You can use your EOs without an open flame in several ways:
1. Soak a few cotton balls and place them strategically near you. Tuck one into your collage since it may get some viewers. Bring them to/from the office in a ziplock or glass jar (with tight-fitting lid) to keep them fresh for as long as possible.
2. Make a little rice pack and include EOs. Use pretty fabric to brighten your office. Try one as a mug cozy (flat-ish and larger than your favorite mug). The heat from your coffee or tea or just plain hot water will release the scent. Try one as a lower back pillow on your chair. Your body heat will release the scent. I'd make both with removable covers, personally.
3. Use hot water in a mug to add EOs.
4. Put one drop of lemon EO in your drinking water. I do this and it makes a world of difference in my outlook and mood.
(I use a 24 oz SS bottle with one drop of lemon EO.) You could also use flower essences.
5. Use lavender EO neat (straight) as perfume. One drop lightly rubbed between your wrists and then dab your wrists on each side of your neck. Lavender and tea tree EOs are the only ones you can use without diluting. I'd keep a lavender EO in your desk for this purpose since no mixing is required and the effects can be immediate. Otherwise, you can mix up a small amount of any EO and a carrier oil in a tiny glass vial to use whenever you wish. I have a homemade first aid oil (50% sweet almond oil, 25% lavender EO, 25% tea tree EO) in an old "Burt's Bees blemish stick" (glass roll-on container) in my tiny first aid kit.
DD loves this and says she feels better instantly. I think it is the scent that affects her first, but it also helps speed up healing. The same concept can be applied for your emotions/mood. Citrus EOs tend to perk us up, so I'd go for a mix of those in a carrier oil. Citrus EOs break down really quickly compared to other EOs, so either mix up a very small batch at a time or add in something longer lasting...also put a few drops of vitamin E oil for added preservation.
6. The easiest thing to do is to just open the EO bottle and inhale the scent. The scent itself won't linger long, but it's effect will.