CN215863421U

CN215863421U - Plasma molten flue gas secondary combustion chamber

Info

Publication number: CN215863421U
Application number: CN202121798768.XU
Authority: CN
Inventors: 周赞; 龚滨; 殷波; 陈军; 于飞
Original assignee: Wuxi Xuelang Environmental Technology Co Ltd
Current assignee: Wuxi Xuelang Environmental Technology Co Ltd
Priority date: 2021-08-04
Filing date: 2021-08-04
Publication date: 2022-02-18
Anticipated expiration: 2031-08-04

Abstract

The utility model provides a plasma molten flue gas secondary combustion chamber which can ensure that CO in tail gas of a plasma melting furnace is completely combusted, and ensure that the content of CO in the combusted tail gas reaches the standard. Comprises a secondary combustion chamber flue gas inlet connected with a plasma furnace and a secondary combustion chamber flue gas outlet connected with a downstream tail gas treatment device; the ash hopper, the Venturi section and the flue gas retention section are sequentially arranged from bottom to top and are communicated with each other; the second combustion chamber flue gas inlet is arranged on the side surface of the bottom of the ash bucket; the cross section of the section body of the Venturi section is smaller than the cross sections of the smoke inlet and the smoke outlet, and the auxiliary burner and the secondary air inlet device are arranged on the Venturi section; a third air inlet device is arranged at the bottom of the smoke retention section and above the smoke outlet of the venturi section, and the air outlet of the third air inlet device faces downwards; the secondary air inlet device and the tertiary air inlet device adopt a high-pressure rotational flow form for air inlet, and the rotational flow directions of the secondary air inlet device and the tertiary air inlet device are opposite.

Description

Plasma molten flue gas secondary combustion chamber

Technical Field

The utility model relates to the technical field of solid waste plasma melting treatment, in particular to a plasma molten flue gas secondary combustion chamber.

Background

When solid waste and dangerous waste are treated by applying a plasma melting technology, a plasma device is used for generating high temperature, organic matters and dioxin possibly existing in the dangerous waste are broken under the combined action of the high temperature generated by plasma and ultraviolet rays to form small molecules or atoms, and recombination is carried out under a reducing atmosphere to generate plasma molten flue gas, wherein the plasma molten flue gas comprises: simple substance carbon, CO, H2, CH4, HCl and other harmful substances.

Generally, a secondary combustion chamber is arranged at the outlet of the plasma furnace, secondary combustion-supporting air is introduced into the secondary combustion chamber, and combustible components and harmful substances in plasma melting smoke are fully incinerated and decomposed under the premise of ensuring the principle of '3T + E', namely, under the conditions of sufficient smoke temperature (> 1100 ℃), sufficient residence time (> 2s at 1100 ℃), sufficient disturbance (secondary air for forming airflow into swirling flow at the throat of the secondary combustion chamber) and sufficient excess oxygen.

However, the concentration of CO in the tail gas of the plasma melting furnace is very high, particularly the CO ratio in the flue gas of the thermal plasma melting furnace based on reducing atmosphere can reach more than 30-40%, if the mixing strength of the flue gas and combustion air is difficult to ensure by adopting the traditional secondary combustion technology, the CO in the flue gas can not be burnt fully and thoroughly, and the CO emission in the subsequent tail gas treatment process exceeds the standard.

Disclosure of Invention

In order to solve the problem that CO in tail gas at an outlet of a plasma furnace is difficult to completely burn in the prior art, the utility model provides the secondary combustion chamber for plasma molten flue gas, which can ensure that CO in the tail gas of the plasma molten furnace is completely burned and ensure that the content of CO in the burnt tail gas reaches the standard.

The technical scheme of the utility model is as follows: the plasma molten flue gas secondary combustion chamber comprises a secondary combustion chamber flue gas inlet connected with the plasma furnace and a secondary combustion chamber flue gas outlet connected with a downstream tail gas treatment device;

it is characterized in that it also comprises: the ash hopper, the Venturi section and the flue gas retention section are sequentially arranged from bottom to top and are communicated with each other;

the second combustion chamber flue gas inlet is arranged on the side surface of the bottom of the ash hopper;

the cross section of the section body of the Venturi section is smaller than the cross sections of the smoke inlet and the smoke outlet of the Venturi section, and an auxiliary burner and a secondary air inlet device are arranged on the Venturi section;

a third air inlet device is arranged at the bottom of the flue gas retention section and above the flue gas outlet of the venturi section, and an air outlet of the third air inlet device faces downwards;

the secondary air inlet device and the tertiary air inlet device adopt a high-pressure rotational flow form for air inlet, and the rotational flow directions of the secondary air inlet device and the tertiary air inlet device are opposite.

It is further characterized in that:

the flue gas retention section is of a vertical straight-tube structure, and a flue gas outlet of the secondary combustion chamber is arranged on the side surface of the top of the flue gas retention section;

it still includes: the quick smoke exhaust chimney is communicated with the top end of the smoke retention section;

a primary air inlet device is arranged on the side wall of the inner cavity of the ash bucket, and the primary air inlet device adopts high-pressure distributed air inlet;

the tertiary air inlet device adopts a high-pressure distributed cyclone device.

According to the plasma molten flue gas secondary combustion chamber provided by the utility model, the ash bucket with large capacity is arranged to reduce the flue gas flow velocity of plasma molten flue gas, the turbulence effect of combustion-supporting air and flue gas is enhanced by the plasma molten flue gas after the speed is reduced through the secondary air inlet device and the tertiary air inlet device which are opposite in rotational flow direction, so that the combustion-supporting air and the flue gas are mixed more sufficiently, sufficient combustion is ensured, and further, CO in the flue gas can be completely combusted; and finally, in a flue gas retention section of the straight-tube structure, on one hand, the retention time of the flue gas in combustion at the temperature of more than 1100 ℃ is prolonged, CO in the flue gas can be further ensured to be burnt out, on the other hand, the third combustion-supporting air can effectively adjust the temperature of the outlet flue gas within a controllable range, and the temperature of the outlet flue gas is ensured to be stable and the oxygen content reaches the standard.

Drawings

FIG. 1 is a schematic structural view of a plasma molten flue gas secondary combustion chamber in the patent;

FIG. 2 is a schematic view of a secondary air intake device according to the present patent;

fig. 3 is a schematic view of a tertiary air intake device in this patent.

Detailed Description

As shown in fig. 1 to 3, the plasma melting flue gas secondary combustion chamber comprises a secondary combustion chamber flue gas inlet 5 connected with a plasma furnace and a secondary combustion chamber flue gas outlet 6 connected with a downstream tail gas treatment device; an ash hopper 1, a Venturi section 2, a flue gas retention section 3 and an acute exhaust chimney 4 which are communicated with each other are sequentially arranged from bottom to top.

The secondary combustion chamber flue gas inlet 5 is arranged on the bottom side surface of the ash bucket 1, and a primary air inlet device 7 is arranged on the middle side wall of the ash bucket 1; the side-distributed high-pressure primary air inlet device is adopted in the ash hopper 1, so that the sufficient mixing and sufficient retention time of primary air and flue gas are ensured, and the limited combustion and limited heat release effects in the first stage are effectively realized.

The cross section of the section body of the Venturi section 2 is smaller than the cross sections of the smoke inlet 2-1 and the smoke outlet 2-2, the auxiliary burner 10 is arranged in the Venturi section 2, the secondary air inlet device 8 is arranged in the inner cavity of the Venturi section 2, plasma molten smoke entering from the larger smoke inlet 2-1 enters the section body of the Venturi section 2 which is smaller, the flow speed of the smoke can be increased, meanwhile, cyclone introduced by the secondary air inlet device 8 is more easily and fully fused with the plasma molten smoke, and the combustion in the Venturi section 2 is ensured to be more sufficient.

The flue gas retention section 3 is of a vertical straight cylinder structure, a tertiary air inlet device 9 is arranged at the bottom of the flue gas retention section 3 and above a flue gas outlet 2-2 of the Venturi section 2, and an air outlet of the tertiary air inlet device 9 faces downwards; the secondary air intake device 8 and the tertiary air intake device 9 have opposite rotational flow directions, and the air intake arrangement modes of the secondary air intake device and the tertiary air intake device specifically refer to the attached figures 2 and 3 in the specification. The tertiary air inlet device 9 adopts a high-pressure rotational flow form to supply air, so that tertiary combustion-supporting wind can enter the venturi section 2 and meet with secondary combustion-supporting wind and plasma molten flue gas to generate a turbulent flow phenomenon.

The second combustion chamber flue gas outlet 6 is arranged on the side surface of the top of the flue gas retention section 3. The quick exhaust chimney 4 is communicated with the top end of the smoke detention section 3, and when the pressure is increased sharply due to deflagration and the like in the quick exhaust chimney 4, the quick exhaust chimney 4 can be opened automatically to release the pressure, so that the safe operation of the secondary combustion chamber is ensured.

Based on the combustion method realized by the plasma molten flue gas secondary combustion chamber in the patent, the plasma molten flue gas discharged by the plasma furnace is divided into three stages for treatment: in the limited combustion stage, the sufficient combustion stage and the peroxide retention stage, combustible gas in the flue gas is controlled to be combusted in stages and release heat step by supplying oxygen in stages, so that the risks of overtemperature, overpressure, explosion and the like caused by instantaneous concentrated combustion of the combustible gas are avoided; it specifically comprises the following steps.

S1: in the limited combustion stage, plasma molten flue gas exhausted by the plasma furnace is introduced into the ash hopper 1 from bottom to top through a flue gas inlet 5 of the secondary combustion chamber, the length and the cross section of the ash hopper 1 are designed according to the smoke discharge of the plasma furnace and the flue gas heat capacity of the plasma molten flue gas, so that the flow rate of the flue gas is reduced in the large ash hopper 1, limited combustion is carried out, the temperature of the flue gas is further ensured to be controllable, and the risks of over-temperature, over-pressure, explosion and the like caused by instantaneous centralized combustion of combustible gas are avoided; the settled material generated by the flue gas deceleration in the ash bucket 1 is discharged from a slag discharge port 11 at the bottom of the ash bucket.

Meanwhile, in the ash bucket 1, primary combustion-supporting air is introduced through a primary air inlet device 7, the oxygen content of the primary combustion-supporting air is the oxygen content required by limited combustion of plasma melting flue gas, and in the embodiment, the oxygen content of the primary combustion-supporting air only meets the requirement that the total oxygen demand is less than 50%; the mixing of the first combustion-supporting air reduces the temperature of the flue gas, and on the other hand, a small amount of oxygen is provided to enable combustible substances such as CO and organic matters in the flue gas to be combusted and decomposed in a limited way, so that the problem of safety in use of the device caused by sudden temperature rise due to sufficient combustion is avoided.

S2: in the Venturi section 2, the smoke enters a sufficient combustion stage, the plasma molten smoke from the ash hopper after limited combustion and speed reduction enters the section body of the narrower Venturi section 2 from the wider smoke inlet 2-1 and can accelerate, the smoke with the changed flow rate is more easily and sufficiently mixed with secondary combustion-supporting air, and sufficient secondary combustion is ensured.

And secondary combustion-supporting air is introduced into the plasma molten flue gas with the reduced flow speed through the secondary air inlet device 8, and is high-pressure rotational flow air inlet, so that the plasma molten flue gas and the secondary combustion-supporting air can generate a turbulent flow effect, and the plasma molten flue gas and the combustion-supporting air are fully stirred and mixed for full combustion.

Meanwhile, the cross section of the section body of the Venturi section 2 is smaller than the cross section of the smoke inlet 2-1 at the bottom of the Venturi section and the cross section of the smoke outlet 2-2 at the top of the Venturi section 2, namely, the Venturi section 2 adopts a closing-in structure, so that the disturbance and the mixing area of secondary air can be ensured to be deep into the middle of the section of the secondary combustion chamber, and the mixing of combustion-supporting air and plasma molten smoke is further ensured; in the Venturi section 2, the contact probability of combustible components in the plasma molten flue gas and oxygen is greatly improved, the full combustion and decomposition of combustible materials including CO are facilitated, the air volume of secondary combustion-supporting air is set to ensure that 100% oxygen demand required by combustion energy can be provided, and meanwhile, an auxiliary combustor 10 is arranged on the side face of the Venturi section 2 and can supplement heat required by combustion according to needs.

S3: plasma molten flue gas in combustion is violently mixed in the Venturi section 2, then upwards enters the flue gas retention section 3, and third combustion-supporting air is introduced into the initial section at the lower part of the flue gas retention section 3.

And as the supplement of secondary air, the air volume of the third combustion-supporting air is set to meet the following two points:

the oxygen content of the secondary combustion chamber meets the requirement that the oxygen content at the outlet of the secondary combustion chamber is more than 6 percent;

the total air supply quantity meets the requirement that the temperature of the flue gas at the outlet of the secondary combustion chamber is controlled within the range of 1100-1150 ℃.

In the flue gas retention section 3, the plasma molten flue gas after full combustion enters a peroxide retention stage after combustion, and the flue gas after full mixing with tertiary combustion-supporting air stays at the section for more than 2 seconds at high temperature (more than 1100 ℃), so that combustible components and organic matters are fully burnt out and decomposed.

Meanwhile, tertiary combustion-supporting air is secondary combustion-supporting air which is high-pressure rotational flow air with opposite air inlet rotational directions and is blown into the venturi section 2 from the smoke outlet of the venturi section 2; the third combustion-supporting air is blown downwards and mixed with the second combustion-supporting air, so that the mixing and turbulence effects of the ion melting flue gas, the first combustion-supporting air and the second combustion-supporting air are enhanced, and the more sufficient combustion in the Venturi section 2 is further ensured.

S4: after the peroxy retention stage, the fully combusted flue gas is discharged from a flue gas outlet 6 of a secondary combustion chamber on the side surface of the flue gas retention stage 3, enters a downstream treatment facility, and is discharged to a subsequent tail gas treatment process.

After the technical scheme of this patent is used, the post combustion chamber is mixed effectually, and CO burns out more easily in the flue gas, can ensure that export CO content is up to standard.

Claims

1. A plasma molten flue gas secondary combustion chamber comprises a secondary combustion chamber flue gas inlet connected with a plasma furnace and a secondary combustion chamber flue gas outlet connected with a downstream tail gas treatment device;

2. The plasma molten flue gas secondary combustion chamber of claim 1, wherein: the flue gas is detained the section and is the vertically straight section of thick bamboo structure, second combustion chamber exhanst gas outlet set up in flue gas is detained section top side.

3. The plasma molten flue gas secondary combustion chamber of claim 1, wherein: it still includes: and the quick smoke discharging chimney is communicated with the top end of the smoke retention section.

4. The plasma molten flue gas secondary combustion chamber of claim 1, wherein: a primary air inlet device is arranged on the side wall of the inner cavity of the ash bucket and adopts high-pressure distributed air inlet.

5. The plasma molten flue gas secondary combustion chamber of claim 1, wherein: the tertiary air inlet device adopts a high-pressure distributed cyclone device.