3 replies to this topic

[omka]

Hello, 

I have found this example in a book talking about linear control system. Could someone help me please to understand how does this systems works?

the role of this exchanger is to use the heat of the steam to heat the cold water.

i can't understand where exactly the steam go before and after heating the water. is the steam pass by the edge of the square (which is bold in the image)or inside the square. Is the water in pipe?

another question I can't understand how the condensation takes place in this system and its objectif.

Thanks for any help and sorry for my english

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[robotan]

salam , dear omka 

 

i think it's simple regulation loop 

 

1) for the vapor flow it depend of heat exanger type for exemple: if you have shell and tube heat exchanger the cold water pass in tubes and hot vapor pass in shell side.

 

2)it's very normal condensation take place in the vapor side because the hot vapor exchange heat with cold water and therefore there is a change of state from vapor to liquid. it's objective maybe the condensed vapor is pumped toward other equipment.

 

3) the regulation is done to obtain desired temperature  of cold water at the exit of exchanger, if we have low exit temperature of water the regulation valve of steam opens more and vis versa.

[Saml]

It is an schematic. Condensation happens in the box (that may be the shell of a exhanger).

Opening and closing the valve, you are modifying the pressure drop, and the resulting effect is a change in the pressure inside the box. This change the condensation temperature and the heat transferred.

 

The condensates removal is not clearly drawn but is probably a steam trap.

 

This system works fine as long as the presssure requirement at minimum load is above the pressure required for condensate removal. i.e. if at minimum load 100 °C condensation tempeature is too hot you cannot design for such a sysemw with steam traps discharging to atmospheric pressure.

 

The upper limit is the pressure of the incoming steam

[omka]

thank you robotan and Sam