Liquid heaters and vaporizers – Miscellaneous
Patent
1990-01-03
1991-10-01
Favors, Edward G.
Liquid heaters and vaporizers
Miscellaneous
110245, 16510416, B09B 300, F22B 100
Patent
active
050523449
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a control apparatus capable of controlling the amount of thermal energy recovered from a sector of the fluidized bed of a boiler system and supplied to the boiler drum thereof, the boiler system being so constructed that such combustibles as municipal refuse, industrial waste, coal or the like are incinerated in a so-called fluidized bed and the boiler drum receives the resulting thermal energy. The present invention relates more particularly to the improvement of an incineration control apparatus adapted to enhance the response of the suppressed control of increases and decreases in steam pressure caused by variations in the steam load by correlating the steam pressure in the boiler drum with control of the thermal energy recovered by the boiler drum.
BACKGROUND ART
Fluidized bed boilers are widely known. However, there has been general concern recently about boilers of this type which have a construction wherein the fluidizing medium is divided into two parts, one part being accommodated in the incineration chamber and the other being accommodated in the thermal energy recovery chamber in such a manner that the medium is circulated, thermal energy being recovered from the heat recovery means which takes the form of water pipes or the like provided in the recovery chamber, the amount of recovered thermal energy being controllable.
As for the principle of controlling the amount of thermal energy to be recovered from the fluidizing medium in such a heat recovery chamber, there are known methods wherein the contact area between the heat recovery means such as water pipes or the like and the fluidizing medium in the fluidized bed in the heat recovery chamber is so varied that the amount of thermal energy transferred may be controlled (i.e., the so-called slumping bed method), or wherein the condition of the bed comprised of the fluidizing medium in the heat recovery chamber is so varied that the heat transfer coefficient between the fluidizing medium and the heat recovery means may be controlled. The latter category includes such methods as that wherein the condition of the bed comprised of the fluidizing medium is varied between a fluidized bed condition having an extremely high heat transfer coefficient and a fixed bed condition having an extremely low heat transfer coefficient, heat recovery being intermittently controlled (as disclosed in Japanese Patent Public Disclosure No. 58-183937, U.S. Pat. No. 3,970,011 and U.S. Pat. No. 4,363,292), and that wherein the boundary between the area of the fluidized bed condition and the fixed bed condition is continuously varied so that heat recovery may be controlled continuously and smoothly (as disclosed in Japanese Patent Public Disclosure No. 59-1990). Additionally another method has recently been proposed by the inventor of the present invention (as disclosed in Japanese Patent Application No. 62-9057) in which the fluidizing medium in the heat recovery chamber is supplied with air at a relatively low air velocity (or 0 Gmf-2 Gmf in respect of mass velocity), the fluidizing medium is maintained as a transient bed which is a typical bed condition with a heat transfer coefficient which will vary substantially linearly in relation to the air velocity, the heat transfer coefficient therein being continuously varied in a substantially linear manner so that recovery of thermal energy may be controlled continuously and smoothly.
It should be pointed out here that since controlling the amount of thermal energy recovered by a boiler drum from a heat recovery chamber is particularly effective in maintaining the temperature of the fluidized bed in the incineration chamber within an appropriate range, this type of control is regarded as beneficial because it offers the following advantages. 850.degree. C., incineration efficiency may be improved (in the case of coal burning). 850.degree. C., burning of the fluidized bed may be prevented (in the case of incineration of the municipal refuse). C.-850.degree. C., which is a d
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Higo Tsutomu
Inumaru Naoki
Kawaguchi Hajime
Kosugi Shigeru
Ohshita Takahiro
Ebara Corporation
Favors Edward G.
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