Concentrating evaporators – Fluid feed or discharge devices – Automatic
Reexamination Certificate
1998-05-14
2002-07-02
Manoharan, Virginia (Department: 1764)
Concentrating evaporators
Fluid feed or discharge devices
Automatic
C044S301000, C044S903000, C044S904000, C159S023000, C159S046000, C159S047100, C159S900000, C196S132000, C196S141000, C210S774000
Reexamination Certificate
active
06413361
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an evaporator system for separation of water content in a heavy oil emulsified fuel by way of heating, and an operation method thereof.
2. Description of the Prior Art
As heavy oils of a high consistency nature, in order to make its handling during transportation and storage easier, heavy oil fuel is provided in advance with an appropriate amount of water and surface active agent so as to form what is called a heavy oil emulsified fuel. When this heavy oil emulsified fuel is to be burned in a combustion furnace of a boiler etc., it is desirable to remove water content from the heavy oil emulsified fuel for combustion efficiency.
A prior art evaporator system for separation of water content in the heavy oil emulsified fuel is shown in
FIG. 7
, and a description will be made thereof. In
FIG. 7
, numeral
11
designates a tank, in which an emulsified fuel
11
a
is stored. Numeral
12
designates a pump, numeral
13
designates a preheater, numeral
14
designates an evaporator, numeral
15
designates a separator, numeral
16
designates a heating steam supply equipment and numeral
17
designates a pump.
In the evaporator system of
FIG. 7
having such equipment and machinery, the emulsified fuel
11
a
, containing water, in the tank
11
is fed into the preheater
13
via the pump
12
and a piping
11
b
. A heat exchanger tube
13
a
is provided within the preheater
13
for flow of heating water or steam, after separated, as a preheating source medium which is described later, and the emulsified fuel
11
a
is filled surrounding the heat exchanger tube
13
a.
It is to be noted that the preheating source medium and the emulsified fuel
11
a
may flow either on the inside or on the outside of the heat exchanger tube
13
a.
The emulsified fuel
11
a
outside of the heat exchanger tube
13
a
is preheated to a certain temperature through heat exchange with the preheating source medium and is sent to the evaporator
14
via a piping
13
b
. Within the evaporator
14
are provided a plurality of generating tubes
14
a
,
14
b
,
14
c
, for flow of the preheated emulsified fuel
11
a.
On the other hand, the emulsified fuel
11
a
is heated by a heating source medium surrounding the generating tubes
14
a
,
14
b
,
14
c
, the heating source medium being a heating steam, for example, which is supplied from the heating steam supply equipment
16
via a piping
16
a
, and the heating source medium of which temperature has been lowered is discharged through a piping
16
b
. Thus, the emulsified fuel
11
a
within the generating tubes
14
a
,
14
b
,
14
c
is boiled to be evaporated and is then sent to the separator
15
via a piping
14
d.
The emulsified fuel
11
a
fed into the separator
15
is separated into water content (such as steam) (i.e., water portion) and heavy oil fuel. The water content separated from the emulsified fuel
11
a
at the separator
15
is sent to the preheater
13
via a piping
15
a
in a state of heating water or steam to be used as a preheating source which flows in said heat exchanger tube
13
a
of the preheater
13
. After its temperature has been lowered, the water content is discharged out of the system via a piping
15
b.
It is to be noted that a surplus water remaining after the separated water has been taken for said preheating source is extracted outside of the system via an extraction valve
15
c
and a piping
15
d
to be used for an atomizing steam etc. Also, the heavy oil fuel of which water content has been separated at the separator
15
is taken out of the system via a piping
15
e
and a pump
17
to be burned in a combustion system (a boiler, for example) having main equipment, such as a tank, a burner, etc. which are not shown in the figure.
In order to make effective use of the amount of heat input of the heating source medium fed into the evaporator
14
, a heat regeneration type is used in which the water content separated from the emulsified fuel at the separator
15
is introduced into the preheater
13
as the preheating source medium so that its heat source is made use of repeatedly, and a design of construction consisting of the preheater
13
, the evaporator
14
, etc. having a heating area that is compact to the greatest extent possible is employed.
In the prior art evaporator system as described above, it is essential to operate it so as to obtain such a high efficiency water separation so as to bring on a maximum thermal efficiency, a most compact-sized design of equipment and machinery and an always constant predetermined value of water content in the heavy oil emulsified fuel which is obtained after separation.
In the mentioned combustion system (boiler etc.) for burning the separated heavy oil fuel, however, the amount of use of the heavy oil fuel used therein is not always constant but varies unavoidably corroding to load change in the boiler etc. For example, if flow rate of the emulsified fuel is increased from a certain flow rate, because the system is of a closed loop, the amount of the preheating source medium from the piping
15
a
does not increase rapidly resulting in lowering of outlet temperature of the preheater and change of the operation conditions.
Thus, when the amount of the emulsified fuel (hereinafter called a “load”) sent to the preheater from the tank
11
changes, because the system employs a heat regeneration type, there occurs a delay in delivery and receipt of heat and temperature in each portion changes. Consequently, water content in the emulsified fuel obtained after separation does not become constant, and as one countermeasure therefor, there is given unavoidably a considerable allowance in the design of heating area in the heat exchanger portion of each component of equipment and machinery.
On the other hand, a small amount of light oil content is mixed in the water content separated at the separator
15
, and the preheating source medium in which this light oil content is mixed is used for heat exchange at the preheater
13
. When this preheating source medium is discharged in a state of steam (gas) from the preheater
13
, the light oil content mixed therein in a state of vapor is condensed soon together with the water content so that the oil content is suspended in the water. The oil content once suspended in the water is hardly separated or removed by a general oil content treatment equipment, and draining thereof into rivers and the like becomes impermissible so that there occurs an obstacle in the operation of the evaporator system.
Further, if there occurs a pressure reduction action in the separator
15
, the water content in the emulsified fuel which is heated to a high temperature at the evaporator
14
flashes (evaporizes) rapidly and hardly gets out of the surrounding high consistency heavy oil fuel resulting in a state of bubbles in which the emulsified fuel surrounds the steam gas. As the result, the volume of the fuel increases rapidly to fill the separator
15
or to cause an overflow in the water content separation and extraction pipings, separation performance of the water content is deteriorated rapidly, and a large amount of the oil content is discharged out of the system.
SUMMARY OF THE INVENTION
In view of the problems as mentioned above in the prior art heavy oil emulsified fuel evaporator system, it is an object of the present invention to provide an operation method of a heavy oil emulsified fuel evaporator system. In this method, a heavy oil emulsified fuel, after being preheated at a preheater, is led into an evaporator to be heated and then to a separator for separation of its water content so as to form a water portion and a heavy oil portion. The water content, after being separated, is used as a preheating source medium for said preheater, and is channeled to the preheater to preheat the emulsified fuel. The water content separation to a predetermined level is enabled irrespective of load change in a heavy oil fuel combustion equipment. The pressure of the preheating
Hino Hirokazu
Ichinose Toshimitsu
Tokuda Kimishiro
Ueda Katsuyuki
Manoharan Virginia
Mitsubishi Heavy Industries Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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