Part 2 CCT Overview
Multi-purpose Coal Utilization Technologies (De-ashing and Reforming Technologies)

4D2. Low-rank Coal Upgrading Technology (UBC Process)Research and development: Japan Coal Energy Center; Kobe Steel, Ltd.
Project type: Joint research of technologies applicable in coal-producing countries
Period: 2001-2004 (4 years)

Technology overview

1. Background and process overview
Brown and sub-bituminous coal, accounting for about 50% ofupgrading technology (UBC process) has been developed tocoal reserves, are referred to as "low-rank coal." Applications areenable the effective use of such low-rank coal. This process, anlimited due to its low heating value and spontaneous

adaptation of the slurry dewatering technique in the brown coal

combustibility. Unlike bituminous coal, however, much of the low-liquefaction

rank coal has low sulfur/ash content. Therefore, if it could be

preparation/dewatering,

efficiently upgraded and converted into high-grade, high-heating

recovery, and 3) briquetting (Fig. 1).

process,

consists2)

of3

solid-liquidstages:1)

slurryseparation/solvent

coal, it would greatly contribute not only to a stable energy supply
but also to environmental conservation. A low-rank coal

Raw coalAsphalt

Slurry dewatering

Solid-liquid separation
Decanter

Evaporator(140 C/350kPa)
O

Slurry preparation
Solvent recovery

Wastewater

Recycle solvent

Upgraded brown coal (UBC)

Upgraded brown coal briquette

Fig. 1 UBC process for upgrading low-rank coal

During the slurry preparation/dewatering stage, after theof heavy oil functions to prevent the re-adsorption of moisture andpulverized high-moisture low-rank coal has been mixed withaccumulation of the heat of wetting (Fig. 2).

circulating oil (normally light petroleum oil), and then laced withheavy oil (such as asphalt), and heated in a shell and tube-type

Before dewatering

After dewatering

evaporator, moisture is recovered as water vapor. This watervapor is sent to the shell side of the evaporator, after beingpressurized by a compressor, to use the waste-heat as aheating source, providing substantial energy savings during thedewatering stage. Low-rank coal also contains numerous poresand the moisture within them is removed in the course ofCapillary water

evaporation. During that time, laced heavy oil is effectively

Surface water

adsorbed into the surface of the pores, thus preventing
spontaneous combustion. Moreover, the water-repellant nature

Selective adsorption of asphalt
into pores

Asphalt

Fig. 2 Fundamentals of low-rank coal upgrading77

Clean Coal Technologies in JapanAt the stage of solid-liquid separation/solvent recovery, after mostof the recycled solvent is recovered from the dewatered slurry by adecanter, the recycled solvent remaining in the pores of theupgraded coal is recovered by a tubular steam dryer.
Since the upgraded coal produced in the UBC process is still in a
powder form, for transportation to non-local customers it is formed
into briquettes. Using a double roll briquetter, the upgraded coalcan easily be briquetted without the use of a binder. Photo 1 showsa picture of upgraded-coal briquettes.

Photo 1 Briquetted UBC

2. Development target
1) Upgrading cost
Assuming that the FOB price of bituminous coal with a heating

4. Future assignments and prospective commercialization

value of 6,500 kcal/kg is $20/ton, that of 4,500 kcal/kg sub-The Japan Coal Energy Center and the Research andbituminous coal should be around $13/ton in calorific equivalents.

Development Agency of the Ministry of Energy and Mineral

When upgrading this coal to a calorific value of 6,500 kcal/kg, theResources served as the driving force for building a 5 ton/day (ontreatment cost guideline should be set at $7/ton. However, taking

a raw coal basis) UBC process demonstration plant in Cirebon,

into account the advantages of low-rank coal, such as its low ash

Java Barat province, Indonesia. Operation of the demonstration

content, the R&D team has set a development target to keepplant was completed in 2005 (Photo 2).

upgrading costs equal to or less than $10/ton.

In low-rank coal producing countries, including Indonesia, coal2) Thermal efficiency in the upgrading process

producers are highly interested in the UBC process and are

The upgrading of low-rank coal needs to provide a higher thermal

hoping for early commercialization.

efficiency than that obtained from the direct firing of the same
low-rank coal when considering the entire process involved, fromUBC production to power generation. Thus, the minimum thermal
efficiency target for the upgrading process has been set to 90%.

3. Development progress and results
The heating value of upgraded coal, though it varies depending
upon the characteristics of the coal, has been improved to around
6,500kcal/kg, and its spontaneous combustion problem has also
been successfully suppressed. It has also been confirmed thatbriquetted upgraded-coal is similar to normal bituminous coalwhen it comes to ease-of-handling and re-crushing.
Furthermore, upgraded coal, when combusted, quite easily burns
itself out to leave almost no un-burned portion even under low-Photo 2 Low-rank coal
upgrading demonstration plant

NOx combustion conditions, exhibiting excellent characteristics
as a fuel.

Reference1) Toru Sugita et al., UBC (Upgraded Brown Coal) Process Development, Kobe Steel Engineering Reports, 53, 42, 2003.

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