OK, I get the message..
Well, the level of complexity is that of giving all the pipes and valves messures, tanks, pumps, fans, the power of them, and other things but is not compulsory to make it 3D (We are not thaught that in faculty.)
I was maybe fooled with hope that making it 3D would be pice of cake by watching some tutorials in youtub but it's true that complexity increase easily when we are in 3D.
So, I will again consider 2D somehow
Nevertheles, I will enrole myself in a course of AutoCAD because it's passionating everything it can be done if we know how!
Thankyou very much ReMark
Thanks for yours quik answers