Dechlorination device for bleaching liquid in calcium hypochlorite production

Abstract

The utility model relates to a bleaching liquid dechlorination device in calcium hypochlorite production, which comprises a reduction kettle, a vacuum dechlorination tower and a tail gas alkali absorption tower, an inlet of the reduction kettle is communicated with a bleaching liquid source in the calcium hypochlorite production, and a liquid outlet of the reduction kettle is communicated with an inlet of the vacuum dechlorination tower. The exhaust port is communicated with the inlet of the tail gas alkali absorption tower, and the hydrochloric acid feeding port is communicated with an external hydrochloric acid source; an outlet of the vacuum dechlorination tower is communicated with an inlet of the tail gas alkali absorption tower; an alkali liquor feeding port of the tail gas alkali absorption tower is communicated with an external alkali liquor source, an outlet of the tail gas alkali absorption tower is communicated with a chimney, and a liquor outlet of the tail gas alkali absorption tower is communicated to a calcium hypochlorite production line. The device can effectively improve the dechlorination effect of the bleaching liquid, simplify the process flow, reduce manual intervention, lower the production cost and improve the economic benefit.

Description

Technical Field

[0001] This utility model relates to a chemical apparatus, particularly an apparatus used in the production of calcium hypochlorite, specifically a dechlorination apparatus for bleaching solutions in the production of calcium hypochlorite. Background Technology

[0002] The production of calcium hypochlorite generates a large amount of bleaching liquor. The main components of this liquor are Ca(ClO)₂, NaClO, NaCl, CaCl₂, and H₂O. Therefore, if discharged directly into the environment without treatment, it will severely pollute the environment.

[0003] Currently, the main methods for treating bleaching liquor include: (1) bleaching pulp with bleaching liquor; (2) treating cyanide-containing wastewater with bleaching liquor, oxidizing cyanide into carbon dioxide and nitrogen, and the treated cyanide-containing wastewater can meet discharge standards; (3) treating industrial waste residue fly ash with bleaching liquor; (4) using chlorine recovered from intermittent acidification of bleaching liquor to produce sodium hypochlorite, and using the acidified and dechlorinated bleaching liquor to produce calcium carbonate, etc. However, the above treatment methods have the following shortcomings: the bleaching effect of bleaching liquor is not good; the intermittent acidification operation of bleaching liquor is complicated and the manual load is large; the treatment process is long and requires a lot of equipment, which causes great trouble for production enterprises.

[0004] Therefore, improvements are urgently needed to better meet production demands. Utility Model Content

[0005] The purpose of this invention is to address the problems encountered in the treatment of by-product liquids in calcium hypochlorite production, and to provide a dechlorination device for bleaching liquid in calcium hypochlorite production. This device can effectively improve the dechlorination effect of bleaching liquid, simplify the process flow, reduce manual intervention, and lower production costs.

[0006] The technical solution of this utility model is:

[0007] A dechlorination device for bleaching liquor in calcium hypochlorite production includes a reduction vessel, a vacuum dechlorination tower, and a tail gas alkali absorption tower.

[0008] The inlet of the reduction vessel is connected to the bleaching liquid source in the calcium hypochlorite production, its outlet is connected to the liquid phase inlet of the vacuum dechlorination tower, its exhaust port is connected to the gas phase inlet of the tail gas alkali absorption tower, and its hydrochloric acid feed port is connected to an external hydrochloric acid source.

[0009] The gas phase outlet of the vacuum dechlorination tower is connected to the inlet of the tail gas alkali absorption tower.

[0010] The alkaline feed port of the tail gas alkaline absorption tower is connected to an external alkaline source, its outlet is connected to a chimney, and its discharge port is connected to the calcium hypochlorite production line.

[0011] Furthermore, it also includes a bleaching solution tank, the inlet of which is connected to the bleaching solution source, and the outlet of which is connected to the inlet of the reduction vessel, so as to temporarily store the bleaching solution.

[0012] Furthermore, the outlet of the reduction vessel is connected to the circulation port of the reduction vessel via a vessel liquid circulation pump, forming a vessel liquid circulation pipeline; the inlet of the vacuum dechlorination tower is connected to the vessel liquid circulation pipeline; an online pH monitor is also installed on the vessel liquid circulation pipeline; the online pH monitor is also electrically connected to the first shut-off valve located at the hydrochloric acid feed port, and can control the opening and closing of the shut-off valve according to the detected pH value; a liquid level control instrument is installed on the reduction vessel.

[0013] Furthermore, the lower and upper parts of the vacuum dechlorination tower are respectively provided with a circulation outlet and a circulation inlet; the circulation outlet and circulation inlet are connected through the vacuum dechlorination tower circulation pipeline; the vacuum dechlorination tower circulation pipeline is equipped with a vacuum dechlorination tower circulation pump.

[0014] Furthermore, it also includes a neutralization tank, the inlet of which is connected to the residual liquid outlet of the vacuum dechlorination tower, the outlet of which is connected to the discharge pipeline, and the calcium hydroxide feed port of which is connected to the calcium hydroxide solution source; the neutralization tank is equipped with an online pH monitor.

[0015] Furthermore, the drain outlet of the tail gas alkali absorption tower is connected to the alkali circulation port of the tail gas alkali absorption tower after passing through the alkali circulation pump, forming an alkali circulation pipeline; it also includes a buffer tank, the inlet of which is connected to the alkali circulation pipeline, and the outlet of which is connected to the calcium hypochlorite production line.

[0016] Furthermore, the alkali circulation pipeline is equipped with an alkali circulation cooler, an ORP instrument, and a second shut-off valve connected in series; a third shut-off valve is provided at the inlet of the buffer tank; the second shut-off valve and the third shut-off valve are electrically connected to the ORP instrument respectively.

[0017] Furthermore, the bleaching solution tank is equipped with a liquid level monitoring device, which can detect the liquid level in the bleaching solution tank and control the flow rate of the bleaching solution flowing into the bleaching solution tank accordingly; the outlet of the bleaching solution tank is equipped with a bleaching solution transfer pump.

[0018] Furthermore, the inlet of the tail gas alkali absorption tower is equipped with a tail gas delivery pump, and its outlet is connected to the chimney after passing through an induced draft fan.

[0019] The beneficial effects of this utility model are:

[0020] 1) This utility model realizes the dechlorination of bleaching liquid and the resource utilization of waste chlorine gas. The dechlorination waste liquid can be used as brine extraction water, and the sodium hypochlorite that absorbs waste chlorine with alkali can be reused as raw material for the bleaching powder preparation device.

[0021] 2) This utility model has a high degree of automation. By precisely controlling key parameters such as pH value and liquid level, it ensures a stable and reliable reaction process and significantly reduces human intervention.

[0022] 3) The process of this utility model is simple and efficient, which can significantly reduce energy consumption and investment costs and improve economic benefits. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of this utility model.

[0024] Among them, 1-bleaching liquid tank, 2-bleaching liquid transfer pump, 3-reduction kettle, 4-kettle liquid circulation pump, 5-vacuum dechlorination tower circulation pump, 6-vacuum dechlorination tower, 7-vacuum dechlorination tower discharge pump, 8-neutralization tank, 9-self-priming tank, 10-transfer pump, 11-tail gas transfer pump, 12-tail gas alkali absorption tower, 13-alkali circulation cooler, 14-alkali circulation pump, 15-induced draft fan, 16-chimney, 17-buffer tank, 18-buffer tank transfer pump, 19-first shut-off valve, 20-third shut-off valve; 21-second shut-off valve. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] like Figure 1 As shown.

[0027] A dechlorination device for bleaching liquor in calcium hypochlorite production includes a bleaching liquor tank 1, a reduction vessel 3, a vacuum dechlorination tower 6, a neutralization tank 8, and a tail gas alkaline absorption tower 12.

[0028] The bleaching solution tank 1 is constructed of concrete. Its inlet is connected to the bleaching solution source in calcium hypochlorite production, and its outlet is connected to the inlet of the reduction reactor 3 via a bleaching solution transfer pump 2, thus allowing for temporary storage of the bleaching solution. Preferably, the bleaching solution tank 1 is equipped with a liquid level monitoring device, which can detect the liquid level in the tank and control the flow rate of the bleaching solution flowing into it to achieve a stable supply to the reduction reactor.

[0029] The outlet of the reduction vessel 3 is connected to the circulation port of the reduction vessel via the vessel liquid circulation pump 4, forming a vessel liquid circulation pipeline. This vessel liquid circulation pipeline is connected to the liquid phase inlet of the vacuum dechlorination tower 6, so that part of the vessel liquid flows into the vacuum dechlorination tower 6 and the other part flows back into the reduction vessel to continue the reaction.

[0030] The exhaust port of the reduction vessel 3 is connected to the gas phase inlet of the tail gas alkaline absorption tower 12, so that the chlorine-containing tail gas generated by the reaction is fed into the tail gas alkaline absorption tower for treatment. Simultaneously, the hydrochloric acid feed port on the reduction vessel 3 is connected to an external hydrochloric acid source, so that hydrochloric acid can be supplied to meet the reaction requirements. Preferably, the reduction vessel 3 is equipped with a liquid level control device to monitor the internal liquid level and ensure safety.

[0031] Furthermore, the reactor liquid circulation pipeline is also equipped with an online pH monitor, which is electrically connected to the first shut-off valve 19 located at the hydrochloric acid feed port. Thus, the opening and closing of the first shut-off valve can be controlled according to the detected pH value to ensure that the pH value in the reduction reactor meets the requirements.

[0032] The vacuum dechlorination tower 6 can efficiently absorb free chlorine in waste liquid under vacuum conditions through a gas-liquid countercurrent contact mechanism, significantly reducing the chlorine content of the waste liquid. The outlet of the vacuum dechlorination tower 6 is connected to the inlet of the tail gas alkaline absorption tower, so that the generated chlorine-containing tail gas is combined with the tail gas from the reduction reactor and then transported to the tail gas alkaline absorption tower. At the same time, the lower and upper parts of the vacuum dechlorination tower 6 are respectively provided with a circulation outlet and a circulation inlet, and these circulation outlets and inlets are connected to the vacuum dechlorination tower circulation pump 5 through a vacuum dechlorination tower circulation pipeline to circulate the feed liquid in the vacuum dechlorination tower.

[0033] The neutralization tank 8 is constructed of concrete. Its inlet is connected to the residual liquid outlet of the vacuum dechlorination tower 6 via a vacuum dechlorination tower discharge pump 7. Its outlet is connected to a discharge pipeline, and its calcium hydroxide feed port is connected to a calcium hydroxide solution source. This allows the residual liquid from the vacuum dechlorination tower to be fed into the tank, where the calcium hydroxide solution undergoes an acid-base neutralization reaction with the residual liquid. Once the pH value meets the discharge standards, the liquid is discharged through the discharge pipe. Preferably, the neutralization tank 8 is equipped with an online pH monitoring system to detect the pH value and ensure that the treated wastewater meets the neutral discharge standard. Simultaneously, the discharge pipe is equipped with a self-priming tank 9 and a transfer pump 10 to ensure smooth discharge.

[0034] The tail gas alkaline absorption tower 12 is a high-efficiency spray tower, mainly made of FRP with an anti-corrosion lining. It achieves efficient absorption through the chemical reaction between alkaline solution and chlorine gas, and simultaneously converts chlorine gas into reusable sodium hypochlorite. The bottom of the tail gas alkaline absorption tower 12 is equipped with an alkaline solution feed port, which can be connected to an external alkaline solution source for timely addition of sodium hydroxide solution.

[0035] The outlet of the tail gas alkaline absorption tower 12 is connected to the chimney 16 after passing through the induced draft fan 15, so as to stably discharge the tail gas.

[0036] The drain outlet of the tail gas alkaline absorption tower 12 sequentially passes through the alkaline circulation pump 14, the alkaline circulation cooler 13, the ORP instrument, and the second shut-off valve, and then connects to the alkaline liquid circulation port located at the top of the tail gas alkaline absorption tower 12, forming an alkaline liquid circulation pipeline. This allows the reacted solution to be reintroduced into the tower for further reaction, ensuring complete reaction. Simultaneously, this alkaline liquid circulation pipeline sequentially passes through the third shut-off valve 20, the buffer tank 17, and the buffer tank transfer pump 18, and then connects to the calcium hypochlorite production line, allowing the sodium hypochlorite solution from the alkaline absorption of waste chlorine to be reused as a calcium hypochlorite raw material.

[0037] The ORP (Oxidation-Reduction Potential) meter is electrically connected to both the second shut-off valve 21 and the third shut-off valve 20. Therefore, based on the ORP value of the solution in the alkali circulation pipeline, the meter determines the opening and closing of the second shut-off valve and the third shut-off valve. Specifically, if the ORP value does not meet the set value, the third shut-off valve 20 closes, the second shut-off valve 21 opens, and the solution returns to the tail gas alkali absorption tower for recycling. If the ORP value meets the set value, the third shut-off valve 20 opens, the second shut-off valve 21 closes, and the solution flows through the buffer tank to the calcium hypochlorite production line.

[0038] The alkali circulation cooler 13 can cool the circulating liquid material to meet production requirements. The cooling medium of the alkali circulation cooler 13 can be cooling water, which is convenient to use.

[0039] Furthermore, the inlet of the tail gas alkali absorption tower 12 is equipped with a tail gas transfer pump 11 to improve transmission efficiency. Moreover, the tail gas alkali absorption tower can be configured as a single tower, a dual-tower series operation, or a three-tower multi-stage configuration, depending on the operating conditions, to fully meet production needs.

[0040] The working process of this utility model is as follows:

[0041] (1) The bleaching solution is temporarily stored in a bleaching solution tank, and the liquid level is controlled by a liquid level monitoring device. Then, the bleaching solution is transported to the reduction reactor by a bleaching solution transfer pump, and 32% industrial hydrochloric acid is injected into the reduction reactor at the same time to carry out an oxidation-reduction reaction, generate chlorine gas and release heat of reaction;

[0042] (2) The mixture after the reaction is divided into two paths by the reactor liquid circulation pump: part of it is returned to the reduction reactor for circulation reaction, and part of it is sent to the vacuum dechlorination tower; during this period, the pH value of the mixture is monitored by the pH online monitoring instrument, and the opening and closing of the first shut-off valve is controlled accordingly to ensure that the pH value in the reduction reactor meets the production requirements.

[0043] (3) The vacuum dechlorination tower achieves efficient absorption of free chlorine in the waste liquid through a gas-liquid countercurrent contact mechanism, and circulates the feed liquid through the vacuum dechlorination tower circulation pump. The escaped chlorine gas is sent to the tail gas alkali absorption tower through the tail gas transfer pump.

[0044] (4) The dechlorination residue is pumped from the vacuum dechlorination tower to the neutralization tank and neutralized with 20% calcium hydroxide solution (temperature ≤50℃). The waste liquid with pH ≥7 after neutralization is discharged through the self-priming tank and the transfer pump.

[0045] (5) The chlorine-containing tail gas generated by the reduction reactor and vacuum dechlorination tower is transported to the tail gas alkali absorption tower via a tail gas transfer pump. A suitable concentration (32%) sodium hydroxide solution is used for countercurrent absorption within the tower, and the alkali absorption solution is circulated and cooled by an alkali circulation cooler and an alkali circulation pump. After the chlorine content in the treated tail gas meets national emission standards, it is discharged into the chimney via an induced draft fan. Simultaneously, fresh alkali solution is replenished to the vacuum dechlorination tower as needed to maintain absorption efficiency.

[0046] (6) During the absorption of chlorine-containing tail gas in the vacuum dechlorination tower, sodium hypochlorite solution is generated simultaneously. This sodium hypochlorite solution flows out from the bottom of the tower and enters the alkali circulation pipeline, and the ORP value of the solution is monitored by an ORP instrument. If it does not meet the set value, the third shut-off valve is closed and the second shut-off valve is opened, and the solution flows back to the tail gas alkali absorption tower for circulation reaction; if it meets the set value, the third shut-off valve is opened and the second shut-off valve is closed, so that the solution flows to the buffer tank, and then flows to the calcium hypochlorite production after passing through the buffer tank transfer pump, realizing reuse.

[0047] All the devices described in this utility model are conventional equipment in the art. However, through the inventive process design of this application, this utility model has the following advantages:

[0048] 1) By continuously adding hydrochloric acid, sodium hydroxide and calcium hydroxide, the dechlorination of bleaching liquor and the resource utilization of waste chlorine gas were realized, and the dechlorination waste liquid could be used as brine extraction water, and the sodium hypochlorite that absorbs waste chlorine with alkali could be reused as raw material for the bleaching powder unit.

[0049] (2) By equipping the system with instruments and valves such as pH meter, liquid level control, and shut-off valve, the automation level is improved, and by precisely controlling key parameters such as pH value and liquid level, the reaction process is ensured to be stable and reliable, and manual intervention is significantly reduced;

[0050] (3) The process is simple and efficient. Only kettles, tanks, pumps and towers are needed to complete the waste liquid treatment, which greatly reduces energy consumption and investment costs.

[0051] The parts not covered in this utility model are the same as or can be implemented using existing technologies.

Claims

1. A dechlorination device for bleaching liquor in calcium hypochlorite production, comprising a reduction vessel, a vacuum dechlorination tower, and a tail gas alkaline absorption tower, characterized in that, The inlet of the reduction vessel is connected to the bleaching liquid source in the calcium hypochlorite production, its outlet is connected to the liquid phase inlet of the vacuum dechlorination tower, its exhaust port is connected to the gas phase inlet of the tail gas alkali absorption tower, and its hydrochloric acid feed port is connected to an external hydrochloric acid source. The gas phase outlet of the vacuum dechlorination tower is connected to the inlet of the tail gas alkali absorption tower. The alkaline feed port of the tail gas alkaline absorption tower is connected to an external alkaline source, its outlet is connected to a chimney, and its discharge port is connected to the calcium hypochlorite production line.

2. The dechlorination device for bleaching liquor in calcium hypochlorite production according to claim 1, characterized in that, It also includes a bleaching tank, the inlet of which is connected to the bleaching liquid source, and the outlet of which is connected to the inlet of the reduction vessel.

3. The dechlorination device for bleaching liquor in calcium hypochlorite production according to claim 1, characterized in that, The outlet of the reduction vessel is connected to the circulation port of the reduction vessel via a vessel liquid circulation pump, forming a vessel liquid circulation pipeline; the inlet of the vacuum dechlorination tower is connected to the vessel liquid circulation pipeline; an online pH monitor is also installed on the vessel liquid circulation pipeline; the online pH monitor is also electrically connected to the first shut-off valve located at the hydrochloric acid feed port, and can control the opening and closing of the shut-off valve according to the detected pH value; a liquid level control instrument is installed on the reduction vessel.

4. The dechlorination device for bleaching liquor in calcium hypochlorite production according to claim 1, characterized in that, The lower and upper parts of the vacuum dechlorination tower are respectively provided with a circulation outlet and a circulation inlet; the circulation outlet and circulation inlet are connected through the vacuum dechlorination tower circulation pipeline; the vacuum dechlorination tower circulation pipeline is equipped with a vacuum dechlorination tower circulation pump.

5. The dechlorination device for bleaching liquor in calcium hypochlorite production according to claim 1, characterized in that, It also includes a neutralization tank, the inlet of which is connected to the residual liquid outlet of the vacuum dechlorination tower, the outlet of which is connected to the discharge pipeline, and the calcium hydroxide feed port of which is connected to the calcium hydroxide solution source; the neutralization tank is equipped with an online pH monitor.

6. The dechlorination device for bleaching liquor in calcium hypochlorite production according to claim 1, characterized in that, The drain outlet of the tail gas alkali absorption tower is connected to the alkali circulation port of the tail gas alkali absorption tower after passing through the alkali circulation pump, forming an alkali circulation pipeline; it also includes a buffer tank, the inlet of which is connected to the alkali circulation pipeline, and the outlet of which is connected to the calcium hypochlorite production line.

7. The dechlorination device for bleaching liquor in calcium hypochlorite production according to claim 6, characterized in that, The alkali circulation pipeline is equipped with an alkali circulation cooler, an ORP instrument, and a second shut-off valve connected in series; a third shut-off valve is provided at the inlet of the buffer tank; the second and third shut-off valves are electrically connected to the ORP instrument.

8. The dechlorination device for bleaching liquor in calcium hypochlorite production according to claim 2, characterized in that, The bleaching solution tank is equipped with a liquid level monitoring device, which can detect the liquid level in the tank and control the flow rate of the bleaching solution flowing into the tank accordingly; the outlet of the bleaching solution tank is equipped with a bleaching solution transfer pump.

9. The dechlorination device for bleaching liquor in calcium hypochlorite production according to claim 1, characterized in that, The tail gas alkaline absorption tower is equipped with a tail gas conveying pump at its inlet, and its outlet is connected to the chimney after passing through an induced draft fan.

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