CN203772039U - Purification system with combination of utilization of waste heat of flue gas in electric furnace and efficient filtration - Google Patents

Abstract

The utility model discloses a purification system with combination of utilization of waste heat of flue gas in an electric furnace and efficient filtration. The system comprises the electric furnace, a flue gas treatment device, a dust removing device, a main blower and a chimney which are sequentially communicated through pipelines, wherein the flue gas treatment device comprises a high-temperature flue gas treatment segment and a medium- temperature and low-temperature flue gas treatment segment; the flue gas which is treated by the high-temperature flue gas treatment segment is introduced into the medium-temperature and low-temperature flue gas treatment segment to be treated; the temperature of the flue gas is not less than 450 DEG C after the flue gas is treated by the high-temperature flue gas treatment segment; the temperature of the flue gas is not greater than 250 DEG C after the flue gas is treated by the medium-temperature and low-temperature flue gas treatment segment. According to the system, the flue gas in the electric furnace is treated in different temperature areas, wherein in the high-temperature area, the upper limit temperature is 450 DEG C at which dioxin cannot be synthesized again, so that the resynthesis of the dioxin is avoided; in the medium- temperature and low-temperature area, the flue gas can be rapidly cooled to reach below the lower limit temperature of 250 DEG C at which the dioxin is synthesized again, so that the resynthesis of the dioxin is also avoided. Thus, the system disclosed by the utility model can be used for utilizing the waste heat of the flue gas as well as inhibiting the resynthesis of the dioxin, thereby decreasing the discharge of the dioxin.

Description

Combined purification system of electric furnace flue gas waste heat utilization and high-efficiency filtration

technical field

The invention belongs to the field of electric furnace flue gas waste heat utilization and purification equipment, in particular to a combined purification system for electric furnace flue gas waste heat utilization and high-efficiency filtration.

Background technique

Existing electric furnace flue gas dioxin emission reduction technologies can be roughly divided into two categories: source generated dioxin emission reduction technologies and generated dioxin emission reduction technologies. Source emission reduction technology is to eliminate the conditions for dioxin formation at the source, which can be achieved by means of sorting raw materials into the furnace, process control of feeding process, rapid cooling of flue gas with water, and spraying of flue gas with alkaline inhibitors. Dioxins can be reduced by 80% to 95%. The generated dioxin emission reduction technologies can be divided into four categories: high-efficiency filtration technology, activated carbon adsorption technology, catalytic filtration Remedia technology and other technologies. High-efficiency filtration technology utilizes the characteristic that most of dioxins are adsorbed on the surface of soot in solid form under low temperature conditions, and reduces dioxin emissions through high-efficiency dust collectors. Activated carbon adsorption technology is divided into two processes. One process is to spray activated carbon powder in front of the bag filter to absorb dioxins in the flue gas, and then remove them through the bag filter to reduce dioxin emissions. In this method, the gas phase dioxins in the flue gas have less chance of contacting and being adsorbed by the activated carbon, and the dust cleaning cycle of the bag filter is short, the residence time of the activated carbon on the bag is short, the utilization rate of the activated carbon is low, and the dioxin removal effect is limited; One technique is to set up a fixed-bed activated carbon adsorption device. The investment cost of this technique is relatively high, and there is a possibility of explosive combustion if the design of the electric furnace flue gas is unreasonable. The Catalytic Filtration Remedia technology was pioneered by Gore in the United States. It integrates surface filtration technology and catalytic filtration technology on the filter bag, and can completely decompose dioxins into CO, H2O and HCl and dioxin are completely removed without secondary pollution. This technology is more suitable for electric furnace flue gas, and is suitable for the technical transformation of the existing bag filter. It only needs to replace the filter bag and can meet the emission requirements of dioxin. However, the filter bag is expensive, the life of the catalyst is not long, the replacement of the filter bag is frequent, and the operating cost is relatively high. For other purification methods that have generated dioxin fumes, the core technology is catalysis + decomposition technology, such as selective catalytic reaction technology (SCR), electron beam decomposition technology, photocatalytic technology, etc. Most of these technologies are still in the research and development stage However, there are generally problems such as high investment costs, large and complex devices, and low operating life, and large-scale industrial applications are still immature. Flue gas quenching technology has disadvantages such as high operating cost, water consumption, and waste heat of flue gas that is not recycled and utilized. It reduces emissions but does not save energy. At present, although there is a treatment process that first recovers the waste heat of the flue gas through the waste heat boiler, and then purifies it through the bag filter, this treatment process generally does not consider the reduction of dioxin emissions.

Contents of the invention

In view of this, the purpose of the present invention is to provide a combined purification system of electric furnace flue gas waste heat utilization and high-efficiency filtration, which can not only utilize electric furnace flue gas waste heat but also inhibit the resynthesis of dioxins, thereby significantly reducing the emission of dioxins .

The purpose of the present invention is achieved through the following technical solutions:

A system for combined purification of electric furnace flue gas waste heat utilization and high-efficiency filtration, including an electric furnace, a flue gas treatment device, a dust removal device, a main fan, and a chimney connected in sequence through pipelines. The flue gas treatment device includes a high-temperature flue gas treatment section and Medium and low temperature flue gas treatment section, the flue gas treated in the high temperature flue gas treatment section is introduced into the medium and low temperature flue gas treatment section for treatment, the temperature of the flue gas treated in the high temperature flue gas treatment section is not lower than 450°C, The temperature of the flue gas treated by the medium and low temperature flue gas treatment section is not higher than 250°C;

Further, the high-temperature flue gas treatment section uses a high-pressure waste heat boiler to recover waste heat from the flue gas;

Further, the temperature of the flue gas treated in the high-temperature flue gas treatment section is 500°C;

Further, the medium and low temperature flue gas treatment section uses a medium pressure heat pipe waste heat boiler to recover waste heat from the medium and low temperature flue gas or uses spray cooling to cool the medium and low temperature flue gas;

Further, the dust removal device adopts a bag filter, and the bag filter uses a high-efficiency film-coated filter material and performs secondary flue gas mixed air treatment.

The beneficial effects of the present invention are: the present invention treats the flue gas of the electric furnace in different temperature zones. In the high temperature zone, because the upper limit temperature of dioxin resynthesis is 450°C, there will be no dioxin resynthesis. In the medium and low temperature zone, it can Rapidly cool the flue gas to the lower limit temperature of dioxin resynthesis below 250°C, so there will be no resynthesis of dioxins. Therefore, the present invention can not only utilize the waste heat of flue gas but also inhibit the resynthesis of dioxins, thereby reducing Dioxin emissions.

Other advantages, objects and features of the present invention will be set forth in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the investigation and research below, or can be obtained from Taught in the practice of the present invention. The objects and other advantages of the invention may be realized and attained by the following specification.

Description of drawings

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic structural view of Embodiment 1 of the present invention;

Fig. 2 is a schematic structural diagram of Embodiment 2 of the present invention.

Detailed ways

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the preferred embodiments are only for illustrating the present invention, but not for limiting the protection scope of the present invention.

As shown in Fig. 1 , the combined purification system of electric furnace flue gas waste heat utilization and high-efficiency filtration in Embodiment 1 includes electric furnace 1, flue gas treatment device 2, dust removal device 3, main fan 4 and chimney 5 connected in sequence through pipelines, The flue gas treatment device includes a high temperature flue gas treatment section 21 and a medium and low temperature flue gas treatment section 22. The flue gas treated in the high temperature flue gas treatment section is introduced into the medium and low temperature flue gas treatment section for treatment. The temperature of the flue gas treated in the gas treatment section is not lower than 450°C, and the temperature of the flue gas treated in the medium-low temperature flue gas treatment section is not higher than 250°C.

In this embodiment, the high-temperature flue gas treatment section uses a high-pressure waste heat boiler to recover waste heat from the flue gas, and the temperature of the flue gas after treatment in the high-temperature flue gas treatment section is set at 500°C; the medium-low temperature flue gas treatment section A medium-pressure heat pipe waste heat boiler is used to recover waste heat from the medium and low temperature flue gas, and the outlet flue gas is set at 210°C. Existing high-pressure waste heat boilers and medium-pressure heat pipe waste heat boilers are all mature technologies, and the correct selection of equipment according to specific flue gas parameters can meet the requirements of rising parameter settings.

In this embodiment, high-temperature waste heat boilers are used to recover flue gas heat for high-temperature flue gas above 500°C. In this temperature range, the heat transfer temperature difference is large, and the radiant heat of flue gas can be effectively used, and the comprehensive heat transfer efficiency is high; The low-temperature section adopts a medium-pressure heat pipe waste heat boiler to recover the heat of the flue gas in the low-temperature section, and makes full use of the rapid heat transfer properties of the phase change medium of the heat pipe waste heat boiler, which can also maintain a high heat transfer efficiency. Therefore, the integration of the two technologies enables the temperature to drop to about 210°C quickly with less heating area of the boiler. The advantage of this embodiment is that it can not only effectively reduce the resynthesis of dioxins, but also recover almost all available flue gas waste heat.

In this embodiment, the flue gas is finally purified by the bag filter, which uses high-efficiency film-coated filter material and a low filtering wind speed, which can ensure that the concentration of particulate matter at the flue gas outlet is below 10mg/m3 and minimize The emission of dioxin is more suitable for electric furnaces with a large flue gas volume of more than 50 tons.

Fig. 2 is a system for combined purification of electric furnace flue gas waste heat utilization and high-efficiency filtration in Example 2 of the present utility model. The flue gas is spray cooled.

In this embodiment, dual-medium high-pressure spray gun spray is used to quench the flue gas, and the three-impulse closed-loop automatic control technology of inlet and outlet flue gas temperature, flue gas flow rate, and water spray volume is used to realize precise adjustment of the water spray volume, so that the flue gas When the temperature drops below 200°C, ensure that the flue gas is above the dew point of the flue gas to ensure that the subsequent bag filter does not stick to the bag and operates safely.

The nozzle in this embodiment is set at the tail of the waste heat boiler, and the flue gas is rapidly cooled to below 200°C by evaporative cooling. This small part of the heat of the flue gas is not recovered, which can reduce the investment of the waste heat boiler and significantly reduce the risk of resynthesis of dioxins ; At the same time, the amount of water sprayed per square meter of flue gas is also greatly reduced, roughly calculated to be about 1/6 of the water consumption of traditional flue gas quenching, and the comprehensive economic and environmental benefits are obvious. The advantage of this embodiment is that it can effectively reduce the resynthesis of dioxins, the one-time investment is less, the system is simple, and the energy consumption is low; it is more suitable for the transformation of an electric furnace with a small flue gas volume below 50 tons or an existing electric furnace.

In this embodiment, the flue gas is finally purified by the bag filter, which uses high-efficiency film-coated filter material and adopts a low filtration wind speed (controlled below 0.8m/min). In order to ensure the safety of the bag filter and the elimination of particulate matter and dioxins in the secondary flue gas of the electric furnace, measures for mixing the secondary flue gas have also been taken.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements, without departing from the spirit and scope of the technical solution, should be included in the scope of the claims of the present invention.

Claims (5)

1. A system for combined purification of electric furnace flue gas waste heat utilization and high-efficiency filtration, comprising an electric furnace, a flue gas treatment device, a dust removal device, a main fan and a chimney connected in sequence through pipelines, characterized in that: the flue gas treatment device includes A high-temperature flue gas treatment section and a medium-low temperature flue gas treatment section, the flue gas treated in the high-temperature flue gas treatment section is introduced into the medium-low temperature flue gas treatment section for treatment, and the temperature of the flue gas treated in the high-temperature flue gas treatment section is It is not lower than 450°C, and the temperature of the flue gas after the treatment in the middle and low temperature flue gas treatment section is not higher than 250°C. 2. The system for combined purification of electric furnace flue gas waste heat utilization and high-efficiency filtration according to claim 1, characterized in that: the high-temperature flue gas treatment section uses a high-pressure waste heat boiler to recover waste heat from the flue gas. 3. The system for combined purification of electric furnace flue gas waste heat utilization and high-efficiency filtration according to claim 1, characterized in that the temperature of the flue gas after treatment in the high-temperature flue gas treatment section is 500°C. 4. The system for combined purification of electric furnace flue gas waste heat utilization and high-efficiency filtration according to claim 1, characterized in that: the medium and low temperature flue gas treatment section adopts a medium pressure heat pipe waste heat boiler to recover the waste heat of the medium and low temperature flue gas or The medium and low temperature flue gas is cooled by spray cooling. 5. The system for combined purification of electric furnace flue gas waste heat utilization and high-efficiency filtration according to claim 1, characterized in that: the dust removal device adopts a bag filter, and the bag filter uses a high-efficiency film-coated filter material and performs secondary Flue gas mixed air treatment.