How to increase the maximum send rate per second ?

Want to ask about the maximum send rate per second

How to increase?

Our current settings are:

Daily sending quota

50,000 emails per 24-hour period

Maximum send rate

14 emails per second

Because we estimate here, we need to send 700 letters within two hours

But because of this limitation, only about 500 letters have been completed.

So I want to ask how to increase the maximum send rate per second?