Part Time B.Tech

Evening or distance engineering courses are not valid any more as per the latest supreme court verdict, hence would recommend you to join regular B.Tech course for better career prospects.

Dear,
You can't do B.Tech through distance/part-time or correspondence. However, you can study AMIE course. AMIE is an engineering programme run by the Institution of Engineers, India. This course is specifically meant for people like you who are working after completing Diploma. The institution of Engineers is a central government organisation.
You don't need to go to any college or attend any classes. Find an Institution of Engineers branch in your locality. Use the internet for this. Enrol yourself. Rest, they will guide you. It's a flexible course you can finish papers one by one or as per your wish.

Hello Santosh,
It all depends on a particular college and facilities available in that college. It's not available in all colleges. First check which college is offering it and then seek admission after enquiring about all aspects.

Hello Nisam,
Actually experience is definitely a must. But duration is not fixed. I would advise you to approach your intended college for any clarification.