Michael Bartlett

First Experiments on an Evaporative Gas Turbine Pilot Power Plant: Water Circuit Chemistry and Humidification Evaluation

The evaporative gas turbine (EvGT), also known as the humid air turbine (HAT) cycle, is a novel advanced gas turbine cycle that has attracted considerable interest for the last decade. This high-efficiency cycle shows the potential to be competitive with Diesel engines or combined cycles in small and intermediate scale plants for power production and/or cogeneration. A 0.6 MW natural gas-fired EvGT pilot plant has been constructed by a Swedish national research group in cooperation between universities and industry. The plant is located at the Lund Institute of Technology, Lund, Sweden. The pilot plant uses a humidification tower with metallic packing in which heated water from the flue gas economizer is brought into direct counter current contact with the pressurized air from the compressor This gives an efficient heat recovery and thereby a thermodynamically sound cycle. As the hot sections in high-temperature gas turbines are sensitive to particles and alkali compounds, water quality issues need to be carefully considered. As such, apart from evaluating the thermodynamic and part-load performance characteristics of the plant, and verifying the operation of the high-pressure humidifier, much attention is focused on the water chemistry issues associated with the recovery and reuse of condensate water from the flue gas. A water treatment system has been designed and integrated into the pilot plant. This paper presents the first water quality results from the plant. The experimental results show that the condensate contains low levels of alkali and calcium, around 2 mg/l Sigma(K,Na,Ca), probably originating from the unfiltered compressor intake, About 14 mg/l NO2- +NO3- comes from condensate absorption of flue gas NOx. Some Cu is noted, 16 mg/l, which originates from copper corrosion of the condenser tubes. After CO2 stripping, condensate filtration and a mixed bed ion exchanger the condensate is of suitable quality for reuse as humidification water The need,for large quantities of demineralized water has by manY authors been identified as a drawback for the evaporative cycle. However, by cooling the humid flue gas, the recovery, of condensed water cuts the need of water feed. A self-supporting water circuit can be achieved, with no need for any net addition of water to the system. In the pilot plant, this was achieved by cooling the flue gas to around 35degreesC.

Performance and Cost Analysis of Advanced Gas Turbine Cycles With Precombustion CO2 Capture

This paper presents the results of an evaluation of advanced combined cycle gas turbine plants with precombustion capture of CO 2 from natural gas. In particular, the designs are carried out with the objectives of high efficiency, low capital cost, and low emissions of carbon dioxide to the atmosphere. The novel cycles introduced in this paper are comprised of a high-pressure syngas generation island, in which an air-blown partial oxidation reformer is used to generate syngas from natural gas, and a power island, in which a CO 2 -lean syngas is burnt in a large frame machine. In order to reduce the efficiency penalty of natural gas reforming, a significant effort is spent evaluating and optimizing alternatives to recover the heat released during the process. CO 2 is removed from the shifted syngas using either CO 2 absorbing solvents or a CO 2 membrane. CO 2 separation membranes, in particular, have the potential for considerable cost or energy savings compared with conventional solvent-based separation and benefit from the high-pressure level of the syngas generation island. A feasibility analysis and a cycle performance evaluation are carried out for large frame gas turbines such as the 9FB. Both short-term and long-term solutions have been investigated. An analysis of the cost of CO 2 avoided is presented, including an evaluation of the cost of modifying the combined cycle due to CO 2 separation. The paper describes a power plant reaching the performance targets of 50% net cycle efficiency and 80% CO 2 capture, as well as the cost target of 30

A Study of Humidified Gas Turbines for Short-Term Realization in Midsized Power Generation—Part I: Nonintercooled Cycle Analysis

per ton of CO 2 avoided (2006 Ql basis). This paper indicates a development path to this power plant that minimizes technical risks by incremental implementation of new technology.

A Study of Humidified Gas Turbines for Short-Term Realization in Midsized Power Generation—Part II: Intercooled Cycle Analysis and Final Economic Evaluation

Humidified Gas Turbine (HGT) cycles are a group of advanced gas turbine cycles that use water-air mixtures as the working media. In this article, three known HGT configurations are examined in the context of short-term realization for small to midsized power generation: the Steam Injected Gas Turbine, the Full-flow Evaporative Gas Turbine, and the Part-flow Evaporative Gas Turbine. The heat recovery characteristics and performance potential of these three cycles are assessed, with and without intercooling, and a preliminary economic analysis is carried out for the most promising cycles.

Modelling of Alkali Contaminant Flows in Evaporative Gas Turbines

Humidified gas turbine (HGT) cycles are a group of advanced gas turbine cycles that use water-air mixtures as the working media. In this article, three known HGT configurations are examined in the context of short-term realization for small to mid-sized power generation: the steam injected gas turbine, the full-flow evaporative gas turbine, and the part-flow evaporative gas turbine. The heat recovery characteristics and performance potential of these three cycles are assessed, with and without intercooling, and a preliminary economic analysis is carried out for the most promising cycles.

Method of generating energy in a power plant comprising a gas turbine, and power plant for carrying out the method

A new advanced gas turbine cycle, called the Evaporative Gas Turbine (EvGT), also known as a Humid Air Turbine (HAT), has recently been demonstrated in Sweden, with a pilot plant built and operational. As the EvGT cycle involves complex interactions between air and water streams, air quality aspects need to be carefully examined. This article examines different strategies to prevent contamination and turbine corrosion and presents a theoretical model simulating the flow of alkali salts in the EvGT cycle for different ambient salt concentrations, cycle configurations and equipment performance.Similar to the existing pilot plant, the EvGT cycle studied in this article requires no external water source to meet its water demands. Instead, water is condensed from the flue gas and recycled to the humidification tower. Recirculating the condensate implies that the best strategy to ensure a high air quality and hinder impurity build up and transfer within the cycle is to filter the incoming air. Furthermore, air intake filters could simplify or eliminate the need for condensate treatment. The humidification tower is an important area for the transfer of contaminants to and from the water and air streams. Minimising droplet entrainment and bleeding off a fraction of the humidifying water are key strategies to protect the turbine, while the capture of airborne particles in the humidifying water film improves the air quality.The model constructed predicts that a small blow down from the water circuit (typically 0.1-3.5% of the feed water flow) is sufficient to ensure that the alkali concentration does not exceed those in an equivalent dry gas turbine. This blow down can then be treated and partly recycled to the water circuit or discarded.Copyright