JPS63194196A - Outlet port temperature controller for heat exchanger - Google Patents

Abstract

PURPOSE:To improve the response property of a feedback control system which starts control operation upon the change of the outlet temperature of a preheater, by a method wherein the title controller is equipped with a temperature detector at the outlet port of a heat exchanger, a temperature detector and a flow rate detector at the inlet port of the heat exchanger and a temperature controlling means, operating detected signals fed by respective detectors and outputting an opening degree signal for the temperature control valve of the heat exchanger. CONSTITUTION:A flow rate detector FE and a temperature detector TE are provided in the inlet line of a preheater PH to input the outputs of each detectors into a preheater temperature controller 10. Another temperature detector TE is provided at the outlet port of the preheater and the output thereof is inputted into the heat exchanger temperature controller 10. The data of the flow rate and the temperature of the inlet port are compared with the set temperature of the outlet port to employ it for the operation of the amount of necessary heat. The outlet temperature is compared with the set temperature of the outlet port and is inputted into a feedback control block while the results of operations of PID proportion, integration and differentiation are added to the result of necessary amount operation and the value of compensation, thereafter, the result of the operation is outputted to a temperature control valve TCV. According to this method, abnormal temperature rise will not be caused, stable temperature control may be effected and the response of the title controller may be improved, therefore, the operating properties of a waste disposal device or the like, using the preheater, may be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applied to an outlet temperature control device of a heat exchanger such as a heater or a cooler.

[Conventional technology]

As shown in Fig. 3, conventionally, a temperature detector 5TI is installed at the outlet of the preheater PH, and the temperature signal from this detector TE is used to detect
In order to keep the outlet temperature constant, the preheater outlet temperature control valve TCV is controlled by a feedback controller TC.

[Problem that the invention seeks to solve]

According to the prior art as described above, if the fluid flow rate and temperature at the inlet of the preheater enter the preheater without significant changes,
The outlet temperature can be controlled stably by setting the proportional, integral, and differential P of the preheater temperature controller TIC, but if the fluid inlet is switched from inlet A to inlet BK], fluids with completely different temperatures and flow rates enter the preheater. However, the temperature at the outlet could not be stabilized quickly with only the temperature controller T-C.
The outlet temperature fluctuates for a long period of time, and in some cases, it may exceed a preset alarm point as an abnormality in the equipment, making it necessary to stop the equipment. (Problem A) Also, when a low flow rate of fluid occurs, which does not occur during normal operation, the temperature at the outlet of the preheater may rise abnormally due to insufficient control ability of the preheater temperature controller TCV, although it depends on the characteristics of the preheater. Sometimes.

(Problem B) [Means for solving the problem] In order to cope with sudden changes in flow rate and temperature at the preheater inlet, the inflow flow rate x (inflow water temperature - preheater outlet setting temperature) - required amount of heat. According to the relational expression], the opening compensation function of the preheater temperature control valve TOY is added to the temperature controller. (Measures for Problem A) Additionally, an interlock circuit is added to the temperature controller to close the preheater temperature control valve TCV when the inlet flow rate is low, which is not necessary for normal control. (Measures for Problem B) [Operation] The flow rate and temperature at the inlet of the preheater are measured and input into the temperature controller, and the temperature at the outlet of the preheater (- To improve the response of a feedback control system that starts a control operation after waiting for a change in the following delay.

[Example] In FIG. 1, a flow rate detector IIE and a temperature detector 5TE are installed in the inlet line of the preheater PK and input to the preheater temperature control device 10. In addition, a temperature sensor T is installed at the preheater outlet.
I is installed and this is also input to the heat exchanger temperature control device W110. The inlet flow rate and temperature data are compared with the outlet temperature set point and used to calculate the required amount of heat.

The outlet temperature is compared with the outlet temperature setting, input to the feedback control block, and the results of proportional, integral, and differential calculations from P are added to the compensation value of the required heat amount calculation result, and the result is output to the temperature control valve TCV. This functional block diagram is shown in FIG.

The heat exchanger temperature control device 10 also includes a changeover switch SW that detects a low inlet flow rate and forcibly closes the temperature control valve TCV.

〔Effect of the invention〕

The heat exchanger outlet temperature control device of the present invention allows stable temperature control of the heat exchanger outlet temperature without causing an abnormal temperature rise such as stopping the alarm point device. Furthermore, since the responsiveness is improved, the operability of a waste treatment apparatus using a preheater is improved, and the operating time (device start-up time) can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a temperature control diagram in which the heat exchanger outlet temperature control device of the present invention is implemented in a preheater, FIG. 2 is a functional block diagram of FIG. 1, and FIG. 3 is a conventional temperature control diagram. ASS...Heating steam TFi...Temperature detector F
Fi...Flow rate detector TCV...Preheater temperature control valve PH...Preheater

Claims (1)

[Claims] A heat exchanger outlet temperature control device that controls the outlet temperature of a fluid heat exchanged with a heat exchange medium in a heat exchanger includes a temperature detector that detects the fluid temperature at the heat exchanger outlet, and a temperature detector that detects the fluid temperature at the heat exchanger inlet. A temperature detector and a flow rate detector are provided to detect the fluid flow rate, and detection signals from these detectors are input and processed to open a heat exchanger temperature control valve that controls the flow rate of the heat exchange medium. A heat exchanger outlet temperature control device, characterized in that it is equipped with a temperature control means that outputs a temperature signal.