Sagamu Brewery: quality refrigeration for quality beer

By Daniel Green of WSP Industrial

With the potential to be Africa’s largest brewery outside of South Africa, Sagamu Brewery in Nigeria required an impressive refrigeration solution to ensure that their cooling needs are met throughout the brewing process. 

WSP Sagamu P026 COVERThe recently completed Sagamu Brewery in Nigeria.

AB InBev’s new USD250-million brewery in Sagamu, Nigeria, was recently completed in record time, with WSP designing the refrigeration plant. This brewery was built with an initial capacity of 3.2MHL/annum, with a plan to expand the capacity to 6.4MHL/annum in future, making this brewery the largest brewery in Africa outside of South Africa.

Although WSP awarded the contract for the refrigeration installation in March 2017, the site installation only commenced in January 2018 due to delays on site. However, WSP, together with the local contractors, managed to make up for the builders’ delays and achieved the original programme’s first brew date of 15 May 2018.

This brewery was built with an initial capacity of 3.2MHL/annum, with a plan to expand the capacity to 6.4MHL/annum in future, making this brewery the largest brewery in Africa outside of South Africa.

Client brief

WSP conducted the detailed design of the system based on the concept design and load requirements issued by the consulting engineers, Alectia.

The refrigeration system required cooling to be supplied to three separate user circuits as listed below:

Refrigeration system Load
-4.5°C glycol chiller system 4 400kWR
+2°C glycol chiller system 3 450kWR
+8°C chilled water system 1 400kWR

The client specification called for a design that did not allow for ammonia to be present outside the plant room area. As a result, glycol was used as the secondary cooling medium and was chilled by means of ammonia thermosiphon type chillers in the plant room and reticulated to the various process users.

System description

The refrigeration areas consisted of the following main systems:

  • -4.5°C chiller system
  • +2°C chiller system
  • +8°C chiller system
  • Compressor plant
  • Condenser plant.

-4.5°C chiller system

The chiller comprised an ammonia accumulator vessel, which fed ammonia to two 2 200kWR thermosiphon plate heat exchangers (PHE), which cooled the glycol returned from the process users at -0.5°C to the required supply temperature of -4.5°C. The reticulation of the glycol through the system was done by three pump sets: one to pump through the chiller and two pump sets to pump the chilled glycol to the various process users such as the fermentation vessels and filtration chiller.

+2°C chiller system

The +2°C chiller system was made up of a cascade system consisting of three chillers in series, which cooled the glycol returned from the process users at +25°C to the required supply temperature of +2°C. The chiller stages were as follows:

Stage 1: +25°C to 18°C 900kWR
Stage 2: +18°C to 8°C 1 100kWR
Stage 3: +8°C to +2°C 1 450kWR

Each chiller consisted of single thermosiphon PHE fed from their own accumulator vessel. A single pump set was used to pump the glycol through the three chillers and to the process users. The first two stages were used to chill the bulk of the load at the higher coefficient of performance (COP), while the last stage was used to trim the remaining load. This allows for the system to run at the highest possible COP during Wort cooling.

+8°C chiller system

The chiller consisted of an ammonia accumulator vessel, which fed ammonia to a single 1 400kWR thermosiphon plate heat exchangers that cooled the water returned from the process users at 15°C to the required supply temperature of 8°C. A single pump set was used to pump the chilled water through the chiller and to the HVAC users.

Compressor plant

The compressor plant consisted of nine ammonia screw compressors (all Grasso models) as well as one small reciprocating compressor installed as a pump down compressor.

Each of the screw compressors was cooled by means of thermosiphon oil coolers, which were fed off a priority feed from the condensers. The screw compressor motors were all fitted with a variable speed drive which, together with the compressor unloading mechanism, maintained the suction pressure of their respective accumulator vessels.

The swing/backup compressor was installed to ensure that the plant does not loose capacity should one of the compressors fail or need to undergo maintenance.

Condenser plant

The condenser plant comprised four evaporative condensers from BAC, a liquid receiver, mechanical auto purger, and an automatic water dosing system. Each of the condensers’ four fans was fitted with variable speed drives, which were controlled by means of the plant’s condensing pressure to minimise the electrical usage of the plant.

Challenges

Like with most construction projects, the timeline for the build was extremely tight and was further affected by the civil delays on site. To limit the time required on site, the various refrigeration packages were pre-manufactured in South Africa by local contractors MRE Industrial Refrigeration and Charlson Pumps and then shipped as complete skid packages.

Due to various delays, the time allocated for commissioning was very limited and as a result, various parts of the system were only commissioned during the first brew process, putting a huge amount of pressure on the commissioning engineers to resolve problems with the system rapidly so as to not affect the beer quality.

But in the end, it all came together.

List of professionals

Owner   - AB InBev
Developer - AB InBev
Architect / Designer  - PPS Architects
Project manager   - Royal Haskoning DHV
     
Consulting engineer    
Electrical - WSP Group Africa
Mechanical - WSP Group Africa
Wet services - WSP Group Africa
Structural  - Aurecon
Refrigeration plant - Alectia
     
Contractors    
Main building - Vita Construction
HVAC&R - Emtech
MV Electrical  - WSP Group Africa
Refrigeration - WSP Group Africa
     
Suppliers     
NH3 compressors - GEA Africa
Chiller plate heat exchanger - GEA Africa
NH3 vessels - D&D Fabrication
Glycol pumps - Grundfoss
Condensers - BAC
NH3 valves - Hansen, Danfoss
Air purger - Hansen
Variable speed drives (VSD) - Danfoss
PLC - Siemens
Ammonia skid manufacture - MRE Industrial Refrigeration
Glycol skid manufacture - Charlson Pumps

* Photos by WSP



Click here to read the January/February 2018 issue of Cold Link Africa

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