Combustor with primary and secondary swirl premixing chamber

Abstract

A kind of burner with main and auxiliary cyclone premixing chamber, the wall of main cyclone premixing chamber is formed with main cyclone premixing chamber and airflow scaling outlet flow passage, the upper portion of the wall of main cyclone premixing chamber is provided with main gas inlet pipe, the lower portion of the wall of main cyclone premixing chamber is provided with main air inlet pipe, the inner side air guide pipe of air distribution ring channel, the top of main cyclone premixing chamber is provided with auxiliary cyclone premixing chamber, the wall of auxiliary cyclone premixing chamber is provided with auxiliary gas inlet pipe and auxiliary air inlet pipe which are communicated with auxiliary cyclone premixing chamber, the auxiliary gas inlet pipe and auxiliary air inlet pipe are respectively communicated with auxiliary gas outlet pipe and auxiliary air outlet pipe, the auxiliary gas outlet pipe and auxiliary air outlet pipe are respectively communicated with gas inlet main pipe and air inlet main pipe;The design of the present application is scientific and reasonable, which can realize complete, sufficient, uniform and stable premixing combustion, and can effectively control and guarantee the smooth progress of premixing combustion process, realize effective adjustment and control of combustion condition, and has significant social and economic benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to a gas fuel combustion device, in particular to a burner with a main and auxiliary swirl premixing chamber. BACKGROUND

[0002] For the gas fuel combustion device (burner) used in various industrial furnaces, it is a current urgent and realistic task to improve the sufficient and uniform premixing of air and fuel gas to achieve efficient and complete combustion in the combustion chamber (sufficient and uniform premixed combustion). However, the sufficient premixed combustion of gas fuel has normal preheating combustion in the burner, or non-normal premixed combustion (backfire and misfire, or deflagration, etc.) in the burner. This brings challenges to the design and manufacture of premixed burners, and also puts forward more stringent requirements for operation and management. Despite this, the damage of the burner caused by improper design of the burner, and then the performance decline and damage of the heat utilization equipment, have become very common burner failures and accidents. Since the burner damage often occurs during normal operation of the equipment, the damage caused by non-normal combustion of the burner is more serious. For this reason, the premixed burner is always very cautious in large heat utilization equipment, and more often uses diffusion combustion or semi-premixed combustion to complete the gas fuel combustion process. However, at present, energy saving and low-nitrogen combustion have become a trend, and the combustion device must achieve sufficient and complete premixed combustion. Therefore, on the basis of sufficient research and follow-up verification of the combustion characteristics of gas fuel, a burner with a main and auxiliary swirl premixing chamber is proposed. SUMMARY

[0003] In view of the above situation, in order to overcome the defects of the prior art, the purpose of the present application is to provide a burner with a main and auxiliary swirl premixing chamber, which can effectively solve the problems of instability, uncertainty and uncontrollability of the gas fuel combustion process of the existing burner, and it is difficult to realize the true premixed combustion.

[0004] To achieve the above object, the technical scheme of the present application is a burner with main and auxiliary cyclone premixing chambers, which comprises a bell-shaped main cyclone premixing chamber wall, a main cyclone premixing chamber with a mushroom-shaped cross section is formed in the main cyclone premixing chamber wall, and a lower air flow converging outlet flow channel with a converging cross section is formed in the lower part of the main cyclone premixing chamber wall; a main gas inlet pipe is arranged on the upper part of the main cyclone premixing chamber wall, which is led from a main gas inlet main pipe through a main gas regulating valve, and is connected to a gas distribution ring channel arranged in the main cyclone premixing chamber wall; a plurality of circumferentially distributed and horizontally inclined gas injection ports are arranged on the inner side of the gas distribution ring channel and are connected to the main cyclone premixing chamber; a main air inlet pipe is arranged on the lower part of the main cyclone premixing chamber wall, which is led from an air inlet main pipe through a main air regulating valve, and is connected to an air distribution ring channel arranged in the main cyclone premixing chamber wall; a plurality of circumferentially distributed and vertically upward air guide pipes are arranged on the inner side of the air distribution ring channel and are connected to the main cyclone premixing chamber; a plurality of horizontally inclined air injection ports are arranged on the upper part of the air guide pipes and are connected to the main cyclone premixing chamber; the air injection ports and the gas injection ports are arranged in a staggered manner in the horizontal direction and are arranged in the same direction in the vertical direction.

[0005] A mushroom-shaped auxiliary cyclone premixing chamber is arranged on the top of the main cyclone premixing chamber, and a flow guide premixing ring groove with a circular arc-shaped cross section is arranged on the lower part of the ball top of the auxiliary cyclone premixing chamber; an auxiliary premixing gas injection port is arranged on the lower part of the auxiliary cyclone premixing chamber and is connected to the main cyclone premixing chamber; an auxiliary gas inlet pipe and an auxiliary air inlet pipe are arranged on the auxiliary cyclone premixing chamber wall and are connected to the flow guide premixing ring groove in a direction symmetrical to the rotation cutting direction of the flow guide premixing ring groove; the auxiliary gas inlet pipe and the auxiliary air inlet pipe are connected to an auxiliary gas outlet pipe and an auxiliary air outlet pipe through an auxiliary gas regulating valve and an auxiliary air regulating valve, respectively; the auxiliary gas outlet pipe and the auxiliary air outlet pipe are connected to the gas inlet main pipe and the air inlet main pipe, respectively; a flow regulating pipe is inserted into the top of the auxiliary cyclone premixing chamber, and a flow regulating gas injection port is arranged in the auxiliary premixing gas injection port.

[0006] The present application has a scientific and reasonable design, can realize complete, sufficient, uniform and stable premixing combustion, can effectively control and protect the smooth progress of the premixing combustion process, can effectively regulate and control the combustion working condition, and has significant social and economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is the main sectional view of the structure of the present application.

[0008] Figure 2 is the A-A sectional view in the present application. Figure 1

[0009] Figure 3 is the B-B sectional view in the present application. Figure 1

[0010] ​​Legend: 1 main swirl premixing chamber wall, 1-1 main swirl premixing chamber, 1-2 airflow zooming outlet flow channel, 2 auxiliary swirl premixing chamber wall, 2-1 auxiliary swirl premixing chamber, 2-2 flow guiding premixing ring groove, 2-3 auxiliary premixing gas spouting outlet, 2-4 auxiliary coal gas inlet pipe, 2-5 auxiliary air inlet pipe, 2-6 auxiliary coal gas outlet pipe, 2-7 auxiliary air outlet pipe, 2-8 auxiliary coal gas regulating valve, 2-9 auxiliary air regulating valve, 2-10 regulating gas flow inlet pipe, 2-11 regulating gas flow spouting outlet, 3 coal gas inlet main pipe, 3-1 main coal gas inlet pipe, 3-2 coal gas distribution ring channel, 3-3 coal gas spouting outlet, 3-4 main coal gas regulating valve, 4 air inlet main pipe, 4-1 main air inlet pipe, 4-2 air distribution ring channel, 4-3 air spouting outlet, 4-4 air flow guiding pipe, 4-5 main air regulating valve. Embodiment

[0011] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings and specific cases.

[0012] With reference to the accompanying drawings, a burner with main and auxiliary swirl premixing chambers comprises a bell-shaped main swirl premixing chamber wall, the main swirl premixing chamber wall 1 is internally formed with a main swirl premixing chamber 1-1 with a mushroom-shaped cross section and a lower airflow zooming outlet flow channel 1-2 with a zooming-shaped cross section, the upper part of the main swirl premixing chamber wall 1 is provided with a main coal gas inlet pipe 3-1 led from a coal gas inlet main pipe 3 through a main coal gas regulating valve 3-4, which is in communication with a coal gas distribution ring channel 3-2 arranged in the main swirl premixing chamber wall 1, the inner side of the coal gas distribution ring channel 3-2 is provided with a plurality of circumferentially-distributed and horizontally-inclined coal gas spouting outlets 3-3 in communication with the main swirl premixing chamber 1-1; similarly, the lower part of the main swirl premixing chamber wall 1 is provided with a main air inlet pipe 4-1 led from an air inlet main pipe 4 through a main air regulating valve 4-5, which is in communication with an air distribution ring channel 4-2 arranged in the main swirl premixing chamber wall 1, the inner side of the air distribution ring channel 4-2 is provided with a plurality of circumferentially-distributed and vertically-upward air flow guiding pipes 4-4 in communication therewith, the upper part of the air flow guiding pipes 4-4 is provided with a plurality of horizontally-inclined air spouting outlets 4-3 in communication with the main swirl premixing chamber 1-1; wherein the air spouting outlets 4-3 and the coal gas spouting outlets 3-3 are arranged in a staggered manner in the horizontal direction and in a consistent manner in the vertical direction.

[0013] The top of the main rotational flow premixing chamber 1-1 is provided with an auxiliary rotational flow premixing chamber 2-1 in the shape of an inverted bottle with a cross section, which is formed by an auxiliary rotational flow premixing chamber wall 2, and a flow guide premixing ring groove 2-2 in the shape of a circular arc at the lower part of the ball top, and an auxiliary premixing gas outlet 2-3 which is in communication with the main rotational flow premixing chamber 1-1 at the lower part; the auxiliary rotational flow premixing chamber wall 2 is symmetrically provided with an auxiliary coal gas inlet pipe 2-4 and an auxiliary air inlet pipe 2-5 which are in communication with the flow guide premixing ring groove 2-2 in the direction of rotational cutting, the auxiliary coal gas inlet pipe 2-4 and the auxiliary air inlet pipe 2-5 are in communication with an auxiliary coal gas leading pipe 2-6 and an auxiliary air leading pipe 2-7 through an auxiliary coal gas regulating valve 2-8 and an auxiliary air regulating valve 2-9 respectively, and the auxiliary coal gas leading pipe 2-6 and the auxiliary air leading pipe 2-7 are in communication with a coal gas inlet main pipe 3 and an air inlet main pipe 4 respectively; a regulating gas flow leading pipe 2-10 is inserted into the top of the auxiliary rotational flow premixing chamber 2-1, and a regulating gas flow outlet 2-11 of the regulating gas flow leading pipe 2-10 is located in the auxiliary premixing gas outlet 2-3.

[0014] In order to ensure better implementation effect, the main rotational flow premixing chamber wall 1 is a bell-shaped structure which is formed by a steel structure shell and an inner layer of high-temperature-resistant and fire-resistant material, and the internal structure is the main rotational flow premixing chamber 1-1.

[0015] The main rotational flow premixing chamber wall 1 is formed by a heavy refractory brick layer, a light refractory brick layer, a ceramic fiber felt layer and a steel shell from inside to outside, and the inner surface of the steel shell is sprayed with a 50mm-thick fire-resistant spraying layer to improve the rigidity of the steel shell; the heavy refractory brick layer of the inner layer is made of fire-resistant material with strong thermal shock resistance, high load softening temperature and low deformation rate to maintain the firmness and stability of the main rotational flow premixing chamber wall 1 under high temperature and large temperature difference; the ceramic fiber felt layer has the functions of adjusting the structure size and heat preservation; the auxiliary rotational flow premixing chamber wall 2 has the same masonry structure as the main rotational flow premixing chamber wall 1.

[0016] The coal gas outlet 3-3 and the air outlet 4-3 are a plurality of one-way horizontal inclined gas flow channels which are alternately and uniformly distributed in the horizontal direction and are arranged in multiple layers in the vertical direction, and each of the layers has at least three layers; the inlet end of the coal gas outlet 3-3 is vertically connected to the inner wall of a coal gas distribution ring channel 3-2, and the outlet end is horizontally inclined to communicate with the outer wall of the main rotational flow premixing chamber 1-1, the inclination angle is 15°-45°, and the cross section is in the shape of a gradually converging nozzle; the inlet end of the air outlet 4-3 is vertically connected to an air flow guide pipe 4-4, the air flow guide pipe 4-4 is bent upward after the air flow guide pipe 4-4 reaches an air distribution ring channel 4-2 to communicate with the air distribution ring channel 4-2, and the outlet end of the air outlet 4-3 is horizontally inclined to communicate with the outer wall of the main rotational flow premixing chamber 1-1, the inclination angle is 15°-45°, and the cross section is in the shape of a gradually converging nozzle; the uniformly distributed and staggered and multi-layer combined outlet structure of the coal gas outlet 3-3 and the air outlet 4-3 can achieve sufficient and uniform rotational flow premixing of air and coal gas.

[0017] The auxiliary cyclone premixing chamber wall 2 is provided with an auxiliary coal gas inlet pipe 2-4 and an auxiliary air inlet pipe 2-5 which are connected to the ring groove 2-2 and are symmetrical to the direction of rotation, forming a strong cyclone premixing adjusting gas flow, the direction of which is consistent with the direction of the empty coal gas cyclone flow in the main cyclone premixing chamber 1-1; the premixing state of the cyclone premixing adjusting gas flow is determined by the opening degree of the auxiliary coal gas adjusting valve 2-8 and the auxiliary air adjusting valve 2-9; the auxiliary premixing gas outlet 2-3 is gradually expanded when connected to the top of the main cyclone premixing chamber 1-1, and is gradually changed from a contraction channel to an expansion channel, so as to form a cyclone divergent jet flow to affect the main cyclone premixing gas flow.

[0018] The regulating gas flow inlet pipe 2-10 is circular and made of heat-resistant steel pipe, the lower end of which is gradually contracted to form a regulating gas flow outlet 2-11 and is arranged at the center of the auxiliary premixing gas outlet 2-3. Since the regulating gas flow is a high-pressure gas flow, the center arrangement of the regulating gas flow outlet 2-11 has a more prominent regulating effect, especially in the process of stopping combustion, the entrainment and purging effect of the main cyclone premixing chamber is particularly obvious.

[0019] In the specific implementation of the present application, the coal gas enters the coal gas distribution ring 3-2 from the main coal gas inlet pipe 3-1, and enters the main rotational flow premixing chamber 1-1 through the multiple rows of multiple coal gas nozzles 3-3 which are uniformly distributed in the circumferential direction and are horizontally inclined on the inner side of the coal gas distribution ring 3-2. Similarly, the air enters the air distribution ring 4-2 from the main air inlet pipe 4-1, and enters the main rotational flow premixing chamber 1-1 through the multiple rows of multiple air nozzles 4-3 which are uniformly distributed in the circumferential direction and are vertically upward after turning on the inner side of the air distribution ring 4-2. The coal gas and air streams respectively sprayed from the three layers of coal gas nozzles 3-3 and air nozzles 4-3 which are staggered in each layer complete sufficient and uniform premixing with each other in the process of rotational flow, and form rotational flow premixed gas streams, which are then sprayed out through the airflow converging outlet flow channel 1-2 at the bottom of the main rotational flow premixing chamber 1-1, form rotational flow diffusion gas streams, and form backflow vortexes in the center to enter the combustion space or heat utilization space, and form stable combustion gas streams after ignition at the hot spot. The stable flame effect is the backflow vortex flow formed by the rotational flow gas streams in the airflow converging outlet flow channel 1-2. When the burner needs to be adjusted, the coal gas and air enter the auxiliary rotational flow premixing chamber 2-1 through the auxiliary coal gas inlet pipe 2-4 and the auxiliary air inlet pipe 2-5 respectively, and form rotational flow gas streams in the same direction as the rotational flow direction of the main rotational flow premixing chamber 1-1 with the assistance of the circular-arc-shaped flow guiding premixing ring groove 2-2, and enter the main rotational flow premixing chamber 1-1 downward through the auxiliary premixed gas nozzle outlet 2-3. At this time, the adjustment effect is mainly to form different mixing states of different components in the auxiliary rotational flow premixing chamber under the condition that the main combustion state does not change, and to change the combustion state without changing the rotational flow intensity. The usual adjustment working conditions are: 1) only the auxiliary coal gas is opened or only the auxiliary air is opened (suitable for low coal gas calorific value or high coal gas calorific value); 2) the auxiliary coal gas and air are not opened (suitable for normal operation condition); 3) the main coal gas and main air are not opened (suitable for furnace heating and heat preservation condition). When the burner is started (furnace is started) and the burner is stopped (furnace is stopped), it is necessary to introduce high pressure (or relatively high pressure) air into the control gas flow inlet pipe 2-10, and then the air is sprayed out from the auxiliary premixed gas nozzle outlet 2-3 through the control gas flow nozzle outlet 2-11. For the burner starting condition, the main purpose is to suck away the residual coal gas in the burner through high pressure gas flow injection, so as to prevent the explosion of the burner when the air pipeline is opened first when the burner is restarted. For the burner stopping condition, the main purpose is still to suck away the residual coal gas in the burner through high pressure gas flow injection, and to reduce the temperature of the main rotational flow premixing chamber of the burner, so as to prevent the main rotational flow premixing chamber from burning when the burner is restarted. In normal operation, if the main rotational flow premixing chamber is high temperature, the high pressure gas flow in the control gas flow inlet pipe can also effectively reduce the temperature of the main rotational flow premixing chamber, so as to maintain the normal premixed combustion condition.

[0020] From the above implementation process can be seen, 1) by setting the multi-layer air-coal gas phase arrangement of the circumferentially uniform horizontal inclined multi-channel premixing structure in the main swirl premixing chamber of the burner, and cooperating with the lower part of the contraction and expansion of the nozzle structure, the fully and stable premixed combustion process is realized under the premise of realizing the fully uniform swirl air-coal gas premixed gas flow, and the circumferential uniformity of the air-coal gas flow can be achieved, which provides a safe and controllable burner structure for completely realizing the fully premixed combustion of the hot blast furnace; 2) The auxiliary swirl premixing chamber is added, which makes the combustion adjustment and control more reliable, controllable and convenient, and also effectively and definitely guarantees the normal combustion process; 3) High-pressure air high-speed injection of air and air can not only enhance the adjustment effect of the auxiliary swirl premixed gas flow on the main swirl premixed gas flow, but also effectively remove the residual gas when the burner starts and stops, and effectively reduce the temperature of the main swirl premixing chamber of the burner, so as to ensure the smooth progress of the premixed combustion process.

[0021] Specifically, in view of the fact that it is difficult for conventional gas combustion devices to achieve true premixing combustion, the present application proposes a burner with a main and auxiliary cyclone premixing chamber, which connects the main and auxiliary cyclone premixing chambers in series to achieve sufficient strong cyclone premixing of air and gas (fuel gas) without preheating combustion in the chamber, thus having the remarkable features of low-temperature operation and safety explosion prevention. It is a new burner structure that combines various fluid flow modes and premixing modes, and has combined innovation and unique innovation that are integrated with each other. The structure of the air-gas in the main cyclone premixing chamber of the burner is staggered and arranged in layers, which can effectively achieve the function of sufficient and uniform premixing of air-gas (significant improvement of premixing degree). The air-gas in the auxiliary cyclone premixing chamber at the top forms a high cyclone strength premixed gas flow through the guide and premixing ring groove, which plays an active and forced adjustment role on the main cyclone premixing chamber, produces sufficient and complete premixing effect between air-gas flows, and actively and efficiently regulates the premixing state of air-gas. At the same time, the control gas flow introduction pipe at the center can spray gas flow for main premixing chamber purging after stopping combustion, effectively preventing and avoiding backfire and deflagration accidents caused by gas residue after the burner stops combustion, and can effectively regulate the overall temperature of the premixing combustion device (mainly to reduce the temperature of the main cyclone premixing chamber) to prevent air-gas flow from burning in the main cyclone premixing chamber during the next combustion process. Finally, the air-gas flow that has been fully premixed passes through the converging-diverging nozzle outlet to form a strong rotational vortex flow state at the center, and after ignition at a high temperature, it forms a stable premixed combustion gas flow, effectively avoiding flameout (extinguishing) and combustion process oscillation during high-flow-rate combustion. Obviously, the combustion device of the present application can achieve complete, sufficient and uniform premixing of air-gas flow in a cold state, and stable and completely controllable premixed combustion after the premixed gas flow is sprayed, realizes complete, sufficient, uniform, safe, stable and controllable high-temperature, high-efficiency and low-nitrogen combustion in the premixing combustion process, overcomes many problems of instability, uncertainty and uncontrollability in the conventional gas fuel combustion process, can effectively control and ensure the smooth progress (maintenance) of the premixing combustion process, and can effectively regulate and control the combustion conditions. It can fully meet the technical requirements of various heat utilization equipment for energy saving, high efficiency, high temperature and low emission, and is suitable for various heat utilization equipment such as energy-saving and environmentally friendly main and important equipment such as hot blast furnace, heating furnace, boiler, etc. It has a relatively wide application environment and development prospect, and has significant social and economic benefits.

[0022] It should be pointed out that the above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any person skilled in the art can make changes or modifications to the equivalent embodiments of the above disclosed technical content without departing from the scope of the technical solution of the present application, which falls within the protection scope of the present application.

Claims

1. A burner with primary and secondary swirl premix chamber comprising a bell-shaped primary swirl premix chamber wall, characterized in that, The main rotational flow premixing chamber wall (1) is composed of a main rotational flow premixing chamber (1-1) with a mushroom-shaped cross section and a lower gas flow converging outlet flow channel (1-2) with a converging cross section. The top of the main rotational flow premixing chamber (1-1) is provided with an auxiliary rotational flow premixing chamber (2-1) with an inverted bottle-shaped cross section formed by an auxiliary rotational flow premixing chamber wall (2), a flow guide premixing ring groove (2-2) with a circular arc-shaped cross section is arranged at the lower part of the ball top, and an auxiliary premixing gas outlet (2-3) is arranged at the lower part and communicated with the main rotational flow premixing chamber (1-1).

2. The burner with primary and secondary swirl premixing chamber according to claim 1, characterized in that, The main rotational flow premixing chamber wall (1) is a bell-shaped structure composed of a steel shell and an inner layer of high-temperature-resistant refractory material.

3. The burner with primary and secondary swirl premixing chamber according to claim 1, characterized in that, The main rotational flow premixing chamber wall (1) is composed of a heavy refractory brick layer, a light refractory brick layer, a ceramic fiber felt layer and a steel shell from inside to outside, and a 50mm-thick refractory spraying layer is sprayed on the inner surface of the steel shell to improve the rigidity of the steel shell. The auxiliary rotational flow premixing chamber wall (2) has the same masonry structure as the main rotational flow premixing chamber wall (1).

4. The burner with primary and secondary swirl premixing chamber according to claim 1, characterized in that, The coal gas nozzle (3-3) and the air nozzle (4-3) are a plurality of one-way horizontal inclined and vertically multi-layer arranged air flow channels which are alternately and uniformly distributed, and the number of layers of the air flow channels is at least three; the inlet end of the coal gas nozzle (3-3) is vertically connected to the inner wall of the coal gas distribution ring channel (3-2), and the outlet end is horizontally inclined to the outer wall surface of the main rotational flow premixing chamber (1-1) with an inclined angle of 15°-45°, and the cross section is a gradually converging nozzle; the inlet end of the air nozzle (4-3) is vertically connected to the air guide pipe (4-4), the air guide pipe (4-4) is connected to the air distribution ring channel (4-2) after being turned upward, and the outlet end of the air nozzle (4-3) is horizontally inclined to the outer wall surface of the main rotational flow premixing chamber (1-1) with an inclined angle of 15°-45°, and the cross section is a gradually converging nozzle; the uniformly distributed and staggered and multi-layer combined nozzle structure of the coal gas nozzle (3-3) and the air nozzle (4-3) can achieve sufficient and uniform rotational flow premixing of air and coal gas.

5. The burner with primary and secondary swirl premixing chamber according to claim 1, characterized in that, The auxiliary rotational flow premixing chamber wall (2) is symmetrically provided with an auxiliary coal gas inlet pipe (2-4) and an auxiliary air inlet pipe (2-5) which are connected to the rotational cutting direction of the guide flow premixing ring groove (2-2) to form a strong rotational flow premixing adjusting gas flow, and the rotational flow direction is consistent with the empty coal gas rotational flow direction in the main rotational flow premixing chamber (1-1); the premixing state of the rotational flow premixing adjusting gas flow is determined by the opening degree of the auxiliary coal gas adjusting valve (2-8) and the auxiliary air adjusting valve (2-9); when the auxiliary premixing gas nozzle (2-3) is connected to the top of the main rotational flow premixing chamber (1-1), the channel is gradually expanded to form a rotational flow divergent jet flow which affects the main rotational flow premixing gas flow.

6. The burner with primary and secondary swirl premixing chamber according to claim 1, characterized in that, The regulating gas flow inlet pipe (2-10) is a circular pipe made of heat-resistant steel, the lower end is gradually contracted to form a regulating gas flow nozzle (2-11), and is arranged at the center of the auxiliary premixing gas nozzle (2-3).

Images