JP5087667B2 - Saturated steam generator - Google Patents

Description

  The present invention relates to a saturated steam generator, and more particularly to a saturated steam generator that generates saturated steam using superheated steam as a heating source.

In hospitals, etc., for sterilization of objects to be sterilized such as therapeutic bandages, scalpels, forceps, and surgical gowns, the sterilization chamber containing the objects to be sterilized is usually pressurized with saturated steam to a predetermined pressure and temperature. A steam sterilization method is used in which is maintained for a certain period of time.
Among steam sterilizers used in such steam sterilization methods, large steam sterilizers that can sterilize a large amount of materials to be sterilized are usually supplied with saturated steam from a large boiler provided in a hospital or the like. The

However, since large boilers are accompanied by the burning of kerosene, they are not appropriate from the standpoint of environmental protection, and noise during driving is also a problem.
Therefore, as shown in FIG. 5, the present inventors can reduce the size of the heating source in the saturated water vapor generator that generates saturated water vapor, and are environmentally friendly and can greatly reduce the operation sound. The inventors have devised a saturated steam generator that can also reduce running costs.

An outline of the structure of the saturated water vapor generator shown in FIG. 5 will be described.
The saturated steam generator includes a heat storage tank 10 and a saturated steam generator tank 12.
In the heat storage tank 10, a heat storage unit 11 made of a solid heat storage material and a liquid heat storage material is provided. A heat transfer tube 16 is disposed in the heat storage unit 11, and water is supplied into the heat transfer tube 16 by the pump 14. The water that has passed through the heat transfer tube is superheated and is supplied as superheated steam into the heater 20 disposed in the saturated steam generation tank 12.
On the other hand, the water that is the source of saturated water vapor supplied into the evaporation tank 18 is treated water that has undergone water treatment such as microfiltration and deionization treatment, and is supplied to the evaporation tank 18 through the pipe 8 by the pump 9. Has been.

The structure in the conventional heat storage tank is shown in FIG.
The heat storage tank 10 is provided with the above-described heat storage unit 11 and an electric heater 15 that is provided so as to pass through the heat storage unit 11 and heat the heat storage unit 11.
Here, each electric heater 15 shown is provided so that the whole can be heated over the water inlet side of the heat transfer tube 16 and the superheated steam outlet side.
The heat storage tank 10 is heated by energizing the electric heater 15 mainly with inexpensive late-night power.
When the midnight power is energized for about 10 hours, the superheated steam at about 500 ° C. is stably obtained from the heat storage tank 10 for about 7 hours and 8 hours.

JP-A-1-193502 JP-A-3-282101 JP 2001-104456 A Japanese Patent Laid-Open No. 10-57453 JP-A-9-89201

  In the saturated steam generator having the above-described structure, the water supply to the heat storage tank is performed by turning the pump on and off. However, the overshoot and undershoot of the generation of saturated steam become large only by the pump on / off control. Therefore, there is a problem that stable generation of saturated water vapor is desired.

  In addition, water supply to the heat storage tank and supply of treated water to the saturated steam generation tank were performed by separate pumps, so there are many moving parts, and there is a problem that the maintainability should be improved. There are also issues such as the reduction of the number of parts, etc., and the problem that the treated water overflowed in the conventional saturated steam generation tank is drained as it is, and the treated water is wasted and the running cost is high. It was.

  Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a saturated steam generator capable of stably generating saturated steam.

The present invention has the following configuration in order to solve the above problems.
That is, according to the saturated steam generator according to the present invention, a heat storage tank and a saturated steam generation tank are provided, and water is heated in the saturated steam generation tank by superheated steam obtained by overheating in the heat storage tank. A heater that heats the solid heat storage material and the liquid heat storage material in a heat storage section that is filled with a solid heat storage material and a liquid heat storage material provided in the heat storage tank. And a heat transfer pipe that superheats the water passing through it to form superheated steam, a water supply pump for supplying water to the heat transfer pipe is provided, and the saturated steam pressure generated in the saturated steam generation tank is A pressure measuring means for measuring is provided, a saturated steam pressure value measured by the pressure measuring means is input, and a control means for controlling the feed water pump is provided so that the saturated steam pressure value is always constant. It is characterized by being.
By adopting this configuration, a more stable saturated water vapor output can be expected.

  Further, the water supply pump branches downstream in order to supply water to the heat transfer pipe and the saturated steam generation tank, and the water supply pipe is formed by connecting the branch destinations to the heat transfer pipe and the saturated steam generation tank, respectively. Therefore, the number of water supply pumps, which are operating parts, is reduced from the conventional one to one, and maintenance is facilitated and the number of parts can be reduced.

According to the saturated steam generator according to the present invention, since the saturated steam pressure value measured by the pressure measuring means is input, and the control means for controlling the feed water pump based on the saturated steam pressure value is provided, it is more stable. The output of saturated water vapor can be expected.
According to claim 2, since only one water supply pump that feeds water to the heat transfer tube and the saturated steam generation tank is provided in common, the number of water supply pumps that are operating parts is reduced from the conventional one to one. Therefore, maintenance is facilitated and the number of parts can be reduced.

It is a basic diagram explaining an example of the saturated steam generator which concerns on this invention. It is sectional drawing for demonstrating the structure of the thermal storage tank used for FIG. It is explanatory drawing explaining the state of filling of the thermal storage material in a thermal storage part. It is sectional drawing which shows other embodiment in the structure of a thermal storage tank. It is an approximate line figure explaining the conventional saturated steam generator. It is sectional drawing for demonstrating the structure of the thermal storage tank used for the conventional saturated steam generator.

FIG. 1 is a schematic diagram showing an example of a saturated steam generator according to the present invention. A saturated water vapor generator 30 shown in FIG. 1 includes a heat storage tank 32 and a saturated water vapor generation tank 34.
First, the water supply system will be described.
The water to be superheated in the heat storage tank 32 of the saturated steam generator 30 and the water to be saturated steam in the saturated steam generator 34 are both pure water that has been subjected to microfiltration, deionization processing, etc., RO (reverse treated water such as osmosis) and soft water.
Only one water supply source pipe 35 for supplying treated water is provided for the heat storage tank 32 and the saturated water vapor generation tank 34.

The water supply source pipe 35 is connected to the storage tank 36, and the supplied treated water is temporarily stored here.
A water supply pipe 38 for supplying water from the storage tank 36 to both the heat storage tank 32 and the saturated water vapor generation tank 34 is connected. A strainer 39 is provided in the middle of the water supply pipe 38.
A water supply pump 40 is provided in the water supply pipe 38, and treated water is transferred to the heat storage tank 32 and the saturated water vapor generation tank 34 by the water supply pump 40.

The water supply pipe 38 branches into two, a heat storage tank side water supply pipe 42 that goes to the heat storage tank 32 and a generation tank side supply pipe 44 that goes to the saturated water vapor generation tank 34 on the downstream side of the water supply pump 40.
The heat storage tank side water supply pipe 42 is provided with a motor valve 45 in the middle, and the tip is connected to a heat transfer pipe 76 (see FIGS. 2 and 4) in the heat storage tank 32.
The generation tank side supply pipe 44 is provided with a motor valve 47 in the middle, and the tip is connected to the saturated water vapor generation tank 34.

Next, a steaming system for superheated steam superheated in the heat storage tank 32 will be described.
As described above, the heat storage tank side water supply pipe 42 to the heat storage tank 32 is connected to one end (reference numeral 76 a in FIG. 2) of the heat transfer pipe 76 in the heat storage tank 32, and the treated water enters the heat transfer pipe 76. Supplied.
The treated water that passes through the heat transfer tube 76 is superheated by the heat storage unit 72 to become superheated steam.
A supply pipe 46 for supplying superheated steam to the saturated steam generation tank 34 is connected to the other end of the heat transfer pipe 76 (reference numeral 76b in FIG. 2).

The supply pipe 46 is connected to one end of the heating pipe 48 in the saturated steam generation tank 34 and supplies superheated steam into the heating pipe 48.
The heating pipe 48 is disposed inside the saturated steam generation tank 34, and a small hole is formed on the outer surface, and superheated steam can be ejected from the small hole. The superheated steam ejected from the heating pipe 48 directly heats the treated water stored in the saturated steam generation tank 34 to evaporate the treated water and generate saturated steam.
In addition, the superheated steam spouted in the treated water stored in the saturated steam generation tank 34 is drained as a result of heat exchange and returned to the water.

Next, the supply / discharge system of the treated water to the saturated steam generation tank 34 will be described.
As described above, the generation tank side water supply pipe 44 is connected to the saturated steam generation tank 34 and supplies treated water into the saturation steam generation tank 34.
The treated water heated by the superheated steam ejected from the heating pipe 48 is converted to saturated steam and steamed from the steam feeding pipe 50.
Note that an emergency drain pipe 51 is connected to the saturated steam generation tank 34.

If the amount of treated water stored in the saturated water vapor generation tank 34 exceeds a predetermined amount of water, it is not preferable in terms of the efficiency of water vapor generation. Therefore, an overflow pipe 52 is provided for discharging the water when the amount of water exceeds the predetermined amount.
The overflow pipe 52 is provided with a valve 54 and a drain trap 56 in the middle, and the tip is connected to a storage tank heat transfer pipe 58 disposed in the storage tank 36. The storage tank heat transfer tube 58 is provided so as to be immersed in the treated water stored in the storage tank 36, and exchanges heat between the overflowed water and the water in the storage tank 36. That is, the treated water in the generation tank 34 overflowed by the water in the storage tank 36 is cooled, and the treated water stored in the storage tank 36 by the heat of the overflowed treated water passing through the storage tank heat transfer pipe 58. Is heated. In this manner, the treated water in the storage tank 36 is heated, so that the thermal efficiency can be increased and the treated water in the storage tank 36 can be degassed.

The front end of the storage tank heat transfer pipe 58 is opened in the storage tank 36 so that the treated water in the overflowing generation tank 34 and the treated water supplied from the water supply source pipe 35 are mixed. . For this reason, the treated water in the generation tank 34 that has overflowed can be used again for superheated steam or saturated steam.
A pressure relief valve 60 is provided between the overflow pipe 52 and the heat storage tank side water supply pipe 42.

The saturated steam generated in the saturated steam generation tank 34 is output through the steam supply pipe 50.
Although not shown in the drawings, it is preferable to provide a known technique such as a baffle or a cyclone between the saturated steam generation tank 34 and the steam supply pipe 50 as a means for preventing entrainment of droplets. is there. However, the splash entrainment prevention means is not limited to baffles or cyclones.

In addition, the steam supply pipe 50 is provided with a drain trap 69 on the way to trap the drain condensed in the steam supply pipe 50. A drain pipe 71 for returning the drain trapped by the drain trap 69 into the water storage tank 36 is branched from the steam supply pipe 50.
The drain pipe 71 is connected to the middle part of the overflow pipe 52 and opens in the storage tank 36 via a storage tank heat transfer pipe 58 disposed in the storage tank 36.
By setting it as such a structure, the temperature in the storage tank 36 can be raised, a thermal efficiency can be raised, and deaeration can be performed. On the other hand, drain generated by condensation in the steam supply pipe 50 is returned to the storage tank 36 and can be reused by using it as superheated steam or saturated steam, so that the treated water can be used effectively and not wasted. can do.

Next, a control system for generating saturated water vapor will be described.
Water quality detecting means 62 and 64 for detecting the quality of the treated water are provided in the storage tank 36 and the saturated water vapor generating tank 34 where the treated water is stored.
An example of the water quality detection means 62, 64 is an electrode switch having two electrodes 62a, 62b and 64a, 64b, respectively. The electrode switch detects the resistance value (electric conductivity) of the treated water, and determines that the impurity increases as the resistance value decreases.
The water quality detection means 62 and 64 are connected to the control unit 66, and the control unit 66 determines the water quality.
The controller 66 measures the resistance value between the two electrodes, and when it is determined that the resistance value has decreased and the water quality has deteriorated, the operation of the saturated steam generator can be stopped. For this reason, the water quality of the saturated water vapor can be maintained at a certain level.

Moreover, the pressure gauge 70 provided in the steam supply pipe 50 that outputs saturated steam from the saturated steam generating tank 34 is connected to the control unit 66, and the pressure of the generated saturated steam is input to the control unit 66 and fed back. Control is performed.
The control unit 66 controls the feed water pump 40 via the inverter 68 so that saturated steam with a constant pressure is always output based on the measured saturated steam pressure.
As described above, the control unit 66 of the present embodiment serves as both the first control means and the second control means in the claims, and maintains the water quality maintenance control and the output saturated water vapor pressure. However, it is also possible to provide two control units each having different functions.
Further, in addition to controlling based on the pressure of the saturated steam generated as described above, the control unit 66 measures the steam amount or temperature of the generated saturated steam, and controls the feed pump 40 based on these measured values. You may control.
Control of the water supply pump 40 is not limited to the inverter 68, and the control valve may be moved by a motor or the orifice may be adjusted.

The heat storage tank 32 used in the saturated steam generator described above will be described with reference to FIG. Hereinafter, although an embodiment using an electric heater will be described as an example of a heater for heating the heat storage tank, the heater for heating the heat storage tank is not limited to the electric heater. In addition to the electric heater, a steam heater, an oil heater, or the like can be considered.
The heat storage tank 32 shown in FIG. 2 is supplied with an electric heater 74 for heating the heat storage material and treated water in a heat storage portion 72 filled with a heat storage material in which a solid heat storage material and a liquid heat storage material are mixed. A heat pipe 76 is provided. Furthermore, the outer peripheral surface of the heat storage unit 72 is covered with a heat insulating material 78 to prevent heat dissipation from the heat storage unit 72.
As the heat storage material filled in the heat storage unit 72, a solid heat storage material and a liquid heat storage material having different particle diameters are used, and the solid heat storage materials having different particle diameters are small particles in the gaps between the large heat storage solid heat storage materials. A solid heat storage material having a diameter is filled in, and a liquid heat storage material is filled in a gap between the solid heat storage material having a large particle size and the solid heat storage material having a small particle size.

The state of filling of the heat storage material in the heat storage unit 72 is shown in FIG.
FIG. 3A shows a state in which the solid heat storage material 77a having a large particle size and the solid heat storage material 77b having a small particle size are filled with two types of solid heat storage material and the liquid heat storage material 80, A small-particle-size solid heat storage material 77b enters and fills a gap between the large-particle-size solid heat storage material 77a, and a liquid heat-storage material 80 is filled in the gap between the solid-state heat storage materials 77a and 77b.

FIG. 3B shows a state of the heat storage unit 72 filled with the solid heat storage material having three kinds of particle sizes and the liquid heat storage material 80. This solid heat storage material includes a solid heat storage material 77a having a large particle size, a solid heat storage material 77b having a small particle size, and a solid heat storage material 77c having a medium particle size that is an intermediate particle size between the solid heat storage materials 77a and 77b. The solid heat storage material 77c having a medium particle size enters and fills the gap between the solid heat storage materials 77a having a diameter, and the solid heat storage material 77b having a small particle size enters the gap between the solid heat storage materials 77a and 77c. Yes. Furthermore, the liquid heat storage material 80 is filled in the gaps between the filled solid heat storage materials 77a, 77b, and 77c.
In this way, as shown in FIGS. 3 (a) and 3 (b), solid heat storage materials having different particle diameters are filled so that a solid heat storage material having a small particle size enters a gap between solid heat storage materials having a large particle size, In the heat storage unit 72 in which the liquid heat storage material is filled in the gap between the solid heat storage materials, the filling density of the solid heat storage material and the liquid heat storage material is filled with the solid heat storage material and the liquid heat storage material having substantially the same particle diameter. Compared to the density, the heat storage amount and the heat conduction to the heat transfer tube 76 can be improved.

As the solid heat storage material shown in FIGS. 3 (a) and 3 (b), one or two or more kinds of particles selected from magnesia, magnetite, silica and alumina can be suitably used. As the liquid heat storage material, nitrate is used. Can be suitably used. Nitrate is solid at room temperature, but melts and becomes liquid at 142 ° C or higher.
As an example of the composition of the heat storage material forming the heat storage unit 42, 55% large particle size magnesia, 25% small particle size magnesia, and 20% nitrate are preferable.

The electric heater 74 provided in the heat storage unit 42 includes three electric heaters so as to have a total electric capacity of 27 kW.
As a specific example, if the power capacity usable in the entire heat storage tank 32 is 27 kW, the electric heater provided in the heat storage tank 32 includes one 15 kW electric heater 74a and six kW electric heaters 74b and 74c. Make sure that two are provided.
Among them, the 15 kW electric heater 74 a having the highest electric capacity is provided so as to be positioned on the inlet side (reference numeral 76 a side) of the heat transfer tube 76, and the remaining 6 kW electric heaters 74 b and 74 c are each of the heat transfer tube 76. It is provided so as to heat the midway part and the discharge port side (reference numeral 76b).
As described above, by arranging the electric heater having the highest temperature on the introduction port side of the heat transfer tube 76, the introduction port side of the heat transfer tube 76 can be preferentially heated. That is, during the operation of generating saturated water vapor, the temperature on the inlet side of the heat transfer tube 76 particularly decreases, so that only the inlet side can be reheated with priority.

In addition, other embodiment about arrangement | positioning of an electric heater is described based on FIG.
That is, the arrangement of the electric heaters 74 in the above-described embodiment is such that the total power consumption is the same as that of the conventional one, and the distribution is inclined and distributed so that the heat transfer tube 76 inlet side becomes larger.
However, it is also preferable to use different electric heaters for heat storage using midnight power and for reheating the inlet side where the temperature drop is significant.
In other words, the electric heater 82 is arranged to store heat using midnight electric power by using three 9 kW electric heaters 82a, 82b, and 82c, and to heat only the inlet side separately from the three electric heaters. A heater 82d is provided.
The electric capacity of the electric heater 82d that heats only the inlet side is preferably 27 kW so that all the electric power that can be used for the entire heat storage tank 32 can be used. In other words, when only the electric heater 82d is energized during or after the generation of saturated steam, reheating can be focused on the inlet side where the temperature drop is particularly significant.

Furthermore, as another embodiment of the arrangement of the electric heaters, three electric heaters having the same electric capacity may be arranged on the introduction port side, the intermediate portion, and the discharge port side, and may be controlled independently (not shown). )
Even in such a case, only the inlet side can be heated with priority.

By using the electric heaters 74 and 82, the heat storage material can be heated by electricity, which is clean energy, and the heat storage material can be heated by low-cost midnight power, so that clean and inexpensive superheated steam can be obtained. it can.
Here, an ordinary boiler that can continuously discharge superheated steam for 8 hours or more, that is, a boiler that cooks fuel such as heavy oil, requires additional equipment such as a fuel tank, a fuel pipe, an air duct, and an exhaust gas duct. , Its size becomes extremely large. In this respect, in the heat storage tank 32 shown in FIGS. 2 and 4, since the electric heaters 74 and 82 are employed as the heaters for the heat storage material, no additional equipment such as a fuel tank can be required, and the heat storage tank is extremely compact. It can be.

  In the embodiment described above, the superheated steam is directly brought into contact with the treated water stored in the saturated steam generation tank 34 (bubbling heating), but the superheated steam is directly applied to the treated water for generating saturated steam. You may make it heat by exchanging heat through the tube for a heating, without making it contact (indirect heating).

Moreover, the specific numerical value of the electric capacity of the heater according to the above-described embodiment has been described only as an example, and is not limited to the numerical value heater described above.
Furthermore, the water quality detecting means is not limited to the electrode switch, and any means capable of detecting the water quality may be used.

DESCRIPTION OF SYMBOLS 30 Saturated steam generator 32 Heat storage tank 34 Generation tank 35 Water supply main pipe 36 Storage tank 38 Water supply pipe 39 Strainer 40 Water supply pump 42 Heat storage tank side pipe 44 Saturated steam generation tank side pipe 45, 47, 60 Valve 46 Supply pipe 48 Heating pipe 50 Steam supply pipe 51 Drain pipe 52 Overflow pipe 56, 69 Drain trap 58 Reservoir heat transfer pipe 62, 64 Water quality detection means 66 Control unit 68 Inverter 71 Drain pipe 72 Heat storage part 74, 82 Electric heater 76 Heat transfer pipe 77a, 77b, 77c Solid heat storage material 78 Heat insulation material 80 Liquid heat storage material

Claims (2)

A saturated steam generator that includes a heat storage tank and a saturated steam generation tank, and generates saturated steam by heating water in the saturated steam generation tank with superheated steam obtained by overheating in the heat storage tank,
In a heat storage section formed by filling a solid heat storage material and a liquid heat storage material provided in the heat storage tank, a heater for heating the solid heat storage material and the liquid heat storage material, and water passing through the superheated superheated steam And a heat transfer tube
A water supply pump for supplying water to the heat transfer pipe is provided;
Pressure measuring means for measuring the saturated steam pressure generated in the saturated steam generation tank is provided,
A saturated steam generator, comprising: a control means for inputting the saturated steam pressure value measured by the pressure measuring means and controlling the feed water pump so that the saturated steam pressure value is always constant. . The water supply pump is
In order to supply water to the heat transfer pipe and the saturated steam generation tank, the water is branched downstream, and one of the branch destinations is provided in the water supply pipe connected to the heat transfer pipe and the saturated steam generation tank, respectively. The saturated water vapor generator according to claim 1.

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