energy end-use models for pulp, paper, and paperboard mills

Pergamon 0360-5442(95)00039-9

Energy Vol 20, No 10, pp 1005-1019, 1995 Copyright © 1995 Elsevier Science Ltd

Pnnted m Great Britain All nghts reserved 0360-5442/95 $q 50 + 0 00

ENERGY END-USE MODELS FOR PULP, PAPER, AND PAPERBOARD MILLS-]

LUIS GIRALDO and BARRY HYMAN$ :~Department of Mechamcal Engmeenng, FU-10, Unmverslty of Washington, Seattle, WA 98195, U.S A

(Recewed 24 January 1995)

Abstract--Thts paper deals with energy end-use models for pulp, paper, and paperboard mtlls The models are consistent wtth data published in the U.S Department of Energy's 1991 Manufac- tunng Energy Consumption Survey (MECS) A graphical framework for depicting these energy flows is presented. Development of these models is a key step in creating energy process-step models for pulp, paper, and paperboard produchon. The applicability of the modeling approach and framework to other industries is &scussed.

INTRODUCTION

Two approaches have traditionally been used to model energy pattems in manufacturing processes. The first is concentrated on generic end-uses such as machine drive, lighting, HVAC, and process heating; the second is focused on sequential process steps such as washing, coolong, mixing, etc. Each only gives a partial picture of energy-usage patterns, and both suffer from the inability to calibrate the models with systematically collected data. A general approach for combining end-uses and process steps into calibrated energy consumption models of manufacturing processes was recently completed.~ This paper is the first part of an effort to apply that technique to pulp, paper, and paperboard mills.

MECS

The Manufacturing Energy Consumption Survey (MECS) conducted by the U.S. Department of Energy is the most comprehensive source of manufacturing-energy consumption data.: Published every 3 years since 1985,§ MECS details manufacturing-energy use by industry, fuel type, end-use, and geographic region. The 1991 MECS,¶ the most recent edition, provides energy data for all 20 manufacturing major groups designated as Standard Industrial Classifications (SIC) 20-39. The SIC system also disaggregates each 2-digit SIC major group into 3-digit SIC industry groups and 4-digit SIC industries, and energy data for 40 4-digit SICs are included in the 1991 MECS. MECS definitions, variables, and data are the logical foundation for building manufacturing-energy consumption models because of wide manufacturing sector coverage, use of statistically rigorous samphng and data analysis techniques, availability of regular updates, and consistent data treatment across all industries.

The Paper and Allied Products (SIC 26) major group is composed of the five 3-digit industry groups and the 17 4-digit industries listed in Table 1. This paper deals with SIC 2611-pulp mills, 2621-paper mills, and 2631-paperboard mills; these three industries used 94.5% of the energy consumed by the SIC 26 major group in 1991. We wall describe-our analysis for SIC 2631 in detail, and present the results for SIC 2611 and SIC 2621 in summary form.

tThls research was supported by Battelle-Paofic Northwest Laboratory under Task Order 210457 and Bonneville Power Adnums- traUon under Purchase Order DE-AP79-93BP06172. Preparation of the manuscnpt was supported under Grant DE-FG06- 89ER-75522 or DE-FG06-92RL-12451 with the U.S. Department of Energy. By acceptance of this article, the pubhsher acknowledges the U.S Government's right to retain a non-excluswe, royalty-free hcense in and to any copyright covenng this paper

~:To whom all correspondence should be addressed §Starting in 1994, MECS wall be conducted every 2 years ¶When th~s paper was wntten, the data tables for the 1991 MECS were avadable but the document aself had not yet been

pubhshed. Hereafter we will refer to th~s data source as the 1991 MECS. E~v zo/lo-o 1005

1006 Lms Glraldo and Barry Hyman

Table 1. Paper and alhed products SIC mdustry group and mdustry classtfication.

SIC Industry Name SIC Induslries Group

261

262

263

265

267

Pulp mills

Paper mills

Paperboard mills

Paperboard boxes and c~ntainers

Converted paper and paperboard products

2611

2621

2631

2652, 2653, 2655, 2656, 2657

2671, 2672, 2673, 2674, 2675, 2676, 2677, 2678, 2679

Energy data from MECS Tables A4, A6, A16, A17, and A23t for the SIC 26 major group and its three key industries are presented in Table 2.

To avoid double counting energy in Table A4, the MECS definition of Net Electricity, excludes electricity generated onsite from combustible fuels, i.e.

Table 2. Paper industry data extracted from MECS Tables A4, A6, A16, AIT, and A23 (1012 Btu).

M£CS Sowcc

Table A4

TableA6

Tabl~ A16

Tab~Al7

Table A23

Total

Set Electricity Residual Fuel Oil

Distillate Fuel Oil ~letoral Gas

Energy Form

LPG

Coal Coke and Breeze

Other

Total Bywoducts

Blast Furnace/Coke Oven Gases

Waste Ges Petroleum Coke

Pulping Liquor

Wood Chips, Bark Waste Oils, Tars and Waste Materials

Net Demand for Electricity Purchases

Transfers In Total Onsite Generation

Sales and/or Transfers Offsite

Cogeneration Renewables Other

Purchased Steam from Utility Purchased Steam front Nouotility

Paper and Allied Products

Major Group (SIC 26)

1472

201 156

9 548

W 296

W 1257

1213

0

5 857 348

3

375

217

4 184

31

155 10 19

8

Ii

Pulp Mills

(SIC 261 l)

9

28 1

32

1

7

0 221

223

0

1

178

45

29

10

0

21

2

17 W W

Paper Mills

(SlC 262 t)

1204

ll2

85

W 260

2 193

W 548

52O

0

0

W 354

W *

208

w

w 105

21

92

9 4

(sic 2631)

832

35 W

I 185

$

W

0

45O

467

0

0 !

326 139

1

92

W

W

57

8

46

W

W

2 6 8 2

Note: Humbe~ in bold font ere column totals within each MECS table. Values in an', horizontal row for SIC 2611, 2621, and 2631 do mot add to the value for SIC 26 because of ether SIC 26 industries not tabulated st the 4-digtt level. * = The nmaeri~d value is leu than 0.5. but

conlribalion is included in higher level totals. W = Data withheld to avoid d~lming data for individual establi~m~n~. Q = Data withheld be¢_~_,_,~ of the large Relative Standard En.or.

tWe use italics to refer to MECS tables. *We capitahze MECS energy and end-use variables to distinguish them from generic types and uses.

Energy end-use models 1007

Net Electricity = Electricity (purchases - Sales) + Electricity from Noncombustible Renewables. (1)

Also in Table A4, Other is defined as

Other = Byproducts + Steam (purchases - Sales) +

Steam from Noncombustible Renewables + Fuels Not Listed Separately, (2)

where the Byproducts component is disaggregated in Table A6. Table A16 shows the components of Net Demand for Electricity; a distinction is made between Purchases and Transfers In but Sales and Transfers Offsite are combined. We will use the terms Purchases and Sales to include electricity-transfer transactions (and adopt the same convention with regard to steam transactions). Therefore, we can write

Net Demand for Electficlty = Electricity (Purchases - Sales) + Total Onsite Electricity Generation. (3)

The end-use data for SIC 2631 from Tables A36 and A38 are summarized in Table 3. Similar data are included in Tables A36 and A38 for SIC 26, 2611, and 2621.

Particularly striking is the number of gaps in the published numerical values in Tables 2 and 3. However, even if all these gaps were filled in, the data are still not sufficient for constructing complete end-use models. The major missing pieces are: estimates of the efficiencies of onsite electricity and steam generation, allocation of purchased steam and onsite generated steam to end-uses, and utilization of recovered waste heat.

The objectives of this paper are to build complete, fully documented, end-use models for pulp, paper, and paperboard mills that are consistent with the 1991 MECS data and to depict the energy flows between inputs and end-uses in a manner that clarifies the energy-use patterns underlying the data. The generic graphical format for the energy-flow models (originally developed in Ref. 3) and the specific quantitative results we obtained for SIC 2631 are shown in Fig. 1. The rest of this paper is devoted to describing how we used Tables 2 and 3 and supplementary sources to obtain the values displayed in Fig. 1 for SIC 2631. Counterparts to Fig. 1 for SIC 2611 and SIC 2621 are presented in Figs. 8 and 9.

FUELS, BYPRODUCTS, AND NET STEAM

We focus first on using Table 2 to quantify the six fuel inputs for SIC 2631 depicted in the lower left corner of Fig. 1. The numerical values for Distillate Fuel Oil, Natural Gas, and Coke & Breeze are taken directly from Table A4. We next convert the asterisk for Liquefied Petroleum Gas (LPG) in Table A4 to zero. Then, from column totals in Table A4, we find

Residual Fuel Oil + Coal = 130 x 1012 Btu.'

From row totals in Table A4 for SIC 26, the following inequalities must be satisfied for SIC 2631:

Residual Fuel Oil ~< 43 x 1012 Btu, Coal ~< 96 × 1012 Btu.

With the aid of these relations, we estimate the values for Coal and Residual Fuel Oil shown in Fig. 1. We next turn to the Net Steam and Other Energy Sources Except Net Steam inputs in the left column

of Fig. 1. Net Steam is defined analogous to the Net Electricity definition in Eq. (1), i.e.

Net Steam = Steam (Purchases - Sales) + Steam from Noncombustible Renewables. (4)

While each of the three terms on the right-hand side of Eq. (1) are displayed separately in the upper left corner of Fig. 1, there is insufficient MECS data to similarly disaggregate Net Steam. Hence we depict Net Steam as a single entity in Fig. 1. Substituting Eq. (4) into Eq. (2) yields

Other = Byproducts + Net Steam + Fuels Not Listed Separately.


Electricity

I Ek:ctricity Sold

Electricity fi~n Noncombustible

Renewables

Net Steam

Residual Fuel Oil

Dmfillw~c Fuel Off

Nat~nd Gas

I Liqudied Pc~olcum G-~

Coal

43

f

732

32 f - ~

,43 1"5 [o I 9O

I Coke and I 0 Breeze

sou~s ~ - i s Net Steam

467

$ I 49

57

Omste P_,lcctncity Oamation

I Umu~vemd Was~ He-*

44 _[ W~ I-I1~ -I

T 217

1V,,0.71 730

1 19

) 432

92

L

1-23̀

467

6'74

7 oJ

Process

Coo~ud

El~o-Ch~ic~l

Process Use

L 2

I-

Facility L 2 ltVAC r

Facility L 3 Li~ F

Famhty L I Support ]

Tmnspormaoa

ot~ L 0 Nms-Proc~.s

Use

Fig. 1. Energy flows m paperboard nulls, SIC 2631 (1012 Btu)

We assume that all Byproducts (mostly pulping liquor, wood chips, and bark according to Table A6) and all Fuels Not Listed Separately are combustibles that are consumed as boiler fuel. Since we account for boiler efficiency when producing steam onsite from combustible energy forms but assume (as depicted in Fig. l ) that Net Steam goes directly to end-uses, we rewrite the above as

Other = Other Energy Sources Except Net Steam + Net Steam, (5)

where

1010 Luis Oiraldo and Barry Hyman

Other Energy Sources Except Net Steam = Byproducts + Fuels Not Listed Separately. (6)

Using the numerical values for Other in Table A4 and for Total Byproducts in Table A6 and assuming that Fuels Not Listed Separately = 0 x 10 ~2 Btu, Eqs. (5) and (6) provide

Other Energy Sources Except Net Steam = 467 x 1012 Btu,

Net Steam = 13 x 1012 Btu.

(7)

(8)

ELECTRICITY

We turn now to the upper left comer of Fig. 1 to examine the acquisition and disposition of electricity. Using the column total from Table A16, we get for SIC 2631 (recalling that we include Transfers In as part of Purchases)

Electricity Purchases = 43 x 1012 Btu. (9)

Substituting Eq. (9) and the values of Net Electricity from Table A4 and Sales and/or Transfers In from Table A16 into Eq. (1) yields

Electricity Generated from Non combustible Renewables = 0 x 1012 Btu. (10)

The results of Eqs. (9) and (10), together with the appropriate numerical values from Table A16, are depicted in the upper left comer of Fig. 1.

END-USE ALLOCATIONS

In this section, we allocate the energy forms to the five process end-uses displayed above the dashed line and the five non-process end-uses displayed below the dashed line in the right column of Fig. 1. We allocate Net Demand for Electricity separate from Fuels and Byproduct Energy allocations.

Allocating electricity to end-uses

We allocate Net Demand for Electricity among Boiler Fuel and end-uses according to the data in the last column of Table 3.I" The available subtotal for Total Process Uses provides

Process Cooling and Refrigeration + Other Process Use = 2 x 1012 Btu

and we assign this entire amount to Other Process Uses. For the Total Non-Process Uses, we convert both * and Q entries to zero to be consistent with the related individual and subtotal numbers in the last column of Table 3.

Allocating fuels and byproducts

We do this allocation in two stages. First, we apply each of the seven inputs in the lower left comer of Fig. 1 either to end-uses (indicated in Fig. 1 attached to horizontal line segments) or to generate electricity or steam onsite (indicated in Fig. 1 attached to vertical line segments). Second, we decompose those allocations into individual end-uses and modes of steam/power generation.

There are sufficient data in Table 3 to do the first-stage allocation for all fuels except for Natural Gas (NG) and Other Energy Sources Except Net Steam. We had earlier concluded that this latter input was identical to Byproducts [compare the Total Byproducts entry in Table A6 with Eq. (7)], all of which serves as boiler fuel.

tAccording to MECS, ConvenUonal Electricity Generation refers to electricity generated via gas turbines or piston engines (as opposed to steam turbines). As indicated in Table 3, MECS treats Conventional Electricity Generation as one of six Non- Process end-uses. However, as depicted in Fig. 1, we treat fuel consumed for Conventional Electricity Generation in the same manner in which we treat boiler fuel as input to an intermediate energy conversion process.


Allocating NG requires moving directly to the Stage 2 disaggregation. The values in the NG column of Table 3 provide

(Total Non-Process Uses + End-Use Not Reported)Nc = 12 x 1012 Btu. (11)

From the last row in Table 3 (with the W, Q, and * entries converted to zero), we find

End-Use Not ReportedN~ + End-Use Not ReportedD,st, nate Fuel O,1 = 6 x 1012 Btu. (12)

But since Table 3 also provides the total consumption of Distillate Fuel Oil as 1 x 1012 Btu and allocates it all to Non-Process Uses, Eq. (12) reduces to

End-Use Not ReportedNc = 6 x 1012 Btu. (13)

Thus, Eq. ( 11 ) leads to

Total Non-Process USeSNG ---- 6 × 1012 Btu. (14)

Next, we distribute the End-Use Not Reported amount for NG from Eq. (13) among the three major end-use categories in the same proportion as the reported NG use is distributed among those same categories. This gives the following revisions to the main category subtotals:

Boiler Fuel = 141 x 1012 Btu,

Total Process Uses = 38 x 1012 Btu.

(15)

(16)

We now subtract Conventional Electricity Generation from the Total Non-Process Uses value given in Eq. (14) since we include fuels used to generate electricity as part of the vertical line segments in Fig. 1 that serve as input to onsite steam/power generation. To do this, we first convert the asterisk entry for NG Facility Support in Table 3 to zero. We then combine Eq. (14) with the Total Non- Process Uses value in Table 3 for NG to arrive at

Conventional Electricity Generation + Other Non-Process Use = 4 x 1012 Btu.

We divide this evenly among the two activities to get

Conventional Electricity Generation = 2 x 10 12 Btu. (17)

We subtract this from Eq. (14) and combine it with Eq. (15) to get

NG for onsite steam and power generation = 143 x 1012 Btu. (18)

This is the value displayed in Fig. 1. To simplify the depiction in Fig. 1, all fuels allocated to end-uses are aggregated to 51 x 1012 Btu

and all fuels used for steam/power generation are aggregated to 732 x 1012 Btu, The 51 × 1012 Btu are allocated to the individual end-uses according to Table 3 as modified by the above discussion plus our judgment that Process Heating accounts for 90% of the Process Uses of NG, These allocations are summarized in Table 4 but are not entered into Fig. 1 yet because steam and recovered waste heat must also be allocated to those end-uses. But first we turn to the onsite steam/electricity generation activities.

ONSITE STEAM AND ELECTRICITY GENERATION

In this section, we focus on the portion of Fig. 1 that accounts for onsite steam and electricity generation. In general, onsite electricity has three components: Cogeneration, generation from Non- combustible Renewables, and generation from fuels with no waste heat recovery. Since no electricity


Table 4. Allocauon of fuels to end-uses for SIC 2631 (1012 Btu).

End-use Residual Distillate Natural Coal Total Fuel Oil Fuel Oil Gas

Process Heating

Process Cooling and Refi'igeration

Machine Drive

El©ctro-Chemical Process

Other Process Uses

Facility HVAC

Facility Lighting

Facility Support

Onsite Transportation

Other Non-Process

34

0

Total 6 1 42 2 51

42

0

is generated from Non combustible Renewables in SIC 2631 [see Eq. (10)], Cogeneration and generation from fuels with no waste heat recovery are the only non-zero components. Each of these components can involve direct (or conventional, in MECS parlance) generation from fuels or indirectly via steam produced in a boiler. We begin the analysis by estimating boiler efficiency.

Boiler efficiency

We estimate boiler efficiency (r/) based on the efficiencies for each fuel used weighted by the amount of each fuel used for steam production. Using the fuel-specific efficiency data summarized in Table 5

Table 5. Efficwncy of steam producUon by boder fuel.

Fuel Efficiency

Oil

Gas

Coal

Bark

Spent Liquor

83%

82%

81%

64%

65%


gives 7) = 0.71.4 From Eqs. (17) and (18), 2 × 1012 Btu of the 143 × 1022 Btu of NG depicted in Fig. 1 are for Conventional Electricity Generation. So only the 141 x 1022 Btu of NG that goes to the boiler are included in this efficiency calculation.

Cogeneration

We assume that all Cogeneration in SIC 2631 is via the steam topping cycle. The component of Fig. 1 that represents Cogeneration is depicted in Fig. 2.

From Table A17, electricity generated in SIC 2631 using Cogeneration is

Cogeneration = 46 × 1022 Btu. (19)

We work backward from this value to estimate the amount of fuel input required. A typical efficiency for converting steam to electricity is 0.57. 5 Thus, 81 × 1012 Btu of steam are required as input to the turbines, of which 35 × 1012 Btu are rejected as waste heat. At a 0.71 boiler efficiency, 114 x 1012 Btu of fuel are required as input to the boiler. The total waste heat from the turbine and boiler is then 68 × 1012 Btu. If the overall efficiency of Cogeneration is 0.65, the amount of waste heat recovered for end-use applications is found from 0.65 = (46 + x)/114 to be 28 × 1012 Btu. The remaining 40 × 1212 Btu of waste heat are unrecovered.

Electricity generation from fuels with no waste heat recovery

The two most important methods for power generation with no waste heat recovery in SIC 2631 are gas turbines and steam turbines. We deal first with gas turbines.

According to Eq. (17), 2 x 10~2Btu of NG are used for Conventional Electricity Generation. Assuming a conversion efficiency of 0.40, we conclude that 0.8 x 1012 Btu of electricity are generated while 1.2 x 1012 Btu are unrecovered waste heat. Figure 3 shows the relevant energy flows for this power generation mode.

To estimate onsite power generation from steam turbines with no heat recovery, we begin by disaggre- gating onsite power generation according to the categories listed in Table A17, viz.,

46

Onsite Electricity Generation

Um'eeovered Waste Heat

T40

Waste Heat

T33

81 { Boiler • =0.71

114 -1

28

Fig 2

to end uses Cogeneratlon in SIC 2631 (I0 ~z Btu).


0.8

T O~ilc

Electricity Generation

T 2.0

Unrecovered Waste Heat

.2

1.2 ~! Waste Heat

Fig. 3. Conventional electncRy generation in SIC 2631 using gas turbines (10 m2 Btu).

Onsite Electricity Electricity Generated Generation = Cogeneration + from Non combustible + Other. (20)

Renewables

From Eq. (10), Electricity Generated from Non combustible Renewables is zero. Hence we conclude that Other in Eq. (20) represents Total Onsite Electricity Generation except for Cogeneration. Substitut- ing the numerical values from Tables A16 and A17, we find that onsite electricity generation from fuels with no waste heat recovery provides 11 x 10 t2 Btu. Subtracting the 0.8 x 1012 Btu depicted in Fig. 3 as being generated using gas turbines, we have 10.2 x 10 ~2 Btu of electricity generated by steam turbines. Applying the 0.71 and 0.57 efficiencies for fuel-steam and steam-electricity conversions, we calculate the flows shown in Fig. 4.

10.2

Onsite 7.7 [ Electricity Generation ~1

17"9T ~]

25.2

Unrecovered Waste Heat

15.0

Waste Heat

T 7.3

Boiler =0.71

Fig. 4. Electricity generation in SIC 2631 using steam turbines with no heat recovery (10 t2 Btu).


57

T Total Onsite Electricity Generation

140

U m ' e ~ v ~ W L ~ Hem

56

44 I i Waste Heat

41 99

I Boiler 11 =0.71

-I

29

142 to

from fuel end uses Sotlrc.~s

Fig 5 0 n s i t e electricity generaUon m SIC 2631 (1012 Btu).

We combine all modes of electricity generation by superimposing Figs. 2, 3 and 4 to obtain the flows shown in Fig. 5.

Steam generation

Figure 1 shows that fuels with an energy content of 730 x 10 t2 Btu are burned in the boiler. With a 71% efficiency, that yields 518 × 1012 Btu of steam. As shown in Fig. 5, 99 x 1012 Btu of this steam are used for electricity generation, leaving 419 × 1012 Btu to be distributed among end-uses. The remaining 212 × 10 t2 Btu are waste heat. To preserve the energy balance for the boiler, we also transform the 5 × 1012 Btu of electricity required for boiler operations to waste heat. Figure 6 summarizes these energy flows associated with steam generation.

We assume that the only end-uses consuming steam are Process Heating, Machine Drive, Other Process Use, and Facility HVAC. We distribute steam among these end-uses in the same proportion

waste heat

217

99 steam for J

electricity generation 4: Boil©r 730 q = 0.7 ! ] -,

419 from fuel

sources steam for end uses

Fig 6. Onslte steam generauon m SIC 2631 (10)2 Btu).

electricity for boiler e ~rations

5

L F


as they consume combustible fuels (see Table 4), i.e., 95% for Process Heating, 3% for Machine Drive, 1% for Other Process Use, and 1% for Facility HVAC.

Waste heat recovery

We distribute waste heat recovered from Cogeneration and Process Heating to end-uses in the same proportion as steam. In Fig. 7, y represents the amount of steam and recovered waste heat that is allocated to end-uses. Process Heating receives 0.95y of this thermal energy plus 2 x 1012 Btu of electricity (Fig. 1 ) and 42 x 10 t2 Btu of direct fuel use (Table 4). The 30% of that Process Heating utilization that is assumed to be recovered is combined with the 28 x 10 ~2 Btu of waste heat recovered from cogeneration (Fig. 5) and added to the 419 x 10 ~2 Btu of steam coming from the boiler (Fig. 6) and the 13 x 1012 Btu Net Steam [Eq. (8)]. The energy balance at node A in Fig. 7 provides y = 663. This allows us to complete the flows in Fig. 7 and consolidate those results with Figs. 5 and 6 to complete Fig. 1.

Similar procedures lead to the results shown in Figs. 8 and 9 for pulp mills (SIC 2611) and paper mills (SIC 2621).

CONCLUSIONS

We have presented detailed end-use models of 1991 energy consumption in pulp mills (SIC 2611), paper mills (SIC 2621), and paperboard mills (SIC 2631). In each model, electricity, fuel, steam, and recovered waste heat are allocated among the five process end-uses and five non-process end-uses covered in the 1991 MECS. The generic graphical representation of energy flows (Figs. 1, 8,and 9) is a powerful tool to clarifying the patterns underlying the data that is scattered over seven MECS Tables.

While the availability of the 1991 MECS end-use data was the crucial element in developing credible models, the MECS data had many gaps and had to be supplemented by data from other sources and

Net Steam

unrecovered waste heat

L.. Waste Heat r

0.30(0.95y + 2 + 42) + 28

13

steam from boiler

~ 419

432 A

0.95y + 2 + 42

.95y~

.03y~

.Oly~

Process Heating

Machine Drive

Other ProcessU~

.01 y~ [ Facility q HVAC

[_ .2

42

V"

Fig. 7. Flows reqmred to allocate waste heat and steam to end-uses for SIC 2631 (10 ~2 Btu).

electricity

fuel


Puurchased Electricity

Elecmctty Sales

Electrtctty from Noncombu.~ble

Renewables [

Net Steam

Restdual Fuel 011

Dlsttllate Fuel Otl

Natural Gas

Lsquefied Petroleum

Gas

Coal

Coke and Breeze

10

I 21

Total Omite ] Eleetrtctty 15 Geue~ion

0 - - ~ 35

278

(

278

Other Energy Sources Except

Net Stem I

Umcovered Waste Heat

T 270

Waste Heat

89

Boiler q,=O 6g

t 154

151

165

29

I ;I ° tJ

249

250

0q

°'I Ftg 8. Energy flows in pulp mills, SIC 2611 (10 ~2 Btu)

Heating

R c ~ o .

D~ve

EIcolzo-Chemlcal Processes

Other Process Use

Faedity HVAC

Faedtty Lighting

F~ih~ Support

Ornate Tm3spor~uon

Non-Proems Use

/ 29

many assumptions to complete the models. These additional data sources, plus all our estimation methods and assumptions are explicitly described in this paper so the models can be easily modified to reflect different data and assumptions. In particular, an important refinement of the model structure would be to include estimates of losses from steam distribution systems between the boiler and the end-uses. The main barrier to this and other refinements of the modeling framework is the unavailability of reliable data. Some of that data may be available for specific industries from their affiliated trade associations.

The framework developed here can be applied to construct end-use models for any of the 37 other


Elecai©ity

E~.eic~ ]_ Sales [~

- ~ I Nomcmnlo~m'ble RenewabRe [

-I Steam

Residual Fuel Oil

Distillate Fucl Oil

Natural Gas

Liquefied Peeroleum

Gas

Coke and Breeze

Oth~

Net Steam

124

21

J -I

10

f

988

•I 84

105

To~I Omite Eie©u'i©ity Gemration

76

162 ~.

978

29

Umeeovered Waste Heat

194~

Waste Heat

T 267

Boilex -q-0.73

•,t 552

581

2O8 ID

I33o I

73

199

259 76 657 987

193

193

520

520

-I o] q

Process tle, eng

Pmeea CooUnS ©rid Refrigemion

Drive

Eiec~-Chem~ Processes

Other Proa~ Use

I 2

I- ]2 r LI82 r L, l- L0 !-

F.~ l_ 7 HVAC ]

Facility I-- 6 Ligheng ]

Facility l_ 2 Support ]-

Omite L 0 Tnmsportati~ l-

o~ Lo Non-Proc~s

Use ]~

2O5

Fig. 9. Energy flows in paper mills, SIC 2621 (10 ~2 Btu).

4-digit SIC manufacturing industries included in MECS. While useful in their own right, these end- use models can also serve as control totals for MECS-based process-step models using the approach described in Ref. 1.

REFERENCES

1. B. Hyman and T. Reed, Energy---The International Journal 20, 593 (1995). 2. "Manufacturing Energy Consumption Survey: Consumption of Energy 1988," U.S. Department of Energy

DOE/EIA-0512(88), Washington, DC (May 1991).


3. B. Hyman, S. Freeman, and L. G~raldo, "Generic Description of Manufacturing Energy Flows," Mechanical Engineering Department, University of Washington, Seattle, WA (Feb. 1994).

4. T. J. Grant, "Patterns of Fuel and Energy Consumption in the U.S. Pulp and Paper Industry," American Paper Institute, New York, NY (1985).

5. M. H Chiogioji, Industrial Energy Conservation, pp. 173, 178, Marcel Dekker, New York, NY (1979).

energy end-use models for pulp, paper, and paperboard mills

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