Patent Application
20070253885
The following illustrative embodiments are provided to illustrate the disclosures of the present invention. These and other advantages and effects can be apparently understood by those skilled in the art after reading this specification. The present invention can also be performed or applied by other different embodiments. The details of the specification may be modified and varied on the basis of different points and applications without departing from the spirit of the present invention.
Firstly, in the hydroxylamine-oxime recycling system, after the formation of cyclohexanone-oxime, the phosphate inorganic processing solution is isolated and introduced into the steam stripping tower A through a pipe 10. The inorganic processing solution contains phosphate salts, hydroxylamine, water, and organics. The organics includes ketones such as cyclohexanone; ketone oximes, such as cychohexanone oxime; carboxylic acids; alcohols; aldehydes; esters; amines; and hydrocarbons such as toluene, etc.
Secondly, the inorganic processing solution in the steam stripping tower A is introduced into the reboiler B through a pipe 12 for heating, and then reintroduced into steam stripping tower A through a pipe 14. During the process of steam stripping, excess water and undesired organics are expelled from the top of the steam stripping tower A through a pipe 16. Among those, the expelled organics are recovered by cooling. The inorganic processing solution stripped with steam to remove excess water and organic contaminants then flows out from the bottom of the steam stripping tower A through a pipe 18. Subsequently, the composition of the solution is adjusted according to requirement. For example, the solution is delivered to a nitric acid absorbing tower for supplementing nitrate ions so as to carry out the following hydroxylamine synthesis.
The steam used in this steam stripping device is introduced into reboiler B through a pipe 20, thereby heating the inorganic processing solution. Generally, the steam is supplied by a single steam-electricity cogeneration plant in the factory. The steam may be of high pressure steam, middle pressure steam, or low pressure steam, which is not designed according to the required condition of a particular device. Meanwhile the flow of steam is regulated by a control valve 100 to be led into reboiler B. Since the steam is easily overheated during transmission in the present invention, a desuperheating unit C is disposed at the steam inlet of the reboiler B. Cooling liquid, such as boiler feed water, is introduced into the desuperheating unit C through a pipe 22 to lower the temperature of the superheated steam by spraying through a pipe 24. Successively, the cooled steam is introduced into reboiler B so as to prevent adverse influence on the inorganic processing solution caused by superheated steam.
In the steam stripping device for an inorganic processing solution of the present invention, the desuperheating unit disposed at the steam inlet of the reboiler is used to lower the temperature of superheated steam by spraying water when the temperature of the introduced steam becomes too high. After the temperature is lowered, the steam is reintroduced into the reboiler. Thereby, thermal decomposition of organics into other organic compounds, such as organic acids, cyclic compounds, and carbon complexes, in the inorganic processing solution can be avoided. Furthermore, the organic contaminants can also be efficiently removed. In this embodiment, the total carbon content in the steam stripped phosphate inorganic processing solution used in the hydroxylamine-oxime recycling system, based on the total amount of phosphate inorganic processing solution, is preferably not more than 0.03 wt % (300 ppm), preferably not more than 0.02 wt % (200 ppm), further more preferably not more than 0.015 wt % (150 ppm), and most preferably not more than 0.01 wt % (100 ppm); the total amount of cyclohexanone and cyclohexanone-oxime together preferably not more than 0.001 wt % (10 ppm), more preferably not more than 0.0005 wt % (5 ppm), further more preferably not more than 0.0003 wt % (3 ppm), and most preferably not more than 0.0002 wt % (2 ppm).
Additionally, the steam stripping device of the present invention can prevent the denature of inorganic processing solution due to superheating. Accordingly, when the steam stripping device is applied to hydroxylamine-oxime recycling system, not only the efficiency of removing organic contaminants can be enhanced, but also can prevent the denature of inorganic processing solution. Thereby, it can prevent the decreases of catalyst activity and selectivity of hydroxylamine production in the hydroxylamine synthese.
The phosphate inorganic processing solution, after conducting oxime reaction to form cyclohexanone oxime in a hydroxylamine-oxime recycling system and being isolated by extraction, was used. Total carbon, amount of cyclohexanone and cyclohexanone-oxime, and amount of toluene in the solution were analyzed. The results obtained are shown in Table 1.
The phosphate inorganic processing solution was stripped with low pressure steam having 5 kg/cm2 (at 161□) under conditions of atmospheric pressure and 110□ in the steam stripping device of the present invention. When steam stripping was completed, total carbon, amount of cyclohexanone and cyclohexanone oxime, and amount of toluene in the solution were measured. The results are shown in Table 1.
The procedures of Example 1 were repeated except that a steam stripping tower without a desuperheating unit was used. The results obtained are shown in Table 2.
The foregoing detailed descriptions of the embodiments have been discussed for illustrating the features and functions of the present invention but not for limiting the scope of the present invention. Those skilled in the art will appreciate that modifications and variations according to the spirit and principle of the present invention may be made. All such modifications and variations are considered to fall within the spirit and scope of the present invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 095110889 | Mar 2006 | TW | national |
