Coking phenol-cyanogen wastewater refrigeration system and refrigeration method

Abstract

The invention discloses a coking phenol-cyanogen wastewater refrigeration system and method, the refrigeration system comprises a wastewater buffer pool, a heat exchanger, a cooling-water machine, a cooling tower and a chilled water buffer pool, and the above structures are connected through pipelines to form a wastewater circulation loop, a chilled water circulation loop and a cooling water circulation loop. The temperature of the coking phenol-cyanogen wastewater is accurately controlled through the synergistic effect of the three circulation loops, the temperature of the wastewater cooled by the heat exchanger can be stably controlled at 25-30 DEG C (the optimum survival interval of microorganisms), the problem of microorganism inactivation caused by the fact that the high-temperature wastewater directly enters a biochemical pool is avoided, and the biochemical treatment efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater refrigeration, and particularly to a coking phenolic cyanide wastewater refrigeration system and a refrigeration method. Background Art

[0002] Coking phenolic cyanide wastewater is a high-concentration organic industrial wastewater generated during the production process of the coking industry. Due to the presence of a large number of complex and difficult-to-degrade organic substances, it has significant strong biological toxicity. If this wastewater is directly discharged without proper treatment, it will cause serious pollution to the ecological environment. Therefore, strict biochemical treatment must be carried out before discharge to reduce its toxicity and harm to the environment.

[0003] During the biochemical treatment process, the temperature control of the biochemical system is crucial. Microorganisms are the core "workers" of biochemical treatment, and they can maintain good activity within a specific temperature range to efficiently decompose organic pollutants in the wastewater. Once the temperature of the biochemical system exceeds the upper limit that microorganisms can bear, the activity of microorganisms will be inhibited, and even a large number of them will die, leading to unstable operation of the entire biochemical system, significant fluctuations, and ultimately possible system collapse, causing the wastewater treatment work to stagnate and failing to achieve the expected treatment effect.

[0004] In summer, the temperature of the biochemical system of coking phenolic cyanide wastewater treatment facilities can reach the critical value of 39°C under natural conditions, which is already close to the temperature limit that microorganisms can bear. In order to better control waste gas emissions and respond to the environmental protection requirements of ultra-low waste gas emissions, both the anoxic tank and aerobic tank in the coking phenolic cyanide wastewater treatment system are covered and sealed. However, according to theoretical calculations and the operating experience of similar coking wastewater treatment facilities, after covering and sealing, the overall temperature of the biochemical system will increase by about 3°C - 5°C. This means that in summer, the maximum temperature of the coking phenolic cyanide wastewater treatment biochemical system may climb to 42°C - 44°C, which far exceeds the upper temperature limit that microorganisms can bear.

[0005] Currently, existing wastewater treatment systems are not equipped with any auxiliary cooling facilities, which makes the biochemical system extremely prone to fluctuations in high-temperature environments, thereby triggering the risk of system collapse, seriously affecting the normal treatment process of coking phenolic cyanide wastewater, restricting the sustainable development of the coking industry, and urgently requiring technological innovation to solve this key problem. Summary of the Invention

[0006] Aiming at the above deficiencies existing in the prior art, the purpose of the present invention is to provide a coking phenolic cyanide wastewater refrigeration system and a refrigeration method to solve the problem that in the existing coking phenolic cyanide wastewater treatment process, no auxiliary cooling facilities are equipped, and the biochemical system is extremely prone to fluctuations in high-temperature environments, thereby triggering the risk of system collapse.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A coking phenolic cyanide wastewater refrigeration system includes a wastewater buffer tank, a heat exchanger, a chiller, a cooling tower, and a chilled water buffer tank, wherein: The water outlet of the wastewater buffer tank is connected to the wastewater inlet of the heat exchanger through a wastewater outlet pipe. A wastewater pump and a wastewater pipe valve are sequentially arranged on the wastewater outlet pipe. The wastewater outlet of the heat exchanger is connected to the water inlet of the wastewater buffer tank through a wastewater return pipe, forming a wastewater circulation loop; The water outlet of the chilled water buffer tank is connected to the chilled water inlet of the chiller through a chilled water inlet pipe. A chilled water circulation pump and a chilled water inlet valve are arranged on the chilled water inlet pipe. The chilled water outlet of the chiller is connected to the chilled water inlet of the heat exchanger through a chilled water outlet pipe. A chilled water outlet valve is arranged on the chilled water outlet pipe. The chilled water outlet of the heat exchanger is connected to the water inlet of the chilled water buffer tank through a chilled water return pipe, forming a chilled water circulation loop; The water outlet of the cooling tower is connected to the cooling water inlet of the chiller through a cooling water inlet pipe. A cooling water circulation pump and a cooling water inlet valve are arranged on the cooling water inlet pipe. The cooling water outlet of the chiller is connected to the water inlet of the cooling tower through a cooling water outlet pipe, forming a cooling water circulation loop.

[0008] Furthermore, both the heat exchanger and the chiller are provided with two groups, forming a parallel operation system; The wastewater inlets of the two groups of heat exchangers are connected to the wastewater outlet pipe through parallel branch pipes. The wastewater outlets of the two groups of heat exchangers are respectively connected to the water inlets of the wastewater buffer tank through two wastewater return pipes; The chilled water inlets of the two groups of chillers are connected to the chilled water inlet pipe through parallel branch pipes. The chilled water outlets are respectively connected to the chilled water inlets of different heat exchangers through two chilled water outlet pipes; The cooling water inlets of the two groups of chillers are connected to the cooling water inlet pipe through parallel branch pipes. The cooling water outlets are respectively connected to the water inlets of the cooling tower through two cooling water outlet pipes; Independent pumps and valves are arranged on the corresponding branch pipes.

[0009] Furthermore, a parallel branch is also arranged on the wastewater outlet pipe. A standby wastewater pump and a standby wastewater pipe valve are sequentially arranged on the parallel branch. The water outlets of all wastewater pumps and the standby wastewater pump are respectively connected to the wastewater inlets of the two groups of heat exchangers through branch pipes, and selection valves are arranged on each branch pipe; A parallel branch is also provided on the chilled water inlet pipe. A standby chilled water circulation pump and a standby chilled water inlet valve are sequentially arranged on the parallel branch. The outlet ends of all the chilled water circulation pumps and the standby chilled water circulation pump are respectively connected to the chilled water inlets of two groups of chillers through branch pipes, and selection valves are provided on each branch pipe. A parallel branch is also provided on the cooling water inlet pipe. A standby cooling water circulation pump and a standby cooling water inlet valve are sequentially arranged on the parallel branch. The outlet ends of all the cooling water circulation pumps and the standby cooling water circulation pump are respectively connected to the cooling water inlets of two groups of chillers through branch pipes, and selection valves are provided on each branch pipe.

[0010] Furthermore, a first temperature sensor and a second temperature sensor are respectively provided on the chilled water outlet pipe and the chilled water return pipe.

[0011] Furthermore, the heat exchanger is a shell-and-tube heat exchanger.

[0012] Furthermore, the chiller is a screw chiller.

[0013] Furthermore, a self-cleaning filter is provided on the cooling water inlet pipe.

[0014] A method for refrigerating coking phenol-cyanide wastewater based on the above system includes the following steps: (1) Temporarily store the wastewater to be treated in the wastewater buffer tank and pump it into the wastewater channel of the heat exchanger through a wastewater pump. (2) Start the chiller synchronously, so that the industrial water cached in the chilled water buffer tank is transported to the chiller through the chilled water circulation pump for refrigeration and then flows into the chilled water channel of the heat exchanger to conduct countercurrent heat exchange with the wastewater. (3) After heat exchange, the temperature of the wastewater decreases and returns to the wastewater buffer tank, and the heated chilled water returns to the chilled water buffer tank and is pumped into the chiller through the chilled water circulation pump for cooling. (4) During the operation of the chiller, continuously supply cooling water to the chiller through the cooling tower to maintain the heat exchange of the condenser of the chiller. The cooling water heated after heat exchange in the chiller flows back to the cooling tower for circulating cooling, thereby realizing the cooling of the wastewater.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention first introduces a closed-loop refrigeration system in the treatment of coking phenol-cyanide wastewater. Through the synergistic effect of a three-stage circulation system (wastewater circulation, chilled water circulation, cooling water circulation), precise control of the temperature of coking phenol-cyanide wastewater is achieved. After being cooled by the heat exchanger, the temperature of the wastewater can be stably controlled at 25-30°C (the optimal survival range of microorganisms), avoiding the problem of microbial inactivation caused by high-temperature wastewater directly entering the biochemical pool and improving the biochemical treatment efficiency. 2. In the coking phenol-cyanide wastewater refrigeration system of the present invention, both the heat exchanger and the chiller are configured with parallel standby units. When abnormal heat exchange temperature difference or equipment failure is detected, it can be switched to the standby unit to ensure the continuous operation of the refrigeration system and avoid the risk of uncontrolled wastewater temperature caused by the shutdown of a single-unit system.

[0016] 3. By setting temperature sensors on the chilled water outlet / return water pipelines in the present invention to monitor the heat exchange temperature difference in real time, and combining with the frequency conversion control module of the chiller to dynamically adjust the output temperature of the chilled water, a closed-loop temperature control system can be formed to ensure the stability and controllability of the wastewater cooling process. In addition, the double-stage buffer design of the wastewater buffer pool and the chilled water buffer pool in the present invention can cope with the flow fluctuations of coking wastewater, and the flow of each loop can be precisely matched through valves, which is especially suitable for the intermittent drainage condition of coking production and avoids the water quality impact problem of the traditional direct cooling method. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic process flow diagram of the coking phenol-cyanide wastewater refrigeration system of the present invention; Figure 2 is a schematic plane installation diagram of the refrigeration system of the present invention.

[0018] In the figure, wastewater buffer pool 1, heat exchanger 2, chilled water buffer pool 3, chiller 4, cooling tower 5, self-cleaning filter 6. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The following further describes in detail the specific embodiments of the present invention with reference to the drawings.

[0020] As Figure 1 shown, a coking phenol-cyanide wastewater refrigeration system includes a wastewater buffer pool 1, a heat exchanger 2, a chilled water buffer pool 3, a chiller 4 and a cooling tower 5, wherein: The water outlet of the wastewater buffer pool 1 is connected to the wastewater inlet of the heat exchanger 2 through a wastewater outlet pipeline. A wastewater pump and a wastewater pipeline valve are sequentially arranged on the wastewater outlet pipeline. The wastewater outlet of the heat exchanger 2 is connected to the water inlet of the wastewater buffer pool 1 through a wastewater return pipeline, forming a wastewater circulation loop; The water outlet of the chilled water buffer pool 3 is connected to the chilled water inlet of the chiller 4 through a chilled water inlet pipeline. A chilled water circulation pump and a chilled water inlet valve are arranged on the chilled water inlet pipeline. The chilled water outlet of the chiller 4 is connected to the chilled water inlet of the heat exchanger 2 through a chilled water outlet pipeline. A chilled water outlet valve is arranged on the chilled water outlet pipeline. The chilled water outlet of the heat exchanger 2 is connected to the water inlet of the chilled water buffer pool 3 through a chilled water return pipeline, forming a chilled water circulation loop; The water outlet of the cooling tower 5 is connected to the cooling water inlet of the chiller 4 through a cooling water inlet pipe. A cooling water circulation pump and a cooling water inlet valve are provided on the cooling water inlet pipe. The cooling water outlet of the chiller 4 is connected to the water inlet of the cooling tower 5 through a cooling water outlet pipe, forming a cooling water circulation loop.

[0021] During specific implementation, two sets of the heat exchanger 2 and the chiller 4 are provided to form a parallel operation system; The wastewater inlets of the two sets of heat exchangers 2 are connected to the wastewater outlet pipe through parallel branch pipes, and the wastewater outlets of the two sets of heat exchangers 2 are respectively connected to the water inlet of the wastewater buffer pool 1 through two wastewater return pipes; The chilled water inlets of the two sets of chillers 4 are connected to the chilled water inlet pipe through parallel branch pipes, and the chilled water outlets are respectively connected to the chilled water inlets of different heat exchangers 2 through two chilled water outlet pipes; The cooling water inlets of the two sets of chillers 4 are connected to the cooling water inlet pipe through parallel branch pipes, and the cooling water outlets are respectively connected to the water inlet of the cooling tower 5 through two cooling water outlet pipes; Independent pumps and valves are provided on the corresponding branch pipes.

[0022] Setting two sets of systems to operate in parallel, one is to increase the efficiency of water treatment, and the other is that during maintenance, it can ensure that there is always one set of refrigeration equipment operating to maintain the cooling capacity of the system, thereby preventing the death of microorganisms in the biochemical system due to excessive temperature and affecting the biochemical efficiency. When only one set of system is operating, the other set can also be used as a standby unit. When the temperature difference is abnormal or the equipment fails, the standby unit can be switched to ensure the normal operation of the refrigeration system. The processing efficiency of a single set of system in the refrigeration system of the present invention is 75m 3 / h.

[0023] During specific implementation, a parallel branch is further provided on the wastewater outlet pipe. A standby wastewater pump and a standby wastewater pipe valve are sequentially provided on the parallel branch. The outlet ends of all wastewater pumps and the standby wastewater pump are respectively connected to the wastewater inlets of the two sets of heat exchangers 2 through branch pipes, and selection valves are provided on each branch pipe; A parallel branch is further provided on the chilled water inlet pipe. A standby chilled water circulation pump and a standby chilled water inlet valve are sequentially provided on the parallel branch. The outlet ends of all chilled water circulation pumps and the standby chilled water circulation pump are respectively connected to the chilled water inlets of the two sets of chillers 4 through branch pipes, and selection valves are provided on each branch pipe; A parallel branch is further provided on the cooling water inlet pipe. A standby cooling water circulation pump and a standby cooling water inlet valve are sequentially provided on the parallel branch. The outlet ends of all cooling water circulation pumps and the standby cooling water circulation pump are respectively connected to the cooling water inlets of the two sets of chillers 4 through branch pipes, and selection valves are provided on each branch pipe; During operation, any two of the three wastewater pumps on the wastewater outlet pipe can simultaneously supply water to two groups of heat exchangers 2 respectively, and the third pump is in standby state.

[0024] Any two of the three chilled water circulation pumps on the chilled water inlet pipe can simultaneously supply water to two groups of chillers 4 respectively, and the third pump is in standby state.

[0025] Any two of the three cooling water circulation pumps on the cooling water inlet pipe can simultaneously supply water to two groups of chillers 4 respectively, and the third pump is in standby state.

[0026] In this way, in the case of one pump failing, another standby pump can be enabled to work, so as to ensure that there are always two systems operating in parallel in the system, thereby ensuring the biochemical efficiency.

[0027] During specific implementation, a first temperature sensor and a second temperature sensor (not shown) are respectively provided on the chilled water outlet pipe and the chilled water return pipe. In this way, the temperature difference of the chilled water can be monitored, so as to assist the staff in judging whether a failure occurs, so as to switch the standby unit in time to ensure the normal operation of the system. By monitoring the temperature difference of the chilled water, it is also convenient for technicians to adjust the chilled water outlet temperature of the chiller 4 according to the temperature difference, so as to make the temperature of the wastewater suitable for the survival of microorganisms.

[0028] During specific implementation, the heat exchanger 2 is a shell-and-tube heat exchanger.

[0029] During specific implementation, the chiller 4 is a screw chiller.

[0030] During specific implementation, a self-cleaning filter 6 is provided on the cooling water inlet pipe. This is because the cooling tower is in direct contact with the atmosphere, and the surrounding area of the cooling tower is the coke oven production area. By filtering and cleaning the water through the self-cleaning filter 6, water pollution can be prevented.

[0031] During specific implementation, the refrigeration system of the present invention fully considers the process layout of the existing coking phenol-cyanide wastewater treatment system. The entire set of cooling facilities occupies a small area and can be built on the open space between the original anoxic tank and the pre-aeration tank. The screw chiller 4, the wastewater pump, and the power distribution cabinet are installed in the original No. 1 pump house, thereby realizing the reasonable utilization of the site. The plane installation schematic diagram of the refrigeration system is as Figure 2 shown.

[0032] When using the refrigeration system of the present invention for refrigeration, the temperature of the wastewater can be reduced by more than 10°C, meeting the design goal (temperature drop requirement of 7°C). And during actual operation, the chilled water outlet temperature can be adjusted in real time according to the incoming water temperature of the front-end phenol-cyanide wastewater, so as to achieve the purpose of energy conservation.

[0033] A coking phenol-cyanide wastewater refrigeration method based on the above system, comprising the following steps: (1) Temporarily store the wastewater to be treated in the wastewater buffer tank 1, and pump it into the wastewater channel of the heat exchanger 2 through a wastewater pump; (2) Synchronously start the chiller 4, so that the industrial water cached in the chilled water buffer tank 3 is transported to the chiller 4 through a chilled water circulation pump for refrigeration and then flows into the chilled water channel of the heat exchanger 2 to perform countercurrent heat exchange with the wastewater; (3) After the temperature of the wastewater is reduced by heat exchange, it returns to the wastewater buffer tank 1, and the heated chilled water returns to the chilled water buffer tank 3 and is pumped into the chiller 4 through a chilled water circulation pump for cooling; (4) During the operation of the chiller 4, continuously supply cooling water to the chiller 4 through the cooling tower 5 to maintain the heat exchange of the condenser of the chiller 4, and the cooling water heated by heat exchange in the chiller 4 flows back into the cooling tower 5 for circulating cooling, thereby realizing the cooling of the wastewater.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the technical solutions. Those of ordinary skill in the art should understand that any modifications or equivalent replacements made to the technical solutions of the present invention without departing from the purpose and scope of the present technical solution shall be covered by the scope of the claims of the present invention.

Claims

1. A coking phenol-cyanide wastewater refrigeration system, characterized in that, It includes a wastewater buffer tank, a heat exchanger, a chiller, a cooling tower and a chilled water buffer tank, where: The water outlet of the wastewater buffer tank is connected to the wastewater inlet of the heat exchanger through a wastewater outlet pipe. A wastewater pump and a wastewater pipe valve are sequentially arranged on the wastewater outlet pipe. The wastewater outlet of the heat exchanger is connected to the water inlet of the wastewater buffer tank through a wastewater return pipe, forming a wastewater circulation loop; The water outlet of the chilled water buffer tank is connected to the chilled water inlet of the chiller through a chilled water inlet pipe. A chilled water circulation pump and a chilled water inlet valve are arranged on the chilled water inlet pipe. The chilled water outlet of the chiller is connected to the chilled water inlet of the heat exchanger through a chilled water outlet pipe. A chilled water outlet valve is arranged on the chilled water outlet pipe. The chilled water outlet of the heat exchanger is connected to the water inlet of the chilled water buffer tank through a chilled water return pipe, forming a chilled water circulation loop; The water outlet of the cooling tower is connected to the cooling water inlet of the chiller through a cooling water inlet pipe. A cooling water circulation pump and a cooling water inlet valve are arranged on the cooling water inlet pipe. The cooling water outlet of the chiller is connected to the water inlet of the cooling tower through a cooling water outlet pipe, forming a cooling water circulation loop.

2. The coking phenol-cyanide wastewater refrigeration system according to claim 1, wherein Both the heat exchanger and the chiller are provided with two groups, forming a parallel operation system; The wastewater inlets of the two groups of heat exchangers are connected to the wastewater outlet pipe through parallel branch pipes, and the wastewater outlets of the two groups of heat exchangers are respectively connected to the water inlets of the wastewater buffer tank through two wastewater return pipes; The chilled water inlets of the two groups of chillers are connected to the chilled water inlet pipe through parallel branch pipes, and the chilled water outlets are respectively connected to the chilled water inlets of different heat exchangers through two chilled water outlet pipes; The cooling water inlets of the two groups of chillers are connected to the cooling water inlet pipe through parallel branch pipes, and the cooling water outlets are respectively connected to the water inlets of the cooling tower through two cooling water outlet pipes; Independent pumps and valves are arranged on the corresponding branch pipes.

3. The coking phenol-cyanide wastewater refrigeration system according to claim 2, wherein, A parallel branch is also arranged on the wastewater outlet pipe. A standby wastewater pump and a standby wastewater pipe valve are sequentially arranged on the parallel branch. The water outlets of all wastewater pumps and the standby wastewater pump are respectively connected to the wastewater inlets of the two groups of heat exchangers through branch pipes, and selection valves are arranged on each branch pipe; A parallel branch is also arranged on the chilled water inlet pipe. A standby chilled water circulation pump and a standby chilled water inlet valve are sequentially arranged on the parallel branch. The water outlets of all chilled water circulation pumps and the standby chilled water circulation pump are respectively connected to the chilled water inlets of the two groups of chillers through branch pipes, and selection valves are arranged on each branch pipe; A parallel branch is also arranged on the cooling water inlet pipe. A standby cooling water circulation pump and a standby cooling water inlet valve are sequentially arranged on the parallel branch. The water outlets of all cooling water circulation pumps and the standby cooling water circulation pump are respectively connected to the cooling water inlets of the two groups of chillers through branch pipes, and selection valves are arranged on each branch pipe.

4. The coking phenol-cyanide wastewater refrigeration system according to claim 1, wherein, A first temperature sensor and a second temperature sensor are respectively arranged on the chilled water outlet pipe and the chilled water return pipe.

5. The coking phenol-cyanide wastewater refrigeration system according to claim 1, wherein The heat exchanger is a shell-and-tube heat exchanger.

6. The coking phenol-cyanide wastewater refrigeration system according to claim 1, wherein The chiller is a screw chiller.

7. The coking phenol-cyanide wastewater refrigeration system according to claim 1, wherein A self-cleaning filter is arranged on the cooling water inlet pipe.

8. A refrigeration method for coking phenol-cyanide wastewater based on the system according to any one of claims 1-7, characterized in that, It includes the following steps: (1)Temporarily store the wastewater to be treated in the wastewater buffer tank and pump it into the wastewater channel of the heat exchanger through a wastewater pump; (2)Simultaneously start the chiller, so that the industrial water cached in the chilled water buffer tank is transported to the chiller by the chilled water circulation pump, flows into the chilled water channel of the heat exchanger after being cooled by the chiller, and exchanges heat with the wastewater in countercurrent; (3)After heat exchange, the temperature of the wastewater drops and returns to the wastewater buffer tank, and the heated chilled water returns to the chilled water buffer tank and is pumped into the chiller by the chilled water circulation pump for cooling; (4)During the operation of the chiller, continuously supply cooling water to the chiller through the cooling tower to maintain the heat exchange of the condenser of the chiller. The cooling water heated after heat exchange by the chiller flows back into the cooling tower for circulating cooling, so as to realize the cooling of the wastewater.

Images