Here, pressure of steam is given as 7 bar and it is flowing in pipe at temp of 250oC
And the steam is ejected to surrounding at constant pressure and forms water droplet.
The temperature at which it changes to water at constant pressure is defined as saturation temperature.
From the steam table for constant pressure line we can take value ,
We get the saturation temperature or the temperature at which water droplets forming is
Now , for finding the heat rejected per kg we can use stead flow energy equation
h1 enthalpy at 150 oC=2762 kJ/kg and h2 ,enthalpy at 250 oC=2954
Here heat rejected= h2-h1=2954-2762= 191 kJ/kg