We have a hot spot at 22m on our kiln, would it be possible to use a jet of water to cool the shell in this area?

People sometimes do that. However, it causes a significant blemish on the shell and when the water is switched on a significant thermal shock and potential contraction. In general it is better to use fans and/or stop the kiln and repair the refractory lining. If you put a fan close to the shell you may induce the thin section of the lining to coat over and bring the shell temperature down.