CN104474878A - Double-tower double-medium energy-saving high-efficiency flue gas desulfurization dust-removal combined device - Google Patents

Double-tower double-medium energy-saving high-efficiency flue gas desulfurization dust-removal combined device Download PDF

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CN104474878A
CN104474878A CN201410794015.XA CN201410794015A CN104474878A CN 104474878 A CN104474878 A CN 104474878A CN 201410794015 A CN201410794015 A CN 201410794015A CN 104474878 A CN104474878 A CN 104474878A
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tower
flue gas
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dust
gas desulfurization
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赵民
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赵民
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Abstract

The invention provides a double-tower double-medium energy-saving high-efficiency flue gas desulfurization dust-removal combined device. The double-tower double-medium energy-saving high-efficiency flue gas desulfurization dust-removal combined device is provided by analyzing the development and application status of a flue gas desulfurization system and dust-removal equipment of a current thermal power plant, analyzing an environmentally-friendly policy and anticipated demands, analyzing influencing factors of limestone-gypsum wet desulfurization efficiency and energy consumption and a compatibilizing and compatibilizing technological approach and analyzing the application situations of various dust removal technologies. The double-tower double-medium energy-saving high-efficiency flue gas desulfurization dust-removal combined device provided by the invention can be used for achieving the double-tower series connection, double media and the double circulation by combining a wet electric dust-removal tower and an absorption tower together, and can be used for achieving the low energy consumption and the ultralow discharge and reducing the construction cost by respectively adopting limestone and lime as desulfurizing agents.

Description

The two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit of a kind of double tower
Technical field
It is one of main contents of environmental protection work that Air Pollutant Emission is administered; environmental protection cause is pure energy resource consumption type cause; advance the transformation of environmental protection facility technology; while realizing up to standard or minimum discharge; make its energy-saving run; need more energy-conservation green technology, the environmental protection equipment system that reasonable disposition is more energy-conservation, energy-conservation inherently environmental protection.
Under current environmental protection policy, in the face of strict coal steam-electric plant smoke discharge index, the environmental objective of degree of depth pollutant emission reduction will be realized with lower energy penalty, realize the cooperation-removal effect that minimum discharge needs to consider the pollutants such as sulfur dioxide, nitrogen oxide, flue dust, aerosol, acid mist, heavy metal, consider environmental protection and power saving.
Comprehensive analysis uses multiple desulfurizing agent, the various environmental protection equipment feature of comprehensive analysis, the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit of a kind of double tower of the present invention is proposed, this device combines wet-esp and absorption tower, double-column in series, two medium, Two-way Cycle, adopt lime stone respectively, lime makees desulfurizing agent, realize low energy consumption minimum discharge, reduce construction costs.
Technical background
Heat-engine plant desulfurized have burning before, in, rear desulfurization, wherein after burning, flue gas desulfurization is the sulfur method of common commercialization application, wet method can be divided into by operational characteristic, dry method and semidry method three kinds, calcium method is had by desulfurization medium difference point, ammonia process, magnesium processes, Dual alkali etc., commercialization generally adopts technology to be calcium method, coastal have part sea water desulfuration unit, the medium and small following capacity unit of minority adopts other sulfur removal technologies such as ammonia process, along with the requirement of country and local air pollution emission standard limited value improves gradually, original desulphurization system is original dry method particularly, semidry method system can not meet emission request, large quantities of dry desulfurization device transform wet method as, early stage desulfurizer multi-band has gas bypass, the current active service desulfurizer overwhelming majority eliminates gas bypass, partial desulfurization device is provided with GGH, unit operation is provided with booster fan when setting up desulfurizer more.
Lime stone (lime)-gypsum wet flue gas desulfurizing technology is through years development, because desulfuration efficiency is high, technical maturity, system stability, desulfurizing agent relatively easily obtain, by-product utilization rate advantages of higher, become technology the most ripe, practical achievement is maximum, the sulfur removal technology that operation conditions is the most stable, the supporting limestone-gypsum desulphurization system of the overwhelming majority of current China thermal power unit operation.
Domestic electrostatic precipitator technology maturation, power plant boiler common configuration electrostatic precipitator, in recent years along with national environmental protection requires to improve gradually to prevention and control of air pollution, reduce haze, control PM2.5, to the raising gradually of dust emission index request, part power plant carries out all kinds of reconstruction for Capacity Enlargement to original electric precipitation, setting up electric field, increasing specific dust collection area, adopt the technology such as high frequency efficient power supply, switched-mode power supply, flue gas conditioning, traveling electrode, low low temp. electric dedusting, electric bag compound, pure bag-type dust as adopted; After bag-type dust improves windage, indicator of power consumption, the dust concentration of house outlet declines obviously, low temperature dedusting has certain energy-saving effect, the scope of application has limitation, and the dedust innovation of additive method is effect improved, still can not meet dust emission requirement from now on; Wet desulphurization has certain clean result to exhaust gas dust, and operating experience test card bright Gypsum Wet desulfuration spray tower can reach 40%-70% to cigarette flue dust detersive efficiency former after electric precipitation.
" fossil-fuel power plant atmospheric pollutant emission standard " GB13223-2011 requires that on July 1st, 2014 rises, coal-fired boiler in thermal power plant emission limit sulfur dioxide 200 milligram/cubic metre (newly-built 100 milligram/cubic metre), the flue dust 30 milligram/cubic metre of the whole nation except the areas such as Guangxi, Chongqing, Sichuan, Guizhou; " key area " performs the special emission limit sulfur dioxide of atmosphere pollution 50 milligrams/cubic metre, flue dust 20 milligrams/cubic metre; Environmental Protection Department bulletin (2013 No. 14) requires that 19 provinces (district, city), 47 regions and above city Thermal Power Generation Industry coal unit performed the special emission limit of flue dust from 1 day July in 2014; Provincial standard is as " Shandong Province's fossil-fuel power plant atmospheric pollutant emission standard " requirement, existing from 1 day January in 2017 (i.e. non-key area) thermal power generation coal-burning boiler performs emission limit sulfur dioxide 100 milligrams/cubic metre, flue dust 20 milligrams/cubic metre, higher than national standard requirement.
" coal electricity energy-saving and emission-reduction upgrading and transformation action plan (2014-the year two thousand twenty) " (Office of the State Council is sent out (2014) No. 31) explicitly calls for eastern region newly-built Thermal generation unit Air Pollutant Emission concentration substantially to reach gas turbine group emission limit (combustion engine emission limit, namely under benchmark oxygen content 6% condition, flue dust, sulfur dioxide, discharged nitrous oxides concentration is not respectively higher than 10, 35, 50 milligrams/cubic metre), middle part new-built unit in principle close to or reach gas turbine group emission limit, encouragement west area new-built unit is close or reach gas turbine group emission limit, to the year two thousand twenty, eastern region active service 300,000 kilowatts and above public Thermal generation unit, 100,000 kilowatts and provide Thermal generation unit and other Thermal generation unit with good conditionsi for oneself above, after transformation, Air Pollutant Emission concentration reaches gas turbine group emission limit substantially, middle part new-built unit in principle close to or reach gas turbine group emission limit, encouragement west area new-built unit is close or reach gas turbine group emission limit, support that synchronously carrying out atmosphere pollution combination and cooperation removes, and reduces the pollutant emissions such as sulfur trioxide, mercury, arsenic, the action plan that some areas environmental protection, energy conservation department specify or local policy, the environmental protection standard of proposition is higher, and area of application is wider, implements time slot request tighter.
Atmosphere pollution control requires day by day to improve to flue gas emission limit, in order to meet up to standard or minimum discharge, in recent years and a few years from now on various places thermal power plant have a large amount of desulfurizer increase-volume renovation and improving engineering projects, for meeting " key area " sulfur dioxide 50 milligrams/cubic metre, flue dust 20 milligrams/cubic metre, especially meet eastern region titanium dioxide S35 milligram/cubic meter that " action plan " requires, the discharge index requirement of flue dust 10 milligrams/cubic metre, be subject to the restriction of various transformation condition, for obtain the scrap build difficulty of carrying out close to this ultra-clean CER and economic input all larger.
Environmental protection equipment is pure energy consumption equipment, must consider power saving the colleague solving environmental issue, realizes best energy-saving effect with minimum energy consumption; Desulfurizer and cleaner have suitable synergy in desulfurization, dedusting; Active service unit carries out the environmental transformation of pollutant deep removal, also by Reconstruction in field execution conditions, and the various conditionality such as horizontal layout, implement difficulty large, there is many common problems in each power plant in environmental transformation; Needs of production comprehensively analyzes various desulfurization, dust collecting process feature, efficiency and energy losing, and synergy, the various factors such as implementation condition, select a kind of energy-conserving and environment-protective desulfurization and dedusting scheme.
lime stone (lime)-gypsum wet flue gas desulfurizing technical Analysis
As previously mentioned, lime stone (lime)-gypsum wet flue gas desulfurizing technical development for many years, is the sulfur removal technology that technology is the most ripe, desulfuration efficiency is high, system run all right, desulfurizing agent obtain easily, by-product utilization rate is high, business application achievement is maximum; Below to the analysis of this sulfur removal technology, based on smoke absorption double-film theory model (see figure 1).
Number of mass transfer unit NTU is the function of all parameters affecting S02 removal efficiency,
NTU=ln (Yin/Yout)=(K × A)/G, wherein 1/K=1/Kg+H/(K1 φ)
A--improves the mass transfer cross section gross area
The average overall mass transfer coefficient of K--gas phase
The total flue gas mass flow of G--
φ--liquid film strengthens coefficient
K1--improves film mass transfer and divides coefficient
The product improving mass transfer cross section gross area A and the average overall mass transfer coefficient K of gas phase can improve desulfuration efficiency; Under the condition that total flue gas mass flow G is constant, improve serum recycle amount, namely increase liquid-gas ratio (L/G) and not only increase mass transfer surfaces and amass A, too increase and absorb the available total alkali content of S02 and both improve liquid film and strengthen coefficient φ, overall mass transfer coefficient K.
The relation of liquid-gas ratio (L/G) and desulfuration efficiency as shown in Figure 2, curve end improves desulfuration efficiency needs the ratio of the liquid-gas ratio increased to increase, and improves desulfuration efficiency more and more difficult, more and more uneconomical by increase serum recycle amount; Liquid-gas ratio is the major parameter affecting desulfurizer power consumption.
Promote calcium sulfur ratio (Ca/S), affect desulfuration efficiency by improving liquid film enhancing coefficient φ, when undissolved limestone content is increased to certain value, pH value is higher than after 5.7, and lime stone rate of dissolution sharply declines, the raising of desulfuration efficiency slows down slow (see figure 3), the raising of calcium sulfur ratio makes lime stone consumption increase, and runs uneconomical, also affects gypsum purity and recycling, take different PH to obtain double tower circulation and precision processing tower product can be entered first stage tower and react further, improve limestone utilization.
Increase stock tank and increase tower height, increasing solid retention time and gas-liquid contact time, improving S02 and absorb, but affect apparatus cost and performance driving economy simultaneously, original absorption tower is not all possess the transformation condition increasing stock tank and increase tower height.
The selection of nozzle affects desulfuration efficiency with layout, selects the nozzle that the good circulating resistance of atomizing effect is little, optimizes arrangement of nozzles and improves coverage rate, improves film mass transfer and divides COEFFICIENT K 1, and lifting mass transfer surfaces amasss A; Spiral nozzle atomizing effect is better than hollow cone nozzle, but anti-clogging aspect weak effect; It is effective that liquid cylindrical nozzle is wear-resistant, although there is the two contact of liquid gas, liquid-gas ratio is selected higher, owing to being female pipe method of operation, has problems in system reliability.
Various operating experience explanation, it is reliable that pallet through improving and optimize runs, it is the measure that raising absorption tower desulphurizing ability and desulfuration efficiency can be taked, arrange pallet can promote mass transfer surfaces and amass A, play flue gas flow equalizing effect simultaneously, reduce bypass effect when flue gas is washed by spraying layer; Must calculate when selecting dress pallet and select rational aperture and percent opening; Arrange pallet can reduce liquid-gas ratio and run, the energy consumption that the electric energy of saving will increase more than increasing flue gas resistance.
The desulphurization system of domestic early stage construction is all with GGH, and heat exchange improves neat stress temperature, has ensured that chimney heavy corrosion does not occur, and improves flue gas and climbs and increase range of scatter; But GGH has been with problems, a resistance being increased flue gas system, general drag overall, at about 500-1200Pa, strengthens blower fan power consumption; Two is that itself easily blockage problem occurs, on-line rinsing invalid shutdown time serious; Three to be that rotor swinging GGH applies many, but energy consumption is high, comprises drive motors, seal fan, low leakage fan power consumption, height setting-out flushing pump, blow ash power consumption; Four is that GGH leakage cigarette makes neat stress secondary pollution, and make discharge state modulator more difficult in higher level, GGH often leaks the former cigarette of 1%, affects desulphurization system efficiency at least 1%; Five be repair and maintenance costly.Along with chimney anticorrosion technical problem is resolved, remove a kind of trend that swinging GGH becomes energy-saving and emission-reduction transformation, remove GGH and can contribute reduction 20-50mg/m3 clean cigarette S02 content; Domestic at present also have heat-pipe heat exchanger MGGH to apply, and realizes zero leakage, but investment is large, also produce certain resistance, energy-conservation aspect can not show a candle to that to arrange low-level (stack-gas) economizer effective, pollutant emission aspect, improve measurement parameter, improve plume perception, overall control is helped little.
Original unit is set up desulphurization system majority and is provided with booster fan, whether booster fan arranges the impact of system desulfuration efficiency little, although various reducing energy consumption was done to booster fan and power supply, dragging system by multiple power plant, operating experience illustrated that booster fan and the total power consumption of air-introduced machine were far above drawing the blower fan power consumption increasing integration type unit; Arranging booster fan is unreliable factor of having connected on unit air and gas system equipment dependability chain, especially after desulfurization bypass mandatory dismantling, has more highlighted this problem; Increasing implementation in power plant is drawn to increase and is unified, and particularly along with denitration transformation, ultra-clean discharge are transformed, palpus is blower fan boosting and transformation simultaneously, once invests, and realization is drawn to increase and unified.
the selection analysis of desulfurizing agent
Aforementioned lime stone (lime)-gypsum wet flue gas desulfurizing technique desulfurizing agent obtains easily, by-product utilization rate is high, application at most, with regard to lime stone and lime as with regard to desulfurizing agent, because desulfurizing agent consumption is large in practical application, Gypsum Wet is business application mainstream.
Lime has activity of with S02 reacting more better than lime stone, higher dissolution rate, a kind of efficient desulfurizing agent relative to lime stone, once developed in early stage dry method or semidry method system in desulfurization and be widely used as desulfurizing agent, the main component of lime is calcium oxide (CaO), nature does not have natural lime resource, the lime material that to be lime stone (CaCO3) obtain through the roasting of about 1100 celsius temperature a few hours, and quick lime (CaO) becomes white lime (Ca(OH) 2 through digestion); White lime is a kind of highly basic, and solubility and degree of ionization are much larger than lime stone, and lime base FGD system cloud gray model can not affect Ca(OH under higher pH value condition) solubility of 2, pH value general control is at 6.0-7.0, and pH value is more much higher than limestone-based process; Lime or calcium hydroxide are a kind of more expensive raw materials relative to lime stone, and price factor, acquiring way, accumulating condition limit its generally application as heat-engine plant desulfurized dose, and CaCO3 is as desulfurizing agent in current heat-engine plant wet desulfurization many employings; Lime stone or lime are as the wet desulfurization system of desulfurizing agent, process choice, Type of equipment, Operation system setting, requirement for anticorrosion are all close, chemical reaction communicates, accessory substance and dehydration equipment identical, technology application is ripe, enforcement is simple, security of system, good reliability, all can easily obtain than other media as desulfurizing agent, because lime and S02 react more efficient, reach same desulfuration efficiency, when calcium sulfur ratio is close, liquid-gas ratio is the half making desulfurizing agent with lime stone, and serum recycle amount is less, flue gas resistance energy consumption is lower, more energy-conservation.
Theoretically, calcium method desulfurization calcium-base absorbing agent molecule can absorb a SO2 molecule, and the consumption of heat-engine plant desulfurized dose is larger; The molecular weight of lime (CaO) is 56, and the molecular weight of lime stone (CaCO3) is 100, calcium hydroxide (Ca(OH) 2) molecular weight 74, the molecular weight ratio lime stone of lime is almost half as large, and therefore the lime desulfurization amount of unit mass almost doubles than lime stone; Market price aspect, 325 order agstone prices are at 150-200 yuan/ton, and lime price is about more than 2 times of agstone, that is removes the S02 of same quantity, adopt lime and agstone cost of material about the same, lime cost is slightly higher; Use after wet desulfurization system lime slaking, as place restriction also can be selected not design digestive system, directly purchase calcium hydroxide (Ca(OH) 2), calcium hydroxide price is suitable with lime, and consumption is about 3/4 of agstone consumption, and cost of material is higher.
flue gas ash removal technical Analysis
Electrostatic precipitator is the deduster that thermal power plant generally adopts, and its operation principle is that after gas ionization makes powder dust particle charged, charged particle moves under the effect of electric field force, is collected on dust collecting pole plate, falls into ash bucket collect in the effect of rapping power.Domestic electrostatic precipitator technology maturation, equipment resistance is low, and adapt to flue gas changing capability strong, maintenance workload is few, along with environmental protection standard improves dust emission index, in order to realize qualified discharge, part power plant carries out all kinds of reconstruction for Capacity Enlargement to original electric precipitation, the supporting electrostatic dust remover electric field progression of new-built unit is increased to 5 grades or 6 grades, electric precipitation increases electric field, increase specific collection area, build or investment for trnasforming urban land large, efficiency of dust collection requires higher, economic input ratio is larger, the effect obtained is general, and affect by afterbody electric field and frid rapping, there is reentrainment of dust situation, it is a lot of by production scene apparatus arrangement space constraint that this tradition improves transformation, and operating cost is higher, relying on electric precipitation dilatation to realize minimum discharge, to be only applicable to Inlet dust concentration lower, specific dust collection area increases little unit.
Employing high frequency electric source, two-region are powered, many example of modification of control and optimize illustrate that transformation synergistic effect is limited, and also with before electric precipitation design capacity is relevant for its power savings.This kind of transformation adapts to the changeable poor effect of coal-fired ature of coal, and smoke dust discharge concentration can not get ensureing.
Low temperature dedusting technology belongs to flue gas conditioning category, and domestic have part to adopt achievement, is applicable to the power plant using low ash content, low-sulfur coal, higher to coal quality requirements, have acid dew piont corrosion problem in operation, investment is large, adopting the relevant transformation of low-level (stack-gas) economizer, is a kind of effective conservation measures.
Electric precipitation afterbody electric field changes traveling electrode.The positive plate continuous rotary motion of final stage electric field, rotating brush deashing, ash-removal effect is good, effectively reduces reentrainment of dust situation and occurs.Be singly that synergistic effect is limited, the limitation of electric cleaner on fine dust is collected can not fundamentally be resolved.The increase of rotatable parts, improve equipment failure rate, certain factory 300MW unit electric precipitation afterbody electric field changes rotation electrode into has in 1 year two or more electric field to be forced to out of service because of rotating mechanism fault, simultaneously due to rotary part wearing and tearing, improves maintenance cost and workload.
Electricity bag compound, pure bag-type dust can effectively reduce smoke evacuation dustiness, efficiency of dust collection is higher and not by the impact of the dust characteristics such as exhaust gas components, dust content, particle dispersion and dust specific resistance, but it is excessive to there is running resistance, cloth bag needs regularly every 3-5 to change, and operation and maintenance cost is too high.
Wet electrical dust precipitator: the domestic power plant of wet electrical dust precipitator starts to adopt gradually, after being arranged in wet desulfurization system, has vertical and horizontal two kinds of forms, is combined by the wet electrical dust precipitator of vertical replaces demister, also referred to as electrostatic precipitator with desulphurization system.Wet-esp can directly be arranged in top, absorption tower, considers flue gas desulfurization and dedusting, effectively can reduce investment, and saves apparatus arrangement space; Wet electrical dust precipitator is more in metallurgical industry sintering gas disposal achievement, and application comparatively early.Can effectively remove the pollutants such as fine dust in flue gas, aerosol and acid mist.Wet electrical dust precipitator top of electrodes is provided with water injection system, and one is rinse electrode, and two is water smoke is sprayed to electric field add wet flue gas, and water smoke is charged and be atomized further in powerful corona field, and trapping powder dust particle, is trapped by dust collector pole under the driving of electric field force.The wet-esp be combined with wet desulphurization, because flue gas is saturated through spray column washing, need not arrange independently spraying system.Do not have rapping apparatus, only need arrange rinse-system, flushing water forms moisture film on dust collector pole, washes away dust to bottom tank.
Accompanying drawing explanation
Fig. 1 is the function that smoke absorption double-film theory model figure, Fig. 1 describe that number of mass transfer unit NTU is all parameters affecting S02 removal efficiency.
Fig. 2 is the graph of a relation of liquid-gas ratio (L/G) and desulfuration efficiency, Fig. 2 describes the relation of liquid-gas ratio (L/G) and desulfuration efficiency, curve end improves desulfuration efficiency needs the ratio of the liquid-gas ratio increased to increase, and improves desulfuration efficiency more and more difficult, more and more uneconomical by increase serum recycle amount.
Fig. 3 is lime stone and gypsum quality percentage in slurries, Fig. 3 describes the relation of lime stone consumption and desulfuration efficiency, promote calcium sulfur ratio (Ca/S), when limestone content undissolved in desulfurization slurry is increased to certain value, pH value is higher than after certain value, lime stone rate of dissolution sharply declines, and improves desulfuration efficiency more difficult with lifting calcium sulfur ratio (Ca/S).
Fig. 1, Fig. 2, Fig. 3 derive from bibliography " heat-engine plant wet flue gas desulfurization technique handbook " (thoughtful auspicious, Duan Jianzhong, Xue Jianming write, in June, 2006 first edition).
Fig. 4 is the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit sketch of a kind of double tower, and Fig. 4 describes the two main comprising modules of medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit of a kind of double tower of the present invention.
Fig. 5 is thermal power unit boiler tail flue gas system diagram, and Fig. 5 describes the two position of medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit in thermal power unit boiler tail flue gas system of a kind of double tower of the present invention.
Fig. 6 is the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit of a kind of double tower and system diagram, and Fig. 6 describes the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit Major Systems of a kind of double tower of the present invention.
the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit explanation of a kind of double tower
Propose the two medium flue gas desulfurization and dedusting combination unit (as shown in Figure 6) of a kind of double tower based on above-mentioned analysis, every platform unit establishes two spray absorbers to be composed in series double tower Two-way Cycle, every Deethanizer design process 100% exhaust gas volumn; First stage tower adopts lime stone to make desulfurizing agent, and secondary tower adopts lime to make desulfurizing agent; First stage tower gypsum excavationg pump designs according to package unit amount of gypsum, secondary tower gypsum excavationg pump is according to 30% design of package unit amount of gypsum, two-level absorption tower gypsum slurries concentrates underflow through cyclone and enters first stage tower, when secondary tower adopts lime to make desulfurizing agent, through cyclone, solid content 50% thick plaster slurry is entered first stage tower, top stream returns secondary tower; Secondary tower gypsum also directly can drain into vacuum dewatering system, and cyclone top stream returns secondary tower.
First stage tower is greater than 90% design by efficiency, in the former flue gas of absorbing and removing more than 90% SO2, two-level absorption tower adopts efficient desulfurizing agent, 95% design is greater than by efficiency, adjust spraying layer in operation and run the number of plies, realize desulphurization system outlet SO2 concentration up to standard, original single tower desulfurizing fly ash, former absorption tower can be used as first stage tower; First grade absorption tower exhaust pass configuration flue gas sampling analytical equipment, is found out the SO2 assimilation ratio of a secondary tower the best, is used for instructing package unit combustion adjustment by test in operation.
Because this efficient desulfurizing agent of lime selected by secondary tower, at a whole set of desulfurizer end, SO2 concentration, comparatively under low condition, is also easily trapped by calcium hydroxide spray droplet, relative to employing limestone desulfurization, secondary tower liquid-gas ratio is significantly reduced, thus reduce electrical power consumption of water pump and flue gas resistance.
First grade absorption tower makees desulfurizing agent owing to adopting cheapness with the relative lime stone more easily obtained, and is the main region of SO2 absorption, absorbs the SO2 of in flue gas about 90%, and slurry pH value controls according to 5-5.5 adjustment, is beneficial to gypsum generation and lime stone dissolving; Two-level absorption tower adopts the higher lime of absorption efficiency to make desulfurizing agent, pH value can tune to pH value when 6-7(secondary tower adopts lime stone to make desulfurizing agent and controls slightly lower), be beneficial to the absorption of low concentration SO 2, realize SO2 deep removal, ensure the desulfurization high efficiency of package unit; Secondary tower desulfurization total amount only accounts for about 10%, desulfurizing agent consumption (calculating with Ca) only accounts for 10%, and because CaO molecular weight is lower than CaCO3 nearly a times, the amount (weight) removing the CaO that 10% SO2 consumes is CaCO3 consumption 56%, so be unlikely to because desulfurizing agent unit price is high and significantly improve desulfurizing agent purchase cost; The power plant that has ready conditions can arrange lime slaking device, and the power plant of place anxiety also directly can purchase calcium hydroxide, and at this, design comparison is flexible on the one hand.
GGH leaks out and the flue gas through desulfurization is polluted again, for former cigarette SO2 concentration 3000mg/m3 desulphurization system, GGH often leaks out 1%, the just SO2 concentration of contribution 30mg/m3, it is transformation trend that the original GGH of desulphurization system removes, the bypass of current environmental requirement mandatory dismantling, so flue gas system does not arrange GGH, do not establish bypass, first stage tower entrance establishes emergency spray cooling system, main chimney anticorrosion, two and above unit public single-drum chimney time, design maintenance chimney on secondary tower, flue gas analysis sampling apparatus also assorted by maintenance chimney, flue gas has carried out deep desulfuration dedusting, the power plant that horizontal layout satisfies the requirements also can adopt nicotinic acids form of export, first stage tower establishes one deck ridge demister+tubular demister, and ridge demister+electrostatic precipitator (wet electrical dust precipitator) established by secondary tower, two tower oxidation fans can concentrated setting public, preferentially select one-stage centrifugal blower fan, adopt diesel ignition or combustion-supporting unit, sump oil floss hole is set at a secondary tower tower wall sizing compartment liquid level, collect oil slick waste liquid.
In a set of desulphurization system, adopt lime stone, lime respectively as the desulfurizing agent of a secondary tower, not only slurries system interrelated but also relatively independent; Technique, equipment, system, requirement for anticorrosion are close, the equipment such as water supply, flushing, oxidation fan can share completely, two tower chemical reactions communicate, accessory substance and dehydration equipment identical, two kinds of technologies all apply maturation, system security reliability is good, all can easily obtain than other media as desulfurizing agent.
Secondary tower adopts lime to make desulfurizing agent, and because lime and S02 react more efficient, reach same desulfuration efficiency, when calcium sulfur ratio is close, liquid-gas ratio is the nearly half making desulfurizing agent with lime stone; Equally because serum recycle amount diminishes, stock tank volume also reduces relatively; Water balance aspect, slurrying water, mist eliminator flushing water are by main for system at night water source, and the SO2 of secondary tower process accounts for 10% of SO2 total amount in flue gas, and versus primary tower slurrying water consumption is less; Secondary tower temperature is being entered lower than 80 DEG C through the cooled flue gas of first stage tower spray washing, so the evaporation capacity of secondary tower is little more than first stage tower, the concentrated speed of CL+ ion is little, and fraction slurries enters first stage tower with gypsum, play blowdown effect, do not need to go out sewage discharge separately.
Secondary tower gypsum slurries is through cyclone initial concentration, solid content about 50% underflow enters first stage tower, slurries amount only accounts for about 5% of first stage tower gypsum discharge slurries total amount, this part liquid PH is to the pH value higher than first stage tower slurries, but because total amount proportion is less, impact is little, and can improve first stage tower slurries quality.
Below every grade of absorption tower bottom spray layer, one deck alloy pallet is set.Arranging pallet at wet desulphurization absorption tower, is through practice test, improves the technology of the comparative maturity of desulfuration efficiency.Flue gas is by adding gas/liquid mass transfer area A during pallet bubbling, when total exhaust gas volumn G is constant, NTU improves, pallet is set up compared with spray void tower in absorption tower, pallet takies setting height(from bottom) lower than one deck spraying layer, reach same desulfuration efficiency, tray reduces liquid-gas ratio, decreases slurry circulating pump power consumption, although tray adds air and gas system resistance, total power consumption reduces; The resistance that pallet produces, make the increase of train drag overall, reduce the effect of parallel port resistance inequality, in absorbing, smoke distribution is more even, in particular improve the uniformity of flue gas in every first grade absorption tower bottom spray area distribution, flue gas uniform contact in spray droplet and absorption tower.
Adopt double tower Two-way Cycle, and adopt close and different two media to implement flue gas desulfurization, first stage tower, to flue gas bulk processing, to gypsum precision processing, goes out waste water and processes further; Secondary tower, to flue gas precision processing, to gypsum bulk processing, does not process waste water; First stage tower focuses on the amount of sulfur dioxide treatment, and secondary tower is focused on absorbing thoroughly sulfur dioxide; The two medium double circulation desulphurization of double tower makes ultra-clean discharge easier, and energy consumption is dropped to minimum.
Electrostatic precipitator (wet electrical dust precipitator) is set at two-level absorption tower top: wet desulfurization system while desulfurization owing to having collaborative dustproof function to flue gas washing itself, can wash the 40-50% of former cigarette dustiness, the two washing of two-stage tower series connection improves dust removing effects; Flue gas is by after desulfurizing tower twice washing, and dustiness declines further, and dust is combined with droplet better, and dust specific resistance declines, and is more conducive to be captured by during electrostatic precipitator; Electrostatic precipitator has similar operational performance at home, and this layout also has the feature of flue gas naturally sharing current, more need not have the current equalizer of certain resistance at setup of entrances and exits with horizontal wet electric precipitation; Do not need to arrange wet-esp to gather dust kerve and drainage arrangement; Do not need design dress supply-water pump, case; Device does not need to design independently pile foundation; And save the investment of some mechanical demister; Can wet-esp control system be fused in the middle of Desulfurization Control Systems, more concentrate, simplify, efficiently, not need to set up a set of control system.
Under double-tower washing and wet cottrell synergy, can make that neat stress dust concentration is easier is reduced to 5 milligrams/cubic metre, and the aerosol effectively removed in flue gas and acid mist, this is the function not available for other dedusting methods; Also make the operation of former electric precipitation on same unit flue gas system more flexible, discharge more consideration energy-saving runs measure under the prerequisite do not exceeded standard.

Claims (9)

1. the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit of double tower, it is characterized in that wet-esp and absorption tower are combined, double-column in series, two medium, Two-way Cycle, adopt lime stone respectively, lime makees desulfurizing agent, realize low energy consumption minimum discharge, reduce construction costs.
2. the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit of a kind of double tower according to claim 1, is characterized in that every platform unit establishes two spray absorbers to be composed in series double tower Two-way Cycle, every Deethanizer design process 100% exhaust gas volumn; First stage tower adopts lime stone to make desulfurizing agent, and secondary tower adopts lime to make desulfurizing agent; First stage tower gypsum excavationg pump is according to the design of package unit amount of gypsum, and secondary tower gypsum excavationg pump designs according to the 20-30% of package unit amount of gypsum, and two-level absorption tower gypsum slurries concentrates underflow through cyclone and enters first stage tower, also directly can drain into vacuum dewatering system.
3. the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit of a kind of double tower according to claim 1, it is characterized in that first stage tower adopts lime stone that is relatively inexpensive and easy acquisition to make desulfurizing agent, 90% design is greater than by efficiency, in the former flue gas of absorbing and removing about 90% SO2, be the main region that SO2 absorbs, the quantity of important requirement process, improves efficiency under certain energy consumption, slurry pH value controls according to 5-5.5 adjustment, is beneficial to gypsum and generates and lime stone dissolving.
4. the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit of a kind of double tower according to claim 1, it is characterized in that secondary tower has selected lime to make desulfurizing agent, two-level absorption tower adopts the more efficient desulfurizing agent of absorption efficiency, be greater than 95% design by efficiency, pH value can tune to 6-7, is beneficial to the absorption of low concentration SO 2, in secondary tower uptake zone, SO2 concentration, comparatively under low condition, also thoroughly can be trapped by calcium hydroxide spray droplet, realize SO2 deep removal.
5. the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit of a kind of double tower according to claim 1, it is characterized in that design desulphurization system time do not adopt any absorption tower close to 100% high efficiency, but superposed by the double-column in series efficiency higher by efficiency, the high-efficiency low energy consumption realizing package unit runs, and the adjustment two tower spraying layer that is in operation runs the number of plies, realize desulphurization system outlet SO2 concentration up to standard, found out the SO2 assimilation ratio of a secondary tower the best by test.
6. the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit of a kind of double tower according to claim 1, it is characterized in that two-level absorption tower adopts lime to make desulfurizing agent, secondary tower liquid-gas ratio is significantly reduced relative to employing lime stone, thus reduce electrical power consumption of water pump and flue gas resistance, ensure the desulfurization high efficiency of package unit, and energy consumption has been dropped to minimum.
7. the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit of a kind of double tower according to claim 1, it is characterized in that flue gas is by after desulfurizing tower twice washing, dustiness declines further, dust is combined with droplet better, dust specific resistance declines, and is more conducive to droplet and is captured by during electrostatic precipitator.
8. the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit of a kind of double tower according to claim 1, it is characterized in that the two washing of two-stage tower series connection improves dust removing effects, wet electrical dust precipitator is set at two-level absorption tower top as electrostatic precipitator and mechanical demister synergy, gives full play to wet desulfurization system to demist dustproof function after flue gas washing.
9. the two medium energy-saving heavy duty detergent flue gas desulfurization and dedusting combination unit of a kind of double tower according to claim 1, it is characterized in that top, absorption tower arranges wet electrical dust precipitator, be conducive to flue gas naturally sharing current, resistance is low, be arranged on absorption tower and reduce the mechanical demister number of plies, wet-esp is not set and gathers dust kerve, drainage arrangement and with supply-water pump, case, by wet-esp control system and Desulfurization Control Systems integrated design, share pile foundation with absorption tower, more concentrate, simplify, efficient.
CN201410794015.XA 2014-12-21 2014-12-21 Double-tower double-medium energy-saving high-efficiency flue gas desulfurization dust-removal combined device Pending CN104474878A (en)

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