Water cooling essentials in a cooling tower

Cooling towers are lean and simple machines aimed to cool down water employed in industrial production processes of any kind. These are simple machines because the only component moving is the electrical fan, and the cooling process is achieved through a direct air/water contact heat exchange, without exchange pipes.

The water to be cooled enters in direct contact with the air in the cooling tower, allowing the water to be cooled at a lower temperature compared to the environmental air temperature.

This is achieved thanks to the latent heat of vaporization that brings a wind chill effect, taking advantage of the amount of water that evaporates in direct contact with air, removing calories. The amount of heat removed by water’s evaporation is a relevant amount, called latent heat of vaporization, and is equal to about 550-600 kilocalories per kg of water evaporated.

And so, a cooling tower is a machine that allows to cool water in a very efficient way with a contained energy consumption. On the opposite, there is a consumption of water, dissipated due to evaporation, that must be reintegrated in the circuit in a greater quantity than the quantity of water dissipated, in order to dilute the concentration of salts obtained as a consequence of the evaporative process.

The reference temperature for the cooling potential that can be achieved in a cooling tower is the wet bulb temperature, that is the environmental temperature measured with a thermometer with a moist bulb. Usually, wet bulb temperature in a city like Milan, for example, is 26° C in the worse conditions, in July, when ambient temperature rises up to 35-36° C. In these conditions, the wet bulb temperature is 10° C lower than environmental temperature, so that it’s possibile to cool down water at a temperature 3-4° C higher than wet bulb temperature, depending on the design and sizing of the cooling tower.

Thermoregulation unit in pharma lab

The processing of pharma products requires well defined temperature loops that must be thermoregulated, as we’ve already faced the argument in many other occasions. Recently, we’ve supplied a new thermoregulating unit for a pharma lab, intended for heating and thermoregulation of injectable solutions.

termoregolazione laboratorio farmaceutico

The thermoregulating unit is employed for laboratory tests and production, combined with an equipment that forces an injectable solution to achieve a defined thermal cycle.

Tempco termoregolazione farma

The main target of the application is to obtain high precision temperatures and to maintain them within a strict range of tolerances that can be programmed/setted-up.
The solution is completed by a remote interface for the recording with data log of the results. The thermoregulation unit is in full inox execution for employ in pharma environment.

Tempco pharma thermoregulation unit

Dimple jacket exchangers in industrial laundry ironers

A new and curious application of TCOIL dimple jacket exchangers we’ve recently made involves these flexible type of heat exchangers in the manufacture of flatwork ironers. These are big industrial mangano ironers employed in big industrial laundries for automatic ironing.

Mangano ironer TCOIL dimple jacket

We’ve realized the cradles of these big dryers and ironers with a special TCOIL, with upper side with higher thickness and a polished surface, and lower side inflated. Diathermic oil flows inside the inflated plates. The TCOIL in the ironer can indeed be heated using steam or hot oil, to reach a temperature of 120/130° C.

TCOIL applicazione mangano da stiro

The laundry is passed between the cradle and the roll mounted as it can be seen in the images. Sort of huge ironers, these mangano ironers are commonly employed to dry and iron flat laundry, such as sheets, bath towels and tablecloths.

mangano da stiro scambiatore TCOIL

Free cooling for heat dissipation in inverter testing

This past week we have installed a cooling plant for heat dissipation of resistive electrical resistances employed in the simulation of working conditions of inverters. The plant was commissioned by CRS, a company based in Merate (LC, Italy) that designs and manufactures inverters and industrial power equipment.

dissipazione test inverter CRS

The company needed a cooling plant for heat dissipation of electrical power loads during the testing of its inverters. We’ve supplied a dry cooler system for outdoor installation and a distribution and pumping circuit of cool water serving the two testing areas.

dry cooler inverter CRS

The installation has been achieved with maximum customer’s satisfaction. The distribution system has been realized on-site, and all the piping employed is made by stainless steel.

raffreddamento inverter CRS

Self draining Dry cooling, cooling efficiency in every season

We’re facing today the topic of dry cooling, and in particular of self draining dry cooling. First of all, a dry cooler is an air/water exchanger that employs ambient air as cooling media to cool down the temperature of water. Compared to an evaporative cooling tower, a dry cooler offers simple installation, easy management and employs water in closed circuit, never in direct contact with external ambient air. The fluid to be cooled is indeed circulating in pipes, while the exchanger has a fin pack, often with copper pipes and aluminium fins but it’s also possibile to have stainless steel pipes and aluminium fins or both pipes and fins in carbon steel, depending on the kind of application and type of fluid to be cooled (water, water glicol, hydraulic oil, diathermic oil for example).

A dry cooler is in addition a quite economic solution, due to the fact that the only energy consumption is related to the fans ensuring the air flow.

A dry cooling solution has some limits, strictly related to the external ambient air employed to cool down the fluid. During the summer, the outlet temperature of the water can be indeed at maximum 5-10° C higher than the temperature of ambient air.

On the other hand, during the winter, when air temperature goes below 0° C, the risk is that the water inside the pipes can freeze, with severe damages to the plant with breakage of pipes. In this case there are two solutions: if the requirement of the process allows it, is it possibile to employ water glicol, preventing the freezing, otherwise the solution is represented by self draining dry coolers. In this kind of dry cooler the water inside the pipes is automatically and completely drained out of the exchanger, thanks to a sloped exchange pack and to a special pipe battery with valves for the complete discharge of the water.

At last, dry coolers have significantly increased their energy efficiency thanks to developments in the technology of fans, using EC motor fans that during the different seasons provide the proper adjustment of the functioning speed to the weather conditions and to the effective needs of the plant, reducing energy consumption at the minimum required.

Dematerialization and green recovery in the farm

Time for dematerialization in Tempco… in our path toward digitalization we’ve taken a step forward by eliminating all the documents stored in our archives for the past 12 years.

In the sign of saving and recovery, heat recovery and not only, we’ve looked for a green way to recycle the whole amount of paper that was coming out of the paper shredder. We finally found a farm, the Farm Besana, that takes care of animals with respiratory disease due to hay using paper strips as bedding.

dematerializzazione documenti archivio green

The paper bedding is eco friendly, absorbent and doesn’t generate dust. It is the ideal solution for horses with respiratory issues, and a valid and economic alternative to de-dusted hay.

recupero greeen dematerializzazione

Fattoria Besana cavalli

A nice example of circular economy, don’t you think?

The beautiful horse pictured here is called Egano 7 and is allergic to hay, so that it must be fed only with de-dusted e wet hay.

 

 

 

 

 

 

 

Logarithmic mean temperature difference in heat exchangers selection

LMTD stands for Logarithmic mean temperature difference, being the logarithmic average of the temperature difference between the hot and cold feed on primary and secondary end of a heat exchanger. The value is fundamental for the calculation of the thermal exchange surface of a heat exchanger.

The LMTD is a crucial value also for the selection of the kind of heat exchanger most suitable for a certain application. Thermal transfer between two fluids presenting a short temperature gap is indeed very slow, while it will be much more faster and efficient in case of steam at 130° C to heat up cold water to a temperature of 70° C, for example. For the same reason, heat recovery is much more efficient having a small quantity of water at very high temperature instead of a lot of water at a mild temperature.

Plate heat exchangers allow to work with very narrow log mean temperature differences, thanks to possibility to work with countercurrent fluids and with turbulent flows, achieving high thermal exchange rates. Thermal transfer rates of shell and tubes exchangers are instead lower, thus requiring a higher LMTD. The Log mean TD is therefore even widened for air/water or air/steam finned pack exchangers, requiring very extended thermal transfer surfaces.

In general, the logarithmic mean temperature difference is inversely proportional to the thermal transfer surfaces. Even a half degree of difference has a strong impact on the heat transfer surface and the calculation of a heat exchanger, thus on its cost.
In Tempco we’re are willing to provide you some example of this kind of calculations!

Cooling of soda solution in oil & gas depuration process

We have recently realized an interesting application for the cooling of soda caustic solution employed in the separation and purification process in oil & gas facilities. The system employs a plate heat exchanger served by a chiller, that produces nonfreezing solution at the temperature of 0° C employed for the cooling of a caustic soda solution at 4%. The soda solution comes from the depuration process of the condensations of the petrochemical plant, with an inlet temperature in the plate heat exchanger of approx 45° C and outlet temperature of 25° C.

Tempcoil gas raffreddamento soda

The treatment of condensations in an oil & gas plant is achieved using a bipolar cation and anion-exchange resins membrane process, that removes the ions present in the condensations cooled down at 45° C, in order to avoid possibile pollution by hydrocarbons. The exhaust resins are then regenerated with solutions of sulphuric acid and soda at 4%.

The heat exchangers has titanium plates, ensuring corrosion resistance due to possible presence of chlorides concentrations. The thermal power capacity is 500 KW, and all the connecting pipes are mixed rigid and flexible, in order to allow easy installation operations on-site.

scambiatore piastre petrolchimico

tubazioni connessione impianto raffreddamento

The chiller provides the heat dissipation of the thermal energy removed from the soda solution, and must ensure 365/24 operations. The system is thus equipped with redundancy, with multi-compressor and multi-circuit, avoiding interruptions of the depuration process even in case of partial fault. In addition, the chiller has been sized for the most challenging summer design conditions, to guarantee the maximum efficiency in all variable weather conditions in winter/summer. A step regulation allows to adjust the power capacity to the season and to the effective thermal need required.

raffreddamento petrolchimico

 

First start-up of a thermoregulating unit

The initial start-up of a thermoregulating unit is a very delicate monent, on which many customers ask for our support.

Industrial thermoregulation units by Tempco are supplied completely tested and checked. Once on-site, the units must be filled with the working fluid and started-up, and this operation is crucial for the safe and optimal functioning of the units.

The filling is indeed a very delicate step. In case of water or pressurized water as working fluids, the operation is simplified because water easily flows within the hydraulic circuits, giving no problems related to air bubbles. The operation becomes more delicate with diathermic oil thermoregulating units: the heat transfer oil has indeed a high viscosity, capturing and holding air bubbles.

It seems a trivial tip, but the very first thing to do proceeding in the first start-up of a thermoregulating unit is to check the rotation direction of the pump. This is important for two main reasons, the first being to ensure the correct functioning of the unit to achieve maximum efficiency, and then because a wrong pump rotation direction can damage the spring of mechanical seals of the pump.

Let’s then start filling up very slowly the unit, taking care of completely eliminate the air within the hydraulic circuit. Once the air is completely removed, is it possible to proceed with the first start-up of the thermoregulating unit, turning on the pump and checking the pressure indicator on pump delivery. The pressure indicator must be stable, indicating the nominal project value of the working pressure of the pump. Otherwise, if the indicator is shaking, it means there is still some air inside the circuit, that must be removed. The cycle must be repeated until the pressure is completely stable.

Once the air bubbles are totally removed, the temperature can be raised, setting an lower set point on the thermoregulator compared to the nominal final working temperature, checking that the pressure indicator is stable. The operation must be repeated until the final working temperature is reached.

The first start-up of a complicated industrial thermoregulating unit working with diathermic oil can even take a whole working day, but it’s very important to carefully achieve it. In particular, the first heating up run must be done gradually and very slowly, to ensure that there is no air bubbles within the hydraulic circuit, avoiding serious damages on the mechanical components of the unit, such as mechanical seals and heating resistances.