There is a principle that works very well with everyone and especially with children. It is that if something is so firmly denied that the person sees no possibility of ever having it, they will soon cease to desire it. However, if it is not very firmly denied, they will keep trying. Kind of like my cat who was never allowed inside and she finally got over trying to get in. She'd even stand near the open door and watch, but wouldn't try to get in anymore.
So what I would do in this case is give her a swat (if you aren't against a swat; if you do it before you get angry and frustrated, you won't be lashing out and it can be very effective. You can probably get the same results--with more time and effort--without the swat if you are willing to invest the time to see the battle through; swats speed up the process considerably). So give her one firm swat and put her in the corner until she calms down. You can tell her in the process what she did wrong, but don't expect her to understand it all the first time. I do it out of principle, but I don't waste time with long explanations. Something like, "That was because you were screaming. Now you can stand in the corner until you calm down." She'll figure out what you meant from the context after a couple of repeats. Then I would do the opposite of what she wants until she surrenders to me and can be happy wherever I put her.
For instance: Suppose she starts screaming to get out of the chair. I would give her one swat (calmly) and put her in the corner for a time out which would last until she has calmed down--even if it takes more than 2 minutes. At 2 she's perfectly in control of her emotions, so once she realizes she's not going to get anywhere by screaming she'll calm down. Then I would put her back in the chair and tell her to stay there. If she starts screaming to get back in, I would do the same thing, only this time I would end by putting her on my lap to finish the meal. Repeat as necessary. If you are consistent the first few times, you won't have many battles and each one will be shorter than the one before; if you give her wiggle room, the battles will always be long.
Now, in my case my 2yo doesn't scream, but she does sometimes get rather demanding. I don't swat for that, but I do redirect. If she's saying, "Up, up, up, up, up," etc, I would stop her and tell her to say "Up, please." When she says "Up, please," then I put her up, not before, but only if she does it cheerfully. If she doesn't do it cheerfully, I tell her she can't get up now, and then deal with her as necessary. Sometimes she'll just resign herself to it, other times it will be more of a battle.
You might be able to get more ideas from www.raisinggodlytomatoes.com