Tomlinson Boiler Air Emissions

Modern Tomlinson boilers are characterized by emissions of criteria pollutants that are similar overall to grid power (some are higher, like CO and PM, while others are lower, like SO₂ and NO_x). The most significant pollutants, in terms of both environmental impacts and relative emissions rates from Tomlinson boilers, are NO_x and particulates. While many furnaces already have particulate controls in place, there is no effective form of NO_x after treatment. Furnace rebuilds and replacements trigger the New Source Review (NSR) process, which generally results in process modifications being made to reduce TRS emissions. Installation of more efficient particulate control is also common following a NSR, and generally modern furnaces have better design and controls than older ones, which results in lower overall emissions. Table 9.8 presents a qualitative analysis of relative environmental impact of different mill‐level emissions, together with relative emission rates for controlled and uncontrolled Tomlinson furnaces and with biorefinery technology (Argonne National Laboratory 2006; USEPA 2002).

Economic Development Opportunities

Biorefineries could have important economic development benefits, stemming from the enhancement of the competitiveness of the pulp/paper industry. The financial analysis illustrated the potential for attractive financial returns and significantly increased cash flows relative to Tomlinson systems. The related economic development benefits include preserving and growing employment in the industry and potentially adding to rural and semi‐rural employment by creating increased demand for raw materials for paper production and biomass supply and, in the longer term, energy and other products derived from biomass. On a national scale these impacts are likely to be modest, but in certain regions or states (especially southeast, upper mid‐west), the impacts could be very significant. However, if biorefineries help catalyze a new, larger, bio‐energy industry, the economic impacts would be more substantial at the national level as well.

A kraft mill that adopts BLG exclusively to displace the boiler and to produce more electricity can be profitable (Larson et al. 2003, 2006a). But at present, a much developed biorefinery with a diverse product range adds many new options that may become economically attractive if BLG technology can solve a few technical challenges (Bajpai 2008). Current BLG technology has excited new interest in biorefinery and has the ability to leverage BLG into a wide portfolio of products, retrofitted to different types of mill, including medium‐sized mills facing shutdown. The Chemrec development plant in Piteå, Sweden, is the most developed BLG model with strong industry momentum. Volvo Technology Transfer AB and affiliates new hold a majority share. The biorefinery aims to produce pulp (and paper) and to use the BLG syngas to produce DME fuel. DME is clean‐burning and has advantage over diesel. Chemrec has successfully implemented a DME demonstration in Piteå. The Chemrec 2020 plan anticipates five large and three small BLGDME and BLGMF plants. Economic projections are attractive. This is largely due to return from DME (Ekbom et al. 2003, 2005; Connor 2007).

Table 9.8 Qualitative indication of relative environmental impact of different mill‐level emissions, together with relative emission rates for controlled and uncontrolled Tomlinson furnaces and with biorefinery technology.

Source: From Larson et al. (2006b).

Pollutant/discharge	Relative environmental impact of pollutant	Relative emissions rates from Tomlinson furnace (uncontrolled)	Relative emissions rates with control on Tomlinson	Relative emission rates expected with biorefineries
SO2	H	L	L (not required)	VL
NOx	H	M	Md	VL
CO	L	M (can be highly variable)	Md	VL
VOC	H	L	Ld	VL
PMb	H	Hc	L–M	VL
CH4	L–M	L	Ld	VL
HAPs	M–H	Lc	Lc	VL
TRSe	L	L	Ld	VL
Waste Waterf	M–H	L	L	VL–L
Solidsa	L	L	L	L

VL, very low; L, low; M, moderate; H, high.

^a General importance, not specifically for the P&P industry.

^b PM, particulate matter. Of greatest concern with PM emissions are fine particulates smaller than 10 and 2.5 μm in diameter (PM10 and PM2.5 respectively).

^c Current MACTII rules are expected to result in about a 10% reduction of HAPs and a modest reduction in PM.

^d Not generally practiced other than by maintaining good combustion efficiency.

^e Total reduced sulfur.

^f For power systems, the issue is mainly one of the cooling water (quantity and discharge temperature).

If biorefineries were to penetrate slowly rather than rapidly into the market, the cumulative (25‐year) energy savings would be roughly 2–12 quads less. Assuming a rough average fossil fuel price range of $5–10/MMBtu (which corresponds to $29–58/barrel of crude oil or 1.7–3.4 ¢/kWh of electricity), the corresponding added energy costs would be $10–120 billion over this period (Larson et al. 2006a, b).

For certain emissions, it is also possible to estimate a market value since there are existing cap‐and‐trade markets. At $625/T (the recent price for SO₂ allowances), and assuming prices remain at this level in real terms, SO₂ reductions have a cumulative value of up to $301 million over the 25‐year period following commercial introduction of biorefineries. (In some of the configurations, the net SO₂ benefit is negative because of the large decreases expected in grid power SO₂ emissions discussed earlier.) NO_x, if valued at $2100/T over the same period, has a market value as high as of $1.5–2.6 billion in the Aggressive market penetration scenario. If a system for trading CO₂ is put in place, the CO₂ value could be as high as $37 billion in the Aggressive market penetration scenario at a price of $25/MT of CO₂. While it will likely be difficult for biorefineries to capture all of these additional revenue streams, these estimates provide an indication of the value to the nation of emissions reductions that biorefineries could enable. Thus, in addition to energy costs savings, the value of lost SO₂, NO_x, and CO₂ emissions reductions due to slower market penetration could also be in billions of dollars (Larson et al. 2006b).