Recycling system for waste heat of nonferrous smelting waste gas

Abstract

The utility model discloses a non-ferrous smelting waste gas waste heat recycling system which comprises a high-temperature-resistant dust remover and a two-section type heat exchanger, the high-temperature-resistant dust remover is arranged at the front end of the heat exchanger, and hot flue gas from a medium-temperature medium-pressure waste heat boiler directly enters the high-temperature-resistant dust remover through a pipeline. Hot flue gas after dust removal enters a shell pass of the two-section type flue gas heat exchanger and exchanges heat with water reversely flowing in a tube pass of the heat exchanger, generated saturated steam enters a steam pocket arranged at the top of the heat exchanger, the steam pocket is connected with a user side through a pipeline, and the tube pass of the heat exchanger is connected with a circulating water system. The flue gas waste heat recovery device effectively solves the problems of dust deposition, hardening and corrosion of a traditional technical route, realizes efficient recovery and utilization of flue gas waste heat, and brings remarkable economic and social benefits.

Description

Technical Field

[0001] This utility model belongs to the field of waste heat recovery technology of smelting waste gas, and particularly relates to a waste heat recovery system for non-ferrous smelting waste gas. Background Technology

[0002] In recent years, my country's lead and zinc smelting industry has achieved large-scale development. After years of exploration and progress, lead and zinc smelting technology has reached an advanced level. However, the high energy consumption problem that has long existed in my country's non-ferrous metals industry remains very prominent. Data shows that the energy consumption per unit of product in my country's non-ferrous metals industry is about ten percentage points higher than the international advanced level. In the energy consumption composition of non-ferrous metallurgy, effective heat accounts for only 32%, another 8% of the heat is lost through furnace walls, etc., and the remaining 60% is the waste heat in the non-ferrous metal smelting process. Among these waste heat, the proportion of flue gas waste heat is as high as about 80%. It can be seen that recovering the waste heat of flue gas in the non-ferrous metallurgical industry is of great significance for reducing the energy consumption of the non-ferrous metallurgical industry. At present, the more common methods for recovering and utilizing the waste heat of flue gas from non-ferrous furnaces and kilns include: installing waste heat boilers in the flue to produce steam, using waste heat to generate electricity, using waste heat to preheat air or materials, installing vaporization water jackets to produce low-pressure steam, or installing cooling water jackets to produce hot water, etc. Moreover, the recovery of waste heat from flue gas in non-ferrous furnaces and kilns mainly targets high-temperature flue gas.

[0003] In the smelting process, the product enters the cooling line for cooling, generating a large amount of medium- and low-temperature waste heat gas emissions. After passing through the waste heat boiler, the emission temperature of this waste gas remains above 300℃ for most of the year. This portion of medium- and low-temperature flue gas waste heat accounts for about half of the total flue gas waste heat, and the particulate matter concentration is very high, generally above 40g / m³. The existing technical route first requires passing the product through a surface cooler, where it is cooled by air before entering the bag filter for treatment. Not only is this heat not fully utilized and is wasted, but the surface cooler also suffers from severe ash accumulation, caking, and corrosion during operation, leading to serious equipment damage in this process and high operating, maintenance, and repair costs. Utility Model Content

[0004] To address the aforementioned problems, this utility model proposes a waste heat recovery system for non-ferrous smelting waste gas. The aim is to solve the problems in the existing technology where the waste heat from low-temperature flue gas is insufficient and wasted, and where the surface coolers of the system equipment suffer from severe ash accumulation and caking during operation, resulting in serious equipment damage in this process and high operating, maintenance, and repair costs.

[0005] This utility model is implemented as follows:

[0006] A waste heat recovery system for non-ferrous smelting waste gas includes a dust collector installed at the front end of a heat exchanger. Hot flue gas from a medium-temperature and medium-pressure waste heat boiler enters the dust collector directly through a pipeline. After dust removal, the hot flue gas enters the shell side of a two-stage flue gas heat exchanger, where it exchanges heat with water flowing counter-currently in the tube side of the heat exchanger. The resulting saturated steam enters a steam drum located at the top of the heat exchanger. The steam drum is connected to the user end through a pipeline, and the tube side of the heat exchanger is connected to a circulating water system.

[0007] Furthermore, the two-stage heat exchanger includes an evaporation section and a heating section, wherein the heat exchange area of ​​the evaporation section is 1.2 to 1.4 times that of the heating section.

[0008] Furthermore, the shell-side length of the heat exchanger is 5 to 6 meters.

[0009] Furthermore, the tubes of the heat exchanger are arranged in staggered or sequential rows internally.

[0010] Furthermore, the dust collector is equipped with a jet cleaning device at the top and an ash conveying device at the bottom, and the ash conveying device is equipped with a fluidized heat exchanger inside.

[0011] Furthermore, the circulating water system is equipped with a soft water tank, the inlet of the heating section is connected to the soft water tank, and the outlet of the evaporation section is connected to the circulating water system through the fluidized heat exchanger.

[0012] Furthermore, the filter bags of the dust collector are made of high-temperature resistant metal or ceramic materials, with a length of 4 meters or 6 meters, and are suspended at the top of the tube sheet inside the dust collector housing.

[0013] Furthermore, the heat exchanger is equipped with water temperature and flow sensors, which can transmit monitoring data to the control system in real time.

[0014] Furthermore, the condensate generated by the steam drum is connected to the tube side of the heating section via a pipeline.

[0015] Furthermore, the connecting pipelines between the various devices in the system are insulated.

[0016] The beneficial effects of this utility model are:

[0017] This innovative approach places the high-temperature dust collector before the heat exchanger, removing dust before cooling, thus changing the traditional process of cooling before dust removal. This reduces the amount of solid particles entering the flue gas from the heat exchanger, preventing blockage and caking in subsequent equipment, especially the surface coolers which suffer severe dust accumulation and caking during operation, leading to serious equipment damage in this stage. This technological change reduces maintenance costs for this stage of equipment by at least 30%, improves system stability, and reduces environmental pollution. Simultaneously, in conjunction with a two-stage heat exchanger, the flue gas in the shell side and the circulating water in the tube side undergo counter-current heat exchange in an evaporation section and a heating section, gradually transferring the heat from the smelting waste gas to the hot water. This improves the efficiency of heat recovery from the smelting waste gas, maximizing the utilization of waste heat and reducing heat waste. The produced steam can be supplied not only to industrial users but also used for power generation, achieving multi-functional utilization of waste heat.

[0018] In addition to the waste heat of hot flue gas, this invention also makes full use of the waste heat of high-temperature ash, maximizing the utilization of waste heat energy. The generation of more saturated steam enhances the full utilization of thermal energy, reduces additional energy consumption, lowers production costs, further improves the overall economic efficiency and resource utilization of the system, and further reduces the production cost of non-ferrous metal smelting.

[0019] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0020] Figure 1 A schematic diagram of the system connection relationship of this utility model;

[0021] Figure 2 This utility model's workflow diagram.

[0022] In the picture, 11 is a high-temperature dust collector;

[0023] 12 Heat exchanger, 121 Shell side, 122 Tube side, 123 Evaporation section, 124 Heating section, 125 Steam outlet, 126 Water inlet, 127 Water outlet;

[0024] 13 Circulating water pump, 14 Soft water tank, 15 Steam drum, 16 Ash conveying device, 17 Pulse jet cleaning device, 18 Air supply end, 19 Flue gas temperature and flow detector, 20 Water temperature and flow sensor. Detailed Implementation

[0025] This embodiment is a waste heat recovery system for non-ferrous smelting waste gas, including a medium-temperature and medium-pressure waste pressure boiler and control system, a high-temperature dust collector 11, a flue gas heat exchanger 12, a circulating pump 13, a soft water tank 14, a steam drum 15, an ash conveying device 16, a pulse-jet cleaning device 17, and a gas consumption terminal 18, etc. Figure 1 As shown.

[0026] After the hot flue gas from the medium-temperature and medium-pressure waste heat boiler exits, it enters the high-temperature bag filter 11 directly through a pipeline. The hot flue gas after dust removal enters the shell side 121 of the two-stage flue gas heat exchanger 12. The two-stage heat exchanger 12 includes an evaporation section 123 and a heating section 124. The saturated steam outlet 125 of the evaporation section 123 is connected to a steam drum 15. The condensate generated in the steam drum 15 is introduced into the tube side of the heating section 124. The steam drum 15 is connected to the user terminal 18 through a pipeline.

[0027] The tube side 122 of the heat exchanger 12 is connected to a circulating water system, which includes a circulating water pump 13 and a soft water tank 14. The inlet 126 of the heating section 124 is connected to the soft water tank 14, and the outlet 127 of the evaporation section 123 is connected to the ash conveying device 16. The circulating water system is closed, and the soft water tank 14 can be used to replenish the water volume reduced by the discharged steam, or to provide all the water required for startup.

[0028] The heat exchanger 12 is equipped with a flue gas temperature and flow detector 19 on the flue gas inlet pipe, and the heat exchanger 12 is equipped with a water temperature and flow sensor 20, which can transmit monitoring data to the control system in real time. The control system can adjust the system operation according to the flue gas entering the heat exchanger 12 and the circulating water in the heat exchanger, so as to meet the requirements of generating saturated low-pressure steam and cooling the flue gas to about 140°C.

[0029] The specific dimensions of the shell side 121 of the heat exchanger 12 can be calculated and customized according to the on-site flue gas velocity and site conditions. The circulating water in the tube side 122 flows counter-currently to the hot flue gas in the shell side 121. The tube side 122 is arranged in staggered or parallel rows inside the heat exchanger 12 to allow the softened water to flow in the pipes and fully contact the waste heat flue gas. The tube side 122 is made of acid-resistant and wear-resistant material. In this preferred embodiment, the total length of the shell side 121 of the heat exchanger 12 is 5 to 6 meters, the heat exchange area of ​​the evaporation section 123 is 1.2 to 1.4 times the heat exchange area of ​​the heating section 124, and the flue gas velocity is 2 to 4 m / s.

[0030] The filter bags of the high-temperature dust collector 11 are made of either high-temperature resistant metal or ceramic materials, with a length of 4 meters or 6 meters. They are suspended at the top of the tube sheet inside the dust collector 11 shell for easy installation and maintenance. Hot flue gas enters the dust collector 11 directly from the outlet of the medium-temperature and medium-pressure waste heat boiler. The top of the high-temperature dust collector 11 is designed with a preheating jet cleaning device 17. The compressed air used for cleaning is preheated and then sprayed into the dust collector 11 through a jet valve to blow off the dust adhering to the inner wall of the dust collector 11.

[0031] The blown-off dust falls into the ash conveying device 16 below. The ash conveying device 16 is equipped with a fluidized heat exchanger, which has a heat recovery function. It can recover the heat of the high-temperature dust and use the recovered heat energy to exchange heat with the water in the circulating water system, so as to make full use of the heat energy of the high-temperature dust.

[0032] The working principle and usage of this utility model are as follows:

[0033] Hot flue gas from the outlet of the medium-temperature and medium-pressure waste heat boiler is directly introduced into a high-temperature resistant bag filter 11 for dust removal. The outlet of the dust collector 11 is connected to the shell side 121 of a two-stage flue gas heat exchanger 12. The hot flue gas from the dust collector 11 exchanges heat with the circulating water flowing counter-currently in the tube side 122 of the flue gas heat exchanger 12. The two-stage flue gas heat exchanger 12 includes an evaporation section 123 and a heating section 124. The hot flue gas first enters the evaporation section 123 of the heat exchanger 12, heating the hot water in the tube side 122 of the evaporation section into saturated steam. Then it enters the heating section 124, heating the hot water entering from the soft water tank 14 into the tube side 122 of the heating section 124 to the phase change critical point. The tube side 122 is arranged in staggered or parallel rows inside the heat exchanger 12. One end of the tube side 122 is connected to the circulating water device 13, which is connected to the soft water tank 14 through a pipe to form a closed circulating water system. The steam generated in the heat exchanger 12 is connected to the steam drum 15 located at the top of the heat exchanger 12 through the steam outlet of the tube side 122. The low-pressure steam in the steam drum 15 can be supplied to the steam user at the gas end 18 or used for organic Rankine cycle power generation. The cooled flue gas enters the next process.

[0034] The specific steps are as follows:

[0035] S1, the flue gas with a temperature between 320 and 400°C, drawn from the end of the flue gas outlet of the medium-temperature and medium-pressure waste heat boiler, is introduced into the high-temperature dust collector 11 through an insulated pipe for high-temperature dust removal.

[0036] S2, the flue gas after dust removal in step S1 is introduced into the shell side 121 of the two-stage flue gas heat exchanger 12 through an insulated pipe, and then enters the evaporation section 123 of the heat exchanger 12. The flue gas in the shell side 121 exchanges heat with the counter-flowing 90-99°C hot water in the tube side 122. After heat exchange, the temperature of the flue gas drops to 220-180°C, and the water inside the tube side 122 obtains low-pressure saturated steam of 0.4-0.5 MPa. The saturated steam enters the steam drum 15 located at the top of the heat exchanger 12. The low-pressure saturated steam in the steam drum can be used at the low-pressure steam outlet 18 or for organic Rankine cycle power generation.

[0037] S3, the flue gas from the evaporation section 123 is introduced into the heating section 124, where it exchanges heat with the 70-90°C water flowing counter-currently in the tube side 122 of the heating section 124, further reducing the flue gas temperature to about 140°C. The hot water in the tube is heated to the phase change critical point before entering the evaporation section, and then enters the evaporation section 123.

[0038] S4, the flue gas that has been cooled in the two-stage heat exchanger 12 enters the next process through the insulated flue pipe, and the saturated low-pressure steam obtained by the evaporation section 123 is introduced into the steam drum 15 from the steam end outlet of the heater 2.

[0039] S5. The high-temperature dust obtained in step S1 is introduced into the ash conveying device 16. The high-temperature dust enters the fluidized heat exchanger inside the ash conveying device. The heat of the high-temperature dust is recovered through water tube heat exchange. The cooled heavy metal dust will enter the metal recovery system for reuse.

[0040] Finally, it should be noted that the above is only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to the preferred arrangement, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model (such as the connection method, the shape of each element, etc.) without departing from the spirit and scope of the technical solution of this utility model.

Claims

1. A system for reusing waste heat from non-ferrous smelting waste gas, characterized in that, The dust collector (11) is set at the front end of the heat exchanger (12). The hot flue gas from the medium-temperature and medium-pressure waste heat boiler enters the dust collector (11) directly through the pipeline. The hot flue gas after dust removal enters the shell side (121) of the two-stage flue gas heat exchanger (12) and exchanges heat with the water flowing in the opposite direction in the tube side (122) of the heat exchanger (12). The generated saturated steam enters the steam drum (15) set at the top of the heat exchanger (12). The steam drum (15) is connected to the user end (18) through the pipeline. The tube side (122) of the heat exchanger (12) is connected to the circulating water system.

2. The waste heat recovery system for non-ferrous smelting waste gas according to claim 1, characterized in that, The two-stage heat exchanger (12) includes an evaporation section (123) and a heating section (124), wherein the heat exchange area of ​​the evaporation section (123) is 1.2 to 1.4 times that of the heating section (124).

3. The waste heat recovery system for non-ferrous smelting waste gas according to claim 1, characterized in that, The shell side (121) of the heat exchanger (12) has a length of 5 to 6 meters.

4. The waste heat recovery system for non-ferrous smelting waste gas according to claim 1, characterized in that, The tube side (122) of the heat exchanger (12) is arranged in staggered or sequential tube rows inside.

5. The waste heat recovery system for non-ferrous smelting waste gas according to claim 1, characterized in that, The dust collector (11) is equipped with a jet cleaning device (17) at the top and an ash conveying device (16) at the bottom. The ash conveying device (16) is equipped with a fluidized heat exchanger inside.

6. The waste heat recovery system for non-ferrous smelting waste gas according to claim 5, characterized in that, The circulating water system is equipped with a soft water tank (14), the inlet (126) of the heating section (124) is connected to the soft water tank (14), and the outlet (127) of the evaporation section (123) is connected to the circulating water system through the fluidized heat exchanger.

7. The waste heat recovery system for non-ferrous smelting waste gas according to claim 6, characterized in that, The filter bags of the dust collector (11) are made of high-temperature resistant metal or ceramic filter bags, with a length of 4 meters or 6 meters, and are suspended on the upper end of the tube sheet inside the dust collector (11) shell.

8. The waste heat recovery system for non-ferrous smelting waste gas according to claim 1, characterized in that, The heat exchanger (12) is equipped with a flue gas temperature and flow detector (19) on the flue gas inlet pipe, and the heat exchanger (12) is equipped with a water temperature and flow sensor (20), which can transmit the monitoring data to the control system in real time.

9. The waste heat recovery system for non-ferrous smelting waste gas according to claim 6, characterized in that, The condensate generated by the steam drum (15) is connected to the tube side of the heating section through a pipeline.

10. The waste heat recovery system for non-ferrous smelting waste gas according to any one of claims 1 to 9, characterized in that, The system's connecting pipes are insulated.

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