CN1120465A

CN1120465A - Method and apparatus for cleaning gas in chimney

Info

Publication number: CN1120465A
Application number: CN95104030A
Authority: CN
Inventors: 俞德辉; 塔查斯·多米尼科
Original assignee: Service Protection Environnement Ingenierie Et Construction "speic"
Current assignee: Service Protection Environnement Ingenierie Et Construction "speic"
Priority date: 1994-03-14
Filing date: 1995-03-14
Publication date: 1996-04-17
Also published as: FR2717248B1; FR2717248A1

Abstract

The invention relates to a purification equipment used for flue gas with high temperature and high content of heavy metal, such as the flue gas which comes from a waste (garbage) burning furnace. The equipment comprises a spraying tower (7) in which the flue gas to be purified is transmitted and a loop (12) which pumps water solution through the bottom of the tower (7); furthermore, after being cooled in a heat exchanger (13), the water solution is dropwise injected into the tower again under the temperature lower than the air dew point temperature of the flue gas, so as to intercept acid contamination and at the same time extract heavy metal from the flue gas through a mixed condensation way.

Description

The purification method of flue gas and equipment

The present invention relates to containing water vapor and pollutant, contain the purification of the flue gas of heavy metal and the acid contaminant such as hydrogen halides specifically.For example relate to and come from house refuse, industrial refuse or hospital's waste material (rubbish) burn the purification of the flue gas of (change) stove.

The equipment that can reduce acid contaminant content in waste material (rubbish) the incinerator combustion flue gas has been described in French publication FR2592812.This known equipment comprises the heat exchanger that is placed on the flue, and the heat transport fluid that temperature is lower than the flue gas dew-point temperature is by this heat exchanger, so that make steam in the flue gas in the exchanger surfaces condensation, and acid contaminant is incorporated in the condensed fluid.This equipment can extract heavy metal in the flue gas, especially mercury very satisfactorily.Yet this equipment has some defectives.For the corrosion of anti-flue gas, this heat exchanger has a plurality of expensive impregnated graphite tubulose members.In addition, this equipment must be with its dedusting before flue gas is delivered to heat exchanger, and the logical brush device of a pipeline must be arranged to avoid accumulating blocking channel because of solid residue between tubular element.At last, this equipment is because the maximum temperature that deduster and impregnated graphite tubulose member heat exchanger use is quite low, and is very unaccommodated for handling the high-temperature flue gas that directly comes from waste incineration (change) stove.

The objective of the invention is to overcome these defectives, and a kind of stack gas cleaning equipment proposed, this equipment is built lower than the known device with cost of use, and can also handle high-temperature flue gas, as come from flue gas, especially waste material (rubbish) fusion of appropriate capacity incinerator and the flue gas of vitrifying stove.

The present invention reaches by following equipment, and this equipment comprises that flue gas is transported to spray column wherein; By the lifting aqueous solution at the bottom of the tower and with the more reflooded devices of the aqueous solution, after in heat exchanger, cooling off, under the temperature that is lower than the flue gas dew-point temperature, contact, so that when extracting acid contaminant, from flue gas, extract heavy metal by condensation by mixing with flue gas.

In preferred enforcement of the present invention, this equipment also comprised one in addition before flue gas is delivered to tower, the container of the cooling stack gas that flue gas is passed through, and the aqueous solution is sprayed onto device in the described cooled containers, advantageously extract its solution at the bottom of the tower, extraction point is positioned under the height of the spray water solution extraction point that is sprayed onto in the tower.Like this, extract the aqueous solution in the tower, and it is its spray solution feed of employed pump in the cooled containers is safer, when flue gas is delivered to before the cooling chamber when flue gas do not had dedusting, the aqueous solution that extracts at the bottom of the tower contains the solid residue that comes from flue gas, and its solid residue can be removed with clarifying (purification) device.

Therefore, content of the present invention is the method about purifying flue gas, the step that this method characteristic ground comprises is that flue gas is sent to the direct aqueous solution with dispersion to be contacted, the temperature of the aqueous solution is lower than the flue gas dew-point temperature, extracts heavy metal so that make by condensation by mixing from flue gas when extracting acid contaminant.

Advantageously, flue gas contacts in sprinkling with the aqueous solution of dispersion carries out, and its aqueous solution is extracted out at the bottom of tower, and annotates in this tower with the thin shape that drips after by the heat exchanger that plays cooling effect again.

More advantageously be that the step that the inventive method comprises is to cool off this flue gas by the mode of aqueous solution sprinkling before delivering to flue gas in the tower in the cooled containers that it passes through.

Other characteristics of the present invention and advantage will be embodied among the following embodiment of the invention described in detail, nonrestrictive, and show during with reference to following accompanying drawing, and the situation among the figure is:

-Fig. 1 is the overall pattern of cleaning equipment of the present invention

-Fig. 2 at length shows the represented a part of equipment of Fig. 1.

Equipment shown in Fig. 1 is used to handle the flue gas stream 1 that comes from incinerator 2, and for example this class incinerator is included in the molten chamber of ash under plasma square or the electric burner effect so that make its vitrifying.Pending flue gas is carried some solid particles, the steam that generates when also containing incineration firing, the sour gas such as HCl or HF and organic or inorganic pollutant, especially the temperature of heavy metal (mercury, lead etc.), flue gas that contains high-load is very high, may reach 1250 ℃.

In a kind of enforcement of the present invention, flue gas stream 1 is directly delivered to condensation by mixing processing unit 3 without dedusting, and this unit also is referred to as mixing condenser 3.By the variation scheme, its flue gas is cooled off in advance until the compatible temperature of deduster that reaches and use, and most of at least solid particle is held back, and solid particle is reclaimed by 5 by the filter 4 of special use.

Preferably, as shown in the figure, processing unit 3 comprises the cooled containers 6 that the flue gas that comes from incinerator 2 is passed through, and perhaps if necessary, flue gas is come out from filter 4, also comprises the flue gas of leaving cooled containers 6 to be carried the spray column 7 that go.The temperature of the aqueous solution 8 is kept below the flue gas dew-point temperature, the aqueous solution is sprayed onto in the tower 7 according to mode with the flue gas adverse current.More precisely, adopt the nozzle 9 spray water solution that dispose in stacking mode, so that in tower 7, form multilayer liquid (in a manner known way).Flue gas continues to pass through the aqueous layer of sprinkling and the steam that wherein contained and the aqueous solution 8 thin dripped when contacting and be condensed, and is accompanied by the absorption acid contaminant.In the acidic condensate that obtains, captured most heavy metal.Because the sour gas in the flue gas is dissolved in the solution, the acidity of the formed aqueous solution helps removing heavy metal.

Nozzle 9 is by feed loop 12 feed, and this loop is included in the heat exchanger 13 that 10 places extract the pump 11 of 7 aqueous solution at the bottom of the tower and are positioned at pump 11 downstreams.Valve 14 connect with nozzle in case with the Flow-rate adjustment of each nozzle to desired value.

Assembling heat exchanger 13 is suitable in feed loop 12 carrying out heat exchange between the aqueous solution of circulation and the water in the secondary coolant circuit 15, and its water temperature is lower than the desired temperature of the aqueous solution to be sprayed certainly.Be equipped with a demister 20 in a manner known way on tower 7 tops, this demister 20 is used to hold back and stays in 21 places and leave the drop that the flue gas of tower is taken away.When the loss of material of passing through surpasses the boundary of appointment, by cleaning this dust arrester 20 by valve 42 and nozzle 41 precipitation that city river network 43 links.

Cooled containers 6 is for building the stabilizing material that tower 7 allows to use anti-lower temperature, and this temperature is lower than the flue gas container 6 desired temperature that are in higher temperature.So just reduced the totle drilling cost of this equipment.With one or more nozzles 16 aqueous solution is sprayed onto in the container 6.Preferably, as shown in the figure, these nozzles 16 are by loop 29 feed, and this loop 29 comprises the pump 17 of the aqueous solution 8 in the

extraction tower

7, and 18 places at the bottom of tower promptly are positioned at the minimum point of tower 7 and extract the aqueous solution under the height of aforementioned extraction point 10.Not under the situation through dust removal process in advance, be preferably in and add water clarifier 40 in the loop 29 when flue gas is delivered to tower 7, so that remove the most of solid residue that contains in the aqueous solution 8, these solid residues are tending towards being deposited on tower at 7 the end.In 39 places these solid residues are extracted into unit for treating water 35, but also these solid residues can be delivered to incinerator.The flue gas of cooling is along with the solution that is sprayed by nozzle 16 leaves container 6 in 19 places, so that flow into tangentially in the tower 7 under nozzle 9.

The aqueous solution 8 is most of by closed circulation.Yet when the heavy metal that extracts from flue gas in the aqueous solution or other pollutant levels were very high, discharging loop 23 can adopt decant overflow mode to carry out, and, supply water and 22 can support the supply of (if this thing happens) nozzle 16.These 22 1 sides that supply water link to each other with feed-tank or fire net,, link to each other with opposite side in nozzle 16 upstreams and by point 25 places that non-return valve 26 and pump 17 separate in being positioned on the loop 23 by valve 24.Discharge from tower 7 at the height that is higher than

extraction point

10 and 18 in discharging loop 23, the acid contaminant that this discharging loop energy decant extracts from flue gas, and (if this thing happens) hydrocarbon and suspended material.Supply nozzle 41 water are so that the loss of compensation water solution is especially all the more so under the amount situation of amount above the steam that is condensed that contains in the flue gas of decant.Be equipped with a swash plate 27 at the bottom of the tower that tilts, supply with the compressed air of lower pressures by valve 28, so as before this equipment of starting agitate water solution.

The flue gas of dehydrohalogenation and heavy metal is left tower 7 and is sent to desulfurization unit 30, extracts flue gas with air blast 31 out from its unit 30 again, is discharged in the atmosphere by chimney again.This unit 30 itself is known, in the water inlet of 32 places, advances alkalinity additive at 33 places, so that make alkaline detergent solution.The washings that reduce concentration are arranged treatment unit for waste water 35 in 34 places, this unit also receives the aqueous solution in self-discharging loop 23.Advantageously, owing to the temperature of the flue gas of leaving tower 7 is low, can obtain high desulfurization rate and SO ₂Residual quantity is extremely low, is about several ppm.

Processing unit 35 itself is known, adds precipitation of heavy metals and the necessary additive of other pollutant (as the suspension material) at 36 places, so that the water 38 that reclaims filter cake 37 and handled after filtering precipitate.

At last, the present invention is using sturdy and durablely, not too expensive, can also purify the Halogen flue gas with high-load heavy metal, especially mercury effectively in the time of for ease of maintenaince structure equipment and is the flue gas with high temperature.

Certainly, the present invention is not subjected to the restriction of the embodiment that described.For example, can remove cooled containers 6, the phase I of spray column 7 plays a part identically at that time, also can add desulfurization unit in the spray column eminence, will dispose the separator disk of flue gas and alkaline rinse under the sort of situation.Can use and stream spray column replacement adverse current spray smile tower 7.

Claims

1. purify such as coming from the method that waste material (rubbish) burns the flue gas of (change) stove, this flue gas contains steam and pollutant, especially heavy metal and acid contaminant, such as hydrogen halides, in the method with flue gas cools and send to directly and contact with the acidic aqueous solution that has disperseed (8), the temperature of this aqueous solution is lower than the flue gas dew-point temperature, so that when intercepting and capturing acid contaminant by condensate liquid, from flue gas, extract heavy metal by condensation by mixing, flue gas contacts in spray column (7) with acidic aqueous solution (8) carries out, its acidic aqueous solution (8) extracts at the bottom of tower, be added to this tower by heat exchanger (13) back that is used for cooling off again with the thin shape that drips, it is characterized in that: the cooling of described flue gas is the aqueous solution to be sprayed onto in the cooled containers (6) that the flue gas that is in the tower upstream passes through carry out, and its feature also is to be sprayed onto the aqueous solution in the cooled containers (6) and leaves cooled containers (6) with flue gas and flow in the spray column (7).

2. method according to claim 1 is characterized in that the solution that is sprayed onto cooled containers (6) extracts at the bottom of tower, and by clarifier (40).

3. the cleaning equipment of flue gas, this flue gas contains steam and pollutant, especially heavy metal and the acid contaminant such as hydrogen halides, they come from waste material (rubbish) and burn (change) stove, this equipment comprises the spray column (7) that flue gas is sent into, with extract acidic aqueous solution (8) from the bottom of tower and its aqueous solution is cooled off reflooded device afterwards in heat exchanger (13), the aqueous solution contacts with flue gas under the temperature that is lower than the flue gas dew-point temperature in tower, so that in condensate liquid intercepting acid contaminant, adopt mixing condensation from flue gas, to extract heavy metal, this equipment is characterised in that it also is included in flue gas and delivers to tower (7) the flue gas flue gas cools container (6) that will pass through before, device with spray water solution in described container (6), its feature also is: condensing container (6) is connected with tower (7), so that the flue gas of cooling is left cooled containers (6) with the aqueous solution of the cooled containers (6) of sprinkling, so that flow in the tower (7).

4. equipment according to claim 3, it is characterized in that: the aqueous solution that is sprayed onto in the described container (6) extracted from tower (7) end, extraction point (18) is lower than the extraction point of the aqueous solution (8) that is sprayed onto in the tower (7), and the clarifier (40) by being used for removing the contained solid residue of flue gas.

5. according to the described equipment of arbitrary claim in claim 3 and 4, it is characterized in that it also comprises the dust arrester that is in described spray column (7) upstream.

6. according to the described equipment of arbitrary claim among the claim 3-5, it is characterized in that it comprises a desulfurization unit (30) that is positioned at described spray column (7) downstream.