Method and system for producing an ultra pure solution of a chemical product from the industrial quality chemical product in liquid form

摘要

The liquid chemical product is fractionated in a distillation device (5, 6, 7) into a contaminated heavy liquid and a purified gas. The purified gas is sent to an absorber (12) where it is put in contact with deionized water from a buffer store (13). The resulting solution is recovered. The absorption and recovery stages can be repeated to obtain the desired concentration in the buffer store The solution contained in the buffer store is cooled or heated in a heat exchanger (15) before it is recirculated to the absorber. The concentration of chemical product and its level in the buffer store are controlled permanently in the buffer store and the amount of chemical product into the distillation column and water into the buffer store are controlled as a function of the concentration and level desired. The chemical product is introduced into the distillation device in liquid and/or gaseous form. The chemical product is NH3, HCl or HF. The chemical product is stored in a storage tank (1) which can contain it as a compressed liquid of industrial quality. The pressure expanding device (2) expands the liquefied gas. The pipe (4) connecting the storage tank to the distillation device contains a valve (3) and the pipe (11) carrying the purified gas from the distillation device to the dissolving device (absorber) contains a valve (9). The distillation device comprises a boiler (5), a distillation column (6) and a condenser (7) fed with cooled water by a pipe (10) with a stop valve (8). The distillation column is packed or has plates. The dissolving device comprises an absorption column (12), a store (13) for deionized water connected to a feed pipe (20) with a stop and/or control valve (19) and a pump (17). This system also includes a heat exchanger (15) on the pipe (14) between the store and the top of the absorption column, and means (18) of extracting solution from the buffer store. The system also includes means of controlling the inlet flows as a function of concentration (22) and the level of solution in the buffer store.