At what temperature the kelvin scale will be double of Fahrenheit scale?

Never.

Explanation:

32F is 0C, is 273k. 0F is 255k. Since Fahrenheit degrees are smaller than Celsius or kelvin, the Fahrenheit numbers will go up faster than kelvin numbers will. Below 0°F it would make no sense, since a negative number cannot be twice a positive number. Using mathematics you can show that the lines would cross somewhere below 0k, but that temperature does not exist

because if the tool that you are using is not balanced it there would be false mass.