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Estimation of Manufacturing Costs - Coggle Diagram
Estimation of Manufacturing Costs
Introduction
Cost associated with day to day operation of a chemical plant
The primary components of the cost of manufacture are raw materials, utilities, and waste treatment
Estimation of Manufacturing Cost
Direct Cost
Include expenses directly associated with the manufacturing operation
Vary with production rate but not necessarily directly proportional
Raw Materials
Waste Treatment
Utilities
-Operating Labor
Supervisory and Clerical labor
Maintenance and Repairs
Operating Supplies
Laboratory Charges
Patents and Royalties
Fixed Costs
expenses that remain practically constant from year to year
Do not vary with production rate but relate “directly” to production function
Rent
Local Taxes and Insurances
Depreciation
General Expenses
Functions to which operations must contribute –overhead burden
For hospital and medical services, general plant maintenance and overhead etc
Do not vary with changes in production rate
Administration costs
Distribution and selling costs of products
Research and development expenses such as salaries, special equipment, research facilities and consultant fee
Manufacturing Costs
Table 8.1
Description of items
Table 8.2
Factors for estimating costs
Maintenance and repairs
2-10% FCI
Proportional to size of plant
Supervisory and clerical labor
10-25% COL
Proportional to op. lab
Depreciation
some % of FCI
COM = DMC + FMC + GE
Cost of Operating Labor
NOL = the number of operators per shift
P = particulate processing steps
Nnp = non-particulate processing steps – compression,
heating/cooling, mixing, separation, and reaction
Cost of Raw Materials, Utilities, and Waste Treatment
Flowrates
Get these from PFD
(use Stream factor)
Costs
Utilities and waste treatment (Table 8.3)
Common chemical (Table 8.4)
Stream Factor
Operating hours per year divided by total hours per year
Typically 8000 operating hours
0.9 - 0.95 typical
8000/8760 = 0.913
Utilities (Fuel and Electricity)
Fuel for Fired Heaters
PFD gives process load (energy balance) but total flow is more due to efficiency - 70-90% from Table 11.11
Fuel cost may vary wildly
Electricity for pumps and compressors
Shaft power (fluid power/efficiency)
Power to drive (shaft power/drive efficiency)
Utilities (Steam)
Pressure levels
Low (2-6 bar)
Medium (10-17 bar)
High (44.3 bar)
Available saturated but sometimes superheated
Large chemical complexes generate high-pressure steam and use excess pressure to generate electricity
Steam can be used as a drive medium for compressors and pumps
Thermodynamic efficiency
Drive efficiency
Utilities (Cooling Water)
Make-up based on Delta T (40-30)
Should charge cw based on energy used (Table 8.3)
Does not matter (much) if cw returned at 40 or 45 degree Celsius (same energy)
45 degree Celsius is absolute max (due to fouling)
Utilities (Refrigerated Water)
Energy costs are not Delta T dependent (cost based on 5 degree Celsius supply temperature)
