I have a food dehydrator that I use for a few fruits and vegetables, and i have dehydrated celery stalks and the leaves. It is no more strange than dehydrated milk, which also has a lot of water. To re-hydrate, just add to soups. That was the only way I used it. Now I only dry the leaves, and I would not be without the dry celery leaves in the winter. Because I am without asparagus for a few years while I am replanting the bed, I have tried a few new things this past winter. I covered my fall spinach and parlsey and celery plants all winter, and now they are regrowing!! I am mindful that celery and parsley are biennals and will be trying to go to seed shortly, but it is a cheerful site to see them growing right now. My celery and parsley seeds in the greenhouse have just germinated, yea!!
Also, you know the difference between store bought tomatoes and warm from the vine tomaotes? Well, the same thing is true with celery. Home grown celery to truely delicious, and flavorful.