RU2115065C1 - Method and device for obtaining heated heat carrier - Google Patents

Abstract

FIELD: increase of temperature of raw material at inlet of hydrocarbon catalytic reforming reactor. SUBSTANCE: method of obtaining heated heat carrier includes catalytic flameless combustion of fuel in mixture with air; its amount exceeds stoichiometrically amount of fuel required for combustion by 3 to 10 times. Before feeding the fuel-and-air mixture for combustion, it is preliminarily preheated. Heat carrier formed after combustion of fuel is mainly directed for heating the raw material in course of reforming of hydrocarbons. Heating the fuel-and-air mixture before feeding it for combustion may be effected by part of used heat carrier; other part of heat carrier is connected with the aid of ejector with flow of heated fuel-and-air mixture which is again directed to combustion chamber. Relationship of flows of fuel-and-air mixture and part of used heat carrier connected in ejector ranges from 1:1.5 to 1:8. Device for obtaining heated heat carrier includes the following components connected in series by means of pipe lines: compressor, recuperative heat exchanger, ejector and combustion chamber with catalytic checker. Outlet of combustion chamber is connected with recuperative heat exchanger through heat recovery units (for example, heat exchanger is mounted for hydrocarbon reforming). Connecting pipe line between heat recovery unit and recuperative heat exchanger has branch pipe running to ejector. EFFECT: elevation of temperature of raw material at inlet of hydrocarbon catalytic reforming reactor. 5 cl, 1 dwg

Description

 The invention relates to the production of coolants, mainly in oil refining processes, and, in particular, can be used to increase the temperature of raw materials at the inlet to the catalytic reforming reactor of hydrocarbons.

 A known method of regulating the process of catalytic reforming of hydrocarbons, providing for before entering the reactor the heating of raw materials in a furnace with open burning of fuel [1]. The disadvantage of this method is the excessively high temperature that develops in the process of burning gas, which leads to the formation of undesirable harmful substances in the combustion products (coolant), for example, nitrogen oxides.

 A known method and device for heating oil reservoirs [2]. In the device lowered into the well, flameless combustion of the air-gas mixture on the catalyst and subsequent dilution of the combustion products of air to obtain the desired temperature before pumping the coolant into the formation are carried out. The disadvantage of this method is also the high temperature of gas combustion, leading to the formation of nitrogen oxides. Subsequent dilution with air to reduce the temperature of the coolant does not eliminate the already formed nitrogen oxides. In addition, when the ratios of fuel and oxidizer used are close to stoichiometric, the fuel, as a rule, does not burn out completely.

 The closest known analogues are the method and device for producing a heated working environment [3]. The method involves mixing fuel with air and water and then burning the resulting mixture on a catalyst in a combustion chamber. The presence of water in the combustible mixture lowers the process temperature and prevents the formation of nitrogen oxides. However, the use of an additional component significantly complicates the equipment used, and the presence of water vapor in the coolant creates a further problem of condensate collection and removal.

 These disadvantages of known processes and devices are largely eliminated by the invention.

 A method of producing a heated heat transfer medium according to the invention includes catalytic flameless combustion of fuel mixed with air, the amount of which exceeds 3-10 times the stoichiometrically necessary for burning fuel. The air-fuel mixture is preheated before being fed for combustion. Air in the proposed method performs the functions of an oxidizing agent and a cooling (diluting) non-combustible component. The coolant formed as a result of fuel combustion is sent for recycling, mainly for heating raw materials in the process of hydrocarbon reforming.

 The heating of the air-fuel mixture before feeding it for burning can be done with a part of the spent coolant. The other part of the coolant using an ejector is connected to the stream of heated air-fuel mixture and again sent to the combustion chamber.

 The ratio of the flows of the air-fuel mixture connected to the ejector and part of the spent coolant can be 1: 1.5 - 1: 8. The latter value is preferable, but its maintenance requires the use of particularly powerful compressors. In practice, the pressure in a mixture of fuel and air is up to 5 atmospheres, but may be higher.

 A device for producing a heated heat transfer medium includes a compressor, a recovery heat exchanger, an ejector, and a combustion chamber with a catalytic nozzle connected in series, the outlet of the combustion chamber being connected to a recovery heat exchanger through a heat exchanger (mainly representing the heat exchanger of a hydrocarbon reforming plant). The connecting pipe between the utilizer and the recovery heat exchanger has a branch to the ejector. Gaseous fuel also enters the described device through the ejector.

 The drawing shows a schematic diagram of the proposed device for producing a heated coolant, where 1 is a compressor; 2 - recovery heat exchanger; 3 - ejector; 4 - a combustion chamber with a catalytic nozzle; 5 - heat recovery unit; 6 - connecting pipe between the utilizer 5 and the recovery heat exchanger 3; 7 - a branch from the connecting pipe 6 to the ejector 3; 8 - exhaust discharge pipe.

 The operation of the device is illustrated by a specific example.

The air-fuel mixture in an amount of 600 kg / h by air and 5 kg / h by fuel is fed into the combustion chamber 4 with a catalytic nozzle of aluminum oxide coated with platinum group metals. The fuel is satellite gas, for the combustion of which a stoichiometric amount of air is approximately 15 kg per 1 kg of fuel. The heat utilizer 5 receives kg / h of coolant. The difference between the flow rates of the air-fuel mixture and the coolant occurs due to recirculation using the ejector 3 parts of the spent coolant. The temperature of the coolant at the outlet of the catalytic combustion chamber is 740 ^o C; the degree of fuel combustion - 99.7%. Nitrogen oxides and carbon monoxide are practically absent. Process control is carried out by changing fuel consumption. The transmitted power is 52 kW with a device efficiency of 78%.

Claims (5)

 1. A method of producing a heated coolant, including catalytic flameless burning of fuel mixed with air and an uncombustible component and subsequent supply of the resulting coolant for disposal, wherein the air-fuel mixture is heated by the resulting coolant before being supplied for combustion, characterized in that the non-combustible component is also air, the total amount which in a mixture with fuel exceeds the stoichiometrically necessary for fuel combustion by 3-10 times.  2. The method according to claim 1, characterized in that the mixture is heated by a part of the spent coolant, and the other part of the coolant is connected to the flow of the heated air-fuel mixture by means of an ejector and again sent to combustion.  3. The method according to claim 2, characterized in that the ratio of the flows of the air-fuel mixture connected to the ejector and the part of the spent coolant is 1: 1.5 to 8.0.  4. The method according to p. 1, characterized in that the pressure in the mixture of fuel and air is up to 5 atm.  5. A device for producing a heated heat transfer medium, comprising a compressor, a heat recovery heat exchanger and a combustion chamber with a catalytic nozzle connected in series, the output of the combustion chamber being connected to a heat recovery heat exchanger, characterized in that an ejector is installed between the heat recovery heat exchanger and the combustion chamber, and the output of the combustion chamber is connected to heat recovery heat exchanger through the heat exchanger, and the connecting pipe between the heat recovery heat exchanger and the heat exchanger and has a branch to the ejector.