Clean Air Sustainable Recycling

Transcription

1 Clean Air Sustainable Recycling

2 Cleaning flue gases to preserve air quality: a major challenge for Waste-to-Energy plants and other industries In this context, industries are facing a double challenge: Comply with an increasingly binding legislative and regulatory framework. Industrial flue gases must meet the requirements at the legal standards on acid gas emissions (hydrochloric acid, sulphur dioxide, hydrogen fluoride and nitrogen oxides), heavy metals and micro pollutants, dioxins and furans. Achieve performance which is not only economical but also socially and environmentally respectful. Best Available Techniques : The European reference The Industrial Emissions Directive IED 2010/75/EU requires that licenses to operate industrial facilities in various sectors take into account the reduction and control of their environmental impact. To allow this, a European Office based in Seville defined the Best Available Techniques for each industrial sector. These BATs are described in the Best available techniques REFerence (BREF) documents, which are becoming the reference for providing information regarding the emission levels that can be achieved using specific techniques. The dry sodium bicarbonate system is given as one of the BATs. SOLVAir Solutions backed by SOLVAY The SOLVAir Solutions were developed and patented by SOLVAY, an international group active in chemistry. SOLVAir mission is to offer and continuously develop competitive and sustainable environmental solutions used for air emission control and associated waste, through a range of products, services, technologies and treatment systems. SOLVAY is the leading producer of sodium bicarbonate worldwide and in Europe, with seven BICAR production sites in Europe. 2 / SOLVAir

3 BICAR : Production in Europe BICAR applications are numerous: health, hygiene, detergents, disinfection, food and feed, water treatment, paper, powder extinguishers, pharmaceuticals and many more. Torrelavega (SP) Dombasle (FR) Bernburg (DE) Rheinberg (DE) Rosignano (IT) Devnya (BG) SOLVAir : the complete solution Sodium Bicarbonate Raw flue gases Clean air Clean flue gases Residual Sodium Chemicals Sustainable recycling Recyclable product Towards zero waste Clean air Efficiency: the SOLVAir bicarbonate dry process allows very high abatement rates, which respect the strictest emission limits at an excess of BICAR down to 10 %. It eliminates sulfur oxides (SOx), chlorhydric acid (HCl) and fluorhydric acid (HF). Combined with activated carbon, it adsorbs heavy metals, dioxins and furans. Economy and simplicity: BICAR is a very effective reagent. Thanks to its simplicity, the SOLVAir bicarbonate process requires low investment and limited maintenance costs. The quantity of Residual Sodium Chemical (RSCs) is reduced and there is no need for liquid effluent treatment. Total safety of use: BICAR is a neutral powder. It is non-corrosive, non-irritant and non-toxic, and can be handled easily and safely. Sustainable recycling The SOLVAir RSC Recycling Solutions make it possible to treat and recycle the Residual Sodium Chemicals coming from the flue gas cleaning. SOLVAir / 3

4 The SOLVAir bicarbonate process: dry injection of BICAR The sodium bicarbonate BICAR, in contact with the flue gases, effectively neutralizes the acids. Chemical reactions (netto reactions with massic ratio) NaHCO NaHCO NaHCO NaHCO Residue/sorbent ratio HCl 1 SO2 1 ½ O2 SO3 1 HF 1 NaCl Na2SO Na2SO NaF CO2 H2 O CO2 H2 O CO2 H2 O CO2 H2 O Thermal activation 2 NaHCO3 4 / SOLVAir Na2CO3 CO2 H2 O

5 Thermal activation of BICAR through the microscope Inside the flue gases, BICAR is activated and becomes high specific surface sodium carbonate. This transformation is the key reaction wich gives the SOLVAir bicarbonate process its excellent acid neutralization performance. Sodium bicarbonate before thermal activation Activated sodium carbonate Temperature The efficiency of BICAR and the SOLVAir bicarbonate process are optimal between 140 C and 300 C. Outside this temperature range, contact the SOLVAir team to define if BICAR can be used. 140 C 300 C SOLVAir / 5

6 Clean air Effective and simple, the SOLVAir Bicarbonate Solution is a dry sorbent injection process for air emission control. SNCR (optional) Energy Recovery Electricity Steam HCI Waste SO x Clean gas SOx, HCI, HF Role of the bag filter The acid neutralization reaction begins as soon as BICAR is in contact with the acid gases. With a bag filter, the sodium bicarbonate forms a homogeneous layer on the whole filtrating surface (filtration cake). This allows neutralization of the acid gases efficiently while complying with the strictest emission limits and optimizing BICAR consumption. 6 / SOLVAir

7 Comply with 2010/75/EU De-dusting (optional) Milled Sodium Bicarbonate Adsorbent NH 3 Reactor Bag Filter SCR DeNO x Heat Recovery (recommended) Stack Fly ash Residual Sodium Chemicals Towards Zero Waste Step 1 1 Step 3 3 Step 5 5 To further enhance recycling of residues, a first step of de-dusting is recommended prior to neutralization. Step 2 2 The ground sodium bicarbonate BICAR is injected into the flue gas to neutralize the acids present in the gas, particularly: hydrochloric acid (HCl) sulphur oxides (SO X ) hydrogen fluoride (HF) Together with activated carbon or lignite coke, the process allows adsorption of heavy metals and organic micro pollutants. The solid Residual Sodium Chemicals (RSCs) resulting from the neutralization are captured by the bag filter, ready for sustainable recycling. Their main components are sodium chloride, sodium sulphate, sodium fluoride and sodium carbonate. Step 44 A catalytic DeNO X device allows the reduction of NO X below the limit imposed by the most severe legislation. Thanks to the excellent SO X removal efficiency and adequate operating temperature, reheating of the gases is not necessary. A heat exchanger prior to the stack is recommended to increase marketable energy by improved recovery efficiency. Step 6 6 The clean gases are sent to the stack. The SOLVAir process can easily be adapted to comply with future, more severe legislation regarding emission limits. Efficient and so simple The SOLVAir Bicarbonate process features a unique combination of pure simplicity and excellent cleaning performance. Thanks to its thermal activation, the milled Sodium Bicarbonate BICAR succeeds in achieving the highest abatement rates of acids with a very low excess. This result is achieved by a fully dry system, with nothing other than a silo, an injection system and a filter as equipment. Too simple to be true? Hundreds of SOLVAir users witness the efficiency of its performance everyday! SOLVAir / 7

8 Clean air with a simple and safe process A few operating settings will allow the optimization of mitigation rate Milled BICAR particle size The particle size distribution is a key element in the SOLVAir Bicarbonate process. The finer the grains, the larger the contact surface: efficiency is then improved. Milling at d90 < 35 µm* is recommended for HCl mitigation (waste to energy plant) down to 10 mg/nm 3. A lower emission value of HCl or a SO X mitigation rate above 80 % requires d90 lower than 20 µm to reduce the BICAR consumption. Mixing with flue gas For best performance of the process, a homogeneous mixing is required and can generally be achieved with a residence time of minimum 2 s before the filter. For ducts bigger than 1 m 2 section, BICAR should be injected using a mixing system like a multiple point injection. Bag filter operation The filter is one of the fundamental elements of the SOLVAir Bicarbonate Solution. It acts as a de-dusting device and also as a reactor. Thanks to the reagent layer formed on the bags, the bag filter allows reduction of the BICAR consumption. Dust and water content Even in cases where the raw gases contain a high level of dust or water, sodium bicarbonate BICAR allows very high mitigation rates. * d90 < 35 µm : particles with the diameter less than 35 µm represent 90% of the volume. Compatibility with DeNO x, particularly catalytic (SCR) NO X reduction is accomplished by means of either Selective Catalytic Reduction (SCR) or Non Catalytic (SNCR) systems. The SOLVAir bicarbonate Solution is compatible with both. The SCR system uses ammonia and a catalyst to convert the NO X to N 2. It needs to operate at relatively high temperature in order to avoid the condensation and deposit of ammonium (bi)sulfates on the catalyst layer. When the catalyst system is installed at the end of the treatment (tail end), as in many waste to energy plants, using sodium bicarbonate BICAR enhances the energy recovery. First of all, sodium bicarbonate has the highest reactivity towards SO 3 and SO 2, allowing a very low level of remaining pollutants, and minimizing the risk of formation of ammonium (bi)sulfates. Furthermore, the extended operating temperature range for BICAR avoids any injection of water and the subsequent cooling of the flue gases. Combined, these facts enable the use of the catalytic device at the same temperature as the bag filter, saving the energy often used to re-heat the gases. A heat exchanger prior to the stack increases marketable energy by improved recovery efficiency. 8 / SOLVAir

9 Performance in acid mitigation The HCl and SO X removal efficiency mainly depends on the design and optimization of the air emission control system Acid removal performance When plant parameters comply with the SOLVAir technical specifications, very high acid removal rates are reached, above 99,9% for HCl and 99% for SO 2. If the required SO 2 removal rate is below 80%, an extremely low excess of bicarbonate is necessary to comply with the emission limit. Generally observed HCl mitigation on a bag filter HCl mitigation (%) ,5 0,6 0,7 0,8 0,9 1,0 1,1 1,2 1,3 1,4 1,5 1,6 1,7 Generally observed SO 2 mitigation on a bag filter Stoichiometric ratio SO 2 mitigation (%) ,5 0,6 0,7 0,8 0,9 1,0 1,1 1,2 1,3 1,4 1,5 1,6 1,7 Stoichiometric ratio BICAR is extremely efficient on SO 3 BICAR preferably neutralizes SO 3 compared to SO 2. This effect allows: to protect DeNO X catalysts from ammonium (bi)sulfate deposits to increase the regeneration time interval of catalysts SOLVAir / 9

10 Typical process control As the acid concentrations are measured at the stack, the BICAR flow rate can be effectively controlled in order to respect the strictest emission limits with a minimum sorbent consumption. 40 Respect of an emission limit of 10 mg/nm³ HCl dry at 11% O 2 (daily average) 100 HCI in clean gas (mg/nm 3 dry at 11% O 2 ) :00 2:00 4:00 6:00 8:00 10:00 12: Sodium bicarbonate flow rate (kg/h) Bicarbonate flow rate (kg/h) HCI in clean gas (mg/nm 3 dry at 11% O 2 ) Peak shaving The SOLVAir process is extremely flexible. It has proven its efficiency for acid concentrations even above mg/nm 3. Acid raw gas peaks are very rapidly absorbed thanks to the fast reaction speed of BICAR. Example of removal of HCl peaks at waste-to-energy plant (10 mg/nm³ HCl dry at 11% O 2 - daily average) HCI in raw gas (mg/nm 3 wet) Sodium bicarbonate flow rate (kg/h) HCI in clean gas (mg/nm 3 dry 11% O 2 ) 0 09:36:00 10:48:00 12:00:00 13:12:00 14:24:00 15:36:00 16:48:00 18:00:00 19:12:00 0 HCI in raw gas (mg/nm 3 wet) Bicarbonate flow rate (kg/h) HCI in clean gas (mg/nm 3 dry at 11% O 2 ) 10 / SOLVAir

11 Energy efficiency Energy efficiency is becoming more and more critical for the waste to energy industry because it contributes to the reduction of CO2 emissions. As cheap fuels are becoming rare, the competition between energy producers increases daily. For instance, in the EC directive on waste 2008/98/EC, an energy efficiency factor R1 is defined. If an installation is rated with a factor lower than 0.60 (or 0.65 depending on the permit date), the operation will not be accepted as Energy Recovery but as Disposal. In some countries Energy Recovery from Waste can also benefit from green energy certificates, since a major part of Municipal Solid Waste (MSW) is renewable biomass, thus boosting profitability. Bag Filter NH 3 SCR DeNO x Heat Recovery (recommended) 185 C 185 C 135 C Heat 131 kwh/t The reactivity of sodium bicarbonate BICAR is high within a large moisture content and temperature range. This is why SOLVAir bicarbonate process avoids water injection for cooling/conditioning purposes and reheating of the flue gas upstream of a catalytic DeNOx system (SCR). By saving steam or fuel for flue gas reheating, and by optimizing heat recovery, the marketable energy expressed in the graph below as net conversion yield is boosted for SOLVAir process : From 29% for a wet flue gas treatment with only electricity production to 88% for a waste-to-energy plant using SOLVAir process and connected to district heating network From 40%, which is the average of 314 plants (CEWEP 2013 study), to 51% with SOLVAir process by reducing the internal heat consumption and increasing the energy recovery (131 kwh/t MSW) Total net conversion yield on input (0-100%) R1 - Waste Frame Directive Definition (0-2,37) R1 - Corrected with Climatic Factor (0-3,27) 88% 1,69 51% 1,31 29% 0,84 0,99 40% 0,79 0,79 Wet F.G.T. MSWI Example Average CEWEP 314 EU Plants Germany (2007) Actual situation (2013) If all of them would use SOLVAir bicarbonate process SOLVAir MSWI Example Italy (2011) The graph above shows that the R1 factor is not linked to the net conversion yield, due to the fact that each flue gas treatment technology has a different internal energy use. The R1 climate correction factor which is already implemented in some southern countries increases the value of the R1 factor, in this example from 1,31 to 1,69. Sources: P. Billig, Beitrag der Abfallwirtschaft zum Klimaschutz, 2007, Duisburg (DE) CEWEP Energy Report III by Dr.-Ing. Dieter O. Reimann, 2013, Bamberg (DE) and Energy Recovery / Energy increasing potential using Sodium Bicarbonate for Dry Flue Gas Cleaning in Thermal Waste Treatment by Dr.-Ing. Dieter O. Reimann R. Boero, Tecnologie e gestione nell incenerimento dei rifiuti. Operatori e comunità scientifiche a confronto, 2011, Cassino, (IT) Clerens / ESWET report for JRC and HDD data according to Eurostat Gazzetta ufficiale della Republica Italiana del SOLVAir / 11

12 Sustainable recycling Waste-to-Energy industry The Directive 2008/98/EC indeed gives a much higher priority to recycling over disposal. With the SOLVAir Bicarbonate Solution, the recycling of residue is an industrial reality. It provides practical answers to environmental issues, minimizing the disposal of final waste in accordance with the European waste policy. Since the beginning, SOLVAir Research teams have developed and patented solutions to recycle residual sodium chemicals. These studies have allowed SOLVAY to implement, alone or in partnership, industrial scale treatment plants. In France and Italy, SOLVAY has invested in the recycling of flue gas cleaning residues from waste to energy plants. SOLVAY proposes an original and patented technology to treat the Residual Sodium Chemicals (or RSC) of waste-to-energy plants. The sodium salts based on sodium chloride are treated and recycled as a substitute for one of the raw materials used to produce sodium carbonate. 1 t RSU De-dusting Sodium Bicarbonate ± 15 kg * Adsorbent ± 0,4 kg Bag Filter Fly ash ± 20 kg Residual Sodium Chemicals ± 11,5 kg Water Brine Filtration Purification Towards Zero Waste Dissolver Cake 1 to 2 kg Recyclable brine ± 45 kg (± 10,5 kg salts) * Depending on waste quality Stabilisation Final residue 2 to 4 kg Disposal on licenced landfill site Soda Ash production The SOLVAL unit in Rosignano, Italy, a 100 % SOLVAY subsidiary, processes the Residual Sodium Chemicals of several Italian waste-to-energy plants, and sends the purified brine to the soda ash plant. The RESOLEST plant, located in the East of France near Nancy, is a joint venture between SOLVAY and SITA FD (SUEZ). The brine is transported by pipeline to the SOLVAY Dombasle plant located 4 km away, and is used in the production of sodium carbonate. 12 / SOLVAir

13 Desulphurization facilities For facilities having SO X as main pollutant, such as power plants, ceramics production, sewage sludge incineration, ferrous and non ferrous production etc., the major component of residue is sodium sulphate. To enable the recycling of these residues, SOLVAir has developed the RESOGYPSE process, based on the following reaction: Na 2 SO 4 CaCl 2 CaSO 4 2 NaCl This process presents the advantage of transforming residuals into two valuable products, calcium sulphate, known as gypsum, widely used in cement production, and sodium chloride, used as a raw material in soda ash production. Calcium chloride solution Brine 5.5 tons Soda ash plant Sodium carbonate production Residue 1 ton Gypsum 0.75 ton Building materials Gypsum Resogypse is in operation at the RESOLEST plant near Nancy Glass and aluminium industries The glass industry and secondary aluminium production are among the sectors for which SOLVAir offers an economical and combined solution: in addition to the neutralization of the acids in the flue gases, RSC can be recycled as raw materials in their production. SOLVAir / 13

14 Importance of bicarbonate particle size Savings on sorbent The flue gas treatment performance may be significantly lower when sodium bicarbonate particle size distribution is coarser than SOLVAir technical specifications values (d90 < 35 µm for HCl mitigation down to 10 mg/nm³ and d90 < 20 µm for SO X mitigation rates above 80% or HCl < 10 mg/nm³ at stack). According to SOLVAir MSWI customer experience, the sorbent consumption may decrease up to 18% if milled sodium bicarbonate particle size distribution decreases from d90 ~46 µm to d90 ~28 µm.* Sorbent avergae consumption per line (Kg/h) ,6 28,0 Particle size distribution : d90 (µm) Savings on residues A sorbent overconsumption of 18% also increases RSC production of almost 12%**. This has to be added to the extra sorbent costs. Optimizing the sorbent consumption has therefore a double positive effect for the customer operating costs and also for the flue gas treatment environmental footprint. How to get the right particle size? Milling on site A hammer milling technology and dynamic air classifier system enables to get the adequate particle screening and delivers a constant particle size distribution at all sorbent flow rates. Ready-to-use product SOLVAY supplies ready-to-use sorbent, specially designed for flue gas treatment purposes. The ready-to-use sorbent solution has the advantage to: lower the costs be easily implemented increase flexibility on the dosing rate be formulated for easy handling For any further information, please contact SOLVAir team. * Query: SOLVAir optimization campaign at a French Waste-to-Energy facility (2 x 8 t/h lines) with weekly follow-up of RSC composition from November 2007 till May ** Assuming that overdosed sorbent with coarse particle size distribution will generate soda ash and not mitigate acid compounds. 14 / SOLVAir

15 Expertise serving industry SOLVAir has built its know-how and renowned reputation on its capacity to partner industries in their technical, economical and environmental evolution. The SOLVAir team is at your side throughout every stage of your project. Alongside engineering companies or your own technical teams, they offer you expertise and advice to: establish a diagnosis of your installations emissions assist in the design of the flue gas cleaning plant explore the possibilities of converting existing flue gas cleaning systems to the SOLVAir Bicarbonate process propose and carry out preliminary tests in situ with mobile equipment and laboratories ease and optimize the start-up and commissioning stages : air emission control performance analysis, verification and optimization consider purification and/or recycling possibilities for the Residuals Sodium Chemicals. The SOLVAir markets Industrial Boilers Ceramic Industry SOLVAir has acquired and continues to develop expertise in many markets to provide the best solution for each of its numerous customers. Paper Mills Cement Plant Steel Industry Non Ferrous Metallurgy Waste to Energy Wastewater (sludge) Glass Industry Energy from Biomass Mineral Wool Industry Oil Refinery Carbon based Industry SOLVAir / 15

16 SOLVAY SA - NV Rue de Ransbeek 310 B 1120 Brussels , Solvay The information contained in this document is given in good faith and by way of information at the time of publishing. SOLVAY does not engage its responsibility.the use of our products is the treatment of flue gases, excluding all others uses and applications. The buyer is required to monitor and respect, in his sole liability, the conditions under which our products are stored and used in his territory, to provide all required information to the user, and to respect all existing patents and all regulations applicable to our products and to his activity.