JPS61821A - Temperature controller of heavy oil heater - Google Patents

Abstract

PURPOSE:To secure a wide control range without deteriorating the controllability by applying the control of temperature that controls only a range of low heat exchange quantity where the controllability is deteriorated according to the increase or decrease of the heat transmission area. CONSTITUTION:When the output of a deviation controller 2 is set lower than a certain level to the opening amount of a steam flow rate control valve 4, the output of a function generator 7 is outputted by changing the level set value by an amount larger than the reference water level 10. Thus a difference is produced between the output of a condensed level oscillator 6 and that of a function generator 7, and the output of a deviation controller 8 delivers a closed signal to a condensed water level control valve 9. The level 10 is raised up for condensed water by closing the valve 9, and the control of temperature is carried out within a range of low heat exchange quantity with reduction of a heat transmission area. Thus a wide control range of temperatures is secured without deteriorating the controllability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a temperature control device for a heavy oil heater that can ensure a wide control range without impairing conventional controllability.

Conventional technology Conventional heavy oil heater temperature control devices, for example.

As shown in FIG. 2, it is composed of a heavy oil heater outlet heavy oil temperature transmitter], a deviation controller 2, a heavy oil heater outlet heavy oil temperature setting device 3, and a heavy oil heater steam flow rate control valve 4. The heat exchange amount is controlled by changing the steam flow rate based on the opening degree of the heavy oil heater steam flow rate control valve, which is determined from the deviation between the heavy oil temperature at the outlet of the heavy oil heater and its set temperature.

Therefore, in the conventional temperature control device, the rangeability of the steam flow rate control valve 4 is directly within the control range of the heavy oil heater.

Problems to be Solved by the Invention The present invention aims to provide a temperature control device that can control even the range of low heat exchange amount where controllability deteriorates and secure a wider control range than conventional temperature control devices. purpose.

Means for Solving the Problems The heavy oil heater temperature control device according to the present invention includes a controller that adjusts the opening degree of the heavy oil heater steam flow control valve, and an output of the controller that is inputted to adjust the heavy oil heater condensate water level. The controller includes a function generator that outputs a set value, and a controller that receives the output of the function generator and the output of the heavy oil heater condensed water level transmitter and outputs a heavy oil heater condensed water level control valve opening adjustment signal. By adding temperature control that is performed by increasing or decreasing the heat transfer area only in the range of low heat exchange amount where controllability deteriorates, a wide control range is secured without impairing the controllability of the conventional control method.

EXAMPLES Below, a preferred embodiment of the present invention illustrated in FIG. 1 will be described in detail.

In FIG. 1, the temperature control device for the heavy oil heater includes a heavy oil heater (heat exchanger) 11 and a heavy oil heater steam flow control valve 4.
, a heavy oil heater condensed water level control valve 9, and a drain trap 5, and a heavy oil heater outlet heavy oil temperature transmitter 1, a heavy oil heater outlet heavy oil temperature setting device 3, and the heavy oil temperature transmitter. 1 and a deviation controller 2 of the output signal of the setting device 3.

A heavy oil heater condensed water level transmitter 6, a function generator 7 for the deviation output of the deviation controller 2, and a condensed water level transmitter 6
and a deviation controller 8 for the output signal of the function generator 7 are connected.

To explain the operation, the output of the deviation controller 2 which receives the output of the heavy oil heater outlet heavy oil temperature transmitter 1 and the output of the heavy oil heater outlet heavy oil temperature setting device 3 is determined by the output of the heavy oil heater steam flow rate control valve 4. This becomes the opening command and the function generator 70 input. The output of the function generator 7 becomes the target value for the heavy oil heater condensate level.

The output of the deviation controller 8, which receives this target value and the output of the heavy oil heater condensed water level transmitter 6, becomes a control signal to the heavy oil heater condensed water level control valve 9.

In this control system, in order to control the heavy oil temperature at the outlet of the heavy oil heater to a set temperature, the heavy oil heater steam flow control valve 4 is operated by the output of the deviation controller 2. If the output of the deviation controller 2 is above a certain level with respect to the water level, the function generator 7 outputs a level setting value of the reference water amount of 10 or less.

The output of the heavy oil heater condensed water level transmitter 6 is the reference water level 1.
Since it is not possible to output a level signal below 0, a deviation controller 8 whose input is the output of the condensed water level transmitter 6 and the function generator 7 is used.
outputs a fully open signal to the condensed water level control valve 9. This control state is similar to conventional control because the condensed water level control valve 9 is fully open.

Next, the deviation controller 2
When the output of the function generator 7 becomes less than a certain level, the output of the function generator 7 changes the level setting value to a reference water amount of 10 or more and outputs it. Therefore, a deviation occurs between the output of the condensed water level transmitter 6 and the output of the function generator 7, and the output of the deviation controller 8 outputs a close signal to the condensed water level control valve 9. By closing the condensed water level control valve 9, the standard water amount 100 level of condensed water is raised, the heat transfer area is narrowed, and temperature control is performed in the range of low heat exchange amount.

As mentioned above, in the conventional control device, the amount of heat exchange is controlled by changing the steam flow rate based on the opening degree of the heavy oil heater steam flow rate control valve, which is determined from the deviation between the heavy oil temperature at the outlet of the heavy oil heater and the set temperature. For this reason, the shearability of the steam flow control valve was limited to the control range of the heavy oil heater, whereas in the device according to the present invention, the steam flow rate control for temperature control is performed when the steam flow rate is low (steam flow rate control When the valve opening degree is small), the condensed water level control in the heavy oil heater is used to change the heat transfer area in the heavy oil heater with changes in the condensed water level and control the amount of heat exchange. This has the effect of ensuring a wider control range than conventional control devices.

[Brief explanation of the drawing]

FIG. 1 is a system diagram illustrating the outline of a heavy oil heater temperature control device according to the present invention, and FIG. 2 is a system diagram showing a typical example of a conventional heavy oil heater temperature control device. 1. Heavy oil temperature transmitter, 2. Deviation controller, 3. Heavy oil temperature setting device, 4. Steam flow control valve, 5. Drain trap, 6. Condensed water level transmitter, 7. Function generator,
8. Deviation controller, 9. Condensed water level control valve, 10.
- Standard water volume, 11... Heavy oil heater (heat exchanger). (2 people)

Claims (1)

[Claims] a controller that adjusts the opening degree of the heavy oil heater steam flow control valve;
A function generator receives the controller output and outputs the heavy oil heater condensate level set value, and a function generator receives the same function generator output and the heavy oil heater condensate water level transmitter output to control the heavy oil heater condensate water level. A heavy oil heater temperature control device comprising a controller that outputs a valve opening adjustment signal.