Gas treatment system and method
阅读说明：本技术 气体处理系统和方法 (Gas treatment system and method ) 是由 瓦莱丽·纳斯塔西 凯瑟琳·格拉西安 于 2019-02-21 设计创作，主要内容包括：本发明涉及一种用于处理污染气体的方法,包括以下步骤：使污染气体在被称为接触器的气/液接触器中循环,然后使污染气体在过滤器单元中循环,该过滤器单元被称为过滤器单元,所述方法包括在接触器中使循环的液体与污染气体相接触,所述循环的液体的温度为2℃至15℃,优选地为5℃至10℃,并且本发明还涉及用于实施所述方法的处理单元,其包括气/液接触器和过滤器单元。(The invention relates to a method for treating a contaminated gas, comprising the following steps: the process comprises contacting a circulating liquid with the contaminated gas in a contactor, the circulating liquid having a temperature of from 2 ℃ to 15 ℃, preferably from 5 ℃ to 10 ℃, and to a treatment unit for carrying out the process, comprising a gas/liquid contactor and a filter unit.)
1. A method for treating a dirty gas, comprising the steps of:
-circulating said dirty gas in a gas/liquid contactor, called contactor, and then
-circulating the dirty gas in a filter unit, called filter unit,
the method is characterised in that it comprises contacting a circulating liquid with the dirty gas in a contactor, the circulating liquid having a temperature of from 2 ℃ to 15 ℃, preferably from 5 ℃ to 10 ℃.
2. The method of claim 1, wherein circulating the dirty gas in the contactor comprises circulating dirty gas in a direction opposite to a direction in which the liquid is circulated in the contactor.
3. The method of claim 2, wherein circulating the dirty gas in a contactor comprises:
-circulating the dirty gas in the same direction as the liquid is circulated in the contactor,
-circulating the dirty gas in a direction opposite to the direction of circulation of the liquid in the contactor.
4. The method according to any one of the preceding claims, characterized in that it comprises:
-injecting dirty gas into a first section of the contactor, referred to as the co-current section, wherein dirty gas circulates in the same direction as the liquid circulates in the first section of the contactor, and
-circulating the dirty gas in a second section of the contactor, called the counter-current section, wherein dirty gas is circulated in a direction opposite to the direction in which liquid is circulated in the second section of the contactor, and
-circulating the dirty gas in a filter unit.
5. A method according to any one of the preceding claims, comprising contacting the foul gas and liquid circulating in the contactor with a heat exchanger.
6. The method according to any one of the preceding claims, comprising circulating a cooling liquid in a heat exchanger, the cooling liquid having a temperature of 2 ℃ to 15 ℃, preferably 3 ℃ to 10 ℃.
7. The method according to any one of the preceding claims, characterized in that it comprises:
-injecting the liquid circulating in the contactor into the second part of the contactor, or into the first part of the contactor, respectively, and then
-re-injecting the liquid that has been circulated in the second part of the contactor into the first part of the contactor or into the second part of the contactor, respectively.
8. A method according to any preceding claim, comprising the step of heating the dirty gas prior to circulating it in the filter unit.
9. The method according to any one of the preceding claims, wherein the method is performed to remove odorous Volatile Organic Compounds (VOCs).
10. The method of any preceding claim, wherein the dirty gas is dirty air.
11. The method according to any one of claims 1 to 9, wherein the dirty gas is biogas.
12. A dirty gas treatment unit, comprising:
-a gas/liquid contactor, called contactor, in which dirty gas is circulated,
-a filter unit, called filter unit, in which dirty gas circulates;
the dirty-gas treatment unit is characterized in that it is designed to perform the method according to any of claims 1-11.
13. The dirty gas treatment unit of claim 12, wherein the arrangement is such that liquid circulating in the contactor is injected into the second section of the contactor, or into the first section of the contactor, respectively, and such that liquid that has been injected into the second section of the contactor is re-injected into the first section of the contactor, or into the second section of the contactor, respectively;
the temperature of the liquid circulating in the contactor is from 2 ℃ to 15 ℃, preferably from 5 ℃ to 10 ℃.
14. The dirty gas treatment unit according to claim 12 or 13, wherein:
-the first part of the contactor, called co-current section, is arranged such that the dirty gas circulates in the same direction as the liquid circulating in the contactor circulates in the first part of the contactor, and
the second section of the contactor, called the counter-current section, is arranged so that the dirty gas circulates in the opposite direction to the direction in which the liquid circulating in the contactor circulates in the second section of the contactor.
Technical Field
The present invention relates to the field of treating gases such as air and biogas, and in particular to the treatment of foul air.
The present invention relates particularly to the removal of odorous and odorous Volatile Organic Compounds (VOCs) from foul gases.
The invention also relates to the pretreatment of biogas.
Background
Biofiltration methods are known in the prior art. These processes require maintenance and control of operating conditions. Furthermore, the air flow to be treated must be continuous and constant.
Gas scrubbing processes and associated purifiers are also known. These treatments and devices may be wastewater based and in such cases the water consumption is considerable and the rate of odor removal is relatively limited. There are also gas scrubbers using organic solvents, which have better removal rates for hydrophobic VOCs. However, the use of organic solvents makes these treatments more expensive and complex. Furthermore, the use of organic solvents requires increased control over the process. There are also chemical scrubbers that have very high removal rates for certain odoriferous compounds, but are practically ineffective for most VOCs.
It is also known to treat dirty air using adsorption filters. The filter requires frequent replacement of the filter media, which makes the process very expensive.
Thermal oxidation processes are also known in the art. These processes require heavy equipment that requires regular maintenance and high maintenance costs.
The publication made by Thakur Prabhat Kumar et al on Research Journal of Chemical Sciences, 2011, Vol.1, pp.83-92 is particularly known in the art. The publication is a scientific review describing the use of biofilters to treat VOCs. It mainly describes the advantages and limitations of biofilters, the difficulties of adapting to large scale biofilters and the parameters to be adjusted to optimize the biofilter function.
Furthermore, publications by Faisal I.Khan and Aloke Kr.Ghoshal on Journal of Loss presentation in the Process Industries, 2000,
It is an object of the present invention to significantly overcome the disadvantages of the prior art methods and devices.
The object of the invention is, inter alia:
-improving the removal of VOCs and odors, especially, but not limited to, odorous VOCs contained in polluted air, and/or
Reducing the consumption of raw materials, and/or
Enabling the treatment of foul gases (especially foul air and biogas) containing high concentrations of VOCs, and/or
Ease of operation and maintenance, and/or
-reduction of energy costs.
Another object of the invention is to provide a method that enables the removal of the following substances in addition:
-odor other than that of odorous VOCs, and/or
-particles, and/or
-dust.
Disclosure of Invention
To meet at least one of the above objects, a method for treating a dirty gas is proposed, comprising the following steps, preferably performed in this order:
circulating the dirty gas in a gas/liquid contactor, called contactor, and then
Circulating the dirty gas in a filter unit, called filter unit, in particular a filter unit that filters by adsorption.
Thus, the method according to the invention comprises an absorption step, generally called a washing step, followed by an adsorption step, called a gas filtration step, whereas the previously described known methods comprise a particle filtration step, followed by a humidification step, followed by a biological treatment step (or biological filtration).
For the purposes of the present invention, the term "foul gas" refers to a gas contaminated with contaminants such as VOCs and/or odorous molecules and/or dust. They may be particularly hydrophilic VOCs, and especially odorous VOCs.
The foul gas may especially be biogas, i.e. methane produced by fermentation of sludge and/or waste, especially contaminated with contaminants as defined above. In this case, the process of the invention makes it possible in particular to purify biogas, i.e. to increase its methane (CH)4) And (4) concentration.
In this patent application, dirty air may be defined as contaminated air, i.e. air with contaminants such as, but not limited to, VOCs (especially odorous VOCs), dust or odors. The dirty air is, for example, but not limited to, air produced by an industrial process.
The method according to the invention is characterized in that it comprises contacting a circulating liquid with the dirty gas in a contactor, the circulating liquid having a temperature of 2 ℃ to 15 ℃, preferably 5 ℃ to 10 ℃.
Once the gas, in particular air, has been subjected to the method according to the invention, it is no longer considered to be dirty.
The gas, in particular air, is considered to have been treated once it has been subjected to the method according to the invention, i.e. once it meets the emission standards.
In the present patent application, the term "contactor" refers to a gas/liquid contactor in the absence of precision.
Gas/liquid contactors are devices well known to those skilled in the art which seek to recover one or more compounds contained in a gas by means of a liquid which is then recovered. Thus, the gas/liquid contactor makes it possible to extract one or more compounds contained in the gas by performing mass transfer from the gas phase, i.e. the dirty gas, to the liquid phase, i.e. the circulating liquid. In practice, the functions of a contactor generally include:
-contacting the liquid with a gas comprising one or more compounds to be recovered, so as to optimally transfer the compounds from the gas to the liquid, and then
-recovering the liquid containing the compound.
The gas/liquid contactor may contain packing in order to increase the exchange surface between the dirty gas and the circulating liquid to facilitate mass transfer (or scrubbing). However, the gas/liquid contactor does not contain any adsorbent solid support designed to have contaminants, such as VOCs and/or odorous molecules and/or dust, contained in the foul gas adsorbed onto its surface. In particular, the gas/liquid contactor does not contain any activated carbon.
According to the present invention, the step of circulating in the gas/liquid contactor involves reducing the amount of contaminants contained in the foul gas, such as VOCs and/or odorous molecules and/or dust, by transferring the foul gas to the circulating liquid. This step of the method is therefore similar to the step of performing a physicochemical scrubbing of the dirty gas using the circulating liquid. Thus, the phenomenon involved is usually absorption.
One advantage of the method of the invention is that it does not comprise a step of biological treatment (biological filtration) of the foul gases.
For the purposes of the present invention, the term "filter unit" refers to a filter unit based on purely physical phenomena, such as adsorption (physisorption). Thus, no chemical conversion of the molecules held by the filter unit takes place; thus, the filter unit is not a VOC or contaminant destroying unit, nor is it a biological unit.
The liquid circulated in the contactor may be water, oil or an organic solvent.
Preferably, the liquid circulated in the contactor may be water, in particular industrial water.
Industrial water can be filtered; preferably, the process water may be filtered at 25 μm to 750 μm, more preferably at 150 μm to 350 μm.
The liquid circulated in the contactor may be water from a refrigeration device designed to cool the water.
In case the liquid circulating in the contactor comes from a refrigeration device designed to cool water, the refrigeration device may be supplied with industrial water.
The flow rate of liquid circulating in the contactor relative to the flow rate of dirty air circulating in the contactor may be less than 20l/m3Preferably less than 10l/m3. This flow rate is commonly referred to by those skilled in the art as the liquid-to-gas ratio.
According to the invention, the circulation of the dirty gas (in particular air) in the contactor may comprise circulation of the dirty gas (in particular air) in a direction opposite to the direction of circulation of the liquid in the contactor.
Thus, according to the first aspect of the invention, the circulation of the dirty air in the contactor may comprise:
-the dirty gas circulates in the same direction as the liquid circulates in the contactor, and
-the dirty gas is circulated in a direction opposite to the direction of circulation of the liquid in the contactor.
Preferably, the step of circulating the dirty gas in the same direction in which the liquid circulates in the contactor is performed before the step of circulating the dirty gas in the opposite direction to the direction in which the liquid circulates in the contactor.
The method according to the invention may comprise:
-injecting dirty gas (in particular air) into a first portion of the contactor, called co-current portion, wherein dirty gas circulates in the same direction as the liquid circulates in said first portion of the contactor, and
-circulating dirty gas (in particular air) in a second portion of the contactor, called counter-current portion, in which dirty gas is circulated in a direction opposite to the direction in which liquid is circulated in said second portion of the contactor, and then
-circulating the dirty gas in the filter unit.
Thus, in other words, the method may comprise:
-circulating the dirty gas cocurrently with the liquid circulating in the contactor, the dirty gas circulating in the same direction as the liquid circulating in the first section, and then
Circulating the dirty gas counter-currently to the liquid circulating in the contactor, the dirty gas circulating in a direction opposite to the direction of circulation of the liquid in the second section, and then
-circulating the dirty gas in the filter unit.
Preferably, the temperature of the dirty gas (especially air) injected into the contactor may be greater than 5 ℃, especially from 5 ℃ to 80 ℃.
More preferably, the temperature of the dirty gas injected into the contactor may be from 15 ℃ to 60 ℃, even more preferably from 35 ℃ to 55 ℃.
According to the first embodiment, the temperature of the dirty gas (in particular air) injected into the contactor may be 40 ℃ to 50 ℃. According to another embodiment, the temperature of the dirty air injected into the contactor may be 25 ℃ to 35 ℃.
According to the invention, the method may comprise contacting the foul gas (especially air) and the liquid circulating in the contactor with a heat exchanger.
The step of contacting the foul gas and the liquid circulating in the contactor with the heat exchanger may be performed wholly or partially simultaneously with the step of circulating the foul gas cocurrently with the liquid circulating in the contactor, in other words in the first section of the contactor.
Preferably, the method may comprise circulating a cooling liquid in the heat exchanger, the cooling liquid having a temperature of from 2 ℃ to 15 ℃, preferably from 3 ℃ to 10 ℃.
More preferably, the temperature of the cooling liquid may be 5 ℃.
Even more preferably, the temperature of the cooling liquid may be equal to the temperature of the liquid circulating in the contactor.
The cooling fluid may be recycled for use in:
reinjection into the cooling liquid circuit, and/or
Reinjection into a contactor, and/or
-reinjection into the circuit for the liquid circulating in the contactor.
The cooling fluid may be water.
Preferably, the cooling liquid may be industrial water.
Industrial water can be filtered; preferably, the process water may be filtered at 25 μm to 750 μm, more preferably at 150 μm to 350 μm.
The cooling liquid may be water from a refrigeration device designed to cool the water.
The cooling liquid may be water from a refrigeration device designed to cool the water.
In case the liquid circulating in the contactor comes from a refrigeration device designed to cool water, the refrigeration device may be supplied with industrial water.
Alternatively, the cooling liquid may be a refrigerant liquid, such as glycol, ethylene glycol or monoethylene glycol (MEG), preferably MEG.
According to the invention, the method may comprise:
-injecting the liquid circulating in the contactor into the second part of the contactor, or into the first part of the contactor, respectively, and then
-re-injecting the liquid that has been circulated in the second part of the contactor into the first part of the contactor or into the second part of the contactor, respectively.
Preferably, the method may comprise:
-injecting the liquid circulating in the contactor into the second part of the contactor, and then
-re-injecting the liquid that has been circulated in the second part of the contactor into the first part of the contactor.
After the reinjected liquid is circulated in the first portion of the contactor, or after being circulated in the second portion of the contactor, the method may include recovering liquid that has been circulated in the contactor.
The recovered liquid that has been recycled in the contactor can be removed for subsequent treatment and/or recycling thereof.
The method may comprise the step of heating the dirty gas (in particular air) prior to circulating the dirty gas in the filter unit.
Preferably, the step of heating the dirty gas is performed after the step of circulating the dirty gas in the contactor.
During this heating step, the dirty gas may be heated to a temperature above 3 ℃, in particular 5 ℃ to 35 ℃, preferably 10 ℃ to 30 ℃.
In this heating step, in a particularly preferred manner, the dirty gas may be heated to a
Preferably, the circulation of the dirty gas in the first portion of the contactor may be in a downward or upward swirling motion around a central region of the contactor, and the circulation of the dirty gas in the second portion of the contactor may be in a substantially straight upward or downward motion in the central region of the contactor.
According to the invention, the circulation of the dirty gas may be at 100m3H to 20000m3H, preferably 250m3H to 10000m3H, more preferably 500m3H to 5000m3Flow rate per hour. In other words, 100m per hour3Up to 20000m3Preferably 250m3To 10000m3More preferably 500m3To 5000m3Injected into the contactor and recovered at the contactor outlet.
The method according to the present invention can be used for removing odorous Volatile Organic Compounds (VOCs).
The method may also be used to remove:
-hydrophilic VOCs, and/or
-odorous hydrophilic VOCs, and/or
-dust, and/or
-particles, and/or
Odorous compounds other than VOCs, and/or
-odorless VOCs.
Preferably, the method is used for treating dirty air, in particular originating from:
-sludge, and/or
Treatment of sludge from water treatment, and/or
A waste water treatment process, and/or
-a waste treatment facility.
The process according to the invention can be used to treat gases, in particular with a content of more than 10mg/m3Preferably 10mg/m3To 1000mg/m3More preferably 50mg/m3To 500mg/m3The concentration of VOC is.
According to the invention, there is also proposed an apparatus for treating dirty gas (in particular air), comprising:
a gas/liquid contactor, called contactor, in which the dirty gas circulates,
-a filter unit, called filter unit, in which the dirty gas circulates;
the dirty-gas treatment unit is characterised in that it is designed to carry out the method according to the first aspect of the invention.
The gas (in particular air) is no longer considered to be dirty once it has passed through the treatment unit.
Gas, in particular air, is considered to be treated once it has passed through the treatment unit described according to the second aspect of the invention.
Preferably, the processing unit according to the invention is designed to carry out the method according to the invention.
According to the invention, the filter unit may be any device known to the person skilled in the art and is preferably an activated carbon filter unit.
According to the invention, the treatment unit may comprise one or more contactors.
The treatment unit is arranged such that the flow rate of the liquid circulating in the contactor is relative to the flow rate of the dirty gas circulating in the contactorThe flow rate can be less than 20l/m3Preferably less than 10l/m3。
The unit for treating dirty gas, in particular air, may be arranged such that the liquid circulating in the contactor, the temperature of which is 2 ℃ to 15 ℃, preferably 5 ℃ to 10 ℃, is injected into the second part of the contactor, or into the first part of the contactor, respectively, and such that the liquid that has been injected into the second part of the contactor, the temperature of which is 2 ℃ to 15 ℃, is re-injected into the first part of the contactor, or into the second part of the contactor, respectively.
The gas/liquid contactor is arranged such that liquid circulating in the contactor is in direct contact with the foul gas circulating in the contactor.
Preferably, the dirty gas injected into the contactor may have a temperature of greater than 5 ℃, in particular 5 ℃ to 80 ℃.
More preferably, the dirty gas injected into the contactor may have a temperature of 15 ℃ to 60 ℃, even more preferably 35 ℃ to 55 ℃.
Particularly preferably, the foul gas injected into the contactor may have a temperature of 40 ℃ to 50 ℃.
The liquid circulated in the contactor may be water, oil or an organic solvent. Preferably, the liquid to be circulated is water, especially industrial water.
A first portion of the contactor, referred to as the co-current portion, may be arranged to circulate the dirty gas in the same direction that the liquid circulating in the contactor circulates in said first portion of the contactor, and a second portion of the contactor, referred to as the counter-current portion, may be arranged to circulate the dirty gas in the opposite direction to the direction that the liquid circulating in the contactor circulates in said second portion of the contactor.
Preferably, the second portion of the contactor may be a central region of the contactor, wherein the circulation of the dirty gas may be in a substantially straight upward or downward motion, and the first portion of the contactor may be a peripheral region of the contactor, wherein the circulation of the dirty gas may be in a downward or upward swirling motion around the first portion.
Preferably, the central region can extend along a central axis of the contactor. For example, the central axis may be the axis of rotation of the contactor.
The second portion of the contact may extend from an outer edge of the central region to an inner edge of the contact.
The unit for treating foul gases, in particular air, may comprise a heat exchanger arranged so that the foul gases and the liquid circulating in the contactor come into contact with the exchange surfaces of the exchanger inside which a cooling liquid is circulated at a temperature of 2 ℃ to 15 ℃, preferably 5 ℃ to 10 ℃.
The cooling liquid may be water or a refrigerant liquid, as defined above in connection with the method of the invention.
According to the invention, the treatment unit may be arranged such that dirty gas, in particular dirty air:
circulating in a contactor, then
-circulating in the filter unit.
Preferably, the dirty gas treatment unit may be arranged such that liquid that has been circulated in the contactor is recovered for its subsequent treatment and/or recycling purposes.
According to the invention, the dirty gas treatment unit may comprise a dirty gas heating element arranged such that dirty gas is heated before entering the filter unit.
The heating element may be any heating device known to those skilled in the art and may in particular comprise a hot wire placed on the circulation path of the dirty gas.
The contactor according to the invention may be any type of contactor known to the person skilled in the art. As an example, the contactor may be of the following type: spray towers, packed towers, bubble-cap towers, plate towers, falling-film towers, or cyclones.
Advantageously, the contactor is a "cyclone exchanger" type contactor.
For treating foul gases, especially foul gasesA unit for air, which can be set up to remove the air contained in the dirty air, in particular containing more than 10mg/m3Preferably 10mg/m3To 1000mg/m3More preferably 10mg/m3To 500mg/m3Volatile Organic Compounds (VOCs) at a concentration of VOCs in the polluted air (particularly odorous VOCs).
The apparatus for treating dirty gas (particularly dirty air) may be arranged so that the dirty gas is at 100m3H to 20000m3H, preferably 2500m3H to 10000m3H, more preferably 500m3H to 5000m3Flow rate circulation of/h.
The means for treating the dirty gas, particularly dirty air, may comprise means for cooling water injected into the contactor and/or heat exchanger.
The cooling device may be any refrigeration device designed to cool water and/or to refrigerate, such as in particular a gas compression and/or gas absorption system and/or a heat pump system.
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