Dust Explosion Is One Of The Major Hazards Engineering Essay

Dust Explosion Is One Of The Major Hazards Engineering Essay Dust explosion must be controlled but means of necessary vent area design, Vessel strength, also following proper operational procedures and maintaining good housekeeping. Here a new bag filling plant and silo for plastic manufacturer is designed. So, as a safety advisor the vent sizing for a silo is presented to vent a dust explosion. Information required for the calculation of the vent sizing are strength of the vessel i.e. silo, explosion properties of the dust, size and shape of the vessel, the static activation pressure that is to open the venting in case of any pressure rise, condition of the dust cloud. If the dust is found to be toxic then venting should not be done if theres immediate harm to the environment. But in some unavoidable circumstances then the venting is done with an endangered area shall be specified. For that safe discharge area must be calculated to vent the dust to the atmosphere. And location of venting is chosen on the top of the silo i.e. vertical venting. This assumption made on the condition that the silo is sited in a congested area. Horizontal venting will cause harm the personnel working in the plant area. Plant Sketch Silo Air to bag filter Pneumatic Conveyor Cyclone Powder Inlet from plant Air Blower Vibrating outlets to bag filling stations Data given, Silo is of cylindrical shape. Diameter = 10m Height = 30m Vent duct length = 15 m Silo Design pressure = 0.25 barg Material stored in silo is plastic power and also includes Methylene dianiline (MDA). Here the dust is tested in and 20 litre sphere apparatus to find the maximum rate of pressure rise per unit time. The main apparatus is Sphere explosion vessel, dust dispersion system, ignition source, Pressure monitoring system and control system. This test done as per BS EN 14034-2:2006. And it is found that (dp/dt) max = 928 bar.s-1 Where (dp/dt) max Maximum rate of pressure (p) rise per unit time (t) The objectives of this design are i. To vent the deflagrating that occurs inside the vessel ii. To avoid the injury to personnel by vent discharge iii. To limit the damage of the vessel iv. To limit the damage of the nearby structures The following steps are identified for venting sizing with reference to i. Dust deflagration index Kst must be found, Kst = (dp/dt)max * V 1/3 Where (dp/dt) max Maximum rate of pressure (p) rise per unit time (t) =928 bar/s And volume of the test apparatus is 0.02m3 Kst = 928 * (0.02)1/3 bar.m.s-1 Kst = 252 bar.m.s-1 ii. Now maximum explosion overpressure occurs during dust explosion in an enclosed vessel (non-vented vessel) Pmax which is to determine the explosive characteristics of the dust. Procedure for measuring Pmax is done in 5litre apparatus and the apparatus is designed to withstand an internal overpressure of 20 bar. First required amount of dust is taken for the test. Then the dust is dispersed in the vessel at atmospheric pressure and before that the initial temperature is noted down. Then initial pressure Pi i.e. just a moment before ignition is noted. And the pressure rise recorded as a function of time. And from pressure time curve Pex is determined for the particular dust concentration. And the test is done for various dust concentration and the Pex results are plotted with various dust concentration until the maximum value of Pex is found. And that maximum value is the maximum overpressure Pmax. This Pmax and Kst plays crucial factor in determining the vent size and design for explosion protection. Here dust mixture composition is not known, so the vent size is based on highest Kst and Pmax value. The result of Pmax for various dust classes is referred from BS EN 14034-2:2006, the table is shown below Kst (bar.m.s-1) Dust explosion class Pmax (bar) 0 St 1 à ¢Ã¢â‚¬ °Ã‚ ¤ 9 200 St 2 à ¢Ã¢â‚¬ °Ã‚ ¤ 10 Kst > 300 St 3 à ¢Ã¢â‚¬ °Ã‚ ¤ 12 Table 1a: Where, St 1- moderate explosible St 2 strong explosible St 3 very strongly explosible Hence from the table above Pmax is taken as 10 bar for Kst = 252 bar.m.s-1 and the dust is classified as St 2. iii. Now the vessel design pressure selection must be measured, if the enclosure vessel is designed as ASTM then Pmawp (Maximum allowable work pressure) can be calculated. Here it is given that design pressure is 0.25barg. Venting provided should be sufficient to reduce the enclosure vessel rapture due to reduced maximum overpressure, Pred,max Here Pred,max shall be chose shall not exceed two-third of the vessel strength. Venting shall be provided such that Pred,max shall not exceed the vessel strength to prevent the rapture of vessel during venting. Pred,max à ¢Ã¢â‚¬ °Ã‚ ¤ (Pes/ DLF) Where, DLF dynamic Load factor as a result of pressure rise. In absence of detailed structural analysis, it is assumed that DLF = 1.5 the design based on weakest structural element. i.e. Pred,max à ¢Ã¢â‚¬ °Ã‚ ¤ (2/3)(Pes) Where Pes enclosure strength in bar Hence, Pred,max = 0.166 bar iv. Vessel Height to diameter ratio, the ratio of height to diameter of the vessel must be included in determining the vent area. Increase in ratio of height to diameter increases the flame propagation inside the vessel. Hence the estimation of the ratio is given below, Veff = à Ã¢â€š ¬ r2 h Where Veff is the volume of the cylindrical vessel were flame can travel along the path. h Height of the cylinder r radius of the cylinder Veff = 3.14 * 5* 5* 30 = 2355m3 Aeff = Veff / H Where Aeff is the effective area of the cylindrical vessel Aeff = 2355 / 30 =78.5 m2 Deff = ((4*Aeff)/à Ã¢â€š ¬)1/2 Where Deff is the effective diameter of the cylindrical vessel Deff=((4*78.5)/3.14)1/2 = 10m H/D = 30/10 = 3m v. Venting cover operation, the following factors to considered for the venting cover operation such as venting opening shall be free and clear, should be obstructed by weather conditions and any dust deposits. The vent cover shall open at its static activation over pressure Pstat. And vent cover should withstand the pressure within the static activation overpressure Pstat.. Here venting cover with specific mass And Hence Pstat = 0.2 bar. Sizing of vent area, here the specific situation must be considered for the venting sizing. Here the material is transferred by pneumatic conveyor. And this is classified as Inhomogeneous dust distribution as per New findings on explosion venting by R.Siwek. For vessel length L> 10m A = 0.0011 * Kst* H *Df * [(1/Dz) (8.6 log Pred,max 6) 5.5* log Pred,max + 3.7] ( 1 +1.715 * Pred,max -1.27 * log (H/D)) Where, Df diameter of the pipeline, here its assumed as 0.1m for effective dust reduction A Vent area m2 Dz effective diameter of the cylindrical vessel Dz =( (4*v)/à Ã¢â€š ¬ ) 1/3 = (( 4*2355)/3.14)1/3 = 14 A = 0.0011 * 252 * 30 * 0.1 * [(1/14) (8.6 log 0.166 6 ) 5.5 log 0.166 + 3.7] (1 + 1.715 * 0.3 -1.27 * log 3) A = 30 m2 Effect of vent ducting, duct is normally to vent the discharge to a safe area away from the work area. But increase in duct length will increase reduced maximum explosion pressure. P red,max = -0.03267 * l*(H/D) + 0.3481 * l0.798 Where, l length of the duct (m) P red,max maximum reduced explosion pressure with vent duct P red,max = -0.03267 * 15 * (30/10) + 0.3481 * 150.798 P red,max = 1.5 bar P red,max = 0.2 *(C1 C2) * (1-(H/D)) + C1 Where C1 = P red,max * (1 + 17.3 *(A*V-0.753)1.6 * l) = 1.027 C2 = (0.0586 * l) + 1.023] * P red,max0.981 (0.01907 *l) = 0.5 P red,max = 0.8 bar And from the above equation relationship between the reduced maximum explosion pressure with vent duct and duct length can be found and also necessary increase in cylindrical vessel strength can also be estimated. Since the facility is still being designed and from the above result of with effect of vent duct it is evident that reduced maximum explosion pressure increases above the vessel design pressure. So the increase in design pressure and the vessel strength must be re-considered if vent duct is used to deflagrate the flame. Safe discharge, Maximum flame length for dust, X = Q*V1/3 Where Q 8 for vertical discharge X = 8 * (2355)1/3 X = 106.4 m Maximum flame width, W = 1.3 * (10*v)1/3 = 37m Maximum external pressure (dust) P = 0.2 * Pred,max * A0.1 * V0.18 = 0.188 bar Where P maximum external pressure A Vent area V Volume of the cylindrical vessel. 2. This bag filling facility handles plastics powder which generates dust must be examined for the explosive characteristics. For that we need to analyse the chemical compositions in it. The explosive dust decomposes generating large enormous energy. This decomposition includes oxygen in the molecule so it is not necessary that it needs air. So it is important to screen the chemical composition first, if the test indicates the presence of explosive characteristics then necessary dust explosion prevention and protection techniques must be implemented as a basis of safety. In order to prevent the dust explosion following techniques are used i. Controlling the source of ignition ii. Inerting For explosion protecting the following techniques are used i. Explosion containment ii. Explosion suppression iii. Venting DUST EXPLSION PROTECTION PREVENTION Control of ignition containment Source Suppression Inerting Venting Now the details of each technique are explained in detail below Controlling the source of ignition, dust explosion cannot occur unless theres a source of ignition. And hence a careful analysis must be done in design, operation and maintenance for the possible sources of ignition. Here are some of possible sources of ignition a. hot surface b. spark c. electrostatic spark d. heat e. friction f. flames Flames are one of the sources which can easily ignite the dust. Direct heating i.e. using of burners can be avoided in process where dust generation is possible. Welding works carried on the silo which has possible dust generation inside the vessel. So all hot works carried on silo must be allowed as per the statutory requirements. Any Internal combustion engines near the silo might take in the dust generated nearby and can cause explosion. And hence this combustion engine can be avoided or use of flameproof combustion engines. Electric power is also one of the sources of ignition. Electric spark which are produced from electrical equipment, if comes in contact with dust will result in explosion. Hence all the electrical equipment must be intrinsically safe and also ATEX 137 EU directive 95/9/EC certified equipment should be used depending upon the dust and zone classification. So this must be done during procurement stage. Once ATEX is implemented then zone classification must be done as a part of ATEX requirement by analysing the possible generation dust from the process i.e. Zone 20 dust generation is often, zone 21 dust generation likely to occur or Zone 22 dust generation not likely to occur. Dust depositing on hot surface will cause explosion depending on the temperature and geometry of the surface. In most of the cases this can be avoided by good housekeeping. And also Ignition occurs only when the surface temperature reaches the minimum ignition temperature of the dust. Static electricity is also one of the major hazards in process and chemical industries. When a charged particle comes in contact with the opposite or dissimilar object there will be transfer of charge and will results in spark. Since the powder have charged particle, when it comes in contact with dissimilar particle in transferring or free falling there will be transfer of charge which will generate spark. And the spark generated can cause ignition of the dust. Hence all the metal containers must be earthed so that the charge generated will leak away to the earth. And use non conducting materials are recommended in construction. Below diagram show difference between earthed and non-earthed conductor Figure 2a: Hazards in non-earthed conductor Friction is also one of the ways that dust cloud can be ignited. That is when hot particles come in contact with mechanical equipment by rubbing or impacting against the equipment can ignite the dust cloud. This friction ignition depends upon the maximum velocity of the hot particle impacting against the hot surface. And hence use of such mechanical equipment should be avoided. And the other possible chances of ignition of dust clouds can be through spontaneous combustion. So this type of burning occurs due to self-heating as a result of internal exothermic reaction which is followed by thermal runaway. If this heat release is unable escape will result in ignition. And also sufficient oxygen and dust concentration must be present for the thermal runaway ignition. Hence the safe way is to displace the oxygen is by inerting. Inerting is a process by sending inert substances to remove or prevent the explosive atmosphere formation. The main objective is to eliminate or to reduce the oxygen level below the lower flammability limit in order to avoid the catastrophic dust explosion, in some case combustion can also occur in very low oxygen level so in that case is safe to replace all the air with inert gases. Even sometimes explosive dust generated inside the vessel can be diluted into non explosive dust by passing certain inert dust e.g. limestone. When inerting theres chance of inert gases gets trapped inside the vessel, where personnels are accessible for confined space works, this will result in asphyxiation. Hence proper statutory rules must be followed in entry of confined space. Care should be taken when inert gases are sent into the distribution line. That is before passing the inert gases the impurities such as hazardous substance moisture etc. should be removed from the inert gases by means of filter. And flow of the inert gases must be maintained by the pressure monitoring and controlled. Flow chart for inerting process is shown below Inerting Use of inert dust as an inert medium Suitable inert gas available e.g.) N2, co2 etc Performing oxygen limiting measurement at process temperature and pressure Design dust inert system Ensure the reliability of the monitoring system Inert gas cost when compared to other safety technique, are the cost found satisfactory Consider basis of safety for design and operation And some the other available prevention techniques include installation of pressure sensor, alarm system in-case of overpressure, Automatic shutdown system in-cases of overpressure, Level indicator, correct operational procedures and Proper maintenance and inspection procedures. Explosion containment is used to withstand the explosion pressure rise and to prevent the rupture of the containment. The explosion containment usage is accepted when the release of the process materials is not acceptable. First maximum explosion pressure Pmax must be determined, since it is the crucial factor in explosion containment. Hence pressure resistant vessels are designed to withstand the maximum explosion pressure without any deformation or rupturing the vessel. And hence the stress induced by the maximum explosion overpressure should not exceed 50% of the yield strength of the weakest part. Explosion pressure shock resistant vessel is also designed to handle the maximum explosion pressure but deformation occurs to some extent. And the stress induced by the maximum explosion overpressure should not exceed 90% of the yield strength of the weakest part. Logical flow chart for explosion containment is shown below Explosion Containment Multi-volume Single volume Can explosion be contained by knowing Pmax and plant design? Are the multiple volume is mechanically isolated Is Rapture of vessel acceptable? Use pressure shock resistant vessel Use pressure resistant vessel Consider basis of safety for design and operation Cost valid when compared to other safety techniques Suppression is a technique which identifies the starting point of explosion and extinguishes the growing fire. Normally suppressor is used whenever it is difficult to discharge the pressure and flame in a safe area. Normally it takes 40 90ms for an explosion to occur when the dust gets ignited. So now the explosion detector detects the pressure rise in the vessel and it is designed to set the alarm when it reaches the reference pressure rise and activates the suppressor so that it suppresses/extinguishes the growing fire ball inside the vessel. Suppressor can also be used in parallel with venting where sufficient venting area is not achieved. And also it is to noted that explosion detector should withstand to the vibration, shock and resistant against corrosion. Below figure shown is the normal working of suppressor in the vessel. Normally suppression can be used for a vessel volume up-to 1000m3. For vessel larger than 1000m3 explosion suppression can be used and the explosion suppressor must be within the vessel volume boundary. Fig 2b: Suppressor working If a vessel is without suppressor and dust explosion occurs in a enclosed vessel then the pressure rise grow and attains destructible level which is shown below in graph (line A). If a suppressor is installed and suppressor extinguished before the explosion then the maximum pressure rise will be reduced Pred within the maximum vessel design pressure, shown below in graph (line B). In order to achieve the above it also depends upon the suppressor location, suppressor discharge rate and also number of suppressor placed in the vessel. Graph 2a: Pressure rise with suppressor and without suppressor There are many types of suppressors available such as hemispherical suppressor, High rate discharge suppressor are used. Normally high rate discharge are most widely used because for their high discharge rate to suppress the fire. In hemispherical suppressor usually liquids i.e. water is used as suppressant and can store upto 5 litres. And the initial velocity of hemispherical suppressor is 200m.s-1 and the discharge time is 10 30 ms. For high rate discharge suppressor the suppressant used can be liquid or dry powder. It can suppressant discharge time is within 10 millisecond and suppressant stored upto 40kg. And the suppressant materials used in order to supress the fire must quench the combustion. And some of the commonly used suppressants are dry powder i.e. dry chemical and water. Flameless venting is done to vent the explosions without any risk of external flame. Flameless venting device consists of flame arrestor which quenches the flame that propagates outside from the vessel. The main principle is that the arrestor reduces the fuel from flame below the ignition temperature by energy dissipation in the flame arrestor. 3. Here in this bag filling facility, use of hazardous substance involved. Hence this operation must abide to control of substance hazardous to health Regulation 2002 (As Amended) (COSHH) to control the hazards to the human health. Here in this bag filling facility there is use of plastic powder which get filled and packed. In this plastic power has an additive known as Methylene dianiline. This plastic powder is a thermoplastic intended for use in injection of moulding machine. This methylene dianiline is a carcinogen which causes cancer when it is inhaled by the people engaged in bag filling operation. So it is necessary to conduct control of substance hazardous to health risk assessment. And to evaluate the allowable exposure limits and the necessary measure to be taken while handing the hazardous materials. Main steps to be followed to prevent the health hazards and to comply with COSHH are as follows i. Determine the risk ii. Control measure implementation iii. Control the exposure iv. Continual improvement and practice of the control measure implemented v. Monitoring the exposure level with the control measures vi. Providing health monitoring check up vii. Prepare Emergency plan and conduct emergency mock drill viii. Providing training and necessary information to the employees Substances or chemicals that are hazardous to personnel health will come under COSHH. Here methylene dianiline is used which is identified as a potential carcinogen and hence the operation should comply with COSHH to control the health hazards and improve the operation. Determine the hazard The first step is to identify the hazard whether the substance used in the process causes health hazard to employee engaged in work. Here it is identified that Methylene Dianiline is a potential carcinogen. So operators engaged for bag filling, sealing and engaged in cleaning activities are at risk if exposed. So first we need to find the possible exposure points. From analysing the operation involved in bag filling facility. The possible release/exposure points are identified below, i. filling arms in bag filling station building it vibrates to prevent clogging ii. Opening the valve fast will cause sudden release of pressure. iii. Bag sealing possible dust generation since the bag is left opened iv. Cleaning the spilled dust near filling area v. Pneumatic conveyor possible leak point will cause dust discharge Here it is identified that possibility of the substance route to affect operator health is through inhalation when released in air. And hazards of methylene dianiline and its chemical properties are taken from CHIP classification, Now CHIP regulation gradually replaced by European CLP. And the hazard classification is taken from European regulation EC No 1271/2008 on Classification labelling and Packing (CLP) from Table 3.2 part3 of Annexure I to directive 67/548/EEC Index No International Chemical Identification Ec No CAS no Classification Labelling Concentration Limit 612-051-00-1 4,4Methylenedianiline 202-974-4 101-77-9 Crac Cat 2;R 45 Mutta.Cat,3; R 68 T; R39/23/24/25 Xn; R48/20/21/22 R43 N; R51-53 T;N R:45-39/23/24/25-43-48/20/21/22-68-51/53 S:53-45-61 Table 3a Classification is taken from European regulation EC No 1271/2008 on Classification labelling and Packing (CLP) from Table 3.1 part3 of Annexure VI to directive 67/548/EEC Index No International Chemical Identification EC No CAS no Classification Labelling Hazardous Class and Category codes Hazardous Statement Codes Pictogram signal word code Hazardous Statement Codes Suppl. Hazardous Statement Codes 612-051-00-1 4,4Methylenedianiline 202-974-4 101-77-9 Carc 1B Muta 2 STOT SE 1 STOT RE 2 Skin sens 1 Aquatic Chronic 2 H350 H341 H370 ** H373 ** H317 H411 GHS08 GHS07 GHS09 Dgr H350 H341 H370 ** H373 ** H317 H411 Table 3b: Where R Risk phase and H Hazard , Classification of levels of danger i.e. harmful, toxic, very toxic as per CHIP regulation. Here MDA is classified as potential carcinogen R 45 Cancer causing substance. Deciding proper safe guarding measure Since here the plant is in designing stage so the possible release/exposure points, population exposed to the hazardous substance and route of entry are identified and necessary control measure are indentified below to implement from the designing stage. So COSHH essential uses out of the risk assessment information it chooses one of the methods for control measure shown below, Figure 3a: The factors used in identifying appropriate controls measure are in below figure, Figure 3b: So the following steps are followed in identifying adequate control measure as mentioned in COSHH essentials: Easy steps to control chemicals i. Group the hazards identified ii. Grouping the physical properties of the amount used iii. Asses the anticipated exposure iv. Now combine step 1 to 3 to form a generic assessment Grouping the hazard, hazards are classified between A to E by R-Phase given in CHIP and H-Phase given in CLP. Below the table shows the classification of hazard group. In the below table units, mg/m3 milligrams per cubic meter and ppm parts per million. From below table methylene dialine classified under group E dust. Table 3c: Now to determine the predictive exposure we must first classify the hazardous substance physical properties. Here in bag filling operation, hazardous substance is in dust form, since the plastic powders are granule will generate dust. So as per COSHH essential they have presented a table for identifying the determinants of the hazardous substance. That is the factor for deciding the physical properties for solid are dustiness and for the liquid is the volatility. And based upon the below shown table here methylene dianiline is identified as fine solid and light power and the corresponding determinant is identified as high. Table 3d: And after identifying the determinant and amount used as per COSHH essential has identified four band of exposure potential and the table is shown below, Table 3e: Here in bag filling and packing operation the main product is plastic powder which contains methylene dianiline as an additive. So the quantities used which assumed to be in tonnes, the main aim of this plant is packing plastic powder. And the exposure predictor band here it is identified as EP 4. sNow to decide which the control approach is adequate enough to control the situation of health hazard has to be identified from the range given which is used in COSHH essential. And table is shown below Table 3f: And based upon the above control approval table and exposure predictor table COSHH essential formed a table relating exposure predictor to control approach. And the table is shown below. Table 3g: In-order to choose the type of control measure recommended we have to relate the target airborne exposure to the exposure predictor band .Hence for this bag filling facility type-4 control is recommended because the concentration level of the dust is unknown. Sample COSHH Risk assessment Step 1 Step 2 Step 3 Step 4 What are the hazard What will harm and who? What are you doing Improvements needed Who When Check Breathing in dust from filling station Since the dust contains MDA might cause cancer and irritates the respiratory system Dust mask Get cab and filtered air supply Conveyor to silo, to filling station Nobody Dust Extraction Check for leaks weekly Bagging plastic powder Charge handed Storage and dispatch Forklift driver Dust mask Get cab and filtered air supply Cleaning the plastic powder dust spill Charge hand Brushing Vacuum hose to dust extraction Changing dust filter Charge hand Use of P3 respirator Contract out this work Also: Action Taken Action needed Examination Test COSHH Supervision Instruction and training Emergency Plan Health Surveillance Monitoring Review Date Recommendations Here to reduce the possible exposures to hazardous substance below are the following recommendations, i. Minimizing the generation of plastic dust such as designing conveying system in such a way to reduce the impact with hard surface to reduce the dust generation i.e. use of long sweep elbows. ii. Minimising the release of plastic dust such as keep silo in good conditions i.e. avoid crack, proper maintenance etc., maintain the transfer equipment in good seal condition to avoid leaks. iii. Plastic dust can be captured and contained. iv. Create awareness among the employee about the hazards associated in handling hazardous substance and use of MSDS. v. Regular health surveillance must be conducted to employee exposed to risk. vi. Use of proper respiratory PPEs while handling with plastic powder. As per COSHH essential it is identified suitable PPEs for the selected group hazard. Table is shown below and it is identified as Assigned protection factor 200. This APF is in reference with BS 4275 Table 3h 4. Project Description The new bag filling line and silo is being constructed for a plastic manufacturer which is located in congested area which means the silo is located in between the nearby structures and objects but the whole plant is located in plain and partly terrain area. This facility involves transfer of plastic powder from the plant to silo for storage so that it can used to store plastic powder prior to the bagging and distribution. Here in the silo there is possible release of dust into the atmosphere due to overpressure or overfilling. Since the dust generated inside the silo is vented to atmosphere so it must meet to the current environment legislation in order to avoid air pollution. From Silo the plastic powder is sent to bag filling station. The bag filling station comprises a building in which there are four bag filling stations. Hence an environmental impact aspect must be undertaken before the commencement stage . Plant Sketch Silo Air to bag f

Curricular Aims: Assessment of University Capstone :: Education School Essays

Curricular Aims: Assessment of University Capstone Albert North Whitehead (1929) believed that the raison d’etre of universities was neither for the imparting of knowledge nor for the opportunity for research. Cheaper alternatives for both were and are available to achieve those functions. Instead, he asserted. The justification for a university is that it preserves the connections between knowledge and the zest of life, by uniting the young and the old in the imaginative consideration of learning. The university imparts information, but it imparts it imaginatively. At least, this is the function which it should perform for society. A university which fails in this respect has no reason for existence (p. 93). When Whitehead described the purpose of education in his text, The Aims of Education, he had the luxury of his assertions without the burden of proof. The Academy today, while equally as passionate about the aims of education as Whitehead, must not only describe its reason(s) for existence, it must also provide evidence that those aims which it described as important are ultimately attained by its students. This evidence must be considered and presented both for ourselves (The Academy) and for our â€Å"constituents† (i.e. students, accrediting bodies, employers, donors, and society). The authors assert that three issues are paramount to any assessment of a curriculum in higher education. The first deals with the â€Å"reason for existence† issue raised by Whitehead (i.e. Are we doing the right thing?). The second issue has to do with examination of whether we are accomplishing our goals (i.e. Are we doing the right thing right?). The final issue involves how we can assess whether we are doing the "right thing right." Doing the right thing? Several years ago, Millikin University embarked on the difficult challenge to create a seamless curriculum that provided for intentional connections -- connections between the major and the non-major, connections between the curricular components at each level, and connections between the curricular components over the course of four years. In the development of this comprehensive and cohesive curriculum (dubbed the MPSL -- the Millikin Program of Student Learning), the faculty identified "common threads" of the MPSL. Those common threads are 1) Student learning goals, 2) Core questions, values, and means, and 3) Proficiencies. (See the student learning goals in Table 1 for the specific elements defining each one). The faculty vision for the University is actualized through the effective implementation of these common threads within the curriculum.

Reverse Osmosis for Wastewater Recycling Essay

Reusing treated wastewater for beneficial purposes, such as agricultural and landscape irrigation, industrial processes, toilet flushing, or groundwater basin replenishment, is growing in response to environmental and economic concerns. One of the key factors involved in recycling wastewater treatment plant (WWTP) effluent for another use is the need to reduce total dissolved solids (TDS). This is often done by using a reverse osmosis (RO) system, which relies on pressure differential to force a solution (in this case, water) through a membrane that retains the solute on one side and allows the pure solvent to pass to the other side. While extremely effective on biologically treated wastewater, RO systems need to be coupled with an effective pretreatment system to avoid common issues that can result in system failure, including plugging, fouling, and scaling. One of the most effective pretreatment options for wastewater applications is membrane bioreactor (MBR) technology, in which a membrane process like ultrafiltration (UF) or microfiltration is combined with a suspended growth bioreactor. MBR provides high quality feed water to the RO, minimizes footprint and the cost of civil works, and reduces treatment plant downtime, thereby reducing operating costs. Koch Membrane Systems’ PURON ® submerged MBR technology has successfully been used as the pretreatment option for challenging industrial and municipal water reuse RO systems, and can help make water recycling technologies more cost-effective. Reverse Osmosis Systems Present Challenges for Water Reuse Pretreatment methods are critical when designing RO systems. For example, RO membranes used for most water reuse applications contain a brine spacer, typically made of low density polyethylene mesh netting. If there is a high level of suspended solids in the feed water, this brine spacer can become plugged. Another issue is the high levels of organics contained in many biologically treated wastewaters, which are rejected by the RO membrane and progressively concentrated as the water flows across the membranes. This concentration of organics can foul the membrane, especially towards the RO system outlet. Biofouling can also occur, because the organics in wastewater make an excellent food source for microorganisms. Also, some treated wastewaters contain high levels of bacteria, so biogrowth may occur quickly even if RO feed water is disinfected. Finally, calcium phosphate scaling can cause problems with RO systems operating on some wastewaters. The scaling can be mitigated by operating at lower water recovery, using acid or other antiscalant to minimize scaling, or modifying the operating conditions of the WWTP to reduce the amount of phosphate in the RO feed. These plugging, fouling, and scaling issues mean that the RO system needs to be operated at higher pressures, leading to increased power consumption, increased chemical costs for cleaning, and a shorter membrane life. How can these challenges be minimized and overall water reuse system lifecycle costs reduced? Effective pretreatment of the feedwater before it flows through the RO system is the answer, provided that the pretreatment steps are chosen carefully to ensure that the RO system can work as intended. Reverse Osmosis Pretreatment Options There are many different pretreatment options, and the best for a particular process depends on power, chemical, labor and land costs, wastewater source, and the existing wastewater treatment system. Conventional Pretreatment The conventional effluent pretreatment scheme might be primary treatment, biological treatment and, the most crucial part of the process, solids-liquid separation using secondary clarification. The conventional sedimentation process often doesn’t remove enough bacteria and suspended solids, so sand filtration may be added to improve the solids-liquid separation and provide higher quality water to feed the RO system. Using ferric chloride along with the sand filtration may enhance solids and organics removal. However, upsets in the secondary clarifier can lead to effluent with higher levels of TSS and BOD, causing plugging of the brine spacer with suspended solids and organic fouling. Also, power consumption for RO systems with this type of pretreatment tends to be high, and membrane life is often quite short. Lime-softening has been somewhat more successful in protecting the RO membranes, but this increases operating costs and does not totally prevent fouling of RO membranes. Ultrafiltration Improves Suspended Solids Removal As RO Pretreatment Many of today’s water reuse systems use an ultrafiltration (UF) pretreatment step to emove suspended solids. These systems typically use hollow fiber UF membranes, which do an excellent job of providing water with low suspended solids to feed the RO system. However, the UF system is an extra treatment step, requiring additional footprint, and adding to operating costs. The UF system may also be susceptible to upsets from a conventional WWTP, which can further increase its operating costs. Membrane Bioreactor As RO Pretreatment With an MBR, the UF membranes are submerged in the activated sludge to combine the biological step and the solid-liquid separation into a single process. The membrane acts as a barrier, which improves the effluent quality. The MBR eliminates the secondary clarifier and does not rely on gravity for liquid-solids separation and so allows the activated sludge to operate with a higher mixed liquor suspended solids (MLSS) concentration. The increased MLSS concentration reduces bioreactor tank volume, saving footprint and capital construction costs. Overall, the MBR process reduces footprint significantly compared to the combination of conventional activated sludge followed by sand filtration or ultrafiltration. The footprint savings due to the wastewater treatment plant alone can be as much as 50 percent, along with additional footprint savings from eliminating other filtration steps. Using MBR technology also simplifies the overall treatment train, minimizing the number of unit operations. Benefits Of Koch Membrane Systems’ PURON MBR Technology Koch Membrane Systems’ PURON submerged hollow fiber UF module offers robust, cost effective solutions for RO pretreatment. The patented membrane module contains hollow fibers, the lower ends of which are fixed in a header. The upper ends are individually sealed and are free to move laterally, as shown in Figure 1. The PURON module is submerged in the mixed liquor. All solids and particulates remain on the outside of the fibers while permeate flows in an outside-in pattern by means of a vacuum that evacuates permeate through the inside of the hollow fiber. | The free moving fibers, combined with central air scour aeration, ensure stable filtration during plant operation, long membrane life, and lower operating costs due to reduced need for energy, cleaning and maintenance. PURON MBR has been used successfully as the pretreatment step for a number of challenging industrial wastewater systems. For example, a Belgian firm that manufactures chemicals for film processing and printing uses large amounts of fresh water for cleaning and production. The firm began reusing its wastewater to reduce its fresh water costs, and selected an RO system to produce water with the low salt and nitrogen content required for its process. The firm installed a PURON submerged hollow fiber MBR as the pretreatment step prior to the RO, and the system has been operating successfully since 2005. Another example is an Australian malt-producing company that sought to reduce its use of fresh water by recycling its wastewater. PURON MBR technology was selected as the pretreatment step for the RO system, since it provided the best quality water to feed the RO while minimizing overall operating costs. The MegaMagnum ® RO system recovers the MBR effluent as product water for reuse. The system has been running since 2006. In fact, the RO permeate quality is equal to or better than the local potable water supply. Space & Cost Considerations Treatment operation footprint is a primary consideration in developing the best treatment system. Since the PURON MBR system reduces the volume of the bioreactor tanks and eliminates the secondary clarifier, the footprint for an MBR process is much smaller than tertiary filtration steps with sand filtration or UF. If space is limited, MBR may be the only pretreatment choice that fits in the available space. Other considerations include costs of land, civil works, equipment, power, chemicals and labor, and the payback period used. High land and civil costs tend to favor MBR use. For large municipal treatment facilities requiring RO as a final treatment step, an MBR should compare favorably to conventional wastewater treatment as a pretreatment step prior to RO. In a 20-year analysis the municipality should realize savings in RO membrane replacement and power as a result of the MBR pretreatment step. For an industrial company looking at a short payback, the preference for conventional or MBR technology will depend on the relative cost of civil works and land versus the equipment cost. Conclusions Using RO systems to reclaim and recycle wastewater effluent is growing rapidly, and Koch Membrane System’s PURON MBR technology is now being considered as the pretreatment option for an increasing number of industrial and municipal reuse applications. The PURON submerged membrane modules provide high quality feed water to the RO, minimize footprint and the cost of civil works, and reduce the susceptibility of the RO treatment train to upsets. PURON is a trademark of Koch Membrane Systems GmbH and is registered in Austria, Benelux, Canada, China, France, Germany, Italy, Oman, Saudi Arabia, Spain, Taiwan and the United Kingdom. MegaMagnum is a registered trademark of Koch Membrane Systems, Inc. in the United States and other countries. Wastewater Recycling for the Stone Fabrication Industry As a stone fabricator you’re looking for a wastewater treatment system that keeps you in compliance, but wouldn’t it be nice to save some money too? That’s where our wastewater recycling and treatment systems come in. These zero discharge, closed loop systems collect the water you use for polishing, cutting, and other processes; cleans it thoroughly, and recycles it so you can use it again. Your wastewater is never discharged into the public system during this process, so you have no chance of being out of compliance. Between the money you’ll save on non-compliance fees and the reduced cost of your water bill, the return on your investment will be substantial. And because we use the most durable, well-designed components on the market in each wastewater recycling system, you can be sure this system will run efficiently for as long as you need it to. We even design and manufacture some of those components in house, including: * Filter presses * Clarifier systems * Chlorine dioxide generators * Control panels * More The solid, smart construction of our zero discharge wastewater recycling systems results in a wide variety of beneficial features, including automation options, expandable filter presses that can accommodate your business as it grows, the ability to accommodate flow rates for 10 GPM – 200 GPM, the ability to filter solids water down to below 1 micron, and more.

Medieval Piety Essays - 1629 Words

Religion in the Middle Ages takes on a character all of its own as it is lived out differently in the lives of medieval men and women spanning from ordinary laity to vehement devotees. Though it is difficult to identify what the average faith consists of in the Middle Ages, the life told of a radical devotee in The Book of Margery Kempe provides insight to the highly intense version of medieval paths of approaching Christ. Another medieval religious text, The Cloud of Unknowing, provides a record of approaching the same Christ. I will explore the consistencies and inconsistencies of both ways to approach Christ and religious fulfillment during the Middle Ages combined with the motivations to do so on the basis of both texts. A central†¦show more content†¦Pursuing such spiritual fulfillment is a responsibility not to be taken lightly. Often, literal commands of Jesus such as pilgrimages have two and three fold benefits. Besides the very physical connections with the sacred that they offer arriving at places of sacred history, pilgrimages are also a form of penance for sins. Because of the sacrifice of time, money, and risk to make these pilgrimages, best seen by Kempes outrageous devotion in leaving behind her life and family for long periods of time, pilgrimages assist in erasing sins in ones life. Another reason that Margery and medieval Christians would embark on these pilgrimages is for the reverence of saints and their relics that they would visit. The Middle Ages emphasized an important connection to the lives of past saints believing that the saints still had power to intercede blessings into the lives of religious people on Earth. Where Margery is set a part from common laity, during her pilgrimage to Jerusalem she receives a special spiritual gift of â€Å"cryings† that she can not control when rel igious emotion comes over her. Describing these outbursts, the author of her autobiography says, â€Å"The crying was so loud and so amazing that it astounded people†¦Ã¢â‚¬  (Windeatt, 104). It is assumable that emotional experiences upon pilgrimages of either laity or monastics to such places as the Holy Land would be common, however that people wereShow MoreRelatedMedieval Woman Book Owners : Arbiters Of Lay Piety And Ambassadors Of Culture By Susan Groag Bell850 Words   |  4 Pages In the journal article Medieval Woman Book Owners: Arbiters of Lay Piety and Ambassadors of Culture, written by Susan Groag Bell, explains the cultural changes in the Middle Ages. She give details on how the increase in lay piety and vernacular literature were both connected with one another. In addition to this, these two topics played key roles in the changes taking place. The increase in lay piety is said to be a response to the political conflicts, religious demographic, and climatologica l factorsRead MoreA Critical Analysis Of Merciles Beautee1792 Words   |  8 Pageswith the representation of woman as an empowered â€Å"feudal lord† due to the sheer objectification of femininity and beauty. Poets such as Geoffrey Chaucer and William Dunbar commend a woman’s aesthetic appeal or satirise the lack of it, thus elevating medieval misogynistic expectations of physical beauty as a feminine necessity that objectifies women under the control of man’s advances. Throughout courtly love lyrics female beauty is a purely frivolous and superficial trait lacking predominant depth, toRead MoreThe Rise and Fall of Feudalism Essay868 Words   |  4 Pagesin Europe (136). Partially because of its success in providing security and stability, and also its huge promotion by the Catholic Church (136). The economics of Feudalism were based on Christianity and on politics that reflected the justice and piety of the Church (Pluta 1). The power of the church to gre at wealth overlapped with the expansion of Feudalism (International 136). Feudalism began to decline in parts of Western Europe by the fourteenth century as a result of pressure from a numberRead MoreMedieval Poetry3509 Words   |  15 PagesMedieval literature is a very diverse subject. The term covers the literature of Europe during the period between the fall of the Roman Empire and the beginnings of the Renaissance in the 15th century, spanning a period of roughly 1,000 years. As a result, it is difficult to make generalizations about medieval literature. It is, nonetheless, possible to identify a few general trends. Allegory and symbolism are common in medieval literature, perhaps more so than in modern writing. Religious and philosophicalRead More The Greatest Literary Emblem of the Middle Ages Essay2067 Words   |  9 Pagesthey flourished and developed, which was the Medieval Era. The Middle Ages is the period of European history that goes from the collapse of the Roman civilization to the beginning of the Renaissance, and it extends from about 500 to 1500 ca. (â€Å"Middle Ages†). This period is called the â€Å"Dark Ages† since it is regarded by the Renaissance scholars as a long interval of superstition, ignorance, barbarism, and social oppression due to the fact that the Medieval era was a fight to establish a new societyRead More Transcendentalism in Beowulf and Antigone2110 Words   |  9 Pagestheism, where the god or gods are treated as father figures; the gods controlled the lives of all their people just as parents control their children, even, as Martin Luther stat ed, with an attitude of fear. Through the periods of Ancient Greece, to Medieval Europe, to Renaissance Europe, a cycle forms from a completely transcendentalist attitude to a completely theistic attitude, and back. Some of the first literature scholars have recovered through the years has come from the Ancient period, particularlyRead MoreTrue Womanhood, By The Virgin Mary, Eve, And Noah s Wife1470 Words   |  6 PagesThroughout our classes and discussions we have discussed the topic of true womanhood, along with women in medieval drama. Thinking of these two concepts, the question arises are they any true women in medieval plays? The multiple plays that we have read, there are many different types of women that have been discussed. These plays covered drastic differences with the way the women acted, and their actions towards the men in their lives and certain circumstances. Through four plays, there are fourRead MoreThe Use Of Gunpowder And Firearms Triggered The Decline Of Chivalry1224 Words   |  5 Pagesespecially England and Germany, â€Å"were obsessed with strategies of offensive warfare that derived their historic precedents from the system of knighthood.†4 In fact, medieval knigthood did not solely consist of direct attack, but the important thing is that the nations involved in World War I considered themselves as revival of medieval chivalry. Therefore, European nations used the image of the brave knight, fighting for his country and suffering as Christ on the cross to encourage their own soldiersRead MoreMartin Luther Argumentative Essay1370 Words   |  6 Pagescongregation. The clergy’s use of indulgences as a way to salvation lacked the piety that disciples desired. Criticism of Catholicism did not cause sweeping changes in the sixteenth century; instead, the Protestant Reformation occurred due to the confluence of events triggered by one priest, Martin Luther. (Schilling) Although some historians allege that Martin Luther’s theology was reactionary due to its roots in medieval Christianity, his beliefs that the hierarchy of the church was unnecessary andRead MoreWomen And Spiritual Equality : New York : Saint Martin s Press, 1998 1358 Words   |  6 Pageswrites that there was controversy surrounding this practice, she avoids this debate and instead focuses on the content of the devotion. The era of the middle ages is the subject of chapters six through eleven. In chapter six, she presents early medieval saints. Though she had used Syriac sources in the earlier chapter, she relies heavily on them in the chapter and does not provide sources that reflect the rest of Eastern Christendom. She also begins to focus on specifically western saints at this