JPH0735311A - Combustion type superheater - Google Patents

Abstract

PURPOSE:To provide a cheap and small-sized combustion type superheater of a good controlability in which, even when a vapor generation amount at a waste heat boiler is decreased a great deal, a vapor amount more than a prescribed value can be obtained at a prescribed temperature without fail. CONSTITUTION:In a combustion superheater 17, to a supply passage 16 which supplies to a generation set 3 vapor produced by a waste heat boiler 6 which collects waste heat from exhaust gas of an incinerating furnace 1, the vapor is superheated to turn into a prescribed flow amount of high temperature vapor. Further along a vapor flow passage 17d of the combustion type superheater 17, a multi-staged water atomizing mechanisms 17a and 17b for adjustment of a vapor flow amount are arranged.

Description

Detailed Description of the Invention

[0001]

[Industrial field of application] In recent years, in order to effectively utilize the heat energy generated in a refuse incinerator, a generator for exchanging heat contained in exhaust gas generated in the incinerator with a waste heat boiler to generate steam is provided. Attention is being paid to the provided municipal waste incinerator.
The present invention is used in such a refuse incinerator,
The present invention relates to a combustion type superheater that superheats steam generated in a boiler to generate high-temperature steam at a constant flow rate and supplies the steam to a power generator in order to improve power generation efficiency.

[0002]

2. Description of the Related Art It is necessary to supply superheated steam at a constant flow rate or more to a turbine for highly efficient and stable power generation. However, the amount of steam generated in the waste heat boiler is closely related to the unstable combustion of dust, and the amount of steam generated greatly changes when the combustion state of dust changes. Therefore, conventionally,
By installing a combustion type superheater that superheats the steam generated in the boiler,
It was configured to stably supply superheated steam at a constant flow rate or more to the turbine. That is, the combustion type superheater is provided with a steam flow rate sensor at the inlet of the combustion type superheater, and when the detected flow rate decreases, water is sprayed to increase the steam flow rate and to maintain a constant steam temperature. It was configured by providing a water spray mechanism of.

[0003]

However, when the above-mentioned combustion type superheater provided with a single water spray mechanism is used in a refuse incinerator, the amount of steam generated in the boiler is greatly changed due to fluctuations in the quality of the refuse. If the amount of steam is reduced to a certain level, it is necessary to spray a large amount of water from the water spray mechanism in order to secure a steam amount equal to or larger than the set amount. In order to superheat such a large amount of sprayed steam in a short time, it is necessary to increase the combustion heat quantity of the combustion superheater and increase the heat transfer area, that is, to use a large combustion superheater. There was a problem that the cost would increase. Further, in such a large combustion type superheater, there is a problem that the controllability for maintaining the set flow rate at the set temperature is deteriorated. The object of the present invention is to eliminate the above-mentioned conventional drawbacks, and even if the amount of steam generated in the waste heat boiler is significantly reduced, the facility cost can be reduced in order to secure a certain amount or more of steam. The point is to provide a combustion type superheater with excellent controllability.

[0004]

To achieve this object, the combustion type superheater according to the present invention is characterized in that a plurality of stages of water spraying mechanism are provided along the steam flow path.

[0005]

As shown in FIG. 2, the water spray mechanisms 17a and 17b are provided.
If the two are provided in the front and rear on the steam flow path and sprayed separately (solid line in the figure), the heat exchange temperature difference (logarithmic average) will be greater than in the case of spraying with a single water spray mechanism 17a (dashed line in the figure). Therefore, even if the heat transfer area is small, it is possible to overheat to a predetermined temperature. That is, the heat exchange amount Q is represented by the product of the heat transfer rate K, the heat transfer area S, and the temperature difference ΔT. Here, when the heat exchange amount Q is constant and the temperature difference T is large, the heat transfer area is It is based on the fact that S becomes small. At this time, if the electric heating area is small, the combustion temperature can be adjusted by the rapid adjustment of the fuel supply amount with respect to the load fluctuation (vapor fluctuation) of the combustion type superheater, and the temperature can be stably adjusted to the set temperature without a response delay. .

For example, as shown in FIGS. 3 and 4, the exhaust gas temperatures at the inlet and the outlet of the combustion type superheater are 800 ° C. and 40 ° C., respectively.
Fixed at 0 ° C, the steam temperature after water injection was 320 ° C which is 10 ° C higher than the saturation temperature at a pressure of 10 MPa, the steam temperature before water injection was 550 ° C considering the heat resistant temperature of the heat transfer tube, and the water injection temperature was 20 ° C. Consider a case where the superheater having a water spray mechanism of two stages and the superheater having a water spray mechanism of two stages have the same heat exchange amount and the same water injection amount.

In the superheater having the two-stage water spray mechanism, as shown in FIG. 3A, when the steam having a flow rate of 74% is input to the superheater, the total quantity Q of steam is obtained. Therefore, 13% of water is injected by the first-stage water spray mechanism a and 13% of water by the second-stage water spray mechanism b. As shown in FIG. 3 (b), at this time, when the exchange heat amount (obtained by the product of the enthalpy and the flow rate) in the region from the second-stage water spray mechanism b to the outlet is set to reference 1, The heat exchange amount in the area reaching the first-stage water spray mechanism a is 0.5, and the heat exchange amount in the area reaching from the first-stage water spray mechanism a to the second-stage water spray mechanism b is also 0. .5, and the product of the logarithmic mean temperature difference and the electrothermal area is proportional to the amount of heat exchanged, as described above, the area from the water spray mechanism b in the second stage to the outlet, the first stage The ratio of the electrothermal areas of the region from the water spray mechanism a to the second stage water spray mechanism b and the region from the inlet to the first stage water spray mechanism a is 1:
It is calculated as 0.5: 0.5.

In the first-stage water injection, as shown in FIG.
When the steam having a flow rate of 74% is input to the superheater, in order to obtain the steam quantity having the total flow rate Q, 26
% Pour water. As shown in FIG. 4B, when the heat exchange amount in the area from the water spray mechanism c to the outlet is set to 1 at this time, the heat exchange amount in the area from the inlet to the water spray mechanism c is 1 as well. From the relationship that the product of the logarithmic average temperature difference and the electric heating area is proportional to the amount of heat exchanged, the ratio of the electric heating areas of the region from the water spray mechanism c to the outlet and the region from the inlet to the water spray mechanism c is It is calculated as 1: 4.1. Therefore, the sum of the electric heating areas when a single water spray mechanism is provided is 5.1, while the sum of the electric heating areas when a two-stage water spray mechanism is provided is 3.4. When the stepped water spray mechanism is provided, the size can be made smaller. The exhaust gas temperature at the inlet and outlet of the combustion superheater described above, pressure, steam temperature after water injection,
The steam temperature before water injection, the water injection temperature, etc. are examples, and the same applies even if appropriately changed.

[0009]

According to the present invention, even if the amount of steam generated in the waste heat boiler is significantly reduced, it is inexpensive, compact, and controllable in order to ensure a certain amount of steam or more at the set temperature. It has become possible to provide an excellent combustion type superheater.

[0010]

EXAMPLES Examples will be described below. Garbage incinerator
As shown in FIG. 1, a stoker-type incinerator 1 that incinerates municipal waste, an exhaust gas treatment device 2 that purifies exhaust gas generated from the incinerator 1, and a power generation device 3 that uses the heat of exhaust gas to generate electricity. Etc.

The incinerator 1 includes a hopper 4 for receiving an incineration object, a pusher Pu for injecting city waste, which is an incineration object in the hopper 4, from the lower end into the furnace, and an incineration object pushed by the pusher Pu. While agitating and transporting the substance, a stoker S for sequentially drying, burning, and ashing is provided by high temperature primary combustion air supplied from the bottom thereof, and at the top of the stoker S in order to complete combustion of unburned gas. A secondary combustion space 7 is formed in the space, and a secondary combustion air supply unit 9 for supplying the secondary combustion air to the space 7 is provided so as to face the space 7, and a space downstream of the space 7 is provided. 8 is provided with a waste heat boiler 6 for recovering the thermal energy of the combustion exhaust gas.

The exhaust gas treatment device 2 is composed of a bag filter 12, a smoke washing device 13 and the like which are provided in the middle of a flow path from the exhaust gas passage 10 provided downstream of the space 8 to the chimney 11.

The power generator 3 comprises a steam turbine 14 and a generator 15 connected to its output shaft,
About 100 kgf / c generated from the waste heat boiler 6
m ² and high temperature steam of 310 ° C. are led to a combustion type superheater 17 through a steam supply line 16 which is a main steam line, and are superheated to about 500 ° C. by the combustion type superheater 17 and then supplied to the steam turbine 14. To do.

As shown in FIG. 2, the combustion type superheater 17 includes a gas burner 17c, a steam passage 17d for introducing steam from the waste heat boiler 6, and a two-stage structure provided along the steam passage 17d. Water spray mechanisms 17a and 17b are provided, and the steam flow path 17 is generated by the combustion heat of the gas burner 17c.
It superheats the steam from the waste heat boiler 6 flowing in d, and supplies a part of its own exhaust gas as a cooling gas to the combustion chamber via a flow rate adjusting damper 17e in order to protect the side wall of the heat exchange part. A cooling circulation passage 17f is provided, and the remaining exhaust gas is supplied as secondary combustion air for the incinerator 1 via the combustion air supply passage 30. The combustion type superheater 17
A steam amount sensor 17h is provided at the steam inlet to
When the detected value of the steam amount sensor 17h is smaller than the set steam amount, a predetermined amount of water is sprayed by the water spray mechanisms 17a and 17b to secure the set steam amount.

For example, as shown in FIG. 3, the exhaust gas temperature at the inlet and outlet of the combustion type superheater is fixed at 800 ° C. and 400 ° C., and the steam temperature after water injection is 10 ° C. higher than the saturation temperature at a pressure of 100 kgf / cm ² . A high 320 ° C, the steam temperature before water injection is 550 ° C considering the heat resistant temperature of the heat transfer tube, and the water injection temperature is 20 ° C. When steam with a flow rate of 74% of the target flow rate Q is input to the superheater, the target In order to obtain the amount of steam of the flow rate Q, 13% is injected by the first-stage water spray mechanism 17a, and 13% is injected by the second-stage water spray mechanism 17b.
Set the amount of water injection appropriately.

The steam supplied to the steam turbine 14 and used to generate all the energy is recovered after being cooled by the cooler 18 through the exhaust passage 14c and returned through the condensate passage 25 circulated to the waste heat boiler 6. Further, a part of the steam supplied to the steam turbine 14 is taken out from the extraction passages 14 a and 14 b after having used a part of the energy for power generation, and is guided to the feed water preheater 19 provided in the condensate passage 25.

Another embodiment will be described below. Exhaust gas temperature of the inlet and outlet of the combustion type superheater described in the previous embodiment, pressure, steam temperature after water injection, steam temperature before water injection, water injection temperature, etc. are examples, and are not particularly limited. It can be set appropriately. In the above-described embodiment, the combustion type superheater is provided with the two-stage water spray mechanism provided in front and rear, but the position where the water spray mechanism is provided may be appropriately determined by the system and is not particularly limited. Further, the water spray mechanism is not limited to the two-stage type, but may be configured in multiple stages. Further, the water spray mechanism at the latter stage may be one that also controls the steam temperature in addition to the steam flow rate.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a refuse incinerator.

FIG. 2 is a schematic configuration diagram of a combustion type superheater.

FIG. 3 is an operation explanatory view of a combustion type superheater.

FIG. 4 is an operation explanatory view of a conventional combustion type superheater.

[Explanation of symbols]

 3 generator 6 boiler 17a water spray mechanism 17b water spray mechanism 17d steam flow path

Claims (1)

[Claims] 1. A combustion type superheater which guides steam generated in a boiler (6) to a steam flow path (17d) to superheat it to generate high-temperature steam at a constant flow rate and to supply the steam to a power generator (3). A combustion type superheater provided with a plurality of stages of water spray mechanisms (17a), (17b) along the steam flow path (17d).