Products by Loesche America:

HOT GAS PRODUCERS

Our Specialty since 1960

The combustion chamber developed by Loesche GmbH is primarily fabricated from heat resistant steels. Refractory lining material is only used in the area of the burner muffle.

This combustion chamber type, introduced under the name LOMA heater (Lochmantel-Feuerung) has been employed worldwide for decades in various thermal processes and contributed to their optimum thermal design.

The LOMA heater is characterized by the following:

• The steel combustion chamber has only minimal refractory lining in the burner muffle, thereby reducing the retained heat. Long heat-up and cool-down times are not required.
• Rapid thermal load variation increases the control of downstream processes.
• Emergency stop and normal start/stop sequences do not require the installation of an emergency chimney.
• Due to the steel construction a distinctly reduces machine weight is achieved when compared to combustion chambers which are completely refractory lined.

Any preferred burner type from various suppliers can be used in conjunction with the combustion chamber.

In the 40 years of use worldwide all conventional fuels such as the following have been successfully used:

• Natural Gas
• Industrial Gas
• Blast Furnace Gas
• Light Fuel Oil
• Heavy Fuel Oil
• Crude Oil

The decades long experience in the use of these combustion chambers with various burner types and fuels in diverse applications puts Loesche GmbH in a position to offer hot gas producer plants on a turnkey basis. Experience in process plant design and presence of Loesche personnel on all constituents ensures efficient support for erection, commissioning and maintenance.

The After Sales Service department guarantees that as far as necessary, new developments are applied in existing installations.

Understanding Flow:
The flue gas generated by the burner (5) flows through the burner muffle (4) and is mixed, in the perforated jacket area, with the process air to be heated. The process air (3) flowing in allows the perforated jacket (1) and the protective jacket (2) to be cooled. The design of the combustion chamber also enables a spiral flow cycle of the process air to be generated.

The spiral flow is also transferred to the flue gases from the burner muffle, which brings about an intensive mixture of both gas flows. As a result, a very even temperature profile is attained at the outlet of the hot gas generator.

The temperature limit of the hot gas is 500 °C for the standard design; for higher temperatures of up to 800 °C an improved material is supplied.

The LOMA heaters are offered in a standardized range, with the thermal outputs of 1.25 x 106 kJ/h to 145 x 106 kJ/h.

Applications of the classic LOMA heaters
In the past decades, this hot gas generator has been supplied by the Loesche GmbH to the most diverse branches of industry and is being operated with great success.

Dry-grinding processes are one of the main applications, primarily in connection with modern LOESCHE roller grinding mills for the drying and grinding of:

• Cement raw meal materials
• Coal
• Limestone
• Dolomite
• Slag
• Copper ore

Drying of sensitive materials such as fertilizers and other products from the chemical industry is another key function of the LOMA heater –as is sewage sludge drying in mobile drying plants.

The use of LOMA heaters is primarily based on the advantage provided by their very low weight compared with combustion chambers lined completely with refractory material. The fact that the hot gas generator can be immediately started and shut down also allows great flexibility however and enables such drying plants to be optimized in terms of energy management.

Drying of feedstuffs: For several years, the state authorities have, for the purpose of minimizing CO emissions, promoting the use of drying techniques which emit lower levels of CO.

The very even temperature profile at the outlet of the hot gas generator prevents the material from overheating as a result of hot flue gas flows and thus also avoids increased CO formation.

A Special Development for the Burning of Low-Calorific Gases
The LOMA-heater combined with a multiple lance burner represent a special development and is characterized by the following features:

• Minimum stored heat
• Low preheating period only when starting from the cold state
• Wide Control Range (Plant can be immediately started and shut down)
• No supporting burner necessary
• No emergency chimney necessary

The multiple lance burner (1) is made up of a number of individual nozzles, for both low-calorific gas and combustion air. Both constituents meet within the nozzle mixture; the basic requirement for efficient combustion is therefore achieved.

Owing to this flow design, it is possible to carry out the major portion of the combustion process in a very small burner muffle (3).

To start the hot gas generator, is it essential to use a start burner (2) installed co-axially.

This start burner has the function of heating up the interior wall of the burner muffle to a surface temperature of approx. 700 °C - the inflammability limit temperature of CO. After the main burner has been started, the start burner is switched off.

At the same time, the start burner can be sized so that an entire plant can be heated up. e.g. for the dry-grinding of coal, dry-grinding of slag etc.

To ensure a stepless operation, the capacity ranges of the main burner and the start burner are designed to overlap.

The main burner has a control range of 1:10, the start burner control range is 1:5 - 1:8. Every essential operating point within the control range of approx. 1:50 - 1:70 can therefore easily be achieved.

The hot flue gases escaping from the burner muffle (3), are in the area of the perforated jacket (4), mixed with the process air to be heated up, which is supplied to the hot gas generator via the spiral housing (5).

Its main application is the burning of blast furnace gas. By means of this combustion system, low-calorific gases with a thermal value from 2,500 kJ/m3 (S.T.P.) are burned without a supporting burner.

Such hot gas generators are used in connection with Loesche roller grinding mills in dry-grinding plants to process coal for the smelting of iron ore.

Since 1991 fourteen hot gas generators - as described - have been built and put into operation. The thermal output of these plants is between 16.7 x 106 kJ/h and 54 x 106 kJ/h.

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