JPH0626603A - Method and apparatus for generating vapor of low temperature - Google Patents

Abstract

PURPOSE:To enable vapor to be reduce in pressure at a quite low control deviation and further to enable uniform heating to be carried out at a low temperature under a specified low pressure by a method wherein a condensing latent heat of saturated vapor at a low pressure is utilized. CONSTITUTION:Vapor generated at a vapor generating part 1 is fed to a vacuum generating part 6 through a pressure reducing part 2 having a vacuum pressure reducing valve 3 and a temperature lowering part 4 and also through an equipment 5 using vapor of low temperature and then vapor of which pressure is reduced to a value less than the atmospheric pressure at the vacuum pressure reducing valve 3 at the pressure reducing part 2 is changed to saturated vapor through a temperature reduction at the temperature lowering part 4. Then, the vapor is fed to the equipment 5 using low temperature vapor and a specified low temperature is applied to it to cause a vacuum suction and a drain recovering operation to be carried out at the vacuum generating part 6 from the vapor passed through the equipment 5 using the vapor. In addition, the vacuum pressure reducing valve 3 may act to keep the vapor pressure at the secondary side to be less than the atmospheric pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is 100 ° C., which is required in processes such as concentration, distillation, drying, temperature control and fermentation in various technical fields including the technical fields such as food industry and biochemicals. The present invention relates to a method and apparatus for generating low-temperature steam as described below.

[0002]

2. Description of the Related Art Conventionally, hot water is generally used as a heat source at a low temperature of 100 ° C. or lower in the processes of concentration, distillation, drying, temperature control, fermentation and the like in various technical fields. Although hot water has advantages such as being easy and free from overheating, it transfers heat by sensible heat, so the heat capacity per unit flow rate is small, and the temperature difference between the inlet and outlet of the device cannot be avoided. Also, if the flow rate is not increased during heat transfer, the heat transfer coefficient cannot be large and the circulation pump and the like become large. Further, there are drawbacks such that it is difficult to uniformly heat the entire apparatus, uneven heating occurs, and when the apparatus is designed to be opened to the atmosphere, corrosion is likely to occur at about 60 to 80 ° C.

In order to deal with such a problem, it is desirable to use a low pressure saturated vapor of 1 atm or less as a heating source. That is, since the temperature and pressure of saturated steam are determined one-to-one, it is possible to set the saturated steam to the desired temperature by controlling the pressure, and at low pressures of 1 atm or less, the ratio of latent heat to total heat Is large, and it is possible to eliminate the temperature difference between the inlet and outlet of the device and increase the amount of heat used effectively. Moreover, since it is a gas, it does not cause uneven heating even when used as a heating source. However, in a low-pressure saturated steam of 1 atm or less, a small pressure difference of about 0.1 atm causes a large temperature difference, and it is necessary to make the control deviation extremely small. Therefore, the low-pressure saturated steam is used as a heating source. In order to solve this problem.

[0004]

SUMMARY OF THE INVENTION The technical problem of the present invention is to enable the steam to be decompressed with a very small control deviation in order to utilize the latent heat of condensation of saturated steam at such a low pressure, whereby a constant low pressure is achieved. In order to obtain a low-temperature steam generation method and apparatus capable of performing uniform heating at a low temperature of 100 ° C. or lower.

[0005]

A low temperature steam generating method of the present invention for solving the above problems is to reduce the temperature of steam generated in a steam generating section to a low temperature through a pressure reducing section and a temperature reducing section equipped with a vacuum pressure reducing valve. Guide to the vacuum generation unit through the steam using equipment, and after the steam reduced in atmospheric pressure or less in the vacuum pressure reducing valve of the pressure reducing section to saturated steam by the temperature reduction in the temperature reducing section, by introducing to the low temperature steam using equipment, In the method in which a certain low temperature is applied to it, and from the steam that has passed through this steam-using device, vacuum suction and drain recovery are performed in the vacuum generation unit, the vacuum pressure reducing valve has a steam inlet and a steam outlet. The main valve is attached to and separated from the valve seat in the valve body, and a pressure receiving member having substantially the same pressure receiving area as that of the main valve facing the equilibrium pressure chamber is provided on the valve shaft attached to the main valve. In front of the valve that supplies to the pressure chamber Attached to the valve shaft by a spring that urges the main valve in the valve closing direction by generating an action force in the pressure receiving member in the equilibrium state by generating an action force in the direction opposite to the action force of the steam pressure applied to the main valve. Is exposed to the operation pressure chamber, and the main valve is opened and closed by the interaction with the diaphragm that biases the main valve in the opening direction by the vapor pressure after the valve, and the secondary pressure of the vacuum pressure reducing valve is increased by the set pressure by the spring. It is characterized by lowering the atmospheric pressure to obtain low-temperature steam.

Further, a low-temperature steam generator of the present invention for solving the same problem includes a steam generator for generating steam, and a depressurizer for depressurizing the steam generated in the steam generator to atmospheric pressure or less by a vacuum pressure reducing valve. Connected to a temperature reducing section for reducing the temperature of the steam reduced in the pressure reducing section to saturated steam and a discharge system for the steam discharged from the temperature reducing section through a device using low temperature steam, for vacuum suction and drain of the discharged steam. The vacuum pressure reducing valve is equipped with a vacuum generating part for recovery, and the main valve can be attached to and detached from a valve seat in the valve body, which has a steam inlet communicating with the steam generating part and a steam outlet communicating with the temperature reducing part. A valve for keeping the main valve in the equilibrium state in the equilibrium pressure chamber by installing a pressure receiving member having a pressure receiving area substantially the same as the main valve facing the equilibrium pressure chamber on the valve shaft attached to the main valve. Connect the flow path to supply the front vapor pressure and close it to the main valve. Attached to the spring and the valve shaft for urging comprises a diaphragm which faces the operating pressure chamber,
It is characterized in that an operating mechanism for opening and closing the main valve is constituted by the interaction between the valve post vapor pressure supplied to the operating pressure chamber and the spring.

[0007]

[Function] Since the steam generated in the steam generating unit is vacuum-sucked in the vacuum generating unit on the discharge side of the low temperature steam-using device, the pressure is reduced to below atmospheric pressure by the vacuum pressure reducing valve in the pressure reducing unit, and further the temperature reducing unit is used. After being reduced in temperature to saturated steam, it is led to equipment using low-temperature steam. Therefore, in steam-using equipment, low-pressure saturated steam of 1 atm or less can be used as a low-temperature heating source. In this case, since the temperature and the pressure of the saturated steam are determined one-to-one, it is possible to set the saturated steam to the desired temperature by controlling the pressure. Since the ratio is large, the amount of heat used effectively is large, and since it is heat transfer for solidification, the heat transfer coefficient can be one digit larger than that for hot water. Further, since it is a gas, it does not cause uneven heating even when used as a heating source.

Further, in low-pressure saturated steam of 1 atm or less, even if a slight pressure difference causes a large temperature difference, it is necessary to make the control deviation extremely small. However, in the vacuum pressure reducing valve, before the valve for supplying to the equilibrium pressure chamber. Since the main valve is kept in equilibrium by the vapor pressure, the equilibrium is maintained regardless of the fluctuation of the pre-valve vapor pressure, and the opening / closing of the main valve is controlled according to the post-valve vapor pressure to control the vacuum pressure reducing valve. It is possible to obtain the low temperature steam by lowering the secondary side pressure of the above from the atmospheric pressure by the pressure set by the spring. When saturated steam is generated by such control, the steam can be decompressed with a very small control deviation, and the saturated steam can be accurately set to a desired temperature.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the overall structure of a low temperature steam generator according to the present invention, and FIG. 2 shows the structure of a vacuum pressure reducing valve used in the low temperature steam generator. The low-temperature steam generator shown in FIG. 1 is basically a steam generator 1 including a boiler and an accumulator for generating steam.
A decompression unit 2 for decompressing the steam generated in the steam generation unit 1 to below atmospheric pressure by a vacuum decompression valve 3, and the decompression unit 2
Is connected to a temperature reducing section 4 for reducing the temperature of the steam reduced in pressure to saturated steam and a discharge system for the steam discharged from the temperature reducing section 4 through a low temperature steam using device 5, and vacuum suction of the discharged steam and drain recovery And a vacuum generating unit 6 for performing. In FIG. 1, reference numeral 7 indicates a makeup water source, and 8 indicates a discharge system leading to a recovery tank and the like.

The vacuum pressure reducing valve 3 operates so as to keep the steam pressure on the secondary side (the device 5 using low-temperature steam) constant below atmospheric pressure. As shown in detail in FIG. A valve opening / closing mechanism 11 that cuts off the flow path, an acting force balancing mechanism 12 for balancing the acting force acting on the main valve, and an operating mechanism 13 that opens and closes the main valve according to the steam pressure on the secondary side. Is equipped with.

A valve opening / closing mechanism 11 in the vacuum pressure reducing valve.
Is provided with a valve body 15 having a steam inlet 16 connected to the steam generating section 1 and a steam outlet 17 communicating with the temperature reducing section 4, and a main valve 19 is connected to a valve seat 18 in the valve body 15. A valve shaft 20 is attached to the main valve 19 by being separated from each other.

Further, the acting force balancing mechanism 12 is provided with a case 22 connected to the valve main body 15 so as to surround the valve shaft 20, and a balancing pressure chamber 23 is formed in the case 22. There is. The equilibrium pressure chamber 23 includes the valve shaft 20 and the main valve 1.
9 is connected to the steam inlet 16 side by a flow path 24 penetrating the inside of the valve 9, and in order to partition the equilibrium pressure chamber 23 in the case, a pressure receiving member 25 is mounted on the valve shaft 20 and the periphery of the pressure receiving member 25 is attached. Balancing bellows 2 with one end attached to
The other end of 6 is attached to the connecting portion between the case 22 and the valve body 15. The pressure receiving member 25 facing the equilibrium pressure chamber has substantially the same pressure receiving area as the main valve, and the pressure receiving member 25 is closed by the pre-valve vapor pressure supplied into the equilibrium pressure chamber 23 through the flow path 24. The acting force in the direction is generated, and this acting force and the acting force in the valve opening direction due to the vapor pressure acting on the main valve 19 are balanced. Therefore, the acting force due to the vapor pressure on the main valve does not affect the operating force for opening and closing the valve.

On the other hand, according to the steam pressure on the secondary side, the main valve 1
The operating mechanism 13 for opening and closing 9 has a spring 28 for urging the main valve 19 in the valve closing direction and a diaphragm 31 inside.
And a pressure sensitive tank 30 in which the operation pressure chamber 32 is formed by partitioning in the lower half portion. The spring 28 is used for the column 3 fixedly installed on the pressure sensitive tank 30.
It is mounted elastically between the spring seat body 35 on the No. 4 and the spring seat body 36 attached to the shaft rod 38 penetrating the pressure sensitive tank 30. The pressure sensitive tank 30 is attached to the lower end of the case 22 and is fixed to the diaphragm 31.
Is connected to the valve shaft 20 via a coupling 39, the operating pressure chamber 32 is connected to the secondary side of the vacuum pressure reducing valve 3 via a needle valve 41 and a pressure sensitive tank 42 by a pressure guiding tube 40, and a pressure sensing is performed by a diaphragm. The back pressure chamber 43 defined in the upper half of the tank 30 is open to the atmosphere. This operating mechanism 13
Generates an actuation force in the valve opening direction on the diaphragm 31 by the post-valve vapor pressure introduced into the operation pressure chamber 32 below the atmospheric pressure, and the interaction between this actuation force and the biasing force of the spring 28 causes the main valve 19 to move. To open and close.

The temperature reducing unit 4 for reducing the temperature of the vapor decompressed in the decompression unit 2 to saturated vapor is used to vacuum the drain, which is pumped from the drain tank 45 in the vacuum generating unit 6 by the pump 46, by a nozzle (not shown). It is jetted out into the pipe 47 on the secondary side of the pressure reducing valve 3, and in the dehumidification tank 48 connected to the pipe 47, the water jetted from the nozzle is sufficiently brought into contact with the steam and separated, whereby the steam This is to reduce the temperature. In the temperature reduction tank 48, while the steam descends and passes through a large number of perforated plates 49 provided in the inflow side flow passage, the steam is brought into contact with the water jetted from the nozzle so that the large number of perforated plates provided in the discharge side flow passage are provided. While climbing through the plate 50,
A temperature reducing tank 4 configured to separate excess water drops.
A discharge pipe 51 of the separated and removed jet water is connected to the lower bottom of the pipe 8. When the steam is depressurized in the depressurizing unit 2, the steam becomes superheated steam due to isenthalpic change,
By the above-mentioned temperature reduction, the steam can be saturated steam at that pressure.

The low temperature section 4 is connected to a low temperature steam using apparatus 5 for performing low temperature heating at 100 ° C. or lower in the steps of concentration, distillation, drying, temperature control, fermentation, etc., and the steam using apparatus 5 is used.
A vacuum generation unit 6 for performing vacuum suction and drain recovery of the exhaust steam is connected to the exhaust system pipe 54 for the steam exhausted through the above. The vacuum generator 6 introduces the drain, which is pumped from the drain tank 45 by the pump 46, into the jet pump 55 as driving water and ejects it from the nozzle 56, and the ejection of the driving water causes the drain suction port 5 to flow.
7 is used to generate a negative pressure, which causes vacuum suction from the discharge system of the steam-using device 5 to lower the pressure on the secondary side of the decompression unit 2 and at the same time discharge pipe 54 of the low-pressure steam-using device 5.
And the steam and drain from the discharge pipe 51 of the temperature reduction tank 48 are collected in the drain tank 45 together with the driving water.

The temperature of the circulating drive water returned from the drain tank 45 to the drain tank 45 via the pump 46 and the jet pump 55 is preferably set to a temperature slightly lower than the saturated steam temperature in the steam-using device 5, for that reason. The temperature detector 60 provided in the drain tank 45 detects the temperature of the driving water and controls the makeup water valve 61 to introduce low-temperature makeup water. Thereby, the degree of vacuum in the jet pump 55 can be efficiently increased. Further, the drain tank 45 is provided with a water level detector 62, and by controlling the driving of the drainage pump 63 by the output thereof, the drainage system for discharging the excess water to the recovery tank or the like so that the water level is always within a certain range. I am trying to make it flow out to 8. Further, an overflow pipe 64 is attached to the drain tank 45.

In the low temperature steam generator having the above structure, the steam generated in the steam generating section 1 is guided to the vacuum generating section 6 through the vacuum pressure reducing valve 3 and the temperature reducing section 4 and the low temperature steam using device 5. However, since the vacuum generation unit 6 on the discharge side of the low-temperature steam using device 5 is performing vacuum suction by the jet pump 55, the pressure is reduced to below atmospheric pressure by the vacuum pressure reducing valve 3 of the pressure reducing unit. The steam is made into saturated steam by reducing the temperature in the temperature reducing section 4, and then the low temperature steam using device 5 is used.
Be led to. Therefore, in the steam-using device 5, 1
Low-pressure saturated steam at atmospheric pressure or lower can be used as a low-temperature heating source at 100 ° C. or lower. The steam that has passed through the steam using device 5 is discharged by vacuum suction in the vacuum generating unit 6, and is simultaneously drained and recovered.

Since the temperature and the pressure of the saturated steam used as the above-mentioned heating source are determined one-to-one, it is necessary to set the saturated steam to the desired temperature and use it for heating by controlling the pressure in the vacuum pressure reducing valve 3. In addition, at low pressure of 1 atm or less, latent heat occupies a large proportion of the total amount of heat, the amount of effective heat is large, and since it is solidification heat transfer, the heat transfer coefficient should be one digit larger than that of hot water. You can Also,
Since it is a gas, it does not cause uneven heating even when used as a heating source.

Further, in a low-pressure saturated vapor of 1 atm or less, even if a slight pressure difference causes a large temperature difference, it is necessary to make the control deviation extremely small, but in the vacuum pressure reducing valve 3, it is supplied to the equilibrium pressure chamber 23. Since the main valve 19 is held in the equilibrium state by the valve front vapor pressure, the equilibrium state is maintained regardless of the fluctuation of the valve front vapor pressure, and the main valve 19 is stably opened / closed according to the valve post vapor pressure. Is controlled to lower the secondary pressure of the vacuum pressure reducing valve 3 below the atmospheric pressure by the pressure set by the spring 28 to obtain low-temperature steam. When saturated steam is generated by such control, the steam can be decompressed with a very small control deviation, and the saturated steam can be accurately set to a desired temperature.

[0020]

According to the method and apparatus of the present invention detailed above, in order to utilize the latent heat of condensation of saturated vapor at low pressure, the saturated vapor can be set to a desired temperature by controlling the pressure. Further, the proportion of latent heat in the total amount of heat is large, which eliminates the temperature difference between the inlet and outlet of the device, and at the same time has a large amount of heat used effectively, and since it is a gas, it does not cause uneven heating even when used as a heating source. Further, since the vacuum pressure reducing valve equipped with the action force balancing mechanism for balancing the action force acting on the main valve is used to reduce the pressure of the steam,
The steam can be decompressed with a very small control deviation, which makes it possible to carry out uniform heating at a desired temperature at a low temperature such as 100 ° C. or lower.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an overall configuration of a low-temperature steam generator according to the present invention.

FIG. 2 is a sectional view of a vacuum pressure reducing valve used in the low-temperature steam generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 steam generating part, 2 pressure reducing part, 3 vacuum reducing valve, 4 temperature reducing part, 5 low temperature steam using equipment, 6 vacuum generating part, 13 operating mechanism, 15 valve body, 16 steam inlet, 17 steam outlet, 18 valve seat, 19 main valve, 20 valve shaft, 23 equilibrium pressure chamber, 24 flow path, 25 pressure receiving member, 28 spring, 31 diaphragm, 32 operating pressure chamber.

Claims (2)

[Claims] 1. The steam generated in the steam generating section is led to the vacuum generating section via a low temperature steam-using device through a pressure reducing section and a temperature reducing section equipped with a vacuum pressure reducing valve, and the vacuum pressure reducing valve in the pressure reducing section has a large value. The steam depressurized below atmospheric pressure is made into saturated steam by reducing the temperature in the temperature reducing section, and then it is introduced into the equipment using low temperature steam, and a certain low temperature is applied to it. In the method of performing vacuum suction and drain recovery in the above, in the above vacuum pressure reducing valve, a main valve is installed oppositely to a valve seat in a valve body having a steam inlet and a steam outlet, and A pressure-receiving member having substantially the same pressure-receiving area as the main valve facing the equilibrium pressure chamber is installed on the valve shaft attached to the equilibrium pressure chamber, and the vapor pressure before the valve is supplied to the equilibrium pressure chamber. Action force due to Is generated and held in equilibrium,
The main valve interacts with a spring that biases the main valve in the valve closing direction and a diaphragm that is attached to the valve shaft and faces the operating pressure chamber and biases the main valve in the valve opening direction by the vapor pressure after the valve. The low-temperature steam generation method is characterized in that the low-pressure steam is obtained by opening and closing the valve, and lowering the secondary side pressure of the vacuum pressure reducing valve below the atmospheric pressure by the set pressure by the spring. 2. A steam generating section for generating steam, a decompression section for decompressing the steam generated in the steam generating section to atmospheric pressure or less by a vacuum decompression valve, and a saturated steam by decompressing the steam decompressed in the decompression section. And a vacuum generation unit connected to an exhaust system for the steam discharged from the temperature reduction unit through a device using low-temperature steam and performing vacuum suction and drain recovery of the exhaust steam. Is a valve seat in the valve body that has a steam inlet communicating with the steam generating section and a steam outlet communicating with the temperature reducing section. A pressure receiving member having substantially the same pressure receiving area as that of the main valve facing the equilibrium pressure chamber is provided, and the equilibrium pressure chamber is connected to a flow path for supplying a pre-valve vapor pressure for keeping the main valve in an equilibrium state. Operated by attaching to the valve, a spring that biases it toward the valve and the valve shaft. A low-temperature steam generator comprising a diaphragm facing a pressure chamber, and an operation mechanism configured to open and close a main valve by an interaction between a post-valve steam pressure supplied to the operation pressure chamber and the spring.