Flying SIN to DAC- are we eligible for 24hr visa-free transit at CAN?

Rejwan, it is important to know that you will by traveling through China on 24 hour visa free transit, so this is not a visa, but this is your status or better to say a scheme that allows you to travel via China absolutely visa free.

This permit, by its definition, is not a passenger's right, but more like a bonus that is offered on case by case basis. In other words the issuing of the permit remains in absolute jurisdiction and discretionary decision of the Chinese immigration authorities.

Since you have 21 hours long layover, I would say that your chances to be allowed to exit the airport are excellent, but definitely not with 100% certainty. There is nobody that could guarantee 100% certainty when we come to this option.

In any case, the first thing that you will do upon landing is to approach 24 hour visa free transit counter where you will apply for a temporary entry permit by presenting your flight tickets and a hotel booking if you plan to stay in a hotel. It is advisable to have all those details printed out. This application is free of any charge. After a short check, you will be hopefully granted a permit and after that you will head to the immigration. When you have cleared the immigration you will proceed to the city to enjoy your free time on your own. Have a nice journey.