Solution to the cleavage and explosion of Alfalava plate heat exchanger surface de-coking and oil removal

Abstract

The present invention belongs to the field of maintenance and cleaning in the petrochemical industry. A method for solving the problem of cleavage and explosion membrane for de-coking and de-oiling on the surface of Alfalava plate heat exchangers. After switching the plate exchanger, there is no need to open the plate exchanger body. Without disassembly, a closed operating system is formed by connecting pipelines and 316L stainless steel to make a centrifugal pump and a closed stainless steel reactor; after the sealed operating system and the plate exchanger are connected, a set of plate exchanger-plate exchanger extracorporeal circulation closed operating reaction system is formed; with a number of plant enzyme reactants as carriers, a number of plant enzyme reactants react on the surface of the spiral structure inside the plate exchanger to generate continuous cleavage and explosion membranes; under the physical crushing action, the coke scale is turned into small particles of powder, and the closed reaction system is continuously circulated to bring the crushed coke scale powder and asphaltene scale out of the plate exchanger body to complete the de-coking and de-scaling. The present invention will not cause equipment damage, nor will it produce toxic and harmful gases, liquids, and solids that are harmful to the human body. The discharge will not have an adverse effect on the environment, and it can be naturally degraded.

Description

Technical Field

[0001] The invention belongs to the field of maintenance and cleaning of the refining industry, and in particular relates to the cleaning of oil-coke mixed scale on the surface of a plate heat exchanger in the refining industry. Background Art

[0002] The Swedish multinational company Alfa Laval put into use a spiral plate heat exchanger (hereinafter referred to as the plate heat exchanger) in the ebullated bed residue hydrocracking unit of the domestic refining industry. This was the first time that the equipment was used in China. Due to various reasons, scaling and blockage problems frequently occurred in the equipment within 1-3 months after it was put into use, which seriously threatened and affected the smooth operation of the ebullated bed hydrocracking unit.

[0003] At present, there are documents that disclose that when Alfalava plate heat exchangers are used in continuous reforming devices, the cleaning method adopted is chemical cleaning, using Na2CO3 for cleaning, but it also has its shortcomings and is prone to alkali embrittlement. Currently, attempts are made to use organic and high-temperature decomposition agents.

[0004] However, there is no ready-made experience at home and abroad to solve the clogging problem of Alfalava plate heat exchangers used in boiling bed residue oil hydrocracking units in the domestic refining industry. It is said that the clogging of the plate heat exchanger is directly related to the type of refined oil. In the case that the quality of crude oil cannot be changed, finding a feasible and convenient solution has important economic and demonstration significance. However, there is no complete and mature solution for reference internationally. Summary of the invention

[0005] The purpose of the present invention is to solve the serious coking and clogging problem of Alfalava plate heat exchanger after use, to provide a method for cleavage and explosion membrane to solve the problem of decoking and oil removal on the surface of Alfalava plate heat exchanger, and to effectively achieve the following two purposes:

[0006] (1) Inorganic coke scale and organic residue oil scale coexist and are solved simultaneously, and the bursting membrane formed does not damage the plate heat exchanger body.

[0007] (2) Large pieces of hard scale are effectively discharged from the equipment after blasting and cleavage reactions.

[0008] The technical scheme adopted by the present invention to achieve the above-mentioned purpose is: a method for solving the cleavage and explosion membrane of the Alfalava plate heat exchanger surface for de-coking and de-oiling. After switching the plate heat exchanger, the plate heat exchanger body does not need to be opened, and the closed stainless steel reactor is formed by connecting pipelines and 316L stainless steel to form a closed operating system without disassembly; after the sealed operating system is connected to the plate heat exchanger, a set of plate heat exchanger-plate heat exchanger extracorporeal circulation closed operating reaction system is formed; with a plurality of plant enzyme reactants as carriers, the plurality of plant enzyme reactants react on the surface of the spiral structure inside the plate heat exchanger to generate continuous cleavage and explosion membranes; the cleavage and explosion membrane continuously impacts the surface of the oil and coke mixed scale of the plate heat exchanger body by continuously generating O2 explosion gas, and the coke scale is changed into small particles of coke scale powder, and the closed reaction system is continuously circulated, and the coke scale powder and asphaltene scale are brought out of the plate heat exchanger body, and are settled in the cycle to complete de-coking and de-scaling.

[0009] Furthermore, the optimization scheme of the present invention is:

[0010] S1: The plate heat exchanger-plate heat exchanger extracorporeal circulation closed operation reaction system is formed by connecting stainless steel pipelines, 316L stainless steel horizontal single-stage centrifugal pumps and stainless steel reactors with steam heating function without disassembling the plate heat exchanger. The 316L stainless steel horizontal single-stage centrifugal pump is equipped with a motor. After the sealing operation system and the plate heat exchanger are connected, a set of plate heat exchanger-plate heat exchanger extracorporeal circulation closed operation reaction system is formed; water test operation, leak detection, to ensure that the system has no leaks;

[0011] S2: The plate heat exchanger-plate heat exchanger extracorporeal circulation closed operation reaction system uses hot water to heat up to 80-95°C, and adds plant enzyme reagents; the addition of plant enzyme reagents forms a cleavage reaction that will produce a bursting membrane. Through the dual effects of physics and chemistry, the scale surface inside the plate heat exchanger is broken by physical impact, disturbance and other crushing effects, so as to achieve the effect of loosening, peeling and crushing the oil coke mixed scale;

[0012] The circulation reaction is carried out for 15 hours, and the circulation direction is switched every 1-1.5 hours; the hard coke scale deposited on the bottom of the reactor is cleaned in time; the plate heat exchanger body is basically clean. The above reaction time is 30-40 hours, and it can be put into use immediately.

[0013] The present invention is an innovative process. In order to achieve the particularity of removing both inorganic coke hard scale and organic high molecular weight residual oil mixed entrainment, a closed reaction circulation system is equipped on site. The cleavage explosion membrane technology generated by plant enzyme reactants is used to solve the frequent blockage problem of plate heat exchangers.

[0014] The method, mechanism and main reaction equation of the present invention for removing oil-coke mixed scale by bursting membrane are as follows:

[0015] The equations for the reactions of the main plant enzymes are:

[0016] Na2Cr2O7+ CmHn+OH - → 2CrO3+Na4Cr O4+H2O2+O2↑, where the chemical formula of CmH is a large amount of residual oil component, C is generally between 30-260

[0017] The reaction process produces an instantaneous burst of O2, which plays a role in cleavage and forced peeling.

[0018] Among them, H2O2 further reacts to form an explosion effect, the mechanism is the same as above, the reaction formula is:

[0019] H2O2→H2O+O2↑

[0020] The cleavage explosion membrane continuously generates O2 explosion gas, which continuously impacts the surface of the oil-coke mixed scale of the plate heat exchanger body, and the coke scale turns into small particles of coke scale powder. The closed reaction system circulates continuously, and the coke scale powder and asphaltene scale are brought out of the plate heat exchanger body and settle in the circulation, completing the de-coking and descaling.

[0021] In addition, the oxide components in the blasting agent and the large amount of residual oil decompose, and the large amount of molecular chains are decomposed through continuous catalytic effect to generate small amounts of hydrocarbon polymers and CO, CO2 gas, and O2 produced by the decomposition of the above-mentioned oxidants. Similar to the reaction process, the CO and CO2 produced in the reaction process explode instantly, which also plays a role in cleavage and forced stripping, and flows out of the circulation system into the sedimentation tank outside the equipment body.

[0022] Through physical and chemical organic combination:

[0023] (1) Physical impact: disturbance and peeling;

[0024] (2) Chemical cleavage: Plant enzymes cleave and decompose asphalt soft scale, producing explosive micro-bubbles;

[0025] Through the above-mentioned dual physical and chemical effects, the oil-coke mixed scale attached to the surface of the internal equipment body of the plate heat exchanger disintegrates, and the coke scale changes from large pieces to small pieces, small pieces to crushed pieces, and crushed pieces to small particles of powder. The closed reaction system circulates continuously, bringing the crushed coke scale powder and asphaltene scale out of the plate heat exchanger body and settling them during the circulation, achieving the effect of cleaning and descaling. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the present invention.

[0027] Figure 2 It is a partial schematic diagram of the interior of the bursting membrane formed by the present invention.

[0028] In the figure: 1 plate heat exchanger; 2 stainless steel pipeline; 3 plant enzyme reactant; 4 stainless steel reactor; 5 heater; 6 horizontal single-stage centrifugal pump; 7 oil coke mixed scale; 8 bursting membrane. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with specific embodiments, but the present invention is not limited to the specific embodiments.

[0030] like Figure 1 As shown, without disassembling the plate heat exchanger 1, the stainless steel pipeline 2, the 316L stainless steel horizontal single-stage centrifugal pump 6 and the 10 cubic stainless steel reactor 4 with the steam heater 5 are connected to form a closed operating system, wherein the 316L stainless steel horizontal single-stage centrifugal pump is equipped with a 75kw motor, a head of 80 meters, and a speed of 1450r / min. After the sealed operating system and the plate heat exchanger are connected, a set of plate heat exchanger-plate heat exchanger extracorporeal circulation closed operating reaction system is formed; water test operation, leak detection;

[0031] When there is no leak, hot water is heated to 80°C and a plant enzyme reagent 3 is added; the addition of the plant enzyme reagent forms a cleavage reaction that produces a bursting membrane 8. The method, mechanism, and main reaction equations for removing oil-coke mixed scale by the bursting membrane are as follows:

[0032] The equations for the reactions of the main plant enzymes are:

[0033] Na2Cr2O7+ CmHn+OH - → 2CrO3+Na4Cr O4+H2O2+O2↑, where the chemical formula of CmH is a large amount of residual oil component, C is generally between 30-260

[0034] The reaction process produces an instantaneous burst of O2, which plays a role in cleavage and forced peeling.

[0035] Among them, H2O2 further reacts to form an explosion effect, the mechanism is the same as above, the reaction formula is:

[0036] H2O2→H2O+O2↑

[0037] The cleavage explosion film continuously generates O2 explosion gas, which continuously impacts the surface of the oil-coke mixed scale 7 of the plate heat exchanger body, and the coke scale turns into small particles of coke scale powder;

[0038] In addition, the oxide components in the blasting agent and the large amount of residual oil decompose, and the large amount of molecular chains are decomposed through continuous catalytic effect to generate small amounts of hydrocarbon polymers and CO, CO2 gas, and O2 produced by the decomposition of the above-mentioned oxidants. Similar to the reaction process, the CO and CO2 produced in the reaction process explode instantly, which also plays a role in cleavage and forced stripping.

[0039] The closed reaction system circulates continuously for 15 hours, and the circulation direction is switched every hour; the crushed coke scale powder and asphaltene scale are brought out of the plate heat exchanger body, and the hard coke scale deposited at the bottom of the reactor is cleaned in time, and the plate heat exchanger body is basically clean. The above reaction time is 30 hours, and the plate heat exchanger can be put into use immediately after the coke cleaning and descaling are completed.

[0040] Experiments have proved that the core of the present invention is the chemical cleavage effect of plant enzymes, which forms a large number of tiny bubbles on the surface of the plate heat exchanger. The bubbles are explosive in an instant and can reach a micro-area pressure environment of 1000MP, instantly crushing 95% of the oil coke mixed scale attached to the surface of the plate heat exchanger body. In addition, the high-speed circulation effect of the closed reaction system brings most of the powdered, cleaved and decomposed oil coke mixed scale out of the plate heat exchanger body and settles in the circulating plate heat exchanger extracorporeal reactor.

[0041] The present invention adopts different plant enzyme reactants, which can self-remove different residual oil scales and coke scales synchronously at the same time, and at the same time cooperate with each other, and no offset reaction will occur between the plant enzyme reactants. The bursting membrane generated instantly will not cause equipment damage after explosion. In the process of the plant enzyme reactants reacting to form the bursting membrane, no toxic and harmful gases, liquids, and solids that are harmful to the human body are generated, and the discharge will not have an adverse effect on the environment, so that it can be naturally degraded.

Claims

1. A method for solving the problem of cleavage and explosion of Alfalava plate heat exchanger surface de-coking and de-oiling, characterized in that: After switching the plate heat exchanger, there is no need to open the plate heat exchanger body. Without disassembling, a closed operating system is formed by connecting pipelines and a centrifugal pump made of 316L stainless steel or titanium stainless steel and a closed stainless steel reactor; after the sealed operating system is connected to the plate heat exchanger, a set of plate heat exchanger-plate heat exchanger extracorporeal circulation closed operating reaction system is formed; with a number of plant enzyme reactants Na2Cr2O7 as carriers, a number of plant enzyme reactants Na2Cr2O7 react on the surface of the spiral structure inside the plate heat exchanger to generate continuous cleavage explosion membranes, and the cleavage explosion membranes continuously generate O2 explosion gas to continuously impact the surface of the oil and coke mixed scale of the plate heat exchanger body, and the coke scale becomes small particles of coke scale powder, and the closed reaction system circulates continuously, switching and changing the circulation direction every 1-1.5 hours, bringing the coke scale powder and asphaltene scale out of the plate heat exchanger body, settling in the circulation, and completing the de-coking and descaling.

2. The method for cleavage and explosion membrane for de-coking and oil removal on the surface of Alfalava plate heat exchanger according to claim 1 is characterized in that: S1: The plate heat exchanger-plate heat exchanger extracorporeal circulation closed operation reaction system is formed by connecting stainless steel pipelines, 316L stainless steel horizontal single-stage centrifugal pumps and stainless steel reactors with steam heating function without disassembling the plate heat exchanger. The 316L stainless steel horizontal single-stage centrifugal pump is equipped with a motor. After the sealing operation system and the plate heat exchanger are connected, a set of plate heat exchanger-plate heat exchanger extracorporeal circulation closed operation reaction system is formed; water test operation, leak detection, to ensure that the system has no leaks; S2: The plate heat exchanger-plate heat exchanger extracorporeal circulation closed operation reaction system is heated to 80-95°C by hot water, and the plant enzyme reagent Na2Cr2O7 is added; the plant enzyme reagent Na2Cr2O7 is added to form a cleavage reaction that will produce a bursting membrane, and through the dual effects of physics and chemistry, the scale surface inside the plate heat exchanger is physically impacted, disturbed and crushed, so as to achieve the effect of loosening, peeling and crushing the oil coke mixed scale; The cycle reaction lasts for 15 hours, and the cycle direction is switched every 1-1.5 hours; the hard coke scale deposited at the bottom of the reactor is cleaned in time; The plate heat exchanger body is clean and can be put into use immediately.

Images