Improved Manufacturing Operations

1
CHAPTER 5

• Improved Manufacturing Operations

2
Cost Benefit Analysis
3
A Typical Industrial Process
4
Elements of P2 Efforts by 212 Industries
5
The Manufacturing Process

• Objective
• to transform an idea into a saleable product
• Steps
• Design
• Product Development
• Quality Control
• General Management
• Production

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Design

• Product Planning
• long term process to identify the product areas
  of interest
• Product Development
• concept further explored in relation to
  possibilities of the company
• Product Design
• creates a design on the basis of market-related,
  functional technical, manufacturing and
  aesthetics requirements

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Sequential Engineering

• Marketing identifies the need for new products,
  price ranges and their expected performance from
  customers or potential customers
• Design and Engineering work independently and
  develop the technical requirements and final
  design details
• Manufacturing, testing, quality control and
  service groups see the design in an almost
  complete stage
• As the manufacturing process is sequential in
  progression, it is commonly called sequential
  engineering

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Sequential Engineering Process
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Structure Of An Industrial Enterprise
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Concurrent Engineering

• Provides a systematic and integrated approach to
  introduction and design of products so as to
  ensure that decisions made in the design stage
  result in a minimum overall cost during its
  life-cycle

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Concurrent Engineering Process
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Concurrent Engineering (contd.)

• Objective
• Decreased product development lead time
• Improved profitability
• Greater competitiveness
• Greater control of design and manufacturing costs
• Close integration between departments
• Enhanced reputation of the company and its
  products
• Improved product quality
• Promotion of team spirit

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Concurrent Engineering (contd.)

• Design for Manufacture
• consideration of how well a design can be
  integrated into factory processes such as
  fabrication and assembly
• Design for Assembly
• consideration of ease of assembly, error-free
  assembly, common part assembly, etc.
• Design for Serviceability
• design to facilitate initial installation, as
  well as repair and modification of products in
  the field

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Concurrent Engineering (contd.)

• Design for Reliability
• consideration of topics such as electrostatic
  discharge, corrosion resistance, and operation
  under variable ambient conditions and so on
• Design for X
• term coined to describe these various segments,
  where X stands for the particular segment

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Chemical Reactors

• place where raw materials are converted into
  products
• primary source of waste materials
• operate in batch or continuous mode
• Batch mode all reagents are added to a stirred
  tank at the beginning of the reaction, no new
  material is fed or removed during the reaction
  period
• Continuous flow reagents are continually fed and
  products are continually removed

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Rate of Conversion
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Continuous Flow Reactors
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Heat Exchangers

• commonly used to exchange heat between products
  and reactants
• can be heater or cooler
• direct and indirect type
• indirect shell and tube exchangers

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Distillation

• most important process for the separation of
  chemical mixtures
• compounds with different vapor pressures cane be
  separated from a mixture by gradually varying the
  temperature
• batch or continuous

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Distillation Columns
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Absorption

• chemical or physical process of selective
  transfer of one or more compounds in the process
  stream into a liquid
• different types packed, tray, spray towers
• countercurrent or co-current

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Adsorption

• chemical or physical binding with the contact
  surface
• usually carried out in a column
• e.g. activated carbon, activated silica, resins

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Extraction

• transfer of solutes from a liquid or solid phase
  into a liquid solvent
• both liquid-liquid and solid-liquid extraction
  possible
• supercritical extraction
• essentially a liquid extraction process employing
  compressed fluids under supercritical extraction
  instead of normal solvents

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Supercritical Point
25
Supercritical Fluid Properties
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Drying

• used to either recover a solvent or to remove
  water or solvents from a solid product
• batch or continuous basis
• different types tunnel, rotary, drum, spray,
  flash evaporators

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Process Development And Design

• Refinement of a process concept from early
  conceptual stages through preliminary engineering
• Waste generation can often be minimized through
  proper design and operation of the process system

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Separation Technologies
29
Typical Environmental Design Constraints and
Objectives
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P2 Potential in theDesign Process
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Computer Tools

• assist in the preliminary stages of design, such
  as molecular description, synthesis pathway
  identification, etc.
• assist in design phases
• currently, computers are used in every stage of
  manufacturing, from conceptual design to final
  manufacturing.

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Computer Based ToolsIndustrial-scale Process
Design
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Computer Based ToolsChemical Changes
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Computer Based ToolsIndustrial Production Stage
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The Clean Process Advisory System

• collaborative effort of CenCITT, CWRT, and NCMS
• furnishes engineers with a means to routinely
  find, simulate and compare various design
  approaches on the basis of P2
• technology descriptions and expert guidance to
  find design options
• numerical simulations and property data resources
  to simulate those options, and
• data resources and algorithms to quantify and
  compare their pollution prevention dividends in
  conjunction with cost and safety implications

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Strategic WAste Minimization Initiative

• SWAMI developed by USEPA
• Designed to identify waste minimization
  opportunities within industrial settings
• provides a scheme for identifying and
  prioritizing (on a cost or volume basis) waste
  reduction opportunities
• performs mass balance calculations, draws process
  flow diagrams, and
• directs the selection of candidate waste
  minimization strategies.

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EcoSys

• Developed by DoE
• allows the opportunity to see the potential
  impact of environmental strategies, manufacturing
  processes or products before investing
  significant amounts of time or money
• includes a database with the environmental
  characteristics of more than 500 substances and
  four models of environmental thinking

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Process ChangesAdvanced Process Technologies

• Question can anything be done to increase the
  efficiency of the reaction?
• Many times, simple changes in operating
  conditions like reaction temperature or process
  can greatly increase efficiency

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Strategies for Minimizing Pollution

• Avoid adsorptive separations where adsorbent beds
  cannot be readily regenerated
• Provide separate reactors for recycle streams, to
  permit optimization of reactions
• Consider low-temperature distillation columns
  when dealing with thermally labile process
  streams
• Consider high-efficiency packing rather than
  conventional tray-type columns, thus reducing
  pressure drop and decreasing reboiler temperatures

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Strategies for Minimizing Pollution (contd.)

• Consider continuous processing when batch
  cleaning wastes are likely to be significant
  (e.g., with highly viscous, water-insoluble, or
  adherent materials)
• Consider scraped-wall exchangers and evaporators
  with viscous materials to avoid thermal
  degradation of product

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Process ChangesImproved Reactor Design

• Improve the degree of agitation
• better mass transfer efficiency
• use more efficient mixers and baffling systems
• Insulate the reactors
• improves temperature control within the reactor
• Use high efficiency heat exchangers
• Switch to continuous flow mode
• Simplify cleaning of the reactor

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Other Process Changes

• Increasing the number of stages in extraction
  processes that use water
• Using spray balls as a scouring agent for more
  effective internal vessel cleaning
• Changing from wet cooling towers to air coolers
• Improving control of cooling tower blowdown
• Attaching triggers to hoses to prevent unattended
  running

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Other Process Changes (contd.)

• Improving energy efficiency to reduce steam
  demand and hence reduce the wastewater generated
  by the steam system through boiler blowdown,
  aqueous waste from boiler feedwater equipment,
  and condensate loss
• Increasing condensate return from steam lines to
  reduce boiler blowdown and aqueous waste from
  boiler feedwater equipment
• Improving control of boiler blowdown

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Process ChangesImproved Reactor Control

• Improving reactor environment controls can have a
  substantial impact
• Control system efficiency improved by
• Measurement accuracy, stability and repeatability
• Sensor locations, controller response action
• Process dynamics
• Final control element (valves, dampers, relays,
  etc.) characteristics and location
• Overall system reliability

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Process ChangesImproved Separation Processes

• Do mechanical separations first if more than one
  phase exists in the feed.
• Avoid over-design and use designs that operate
  efficiently over a range of conditions. Favor
  simple processes.
• Favor processes transferring the minor rather
  than the major component between phases.
• Favor high separation factors.
• Recognize value differences of energy in
  different forms and of heat and cold at different
  temperature levels.

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Process ChangesImproved Separation
Processes(Contd.)

• Investigate use of heat pump, vapor compression,
  or multi-effects for separation with small
  temperature ranges.
• Use staging or countercurrent flow where
  appropriate.
• For similar separation factors, favor energy
  driven processes over mass separating-agent
  processes.
• For energy driven processes, favor those with
  lower heat of phase change.

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Separation Processes
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Recycling

• Attractive way of reducing waste streams needing
  treatment and the associated costs, while at the
  same time reducing the demand for virgin process
  chemicals and their associated costs
• May be on-site or off-site

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Recycling Options
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Typical Water Use on a Chemical Process Site
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Product Changes

• Make changes in the product itself or in the
  chemicals used to make the product
• Replace solvent-based paints with water-base
  paints
• Substitute parts which can be reused
• Workpieces with fewer turnings and cavities will
  reduce the amount of dragout from process tanks

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Storage

• Establish a Spill Prevention, Control and
  Countermeasures (SPCC) plan
• Use properly designed storage tanks and vessels,
  and only for the intended purpose
• Install overflow alarms on all storage tanks
• Install secondary containment areas
• Document all spillage
• Space containers to facilitate inspection
• Stack containers properly to minimize tipping,
  breaking, or puncturing

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Storage (contd.)

• Raise containers off the floor to minimize
  corrosion from sweating concrete
• Separate different hazardous substances to
  minimize cross-contamination and to separate
  incompatible materials
• Use a just-in-time order system for process
  chemicals
• Order reagent chemicals in exact amounts
• Establish an inventory control program to trace
  chemicals from cradle to grave
• Rotate chemical stock

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Storage (contd.)

• Validate shelf-life of chemical expiration dates,
  eliminate shelf-life requirements for stable
  materials, and test effectiveness of outdated
  materials
• Label all materials and containers with material
  identification, health hazards, and first aid
  recommendations
• Switch to less hazardous raw materials
• Switch to materials packaging and storage
  containers that are less susceptible to corrosion
  or leakage

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Storage (contd.)

• Use large containers where possible to minimize
  the tank surface-to-volume ratio, thereby
  reducing the area that has to be cleaned
• Use rinsable/reusable containers
• Empty drums and containers thoroughly before
  cleaning or disposing

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Most Common Deficiencies in Storing Hazardous
Wastes and Materials
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Management

• For P2 programs to be successful, management has
  to be fully committed to concepts of Pollution
  Prevention
• Well conceived and functional preventive
  maintenance program
• Proper employee training
• Good Record keeping

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Housekeeping

• Close or cover solvent containers when not in use
• Isolate liquid wastes from solid wastes
• Turn off equipment and lights when not in use
• Eliminate leaks, drips and other fugitive
  emissions
• Control and clean up all spills and leaks as they
  occur
• Develop a preventive maintenance schedule and
  enforce its use
• Schedule production runs to minimize cleaning
  frequency

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Housekeeping (contd.)

• Improve lubrication of equipment
• Keep machinery running at optimum efficiency
• Dry sweep floors when ever possible
• Do not allow materials to mix in common floor
  drains
• Insist on proper labeling of all containers
• Educate all employees as to the need for proper
  housekeeping practices
• Include housekeeping reviews in all process
  inspections
• Adopt a Total Quality Management philosophy

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Training

• Key to the success of any P2 program
• Should be ongoing, with frequent review updates
• Should provide the necessary information to
  achieve P2 goals
• Variety of training techniques should be used
• Operators should play a major role in training

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Training(contd.)

• Promote awareness of waste reduction initiatives
• Establish quantifiable wastewater reduction goals
• Train personnel in waste reduction techniques and
  water usage minimization practices
• Implement plant-wide waste reduction techniques
  and water usage minimization practices
• Monitor progress toward attaining waste reduction
  goals and readjust objectives if they prove to be
  unattainable
• Attain waste reduction goals

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Record Keeping

• Helps in both the development and implementation
  of a sound pollution prevention program
• Document process procedures, control parameters,
  chemical specifications, chemical usage, energy
  usage, waste generation, and spill frequencies
• Inventory control, for both process chemicals and
  waste materials, will reduce the volumes and thus
  reduce costs and potential losses to the
  environment from leaks or spills, or the need to
  dispose of contaminated, off-specification or
  out-of-date reagents