POC-SCALE TESTING OF A DRY TRIBOELECTROSTATIC SEPARATOR FOR FINE COAL CLEANING

PDF Version Also Available for Download.

Description

Numerous advanced coal cleaning processes have been developed in recent years that are capable of substantially reducing both ash- and sulfur-forming minerals from coal. However, most of the processes involve fine grinding and use water as the cleaning medium; therefore, the clean coal products must be dewatered before they can be transported and burned. Unfortunately, dewatering fine coal is costly, which makes it difficult to deploy advanced coal cleaning processes for commercial applications. As a means of avoiding problems associated with the fine coal dewatering, the National Energy Technology Laboratory (NETL) developed a dry coal cleaning process in which mineral ... continued below

Physical Description

235 pages

Creation Information

Yoon, R.H.; Luttrell, G.H.; Yan, E.S. & Walters, A.D. April 30, 2001.

Context

This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. More information about this report can be viewed below.

Who

People and organizations associated with either the creation of this report or its content.

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this report. Follow the links below to find similar items on the Digital Library.

Description

Numerous advanced coal cleaning processes have been developed in recent years that are capable of substantially reducing both ash- and sulfur-forming minerals from coal. However, most of the processes involve fine grinding and use water as the cleaning medium; therefore, the clean coal products must be dewatered before they can be transported and burned. Unfortunately, dewatering fine coal is costly, which makes it difficult to deploy advanced coal cleaning processes for commercial applications. As a means of avoiding problems associated with the fine coal dewatering, the National Energy Technology Laboratory (NETL) developed a dry coal cleaning process in which mineral matter is separated from coal without using water. In this process, pulverized coal is subjected to triboelectrification before being placed in an electric field for electrostatic separation. The triboelectrification is accomplished by passing a pulverized coal through an in-line mixer made of copper. Copper has a work function that lies between that of carbonaceous material (coal) and mineral matter. Thus, coal particles impinging on the copper wall lose electrons to the metal thereby acquiring positive charges, while mineral matter impinging on the wall gain electrons to acquire negative charges. The charged particles then pass through an electric field where they are separated according to their charges into two or more products depending on the configuration of the separator. The results obtained at NETL showed that it is capable of removing more than 90% of the pyritic sulfur and 70% of the ash-forming minerals from a number of eastern U.S. coals. However, the BTU recoveries were less than desirable. The laboratory-scale batch triboelectrostatic separator (TES) used by NETL relied on adhering charged particles on parallel electrode surfaces and scraping them off. Therefore, its throughput will be proportional to the electrode surface area. If this laboratory device is scaled-up as is, it would suffer from low throughput capacities and high maintenance requirements. In general, surface area-based separators (e.g., shaking tables, magnetic drum separator, electrodynamic separator, etc.) have lower throughput capacities than volume-based separators (e.g., flotation cell, dense-medium bath, cyclones, etc.) by an order of magnitude. Furthermore, the electrodes of the laboratory unit need to be cleaned frequently, creating a high maintenance requirement if it is scaled-up to a commercial unit. The bench-scale continuous TES unit developed at NETL, on the other hand, separates positively and negatively charged particles by splitting the gaseous stream containing these particles in an electric field by means of a flow splitter, so that the oppositely charged particles can be directed into different compartments. This device is fundamentally different from the laboratory unit in that the former is a surface area-based separator, while the latter is a volume-based separator. The bench-scale unit is referred to as an entrained flow separator by the in-house researchers at NETL. Thus, the entrained flow TES unit is a significant improvement over the laboratory unit with regard to throughput capacity. In the present work, the entrained flow separator concept will be utilized for developing a proof-of concept (POC) separator that can be scaled-up to commercial size units. To accomplish this, it is necessary to develop a bench-scale separator that can achieve high Btu recoveries while maintaining the high degree of separation efficiencies. It is the objective of the present investigation to develop an efficient separator by studying the mechanisms of triboelectrification and investigating better ways of separating the charged particles. An important criterion for developing efficient separators is that they not only provide high separation efficiencies but also have high throughput capacities, which are essential ingredients for successful commercialization.

Physical Description

235 pages

Notes

OSTI as DE00824952

Source

  • Other Information: PBD: 30 Apr 2001

Language

Item Type

Identifier

Unique identifying numbers for this report in the Digital Library or other systems.

  • Report No.: NONE
  • Grant Number: AC22-95PC95151
  • DOI: 10.2172/824952 | External Link
  • Office of Scientific & Technical Information Report Number: 824952
  • Archival Resource Key: ark:/67531/metadc783641

Collections

This report is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

What responsibilities do I have when using this report?

When

Dates and time periods associated with this report.

Creation Date

  • April 30, 2001

Added to The UNT Digital Library

  • Dec. 3, 2015, 9:30 a.m.

Description Last Updated

  • Jan. 3, 2017, 4:53 p.m.

Usage Statistics

When was this report last used?

Yesterday: 0
Past 30 days: 1
Total Uses: 8

Interact With This Report

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

Citations, Rights, Re-Use

Yoon, R.H.; Luttrell, G.H.; Yan, E.S. & Walters, A.D. POC-SCALE TESTING OF A DRY TRIBOELECTROSTATIC SEPARATOR FOR FINE COAL CLEANING, report, April 30, 2001; United States. (digital.library.unt.edu/ark:/67531/metadc783641/: accessed April 19, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.