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Caldo Consultants

Caldo Consultants specialise in advising clients about all matters concerning the processing of hot gases.

The challenges of operating at high temperatures are often under-estimated by engineers who are new to the field. It is not just a question of using different materials of construction, there are many ways in which processes do not behave as anticipated and Caldo has had to deal with most of them.

Caldo Engineering Ltd was started in 1991 by Chris Withers, a chemical engineer. The company supplied ceramic filters and related hot gas treatment equipment worldwide for over 25 years until it was wound up in late 2016 due to a shortage of orders for equipment and components.

Caldo Consultants Ltd is the successor company that responds to all process, technical and marketing enquiries. This website outlines the services we offer, reviews several technical issues of interest and presents some literature items for download.


What We Can Do

Process Design

The ability to filter at high temperatures often creates new options for the design of a process that is more straightforward, cheaper and more efficient than previously. However, calculation of the process flows is more complicated when higher temperatures are involved and Caldo has extensive experience in modelling such processes to allow equipment to be sized correctly. In particular, Caldo has extensive experience with incineration and gasification processes.

Problem Solving

Sometimes hot gas treatment equipment does not work as expected and it is not straightforward to identify the main cause of the problem. In these cases it can be useful to review the situation with someone expert in the field but not connected with the particular problem. We will be able to help either to identify the cause of the problem or, failing that, to confirm that all the appropriate steps have been taken.

We have considerable experience of commissioning equipment, especially equipment for new or changed processes. Often specialist help for a short period can help overcome particular problems during start-up by providing skills that are only rarely required by an organisation.

Help with Purchasing

If you are looking for equipment for a hot gas treatment process we can help you define your requirements. We can prepare a process specification and/or an equipment specification to provide the basis for a request for quotation (RFQ), also known as an invitation to tender. These inputs will enable us to construct an accurate and detailed  RFQ.

This is important because a tight definition of your requirements will produce responses that are more similar to each other. This will enable you to choose your preferred supplier on the basis of of price and service rather than having to judge the merits of competing technologies.

Also we can help evaluate the quotations that you receive. This is especially useful when you have received a number of alternative technical solutions to your statement of needs and are looking to identify the most cost-effective approach.

Sourcing Spares and Components

Caldo Engineering built hot gas filtration equipment for 25 years and is well acquainted with the suppliers of the specialised components such as filter elements, pulse cleaning systems and so on. If you need advice on where to go for spares or components contact us with your requirements and we will refer you to reliable suppliers.






Caldo has been involved with hot gas filters and related equipment since 1991

The SEMs (scanning electron micrographs) above show two images of the same dust, one at 10x the magnification of the other. On the picture with lower magnification the particles look to be mainly >5 microns in size, which would make the dust relatively straightforward to filter. However the more magnified image shows these particles as agglomerates of much smaller spherules, typically <1 microns in size and some of which may have condensed from the vapour phase. The agglomeration probably occurred mainly during and after the filtration process, so the dust pre-filtration was predominantly sub-micron which makes for a much more difficult duty.

Email Caldo at caldo@caldo.com; phone on +44 (0)1562 743346: fax to +44 (0)1562 544217