Process for preparing acid from calcium chloride wastewater evaporation condensate water recovered to hydrochloric acid synthesis process

Abstract

The invention relates to the technical field of chemical production, in particular to an acid making process by recovering calcium chloride wastewater evaporation condensate water to a hydrochloric acid synthesis process. A condensate water pump and a heat exchanger are additionally arranged in a calcium chloride wastewater evaporation system, the condensate water is cooled and then conveyed to the hydrochloric acid synthesis process, and an opening is touched in front of a desalted water pipeline valve of a tail gas absorption tower; and adjusting the flow of condensate water by using a desalted water self-control valve to prepare hydrochloric acid. The condensate water generated by the evaporation system is conveyed to the hydrochloric acid synthesis process to prepare hydrochloric acid, so that the burden that the condensate water cannot be discharged can be reduced, the wastewater treatment system continuously treats wastewater at high load, meanwhile, the condensate water is recycled, the production cost is saved, and the problem of water resource shortage is solved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical production, and in particular to an acid-making process in which condensed water from evaporation of calcium chloride wastewater is recycled to a hydrochloric acid synthesis process. Background Art

[0002] In the current normal production process, the calcium chloride wastewater system is responsible for treating the calcium chloride wastewater generated by the titanium dioxide subsystem in the production of titanium dioxide. By adding Glauber's salt and soda ash into the reactor to remove calcium ions, sodium chloride is finally produced through evaporation concentration and dehydration. A large amount of condensed water will be generated during the evaporation process. Due to the fluctuation of calcium chloride wastewater indicators and the unstable operation of some equipment, the indicators of the condensed water fluctuate greatly and cannot be discharged, which increases the pressure of external drainage.

[0003] The hydrochloric acid synthesis process utilizes the property that hydrogen chloride is easily soluble in water to produce hydrochloric acid for self-use or take-away. The water used to absorb the hydrogen chloride is desalted water. However, due to the current sluggish hydrochloric acid market, a large increase in hydrochloric acid inventory and the high cost of desalted water, hydrochloric acid production continues to be at a loss. Summary of the invention

[0004] The object of the present invention is to provide an acid-making process for recycling condensed water from evaporation of calcium chloride wastewater to a hydrochloric acid synthesis step, so as to solve the problem in the above-mentioned background technology that the condensed water produced by the calcium chloride wastewater evaporation system can be directly discharged, but due to fluctuations in indicators, it cannot be discharged, resulting in a burden on external drainage.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A process for producing acid by evaporating condensed water from calcium chloride wastewater and recycling it to a hydrochloric acid synthesis process. A condensed water pump and a heat exchanger are added to the calcium chloride wastewater evaporation system. After cooling the condensed water, the condensed water is transported to the hydrochloric acid synthesis process. The condensed water is connected to the desalted water pipeline valve of the tail gas absorption tower, and the desalted water automatic control valve is used to adjust the condensed water flow rate to produce hydrochloric acid. The process specifically includes the following steps:

[0007] S10 wastewater pretreatment stage: collect wastewater from the calcium chloride production process, concentrate it and separate solid calcium chloride by heating and evaporation, and generate high-temperature steam and condensed water at the same time;

[0008] S20 adds condensate pump and heat exchanger: at the outlet of the evaporation system, install condensate pump to pump condensate to the heat exchanger for cooling. The heat exchanger uses external low-temperature medium as cooling source to reduce the condensate temperature to an appropriate range to meet the requirements of subsequent processes;

[0009] S30 Condensate delivery and flow control: The cooled condensate is delivered to the hydrochloric acid synthesis process through an additional condensate pump. During the delivery process, the desalted water automatic control valve is used for precise control. The flow of condensate is adjusted according to the actual needs of the hydrochloric acid synthesis process to ensure process stability and product quality.

[0010] S40 tail gas absorption and desalted water circulation: before conveying condensed water to the hydrochloric acid synthesis process, it needs to pass through the tail gas absorption tower desalted water pipeline valve front joint, and use the existing desalted water system to absorb and treat the tail gas, while ensuring the smooth circulation of desalted water; through the adjustment of the desalted water automatic control valve, the mixing ratio of condensed water and desalted water is optimized, and the efficiency and purity of hydrochloric acid synthesis are improved;

[0011] S50 hydrochloric acid synthesis process: the condensed water with adjusted flow rate is used as one of the raw materials to react with the hydrogen chloride gas produced by the synthesis furnace to generate hydrochloric acid. In this process, the primary graphite absorber is responsible for absorbing the remaining hydrogen chloride gas to ensure the safety and purity of the reaction environment. The hydrochloric acid generated by the reaction is collected in the hydrochloric acid intermediate tank for use or storage in subsequent processes.

[0012] Preferably, before the calcium chloride wastewater enters the evaporation system, a pretreatment unit is added, including a regulating tank, a filter and a neutralization tank, for removing suspended matter and heavy metal ion impurities in the wastewater.

[0013] Preferably, a coagulant for removing suspended solids in the wastewater is added to the regulating tank, and the coagulant is polyaluminium chloride or iron salt.

[0014] Preferably, the filter is a sand filter, a fiber filter or a microporous filter.

[0015] Preferably, an acid-base regulator for adjusting the pH value of the wastewater is added to the neutralization tank.

[0016] Preferably, the heat exchanger in step S20 is a plate heat exchanger or a heat pipe heat exchanger.

[0017] Preferably, the heat exchange medium in the heat exchanger is air or cold water.

[0018] Preferably, the temperature of the condensed water used in step S30 is 30-50°C.

[0019] Preferably, a precision filter or an ion exchange resin purifier is installed at the inlet of the condensate pump in step S30 to remove trace impurities and soluble salts in the condensate.

[0020] Preferably, the tail gas absorption tower has a built-in spray system.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. Resource recycling

[0023] Reduce water waste: By recycling the condensed water generated during the evaporation process and using it in the hydrochloric acid synthesis process, water resources can be recycled, the use of fresh water can be reduced, and water resources can be saved.

[0024] Improve resource utilization: Condensate still contains certain usable components, such as chlorides, etc. Direct discharge will cause resource waste. Recycling it for hydrochloric acid synthesis can maximize the use of these resources.

[0025] 2. Improved economic benefits

[0026] Reduce production costs: Recycling condensed water as one of the raw materials for hydrochloric acid synthesis reduces dependence on purchased raw materials, thereby reducing production costs.

[0027] Increase product output: Using recycled condensed water to synthesize hydrochloric acid can increase the output of hydrochloric acid and improve production efficiency.

[0028] 3. Enhanced environmental friendliness

[0029] Reduce wastewater discharge: By recycling condensed water, the amount of wastewater discharged is reduced, reducing the pollution load on the environment.

[0030] Reduce the difficulty of treatment: Harmful substances in wastewater are removed or concentrated to a certain extent during the evaporation process, which reduces the difficulty of subsequent treatment and reduces treatment costs.

[0031] 4. Process optimization and stabilization

[0032] Process optimization: Adding condensate pumps and heat exchangers to the calcium chloride wastewater evaporation system, as well as subsequent condensate delivery and flow control systems, makes the entire process more complete and optimized.

[0033] Improved production stability: Through precise flow control and optimized mixing ratio, the stability of the hydrochloric acid synthesis process and product quality can be ensured, and production efficiency and product qualification rate can be improved.

[0034] 5. Sustainable development

[0035] Compliance with environmental protection policies: This process complies with the national environmental protection policy requirements on energy conservation, emission reduction, and resource recycling, and helps enterprises achieve sustainable development.

[0036] Promote technological progress: During the process of process implementation, continuous technological innovation and optimization are needed to overcome technical difficulties and improve process efficiency, thereby promoting technological progress in related fields.

[0037] To sum up, the present acid-making process of recycling the condensed water from the evaporated calcium chloride wastewater to the hydrochloric acid synthesis process can reduce the burden of the condensed water that cannot be discharged by transporting the condensed water generated by the evaporation system to the hydrochloric acid synthesis process to produce hydrochloric acid, so that the wastewater treatment system can continuously treat the wastewater at a high load. At the same time, the condensed water can be recycled, which saves production costs and solves the problem of water shortage. It shows significant beneficial effects in resource recycling, economic benefit improvement, environmental friendliness enhancement, process optimization and stabilization, and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they provide further detailed explanations but do not constitute a limitation of the present invention.

[0039] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0040] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] Example 1: Basic Optimization Configuration

[0042] S10 wastewater pretreatment stage:

[0043] The wastewater first enters the equalization tank, where polyaluminium chloride is added as a coagulant to remove suspended matter in the wastewater.

[0044] The wastewater is then filtered through a sand filter to further remove suspended matter and some impurities.

[0045] The filtered wastewater enters the neutralization tank, and an appropriate amount of sodium hydroxide is added to adjust the pH value to neutral or slightly acidic to meet the requirements of the subsequent evaporation system.

[0046] S20 adds condensate pump and heat exchanger:

[0047] A high-efficiency condensate pump is installed at the outlet of the evaporation system to pump the high-temperature condensate to the plate heat exchanger.

[0048] The heat exchanger uses air as the cooling medium and reduces the condensed water temperature to 40°C through heat exchange.

[0049] S30 Condensate Delivery and Flow Control:

[0050] The cooled condensed water is transported to the hydrochloric acid synthesis process through a condensate pump. A desalted water automatic control valve is installed on the way to adjust the condensed water flow in real time according to the needs of the hydrochloric acid synthesis process.

[0051] Install a precision filter at the inlet of the condensate pump to ensure the cleanliness of the condensate before it enters the synthesis process.

[0052] S40 tail gas absorption and desalted water circulation:

[0053] Before being transported to the hydrochloric acid synthesis process, the condensed water passes through the desalted water pipeline valve of the tail gas absorption tower, and the tail gas is absorbed and treated by the spray system.

[0054] The desalted water automatic control valve adjusts the mixing ratio of condensed water and desalted water to optimize the efficiency of hydrochloric acid synthesis.

[0055] S50 hydrochloric acid synthesis process:

[0056] The condensed water with adjusted flow rate reacts with hydrogen chloride gas in the synthesis furnace to generate hydrochloric acid.

[0057] The first-stage graphite absorber ensures the purity of the reaction environment, and the generated hydrochloric acid is collected in the hydrochloric acid intermediate tank.

[0058] Example 2: High-performance configuration

[0059] S10 wastewater pretreatment stage:

[0060] Use polyaluminium chloride and iron salt composite coagulants to improve the efficiency of suspended matter removal.

[0061] The filter is upgraded to a fiber filter to enhance the filtering effect.

[0062] An automatic pH adjustment system is added to the neutralization tank to accurately control the pH value of the wastewater.

[0063] S20 adds condensate pump and heat exchanger:

[0064] A heat pipe heat exchanger is used to improve heat exchange efficiency and further reduce the condensed water temperature to 35°C.

[0065] The heat exchange medium is circulating cold water, which ensures the long-term stable operation of the heat exchanger.

[0066] S30 Condensate Delivery and Flow Control:

[0067] An ion exchange resin purifier is added in front of the condensate pump to deeply remove soluble salts in the condensate.

[0068] The desalted water automatic control valve has been upgraded to an intelligent control system to achieve more precise flow regulation.

[0069] S40 tail gas absorption and desalted water circulation:

[0070] The tail gas absorption tower spray system is upgraded to high-efficiency atomization spray to improve the tail gas absorption efficiency.

[0071] Add online monitoring device to the desalted water circulation system to ensure stable water quality

[0072] S50 hydrochloric acid synthesis process:

[0073] Introduce online analyzers to monitor hydrochloric acid concentration and purity in real time to ensure product quality.

[0074] Optimize the operating parameters of the synthesis furnace to improve the efficiency of hydrochloric acid synthesis.

[0075] Example 3: Environmentally friendly and energy-saving configuration

[0076] S10 wastewater pretreatment stage:

[0077] A biological pretreatment unit is introduced to utilize microorganisms to degrade organic matter and some heavy metal ions in the wastewater.

[0078] The selection of coagulants and filters focuses on environmentally friendly materials to reduce secondary pollution during the treatment process.

[0079] S20 adds condensate pump and heat exchanger:

[0080] The heat exchanger uses waste heat recovery technology to recover the heat released during the cooling process and use it to preheat other process water, thus achieving energy recycling.

[0081] The heat exchange medium is low-temperature circulating water within the plant, which reduces external energy consumption.

[0082] S30 Condensate Delivery and Flow Control:

[0083] The condensate pump adopts variable frequency speed regulation technology to automatically adjust the speed according to actual needs and reduce energy consumption.

[0084] The desalted water automatic control valve is linked to the condensate pump to optimize the overall energy consumption of the system.

[0085] S40 tail gas absorption and desalted water circulation:

[0086] The exhaust gas absorption tower adds an exhaust gas recirculation system to reintroduce part of the absorbed exhaust gas into the synthesis furnace to reduce exhaust gas emissions.

[0087] The desalted water circulation system is equipped with an automatic sewage discharge device to regularly discharge impurities and aging substances in the system.

[0088] S50 hydrochloric acid synthesis process:

[0089] Introduce green catalysts to reduce energy consumption and pollutant emissions during the synthesis process.

[0090] Optimize the exhaust gas treatment system to ensure that the exhaust gas meets national environmental protection standards.

[0091] The present invention has the following advantages:

[0092] 1. Resource recycling

[0093] Reduce water waste: By recycling the condensed water generated during the evaporation process and using it in the hydrochloric acid synthesis process, water resources can be recycled, the use of fresh water can be reduced, and water resources can be saved.

[0094] Improve resource utilization: Condensate still contains certain usable components, such as chlorides, etc. Direct discharge will cause resource waste. Recycling it for hydrochloric acid synthesis can maximize the use of these resources.

[0095] 2. Improved economic benefits

[0096] Reduce production costs: Recycling condensed water as one of the raw materials for hydrochloric acid synthesis reduces dependence on purchased raw materials, thereby reducing production costs.

[0097] Increase product output: Using recycled condensed water to synthesize hydrochloric acid can increase the output of hydrochloric acid and improve production efficiency.

[0098] 3. Enhanced environmental friendliness

[0099] Reduce wastewater discharge: By recycling condensed water, the amount of wastewater discharged is reduced, reducing the pollution load on the environment.

[0100] Reduce the difficulty of treatment: Harmful substances in wastewater are removed or concentrated to a certain extent during the evaporation process, which reduces the difficulty of subsequent treatment and reduces treatment costs.

[0101] 4. Process optimization and stabilization

[0102] Process optimization: Adding condensate pumps and heat exchangers to the calcium chloride wastewater evaporation system, as well as subsequent condensate delivery and flow control systems, makes the entire process more complete and optimized.

[0103] Improved production stability: Through precise flow control and optimized mixing ratio, the stability of the hydrochloric acid synthesis process and product quality can be ensured, and production efficiency and product qualification rate can be improved.

[0104] 5. Sustainable development

[0105] Compliance with environmental protection policies: This process complies with the national environmental protection policy requirements on energy conservation, emission reduction, and resource recycling, and helps enterprises achieve sustainable development.

[0106] Promote technological progress: During the process of process implementation, continuous technological innovation and optimization are needed to overcome technical difficulties and improve process efficiency, thereby promoting technological progress in related fields.

[0107] In summary, the acid production process of recycling the evaporation condensate of calcium chloride wastewater to the hydrochloric acid synthesis process has shown significant beneficial effects in resource recycling, economic benefit improvement, environmental friendliness enhancement, process optimization and stabilization, and sustainable development.

[0108] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A process for producing acid by recycling condensed water from evaporation of calcium chloride wastewater to a hydrochloric acid synthesis process, characterized in that: A condensate pump and a heat exchanger are added to the calcium chloride wastewater evaporation system to cool the condensate and then transport it to the hydrochloric acid synthesis process. The condensate is connected to the tail gas absorption tower desalted water pipeline valve in front of the valve, and the desalted water automatic control valve is used to adjust the condensate flow rate to produce hydrochloric acid. The specific steps include: S10 wastewater pretreatment stage: collect wastewater from the calcium chloride production process, concentrate it and separate solid calcium chloride by heating and evaporation, and generate high-temperature steam and condensed water at the same time; S20 adds condensate pump and heat exchanger: at the outlet of the evaporation system, install condensate pump to pump condensate to the heat exchanger for cooling. The heat exchanger uses external low-temperature medium as cooling source to reduce the condensate temperature to an appropriate range to meet the requirements of subsequent processes; S30 Condensate delivery and flow control: The cooled condensate is delivered to the hydrochloric acid synthesis process through an additional condensate pump. During the delivery process, the desalted water automatic control valve is used for precise control. The flow of condensate is adjusted according to the actual needs of the hydrochloric acid synthesis process to ensure process stability and product quality. S40 tail gas absorption and desalted water circulation: before conveying condensed water to the hydrochloric acid synthesis process, it needs to pass through the tail gas absorption tower desalted water pipeline valve front joint, and use the existing desalted water system to absorb and treat the tail gas, while ensuring the smooth circulation of desalted water; through the adjustment of the desalted water automatic control valve, the mixing ratio of condensed water and desalted water is optimized, and the efficiency and purity of hydrochloric acid synthesis are improved; S50 hydrochloric acid synthesis process: the condensed water with adjusted flow rate is used as one of the raw materials to react with the hydrogen chloride gas produced by the synthesis furnace to generate hydrochloric acid. In this process, the primary graphite absorber is responsible for absorbing the remaining hydrogen chloride gas to ensure the safety and purity of the reaction environment. The hydrochloric acid generated by the reaction is collected in the hydrochloric acid intermediate tank for use or storage in subsequent processes.

2. The acid-making process of recycling condensed water from evaporation of calcium chloride wastewater to a hydrochloric acid synthesis step according to claim 1, characterized in that: Before the calcium chloride wastewater enters the evaporation system, a pretreatment unit is added, including a regulating tank, a filter and a neutralization tank, to remove suspended matter and heavy metal ion impurities in the wastewater.

3. The acid-making process of recycling condensed water from evaporation of calcium chloride wastewater to a hydrochloric acid synthesis step according to claim 2, characterized in that: The regulating tank is added with a coagulant for removing suspended solids in the wastewater, and the coagulant is polyaluminium chloride and iron salt.

4. The acid-making process of recycling condensed water from evaporation of calcium chloride wastewater to a hydrochloric acid synthesis step according to claim 2, characterized in that: The filter is a sand filter, a fiber filter or a microporous filter.

5. The acid-making process of recycling condensed water from evaporation of calcium chloride wastewater to a hydrochloric acid synthesis step according to claim 2, characterized in that: Acid-base regulator for adjusting the pH value of wastewater is added into the neutralization tank.

6. The acid-making process of recycling condensed water from evaporation of calcium chloride wastewater to a hydrochloric acid synthesis step according to claim 1, characterized in that: The heat exchanger in step S20 is a plate heat exchanger or a heat pipe heat exchanger.

7. The acid-making process of recycling condensed water from evaporation of calcium chloride wastewater to a hydrochloric acid synthesis step according to claim 1, characterized in that: The heat exchange medium in the heat exchanger is air or cold water.

8. The acid-making process of recycling condensed water from evaporation of calcium chloride wastewater to a hydrochloric acid synthesis step according to claim 1, characterized in that: The temperature of the condensed water used in step S30 is 30-50°C.

9. The acid-making process of recycling condensed water from evaporation of calcium chloride wastewater to a hydrochloric acid synthesis step according to claim 1, characterized in that: In step S30, a precision filter or an ion exchange resin purifier is installed at the input port of the condensate pump to remove trace impurities and soluble salts in the condensate.

10. The acid-making process of recycling condensed water from evaporation of calcium chloride wastewater to a hydrochloric acid synthesis step according to claim 1, characterized in that: The tail gas absorption tower has a built-in spray system.

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