I have created some DNN schedulers to run at 24 hours time intervals. But the schedulers are not running in Dnn during the time when the IIS recycles App-pool and before the next request will come to the application. 

Is there any solution to run my DNN schedulers irrespective of IIS Worker process area Alive or not ?

For the dnn scheduler to trigger - the application pool must be alive.  I would suggest running a keep alive application or using a site test service to ensure that the application pool is active.

Westa 

The scheduler is a queue - by default it only ever allows one schedule task to run at a time - as such yes what you are seeing is by design.
While it is theoretically possible to increase the number of scheduler threads in your web.config - doing so has a lot of potential to cause issues with other core scheduler tasks.
I would personally be somewhat concerned about any scheduler task that is running for more than a minute or so.
Maybe you need to look at better ways to design your scheduled tasks so that they are less intensive.
Alternatively - If you are running some sort of time critical background task or system monitor - you may be better off starting up your own stand alone workerprocess and pass the job off to it - instead of relying on the scheduler workerthread - dnn also needs access to the scheduler for its own springclearing and things like indexing - if you have a process hogging the scheduler thread the whole system may suffer over time.

Westa