Using the thermal wastes from two electrical generator groups to feed a BROAD chiller, the co-generation central produces 636TR of cold water for the air-conditioning system of the shopping.
This equipment, dimensioned to use only the thermal wastes may, if necessary, produce cold water in partial or total load through burning of natural gas, thus being a chiller with three different energy sources.
Therefore, besides saving for the customer, producing cold water without costs for the shopping, the system also provides the security of having a back up of its total load through natural gas.
ADVANTAGES OF CHILLERS FED WITH EXHAUST GASES
The exhaust gases with temperatures exceeding 400° C can feed double stage chillers with COP *= 1.39. The technology available in other Co-generation Plants operating in Brazil uses simple stage chillers with COP around 0.70 and it is still competitive in relation to conventional solutions. In these plants, the energy to feed a chiller comes from the heated water in the sleeve of the engine and in heat recovers coupled to the exhaust gases.
* Maximum load
About the point of view of energy saving, the biggest COP of TUMA-BROAD solution allows to co-generate up to 42TR per 100kW of electric power made available, against approximately only 20TR of other Co-generation Plants.
Besides the saving, the cogeneration plants, with the use of exhaust gases directly into the chiller, require a much smaller physical space, eliminating the recovery boilers, heat exchangers, and other peripherals used in co-generation traditional plants. This means reductions in the investment cost and, in many cases, the possibility of installing or not installing the Co-generation Plant.
EQUIPMENT
Absorption Chiller
Electrical Chiller
Electrical Generator
Transformers
Electrical Panels
Cooling Towers
Diverter Valve 532ºC
Retention Valve 532ºC
Project Manager
Job Management
MANUFACTURER
BROAD
York
Caterpillar
WEG
Schneider
Alpina
BROAD
TUMA
SENAP
N&A
QUANTITY
1
3
2
2
1
4
1
4
CLIENT - JCPM
CAPACITY
636TR
3 x 300TR
2 x 1300kW
1750 kVA
2600kW
1.123.650 kcal/h
508TR
650kW
DESIGNED BY TUMA
Jardins Shopping Mall had an electrical power demand of 1,260kW at rush hour and 1,924kW out of this time. This difference, 664kW, referred to the demand for energy from CAG (Central de Água Gelada, ‘iced water plant’) which, during the rush hour remained off, and the thermal load of this period was combated by the iced water of the thermo accumulation tanks.
The power consumption of the shopping mall was 73,698kW h/month at rush hour and 732,112kW h/month out of this time, totaling 805,810kW h/month. Out of this total, 370,570kW h, or 46%, referred to the monthly consumption of the CAG air conditioning. This had three electrical chillers of 300TR each, two of them operating under full load and one operated at 70%, totaling 810TR. The efficiency of the plant was 0.82 kW / TR.
Predicted situation due to the expansion and retrofit of the shopping mall
The shopping would begin to have an electrical power demand of 1,879kW at rush hour and 2,820kW out of this time. This difference of 941kW would refer to the demand of CAG energy which, at rush, hour would remain off and the thermal load of this period would be combated again by the cold water from the thermo accumulation tanks.
The power consumption of the shopping mall would be 111,597kW h/month at rush hour, and 1,068,005kW h/month out of this time, totaling 1,179,602kW h/mês. The CAG would receive another chiller of 380TR, besides having to replace one of three existing chillers due to the damage because of the time of use.
Installation of a BROAD chiller by absorption with capacity of 636TR, which can be fed directly from the exhaust gases and hot water from electrical generator groups or by direct combustion of natural gas. Operation with only two of the three existing electric chillers, getting one as reserve.
With the installation of these chillers, the absorption reduced the predicted demand for electricity of 2,820kW (out of the rush hour) to 2,044kW, excluding the use of part of the electrical chillers.
The demand for 2,044kW began to be served by two Caterpillar electrical generators, powered by natural gas, with unit power of 1,300kW, totaling 2,600kW available. The thermal wastes of these engines - exhaust gases and hot water - would be enough to co-generate up to 950TR, but the supplied chiller was a 636TR one, limited to the need for expansion of the Mall.
The BROAD chiller will operate only with exhaust gases and hot water, using supplementation of natural gas direct burning just when the Mall demand for energy is lower than 1,740kW.
The thermo accumulation tanks will be used only to supplement the thermal load of the Shopping that exceeds 1,236TR. Thus all equipment can be connected producing cold water at rush hour, because there is no differentiated price for Natural Gas at this time. Therefore the need to store cold water in thermo accumulation tanks and the losses of energy in these ones will be reduced.
In order to avoid disturbance of the adjacent environments and ensure a maximum level of noise no higher than the 85dbA on the external side, already existing in the area, TUMA measured the background noise of the place before doing the work and provided the civil project of the Co-Generation Plant, including solutions and materials for acoustic and anti-vibrating treatment.
It was also designed and installed a system of ventilation and purge with capacity to remove the heat generated by equipment in operation within the Engine Room. To minimize the volumes required for the ventilation system, and costs of acoustic reduction, it was chosen to serve the Electrical Generator groups with remote radiators.
