A Working Guide to Process Equipment

(continuing professional development– CPD Course)

Resource person: Engr. Yasin ZafarPFL Multan

Today’s AGENDA

Introduction – Resource person & AudienceBasic Chemical plant Terminologies / ConceptsSteam – Steam Turbines – Air CompressorsHeat Exchangers – Trouble shootingsPumps – Start-up and Operational hazardsFiltration systems – ImprovementsAbsorption & Adsoprtion Instrumentation & Control - AccidentsSuggested Readings

Basic Concepts

Difference between Heat and TemperatureHeat:Heat can never be contained in a body or possessed by a body.Heat is energy in transit.• Thermal equilibrium• Units• Heat Transfer & Thermodynamics

– (ref. Applied Thermodynamics by A. McCONKEY)

Pressure & Stress

Cross sectional area & Surface area

Pressure and Flow

• If end of the piping system is closed??• If end of the piping system is opened??

• Centrifugal compressors & Axial flow compressor

• Examples

Pressure and Vacuum

• Pressure below atmospheric• 0 is a perfect vacuum

• How we can make vacuum?• Why we need vacuum?• Vacuum in INSULATIONS

• Vacuum Hazards?• Jets ejectors require very little attention and

maintenance.

Ejector

Critical Temp. & Critical Pressure

• Above that temp., a gas can not be liquefy.

• LCO2 = 31C• Critical pressure = 72 atm

• Phase Diagrams

• Cryogenics: Cryos: Cold, Genics: Generation

STEAM

• Sensible and latent Heat• Saturated and Superheated Steam - Examples

• Pressurization of steam circuit– Hammering– Steam traps

– (ref. Design of Fluid Systems by Spirax Sarco)

Main Steam Circuit

Steam Turbine

What causes steam turbine to spin?

Air Compressors - Axial

The last stage is Centrifugal

Operational Hazards of Compressors

• What is surging?

• Why Surging Occurs?

• Performance curves of air compressor

• Operational Excellence

SURGING

LEGENDS

NORMAL FLOW

REVRSE FLOW

Is Chemical Engineering an ART or SCIENCE??

Chemical Engineering is both an ART and Science (Mccabe and Smith)

TRUE or FALSE!!!

HEAT EXCHANGERS TYPES

• Direct Contact– Cooling towers

• In Direct Contact– Shell and tube heat exchangers

• Recuperators– Regenerators

Construction of Heat Exchangers

Components of HEX

Channel baffle and Tube Sheet

Spiral / Coil Heat Exchanger

Triangular Pitch

Plugging of tubes

Expansion Bellows

Operational Plant Terminologies

• Battery Limit• Raw Material• Final Product with Quality• Plant Load• Consumption factors• Inventories / Stock Level• Reaction Chemistry• Line tracing – PFD & P&ID

Centrifugal PumpsHow it works?

Operational Problems

• Cavitation• Mechanical Seal Damage• Vibrations• Suction strainer chocking• Discharge NRV stuck• Low level of suction reservoir• High bearing temperature

Major components

Balancing & Min. flow line

Bearing Housing

Filtration System

• Importance• Types – Dust Louvers, Candles, Dri packs, • Trouble shootings• Pressure drop across filters – if more ∆P?• Improvements

– (Ref. American Air Filters, AAF)

Absorption & Adsorption

• Unit Operations & Unit Processes• Physical and chemical• Absorption tower – Tray or Packed• Adsorbers & Dryers• Favorable conditions• Trouble shootings

Absorption Tower

Bubble Cap Column

Structure of Bubble Cap

Internals of Absorption Tower(Sealing)

Weir and Down comer

Instrumentation & Control

• Hardware elements of process control system

• RTD’s and Thermocouples

• Orifice and pitot tube

• Ratio Control

RECORDER

CONTROLLER

Field Rack Room Control Room

OUTPUT BARRIER

INPUT BARRIER

TRANSMITTER

CONTROL VALVE

Control Output Set Point

4-20 mA

4-20 mA

TYPICAL CONTROL LOOP

Objectives of Control System

• Ensuring the STABILITY of chemical process

• OPTIMIZE the PERFORMANCE of chemical process

• SUPPRESS the influence of EXTERNAL DISTURBANCE

LOOP TAG

LOOP DESCRIPTION

MODE OFOPERATION

PROCESSCONDITIONS

OF LOOP

PROCESSVARIABLE

SET POINT

Manipulated Variable

LOOP OUTPUT

CONTROL LOOP FACE PLATE

Manual CascadeAuto

Interlocking & Logics

• What are interlockings?

• Why Interlockings and Logics?

• Examples

• Failure of interlockings / logics

Purpose

• The alarm and interlocking system is designed to protect the plant and personnel from damage due to dangerous operating conditions. When such conditions arise, the plant is shut down and , at the same time, the necessary safety devices go into operation.

Plant Safety

• PSV’s• Safety Trips• Housekeeping• MSDS• Fire fighting Equipment• Safety Equipments

(ref. MSA, Chemical Safety Board (CSB)

47

03 FACTORS for SHAFT

CRITICAL SPEED

VIBRATION

STRESSES

48

STRESSES• Shaft is subjected to the action of forces called

STRESSES.

3 types of stresses: • Torsional stress: twisting• Bending stress• Axial stress

49

CRITICAL SPEED

• The speed of shaft rotation which is equal to the shaft frequency of vibration is called critical speed.

50

Vibration

• The cyclic or pulsating motion of a machine or machine component from its point of rest.

• Vibration always transmits as SINE wave. Sine wave can be measured.

Accidents

Suggested Readings

• A working guide to process equipment by Lieberman• Fertilizer Manual by UN Industrial Development

Organization• STOP (Safety training observation program) Series• Troubleshooting process operations by Lieberman• www.4shared.com

• Resource person email contact: yasin_zafar@yahoo.com

Q & AQ & A?

Thank You!Thank You!