It depends on the amount of acid compared to the amount of water. If you are adding a small amount of acid to a much larger volume of water, it should be of little concern because the large amount of water will carry the heat away.
You should have the acid gravity drain into the water rather than inject the acid. If you inject the acid, you should be concerned about water backing up into your acid piping and tank. If that acid backup occurs, you may generate localized exothermic heat in the piping. A double block and bleed valves arrangement will prevent backup. You also need to be concerned should the system stop operating with acid in the piping.
It would probably be more practical for your operation if you were using a more dilute acid. The process may be safer and easier to control.