Recovery of valuable resources from produced water and coal combustion products

Abstract

The present invention relates to processes employing water produced from wells that, after suitable purification steps, is processed to recover resources that can be used to treat other waste streams, such as flue gases and ashes from combustion of fossil fuels.

Claims

1. A method for producing sodium bicarbonate and ammonium chloride using water produced from oil or gas wells (Produced Water), or water flowing back (Flowback Water) after fracking oil or gas wells, as a source of brine, comprising the steps of: removing oil from Produced Water or Flowback Water in an oil/water separator; after oil removal, evaporating Produced Water or Flowback Water to increase its salinity, forming a high-salinity brine, adding solid sodium chloride if necessary; adding sodium sulfate to precipitate sulfate salts from said high-salinity brine in a first clarifier; adding sodium carbonate to precipitate carbonate salts and metals from said high-salinity brine in a second clarifier; adding ammonia and carbon dioxide to said high-salinity brine; and reacting sodium chloride in the high-salinity brine with the ammonia and carbon dioxide to yield sodium bicarbonate and ammonium chloride.

2. The method of claim 1, wherein the sodium chloride content of the high-salinity brine when reacted is approximately 150,000 ppm.

3. The method of claim 1, wherein the sodium bicarbonate and ammonium chloride are used to remove mercury, sulfur dioxide, nitrogen oxides, and carbon dioxide from fossil fuel combustion flue gas.

4. The method of claim 1, wherein the sodium bicarbonate is used to remove divalent elements from the high-salinity brine.

5. The method of claim 1, wherein sodium bicarbonate and sodium sulfate produced from the treatment of fossil fuel combustion gas are used to remove divalent cations from Produced Water and to provide carbon dioxide.

6. The method of claim 1, wherein chemicals selected from the group consisting of unburned carbon, zeolites, and magnetite are recovered from fly ash and used specifically to pretreat Produced Water as well as for removing other toxic organics from other wastewaters.

7. The method of claim 1, wherein the oil is removed from the Produced Water using a combination of microbubbles and coarse bubbles with a flocculating polymer to float oil out of the Produced Water.

8. The method of claim 1, wherein microbubbles and coarse bubbles are used in combination with solar energy and waste heat to increase the evaporation rate of Produced and Flowback Water.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which:

(2) FIG. 1 is a schematic diagram of the SSP process used to pretreat PW prior to the CP process shown in FIGS. 2 and 3 below.

(3) FIG. 2 is a schematic diagram of the Debang version of the CP.

(4) FIG. 3 is a schematic diagram of the Solvay version of the CP.

(5) FIG. 4 is a schematic diagram of the FGE treatment process that uses chemicals from the CP and provides chemicals for the SSP in FIG. 1.

(6) FIG. 5 is a schematic diagram of the recovery of valuable resources from CCP.

DETAILED DESCRIPTION OF THE INVENTION

(7) While this invention is susceptible to embodiment in many different forms, there is shown in the drawings and will herein be described in detail specific embodiments, with the understanding that the present disclosure of such embodiments is to be considered as an example of the principles and not intended to limit the invention to the specific embodiments shown and described. In the description below, like reference numerals are used to describe the same, similar or corresponding parts in the several views of the drawings. This detailed description defines the meaning of the terms used herein and specifically describes embodiments in order for those skilled in the art to practice the invention.

(8) FIG. 1 shows a schematic diagram of the SSP process used to pretreat PW prior to the CPs shown in FIGS. 2 and 3 below. PW (1) flows into an oil water separator (2) that removes oil (3) and flows oil free PW (4) to an evaporator (5). The preferred method for removing oil from the PW is the use of a combination of microbubbles and coarse bubbles (16), preferably produced by hydrodynamic cavitation, with a flocculating polymer to float oil (3) out of the PW.

(9) Solar energy, supplemented by waste heat (6) as needed, is next used to evaporate PW in evaporator (5) to concentrate the NaCl content of the PW to a level suitable for the CPs shown in FIGS. 2 and 3. As indicated at (16), microbubbles may again be used to enhance the evaporation process.

(10) Sodium sulfate (7), preferably produced from the treatment of FGE in FIG. 4, is then added to the concentrated PW (8), to react with barium, strontium, and radium to produce insoluble sulfate salts (9) that are removed by a first clarifier (10) with the aid of magnetite (17).

(11) Sodium carbonate (12), preferably also from the treatment of FGE in FIG. 4, is then added to the clarified PW (11), forming carbonate salts of calcium, iron, manganese and strontium that may be precipitated out in a second clarifier (13) with the aid of magnetite (17), as indicated at (14). The treated PW provided at (15) is now a highly concentrated brine solution containing mainly sodium chloride that is used in the CP of either of FIG. 2 or 3.

(12) It is preferred that both clarifiers (10) and (13) use the magnetic ballast clarifying techniques disclosed in applicant's co pending application Ser. No. 14/612,635, but this is required for practice of the present invention.

(13) FIG. 2 shows a detailed flow diagram of the Debang version of the CP, where the mainly pure NaCl solution (15) 50,000 ppm is further concentrated if needed by the addition of solid NaCl (21) to the treated PW (15) to achieve saturation. Then ammonia (22) is added to the NaCl solution to produce ammoniated brine that then flows into a carbonating tower (24) that uses carbon dioxide (25) to complete the CP reaction. The result is the production of sodium bicarbonate (26) and ammonium chloride (27) some of which may be sold, some of which can be used to remove mercury from FGE, as discussed below, while some can be recycled (23) back into the CP to add ammonia back into the process.

(14) FIG. 3 is a detailed diagram of the Solvay version of the CP where a relatively clean solution of NaCl from the SSP shown in FIG. 1 (15) is further concentrated if needed by the addition of solid sodium chloride (42). This concentrated NaCl solution is combined with ammonia (44) recovered from the CP or by additional ammonia (43) added to produce an ammoniated brine solution that then flows into a carbonating tower (45) where carbon dioxide (54) is added to produce ammonium chloride (48) and sodium bicarbonate (49). The ammonium chloride solution (48) flows to an ammonia recovery system (46) and the sodium bicarbonate (49) is either sold or converted to sodium carbonate, with the resulting carbon dioxide reused in the CP. Calcium hydroxide (50) is used in the ammonia recovery system (46) where ammonia is formed (44) and reused in the CP process and calcium chloride is either sold or used in FIG. 4 to treat FGE. Sodium bicarbonate (49) is either sold or is treated with waste heat (41) in a reactor (56) to produce carbon dioxide for use back into the carbonating tower (45) and sodium carbonate (57) The sodium carbonate (57) reacts in a reactor (58) with calcium hydroxide (55) from a lime kiln (51) to produce limestone (53) and sodium hydroxide (59).

(15) FIG. 4 is a schematic diagram of the FGE treatment process that uses chemicals from the CP and provides chemicals for the pretreatment of PW (SSP) shown in FIG. 1. FGE (60) flows into a flue gas stack (61) where various reactions take place. First sodium bicarbonate (49) is added to react with sulfur dioxide, carbon dioxide, and nitrogen oxides. Carbon dioxide is removed as sodium carbonate (12) and is used in the SSP (FIG. 1) to react with divalent cations to produce divalent carbonate salts. The sodium bicarbonate (49) also reacts with sulfur dioxide to produce sodium sulfate (7) that is used in the SSP (FIG. 1) to react with barium, strontium, and radium. Calcium chloride (47) from the CP (FIG. 3) is an oxidizer and when added to FGE (60) will convert elemental mercury contained in the FGE (60) into ionic mercury that will adsorb onto fly ash (64) and thereby removed by the fly ash collector system (63). Ammonium chloride could similarly be used to remove mercury from FGE. After treatment, clean emissions (65) result.

(16) FIG. 5 shows the recovery of valuable resources from CCP. CCP (71) first flows into a separator (66) that separates magnetite (67) by magnetic, gravity, or electrostatic methods that are capable of separating magnetite either by its ferromagnetic properties, its density, or its electrical charge. Either dry or wet separation technologies can be used. Next CCP (71) flows into a second separator (68) where unburned carbon (69) is separated by either air (dry system), or froth flotation (wet system). Unburned carbon is less dense than the inorganic components of CCP (71) and therefore can be separated by air flotation. Because unburned carbon is also less dense than water, when mixed with frothing chemicals, principally an organic liquid like diesel fuel, it will float to the surface of the water. Finally remaining CCP (71) flows into a final collector (70) that collects alumino-silica products used for such applications as zeolite manufacture, cement additive, agriculture, adsorbents etc.

(17) While this application has broadly described the inventive processes, not every detail has been described in detail. Those skilled in the art know the individual steps to be performed and equipment suitable for these processes.