JPS592873Y2 - Brine heater heating steam temperature control device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a heating steam temperature control device for a brine heater.

A conventional heating steam temperature control device for a brine heater for water supply is shown in Fig. 1, in which 2 is a desuperheater, 4 is a brine heater,
Heated steam is introduced into this to heat the brine B flowing through the heat transfer tube 4a to a required temperature.

Drain i condensed by heating the brine B is sent by a condensate pump 6 via a condensate line C and injected into the desuperheater 2 to detemperate the steam S supplied there.

The brine heated by the brine heater 4 is sent to a water supply device (not shown).

g is a level controller, and f is a level control valve.

The temperature of the heated steam supplied to the brine heater 4 is controlled by detecting the temperature of the steam flowing through the steam line h downstream of the desuperheater 2 using the temperature sensor TE, and by detecting the difference between this detected value and the set value X. is calculated by the proportional and integral calculator P+I, and the electro-pneumatic converter E/P is operated by the signal obtained from the condensate line C.
This was done by adjusting the opening/closing degree of the water injection valve 8 inside and adjusting the amount of drain i injected into the desuperheater 2.

However, the temperature of the drain i injected into the desuperheater 2 is approximately 100
℃, the difference in volume with steam is small, so a large amount of drain i had to be injected.

In addition, if the injected drain i does not completely evaporate in the pipe from the desuperheater 2 to the downstream temperature sensor TE, the drain i will adhere to the measurement terminal of the temperature sensor TE, and the temperature sensor TE will detect the steam temperature. When the temperature drops below the actual value, a similar signal is issued and the amount of drain injected into the desuperheater 2 is reduced.

Next, when the amount of drain i to be injected decreases, the drain i adhering to the temperature sensor TE evaporates, and the temperature sensor TE detects a temperature higher than the actual temperature and performs erroneous control to increase the amount of drain to be injected.

This phenomenon is called control bunching.

Therefore, in order to prevent the control bunching described above, conventionally,
In order to completely evaporate the drain i in the steam line h from the desuperheater 2 to the temperature sensor TE, the length of the pipe had to be at least 40 times the inner diameter of the pipe.

The present invention has been devised in view of the above, and will be described below based on an embodiment shown in FIG.

Components in FIG. 2 denoted by the same reference numerals as those in FIG. 1 are the same.

In FIG. 2, the supplied steam S passes through a flow meter 1, its temperature is measured by a temperature sensor 10, and the temperature is reduced by pouring water into a drain i in a desuperheater 2, and the steam is heated to a desired temperature, and then sent to a brine heater 4. to go into.

The steam after heat exchange in the brine heater becomes drain and is returned to the steam generator 21 by the condensate pump 6 via the control valve 7.

Reference numeral 3 denotes a drain tank, and when the drain level rises and the drain tank is opened, a level switch 19 is operated and an on-off valve 5 is opened.

When the level of the drain tank 3 drops too much, the level switch 20 operates and the on-off valve 5 closes.

Reference numeral 18 denotes a drain level controller for the brine heater 4, which adjusts the drain level by opening and closing the level cooking valve 7.

The flow rate of the supplied steam S is converted into an electrical signal by the flow rate transmitter 9, and this signal is linearized by the square root calculator 12 and then enters the calculator 13 together with the temperature signal measured by the temperature sensor 10. Enthalpy is calculated.

The injection valve 8 is opened so that a drain amount proportional to this enthalpy value is injected into the desuperheater 2, but in this case, the computer 21 works, the temperature of the steam whose temperature has been reduced by the attemperator 2 is measured by the temperature sensor 11, and this temperature signal is subtracted from the set value
6 and input to the adder 14.

The electric signal output from the adder 14 is converted into a pneumatic signal by the converter 17, and the water injection valve 8 is actuated.

Therefore, the temperature of the heated steam introduced into the brine heater 4 is controlled by measuring the state of the heated steam using the flow meter 1 and the temperature sensor 10, calculating its enthalpy using the calculator 13, and controlling the drain according to this enthalpy value. Place in desuperheater 2.

If there is a difference between the detected value of the temperature sensor 11, that is, the temperature of the heated steam introduced into the brine heater 4, and the set value X, the difference is corrected by the proportional calculator 16.

For example, if the steam flow rate is lower than the actual amount due to an error in the flow meter 9, the amount of water injected into the desuperheater 2 from the drain will be decreased.

In this case, there is a difference between the set temperature (set value X) and the actually measured temperature (value detected by the temperature sensor 11).

The amount of water injected is increased by a signal from the proportional calculator 16 so as to fill this difference.

If the drain i injected into the desuperheater 2 has passed and not all of it evaporates, the remainder is stored in the drain tank 3,
The drain level is maintained at a predetermined level by the level switches 19 and 20, and the excess is returned to the brine heater 4 by the on-off valve 5.

As described above, the heating steam temperature control device for a brine heater according to the present invention includes means for detecting the enthalpy of steam upstream of the attemperator and injecting steam into the attemperator in proportion to the detected enthalpy value. Since it is equipped with a means to adjust the amount of condensate, it is possible to grasp the enthalpy of the steam supplied to the desuperheater and inject condensate commensurate with that, ensuring that the amount of condensate injected into the desuperheater is always appropriate. As a result, there is no need for excess injection and the drain can be completely evaporated, and the length of the pipe from the desuperheater to the temperature sensor in the middle of the pipe path from the brine heater to the brine heater can be made much shorter than in the past.

Furthermore, control bunching does not occur.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional heating steam temperature control device for a water supply brine heater, and FIG. 2 is a circuit diagram of an embodiment of the present invention. 4...Brine heater, i...Drain, B...Brine, 2...Desuperheater.

Claims (1)

[Scope of utility model registration request] In a system in which condensate generated in a brine heater is injected into a desuperheater to heat the brine, the steam is detempered by injecting it into a desuperheater, and the brine is heated by introducing the wetted steam into the brine heater, in which the steam in the upstream of the desuperheater is 1. A heating steam temperature control device for a brine heater, comprising: means for detecting the enthalpy of the water; and means for adjusting the amount of condensate injected into the desuperheater in proportion to the detected enthalpy value.