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Value Engineering for Selection of Gas Sources in
Gas Supply Engineering
Liu JiayouDepartment of resources and civil engineering
Shandong University of Science and Technology
Taian, China
E-mail: [email protected]
AbstractApplying an appropriate city gas source is important
for reducing the costs of living and production, energy-saving,
environmental protection and city long-term planning. According
to the principle of value engineering (VE), the paper puts
forward a model for selecting city gas source. The model includes
identifying research object, function analysis, cost analysis and
value analysis. The model mainly focuses on function analysisand a functional evaluation index system of gas source is
constituted, the improved analytical hierarchy process (AHP) is
used to determine the weights of the indexes for function
coefficient calculation. Combining the technical and economic
characters of gas sources, value index is formulated as the
evaluation parameter to select the optimal scheme. An
application case is studied using the model, and the selected gas
source long-distance pipeline natural gas (LPNG) is suitable for
the city.
Keywords-value engineering; gas source; function analysis;
value index
I. INTRODUCTIONCity gas is one of the most important energy resources for
urban residents living and industry production. An appropriategas source is of significant for reducing the costs of living and
production, energy-saving, environmental protection andpromoting sustainable development of cities. At present, citygas sources mainly include LPNG, liquefied natural gas(LNG), compressed natural gas (CNG), liquefied petroleumgas (LPG), manufactured gas (MG) (including coal-generatedgas, oil-generated gas, etc) [1]. And marsh gas is used as gassource in some small towns. Because of differentcharacteristics of gas sources and diversity of cites locationand long-term planning, many factors should be considered
when selecting gas source. In gas supply engineering, thecommon method for selecting gas source is that thecharacteristics of the gas sources and city gas pipeline planningare qualitatively analyzed, and then the optimal gas source isdetermined by comparing the annual cost of gas sources
projects. The method is more subjective and evaluation index issimplex [2]. The paper presents a model based on VE forselecting optimal city gas source.
II. MODEL FORSELECTING CITY GAS SOURCE BASED ONVE
A. Principle of VEVE or value analysis (VA) is a scientific techno-economic
comparison method developed by Lawrence D. Miles. Themethod uses all existing technologies, knowledge, and skills toefficiently identify costs or efforts that do not contribute to thecustomer's needs and wants [3]. VE focuses on functionanalysis of the research objects and aims to gain the maximum
benefits and the needed functions at the lowest life cycle cost(LCC). The expression for the method is (1).
CFV /= (1)
Where, V is value or value index of the scheme, F is the
function or function coefficient of the scheme, C is cost orcost coefficient of the scheme.
To gain the maximum benefits, F should be greater andC should be smaller. A greatest value of V shows thefunctions of the research object are achieved at the lowest LCCand the object should be the optimal one.
B. Model for Selection of Gas Sourcse in Gas SupplyEngineering
The program of VE includes identifying research object,function analysis, cost analysis and value analysis.
1) Determining research objectTo select the optimal city gas source using VE method,
various gas sources should be identified as the research objects
[3].
2) Function analysisCity gas source takes the role of supplying gas for varioususers safely and reliably, the characteristics of gas sources mustmeet the requirements of different users and the requirementsof city long-term planning, the design and construction of gassource engineering must follow the relevant norms andregulations and strive to reduce the project cost. According tothe suggestion of experts and gas engineering requirements, thefunctional evaluation index system of gas source is constructedand shown in Fig.1.
978-1-4244-4813-5/10/$25.00 2010 IEEE
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The importance of the evaluation indexes in Fig.1 isdifferent, it is necessary to determine the weights of the indexesfor calculation of function or function coefficient. In the paper,the weights are determined using improved AHP. Assumingm experts evaluate the importance of n indexes on the samelayer. According to the principle of AHP, a judgment matrix is
established, then an eigenvalue weight matrixB can be gainedusing the concept of the optimal delivery matrix of
antisymmetric matrix [4], [5], [6].
==
mnmm
n
n
nm
bbb
bbb
bbb
BB
"
####
"
"
21
22221
11211
)( (2)
10 kjb , 11
==
n
j
kjb , ( )njmk ,,2,1;,,2,1 "" ==
Where, kjb is the weight of the j index evaluated by the
k expert.Objectively, there is an optimal relative weight matrix
( )nwwwW ",, 21= and it can be obtained using conceptof generalized distance and the minimum variance.
( )= =
==
m
k
n
j
jkj wbWBD1 1
22
Seeking derivative of the variable jw , letting
02211
==
==
m
k
kj
m
k
j
j
bww
D
m
b
w
m
k
kj
j
==
1 ( )nj ,,2,1 "= (3)
( )
( )
2/1
1 1
2
1
2
=
= =
=
m
k
n
j
jkj
n
j
jkj
k
wb
wb
c (4)
Where, kc is the proportion of weight error evaluated by
the k expert to the total weight errors. According to the
principle that the smaller is the error, the larger is the entropy,the following transformation is carried out.
kk cd /1= (5)
Figure 1. Functional evaluation index system of gas source.
=
=m
k
k
kk
d
d
1
(6)
So the comprehensive weights matrix V of the indexescan be expressed as (7).
nj vvvvBV "" ,,,, 21== (7)
( )m ,,, 21 "=
Where, jv is the comprehensive weight of the j index.Five experts are invited to evaluate the indexes in Fig.1
using the improved AHP. The weights of the indexes arecalculated and shown in TABLE I and TABLE II.
According to functional evaluation index system of gas
source, the indexes are graded using 10-points system, and a
high score shows the degree satisfying the basic function is
higher. Assuming there are p schemes and q function
indexes, the cumulative scores of the indexes and function
coefficients can be calculated using (8) and (9) respectively.
ij
q
j
ji SvS =
=1
( )pi ,,2,1 "= (8)
TABLE I. INDEX WEIGHT OF BLAYER
Index B1 B2 B3
Weight 0.6056 0.1972 0.1972
TABLE II. INDEX WEIGHT OF CLAYER
B B1 B2 B3
Index C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12
Weight 0.2784 0.2666 0.2750 0.1122 0.0679 0.4437 0.1850 0.1629 0.5296 0.0739 0.2024 0.1942
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Annual cost, 104yuan 169 240 336 177
Cost coefficient 0.1835 0.2606 0.3637 0.1922
TABLE V. VALUE INDEXES OF GAS SOURCES
Item LPNG LNG CNG LPG
Function coefficient 0.2674 0.2508 0.2493 0.2324
Cost coefficient 0.1835 0.2606 0.3637 0.1922
Value index 1.4572 0.9624 0.6855 1.2092
IV. CONCLUSIONAccording to principle of value engineering, a model for
selection of city gas sources is constructed. The model mainly
focuses on the function analysis of city gas source and a
function evaluation indexes system for gas sources isestablished, an improved AHP are used to determine the
weights of the indexes. Value indexes of gas sources are used
as the evaluation parameter for selection of gas sources.Application case is analyzed using the model and the
selected gas source LPNG meets the city requirements. Valueengineering is feasible to select the city gas source and theevaluation result is reasonable and intuitive.
REFERENCES
[1] Duan Changgui, Gas Transmission and Distribution, Beijing: ChinaArchitecture & Building Press, 2002.
[2] Deng Yuan, Handbook of Gas Planning and Design, Beijing: ChinaArchitecture & Building Press, 1992.
[3] MILES L D., Techniques of Value analysis and Engineering. NewYork: McGraw-Hill,1972.
[4] Yang Hong and Wan Zhonglun, Determination of the function weightin value engineering, Journal of Xihua University (Natural Science),Vol.24, pp.77-79, March 2005.
[5] Jia-you LIU, Selection of gas pipeline system schemes based on valueengineering, Proceeding of the 2nd International Conference on ValueEngineering and Value Management (ICVE&M2009), PublishingHouse of Electronics Industry, pp. 227-232, October 2009.
[6] Ma Rongguo and LiuYanni, Weight value determination method ofhighway construction comprehensive evaluation, Journal of Trafficand Transportation Engineering, vol. 5, pp.110-112, June 2005.
[7] Liu Jiashun, Li Guoming, Technology Economy, Beijing: MechanicIndustry Press, 2004.
[8] Sun Jihong, Gas source selection for middle and small cities,Engineering Construction and Archives, vol.19, pp.417-419, May 2005.
[9] Yang Jianwei and Zhao Liang, Selection of city pipeline reserve gassource, Urban Gas, vol. 372, pp.25-26, February 2006.
[10] Xu Shu, Economic and technical analysis of gas source selection inXinglin region, Energy and Environment, pp.27-30, March 2004.
[11] FU Xiguo, Selection of gas sources in middle and small towns, GAS& HEAT, vol. 25, pp.7-48, July 2005.