Device for improving waste heat recovery stability and steam production rate of zinc smelting flue gas acid making

Abstract

The invention relates to a device for improving waste heat recovery stability and steam production rate in zinc smelting flue gas acid making, and belongs to the technical field of waste heat recovery in zinc smelting flue gas acid making. On the basis of an existing zinc smelting flue gas acid making and waste heat recovery system, a quench tower is additionally arranged between a gas cooling tower and an electric demister of a smelting flue gas acid making device; the water content of the acid-making flue gas is reduced, the unrecoverable dilution heat generated by absorbing the water in the acid-making flue gas is reduced, and the absorbed acid can maintain higher acid concentration; meanwhile, due to mutual mixing of the dry acid, the absorption acid and the waste heat recovery system acid and maintenance of the acid concentration of the dry acid, the absorption acid and the waste heat recovery system acid can also maintain relatively high acid concentration, and equipment corrosion caused by reduction of the acid concentration can be reduced or eliminated; and meanwhile, due to the maintenance of the acid concentration, the water adding amount of the waste heat recovery diluter is increased, so that more dilution heat can be generated, the acid mixing amount between the waste heat recovery and drying circulating tank and the absorption circulating tank is reduced, and the heat loss caused by acid mixing is further reduced.

Description

Technical Field

[0001] This invention belongs to the field of waste heat recovery technology for acid production from zinc smelting flue gas. Specifically, it relates to a device for improving the stability and steam production rate of waste heat recovery from acid production from zinc smelting flue gas. Background Technology

[0002] In the process of producing sulfuric acid from zinc smelting flue gas, the recoverable heat energy consists of three parts: first, the sensible heat of the sulfur dioxide flue gas, most of which enters the primary and secondary absorption towers, exchanges heat with the absorption acid, and directly enters the absorption acid and indirectly enters the sulfuric acid circulating water; a small portion exchanges heat with the air through the SO3 cooler; second, the heat of SO3 absorption, which directly enters the absorption acid and indirectly enters the sulfuric acid circulating water through the acid cooler; and third, the heat of dilution, which directly enters the absorption acid and indirectly enters the sulfuric acid circulating water. To recover these three parts of heat, smelting flue gas sulfuric acid production units are usually equipped with a waste heat recovery system to recover the heat generated during the process.

[0003] In existing technology, the high-temperature dust-laden sulfur dioxide flue gas generated after high-temperature desulfurization of zinc sulfide concentrate in a fluidized bed furnace is cooled and dusted by a waste heat boiler, cyclone dust collector and electrostatic precipitator, and then enters the sulfuric acid primary power wave, gas cooling tower, secondary power wave and electrostatic precipitator for further cooling, dust removal and impurity removal. Finally, it enters the drying tower and other subsequent acid production equipment to produce 98% industrial sulfuric acid. At the same time, a low-temperature waste heat recovery system is used to recover the low-temperature heat energy in the zinc smelting flue gas acid production process.

[0004] The concentration of drying acid decreases after absorbing moisture, thus requiring the replenishment of concentrated acid; the concentration of absorbing acid increases after absorbing sulfur trioxide, thus requiring the replenishment of dilute acid. Simultaneously, the heat of dilution generated by diluting sulfuric acid is an important component of recoverable heat energy. Therefore, acid dilution operations are typically located within a low-temperature waste heat recovery system. To maintain acid concentration balance, the absorbing acid, drying acid, and sulfuric acid in the low-temperature waste heat recovery system are interconnected. Unstable acid concentrations can lead to several problems: a decrease in acid concentration significantly increases the corrosiveness of sulfuric acid, easily causing equipment corrosion; conversely, excessively high acid concentration reduces the absorption rate of the absorbing acid, affecting the plant's capacity and stability.

[0005] In current production facilities, in order to maintain acid concentration balance, it is usually necessary to increase the amount of sulfuric acid in the acid absorption, drying, and low-temperature waste heat recovery systems. The loss of sulfuric acid heat during the acid-carrying process is unavoidable and reduces the low-temperature waste heat recovery rate.

[0006] Meanwhile, since the sulfuric acid in the absorption acid, drying acid and low-temperature waste heat recovery system is interconnected, any fluctuation in acid concentration will seriously affect the stability of the system. For example, it will affect the sulfur trioxide absorption rate, which in turn will affect the sulfuric acid production. At the same time, the gas production of the evaporator will also fluctuate due to the fluctuation in sulfuric acid production, causing instability in the production unit and having a significant impact on the operation and capacity of the entire unit.

[0007] In smelting flue gas acid production units and low-temperature waste heat recovery systems, stable operation of the units and improvement of heat recovery rate are both crucial. Summary of the Invention

[0008] To overcome the problems existing in the background technology, the present invention provides an apparatus for improving the stability and steam production rate of waste heat recovery from zinc smelting flue gas to produce sulfuric acid. By adding a quench tower between the gas cooling tower and the electrostatic precipitator of the smelting flue gas to produce sulfuric acid, and by connecting the smelting flue gas to the low-temperature waste heat recovery system through the pipeline, not only is the recoverable heat energy of the smelting flue gas to produce sulfuric acid improved, but also the stability of the smelting flue gas to produce sulfuric acid and the low-temperature waste heat recovery system is improved, the risk of equipment corrosion is reduced, and the heat recovery rate of the low-temperature waste heat recovery system is improved.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0010] The device for improving the stability and steam production rate of sulfuric acid production from zinc smelting flue gas includes a sulfuric acid production device from smelting flue gas and a low-temperature waste heat recovery system. A quench tower is added between the gas cooling tower and the electrostatic precipitator of the sulfuric acid production device from smelting flue gas, and the sulfur dioxide flue gas is cooled in the quench tower.

[0011] The high-temperature SO2 flue gas from the zinc smelting system first enters the primary dynamic wave scrubbing tower, and then sequentially enters the gas cooling tower, quench tower, electrostatic precipitator, drying tower, 3K fan, front section of converter, low-temperature waste heat absorption tower, back section of converter, secondary absorption tower and desulfurization tower.

[0012] Furthermore, the acid at the outlet of the demineralized water preheater of the low-temperature waste heat recovery system is connected in series via pipeline to the absorption circulation tank and drying circulation tank of the smelting flue gas acid production unit; the acid at the outlet of the drying acid circulation tank of the smelting flue gas acid production unit is connected in series via pipeline to the acid-acid heat exchanger of the low-temperature waste heat recovery system.

[0013] Furthermore, the drying tower is equipped with a drying circulation tank and a drying circulation pump; the outlet of the drying circulation pump is connected by pipes to the drying tower, the absorption circulation tank and the low-temperature waste heat recovery acid-acid heat exchanger.

[0014] The secondary absorption tower is equipped with an absorption circulation pump and an absorption circulation tank; the absorption acid circulates between the secondary absorption tower and the absorption circulation tank through the absorption circulation pump; the outlet of the absorption circulation pump is connected to the secondary absorption tower, the drying circulation tank and the low-temperature waste heat absorption tower through pipelines respectively.

[0015] Furthermore, the aforementioned low-temperature waste heat recovery system includes a low-temperature waste heat circulation tank, a low-temperature waste heat circulation pump, a low-temperature waste heat absorption tower, an evaporator, an acid-acid heat exchanger, a deaerator, a demineralized water preheater, and a deoxygenated water preheater.

[0016] The low-temperature waste heat absorption tower, evaporator and diluent are connected in sequence by pipelines to form a circulation loop. A low-temperature waste heat circulation tank and a low-temperature waste heat circulation pump are provided between the low-temperature waste heat absorption tower and the evaporator.

[0017] The demineralized water preheater, deaerator, deoxygenated water preheater and evaporator are connected in sequence by water pipes. The demineralized water first enters the demineralized water preheater for preheating, and then enters the deaerator and evaporator in sequence to exchange heat with the high-temperature and high-concentration absorption acid in the evaporator to generate low-pressure steam.

[0018] The evaporator outlet acid pipe is equipped with a tee, which is connected to the diluent and the deoxygenated water preheater through pipes respectively; the deoxygenated water preheater, acid-acid heat exchanger, demineralized water preheater, drying circulation tank and absorption circulation tank are connected in sequence through acid pipes.

[0019] Furthermore, the dried acid enters the diluent after being heated by the acid-acid heat exchanger; the sulfuric acid in the diluent circulates between the low-temperature waste heat absorption tower, the diluent, and the evaporator and exchanges heat with the water entering the evaporator.

[0020] The acid from the outlet of the low-temperature waste heat circulation pump returns to the middle of the low-temperature waste heat absorption tower through the pipeline via the evaporator and diluent. The acid absorbs SO3 flue gas in the low-temperature waste heat absorption tower and exchanges heat with the flue gas entering the low-temperature waste heat absorption tower to raise its temperature.

[0021] Furthermore, after heat exchange in the evaporator, the sulfuric acid sequentially enters the deoxygenated water preheater, acid-acid heat exchanger, and demineralized water preheater to exchange heat with water or dried acid for cooling. After cooling, part of the acid enters the drying circulation tank, and another part enters the absorption circulation tank; the other part enters the diluent and returns to the low-temperature waste heat absorption tower.

[0022] Furthermore, a water supply pipe is connected between the deaerator and the diluter, through which water is added to the diluter.

[0023] Furthermore, the evaporator is equipped with a wastewater drain pipe to send the wastewater inside the evaporator to the wastewater expansion tank.

[0024] The beneficial effects of this invention are:

[0025] This invention, by adding a quench tower between the gas cooling tower and the electrostatic precipitator in a zinc smelting flue gas acid production unit, effectively reduces the temperature of the acid production flue gas, thereby reducing the moisture content of the acid production flue gas (or sulfur dioxide flue gas). This invention, by reducing the moisture content of the acid production flue gas, also produces the following significant effects: First, by using drying acid in the drying tower to dry the sulfur dioxide flue gas, the unrecoverable heat of dilution generated during the water absorption process of the drying acid is significantly reduced, thus maintaining a high acid concentration and reducing corrosion of the drying tower caused by the decrease in acid concentration. Second, because the drying acid, absorption acid, and low-temperature waste heat recovery system acids are interconnected, after the concentration of the drying acid is increased, the concentrations of the drying acid, absorption acid, and waste heat recovery acid can all be maintained within a high concentration range, solving the equipment corrosion caused by the decrease in the concentration of the drying acid, absorption acid, and low-temperature waste heat recovery acid, thereby avoiding or reducing downtime of the acid production unit and low-temperature waste heat recovery system due to equipment corrosion. Third, more water can be added to the low-temperature waste heat recovery diluent to maintain the concentration balance of the drying acid, the absorbing acid, and the low-temperature waste heat recovery acid, thereby generating more recoverable dilution heat and increasing the heat output of the entire system. Fourth, due to the increased concentration of the drying acid, the flow rate of acid between the low-temperature waste heat recovery system and the drying acid and the absorbing acid is significantly reduced, greatly reducing the heat loss caused by the large flow rate of acid during the maintenance of the concentration balance of the drying acid, the absorbing acid, and the low-temperature waste heat recovery system, and improving the heat recovery rate. Fifth, the stable concentration of the absorbing acid ensures the stability of the absorption capacity of the absorbing acid, thereby improving the stability of the sulfuric acid production of the smelting flue gas sulfuric acid production unit. At the same time, the stable dilution acid production of the low-temperature waste heat recovery system and the stability of the smelting flue gas sulfuric acid production unit can improve the stability of the low-temperature waste heat recovery system and the stability of the gas production, thereby improving the stability of the entire smelting flue gas sulfuric acid production unit and the low-temperature waste heat recovery system. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the smelting flue gas flow path of the present invention;

[0027] Figure 2 This is a schematic diagram of the overall structure of the present invention;

[0028] Figure 3 This is a schematic diagram of the low-temperature waste heat recovery device of the present invention;

[0029] Note: In the diagram, 1-quench tower, 2-quench tower circulating pump, 3-flue gas inlet, 4-coolant outlet, 5-coolant inlet, 6-heat exchanger, 7-refrigeration unit, 8-chilled water circulating pump, 9-chilled water storage tank, 10-cooling flue gas outlet;

[0030] 21-Secondary absorption tower, 22-Acid absorption circulation tank, 23-Drying tower, 24-Drying tower circulation tank, 25-Low-temperature waste heat absorption tower, 26-Low-temperature waste heat absorption circulation tank, 27-Dilutioner, 28-Evaporator, 29-Desorption tower, 30-Demineralized water tank, 31-Deoxygenated water preheater, 32-Acid-acid heat exchanger, 33-Demineralized water preheater, 34-Deoxygenator, 35-Expansion tank

[0031] Figure 2 In the diagram, the red pipeline is the pipeline from the low-temperature waste heat recovery system to the smelting flue gas acid production unit, the green pipeline is the pipeline from the smelting flue gas acid production unit to the low-temperature waste heat recovery system, and the blue pipeline is the pipeline from which deoxygenated water is added to the diluent to dilute the acid concentration. Detailed Implementation

[0032] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are all within the scope of protection of this invention.

[0033] To illustrate the present invention more clearly, the following embodiments will be described in detail.

[0034] Example 1

[0035] The present invention provides an apparatus for improving the stability and steam production rate of sulfuric acid production from zinc smelting flue gas. The apparatus includes a sulfuric acid production device from smelting flue gas and a low-temperature waste heat recovery system. The present invention adds a quench tower to the existing sulfuric acid production device from smelting flue gas and low-temperature waste heat recovery system to reduce the temperature and moisture content of the sulfuric acid production flue gas (sulfur dioxide flue gas). At the same time, the connecting pipelines of the sulfuric acid production device from smelting flue gas and the low-temperature waste heat recovery system are arranged.

[0036] This invention reduces the temperature of acid-producing flue gas by setting up a quench tower, thereby reducing the water content of the acid-producing flue gas. The principle is as follows:

[0037] The saturated vapor pressure of water in sulfur dioxide flue gas increases with increasing temperature. Calculation process:

[0038] (1) Moisture content of sulfur dioxide flue gas at the inlet of the drying tower at a temperature of 32℃:

[0039] Assume that the sulfur dioxide flue gas is in a saturated state at 32℃ (the partial pressure of water vapor equals the saturated vapor pressure, i.e., P). v1 =P sat,32 =4.746 kPa), at this point the absolute water content of water vapor (the mass of water vapor per unit volume of flue gas) can be expressed by the ideal gas law. calculate.

[0040] In the ideal gas law, P is the partial pressure of water vapor (kPa); V is the volume of flue gas (m³). 3 Here we take 1m 3 M is the molar mass of water (18 g / mol); R is the gas constant (8.314 kPa·L / (mol·K)); T is the absolute temperature (K), 32℃=305.15K.

[0041] Calculate the water content m1 of sulfur dioxide flue gas at a temperature of 32℃.

[0042]

[0043] (2) Moisture content of sulfur dioxide flue gas at the inlet of the drying tower when the temperature drops to 20℃:

[0044] Calculate the water content (m2) of sulfur dioxide flue gas at a temperature of 20℃.

[0045]

[0046] The moisture content in high-temperature sulfur dioxide flue gas is related to temperature; lowering the flue gas temperature can reduce the moisture content.

[0047] After adding the quench tower, the inlet flue gas temperature of the drying tower drops from the original 32℃ to 20℃. This reduction in inlet flue gas temperature decreases the amount of water carried in by sulfur dioxide flue gas per hour.

[0048] m = V 实际 ×(m1-m2)=16.4g / m 3 ×70000m 3 / h = 1.148t / h.

[0049] Therefore, it is feasible to reduce the water content in the drying acid by lowering the temperature of the sulfur dioxide flue gas at the inlet of the drying tower.

[0050] This invention is an improvement on existing smelting flue gas acid production devices and low-temperature waste heat recovery systems. Given that smelting flue gas acid production devices and low-temperature waste heat recovery systems are known technologies, this embodiment mainly describes the improvements of this invention as follows.

[0051] This invention adds a quench tower to an existing sulfuric acid production unit made from smelting flue gas. The quench tower is located between the gas cooling tower and the electrostatic precipitator. The principle of the quench tower in cooling sulfur dioxide flue gas is as follows: Figure 3The quenching tower of this invention is equipped with a heat exchanger 6, a refrigeration unit 7, a chilled water storage tank 9, and a chilled water circulation pump 8. The inlet of the chilled water circulation pump 8 is connected to the chilled water storage tank 9 via a pipe, and the outlet is connected to the refrigeration unit 7 via a pipe. The chilled water inlet of the heat exchanger 6 is connected to the refrigeration unit 7, and the chilled water outlet of the heat exchanger 6 is connected to the chilled water storage tank 9. The refrigeration unit 7 provides chilled water to the heat exchanger 6 to remove heat from the coolant. After heat exchange, the chilled water returns to the chilled water storage tank 9 and is pumped into the refrigeration unit 7 by the chilled water circulation pump 8 for cooling. The quenching tower 1 is a packed tower. The lower part of the quenching tower 1 has a flue gas inlet 3 and a coolant outlet 4, the upper part has a coolant inlet 5, and the top has a cooled flue gas outlet 10. High-temperature sulfur dioxide flue gas enters the quenching tower from the flue gas inlet 3 and exchanges heat countercurrently with the chilled liquid supplied from the coolant inlet 5, thereby reducing the temperature of the sulfur dioxide flue gas. The cooled sulfur dioxide flue gas enters the electrostatic precipitator through the cooled flue gas outlet 10. The refrigeration unit 7 of this invention is a purchased device. Its working principle is based on the reverse Carnot cycle. By circulating the refrigerant in components such as the evaporator, compressor, condenser, and throttling device, heat is transferred from the low-temperature object to the high-temperature object, thereby achieving the purpose of refrigeration.

[0052] In this invention, the main series piping of the smelting flue gas acid production device and the low-temperature waste heat recovery system is as shown in the attached diagram. Figure 2 (As shown): (1) The acid from the outlet of the demineralized water preheater of the low-temperature waste heat recovery system is connected to the absorption circulation tank and drying circulation tank of the smelting flue gas acid production unit. (2) The acid from the outlet of the drying circulation tank of the smelting flue gas acid production unit is connected to the acid-acid heat exchanger of the low-temperature waste heat recovery system. (3) The acid from the outlet of the low-temperature waste heat absorption tower circulation tank is sequentially transported through pipelines to the evaporator, deoxygenated water waste heat exchanger, acid-acid heat exchanger and demineralized water preheater.

[0053] The direction of the acid production flue gas in this invention is as follows: zinc sulfide concentrate at 109m 2 After high-temperature desulfurization in the fluidized bed furnace, the high-temperature dust-laden sulfur dioxide flue gas is cooled and removed by a waste heat boiler, cyclone dust collector, and electrostatic precipitator, and then sequentially enters a primary dynamic wave scrubbing tower, a gas cooling tower, a quench tower, an electrostatic precipitator, a drying tower, a 3K fan, the front section of the converter (primary conversion), a low-temperature waste heat absorption tower, the rear section of the converter (secondary conversion), a secondary absorption tower, and a desulfurization tower.

[0054] The low-temperature waste heat recovery system includes a low-temperature waste heat absorption tower, an evaporator, an acid-acid heat exchanger, a deaerator, a demineralized water preheater, and a deoxygenated water preheater. The low-temperature waste heat absorption tower, evaporator, and diluent are sequentially connected by sulfuric acid pipelines, forming a high-temperature, high-concentration absorption acid circulation loop. A low-temperature waste heat circulation tank and a low-temperature waste heat circulation pump are installed between the low-temperature waste heat absorption tower and the evaporator. The low-temperature waste heat circulation pump provides the power for the circulation loop. The high-temperature, high-concentration absorption acid heats the deoxygenated water in the evaporator to produce low-pressure steam. A water supply pipe connects the deaerator and the diluent, adding water to the diluent to maintain the concentration balance of the drying acid, absorption acid, and low-temperature waste heat recovery acid, thereby recovering the dilution heat generated by adding water to the diluent. The more dilution heat generated by the diluent, the more heat energy can be recovered. This invention reduces the moisture content of the sulfur dioxide flue gas entering the drying tower, thereby increasing the concentration of the drying acid and maintaining a higher concentration within the drying tower, thus reducing corrosion caused by a decrease in acid concentration.

[0055] The demineralized water preheater, deaerator, deoxygenated water preheater, and evaporator are connected sequentially by water pipes. The demineralized water first enters the demineralized water preheater for preheating, then sequentially enters the deaerator and deoxygenated water preheater for further heating, and finally enters the evaporator for further heating.

[0056] The heat exchanger inside the vessel generates low-pressure steam through acid heat exchange.

[0057] The drying acid circulates between the drying tower and the drying circulation tank via a drying circulation pump. The drying acid comes into countercurrent contact with the flue gas to absorb moisture from the sulfur dioxide flue gas. The outlet of the drying circulation pump is connected via pipelines to the drying tower, the absorption circulation tank, and the acid-acid heat exchanger. In the acid-acid heat exchanger, the drying acid exchanges heat with the high-temperature, high-concentration absorption acid recovering from low-temperature waste heat. After its temperature rises, the drying acid enters the diluent. The absorption acid, after being cooled by the acid-acid heat exchanger, enters the demineralized water preheater. The absorption acid circulates between the secondary absorption tower and the absorption circulation tank via an absorption circulation pump. The absorption acid comes into countercurrent contact with the SO3 flue gas from the converter to absorb SO3. The outlet of the absorption circulation pump is connected via pipelines to the absorption tower, the drying circulation tank, and the low-temperature waste heat absorption tower. In this invention, the absorption acid, drying acid, and low-temperature waste heat recovery system are interconnected. As the concentration of the drying acid increases, the concentrations of all three acids—drying acid, absorption acid, and waste heat recovery acid—can be maintained within a high range. This solves the problem of equipment corrosion caused by decreased concentrations of these acids, thereby preventing or reducing downtime of the acid production unit and low-temperature waste heat recovery system due to corrosion. Simultaneously, the increased concentration of the drying acid significantly reduces the acid flow rate between the low-temperature waste heat recovery system and the drying and absorption acids. This greatly reduces heat loss caused by large-flow acid exchange to maintain the acid concentration balance of the drying acid, absorption acid, and low-temperature waste heat recovery system, thus improving the heat recovery rate.

[0058] The evaporator outlet acid pipe is equipped with a tee, which connects to the diluent, the low-temperature waste heat absorption tower, and the deoxygenated water preheater via pipelines. The deoxygenated water preheater, acid-acid heat exchanger, demineralized water preheater, drying circulation tank, and absorption circulation tank are sequentially connected by acid pipes. Through this pipeline connection, the high-temperature, high-concentration absorption acid from the evaporator sequentially enters the deoxygenated water preheater, acid-acid heat exchanger, and demineralized water preheater to exchange heat with water or drying acid for cooling. After cooling, part of the acid enters the drying circulation tank, another part enters the absorption circulation tank, and the remaining part returns to the low-temperature waste heat absorption tower via the diluent.

[0059] This invention adds water to the diluent via a water inlet pipe. The dilution heat generated by the diluent exchanges heat with the demineralized water in the evaporator. Even after the concentration of the drying acid increases, the concentrations of the drying acid, absorption acid, and waste heat recovery acid can all be maintained within a high concentration range. More water can be added to the diluent to maintain the concentration balance of the drying acid, absorption acid, and low-temperature waste heat recovery acid, thereby generating more recoverable dilution heat and increasing the overall system's heat output. This invention not only improves the stability of the zinc smelting flue gas acid production unit but also increases the steam production rate of the low-temperature waste heat recovery unit.

[0060] Tables 1 and 2 show the unit product energy consumption limits and advanced energy consumption values ​​for existing industrial sulfuric acid enterprises, as detailed below (no advanced values ​​are apparent):

[0061] Table 1. Energy consumption limits per unit product for existing industrial sulfuric acid enterprises.

[0062]

[0063] Table 2 Advanced Values ​​of Energy Consumption per Unit Product of Industrial Sulfuric Acid

[0064] Types of raw materials for production Unit product comprehensive energy consumption kgce / t Electricity consumption per ton of acid (kWh / t) sulfur ≤-180 ≤60 Pyrite ≤-135 ≤110 Copper and nickel smelting flue gas ≤-30 ≤100 Lead smelting flue gas ≤5 ≤130 Zinc smelting flue gas ≤-120 ≤110 Other ferrous metal smelting flue gas ≤42 ≤210

[0065] After the implementation of this invention, the comprehensive energy consumption of zinc sulfuric acid was reduced to -131.96 kgce / t, which is lower than the advanced value in the same industry. Table 3 shows the comprehensive energy consumption of zinc sulfuric acid from August to December 2024 after the invention was put into use.

[0066] Table 3. Comprehensive energy consumption for acid production from zinc smelting flue gas after the implementation of this invention (kgce / t)

[0067]

[0068]

[0069] After the implementation of this invention, the electricity consumption per unit of zinc-sulfuric acid was reduced to 109.39 kWh / t, which is lower than the advanced value in the same industry. Table 4 shows the electricity consumption per unit of zinc-sulfuric acid from August to December 2024 after the invention was put into use.

[0070] Table 4. Power consumption per ton of acid produced from zinc smelting flue gas after the invention is put into operation (kWh / t)

[0071] month 8 9 10 11 12 average value Electricity consumption per unit (kWh / t) 109.15 114.37 113.35 105.71 104.39 109.39

[0072] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. An apparatus for improving the stability and steam production rate of waste heat recovery from zinc smelting flue gas for acid production, comprising a smelting flue gas acid production unit and a low-temperature waste heat recovery system, characterized in that, A quench tower is added between the gas cooling tower and the electrostatic precipitator of the smelting flue gas acid production unit, and the sulfur dioxide flue gas is cooled down in the quench tower.

2. The apparatus according to claim 1, characterized in that, The high-temperature SO2 flue gas from the zinc smelting system first enters the primary dynamic wave scrubbing tower, and then sequentially enters the gas cooling tower, quench tower, electrostatic precipitator, drying tower, 3K fan, front section of converter, low-temperature waste heat absorption tower, back section of converter, secondary absorption tower and desulfurization tower.

3. The apparatus according to claim 1, characterized in that, The acid at the outlet of the demineralized water preheater of the low-temperature waste heat recovery system is connected in series via pipeline to the absorption circulation tank and the drying circulation tank of the smelting flue gas acid production unit; the acid at the outlet of the drying acid circulation tank of the smelting flue gas acid production unit is connected in series via pipeline to the acid-acid heat exchanger of the low-temperature waste heat recovery system.

4. The apparatus according to claim 1, characterized in that, The drying tower is equipped with a drying circulation tank and a drying circulation pump; the outlet of the drying circulation pump is connected by pipes to the drying tower, the absorption circulation tank and the low-temperature waste heat recovery acid-acid heat exchanger. The secondary absorption tower is equipped with an absorption circulation pump and an absorption circulation tank; the absorption acid circulates between the secondary absorption tower and the absorption circulation tank through the absorption circulation pump; the outlet of the absorption circulation pump is connected to the secondary absorption tower, the drying circulation tank and the low-temperature waste heat absorption tower through pipelines respectively.

5. The apparatus according to any one of claims 1 to 4, characterized in that, The aforementioned low-temperature waste heat recovery system includes a low-temperature waste heat circulation tank, a low-temperature waste heat circulation pump, a low-temperature waste heat absorption tower, an evaporator, an acid-acid heat exchanger, a deaerator, a demineralized water preheater, and a deoxygenated water preheater. The low-temperature waste heat absorption tower, evaporator and diluent are connected in sequence by pipelines to form a circulation loop. A low-temperature waste heat circulation tank and a low-temperature waste heat circulation pump are provided between the low-temperature waste heat absorption tower and the evaporator. The demineralized water preheater, deaerator, deoxygenated water preheater and evaporator are connected in sequence by water pipes. The demineralized water first enters the demineralized water preheater for preheating, and then enters the deaerator and evaporator in sequence to exchange heat with the high-temperature and high-concentration absorption acid in the evaporator to generate low-pressure steam. The evaporator outlet acid pipe is equipped with a tee, which is connected to the diluent and the deoxygenated water preheater through pipes respectively; the deoxygenated water preheater, acid-acid heat exchanger, demineralized water preheater, drying circulation tank and absorption circulation tank are connected in sequence through acid pipes.

6. The apparatus according to claim 5, characterized in that, After the dried acid is heated by the acid-acid heat exchanger, it enters the diluent; the sulfuric acid in the diluent circulates between the low-temperature waste heat absorption tower, the diluent and the evaporator and exchanges heat with the water entering the evaporator. The acid from the outlet of the low-temperature waste heat circulation pump returns to the middle of the low-temperature waste heat absorption tower through the pipeline via the evaporator and diluent. The acid absorbs SO3 flue gas in the low-temperature waste heat absorption tower and exchanges heat with the flue gas entering the low-temperature waste heat absorption tower to raise its temperature.

7. The apparatus according to claim 5, characterized in that, After heat exchange in the evaporator, the sulfuric acid enters the deoxygenated water preheater, acid-acid heat exchanger, and demineralized water preheater in sequence to exchange heat with water or dry acid and cool down. After cooling, part of the acid enters the drying circulation tank, and the other part enters the absorption circulation tank; the other part enters the diluent and returns to the low-temperature waste heat absorption tower.

8. The apparatus according to claim 5, characterized in that, A water supply pipe is connected between the deaerator and the diluter, through which water is added to the diluter.

9. The apparatus according to claim 5, characterized in that, The evaporator is equipped with a sewage pipe to send the sewage inside the evaporator to the sewage expansion container.

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