Thursday, 27 September 2012

What Engineers Know and How they Know It

W.G. Vincenti was an engineering researcher who wrote a book called "What Engineers Know and How they Know It", which I am trying to get my colleagues at the University to read, to understand how engineering research and engineering practice should fit together.

Vincenti's basic idea is that engineering is not applied science - engineering has six categories of knowledge of which the last five are proper subjects for engineering research, as follows:

1.Fundamental Design Concepts

These are not scientific fundamentals, but instead the design engineer's axioms - a common idea of what the thing being designed is for, its operating principle, and its normal configuration.

2.Criteria and Specifications

Engineers may design artefacts to meet a need defined by others in non-technical terms, but in order to do so they need to transform the general, qualitative specification into concrete, quantifiable performance characteristics.

3.Theoretical tools

The theoretical tools of the engineer may be based in mathematics, science, or be peculiar to engineering. They provide ways of thinking about and analysing design problems.

3a. Mathematical Methods and Theories

The mathematical tools least peculiar to the engineer may be based in pure mathematics, or sciences, but they have been simplified for application to a particular situation by intoducing a set of approximations and assumptions which apply to only that specific set of circumstances. More particular still are the phenomenological theories which practitioners share about things too complex for scientific analysis, even if they have little scientific standing. At the far end of the spectrum are commonly held approaches to design of specific systems, used only because they seem to work, and no better method is known.

3b. Intellectual Concepts

Engineers are less like philosophers than they are like scientists. They are not fussy about where they get their ways of thinking about a design problem from - anything which works is good.

4.Quantitative data

Engineers need physical data to design things. They need descriptive knowledge, of how things are. They need prescriptive knowledge, of how things should be to ensure that the designed item meets the specified need. 

5.Practical Considerations

One can have perfect knowledge in all previous categories and still be unable to design an artefact that works. One also needs know-how, usually obtained from long practice in the profession, and interaction with those who produce, commission and operate the artefact.
 
6. Design Instrumentalities

Or less opaquely, structured procedures for going about the design of an artefact, ways of thinking about design problems, and judgemental skills. Some of these can be taught directly, but professional competence in these areas comes only from practice.

Vincenti then differentiates between seven ways in which engineering knowledge is generated (I know, he clearly had a lot of time on his hands. I am going somewhere with this....)

1. Transfer from science
2. Invention
3. Theoretical engineering research
4. Experimental engineering research
5. Design practice
6. Production
7. Direct trial

He draws the following table to illustrate the interaction between knowledge types and knowledge generating activities:

Table 7.1 Summary of Knowledge Categories and Generating Activities
















So engineering research can generate new engineering knowledge in all categories other than practical considerations. Researchers know about, practitioners know how. This is where I come in.

Sunday, 16 September 2012

Home Again

Back home after another successful course in the Gulf, this time on the use of membranes for water treatment in Qatar.

Both SCWO (Supercritical Water Oxidation) projects seem to be progressing well, undertook a site visit just before I went away for the UK one, and the European one looks likely to result in a treatability trial at least. I might produce a course on the technology if it looks viable/practical.

We are having a few problems with the Indian restaurant job, where extremely high levels of both grease and powerful cleaning agents are putting very high loads on the plant. We have recommended they use only agents with the EU Eco-label, as salesmen for cleaning products seem to be making slightly vague but nevertheless convincing green claims to our client. One to watch out for is: "Biodegradable to European Union definition of the term"- this is a pretty low standard, as I said in my correspondence with the consultants who employed me (acronyms explained below):

The EU standard for biodegradability of surfactants is >60% over 28 days HRT*, though this manufacturer claim that some of their products achieve >95% over 28 days.

This standard appears to be about biodegradability in the wider environment, rather than in the few hours of HRT in an ETP*. If we were looking to improve FOG* loss in the OWS*, we would need 95%+ removal in an hour or two.

Their degreasing products are mostly strongly alkaline mixtures of petrochemical based surfactants. They look to me to be pretty much standard heavy duty janitorial / industrial cleaners, similar to beer line cleaners.

I see no reference in their website or literature of the "septic tank friendliness" which their salesman claimed. There are many vaguely green claims made, especially by salesmen, so to make things easy for the client,  products in compliance with the requirements of the EU Ecolabel would be my desirable minimum standard. (A quick check of a couple of the salesman's products shows that their products do not all meet this standard (Their sanitiser has R50 substances well above specified limit)) Even this standard does not guarantee suitability, but it would improve matters.   

The products most likely to be causing the problems with FOG passing the  OWS, and to be likely to have biocidal effects are as follows:

Beer line cleaners
Degreasers
Floor cleaners
Dishwasher detergents
Toilet cleaners
Drain maintenance products

All of these should be the least aggressive product possible, close to neutral pH, and using the most biodegradable surfactants possible. The EU Ecolabel would be a useful guide.

Use of the lowest possible concentration of cleaning products to give an acceptable degree of cleaning is recommended, as is following the recommendations of the BW guide sent earlier."

The client is responding to our requests, and hopefully plant performance (whose improvement has stalled short of the required standard) will once again start to improve.  

Acronyms:
ETP= Effluent Treatment Plant
HRT = Hydraulic Residence Time
FOG = Fats, Oils and Greases
OWS = Oil Water Separator

And there's more - as well as bits and bobs of work for our long term repeat business clients (including something on foam suppression), we also have an order in the pipeline for treatment of a very interesting waste-water with unusually hazardous properties, and are starting the planning of a couple of courses in Oman and the Far East around the year end.

One more week of full-time consultancy before I'm back teaching at Nottingham. It's all about process design this year - I'm teaching it to all three years of the undergraduate course, and to most of the Masters' students too.  

Interesting to teach formally things you learned informally. First you have to figure out what you know and how you know it.

Monday, 3 September 2012

Supercritical Water Oxidation

We are looking at a couple of jobs involving use of SCWO for decontamination of industrial effluents, one full scale, and the other involving a bench scale trial. Interesting stuff.

We are also going to have a look at a water recycling job for a petrochemicals manufacturer whilst we are in the Middle East in a couple of weeks time giving a couple of training courses centring largely on the use of membranes in industrial effluent treatment.

The truck wash effluent job seems to be approaching the point at which we will be able to offer a recommendation, but it has been hard getting the bidders to offer enough real information to technically assess their bids.

We are having difficulties with the package plant recommissioning, as the client will not stop putting beer pump cleaner and other caustic based cleaning products down the drains. Things were progressing nicely until sufficient caustic was added to the plant to raise pH throughout to 9 for a sustained period. 

The plating plant effluent job came to nothing, looks like it was one of the many people who would like you to design a plant for them free of charge with the promise of payment down the line. We have too much paying work to be tempted to work for free.

Back at the Uni on 21st September, which doesn't mean I'll not be carrying on with Expertise work, but it will obviously reduce the amount I can do, whilst still doing justice to my students' needs.

This first summer break from full-time teaching seems to have worked well, I've been continuously busy, whilst still having time for a couple of short breaks.

Today's job - stop procrastinating with your blog and start planning out the mix of lectures, syndicate and individual exercises you are going to use on those courses in the Gulf....