Treatment method for preventing overflow of cold coke water of needle coke containing oil and peculiar smell

Abstract

The invention belongs to the field of petrochemical industry, and provides a treatment method for overflow of oil-containing and odor-resistant cold coke water of needle coke, a contact cooling tower is newly added and is divided into an upper independent part and a lower independent part, the lower part is used for cooling and purging oil gas, and the upper part is used for overflow treatment of the cold coke water, so that function division is realized; purging oil gas from a coke tower firstly enters the lower portion of the contact cooling tower to be cooled, the cooled gas phase enters the air cooler to be cooled, and follow-up treatment is carried out after separation of the separation tank; coke cooling water from a coke tower overflows and then enters the upper portion of the contact cooling tower, a flocculating agent is added to promote oil products in the coke cooling water to be gathered at the tower bottom of the upper portion and then extracted, a water phase obtained after oil removal enters the coke cooling water storage tank to be recycled, and a gas phase is discharged from the tower top and is subjected to follow-up treatment through the air cooler. The method provided by the invention can effectively solve the problems that in the overflow process of the cold coke water of the needle coke, oil products contained in the coke enter the storage tank along with the cold coke water to cause oil accumulation in the tank, and the oil products are mixed into the cold coke water system to cause peculiar smell in the tank area.

Description

A method for preventing overflow of oily and odorous needle-shaped char water from cooling. Technical Field

[0001] This invention belongs to the field of petrochemicals, and specifically relates to a method for treating the overflow of cold coke water containing oil and odor. Background Technology

[0002] In the cold coking process of needle coke, the traditional method uses a cold coke water overflow method: cold coke water is continuously poured into the tower from the bottom, and overflows into the cold coke water storage tank after the liquid level reaches the top of the tower. A significant drawback of this existing technology is that the oil contained in the coke will enter the cold coke water system along with the cold coke water, directly causing oil to accumulate in the cold coke water storage tank, and the tank area is prone to odor, affecting the production environment and system stability.

[0003] In the prior art, patent CN111533353A discloses a wastewater treatment method for delayed coking units, which requires four core modules: pretreatment, cyclone flotation oil removal, two-stage backwashing filtration, and steam stripping. This method has a complex process and is a deep, back-end treatment process for coking wastewater. The process chain is long and the equipment composition is complex. It can also cause overflow cold coke water to stagnate in the pipeline due to the long treatment cycle, which affects the continuity of production.

[0004] Patent CN203890180U discloses a wastewater treatment device for coking wastewater. This device is for the centralized treatment of coking wastewater at the back end. It requires multi-module step-by-step treatment through a contact cooling tower, an oil-water separator, a wastewater settling tank, and a stripping tower. It relies on the static settling and separation of wastewater in the settling tank, resulting in a long treatment cycle. Furthermore, it does not have any treatment modules for gaseous oil and gas, has low processing load flexibility, and cannot adapt to scenarios with fluctuating overflow.

[0005] Patent CN204022599U discloses a contact cooling tower oily wastewater treatment system, including a contact cooling tower, an air cooler, a water cooler, a return tank, and a wastewater external pump. This solution is also for the centralized treatment of coking wastewater at the back end, relying on static sedimentation separation, and has a long treatment cycle. Although the oil and gas mixture discharged from the contact cooling tower is cooled into oily wastewater by the air cooler and water cooler, it does not cover the additional high-temperature gas phase (such as the volatile oil and gas carried by the cold coking water itself) generated when the cold coking water overflows.

[0006] In summary, existing technologies are all aimed at "purification and recycling of static oily wastewater at the back end", rather than "instant oil removal and odor control of dynamic overflow at the front end". Currently, there is no dedicated process design for instant oil separation and odor control during the overflow process. Summary of the Invention

[0007] To address the aforementioned problems in existing technologies, this invention provides a method for treating the overflow of cold coke water containing oil and odor. A new contact cooling tower is added, divided into upper and lower independent sections. The lower section is used for cooling and purging oil and gas, while the upper section is used for treating the overflow of cold coke water, achieving functional zoning. The purging oil and gas from the coke tower first enters the lower part of the contact cooling tower for cooling. The cooled gas phase then enters an air cooler for further cooling and is separated in a separator before undergoing subsequent processing. The overflowing cold coke water from the coke tower first enters the upper part of the contact cooling tower, where a flocculant is added to cause the oil in the cold coke water to accumulate at the bottom of the upper tower before being extracted. The water phase after oil removal enters a cold coke water storage tank for recycling, while the gas phase is discharged from the top of the tower and undergoes further processing via the aforementioned air cooler.

[0008] In this invention, the contact cooling tower is arranged vertically, which can reduce the equipment footprint. At the same time, the cold coke water in the upper part of the cooling tower is easy to overflow after treatment. The purging oil and gas in the lower part of the cooling tower is cooled and then treated by the same air cooler as the oil and gas in the upper part of the cooling tower. This shortens the pipeline and also realizes equipment sharing.

[0009] The treatment method provided by this invention is a "front-end source control treatment" for the overflow of cold coke water. By setting up a combination of contact cooling tower, flocculation oil removal, and gas phase cooling separation, it can achieve real-time oil control and odor blocking during the overflow process. The water phase after oil removal is then recycled into the cold coke water storage tank. This effectively cuts off the problem of oil entering the storage tank with the overflow and direct discharge of oil and gas from the source. It can effectively solve the problems of oil contained in the coke entering the storage tank with the cold coke water during the overflow of needle coke cold coke water, resulting in oil accumulation in the tank and odor caused by oil mixing into the cold coke water system.

[0010] The specific technical solution of the present invention is as follows: (1) A contact cooling tower is set up. The purge oil and gas from the coke tower enter the lower part of the contact cooling tower and is sprayed with cooling medium. The bottom circulation pump is started to establish external circulation and cool the purge oil and gas. The cooling medium and the oil and gas are in reverse contact to dissolve the oil in the oil and gas and initially cool the oil and gas temperature. The oil and gas then enter the air cooler for cooling. The cooled gas-liquid mixture enters the separation tank. The separated light oil is sent to the light sludge tank in the tank area using a light sludge pump. The acidic water phase condensed at the bottom is sent to the acidic water stripping device for further processing using an acidic water pump. The cooling medium after heat exchange is cooled by a cooling water tank. The cooling medium mixed with oil is periodically discharged to the sludge tank in the tank area through the sewage pipeline and new cooling medium is added. 2) After overflowing from the top of the coke tower, the cold coke water enters the upper part of the contact cooling tower through a pipeline. The cold coke water inlet is located on the upper side of the cooling tower. At the same time, the flocculant injection device is activated, and flocculant is injected at the inlet of the cold coke water pipeline. During this period, it is continuously added according to the overflow demand. The flocculant and cold coke water enter the upper part of the contact cooling tower together without stirring. The residual oil in the cold coke water is cooled and accumulates at the bottom of the upper part of the contact cooling tower under the action of flocculant. There is an oil outlet at the bottom of the tower. The oil is pumped out to the sludge tank using a sludge pump. The water phase after oil removal overflows from the outlet on the side of the top of the tower to the cold coke water storage tank for subsequent recycling. The oil and gas generated in the upper part of the contact cooling tower enter the air cooler for cooling from the top of the tower through the gas exhaust pipe. The cooled gas-liquid mixture enters the separator for separation and then undergoes further processing.

[0011] Furthermore, the contact cooling tower is divided into two independent parts, the lower part for cooling the purging oil and gas, and the upper part for treating the overflow of cold coke water, thus realizing functional zoning. According to the operation sequence of the needle coke process, the coke tower first uses steam to cool the coke. The purging oil and gas from the coke tower first enters the lower part of the contact cooling tower for treatment, and then the coke is cooled using cold coke water. The cold coke water overflows from the coke tower and enters the upper part of the contact cooling tower for treatment. The purging oil and gas in the lower part and the cold coke water in the upper part are treated separately and do not interfere with each other.

[0012] Furthermore, the flocculant addition amount is 0.005-0.025 g / L, that is, 0.005-0.025 g of flocculant is added per liter of cold coke water. The specific adaptation is as follows: the flocculant addition amount is divided into two working conditions according to the oil concentration of the cold coke water: low oil content condition: the oil concentration of the cold coke water is 100-250 mg / L, and the flocculant addition amount is 0.005-0.01 g / L; high oil content condition: the oil concentration of the cold coke water is 250-500 mg / L, and the flocculant addition amount is 0.01-0.025 g / L.

[0013] Furthermore, the flocculant was purchased from Shandong Chenyu Petroleum Technology Co., Ltd., specifically CY-207 flocculant.

[0014] Furthermore, the air cooler is a finned tube type with a cooling range of -40 to 106°C. It uses a variable frequency motor, and the inlet valve is a pneumatic switch. A medium-pressure steam interface is provided after the valve for easy purging. The inclination angle of the finned tube from the inlet to the outlet is 10-30°.

[0015] Furthermore, the cooling medium used in the lower part of the contact cooling tower is selected from light wax oil or heavy diesel oil.

[0016] Compared with the prior art, the present invention has achieved the following beneficial effects: (1) Functional zoning design: The upper and lower parts of the contact cooling tower are used separately. The lower part is used to cool the oil and gas of the coke tower and the upper part is used to remove oil from the overflow of cold coke water. This realizes that one set of equipment can carry two core processes, simultaneously blocking oil accumulation and odor, avoiding the environmental burden at the back end, and also avoiding the duplication of equipment construction. Moreover, the upper and lower zoning are completely independent, avoiding the mutual interference between the overflow treatment and the large-scale cooling process, improving their respective processing efficiency, and solving the problem of the traditional process not having a dedicated separation device; The present invention uses "contact cooling tower + "Flocculation oil removal" achieves instant separation, perfectly matching the continuous flow characteristics of cold coke water, and does not require waiting for the complex process of "deep purification", does not affect the continuity of cold coke operation, the process is simpler, and is more suitable for the "short path, fast processing" requirements of overflow scenarios; (2) Flocculation oil removal technology: by injecting flocculants to actively gather oil, compared with the traditional process that relies on natural sedimentation, the oil removal rate reaches more than 90%, reducing the amount of oil entering the cold coke water storage tank from the source, and solving the problem of oil accumulation in the tank; (3) Deep gas treatment: the oil and gas generated in the contact cooling tower and the purge oil and gas from the coke tower are cooled and separated to achieve light oil recovery. The condensate is sent out to avoid the odor caused by direct discharge of oil and gas, and at the same time, resource recycling is realized, which solves the odor and environmental protection problems of the tank area; (4) Equipment compatibility: The contact cooling tower, air cooler, separation tank, and conveying pipeline used in this invention are all conventional equipment in the chemical field. There is no need to customize special equipment. Existing equipment can be directly selected or adapted; In this invention, the contact cooling tower is set up vertically, which can reduce the equipment footprint. At the same time, the cold coke water in the upper part of the cooling tower is easy to overflow after treatment. The purging oil and gas in the lower part of the cooling tower is cooled and treated with the oil and gas in the upper part of the cooling tower using the same air cooler, which shortens the pipeline and realizes equipment sharing. Attached Figure Description

[0017] Figure 1 is a simplified process flow diagram of the present invention.

[0018] In the diagram, 1 is the contact cooling tower, 1-1 is the upper part of the contact cooling tower, 1-2 is the lower part of the contact cooling tower, 2 is the air cooler, 3 is the separator, 4 is the light sludge pump, 5 is the acid water pump, 6 is the sludge pump, 7 is the bottom circulation pump, and 8 is the cooling water tank. Detailed Implementation

[0019] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they should be performed in accordance with the techniques or conditions described in the literature in the field, or in accordance with the product manual.

[0020] The flocculant used in the following examples was purchased from Shandong Chenyu Petroleum Technology Co., Ltd., CY-207 flocculant.

[0021] Example 1: A method for preventing the overflow of cold coke water from needle-shaped coke containing oil and odor. The specific operating steps are as follows: Operating parameters: coke tower steam pressure 0.5MPa, purging time 2.5h; cold coke water overflow rate 50m³ / h. 3 / h, initial oil concentration 130mg / L, temperature 70℃; (1) Set up contact cooling tower 1, purge oil gas (temperature 180℃) from coke tower enters the lower part 1-2 of contact cooling tower, and sprays 45℃ cooling medium light wax oil, start tower bottom circulation pump 7, establish tower external circulation, cool purge oil gas process, and do not interfere with the upper process; light wax oil and oil gas make counter-contact, dissolve oil in oil gas, and initially cool oil gas temperature, after cooling temperature 90℃, oil gas enters air cooler 2 for cooling, air cooler 2 cooling temperature is controlled at 50℃, oil gas is cooled to 55℃ by air cooler 2, and the cooled gas-liquid mixture enters separation tank 3, the separated light oil is sent to tank area light sludge tank by light sludge oil pump 4, and the acidic water phase condensed at the bottom is sent to acidic water tank by acidic water pump 5. The stripping unit performs subsequent processing; the light wax oil after heat exchange is cooled to 45°C through the cooling water tank 8, and the light wax oil mixed with oil is periodically discharged to the sludge tank in the tank area through the sewage pipeline and replenished with new light wax oil; (2) the cold coke water overflows from the top of the coke tower and enters the upper part 1-1 of the contact cooling tower through the pipeline. The cold coke water inlet is located on the upper side of the cooling tower. At the same time, the flocculant injection device is started and injected at the inlet of the cold coke water pipeline. The flocculant addition amount is 0.005g / L. During this period, it is continuously added according to the overflow demand. The flocculant and the cold coke water enter the upper part 1-1 of the contact cooling tower together without stirring; the residual oil in the cold coke water is cooled and accumulated at the bottom of the upper part 1-1 of the contact cooling tower under the action of the flocculant. The bottom of the tower is equipped with an oil outlet. The sludge pump 6 is used to pump the oil to the sludge tank. The pumping flow rate is 0.3-0.5m. 3 / h, the water phase after oil removal overflows from the outlet on the side of the top of the tower into the cold coke water storage tank for subsequent recycling; the oil and gas generated in the upper part 1-1 of the contact cooling tower enters the air cooler 2 through the gas discharge pipe from the top of the tower for cooling. The cooling temperature of the air cooler 2 is controlled at 50℃, the inlet temperature is 70℃, and the temperature after cooling is 52℃. The cooled gas-liquid mixture enters the separator 3 for separation and then undergoes further processing.

[0022] Table 1. Detection data of indicators before and after cold coke water treatment under the operating conditions of Example 1.

[0023] Effect analysis: The residual oil removal rate reached 91.5%, effectively avoiding oil accumulation in the cold coke storage tank; compared with the traditional single polyaluminum ferric chloride (PAFC) flocculation treatment scheme, the flocculant dosage in Example 1 was reduced by 30%, the operating cost was reduced, and it is suitable for low-load production scenarios.

[0024] The odor concentration (non-methane total hydrocarbons) in the tank area decreased from 106 mg / m³ before treatment. 3 Reduced to 12 mg / m 3 It meets the requirements of the "Emission Standard of Pollutants for Petroleum Refining Industry" (GB 31570-2015); the light oil recovery rate is over 85%, realizing resource recovery.

[0025] Example 2: A method for preventing the overflow of cold coke water from needle-shaped coke containing oil and odor. The specific operating steps are as follows: Operating parameters: coke tower steam pressure 0.6 MPa, purging time 3 h; cold coke water overflow rate 80 m³ / h. 3 / h, initial oil concentration 215mg / L, temperature 75℃; (1) Set up contact cooling tower 1, the purge oil gas (temperature 195℃) from the coke tower enters the lower part 1-2 of the contact cooling tower, and sprays it with 45℃ cooling medium light wax oil. Start the tower bottom circulation pump 7 to establish the tower external circulation and cool the purge oil gas. The process is not interfered with by the upper process. Light wax oil is selected as the cooling medium to make counter-contact with the oil gas, dissolve the oil in the oil gas, and initially cool the oil gas temperature. After cooling, the temperature is 102℃. The oil gas then enters the air cooler 2 for cooling. The cooling temperature of the air cooler 2 is controlled at 50℃. The oil gas is cooled to 57℃ by the air cooler 2. The cooled gas-liquid mixture enters the separator 3. The separated light oil is sent to the tank area light sludge tank by the light sludge oil pump 4. The acidic water phase condensed at the bottom is sent to the tank area by the acid water pump 5. The light wax oil is sent to the acidic water stripping unit for further processing; the light wax oil after heat exchange is cooled to 45°C through the cooling water tank 8, and the light wax oil mixed with oil is periodically discharged to the sludge tank in the tank area through the sewage pipeline and replenished with new light wax oil; (2) the cold coke water overflows from the top of the coke tower and enters the upper part 1-1 of the contact cooling tower through the pipeline. The cold coke water inlet is located on the upper side of the cooling tower. At the same time, the flocculant injection device is started and injected at the inlet of the cold coke water pipeline. The flocculant addition amount is 0.008g / L. During this period, it is continuously added according to the overflow demand. The flocculant and the cold coke water enter the upper part 1-1 of the contact cooling tower together without stirring; the residual oil in the cold coke water is cooled and accumulated at the bottom of the upper part 1-1 of the contact cooling tower under the action of the flocculant. The bottom of the tower is equipped with an oil outlet. The sludge pump 6 is used to pump the oil to the sludge tank. The pumping flow rate is 0.5-1.0m. 3 / h, the water phase after oil removal overflows from the outlet on the side of the top of the tower into the cold coke water storage tank for subsequent recycling; the oil and gas generated in the upper part 1-1 of the contact cooling tower enters the air cooler 2 through the gas discharge pipe from the top of the tower for cooling. The cooling temperature of the air cooler 2 is controlled at 45℃, the inlet temperature is 75℃, and the temperature after cooling is 53℃. The cooled gas-liquid mixture enters the separator 3 for separation and then undergoes further processing.

[0026] Table 2. Detection data of indicators before and after cold coke water treatment under the operating conditions of Example 2.

[0027] Effect analysis: The residual oil removal rate reached 91.6%, effectively preventing oil accumulation in the cold coke storage tank; the odor concentration (non-methane total hydrocarbons) in the tank area decreased from 120 mg / m³ before treatment. 3 Reduced to 15 mg / m 3 It meets the requirements of the "Emission Standard of Pollutants for Petroleum Refining Industry" (GB31570-2015); the light oil recovery rate reaches more than 85%, realizing resource recovery.

[0028] For those skilled in the art, the specific embodiments are merely illustrative descriptions of the present invention. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A method for preventing the overflow of oily and odorous needle-shaped char water from cold coke, characterized in that, The specific methods are as follows: (1) Set up a contact cooling tower (1), the purge oil and gas from the coke tower enter the lower part (1-2) of the contact cooling tower, and spray the cooling medium. Start the bottom circulation pump (7) to establish external circulation and cool the purge oil and gas. The cooling medium and the oil and gas come into counter-current contact to dissolve the oil in the oil and gas and initially cool the oil and gas temperature. The oil and gas then enter the air cooler (2) for cooling. The cooled gas-liquid mixture enters the separator (3). The separated light oil is sent to the light sludge tank in the tank area using the light sludge pump (4). The acidic water phase condensed at the bottom is sent to the acidic water stripping unit for subsequent processing using the acidic water pump (5). The cooling medium after heat exchange is cooled by the cooling water tank (8). The cooling medium mixed with oil is periodically discharged to the sludge tank in the tank area through the sewage pipeline and new cooling medium is added. (2) Cool the coke. Water overflows from the top of the coke tower and enters the upper part (1-1) of the contact cooling tower through a pipe. The cold coke water inlet is located on the side of the upper part of the cooling tower. At the same time, the flocculant injection device is started and injected at the inlet of the cold coke water pipe. During this period, it is continuously added according to the overflow demand. The flocculant and the cold coke water enter the upper part (1-1) of the contact cooling tower together without stirring. The residual oil in the cold coke water is cooled and accumulated at the bottom of the upper part (1-1) of the contact cooling tower under the action of the flocculant. The bottom of the tower is equipped with an oil outlet. The oil is pumped out to the oil tank using the sludge pump (6). The water phase after oil removal overflows from the outlet on the side of the top of the tower to the cold coke water storage tank for subsequent recycling. The oil and gas generated in the upper part (1-1) of the contact cooling tower enter the air cooler (2) from the top of the tower through the gas discharge pipe for cooling. The cooled gas-liquid mixture enters the separator (3) for separation and then undergoes subsequent processing.

2. The method for treating overflow of needle-shaped char water containing oil and odor according to claim 1, characterized in that, The contact cooling tower (1) is divided into two independent parts, the lower part for cooling the purging oil and gas, and the upper part for treating the overflow of cold coke water. According to the operation sequence of the needle coke process, the coke tower first uses steam to cool the coke. The purging oil and gas from the coke tower first enters the lower part (1-2) of the contact cooling tower for treatment, and then uses cold coke water to cool the coke. The cold coke water overflows from the coke tower and enters the upper part (1-1) of the contact cooling tower for treatment.

3. The method for treating overflow of needle-shaped char water containing oil and odor according to claim 1, characterized in that, The flocculant addition amount is 0.005-0.025 g / L, that is, 0.005-0.025 grams of flocculant are added per liter of cold coke water.

4. The method for treating overflow of needle-shaped char water containing oil and odor according to claim 3, characterized in that, The flocculant addition amount is divided into two conditions based on the oil concentration of the cold coke water: low oil content condition: the oil concentration of the cold coke water is 100-250 mg / L, and the flocculant addition amount is 0.005-0.01 g / L; high oil content condition: the oil concentration of the cold coke water is 250-500 mg / L, and the flocculant addition amount is 0.01-0.025 g / L.

5. The method for treating overflow of needle-shaped char water containing oil and odor according to claim 1, characterized in that, The air cooler (2) is a finned tube type with a cooling range of -40 to 106°C. It uses a variable frequency motor, and the inlet valve is a pneumatic switch. A medium-pressure steam interface is provided after the valve for easy purging. The inclination angle of the finned tube from the inlet to the outlet is 10-30°.

6. The method for treating overflow of needle-shaped char water containing oil and odor according to claim 1, characterized in that, The cooling medium used in the lower part (1-2) of the contact cooling tower is selected from light wax oil or heavy diesel oil.

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