A turkey or chicken chili in a thermos helped me survive similar work environments. Carbs are good if you're doing a lot of heavy work, so sandwiches are a good idea especially if you use real fillings rather than typical deli lunch meat. Throw some seasoned chicken breasts in a crock pot on low for 6-8 hours and then shred it with a couple forks and use that for an even layer of protein on your sandwiches. I usually toss mine in a little mayo and hot sauce.

If you have protein powder around, you can make your own protein bars without all the processed junk in them and keep one wrapped in saran wrap or tin foil close by for your breaks ( I used to keep one in a pocket, even though it got warm it was better than nothing). They also make shaker bottles with storage on the bottom that you could keep nuts and dried fruit or a protein bar in. Most places will let you have water closer than a break room, so that could come in handy.