RU2737991C1 - Burner device for commercial steam movable installation - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: invention relates to the field of power engineering. Burner device comprises a housing in the form of a steel cylinder with side openings, a gas header with a gas-dispensing assembly, a mounting tube for the igniter, a mounting tube for the photosensor and a mounting flange, wherein front part of housing is closed by concave plate, in which there are seven micro-torch burners - one pilot in center along axis of housing and six along circumference, passing through their axes, with installation angle of 15° to center, wherein each micro-torch burner comprises an axial swirler with straight blades installed at angle of 45°, in the center of which there is a gas nozzle with gas outlet holes, and the burner gas dispensing assembly consists of a gas supply pipe and seven gas supply tubes connected to the micro-torch burners.

EFFECT: invention allows improving operating reliability of the burner device, improving uniformity of fuel combustion in the absence of scale products and ecological indices.

1 cl, 3 dwg

Description

Technology area

The proposed invention mainly relates to the field of oil field and can be used in the composition of tools designed for dewaxing operations of wells, main and field pipelines, as well as for heating sections of ground communications. In addition, the proposed invention can find its application in the creation of mobile boiler houses for heating residential and industrial premises, for eliminating emergencies in the municipal services of cities and workers' settlements, for heating water supply and heating systems during their repair in winter, for cleaning the roadway, in including curbs, pipelines, sewage systems, as well as performing other work using hot water and steam.

State of the art

From the prior art, field steam mobile installations (PPUA) are known. PPUA units are designed for dewaxing of wells, main and field oil pipelines, as well as for heating sections of ground communications that were frozen in a temperate climate. They can also be used during the installation and dismantling of installations used for drilling wells, and for any other equipment that needs heating.

The reason for the formation of asphalt-resin-paraffin deposits is a change in the thermodynamic state of the medium due to the cooling of the gas-oil flow to a temperature lower than the temperature of oil saturation with paraffin, which results in the precipitation of a solid phase with the deposition of particles on the contacting surfaces of the equipment. Paraffinization of equipment can lead to reduced production rates, increased power consumption and equipment damage.

To eliminate the noted deposits, the prior art knows the use of a thermal method, in which the melting of paraffin deposits (for example, on the walls of wells) is carried out using hot high-pressure steam.

Since there is a need to move purification units from one reservoir to another, steam generation means are typically deployed on mobile platforms known as PPUAs.

The main element of the PPUA, directly responsible for the generation of steam, is a steam boiler with a burner located underneath it, which is in thermal contact with it.

As an illustration of the prior art, one can cite a solution known from patent RU 2183792 C1, 20.06.2002, which is a heater of a steam generator installation. In the known solution, the burner device is located in thermal contact with the steam generating means (Fig. 1 of the patent document). However, the known solution is not aimed at improving the design of the burner device.

In turn, existing mobile steam generating units (for example, PPUA-1600/100) are equipped with nozzle burners (Fig. 1 of the description of this application), containing: 1 - housing; 2,3 - nozzles; 4 - ignition device; 5 - glass; 6 - adjusting bolt; 7 - flame indicator; 8 - electromagnetic valve; 9 spark plug; 10 - nozzle; 11 - stabilizer; 12 - pipelines; 13 - guide; 14 - holder. These burners operate exclusively on diesel fuel, as a result of which they have a number of significant disadvantages, especially when they work at low temperatures.

These disadvantages include:

- low reliability of operation at low temperatures due to the filling of the heat exchanger cavity with diesel fuel. Subsequently, combustion occurs on the cold walls of the heat exchanger with intense carbon formation;

- the outflow of fuel from the nozzles occurs at an angle relative to the axis of the coil heat exchanger, as a result of which part of the atomized fuel falls on the cold walls of the heat exchanger and forms solid deposits, which significantly impede heat transfer from heated gases to water;

- poor mixing in the cavity of the heat exchanger of fuel and air, especially at low temperatures, which leads to a decrease in combustion intensity, increased chemical and mechanical underburning, deterioration of environmental indicators;

- low efficiency;

- high material consumption and design complexity.

With regard to the disadvantages noted, one can notice the linear arrangement of several nozzles of the known burner device, as a result of which the temperature field created by the torch is not uniform enough. Uneven combustion of the mixture can lead to the formation of toxic combustion products, i.e. degrades environmental performance.

The proposed invention is aimed at overcoming the known drawbacks of the prior art by improving the design of the burner used as part of the PPUA equipment and provides the achievement of the technical results presented in the following sections of the description.

Disclosure of invention

According to the invention, a burner device for a field steam installation is proposed, installed in thermal contact with a steam generation means, and comprising a body in the form of a steel cylinder with side windows, a gas manifold with a gas distributing unit, an installation pipe for an igniter, an installation pipe for a photosensor and an installation flange, while the front part of the body is closed by a concave plate, in which seven microflame burners are installed - one pilot in the center along the body axis and six along the circumference passing through their axes, with an installation angle of 15 ° to the center, and each microflame burner contains an axial swirler with straight blades set at an angle of 45 °, in the center of which there is a gas nozzle with gas outlet holes, and the gas distribution unit of the burner consists of a gas supply pipe and seven gas supply pipes connected to microflame burners.

For visual control of the flame, the burner is equipped with a peephole with quartz glass installed at the end.

The above set of essential features of the proposed invention makes it possible to achieve technical results, consisting in stable and safe ignition, increasing the reliability of the burner device and PPUA as a whole (without breakdowns and breakthroughs of the flame), improving the uniformity of fuel combustion in the absence of carbon deposits, improving environmental performance, increasing productivity and efficiency, reducing material consumption.

Implementation of the invention

This section of the description provides more detailed information in relation to the proposed invention, as well as the rationale for the possibility of achieving the above technical results.

It is known that combustion of crude oil or its heavy liquid fractions produces significant amounts of CO ₂ combustion products, as well as sulfur and nitrogen oxides. Therefore, any improvement in devices using such liquid fractions as fuel (for example, diesel fuel) cannot lead to a significant improvement in the environmental performance of such devices.

It is also known that natural gas is the cleanest of organic fuels, free of ash and sulfur compounds. Thus, ensuring the possibility of using natural gas in PPUA units will improve environmental performance. In addition, unlike diesel fuel, gas is less susceptible to the effect of low ambient temperatures on its flammability and requires less technically sophisticated equipment to use it.

However, it should be noted that nitrogen oxides are formed when all types of fuel are burned: from coal to natural gas. The parameters affecting the formation of nitrogen oxides are temperature, residence time of gases in the high temperature zone and the quality of mixing of fuel with an oxidizer. Consequently, there is a need to develop a design of a burner that can reduce the formation of nitrogen oxides during its use. In addition, the use of gas will ensure the absence of fuel carbon deposits on the internal surfaces of the boiler, which will allow to extend the overhaul period of its operation, reduce the period for performing routine maintenance and increase its reliability.

The basis of the proposed invention is based on the studies carried out in relation to the location of flares over the cross section of the working area and their influence on the combustion parameters and the quality of the fuel-air mixture.

Since the formation of nitrogen oxides is influenced by temperature, it will not be sufficient to provide an average low temperature in the combustion zone while maintaining local zones with an increased temperature (A. Dostiyarov, M. Tumanov, D. Umyshev. Study of the combustion rate of a small-scale turbulent flame // Industry of Kazakhstan . -2015. No. 4. p. 72-74).

A possible solution to this problem within the framework of the proposed invention is to reduce the formation time of the fuel-air mixture, which reduces the likelihood of the formation of local zones with a high fuel concentration and provides a short residence time of gases in the high temperature zone.

The explanatory drawing (Fig. 2) shows the design of the proposed burner device, according to the positions, containing:

10 - case with side windows; 20 - mounting flange; 30 - gas distribution unit; 40 - vortex microflame burner with swirler; 50 - installation pipe for the igniter; 60 - seat for spark plug; 70 - mounting tube for the photo sensor; 80 - peepers.

In an illustrative example, the burner operates as follows.

The ignition device is supplied with gas from the ignition gas line, ignition occurs with the help of a high-voltage discharge of the spark plug, which occurs when high voltage is supplied by the electronic ignition unit. Combustion of compressed natural gas (CH ₄ ) is preferred.

When the igniter is ignited, the photosensor detects the presence of a flame for 3 - 5 seconds, after which the automated control system (ACS) issues a signal to open the safety shut-off valves (SPS) on the gas pipeline from the cylinder installation.

Gas enters the burner through the minimum set gap of the control damper and is smoothly ignited by the pilot flame. With a time delay of 10 seconds and no signal is received from the photosensor to extinguish the flame, the solenoid valve on the ignition line closes, the igniter is turned off.

When the flame goes out, on the signal of the photosensor, the ACS with a delay of no more than 1 s issues a command to close all the shut-off valves, the burner and igniter are turned off. After ignition of the ACS burner by means of automatic regulation of the gas and air dampers according to an algorithm that takes into account the dependence of the gas-air pressure and the rate of rise of the steam temperature, it brings the setting to the nominal parameters of the operating mode set by the operator for no more than 20 minutes and maintains them for the required operating time at this mode. A quartz glass peephole at the end can be used by service personnel to safely monitor the flame.

The burner device, due to the smooth regulation of the automation system, ensures the maintenance of the required thermal power of the boiler when operating in two modes and in the second mode, additionally in two sub-modes:

1 mode - with a steam temperature of 164 ° C and a productivity of 1050 kg / h;

Mode 2 - with a steam temperature of 310 ° C and a productivity of 1600 kg / h;

sub-modes: with a steam temperature of 190 ° C (210 ° C) and a productivity of 1600 kg / h.

The working range of gas pressure in front of the burner is from 1.2 kPa to 10.5 kPa.

If it is necessary to reduce the time for the installation to reach the operating mode and generate steam with increased dryness, the gas pressure in front of the burner can be increased to 33 kPa with appropriate changes to the ACS control program.

The air is supplied to the combustion chamber by means of a high-pressure fan, the air flow control is automatically regulated by an air damper. The burner device is equipped with an ignition-protective device, an electronic ignition unit, a photo sensor, a peephole, an automobile spark plug.

Ignition, control and monitoring of the burner operation is carried out remotely from the cabin of the PPUA chassis using an ACS. It is also possible to start the installation and control parameters from the control panel installed in the box.

The ANSYS Fluent software (www.cadfem-cis.ru) was used to simulate the processes occurring during the implementation of the proposed design.

Using numerical modeling, the processes of fuel mixing in microflame burners were studied. It is known that various turbulence models are used to solve turbulent processes, in particular, it is possible to use the K-epsilon (k-ε) model (https://en.wikipedia.org/wiki/K-epsilon_turbulence_model).

The transport equation in this model is determined by the equations of turbulent kinetic energy k and the rate of dissipation of kinetic energy ε.

To increase the uniformity of the temperature distribution in the working zone, the distribution of microflame burners in the front part of the body is applied so that one of the burners is located in the center along the body axis. This micro-flare burner is assigned the function of a pilot (standby) burner, which serves to maintain the flame in the furnace during sudden load drops and prevent flame breakdown, increases the completeness of combustion with large excess air in the main burners, and reduces pulsating combustion. In this case, the other six microflame burners are evenly spaced on a circle passing through the axes of these burners. The angle of installation of the burners 15 ° to the center was chosen for reasons of reliable flame transfer from the pilot burner and optimal thermal contact with the coil heat exchanger, which acts as a means of generating steam.

According to the invention, each microflame burner is equipped with an axial swirler, which serves to create a rotational motion of air forced through the housing windows, together with the gas supplied to each of the burners through gas supply pipes. The angle of installation of the swirler blades is also essential, as will be shown below.

The boundary conditions at the air inlet were set by the temperature and flow rate. The boundary conditions at the fuel inlet were set by the mass flow rate and temperature. The exit from the simulation area was set by pressure. As a result of calculations, the temperature contours were obtained at different angles of the blades for swirling the flow.

The choice of the angle of installation of the inlet swirler blades affects the mixing quality of the fuel-air mixture and hydraulic losses in the burner.

It was found that when fuel is supplied and there is no swirling, a reverse flow zone exists in front of the distributing pipes, which creates additional resistance and reduces the flow rate. With an axial feed, the fuel moves along the walls by the swirling force given by the axial feed, the fuel has a wider contour. By installing a nozzle with gas outlets on the fuel supply tube, the fuel is mixed earlier than in the option without swirling.

The experimentally determined dependence of the drag coefficient ξ on the blade angle β, shown in Fig. 3 (the angle β is plotted along the X axis, the coefficient ξ is plotted along the Y axis), shows that at an angle greater than 50 °, hydraulic losses sharply increase, and at an angle of less than 30 °, turbulence in the chamber decreases and mixture formation worsens.

It has been determined that at an acute angle of installation of the swirling blades (30 °) at the inlet to the gas burner, the high temperature is in the zone of the fuel supply tube; therefore, part of the fuel is not used to heat the steam generating means, which reduces the efficiency of the installation. With an increase in the angle of installation, the uniformity of combustion of the mixture and the shift of the high temperature zone to the front part of the burner increase, however, at an angle approaching 60 °, although the uniformity of combustion of the mixture is maintained, the maximum temperature increases, reaching 2000 K, which leads to an undesirable active formation of oxides nitrogen.

The advantages of the proposed solution are that the burner is installed in the boiler furnace inside a pipe system with a heated medium and provides heating of the medium due to direct radiation of the torch and convection of flue gases; to prevent direct contact of the torch with the pipes, the burner has a concave plate with the installation of the main microburners at an angle of 15 ° to the center, thus, the torch is concentrated in the center and due to the good mixing of the gas-air flows of individual microburners (low gas flow rate and strong air swirl) it is short and does not touch the pipes.

In addition, all microburners have a separate shell with an axial swirler installed at an angle of 15 ° on the front concave plate and is a burner without preliminary mixing, therefore, the zone of maximum temperatures is shifted above both at the base of the plate and at the edges of the shells, the temperature does not exceed 6500 ° C, which acceptable for stainless steel.

Thus, in the proposed solution, the range of angles of installation of the swirler blades is determined, which is from 40 ° to 45 °, in which it is possible to achieve good mixture formation with minimal hydraulic losses, which improves the uniformity of fuel combustion, reduces the level of formation of nitrogen oxides, increases the productivity and efficiency of the burner. devices and installations of PPUA as a whole.

From the foregoing it follows that it is essential to achieve these results is the possibility of using natural gas in the installations of field steam mobile (in particular, PPUA-1600/100), the uniform installation of microflame burners in the front part of the burner device, the presence in each burner of an axial swirler with straight blades set at an angle of 45 °, in the center of which there is a gas nozzle with gas outlet holes.

Claims (2)

1. A burner device for the installation of a field steam mobile, installed in thermal contact with the steam generation means and containing a body in the form of a steel cylinder with side windows, a gas manifold with a gas distributing unit, an installation pipe for an igniter, an installation pipe for a photosensor and an installation flange, while the front part of the body is closed by a concave plate, in which seven microflame burners are installed - one pilot in the center along the body axis and six along a circumference passing through their axes, with an installation angle of 15 ° to the center, and each microflame burner contains an axial swirler with straight blades installed at an angle of 45 °, in the center of which there is a gas nozzle with gas outlet openings, and the gas distribution unit of the burner consists of a gas supply pipe and seven gas supply pipes connected to microflame burners. 2. The burner device according to claim 1, characterized in that it further comprises a peephole with quartz glass at the end.

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