Method and device for the process regulation or control of thermal load changes of an obstruction-curved and/or thick-walled component through which a medium flows in a thermal system
View Patent ↗The novel method and device provide for process control—closed-loop control or open-loop control—for a thermal system with an obstruction-curved and/or thick-walled component through which a medium flows. The wall temperatures of the component are detected, the heat flux density of the heat flux from the medium into the wall of the component is determined, the respective heat transmission coefficient is determined, using the wall temperatures. The heat flux density, and the heat transmission coefficient thus determined are used to influence the medium properties, with the heat stresses in the component being taken into account.
1. A control method in a thermal system containing an obstruction-curved and thick-walled component through which a medium flows, the method which comprises:
detecting a temperature difference between the middle wall temperature and the internal wall temperature of the component;
determining a heat flux density of a heat flux from the medium into a wall of the component;
determining a respective heat transmission coefficient between the medium flowing through the component and the wall off the component from the temperature difference between the middle wall temperature and the internal wall temperature and the heat flux density; and
using the heat transmission coefficient to influence properties of the medium, and thereby taking into account heat stresses in the component.
2. The method according to claim 1 , which comprises implementing the process steps in a closed-loop control method for regulating the thermal system.
3. The method according to claim 1 , which comprises implementing the process steps in an open-loop control method for regulating the thermal system.
4. The method according to claim 1 , wherein the step of determining the heat transmission coefficient comprises measuring the wall temperatures of the component at an inside of the wall and substantially in a center of the wall of the component, and determining the heat flux density from the medium into the wall from the wall temperatures.
5. The method according to claim 1 , which comprises determining the heat flux density from the medium into the wall of the component by calculating
q
=
λ
(
T
m
-
T
i
)
r
i
[
(
r
o
2
r
o
2
-
r
i
2
)
2
ln
r
o
r
i
-
3
r
o
2
-
r
i
2
4
(
r
o
2
-
r
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,
where is a temperature difference between the wall temperature substantially at a center of the wall and a wall temperature at an inner part of the wall of the component, λ is the thermal conductivity, r i is an inner radius and r o is an outer radius of the wall of the component.
6. The method according to claim 1 , which comprises determining the heat transmission coefficient from:
α
=
q
T
s
-
T
i
,
where T s is a temperature of the heat flux from the medium into the wall of the component, T i is a wall temperature at an inner wall surface of the component, and q is the heat flux density.
7. The method according to claim 1 , wherein the component is a component part of a power station, and the heat transmission coefficient changing with the varying medium properties is adapted to a profile of a load change in the power station.
8. The method according to claim 7 , which comprises including in the properties of the medium a temperature, a mass flow, and a pressure from the medium into the wall of the component.
9. The method according to claim 1 , which comprises, taking into account a temperature difference between a measured internal wall temperature and a real temperature on an inner wall of the component, integrating an analytically known temperature profile in the wall of the component into the step of determining the heat transmission coefficient.
10. A process-control device, comprising interconnected control and closed-loop control modules configured to carry out the method according to claim 1 .
11. A control method in a thermal system containing an obstruction-curved and thick-walled component part of a power station, through which a medium flows, the method which comprises:
detecting a temperature difference between the middle wall temperature and the internal wall temperature of the component;
determining a heat flux density of a heat flux from the medium into a wall of the component;
determining a respective heat transmission coefficient between the medium flowing through the component and the wall of the component from the temperature difference between the middle wall temperature and the internal wall temperature and the heat flux density; and
using the heat transmission coefficient to influence properties of the medium in a controlled manner according to an efficiency criterion and to maintain permissible heat stresses; and
adapting the heat transmission coefficient changing with the varying medium properties to a profile of a load change in the power station.