A heating assistance system and process for thermal catalytic reactions

Abstract

The present invention relates to a heating assistance system and process for thermal catalytic reaction, including the steps: wastewater in the raw water tank enters a four-stage heat exchanger through a feed pump, and the first-stage heat exchanger provides heat source for the four-stage heat exchanger to conduct the first-stage heating of the wastewater; it enters the first-stage heat exchanger, and the hot water in the hot water tank is recycled through a circulating hot water pump to conduct the second-stage heating of the wastewater; it enters the second-stage heat exchanger, and steam provides heat source for the second-stage heat exchanger to conduct the third-stage heating; the temperature is detected and the wastewater temperature at the outlet end of the second-stage heat exchanger is adjusted to reach the thermal catalytic reaction temperature range; the wastewater undergoes thermal catalytic reaction in the reactor. The beneficial effects of the present invention are: a heat exchange system for efficient cascaded utilization of heat is constructed, the energy is used in a cascaded manner through multiple heat exchangers, and the recycling of hot water is realized by connecting the hot water tank and the first-stage heat exchanger through a circulating hot water pump, maximizing the energy utilization and reducing the demand for fresh steam in the treatment process.

Description

Technical Field

[0001] The present invention belongs to the field of wastewater treatment, and particularly relates to a heating assistance system and process for thermal catalytic reaction, which can be used as a preheating system for persulfate thermal catalytic chemical reaction of high-salt and high-COD organic wastewater. Background Art

[0002] With the rapid development of contemporary social economy, the discharge of industrial wastewater has increased sharply, leading to serious water pollution problems. There are a wide variety of toxic and harmful substances in industrial wastewater. Especially, wastewater from coal chemical industry, printing and dyeing, pharmaceutical industry, etc. contains high concentrations of organic pollutants. The wastewater has enhanced resistance to photolysis, biodegradation, and oxidation, and has characteristics such as strong toxicity, poor biodegradability, and complex pollutant component content, which are the difficulties in current wastewater treatment. Existing advanced oxidation treatment technologies can effectively degrade most of the organic substances, but for some persistent organic pollutants (POPs), such as polycyclic aromatic hydrocarbons, perfluorooctane, hexabromobiphenyl, hexachlorobenzene, sulfonic acids, etc., stronger external energy fields need to be combined with advanced oxidation for treatment and degradation to achieve the desired effect.

[0003] From the current research status at home and abroad, in recent years, the persulfate thermal catalytic advanced oxidation technology has always been a research hotspot in the field of environmental catalysis. However, due to the complex process of this technology and the need for a large amount of heat source for heating, it has not yet emerged from the laboratory, and there is no practical technology, process, equipment, and material that can be applied in engineering in China. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a heating assistance system and process for thermal catalytic reaction.

[0005] This heating assistance system for thermal catalytic reaction includes: a raw water tank, a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, a quaternary heat exchanger, a reactor, and a hot water tank;

[0006] The raw water tank is connected to the quaternary heat exchanger and the tertiary heat exchanger respectively through two water pipes. The quaternary heat exchanger is connected to the primary heat exchanger, and both the primary heat exchanger and the tertiary heat exchanger are connected to the secondary heat exchanger. A temperature sensor is provided at the outlet end of the secondary heat exchanger. The outlet end of the secondary heat exchanger is connected to the raw water tank, the reactor, and the steam pipeline respectively through a circulation valve, an outlet valve, and a steam valve. A return water valve is also provided at the outlet end of the secondary heat exchanger. The circulation valve, the outlet valve, and the steam valve are all connected to the temperature sensor at the outlet end of the secondary heat exchanger;

[0007] The reactor is connected to a hot water tank, and the hot water tank is connected to a primary heat exchanger through a circulating hot water pump; the hot water tank is also equipped with a temperature sensor, and the hot water tank is also connected to a steam pipeline through a steam valve, and the temperature sensor at the hot water tank of the steam valve; the temperature of the steam is higher than ℃, and the temperature of the hot water in the hot water tank is 50-110 °C.

[0008] Preferably: the outlet of the raw water tank is connected to the inlet of the feed pump, and the outlet of the feed pump is divided into a main path and a branch path. The main path is connected to a four-stage heat exchanger, and the branch path is connected to a three-stage heat exchanger.

[0009] Preferably: temperature sensors are also respectively provided in the upper, middle and lower parts of the hot water tank, and a heating coil is also provided in the hot water tank.

[0010] Preferably: flow sensors are provided on both the feed pump and the steam pipeline.

[0011] Preferably: the heat exchange efficiencies of the primary heat exchanger, secondary heat exchanger, tertiary heat exchanger and quaternary heat exchanger are all greater than or equal to 98.5%.

[0012] The heating process of this heating auxiliary system for thermal catalytic reaction includes the following steps:

[0013] Step 1, first-stage heating: The wastewater in the raw water tank enters the quaternary heat exchanger through the feed pump, and the primary heat exchanger provides heat source for the quaternary heat exchanger to carry out first-stage heating of the wastewater;

[0014] Step 2, second-stage heating: The wastewater after the first-stage heating enters the primary heat exchanger from the quaternary heat exchanger, and the hot water in the hot water tank is recycled through the circulating hot water pump to provide heat source for the primary heat exchanger to carry out second-stage heating of the wastewater;

[0015] Step 3, third-stage heating: The wastewater after the second-stage heating enters the secondary heat exchanger from the primary heat exchanger, and steam provides heat source for the secondary heat exchanger to carry out third-stage heating;

[0016] Step 4, temperature detection: When the temperature sensor shows that the temperature of the wastewater at the outlet end of the secondary heat exchanger is lower than the minimum value of the thermal catalytic reaction temperature, the circulation valve opens, so that the wastewater enters the raw water tank, and steps 1 to 4 are repeated until the temperature of the wastewater at the outlet end of the secondary heat exchanger reaches the thermal catalytic reaction temperature range;

[0017] When the temperature sensor shows that the temperature of the wastewater at the outlet end of the secondary heat exchanger is higher than or equal to the thermal catalytic reaction temperature, the outlet valve opens, so that the wastewater enters the reactor and step 5 is implemented;

[0018] Step 5, thermal catalytic reaction: The wastewater undergoes a thermal catalytic reaction in the reactor and then flows into the hot water tank for reuse in the second-stage heating.

[0019] Preferably, when the device is cold-started, steam is used as the heat source and high-COD organic wastewater is used as the raw water. After the steam enters the secondary heat exchanger, it returns to the raw water tank through the circulation valve to start heating the raw water in the raw water tank.

[0020] Preferably, the wastewater in the raw water tank also enters the tertiary heat exchanger through the feed pump and is heated by the heat source provided by the secondary heat exchanger; the wastewater in the tertiary heat exchanger and the wastewater in the primary heat exchanger converge in the pipeline and then enter the secondary heat exchanger for the three-stage heating in step three.

[0021] Preferably, the inlet temperature of the wastewater is 10 - 25 °C, and the water temperature at the outlet end of the quaternary heat exchanger after the first-stage heating is 35 - 40 °C; the temperature range of the thermal catalytic reaction in step four is 50 - 110 °C, and the minimum value of the thermal catalytic reaction temperature is 50 °C.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1) According to the chemical reaction thermodynamics principle of persulfate thermal catalysis, the present invention constructs a modular supporting heat exchange system for efficient utilization of cascaded heat. The energy is used in a cascaded manner through multiple heat exchangers, and the hot water reuse is realized by connecting the hot water tank and the primary heat exchanger through the circulating hot water pump, maximizing the energy utilization and reducing the demand for fresh steam in the treatment process.

[0024] 2) Between the outlet of the multiple heat exchangers and the reactor of the present invention, a circulation valve and an outlet valve controlled by a temperature sensor are provided, which can be adjusted according to the temperature of the wastewater at the outlet of the multiple heat exchangers to ensure that the wastewater enters the reactor after reaching the set temperature, improving the quality of wastewater treatment and being applicable to the heating assistance of the persulfate thermal catalysis reaction of organic wastewater.

[0025] 3) The present invention can treat industrial production lines in various application scenarios such as coal chemical wastewater, printing and dyeing wastewater, and pharmaceutical wastewater containing high concentrations of organic pollutants, realizing the efficient utilization of heat energy, reducing the energy consumption required by the persulfate thermal catalytic advanced oxidation technology, and having great economic and social benefits in the field of energy chemical engineering and environmental protection. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the heating assistance system for the thermal catalytic reaction of the present invention.

[0027] Description of the reference numerals: raw water tank 1, feed pump 2, primary heat exchanger 3, secondary heat exchanger 4, tertiary heat exchanger 5, quaternary heat exchanger 6, reactor 7, hot water tank 8, circulating hot water pump 9, temperature sensor 10. Detailed Embodiments

[0028] The present invention will be further described below in conjunction with embodiments. The description of the following embodiments is only for helping to understand the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0029] Embodiment 1

[0030] As an embodiment, as Figure 1 shown, this heating assistance system for thermal catalytic reaction, the medium to be heated is high-salt organic wastewater, and a corrosive oxidant is added, including: raw water tank 1, primary heat exchanger 3, secondary heat exchanger 4, tertiary heat exchanger 5, quaternary heat exchanger 6, reactor 7 and hot water tank 8; the heat exchange efficiency of the primary heat exchanger 3, secondary heat exchanger 4, tertiary heat exchanger 5 and quaternary heat exchanger 6 is greater than or equal to 98.5%, and the device is equipped with heat preservation measures to ensure that the heat dissipation loss of the system does not exceed the maximum allowable heat loss specified in GB / T 4272 "General Rules for Equipment and Pipeline Heat Preservation Technology", which can effectively guarantee the heating efficiency.

[0031] The water outlet of the raw water tank 1 is connected to the inlet of the feed pump 2, and the outlet of the feed pump 2 is divided into a main path and a branch path. The main path is connected to the quaternary heat exchanger 6, and the branch path is connected to the tertiary heat exchanger 5. The quaternary heat exchanger 6 is connected to the primary heat exchanger 3, and both the primary heat exchanger 3 and the tertiary heat exchanger 5 are connected to the secondary heat exchanger 4.

[0032] A temperature sensor 10 is provided at the outlet end of the secondary heat exchanger 4. The outlet end of the secondary heat exchanger 4 is respectively connected to the raw water tank 1, the reactor 7 and the steam pipeline through a circulation valve, an outlet valve and a steam valve. A return water valve is also provided at the outlet end of the secondary heat exchanger 4; the circulation valve, the outlet valve and the steam valve are all connected to the temperature sensor 10 at the outlet end of the secondary heat exchanger 4. When deciding whether the heated wastewater enters the reactor 7, the opening and closing of the circulation valve and the outlet valve are controlled by the temperature sensor 10. Specifically:

[0033] When the temperature sensor 10 at the outlet end of the secondary heat exchanger 4 detects that the temperature of the wastewater reaches the set reaction temperature, the outlet valve opens to allow the wastewater to enter the reactor 7; otherwise, the circulation valve is opened to allow the wastewater to return to the raw water tank 1 and be reheated in multiple stages until the temperature requirement is met.

[0034] The reaction operating temperature in the reactor 7 is 50 - 110°C, and the reactor 7 is connected to the hot water tank 8. The hot water tank 8 is connected to the primary heat exchanger 3 through a circulating hot water pump 9, which can realize the reuse of the hot water in the hot water tank 8 and improve the utilization rate of thermal energy; the hot water tank 8 is also connected with a temperature sensor 10, and the hot water tank 8 is also connected to the steam pipeline through a steam valve, and the steam valve is connected to the temperature sensor 10 at the hot water tank 8, and the temperature sensor 10 at the hot water tank 8 switches the steam valve as needed; temperature sensors 10 are also respectively provided in the upper, middle and lower parts of the hot water tank 8, and heating coils are also provided in the hot water tank 8; taking the steam transported by the heating coils and the steam pipeline as the heat source, the hot water temperature in the hot water tank 8 is maintained at 50 - 110°C all the time, providing a heat source for the primary heat exchanger 3.

[0035] The wastewater flowing into the four - stage heat exchanger 6 from the main path at the outlet of the feed pump 2 is heated with the primary heat exchanger 3 as the heat source; when the wastewater flows into the primary heat exchanger 3, the reused hot water in the hot water tank 8 is used as the heat source; when the wastewater flows into the secondary heat exchanger 4, the temperature sensor 10 controls the steam valve to open, and the steam is used as the heat source for heating;

[0036] The wastewater flowing into the three - stage heat exchanger 5 from the branch path at the outlet of the feed pump 2 is heated with the secondary heat exchanger 4 as the heat source, then the wastewater in the three - stage heat exchanger 5 and the wastewater in the primary heat exchanger 3 converge, and then flow into the secondary heat exchanger 4, and are heated with the steam as the heat source.

[0037] Flow sensors are provided on both the feed pump 2 and the steam pipeline to monitor the flow rate and energy consumption.

[0038] All the materials in the device that come into contact with the wastewater, including valves, pipelines, etc., are made of corrosion - resistant materials, and the corrosion - resistant grade is higher than that of duplex stainless steel.

[0039] In the above - mentioned steam pipeline, the transported steam temperature is higher than 150°C.

[0040] Embodiment Two

[0041] As another embodiment, for the heating auxiliary system used in the thermal catalytic reaction in Embodiment One, when the system is cold - started, taking the steam as the heat source and the high - COD organic wastewater as the raw water, the steam enters the secondary heat exchanger 4 and then returns to the raw water tank 1 through a circulation valve to heat the raw water in the raw water tank 1, which helps to quickly complete the pre - heating in the cold - start stage, improve the heating speed of the wastewater, and reach the required temperature in a short time.

[0042] When the system is working normally, its heating auxiliary process includes the following steps:

[0043] Step 1. First-stage heating: The wastewater with an inlet water temperature of 10 - 25°C in the raw water tank 1 enters the four-stage heat exchanger 6 through the feed pump 2, and the first-stage heat exchanger 3 provides heat source for the four-stage heat exchanger 6 to heat the wastewater in the first stage; after the first-stage heating, the water temperature at the outlet end of the four-stage heat exchanger 6 is 35 - 40°C;

[0044] Step 2. Second-stage heating: The wastewater after the first-stage heating enters the first-stage heat exchanger 3 from the four-stage heat exchanger 6, and the hot water in the hot water tank 8 is recycled through the circulating hot water pump 9 to provide heat source for the first-stage heat exchanger 3 to heat the wastewater in the second stage;

[0045] Step 3. Third-stage heating: The wastewater in the raw water tank 1 also enters the three-stage heat exchanger 5 through the feed pump 2, and the second-stage heat exchanger 4 provides heat source for heating; the wastewater in the three-stage heat exchanger 5 after heating and the wastewater in the first-stage heat exchanger 3 after the second-stage heating converge in the pipeline and then enter the second-stage heat exchanger 4, and steam provides heat source for the second-stage heat exchanger 4 for the third-stage heating;

[0046] Step 4. Temperature detection: When the temperature sensor 10 shows that the wastewater temperature at the outlet end of the second-stage heat exchanger 4 is lower than 50°C, the circulation valve opens, allowing the wastewater to enter the raw water tank 1, and steps 1 to 4 are repeated until the wastewater temperature at the outlet end of the second-stage heat exchanger 4 reaches 50 - 110°C;

[0047] When the temperature sensor 10 shows that the wastewater temperature at the outlet end of the second-stage heat exchanger 4 reaches 50 - 110°C, the outlet valve opens, allowing the wastewater to enter the reactor 7 to implement step 5;

[0048] Step 5. Thermal catalytic reaction: The wastewater undergoes a thermal catalytic reaction in the reactor 7, and the temperature of the wastewater after the catalytic reaction reaches 35 - 40°C, meeting the water temperature requirements for subsequent water treatment; the reacted wastewater flows into the hot water tank 8 and always remains at 50 - 110°C, and can be recycled through the circulating hot water pump 9 for the second-stage heating.

Claims

1. A heating assistance system for thermal catalytic reactions, characterized in that, Including: Raw water tank (1), primary heat exchanger (3), secondary heat exchanger (4), tertiary heat exchanger (5), quaternary heat exchanger (6), reactor (7) and hot water tank (8); The raw water tank (1) is connected to the quaternary heat exchanger (6) and the tertiary heat exchanger (5) respectively through two water pipes. The quaternary heat exchanger (6) is connected to the primary heat exchanger (3), and both the primary heat exchanger (3) and the tertiary heat exchanger (5) are connected to the secondary heat exchanger (4). A temperature sensor (10) is provided at the outlet end of the secondary heat exchanger (4). The outlet end of the secondary heat exchanger (4) is connected to the raw water tank (1), the reactor (7) and the steam pipeline respectively through a circulation valve, an outlet valve and a steam valve. A return water valve is also provided at the outlet end of the secondary heat exchanger (4). The circulation valve, the outlet valve and the steam valve are all connected to the temperature sensor (10) at the outlet end of the secondary heat exchanger (4); The reactor (7) is connected to the hot water tank (8), and the hot water tank (8) is connected to the primary heat exchanger (3) through a circulating hot water pump (9); A temperature sensor is also connected to the hot water tank (8), and the hot water tank (8) is also connected to the steam pipeline through a steam valve, and the steam valve is connected to the temperature sensor at the hot water tank (8); The temperature of the steam is higher than 150 °C, and the temperature of the hot water in the hot water tank (8) is 50 - 110 °C; The water outlet of the raw water tank (1) is connected to the inlet of the feed pump (2). The outlet of the feed pump (2) is divided into a main path and a branch path. The main path is connected to the quaternary heat exchanger (6), and the branch path is connected to the tertiary heat exchanger (5); Temperature sensors are also respectively provided in the upper, middle and lower parts of the hot water tank (8), and a heating coil is also provided in the hot water tank (8).

2. The heating assistance system for thermal catalytic reactions according to claim 1, characterized in that: Flow sensors are provided on both the feed pump (2) and the steam pipeline.

3. The heating assistance system for thermal catalytic reactions according to claim 1, characterized in that: The heat exchange efficiency of the primary heat exchanger (3), secondary heat exchanger (4), tertiary heat exchanger (5) and quaternary heat exchanger (6) is greater than or equal to 98.5%.

4. The heating process of the heating assistance system for thermal catalytic reactions according to claim 1, characterized in that, Including the following steps: Step 1, First-stage heating: The wastewater in the raw water tank (1) enters the quaternary heat exchanger (6) through the feed pump (2), and the primary heat exchanger (3) provides heat source for the quaternary heat exchanger (6) to conduct first-stage heating on the wastewater; Step 2, Second-stage heating: The wastewater after the first-stage heating enters the primary heat exchanger (3) from the quaternary heat exchanger (6), and the hot water in the hot water tank (8) is recycled through the circulating hot water pump (9) to provide heat source for the primary heat exchanger (3) to conduct second-stage heating on the wastewater; Step 3, Third-stage heating: The wastewater after the second-stage heating enters the secondary heat exchanger (4) from the primary heat exchanger (3), and steam provides heat source for the secondary heat exchanger (4) to conduct third-stage heating; Step 4, Temperature detection: When the temperature sensor (10) shows that the temperature of the wastewater at the outlet end of the secondary heat exchanger (4) is lower than the minimum value of the thermal catalytic reaction temperature, the circulation valve opens to make the wastewater enter the raw water tank (1), and steps 1 to 4 are repeated until the temperature of the wastewater at the outlet end of the secondary heat exchanger (4) reaches the thermal catalytic reaction temperature range; When the temperature sensor (10) shows that the temperature of the wastewater at the outlet end of the secondary heat exchanger (4) is higher than or equal to the thermal catalytic reaction temperature, the outlet valve opens to allow the wastewater to enter the reactor (7) to implement Step Five. Step Five: Thermal catalytic reaction: The wastewater undergoes a thermal catalytic reaction in the reactor (7) and then flows into the hot water tank (8) for reuse in the second-stage heating.

5. The heating process of the heating assistance system for thermal catalytic reactions according to claim 4, characterized in that: When the device is cold-started, steam is used as the heat source and high-COD organic wastewater is used as the raw water. After the steam enters the secondary heat exchanger (4), it returns to the raw water tank (1) through the circulation valve to heat the raw water in the raw water tank (1) for startup.

6. The heating process of the heating assistance system for thermal catalytic reactions according to claim 4, characterized in that: The wastewater in the raw water tank (1) also enters the tertiary heat exchanger (5) through the feed pump (2) and is heated by the heat source provided by the secondary heat exchanger (4). The wastewater in the tertiary heat exchanger (5) after heating converges with the wastewater in the primary heat exchanger (3) in the pipeline and then enters the secondary heat exchanger (4) to perform the three-stage heating in Step Three.

7. The heating process of the heating assistance system for thermal catalytic reactions according to claim 4, characterized in that: The inlet temperature of the wastewater is 10 - 25°C, and the water temperature at the outlet end of the quaternary heat exchanger (6) after the first-stage heating is 35 - 40°C; the range of the thermal catalytic reaction temperature in Step Four is 50 - 110°C, and the minimum value of the thermal catalytic reaction temperature is 50°C.

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