loading my model to load_class

I my project I need to create model without CI instance.

No, you don't need to do that. A need is having a controller, because CI doesn't work without one (it is literally "the CI instance").
You want to do this because you believe it will make something else easier or simpler for you. And as you're already hitting a brick wall - it obviously doesn't.

This is very common, both here and on StackOverflow ... People don't ask how to do a thing; they decide how they do it (usually the first idea that comes to mind) and then ask how to make that idea work, when it was never a good idea in the first place.

Take a step back, think it through again, and if you can't come up with a way that doesn't involve misusing the framework - ask us for ideas on the higher-level problem.