Green Cooling Tower Solutions

Executive Summary

This proposal addresses the problem of achieving optimal cooling capacity in a Power Plant or any Industrial Process. With regards to Power Plants, steam is used to generate electricity. By maximizing cooling capacity, less steam is required to produce a given amount of electricity, thus lowering Power Plant fuel requirements and reducing operating costs. Normally, the only means of increasing cooling capacity is to increase the size of the Cooling Tower by adding cells, which adds operating costs in the form of increased electricity. Also, significant capital investment is required to install additional cells. As capital investment was a major consideration in the original construction of Power Plants, it is often the case that the Cooling Towers are under-sized, and thus generate far from optimum supply water temperature. Therefore, most Power Plants inherently do not operate at optimum efficiency, particularly in the warmer summer months when cooling water temperature is highest.

The “Green” Cooling Tower technology is an innovative means of adding supplemental cooling capacity to a Power Plant or any Industrial Process without adding additional operating costs in the form of electricity or requiring significant capital investment. The costs of implementing this technology are immediately recoverable in terms of reduced fuel costs and increased power output capacity in summer months, as well as reduced Cooling Tower electricity usage in winter months. Most importantly, the “Green” Cooling Tower operates with no supplied electricity, using instead the hydraulic pressure of the water supplied to the unit to generate air flow which cools the water.

The benefits to Power Plants, in particular, will be significant in terms of energy impact. This technology will significantly impact a Power Plant's ability to produce maximum electricity at minimum fuel usage. This in turn directly reduces the carbon footprint of the Power Plant. Besides establishing a lower cost of operation in the peak power usage periods of summer months, Power Plants will also be able to export more Power to the grid, thus reducing consumer pricing. The net result will be that Power Plants profits will increase through reduced costs and increased output capability, while costs to the consumer will decrease, thus resulting in a significant step towards moving towards a sustainable economy, while also minimizing the impact on the environment.  

The benefits to Power Plants, in particular, will be significant in terms of energy impact. This technology will significantly impact a Power Plant’s ability to produce maximum electricity at minimum fuel usage. This in turn directly reduces the carbon footprint of the Power Plant. Besides establishing a lower cost of operation in the peak power usage periods of summer months, Power Plants will also be able to export more Power to the grid, thus reducing consumer pricing. The net result will be that Power Plants profits will increase through reduced costs and increased output capability, while costs to the consumer will decrease, thus resulting in a significant step towards moving towards a sustainable economy, while also minimizing the impact on the environment.

Our team is composed of the technology developer, Vincent Wiltz of Cooling Tower Specialists, having 30 years experience in the Cooling Tower business.

Problem Statement and Proposed Solution

The “Green” Cooling Tower design addresses the problem of achieving optimal cooling capacity in a Power Plant or any Industrial Process. In Power Plants, in order to generate maximum power using minimal steam, maximum energy must be extracted from the steam in the generating turbine. This is accomplished by minimizing the pressure of the steam on the outlet of the turbine, which is achieved by maximizing steam condensing capacity. This is accomplished by minimizing cooling water supply temperature.

Cooling water flow is used in a shell and tube heat exchanger to condense steam. The lower the cooling water temperature, the lower the steam condensate temperature, and consequently, the lower the steam pressure on the outlet of the turbine. By lowering the pressure of the steam on the outlet of the turbine, or increasing vacuum, more energy is extracted from the steam in the generating turbine. Therefore, a larger quantity of Power can be produced from the same flow of steam. As cooling water temperature rises in summer months, vacuum pressure rises as well, thus reducing the amount of energy derived from the steam across the turbine. The “Green” Cooling Tower technology increases the cooling capacity of an existing Cooling Tower, achieving a reduction in supply water temperature in the range of 3 to 5 deg F during summer months. This translates to an increase of Power Plant efficiency in the range of 1 to 10 %.

In many Power Plants, the capacity of the Cooling Tower is the limiting factor relative to plant efficiency and power output capability. Also, most Cooling Towers use a significant amount of electricity to generate air flow used to cool the circulating water which has been heated by the condensing of steam. The flow of water required to condense steam is significantly high, and the pressure of the water must be sufficiently high enough to circulate this high water flow through the plant’s condenser and up to the top of the Cooling Tower, which is normally an elevation of 30 feet or higher. Large Electric motors, often operating in the range of 1000 HP, are used to drive pumps which flow this cooling water from the Cooling Tower basin through the plant, and back to the top of the Cooling Tower. This return water has significant hydraulic energy generating capability at the point on the return header at the base of the Cooling Tower.

The “Green” Cooling Tower harnesses this hydraulic energy to drive a hydro-turbine, which turns a fan shaft and 24 ft diameter fan blades on the unit. A sufficient amount of air flow is generated by this mechanism to cool 3500 gpm of water flow supplied to the turbine to the optimal approach to the saturation (wet bulb) temperature of the air. This cooling is done by draining the return water out of the hydro-turbine into a spray nozzle assembly which distributes the water evenly across a 30 ft by 30 ft, 4 ft depth section of film fill. The air flow generated flows upwards in a counter-flow fashion, exchanging heat with the water across the film fill. The water then drains back into the existing tower’s basin. Furthermore, by unloading water flow/heat loading from the existing tower, the existing tower achieves colder water with the same amount of air flow in summer months, thus reducing overall supply water temperature. The amount of reduction in water temperature achieved is dependent on the baseline performance capability of the existing tower and the number of “Green” Cooling Tower units applied. In winter months, air flow and hence electrical usage can be reduced on the existing Cooling Tower fans with the “Green” Cooling Tower supplying supplemental cooling capacity.

On a most basic level, this technology uses water to generate wind, with the wind cooling the water down to the optimum temperature. By unloading water from the existing tower, more efficient cooling is achieved with the electricity consumed to drive the fans. A sufficient amount of “Green” Cooling Tower units are applied to result in optimal water temperature. This then leads to optimal steam efficiency across the Power Plant turbine. While Wind Turbines are routinely being used to produce “green” electricity, this technology utilizes a reverse version of the wind turbine to make Power Plants run more efficient, taking advantage of the hydraulic power which is inherently available in most Power Plants.

This technology is currently filed with the US Patent office, patent pending. The first proto-type unit, 6 ft x 6 ft, was installed at a Refinery in Louisiana in May of this year. This unit is effectively cooling 150 gpm across a 25 deg F cooling range down to 84 deg F at a 79 deg F wet bulb temperature.

The first full scale, 30 ft x 30 ft, unit has been installed at the CITGO Refinery in Sulfur, Louisiana. The unit has been proven to effectively operate with supplied water pressure between 10 psig and 25 psig. The higher the pressure, the higher the air flow generated, the higher the water/ heat loading capability. Design water loading is 3500 gpm with 20 psig supply pressure. At lower air flow generation rates with lower pressures (10 psig), water loading is reduced to 2000 gpm. The unit installed at CITGO is only being supplied continuously with 1700 gpm of water flow, limited by the supply capability of the system on which the unit has been installed. On this application, 85 deg F cold water is being obtained at a wet bulb temperature of 80 deg F. Implementation of this unit has reduced the overall cold water temperature of the entire system by 10 deg F, allowing for a costly rental chiller to be removed from service.

We are moving towards full-scale commercialization, focusing on Power Plant markets in Louisiana/Texas and the North East where the largest impact can be made. The only alternative to achieving similar results besides installing additional Cooling Tower cells would be to utilize rental towers. These units require electricity to drive the fans, thus making the “Green” Cooling tower option superior from the standpoint of operating costs and environmental impact.

Project Benefits

Actual benefits are dependent on the condenser capacity and vacuum leaks within the turbine exhaust system. Case studies have been conducted on typical applications in which seasonal data has been analyzed to determine the correlation between condenser vacuum and cooling water temperature. Also, theoretical calculations have been compiled for a Power Plant having a capacity of 285 MW, which assume a liner reduction in condensate temperature/pressure with cooling water temperature. Taking into account this data, the following generalizations/approximations can be stated:

For every 1 deg drop in CW temperature:

Steam savings on Turbine (BTU/hr)= 1MM BTU/hr

Corresponding Natural Gas cost reduction= $6,500/month

Corresponding Reduction in Coal cost= $3,000/month

Based on this case study, a 4 % increase in turbine efficiency was achieved with a 1 deg decrease in cooling water temperature.

As previously stated, the total reduction in supply water temperature achieved through implementing the “Green” Cooling Tower technology is dependent upon the baseline performance of the existing tower and the number of “Green” Cooling Tower units applied. Typically, applications pursued will result in a supply water temperature reduction ranging between 3 and 5 deg F. Hence, assuming turbine system performance similar to the case study above, the following range of cost savings can be realized through implementation of this technology:

Steam Savings:

Min= 3 MM BTU/hr; Max= 5 MM BTU/hr

Natural Gas Cost Savings:

Min= $19,500/month; Max= $32,500/month

Coal Cost Savings:

Min= $9,000/month; Max= $15,000/mo

Coal usage reduction= 4 tons per day

CO2 generation reduction= 8 tons per day

Besides these cost savings, Power Plants will also achieve increased revenue in terms of increased Power output to the grid. At current power prices ($45/MW), 1 MW of increased power output is worth approximately $7,000/month.

With regards to greenhouse gas emissions, reduced boiler firing resulting from the reduced turbine steam usage will directly result in a reduction of greenhouse gases ranging from 12 to 20 %. This reduction also carries a financial benefit in terms of carbon credits, as the carbon footprint of the Facility is reduced.
Power Plants will reap the benefits of this technology, as will consumers who will reap the benefits of reduced electricity costs and a cleaner environment.

All Units will be performance tested upon installation, and will be monitored closely across a 5 year life cycle. Appropriate routine maintenance will applied to the units by Cooling Tower Specialists to ensure that optimal cooling efficiency is maintained. Performance data on all units will be monitored remotely from a real time data acquisition system installed on the units.

Our Team will work closely with each customer to understand the actual benefits obtained in the Power Plant as a result of the increased cooling capacity. We will then use this data to market the technology further.

Conclusion

The Green Cooling tower is a cost effective solution for any Power Plant or other Industrial Facility which currently has limited cooling capacity or can benefit from colder cooling water. Alternatively, this design allows for an existing level cooling to be achieved using less energy, which nearly all facilities should benefit from. Most importantly, this design can lead to a significant, positive impact on the environment. Immediate steps should be taken by anyone reading this report to work with our Team to customize a Green Cooling Tower Solution to fit your specific application.