Heat the chicken broth in a large saucepot over medium-high heat. Remove any dried leaves of each stalk of lemongrass. Cut three pieces from the bottom of each stalk into 2-inch lengths. Discard the upper two thirds of each stalk.
Add the lemongrass pieces and lime zest to the chicken broth. Bring to a boil, lower the heat, and simmer for 10 minutes. Strain the broth, and return the broth to the saucepot. Add the lime juice and coconut milk. Add the shrimp, and simmer on medium heat for 4 minutes until the shrimp is cooked through.
Garnish each bowl with some of the cilantro and red chili.