the pollution index program - Minerals Processing Research Institute
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1. quantitative measurement of the pollution impact of a process The pollution index program is a pollution preventionand measurement module whichcan be used to assess the environmental impact of chemical and refinery processes It is based on the pollution index methodology of EPA Hilaly and Sikdar 1995 This approach defines pollution indices which can be used to compare the performance of different chemical processes Methodology There is a wealth of information on methods for pollution prevention for chemical and refinery processes Some methods currently being developed are the Waste Reduction Algorithm WAR by Hilaly and Sikdar 1995 the Environmental Impact Theory by Cabezas et al 1997 the Clean Process Advisory System CPAS by Baker et al 1995 and the Mass Exchange Network Methodology by Papalexandri et al 1994 The Pollution Index Program uses the Waste Reduction Algorithm WAR The WAR algorithm can be used to minimize waste in the design of new processes as well as in the modification of existing processes It is based on the generic pollution balance of a process flow diagram as given below Pollution Accumulation Pollution Inputs Pollution Generation Pollution Output 1 In the WAR algorithm a quantity called as the Pollution Index is defined to measure the waste generation in a process This index also allows comparison of pollution production of different processes The Environmental Impact Theory Cabeza2. results of these evaluations This form is shown in Figure 5 The column on the left hand side shows the indices based on the generation of potential environmental impact and the right hand side column shows the indices based on the emission of environmental impact Each index is accompanied by a Help button Clicking the Help displays more information about that particular index at the bottom of the screen The results for this problem are given in Table 3 Table 3 Results for the MEK process Index Type Based on Generation of Potential Environmental Impact Total rate of Impact Generation 35 00448 Impact hr Specific Impact Generation 0 061411 Impact kg product Rate of Generation of pollutants product kg pollutants kg products Based on Emission of Potential Environmental Impact Total rate of Impact Emission 36 3829 Impact hr Specific Impact Emission 0 063827 Impact kg product Rate of Emission of pollutants product 4 91228 kg pollutants kg products 23 Pollution Index Program Index Calculations Process 13 lel ES Indices based on Generation of Potential Environmental Impact Total rate of Impact Generation 35 00448 Impact Time Specific Impact Generation Hel 61411368421 0 Impact Product Rate of Generation of Pollutants per unit product 1 Mass Pollutants Mass of products Hel Help on the selected Index This index gives the rate atwhich the process generatespote
3. 20 and SBA and their corresponding flowrates Other components of the system which are not present in this stream need not be entered In accord with the Environmental Impact Theory the process streams are divided into three categories Input Product and Non Product Strl is an input stream So in the Stream Type list we will choose Input Having entered all the information for this stream we can now click the Add stream to list button The stream now gets added to the Stream List table at the top In this manner we can add all the five streams to our model The list at the nght hand top of the form shows the list of all the components in the process Whenever a new component is added to the model it is automatically added to this list Each of these components has Specific Environmental Impact Potentials Qs for each of the nine different categories of impacts The user has to click on the component name in the list and then enter the Qs values in the table All the impact potentials have a default value of zero So let us click on SBA in the Choose component list and enter the value of 0 00041 in the first impact type Also click on MEK and enter 0 42 Figure 2 Welcome Window dex Pivyraim Wiehan The Pollution Index Program Thiz pzta is 92587 or a ceneral theory fort e low end the gane stion 31 9cte ti l are ror meta Incacctioich ache sical pinnes loe 210 em ran mas sia poerialinpectineices ihe shacecteu
4. THE POLLUTION INDEX PROGRAM USER S MANUAL AND TUTORIAL Kedar Telang and Ralph W Pike March 1 2001 Copyright 2001 Mineral Processing Research Institute Louisiana State University Baton Rouge LA 70803 TABLE OF CONTENTS Disclaimer i 3c25 koonu radia pre oder beta De e BRS A pita ai 1 Stata cs rs dead it A A ti 1 Introduction A ee ae ee eds BiG eee peed Lge eee 1 Methodploty o ouch Bee othe es oleh Bre A elect Bm A alta Pere ony 1 The Environmental Impact Theory 2 2 sc4 2 odes ie id Dee ee daa es 1 Pollution Indices 22 304 RL A A A AD ee ARS EAS e Se ey 3 Tutorial SESSION E A A AA E A Eee ae ites ate 6 General Information lt 2640 tsi ho ba a a in tdt ada ad bs boba 14 O agp Ge 4a ede Ce ae Aho eAG wee ee hes 14 References ic eis ocd ele be bch oe eh Aline eek ee Ae bee She a ee ee 16 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 LIST OF FIGURES Process Flow Diagram for the MEK Process 0 0 00 c eee ee ee eee 7 Welcome Wind W dida phe daia e IA ss 9 Open Model Dialog BOX 2 2 cci era ep eae esa a Eee ews 10 Steam Data ea ell Bas a ell Bae od a 8a 11 Pollution Indices s isa codes a gene ane BRR ti oan ped 13 DISCLAIMER Mineral Processing Research Institute MPRI makes no warranties express or implied including without limitation the implied warranties of merchantability and fitness for particular purpose regarding the MPRI software MPRI does not warrant guarantee or
5. am a sum is taken over all the chemicals where M is the mass flow rate of the stream j and x is the mass fraction of chemical k in that stream Q is the characteristic potential impact of chemical k The process streams are divided into three types Input Product and Non product All non i i i product streams are considered as gen out in containing pollutants and all product streams are considered to have zero potential impact This assumption is made because the objective of the methodology is to reduce the impact and amount of waste materials released into the environment Since the product streams are not released into the environment they are considered to have zero potential impact 3 The potential environmental impact of a chemical species is calculated using the following expression Y E Y 4 where the sum is taken over the categories of environmental impact is the relative weighting factor for impact of type 1 independent of chemical k Q is the potential environmental impact of chemical k for impact of type 1 There are nine different categories of impact These can be subdivided into four physical potential impacts acidification greenhouse enhancement ozone depletion and photochemical oxidant formation three human toxicity effects air water and soil and two ecotoxicity effects aquatic and terrestrial The relative weighting factor allows the above expression for the impact to be
6. arators mixers etc and is thus ideally suited for the purpose of this illustration The process flow diagram for the above process is shown in Figure 1 SBA is fed to a hydrogen scrubber where the feed SBA scrubs residual MEK from the hydrogen stream The SBA feed is then pumped up to the reaction pressure and heated to the reaction temperature This feed then enters the reactor The output of the reactor is then sent to a heat exchanger where it is partially condensed The mixture of MEK SBA and hydrogen is cooled further and sent to a separator where the hydrogen is flashed off The hydrogen is then scrubbed and the liquid phase is then sent to the MEK purification system where it is separated into product MEK and waste SBA The mass flow rates kg hr of the input and output streams are given in Table 1 and the potential environmental impact scores for these chemicals are given in Table 2 from Cabezas et al 1997 Table 1 Mass Flowrates of Input and Output Streams for the MEK Process 3362 2670 pa o A Ea 1 EJ mo s Ow y Table 2 Potential Environmental Impact Scores for Chemicals in the MEK Process 0 00041 Q impact kg By prod H2 Feed SBA Cooler Reactor H20 MEK Product MEK Crude MEK Waste SBA Figure 1 Process Flow Diagram for the MEK Process Cabezas et al 1997 8 Now that we have all the necessary data let us use the Pollution Index Program for this proble
7. ctors R W F Impart Tyne R Acidifcation 1 zl Eculixivily Effeutl Aqualic 1 Ecoxizity Effect T errestrial 1 Total Mass Flowrate Greenhouse Emancemerk 1 Humen Toxicity Effect Sir 1 i Calculate Indices Figure 4 Stream Data 12 Also the user has to enter the Relative Weighting Factors for the process In accordance with the theory all the s are initialized to one For this problem we will retain these default values To modify the information for any stream the user simply has to click on that stream in the list and the data for that stream appears in the boxes The user can make the required changes and click the Update Stream Information button Similarly to delete a stream the user has to select the stream first and press the Delete Stream button All of this model information is written to a temporary buffer At any time the user can save the model by choosing the Save option in the menu Let us save our model in a file called example mdb The model is stored as a Microsoft Access database file So it must have the mdb extension Now that we have entered and saved the model the Calculate Indices button can be clicked to view the values of the six pollution indices defined earlier On clicking this button the program uses the data entered by the user to evaluate these indices using equations 5 9 It then displays on the screen the Pollution Indices form which shows the
8. customized to specific or local conditions The suggested procedure is to initially set all the to one and then allow the user to vary them according to local needs To quantitatively describe the pollution impact ofa process the conservation equation is used to define two categories of Impact Indices The first category is based on generation of potential impact within the process These are useful in addressing the questions related to the internal environmental efficiency of the process plant i e the ability of the process to produce desired products while creating a minimum of environmental impact The second category measures the potential impact emitted by the process This is a measure of the external environmental efficiency of the process i e the ability to produce the desired products while inflicting on the environment a minimum of impact Within each of these categories three types of indices are defined In the first category generation the three indices are as follows l I os measures the total rate at which the process generates potential environmental impact due tononproducts This can be calculated by subtracting the input rate of impact from the output rate ofimpact as shown in the following equation 5 I ae and 2 can be calculated using equation 3 4 2 ANP I pa 1 Le x sadislires the potential impact created by all gen TO oP p L P L P nonproducts in manufacturing a unit mass of all the product
9. f streams 4 and 5 Clicking the Back button will bring us back to the Indices form Table 4 Pollution Index Values for Streams in the MEK Process EE ee eee To make modifications in our model we canclick the Back to Stream Data button which will again display the Stream Data window We can now add and delete streams change data for existing streams change the Impact Potentials for the components etc and again click the Calculate Indices button to see the results for the modified model In order to save the changes to the model the Save option on the menu must be used Thus we can make changes in the model and see the effect on the pollution indices by going back and forth in these windows The Exit button in the menu will quit the application General Information The pollution index program is written using Visual Basic 5 0 It uses Microsoft Access 97 as the database 15 Acknowledgments The support of Gulf Coast Hazardous Substance Research Center is gratefully acknowledged Pollution Index Program Waste Reduction Algorithm The Pol utioa Index of a streem is a measure of ts potential environmental 0 00779 U 6 5547 29 32041 Note All product streems 1awe a pollution index ot zero 16 The Waste Reduction Algorithm Idervify the streams with high polli tinn index Iderify the process units from which these streams orig nate Carry our sensitivity ana
10. lysis Le determine the variables which siqnricantly effec the performance charactoristics of that process urit Man pulate these variables tc mirimize the pollution index values Tris is a nonlinear optimizacion aroklem Apply ary heurisiic rules fnecessaryto salve he wasle roinirmicalion problerr Ea Figure 6 WAR Algorithm 17 References Hilaly A K Sikdar S K 1994 Pollution Balance New Methodology for Minimizing Waste Production in Manufacturing Processes J Air and Waste Manage Assoc 44 1303 Cabezas H Bare J C Mallick S K 1997 Pollution Prevention with Chemical Process Simulators the Generalized Waste Reduction WAR Algorithm Computers chem Engg Vol 21 pp S305 310 Baker James R R J Hossli M M Zanoni and P P Radeciki 1995 A Demonstration Version of the Clean Process Advisory System Paper No 8a AIChE Summer National Meeting Boston Massachusetts
11. m On running the program the Welcome Window as shown in Figure 2 appears on the screen It gives a short description of the program s function and the Potential Environmental Impact theory It asks the user to choose either a new model or an existing model We will choose the New Model option For an existing model the program shows the Open Model dialog box shown in Figure 3 Next the program shows the Stream Data form whichis given in Figure 4 Since we have chosen a New model all the data fields will be initially empty The table at the top left corner shows the list of streams in the model New streams can be added by first entering the necessary stream data and then clicking the Add Stream to list button The necessary stream data includes the stream name the component data and the stream type The component data includes the component name and its flowrate The component flowrates can also be specified in terms of the mass fractions along with the total mass flowrate of the stream Since we have the data in terms of mass flowrates we do not need to specify the total flowrate of any stream So let us enter the data for the stream number 1 In the box for the streamname let us enter strl We will name all of our streams for this problem as str1 sr2 and so on We will click the Mass flowrates of components option in the Specify box In the Components Data table we will enter the two components H
12. make any representation regarding the use or the results of the use of the MPRI software in terms of its correctness accuracy reliability currentness or otherwise The entire risk as to the results and performance of the MPRI software is assumed by you In no event will MPRI its director officers employees or agents be liable to you for any consequential incidental or indirect damages including damage for loss of business profits business interruption loss of business information and the like arising out of the use or inability to use the MPRI software even if MPRI has been advised of the possibility of such damages INSTALLATION The PollutionIndex Program must be installed under Windows 95 or Windows NT The procedure to install the program is described as following 1 Insert CD ROM in CD ROM Drive and run the pollinstall exe program 2 The default destination directory is C Program Filesipollution into which the program will be copied when the setup program is run 3 The short cut will be created Under start Programs Advanced Process Analysis 4 Run the program pollution exe in the installation directory Introduction Cost minimization has traditionally been the objective of chemical process design However growing environmental awareness now demands process technologies that minimize or prevent production of wastes The development of such environmentally benign processes requires a tool whichcan perform a
13. nal environmental efficiency of the process plant Smaller the values of these indices more environmentally efficient is the process The second category of indices indices 4 5 and 6 categorizes emission of potential impact within a process These are useful in questions related to external environmental efficiency of the process Indices 1 and 4 can be used for comparison of different designs on an absolute basis whereas the other indices can be used to compare designs independent of the plant size In addition to these indices for the process pollution indices can be defined for the individual streams also Higher the pollution index of a stream higher is the pollution impact of that stream on the environment Since all product streams are considered to have zero potential impact their pollution index values are zero The pollution index value for a stream j can be calculated using the following equation J 1 M xe 10 k where M is the mass flow rate of the stream j x is the mass fraction of chemical k in that stream and Q is the characteristic potential impact of chemical k Tutorial Session To illustrate the use of WAR Algorithm and the working of the Pollution Index Program a small tutorial problem Cabezas et al 1997 is given below The process is of production of methyl ethyl ketone MEK from secondary butyl alcohol SBA This is a typical chemical engineering process with several unit processes such as reactors sep
14. ntial environmental impact Itis equal to the differencebetween the total potential impact leaving the system and thethe total potential impact entering the system The potentialimpact of products is taken to be zero Pr qe a tHE gen out in Indices based on Emission of Potential Environmental Impact Total rate of Impact Emission ee Impact Time Heb Specific Impact Emission 0 063823964912 Impact Product Rate of Emission of Help Pollutants per unit product ast 228070175 Mass Pollutants Mass of products Help Show WAR algorithm Back to Stream Data Figure 5 Pollution Indices 14 Let us click the Show the WAR algorithm button which will display the WAR Algorithm window shown in Figure 6 In this figure the table on the left side shows the pollution index values for the individual streams These values are obtained by applying equation 10 to all the process streams A comparison of these values can help in identifying streams with high pollutant content The pollution index values for the individual streams in the MEK process are given in Table 4 We can see that stream 5 has a very high pollutant content followed by stream 4 Stream 3 has no pollutants because it is a product stream The form also shows the important steps of WAR Algorithm which gives a systematic way of approaching the waste minimization problem Process modifications should be made to reduce the pollutant contents o
15. rr th2 ge craior o pocemia inpaztwitkin a aroczss anc hc output of potential ir paci rom a process The polzntalerniraarmant al nsed is a cor oelual quer lioz halcan no be meas red dirady Lul ean se colcu otac Fem strearr mese f owroces stean compos tzn nd o zlati pocencia impact sczre or es cle ivel pres ar The chainical impact scones incide e comureh stes salur ins eflecis encina Per veras desleal un lu himnar tarry lheseincdires cen be sent anit ace ute the pol utan ted uccine studies with ha yes te press tlowsh2cts To enter a new model i Mew Madcl To edit an existing madal Existing Model Open model E Potion index H ES i current mdb i e train mdb Access Files mdb H m Figure 3 Open Model Dialog Box 10 11 2 Pollution Index Program Process RE ES Precess Stream List Specific Environmental Impact Potential 5 E P Total Mass Flowrate kg hr Type H2 3370 nput E Choose Component H20 str2 37 Yon Product MEK stra S U roduct str4 2683 Non Product xi For Component SBA Update Stream Dele e Stream Information Acidificaton 0 00041 Ecctoxicty Effect Aquatiz 0 Stream Name stl Ferxicity F ffect T eirestrial n _ Greznhouse Enharcement 0 Specify g Mass Fowraes g Mass Fractions Hur tart Tuxivily Effewt ai 0 of Components for Components Hunan Toxicily Effect S oil 0 wi Componenis Data f Component Nama Mass Flowrate kg hr Relative Weighting Fa
16. s It is calculated by dividing index 1 by the rate at which the process outputs products This is shown in the following equation 6 where y is the total rate of output of products P p 3 M Hi measures the mass efficiency of the process i e the ratio of mass converted to an undesirable form to mass converted to a desirable form It is calculated from index 2 by assigning a value of 1 to the potential impacts of all non products This is shown in the following equation A p MY ie MP Eo k l j k gen y P i 7 The indices in the second category emission are as follows 4 N measures the total rate at which the process outputs potential environmental impacts due to non products It is calculated using equation 3 5 I measures the potential impact emitted in manufacturing a unit mass of all the produtts i s calculated by dividing index 4 by the rate at which the process outputs products This is showth e following equation gue 8 5 6 M x measures the amount of pollutant mass emitted in manufacturing a unit mass ofproduct It is calculated from index 5 by assigning a value of 1 to the potential impacts of all non products This is shown in the following equation A 2 My x NP out P 2 9 The first category of indices indices 1 2 and 3 categorizes generation of potential environmental impact within a process These indices are most useful in addressing questions related to the inter
17. s et al 1997 This theory is a generalization of the WAR algorithm which discusses the methodology for evaluating potential environmental impacts and illustrating its use in the design and modification of chemical processes The environmental impacts of a chemical process are generally caused by the energy and material that the process takes from and emits to the environment The potential environmental impact is 2 a conceptual quantity that can not be measured However it can be calculated from related measurable quantities The generic pollution balance equation of the WAR algorithm Eqn 1 is now applied to the conservation of potential environmental impact in a process The flow of impact in and out of the process 1s related to mass and energy flows but is not equivalent to them The conservation equation can be written as dlsys dt i Dai Toer 2 In the conservation equation I is the potential environmental impact content inside the process 1 is the input rate of impact Iou is the output rate of impact and Ien is the rate of impact generation inside the process by chemical reactions or other means Applicationofthis equation to chemical processes requires anexpression that relates the conceptual impact quantity to measurable quantities This can be written as b Ie Sy MAN j j k where I is the total impact flow in the input or the output The sum over j is taken over all the process streams For each stre
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