RU2772354C1 - Displacement compressor cooling method - Google Patents

Abstract

FIELD: refrigeration equipment.

SUBSTANCE: invention relates to methods for cooling displacement compressors and can be used in the operation of refrigeration equipment, as well as gas liquefaction equipment. According to the method, primary substances that are chemically inert with respect to the compressible gas are fed into the working cavity. As primary substances, a mixture of the gaseous phase CH₃-CHO with the liquid phase H₂O is fed into the working cavity, which enter into an endothermic reaction in the presence of an Ag catalyst previously placed in the working cavity of the compressor, and the products of the endothermic reaction are removed through a pipeline to the receiver.

EFFECT: invention is aimed at increasing the efficiency of the heat sink during the operation of the compressor.

1 cl, 1 dwg

Description

The technical field to which the invention belongs

The invention relates to methods for cooling volumetric compressors and can be used in the operation of refrigeration equipment, as well as equipment for gas liquefaction.

State of the art

The positive displacement compressor is a rotary mechanism designed primarily to compress the gaseous phase of a substance and transfer the compressed gas to subsequent units of complex equipment. The compressible gas can be a refrigerant in refrigeration equipment or an inert gas. In the process of compressing the working gas, thermal energy is released, which is transferred to the compressor structure. With an insufficient level of heat removal during gas compression, the likelihood of overheating of the compressor elements increases and, as a result, its premature wear and failure.

A known method of cooling a screw compressor due to air blowing of its housing from the description of patent RU 2131047. However, this method requires high energy costs with low cooling efficiency.

There is also known a method of using a water cooling jacket from the description of patent RU 2429378. The disadvantages of this method include insufficient cooling efficiency due to heat removal only from the surface of the screw compressor housing.

It is known to use a method for cooling the internal cavities of the compressor, which consists in injecting oil into the working cavity of the compressor and on the movable rotary screw elements of the compressor [Sakun I.A. Screw compressors: Fundamentals of theory, calculation, design / I.A. Sakun, Dr. tech. Sciences prof. - 2nd ed., revised. and additional - Leningrad: Mashinostroenie, 1970. - 400 p.]. However, for this type of compressors, there is a need to use oil pumps, filters, oil separators, etc., which prevent contamination of the compressed substance, which increases the labor costs and dimensions of the compressor with associated cleaning units.

In addition to solving the problem of overheating of the working elements of a screw compressor, it is necessary to ensure the most efficient operation of the compressor when compressing gases. It is known that in order to prevent deterioration of the quality indicators of the compressor, it is necessary to stabilize the temperature inside it and bring the process of inert gas compression in the compressor chamber closer to isothermal, since the compression work decreases during the isothermal process, as a result of which energy costs are reduced. One way to maintain a constant temperature inside the chamber of a screw compressor while cooling it is to use the endothermic effects of chemical reactions.

So known is the method of cooling according to the patent SU 1629613, including the supply of a cooling liquid (in a particular implementation - water) into the working cavity of a screw compressor with the addition of a solid component - a crystalline salt (in a particular implementation - a salt of NaCO ₃ * 10H ₂ O), entering into endothermic reaction with the coolant in the working cavity of the screw compressor.

However, the rate of dissolution of salt crystals in water is insufficient to achieve an effective endothermic reaction with rapid compression of gases, as a result of which it becomes impossible to ensure the efficiency of the screw compressor.

Closest to the claimed is the method of cooling according to patent RU 2158381, which includes feeding into the working cavity of the screw compressor a mixture of gases that are chemically inert with respect to the compressed gas, which enter into an endothermic reaction with each other in the presence of a catalyst. This makes it possible to reduce the energy consumption for compression, make it possible to compress the gas to higher pressures without the use of additional stages, and increase the rate of the endothermic reaction. In a particular implementation of the method, C ₂ H ₄ and O ₂ are used as gases in the mixture in a ratio of 1:1, respectively, according to the chemical reaction equation

C ₂ H ₄ +O ₂ \u003d CH ₂ - CH ₂ , silver is used as a catalyst.

The disadvantages of the compressor cooling method according to patent RU 2158381 include the fact that the endothermic reaction of gases takes away an insufficient amount of heat (about 35 kJ) to carry out the endothermic reaction, which reduces the cooling effect.

Unlike the closest analogue in the claimed method, the use of a mixture of liquid and gaseous substances allows you to take more (83 kJ) amount of heat with the same amount of substance, since the heat transfer of the liquid is an order of magnitude greater than the gas. In addition, in the proposed method, the gas increases the contact surface of the reactants, and the introduction of silver, as a chemical reaction reagent, increases the heat transfer rate.

Disclosure of invention

The objective of the invention is to improve the method of cooling a positive displacement compressor, which makes it possible to increase the efficiency of its operation when compressing gases.

The technical result consists in increasing the efficiency of heat removal during operation of a volumetric compressor due to the occurrence of an endothermic reaction with heat absorption of 160-190 J per mole and achieving a constant temperature inside the working cavity of the compressor within the equipment error.

The technical result is achieved due to the fact that primary substances that are chemically inert with respect to the compressible gas are fed into the working cavity, entering into an endothermic reaction, and the products of the endothermic reaction are removed through the pipeline to the receiver, while a mixture of the gaseous phase is fed into the working cavity as primary substances CH ₃ -CHO with a liquid phase of H ₂ O, entering into an endothermic reaction with each other in the presence of an Ag catalyst previously placed in the working cavity of the compressor in a ratio of 1:1:2, respectively, according to the chemical reaction equation

Also, the supply of primary substances into the working cavity is carried out by injection.

Brief description of the drawings

The claimed technical solution is illustrated by the drawing, which shows the installation of the compressor, which is a private implementation of the claimed method of cooling the screw compressor. The positions in the drawing indicate: 1 - dispenser, 2 - pipeline for supplying inert gas, 3 - pipeline for removing coolant, 4 - second thermometer, 5 - pipeline for supplying the liquid phase of H ₂ O, 6 - pipeline for supplying the gaseous phase of CH ₃ -CHO, 7 - the first thermometer.

Implementation of the invention

,

и Ag в количестве 1 моль в соотношении соответственно 1: 1: 2 согласно уравнению химической реакции:The inventive method is carried out during the operation of the compressor to compress the inert gas supplied through pipeline 2. Through pipelines 6 and 5, primary substances are supplied separately - the gaseous phase of substance "A" and the liquid phase of substance "B". In a particular implementation of the proposed method, acetaldehyde CH gas acts as substance "A"₃-CHO, and water H acts as substance "B"₂O. Substances are fed into the dispenser tank 1 leading to the working cavity of the compressor, resulting in a mixture acetaldehyde in water.The mixture is fed into the working cavity of the compressor. The most preferred option for supplying the mixture is injection. Beforehand, a catalyst is placed in the working cavity of the compressor, in particular, it is a Ag silver plate placed on the working elements of the compressor, on the compressor cover or on the compressor screws. The amount of substances "A", "B" and the catalyst is selected from the ratio 1:1:2. When interacting

,

and Ag in an amount of 1 mol in a ratio of 1: 1: 2, respectively, according to the chemical reaction equation:

(1)

(one)

186 kJ of heat is absorbed. The flow of the mixture into the working cavity is controlled by an actuator depending on the temperature measured by the first thermometer 7 and the second thermometer 4. In this case, the temperature values on the thermometer 7 and 4 must match within the measurement error. A mixture of substances and an inert compressible gas are mixed in the working cavity. In the presence of a catalyst, with an increase in pressure, an endothermic reaction of the mixture occurs, and as a result, the compressor structure is cooled. The compressed inert gas and the product of the endothermic reaction, which in particular is a liquid phase of C ₂ H ₅ OH alcohol, are removed through pipeline 3. The coolant - C ₂ H ₅ OH alcohol is sent through the liquid separator to the receiver, and the compressed inert gas is sent further along the cycle of operation of complex equipment associated with a screw compressor.

The organization of an endothermic reaction in the working cavity of a screw compressor makes it possible to bring the inert gas compression process closer to an isothermal one with a deviation of ± 5% and provide the most efficient cooling of the compressible inert gas, in comparison with the closest analogue due to greater heat absorption with the same amount of reagents and with more speed.

An example of the implementation of the proposed method

и жидкость

), химически инертные по отношению к сжимаемому газу (воздуху) при нормальных условиях, подавали по трубопроводам винтового компрессора в дозатор 1. Пластину серебра Ag предварительно установили на крышке винтового компрессора. Массу CH₃-CHO, H₂O и Ag выбирали из соотношения 1:1:2 соответственно согласно. В процессе осуществления способа сжимаемый воздух по трубопроводу подавали в рабочую полость при давлении P₁=0,1 МПа и температуре t₁=20°C. После отсечки рабочей полости от окна всасывания в нее по трубопроводу подавали первичные вещества (

и

) в виде смеси, приготовленной в дозаторе. При сжатии воздуха от давления P₁=0,1 МПа до давления P₂=0,5 МПа выделилось количество теплоты, равное 186 кДж. В рабочей полости реагенты

,

и Ag вступили между собой в эндотермическую реакцию. В процессе протекания эндотермической реакции реагентов поглотилось количество теплоты 186 кДж в расчете на 1 моль

. Таким образом от сжимаемого воздуха полностью была отведена теплота сжатия и, вследствие этого, температура сжатого воздуха на выходе из КМ (t₂) была равна температуре воздуха на входе в КМ, т.е. t₁=t₂=20°C, что позволило говорить о создании политропного (изотермического) процесса сжатия с показателем политропы n=1. После выхода из винтового компрессора смесь охлажденного сжатого воздуха и продукта эндотермической реакции - раствора

в воде - поступила в отделитель жидкости, в котором охлажденный сжатый воздух был отделен и поступил к потребителю, а раствор

поступил в сборную емкость для дальнейшего использования.In laboratory conditions, the claimed method was carried out. As a volumetric compressor, an ALMIG VARIABLE-150-8 screw compressor with a volumetric capacity of 25 m3/min wet compression was used. Primary substances (gas

and liquid

), chemically inert with respect to the compressible gas (air) under normal conditions, was supplied through the pipelines of the screw compressor to the dispenser 1. The Ag silver plate was previously installed on the cover of the screw compressor. The mass of CH ₃ -CHO, H ₂ O and Ag was chosen from a ratio of 1:1:2, respectively, according to. During the implementation of the method, compressed air was supplied through the pipeline into the working cavity at a pressure P ₁ =0.1 MPa and a temperature t ₁ =20°C. After cutting off the working cavity from the suction window, primary substances were fed into it through the pipeline (

and

) in the form of a mixture prepared in a dispenser. When air is compressed from pressure P ₁ =0.1 MPa to pressure P ₂ =0.5 MPa, an amount of heat equal to 186 kJ is released. Reagents in the working cavity

,

and Ag enter into an endothermic reaction with each other. During the course of the endothermic reaction of the reactants, the amount of heat 186 kJ per 1 mole was absorbed

. Thus, the heat of compression was completely removed from the compressed air and, as a result, the compressed air temperature at the CM outlet (t ₂ ) was equal to the air temperature at the CM inlet, i.e. t ₁ =t ₂ =20°C, which made it possible to speak about the creation of a polytropic (isothermal) compression process with a polytropic index n=1. After leaving the screw compressor, the mixture of cooled compressed air and endothermic reaction product - solution

in water - entered the liquid separator, in which the cooled compressed air was separated and supplied to the consumer, and the solution

entered the collection tank for further use.

Claims (3)

1. A method for cooling a volumetric compressor, which consists in the fact that chemically inert with respect to the compressible gas primary substances that enter into an endothermic reaction are fed into the working cavity and the products of the endothermic reaction are removed through a pipeline to a receiver, characterized in that a mixture of the gaseous phase CH is fed into the working cavity as primary substances₃-CHO with liquid phase H₂O entering into an endothermic reaction with each other in the presence of an Ag catalyst previously placed in the working cavity of the compressor in a ratio of 1:1:2, respectively, according to the chemical reaction equation

. 2. The method according to claim 1, characterized in that the supply of primary substances into the working cavity is carried out by injection.

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