Temperature cascade control problem
Thread Content
This post was last edited by Fengyu Xingchen Yicaihong on 2023-6-2 at 09:10. Dear experts, please help me understand how the temperature TE10702 at the bottom of the tank is regulated by the heater outlet temperature TE10507 and the fuel gas control valve FV10601 in the heater. What is the logical relationship between them? What role does TY10702 play? Are the “<” symbol on it and the “>” symbol on FY10601B logical operators such as AND, OR, or NOT? FY20002/3/4: The outlet flow rate at the bottom of this tank should belong to another circuit and can be ignored
As shown in the diagram, TE10702 is controlled by the furnace outlet temperature TE10507 and the furnace fuel gas control valve FV10601. When the temperature of TE10702 is below the set value, TY10702 opens, which causes the fuel gas control valve FV10601 of the heating furnace to open as well; this raises the outlet temperature TE10507 of the heating furnace, thereby increasing the bottom temperature of tank TE10702. “\" and \"> are comparison symbols, indicating that the bottom temperature of TE10702 should be less than the set value, and the output signal of FV10601 should be greater than the set value. FY20002/3/4 is the control element of another circuit and is not within the scope of this temperature cascade control. In summary, the bottom temperature of TE10702 is controlled by TE10507 and FV10601; through appropriate logical relationships, the bottom temperature can be brought to the set value. .
It’s a low selection or high selection; guess: TY10702 calculates a low selection value (TC-10702, TC-10507) as the SP value for FC-10601. The final FY10601B should be the higher of the output values from PC10607 and FC-10601, which is then used to control the valve position. There’s one question I don’t understand: Is FY10601A associated with a flow meter? If it is, the signals from the temperature and pressure analysis table taken earlier are used for compensation calculations. If not, it might have been calculated using the signals from the temperature and pressure analysis table! ?
This post was last edited by cust008 on 2023-6-14 08:56. Ask your supervisor or your colleagues in-house; if they are willing to teach you. But sometimes you end up frustrated – they don’t like to teach. I heard things like that at the time: you don’t need to understand this; just do your assigned tasks properly. You just need to follow orders and do whatever is told to you. What position do you hold? (It means you don’t need to learn this for your position; what you’re learning, *, is beyond the scope required.) ), and so on. If your leader wants to promote you, anything you learn is right; otherwise, everything you learn is wrong. However, it’s truly impressive to be able to connect the greater-than and less-than symbols with NAND and OR – that’s a very rich imagination. Here, when controlling the temperature at the bottom of the tank, the top priority is to ensure that the furnace does not go out, and the second priority is to ensure that the furnace does not overheat. The bottom temperature of the tank is determined by two factors: one is the flow rate of the material, and the other is the amount of heat applied, that is, the flow rate of the fuel. We have not discussed the flow rate of materials here; only the flow rate of fuel is discussed. First, the low setting ensures that the furnace does not overheat, and then the high setting ensures that the furnace does not go out.
It involves complex control; here it is cascade control combined with selective control. > ,
For too-high-temperature conditions, choose a lower value for the heating rate of the mixture and the temperature of the fresh material exiting the furnace; choose a higher value for flow control and pressure control