JPH08170807A - Steam heating equipment - Google Patents

Abstract

PURPOSE: To control a temperature of heating steam precisely without causing a time delay in alteration of the heating temperature. CONSTITUTION: A steam supply pipe 3 is connected to a heat exchanger 1 through the intermediary of a pressure regulating valve 2. The lower part of the heat exchanger 1 is connected to an ejector 11 of an ejector type vacuum pump 4. A cooling water control valve 6 and a temperature sensor 10 are fitted to a tank 5 of the ejector type vacuum pump 4. The cooling water control valve 6 and the temperature sensor 10 are connected to a first controller 7. The pressure regulating valve 2 is connected to a second controller 8. The first controller 7 and the second controller 8 are put in cascade connection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to heating an object to be heated in a heat exchanger with steam, and particularly, the heating temperature thereof is 100.
The present invention relates to a steam heating device suitable for a relatively low temperature of about C. Specifically, it is used for steam heating of various reaction kettles used for polymerization reaction, food distilling devices, concentrating devices, and sterilizing devices. In these cases, the object to be heated often suffers from thermal damage or composition change due to a slight temperature change, and it was necessary to maintain the heating temperature with high accuracy.

[0002]

2. Description of the Related Art As a conventional steam heating device, for example, one disclosed in Japanese Patent Laid-Open No. 3-241202 has been used. This is one in which a pressure reducing valve, a heating container, and an ejector-type vacuum pump are sequentially connected, and the pressure drive part of the pressure reducing valve and the vicinity of the ejector are connected by a pressure communication pipe, and the temperature of water passing through the ejector is controlled. Simply changing the suction force of the ejector changes the pressure drive unit of the pressure reducing valve via the pressure communication pipe, and the set pressure of the pressure reducing valve can be changed automatically, making it easy to change the heating steam temperature. Is what you can do.

[0003]

The above-described conventional steam heating device has a problem that it takes time to change the heating temperature, which causes a time delay in temperature control. This is because when the heating temperature is changed, the temperature of the fluid passing through the ejector must be changed. Actually, by supplying cooling water to the tank communicating with the ejector, the fluid in the tank is changed. There is a time delay because the temperature of the fluid passing through the ejector is changed after the temperature is changed.

Therefore, a technical object of the present invention is to obtain a steam heating apparatus in which the steam heating temperature is changed promptly and there is no time delay.

[0005]

The structure of the steam heating apparatus of the present invention is as follows. A pressure control valve, a heat exchanger, and an ejector-type vacuum pump are connected in sequence, temperature detection means is installed to detect the temperature of the fluid circulating through the ejector-type vacuum pump, and cooling water control is provided to replenish the circulating fluid with cooling water. With a valve attached, heating steam is supplied from the pressure control valve to the heat exchanger and sucked by the ejector-type vacuum pump, the temperature detection means and the cooling water control valve are connected with the first controller to adjust the pressure. The valve is connected to the second controller, and the first controller and the second controller are cascade-connected.

[0006]

[Operation] The first controller of the cooling water control valve and the second controller of the pressure control valve
The cascade connection with the controller allows the control output of the first controller to be given as the set value of the second controller to quickly change the set pressure of the pressure adjusting valve. Therefore, the cooling water is replenished by the control of the cooling water control valve, the temperature of the circulating fluid of the ejector vacuum pump is changed, and the suction pressure of the ejector vacuum pump changes, so that the set pressure of the pressure adjustment valve is changed. It will not be necessary to wait.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The illustrated embodiment will be described in detail. Heat exchanger 1
A steam supply pipe 3 is connected to the pressure control valve 2. The lower part of the heat exchanger 1 is connected to the ejector vacuum pump 4.
A cooling water control valve 6 is installed in the tank 5 of the ejector-type vacuum pump 4.
And a temperature sensor 10 as a temperature detecting means are attached and connected to the first controller 7. The pressure regulating valve 2 and the second controller 8 are connected, and the first controller 7 and the second controller 8 are cascade connected. A pressure sensor 9 for detecting the pressure on the secondary side of the pressure regulating valve 2 is also connected to the second controller 8.

The ejector type vacuum pump 4 comprises an ejector 11 having a built-in nozzle, a tank 5, a circulation pump 12, and a circulation path 13 connecting these. The lower portion of the tank 5 and the suction port side of the circulation pump 12 are connected, and the discharge port side of the circulation pump 12 is connected to the ejector 11. The ejector type vacuum pump 4 is configured to generate a suction force in the ejector 11 by circulating the fluid in the tank 5 with the circulation pump 12 and passing it to the nozzle portion in the ejector 11. A surplus liquid discharge passage 16 is connected to a circulation passage 13 connected to the discharge port of the circulation pump 12 via a valve 15. A temperature sensor 10 for detecting the internal liquid temperature is attached to the tank 5, and a cooling water supply pipe 17 is connected to the upper portion of the tank 5 via a cooling water control valve 6. The tank 5 is on the upper side of the tank 5.
An atmosphere communication pipe 18 that connects the inside to the atmosphere is attached.

Next, the operation will be described. The steam for heating is supplied from the steam supply pipe 3 to the heat exchanger 1 through the pressure regulating valve 2, and the ejector-type vacuum pump 4 is driven to generate suction force at the ejector 11 to generate heat inside the heat exchanger 1. By maintaining the inside of the steam pipe at a predetermined vacuum degree, the object to be heated in the heat exchanger 1 is heated by the low-temperature steam. The steam that has heated the object to be heated is condensed into condensate and is sucked by the ejector 11 of the ejector-type vacuum pump 4 to reach the tank 5.

The degree of vacuum generated in the ejector type vacuum pump 6 is determined by the temperature of the fluid passing through the ejector 11. That is, the degree of vacuum up to the saturation pressure corresponding to the temperature of the passing fluid can be obtained. Therefore, when changing the heating temperature in the heat exchanger 1, for example, when it is necessary to lower the heating temperature, it is necessary to lower the temperature of the fluid passing through the ejector 11 to increase the degree of vacuum. The heating temperature can be lowered by opening / closing the cooling water control valve 6 according to the detected value from −10 to supply the cooling water to the tank 5 and lowering the temperature of the circulating fluid to a predetermined value. in this case,
A control output for controlling the cooling water control valve 6 is output from the first controller, and this control output is input as a set value to the second controller due to the cascade connection.
By immediately changing the set pressure of the pressure regulating valve, the pressure of the steam supplied to the heat exchanger 1 is lowered, and the heating steam whose temperature is lowered by a predetermined value is promptly supplied. Therefore, the cooling water is replenished from the cooling water control valve 6 and the ejector
The time until the set pressure of the pressure adjusting valve 2 is changed only after the temperature of the fluid passing through 11 is lowered becomes unnecessary, and the heating temperature can be controlled without a time delay.

[0011]

According to the present invention, since the first controller of the cooling water control valve and the second controller of the pressure adjusting valve are cascade-connected, the control of the cooling water controlling valve and the setting of the pressure adjusting valve are performed. Since the pressure is also changed, the time required until the temperature of the fluid circulating in the ejector-type vacuum pump is changed becomes unnecessary, and there is no time delay in steam temperature control.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a steam heating device of the present invention.

[Explanation of symbols]

 1 heat exchanger 2 pressure control valve 3 steam supply pipe 4 ejector type vacuum pump 5 tank 7 first controller 8 second controller 10 temperature sensor 11 ejector 12 circulation pump

Claims (1)

[Claims] 1. A pressure control valve, a heat exchanger, and an ejector-type vacuum pump are sequentially connected to each other, and temperature detection means for detecting the temperature of a fluid circulating through the ejector-type vacuum pump is attached to the circulating fluid. In the case where a cooling water control valve for replenishment is attached, heating steam is supplied from the pressure regulating valve to the heat exchanger, and sucked by an ejector-type vacuum pump,
The temperature detecting means and the cooling water control valve are connected by a first controller, the pressure adjusting valve is connected by a second controller, and the first controller and the second controller are cascade-connected. Steam heating device.