JPS5855302Y2 - Coal ash processing equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an apparatus for treating ash containing an ammonia component collected in a high dust denitrification method in a coal-fired boiler.

The fuel used in boilers for power generation and other purposes has recently been shifting from heavy oil to coal, but when coal is used, the exhaust gas contains more nitrogen oxides, dust, etc. than heavy oil, so it is difficult to make the exhaust gas pollution-free. Before it can be released into the atmosphere, it must undergo denitrification, dust collection, and other treatments.

A catalytic reduction method using ammonia has been put into practical use as a denitrification device.

In this case, a denitrification device. Various research and development efforts are underway on how to combine dust collectors.

Currently, there are two types of coal-fired exhaust gas treatment methods that are being considered for practical use: a high-dust denitrification method in which exhaust gas is passed through a denitrification device and then passed through a dust collector; There is a low-dust denitrification method that allows the denitrification device to pass through the air, but the low-dust denitrification method generally has the disadvantage that the air preheater downstream of the denitrification device is easily clogged, so the high-dust denitrification method is considered to be advantageous.

However, in the high dust denitrification method, a part of the unreacted portion of the injected ammonia reacts with SO3 in the gas, and the ash adhering to the generated ammonia compound is collected by the dust collector.

The collected ash adsorbs ammonia compounds as mentioned above, and if it is used as a landfill or as an industrial material, it may lead to secondary pollution such as odor problems and nitrogen content entering the wastewater.

Therefore, in order to utilize the ash effectively as in the past, the ammonia content contained in the collected ash must be removed.

As a means to solve these inconveniences, the ash collected in the dust collector is heated to raise the temperature of the ash, and the ammonia compound (
For example, it is easy to think of separating ammonium sulfate) from the ash and returning the separated gas (ammonia, SO3, etc.) to the inlet end of the denitration equipment, but if such treatment is carried out, SO3
There is a problem in that the SO3 concentration in the gas that is recirculated and passes through the denitrification device and the air preheater installed downstream thereof increases.

The present invention was devised to solve the drawbacks of the conventional methods as described above, and its purpose is to convert the ash collected in the dust collector in the high-dust denitrification method into high-temperature combustion gas extracted from a coal-fired boiler. The ammonia compound is decomposed and separated from the ash, and the generated gas is further sent to the furnace combustion section of the coal-fired boiler to convert SO3 in the gas into SO2 in the high-temperature combustion section.
An object of the present invention is to provide a coal ash processing device capable of decomposing harmful components generated from the ash into harmless substances.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In the accompanying drawings, 1 is a coal ash processing device.

2 is a lime-smelling boiler equipped with a furnace 3 having a combustion section and a high-temperature combustion gas extraction section 4.

An exhaust gas outlet 2a of the boiler 2 is communicated with an exhaust gas flue 5.

A denitrification device 6, an air preheater 7, and a dust collector 8 are installed in the exhaust gas flue 5 in this order.

The denitrification device 6 has an ammonia injection pipe 9 in the flue 5 on the upstream side.
are connected and configured.

The ash discharge section 8a of the dust collector 8 is connected to an ash processing device 11 via an ash transport device 10.

The ash processing device 11 is also connected to a high-temperature combustion gas air passage 12 for supplying high-temperature combustion gas from the high-temperature combustion gas extraction section, which heats the ash with the high-temperature combustion gas and decomposes it to generate ammonia and SO3. A gas air passage 13 is connected thereto for feeding heating gas containing gas to the combustion section of the furnace 3.

14 is a treated ash outlet.

Next, the operation of the device of the present invention will be explained.

Before the exhaust gas generated in the coal-fired boiler 2 is released into the atmosphere through the exhaust gas flue 5, nitrogen oxides in the exhaust gas are suppressed to below emission standards by a denitrification device.

To explain this in more detail, the exhaust gas flowing through the flue 5 is mixed with ammonia from the ammonia injection pipe 9, and the nitrogen oxides and ammonia in the exhaust gas react with each other in the denitrification device to remove nitrogen oxides from the exhaust gas. The treatment process progresses as shown, but not all of the ammonia injected at that time is subjected to the reaction, and some of the unreacted content becomes SO in the exhaust gas.
When the exhaust gas passes through the dust collector 8, these components are collected together with the ash in the dust collector.

Most of the ash in the exhaust gas is collected by the dust collector 8, and the relatively clean exhaust gas is released into the atmosphere through the flue 5, while the collected ash is transported through ash transport. The ash is sent by the device 10 to the ash processing device 11 .

In the ash processing device 11, ash is extracted from the high-temperature combustion gas extraction section 4, and the high-temperature gas (350
It is heated while being mixed directly with the combustion gas (at temperatures above 30°F (°C) or above).

At this time, the ammonia compounds in the ash are decomposed by the high-temperature exhaust gas at a temperature of 350° C. or higher, and gaseous ammonia and SO3 are separated from the ash.

Therefore, the ash treated with this device does not contain ammonia fraction, so even if the ash is used in landfill or as an industrial material, it will not cause secondary pollution such as odor, and the ash will not cause secondary pollution such as odor. It can be used effectively.

In addition, ammonia and S separated in the ash processing device 11
O3 is sent to the furnace, where the ammonia component is converted to nitrogen and nitrogen oxides, but the degree to which this nitrogen oxide increases the concentration of nitrogen oxides in the exhaust gas discharged from the boiler 2 is negligible. .

Therefore, even if the separated ammonia is recycled to the furnace 2 as described above, the problem that nitrogen oxides are concentrated and new treatment is required does not occur.

Furthermore, since most of the SO3 that has entered the furnace 2 is decomposed into SO2 in the combustion gas high temperature section, the problem of concentration of SO3 does not occur.

As is clear from the above explanation, according to the present invention, the ammonia component and SO3 contained in the ash collected by the dust collector can be separated from the ash using high-temperature combustion gas, so the ash can be stored in landfills or used for industrial purposes. It can be effectively used as a material.

(2) The high temperature gas used for separation in (2) is boiler exhaust gas, so no separate heat source is required.

■ The separated ammonia fraction is converted into nitrogen and nitrogen oxides in the furnace, but the increase in nitrogen oxide concentration in the boiler exhaust gas due to nitrogen oxides is negligible and new processing problems arise. do not have.

(2) Since most of the separated SO3 is separated into SO2 in the furnace, excellent effects such as no problem of concentration of SO3 due to circulation can be obtained.

[Brief explanation of the drawing]

The accompanying drawings show an embodiment of the device of the present invention. In the figure, 1 is a coal ash processing device, 2 is a coal-fired boiler, 3 is a furnace, 4 is a high-temperature combustion gas extraction section, 6 is a denitrification device, 9 is an ammonia injection pipe, 8 is a dust collector, and 11 is an ash processing device It is.

Claims (1)

[Scope of utility model registration request] A coal-fired boiler equipped with a furnace having a combustion section and provided with a high-temperature combustion gas extraction section, a denitrification device connected to an exhaust gas outlet of the coal-fired boiler, and a dust collector connected to the discharge port of the denitrification device. an ash processing device connected to the dust collector, the high temperature combustion gas extraction section and the combustion section,
The ash collected by the dust collector is heated in the ash processing device with high-temperature combustion gas extracted from the high-temperature combustion gas extraction section, and the generated heated gas is sent to the combustion section to A coal ash processing device characterized by being configured to decompose harmful components in heated gas.