Title of Invention

"AN IMPROVED PROCESS FOR THE RECOVERY OF EXTRACTION SOLVENT FORM BRINE SOLUTION"

Abstract This invention relates to an improved process for the recovery of extraction solvent from brine solution. This invention particularly relates to the recovery of N-methylpyrolidone (NMP) and sulpholane from brine solution. The process provides for the recovery of extraction solvents like Sulpholane, N-methylpyrolidone (NMP) from brine solutions i.e solutions containing > 50% water and salt content as high as 30,000 ppm wt. In addition, the invention provides a process for the recovery of extraction solvent by liquid-liquid extraction technique using light polar hydrocarbons like alcohol, ethyl glycol ethers etc., particularly low boiling aromatics hydrocarbons.
Full Text This invention relates to an improved process for the recovery of extraction solvent from brine solution
This invention particularly relates to the recovery of N-methylpyrolidone (NMP) and sulpholane from brine solution.
The solvent extraction process is widely used in the refineries either for the production of light aromatics like benzene, toluene, xylene (BTX) or to refine petroleum streams for particular end uses. Many process used in the refineries based on solvent extraction technologies. The solvents such as Sulpholane, N-methylpyrolidone (NMP) are worldwide used commercially for the above mentioned applications.
For units equipped with sea water condensers, during operation if any leakage of sea water occurs in the line unit, then problem like increase in acid content , chloride content, sediments etc. of extraction solvent arise. This in turn tends to corrosivity of the equipments. Moreover, these impurities results in the fouling of column effecting the extraction efficiency. .
If quantity of water increases tremendously in the extraction solvent as happens quite often in such type of leakage then recovery of solvent from water solution becomes a problem. Distillation can not be used to recover the solvent as the presence of salt in the solvent will corrode the equipments. Removal of salts from the extraction solvent is very difficult problem of separation.
Solvents Sulpholane or NMP are used in the refineries for extraction of aromatics from petroleum feed stocks. In these processes sea water is used in the cooling condenser at the top of solvent recovery column. If some damage occurs in the condenser, the sea water get ingress in to the extraction solvent. Due to this drastic increase in chloride content occurs in the solvent, which in turn corrode the metallurgy of the unit. Removal of chloride is not possible by using conventional methods like distillation.
Several techniques are reported to clean the degraded lean extraction solvent. Chief techniques are distillation, membrane separation, ion-exchange resin,

adsorption etc. But non these techniques is used to recover the extraction solvent from brine solution particularly when water and salt contents are very high.
Prior art available in the literature is about the recovery of extraction solvent from degraded lean solvent stream. However, IIP has developed adsorption process for removal of salt from aqueous NMP. In this process aqueous NMP is first treated with a conditioned anion exchange resin to remove chlorides and any acidity. This is followed by treatment with cation exchange resin to remove added alkalinity. But this process does not work when salt content levels are higher than 5000 ppm. Moreover, additional infrastructure i.e. ion exchange columns are needed for this route. But present invention deals with altogether different problem i.e. recovery of extraction solvent from highly concentrated brine solution. To date no solution of such problem is discussed in the open literature. Also no patent is available. The present invention is a new idea generated in our laboratory.
To the best of our knowledge no literature is available for recovery of solvent from brine solution through extraction route.
The main objective of the present invention is to provide an improved process for the recovery of extraction solvent from brine solution which obviates the drawbacks as detailed above.
Another objective of the present invention is to provide an process for the recovery of extraction solvents like Sulpholane, N-methylpyrolidone (NMP) from
brine solutions i.e solutions containing > 50% water and salt content as high as 30,000 ppmwt..
Still another objective of the present invention is to provides a process for the recovery of extraction solvent by liquid-liquid extraction technique using light polar hydrocarbons like alcohol, ethyl glycol ethers etc., particularly low boiling aromatics hydrocarbons.
The flow diagram of the present invention is shown in Fig.-1 of the drawing accompanying the provisional specificiation.
The light aromatic hydrocarbon (LAH) is introduced through line (1) into the contact zone (B) and feed is introduced from tank (A) via line (2) where the two streams meet counter currently. The contact zone may comprise either a packed column or a plate or a rotating disc contactor. The top and bottom phases, thus produced, are separately withdrawn through lines (3) and (4) respectively.
The top phase which leaves the contacting zone (B) via line (3) enters distillation column (C), where it is fractionated to yield LAH and extraction solvent. The LAH is recycled back through line (5) to line 1 to contact zone (B). Bottom product of distillation column is pure extraction solvent recovered from water solution & collected through line (6) to product tank (D).
The bottom phase obtained from the contact zone (B) is introduced via line (4) to the feed tank (A).
Accordingly the present invention provides an process for the recovery of extraction solvent from brine solution which comprises,
(a) contacting counter currently in a extractor brine(feed) solution containing each of 50 wt% of extraction solvent like N-methyl pyrrolidone -NMP and water and 15000 ppm of NaCI with light aromatic hydrocarbon(LAH) in a ratio of LAH to feed ranging from 1 to 6 by wt at a temperature range of 20 to 60°C to obtain LAH phase (top) and water phase (bottom),
(b) recovering the desired pure extraction solvent and LAH from top phase obtained in step a) by known method,


(c) recycling the recovered LAH obtained in the step b) to contacting zone,
(d) recycling the bottom phase from extractor obtained in step a) to feed tank.
In an embodiment of the present invention the light aromatic hydrocarbon (LAH) used is selected from hydrocarbons like alcohol, ethyl glycol ethers, benzene etc particularly low boiling hydrocarbon.
In another embodiment of the present invention feed used is contaminated extraction solvent containing 50% water and 15000 ppm salt.
In yet another embodiment of the present invention ratio of LAH to feed ratio ranges from 1 to 6 by weight preferably 2 to 5 by weight.
In still another embodiment of the present invention feed and LAH is contacted counter currently in a extractor at a temperature between a 20 and 60°C preferably between 30 and 50°C.
In still another embodiment of the present invention recovery of LAH from top phase of extractor is done by known method such as distillation at a temperature 90 - 150°C preferably at a temperature 100 - 130°C.
In still another embodiment of the present invention bottom phase of extractor recycled back to feed tank
The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention.
Example-1
The liquid-liquid equilibrium data were generated with synthetic mixture of NMP+water+NaCI (50:50+15000 ppm) which was admixed with twice the weight of benzene at 40°C. The liquid phases under equilibrium were formed. Each phase was separated and analysed. The NMP was reduced from 30 gms in feed to 18 gms in water phase. The solubility of NMP being 12 gms in benzene.
Example-2
The liquid-liquid equilibrium data were generated with synthetic mixture of NMP+water+NaCI (50:50+15000 ppm) which was admixed with thrice the weight of Toluene at 40°C. The liquid phases under equilibrium were formed. Each phase was separated and analysed. The NMP was reduced from 30 gms in feed to 18.5 gms in water phase. The solubility of NMP being 11.6 gms in toluene.
Example-3
The liquid-liquid equilibrium data were generated with synthetic mixture of NMP+water+NaCI (50:50+15000 ppm) which was admixed with twice the weight of benzene+hexane (80:20) at 40°C. The liquid phases under equilibrium were formed. Each phase was separated and analysed. The NMP was reduced from 30 gms in feed to 16.4 gms in water phase. The solubility of NMP being 13.6 gms in mixed solvent phase.
Example-4
The benzene was fed in to the bottom of a packed liquid -liquid extraction column at a rate of 4.13 kg/hr where it'was contacted counter currently with the synthetic mixture of NMP+water+NaCI (50:50+15000ppm) at a rate of 1.92 kg/hr flowing from the top of the extraction column. The temperature in the column was maintained at 40°C. The resulting benzene phase (Top) and Water phase (Bottom) were withdrawn at the rate of 4.84 kg/hr. and 1.33 kg/hr. respectively.
The top phase was fed into distillation column operating with bottom temperature of 120°C and top temperature of 80°C. The benzene was recovered overhead and the bottom product as pure NMP.
The main advantages of the present invention are as follows:
- Use of readily available light aromatic hydrocarbon (LAH) stream from refinery / petrochemical units to recover extraction solvent from brine water mixture

- LAH is recycled back during the process
- Feasibility of processing contaminated extraction solvent containing high water and salt content

- During the processing extraction solvent is not subjected to high temperature, thus avoiding the degradation of solvent
- Salt remains with the aqueous phase, thus avoiding corrosion of down stream lines
- No new equipments are required, as extraction solvent recovery can be carried out in the existing extraction units





We Claim :
1. An improved process for the recovery of extraction solvent from brine
solution which comprises,
(e) contacting counter currently in a extractor, brine (feed) solution containing each of 50 wt% of extraction solvent like N-methyl pyrrolidone -NMP and water and 15000 ppm of NaCI with light aromatic hydrocarbon(LAH) in a ratio of LAH to feed ranging from 1 to 6 by wt at a temperature range of 20 to 60°C to obtain LAH phase (top) and water phase (bottom),
(f) recovering the desired pure extraction solvent and LAH from top phase obtained in step a) by known method,
(g) recycling the recovered LAH obtained in the step b) to contacting zone,
(h) recycling the bottom phase from extractor obtained in step a) to feed tank.
2. An improved process as claimed in claim 1, wherein the light aromatic hydrocarbon (LAH) used is selected from hydrocarbons like alcohol, ethyl glycol ethers, benzene, particularly low boiling hydrocarbon.
3. An improved process as claimed in claim 1, wherein ratio of LAH to brine (feed) ranges preferably 2 to 5 by weight.
4. An improved process as claimed in claim 1, wherein brine (feed) and LAH is contacted counter currently in a extractor at a temperature preferably between 30 and 50°C.
5. An improved process as claimed in claim 1, wherein recovery of LAH from top phase of extractor is done by known method such as distillation at a temperature 90 - 150°C preferably at a temperature 100 - 130°C.
6. An process for the recovery of extraction solvent from brine solution substantially as herein described with reference to the examples and drawing accompanying this specification.

Documents:

771-del-2005-abstract.pdf

771-DEL-2005-Claims-(07-10-2011).pdf

771-del-2005-claims.pdf

771-DEL-2005-Correspondence Others-(07-10-2011).pdf

771-del-2005-correspondence-others.pdf

771-DEL-2005-Description (Complete)-(07-10-2011).pdf

771-del-2005-description (complete).pdf

771-DEL-2005-Drawings-(07-10-2011).pdf

771-del-2005-drawings.pdf

771-del-2005-form-1.pdf

771-del-2005-form-18.pdf

771-del-2005-form-2.pdf

771-DEL-2005-Form-3-(07-10-2011).pdf

771-del-2005-form-3.pdf

771-del-2005-form-5.pdf


Patent Number 257678
Indian Patent Application Number 771/DEL/2005
PG Journal Number 44/2013
Publication Date 01-Nov-2013
Grant Date 25-Oct-2013
Date of Filing 31-Mar-2005
Name of Patentee COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH
Applicant Address ANUSANDHAN BHAWAN, RAFI MARG, NEW DELHI-110 001, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 M.O GARG, M.K INDIAN INSTITUTE OF PETROLEUM, MOHKAMPUR DEHRADUN 248005, UTTRANCHAL, INDIA.
2 KHUANNA, GURU INDIAN INSTITUTE OF PETROLEUM, MOHKAMPUR DEHRADUN 248005, UTTRANCHAL, INDIA.
3 PRASAD, B.R. NAUTIYAL S.M INDIAN INSTITUTE OF PETROLEUM, MOHKAMPUR DEHRADUN 248005, UTTRANCHAL, INDIA.
4 NANOTI, DHARAM PAUL INDIAN INSTITUTE OF PETROLEUM, MOHKAMPUR DEHRADUN 248005, UTTRANCHAL, INDIA.
PCT International Classification Number C07C 7/04
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA