TECHNOLOGY OF IODINE EXTRACTING FROM FORMATION AND ASSOCIATED WATER OF OIL AND GAS FIELDS

Abstract

The present invention relates to a method for extracting iodine from an aqueous brine, the method comprising the steps: Providing an aqueous brine containing iodide ions; Heating the aqueous brine containing iodide ions; Adding an acid to the aqueous brine to arrive at a pH value from 2 to 4; Adding an oxidizing agent to the aqueous brine; Desorbing iodine by means of an airflow; Adding a sorbent for chemisorbing the iodine; Crystallizing the iodine; Purifying the iodine under a layer of sulfuric acid; Sublimation of the iodine.

Claims

1. Method for extracting iodine from an aqueous brine, the method comprising the steps: Providing an aqueous brine; Heating the aqueous brine; Adding an acid to the aqueous brine to arrive at a pH value from 2 to 4; Adding an oxidizing agent to the aqueous brine to form iodine from iodide contained in the brine; Desorbing the iodine by means of an airflow; Adding a sorbent for chemisorbing the iodine; Crystallizing the iodine; Purifying the iodine under a layer of sulfuric acid; Sublimation of the iodine.

2. Method according to claim 1, wherein the aqueous brine is formation and associated waters from oil and gas fields.

3. Method according to claim 1, wherein the aqueous brine comprises the iodide ions in an amount of at least 20 mg/l, with respect to the total volume of the aqueous brine.

4. Method according to claim 1, wherein heating the aqueous brine comprises heating to a temperature from 45 to 50 C.

5. Method according to claim 1, wherein the pH of the aqueous brine after adding the acid is from 2.5 to 3.5.

6. Method according to claim 1, wherein the acid is sulfuric acid and/or hydrochloric acid.

7. Method according to claim 1, wherein the oxidizing agent is chlorine or chlorine water.

8. Method according to claim 1, wherein the desorbing is carried out in a vertical column apparatus filled with a desorber packing.

9. Method according to claim 1, wherein the desorbing is carried out with an airflow rate in the range from 105 to 150 m.sup.3/m.sup.3, with respect to the volume of the aqueous brine.

10. Method according to claim 8, wherein a water density of the desorber packing is 60 m.sup.2/m.sup.3, with respect to the vertical column apparatus cross-section square.

11. Method according to claim 1, wherein the sorbent is sodium hydroxide and or iodine-hydrogen and sulfuric acids.

12. Method according to claim 1, wherein the purifying of the iodine under a layer of sulfuric acid is carried out at a the temperature of 100 to 160 C.

13. Reactor system for carrying out the method according to claim 1, comprising: a water heater (2); a tank for storing an oxidizing agent (6); means for carrying out iodine oxidation (8); a desorber (5); an absorption column (15); a crystallizer (19); an iodine melting node (21); and a sublimator (22).

14. Method according to claim 9, wherein a water density of the desorber packing is 60 m.sup.2/m.sup.3, with respect to the vertical column apparatus cross-section square.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0079] In the following, the present application will be described in detail with reference to the figure (drawing). It shall, however, be understood that not all of the preferred features mentioned in the following are necessarily needed for building an inventive device. Rather, one or more of the following preferred features may, separately or in combination, be used, in particular in combination with the above general disclosure of the invention, to realize the inventive method.

[0080] In the reactor system shown in FIG. 1 initial iodine-containing formation water (aqueous brine) is fed into separators of oil and water 1, where, after the separation of oil and solid impurities, it is supplied to the inlet of a water heater 2, where the aqueous brine is heated to a temperature of 45 to 50 C. and is pumped into a raw water tank 3.

[0081] Then the aqueous brine flows through a 1.5 m diameter fiberglass pipesludge collector 9 to a pump inlet 4 and afterwards to the top of a desorber 5 for irrigation of the desorber packing. Before the aqueous brine enters the desorber, the following parts are added to it: iodine stock solution from a tank 6, concentrated sulfuric acid for achieving a pH from 2.0 to 2.5, concentrated sulfuric acid, and chlorine water from an electrolyzer 8 for iodine oxidation.

[0082] Acidified and oxidized oil formation water containing iodine ions goes to the top of the desorber 5 and is evenly distributed over the active section of the column using irrigators. Flows of acidified and oxidized iodine-containing oil water flows down packing 10 and 11 while spreading into individual thin streams. An airflow is blown forming a counter-flow from bottom to the top using a fan 12 with a speed of 1.7-1.85 m/sec against the water streams containing elementary iodine. In the course of this process takes place the desorption (transition) by air of elementary iodine from oil water into gaseous phase through the packing layer. The desorber 5 is a vertical cylindrical device made of titanium with an internal diameter of 2.0 to 3.4 m and a height of 12 to 15 m filled up to 5 m (height) and 2 m (diameter) respectively with a highly effective packing.

[0083] The efficiency of the iodine desorption process depends on the specific surface of the packing used in the desorber, the temperature of the drilling water and the amount of air supplied for iodine blowing. Acidified and oxidized iodine-containing formation water is depleted from iodine as it flows down the packing, and the air supplied from the bottom to the top of the desorption column is enriched with iodine vapor as it rises to the top of the desorption column.

[0084] After iodine extraction, the spent acidified formation water is removed from the lower part of the desorption column through a hydrosealing device that prevents the air from escaping, and then goes to a unit 13 for its neutralization by alkaline solution from the electrolyzer 8 and by lime milk (calcium oxideCaO) supplied to the neutralizing unit 13 until it reaches the value of pH=7.0 to 7.5. Afterwards, the treated and neutralized formation water is sent back to the plant for utilization of formation oil waters with further pumping of these waters into the absorbing horizons of oil wells.

[0085] The iodine/air mixture from the top of the desorber 5 flows through a duct 14 to the bottom of the absorber 15 and spreads in the process of its passing through the grate and packing 16, then it is directed to the upper part of the absorption column 15. Against the iodine-air mixturefrom top to the bottomabsorbent flows down (sodium-hydroxide solution) from the sorbent circulation tank 17, by means of a centrifugal pump 18 to the absorption column irrigator. Chemisorption processes take place on the surface of the packing between iodine and sodium hydroxide solutions. The design of the absorber is similar to that of the desorber and differs only in the height of the column9 to 10 m and the height of the packing (5 m). As the sorbent flows down, the sorbent is enriched with iodine and iodate (the total iodine content), and the iodine gets extracted from the air as it rises up the column. After iodine has been extracted (captured) from it, the air escapes to the atmosphere through an exhaust pipe 19.

[0086] The sorbent solution is continuously circulating as per the following scheme:

K-15->E-17->K-15->E-17

[0087] As the iodine sorbent circulates, it is continuously enriched with iodine, i.e. the concentration of iodide I.sup. and iodate IO.sub.3.sup. ions increases, and the content of sodium hydroxide accordingly decreases.

[0088] Lack of sodium hydroxide is compensated by the addition of a sorbent. For normal operation, the pH of the sorbent should be maintained within 9 to 11. After reaching the concentration of general iodine to 80-120 g/l, the basic part of a sorbent is gradually removed to the crystallizer 19 where the fresh water is continuously supplied from the tank for the purposes of cooling and rinsing.

[0089] When concentrated sulphuric acid and chlorine are continuously added from the tank 19, iodine paste gets extracted, which is fed to the Nutsche Filter 20 and then sent to the iodine melting node under the layer of sulphuric acid 21 or to the iodine sublimator 22 and then for its package 23.

[0090] In order to reduce sulfuric acid consumption, the spent stock solution after the Nutsche Filter 20 is fed to the stock solution receiving tank 6 and then added through the pipeline to iodine-containing water supply to the desorber 5. The iodine paste obtained through the filter is rinsed with the fresh water in the volume equal to the weight of the rinsed iodine (1 kg-1 liter of water) and then dried by suction of air through the iodine paste layer with a vacuum pump.

[0091] The refining device (iodine melter) 21 operates at a the temperature of 120 to 140 C. The temperature is maintained using four 1.5 kW heaters. Temperature control is maintained automatically using contact thermometers. Concentrated sulfuric acid and iodine paste are supplied from above. The acid is supplied from the pressure tank 7 with the force of gravity and the iodine paste is loaded manually.

[0092] Refined iodine is removed from the bottom of the unit through the packing, preventing the ingress of sulfuric acid into the finished product. Waste acid is removed from the side outlet and then used to acidify the initial water. Refined iodine is collected in the finished product collector units made of PTFE.

[0093] Iodine extracted to the collector units is then crushed and packaged per 50 kg into the drums with inserts made of polyethylene terephthalate film. The iodine is then fed into the unit 22 for the purpose of obtaining sublimated iodine and, after drying, is then fed to the packaging machines 23. The sublimated or technical iodine obtained shall conform the international standards in terms of its composition and package and shall be distributed in the following packages: 50 kg, 10 kg, 3 kg, 0.5 kg.

[0094] This technology of iodine production is modern, low-waste and ecologically safe. Waste acidic water from desorber is discharged to a reactor with a stirring device 13, into which the lime milk and alkali from the electrolyzer 8 are fed. Discharge water, after its neutralization with lime milk and alkali to pH 7.0 goes into waste water collector 26 and is then pumped into the waste oil formation water reservoirs.

[0095] In order to prevent harmful emissions of iodine vapor formed at the stages of crystallization, purification (sublimation) and scaling from escaping into the atmosphere, those emissions are driven by a fan 24 to the scrubbing packing 25 where the emissions are captured by a liquid absorber pumped 28 from the tank 27. The yield of the finished product (iodine of AR or LR) using this technology is 85 to 88%.

[0096] The features disclosed in the foregoing description, in the claims and the accompanying drawings may, both separately or in any combination, be material for realizing the invention in diverse forms thereof.