| 摘要 |
PROBLEM TO BE SOLVED: To provide a seal gas supplying technique for a flare stack, which avoids the explosion of a gas in a diffusion tower surely and reduces the supplying mount of seal gas remarkably while achieving energy saving. SOLUTION: When a combustible gas dispersion valve 6 is opened upon starting the operation of a plant, sudden emergency and the like, the combustible gas is ignited by an igniting burner 9 to born and disperse the same in the top unit of a stripping tower 1. When the valve 6 is opened, seal gas is also supplied. When a given period of time has elapsed after finishing combustion, the supply of seal gas is stopped. An oxygen concentration meter 2 collects gas in the top unit of the stripping tower 1 to measure the concentration of oxygen. Then, the measured value is judged whether the same is higher than a set valueαor not. When the same value is higher than the set valueα, a supplying valve 5 is opened to supply the seal gas until the measured value becomes not higher than the set valueα. When the measured value is not higher than the set valueα, the measured value is compared with that immediately before the last measurement to judge whether the concentration of oxygen is increased or not. When the same is increased, the seal gas is supplied. The producing of explosive mixture is prevented. Invading air into the top unit of the tower can be detected quickly whereby the invasion of air can be prevented with the small amount of seal gas.
|
