CN104359314B - The energy-saving heating furnace system of a kind of Mist heat recovering and flue gas waste heat recovery method - Google Patents

Abstract

The invention discloses an energy-saving heating furnace system for recovering waste heat of flue gas, which comprises a heating furnace, the heating furnace communicates with a heat exchange unit through a high-temperature flue gas pipeline, and the heat exchange unit is connected with a chimney through a low-temperature flue gas pipeline The heating furnace communicates with the heat exchange unit through the high-temperature air pipeline, and the heat exchange unit communicates with the fan through the low-temperature air pipeline; the heat exchange unit includes an air mixing chamber and a regenerator, and the air mixing chamber There are burners on it, and the burners communicate with air and gas respectively. The invention also discloses a flue gas waste heat recovery method. The system is not only simple in structure, but also can use low calorific value gas for production, thereby reducing the amount of high calorific value gas, energy saving and environmental protection; the system can realize the recycling of waste heat of flue gas, reduce energy loss, and thus save production costs. The method has the advantages of simple process and high feasibility; and the waste heat utilization effect is good.

Description

An energy-saving heating furnace system for recovering waste heat from flue gas and a method for recovering waste heat from flue gas

technical field

The invention relates to waste heat recovery of flue gas in the field of metallurgy, in particular to an energy-saving heating furnace system for recovering waste heat of flue gas and a method for recovering waste heat of flue gas.

Background technique

In the metallurgical industry, furnaces are used to heat metal blanks to be processed. The heating furnace burns fuel, and the high-temperature flue gas generated by fuel combustion flows in the furnace, and the heat is transferred to the metal billet and the furnace wall through the unsteady heat transfer process, and then discharged out of the heating furnace through the exhaust port. The temperature of the flue gas discharged from the heating furnace is relatively high. In the later stage of the heating period and the holding period, the temperature of the flue gas can reach 1100 ℃ ~ 1250 ℃. Recycling and utilizing a large amount of physical latent heat contained in it is a key technology to improve the thermal efficiency of the heating furnace.

At present, three technologies are mainly used for waste heat recovery of heating furnace flue gas. One is to use metal air preheater to recover waste heat from flue gas; the other is to apply regenerative burners; the third is to use waste heat boiler to generate electricity. The metal air preheater occupies a large area, the preheating temperature of the air is between 350°C and 450°C, and the temperature after recovery of flue gas waste heat is between 500°C and 600°C, and the utilization rate of flue gas waste heat recovery is the lowest. The regenerative burner is a regenerative combustion technology that has emerged recently. It can heat the air up to 1000°C, and the flue gas discharge temperature is about 150°C. It has a very high recovery rate for the waste heat of the flue gas. However, the regenerative burner needs a fast switching device to match it, and it needs to be switched every few minutes, which requires high equipment level and control level, and because the temperature of the flue gas in the furnace is low in the early stage of heating up, the preheating temperature of the air is also relatively high. Low, high calorific value gas must be used as fuel for rapid heating of metal blanks, and the operating cost is high. Waste heat boiler power generation is also applied to the heating furnace of some iron and steel enterprises. The method is to install an evaporator on the flue gas pipeline to produce supersaturated steam, and use the supersaturated steam to drive the steam turbine to work, thereby realizing power generation. The flue gas volume and flue gas temperature are not constant and have the characteristics of discontinuity. Therefore, this method has its limitations in application, and has the disadvantages of large investment and small profit.

Therefore, we urgently need a new flue gas waste heat recovery and utilization system to solve the defects of large investment and high cost of the existing flue gas waste heat recovery system.

Contents of the invention

The object of the present invention is to provide an energy-saving heating furnace system and a flue gas waste heat recovery method for recovering flue gas waste heat. The system has a simple structure, can efficiently recover flue gas waste heat, and effectively reduce the cost of flue gas waste heat recovery; the flue gas recovery method It can use gas with low calorific value, reduce the consumption of gas with high calorific value, and save energy and protect the environment.

The invention provides an energy-saving heating furnace system for recovering waste heat of flue gas, which includes a heating furnace, the heating furnace communicates with a heat exchange unit through a high-temperature flue gas pipeline, and the heat exchange unit communicates with a chimney through a low-temperature flue gas pipeline The heating furnace communicates with the heat exchange unit through the high-temperature air pipeline, and the heat exchange unit communicates with the fan through the low-temperature air pipeline; the heat exchange unit includes an air mixing chamber and a regenerator, and the air mixing chamber A burner is provided, and the burner communicates with air and gas respectively;

There are more than two heat exchange units.

The present invention also provides a method for recovering the waste heat of the flue gas by adopting an energy-saving heating furnace system for recovering the waste heat of the flue gas, which includes the following steps:

Step 1. High-temperature air is sprayed from the air chamber nozzle in the heating furnace and mixed with the gas transported by the gas pipeline to form a fire curtain to heat up the metal blank;

Step 2. The high-temperature flue gas discharged from the heating furnace enters the mixed air chamber and the regenerator to be stored through the high-temperature flue gas pipeline. Mixed flue gas, the mixed flue gas enters the heat storage chamber and exchanges heat with the heat storage body to lower the temperature of the mixed flue gas, then enters the chimney through the low-temperature flue gas pipe, and is discharged into the atmosphere;

Step 3: The air pressurized by the fan enters the heat-storing mixing chamber and regenerator through the low-temperature air pipeline, and heat exchange with the regenerator in the regenerating chamber is heated to high-temperature air, and the high-temperature air passes through the mixing chamber And the high-temperature air pipe enters the air chamber in the heating furnace.

According to the above-mentioned scheme, the steps 1 to 3 are repeated and circulated.

According to the above scheme, in step 2, the temperature of the mixed flue gas is 900°C~1250°C.

According to the above scheme, in step 2, the mixed flue gas enters the regenerator chamber and exchanges heat with the regenerator to lower the temperature of the mixed flue gas to below 180°C.

According to the above scheme, in step 3, the high temperature air is 800°C~1100°C.

In the present invention, the high-temperature flue gas discharged from the heating furnace enters the air-mixing chamber through the high-temperature flue gas pipeline, mixes with the flue gas generated by the burner combustion in the air-mixing chamber, and then enters the regenerator. Through the low-temperature flue gas pipe, it enters the chimney and is discharged into the atmosphere. After the air is pressurized by the fan, it enters the heat storage chamber through the low-temperature air pipe, and the low-temperature air is heated by the regenerator, and then enters the air chamber in the heating furnace through the high-temperature air pipe, and is mixed with the gas after being sprayed out from the air nozzle. Combustion forms a fire curtain to heat up the metal blank.

The energy-saving heating furnace system for recovering flue gas waste heat in the present invention not only has a simple structure, but also can use low calorific value gas for production due to the high air preheating temperature, so that less or no high calorific value gas can be used, which is energy-saving and environmentally friendly; The system can realize the recycling of flue gas waste heat, reduce energy loss, and thus save production costs; the system accurately controls the temperature in the air mixing chamber and heat storage chamber through the detection controller, thereby ensuring the safety and smooth progress of production; the whole system is simple to manufacture , small footprint, suitable for popularization and application of flue gas waste heat recovery and utilization in all metallurgical fields. The flue gas waste heat recovery method in the present invention has simple process, high feasibility, and good waste heat utilization effect.

Description of drawings

Fig. 1 is a schematic structural diagram of an energy-saving heating furnace system for recovering waste heat from flue gas according to the present invention.

Figure 2 is a schematic structural view of the heating furnace.

Fig. 3 is a view along the direction A in Fig. 2 .

In the figure: 1. heating furnace, 2-1, high temperature flue gas pipeline, 2-2, low temperature flue gas pipeline, 3-1, low temperature air pipeline, 3-2 high temperature air pipeline, 4, gas pipeline, 5, mixed air Chamber, 6, regenerator, 7, chimney, 8, fan, 10, burner, 11, furnace, 12, air chamber, 13, air nozzle, 14, air inlet.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings.

Referring to Figures 1-3, an energy-saving heating furnace system for recovering waste heat from flue gas, it includes a heating furnace 1, the heating furnace 1 is sequentially connected with a high-temperature flue gas pipeline 2-1, a heat exchange unit, and a low-temperature flue gas pipeline 2- 2. The chimney 7 is connected; the heating furnace 1 is connected with the high-temperature air pipe 3-2, the heat exchange unit, the low-temperature air pipe 3-1, and the fan 8 in sequence.

More than two heat exchange units can be used. In this embodiment, there are two heat exchange units; each heat exchange unit includes an air mixing chamber 5 and a heat storage chamber 6, and the air mixing chamber 5 A burner 10 is provided, and the burner 10 communicates with air and gas respectively; a detection controller is provided on the air and gas pipeline, and the detection controller includes a flow detection unit and a flow adjustment unit to adjust the flow rate entering the burner. Air and gas flow.

The heating furnace 1 includes a furnace hearth 11 and air chambers 12 located on both sides of the furnace hearth 11, the furnace hearth 11 and the air chamber 12 are connected through an air nozzle 13; the air nozzle 13 is at an angle of 0° to 45° with the horizontal direction . The air chamber 12 communicates with the high-temperature air pipeline 3-2 through the air inlet 14, and the heating furnace communicates with the gas pipeline 4. The coal gas in the gas pipeline 4 is mixed with the high-temperature air ejected from the air chamber 12 to generate high temperature. After the flue gas heats the metal blank, it is transported to the air mixing chamber 5 of the heat exchange unit through the high-temperature flue gas pipeline 3-1.

The high-temperature flue gas in the air mixing chamber 5 is mixed with the flue gas burned by the burner 10 to form a mixed flue gas at 900°C~1250°C, and the mixed flue gas exchanges heat with the regenerator in the regenerator 6, so that the mixed flue gas After the temperature drops below 180°C, it is discharged through the low-temperature flue gas pipeline 2-2 and the chimney 7. The fan 8 pressurizes the air and transports it to the regenerator 6 through the low-temperature air pipeline 3-1, and exchanges heat with the regenerator in the regenerator 6, so that the air temperature rises to 800°C~1100°C, and then This high-temperature air enters the air chamber of the heating furnace 1 through the air mixing chamber 5 and the high-temperature air pipeline 3-2.

In this embodiment, the regenerator in the regenerator chamber 6 is composed of refractory balls or perforated bricks.

In this embodiment, the chimney 7 communicates with the regenerator 6 of the heat exchange unit through the low-temperature flue gas pipeline 2-2; the low-temperature flue gas pipeline 2-2, the high-temperature flue gas pipeline 2-1, the low-temperature flue gas pipeline Air pipe 3-1, high-temperature air pipe 3-2, gas pipe, and air intake pipe are all provided with valves to control the air intake respectively; The monitoring system is used to control the temperature of the heat exchange unit to ensure the smooth progress of production; the low-temperature air pipeline 3-1 is also provided with a flow detection and flow adjustment unit to control the air intake.

For better heat exchange, the air chamber 12 can be arranged around the furnace 11, and the air mixing chamber 5 can be placed on the upper part of the heat storage chamber 6 (this application is not limited to this arrangement). In order to ensure the smooth progress of production, the energy-saving heating furnace system for recovering flue gas waste heat also includes a detection controller. The detection controller adjusts the flow rate of heating furnace gas and high-temperature air according to the heating furnace heating speed.

This embodiment also relates to a method for recovering waste heat of flue gas using the energy-saving heating furnace system for recovering waste heat of flue gas, which specifically includes the following steps:

Step 1. High-temperature air is sprayed from the air chamber nozzle in the heating furnace 1 and mixed with the gas transported by the gas pipeline 4 to form a fire curtain to heat up the metal blank;

Step 2: The high-temperature flue gas discharged from the heating furnace 1 enters the mixed air chamber 5 and the regenerator 6 to be stored through the high-temperature flue gas pipe 2-1. The high-temperature flue gas discharged from the furnace 1 is mixed into a mixed flue gas with a temperature of 900 ° C ~ 1250 ° C, and the mixed flue gas enters the regenerator 6 to exchange heat with the regenerator to reduce the temperature of the mixed flue gas to below 180 ° C. Then enter the chimney 7 through the low-temperature flue gas pipeline 2-2, and be discharged into the atmosphere;

Step 3: The air pressurized by the fan 8 enters the heat-storing mixed air chamber 5 and the heat storage chamber 6 through the low-temperature air pipe 3-1, and heat exchange with the heat storage body in the heat storage chamber 6 is heated to a temperature It is high-temperature air at 800°C~1100°C, and the high-temperature air enters the air chamber in the heating furnace 1 through the air mixing chamber 5 and the high-temperature air pipe 3-2;

Step 4, the steps 1 to 3 are repeated and circulated.

In the present invention, an air chamber is designed in the heating furnace 1, and high-temperature air is ejected from the nozzle of the air chamber and mixed with the gas transported by the gas pipeline 4 to form a fire curtain to heat up the metal blank. The air mixing chamber 5 and the heat storage chamber 6 are designed in groups, generally 2 groups, which alternately store heat and release heat. The heating furnace 1 communicates with two groups of air mixing chamber 5, regenerator 6 and chimney 7 through flue gas pipes, and communicates with two groups of air mixing chamber 5, regenerator 6 and fan 8 through air pipes. The high-temperature flue gas discharged from the heating furnace 1 enters the mixed air chamber 5 and the regenerator 6 to be stored in it through the high-temperature flue gas pipe 2-1. The high-temperature flue gas is mixed into a mixed flue gas with a temperature of 900°C~1250°C. The mixed flue gas then enters the regenerator 6 to be stored for heat exchange and the temperature drops below 180°C. The flue gas pipe 2-2 enters the chimney 7 and is discharged into the atmosphere. The air pressurized by the fan 8 enters the mixed air chamber 5 and the regenerator 6 which have stored heat through the low-temperature air pipe 3-1, and is heated to 800°C in the heat exchange with the regenerator in the regenerator 6. At 1100°C, high-temperature air enters the air chamber in the heating furnace 1 through the air mixing chamber 5 and the high-temperature air pipe 3-2. The air and gas flow of the system is adjusted through the detection and control system.

Claims (3)

1. An energy-saving heating furnace system for recovering flue gas waste heat, which includes a heating furnace, characterized in that: the heating furnace communicates with the heat exchange unit through a high-temperature flue gas pipeline, and the heat exchange unit communicates with the heat exchange unit through a low-temperature flue gas pipeline. The chimney is connected; the heating furnace is connected with the heat exchange unit through the high temperature air pipe, and the heat exchange unit is connected with the fan through the low temperature air pipe; the heat exchange unit includes an air mixing chamber and a regenerator, and the mixing The air chamber is provided with burners, and the burners communicate with air and gas respectively; There are more than two heat exchange units; The heating furnace includes a furnace and air chambers located on both sides of the furnace, the furnace and the air chamber are connected through an air nozzle; the air nozzle is at an angle of 0° to 45° with the horizontal direction; The system also includes a detection controller, which adjusts the gas and air flow rate of the burner in the mixing chamber according to the temperature of the mixed flue gas in the mixing chamber, and the detection controller adjusts the gas and high temperature of the heating furnace according to the heating speed of the heating furnace. air flow. 2. The energy-saving heating furnace system for recovering flue gas waste heat according to claim 1, characterized in that: the regenerator in the regenerator chamber is composed of refractory balls or perforated bricks. 3. A method for recovering flue gas waste heat using any energy-saving heating furnace system for recovering flue gas waste heat in claim 1-2, characterized in that it comprises the following steps: Step 1. High-temperature air is sprayed from the air chamber nozzle in the heating furnace and mixed with the gas transported by the gas pipeline to form a fire curtain to heat up the metal blank; Step 2. The high-temperature flue gas discharged from the heating furnace enters the mixed air chamber and the regenerator to be stored through the high-temperature flue gas pipeline. Mixed flue gas, the mixed flue gas enters the heat storage chamber and exchanges heat with the heat storage body to lower the temperature of the mixed flue gas, then enters the chimney through the low-temperature flue gas pipe, and is discharged into the atmosphere; Step 3: The air pressurized by the fan enters the heat-storing mixing chamber and regenerator through the low-temperature air pipeline, and heat exchange with the regenerator in the regenerating chamber is heated to high-temperature air, and the high-temperature air passes through the mixing chamber and high-temperature air ducts enter the air chamber in the heating furnace; The steps 1 to 3 are repeated and circulated; In step 2, the temperature of the mixed flue gas is 900°C~1250°C; In step 2, the mixed flue gas enters the regenerator chamber and exchanges heat with the regenerator to lower the temperature of the mixed flue gas to below 180°C; In step 3, the high-temperature air is 800°C to 1100°C.