Multiple Hearth Research Articles

Biosolids and Energy Evaluation at Post Point Treatment Plant

Biosolids and Energy Evaluation at Post Point Treatment PlantThe City of Bellingham (City) currently owns and operates the Post Point Wastewater Treatment Plant (Post Point Plant). At the Post Point Plant, the City currently processes its biosolids in two multiple hearth furnaces (MHFs). This approach of sludge incineration has proven to be a reliable technology for the City over the years, however, the age of the existing equipment and its capacity...Author(s)David L. ParryScott VandenburghLarry BatemanSourceProceedings of the Water Environment FederationSubjectSession 1: Planning & Permitting Biosolids ProjectsDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2011ISSN1938-6478SICI1938-6478(20110101)2011:4L.87;1-DOI10.2175/193864711802862905Volume / Issue2011 / 4Content sourceResiduals and Biosolids ConferenceFirst / last page(s)87 - 92Copyright2011Word count343Subject keywordsMultiple Hearth FurnaceFluidized Bed IncinerationDigestionCogenerationCHPCombinedHeat and PowerBiogasGasification

Feeding FOG to Thermal Oxidation Units It's All in the Presentation

Feeding FOG to Thermal Oxidation Units It's All in the PresentationThe Hampton Roads Sanitation District (HRSD) has developed a simple and effective system for recovering the energy value of the fat, oil and grease (FOG) waste receipts at its Williamsburg Treatment Plant (WTP). The solids and FOG production at this treatment plant are thermally oxidized by multiple hearth incineration, with the energy recovered in the form of reduced natural gas consumption. The...Author(s)Timothy G. SheaDavid CooleyPeter BurrowesSourceProceedings of the Water Environment FederationSubjectSession 17: Incineration and DryingDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2010ISSN1938-6478SICI1938-6478(20100101)2010:4L.1162;1-DOI10.2175/193864710802767362Volume / Issue2010 / 4Content sourceResiduals and Biosolids ConferenceFirst / last page(s)1162 - 117Copyright2010Word count174Subject keywordsFat-Oil-Grease (FOG)primary scumscum concentrationDCS (decanted concentrated scum)blending of DCS and dewatered sludge cakemultiple hearth incinerationcost-effectiveness

Pilot Plant Demonstration of Activated Carbon Injection With Baghouse Filter for Removal of Mercury From Multiple Hearth Sewage Sludge Incinerator Exhaust

Pilot Plant Demonstration of Activated Carbon Injection With Baghouse Filter for Removal of Mercury From Multiple Hearth Sewage Sludge Incinerator Exhaust

NEORSD Experiences the Power of Renewable Energy

NEORSD Experiences the Power of Renewable EnergyThe Northeast Ohio Regional Sewer District (NEORSD) is starting to replace four multiple hearth incinerators (MHIs) at its Southerly Wastewater Treatment Center (WWTC), located in Cuyahoga Heights, Ohio (Cleveland Metropolitan Area) with three new fluidized bed incinerators (FBIs). The plan is to replace the 46 year old MHIs with 3-100 dtpd capacity FBIs. Design work for this project, which...Author(s)James WelpLee MaultJim RowanMark WilsonLori StoneRobert DominakSourceProceedings of the Water Environment FederationSubjectSession 1: Renewable PowerDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2010ISSN1938-6478SICI1938-6478(20100101)2010:4L.13;1-DOI10.2175/193864710802767245Volume / Issue2010 / 4Content sourceResiduals and Biosolids ConferenceFirst / last page(s)13 - 22Copyright2010Word count274Subject keywordsEnergy efficiencybiosolids incinerationenergy recoverygreen energy production

Power Generation by Incineration: Fluid Bed or Multiple Hearth Incinerators?

Power Generation by Incineration: Fluid Bed or Multiple Hearth Incinerators?

NEORSD Experiences the Power of Renewable Energy

NEORSD Experiences the Power of Renewable EnergyThe Northeast Ohio Regional Sewer District (NEORSD) is starting to replace four multiple hearth incinerators (MHIs) at its Southerly Wastewater Treatment Center (WWTC), located in Cuyahoga Heights, Ohio (Cleveland Metropolitan Area) with three new fluidized bed incinerators (FBIs). The plan is to replace the 46 year old MHIs with 3-100 dtpd capacity FBIs. Design work for this project, which...Author(s)James WelpLee MaultJim RowanMark WilsonLori StoneRobert DominakSourceProceedings of the Water Environment FederationSubjectSession 1: Renewable PowerDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2010ISSN1938-6478SICI1938-6478(20100101)2010:4L.13;1-DOI10.2175/193864710802767245Volume / Issue2010 / 4Content sourceResiduals and Biosolids ConferenceFirst / last page(s)13 - 22Copyright2010Word count274Subject keywordsEnergy efficiencybiosolids incinerationenergy recoverygreen energy production

Residence time investigation of a multiple hearth kiln using mineral tracers

Kaolin is used in many applications (e.g. paint, plastic and rubber) due to its unique properties, including fine particle size, brightness and chemical inertness. Properties can be improved by calcination, heating the kaolin to high temperatures inducing physico-chemical transformations. If calcination time is excessive, kaolin becomes harder and abrasive, due to mullite formation. This is detrimental to product quality; causing processing problems and machinery damage. If calcination time is too short, the kaolin is not fully calcined, becoming highly reactive, an issue for pharmaceutical applications. By controlling the exposure time to high temperature, such negative effects are minimised. Multiple hearth calciners are often used for this transformation, but their operating conditions and configuration make it difficult to determine kaolin residence time. To improve product consistency, trials were performed to measure the residence time distribution of an industrial furnace used to calcine kaolin. Titania, TiO 2, and talc, Mg 3Si 4O 10(OH) 2, were used to individually dope the kaolin, Al 2Si 2O 5(OH) 4, and the concentration of these mineral tracers was detected using X-ray fluorescence. Talc was the preferred mineral tracer, with a mean residence time of 42 min under standard operating conditions, with a throughput of 5.3 tonnes h −1 of 0 wt.% moisture feed.

Replacement of the Multiple Hearth Furnaces by the Fluid Bed Furnaces - The R.L. Sutton WRF Experience

Replacement of the Multiple Hearth Furnaces by the Fluid Bed Furnaces - The R.L. Sutton WRF Experience

Performance of Instrumentation and Control Upgrades to Multiple Hearth Furnace in Anchorage, Alaska

Performance of Instrumentation and Control Upgrades to Multiple Hearth Furnace in Anchorage, Alaska

Replacement of a Multiple Hearth by a Fluid Bed Incinerator The Ypsilanti Sludge Disposal Case History

Replacement of a Multiple Hearth by a Fluid Bed Incinerator The Ypsilanti Sludge Disposal Case History

Upgrade of UBWPAD's Multiple Hearth Furnace Sludge Incinerators

Upgrade of UBWPAD's Multiple Hearth Furnace Sludge Incinerators

House Remains at the Netarts Sandspit Village, Oregon

Houses and households are a major focus of archaeological research on the Northwest Coast of North America. One of the few sites on the southern Northwest Coast to have multiple houses excavated is Netarts Sandspit Village (35-TI-1). Extensively excavated in the 1950s, few details have been available regarding the form of houses at the site and the chronology of their occupations.Reexamination of field notes,feature forms, and photographs from the 1950s excavations reveals that several rectangular wood plank structures built within pits were present at the site. Each was capable of housing several families, contained multiple hearths, and was associated with dense midden deposits. The houses may have had single pitched-roofs, a style commonly seen among Salish-speaking groups in Washington State and British Columbia. Recent excavation and radiocarbon dating demonstrate that the site was first occupied around A.D. 1300 and continued to be inhabited until the mid- to late 1700s. House placement appears to have been partially dictated by vegetation and dune formation. The houses were occupied for several centuries and represent substantial time, energy, and material investments for the families who occupied them.

Fenton peroxidation improves the drying performance of waste activated sludge

Advanced sludge treatment processes (AST) reduce the amount of sludge produced and improve the dewaterability, thus probably also affecting the heat transfer properties and the drying characteristics of the sludge. This paper studies the influence of the Fenton peroxidation on the thermal conductivity of the sludge. Results demonstrate that the Fenton's peroxidation positively influences the sludge cake consistency and hence enhances the mechanical dewaterability and the drying characteristics of the dewatered sludge. For the two sludges used in this study, i.e. obtained from the wastewater treatment plants (WWTP) of Tienen and Sint-Niklaas – the dry solids content of the mechanically dewatered sludge increased from 22.5% to 40.3% and from 18.7% to 35.2%, respectively. The effective thermal conductivity k e of the untreated and the peroxidized sludges is measured and used to determine the heat transfer coefficient h s. An average improvement for k e of 16.7% (Tienen) and 5.8% (Sint-Niklaas) was observed. Consequently the value of h s increased with 15.6% (Tienen) and 5.0% (Sint-Niklaas). This increased heat transfer coefficient in combination with the increased dewaterability has direct implications on the design of sludge dryers. A plate-to-plate calculation of a multiple hearth dryer illustrates that the number of plates required to dry the peroxidized sludge to 90% DS is less than half the number of plates needed to dry untreated sludge. This results in reduced dryer dimensions or a higher capacity for an existing dryer of given dimensions.

Processing of waste from pulp and paper plant

Production of sludge as waste in pulp and paper plants can be considered as one of the serious environmental problems that have to be solved. While landfilling is not a suitable solution from the environmental point of view, thermal treatment proved to be the most appropriate one. This paper describes an efficient way of processing sludge including waste-to-energy aspects. A thermal treatment unit with a capacity of more than 100 tons of wet sludge per day had been built in a large pulp and paper plant some years ago. This pulp and paper plant is located in a mining area. When built, this unit was quite modern. However, because of more and more sweeping environmental laws affecting the process industry, the unit needed a complete retrofit. The retrofit has been realised in three stages. A brief description of the unit for the thermal treatment of sludge is as follows: the waste sludge (after transport from a sludge storage system) is burnt in a multiple hearth incinerator with a fluidised-bed chamber. Then, the flue gas enters a secondary combustion chamber (afterburner chamber). During the first stage of retrofit, only a part of heat from flue gas was utilised for heat recovery (pre-heating air for combustion and fluidisation) and a contact cooler was involved in the unit. The second stage of retrofit can be characterised as a “waste-to-energy” one. The contact cooler was replaced by a system for preheating water for steam generation. Off-gas cleaning system consists of a filter for particulate removal and a three-stage scrubber system. (Several alternatives of retrofit were considered and simulated and the most promising one was selected.)

Reaction-kinetics of the vanadium roast process using steel slag as a secondary raw material

Secondary raw materials like steelworks slag or other vanadium bearing industry wastes like catalysts and oil burner ash can be used for the production of vanadium before their final disposal. Therefore, as in primary processing, alkaline roasting has to be carried out in a rotary kiln or multiple hearth furnace. This process transforms the vanadium, strongly embedded within the spinel mineral structure, into leachable vanadates. Mathematical modeling of this process for the establishment of simulation programs and for model based controller design requires accurate models of the chemical reaction kinetics. In this article a set of equations describing the reaction rate of the vanadium roast process and its derivation is presented. Validation showed good agreement between simulation and measurement data.

Fuzzy control of a multiple hearth furnace

The objective of process control in a reduction furnace is to optimise nickel recovery, while minimising fuel consumption and environmental contamination. This entails the exact control of temperature and gas composition in the furnace. Controlling the temperature of a multiple hearth furnace is a difficult task. Fast and extensive changes in operating conditions occur, complicated by non-linear and time-varying behaviour of the process and interaction between the different variables. Failing to solve the control problem with a normal PID controller led to development of a knowledge-based fuzzy controller, which keeps the temperature as close to the set profile as possible. Such controller is endowed with a set of 60 rule bases, which are dynamically switched depending on technological constraints and/or operating regions. The algorithm used for the resulting MIMO controller has a Mamdani-type inference system. This paper describes the implementation and the first field tests of a control algorithm, the results of which are very positive and encouraging.

Program to Upgrade Biosolids Processing Yields Unprecedented Reduction in Emissions in Hartford, Connecticut

Program to Upgrade Biosolids Processing Yields Unprecedented Reduction in Emissions in Hartford, ConnecticutIn 1997, The Metropolitan District embarked on a project to upgrade two multiple hearth incinerators. The 21 million, multi-task project has resulted in emission reductions of criteria pollutants from 64 to 99.9 percent.When the Connecticut General Assembly created The Metropolitan District (MDC, the District) in 1929, one of its most important missions was to provide a quality biosolids...Author(s)Sally K. NyrenSourceProceedings of the Water Environment FederationSubjectSession 14: Thermal Process II: Successful Projects & TechnologiesDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2002ISSN1938-6478SICI1938-6478(20020101)2002:3L.841;1-DOI10.2175/193864702785301934Volume / Issue2002 / 3Content sourceResiduals and Biosolids ConferenceFirst / last page(s)841 - 855Copyright2002Word count533

Replacement of a multiple hearth by a fluid bed incinerator the Greensboro case history

The incinerator at the T.Z. Osborne Plant in Greensboro, North Carolina burns sludge from its own waste water treatment plant and sludge pumped from the nearby North Buffalo plant. The two plants have a combined capacity of 36 million gallons per day of wastewater. Because of the age of and increasing high maintenance on the existing multiple hearth incinerator, and the need to increase treatment capacity, the Osborne plant concluded a study in 1992 evaluating its options for future municipal sewage sludge disposal. Options which were evaluated during the study included; (i) rehabilitation of the existing eight-year old multiple hearth unit; (ii) addition of a new multiple hearth; (iii) addition of a new fluid bed system; (iv) drying, composting, or land application. The chosen option, based on both economic and environmental considerations, was a new fluid bed system with a capacity of 2.55 tons per hour, approximately double that of the existing multiple hearth. Design of the new fluid bed system began in December 1994 and equipment delivery for the incineration system was begun in April 1995. Initial operation occurred in August 1996. Primary and secondary sludge, dewatered to 28% dry solids by centrifuge, is delivered by piston pumps to the twenty-foot freeboard ID incinerator. A shell and tube heat exchanger recuperates heat from the exhaust gas and preheats the combustion air to 1250°F, resulting in minimal auxiliary fuel use. The air pollution control device is a high-energy Tandem Nozzle® scrubber. Greensboro was the initial installation of this scrubber design on a fluid bed incinerator and its characteristics and performance are discussed. Ash is dewatered in an ash thickener/belt press system prior to disposal to landfill. The system includes a state of the art Programmable Logic Controller (PLC) system for computer control of the operation. The unit was commissioned in August 1996 and has been in continuous operation since that time except for a one week inspection and maintenance shutdown in February 1999. The plant operates 24 h/day, 7 days per week. The initial performance test showed the system to readily meet federal and state air emission standards. Particulate released was 0.002 grains per dry standard cubic foot, carbon monoxide was 22.5 parts per million volumetric (ppmv) and opacity was 0.4%. These results show a significant emission reduction with the fluid bed when compared to the multiple hearth. Annual tests conducted since then and continuous emission monitoring have shown the unit to be in consistent compliance. Since the fluid bed system became operational, the old multiple hearth system has been maintained on standby as a backup, but its use has not been required. Operational experience is discussed, the most interesting of which is the relatively trouble-free operation. The minor problems which occurred and their solutions are detailed. Also included is a comparison of operation and maintenance experience of the fluid bed and the multiple hearth. Current sludge disposal actual cost data are also provided including the average cost per ton of dry solids treated. The almost three years of operational experience to date has shown that the decision to install a new fluid bed system was the correct one on both an environmental and economic basis. It has provided benefits to all interested parties — the wastewater treatment plant, the regulators, the taxpayers, and the surrounding community.

Determination of the Overall Heat Transfer Coefficient in a Vacuum Pyrolysis Moving and Stirred Bed Reactor

A novel moving and stirred bed reactor with a high heat transfer capacity has been operated to achieve the thermal decomposition of used tyre particles under vacuum. The overall heat transfer coefficient determined in this reactor reaches 200–250 W m−2K−1, a value exceeding the levels obtained in conventional rotary kilns and multiple hearth furnaces. In order to design large scale stirred bed vacuum pyrolysis reactors, both experimental and theoretical studies were carried out to understand the heat transfer mechanism and to determine the heat transfer coefficient in the reactor as a function of the operating conditions. In this work, the heat transfer coefficients under different agitation speeds up to 22.5 rpm were measured. The heat transfer coefficient was found to increase with the agitation speed, proportionally to (1/tmix)1/2. A Schliinder's modified model was used to describe the correlation between the heat transfer coefficient and the operating conditions. Calculation of the partial heat transfer coefficients during the three pyrolysis evolution periods revealed the influence of the chemical reactions, the phase change and the feedstock thermal property variation on the overall heat transfer coefficient during the vacuum pyrolysis of tyre particles.

A Comparison of Fluid Bed and Multiple Hearth Biosolids Incineration

Incineration has been used as a disposal method for wastewater treatment biosolids for over sixty years. The first multiple hearth furnace for biosolids incineration was built in 1935 in Dearborn, MI. From that time through the late sixties, the multiple hearth was the thermal technique of choice for biosolids disposal. Today there are still some 150-175 aging multiple hearths in operation in North America. In the seventies, the fluid bed furnace became the preferred thermal technique for biosolids disposal, primarily due to tighter emission regulation and to increasing cost of auxiliary fuel. The first municipal fluid bed was installed in the USA at the Lynnwood, WA wastewater treatment plant in 1962. There have been over 125 fluid bed incinerators installed since then in North America.