RU2173578C1 - Method of preparing sorbent for removing oil from water and solid surfaces - Google Patents

Abstract

FIELD: oil pollution removal. SUBSTANCE: carrier with moisture content no higher than 60% is preliminarily dehydrated to 20-48% moisture. Dehydration can be achieved mechanically: carrier is either compacted at pressure up to 10 MPa or moisture is removed when molding organomineral carrier and drying it under normal conditions. Carrier can be, in particular, high-moor or transition peat and also woodworking waste (e.g. lignin). Dried carrier is impregnated under anaerobic conditions with water-insoluble carbon-containing resins releasing in common with carbon dioxide from carrier at heat treatment for 20 to 90 min at temperature by 15-30 C superior to temperature required to release water- insoluble resins, after which carrier is cooled to temperature no higher than 30 C. EFFECT: reduced expenses with no loss in oil sorption efficiency. 2 cl

Description

 The invention relates to a method for producing a sorbent for purifying water and solid surfaces from oil and oil products.

 The sorbent obtained by the proposed method can be used to purify water and solid surfaces when applying the sorbent and collecting the spent sorbent mechanically in ports, rivers, industrial sites of enterprises and streets of settlements and, which is very important, in wastewater treatment in treatment plants with a progressive design providing for the removal of oil products from water by dispersed, freely floating sorbents.

 Known methods for producing sorbents in which the carrier material is previously subjected to thermal artificial drying [1, 2].

 The disadvantage of these methods is the preliminary thermal artificial drying of the material associated with the large expenditures of thermal energy for the phase transformation of water into steam (up to 5200 kJ per 1 kg of evaporated moisture), which evaporates up to 0.5 tons per ton of carrier material.

 A known method of producing a sorbent [3], carried out by heat treatment of the carrier in an inert gas - nitrogen - to increase the oil capacity of the sorbent.

 The disadvantage of this method is the presence of additional utilities for supplying nitrogen to the working area of the device, dosing it in predetermined volumes, monitoring the presence of nitrogen in the device, as well as storage and transportation costs when using nitrogen as an inert gas.

 The closest analogue adopted for the prototype is a method of producing a sorbent [4]. It uses peat as a carrier, which is brought to a moisture content of 25% by preliminary thermal artificial drying (hereinafter referred to as the dryer) and is pressed into briquettes followed by hydrophobization without air access by the thermal method with water-insoluble agents that are part of the carrier material.

 One of the main disadvantages of the method [4] is the high cost of thermal energy (0.25 tons of liquid fuel per 1 ton of dryer), spent on the phase transformation of free (capillary) water into steam (0.5 tons of water per 1 ton of dryer), and also the cost of electric energy - 250 kW / h for pressing 1 ton of briquettes from the dryer. Also a significant disadvantage of the method [4] is the high residual temperature of the obtained sorbent at the end of the process, as a result of which, in contact with atmospheric oxygen, the ash content of the dryer increases and a sorbent with a low oil capacity is obtained.

 The proposed method for producing the sorbent eliminates the disadvantages of the known methods.

The objectives of the invention:
1. Reducing the cost of removing from the source material of the carrier of moisture present in the carrier in the form of free (capillary) water, which does not require phase transformations to vapor to remove it, due to the exclusion of thermal artificial drying.

 2. Obtaining a sorbent having increased sorption ability, allowing to mechanize its use.

 3. Creation of explosion-proof production for the production of sorbent by eliminating peat dust from the process of aerosol formation during the artificial drying of peat.

The goals are achieved through the use of organo-mineral carriers with a moisture content not exceeding 60% with similar physicochemical properties (peat of high or transient, or wood processing waste - lignin). Moisture is preliminarily removed from the carrier by molding and natural drying, or by pressing (mechanical dehydration) with a force of up to 10 MPa, as a result, a solid lumpy intermediate product with a moisture content of up to 20-48% is obtained, the material of which is impregnated during heat treatment with water-insoluble carbon-containing resins without access of atmospheric oxygen for 20-90 min at a temperature of 15-30 ^o C above the temperature of the allocation of water-insoluble resins in the environment of carbon dioxide, released under the action of temperature from the carrier together with resins.

The heat treatment process is completed at a temperature not exceeding 30 ^o C.

 Example 1. A method of obtaining a sorbent.

 Take milled peat of a small degree of decomposition with a moisture content not exceeding 60%, which is dehydrated to a moisture content of 20-48% by pressing with a force of up to 10 MPa. The cost of removing moisture in this case is not more than 30 kW / h per 1 ton of solid product. (For comparison, according to the known method [4], 0.25 tons of liquid heating oil is consumed per 1 ton of dryer. In addition, 250 kW / h of electric power is needed for briquetting by pressing 1 ton of carrier.

 Comparative characteristics of the sorbent obtained by the present method, and the sorbent obtained by a known method [4] are shown in the table.

The resulting solid lumpy product is heated in carbon dioxide without air oxygen with a 20-90 minute exposure at a temperature higher by 15-30 ^o C the temperature of the allocation of water-insoluble resins (tar) from the carrier, after which it is cooled to a temperature not exceeding 30 ^o C (table - columns 4, 7, 10, 12). Changing the exposure time (table - columns 9, 10, 11), process temperature (table - columns 6, 7, 8) and the temperature of the end of heat treatment (columns 12, 13, 14) get three sorbent options, the characteristics of which are summarized in the table for convenience .

 From the table (columns 4 and 5) it can be seen that the sorbent in the proposed method is 1.1-1.15 times superior in oil intensity to the known one.

 Deviations from the exposure time proposed in the method (column 10), and from the temperature of the 20-90-minute exposure time (column 7), as well as the temperature of the end of the heat treatment (column 12) are the reasons for obtaining sorbents with worse properties that do not meet the objectives of the proposed method (columns 6, 9, 13, 14).

 With increasing temperature and the exposure time of the carrier treatment (columns 6-11), the properties of the sorbent improve slightly, while the energy consumption in this case increases by 2-3 times from the proposed method. In this regard, we take the parameters for obtaining the sorbent according to the proposed method (columns 7, 10, 12).

 The sorbent in the form of a powder with particle sizes up to 1.5 mm, obtained by the proposed method, for a long time retains the desired properties when exposed to changing external factors.

When using the sorbent is applied to the surface of the collected oil or introduced into the water in a stream of water under pressure up to 200 MPa or in a stream of compressed air (at negative ambient temperature up to minus 35 ^o C). Within 30-90 s, 1 g of the sorbent absorbs 1.29-6.7 g of oil products.

 The spent sorbent is collected from a solid or water surface by various mechanisms with suction vacuum devices and Packed mechanically in a container.

 Thus, the urgent problem of obtaining a cheap sorbent that is 1.1-1.15 times higher than the oil capacity of the known one, which allows mechanizing 100% manual labor of accident liquidators using dispersed hydrophobic organomineral sorbents, as well as its regeneration at the oil spill response site, is solved in field conditions.

Literature
1. RU 2058682 C1, B 01 J 20/30, 93.05.31.

 2. SU 1773873 A1, C 02 F 1/28, 05/05/11.

 3. RU 2036843 C1, C 02 F 1/28, 92.02.17.

 4. RU 2116128 C1, B 01 J 20/24, 09.09.02.

Claims (2)

 1. A method of producing a sorbent for cleaning water and solid surfaces from oil, including the removal of moisture from an organomineral carrier and heat treatment in an inert gas medium without oxygen to impregnate the carrier with carbon-containing water-insoluble resins, characterized in that the moisture is removed from the carrier with a humidity of not higher than 60 % to 20 - 48% by pressing it with a force of up to 10 MPa or by molding with subsequent natural drying, heat treatment is carried out for 20 - 90 minutes at a temperature of 15 - 30 ° C above the temperature pouring water-insoluble resins from the carrier, and after heat treatment it is cooled to a temperature not exceeding 30 ° C.  2. The method according to claim 1, characterized in that as a carrier with a moisture content of not higher than 60%, horse or transitional peat is used, as well as wood processing waste, for example lignin.

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