If I filled in "travel" when applying for a private passport, will it affect my future application for a study visa?

No problem. Once you apply for China's ordinary passport (private passport), it does not matter what your purpose is, so there is no such thing as a "tourist passport" or a "study passport". Only when you apply for a foreign visa, the foreign country will issue it according to your purpose. Different types of visas. Therefore, you can use this passport to study abroad, travel, or go abroad for business activities or to visit relatives and friends. It is all possible and legal, as long as you obtain a visa through normal channels and enter and exit normally.