Method and system for coupling thermal desorption of oil-containing diatomite and calcination of filter aid

Abstract

The invention belongs to the technical field of solid waste resource utilization, and particularly relates to a method and system for coupling thermal desorption of oil-containing diatomite and calcination of a filter aid. The system comprises an oil-containing diatomite thermal desorption system, a filter aid calcination system, a high-temperature flue gas heat exchange system and an oil-containing flue gas treatment system, the method comprises the following steps: (1) performing thermal desorption on oil-containing diatomite in a thermal desorption device to obtain deoiled diatomite and oil-containing flue gas; (2) calcining the deoiled diatomite in a rotary kiln, cooling after calcining, crushing, and grading to obtain a regenerated diatomite filter aid; and (3) the oil-containing flue gas enters a condensation system, liquid oil and a small amount of water are obtained after condensation separation, and waste gas enters a flue gas treatment system. According to the method, the rolling oil in the waste oil-containing diatomite can be recycled, and the regenerated diatomite filter aid is prepared by calcining the oil-containing diatomite subjected to thermal desorption, so that the resource waste is reduced, and the environmental pollution is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource utilization, and in particular relates to a method and system for coupling thermal desorption of oil-containing diatomite and calcination of a filter aid. Background Art

[0002] Due to its unique pore structure and excellent filtering ability, diatomaceous earth filter aid, as an efficient and environmentally friendly filtering medium, has been widely used in many industries such as food, beverage, pharmaceutical, and chemical. Diatomaceous earth is often used as a filter for rolling oil in the rolling process of metal aluminum. When the diatomaceous earth reaches the filtering saturation state, its filtering efficiency will decrease, and the diatomaceous earth needs to be replaced. The oil-containing diatomaceous earth discarded by the aluminum industry usually contains 25%-30% rolling oil and is currently managed as hazardous waste. Therefore, recycling the oil in the oil-containing diatomaceous earth and regenerating the de-oiled diatomaceous earth will help realize the resource utilization of solid waste and promote the development of a circular economy.

[0003] At present, a large number of studies have focused on the removal and recovery technology of oil in oil-containing diatomite. Some representative methods include "sulfuric acid-filtration refining technology" and "solvent replacement-distillation refining technology". These methods extract oil by adding sulfuric acid or organic solvents, and then separate the oil from the soil. However, the oil needs to be further neutralized with acid or alkali or separated by distillation, and the diatomite itself also needs further treatment. The process flow of these methods is long and the equipment requirements are also high. Thermal desorption technology has been widely used in the treatment of organic contaminated soil and oily sludge. There are also studies that apply thermal desorption technology to the treatment of oil-containing diatomite, and obtain filter aids by roasting regenerated diatomite. Patent CN 201710341474.6 discloses a method and system for recycling and regenerating oil-containing waste diatomite filter aids, which includes the following steps: A desorption regeneration, that is, the oil-containing waste diatomite is stirred and heated in a regenerator, and desorbed and regenerated at a temperature of 50-220°C for 1-5 hours to obtain regenerated diatomite with an oil content not exceeding 0.09%; B regenerated diatomite roasting, the regenerated diatomite is fully reacted with soda ash at a temperature of 500-1200°C in a rotary kiln to obtain high-purity roasted diatomite; C oil and gas recovery and reuse. The regenerator uses an electromagnetic heating device for heating, and the oil-containing diatomite is processed in batches, which cannot be operated continuously; at the same time, in order to achieve a better removal effect of oil in the diatomite (the oil content does not exceed 0.09%), the desorption time is relatively long; and the connection between the thermal desorption of the oil-containing diatomite and the roasting of the regenerated diatomite is not considered during the treatment process.

[0004] GB / T 24265-2014 "Industrial Diatomite Filter Aid" standard specifies the physical and chemical indicators of industrial diatomite filter aids made by calcination (650-1000℃) or flux calcination (800-1200℃). Among them, the classification of industrial diatomite filter aids is mainly based on permeability and SiO2 content. Considering that the subsequent calcination of the filter aid requires high temperature, and the remaining oil and heat in the diatomite after thermal desorption are conducive to the subsequent calcination of the diatomite, it is particularly necessary to develop a method and system that can couple the thermal desorption of oil-containing diatomite with the calcination of the filter aid. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method and system for coupling thermal desorption of oil-containing diatomite and calcination of filter aids, so that most of the oil in the oil-containing diatomite can be recycled, and the deoiled diatomite can be used as a filter aid after calcination. Under the premise of ensuring safe operation, the thermal desorption time of the oil-containing diatomite is shortened and energy saving and consumption reduction of the entire system are achieved.

[0006] The core innovations of the present invention include:

[0007] (1) The two processes of thermal desorption of oil-containing diatomite and calcination of filter aids were coupled to achieve effective desorption of rolling oil from oil-containing diatomite and convert the deoiled diatomite into raw material for filter aids, thereby realizing the recycling of resources.

[0008] (2) The oil content of oil-containing diatomite after thermal desorption can be controlled below 2.5wt%. Compared with the requirement of controlling the oil content to 0.3% or even lower in the prior art, the load of the thermal desorption process is significantly reduced, the thermal desorption time is greatly shortened, and the production efficiency is improved.

[0009] (3) The oil content of the oil-containing diatomite after thermal desorption is controlled below 2.5wt%, which can ensure the safe and stable operation of the subsequent rotary kiln calcination process. The remaining oil and heat contained in the deoiled diatomite can be effectively utilized as heat energy during the filter aid calcination process.

[0010] (4) The present invention allows the temperature range and residence time of the thermal desorption and calcination processes to be flexibly adjusted according to the quality of the desorbed oil and the performance index requirements of the required filter aid, so as to maximize energy utilization and reduce energy consumption.

[0011] In order to achieve the above object, the present invention adopts the following technical solution:

[0012] A method for coupling thermal desorption of oil-containing diatomite and calcination of filter aids, comprising the following steps:

[0013] 1) Thermal desorption of oil-containing diatomite: The oil-containing diatomite is thermally desorbed at 150-350°C in a thermal desorption device to obtain deoiled diatomite and oil-containing flue gas;

[0014] 2) Preparation of regenerated diatomite filter aid: The de-oiled diatomite is put into a rotary kiln and calcined at 650-1200°C, cooled by a single-drum cooler, and then crushed and classified to obtain regenerated diatomite filter aids of different specifications;

[0015] 3) Treatment of oily flue gas: The oily flue gas generated after desorption of oily diatomaceous earth enters the condensation system, and liquid oil and a small amount of water are obtained after condensation and separation, and the waste gas enters the flue gas treatment system.

[0016] Furthermore, in the step 1), the desorption time of the oil-containing diatomite by heating with a thermal desorption device is 20-50 minutes, and the vacuum degree in the thermal desorption device is maintained at 1000-7000Mpa.

[0017] Furthermore, in the step 1), the oil content of the deoiled diatomaceous earth obtained is ≤2.5wt%.

[0018] Furthermore, in the step 1), the heat required for the thermal desorption device comes from the heat transfer oil after heat exchange with the high-temperature flue gas at the tail of the rotary kiln; the outer layer of the heat transfer oil entering the thermal desorption device heats the inner layer of the oil-containing diatomaceous earth to achieve thermal desorption, and the rolling oil in the oil-containing diatomaceous earth is desorbed at 150-350°C; the cooled heat transfer oil returns to the heat transfer oil heat exchanger to exchange heat with the high-temperature flue gas.

[0019] Furthermore, in the step 2), the residence time of the deoiled diatomaceous earth in the rotary kiln is 15-45 min, and the rotation speed of the rotary kiln is controlled at 1.5-3.0 r / min.

[0020] The present invention also discloses a system for coupling thermal desorption of oil-containing diatomite and calcination of filter aids, including a thermal desorption system of oil-containing diatomite, a filter aid calcination system, a high-temperature flue gas heat exchange system, and an oil-containing flue gas treatment system;

[0021] The oil-containing diatomite thermal desorption system comprises a thermal desorption device and a heat transfer oil heat exchanger; after the oil-containing diatomite enters the thermal desorption device to desorb part or all of the rolling oil, the deoiled diatomite enters the rotary kiln;

[0022] The filter aid calcining system comprises a rotary kiln, a single-drum cooler and a crushing and screening device; the deoiled diatomaceous earth is calcined in the rotary kiln, the diatomaceous earth discharged from the rotary kiln enters the single-drum cooler for cooling, and then is crushed and classified by the crushing and screening device to obtain diatomaceous earth filter aids of different specifications;

[0023] The high-temperature flue gas heat exchange system includes a dust collector and a first flue gas treatment system; the high-temperature flue gas coming out of the rotary kiln tail enters the dust collector for dust removal, and then the low-temperature flue gas enters the first flue gas treatment system after sufficient indirect heat exchange in the thermal oil heat exchanger, and is discharged up to standard after treatment.

[0024] The oily flue gas treatment system comprises a condensation system and a second flue gas treatment system; the condensation system consists of a multi-stage cooler and an oil-water separator; after the oily diatomaceous earth is indirectly heated by the heat transfer oil, the rolling oil therein is desorbed, and the generated oily flue gas enters the condensation system, is cooled by the multi-stage cooler, and is separated by the oil-water separator, and finally liquid oil and a small amount of water are obtained, and the gas enters the second flue gas treatment system for treatment and then meets the emission standards.

[0025] Furthermore,

[0026] The kiln tail of the rotary kiln is connected to the gas inlet of the dust collector, the gas outlet of the dust collector is connected to the gas inlet of the thermal oil heat exchanger, and the gas outlet of the thermal oil heat exchanger is connected to the first flue gas treatment system;

[0027] And / or, the heat transfer oil outlet of the heat transfer oil heat exchanger is connected to the heating medium inlet of the thermal desorption device, and the heating medium outlet of the thermal desorption device is connected to the heat transfer oil inlet of the heat transfer oil heat exchanger;

[0028] And / or, the oily flue gas outlet of the thermal desorption device is connected to the gas inlet of the condensation system, and the gas outlet of the condensation system is connected to the second flue gas treatment system.

[0029] And / or, the kiln head of the rotary kiln is connected to the material inlet of the single-drum cooler; the material outlet of the single-drum cooler is connected to the material inlet of the crushing and screening device; the material outlet of the crushing and screening device is connected to the storage bin of the diatomaceous earth filter aid.

[0030] Furthermore, the thermal desorption device is a double-layer rotary indirect heat exchange device, the inner layer of which serves as a container for oil-containing diatomaceous earth and a thermal desorption reaction chamber, and the outer layer is used to place heat transfer oil; the heat required for the thermal desorption reaction in the inner layer comes from the high-temperature heat transfer oil in the outer layer.

[0031] Furthermore, the inner material inlet of the thermal desorption device is connected to the material outlet of the vacuum feeder; the inner material outlet of the thermal desorption device is connected to the kiln tail of the rotary kiln; the high-temperature heat transfer oil heats the inner layer of the oil-containing diatomaceous earth in the outer layer of the thermal desorption device to achieve thermal desorption; the cooled heat transfer oil returns to the heat transfer oil heat exchanger to exchange heat with the high-temperature flue gas from the rotary kiln, and the high-temperature heat transfer oil after heat exchange enters the outer layer of the thermal desorption device again to provide heat for thermal desorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic flow diagram of a method for coupling thermal desorption of oil-containing diatomite and calcination of filter aids provided by the present invention;

[0033] Figure 2 The color comparison of the liquid oil desorbed at different temperatures in Examples 1-3. From left to right: rolling oil (not yet used for filtration); liquid oil desorbed in Example 1; liquid oil desorbed in Example 2; liquid oil desorbed in Example 3;

[0034] Figure 3 The microstructure comparison of the filter aids calcined at different temperatures in each example. From left to right are: diatomite filter aid prepared in Example 1; diatomite filter aid prepared in Example 2; diatomite filter aid prepared in Example 3 at 1000-1200℃.

[0035] The advantages and positive effects of the present invention are:

[0036] (1) The present invention uses waste oil-containing diatomite to prepare industrial diatomite filter aids, fully utilizes the waste heat of the material from the thermal desorption system, and uses the high-temperature flue gas generated by the rotary kiln calcining system to provide a heat source for the thermal oil heat exchanger, thereby improving the thermal efficiency of the entire system and reducing energy consumption. At the same time, it avoids the problem that the remaining material needs to be further processed after only using the thermal desorption process to treat the oil-containing diatomite.

[0037] (2) The use of a rotary indirect heat exchange device ensures the continuous operation and safe operation of the equipment. At the same time, under the action of the heat transfer oil, the thermal desorption temperature can be kept within a certain range, that is, the problem of rolling oil cracking caused by excessively high temperature in the thermal desorption device in the form of indirect heat exchange outside the combustion chamber is avoided, and the problem of insufficient thermal desorption of rolling oil caused by too low temperature is also avoided.

[0038] (3) The oil content of the oil-containing diatomite, the composition of the rolling oil and the volatile temperature range are fully considered, so that the composition of the liquid oil obtained by thermal desorption can be adjusted as needed.

[0039] (4) It realizes the recycling of valuable resources and reduces the generation of hazardous waste in the aluminum processing industry. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments of the present invention are within the scope of protection of the present invention.

[0041] like Figure 1-3As shown, the present invention discloses a method for coupling thermal desorption of oil-containing diatomite and calcination of filter aids, comprising the following steps:

[0042] 1) Thermal desorption of oil-containing diatomite: The oil-containing diatomite is thermally desorbed in a thermal desorption device at a desorption temperature of 150 to 350° C. for a desorption time of 20 to 50 min. The vacuum degree in the thermal desorption device is maintained at 1000 to 7000 MPa. The oil content of the deoiled diatomite obtained after thermal desorption is ≤2.5 wt%;

[0043] 2) Preparation of regenerated diatomite filter aid: The deoiled diatomite is put into a rotary kiln for calcination at a temperature of 650 to 1200°C; the residence time in the kiln is 15 to 45 minutes; the deoiled diatomite is cooled by a single-drum cooler after leaving the kiln, and then crushed and classified to obtain a regenerated diatomite filter aid; the classification is based on permeability and SiO2 content;

[0044] 3) Heat exchange and treatment of high-temperature flue gas: Natural air enters through the tail end of the single-drum cooler, and after being heated by the kiln materials inside the single-drum cooler, the hot air enters from the head of the rotary kiln and is used as the combustion air of the calcination system; the high-temperature flue gas from the tail of the rotary kiln enters the dust collector for dust removal, and then enters the first flue gas treatment system after sufficient indirect heat exchange in the thermal oil heat exchanger, and is discharged after treatment to meet the standards.

[0045] 4) Heat transfer oil circulation heat exchange: The heat transfer oil heated by the heat transfer oil heat exchanger enters the outer layer of the rotary thermal desorption device to heat the oil-containing diatomaceous earth in the inner layer to achieve thermal desorption. The cooled heat transfer oil returns to the heat transfer oil heat exchanger to exchange heat with the high-temperature flue gas.

[0046] 5) Treatment of oily flue gas: After the oily diatomaceous earth is indirectly heated by heat transfer oil, the rolling oil in it is desorbed at 150-350℃, and the generated oily flue gas enters the condensation system, is cooled by a multi-stage cooler, and is separated by an oil-water separator, and finally liquid oil and a small amount of water are obtained; the waste gas enters the second flue gas treatment system for treatment and meets the emission standards.

[0047] The invention discloses a system for coupling thermal desorption of oil-containing diatomite and calcination of filter aids, an oil-containing diatomite thermal desorption system, a filter aid calcination system, a high-temperature flue gas heat exchange system, and an oil-containing flue gas treatment system;

[0048] The oil-containing diatomite thermal desorption system comprises a thermal desorption device and a heat transfer oil heat exchanger; after the oil-containing diatomite enters the thermal desorption device to desorb part or all of the rolling oil, the deoiled diatomite enters the rotary kiln;

[0049] The filter aid calcining system comprises a rotary kiln, a single-drum cooler and a crushing and screening device; the deoiled diatomaceous earth is calcined in the rotary kiln, the diatomaceous earth discharged from the rotary kiln enters the single-drum cooler for cooling, and then is crushed and classified by the crushing and screening device to obtain diatomaceous earth filter aids of different specifications;

[0050] In order to realize the above technical scheme, the inner material inlet of the thermal desorption device is connected to the material outlet of the vacuum feeder; the inner material outlet of the thermal desorption device is connected to the kiln tail of the rotary kiln; the high-temperature heat transfer oil heats the inner oil-containing diatomite in the outer layer of the thermal desorption device to achieve thermal desorption; the cooled heat transfer oil returns to the heat transfer oil heat exchanger to exchange heat with the high-temperature flue gas from the rotary kiln, and the high-temperature heat transfer oil after heat exchange enters the outer layer of the thermal desorption device again to provide heat for thermal desorption. The kiln head of the rotary kiln is connected to the material inlet of the single-cylinder cooler; the material outlet of the single-cylinder cooler is connected to the material inlet of the crushing and screening device; the material outlet of the crushing and screening device is connected to the storage bin of the diatomite filter aid.

[0051] Specifically, the order of diatomite movement is:

[0052] Thermal desorption step: the oil-containing diatomaceous earth enters a rotary thermal desorption device through a vacuum feeder, is thermally desorbed at a temperature of 150-350° C. to an oil content of ≤2.5 wt %, and is then discharged from an inner cylinder of the rotary thermal desorption device;

[0053] Calcination of filter aids: De-oiled diatomaceous earth enters the rotary kiln from the kiln tail, is calcined at 650-1200℃ in the kiln, and is discharged from the kiln head; the diatomaceous earth discharged from the kiln head of the rotary kiln enters the single-drum cooler for cooling, and then is crushed and graded by the crushing and screening device to obtain diatomaceous earth filter aids of different specifications, which are sent to the storage bin of diatomaceous earth filter aids;

[0054] The above technical solution couples the two steps of thermal desorption of oil-containing diatomite and calcination of filter aids, which not only realizes the desorption of rolling oil from the oil-containing diatomite, but also uses the deoiled diatomite to prepare diatomite filter aids.

[0055] Moreover, the oil content of the oil-containing diatomite after thermal desorption can be controlled within 2.5wt%, which reduces the burden of the thermal desorption process, greatly shortens the thermal desorption time, and thus improves production efficiency; and can ensure the safe and stable operation of the subsequent rotary kiln calcination, and the remaining oil and heat carried in the deoiled diatomite can be effectively utilized as heat energy in the subsequent filter aid calcination process.

[0056] The high-temperature flue gas heat exchange system includes a dust collector and a first flue gas treatment system; the high-temperature flue gas coming out of the rotary kiln tail enters the dust collector for dust removal, and then the low-temperature flue gas enters the first flue gas treatment system after sufficient indirect heat exchange in the thermal oil heat exchanger, and is discharged up to standard after treatment.

[0057] The oily flue gas treatment system comprises a condensation system and a second flue gas treatment system; the condensation system consists of a multi-stage cooler and an oil-water separator; after the oily diatomaceous earth is indirectly heated by the heat transfer oil, the rolling oil therein is desorbed, and the generated oily flue gas enters the condensation system, is cooled by the multi-stage cooler, and is separated by the oil-water separator, and finally liquid oil and a small amount of water are obtained, and the gas enters the second flue gas treatment system for treatment and then meets the emission standards.

[0058] Specifically: the kiln tail of the rotary kiln is connected to the gas inlet of the dust collector, the gas outlet of the dust collector is connected to the gas inlet of the thermal oil heat exchanger, and the gas outlet of the thermal oil heat exchanger is connected to the first flue gas treatment system;

[0059] The heat transfer oil outlet of the heat transfer oil heat exchanger is connected to the heating medium inlet of the thermal desorption device, and the heating medium outlet of the thermal desorption device is connected to the heat transfer oil inlet of the heat transfer oil heat exchanger;

[0060] The oily flue gas outlet of the thermal desorption device is connected to the gas inlet of the condensation system, and the gas outlet of the condensation system is connected to the second flue gas treatment system.

[0061] The order of flow of natural air, oily fume and heat transfer oil is:

[0062] Natural air enters through the tail end of the single-drum cooler, and after being heated by the kiln materials inside the single-drum cooler, the hot air enters from the kiln head of the rotary kiln and is used as the combustion air of the calcining system; the rotary kiln calcining system adopts the kiln head burner for combustion, and the fuel is natural gas; the high-temperature flue gas coming out of the rotary kiln tail enters the dust collector for dust removal, and after sufficient indirect heat exchange in the heat transfer oil heat exchanger, the flue gas enters the first flue gas treatment system, and is discharged up to the standard after treatment.

[0063] The heated heat transfer oil enters the outer layer of the rotary thermal desorption device to heat the oil-containing diatomaceous earth in the inner layer to achieve thermal desorption, and the cooled heat transfer oil returns to the heat transfer oil heat exchanger.

[0064] After the oil-containing diatomaceous earth is indirectly heated by the heat transfer oil, the rolling oil in it is desorbed at 150-350℃, and the generated oil-containing flue gas enters the condensation system, is cooled by the multi-stage cooler, and is separated by the oil-water separator. Finally, liquid oil and a small amount of water are obtained. The gas enters the second flue gas treatment system for treatment and meets the emission standards.

[0065] The working method of the above system is described in detail below through multiple embodiments:

[0066] Example 1

[0067] 1) Thermal desorption of oil-containing diatomite: The oil-containing diatomite with an oil content of 30.95% was thermally desorbed in a thermal desorption device at a desorption temperature of 150-200°C for 45 minutes. The vacuum degree in the thermal desorption device was maintained at 5000-7000 MPa. The oil content of the deoiled diatomite obtained after thermal desorption was 2.1%.

[0068] 2) Preparation of regenerated diatomite filter aid: the deoiled diatomite is put into a rotary kiln for calcination at a temperature of 650-1000°C; the residence time in the kiln is 40 minutes; the speed of the rotary kiln is controlled at 1.5-3.0 r / min; the deoiled diatomite is cooled by a single-drum cooler after leaving the kiln, and then crushed and classified to obtain the regenerated diatomite filter aid;

[0069] 3) Heat exchange and treatment of high-temperature flue gas: Natural air enters through the tail end of the single-drum cooler, and after being heated by the kiln materials inside the single-drum cooler, the hot air enters from the head of the rotary kiln and is used as the combustion air of the calcination system; the high-temperature flue gas from the tail of the rotary kiln enters the dust collector for dust removal, and then enters the first flue gas treatment system after sufficient indirect heat exchange in the thermal oil heat exchanger, and is discharged after treatment to meet the standards.

[0070] 4) Heat transfer oil circulation heat exchange: The heat transfer oil heated by the heat transfer oil heat exchanger enters the outer layer of the rotary thermal desorption device to heat the oil-containing diatomaceous earth in the inner layer to achieve thermal desorption, and the heat transfer oil after cooling returns to the heat transfer oil heat exchanger;

[0071] 5) Treatment of oily flue gas: After the oily diatomite is indirectly heated by heat transfer oil, the rolling oil in it is desorbed at 150-200℃, and the generated oily flue gas enters the condensation system, is cooled by a two-stage cooler, and is separated by an oil-water separator, and finally liquid oil and a small amount of water are obtained; the waste gas enters the second flue gas treatment system for treatment and meets the emission standards.

[0072] Example 2

[0073] 1) Thermal desorption of oil-containing diatomite: The oil-containing diatomite with an oil content of 30.95% was thermally desorbed in a thermal desorption device at a desorption temperature of 190-240°C for 20 minutes. The vacuum degree in the thermal desorption device was maintained at 2000-4000 MPa. The oil content of the deoiled diatomite obtained after thermal desorption was 1.6%.

[0074] 2) Preparation of regenerated diatomite filter aid: de-oiled diatomite is put into a rotary kiln for calcination at a temperature of 800-1000°C; the residence time in the kiln is 35 minutes; the speed of the rotary kiln is controlled at 1.5-3.0 r / min; the de-oiled diatomite is cooled by a single-drum cooler after leaving the kiln, and then crushed and classified to obtain a regenerated diatomite filter aid;

[0075] 3) Heat exchange and treatment of high-temperature flue gas: Natural air enters through the tail end of the single-drum cooler, and after being heated by the kiln materials inside the single-drum cooler, the hot air enters from the head of the rotary kiln and is used as the combustion air of the calcination system; the high-temperature flue gas from the tail of the rotary kiln enters the dust collector for dust removal, and then enters the first flue gas treatment system after sufficient indirect heat exchange in the thermal oil heat exchanger, and is discharged after treatment to meet the standards.

[0076] 4) Heat transfer oil circulation heat exchange: The heat transfer oil heated by the heat transfer oil heat exchanger enters the outer layer of the rotary thermal desorption device to heat the oil-containing diatomaceous earth in the inner layer to achieve thermal desorption, and the heat transfer oil after cooling returns to the heat transfer oil heat exchanger;

[0077] 5) Treatment of oily flue gas: After the oily diatomite is indirectly heated by heat transfer oil, the rolling oil in it is desorbed at 190-240°C, and the generated oily flue gas enters the condensation system, is cooled by a two-stage cooler, and is separated by an oil-water separator, and finally liquid oil and a small amount of water are obtained; the waste gas enters the second flue gas treatment system for treatment and meets the emission standards.

[0078] Example 3

[0079] 1) Thermal desorption of oil-containing diatomite: The oil-containing diatomite with an oil content of 30.95% was thermally desorbed in a thermal desorption device at a desorption temperature of 250-300°C for 25 minutes. The vacuum degree in the thermal desorption device was maintained at 1000-2000 MPa. The oil content of the deoiled diatomite obtained after thermal desorption was 0.5%.

[0080] 2) Preparation of regenerated diatomite filter aid: deoiled diatomite is put into a rotary kiln for calcination at a temperature of 1000-1200°C; sodium carbonate (12% by weight of deoiled diatomite) is added as a flux, and the residence time in the kiln is 20 minutes; the rotary kiln speed is controlled at 1.5-3.0 r / min; the deoiled diatomite is cooled in a single-drum cooler after leaving the kiln, and then crushed and classified to obtain a regenerated diatomite filter aid;

[0081] 3) Heat exchange and treatment of high-temperature flue gas: Natural air enters through the tail end of the single-drum cooler, and after being heated by the kiln materials inside the single-drum cooler, the hot air enters from the head of the rotary kiln and is used as the combustion air of the calcination system; the high-temperature flue gas from the tail of the rotary kiln enters the dust collector for dust removal, and then enters the first flue gas treatment system after sufficient indirect heat exchange in the thermal oil heat exchanger, and is discharged after treatment to meet the standards.

[0082] 4) Heat transfer oil circulation heat exchange: The heat transfer oil heated by the heat transfer oil heat exchanger enters the outer layer of the rotary thermal desorption device to heat the oil-containing diatomaceous earth in the inner layer to achieve thermal desorption, and the heat transfer oil after cooling returns to the heat transfer oil heat exchanger;

[0083] 5) Treatment of oily flue gas: After the oily diatomaceous earth is indirectly heated by heat transfer oil, the rolling oil in it is desorbed at 250-300°C, and the generated oily flue gas enters the condensation system, is cooled by a two-stage cooler, and is separated by an oil-water separator, and finally liquid oil and a small amount of water are obtained; the waste gas enters the second flue gas treatment system for treatment and meets the emission standards.

[0084] In Examples 1-3, the thermal desorption temperature and time are different, so the quality of the desorbed liquid oil is different, which can meet the needs of different application scenarios; the calcination temperature and residence time are different, so the performance indicators of the obtained filter aid can also be adjusted within a certain range, that is, by flexibly adjusting the temperature range and time of the thermal desorption and calcination processes, the quality of the liquid oil and the filter aid can be ensured to meet the requirements, while achieving a higher energy utilization efficiency.

[0085] The above embodiments are preferred examples for realizing the present invention. The present invention is not limited to the above embodiments. In addition to being used for calcining to prepare filter aids, it can also be used for flux calcining to prepare filter aids. Any non-essential additions and substitutions made by those skilled in the art based on the technical features of the technical solution of the present invention belong to the protection scope of the present invention.

Claims

1. A method for coupling thermal desorption of oil-containing diatomite and calcination of filter aids, characterized in that: The following steps are involved: 1) Thermal desorption of oil-containing diatomite: The oil-containing diatomite is thermally desorbed at 150-350°C in a thermal desorption device to obtain deoiled diatomite and oil-containing flue gas; 2) Preparation of regenerated diatomite filter aid: The de-oiled diatomite is put into a rotary kiln and calcined at 650-1200°C, cooled by a single-drum cooler, and then crushed and classified to obtain regenerated diatomite filter aids of different specifications; 3) Treatment of oily flue gas: The oily flue gas generated after desorption of oily diatomaceous earth enters the condensation system, and liquid oil and a small amount of water are obtained after condensation and separation, and the waste gas enters the flue gas treatment system.

2. The method for coupling thermal desorption of oil-containing diatomite and calcination of filter aids according to claim 1, characterized in that: In the step 1), the thermal desorption of the oil-containing diatomite is achieved by heating the thermal desorption device for a desorption time of 20-50 minutes, and the vacuum degree in the thermal desorption device is maintained at 1000-7000Mpa.

3. The method for coupling thermal desorption of oil-containing diatomite and calcination of filter aids according to claim 1, characterized in that: In the step 1), the oil content of the deoiled diatomaceous earth obtained is ≤2.5wt%.

4. The method for coupling thermal desorption of oil-containing diatomite and calcination of filter aids according to claim 1, characterized in that: In the step 1), the heat required for the thermal desorption device comes from the heat transfer oil after heat exchange with the high-temperature flue gas at the tail of the rotary kiln; the outer layer of the heat transfer oil entering the thermal desorption device heats the inner layer of the oil-containing diatomaceous earth to achieve thermal desorption, and the rolling oil in the oil-containing diatomaceous earth is desorbed at 150-350°C; the cooled heat transfer oil returns to the heat transfer oil heat exchanger to exchange heat with the high-temperature flue gas.

5. The method for coupling thermal desorption of oil-containing diatomite and calcination of filter aids according to claim 1, characterized in that: In the step 2), the residence time of the deoiled diatomaceous earth in the rotary kiln is 15-45 min, and the rotation speed of the rotary kiln is controlled at 1.5-3.0 r / min.

6. A system for coupling thermal desorption of oil-containing diatomite and calcination of filter aids, characterized in that: Including oil-containing diatomite thermal desorption system, filter aid calcination system, high-temperature flue gas heat exchange system, oil-containing flue gas treatment system; The oil-containing diatomite thermal desorption system comprises a thermal desorption device and a heat transfer oil heat exchanger; after the oil-containing diatomite enters the thermal desorption device to desorb part or all of the rolling oil, the deoiled diatomite enters the rotary kiln; The filter aid calcining system comprises a rotary kiln, a single-drum cooler and a crushing and screening device; the deoiled diatomaceous earth is calcined in the rotary kiln, the diatomaceous earth discharged from the rotary kiln enters the single-drum cooler for cooling, and then is crushed and classified by the crushing and screening device to obtain diatomaceous earth filter aids of different specifications; The high-temperature flue gas heat exchange system includes a dust collector and a first flue gas treatment system; the high-temperature flue gas from the rotary kiln tail enters the dust collector for dust removal, and then the low-temperature flue gas enters the first flue gas treatment system after sufficient indirect heat exchange in the heat transfer oil heat exchanger, and is discharged after being treated to meet the emission standards; The oily flue gas treatment system comprises a condensation system and a second flue gas treatment system; the condensation system consists of a multi-stage cooler and an oil-water separator; after the oily diatomaceous earth is indirectly heated by the heat transfer oil, the rolling oil therein is desorbed, and the generated oily flue gas enters the condensation system, is cooled by the multi-stage cooler, and is separated by the oil-water separator, and finally liquid oil and a small amount of water are obtained, and the gas enters the second flue gas treatment system for treatment and then meets the emission standards.

7. The system for coupling thermal desorption of oil-containing diatomite and calcination of filter aids as claimed in claim 6, characterized in that: The kiln tail of the rotary kiln is connected to the gas inlet of the dust collector, the gas outlet of the dust collector is connected to the gas inlet of the thermal oil heat exchanger, and the gas outlet of the thermal oil heat exchanger is connected to the first flue gas treatment system; And / or, the heat transfer oil outlet of the heat transfer oil heat exchanger is connected to the heating medium inlet of the thermal desorption device, and the heating medium outlet of the thermal desorption device is connected to the heat transfer oil inlet of the heat transfer oil heat exchanger; And / or, the oily flue gas outlet of the thermal desorption device is connected to the gas inlet of the condensation system, and the gas outlet of the condensation system is connected to the second flue gas treatment system. And / or, the kiln head of the rotary kiln is connected to the material inlet of the single-drum cooler; the material outlet of the single-drum cooler is connected to the material inlet of the crushing and screening device; the material outlet of the crushing and screening device is connected to the storage bin of the diatomaceous earth filter aid.

8. The system for coupling thermal desorption of oil-containing diatomite and calcination of filter aids as claimed in claim 6, characterized in that: The thermal desorption device is a double-layer rotary indirect heat exchange device, the inner layer of which serves as a container for oil-containing diatomaceous earth and a thermal desorption reaction chamber, and the outer layer is used to place heat transfer oil; the heat required for the thermal desorption reaction in the inner layer comes from the high-temperature heat transfer oil in the outer layer.

9. The system for coupling thermal desorption of oil-containing diatomite and calcination of filter aids as claimed in claim 8, characterized in that: The inner material inlet of the thermal desorption device is connected to the material outlet of the vacuum feeder; the inner material outlet of the thermal desorption device is connected to the kiln tail of the rotary kiln; The high-temperature heat transfer oil in the outer layer of the thermal desorption device heats the oil-containing diatomaceous earth in the inner layer to achieve thermal desorption; the cooled heat transfer oil returns to the heat transfer oil heat exchanger to exchange heat with the high-temperature flue gas from the rotary kiln, and the high-temperature heat transfer oil after heat exchange enters the outer layer of the thermal desorption device again to provide heat for thermal desorption.

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