In a large pot, combine the beans and enough cold water to cover by 2 inches. Cover and let stand at room temperature overnight. Drain beans and rinse out pot. Return beans to pot and cover with fresh water. Cover and heat to a boil on high. Boil, uncovered, for 10 minutes. Drain.

To a 4- to 5-qt slow cooker, add beans along with the chicken broth, celery, bell peppers, andouille, onion, Cajun seasoning, salt, garlic powder, and bay leaves. Cover with lid and cook on low for 7?8 hours or high for 3?4 hours, until beans are tender.

When done, remove and discard bay leaves. Season with salt and pepper to taste. To serve, spoon beans over the rice and garnish with the green onions.