Optimal Technical-economic Solution for Heating of a Production Hall

IndustrySouth-East European INDUSTRIAL Мarket - issue 2/2005

South-East European Industrial Market Forum

What is the optimal technical-economic solution for heating of a production hall (workshop) with a total area of approximately 2500 m2? The structure of the hall is a frame with pillars. The distance between the pillars in the walls is 6 m and in the room – 18 m. There are three assembled and functioning portal cranes in the workshop.

The altitude of the factory is approximately 600 m. Gas supply has been installed. The work is done in one eight-hour shift, five working days a week. The nature of the production process does not require frequent opening and closing of the doors. There is a stipulation for guaranteeing 18° C with a -7° C outside temperature. In terms of the production process it is important that the temperature in the workshop does not get lower than 5° C in the nights.

In reply to the organized by the South-East European Industrial Market magazine market research for the possible technical solutions for heating of the aforementioned industrial hall among firms that offer HVAC equipment in Bulgaria we publish various expert opinions on the topic. The received opinions can be generally divided into three main groups – solutions based on heat-conducting appliances, industrial floor heating and gas radiant heating. It should be taken into consideration that in order to find the optimal technical solution to the task, further specifications and characteristics of the site and its application should be supplied.

Heating systems based on heat-conducting appliances

Typical of the heating with heat-conducting appliances is the initial warming of the air, which results in the eventual warming of the subjects and people in the room. The use of heat-conducting appliances requires a beforehand switching of the system in order to provide a sufficient period of time to heat the rooms to the desired temperature. Therefore, in the mornings, when the hall is cold, the heating of the working areas requires time and additional energy. The use of atmospheric heat-conducting appliances is one of the possible technical solutions to the task. The advantages of this type of heating are that it is not necessary to construct a pipe system, but only gas-mains, which accounts for the lower initial investment and also that it is possible to realize zone heating. The disadvantages of this type of heating are that it leads to great convection and unnecessary heating of great air volume, resulting in higher operation expenses, which can be significantly reduced by careful regulation. Another option for the practical realization of the task is to use water heat-conducting appliances. These are heat-conducting appliances supplied with a water air-heater and a fan. The water heat-conducting appliances require the construction of a central supply system.

The heat supply to the separate appliances comes from a boiler. The appliances can be supplied with a thermostat for easier regulation. The heating installation in this case is based on a boiler, usually regulated by the outside temperature. It is characterized by its high maintainability. Its disadvantages are the heating of great air volume, the necessity of constructing a pipe system. Heating systems based on atmospheric heat-conducting appliances are offered in Bulgaria by the “ITA COM” company, and “Ruvex” company with the trademark KROLL. The “Horoz” firm recommends the use of heat-conducting heating system, if the production category is either A, B or C according to the international standards. Other firms that have expressed the opinion that in numerous industrial applications the use of gas heat-conducting appliances is reasonable are the “ET Dinel-Nedialka Colova” and “Bulgaria Therm”. The “Energy-BG” company recommends the use of the ORION AL-KO heat-conducting heating system. Water heat-conducting appliances are also offered by the “Ruvex”.

Industrial floor heating

Its characteristic is that it quickly heats the working areas, but its construction is accompanied by a relatively difficult assembly of the pipes in the floor of the workshop and limitations on the loading during operation. It can be realized as a floor radiant heating.

That is a low temperature heating (temperature range 50°/40°C), performed by coiled in the floor loops of polythene pipes with aluminum deposit. This type of installation requires the construction of a central heat supply line. The water in the installation is heated by the boiler, located in a specially designed boiler-room. The advantages of this method are that it only heats a zone of about 2.5 m above the floor, resulting in the heating of small air volume, which leads to lower operation expenses.

The systems are usually realized on the base of a central heat supply by a boiler, which control is fully automated and it controls the combustion process in accordance with the outside temperature. The effect could reach up to a 30% energy saving. This method of heating allows the convenient solving of the matter with the daily hot water supply, as well as other temperature circles (if any). There is an option for cooling through the floor loops for the summer. It is considered that the high efficiency justifies the higher initial investment. Some other advantages are the even temperature distribution and the reduced convection mobility of the air, which leads to less dust in the air. The relative inertness of the system is also an advantage.

A disadvantage is the necessity of ceasing the production process for the assembly of the floor loops. Maintenance expenses should also be taken into consideration, for example, those for floor coatings. The inertness of the radiant heating is considered by many experts to be an advantage, while others believe it is a disadvantage.

The system mainly functions through radiation and not convection, which prevents the raising of the dust from the floor and protects the respiratory process of the building occupants. The use of a low temperature boiler and/or air cooling heat-pump unit air/water as an energy source can prevent the condensing on the surface of the combustion chamber, which aids the proper application and secures a prolonged functioning of the boiler.

This solution is applicable when the floor surface is not occupied with any special equipment, materials, goods etc. A relative inconvenience of this solution is the raising of the floor level with approximately 15 cm, due to the thermo-insulation, waterproofing, loops, reinforcement, reinforcing plate and coating. Such systems can be implemented by the “Ecothermal”, “ITA COM” and “Ruvex” companies.

Infrared gas radiants

It is considered that the competition of the industrial infrared gas-ceramic heating is due to the:

  • Use of cheap fuels – natural gas or propane-butane. The radiant system provides high efficiency.
  • Distribution of directed radiant energy without any transportation loss.
  • Flame-free, wasteless and noiseless combustion. The maintenance of the system is financially advantageous – there are no expenses for boiler maintenance, heat exchangers, hot water pumps, softening devices and anti-scale chemicals, heating mains and radiators, air conduits and any installations for conducting heated water or air. The options for making serious savings of fuel, personnel etc. make the investment for the purchase of the system a rather profitable one.

Another advantage of the system is the unaging materials of its components – ceramics, stainless steel, brass. This type of heating is characterized by its many advantages compared to conventional heating. First and foremost, it does not require the use of antifreeze systems. Moreover, the working areas and the people are heated directly and as a secondary result they start to heat the air themselves. It is possible to switch the heating only in particular zones of the production rooms.

The effect of the heating can be felt by the people minutes after the switching of the radiants, i.e. it only takes minutes to reach the comfortable working temperature.

Among the Bulgarian companies recommending the use of such systems are “VAC”, on the base of SCHWANK equipment; “CBM Incorporated”, offering CBM International; “Horoz”, by the use of Solaronics, “Gema Engineering”, “Bulgaria Term”, “Nora Gas”, offering systems of Roberts Gordon and “CBM Bulgaria” by CBM International.

TLL Media Ltd. Editorial Department is waiting for any comments and new ideas for heating solutions of such a production hall.