Tail gas treatment system of hydrochloric acid regeneration device

Abstract

The utility model relates to a tail gas treatment system of a hydrochloric acid regeneration device, which comprises a condenser, an absorption tower, a cooling tower, a washing tower, a smoke exhaust fan, an alkaline washing tower and an electric dust remover, a tail gas outlet of the absorption tower is connected with a gas inlet of the condenser, a gas outlet of the condenser is connected with the washing tower, and gas in the washing tower is diluted by the washing tower. The washing tower is connected with a tail gas inlet of the alkaline washing tower through a smoke exhaust fan; a cooling water outlet of the cooling tower is connected with a cooling water inlet of the condenser through a cooling water circulating pump; a condensate outlet of the condenser is connected with a spraying liquid pipeline connected with the absorption tower through a condensate circulating pump; an alkali washing circulating pump is arranged on an alkali washing liquid circulating conveying pipeline of the alkali washing tower; the alkali storage tank is connected with an alkali washing liquid circulating tank at the lower part of the alkali washing tower through an alkali discharging pump; a top furnace gas outlet of the alkaline tower is connected with the electric precipitator. The hydrochloric acid regeneration device tail gas treatment system has the advantages of being reasonable in overall structure, easy to operate and capable of meeting the requirements of energy conservation and emission reduction.

Description

Technical Field

[0001] The utility model belongs to the field of hydrochloric acid regeneration in the metallurgical industry, and in particular relates to a tail gas treatment system for a hydrochloric acid regeneration device. Background Art

[0002] The tail gas treatment process commonly used in hydrochloric acid regeneration units at present is: the high-temperature furnace gas of about 395°C discharged from the roasting furnace of the hydrochloric acid regeneration unit is cooled to about 97°C by circulating spraying of waste acid in the pre-concentrator, and then enters the absorption tower and the washing tower to contact with the upper spraying water in reverse to absorb and wash the acidic gas. At this time, the acid-containing furnace gas has been saturated with water and turned into water vapor, which is discharged into the atmosphere from the chimney of the device. The discharged acid-containing water vapor condenses into water and falls, causing certain corrosion to the equipment and buildings near the plant area, causing harm to the environment, especially to the residents around the plant area. In order to avoid this phenomenon that harms the environment, we have modified the conventional process and developed a new technology for tail gas condensation and alkaline washing acid. Without changing the existing hydrochloric acid regeneration unit building and the layout of the main equipment, a condenser is added after the absorption tower, and then enters the alkaline washing tower for neutralization reaction, so that the acid content of the exhaust gas is controlled at ≤10mg / m 3 , lower than the national tail gas acid content ≤30mg / m 3 However, the modified hydrochloric acid regeneration process requires a large amount of new water from outside, and the emission of particulate matter is still high, so there is room for further improvement in energy conservation and emission reduction. Summary of the Invention

[0003] The purpose of this utility model is to provide a tail gas treatment system for a hydrochloric acid regeneration unit with a simple structure, easy operation, and energy conservation and emission reduction. The acid-containing flue gas from the absorption tower is cooled by heat exchange in a condenser, and a scrubber is used to remove part of the smoke and acid mist in the flue gas. The flue gas then enters an alkaline scrubber for neutralization, further reducing the acid content in the tail gas. The condensate can be used as a spray liquid for the absorption tower, saving washing water and power consumption. The flue gas is finally dedusted by an electrostatic precipitator to meet the exhaust gas discharge requirements.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0005] A tail gas treatment system for a hydrochloric acid regeneration device comprises a condenser, an absorption tower, a cooling tower, a scrubbing tower, a smoke exhaust fan, an alkali scrubbing tower, and an electrostatic precipitator. The tail gas outlet of the absorption tower is connected to the gas inlet of the condenser, the gas outlet of the condenser is connected to the scrubbing tower, the gas in the scrubbing tower is diluted by the scrubbing tower, and the scrubbing tower is connected to the tail gas inlet of the alkali scrubbing tower via the smoke exhaust fan; the cooling water outlet of the cooling tower is connected to the cooling water inlet of the condenser via a cooling water circulation pump, and the condensate outlet of the condenser is connected to a spraying liquid pipeline connected to the absorption tower via a condensate circulation pump; an alkali scrubbing circulation pump is provided on the alkali scrubbing liquid circulation conveying pipeline of the alkali scrubbing tower, and an alkali storage tank is connected to the alkali scrubbing liquid circulation tank at the bottom of the alkali scrubbing tower via an alkali unloading pump; and the furnace gas outlet at the top of the alkali scrubbing tower is connected to the electrostatic precipitator.

[0006] The condensate outlet of the condenser is connected to a water collection tank, and the water collection tank is connected to a condensate circulation pump.

[0007] The electrostatic precipitator is a wet electrostatic precipitator.

[0008] The condenser is a horizontal tube-and-tube condenser, and the heat exchange tubes are graphite-modified PP tubes.

[0009] The gas inlet, gas outlet, cooling water inlet and condensate outlet of the condenser are all provided with temperature and pressure monitoring devices.

[0010] The cooling tower is a countercurrent glass fiber reinforced plastic cooling tower.

[0011] Compared with the prior art, the beneficial effects of the present invention are:

[0012] 1. The hydrochloric acid regeneration unit tail gas treatment system has a reasonable overall structure and is easy to operate, meeting energy conservation and emission reduction requirements. The acid-containing flue gas from the absorption tower is cooled by heat exchange in a condenser before entering a scrubber for preliminary removal of dust and acid mist. It then enters an alkaline scrubber for neutralization, reducing the acid content in the exhaust gas to ≤10mg / m3, far below the national standard for exhaust gas acidity, thereby reducing environmental pollution.

[0013] 2. In the system of the present invention, cooling water is recycled, and the condensate can be used as the spray liquid of the absorption tower, saving washing water and power consumption; it can also reduce the total exhaust gas emissions, reduce the load of the smoke exhaust fan, and save energy and reduce emissions.

[0014] 3. The alkali washing tower furnace gas of the utility model adopts an electrostatic precipitator to remove dust, which meets the exhaust gas discharge requirements and makes the exhaust of the entire system environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural diagram of the present utility model.

[0016] In the figure: 1-absorption tower 2-condenser 3-exhaust fan 4-alkali washing tower 5-alkali washing circulation pump 6-alkali storage tank 7-alkali unloading pump 8-cooling tower 9-cooling water circulation pump 10-collecting water tank 11-condensate circulation pump 12-washing tower 13-electrical precipitator. DETAILED DESCRIPTION

[0017] The present invention will be described in detail below with reference to the accompanying drawings. However, it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0018] See Figure 1 A tail gas treatment system for a hydrochloric acid regeneration device includes a condenser 2, an absorption tower 1, a cooling tower 8, a washing tower 12, a smoke exhaust fan 3, an alkali washing tower 4, and an electrostatic precipitator 13. The tail gas outlet of the absorption tower 1 is connected to the gas inlet of the condenser 2, the gas outlet of the condenser 2 is connected to the washing tower 12, the gas in the washing tower 12 is diluted by the washing tower 12, and the washing tower 12 is connected to the tail gas inlet of the alkali washing tower 4 through the smoke exhaust fan 3; the cooling water outlet of the cooling tower 8 is connected to the cooling water inlet of the condenser 2 through a cooling water circulation pump 9, and the condensate outlet of the condenser 2 is connected to the spraying liquid pipeline connected to the absorption tower 1 through a condensate circulation pump 11; an alkali washing liquid circulation conveying pipeline of the alkali washing tower 4 is provided with an alkali washing circulation pump 5, and the alkali storage tank 6 is connected to the alkali washing liquid circulation tank at the bottom of the alkali washing tower 4 through an alkali unloading pump 7; the furnace gas outlet at the top of the alkali washing tower 4 is connected to the electrostatic precipitator 13.

[0019] The condensate outlet of the condenser 2 is connected to the water collection tank 10, which is in turn connected to the condensate circulation pump 11. The electrostatic precipitator 13 is a wet electrostatic precipitator that absorbs particulate matter (mainly iron oxide powder) in the exhaust gas to a concentration of 10 mg / m3. 3 The following is a better absorption effect of using a wet electrostatic precipitator. The condenser 2 is a horizontal tube condenser 2, and the heat exchange tubes are graphite modified PP tubes.

[0020] Condenser 2's gas inlet, gas outlet, cooling water inlet, and condensate outlet are all equipped with temperature and pressure monitoring devices. Cooling tower 8 is a countercurrent fiberglass cooling tower. A pH meter is installed in the caustic wash liquid circulation tank at the bottom of caustic wash tower 4. When the pH meter indicates neutral, the drain valve is opened to drain brine from the bottom of the tank. Then, caustic unloading pump 7 is activated to add caustic to the tank until it reaches the level specified by the liquid level gauge, and the pump is stopped.

[0021] While working:

[0022] 1) The hydrochloric acid regeneration unit exhaust gas from absorption tower 1 enters condenser 2 for indirect heat exchange with cooling water, condensing the exhaust gas above 90°C to below 40°C. The condensate, after partially condensing the water vapor in the exhaust gas, enters a water collection tank 10 as a spray liquid for absorption tower 1. Cooling water is introduced from the bottom of condenser 2 and overflows from the top, with the water flow direction being opposite to that of the furnace gas, i.e., reverse heat exchange. The condensate discharge pipe is located on the side of the furnace gas outlet. Since the furnace gas temperature has dropped below 40°C, some of the water vapor in the furnace gas has converted to condensate, resulting in a corresponding decrease in the amount of condensate that falls after discharge, significantly reducing corrosion to nearby equipment and buildings.

[0023] 2) The cooling water inlet temperature is 30-32°C and then heated to 35-37°C after heat exchange. It then goes to the cooling tower 8, where it is cooled to 30-32°C again and then returns to the condenser 2 for recycling. During this period, evaporated water is regularly replenished.

[0024] 3) After leaving condenser 2, the furnace gas enters scrubber 12, which is filled with filler and circulated with desalted water. The scrubber water overflows into collection tank 10 and is used as spray liquid for absorption tower 1.

[0025] 4) After the furnace gas leaves the washing tower 12, it is pressurized by the exhaust fan 3 and enters the alkali washing tower 4. The alkali washing circulation pump 5 circulates and sprays alkali solution to wash the tail gas. In the alkali washing tower 4, the tail gas contacts the NaOH solution in reverse direction to completely neutralize the hydrochloric acid therein.

[0026] 5) The furnace gas leaves the alkali washing tower 4 and enters the wet electrostatic precipitator 13. After filtering in the wet electrostatic precipitator 13, the final emitted particulate matter is ≤10mg / Nm 3 The final exhaust gas acid content is ≤10mg / m 3 .

[0027] The hydrochloric acid regeneration device is a commonly used 6m 3 / h scale regeneration device, absorption tower 1 after the furnace gas volume: 20000m 3 / h; temperature: 90℃; total heat: 173635Kcal / h, heat exchange area of ​​condenser 2: F = Q / K.Δt 173635 / 28x23.7 = 261m 2 , the amount of water removed is: 173635 / 37-32=34727kg≈35m 3 , reducing exhaust emissions by 4448m per hour 3 , which is equivalent to 934kg less hydrochloric acid emitted into the atmosphere each year.

[0028] In this embodiment, the exhaust fan 33 has a motor power of 160kW and is variable frequency regulated. Due to the reduction in furnace gas volume, 32kW of energy can be saved per hour, and the energy saving rate is 22%. Assuming that the hydrochloric acid regeneration device works 7,000 hours per year, 224,000kWh of electricity can be saved per year. In addition, 3m3 of condensate is generated per hour during the condensation process.3 The collected water is then used as the spray liquid for the absorption tower 1. Since the original washing tower 12 is sprayed with desalted water, the full flow water enters the collection tank 1010, so 21,000 m3 of desalted water can be saved each year. 3 .

[0029] From the above data, it can be seen that the tail gas treatment system has obvious transformation effect and has achieved good economic and social benefits.

[0030] Through the above specific embodiments, those skilled in the art can easily implement the present invention. However, it should be understood that the present invention is not limited to the above specific embodiments. Based on the disclosed embodiments, those skilled in the art can arbitrarily combine different technical features to achieve different technical solutions. Due to space limitations and to keep the specification concise, each solution formed by these combinations is not described one by one. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A tail gas treatment system for a hydrochloric acid regeneration device, characterized in that: It includes a condenser, an absorption tower, a cooling tower, a washing tower, a smoke exhaust fan, an alkali washing tower, and an electrostatic precipitator. The tail gas outlet of the absorption tower is connected to the gas inlet of the condenser, the gas outlet of the condenser is connected to the washing tower, the gas in the washing tower is diluted by the washing tower, and the washing tower is connected to the tail gas inlet of the alkali washing tower through the smoke exhaust fan; the cooling water outlet of the cooling tower is connected to the cooling water inlet of the condenser through a cooling water circulation pump, and the condensate outlet of the condenser is connected to the spraying liquid pipeline connected to the absorption tower through a condensate circulation pump; an alkali washing circulation pump is provided on the alkali washing liquid circulation transmission pipeline of the alkali washing tower, and the alkali storage tank is connected to the alkali washing liquid circulation tank at the bottom of the alkali washing tower through an alkali unloading pump; the furnace gas outlet at the top of the alkali washing tower is connected to the electrostatic precipitator.

2. A tail gas treatment system for a hydrochloric acid regeneration device according to claim 1, characterized in that: The condensate outlet of the condenser is connected to a water collection tank, and the water collection tank is connected to a condensate circulation pump.

3. The tail gas treatment system of a hydrochloric acid regeneration device according to claim 1, characterized in that: The electrostatic precipitator is a wet electrostatic precipitator.

4. The tail gas treatment system of a hydrochloric acid regeneration device according to claim 1, characterized in that: The condenser is a horizontal tube-and-tube condenser, and the heat exchange tubes are graphite-modified PP tubes.

5. The tail gas treatment system of a hydrochloric acid regeneration device according to claim 1, characterized in that: The gas inlet, gas outlet, cooling water inlet and condensate outlet of the condenser are all provided with temperature and pressure monitoring devices.

6. The tail gas treatment system of a hydrochloric acid regeneration device according to claim 1, characterized in that: The cooling tower is a countercurrent glass fiber reinforced plastic cooling tower.

Images