A system and process for treating oily sludge in an oil refinery

Abstract

The present invention relates to the field of treatment of pollutants in oil refineries, and in particular to a system and process for treating oily sludge in oil refineries, comprising a feed reaction tank, the feed reaction tank being connected to a primary sedimentation separation tank, the primary sedimentation separation tank being connected to a solid-liquid separation dehydrator, the output end of the solid-liquid separation dehydrator being connected to a secondary four-phase separation tank, the slag phase separation output end of the secondary four-phase separation tank being connected to a primary sedimentation separation tank, the secondary four-phase separation tank being respectively connected to a waste oil aging separation tank, a third-level four-phase separation tank and a second-level solid-liquid separator, the suspended separation output end and the slag phase separation output end of the third-level four-phase separation tank being respectively connected to a primary sedimentation separation tank, the oil phase separation liquid output end of the third-level four-phase separation tank being connected to a waste oil aging separation tank, and the separation liquid output end of the second-level solid-liquid separator being connected to a third-level four-phase separation tank. The system and process can ensure that the treated sludge and sewage meet environmental protection indicators, and fuel oil can be recovered.

Description

Technical Field

[0001] The present invention relates to the field of pollutant treatment in oil refineries, and in particular to a system and process for treating oily sludge in oil refineries. Background Art

[0002] Oily sludge (three muds) of petroleum refining enterprises mainly comes from oil separators, flotation tanks, biochemical treatment tanks, crude oil dehydration tanks, oil storage tanks and waste oil tanks. These oily sludges generally contain hydrocarbon compounds, benzene series, phenolic compounds, anthracene compounds, etc. They are accompanied by a foul odor, are fully emulsified, have a high viscosity, belong to a relatively stable multiphase system, and the solid phase is difficult to completely settle, making it very difficult to treat. At present, direct landfill is generally used to treat oily sludge, but the harmful substances and crude oil that is difficult to decompose contained in it will penetrate and diffuse, causing serious pollution to the surrounding soil, water, and air.

[0003] Most of the domestic petroleum refining enterprises were built earlier, with backward processing technology and outdated equipment, and a large amount of old mud has accumulated. After more than ten years or even decades of interaction, the various chemical components of oily sludge have become more stable, and the emulsification of oil substances has become more serious. The demulsification and flocculation effect of cationic polyacrylamide, a flocculant, is not sufficient.

[0004] In the actual operation of three-phase or two-phase drum centrifuges, when the solid content in the sludge reaches a certain level or the demulsification and flocculation effect is not good, the dehydration effect of the centrifuge is not good, which is mainly manifested in the high liquid content of the centrifugal sludge, and the centrifugal liquid contains a large amount of organic matter and is black. If this black liquid is directly pumped into the water system for treatment, a large amount of normal sewage will be polluted into black. At present, most refineries pump this black liquid into the oil separator and flotation tank, but the oil separator and flotation cannot effectively treat this black water, causing water quality impact on the biochemical unit, a vicious cycle. Summary of the invention

[0005] The object of the present invention is to provide a system and process for treating oily sludge in an oil refinery, which can ensure that the treated sludge and sewage meet environmental protection indicators and can recycle fuel oil.

[0006] The technical solution of the present invention is: a refinery oily sludge treatment system, comprising a feed reaction tank, the output end of the feed reaction tank is connected to a primary sedimentation separation tank, the output end of the primary sedimentation separation tank is connected to a solid-liquid separation dehydrator, the water phase separation liquid output end of the solid-liquid separation dehydrator is connected to a secondary four-phase separation tank, the slag phase separation output end of the secondary four-phase separation tank is connected to the primary sedimentation separation tank, the oil phase separation liquid output end of the secondary four-phase separation tank is connected to a dirty oil aging separation tank, the water phase separation liquid output end of the secondary four-phase separation tank is connected to a third-level four-phase separation tank, the suspended separation output end of the secondary four-phase separation tank is connected to a secondary solid-liquid separator, the suspended separation output end and the slag phase separation output end of the third-level four-phase separation tank are respectively connected to the primary sedimentation separation tank, the oil phase separation liquid output end of the third-level four-phase separation tank is connected to the dirty oil aging separation tank, and the separation liquid output end of the secondary solid-liquid separator is connected to the third-level four-phase separation tank.

[0007] Furthermore, the feed reaction tank includes a first round tank, an agitator is arranged in the first round tank, a first feed pipe is arranged on the upper side wall of the first round tank, and a first discharge pipe is arranged on the bottom of the first round tank; the first-level sedimentation separation tank includes a conical bottom round tank, an agitator is arranged in the conical bottom round tank, a second feed pipe is arranged on the upper side wall of the conical bottom round tank, and a second discharge pipe is arranged on the bottom of the conical bottom round tank; the feed reaction tank and the first-level sedimentation separation tank are also respectively provided with heating equipment.

[0008] Furthermore, the secondary four-phase separation tank and the tertiary four-phase separation tank respectively include an outer shell, a scum collecting cylinder whose bottom end is connected to the outer shell is arranged inside the outer shell, the scum collecting cylinder is connected to the feed port via a distributor arranged inside the cylinder, the upper end of the scum collecting cylinder is connected to the scum collector, the upper part of the scum collector is connected to the scum discharge port, the lower part is connected to the oil discharge port, the bottom of the outer shell is connected to the scum discharge port, and the top end is connected to the water outlet.

[0009] Furthermore, the distributor includes a third feed pipe vertically arranged in the scum collecting barrel and connected to the feed port, the upper outer periphery of the third feed pipe is provided with a first cone top forming a first flow gap with the inner wall of the scum collecting barrel, and a second cone top is provided above the third feed pipe, and a second flow gap is formed between the second cone top and the first cone top.

[0010] Furthermore, a slag discharge pipeline connected to the slag discharge port is provided at the bottom of the shell, the slag collector is provided at the upper periphery of the slag collecting cylinder and forms a slag discharge chamber between the slag collecting cylinder, the slag discharge port is provided at the upper part of the slag collector and passes through the shell, the oil discharge port is provided at the lower part of the slag collector and passes through the shell, and a drainage pipeline is also provided at the upper end of the slag collector, and the drainage pipeline is connected to the drainage port through an overflow trough provided on the top of the shell.

[0011] Furthermore, the waste oil aging separation tank includes a second round tank, a fourth feed pipe is provided on the upper side wall of the second round tank, an external separation oil output end is provided at the bottom of the second round tank, and a heating coil is provided on the second round tank; heating equipment is respectively provided in the secondary four-phase separation tank and the tertiary four-phase separation tank.

[0012] Furthermore, the solid-liquid separation dehydrator and the secondary solid-liquid separator are respectively provided with an external discharge dehydrated dry mud output terminal; the solid-liquid separation dehydrator and the secondary solid-liquid separator are centrifuges, plate and frame filter presses, belt filter presses, screw stacking machines or screw stringing machines.

[0013] A refinery oily sludge treatment process, including a refinery oily sludge treatment system, comprises the following steps:

[0014] (1) Dilute the refining sludge or refining slag to a water content of more than 95% for treatment, and pump the material to be treated into the feed reaction tank, add the composite flocculant into the feed reaction tank, and stir quickly to fully mix the agent and the material;

[0015] (2) The mixed materials are sent to a primary sedimentation separation tank for further reaction, and the slag-water mixture discharged from the primary sedimentation separation tank is sent to a solid-liquid separation dehydrator; the dry mud discharged from the solid-liquid separation dehydrator is subjected to thermal desorption treatment, and the discharged liquid enters a secondary four-phase separation tank for static separation;

[0016] (3) The slag phase separation product from the secondary four-phase separation tank is returned to the primary sedimentation separation tank for treatment, the oil phase separation liquid produced by the secondary four-phase separation tank is discharged to the waste oil aging separation tank for storage, the suspended separation product is sent to the secondary solid-liquid separator for dehydration, and the water phase separation liquid is sent to the tertiary four-phase separation tank for static separation;

[0017] (4) The dry mud discharged from the secondary solid-liquid separator is subjected to thermal desorption treatment, and the discharged liquid is sent to the third-stage four-phase separation tank for static separation;

[0018] (5) The suspended separation and slag phase separation of the three-stage four-phase separation tank are returned to the first-stage sedimentation separation tank for treatment, and the oil phase separation liquid of the three-stage four-phase separation tank is discharged to the waste oil aging separation tank for storage. The water phase separation liquid of the three-stage four-phase separation tank meets the external discharge index and is discharged.

[0019] Furthermore, the temperature of the feed reaction tank, the primary sedimentation separation tank, the secondary four-phase separation tank, the tertiary four-phase separation tank, and the waste oil aging separation tank is maintained at 60±5°C.

[0020] Furthermore, the composite flocculant is an RJ2 type high-efficiency composite flocculant.

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

[0022] The system uses the traditional oily sludge treatment process of "conditioning-centrifugation", which solves the problem of a vicious cycle in which the centrifuge sludge has a high liquid content, the centrifuged water contains a large amount of organic matter and is black, causing an impact on the production unit.

[0023] The system adds a new composite carrier flocculant during the reaction stage and performs solid-liquid separation through two-stage equipment. The oil content of the extracted dry sludge can be less than 5%, and the water content is no higher than 65%, which meets the feeding process parameters for subsequent thermal desorption treatment of the dry sludge. It can ensure that the treated sludge and sewage meet environmental protection indicators, and can recycle fuel oil, saving the cost of hazardous waste treatment for the enterprise and solving the shortcomings of the original treatment process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow chart of the present invention;

[0025] Figure 2 It is a structural schematic diagram of the feed reaction tank of the present invention;

[0026] Figure 3 It is a structural schematic diagram of the primary sedimentation separation tank of the present invention;

[0027] Figure 4 It is a schematic structural diagram of a two-stage four-phase separation tank or a three-stage four-phase separation tank of the present invention;

[0028] Figure 5 It is a structural schematic diagram of the waste oil aging separation tank of the present invention;

[0029] In the figure: 10-feeding reaction tank 11-agitator 12-first feed pipe 13-first discharge pipe 20-primary sedimentation separation tank 21-agitator 22-second feed pipe 23-second discharge pipe 30-dirty oil aging separation tank 31-fourth feed pipe 32-external separation oil output end 33-heating coil 40-secondary four-phase separation tank 41-shell 411-slag discharge pipeline 42-slag collection cylinder 43-distributor 431-third feed pipe 432-first circulation gap 433-first cone top 434-second cone top 435-second circulation gap 44-slag collector 441-static flow plate 442-drainage pipeline 443-overflow trough 45-slag discharge port 46-oil discharge port 47-slag discharge port 48-drainage port 49-feed port 50-third-stage four-phase separation tank. DETAILED DESCRIPTION

[0030] In order to make the above features and advantages of the present invention more easily understood, embodiments are given below with reference to the accompanying drawings for detailed description, but the present invention is not limited thereto.

[0031] refer to Figures 1 to 5

[0032] A system for treating oily sludge in an oil refinery comprises a feed reaction tank 10, wherein the output end of the feed reaction tank is connected to a primary sedimentation separation tank 20, wherein the output end of the primary sedimentation separation tank is connected to a solid-liquid separation dehydrator, wherein the water phase separation liquid output end of the solid-liquid separation dehydrator is connected to a secondary four-phase separation tank 40, wherein the slag phase separation material output end of the secondary four-phase separation tank is connected to the primary sedimentation separation tank, wherein the oil phase separation liquid output end of the secondary four-phase separation tank is connected to a waste oil aging separation tank 30, wherein the secondary four-phase separation tank The water phase separation liquid output end is connected to the three-stage four-phase separation tank 50, the suspended separation material output end of the two-stage four-phase separation tank is connected to the two-stage solid-liquid separator, the suspended separation material output end and the slag phase separation material output end of the three-stage four-phase separation tank are respectively connected to the one-stage sedimentation separation tank, and the oil phase separation liquid output end of the three-stage four-phase separation tank is connected to the waste oil aging separation tank; the separation liquid output end of the two-stage solid-liquid separator is connected to the three-stage four-phase separation tank so that the squeezed liquid can be sent to the three-stage four-phase separation tank for further separation.

[0033] In this embodiment, the feed reaction tank includes a first round tank, in which an agitator 11 is provided, a first feed pipe 12 is provided on the upper side wall of the first round tank, and a first discharge pipe 13 is provided at the bottom of the first round tank; the first-level sedimentation separation tank includes a conical bottom round tank, in which an agitator 21 is provided, a second feed pipe 22 is provided on the upper side wall of the conical bottom round tank, and a second discharge pipe 23 is provided at the bottom of the conical bottom round tank; heating equipment is also provided in the feed reaction tank and the first-level sedimentation separation tank, respectively, so as to control the temperature of the feed reaction tank and the first-level sedimentation separation tank during use, so that the material maintains the set temperature.

[0034] In this embodiment, the secondary four-phase separation tank and the tertiary four-phase separation tank respectively include an outer shell 41, and a scum collecting cylinder 42 whose bottom end is connected to the outer shell is arranged inside the outer shell. The scum collecting cylinder is connected to the feed port 49 through a distributor 43 arranged inside the scum collecting cylinder, and the upper end of the scum collecting cylinder is connected to a scum collector 44. The upper part of the scum collector is connected to a scum discharge port 45 to discharge the suspended separation; the lower part of the scum collector is connected to an oil discharge port 46 to discharge the oil phase separation liquid; the bottom of the outer shell is connected to a slag discharge port 47 to discharge the slag phase separation, and the top of the outer shell is connected to a water outlet 48 to discharge the water phase separation liquid.

[0035] In this embodiment, the distributor includes a third feed pipe 431 vertically arranged in the scum collecting barrel and connected to the feed port, and the upper outer periphery of the third feed pipe is provided with a first cone top 433 forming a first flow gap 432 with the inner wall of the scum collecting barrel, and a second cone top 434 is arranged above the third feed pipe, and a second flow gap 435 is formed between the second cone top and the first cone top to feed the material into the scum collecting barrel.

[0036] In this embodiment, in order to discharge the sediment, a slag discharge pipeline 411 connected to the slag discharge port is provided at the bottom of the shell. The feed end of the slag discharge pipeline is fixedly connected to the bottom plate of the shell and is provided with multiple discharge inlets.

[0037] In this embodiment, the scum collector is arranged at the upper periphery of the scum collecting cylinder and forms a scum discharge chamber with the scum collecting cylinder. A static flow plate 441 is arranged between the outer wall of the scum collector and the inner wall of the shell from top to bottom. The static flow plate is arranged with a left-right offset and the free end is facing downward, so that the scum is gradually settled. The scum discharge port is arranged at the upper part of the scum collector and passes through the shell. The oil discharge port is arranged at the lower part of the scum collector and passes through the shell. The upper end of the scum collector is also provided with a drainage pipeline 442. The drainage pipeline is connected to the drainage port through an overflow groove 443 arranged at the top of the shell, so that the scum, oil and water are separated by the cooperation of the scum collector and the shell.

[0038] In this embodiment, the waste oil aging separation tank includes a second round tank, the upper side wall of the second round tank is provided with a fourth feed pipe 31, the bottom of the second round tank is provided with an external separation oil output end 32, and the second round tank is provided with a heating coil 33; the secondary four-phase separation tank and the tertiary four-phase separation tank are respectively provided with heating equipment, so as to control the temperature of the secondary four-phase separation tank and the tertiary four-phase separation tank during use, so that the material maintains the set temperature and improves the separation effect.

[0039] In this embodiment, the solid-liquid separation dehydrator and the secondary solid-liquid separator are respectively provided with an external dehydrated dry mud output terminal so as to discharge the squeezed dry mud.

[0040] In this embodiment, the solid-liquid separation dehydrator and the secondary solid-liquid separator are centrifuges, plate and frame filter presses, belt filter presses, screw stacking machines or screw stringing machines.

[0041] A refinery oily sludge treatment process, including a refinery oily sludge treatment system, comprises the following steps:

[0042] (1) When the concentration of raw materials such as refining sludge or refining scum is high, an external container is required to dilute the raw materials to more than 95% water content for treatment, and pump the materials to be treated into the feed reaction tank, add the composite flocculant in the feed reaction tank, and stir quickly to fully mix the agent and the materials;

[0043] (2) The mixed materials are sent to a primary sedimentation separation tank for further reaction, and the slag-water mixture discharged from the primary sedimentation separation tank is sent to a solid-liquid separation dehydrator; the dry mud discharged from the solid-liquid separation dehydrator is subjected to thermal desorption treatment, and the discharged liquid enters a secondary four-phase separation tank for static separation;

[0044] (3) The slag phase separation product from the secondary four-phase separation tank is returned to the primary sedimentation separation tank for treatment, the oil phase separation liquid produced by the secondary four-phase separation tank is discharged to the waste oil aging separation tank for storage, the suspended separation product is sent to the secondary solid-liquid separator for dehydration, and the water phase separation liquid is sent to the tertiary four-phase separation tank for static separation;

[0045] (4) The dry mud discharged from the secondary solid-liquid separator is subjected to thermal desorption treatment, and the discharged liquid is sent to the third-stage four-phase separation tank for static separation;

[0046] (5) The suspended separation and slag phase separation of the three-stage four-phase separation tank are returned to the first-stage sedimentation separation tank for treatment, and the oil phase separation liquid of the three-stage four-phase separation tank is discharged to the waste oil aging separation tank for storage. The water phase separation liquid of the three-stage four-phase separation tank meets the external discharge index and is discharged.

[0047] In this embodiment, the temperature of the feed reaction tank, the first-stage sedimentation separation tank, the second-stage four-phase separation tank, the third-stage four-phase separation tank, and the waste oil aging separation tank is maintained at 60±5° C., thereby improving the separation effect.

[0048] In this embodiment, the composite flocculant is an RJ2 type high-efficiency composite flocculant to improve the flocculation effect.

[0049] By heating and adding proprietary composite flocculants, the oil content of the solid-liquid separation dehydrator and the dry mud removed can reach less than 5%, and the water content is no higher than 65%, which meets the feed process parameters for subsequent thermal desorption treatment of the dry mud.

[0050] The above description is only a preferred embodiment of the present invention. For ordinary technicians in this field, according to the teachings of the present invention, it does not require creative labor to design different forms of refinery oily sludge treatment systems and processes. Without departing from the principles and spirit of the present invention, all equal changes, modifications, substitutions and variations made within the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A refinery oily sludge treatment system, comprising a feed reaction tank, characterized in that: The output end of the feed reaction tank is connected to a primary sedimentation separation tank, the output end of the primary sedimentation separation tank is connected to a solid-liquid separation dehydrator, the water phase separation liquid output end of the solid-liquid separation dehydrator is connected to a secondary four-phase separation tank, the slag phase separation output end of the secondary four-phase separation tank is connected to the primary sedimentation separation tank, the oil phase separation liquid output end of the secondary four-phase separation tank is connected to a waste oil aging separation tank, the water phase separation liquid output end of the secondary four-phase separation tank is connected to a third-level four-phase separation tank, the suspended separation output end of the secondary four-phase separation tank is connected to a secondary solid-liquid separator, the suspended separation output end and the slag phase separation output end of the third-level four-phase separation tank are respectively connected to the primary sedimentation separation tank, the oil phase separation liquid output end of the third-level four-phase separation tank is connected to the waste oil aging separation tank, and the separation liquid output end of the secondary solid-liquid separator is connected to the third-level four-phase separation tank; the secondary four-phase separation tank and the three-stage four-phase separation tank respectively include an outer shell, wherein a scum collecting barrel whose bottom end is connected to the outer shell is arranged inside the outer shell, the scum collecting barrel is connected to the feed port via a distributor arranged inside the scum collecting barrel, the upper end of the scum collecting barrel is connected to the scum collector, the upper part of the scum collector is connected to the scum discharge port so as to discharge the suspended separated matter, the lower part of the scum collector is connected to the oil discharge port, the bottom of the outer shell is connected to the scum discharge port, and the top end is connected to the water outlet; the distributor includes a third feed pipe vertically arranged in the scum collecting barrel and connected to the feed port, the upper outer periphery of the third feed pipe is provided with a first cone top forming a first flow gap with the inner wall of the scum collecting barrel, and a second cone top is provided above the third feed pipe, and a second flow gap is formed between the second cone top and the first cone top; the scum collector is arranged on the upper outer periphery of the scum collecting barrel and forms a scum discharge chamber with the scum collecting barrel; The solid-liquid separation dehydrator and the secondary solid-liquid separator are centrifuges, plate and frame filter presses, belt filter presses, screw stacking machines or screw stringing machines.

2. A refinery oily sludge treatment system according to claim 1, characterized in that: The feed reaction tank comprises a first round tank, in which an agitator is arranged, a first feed pipe is arranged on the upper side wall of the first round tank, and a first discharge pipe is arranged on the bottom of the first round tank; the first-level sedimentation separation tank comprises a conical bottom round tank, in which an agitator is arranged, a second feed pipe is arranged on the upper side wall of the conical bottom round tank, and a second discharge pipe is arranged on the bottom of the conical bottom round tank; the feed reaction tank and the first-level sedimentation separation tank are also respectively provided with heating equipment.

3. The oily sludge treatment system of a refinery according to claim 1, characterized in that: A slag discharge pipeline connected to the slag discharge port is arranged at the bottom of the shell, the slag discharge port is arranged at the upper part of the slag collector and passes through the shell, the oil discharge port is arranged at the lower part of the slag collector and passes through the shell, and a drainage pipeline is also arranged at the upper end of the slag collector, and the drainage pipeline is connected to the drainage port through an overflow groove arranged on the top of the shell.

4. A refinery oily sludge treatment system according to claim 1, 2 or 3, characterized in that: The waste oil aging separation tank includes a second round tank, a fourth feed pipe is arranged on the upper side wall of the second round tank, an external separation oil output end is arranged on the bottom of the second round tank, and a heating coil is arranged on the second round tank; heating equipment is respectively arranged in the secondary four-phase separation tank and the tertiary four-phase separation tank.

5. The oily sludge treatment system of a refinery according to claim 1, characterized in that: The solid-liquid separation dehydrator and the secondary solid-liquid separator are respectively provided with an external discharge dehydrated dry mud output terminal.

6. A refinery oily sludge treatment process, comprising a refinery oily sludge treatment system according to claim 1, 2 or 3, characterized in that: The steps include: (1) Dilute the refining sludge or refining slag to a water content of more than 95% for treatment, and pump the material to be treated into the feed reaction tank, add the composite flocculant into the feed reaction tank, and stir quickly to fully mix the agent and the material; (2) The mixed materials are sent to a primary sedimentation separation tank for further reaction, and the slag-water mixture discharged from the primary sedimentation separation tank is sent to a solid-liquid separation dehydrator; the dry mud discharged from the solid-liquid separation dehydrator is subjected to thermal desorption treatment, and the discharged liquid enters a secondary four-phase separation tank for static separation; (3) The slag phase separation product from the secondary four-phase separation tank is returned to the primary sedimentation separation tank for treatment, the oil phase separation liquid produced by the secondary four-phase separation tank is discharged to the waste oil aging separation tank for storage, the suspended separation product is sent to the secondary solid-liquid separator for dehydration, and the water phase separation liquid is sent to the tertiary four-phase separation tank for static separation; (4) The dry mud discharged from the secondary solid-liquid separator is subjected to thermal desorption treatment, and the discharged liquid is sent to the third-stage four-phase separation tank for static separation; (5) The suspended separation and slag phase separation of the three-stage four-phase separation tank are returned to the first-stage sedimentation separation tank for treatment, the oil phase separation liquid of the three-stage four-phase separation tank is discharged to the waste oil aging separation tank for storage, and the water phase separation liquid of the three-stage four-phase separation tank meets the external discharge index and is discharged.

7. A refinery oily sludge treatment process according to claim 6, characterized in that: The temperature of the feed reaction tank, the primary sedimentation separation tank, the secondary four-phase separation tank, the tertiary four-phase separation tank and the waste oil aging separation tank is maintained at 60±5°C.

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