Method for Purifying a Gaseous, Liquid or Aerosol Composition Containing at Least One Polluant

Abstract

The invention relates to a method for purifying a gaseous, liquid or aerosol composition, containing at least one pollutant consisting of a volatile inorganic compound (VIC), a siloxane and/or a functional volatile organic compound (Pollution Trap Concept or P.T.C. System).

Claims

1. A method for purifying a gaseous, liquid or aerosol composition, containing at least one pollutant consisting of: at least one volatile inorganic compound selected from carbon dioxide, nitrogen monoxide, nitrogen dioxide, halogenhydric acids, thionyl chloride, sulphuryl chloride, ammonia, halogens, hydrogen sulphide, carbon oxysulphide and sulphur dioxide, and/or at least one siloxane, and/or at least one functional volatile organic compound, said method comprising the following steps: (i) the alkalinisation of said composition to a pH>11 in the presence of a base of general formula M-OH, wherein M represents an alkaline metal, (ii) the putting into contact of the product obtained in (i) with a compound of general formula (I):
R[CH(X)].sub.nCOR.sup.1(I), wherein: R represents: a sulfonyl halide of formula XSO.sub.2R, wherein X represents a halogen, and R represents a C.sub.1-C.sub.20 alkyl group or an optionally substituted aryl group, a halogen, or an OH group, X represents: a halogen, an OH group, a hydrogen, or a COOH group, R.sup.1 represents: a C.sub.1-C.sub.16 alkoxy, a group of formula NHR, wherein R represents a hydrogen atom or a C.sub.1-C.sub.20 alkyl group, a group of formula OR.sup.2 wherein R.sup.2 represents a hydrogen atom, an alkaline metal, an alkaline earth metal or an ammonium group, or a halogen, n represents 1, 2, 3 or 4; to obtain a purified composition, as well as a capture product resulting from the reaction of the at least one pollutant with said base and/or said compound of formula (I); (iii) the separation of said purified composition from said capture product; with the condition that said pollutant does not consist exclusively of hydrogen sulphide, sulphur dioxide, or a functional volatile organic compound carrying a thiol group.

2. The method according to claim 1, wherein said composition contains carbon dioxide and at least one other pollutant consisting of: at least one volatile inorganic compound selected from nitrogen monoxide, nitrogen dioxide, halogenhydric acids, thionyl chloride, sulphuryl chloride, ammonia, halogens, hydrogen sulphide, carbon oxysulphide and sulphur dioxide, and/or at least one siloxane, and/or at least one functional volatile organic compound, said method comprising the following steps: (i) the alkalinisation of said composition to a pH>11 in the presence of a base of general formula M-OH such as defined in claim 1, (ii) the putting into contact of the product obtained in (i) with a compound of general formula (I) such as defined in claim 1, to obtain a purified composition, as well as a capture product resulting from the reaction of the carbon dioxide and of the at least one other pollutant with the base and/or the compound of formula (I); and (iii) the separation of said purified and dry product from said capture product.

3. The method according to claim 2, wherein said composition is a biogas.

4. The method according to claim 2, wherein said capture product is comprised of a first capture product resulting from the reaction of the carbon dioxide with the base, and of a second capture product resulting from the reaction of the at least one other pollutant with the base and/or the compound of formula (I), the first capture product being in particular separated from the second capture product coming from step (iii), the first capture product being more specifically placed into contact, after said separation, with calcium chloride to form calcium carbonate.

5. The method according to claim 1, wherein said composition is an effluent.

6. The method according to claim 1, wherein steps (i) and (ii) are carried out simultaneously.

7. The method according to claim 1, wherein steps (i) and (ii) are carried out in a washing tower, in particular in one single washing tower.

8. The method according to claim 1, wherein: M represents Na or K, and/or R represents chlorine, R.sup.1 represents an OR.sup.2 group, X represents a hydrogen and n represents 1, and/or OR.sup.2 is an OH or ONa group.

9. The method according to claim 1, wherein the functional volatile organic compound is selected from the volatile organic compounds carrying an amine, amide, nitrile, aldehyde, ketone, ester, carboxylic acid, alcohol, thiol, disulphide, thioester group, halogenated volatile organic compounds, phosgene and hydrocyanic acid.

10. The method according to claim 1, wherein step (iii) is followed by a step (iv) of destroying said capture product, in particular in a purification plant, more specifically by aerobic bio-purification.

11. The method according to claim 1, wherein the quantity in moles of pollutant in the purified composition obtained at the end of step (ii) is less than 10%, with respect to the total number of moles of said purified composition.

12. (canceled)

Description

FIGURES

[0153] FIG. 1 represents the diagram of a facility able to implement the method object of the example 3.

[0154] F e and F s correspond respectively to the gaseous flow at the inlet and to the gaseous flow at the outlet.

[0155] R 1 corresponds to the base.

[0156] R 2 corresponds to the aqueous solution of the compound of formula (I).

EXAMPLES

Example 1: Treatment of the Biogas

[0157] 100 m.sup.3 of biogas coming from the methanisation of sludge of the purification plant is treated (absorption and destruction of the polluting compounds of the methanisation). The 100 m.sup.3 of biogas consists of: [0158] 70 m.sup.3 of pure methane (biomethane) (3.123 moles); [0159] 30 m.sup.3 (about 60 kg) of carbon dioxide (CO.sub.2) to be removed and valorised (1.338 moles); and [0160] 0.4 kg of hydrogen sulphide (H.sub.2S) to be removed (11.76 moles).

[0161] Equipment

[0162] The equipment used is as follows: [0163] 800-litre absorption column (column+reservoir), height: 3 m, base surface: 0.28 m.sup.2 (diameter 60 cm), packed with plates, demister at the air outlet; [0164] Circulation of the fluids adjustable from 0 to 25 m.sup.3/H; [0165] Supply valve of pollutant gaseous effluent adjustable from 0 to 1000 m.sup.3/H.

[0166] Reagents

[0167] The compound of formula (I) is in particular monochloroacetic acid or sodium monochloroacetate.

[0168] The quantities of soda and of compound of formula (I) to be used are evaluated below, according: [0169] to the hourly flow rate of the flow of composition to be purified in m.sup.3; [0170] the daily treatment duration; [0171] the concentration of the compounds to be captured in mg/m.sup.3.

TABLE-US-00001 Hourly air flow rate in m3 25.00 Duration of the discharge in hours/day 4.00 Evaluation of the costs Pollutant concentration in Equivalent Units Hourly Daily flow Price of materials noted mg/m.sup.3 of air in ppm mg/m.sup.3 flow in kg in kg/day per kg in (alibaba.com) Carbon dioxide 327,141 588,720 14.72 58.87 Pure reagent 0.41 Hydrogen sulphide 2,876 4,000 0.10 0.40 Pure potash 0.35 Methylmercaptan 0 0.00 0.00 Potash at 30% 0.31 Ethylmercaptan 0 0.00 0.00 Pure soda 0.17 Propanethiol 1 or 2 0 0.00 0.00 Soda at 30% 0.22 Sulphur dioxide 0 0.00 0.00 Javel water 47 0.27 Hydrochloric acid 0 0.00 0.00 Hourly Daily cost cost Base required for the neutralisation in kg (Choice of Soda or Potash) Sodium hydroxide 30% 95.31 381.23 20.97 83.87 Pure soda 28.59 114.37 4.86 19.44 Potassium hydroxide at 30% 132.28 529.11 41.01 164.02 Pure potash 39.68 158.73 13.89 55.56 Compound of formula (I) required for the reaction Dry pure product (in kg) 1.83 7.32 0.75 3.00 Solution at 40% required (in kg) 4.57 18.29 1.31 5.25 Equivalences for comparison with the prior art: Quantities of Javel water 47 Cl required in 7 29 1.93 7.72 the systems of the prior art

[0172] The quantities of reagents, as well as those linked to the prior art methods are calculated with the following stoichiometries:

TABLE-US-00002 Soda or Compound of Javel potash formula (I) 47 ClO.sub.2 Ozone H.sub.2O.sub.2 Pollutant (1 eq.) (eq.) (eq.) (eq.) (eq) (eq.) (eq.) Carbon dioxide 2.1 0.01 0 0 0 0 Hydrogen sulphide 4.2 4.2 5.2 8.5 3.2 12.0 Methylmercaptan 1.1 1.1 8.5 8.2 4.0 8.5 Ethylmercaptan 1.1 1.1 8.5 8.2 4.0 8.5 Sulphur dioxide 2.1 2.0 2.2 2.2 2.2 2.2 Hydrochloric acid 1.0 0 0 0 0 0

[0173] The corresponding costs, as well as those, for the purposes of comparison, of prior art treatments, are listed in the following table:

TABLE-US-00003 Comparison with the methods of the prior art kg kg kg kg kg kg Javel Liquid Ozone soda pure potash pure reagent pure water chlorine via Perhydrol Pollutants to be Molarity Units at 30% soda at 30% potash at 40% reagent 47 dioxide generator 30% treated in kg (in moles) in kg Either soda, or potash By choice In kg In kg In kg In kg Carbon dioxide 1.338.6 58.9 374.8 112.4 524.7 157.4 3.9 1.6 Hydrogen sulphide 11.8 0.4 6.6 2.0 9.2 2.8 14.4 5.8 28.6 31.9 17.6 66.0 Methylmercaptan 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Ethylmercaptan 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Sulphur dioxide 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Hydrochloric acid 0.0 0.0 0.0 0.0 0.0 0.0 Total weight Either soda, or potash. in kg Total in kg according to the Total in kg Comp. of Pure method used Soda Pure Potash Pure form. (I) comp. of Javel at 30% soda at 30% potash at 40% form. (I) 47 ClO.sub.2 Ozone H.sub.2O.sub.2 Sum of the fillers 381.4 114.4 534.0 160.2 18.3 7.3 28.6 31.9 17.6 66.0 Relative prices in kg 0.22 0.17 0.31 0.35 0.32 0.35 0.27 0.89 / 0.41 Estimation of the costs 83.9 19.5 165.5 56.1 5.9 2.6 7.7 28.4 / 27.0 Reaction volume of the washer to be supplemented if 467 necessary (in litres)

[0174] Thus, the treatment with Javel water is 5 times more expensive than the method according to the invention. The treatments with ClO.sub.2 or H.sub.2O.sub.2 are even more expensive, 10 times more expensive than the method according to the invention.

[0175] Operating Procedure

[0176] In the wet well, the calculated quantities of alkaline solution of soda or of potash, then the solution at 40% of the compound of formula (I) are filled in order.

[0177] The additional water is filled, corresponding to 20 volumes of the pure compound of formula (I).

[0178] The reaction medium then displays a value of pH>11.

[0179] The circulation pump is activated then the flow rate valve of the gases is progressively released and controlled at the desired flow rate.

[0180] The end of the reaction is determined and controlled by pH<9.

[0181] The sodium carbonate precipitate is then separated and can be recycled for example in a cement plant.

[0182] Results

[0183] The results obtained are as follows: [0184] The complete removal of H.sub.2S; [0185] The decarbonation (complete removal of the CO.sub.2); [0186] The removal of 4% of water of the methanisation at 40 C. [0187] The total removal of the siloxanes and organochlorines or fluorines if present in a trace state.

[0188] In this example, the method according to the invention made it possible to purify 100 m.sup.3 of biogas which supplied 70 m.sup.3 of pure biomethane, but also to capture and to remove 30 m.sup.3 of carbonic gas and to remove 0.4 kg of H.sub.2S.

[0189] The cost of the treatment according to the method of the invention is as follows: [0190] treatment of the 100 m.sup.3 of biogas: 0.36 per m.sup.3; [0191] for the 30 m.sup.3 of CO.sub.2 present and removed: 1.08 per m.sup.3.

[0192] The treatment of 100 m.sup.3 of biogas supplied 70 m.sup.3 of biomethane equivalent to 680 kW/h of electricity.

[0193] The cost price of the biomethane completely purified according to the method of the invention is 0.054 per kW/h. The cost price in the competing systems is around 0.15 per kW/h.

Example 2: Treatment of a Mixture of Pollutants in Industry

[0194] Equipment

[0195] The equipment used is as follows: [0196] 800-litre absorption column (column+reservoir), height: 3 m, base surface: 0.28 m.sup.2 (diameter 60 cm), packed with plates, demister at the air outlet; [0197] Circulation of the fluids adjustable from 0 to 25 m.sup.3/H; [0198] Supply valve of pollutant gaseous effluent adjustable from 0 to 1000 m.sup.3/H.

[0199] Reagents

[0200] The compound of formula (I) is in particular monochloroacetic acid or sodium monochloroacetate.

[0201] The composition of the effluent to be treated is given in the following table.

[0202] Furthermore, the quantities of soda and of compound of formula (I) to be used are evaluated below, according: [0203] to the hourly flow rate of the flow of composition to be purified in m.sup.3; [0204] the daily treatment duration; [0205] the concentration of the compounds to be captured in mg/m.sup.3.

TABLE-US-00004 Variables in blue to be entered Hourly air flow rate in m.sup.3 500.00 Duration of the discharge in hours/day 10.00 Evaluation of the costs Pollutant concentration in Equivalent Units Hourly Daily flow Price of materials noted mg/m.sup.3 of air in ppm mg/m.sup.3 flow in kg in kg/day per kg in (alibaba.com) Carbon dioxide 288.95 520.00 0.260 2.600 Pure reagent 0.41 Hydrogen sulphide 4.10 5.70 0.003 0.029 Pure potash 0.35 Methylmercaptan 1.07 2.10 0.001 0.011 Potash at 30% 0.31 Ethylmercaptan 49.29 125.00 0.063 0.625 Pure soda 0.17 Propanethiol 1 or 2 0.00 0.000 0.000 Soda at 30% 0.22 Sulphur dioxide 0.27 0.70 0.000 0.004 Javel water 47 0.27 Hydrochloric acid 1.61 2.40 0.001 0.012 Hourly Daily cost cost Base required for the neutralisation in kg (Choice of Soda or Potash) Sodium hydroxide 30% 1.86 18.58 0.41 4.09 Pure soda 0.56 5.58 0.09 0.95 Potassium hydroxide at 30% 2.55 25.50 0.79 7.90 Pure potash 0.76 7.65 0.27 2.68 Compound of formula (I) required for the reaction Dry pure product (in kg) 0.18 1.81 0.07 0.74 Solution at 40% required (in kg) 0.45 4.53 0.13 1.30 Equivalences for comparison with the prior art: Quantities of Javel water 47 Cl required in 4.3 43 1.16 11.60 the systems of the prior art

[0206] The corresponding costs, as well as those, for the purposes of comparison, of prior art treatments, are listed in the following table:

TABLE-US-00005 Comparison with the methods of the prior art kg kg kg kg kg kg Javel Liquid Ozone soda pure potash pure reagent pure water chlorine via Perhydrol Pollutants to be Molarity Units at 30% soda at 30% potash at 40% reagent 47 dioxide generator 30% treated in kg (in moles) in kg Either soda, or potash By choice In kg In kg In kg In kg Carbon dioxide 59.1 2.60 16.55 4.96 23.16 6.95 0.17 0.07 Hydrogen 0.9 0.03 0.49 0.15 0.69 0.21 1.08 0.43 2.14 2.39 1.32 4.95 sulphide Methyl- 0.2 0.01 0.03 0.01 0.04 0.01 0.07 0.03 0.83 0.80 0.39 0.83 mercaptan Ethylmercaptan 10.2 0.63 1.49 0.45 2.09 0.63 3.26 1.30 40.36 38.94 18.99 40.36 Sulphur 0.2 0.01 0.04 0.01 0.06 0.02 0.09 0.04 0.32 0.32 0.29 0.32 dioxide Hydrochloric 0.3 0.01 0.04 0.01 0.05 0.02 0.00 acid Total weight Either soda, or potash..sup. in kg Total in kg according to Total in kKg Comp. of Pure the method used Soda Pure Potash Pure form. (I) comp. of Javel at 30% soda at 30% potash at 40% form. (I) 47 ClO.sub.2 Ozone H.sub.2O.sub.2 Sum of the fillers 18.6 5.6 26.1 7.8 4.7 1.9 43.7 42.4 21.0 46.5 Relative prices in kg 0.22 0.17 0.31 0.35 0.32 0.35 0.27 0.89 / 0.41 Estimation of the costs 4.1 1.0 8.1 2.7 1.5 0.7 11.8 37.8 / 19.0 Reaction volume of the washer to be supplemented 25 if necessary (in litres) The calculation of the reaction volume to be supplemented is calculated in relation to the products at 30% and at 40%

[0207] Thus, the treatment with Javel water is 17 times more expensive than the method according to the invention. The treatments with ClO.sub.2 or H.sub.2O.sub.2 are even more expensive.

[0208] Operating Procedure

[0209] In the wet well, the calculated quantities of alkaline solution of soda or of potash, then the solution at 40% of the compound of formula (I) are filled in order.

[0210] The additional water is filled, corresponding to 20 volumes of the pure compound of formula (I).

[0211] The reaction medium then displays a value of pH>11.

[0212] The circulation pump is activated then the flow rate valve of the gases is progressively released and controlled at the desired flow rate.

[0213] The flow rate of the gases is set to 500 m.sup.3/h. and the flow rate of the circulation pump of the washing solution to 11 m.sup.3/h.

[0214] The unit allowed for an operating duration of 10 hours during which regular controls of the effectiveness verified the absence of pollutants at the outlet of the facility.

[0215] The end of the reaction is determined and controlled by pH<9.

[0216] The sodium carbonate precipitate is then separated and can be recycled for example in a cement plant.

[0217] Optionally, the sodium carbonate can then advantageously be displaced by calcium chloride to obtain calcium carbonate, practically insoluble, according to the reaction:

Na.sub.2CO.sub.3+CaCl.sub.2 CaCO.sub.3+2 NaCl

[0218] Results

[0219] The results obtained are as follows: [0220] The removal of the sulphur compounds; [0221] The decarbonation (complete removal of the CO.sub.2); [0222] The elimination of the hydrochloric acid.

[0223] Furthermore, the capture product (the filtered reaction medium, before discharge) is such that: [0224] pH=8.3; [0225] temperature <30 C., [0226] DCO: 287 mg/l; [0227] DBO.sub.5: 670 mg/l.

Example 3: Continuous Treatment of a Source of Biogas Containing a Mixture of Pollutants in Order to Obtain Purified Biomethane

[0228] Equipment

[0229] The equipment used comprises of the following elements (FIG. 1): [0230] A storage tank for the alkaline solution of soda or of potash; [0231] A storage tank for the solution of the compound of formula (I); [0232] A reactor turbine comprising a compressor, a vaporisation/reaction chamber and a blade turbine; [0233] Two mist nozzles each supplied by a metering pump controlled for the inlet gas flow rate and controlled for pH; [0234] An emulsifier column (diameter 60 cm) with inside packing and pH control probe; [0235] A recovery column with gravity flow (diameter 60 cm) with the outlet of the purified methane comprising a demister; [0236] A separation tray (volume 800 litres) with an overflow; [0237] A buffer tank for the collection of the washing water for control before discharge to the biological purification plant.

[0238] Reagents

[0239] The compound of formula (I) is in particular monochloroacetic acid or sodium monochloroacetate.

[0240] The composition of the effluent to be treated is given below for an average flow rate of 500 m.sup.3/h.: [0241] Methane: 85.2% (426 m.sup.3) [0242] Air: 7% (35 m.sup.3) [0243] CO.sub.2: 4.8% (24 m.sup.3, that is 45 kg) [0244] Various impurities: 2.8% including: [0245] H.sub.2S: 10618 mg/m.sup.3 [0246] Mercaptans: 207 mg/m.sup.3

[0247] (ethanethiol, methanethiol, propanethiol and butanetiol) [0248] Ketones: 198 mg/m.sup.3

[0249] (acetone, 2-butanone) [0250] Siloxanes: 140 mg/m.sup.3

[0251] (trimethyl silanol, tetramethylsilane, siloxane D4) [0252] Alcohols: 71 mg/m.sup.3

[0253] (propanol, butanol, pentanol, isopropylalcohol) [0254] Halogens: 35 mg/m.sup.3

[0255] (di, tri and tetra chloroethylene).

[0256] Furthermore, the quantities of soda and of compound of formula (I) to be used are evaluated below, according: [0257] to the hourly flow rate of the flow of composition to be purified in m.sup.3; [0258] the daily treatment duration; [0259] the concentration of the compounds to be captured in mg/m.sup.3.

[0260] Sodium hydroxide at 30%: 331 kg/h.

[0261] Solution at 40% of the compound of formula (I): 195 kg/h (expressed as sodium monochloroacetate).

[0262] Operating Procedure

[0263] In a storage tank, there is the alkaline solution of soda or of potash.

[0264] In another storage tank, there is the 40% solution at of the compound of formula (I).

[0265] The average flow rate of the inlet flow measured is 500 m.sup.3/h. (8333 litres/minute) and the flow rate of the metering pumps of the washing solution is adjusted as follows according to this inlet flow rate of gases [0266] Alkaline solution: 5.52 ml/minute [0267] Solution of formula (I): 3.25 ml/minute

[0268] These two metering pumps are controlled on the one hand for the gaseous flow rate and on the other hand for the pH probe which must be between 9 and 11.5 (measurement taken on the emulsifier).

[0269] The washing water is continuously drained to the buffer collection tray for correction of the pH if necessary.

[0270] A control of the parameters is carried out before discharge to the biological purification plant. [0271] pH=8.3; [0272] temperature <30 C., [0273] DCO: 287 mg/l; [0274] DBO.sub.5: 670 mg/l.

[0275] Results

[0276] The unit has made it possible for a continuous operation during which regular controls of the effectiveness verified the absence of pollutants at the outlet of the facility.

[0277] The purification results of the biomethane obtained are as follows: [0278] Purification of 426 m.sup.3/h. of biomethane (7100 litres/minute); [0279] The removal of sulphur compounds; [0280] The decarbonation (complete removal of the CO.sub.2); [0281] The removal of the various impurities identified.