RU2493902C1 - Unit for recovery of methanol from saturated aqueous solution - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention can be used in gas processing intended for prevention of crystalline hydrate formation. Methanol recovery unit comprises tank for water-saturated methanol, heat exchanger, scale control device, rectifier, recovered methanol accumulator, evaporator composed of heat pipe accommodating heating tubes and evaporator downcomer tube to feed gas into said rectifier, and combustor. Note here that rectifier, evaporator and combustor make an integral vertical unit.

EFFECT: minimised scaling, decreased overall dimensions.

6 cl, 3 dwg

Description

The invention relates to means for drying hydrocarbon gases (natural and petroleum), in particular to processes for the separation of methanol used in this process from water, and can be used in preparing gas for processing in order to prevent crystalline hydrates.

Known ((http://sapr-n.ru/regeneraciya_metanolnoj_vody.html) is a rectification processing line for water-saturated methanol. The line contains sequentially installed separation tank, heat exchanger, anti-scale device, distillation column where the distillation process takes place. The upper part of the column is connected to the refrigerator designed for cooling methanol vapors, the refrigerator outlet is connected to a methanol collector, and the lower part of the distillation column is connected to a fire evaporator.

A disadvantage of the known means should be recognized its significant dimensions, as well as the formation of scale on the flame tubes of the evaporator, the removal of which is technically difficult.

The technical problem to which the developed tool is aimed is to optimize the process of methanol regeneration from a solution saturated with water.

The technical result obtained by the implementation of the developed tool is to reduce the size of the equipment used while reducing salt deposits on the surface of the equipment used.

To achieve the specified technical result, it is proposed to use the developed methanol recovery unit from a saturated aqueous solution.

The developed device contains a series-installed container for water-saturated methanol, a heat exchanger, a descaling device, a distillation column and a collection of regenerated methanol, as well as an evaporator installed with the possibility of supplying to the lower part of the distillation column a gaseous medium heated to a temperature that separates the mixture of methanol and water, moreover, the evaporator is made in the form of at least one heat pipe, in which at least one heating pipe is located.

Depending on the volume of processed methanol-saturated water solution, the unit may contain more than one evaporator and / or an evaporator containing more than one heating pipe.

In most embodiments, the heating pipes in each evaporator are parallel to each other and uniformly across the volume of the evaporator.

Preferably, the total cross section of all the heating pipes in one evaporator is not more than 70% of the cross section of the evaporator.

Mostly, a heat pipe with an aqueous solution of methanol as a working substance was used as an evaporator.

During the implementation of the developed block, a saturated aqueous solution of methanol is fed through a heat exchanger and an anti-scale device to the middle part of the distillation column, a gaseous medium is heated to the bottom of the distillation column from the evaporator, heated to a temperature that separates the mixture of methanol and water (saturated aqueous methanol solution) with subsequent collection regenerated methanol, wherein at least one heat pipe is used as an evaporator, in which at least one heating tube is located throated pipe.

Heat pipes and heating pipes of circular or oval cross-section are preferably used.

The graphical material (Fig.1-Fig.3) shows a longitudinal section of a heat pipe-evaporator, as well as its two transverse sections, with the following notation: the outer wall 1 of the heat pipe, heating pipes 2, the working substance 3 of the heat pipe, coaxially located pipe 4, pipe 5, supplying thermal energy from the heater.

The methanol recovery unit used differs from the traditional installation in smaller dimensions due to the combination of the evaporation column and evaporator into one vertical unit.

The evaporator is made in the form of a heat pipe in which heating pipes are located. The evaporator can be made as a single heat pipe, or sectioned, i.e. in fact, several heat pipes - evaporators are installed in parallel. Inside the heat pipe there is a working substance - an aqueous solution of methanol (boiling point about 130 ° C), which during the evaporation-condensation process transfers heat from the heating zone to the zone of heating water vaporizing pipes. The heating of the lower part of the heat pipe is carried out in the combustion chamber, which is part of a single vertical unit together with a distillation column and an evaporator. The combustion chamber is equipped with burners evenly located in the lower part of the unit. The heat pipe emitted by them transfers the heat pipe directly to the heating pipes.

Due to this modernization, the required area of the methanol recovery unit is reduced by more than four times.

The use of the inner surfaces of cylindrical pipes for heating and evaporating water minimizes the deposition of salts on heat transfer surfaces. This is achieved by applying anti-adhesive coatings or polishing to the inner surface of the pipes. In addition, the inner surface of the pipes is easily cleaned of deposits by mechanical means with minimal dismantling of the installation. The specifics of the operation of the heat pipe ensures a constant temperature along the entire length of the evaporator pipes and prevents the pipes from overheating in any areas. This effect also prevents the formation of salt deposits on pipes.

In the future, the developed method will be considered on the example of using a regeneration unit for methanol saturated with water, with a capacity of 2 m ³ / h.

The evaporator consists of 16 heating vertical pipes with a diameter of 70 mm and a length of 1.5 m each. The heating pipes are placed in the cylindrical part of the heat pipe with a diameter of ~ 1.2 m and are located evenly on a circle with a diameter of ~ 800 mm. In the center of the heat pipe, a cylindrical pipe with a diameter of ~ 0.4 m is made, which serves as the lowering pipe of the evaporator. Steam from heating pipes enters this pipe. Below the lowering pipe and heating pipes are connected by a common collector. At the top, the heating pipes extend ~ 70 mm above the surface of the heat pipe. A removable grill is installed above the heating pipes to limit the entrainment of the droplet liquid.

50 pipes with a diameter of 70 mm and a length of ~ 1.75 m each protrude from the cylindrical part of the heat pipe into the combustion chamber (furnace). These pipes together with the upper part are united by a common cavity of the heat pipe, at least partially filled with a working fluid (working substance). Evaporating in the lower part of the heat pipe under the influence of the heat of the burners and condensing on the surface of the heating pipes, the working fluid transfers the heat necessary for the heating pipes. The closed circulation of the working substance is supported by the action of mass or capillary forces. Hatches are installed above the heating pipes in the installation casing. At the bottom of the collector, under the heating pipes, there is also a hatch. These hatches are designed to clean the inside of heating pipes. All elements are made of steel (preferably St20). The side surface of the heat pipe is covered with thermal insulation. The combustion chamber has an internal lining.

Claims (6)

1. A methanol recovery unit from a solution saturated with water, comprising a successively installed container for water-saturated methanol, a heat exchanger, an anti-scale device, a distillation column and a regenerated methanol collector, and also an evaporator installed with the possibility of supplying a gaseous medium heated to a temperature providing a temperature to a temperature ensuring separation of a mixture of methanol and water, characterized in that the evaporator is made in the form of at least one heat pipe in which is located enshey least one heating tube. 2. The block according to claim 1, characterized in that it contains more than one evaporator. 3. The block according to claim 1, characterized in that the evaporator containing more than one heating pipe is used. 4. The block according to claim 3, characterized in that the heating pipes in each evaporator are parallel to each other and uniformly in volume of the evaporator. 5. The block according to claim 1, characterized in that the total cross section of all the heating pipes in one evaporator is not more than 70% of the cross section of the evaporator. 6. The block according to claim 1, characterized in that a heat pipe is used with an aqueous solution of methanol as a working substance.

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