Kashima-Kita Orimulsion Burning Boiler |
|
| 1. |
General
Orimulsion is a synthetic fuel mainly composed of natural asphalt (Orinoco oil)
richly buried on the basin of the River Orinoco in Venezuela, South America. To
emulsify this natural asphalt, approximately 30% water and a fine amount of surfactant
are added. This fuel has eliminated the problem of stiffness during storage and
haulage. As a result, it can be handled at room temperature.
In order to establish a technique for utilizing Orimulsion, we have conducted
a variety of fundamental tests since 1986, and grasped the fuel properties of
Orimulsion. In 1991, we modified Boiler No. 2 in Kashima-Kita Electric Power Corporation
into the first Orimulsion burning type boiler in Japan. Since that time, a total
of three boilers were modified into Orimulsion burning units. In 1999, we finished
Boiler No. 5, as a newly designed boiler exclusively burning Orimulsion. |
| 2. |
Fuel Characteristics of Orimulsion
Orimulsion has fluidity similar to that of Heavy Oil C, and can be handled at
room temperature. Table 1 compares Orimulsion with Heavy Oil C, in terms of their
respective properties. In comparison with Heavy Oil C, Orimulsion has the following
features: |
| |
| (1) |
At 30% part water, Orimulsion has a calorie of approximately 70% relative to Heavy Oil C. |
| (2) |
With high amounts of nitrogen and sulfur contained in the fuel, Orimulsion produces large amounts of NOx and SOx. |
| (3) |
In addition, Orimulsion requires consideration to be given to possible pyrogenic corrosion due to its high concentration of vanadium, as well as cryogenic corrosion. |
| (4) |
Having high amounts of ash and residual carbon contained in the fuel, Orimulsion produces a lot of ash in the exhaust gas. As such, Orimulsion requires consideration of possible ash adhesion onto the heat transfer surface. |
|
| Table 1 A Comparison of Fuel Properties |
| Measurement item |
Orimulsion |
Heavy Oil C |
| Density (15°C) |
1.013 |
0.931 |
| Nitrogen (%) |
0.54 |
0.22 |
| Sulfur (%) |
2.78 |
0.97 |
| Moisture (%) |
26.3 |
<0.1 |
High-Heating value (kJ/kg)
[kcal/kg]
|
29,830
[7,125] |
43,680
[10,400] |
| Ash (%) |
0.07 |
0.01 |
| Residual Carbon (%) |
11.2 |
8.0 |
| V (ppm) |
394 |
50 or less |
| Na (ppm) |
9 |
- |
| Mg (ppm) |
26 |
- |
|
3. Features of the Exclusive Orimulsion Burning Boiler
Table 2 shows the principal specifications of Boiler No. 5 in Kashima-Kita Electric
Power Corporation.
It has been known that the Orimulsion burning boiler has both firing furnace and
convention heat transfer surface more seriously corrosive than the C-heavy oil
burning boiler. The heat transfer arrangement, therefore, has been designed so
that the boiler and auxiliary equipment can operate normally irrespective of fluctuations
during operation, while predicting the progress of staining on the heat transfer
surface at each portion after a long-term continuous run following the initial
stages of operation.
| Table 2 Principal Specifications, Boiler |
| Item |
Specification |
Type of boiler
|
Single drum natural circulation type |
Steam Flow tons/hour
|
500 |
Steam Pressure MPa
|
14.4 |
Steam Temperature °C
|
569 |
| Fuel |
Orimulsion, HS-C heavy oil and VRO |
|
500t/h Orimulsion Burning Boiler
| 4. |
Environmental Protection Measures |
| |
The main features are as follows:
| (1) |
NOx Countermeasure
To satisfy the specified environmental restrictions, an exhaust NOx-removal system
has been installed in addition to NOx suppression through combustion measures.
Technically, to suppress the generation of NOx through combustion measures, a
conventional oil firing low-NOx (PM = Pollution Minimum) burner originally developed
by us has been modified into an Orimulsion burning unit. In addition, an intra-furnace
combustion process (MACT = Mitsubishi Advanced Combustion Technology) has been
applied. |
| (2) |
SOx Reduction Measure
The sulfur content in Orimulsion is higher than that in generally available Heavy
Oil C, generating a larger amount of SOx. An exhaust smoke desulfurizer, therefore,
has been installed. |
| (3) |
Soot Reduction Measure
To satisfy the specified environmental requirements, a dry type electric precipitator
has been installed. |
|
5. Operating results of the Exclusive Orimulsion Burning Boiler
Table 3 shows the results of a performance test conducted on the exclusive Orimulsion
burning boiler when 100% loaded in October 1999. Both performance and environmental
measurements were found to be favorable.
| Table 3 Boiler Performance Test Results |
| Item |
Unit |
Design Value |
Test Result |
Boiler Steam Flow
|
tons/hour |
500 |
502.7 |
Turbine Inlet Main Steam Pressure
|
KPa
(kg/cm2g) |
13.7
(140) |
13.7
(140) |
Turbine Inlet Main Steam Temperature
|
°C |
566 |
566 |
Feed Water Temperature
|
°C |
241 |
244.5 |
Boiler Efficiency (LHV base)
|
% |
92.5 |
93.7 |
| NOx concentration(Boiler output)(4%02) |
ppm |
180 |
156 |
| Denitration Efficiency, Denitrator, |
% |
80 |
85 |
|
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