JPS6363809B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating soot and dust, so-called periodic inspection ash, which is collected for a while when starting operation after a boiler periodic inspection.

During periodic inspections of boilers, the inside of the furnace, ducts, and other equipment are inspected, and a considerable amount of rust is removed due to equipment maintenance, reinstallation, vibration, etc., and simple cleaning is not sufficient to remove it. For a while after the regular inspection, for example, for about 20 days, the collected ash will contain a considerable amount of non-combustible components such as rust (Fe ₂ O ₃ ), for example, about 40%. In addition, this collected ash contains unburned carbon from the combustion of heavy crude oil, ammonium sulfate from denitrification, etc., and is burned in a fluidized bed furnace to recover the retained energy and reduce the volume. However, there is a problem in that the operation of the fluidized bed furnace deteriorates due to the formation of small lumps of the fluidized medium, deposits on the perforated plate, etc., and the operation of the fluidized bed furnace eventually has to be shut down.

The purpose of this invention is to solve such problems and to propose a method for incinerating regularly inspected ash.

In short, the present invention is characterized in that it is a method of removing non-combustible components from periodically inspected ash and supplying only combustible components to a fluidized bed furnace for combustion.

First, as an example, the amount and properties of collected ash in a power generation boiler in actual operation are as follows.

Exhaust gas amount 37000 Nm ³ /h Heavy crude oil ash 17Ton/day (710Kg/hr) (When containing 75% unburned components) (a) Heavy crude oil ash properties Unburned carbon (ignition loss) 30-75% (NH ₄ 5-15% SO ₄ 20-40%) Calorific value (dry base) 2550-5960Kcal/
Kg (b) Properties of regularly inspected ash Moisture 70-80% Unexploited carbon (loss on ignition) 5-
15% Electrostatic precipitator collected ash (referred to as EP ash) Rust (Fe ₂ O ₃ ) content 35-40% A power plant is usually equipped with several boilers. Originally, one boiler (unit boiler)
It is uneconomical to install a single incinerator in the area, so the collected ash from several boilers is sent to one collective storage tank, from where it is supplied to the incinerator for combustion.

The pipe system is shown in Figure 1.

1A, 1B, and 1C each indicate independently operated boilers. The exhaust gases from the boilers 1A, 1B, and 1C are collected with dust collectors 2A, 2B, and 2C, and are sent to unit storage tanks 3A, 3B, and 3C, respectively. The collected soot dust (collected ash) is transferred from this unit storage tank to cushion tanks 3A', 3B',
3C' and transmitters 4A, 4B, and 4C with low pressure air (approximately 2.0 kg/cm ² g) to pipes 5A,
5B, 5C, valves 6A, 6B, 6C, switching box 7, main pipe 8, and valve 9, and are sent to collection tank 10. The pressurized air is sent to the incinerator 14 from the pipe 11 and is used as part of the combustion air.

The collected ash in the collection tank 10 passes through the valve 10a,
When necessary, the material is sent to the incinerator 14 via the pipe 10b using a feeding device (not shown) and is incinerated. The auxiliary combustion material is supplied to the incinerator 14 through the pipe 12, and the fluidizing and combustion air and the combustion air are supplied from the blower 13 to the incinerator 14 via the pipe 15.

However, with this type of equipment, burning soot and dust containing a large amount of non-combustible components such as rust after a periodic inspection is treated with a combustion equipment such as a fluidized bed furnace, which causes various difficulties as mentioned earlier. be.

This invention aims to remove such rust etc. from regularly inspected ash and burn only the combustible components to achieve stable operation. The piping system of the apparatus used for this purpose is shown in Fig. 2. In this invention, a bypass pipe line 16 is provided that bypasses the main pipe line 8 connecting the switching box 7 and the collection storage tank 10. A valve 17, a cyclone separator 18, and a bag filter 19 are arranged in this conduit in this order from the switching box 7 side. By closing the valve 9, regularly inspected ash containing rust, etc. does not flow directly into the collection tank 10, but instead flows into the bypass pipe 16, and flows into the cyclone separator 18 through the valve 17, so that most of the rust, etc., which has a large specific gravity, is separated. removed. As a result of analysis in the laboratory, the Fe content of soot dust of 100 μm or more is more than 80%, while the cyclone separator usually easily collects dust of 20 μm or more and is efficient.
The fact that about 98% was obtained indicates that this cyclone separator can sufficiently remove non-combustible components such as rust. Unburned carbon and ammonium sulfate components, which are combustible components, are passed through the bag filter 1 through a pipe 16a.
9 and is collected. This collected ash is transferred to pipe 16b
is sent to the collection storage tank 10 via the storage tank 10.

In particular, for the collected ash when starting the boiler for the first time after a regular inspection, a pipe line 23 including a valve 22 that further bypasses the bypass line 16 is provided,
4. The regular inspection hopper 24 can also be used when inspecting or collecting the cyclone separator 18 and bag filter 19. The pressurized air from the bypass pipe 16 passes through the pipe 20, and the pressurized air to the regular inspection hopper 24 is supplied to the incinerator 14 via the pipe 26 to be used as secondary combustion air.

The regular inspection ash from the regular inspection hopper 24 is sent to the non-combustible component separation device 2.
5, and if necessary, a moisture removal device (dryer)
(not shown), only the combustible components can be sent to the collection tank 10 from the pipe line 27.

In addition, the periodic inspection ash supplied from the cushion tanks 3A', 3B', 3C' to the transmitters 4A, 4B, 4C contains a lot of rust, etc., so the amount transported at one time is approximately 1/5 of the boiler's rated operation. A similar amount will give favorable results for the transportation of regularly inspected ash. The distance from this transmitter to the collective storage tank is approximately 700m.
There are also cases. In one example, the capacity of the cushion tank is about 600, and the inside of the transport pipe is in a plug state, and the product is transported at a speed of 2 to 3 meters per second. It is preferable to supply the collected ash to the cushion tank, complete the transport, and clean the inside of the pipe in one cycle of 700 m, or about 10 minutes per cycle. Therefore, when transporting regularly inspected ash, it is recommended to transport approximately 120 times. Also, it takes about 30 minutes for regular inspection ash to return to the ash state at rated operation.
I experienced that it took a week.

By carrying out this invention, the soot and dust supplied to the collective storage tank will be almost exclusively combustible components, making it possible to operate the incinerator continuously and stably. This has the effect of completely eliminating the need for the furnace to shut down.

[Brief explanation of drawings]

FIG. 1 is a pipe system diagram of a conventional apparatus for treating soot and dust in boiler exhaust gas, and FIG. 2 is a pipe system diagram of a periodic inspection ash processing apparatus according to the present invention. 1A, 1B, 1C...Boiler, 3A, 3B, 3
C...Unit storage tank, 3A', 3B', 3C'...Cushion tank, 4A, 4B, 4C...Transmitter, 7...Switching box, 8...Main conduit, 10...Combined storage tank, 14... ...Incinerator, 16...Bypass pipeline,
18...Cyclone separator, 19...Bag filter, 24...Regular inspection hopper.

Claims (1)

[Scope of Claims] 1. A method for transporting the collected soot and dust through pipes from a unit storage tank for storing soot and dust collected from boiler exhaust gas to a collective storage tank located near an incinerator, and then supplying the soot and dust to the incinerator for combustion treatment. , a switching box is provided in the pipeline, the switching box and the collection storage tank are connected through a main pipeline, and a bypass pipeline is provided in the main pipeline, so that after a regular inspection of the boiler, the collected ash has the composition of normal heavy crude oil ash. Until then, non-combustible components are removed by a non-combustible component removal device provided in the bypass pipe, and combustible components are supplied to an incinerator and burned. 2. The non-flammable component removal device is a cyclone separator or bag filter provided in a bypass pipe,
2. The method for treating periodically inspected ash according to claim 1, wherein the ash collected by the bag filter is burned in an incinerator. 3. A patent claim characterized in that, during the combustion treatment of periodically inspected ash, the amount of soot and dust pumped through the pipe from the cushion tank of the unit storage tank is approximately 1/5 of the amount of soot and dust that is pumped per unit during rated operation of the boiler. A method for processing regularly inspected ash as described in item 1 or 2. 4. Any one of claims 1 to 3, characterized in that the air for pressure-feeding periodically inspected ash is supplied to the incinerator as secondary combustion air for the incinerator via a bag filter connected to the heavy crude oil ash storage tank. Processing method for regularly inspected ash described in ``Kani''. 5. The method for processing periodically inspected ash according to claim 1, characterized in that a pipeline further bypassing the bypass pipeline is provided, and this pipeline is provided with a regularly inspected ash hopper and a non-combustible component separation device.