JPH0666403A - Steam heater - Google Patents

Abstract

PURPOSE:To obtain a steam heater in which a heating temperature is not varied even if a load to be heated is altered. CONSTITUTION:A steam passage 2 for supplying heating steam is connected to a heating vessel 1. A steam control valve 3 is mounted in the passage 2. Pressure detectors 20, 22 are respectively mounted at primary and secondary sides of the vessel 1, and connected to an arithmetic unit 32 through a differential pressure transmitter 23. An ejector type vacuum pump 4 is connected at a lower part of the vessel. The pump 4 has an ejector 5, a tank 8 and a circulating pump 6. A temperature sensor 17 is mounted in the tank 8. A cooling water supply passage 15 is connected to the tank 8 through a cooling water control valve 16. The sensor 17 and the actuator 18 of the valve 16 are connected to a second controller 21. The controller 21 is connected to the unit 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam heating device for efficiently heating a material to be heated with steam of about 100 ° C. while sucking the inside of a heating container with a vacuum pump. In chemistry, food, medical products factories, etc., there are many applications in which an object to be heated must be heated at a relatively low temperature of about 100 ° C in order to maintain product quality. Most of the heating is conventionally performed using warm water. However, since hot water has a small amount of heat and tends to cause uneven heating, and since relatively large-scale equipment is required to manufacture and store hot water, recently, low-pressure steam is used to obtain about 100 ° C. Is being heated.

[0002]

2. Description of the Related Art As an example of conventional low-temperature steam heating, for example, there is one disclosed in Japanese Patent Laid-Open No. 1-277101. This has a pressure reducing valve on the primary side of the heating container,
A vacuum vapor generator connected to an ejector-type vacuum pump that allows the suction pressure generated in the ejector section to be set arbitrarily by controlling the temperature of the fluid that passes through the ejector nozzle on the secondary side. , The pressure reducing valve is equipped with an actuator, and a control signal is sent to the cooling water control valve based on this setting signal and the tank water temperature, as well as sending a setting signal to this actuator. By making the suction pressure generated in the ejector section equal to the set pressure of the pressure reducing valve, steam is not excessively supplied to the heating container through the pressure reducing valve, and efficient low temperature steam heating without steam loss is possible. It will be.

[0003]

In the above-mentioned prior art, there is a problem that the heating temperature fluctuates significantly when the amount or temperature of the object to be heated fluctuates, that is, when the load to be heated fluctuates. It was This is because the suction pressure generated in the ejector section and the set pressure of the pressure reducing valve are the same, so the temperature of the heating steam supplied from the pressure reducing valve and the saturation temperature of the fluid flowing down the ejector section are There is almost no difference between them, and when the load to be heated fluctuates and the amount increases, the condensate generated by condensation of steam due to heat exchange remains and the heating temperature drops. is there. If the difference between the suction pressure at the ejector section and the set pressure of the pressure reducing valve is increased, the retention of condensate can be prevented, but vapor is constantly sucked into the ejector, increasing steam loss. is there. Fluctuations in the heating temperature must be prevented as much as possible, especially in chemical products, foods, medical products, etc., because a slight temperature change causes a change in product quality.

Therefore, a technical object of the present invention is to obtain a steam heating device capable of accurately maintaining a constant heating temperature even if the load to be heated varies.

[0005]

Means for Solving the Problems The technical means of the present invention taken to solve the above-mentioned problems is to dispose a steam control valve on the primary side of a heating container and to provide an ejector on the secondary side of the heating container. A diffuser, a tank, and a circulation pump are sequentially connected, a cooling water supply passage for supplying cooling water to the tank is provided, a cooling water control valve is provided in the passage, and an ejector, a tank, and a circulation pump are provided. In a device provided with a fluid temperature detection member for detecting the temperature of the circulating fluid, a differential pressure detection means for detecting the pressure difference between the primary side and the secondary side of the heating container is provided, and the differential pressure detected by the differential pressure detection means is provided. A control unit is provided which issues an opening / closing signal of the cooling water control valve for maintaining the above-mentioned differential pressure at a desired value based on the signal and the detected temperature signal from the fluid temperature detecting member.

[0006]

The steam having a predetermined temperature or pressure is supplied to the heating container by the steam control valve provided on the primary side. By providing a differential pressure detection means for detecting the pressure difference between the primary side and the secondary side of the heating container, and opening and closing the cooling water control valve so as to maintain this differential pressure at a desired value, the primary side of the heating container The secondary pressure is maintained at the desired differential pressure. By maintaining the desired differential pressure, steam or condensate constantly flows down in the heating container according to the differential pressure and is sucked into the ejector. Therefore, even if the load to be heated fluctuates and the condensate increases, the condensate does not stay in the heating container and the heating temperature can be maintained at a predetermined constant value.

By setting the differential pressure between the primary side and the secondary side of the heating container to the minimum differential pressure at which condensed water does not stay, the suction amount of the steam supplied from the steam control valve to the ejector is also minimized. Volume and minimum steam loss.

[0008]

EXAMPLE An example showing a concrete example of the above technical means will be described (see FIG. 1). FIG. 1 is a block diagram of a steam heating apparatus of the present invention. A steam control valve 3 is attached to a steam passage 2 that supplies steam to the heating container 1. An actuator 19 is attached to the steam control valve 3. As the steam control valve 3, a manual type without an actuator 19 or a self-powered regulating valve can be used, and in the case where a pressure sensor 30 capable of detecting the steam pressure is provided in the steam passage 2. Can be a pressure control valve, and when a temperature sensor (not shown) capable of detecting the steam temperature is provided instead of the pressure sensor 30, a temperature control valve can be used. The actuator 19 of the steam control valve 3 and the pressure sensor 30 are connected via a connecting line to a first controller 31.
Connect to.

A pressure detector 20 is provided on the primary side of the heating container 1,
The pressure detector 22 is also attached to the secondary side, and both are connected to the calculator 32 via the differential pressure transmitter 23. A differential pressure setting unit (not shown) capable of setting a differential pressure in the calculator 32
Built in. The arithmetic unit 32 is connected to the first controller 31. The pressure detectors 20 and 22 and the differential pressure transmitter 23 constitute differential pressure detecting means.

The outlet side end of the steam passage 2 communicates with the ejector 5, and the diffuser portion 9 of the ejector 5 communicates with the suction port 7 of the spiral pump 6 as a circulation pump through the tank 8 to make a spiral. The discharge port 10 of the pump 6 and the nozzle portion 12 of the ejector 5 are connected by a circulation passage 11. Ejector 5, diffuser section 9, tank 8 and centrifugal pump 6
And constitute the ejector type vacuum pump 4. Circulation passage 1
A discharge passage 13 for discharging condensed water as condensed water and cooling water is provided at one end of the valve 1, and a control valve 14 for adjusting the discharge amount is attached. The control valve 14 is not always necessary when there is no large change in the discharge amount. Tank 8
A cooling water supply passage 15 for supplying cooling water to the above can be connected via a cooling water control valve 16. At the bottom of the tank 8, a temperature sensor 17 as a fluid temperature detecting means for detecting the temperature of the water in the tank 8 and further the temperature of the fluid passing through the volute pump 6, the nozzle portion 12 and the ejector portion 5 is attached.
Actuator 18 and temperature sensor of the cooling water control valve 16
17 is connected to the second controller 21. The second controller 21 is connected to the arithmetic unit 32. The first controller 31 has a built-in pressure setting unit (not shown) for transmitting a set pressure signal to the actuator 19 of the steam control valve 3. In addition, the calculator 32 calculates the necessary water temperature in the tank 8 from the set pressure in the first controller 31 and the differential pressure signal in the differential pressure transmitter 23. A transmitting unit (not shown) which emits to the second controller 21 is built in. The second controller 21 has a cooling water control valve 16 based on the above calculation result and the water temperature in the tank 8.
The actuator 18 has a transmitter (not shown) that outputs a required opening / closing signal. The arithmetic unit 32 and the second controller 21 constitute a control unit.

A communication pipe 24 communicating with the atmosphere is attached to the upper portion of the tank 8 via a valve 25. Like the steam control valve 3 and the cooling water control valve 16, the valve 25 and the control valve 14 provided in the discharge passage 13 can also be remotely controlled by the controller.

When the steam heating temperature of the heating container 1 is set, the pressure setting part of the first controller 31 sets the pressure of the steam control valve 3 to a predetermined value. In the case of steam, there is a correlation between pressure and temperature, and the heating temperature can be set by setting the pressure. From the set pressure in the first controller 31 and the temperature detected by the temperature sensor 17, the second pressure is set so that the differential pressure set by the calculator 32 is obtained.
An open / close signal is issued from the controller 21 to the cooling water control valve 16, and the fluid temperature in the tank 8, that is, the ejector.
The temperature of the fluid passing through 5 is maintained at a predetermined value, and as a result, the differential pressure between the primary side and the secondary side of the heating container 1 is also maintained at a desired value. Therefore, even if the load to be heated in the heating container 1 changes and the amount of condensate generated changes, the condensate stays because the differential pressure between the primary side and the secondary side is maintained at a desired value. Therefore, the heating temperature can be maintained constant, and the energy loss can be suppressed to a minimum without excessive heating steam being sucked into the ejector 5.

[0013]

As described above, according to the present invention, by maintaining a desired pressure difference between the primary side and the secondary side of the heating container, the condensate is retained even if the load to be heated fluctuates. Therefore, the steam heating temperature can be accurately maintained at a constant value.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a steam heating apparatus of the present invention.

[Explanation of symbols]

 1 Heating Container 2 Steam Passage 3 Steam Control Valve 4 Ejector Type Vacuum Pump 5 Ejector 6 Spiral Pump 8 Tank 9 Diffuser 15 Cooling Water Supply Passage 16 Cooling Water Control Valve 17 Temperature Sensor 18, 19 Actuator 20 pressure detector 21 second controller 22 pressure detector 23 differential pressure transmitter 31 first controller 32 calculator

Claims (1)

[Claims] 1. A steam control valve is arranged on the primary side of the heating container,
On the secondary side of the heating container, an ejector, a diffuser, a tank, and a circulation pump are sequentially connected, and a cooling water supply passage for supplying cooling water to the tank is provided, and a cooling water control valve is provided in the passage. And a fluid temperature detecting member for detecting the temperature of the fluid circulating through the ejector, the tank, and the circulation pump, the differential pressure detecting means for detecting the pressure difference between the primary side and the secondary side of the heating container is provided. A control unit for issuing an opening / closing signal of a cooling water control valve for maintaining the above-mentioned differential pressure at a desired value by a detected differential pressure signal from the differential pressure detection means and a detected temperature signal from a fluid temperature detection member. A steam heating device characterized in that