You need to pass 13 papers to qualify as an ACCA member. From 2016, ACCA will run four exam sessions per year. Students can sit a maximum of four exams at each exam session, and a maximum of eight distinct exams each calendar year. You could therefore complete all of the exams in 2 years.
However you need to complete 3 years of work experience (training). So it takes minimum of 3 years to complete the ACCA.