Hanson, Jim

Jim is a professional engineer with a BSME from UMass-Amherst. He is a member of the Residual and Biosolids solids separation subcommittee. He is also...

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About Hanson, Jim

Jim is a professional engineer with a BSME from UMass-Amherst. He is a member of the Residual and Biosolids solids separation subcommittee. He is also an author and reviewer of Fact Sheets on WEF’s AccessWater.org platform. He’s been working at GEA Westfalia Separator centrifuges for 32 years.

Hanson, Jim

Titles from this speaker

Description: Affinity Laws for Decanter Centrifuges: Impacts of G force on dewatering centrifuge...

Affinity Laws for Decanter Centrifuges: Impacts of G force on dewatering centrifuge capacity and performance. An explanation of the G-volume scaling methodology.

Abstract

Introduction Affinity Laws for pumps and fans are commonly known but why aren't they commonly known for decanter centrifuges? Dewatering performance has a large impact on overall wastewater treatment operations and understanding how modern decanter centrifuge technology has evolved is critical to selecting the correctly sized equipment. The optimized selection of a decanter centrifuge and its performance plays an important role in the cost of returned solids (solids recovery) and the cost of disposal (dryness of solids). The scaling methodology (Affinity Laws for Decanter Centrifuges) of capacity and performance becomes a crucial activity. The inner diameter of the bowl has historically been one of the main criteria for comparing decanter centrifuges. However, this approach has not been sufficiently accurate for the prediction of capacity or performance. The holding volume, geometry, and operating speeds all need to be compared. For this purpose, GEA has developed and validated a theoretical model by performing side-by-side field trials. The validation of the G x Volume affinity law (See Figure 1) demonstrates that G force combined with volume are reliable criteria for the scaling of capacity and performance of decanter centrifuges for dewatering in wastewater treatment plants. Hypotheses 1. Comparing geometrically similar decanter centrifuges with an equivalent volume with a higher G force would result in either a higher cake dryness or a greater capacity. See figure 2 2. Comparing decanters with a different bowl diameter but with the same G volume, the performance and capacity would be the same. See figure 3 Methodology 1. Side-by-side operation with two equivalent bowl diameter decanter centrifuges with different G-volume was performed at WWTP Langenberg, Germany, keeping other parameters such as sludge characteristics, concentration of infeed sludge and solids recovery identical. 2. Side-by-side operation with two different bowl diameter decanter centrifuges with an equivalent G volume was performed at WWTP Oldenburg, Germany, keeping other parameters like sludge characteristics, concentration of infeed sludge and solids recovery identical. 3. In both trials, the services of KBKopp (Dr. Julia Kopp) were utilized to determine the maximum sludge dewaterability. See figure 4 for photos of the test equipment and site Results The research establishes that centrifuges with an equivalent bowl geometry, but having different G volume owing to rotational speeds, will have an equivalent capacity at the same performance level or a different performance at the same capacity. The capacity and performance is directly proportional to the G volume difference, and only indirectly related to the bowl diameter. See figures 5, 6, 7 Implications The study brings forward 'G x Volume' as reliable criteria for scaling and selection of decanter centrifuges in wastewater treatment plant design and also brings a paradigm shift from conventional wisdom of bowl diameter as the comparative driver. The research helps in selection of centrifuges that get higher capacity per square meter space or significant reduction in cost of operation (disposal and polymer consumption) per cubic meter of sludge handled. In either of the cases, 'G x Volume' based selection drives towards optimized scaling for reduction in CO2 footprint and an efficient circular economy. The Future The development and use of Affinity Laws for Decanter Centrifuges is on-going and is expected to result in more economically efficient and environmentally friendly operations.

This paper was presented at the WEF/IWA Residuals and Biosolids Conference, May 16-19, 2023.

SpeakerHanson, Jim

Presentation time

14:30:00

15:00:00

Session time

13:30:00

16:45:00

SessionSession 08: Dewatering and Polymer Optimization

Session number08

Session locationCharlotte Convention Center, Charlotte, North Carolina, USA

TopicThickening & Dewatering

Author(s)

J. Hanson

Author(s)J. Hanson1, 2, 3, 4,

Author affiliation(s)GEA Westfalia Separator Division1

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2023

DOI10.2175/193864718825158848

Volume / Issue

Content sourceResiduals and Biosolids

Word count23

Description: Enhanced Cake Dryness and Granulation via Efficient Energy Evaporation of Surface...

Enhanced Cake Dryness and Granulation via Efficient Energy Evaporation of Surface Moisture using Combined Centrifugal Dewatering and Spray Drying Techniques

Abstract

A decanter centrifuge discharges dewatered cake solids at a speed in the range of 100 miles per hour. In 1992, a theory was developed whereby the particles are extremely fine (less than 1 mm) and discreet as they are discharged and that if these small particles were allowed to fly freely additional surface moisture would be evaporated. The theory was tested over a period of 20+ years and resulted in a technology combining a decanter centrifuge with a spray drying system. This paper presents the theory and results of full scale testing conducted at locations in Germany, Denmark, China, and the UK. The initial tests utilized a modified decanter centrifuge with an oversized solids collection chamber. Traditional decanter centrifuges collect solids in a compact chamber to minimize space. However as the particles are thrown against the walls of the chamber, they collect and agglomerate into large nuggets or balls. These balls have a relatively small surface to volume ratio and don't allow for efficient evaporation of moisture in downstream processes. One can easily observe this effect on a hot, dry day as surface moisture evaporates from a cake pile, but the moisture remains below the crust. (photo) After the initial tests proved the particle size theory, additional tests were conducted using high speed cameras to document how the particles move within the chamber. (photo) Ultimately, full scale units were built and side-by-side tests conducted. (Photo from Randers) The tests included sampling of feed, cake, centrate and polymer on a traditional decanter centrifuge (GEA model CF4000) and with a GEA granulator 4000. The tests were conducted with only ambient temperature air flow, as well as, progressively warmer air (60 - 130 deg C). Charts and graphics to be provided. The relationship of energy input and moisture evaporated proved to be related as one would expect. Sludge dewaterability analysis uses sludge drying curves to determine which type of moisture a traditional mechanical dewatering device can remove. This same type of analysis shows the amount of energy required to evaporate the surface water. (photo of types of water A, B, C and D). Another unexpected result was the impact on fecal coliform regrowth. In addition to meeting the expected dryness and capacity requirements the system proved to provide solids meeting the British Assurance Scheme (BAS) in regards to e-coli requirements during storage. Hundreds of successful samples were analyzed and documented the rate of regrowth was within the limits. As disposal costs increase due to environmental concerns such as PFAS and as sustainable practices continue to advance, the efficient re-use of energy can be applied to the air chamber. Waste heat sources from digester gas, sludge heat transfer, or other means can provide the energy. The paper details the economics of using the waste heat in comparison to hauling or the cost to use additional energy sources. (charts). Re-using the energy of the flying particle and blowing hot air onto the surface before it impacts the wall, dissipates its energy, and grows in size is the basis of the technology advancement. The paper and presentation steps the reader through the process. Interested readers and attendees will be those involved in dewatering, dewatering optimization, drying, sludge hauling, fecal coliform regrowth, PFAS, beneficial re-use, energy efficiency and sustainability.

This paper was presented at the WEF Residuals and Biosolids Conference in Columbus, Ohio, May 24-27, 2022.

SpeakerHanson, Jim

Presentation time

9:00:00

9:30:00

Session time

8:30:00

10:00:00

Session number16

Session locationGreater Columbus Convention Center, Columbus, Ohio

TopicDewatering Optimization, Net Zero Energy, Thermal drying

Author(s)

J. Hanson

Author(s)J. Hanson1

Author affiliation(s)GEA Mechanical Equipment US; Inc.; 1

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May, 2022

DOI10.2175/193864718825158392

Volume / Issue

Content sourceResiduals and Biosolids

Word count21

Base text size -

Hanson, Jim

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