JPH0243118B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention utilizes heat retained in combustion gas and waste gas (sensible heat).
It is a device that recovers heat for use as a heat source when generating hot water, steam, or high-temperature gas, etc. Specifically, it is a device that recovers heat retained in high-temperature gases such as combustion gas and waste gas that are forcibly sent to a group of smoke pipes via a blower. The present invention relates to a high-temperature gas heat recovery device that is provided with a heat exchange section that recovers gas by indirect heat exchange action. In such a high-temperature gas heat recovery device, in order to maintain a good heat exchange effect in the smoke pipes and perform heat recovery efficiently, the medium and dust attached to the inner peripheral surface of each smoke pipe are removed periodically or irregularly. need to be removed. Conventionally, methods for removing it have included installing steam-type or compressed-air-type soot blowing equipment or water washing equipment, but in either case, the overall structure of the equipment becomes complicated and large. Not only do
The disadvantage was that equipment costs and operating costs were high. Also, there is a known method of increasing the gas flow rate in each smoke pipe during normal operation to prevent smoke and dust from adhering to the inner circumferential surface of the smoke pipe. Since the gas passing pressure loss in the heat exchange section is proportional to the square of the gas velocity, a blower with a very large capacity is required, which has the disadvantage of high initial costs and running costs such as electricity bills. be. In view of the above-mentioned circumstances, an object of the present invention is to make it possible to economically and advantageously remove soot and dust adhering to the inner circumferential surface of each smoke pipe. The high-temperature gas heat recovery device according to the present invention has two states: a first state in which a small group of smoke pipes are sequentially opened to force the high-temperature gas to flow through each of the smoke pipes; A passage area switching mechanism is provided that can switch between a second state in which gas is forced to flow, and the rotational speed of the blower is set to a high and a low speed.
It is characterized by a structure that can be changed freely into stages. That is, there is a relationship in which the gas passage area (the number of smoke pipes through which gas passes) in the heat exchange section is inversely proportional to the gas velocity ratio or the cube of the rotation speed ratio of the blower, and the switching mechanism is switched to the first state. By appropriately selecting the gas passage area and the rotational speed of the blower so as to satisfy the above relationships, it is possible to use a blower with sufficient capacity to carry out normal operation without any trouble, while also ensuring that the air flow inside the smoke pipe is It is possible to increase the gas velocity to a speed sufficient to blow away soot, dust, etc. that has adhered to the inside of the smoke pipe, so it is very easy to install a switching mechanism and configure the blower to be able to change its rotation speed. and by economic means,
The soot and dust adhering to the inside of the smoke pipe can be removed, thereby making it possible to improve the heat recovery efficiency economically. Embodiments of the present invention will be described below based on the drawings. A blower 3 is provided in the exhaust gas discharge path 2 to the chimney 1 to forcefully feed the waste gas, and this blower 3
The waste gas heat recovery device is equipped with a reduced pressure boiler 4 that uses the retained heat (sensible heat) of the waste gas as a heat source on the upstream side, and the reduced pressure boiler 4 maintains the internal pressure below atmospheric pressure. A heat exchange section 7 heats and evaporates heat medium liquid sealed in a closed container 5 with waste gas by indirect heat exchange action via a large number of smoke pipes 6, and a heat medium liquid such as generated steam and water for water supply. It is equipped with a heat exchanger 18 that condenses and liquefies steam through indirect heat exchange and heats and raises the temperature of the fluid to be heated. Then, on the upstream side of the heat exchange section 7, a smoke pipe 6...
For each, a first state in which one end opening of a small number of smoke pipe groups is sequentially opened and the waste gas is forced to flow only within the small number of smoke pipe groups, and a first state in which one end opening of all smoke pipes 6... is simultaneously opened at once. A gas passage area switching mechanism 8 is provided which can be switched to a second state in which the exhaust gas is forced to flow through all the smoke pipes 6 by opening the gas pipe 6, and means for changing the rotational speed of the blower 3 into two high and low stages. , and when the temperature detected by the sensor 9 that detects the temperature of the heat transfer liquid in the normal operating state becomes equal to or lower than the set temperature, the switching mechanism 8 is switched to the second state, and the rotation speed of the blower 3 is increased. The switching mechanism 8 has a notch 11A formed therein.
While opening only one end opening of a small number of smoke pipe groups corresponding to 6, the remaining smoke pipes 6... are closed, and
A baffle plate 11 that rotates to sequentially position the notch 11A corresponding to one end opening of all the smoke pipes 6, a motor 12 that rotates the buff full plate 11, and a motor 12 that rotates the buff full plate 11 to position the notch 11A corresponding to one end opening of all the smoke pipes 6. It is composed of a hydraulic cylinder 13 that changes its position to a position where the openings are simultaneously opened all at once. The means for switching the rotation speed of the blower 3 is a means for changing the number of poles of the drive motor 3A of the blower 3, and other means include means for changing the frequency and means for mechanically changing it. Since the means described above are also well known, a detailed explanation thereof will be omitted. According to the configuration of the above embodiment, normally, the switching mechanism 8 is switched to the second state and the blower 3 is rotating at a low speed, and soot and dust adhere to the inner peripheral surface of the smoke pipe 6. When the heat exchange action in... is inhibited, and as a result, the heat medium liquid temperature reaches the set temperature, the switching mechanism 8 automatically switches to the first state, and
The blower 3 automatically rotates at high speed. The shaft power (Pw), air volume (Q), total pressure (Ps) of the blower 3, gas passage pressure loss (Δp) in the heat exchange section 7, gas velocity (V), gas passage area (S)
There is a relationship as follows: Pw=k ₁ ×Q×Ps, Q=k ₂ ×N, Q=S×V, Δp=k ₄ ×V ² , whereby the switching mechanism 8 is switched to the second state. If the gas velocity at that time is V ₀ , then the pressure loss (Δps), required total pressure (Ps ₀ ), and required rotation speed (N ₀ ) are: Δp ₀ = Δp×(V ₀ /V) ² , Ps ₀ =Ps×(V ₀ /V) ² , N ₀ =N×V ₀ /V. Therefore, when the required shaft power (Pw ₀ ) when switching the switching mechanism 8 to the first state is made the same as the required shaft power (Pw) when switching to the second state, the air volume (Q ₀ ) is as follows. If the efficiency change of the blower is not much different, Pw ₀ = Pw Q ₀ × Ps ₀ = Q × Ps Q ₀ = Q × Ps / Ps ₀ = Q × Ps / Ps × (V ₀ /V) ² = Q × (V /V ₀ ) ² = Q x (N/N ₀ ) ² , and is inversely proportional to the square of the gas velocity ratio and rotation speed ratio, and the gas passage area (S ₀ ) is S ₀ =Q ₀ /V ₀ = Q x (V/V ₀ ) ² /V ₀ = S x (V/V ₀ ) ³ = S x (N/N ₀ ) ³ , which is inversely the cube of the gas velocity ratio and rotation speed ratio. Proportional. Therefore, according to the configuration of the above embodiment, for example, when the gas velocity during normal operation with the switching mechanism 8 switched to the second state is 10 m/s, the flow inside the flue pipe 6 is maintained without changing the required shaft power. soot adhering to
To obtain a gas velocity of 20 m/s sufficient to blow away dust, as shown in the following table, by switching the switching mechanism 8 to the first state, the gas passage area is reduced to 1/8, and the blower 3 All you have to do is double the number of rotations.

【table】

[Table] As shown in FIGS. 3 and 4, the switching mechanism 8 selectively opens and closes the damper plates 14 that can be opened and closed one by one for each of a small number of groups of smoke pipes. The first state may be brought out, and the second state may be brought out by opening all the damper plates 14.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram, FIG. 2 is an enlarged sectional view taken along the line of FIG. 1, FIG. 3 is a vertical sectional view of a main part showing another embodiment, and FIG. FIG. 3... Air blower, 6... Smoke pipe, 7... Heat exchange section,
8... Passage area switching mechanism.

Claims (1)

[Scope of Claims] 1. A high-temperature gas heat system equipped with a heat exchange section 7 that recovers the heat retained in high-temperature gases such as combustion gas and waste gas that are forcibly fed to a group of smoke pipes via a blower 3 through an indirect heat exchange action. In the recovery device, for each of the smoke pipes 6, there is a first state in which a small number of smoke pipe groups are sequentially opened to force the high-temperature gas to flow, and a first state in which all the smoke pipes 6 are forced to flow.
A passage area switching mechanism 8 that can be switched to a second state in which the high temperature gas is forced to flow by simultaneously opening the...
A high-temperature gas heat recovery device characterized in that the rotation speed of the blower 3 is freely changeable in two stages, high and low. 2. The high temperature gas heat recovery device according to claim 1, wherein the blower 3 is provided downstream of the heat exchange section 7. 3. Claim 1 or 2, wherein the passage area switching mechanism 8 is switched to the first state when the rotation speed of the blower 3 is switched to a high side.
The high-temperature gas heat recovery device described in .