OPEN PARA LA SEGURIDAD Y EL RENDIMIENTO

Mejore la seguridad y el rendimiento de su planta gracias a la gestión de alarmas, la supervisión de rendimiento y de activos, la visualización web de datos, la optimización, el control avanzado y la sintonía con la nueva herramienta TaiJi.

Repiensen sus métodos de trabajo y obtengan resultados inmediatos gracias a nuestros servicios, nuestra capacitación y nuestra pericia en asesoría. Manejen el cambio inteligentemente con nuestras soluciones probadas.

Asociado certificado

July 2006

In this issue

puce Classes
puce Articles
puce Trick of the month: How to estimate optimization results?
puce To contact us



Coming classes and seminars

PlantTriage - Performance supervision and Process Control Optimization
September 12-14, Houston, TX

PlantTriage, What's new in V6?
September 15, Houston, TX

See our calendar for 2006

Articles

  • An article by Michel Ruel is published in Process West, June 2006 issue:
    « Performance and Benchmarking ».
    Click here to learn more.

  • An article (1 of 4) by Claude Gosselin from Compagnie Minière Québec Cartier and Michel Ruel will be published in ISA Management Newsletter :
    «Advantages of monitoring the performance of industrial processes».
    Click here to learn more.

This month's tip : How to estimate optimization results?

The idea is to have numbers for every aspect. These estimates can de calculated before optimization or after the work is done.

Benefits of optimization

Usually, we consider these topics :
  • Increase process performance
  • Better use of the equipment
  • Reduced energy costs
  • Improved product quality
  • Variability reduced
  • Reduced valve maintenance
  • Cycling removed
  • Increased up-time
  • Efficiency improved
  • Better operation
  • Smooth start-up

Expected results

If the work is done professionally using good tools and applying best practices, we can estimate that we will obtain:

  • variability,
  • quality,
  • cycling,
  • valve travel,
  • robustness,
  • efficiency,
  • energy costs,
  • reduced by a factor of 2
  • improved by +30%
  • removed
  • reduced by a factor of 5;
    we also estimate that valve wear should be reduced by a factor of 2
  • will be twice better; stability will be twice better when process changes
  • increased by 1 to 5 %
  • reduced by 1 to 5 %

An example

Dryer system using steam to remove water from material (could be mineral, cardboard, etc.).


Constraint imposed by the customer at 8%; above 8%, the product is not sellable.

Steps to optimize this process:

  1. Optimize other parts of the process before the dryer to minimize variability coming in.
  2. Optimize steam and condensate process to ensure that response is fast and interaction among consumers and suppliers of steam is minimized.
  3. Optimize the drying section.
We consider for this example that steps 1 and 2 were part of another project. Hence, the estimates below are for step 3 only.

The image below will be used to explain this case.
  • Blue line is the set point for the moisture content.
  • Red line is the moisture content measurement.
  • Black line is the constraint imposed by the customer.
  • Green line is the controller output sending a command to the steam valve.

  • Before optimization (400 to 1000 minutes)
    • The moisture content has too much variability, we have to dry too much to ensure we remain below the constraint all the time.
    • We spend too much on energy.
    • We sell too much material; if average moisture content would be higher, we would sell more water and less material to our customer.
    • We also abuse the equipment.
  • Optimization
    • Verify and repair equipment: valves, transmitter,etc.
    • Tune loops and review control strategies
    • Adjust alarms and interlocks
  • After optimization (1000 to 1200 minutes)
    • Steam valve travel has been reduced (we can expect the same for other valves)
    • Variability has been reduced
    • We have now an opportunity gap to increase the SP and reduce steam consumption
  • After SP increase (1200 min and after)
    • We are now running close to the limit; SP increased from 5% to 7.8%
    • Steam valve opening is reduced from 26% to 24% (averages)
    • Valve travel greatly reduced.

To prepare our estimates:(Dry Ton = dT)

  • Cost of energy 50$/dT (before optimization)
  • Cost of dry material 500$/dT
  • Selling price 900$/dT
  • Net profit 150$/dT
  • Production is 600 dT/d (0.45 dT/min)
  • Number of valves 40
  • Number of loops 32
  • Valve repair: 3200$ (spare parts + work) every 5 y
  • 3 Start-up/w, 153 Start-up/y(excluded from uptime)
  • 362 days of production per year
Before After Improvement
Efficiency (uptime) 95% 96% 1%
Start-up time 45 min 20 min 25 min
SP 5% 7.8%
Energy cost(/dT) 50.00$ 46.00$ 4.00$
Dry material sold 95% 92.2% 2.8%

Production increase from uptime

Before After Improvement
Efficiency (uptime) 95% 96% 96%/95%=1.0105
Daily production(dT) 600 600 *1.0105=606.3 6.3
Yearly production 600DT/d* 362d=217 200 dT 606.3dT/d* 362d=219 486 dT 2286 dT
Added profit 2286 dT * 150$/dT= 342 900$

Production increase from better start-ups

Before After Improvement
Loss time 153 Start-up/y *45 min=6 885 min/y 153 Start-up/y *20 min=3 060 min/y 3825 min=63.75 h
Yearly production loss 0.45DT/min*6885 min=3 098 dT 0.45DT/min*6885 min=1 377 dT 1721 dT
Added profit 1721 dT * 150$/dT=258 150$

Cost per dry ton:

Before After Improvement
Energy cost 50.00$ 46.00$ 4.00$
Dry material sold 95% 92.2% 2.8%
Yearly production loss 95% x 500$=475$ 92.2% x 500$=461.50$ 13.50$
Added profit 475$ + 50$ =525$ 461.50$ + 46$=507.50$ 17.50$

Production increase from energy reduction

Before After Improvement
Yearly production 600dT/d* 362d=217 200 dT 606.3dT/d* 362d=219 486 dT 2286 dT
Cost change 217 200 dT * 525$/dT=114 030 000$ 219486 dT* 507.50$/dT=110 950 173$ 3 079 827$

Maintenance reduction (50% on valves)

Before After Improvement
Valves per year 40 valves/5y=8 valves 4 valves
Cost 3 200$ * 8 valves=25 600$ 3 200$ * 4 valves=12 800$ 12 800$

Total yearly savings for this project

Improvement
Energy reduction 3 079 827$
Start-up 258 150$
Uptime 342 900$
Maintenance reduction 12 800$
Total 3 693 677$

Accounting

Optimizing 32 loops can be done within 1 week. Hence the total cost for this optimization is under 10 000$. Return on investment is evaluated in days, not months.
At this point an accountant would also evaluate cash flow, ratios, etc.

Other considerations (not calculated here):

  • Improved stability and smoother operation
  • Steam header stability, improving performance on other parts of the process
  • Unplanned shutdowns reduction
  • Better quality product (less variability)

To contact us

puce Lévis's office +1 (418)834-4321
puce Pointe-Claire's office +1 (514)695-3492
puce Hartland's office (877)867-6473
puce Toll free (877)867-6473
puce Email info@topcontrol.com