A fuel injector lance, particularly for transporting and guaranteeing stable gaseous fuel delivery to combustion systems is designed to deliver gaseous fuel to the combustion process, where the fuel stream quantity is controlled by the amount of motive gas delivered to the injector.

The object of the invention is to provide a fuel lance, particularly an injector fuel lance designed to deliver fuel and air mixture to the combustion chamber, continuously and independently of the fuel pressure, applicable in industrial combustion systems, power boiler chambers, industrial furnaces and adiabatic combustion chambers.

Fuel lances designed to supply fuel to combustion systems, also in cases when the fuel pressure is insufficient to overcome flow resistance and ensure adequate parameters are known in the art (US 3441045 A, US 3441045 A). These lances have a coaxial pipe ending with a motive gas injector nozzle mounted in their body along the axis, and on the outer circumference of the pipe with a ring section fuel gas is sucked in, which after mixing with motive gas is transported via a coaxial pipe to the straight- through outlet nozzle located in the terminal part of the lance. The ejector pump presented in the patent description of patent US 7527481 , includes a housing with a bore along a first axis, a first radial passage from an outer surface of the housing to the bore defining a suction port, a bore defining an inlet port in the first part of the housing and an ejector piston mounted within the bore, the ejector piston having at least one radial passage along the second axis from the outer surface of the second housing to the nozzle, which spreads from the first bore to the second bore of the ejector piston.

The objective of the invention is to develop a new construction of a fuel injector lance, which will ensure continuous delivery of fuel to the combustion chamber under variable operating conditions of the combustion system, such as: temperature and pressure within the combustion chamber, pressure and temperature of fuel gas, ambient pressure and temperature, and physicochemical properties of the fuel.

The invention pertains to a fuel injector lance, particularly for transporting and guaranteeing stable gaseous fuel delivery to combustion systems, where the motive gas injector nozzles are located peripherally on the mixing chamber at an angle of (12 - 30)° to the longitudinal axis of the mixing chamber, preferably at a distance smaller or equal to half of the diameter of the mixing chamber, which is connected from the inflow side with a supply pipe through a convergent channel, and from the outlet side it is connected through a divergent channel with a delivery pipe ending with an outlet nozzle.

It is preferred when the lateral wall of a roller cylinder of the mixing chamber, and the conical lateral walls of the convergent and divergent chamber are equipped on the outside with a jacket, between which there is a motive gas pressure chamber with a connecting pipe, with a longitudinal axis placed perpendicularly to the longitudinal axis of the fuel injector lance.

According to the invention, the motive gas nozzles are mounted in the lateral wall of the motive gas mixing chamber and fuel transported, with axes placed at a suitable angle to the fuel lance axis, preferably at an angle of 15 to 20 degrees. The mixing chamber has the shape of a cylinder with a length equal to at least double of the determined diameter. The location of the motive gas nozzle is in a certain distance to the mixing chamber inlet, preferably equal to half of the chamber diameter. The mixing chamber is connected from the fuel gas inlet via a channel in the shape of a truncated cone with the cylindrical pipe where the hopper-shaped channel has a length equal to the diameter of the mixing channel. From the outlet side, the channel connecting the mixing chamber, ending with a straight-through orifice, with the lance delivery part has the shape of a truncated cone expanding towards the outlet. The delivery part of the lance comprises a cylindrical channel with a longitudinal axis that overlaps with the mixing chamber's axis. The lance ends with a fuel nozzle placed centrically in the coaxial pipe. The nozzles end with a straight-through orifice with the axis overlapping with the axis of the delivery pipe and mixer axis. In an embodiment of the invention, the longitudinal axis of the nozzle can be placed at an adequate angle to the longitudinal axis of the transport channel.

The fuel injector lance according to the invention is characterized by a simple construction and lack of complex elements, and therefore, its production is easy and product costs are low. The innovative solution in the proposed invention is the absence in the mixing chamber of an element injector in the form of coaxial pipe or nozzles. This solution allows the fuel lance to be used also for fuels containing tar compounds or organic impurities without the risk of their condensation inside the burner. This condensation can lead to a change in the cross-section of the mixer, thereby, reducing the supply of fuel to the outlet nozzle. Given the simplicity of the construction, the injector is characterized by wide range of work stability and small sensitivity to variable pressure inside the combustion chamber, which translates into the stability of the combustion process being carried out.

This lance can constitute an autonomous part of systems delivering fuel gas or other gases to technological processes.

The fuel injector lance comprises: supply pipe 1 , accelerating channel 2, mixer chamber 3 with injector nozzles 4, expansion channel 5, motive gas intake pressure chamber 6 connecting pipe 7 and delivery pipe 8 with outlet nozzles 9. The supply pipe 1 , accelerating channel 2, mixer chamber 3, expansion channel 5, delivery pipe 8 are located along the same longitudinal axis of the body of the fuel injector lance.

The length of the cylindrical delivery pipe 8 ending with an outlet nozzle 9 is adapted to the combustion system. The cylindrical delivery pipe and the nozzle, depending on needs, can be made from different materials, from carbon steels, alloy steels, various metal alloys to heat-resistant steels. The possibility of using different types of materials for making this element, allows to use the fuel injector lance at a wide range of temperatures and environments, from neutral, strongly oxidizing to aggressive environments. An adequate quantity of the delivered fuel is achieved by injecting the pre-set quantity of motive gas to the injector's mixing chamber 3, where the motive gas stream velocity generates an underpressure, which makes it possible to overcome resistances in the fuel gas delivery system, as well as in the fuel lance itself. Motive gas is delivered with supersonic speed via the nozzles 4 where the axes are arranged at an adequate angle to the longitudinal axis of the mixer. Motive gas is delivered to the nozzles from the pressure collector 6 supplied from the high-pressure system via the cylindrical intake connecting pipe 7, with its axis located perpendicularly to the longitudinal axis of the mixer. The quantity of the sucked motive gas is regulated by a stream of motive gas mass, countered by the pressure in the intake connecting pipe. An adequate angle of the motive gas nozzles causes that the process of mixing fuel gas and motive gas takes place in the injector mixer 3. Due to the low velocity of the gaseous fuel in the cylindrical inlet channel 1 before the inlet to the injector's mixing chamber, a flow channel with a decreasing cross-section was installed 2. The installation of this channel causes the potential energy of fuel gas to change into kinetic energy. This improves the process of mixing fuel gas with motive gas streams supplied through the nozzles 4 in the mixer chamber. This procedure causes that at the inlet to the flow channel with an increasing cross-section 5 a uniform mixture of fuel gas and transported gas is achieved. The task of the cone-shaped channel 5 is to connect the injector mixer with the cylindrical delivery pipe of the lance 8. The velocity of the stream of fuel gas and motive gas mixture is reduced at the expense of increasing of the gas static pressure. Increasing pressure is required to overcome resistances of the fuel gas - motive gas mixture flow through the lance's delivery pipe 8 and outlet nozzle 9 while maintaining appropriate operating parameters. The length of the cylindrical delivery pipe is adapted to the combustion system. The axis of the outlet nozzle 9 can overlap with the axis of the fuel injector lance or, in a patent variation, the longitudinal axis of the nozzle can be placed at a suitable angle to create desired aerodynamic phenomena in the combustion chamber.

The invention in one embodiment is described in drawings where fig.1 presents the fuel injector lance in a perspective view, fig.2 presents the cross-section of the fuel injector lance showing specific elements of the lance construction, fig.3 presents the cross-section A-A of the fuel injector lance showing the injector's mixing chamber and injector nozzles, fig. 4 presents a fragment of the nozzle element and fig. 5 presents the nozzle injector.

Motive gas is delivered to the mixer of the fuel injector lance proportionally to the quantity of fuel gas. This proportion depends on the composition of the motive gas, temperature of the motive gas, composition of the fuel gas, and temperature and pressure of the fuel gas. The proportion of motive gas to fuel gas may range from 0.1 to 2.0 preferably from 0.3 to 1.0.

The mechanism of action of the fuel injector lance is as follows (fig.4): fuel gas (i) is delivered via the supply pipe 1 to the convergent channel 2 at a speed ranging from a few to a dozen or so m/s. In the channel with the decreasing section, the flow rate of the fuel gas (i) increases, so that the achieved velocity at the inlet to the injector's mixing chamber ranges from a dozen or so to several dozen m/s. Fuel gas is transported by generating adequate underpressure at the inlet to the injector's mixing chamber 3. Motive gas (ii) is delivered to the mixing chamber by the injector nozzles 4 at a supersonic speed. In the injector mixer, the motive gas (ii) is mixed with the fuel gas (i). The location of the nozzles injecting the motive gas ensures uniform mixing of the fuel gas and motive gas. The velocity of the fuel gas-motive gas mixture (iii) in the mixer's outlet section ranges from several dozen to even one hundred m/s. The velocity of the motive gas- fuel gas mixture (iii) is reduced in the divergent channel 5 to a value measured along the longitudinal axis of the fuel injector lance amounting to several dozen m/s. Conversion of dynamic pressure to static pressure at the outlet from the convergent channel causes the pressure at the inlet to the delivery pipe 8 to reach a value sufficient to overcome the resistances of the flow through the delivery pipe and the outlet nozzle 9 while maintaining an adequate outlet speed ranging from 40 to 150 m/s, preferably between 90 to 120 m/s. An increase in the pressure achieved in the inlet section of the convergent channel 2 and the outlet section of the divergent channel 5 results from the balance of mass, energy and velocity of the motive gas (ii) and fuel gas (i) streams, as well as energy losses in the convergent channel at the inlet to the mixer and the divergent channel as the mixer outlet.