Is there any limit for the number of Application alerts for a project?

Yes, in Catalyst DevOps you can create up to 20 Application Alerts.

To create an alert, navigate to DevOps → Application Alerts in the Catalyst console and click Create Alert. A single alert can be associated with multiple entities of Cron, Event Listener or Logs, and can notify up to 10 email addresses. You can disable an alert and enable it again later.

Refer to the Application Alerts implementation help page for details.