JPS5938502A - Heat exchanger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchange device that controls the amount of drawn steam suitable for preventing a fluid in a tube whose phase changes from gas to liquid from being supercooled at the outlet of a heat transfer tube.

An example of the structure of a conventional heat exchanger using high-pressure steam and low-pressure steam is shown in FIG. The heat exchanger 1 introduces high-pressure steam through the heated fluid inlet pipe 2, causes it to flow through the plurality of heat transfer tubes 3, reduces the temperature by heat exchange, and forms a condensed water film on the inner surface of the heat exchanger 1 to form a two-phase Flow,
Finally, all of the condensed water is converted into condensed water, which is discharged through the heated fluid outlet pipe 4 and collected in the drain tank 5. At the same time, the non-condensable gas in the heated fluid is discharged through the vent pipe 6. On the other hand, the low-pressure steam flowing orthogonally outside the heat transfer tube 3 flows into the heated fluid inlet pipe 7 and flows out through the outlet pipe 8 while increasing its temperature in the flow direction. Therefore, since the heat load differs in the flow direction outside the heat exchanger tubes 3, the amount of condensed water, G, in each heat exchanger tube 3a, 3b becomes uneven, as shown by the solid line in Fig. 2, and the amount of condensed water is large. In the heat exchanger tube 3a, the performance as a heat exchanger is further deteriorated due to a supercooled state.
From the viewpoint of preventing supercooling, the third
As shown in the figure, an orifice 9 is inserted near the inlet of the heat transfer tube 3, and in order to prevent supercooling after the total condensation point, the condensed water amount is 0 to 10
Although it is a well-known technology to discharge vent steam at a heavy flow rate in the form of steam, depending on the system in which the heat exchanger is provided, it may be provided not only at the design heat load state but also over a wide range of heat loads. In this case, the unbalance of the amount of condensed water in the heat transfer tube will be as shown by the dotted line in Fig. 2, and supercooling will occur, or the vent steam flow rate ratio may be increased. As a heat exchange system, it has the disadvantage of increasing heat loss.

It is an object of the present invention to minimize heat losses in steam/steam heat exchange systems when subjected to different heat load conditions by minimizing subcooling of the heated fluid and vent steam flow rate. The objective is to provide a control system that reduces the

Generally, in heat exchange systems that heat steam as medium energy, the latent heat of the steam is often used to increase temperature efficiency, and it is desirable that the condensed water flowing out from the heat transfer tubes be saturated water. If the heat transfer tubes are operated with different heat load imbalances, overcooling cannot be prevented only by using flow rate distribution orifices to the heat transfer tubes or vent pipes.

Hereinafter, the specific contents of the present invention will be described in detail using examples. In the heat exchange system of the present invention, as shown in FIG. 4, a heat exchanger 1 exchanges heat between high-pressure steam and low-pressure steam. Rl from the mature fluid inlet chamber lO to multiple heat exchanger tubes 3
The condensed water gradually flows into the heated fluid outlet chamber 11, exhibiting a two-phase flow, and is divided into steam and thin ice, and the condensed water exits the heated fluid outlet. It is collected into a drain tank 5 via a pipe 4.

The steam released by Nff is discharged through vent '#6.

On the other hand, the low-pressure steam has a heating fluid population i of 7,
By flowing perpendicularly to the plurality of heat transfer tubes 3, the temperature rises, and the heated fluid is discharged through the heat exchanger tube 8.

A temperature setting device 14 is provided in the heated fluid outlet pipe 4, which receives a detection signal from a pressure detector 13 provided in the heated fluid inlet pipe 2 and generates a temperature signal corresponding to the saturation temperature corresponding to the pressure. A comparator 16 is provided which outputs the degree of supercooling of the condensed water by comparing the temperature signal from the temperature detector 15 and the temperature signal from the temperature setting device 14. In order to provide an opening signal to the steam flow control valve 17, an opening setting device 18 is provided which takes the output signal from the comparator 16 as an input signal, and is equipped with an opening setting device 18 that takes the output signal from the comparator 16 as an input signal. This prevents cooling and minimizes the amount of vent steam.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a conventional heat exchange system, FIG. 2 is a diagram showing the heat load characteristics of heat transfer tubes, FIG. 3 is a diagram showing the structure of an orifice for flow distribution, and FIG. 4 is a diagram showing the configuration of the heat exchange system of the present invention. 1... Heat exchanger, 2... Heating fluid inlet pipe, 3...
Heat exchanger tube, 4... heated fluid outlet pipe, 13... pressure detector, 14... tenth

Claims (1)

[Claims] 1. In a heat transfer tube in which the heating fluid undergoes heat exchange with a phase change from vapor to liquid, the temperature is determined by receiving a detection signal from a pressure detector installed at the inlet pipe of the heating fluid. A temperature setting device that emits a control signal, and at least two outlet pipes for the heating fluid, and receiving a detection signal from a temperature detector provided in one of the exit pipes and the temperature control signal from the temperature setting device. 1. A heat exchanger comprising: a comparator for making a comparison; and means for receiving a control signal from the comparator to set the opening degree of a control valve for other outlet pipes.