Author: Paul McCarthy, Bachelor of Engineering (Hons) in Chemical and Biopharmaceutical Engineering, Department of Process, Energy and Transport Engineering, Cork Institute of Technology; Academic Supervisor: Noel Duffy, December 2015

Abstract

The aim of this report is to evaluate the process and economic impacts of the use of raw material A in the production of product X at a client manufacturing company. The analysis was performed by comparing the use of 3B/1A and 4B raw material mixtures in the manufacture of this product, using historical data from the year 2014.The key findings were:
  1. 3B/1A mix suffers greater average filtration losses of 22 per cent when compared to the 19.6 per cent losses associated with the 4B mix
  2. Re-slurry tank average solids concentration is lower for 3B/1A at 20.7 per cent than for 4B at 21.2per cent
  3. Average dryer throughput is lower at 1,996kg/hr when 3B/1A is in use, compared to 2,035kg/hr for 4B raw material
  4. In process quality marginally improves when 3B/1A is used
  5. Net average hourly income when 3B/1A is in use is 22,051 MU*, and 22,244 MU when 4B is used.
There is, therefore, compelling evidence to suggest that the use of raw material A should be discontinued in the production of product X at the client company. (*MU is a derived currency, used to protect the client company’s commercially sensitive information)

Introduction

[caption id="attachment_28143" align="alignright" width="300"]aaaduffy1 Figure 1: Process flow diagram for the product X production process[/caption] The client company manufacture various products, one of which is product X. The manufacturing process is made up of numerous unit operations and the key steps are shown in the process flow diagram in Figure 1. These steps are crucial to optimum plant performance as they directly impact dryer throughput which is a key metric of plant performance.

Statistical analysis

The client company want to know if there is a statistically significant difference between the process parameters detailed in Table 1 below. A statistical inference analysis procedure was developed and applied to the process data, the results of which are shown below. Table 1: Parameters investigated and results of statistical analysis
Parameter Parameter of Interest (3B/1A) Parameter of Interest (4B) Test Performed Statistically Significant Difference
Filter Losses 0.2123 0.1897 Mann-Whitney Test Yes
RST  Actual % Solids 20.595 21.347 Mann-Whitney Test Yes
RST  % Solids Set point 20.600 21.400 Mann-Whitney Test Yes
RST  Actual vs Set point 0.080 0.071 Mann-Whitney Test Yes
RST  Line Pressures 4.738 4.354 Mann-Whitney Test Yes
DFT  Line Pressures 4.8612 5.3710 Mann-Whitney Test Yes
Dryer Throughput 1996.0 2034.8 2 sample t-test Inconclusive
Moisture Content 3.60 3.52 Mann-Whitney Test No
Average Particle Size 111.50 110.45 Mann-Whitney Test No
Lint 1.0 1.0 Mann-Whitney Test No
Loose Bulk Density 0.296 0.294 Mann-Whitney Test Yes
Specks 18 18 Mann-Whitney Test No
 

Process impacts

[caption id="attachment_28145" align="alignright" width="300"]aaaduffy2 Figure 2: Trends of filter throughput and losses over time (click to enlarge)[/caption] [caption id="attachment_28146" align="alignright" width="300"]aaaduffy3 Figure 3: Trends of re-slurry tank solids concentrations over time (click to enlarge)[/caption] (a) Filtration losses Increased filtration losses associated with 3B/1A mix, and the corresponding reduced filter throughput are shown in Figure 2. [caption id="attachment_28147" align="alignright" width="300"]aaaduffy4 Figure 4: Dryer throughputs for product X in 2014 (click to enlarge)[/caption] [caption id="attachment_28148" align="alignleft" width="300"]aaaduffy5 Figure 5: Comparison of utilities costs for each raw material mixture (click to enlarge)[/caption] (b) Re-slurry tank solids control The impact of the use of 3B/1A mixture on re-slurry tank solids control is clearly demonstrated in Figure 3. (c) Dryer throughput The impact of the use of 3B/1A mixture on dryer throughput can be seen in Figure 4.

Economic impacts

Increased gas, electricity and water usage and costs are associated with 3B/1A mixture as shown in Figure 5. Table 2: Comparison of costs for raw material A and raw material B
3B/1A 4B
Qty. Unit Price Sub Total Qty. Unit Price Sub Total
Gas (kWhr) 546.47 0.10 56.31 503.13 0.10 51.84
Water (m3/hr) 6.22 2.95 18.37 5.66 2.95 16.73
Electricity (kWhr) 6.73 0.30 2.02 6.00 0.30 1.80
RM B (kg/hr) 1,951 2.78 5,425.06 2,600 2.78 7,228.92
RM A (kg/hr) 650 2.21 1,438.51
Total Costs : 6,940 7,299
Product (kg/hr) 2,028 2,090
RFT Product (kg/hr) 1,846 15.71 28,991.21 1,881 15.71 29,543.27
Total Revenue : 28,991 29,543
Net Income (MU/hr) 22,051 22,244

Conclusions

The following conclusions indicate that the use of the 3B/1A raw material mixture had a negative impact on the production of product X in 2014.
  1. Mean filtration losses were 22 per cent for 3B/1A and 19.6 per cent for 4B.
  2. Average re-slurry tank solids were 20.7 per cent for 3B/1A and 21.2 per cent for 4B.
  3. Average dryer throughput was 1,996 kg/hr for 3B/1A and 2,035 kg/hr for 4B.
  4. Average net hourly income was 22,051 MU for 3B/1A and 22,244 MU for 4B.
  5. A typical product X campaign of 300MT took, on average, four hours longer to complete using 3B/1A.
Recommendations
The following are recommended:
  1. The filter correction factor requires regular monitoring.
  2. Re-slurry tank solids control needs to be upgraded.
  3. Long term analysis of Raw Material C could be beneficial.
  4. Investigation of the impact on effluent COD is required.
  5. A thorough examination of the impact on line pressures is necessary.
  6. Further investigations into other products are also required.