the gas is used. That's how it's done.

According to this method, there is an advantage that the hot fluid discharged from the apparatus can be operated even if it is somewhat dirty, but there are the following drawbacks.

(1) Heat exchange equipment is effective.

(2) The gasification temperature is low and the power for driving the compressor is large.

(3) When a CFC-based refrigerant is used, the load temperature cannot be raised too much due to the poor thermal stability of the CFC-based refrigerant (which decomposes at around 110 to 120 ° C.).

When compressing the refrigerant using a screw compressor,
In order to seal the gas leakage between the rotor tooth profiles, oil is injected into the working space, and this oil reduces (4) the decomposition temperature of the refrigerant.

(5) The refrigerant and oil deteriorate.

(6) A device for separating oil and refrigerant is required.

Furthermore, it is known that the following devices perform the following operations.

A large amount of waste steam discharged from factories is compressed through a liquid injection type screw compressor into high temperature high pressure steam, which is then introduced into a heat exchanger and used as a load fluid (steam or other fluid in other systems). The temperature of the water is increased, and a part of the warm water condensed by the heat exchanger is injected into the working space after the suction cutoff of the compressor to perform liquid sealing of the gap generated when the space is formed. It is used for liquid sealing and cooling of the shaft sealing device of the bearing part of the compressor rotor. That is, (a) FIG. 1 shows a basic system A of the same waste heat recovery apparatus, in which a double-lined pipeline is a steam passage that flows in the direction of the arrow, and a single line. The pipeline indicated by is a hot water channel, and this also indicates that it flows in the direction of the arrow as before.

The specific numerical values representing the characteristics of the fluid in each process illustrated below are given only to help the understanding of the operation of this type of device, and the characteristics of the present technology are not necessarily limited by the above numerical values. Please note that.

In the figure, 1 is a liquid injection type screw compressor, which is an electric motor 3
Driven by.

4 is a heat exchanger, which is distributed in other systems and is about 100 to 120.
Passage of load fluid (for waste heat recovery) consisting of steam at ℃
18 are built in.

A large amount of 100 ° C, 1ata steam discharged from factories and the like is sent to the suction side 7 of the compressor 1 through the pipe 6, and is compressed there to become, for example, about 5.5ata, 280 ° C steam. ,
From the discharge side 11 to the heat exchanger 4 via the pipe line 12,
The load fluid passing through the pipe line 21, for example, the load fluid at 100 to 120 ° C. is warmed and heated to around 150 ° C. At the same time, the steam cooled by the heat exchange condenses into warm water of 5.5ata and 155 ° C., passes through the pipe line 13, and a part of the steam is sent from the discharge port 19 side to the reuse destination through the valve 5. On the other hand, the hot water sent to the screw compressor 1 side through the pipe 14 branched from the pipe 13 is injected into the working space after the suction cutoff of the compressor in order to improve the compression efficiency of the compressor. To form the same space, that is, between the rotor tooth profile and the end face is liquid-sealed to inject compressed gas from the nozzle 16 so that leakage of compressed gas does not occur between the low pressure part and the high pressure part, and the screw is also used. The liquid is circulated through the pipe line 24 branched from the pipe line 14 for liquid sealing of the shaft sealing device of the rotor bearing and removal of frictional heat.

At that time, since the warm water returned from the heat exchanger 4 maintains the pressure of 5.5ata, it can be injected into the working space of the compressor without additional pressurization.

Further, the hot water is supplied from the heat exchanger 4 at a temperature of 155 ° C., but the temperature rise due to friction of the shaft sealing device exceeds this sufficiently, so that the cooling effect is necessary and sufficient.

In addition to the above-mentioned basic system and action, another part of the warm water returned through the heat exchanger is introduced into an economizer (consisting of an expansion valve and a separator), where it is flushed for gas / liquid separation. Since steam still has a high pressure, it is recovered and supplied to the working space of the compressor as it is, and part of the separated hot water is liquid-sealed in the working space of the compressor and liquid-sealing and cooling of the shaft sealing device of the rotor bearing. It reduces the driving power of compression and enables energy saving operation.

When the screw compressor is composed of low compression means, a part of the hot water condensed by the heat exchanger is supplied to the working space after the suction cutoff of the high compression means and separated by the economizer. While supplying the vapor to the suction side or the working space of the high compression means, a part of the hot water is injected into the working space of the low compression means to form a liquid seal in the gap generated when the space is formed and the shaft sealing device. Used for liquid sealing and cooling.

(B) FIG. 2 shows another basic system B, in which the compressor provided in the above system A (FIG. 1) is replaced with a compressor composed of low compression means and high compression means. In the figure, members having the same reference numerals as in the system A have the same description, name, configuration and effect as the system A.
A description of this will be omitted.

Liquid injection type screw compressors 1 and 2 are low compression means 1 and high compression means 2 and are driven by an electric motor 3. The compressor may have a structure in which the low compression means and the high compression means are integrally driven by the same shaft, or they may be separated and driven in a tandem type by a common motor.

In the same system B, a large amount of 100 ℃ discharged from factories,
The water vapor of 1ata passes through the line 6 and the low compression means 1 of the compressor.
Of the high compression means 2 is sent to the suction side 7 of the high compression means 2 through a pipe line 9, and is compressed there to become, for example, about 23ata of water vapor and discharged to the discharge side 8. It is further compressed into water vapor at 55ata and 280 ° C, which is sent from the discharge side 11 to the heat exchanger 4 via the pipe line 12,
As in the system A, a load fluid passing through the pipeline 21, for example, 100 to 1
Warm the load fluid at 20 ° C and heat it to around 150 ° C.

At the same time, the steam that has been cooled by the heat exchange action condenses into hot water of 5.5ata, 155 ° C, passes through the pipe line 13, and part of it passes through the discharge side 19 through the valve 5 and is reused. Sent.

On the other hand, in the same manner as described in the description of the system A, the same is formed by injecting from the pipe line 13 into the working space after the suction cutoff of the compression means 1 and 2 through the branched pipe lines 14 and 15, respectively. The gaps created at this time, that is, between the rotor tooth profiles, and between the cylinder inner wall and the rotor tooth profiles and the end faces are liquid-sealed, and compressed gas is injected from the nozzles 16 and 17 to prevent leakage of the compressed gas between the low pressure part and the high pressure part. Also, in order to seal the shaft seal device of the bearing portion of the screw rotor and to remove frictional heat, the liquid is circulated through the pipe lines 24 and 25 branched from the pipe lines 14 and 15, respectively.

At that time, since the warm water returned from the heat exchanger 4 maintains a pressure of 5.5ata, it can be supplied to the working space of any of the compressors without repressurization.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention enables operation at a higher temperature even though it is a relatively simple device, so that the efficiency of recovering waste heat is excellent and a higher temperature load fluid can be obtained. Moreover, it is an object of the present invention to provide a heat pump that can reduce operating costs.

That is, after the waste steam is pressurized by the liquid injection type screw compressor in the above device, it is guided to the heat exchanger, and a part of the warm water that has been condensed by heat exchange with the load fluid is sealed with the liquid in the working space of the compressor. It is used for liquid sealing and cooling of the shaft sealing device, and part of the other is separated into gas and liquid through an economizer, and the vapor is introduced again into the working space of the compressor to reduce the driving force of the compressor and save energy. A heat pump capable of obtaining Further, the present invention is intended to realize a heat pump that is designed to use the warm water that has been condensed and to reduce the operating cost.

Another object of the present invention is to provide the above-mentioned waste heat recovery device that obtains an inexpensive and energy-saving effect by directly contacting hot water from an economizer with the waste steam or waste high temperature water in a flash tank to generate steam. is there.

Furthermore, other objects and advantages will be apparent from a consideration of the claims of the present invention, the detailed description of the invention and the description of the accompanying drawings.

(B) Structure of the Invention Means for Solving the Problems In order to achieve the above-mentioned object, the present invention is required to be composed of the following matters.

(1) Waste water vapor is adiabatically compressed through a screw compressor and then a load fluid is heated through a heat exchanger, which is reused in another system and condensed in the heat exchanger. A part of the hot water produced by injecting is injected into the working space of the compressor after the suction cutoff, and a liquid seal in the gap of the working space generated when the space is formed and a liquid seal of the shaft sealing device of the compressor and In addition to being used for cooling, another part of hot water is guided to a separator via an expansion valve, separated into steam and hot water, and the steam is supplied into the working space after the suction cutoff of the compressor. A waste heat recovery device characterized in that

(2) The discarded steam is supplied to the flash tank to separate it into steam and warm water, and the separated steam is sent to the screw compressor, and the warm water separated in the separator is generated. Part of the above is supplied to the flash tank, which is similarly separated into steam and hot water, and the waste steam thereof is combined and sent to the screw compressor. Waste heat recovery device.

(3) The screw compressor is composed of a low compression means and a high compression means, and supplies a part of the warm water condensed in the heat exchanger to the working space of the high compression means after the intake cutoff. While supplying the water vapor separated by the separator through the expansion valve to the suction side or the working space of the high compression means, a part of the hot water separated there is injected into the working space of the low compression means after shutting off the same space. The waste heat recovery device according to item (1) or (2) above, which is used for liquid sealing of a gap in an action space generated during formation and for liquid sealing and cooling of a shaft sealing device of the same means.

(4) The hot water separated in the separator through the expansion valve is supplied to the compressor and the flash tank after preheating the load fluid passing through the heat exchanger.
The waste heat recovery device according to item (2) or (3).

Action Since the present invention is formed of the above-mentioned constituent elements, the following action is basically performed in the device.

A large amount of waste steam discharged from factories is compressed through a liquid injection type screw compressor into high temperature high pressure steam, which is then introduced into a heat exchanger and used as a load fluid (steam or other fluid in other systems). In addition to increasing the temperature of the compressor, the warm water condensed in the heat exchanger still maintains high temperature and high pressure, so some of it is injected into the working space after the intake cutoff of the compressor, respectively. It is used for liquid sealing and cooling of the shaft sealing device of the bearing portion of the rotor of the compressor while liquid sealing the gap generated during formation.

Some of the remaining hot water is reused for other purposes.

In other words, in addition to the above basic actions, the other part of the warm water that has returned to the economizer through the heat exchanger is introduced into the economizer where it is flushed and vapor-liquid separated is still high in pressure, so leave it as it is. Collect and supply to the working space of the compressor,
Therefore, a part of the separated hot water is discharged to reduce the driving power for compression and enable energy saving operation.

When the screw compressor is composed of a low compression means and a high compression means, a part of the warm water condensed by the heat exchanger is supplied to the working space after the suction cutoff of the high compression means, The vapor separated by the economizer is supplied to the suction side or the working space of the high compression means, while a part of the hot water is injected into the working space of the low compression means to form a liquid seal in the gap generated when the space is formed. Used for liquid sealing and cooling of shaft sealing devices.

In addition to the above-mentioned action, stop the direct supply of the discharged steam to the compressor, connect the flash tank in front of the compressor, and introduce the warm water discharged from the economizer to the flash to separate it into gas and liquid. The steam thus produced is combined with the steam discharged before and supplied to the compressor to improve the waste heat recovery efficiency and reduce the operating cost.

In addition, by providing a second heat exchanger (preheater) between the economizer and the flash tank, and preheating the load fluid guided to the first heat exchanger by the warm water condensed by the economizer, It is also possible to enhance the heat recovery effect.

Example 1 Each member constituting each example of the waste heat recovery apparatus of the present invention described below is a special reason considering that appropriate design changes can be made within the technical level at the time of filing the present invention. It should not be understood that the gist of the present invention is limited based on only the configuration of the present embodiment without showing.

FIG. 3 shows a systematic diagram of an embodiment of the device of the present invention. In the figure, members designated by the same reference numerals as those of the system A have the same names, the same structures as those in the description in FIG. Since it has an effect, its description is omitted.

Part of the hot water of 5.5ata and 155 ° C generated by condensing in the heat exchanger 4 passes through the pipes 13 and 15 and, like the action of the system A,
It circulates through the nozzle 17 into the working space after the intake cutoff of the compressor 1 and through the pipe 25 branched from the pipe 15 for liquid sealing and cooling of the shaft sealing device of the bearing portion of the screw rotor. However, the other part was decompressed through the expansion valve 26, and flushed water of 2.75ata, ≈130 ° C was introduced into the separator 27 via the pipe 28 to separate gas and liquid, and gasified about 2.75at.
The water vapor of a, 130 ° C. is sent to the working space equivalent to the atmospheric pressure of the compressor 1 through the pipe 29, and the hot water of 2.75ata, 130 ° C. is sent from the discharge port 19 to the reuse destination through the pipe 30 and the valve 5.

Needless to say, even if the expansion valve 26 is built in the separator 27 and replaced with an economizer that integrates the two, the same actions and effects can be obtained.

Further, in the device of this embodiment, a part of the warm water condensed by the heat exchanger 4 is circulated to the working space of the compressor 1 and the shaft sealing device through the pipes 13 and 15, but this is stopped. The same effect can be obtained even if the hot water is circulated through the compressor using a conduit branched from the conduit 30.

Embodiment 2 FIG. 4 is another embodiment based on the waste heat recovery apparatus of the system B in which the compressor is composed of the low compression means and the high compression means, and is attached to the system B in the figure. Since the members given the same reference numerals as those having the same names have the same names, the same structures and effects as the members described in the description, the description thereof will be omitted.

In the figure, a part of the hot water of 5.5ata and 155 ° C generated by the condensate in the heat exchanger 4 passes through the pipes 13 and 15 and the suction cutoff of the high compression means 2 is performed as in the case of the first embodiment. Nozzle in the working space after
17 and through a pipe line 25 branched from the pipe line 15 for liquid sealing and cooling of the shaft sealing device of the bearing portion of the screw rotor, while part of the other part flows through the pipe line.
In the same manner as the expansion valve 26, introduced into the separator 27 via the conduit 28,
The vaporized and liquid-separated, gasified water vapor of about 2.75ata and 130 ° C is passed through the pipe 29 to the suction side of the high compression means 2 or the working space equivalent to the atmospheric pressure, and the separated hot water of 2.75ata and 130 ° C is fed to the pipe 30
Low compression means 1 through the pipe line 14 and the nozzle 16.
The space between the working spaces is liquid-sealed, and is supplied through the pipe line 24 for liquid-sealing and cooling of the shaft sealing device of the bearing portion of the screw / rotor. Sent to.

Embodiment 3 FIG. 5 shows a system diagram of another embodiment of the waste heat recovery system of the present invention. The compressor used in the system of this embodiment is composed of low compression means and high compression means. Since the substantial action and effect are the same regardless of whether the compressor is used, the waste heat recovery device using the former compressor will be described in this description.

Further, in the figure, members designated by the same reference numerals as those used in the description of the second embodiment have the same structure and effect as those of the second embodiment, and therefore will not be explained again.

In this example, a large amount of 100 ° C, 1ata discharged from the factory, etc.
Before and after the waste hot water before and after being supplied to the compression means 1 and 2 through the pipe line 6, it is introduced into the flash tank 35 and spray pipe
While spraying into the tank by 22, the hot water of 2.75ata and 130 ° C separated in the separator 27 is supplied into the flash tank 35 through the pipes 30 and 32, and then flows into the flash tank through the spray pipe 36 and flashes. Then, the generated steam is merged with the heat source steam sent from the pipe 6, and is supplied to the intake port side 7 of the compressor 1 through the pipe 38.

At this time, the eliminator 37 is provided in the tank 35 to remove the droplets contained in the flushed steam, and the vapor is sucked into the compressor.

At this time, the high-temperature water from the spray pipe 36 and the waste steam or high-temperature water from the pipe 6 are in direct contact with each other to exchange heat, so that no loss occurs in the heat exchanger.

The hot water formed in the flash tank 35 is sent from the discharge port 19 side to the reuse destination through the valve 5.

Embodiment 4 Another embodiment of the device of the present invention is as follows.

In the system diagram of Example 3 shown in FIG. 5, the hot water of 2.75ata, 130 ° C. supplied from the separator 27 through the pipeline 30 is the pipeline 1
Compressor 1 and flash tank 35 via 4 and 32
The preheater 39 preheats the load fluid fed to the heat exchanger 4 prior to introduction into the heat exchanger 4.

This system is particularly effective when the load fluid inlet temperature is low. Other configurations are the same as those of the fifth embodiment.

(C) Effect of the Invention Since the waste heat recovery device of the present invention has the configuration and operation as described above, (1) a high temperature (110-1
A working medium (load fluid) of 20 ° C. or higher can be obtained.

(2) Since the compression medium is water vapor, the warm water condensed in the heat exchanger does not contain solid impurities at all, so a device for removing the impurities is not required, and it occurs when the working space of the compressor is formed. It can be used directly for liquid sealing of gaps.

In addition, since it is used for liquid sealing and cooling of the shaft sealing device of the screw / rotor shaft, seizure due to temperature rise of the shaft sealing part can be prevented, and an oil / water separation device such as a conventional device using oil and refrigerant can be provided. It is unnecessary.

(3) The excess of warm water that has been condensed does not contain oil (other components), so it can be discarded as it is.

(4) Since hot water having a higher temperature and higher pressure than the sucked water vapor is injected and injected into the working space of the compressor, heat and pressure energy of the waste hot water can be effectively recovered.

(5) Refrigerant gas such as CFC and screw
Since no liquid sealing lubricating oil is used between the rotors, the operating cost is lower than that of the conventional heat recovery device of this type.

(6) Introduce high-temperature, high-pressure steam obtained by flushing part of the warm water reconstituted in the heat exchanger in the separator, economizer or flash tank into the working space after the suction deadline of the compressor. As a result, the driving power of the compressor is reduced by the amount of energy corresponding to the amount of the flash gas introduced, and energy can be saved.

(7) Even if solid impurities and the like are mixed in the waste water vapor, a flash tank is connected in the middle and the gasified medium is introduced into the compressor side, so a filter or the like is unnecessary.

Further, since the flash tank has no heat transfer surface and is a direct contact type, there is no heat loss and the equipment is inexpensive.

As a waste heat recovery device of this kind, it has a particularly remarkable effect.

[Brief description of drawings]

1 and 2 are basic system diagrams of this type of apparatus, and the system diagrams shown in FIGS. 3 to 5 are typical examples of the waste heat recovery apparatus of the present invention. Explanation of reference numerals 1 and 2 …… Liquid injection type screw compressor 3 …… Motor (driving motor) 4 …… Exchanger 5 …… Valve 6 …… Waste steam supply pipes 16 and 17 …… Injection nozzle 18 …… Load Fluid supply pipe 19 …… Discharge pipe 20 …… Flush gas supply ports 22 and 36 …… Spray pipes 24 and 25 …… Shaft sealing device Cooling line 26 …… Expansion valve 27 …… Separator 35 …… Flash tank 37… … Eliminator 39 …… Preheater.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Maehara 411 No. 411 Kamigawara, Sunakozuka, Osa-ku, Nishikanbara-gun, Niigata Prefecture (72) Inventor Shuichi Takada 11-1 Haneda-Asahi-cho, Ota-ku, Tokyo Co., Ltd. EBARA MFG. (72) Inventor Yasuo Ogawa 11-1 Haneda Asahi-cho, Ota-ku, Tokyo Ebara Mfg. Co., Ltd. (56) Reference JP-A-56-24001 (JP, A) JP-A-51-138582 (JP) , A) JP 59-107102 (JP, A) JP 58-1346 (JP, B2)

Claims (4)

[Claims] 1. Wasted steam is adiabatically compressed through a screw compressor and then a load fluid is heated through a heat exchanger for reuse in another system, while being recovered in the heat exchanger. A part of the hot water produced by water injection is injected into the working space of the compressor after the suction cutoff, and the liquid sealing of the gap of the working space that occurs when forming the space and the liquid of the shaft sealing device of the compressor In addition to providing sealing and cooling, part of the other hot water is guided to the expansion valve and separated into steam and hot water, and the steam is supplied into the working space after the suction cutoff of the compressor. A waste heat recovery device characterized in that 2. The discarded steam is supplied to a flash tank to be separated into steam and warm water, and the separated steam thus separated is sent to a screw compressor.
A part of the hot water separated in the separator was supplied to the flash tank, which was also separated into steam and hot water, and the waste steam was combined and sent to the screw compressor. The waste heat recovery device according to claim (1). 3. The screw compressor comprises low compression means and high compression means, and supplies a part of the warm water condensed in the heat exchanger to the working space of the high compression means after the suction cutoff. At the same time, the steam that has passed through the expansion valve and separated by the separator is supplied to the suction side or the working space of the high compression means, and at the same time, a portion of the hot water separated there is injected into the working space of the low compression means after shutting off. The invention according to claim (1) or (2), characterized in that it is used for liquid sealing of a gap in the working space that occurs when forming the same space and for liquid sealing and cooling of the shaft sealing device of the same means. Waste heat recovery device. 4. The hot water separated in the separator through the expansion valve is supplied to the compressor and the flash tank after preheating the load fluid passing through the heat exchanger. ), The waste heat recovery device according to item (2) or (3).