Public company Medellin (Colombia) already running the project Thermal District, the first of its kind built in Latin America, which begins offering a new service: air conditioning on demand.
by José Luis Restrepo Castrillón *
One of the main objectives of EPM is to optimize the energy basket of its customers from the provision of Natural Gas as an efficient, economic and environmentally sustainable fuel. From this objective, it takes relevance the concept of rational and efficient use of energy [URE], understanding this as the optimal use of energy in all links of the different energy chains.
The URE practice be performed based on the selection of an energy source, such as natural gas, optimizing consumption and including the use of combustion products.
According to the provisions in the current strategy of EPM Gas Management, the new project District in Medellin Thermal Alpujarras, promote the theme of development of new products and services that involve:
- Knowledge and understanding of clients' business.
- Beyond that provide natural gas as our commodity, energy solutions that leverage the survival and growth of the client company will be offered
- Establish long-term and at all levels with our customers and
- To ensure that the productive growth this always framed within an environmentally sustainable development
What is a Thermal District?
System Thermal District (SDT) is a system of urban distribution that produces steam, hot water and chilled water from a central plant and then carried by pipeline to district buildings for space heating (heating), to supply water domestic hot and / or for space conditioning (air conditioning). Thus, the individual buildings do not need their own boilers or furnaces, or cooling equipment (Chillers), "The Thermal District does that work for them."
The best of SDT is that it meets the needs of all consumers in one place and you can achieve results that an individual system usually could not. For example, in certain cases an SDT can use a variety of conventional fuels (eg natural gas.) And unconventional (eg solar energy.); further by the size of an SDT, the plant can be changed to use renewable fuels such as biogas or biomass, among others, and not being enough, you can also use the combination of heat and power as an alternative to increase efficiency.
Buildings connected to the SDT have lower costs in purchasing their capital because teams do not need boilers or chillers, and also save space which can be used for other needs.
Owners and building managers participating in the SDT can focus on their reason for being and not have to have expert staff on the issue because they are professionals District those who are operating continuously and have backup systems available. Many of the SDT operate with a reliability of "zeros 9: 99,999%", according to statistics of IDEA (International District Energy Association)
What is Heat and Power Combination (Heat & Power) CHP?
The energy problem is not the shortage of energy, but the technical capacity of its conversion into useful forms. The desired energy or we think of as easy to use, are scarce or too costly to produce, as in the case of electricity. This also does not exist in nature in a directly usable way; hence the constant need to find efficient ways to convert natural energy resources of primaries -energías in forms of useful energy for the processes in modern society, seeking greater efficiency in the transformation. The concept of cogeneration and trigeneration (cogeneration extension) precisely seek to achieve greater efficiency and optimization in the conversion of primary energy source to useful forms of energy.
Cogeneration, also known as CHP: combined heat and power -the combination of heat and potentials, it is the combined production of thermal energy and electrical or mechanical energy. This process is performed from the use of a single primary energy source that drives a motor or a turbine according to the type of fuel available natural origin. The thermal energy is produced in the form of heat that is usually used in the form of hot water or steam. The scope of cogeneration is very broad, including industrial, commercial and service facilities and even residential. Depending on design and equipment, a cogeneration plant can achieve efficiencies up to 60%, which is almost twice the efficiency of traditional power plants.
Trigeneration, also known as CHPC: combined heating, cooling and power generation -the combination of heat, cooling and potentials in essence is the same cogeneration with the addition of a cold generation process. It is defined as the process of production of four products from the primary source:
1. Mechanical power generation or
2. Steam generation
3. Hot water generation
4. Cold generation (cooling, air conditioning).
The possibilities of these processes allow achieving high operational flexibility according to the demands of each of the products; this implies the possibility of meeting many types of applications in countries with or without weather stations.
The efficiency of a trigeneration process depending on the design and equipment can achieve efficiencies up to 90%.
The cold creation process is achieved by recovering heat from cogeneration basic process (CHP) and use it in a cooling process, also known as ARP: Absorption / Adsorption refrigeration plant -ground absorption refrigeration / adhesion-.
Cooling processes have heat from the CHP process connection with two basic modes:
1. Direct connection: Using the exhaust gas and / or the obtained heat engine cooling circuit CHP process. ·
2. Indirect connection: Use low pressure steam or hot water from the CHP process. Depending on the application and need for generating different types of liquids cold heat exchangers are used in the process to achieve the application temperature ranges. lithium bromide temperatures above ranges 5 degrees Celsius or ammonia ranges included and -60 temperature between + 5 degrees centigrade is used. There are available other liquids that are restricted for environmental reasons.
The sizes of the projects are diverse, even in some developed countries have implemented applications relatively large size compared to traditional thermoelectric generators sized plants.
Thermal District Las Alpujarras, Medellin
The project Thermal District (SDT) Alpujarra Medellin is a cooling system located in the La Alpujarra, centrally produced and distributed cold water through underground piping. The cold will be used in the space conditioning in buildings and facilities belonging and adjacent to the Administrative Center La Alpujarra sector, among others: 1. Building of the Mayor of Medellin, 2. City Council building, 3. Building of the Government of Antioquia, 4. Departmental Assembly Building, 5. Building Metropolitan Area, 6. Building of the Tax and Customs DIAN and 7. UNE building (called UNE Courts)
Technological configuration of the plant - CT
The Central plant where the production of cold is given is called Thermal Power Plant (CT). The main energy or from which operate the CT is natural gas. The combustion of this puts into operation a team turbogenerator which will generate:
1. power to ensure the functioning of CT in general, including auxiliary equipment coolers (pumps, cooling towers, monitoring systems and control), also will attend the demand for electrical equipment (chiller) ice maker energy which will support average demand and peak District buildings.
2. It also produces hot air as a result of the combustion of natural gas, which will serve to operate a cooler (chiller) the type of indirect heat absorption which will be responsible for meeting the load base.Los absorption type coolers are coolers characteristics very different operating electric coolers, for example:
- They are silent, produce no noise or vibration
- They are environmentally friendly and not used coolants that affect the ozone layer and
- They operate from natural gas or indirect heat (hot air, hot water, steam).
The icy water produced in the central plant or "Thermal Power Plant - CT" is distributed via underground pipes to each of the buildings of the "District" sector to be used in their air conditioning systems just for the air conditioning of spaces, that each of the buildings that make up the District obtained by others the following benefits:
- Saving space dedicated to electromechanical cooling generation equipment; reducing the space used for the installation can reach 90% in each building.
- Reduced investment in electromechanical equipment, maintenance and renovation.
- Management outsourcing. In general, a unified management to optimize processes.
- Reduced maintenance personnel.
- Reduction of administrative management in general.
- Reducing the level of vibration and noise.
- The network can adapt more quickly to new rules or efficient technology.
- Reduction in occupancy substation EE.
Benefits for the entire coverage area DT:
- Improving the "city brand".
- Increasing the quality and value of urban space.
- efficient equipment that reduce environmental impact and consumption of energy resources.
- Centralized management and maintenance that reduce health risks and emission control and, in general, more efficient control environmental impact.
- Possibility of combining thermal power generation (cogeneration, trigeneration) to encourage the development of energy efficiency projects.
- Improving the urban landscape, by removing capacitors in facades, cooling towers, etc.
- Reduction of urban heat island effect. It means urban heat island temperature rise within urban spaces associated with several factors, including lack of green spaces, modified drafts by the shape of the buildings, radiant asphalt and vehicle emissions heat and in particular, the heat dissipated by the equipment constituting the air conditioning systems of each of the buildings.
- more efficient noise and safety in power plants treatment.
- Reduction of overall costs (energy, maintenance and investment).
- the possibility of using various energy sources and improving the autonomy ensuring continuity and reliability of service is given.
- Increased reliability and quality of the thermal energy supplied.
* José Luis Restrepo Castrillón is Professional and Optimization Technology Projects, the Projects Unit and Optimization Technology EPM. You can write to e-mail: email@example.com