Industrial Sector. I. Summary and Overview

Transcription

1 Industrial Sector I. Summary and Overview This chapter will discuss Industrial Sector technologies and measures to reduce air pollution, as well as ways to reduce air pollution and greenhouse gas emissions. The industrial sector is extremely diverse and involves a wide range of activities including the extraction of natural resources, conversion into raw materials, and manufacture of finished products. Due to this wide variety, we have selected a few industrial sectors based on the emission profiles, as well as geographic locations, e.g. with respect to the target non-attainment areas for use in the hypothetical SIPs. The selected industrial sectors are; Iron and Steel, Pulp and Paper, Cement, Ammonia and Fertilizer, and Petroleum. A wide variety of technologies are available to reduce criteria air pollutant emissions, as well as greenhouse gases, through energy efficiency improvement and fuel switching. In describing technologies it is clear that the performance and results of a specific technology may vary between different applications and plants, depending on a wide variety of factors. Hence, the descriptions are illustrative. End-of-pipe pollution control technologies may involve just the financial costs of installation and O&M, as long as air pollution costs are externalities of the energy price. Alternatively, energy efficiency measures generally reduce energy costs, as well as often reducing other production costs. While it is difficult to estimate the production cost savings, they can are often substantial, as shown by the in-depth analysis of the iron and steel industry (see below). STAPPA - Industrial Sector Draft 1 1

2 II. Selection of Industries and Technologies A. Criteria for selecting industries The industrial sector is extremely diverse and involves a wide range of activities including the extraction of natural resources, conversion into raw materials, and manufacture of finished products. The sub-sectors that account for roughly 45% of all industrial energy consumption, are: iron and steel, chemicals, petroleum refining, pulp and paper, and cement. These industries are generally concerned with the transformation of raw material inputs (e.g., iron ore, crude oil, wood) into usable materials and products for an economy. Due to the wide variety of activities, energy use, greenhouse gas and criteria pollutant emissions vary widely. An industry specific examination is based on the following criteria. The selection for specific sub-sectors will be limited to six industrial sub-sectors. 1. Criteria pollutants Industries emit a wide variety of criteria air pollutants, from an even wider variety of processes. While sulfur emissions depend mainly on the fuels and resources used, emissions of other criteria pollutants also depend on the specific process conditions. In selecting the industrial subsectors we will mainly account for NO 2 and SO 2 emissions. The sub-sectors responsible for at least 10% of the specific emissions will be selected for an in-depth assessment of the emission reduction and energy efficiency improvement technologies. 2. Greenhouse gas emissions Since the Kyoto Conference in December 1997, six greenhouse gases (GHGs) are internationally considered in GHG abatement policies. These six GHGs are summarized in Table 1, as well as the main industrial sources. Table 1 and Table 2 show that carbon dioxide emissions are mainly connected to the energy intensity of the production processes, while the other GHGs are mainly process emissions from specific industries. In selecting the sub-sectors we will primarily use CO2 emissions as a selection criteria. Industries that emit at least 5% of industrial CO2 emissions are selected for further assessment. Table 1. Greenhouse gases and main industrial emission sources. Greenhouse Gas Carbon Dioxide Methane Nitrous Oxide CFCs/HFCs PFCs SF 6 Industrial Sources Combustion processes Clinker making (cement) Fossil fuel production Oil Refining & Chemical industry Iron and Steelmaking Adipic acid production Nitric acid production Electronics industry Plastics industry (foam) Refrigeration Primary aluminum production Electronics industry Magnesium production Electronics industry STAPPA - Industrial Sector Draft 1 2

3 3. Locations: impact on non-attainment areas The impact of emissions on the local air quality depend heavily on the region. Local climate conditions, as well as concentrations. Industries located in non-attainment areas get, therefore, more attention in developing plans for emission reduction. A qualitative estimate of the location of industries in non-attainment areas will be considered in selecting the sub-sectors. We will also consider the concentration among various states. For example, the petrochemical and ammonia industries are heavily concentrated in the South, e.g. Louisiana and Texas. B. Industry Specific Emissions The industrial sector is an important source of emissions of air pollutants and greenhouse gases. As can be seen from the variation in contribution to the emissions, the wide variety of industrial processes affects the specific emissions. Table 2 gives an overview of the nationwide emissions of criteria pollutants and greenhouse gases by industrial sub-sector. We selected the five industrial sub-sectors for an in-depth assessment of emission reduction of air pollutants and greenhouse gas emissions, based on the emission profile and contribution to the total national emissions of air pollutants and greenhouse gases. The selected sub-sectors are; the Iron and Steel Industry, Pulp and Paper Industry, Cement Industry, Ammonia and Fertilizer Industry, and Petroleum Refining. Besides the sub-sectors we will also assess opportunities for boilers as the major energy consuming cross-cutting technology. STAPPA - Industrial Sector Draft 1 3

4 Table 2. Air Pollutant Emissions and Greenhouse Gas Emissions by Industry Sector. Air pollutant data reflects the most recent data, and is expressed in tons/year. CO2 emissions are for 1994, and expressed in Million tons/year. Other GHG emissions are expressed in tons/year. CO2 emissions exclude public power generation (see chapters on utilities and power supply). Industry Sector Air Pollutants Greenhouse Gases CO NO 2 PM10 PT SO 2 VOC CO 2 CH 4 N 2 O HFC PFC SF 6 Metal Mining 4,951 49,252 21,732 9,478 1, ,761 Non-fuel, Non-metal Mining 31,008 21,660 44,305 16,433 9, ,684 Food and Kindred Products n.a. Textiles 8,164 33,053 1,819 38,505 26,326 7, Lumber and Wood 139,175 45,533 30,818 18,461 95,228 74, Wood Furniture 3,659 3,267 2,950 3,042 84,036 7, Pulp and Paper 584, ,901 37, , ,937 74, Printing 8,847 3, ,772 88,788 5, Inorganic Chemicals 242,834 93,763 6, ,971 52, , ,000 Plastic Resins & Fibers 15,022 36,424 2,027 65,875 71,416 1, Pharmaceuticals 6,389 17,091 1,623 24,506 31,645 34,885 Organic Chemicals 112, ,094 13, , ,488 7, ,400 62,000 Petroleum Refining 299, ,795 25, , ,167 4, Rubber and Plastic 2,463 10,977 3,391 24, ,739 17, Stone, Clay, Glass, Concrete 92, ,290 58, ,017 21,092 36, Iron and Steel 982, ,020 36, ,436 67,682 6, ,000 Metal Castings 115,269 10,435 14,667 4,881 17, , Non-Ferrous Metals 311,733 31,121 12, ,599 7,882 85, , Fabricated Metal Products 7,135 11,729 2,811 17, ,228 21, Electronics and Computers 27,702 7,223 1,230 8,568 46,444 23, Motor Vehicle Assembly 19,700 31,127 3,900 29, ,755 5, Shipbuilding and Repair ,862 4,345 3,464 Total , , ,400 1,100 Source: Sector Notebook Data Refresh 1997, U.S. EPA, Washington, DC, (air pollutants); Manufacturing Energy Consumption Survey 1994, Energy Information Administration, U.S. DOE, Washington, DC, 1997 (CO2 emissions); Emissions of Greenhouse Gases in the United States 1995, U.S. DOE/EIA, Washington, DC, 1996 (other GHGs). STAPPA - Industrial Sector Draft 1 4

5 1. Iron and Steel Industry The U.S. iron and steel industry is made up of integrated steel mills that produce pig iron from raw materials (iron ore, coke) using a blast furnace and steel using a basic oxygen furnace (BOF) and secondary steel mills that produce steel from scrap steel or direct reduced iron (DRI) using an electric arc furnace (EAF). The majority of steel produced in the U.S. is from integrated steel mills, although the share of secondary steel mills (or minimills ) is increasing, growing from 15% of production in 1970 to 40% in There were 142 operating steel plants in the U.S. in 1997 (see Figure 1.1). At that time, there were 14 integrated steel companies operating 20 integrated steel mills with a total of 40 blast furnaces. 2 These mills are concentrated in the Great Lakes region, near supplies of coal and iron ore and near key customers such as the automobile manufacturers. The blast furnaces in these mills range in age from 2 to 67 years (including furnace rebuilds), with an average age of 29 years. Production rates vary between 0.5 and 3.1 million metric tons (Mt) per year. Total production of U.S. blast furnaces in 1997 was slightly over 59 Million tons. Integrated Steel Production Secondary Steel Production Figure 1.1. Location of steelmaking facilities in the United States. Secondary steel mills are located throughout the U.S, with some concentration in the South, near waterways for shipping and in areas with lower-cost electricity. 3 In 1997 there were 85 secondary steel companies operating 122 minimills with 226 EAFs. These facilities are spread throughout 35 states, with the largest number of plants in Pennsylvania, Ohio, and Texas. The electric arc furnaces at these mills range in age from 0 (just starting production in 1997) to 74 years, with an average age of 24 years. Total annual nominal capacity listed in 1994 was 50.4 Mt and the average power consumption is 436 kwh/short ton. 4 Between 1995 and 1997 an additional 12 Mt of electric arc furnace capacity was built. STAPPA - Industrial Sector Draft 1 5

6 1.2 Emissions Table Control Methodologies Single Pollutant Few U.S. iron and steel mills control NO x emissions. Processes known to have installed NO x controls are reheat furnaces, annealing furnaces and galvanizing furnaces. Controls in-use include both combustion modifications (low excess air, low NO x burners, flue gas recirculation) and add-on controls (selective catalytic reduction). 5 The controls for each of these furnaces, the controlled NO x emissions and the emissions reductions achieved by the controls are summarized in Table 1.2. Internationally, sinter plant emission control equipment aims at the reduction of dust and SO 2 emissions, 6 although NO x emissions are reduced by 30-50% when controlling sulfur emissions. Special NO x controls can be found in some plants in e.g Japan. 7 In the U.S. sinter plant flue gases are dedusted, but no dedicated air pollution control technologies are installed. In the U.S., low excess air, low NO x burners and low NO x burners plus flue gas recirculation are being used to control NO x emissions from reheat furnaces. Reductions range from 12 percent for low excess air, to 55 percent for low NO x burners plus flue gas recirculation. Low NO x burners, SCR plus low NO x burners, low NO x burners plus flue gas recirculation and SCR alone are being used to control NO x emissions from annealing furnaces. Reductions range from 50 percent for low NO x burners, to 97 percent for SCR plus low NO x burners. Although no applications of SNCR for annealing furnaces (or other iron and steel facilities) exist, it is theorized that, because of SNCR's similarity to SCR, NO x emissions from annealing furnaces using SNCR could be reduced by 60 percent. Similarly, an annealing furnace controlled by SNCR plus low NO x burners might reduce NO x emissions by 80 percent. In the U.S., low NO x burners and low NO x burners plus flue gas recirculation are used to control NO x emissions from galvanizing furnaces. Reductions range from 35 percent for low NO x burners, to 77 percent for low NO x burners plus flue gas recirculation. None of the controls for other NO x -emitting processes and facilities are in use in the U.S. Various authorities report experience in Japan and Europe with coke oven controls (low excess air, SCR and fuel denitrification) and sintering plants (pretreating sinter materials, SCR, electron beam radiation, flue gas recirculation). Reduction Potential and Cost Estimates It appears that most of the estimated 51, ,000 tons of annual U.S. NO x emissions from ferrous metals processing come from processes that are uncontrolled for NO x. As Table 1.2 shows, there is significant reduction potential for three NO x sources (reheat, annealing and galvanizing furnaces), but controls are unavailable for other NO x processes identified in Table 1.2. The national emissions reduction potential is, therefore, significant but unquantifiable based on available data. STAPPA - Industrial Sector Draft 1 6

7 Table 1.2 summarizes the annual costs and cost effectiveness of the control strategies for reheat, annealing and galvanizing furnaces, respectively. These figures come from the EPA's 1993 draft ACT document and are derived from a limited database. The numbers clearly show, however, that NO x reductions can be achieved in nearly every case for hundreds (as opposed to thousands) of dollars per ton. For a 300 MBtu/hr reheat furnace, cost effectiveness ranges from $210-$820/ton of NO x removed. For a 200 MBtu/hr annealing furnace, cost effectiveness ranges from $180-$540/ton of NO x removed. For a 150-MMBtu/hr galvanizing furnace with preheated combustion air, cost effectiveness ranges from $130-$8200/ton of NO x removed. Table 1.2 Emission reduction potentials and cost estimates for NO x emission reduction. 8 Technology Emission Reduction (%) Cost Effectiveness ($/ton NOx removed) Reheat Annealing Galvanizing Reheat Annealing Galvanizing Low NOx Burners (LNB) 33-34% 50% 35% n.a. Low Excess Air (LEA) 12% Selective Catalytic - 85% Reduction Selective Non-Catalytic - 60% Reduction LNB + Flue Gas 55% 82% 77% Recirculation LNB + SCR - 96% LNB + SNCR - 79% Multiple Pollutant & Energy Efficiency Improvement To analyze the potential for reducing carbon emissions from steelmaking in the U.S., a detailed survey of technologies is needed, as process and emissions vary widely between different types of facilities. This assessment is based on a detailed study that compiled information on the costs, savings, and carbon emissions reductions of a number of technologies and measures. 9 The study aimed at identifying the potentials for energy efficiency improvement in the U.S. steel industry. Actual efficiency improvements in a specific plant or location may differ from the average estimates given in the mentioned study. Generally, air pollutant emission reduction is equivalent to the achieved reductions in energy use and GHG emissions, unless combustion conditions are changed or fuels are replaced. Based on the study by Lawrence Berkeley National Laboratory, 8 we estimated the reduction in NO x emissions. Various measures and technologies to reduce the electricity consumption of steelmaking. Hence, NO x emission reductions will take place at the site of electricity production, which may be different than the steelplant site. Table 1.3 and 1.4 summarize the main energy efficiency measures and estimated reduction in energy use, GHG emissions and NO x emissions. Typical costs figures are given as well. STAPPA - Industrial Sector Draft 1 7

8 Table 1.3. Energy Savings, Costs, and Carbon Emissions Reductions for Energy-Efficiency Technologies and Measures Applied to Integrated Steel Production in the U.S. NOx emission reductions are expressed as function of the emissions of the specific operation or process. Option Iron Ore Preparation (Sintering) 1994 Throughput (M ton) Fuel Savings (MBtu/ton crude steel) Electricity Savings (Mbtu/ton crude steel) Primary Energy Savings (Mbtu/ton crude steel) Annual Operating Cost Savings (US$/ton steel) Retrofit Capital Cost (US$/ton steel) Specific NOx Emissions Reduction Estimate (lb/ton) Sinter plant heat recovery Increasing bed depth Improved process control Use of waste fuels in sinter plant Coke Making Coal moisture control Programmed heating Carbon Emissions Reduction (kgc/t) Variable speed drive coke oven gas compressors Coke dry quenching Iron Making - Blast Furnace Pulverized coal injection to 130 kg/thm Pulverized coal injection to 225 kg/thm Injection of natural gas to 140 kg/thm Top pressure recovery turbines (wet type) Recovery of blast furnace gas Hot blast stove automation Recuperator hot blast stove Improved blast furnace control systems Steelmaking Basic Oxygen Furnace BOF gas + sensible heat recovery Variable speed drive on ventilation fans Management of oxygen make-up Integrated Casting Efficient ladle preheating Thin slab casting Integrated Hot Rolling Hot charging Process control in hot strip mill Recuperative burners Insulation of furnaces Controlling oxygen levels and VSDs on combustion air fans Energy-efficient drives (rolling mill) Waste heat recovery (cooling water) Integrated Cold Rolling and Finishing Heat recovery on the annealing line Reduced steam use (pickling line) Automated monitoring and targeting system General Preventative maintenance Energy monitoring and management system Cogeneration Variable speed drive: flue gas control, pumps, fans STAPPA - Industrial Sector Draft 1 8

9 Table 1.4. Energy Savings, Costs, and Carbon Emissions Reductions for Energy-Efficiency Technologies and Measures Applied to Secondary Steel Production in the U.S. Option Steelmaking Electric Arc Furnace 1994 Throughput (M ton) Fuel Savings (MBtu/ton crude steel) Electricity Savings (MBtu/ton crude steel) Primary Energy Savings (Mbtu/ton crude steel) Annual Operating Cost Change (US$/ton steel) Retrofit Capital Cost (US$/ton steel) Specific NOx Emission Reduction (lb/ton) Carbon Emissions Reductions (kgc/t) Improved process control (neural network) Fluegas Monitoring and Control Transformer efficiency UHP transformers Bottom Stirring / Stirring gas injection Oxy-fuel burners Increase 5.6 Eccentric Bottom Tapping (EBT) on existing furnace DC-Arc furnace Scrap preheating Tunnel furnace (CONSTEEL) Scrap preheating, post combustion - Shaft furnace (FUCHS) Twin Shell DC w/ scrap preheating Secondary Casting Efficient ladle preheating Thin slab casting Secondary Hot Rolling Process control in hot strip mill Recuperative burners Insulation of furnaces Controlling oxygen levels and VSDs on combustion air fans Energy-efficient drives in the rolling mill Waste heat recovery from cooling water General Technologies Preventative maintenance Energy monitoring & management system Some technologies have a potential large impact on both GHG emissions and air pollutant emissions, warranting more attention. Below are some of these technologies, based on Worrell et al. 10 Fuel injection in the blast furnace. One of the main energy efficiency measures in the iron making stage is the injection of fuels into the blast furnace, especially the injection of pulverized coal (PCI). Pulverized coal injection replaces the use of coke, reducing coke production and hence saving energy consumed in coke making and reducing emissions of coke ovens and associated maintenance costs. Coal injection has increased in recent years due to environmental legislation combined with the high average age of U.S. coke plants. Closing of old coke plants is leading to increased coke imports. Increased fuel injection requires energy for oxygen injection, coal, and electricity and equipment to grind the coal. The coal replaces part of the coke that is used to fuel the chemical reactions. Coke is still used as support material in the blast furnace. The maximum fuel injection depends on the geometry of the blast furnace and impact on the iron quality (e.g. sulfur). Coal injection is common practice in many European blast furnaces and is increasing in the U.S. to reduce the amount of coke required. Maximum theoretical coal injection rates are around lb/t hot metal. In the STAPPA - Industrial Sector Draft 1 9

10 U.S. the coal injection rate varies. A 1994 survey of seven blast furnaces in the U.S. gave fuel injection rates between 41 and 226 lb/t hot metal. 11 The highest injection rates, of 450 lb/t, have been reached at USX Gary. Coke replacement rates vary between 85% and 100%. 12 We assume that 1 lb of coke will be replaced by 1.08 kg of injection fuel, a replacement rate of 92%. The investments for coal grinding equipment are estimated to be $45-50/t coal injected. O&M costs show a net decrease due to reduced coke purchase costs and/or reduced maintenance costs of existing coke batteries, which is partly offset by the increased costs of oxygen injection and increased maintenance of the blast furnace and coal grinding equipment. We estimate the reduced operation costs on the basis of 1994 prices of steam coal and coking coal to be $15/t. This is a low estimate, as cost savings of up to $30/t are possible, resulting in a net reduction of 4.6% of the costs of hot metal production. Air and surface water pollutant emissions are reduced at the same level of the coke replaced, due to lower coke production. Pulverized coal injection to 260 lb/t hot metal. In this measure, the average coal injection rate is increased from the current average of 4 lb/t hot metal to 260 lb/t hot metal for all blast furnaces. This net increase of 254 lb/t hot metal leads to fuel savings of 0.66 MBtu/t hot metal with capital costs of $6/t hot metal. Operation costs will decrease by $2/t hot metal. 13 Pulverized coal injection to 225 kg/t hot metal. In this measure, the injection rate is increased to 225 kg/t hot metal (as reached at USX Gary blast furnace 13) for the large volume blast furnaces only (defined as those with production rates of Mt/year, which is approximately 30% of total production). Injection of natural gas. This measure is only applied to a portion of medium sized furnaces, defined as those with production rates of Mt/year, represent 20% of total furnaces. Currently, coal is seen as the favorable injection fuel because of its low price. Injection of natural gas is an alternative. Maximum injection rates are lower than for coal. 14 Replacement rates for natural gas vary between 0.9 and 1.15 lb natural gas/lb coke. Natural gas injection tests by the Gas Research Institute show a maximum injection rate of lb/t hot metal, with estimated costs savings of $4/t hot metal. Assuming a replacement rate of 1 lb. natural gas/lb coke, savings from replacing 280 lb of coke are estimated to be 0.8 GJ/t hot metal. We assume that operating costs will decrease similar to that seen in the lower PCI injection measure ($2/t hot metal). Thin slab casting is a new technology integrating casting and hot rolling in one process. Pioneered in the U.S. by Nucor at the Crawfordsville and Hickmann plants, various plants are operating, under construction, or ordered worldwide. Originally designed for small scale process-lines, the first integrated plants constructed (Acme, U.S.; Posco, Korea) or announced were thin slab casters (Germany, Netherlands, Spain) with capacities up to 1.5 Mt/year. 15 Three suppliers (in Germany and Austria) currently supply this technology. We base our description on the CSP-process developed by SMS (Germany) as it represents most of the capacity installed worldwide. Energy savings are estimated to be 4.4 GJ/ton product (primary energy). The energy consumption of a CSP-plant is 85 MJ fuel per ton for the reheating furnace and electricity use of 39 kwh/ton. The investments for a large scale plant are estimated to vary between $100/t and $160/t product. We assume therefore an investment cost of $136/t, with estimated operation cost savings of between $23/t and $42/t product. We therefore assume a cost savings of $36/t. The potential capacity of thin slab casting is estimated to be 20% of U.S. integrated production and 64% of secondary steel. The emissions of the slabbing and reheating furnace are reduced by the same degree as the energy consumption. STAPPA - Industrial Sector Draft 1 10

11 BOF gas and sensible heat recovery (repressed combustion) is the single most energy-saving process improvement in this process step, making the BOF process a net energy producer. By reducing the amount of air entering over the convertor, the CO is not converted to CO 2. The sensible heat of the off-gas is first recovered in a waste heat boiler, generating high pressure steam. The gas is cleaned and recovered. The total savings vary between 0.5 and 0.8 MBtu/t steel, depending on the way the steam is recovered. 16 Repressed combustion reduces dust emissions and since the metal content of the dust is high, about 50% of the dust can be recycled in the sinter plant. The costs will depend on the need for extra gas holders. Repressed combustion is very common in integrated steel plants in Europe and Japan. In the U.S. no BOF gas seems to be recovered, so this measure can still be applied to 100% of U.S. BOF steelmaking. We assume an energy recovery rate of 0.8 MBtu/t crude steel, with estimated capital costs of 20$/t crude steel capacity, based on plants in Japan and The Netherlands. The CO emissions of the BOF plant are very high, and estimated at 139 lb/ton crude steel. 17 The CO emissions will be almost completely reduced. Sinter plant heat recovery. Heat recovery at the sinter plant is a means for improving the efficiency of sinter making. The recovered heat can be used to preheat the combustion air for the burners and to generate high pressure steam which can be run through electricity turbines. Various systems exist for new sinter plants (e.g. Lurgi EOS process) and existing plants can be retrofit. 18 In 1994, only 15% of the blast furnace feed consisted of sinter; the remainder of the feed was composed of pellets, pelletized at the mining site. We assume that this measure can be applied to all existing sinter plants. We estimate the fuel savings (steam and coke) associated with production of this 13.5 Mt of sinter to be 0.47 MBtu/ton sinter, based on a retrofitted system at Hoogovens in The Netherlands, with increased electricity use of 1 kwh/ton sinter. 19 NOx, SOx and particulate emissions are also reduced with this system. The measure has capital costs of approximately $3/t sinter. We do not estimate costs for new sinter plants since it is unlikely that such plants will be built in the U.S., due to the large investment required. New iron making technologies aim at the use or lump ore or ore fines, instead of using agglomerated ores. Other methods to reduce energy use in sinter plants include reduction of air leakage, increasing bed depth, and improved process control. Scrap preheating is a technology that can reduce the power consumption of EAFs through using the waste heat of the furnace to preheat the scrap charge. However, site emissions may increase due to increased fuel use, but are more than offset by reduced emissions from power generation. Old (bucket) preheating systems had various problems, e.g. emissions, high handling costs, and a relatively low heat recovery rate. Modern systems have reduced these problems, and are highly efficient. The energy savings depend on the preheat temperature of the scrap. Various systems have been developed and are in use at various sites in the U.S. and Europe, i.e. Consteel tunnel-type preheater and Fuchs Finger Shaft. The Consteel process consists of a conveyor belt with the scrap going through a tunnel, down to the EAF through a hot heel. Various U.S. plants have installed a Consteel process, i.e. Florida Steel (now AmeriSteel, Charlotte, NC) New Jersey Steel (Sayreville, NJ) and Nucor (Darlington, SC), and one plant in Japan. Electricity use can be decreased to approximately kwh/ton without supplementary fuel injection in retrofit situation, while consumption as low as kwh/t have been achieved in new plants. The FUCHS shaft furnace consists of a vertical shaft that channels the offgases to preheat the scrap. The scrap can be fed continuously (4 plants installed world wide) or through a so-called system of fingers (15 plants installed worldwide). The Fuchs-systems make almost 100% scrap preheating possible, leading to potential energy savings of kwh/t. In the U.S. Fuchs systems have been installed at North Star (Kingman, AZ), North Star-BHP (Delta, OH), Birmingham Steel (Memphis, TN). Two other Finger shaft processes have been ordered by Chapparel (TX) and STAPPA - Industrial Sector Draft 1 11

12 North Star (Youngstown, OH). The scrap preheating systems lead to reduced electrode consumption, yield improvement of %, up to 20% productivity increase and 25% reduced flue gas dust emissions (reducing hazardous waste handling costs). A special system has been developed for retrofitting existing furnaces called the Fuchs Optimized Retrofit Shaft, with a relatively short shaft. Retrofit costs are estimated at $6/t for an existing 110 t furnace. 20 STAPPA - Industrial Sector Draft 1 12

13 2. Pulp and Paper Industry 2.1 Process Description Paper is produced from wood pulp and waste paper. Pulp can be made from various pulping processes. We distinguish chemical, mechanical (for newsprint paper) and other pulping processes. The pulp is used to produce a wide variety of paper types. The paper type is defined by the relative amount of waste paper used. Papermaking is an energy- and carbon-intensive manufacturing process. The U.S. pulp and paper industry (SIC 26) accounted for 16% of total final manufacturing energy use and 3% of total final U.S. energy use in During 1970 to 1995, U.S. pulp production grew from 42 to 74 million tons, with the bulk of the growth occurring in chemical pulp production (average annual growth of 2.6%). In 1995, chemical pulp accounted for 83% of all pulp, followed by mechanical pulp (9%) and other pulp (8%). U.S. paper production grew from 50 to 98 million tons during this period. Wrapping and packaging paper clearly dominates, with 52% of production in 1995, followed by printing and writing (28%), newsprint (8%), sanitary and household (7%), and other paper (5%). While paper production grew at an average annual rate of 2.7%, growth in printing and writing paper and newsprint was faster, averaging 3.9% and 3.3%, respectively. The main paper mill types are integrated mills, integrating a pulping and paper mill, and standalone mills, that either produce market pulp, or paper from market pulp and waste paper. Historically, paper mills can be found near the resource, i.e. forests, but some paper mills are now located near sources of waste paper (e.g. urban areas). 22 The pulp and paper industry is hence concentrated in the North-East, South-East, as well as Mid-West of the U.S. and Washington state. The U.S. is the world s largest paper producer with about 547 paper mills, producing about 98 million tons of paper and 10 million tons of market pulp Emissions Final energy used for papermaking in the U.S. grew from 1.2 Quads (1.3 EJ) in 1958 to 2.6 Quads (2.8 EJ) in Wood waste burned on-site provided most of the energy used, growing from 35% of final energy in 1958 to 51% in The shares of electricity and natural gas also grew during this time, while the use of coal & coke and oil declined. The shift away from oil after the oil embargoes of the 1970s was dramatic, with shares dropping from a high of 26% in 1972 to 7% in Primary energy use grew from 1.3 Quads (1.4 EJ) to 3.9 (3.2 EJ) Quads between 1958 and NOx emissions of the pulp and paper industry are estimated at 365,900 tons per year, or equivalent to approximately 7.5 lb/ton paper produced. The 1994 CO2 emissions are estimated at Million tons C or nearly 18% of total industrial CO 2 emissions in the U.S. STAPPA - Industrial Sector Draft 1 13

14 Table 2.1. Production, energy, carbon and emission data for U.S. papermaking in Average Annual Growth Rate Average Annual Growth Rate Unit Pulp Production Mton % 3.5% Paper Production Mton % 5.5% Final Energy TBtu % 1.9% Primary Energy TBtu % 1.9% Final Energy Intensity Mbtu/ton % -3.4% Primary Energy Intensity Mbtu/ton % -3.4% Carbon Emissions MMton % 2.0% Carbon Intensity TC/ton % -3.3% Sources: U.N., 1998; LBNL, 1998a; LBNL, 198b. 2.3 Control Methodologies Single Pollutant Total NOx emissions from the pulp and paper industry are estimated at 265,900 tons. The main energy consuming, and emitting processes, are pulp making and paper making. Kraft pulp making is the dominant process in the U.S. Kraft pulp mills produce paper pulp from wood. The approximately 200 kraft mills in the U.S. produce 50 million tons of pulp, and have aggregate NO x emissions of 68,000 tons/year. Paper making is responsible for the balance of NOx emissions, which is mainly from industrial boilers and cogeneration systems (gas turbines). The boilers are discussed in a separate section. In Kraft pulp making there are three types of NO x sources. Industrial boilers are used to produce steam and power. Recovery boilers recover chemicals used in the pulping process from wood digester effluent; these boilers evaporate water from the effluent and reduce spent pulping chemicals to forms amenable to recycling. Lime kilns, the third type of NO x source, recover calcium oxide used in the pulping chemical recovery process. Uncontrolled kraft mill emissions are 1-3 lb NO x /air-dried ton of pulp (ADTP) for the industrial boilers, 1.8 lb/adtp for the recovery boiler and 0.6 lb/adtp for the lime kiln. While a variety of NO x controls are available for mill industrial boilers, little has been done to control recovery boiler or lime kiln emissions. NOx emissions from recovery boilers are relatively low, due to low flame temperatures and air staging in the boiler. Because recovery boilers use air staging for the chemical recovery process, they already have relatively low NO x emissions of 0.1 lb/mmbtu on a heat input basis. Further, air staging and selective non-catalytic reduction have been demonstrated to provide additional emissions reductions. Lime kilns should be amenable to controls used on rotary kilns in the cement industry (see section 3). Two strategies 26 have been demonstrated for the control of NO x emissions from recovery boilers low excess air/air staging and SNCR. While recovery boiler NO x emissions are largely fuel derived, given low furnace temperatures, strategies such as switching to lower nitrogen content woods are not practical. Low Excess Air and Air Staging, in combination, results in moderate reductions in NO x emissions. Each 1%-point decrease in economizer excess oxygen level reduces NO x emissions by approximately 10-20%. Modifying the air staging from baseline operation often appears to provide further, boiler-dependent emissions reductions. Both parameters may influence recovery boiler function, and a detailed study at each boiler may be necessary to determine the extent to which this strategy may be implemented. Selective Noncatalytic Reduction (SNCR) using urea (NOxOUT process) has been demonstrated at a 900 MMBtu/hr recovery furnace in Sweden. Controlled emissions of approximately lb/mmbtu STAPPA - Industrial Sector Draft 1 14

15 were obtained at full boiler load in this short-term demonstration, corresponding to an emissions reduction of over 60 percent from an uncontrolled level of lb/mmbtu. Ammonia slip was approximately 11 ppm and nitrous oxide emissions increased only to about 1 ppm. No effect of the SNCR system on overall boiler operation was observed, although approximately 0.4 percent of input ammonia was trapped in the fly ash leaving the boiler. Based on these results, SNCR appears to be an effective control for recovery boiler NO x emissions. Multiple Pollutant & Energy Efficiency Improvement A wide variety of technologies are available to improve the energy efficiency of pulp and paper making operations. No comprehensive study is currently available with estimates of the impact on energy use and emissions and cost-effectiveness of energy efficient technologies for the U.S. pulp and paper industry. Table 2.2 provides a list of technologies and measures by process that can be used to reduce energy use and associated emissions in papermaking. This table includes estimates of energy savings from most of these technologies. 27 There is a net reduction in NOx emissions, but further analysis is required to calculate emissions reduction and further research is required to determine which of these options are cost-effective. Recovery boilers in kraft pulping are the second important source of NO x emissions after steam boilers. A new technology, black liquor gasification combined with gas turbine based cogeneration can replace the traditional recovery boilers, increasing the energy recovery rate, and hence the need for recovery boilers, and partially replacing the steam boilers. In chemical pulping the lignin in the wood is dissolved in a digester where the woodchips are cooked. The chemicals can be a mixture of sodium hydroxide and sodium sulfide or sulfite. After a few hours the fibres are separated from the spent pulping liquor (so-called black liquor). The pulp yield is equal to 40-50% (bleached) or 50-65% (unbleached) of the incoming wood. 28 The process chemicals and energy from the spent liquor are recovered. The black liquor is first concentrated, and subsequently incinerated in socalled recovery boilers, recovering the chemicals and generating steam for the plant (used to produce electricity in a steam turbine plant, with an estimated overall efficiency of 23%). Generally the heat and electricity production ratio matched demand well. High investments of recovery boilers and increasing electricity demand (and decreasing steam use) has increased the interest in new cogeneration options. Gasification produces a fuel gas with heating values of MBtu/scf (HHV) using air or MJ/scf (HHV) using oxygen (or an indirect gasifier, see below) as gasifying medium. 29 The gas should be cleaned to recover inorganic chemicals (e.g. alkalines, H 2 S) to prevent damage to the gas turbine and reduce emissions. In existing pilot plants the gas is not yet burned in a gas turbine but in steam boilers, because gas clean up technologies are still under development. Besides black liquor a gasifier could also use wood wastes (bark and other residues) to produce fuel gas. Typically, this is around 5-10% of the pulp wood and would add 3.4 Mbtu/ton of pulp, to the MBtu/ton pulp from the black liquor. Gasification processes can be divided in low temperature (indirect) and high temperature processes. The problem of low temperature gasification is maintaining the right temperature to reduce tar formation and to avoid agglomeration of bed material. The low temperature processes use a fluidized bed. Solid sodium carbonate is used as the bed material and is precipitated out (and reused). Two manufacturers are the leading developers of fluidized bed processes, i.e. MTCI (USA) and ABB (Sweden). The MTCI design is an indirectly heated fluidized bed gasifier, and a 55 ton/day (solids) pilot plant is tested in North Carolina (USA). The ABB design is an air blown circulating fluidized bed gasifier. A 2-4 ton/day pilot plant has been tested in Sweden since 1991, and 27 ton/day demonstration unit will be tested in the U.S. 30 STAPPA - Industrial Sector Draft 1 15

16 High temperature processes use an entrained bed gasifier, from which the chemicals are recovered in the smelt (comparable to recovery boilers). The high temperatures lead to higher carbon conversion rates, but may lead to more corrosion. Kvaerner Pulping (Sweden) is the leading developer, and a 80 ton/day unit is operating at a Swedish pulp mill. A pressurized system (6-7 bar) is in operation in Sweden since 1994 (7-8 ton/day). Kvaerner Pulping has offered the first commercial sized units ( tpd), and one U.S. order has been received. Implementing a gasifier and combined cycle based cogeneration will increase the electricity production of a pulp mill, making a pulp mill an electricity exporter (baseload). We will estimate the savings for gasification of the black liquor and wood wastes of the pulp mill. For the reference situation we will assume average 1988 energy consumption (electricity consumption of 725 kwh/ton pulp, and 13 MBtu steam/ton pulp. A gasifier and combined cycle will produce approximately 1630 kwh electricity/ton pulp and 9 MBtu-steam/ton assuming a kraft pulp mill, using black liquor and the wood residues in the pulp mill. 31 Many options are available to reduce the steam consumption in the paper machine. Reducing the steam load will not only reduce energy costs, but also the emissions from the boilers. Basically, steam is used in the paper machine to evaporate the water in the paper. Water is removed in three steps; forming, pressing and drying. The last step removes the least water, is the most energy intensive. Increasing the amount of water removed through pressing, will reduce the energy intensive step. 32 New pressing technologies, like the long nip press, increase pressing. Other options include improved heat recovery, improved steam distribution systems, and boiler improvements (see Table 2.2). Cogeneration of heat and power (CHP) based on gas turbine technology is a way to reduce the primary energy needs for papermaking substantially. In the paper machine a large amount of low pressure steam is used, which can be generated from a waste heat boiler from a gas turbine. Classic cogeneration systems are based on the use of a steam boiler and a back-pressure turbine. These systems have a relatively low efficiency compared to a gas turbine system. The net reduction of NO x emissions is dependent on the gas turbines and De-NOx equipment used. Generic measures for gas turbines and industrial cogeneration are described below. STAPPA - Industrial Sector Draft 1 16

17 Table 2.2 Technologies and Measures to Reduce Energy Use and Greenhouse Gas Emissions. Process/Energy-Saving Action Technologies and Measures Estimated Primary Energy Savings Raw Material Preparation Screen out thick chips Improved screening processes Pulping (Mechanical) Recovering heat from grinding Pressurized cyclone Recovering heat from grinding Cyclotherm system Recovering heat from grinding Heat recovery thermomechanical pulp 2.9 MBtu/ton pulp More efficient grinders Switch to conical refiners More efficient grinders Pressurized groundwood Preheating chips to grind easily Chemi-thermomechanical pulping 1.6 to 1.9 MBtu/ton pulp Preheating chips to grind easily Alkaline peroxide mechanical pulping Preheating chips to grind easily Biopulping 1.4 to 3.5 MBtu/ton pulp Pulping (Kraft, Chemical) Reduce heat loss/increased heat recovery Continuous digesters 1.5 MBtu/ton pulp Reduce heat loss/increased heat recovery Continuous digester modifications 2.5 to 4.6 MBtu/ton pulp Reduce heat loss/increased heat recovery Displacement heating of batch digesters Reduce heat loss/increased heat recovery Indirect heating of batch digesters Increased heat recovery Cold blow in batch digesters Pulping (Semi-Chemical) Preheating chips to grind easily Non-sulfur chemi-mechanical pulping 0.9 to 1.2 MBtu/ton pulp Chemical Recovery (Kraft) More efficient concentration of black liquor Improved black liquor evaporators More efficient concentration of black liquor Falling film black liquor evaporation 1.1 to 1.3 MBtu/ton pulp More efficient concentration of black liquor Freeze concentration of black liquor More efficient concentration of black liquor Tampella recovery system 2.1 to 8.2 MBtu/ton pulp More efficient concentration of black liquor Vapor compression evaporation Improved heat retention and recovery Stone preheater for lime kiln Improved heat retention and recovery Lime kiln modifications 0.1 to 0.4 MBtu/ton pulp Replacement of chemical recovery Black liquor gasification 5.0 MBtu/ton pulp Increased production of electricity Black liquor gas turbines 1.4 MBtu/ton pulp Replacement of chemical recovery Direct alkali recovery system Bleaching Alternative delignifying agent Oxygen predelignification 0.2 to 0.3 MBtu/ton pulp Alternative delignifying agent Oxygen bleaching 0.3 MBtu/ton pulp Alternative delignifying agent Displacement bleaching 1.2 to 2.8 MBtu/ton pulp Alternative delignifying agent Ozone bleaching Reduced heat consumption Modifications/fewer stages Papermaking (Forming) More efficient dewatering Gap forming Less pumping/drying High consistency forming 0.3 MBtu/ton Papermaking (Pressing) Increased water removal Extended nip press 0.9 to 3.3 MBtu/ton Papermaking (Drying) Improved heating efficiency Direct drying cylinder firing Improved heating efficiency Infrared drying More efficient use of heat Condebelt drying More efficient use of heat Impulse drying Increased heat recovery Reduced air requirements Upto 0.9 MBtu/ton Increased heat recovery Waste heat recovery 0.3 to 0.6 MBtu/ton Increased drying Infrared profiling General Measures Cogeneration (Gas Turbine) Process control systems 0.3 to 1.0 MBtu/ton Efficient motors Increased use of recycled pulp STAPPA - Industrial Sector Draft 1 17

18 3. Cement Industry 3.1 Process Description Cement production is a highly energy intensive production process. Clinker production is the most energy intensive production step, responsible for about 70-80% of the total energy consumed. Raw material preparation and finish grinding are electricity intensive production steps. Due to the dominant use of carbon intensive fuels, e.g. coal, in clinker making, the cement industry is also an emitter of CO 2 emissions. Besides energy consumption, the clinker making process also emits CO 2 due to the calcining process. In the calcining process limestone is calcined to calcium oxide, emitting about 310 lb C/ton clinker. In the U.S. Portland cement is the dominant cement type use, containing 95% clinker. One major option to reduce clinker demand is the replacement of clinker by additives (e.g. blast furnace slag, fly ash) to produce so-called blended cements. Blended cements have similar qualities but much lower emissions and energy use. The dominant energy consuming process and emission source is the clinker making. Clinker is produced by pyro-processing. The raw meal is burned at high temperatures, thereby calcining the materials to produce clinker. The major kiln type is the large capacity rotary kiln, both wet and dry type. The ground raw material, fed into the top of the kiln, moves down the tube toward the flame. In the sintering (or clinkering) zone the combustion gas reaches a temperature of C, the material C. The kiln can be equipped with a preheater, in which the raw meal is preheated with waste heat from the kiln, before entering the kiln. Introduction of a preheater reduces the energy requirement of the burning process. A preheater that is especially applicable to the dry process is the suspension preheater. The suspension preheater can be used to dry raw material with up to 12% moisture. Another preheater that is especially amenable to the wet process is the grate preheater. Pellets or briquettes, pressed of raw material slurry, are placed on a grate that travels through a closed tunnel. Additionally, in the dry process, a precalcinator can be integrated between the kiln and the preheater. This is a chamber with a burner, in which 80-90% of the CaCO 3 can be dissociated before entering the kiln. Application of a precalcinator allows a shorter kiln and can reduce energy consumption by 5 to 10 %, by reducing radiation losses of the kiln. About % of the fuel is burned in the precalcinator, 30-40% in the kiln. The lower combustion temperatures in the precalcinator will also reduce NOx emissions. Because the typical operating temperatures of these kilns differ, the NO x formation mechanisms also differ among these kiln types. In a primary combustion zone at the hot end of a kiln, the high temperatures lead to predominantly thermal NO x formation. In the secondary combustion zone, however, lower gas-phase temperatures suppress thermal NO x formation. Energy efficiency is also important in reducing NO x emissions; for example, a high thermal efficiency means less heat and fuel are consumed and, therefore, less NO x is produced. Table 3.1 summarizes typical kiln performance. In the U.S. 131 cement plants are operating in 39 states. Plants are most often located near limestone reserves, and may not be near major urban areas. Due to the low cost of cement and heavy weight, cement is not transported over long distances. This leads to regional markets, with differences in processes used, as well as production costs. STAPPA - Industrial Sector Draft 1 18