As with any program you run, it needs to satisfy the system requirements. For the PS3 emulator, you need:
Intel(R) Core(TM) i7 CPU 920 @ 2.67GHz
Free Hard Drive Space
AMD Radeon HD 7970 Graphics Card or better
Directx 11 installed
You may notice that these system requirements requirements are very intensive but they are necessary as your system needs to be 10 times stronger than the PS3 to run the PS3 emulator. Once you are sure you can run the PS3 emulator (or if you are not, might as well give it a try), download the PS3 emulator here.