Steam Flow Surveys in Côte d'Voire

Abstract

A french company contacted our office in Paris to undertake steam surveys at two Cocoa Production Facilities at Abidjan and San Pedro in Côte d'Ivoire. 5 boilers were tested by one of our field engineers over 4 days to provide definitive demand profiles and maximum usage data to specify and design new replacement biomass boilers. Of course, he was well rewarded with fresh mango and pineapples every day! He had to work hard to get any chocolate though!

Equipment Used

The Panametrics PT878GC Portable Flow Meter with specialist high-temperature transducers and plenty of bottled water!!!!

Background

A world-reknowned cocao production company have two main facilities in Côte d’Ivoire producing over 200 tonnes of processed cocoa for export every day. However, most of the boilers are approaching 25 years old, some of which use natural gas. Several boilers actually use the cocao shells to fire the boiler – well it makes sense; very sustainable. However, as you would expect the rising demand for chocolate means more cocao and yes more steam, but from more efficient boilers. This is where RS Hydro comes in.

Abidjan Steam Survey

Two boilers were measured with 3 and 4" outlets, producing up to 5 tonnes per hour at 10 bar. There were no flow meters inline and nobody knew where the steam was going or indeed how much. There were simply many reports that different parts of the production facility were not getting enough steam flow. One of our field engineers installed two PT878GC clamp on gas flow meters on the outlet of each boiler. Production load was held back inorder to maximise the peak demand for steam thus giving the manufacturer the absolute maximum steam demand. However, we also logged all of the steam flow data at 10 second intervals to understand how the demand varied over time and according to which process. It is hoped that one larger and more efficient boiler will not only produce more steam but have lower running costs.

San Pedro Steam Survey

The San Pedro facility produces three times more cocao than the Abidjan facility but some 300 miles away. With three ageing boilers on tap (two biomass and one gas), the same demand profiles needed to be captured as with the first facility. The testing proved even more useful than the local engineers had hoped for…essentially certain areas of the factory were using far less than they expected and others clearly more.

Three boilers supplied 2no 125mm CS (Carbon Steel) Sch40 pipes and 1no 100mm CS Sch40 pipe. Pressures varied from 9 to 15 bar depending on demand. At times demand exceeded the output of the boilers which inevitably led to a significant pressure drop and mass flow. The steam velocities exceeded 30m/sec regularly and down to zero but it is these peaks and durations of the specific flows that are critical to the design of the new replacement boilers. The PT878GC flow meters are battery powered (with a plug in charger available for continuity) and were able to record 12 flow and diagnostic parameters all day at 10 second intervals without any external power.

PT878GC for Steam Flow Calculations

The PT878GC can measure mass flow in two ways: either by (i) using the integral steam tables for temperature or pressure; or (ii) by connecting a live 4-20mA input into the flowmeter so that changes in pressure can compensate the steam density input accordingly. In this instance the steam pressure was relatively stable and as such a static input was used but from time to time was updated manually should the pressure change.

What next?

The data was subsequently compiled into a report with data, photos and diagnostic data to provide an overview of the steam demand for each boiler. The boiler manufacturer was then able to design an optimally sized efficient boiler system. The costs of acquiring good data to provide a sound solution are neglible.

Spare a thought…

RS Hydro are one of GE Panametrics largest distributors worldwide and provide a full range of support services across the globe. Our unique experiences gets us in to some sticky situations…literally, working above a boiler producing 10,000kgs of steam per hour at 200°C. Then add the overalls, gloves, glasses, a hair net (yes a hair net) and hard hat and then it is akin to working in a pressure cooker! Sounds like we are talking our selves out of any future jobs…not at all, just proves we have what it takes to do a good job, anytime anywhere! The engineer managed to lose a few kgs too! Or perhaps it was the overhelming smell of chocolate that kept him going…?

How much did the survey cost?

That would be telling but when a boiler can well exceed £500,000 the costs of designing it wrong could be catastrophic.That is just for one boiler…we measured 6! In this instance a significant part of the cost was actually just getting an engineer to a remote part of Africa.