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US 2018/0347812 A1Published application
Device and Method for Treating Flue Gases
AssigneeS. A. Lhoist Recherche et Developpement
InventorsKevin De Bois, Donatien Laloux
Life of this patent
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Abstract
Device (10) for injecting powders into a furnace pipe (500), comprising a chamber (230) connected to a peripheral pipe (220) and, on the other hand, to the said furnace pipe via the said peripheral pipe (220), which comprises a first part (221) of diameter DP1, and a second part (222) of diameter DP2, having a downstream end (222a) and intended to be in communication with the furnace pipe, and a powder conveying pipe (120) which has a diameter DT and a downstream end (121), characterized in that the second part of the peripheral pipe has a length L≥the diameter (DP2) of the second part of the peripheral pipe, and in that the diameter (DT) and the diameter (DP2) are connected by the relationship 0<DP2−DT<½ DT.
Claims22
1:
- Device (10) for injecting a powdered compound for abatement of pollutants of flue gases into a furnace pipe (500), said device comprising:
- a chamber (230) connected to a peripheral pipe (220) and arranged to be connected to a first blowing element (200) arranged to blow a peripheral gas (210) into said chamber and into said peripheral pipe, and to said furnace pipe via said peripheral pipe,
- said peripheral pipe (220) comprising a first portion (221) having a diameter DP1, connected to the chamber, and a second portion (222) having a diameter DP2, opposite the first portion, having a downstream end (222a), and intended to be in communication with the furnace pipe,
- a pipe (120) for transporting powdered compound, intended to be connected to a second blowing element (100) arranged to blow a transportation gas (110) into said transportation pipe, simultaneously to the jet of peripheral gas, said transportation pipe having a diameter DT and a downstream end (121),
- said transportation pipe (120) passing through said first portion (221) of the peripheral pipe concentrically and longitudinally, in such a way that the downstream end (121) of said transportation pipe is located in a secant plane between the first and the second portion of the peripheral pipe,
- characterized in that the second portion of the peripheral pipe has a length L greater than or equal to the diameter (DP2) of the second portion of the peripheral pipe and in that the diameter (DT) of the transportation pipe (120) and the diameter (DP2) of the second portion of the peripheral pipe (222) are linked by the following relationship:
- 0≤DP2−DT<½DT.
4 more elements
2:
- Device for injecting a powdered compound according to claim 1, wherein the downstream end (222a) of the second portion of the peripheral pipe is arranged to be directly connected to the furnace pipe.
3:
- Device for injecting a powdered compound according to claim 1, wherein the peripheral pipe further comprises' a third portion (223) comprising an upstream portion (224) provided with an upstream end (224a) and a downstream portion (225) provided with a downstream end (225a), having a diameter DP3 less than the diameter DP2, said upstream end being intended to be connected to the downstream end of the second portion of the peripheral pipe, said downstream end being intended to be connected to the furnace pipe.
4:
- Device for injecting a powdered compound according to claim 3, wherein the downstream end (225a) of the third portion of the peripheral pipe is arranged to be directly connected to the furnace pipe.
5:
- Device for injecting a powdered compound according to claim 3, wherein said upstream portion (224) of the third portion of the peripheral pipe has the shape of a truncated cone.
6:
- Device for injecting a powdered compound according to claim 1, further comprising:
- a first blowing element (200) connected to the chamber (230) and arranged to blow a peripheral gas (210) into said chamber and into the peripheral pipe (220),
- a second blowing element (100) connected to the transportation pipe (120) and arranged to blow a transportation gas (110) into said transportation pipe,
- a dosing apparatus (130) for dosing powdered compound, connected to a tank of powdered compound and to the transportation pipe, downstream of said second blowing element with respect to a direction of flow of the transportation gas, arranged in order for the transportation gas to drive the dosed powdered compound.
1 more element
7:
- Device for injecting a powdered compound according to claim 6, wherein said first blowing element (200) and the second blowing element (100) allow the adjustment of flow rates in such a way that the flow rates of the first blowing element (200) and of the second blowing element (100) can be adjusted separately.
8:
- Furnace pipe provided with at least one device for injecting a powdered abatement compound according to claim 1.
9:
- Method for treating flue gases in a furnace pipe with a powdered compound for abatement of pollutants of flue gases, comprising:
- injection of a jet of transportation gas having a mass flow rate QT, said jet of transportation gas being intended to transport said powdered abatement compound into said flue gases having a flue gas flow rate QF,
- simultaneously, injection of a jet of gas, peripherally with respect to the jet of transportation gas, forming a jet of peripheral gas having a mass flow rate QP,
- characterized in that said mass flow rate of peripheral gas in relation to said mass flow rate of the flue gases forms a ratio QP/QF between 0.05% and 0.25%.
1 more element
10:
- Method for treating flue gases in a furnace pipe according to claim 9, wherein said transportation gas has a speed VT and said peripheral gas has a speed VP, the speed of peripheral gas VP being between two times and twenty times the speed of the transportation gas VT according to 2VT≤VP≤20VT.
11:
- Method for treating flue gases in a furnace pipe according to claim 9, wherein the mass flow rate of the transportation gas QT added to the mass flow rate of the peripheral gas QP in relation to the mass flow rate of the flue gases QF forms a ratio (QT+QP)/QF between 0.1 and 0.5%.
12:
- Method for treating flue gases in a furnace pipe according to claim 9, wherein the powdered compound is injected at a mass flow rate QA, the mass flow rate of the transportation gas QT in relation to the mass flow rate of powdered compound forming a ratio QT/QA between 5 and 10.
13:
- Method for treating flue gases according to claim 9, characterized in that the injection of the jets of transportation gas and of peripheral gas occurs at the inner face of the furnace pipe.
14:
- Method for treating flue gases according to claim 9, wherein the temperature of the flue gases to be treated is between 850° C. and 1150° C.
15:
- Method for treating flue gases according to claim 9, wherein the speed of the flue gases to be treated is between 2 m/s and 150 m/s, preferably between 3 and 50 m/s, in particular between 5 and 30 m/s.
16:
- Method for treating flue gases according to claim 9, wherein the speeds of the jets of transportation gas and of peripheral gas are adjusted independently of each other.
17:
- Method for treating flue gases according to claim 9, wherein the transportation gas and/or the peripheral gas is air, independently of one another.
18:
- Method for treating flue gases according to claim 9, wherein the flue gases comprise pollutants selected from the group consisting of the acidic gases, said acidic gases including those which are sulphurated and/or halogenated, the heavy metals, the furans, the dioxins and their mixtures.
19:
- Method for treating flue gases according to claim 18, wherein the acidic gases comprise pollutants selected from the group consisting of SO2, SO3, HCl, HF, HBr, and their mixtures.
20:
- Method for treating flue gases according to claim 9, wherein the powdered abatement compound comprises a carbonate, a hydroxide and/or an oxide of an alkaline earth metal selected from the group consisting of calcium and magnesium, or a mixture thereof.
21:
- Method according to claim 9, wherein the powdered abatement compound comprises a calcium-magnesium compound having the formula aCaCO3.bMgCO3.xCaO.yMgO.zCa(OH)2.tMg(OH)2.ul, where l represents impurities, a, b, x, y, z, t and u being mass fractions each between 0 and 100%, with u≤55%, with respect to the total weight of said calcium-magnesium compound, the sum of the mass fractions a+b+x+y+z+t+u being equal to 100% of the total weight of said calcium-magnesium compound.
22:
- Method for treating flue gases according to claim 9, wherein the powdered abatement compound comprises over 50% by weight, in particular over 90% by weight, Ca(OH)2.