How to Increase Chemical Plant Profitability – Part 5 – Consumables Reduction

One of the most common methods for reducing a processing plant’s expense costs and increase profitability is through consumable reduction.

This could include anything from:

  • Mill balls
  • Specialty chemicals
  • Filter cloths
  • Cleaning supplies, eg. acid
  • Anodes

Consumable reduction

Understand the mechanism

Understanding the mechanism of the consumable is the first step. Whether it is understanding that mill ball wear rates are a function of surface area, or that acid washing consumption is based on equipment online time or impurity concentrations.

This process can often take a lot of reading through journal articles or textbooks to understand the fundamentals, and then conducting a series of experiments and data analysis to justify your own process and decision making.

Improve instrumentation and process control

One of the best ways I have found to reduce chemical dosing consumption is to improve the instrumentation and process control. Often simple chemical dosing system will just dose at a fixed flow or pump output.

In reality the optimum dose is generally as a volumetric ratio to the main flow. If this flow is variable, then there will be a large portion of the time when the specialty chemical is either over or underdosing. Improving the flow metering and implementing a flow ratio controller will both improve the performance and reduce consumption.

Trial new technology

Technology is always advancing, and there are companies who’s sole purpose is to reduce consumable use. For example, if you are looking at reducing the use of filter clothes there are dozens of filter cloth manufacturers who spend a lot more time looking at this and have dozens of different products all for different industries and purposes.

Trialing new technologies is a great way to find more effective and more resistant materials. It also helps you to understand what different components or fundamentals play the biggest part in providing robustness and reducing cost.

Consumable reduction is a great place to start in improving processing plant profitability, and can often be a simple and straight forward practice to reducing operating costs.

6 Tips to Improve Engineering Spreadsheets

As a chemical engineer you are guaranteed to spend hundreds of hours in excel creating spreadsheets, pouring through data, performing analysis, and filtering outliers. One of the hardest tasks is to take another person’s poorly structured spreadsheet and true to understand their logic. These 5 tips give a way to help improve engineering spreadsheets and avoid spending time deciphering poorly structured calculations.

improve engineering spreadsheets

  1. Colour co-ordinate cells

I am a big fan of using different colour codes on different cells types. You can set one colour for input cells, one colour for calculations, one colour for constants and coefficients, and another for outputs.

This makes it very clear which cells should be modified, and which ones can be left alone.

  1. Use conditional formatting

Conditional formatting will automatically change the colour and style of a cell based on any number of equations. For example if you are performing a series of economic analysis looking at different options you could set that negative economic outcomes where presented in red and positive outcomes are green.

You can also set data bars and colour scales to highlight a range of cells from large to small. This makes it very easy to find outliers when looking through a large data sheet full of numbers.

  1. Document calculation logic and data sources

If you pull out a spreadsheet from several months ago it should be structured in such a way that it is as easy to understand now as it was the day it was created. A great way of doing this is to document the calculation logic in a step-by-step manner.

It is also important to put in the sources for important data so that it can be checked or updated if conditions have changed.

  1. Use Macros to replace tedious tasks

For some spreadsheets that are updated frequently it can be a chore to constantly change or move data around. It can also cause errors to appear if a mistake is made.

Macros can be an easy solution, that while take some time to set up initially, can reduce wasted time in the future. This is particularly useful if a set of maneuvers can be automated with a single button click.

  1. Use Auto Sort & Filter

For data analysis the automatic sort & filter tool is a time saver. By eliminating irrelevant data sets it can make the solution clear or at least provide more representative data quickly and easily.

Applying this tool to a large data set is very useful at reducing thousands upon thousands of data sets to the few key pieces of information you are hunting for.

  1. Freeze headings

For very large spreadsheets a simple way to improve the ability to understand is to freeze the headings. This means that it does not matter how far down or across you scroll, the headings will come with you.

I spend the majority of my working week using excel, and I still set up my spreadsheets with a poor structure, but it is an important skill to practice. And over time it will make your whole team’s efficiency increase just to improve engineering spreadsheets.

 

Increase Chemical Plant Profitability – Part 3 – Production

This is Part 3 of the How to Increase Chemical Plant Profitability series.

One of the most popular methods to increase plant profitability is to increase the production capacity of the site without using any additional equipment. This method is most common amongst production of commodities where the sale of the product is almost guaranteed.

This works in two ways:

  1. Direct increase in profit from increased quantity of sales
  2. Efficiency increase through dilution of fixed losses

The first part is fairly self explanatory, so I won’t dwell on that but part two only works without replicating existing production lines.

Focusing on energy efficiency fixed losses are based on temperature (which is generally controlled) and surface area of the vessels (which are fixed). So by increasing flow through the circuit the heat losses remain the same. This means that profitability can be increased by improving energy efficiency through increased flow/production.

production_dilutes_fixed_losses(1)

 

But heat losses are only one of the expenses that can be diluted out through increased production. If the increased production can be done without needing to hire additional people then the total site labour costs can also be diluted out. Anything from energy, to labour, and maintenance costs can be reduced per tonne is this manner.

The actual method of how to increase production is incredibly subjective and cannot be explored in any detail in this general article, but the theory is to identify and eliminate any bottlenecks. This can include anything including:

  • Pumping capacity
  • Storage capacity
  • Customer requirements
  • Ability to hit control setpoints
  • Any equipment capability
  • Labour requirements
  • Maintenance speed
  • Breakdown frequency

The idea behind this method of improving site profitability is fairly easy to grasp so it doesn’t need much detail but the actual execution can be very difficult and time consuming.

 

 

Pulp and Paper Production – The Kraft Process Overview

The kraft process is a process for creating wood pulp out of wood, for use in paper production. Unlike many other chemical engineering processes, the kraft process is not named after its inventor, but instead derived from the German word kraft, meaning “strong.”

This name was chosen by the inventor of the process himself, Carl Ferdinand Dahl, who intended to market the superior strength of the paper created from this process.

A resident of Danzig, Kingdom of Prussia (present-day Germany), Dahl invented the process in 1879, and had himself awarded a U.S. patent for the invention on April 15, 1884. His invention was first put into action when a pulp mill in Sweden first began using it in 1890.

Kraft ProcessThe kraft process has undergone significant improvements throughout the century, especially since the invention of the recovery boiler during the early 1930s by G.H. Tomlinson. The innovation helped it surpass the sulfite process, another pulp-making process, in usage and catapulted it to the widespread popularity that it enjoys today.

The kraft process begins with presteaming common wood chips. This involves collecting wood chips that are 12–25 millimeters (0.47–0.98 inches) in length and 2–10 mm (0.079–0.39 in) in width, and wetting them before heating with steam. This causes cavities within the wood chips to be filled with both air and moisture.

After this, the wood chips are impregnated with white and weak black liquor by heating up to 100 °C (212 °F). During this process, liquor penetrates the capillary structure of the wood chips, and saturates them homogeneously throughout.

White liquor, so-named because of its white opaque color, is a strongly alkaline, aqueous solution of sodium sulfide (Na2S), sodium hydroxide (NaOH), sodium carbonate (Na2CO3), sodium sulfate (Na2SO4), sodium thiosulfate (Na2S2O3), sodium chloride (NaCl), calcium carbonate (CaCO3) and water. However, only the first two (and to a lesser extent, the third) compounds actually contribute to the breakage of extractives–cellulose fiber bonds; the other components of white liquor are considered to be chemically inert.

Black liquor, on the other hand, is simply the residue created from the consumption of white liquor during the previous batches of the kraft process. Black liquor is thus a mixture of woodchip residues in white liquor. Aside from being used as a digesting agent during the early stages of the kraft process, black liquor is also combusted in the recovery burner in order to recover useful compounds from the black liquor and generate extra power for the pulp mill.

The rationale for recycling spent white liquor is pretty simple: economy. Not all of the active components of white liquor are spent up during digestion, and disposing them right after just one use is fiscally imprudent and environmentally irresponsible as well. Black liquor is, as its name suggests, a viscous, aqueous, black liquid that turns water to dark caramel upon contamination, and is very toxic to aquatic life. About 7 tons of black liquor is produced for every 1 ton of pulp manufactured under the kraft process. Recycling black liquor (i.e. spent-up white liquor) greatly reduces the amount of it that goes into our ecosystem.

During digestion, the wood chip–liquor mixture is placed into a highly pressurized vat for several hours at temperatures ranging from 170 to 176 °C (338 to 349 °F). The liquor mixture act to digest the pulpwood into paper pulp by removing lignin (a complex chemical compound found in the wood’s secondary cell wall), hemicellulose (a polymer also found in the cell wall) and other extractives. This is done in order the pulpwood cellulose fibers that are used as ingredient in making paper. Reactions between nucleophilic bisulfide (HS-) or sulfide (S2-) and the woodchip components underpin this step of the kraft process.

Digestion produces a solid pulp known as a “brown stock.” This product is then collected and washed to rid it off the inorganic compounds that came from liquor impregnation. Atmospheric pressure is reduced in the containers in order to let steam arise from the brown stock, and cool them down. Efficiently designed pulp mills recycle this steam to turbines in order to generate electrical power.

Afterwards, the pulp is passed through sieves in order to remove dirt and other unwanted contaminants; and then washed again for several times in order to produce a final product that is clean pulp. Finally, the pulp is bleached to give it paper’s familiar white color. Several chemicals may be added after this process in order to improve the quality of the pulp.

The kraft process produces a lot of by-products, the most notable of them being crude sulfate turpentine and tall oil soap. Both of which can be used as ingredients of a wide range of retail and industrial products, including lubricants, soaps, solvents, inks, binders and many more. Effluent produced by kraft-process pulp mills are extremely detrimental to the environment and should be recycled whenever possible.