The world's energy demand is growing constantly. Many industries aim to reduce their ecological footprint by minimizing energy consumption. Reducing energy consumption is a major cost saving driver. Hydraulic Power Recovery Turbines can be used to save energy. There are two basic types: Impulse (Pelton wheel) and reaction type.
Generally, pumps are a means of fluid transport which convert mechanical energy into hydraulic energy. Pumps increase fluid pressure and flow. When process conditions call for pressure to be dissipated, a pump running backwards may be applied as a reaction turbine to capture that otherwise wasted energy (e.g. by throttling in a valve, dissipating the pressure energy in heat).
Most centrifugal pumps can be modified to run in reverse as turbines. A Hydraulic Power Recovery Turbine is used to transform potential energy (fluid flow at high pressure) into mechanical energy (shaft power). The potential for power recovery exists any time a fluid flows from high to low pressure, and involves a throttling device such as valve, orifice, expansion chamber, etc.
Applications:
- Gas treating with Amine, Ammonia, Selexol, Sulfinol, etc. to remove H2S and CO2
- Hydrotreating and other processes in refineries
- Potassium Carbonate service in a fertilizer plant
- Chemical processes, i.e. gas scrubbing, ammonia synthesis, coal gasification
- Cooling of coal mines
- Oil and refined product pipelines
- Water supply systems
The advantages of HPRT's are:
- Substantial cost savings
- Save space
- Provide reliable and useful operation for years of service
- Reduce net emissions
Short pay back times
In many industrial processes, HPRT's can provide substantial savings with a short pay-back period. It is not uncommon to find that over 1.5 MW can be recovered. Careful attention to process conditions and HPRT controls assure reliable, useful operation for years of service.
Sulzer Pumps builds a number of single stage and multistage HPRT's. We have many years of experience and expertise in this field. The pump types modified for HPRT use are often double suction, horizontally split, single or multistage, ring section, barrel casing, or vertical turbine pumps.
Single stage, double suction pumps include the HSB and BBS/CD.
Axially split multistage pumps include the MSD
Ring section pumps include the MC and MD
Barrel casing pumps include CP, GSG, and HPT
Vertical pumps include SJT, SJP and SJM
Examples:
Example 1: HPRT used in Mine Cooling
We provided a complete HPRT train to a mining company. The equipment is used to cool the air within the mine. From the surface cold water is supplied into the mine to a depth of 450 m (1,500 ft) for use in spray air coolers. In order to reduce the high static pressure in the spray chamber and to recover energy, a turbine is installed, being a multistage reverse-running pump. From the spray chamber, the water will be pumped back to the surface. The return pump system comprises one operational unit and one standby unit. 42 % of the pump-required power will be delivered by the energy recovery from the turbine.
Example 2: Oil Company is using pumps as turbines instead of throttle valves
Liquid charged with gas must be expanded in a scrubbing tower. Sulzer Pumps worked with the customer's engineers to understand the multiphase flow. That knowledge was then used to design the HPRT's hydraulics and rotor. The experience of Sulzer Pumps in designing such HPRT's helped to find a solution for these challenging conditions.
Between the inlet and outlet of a turbine, the pressure drops in very short time. Gas dissolved in the fluid at high pressure diffuses out of the liquid causing gas bubbles to form, resulting in 2-phase flow. The required pressure reduction is from 74.8 bar (1080 psi) to 14.8 bar (210 psi). A 5-stage HPRT with one dummy stage was chosen, so that a further stage may be fitted for smaller flow rates in the future. The continuous power of 258 kW recovered from the expansion assists the 870 kW motor driving the pressure increasing pump.
If you want more information, please contact us directly on hpi.pumps@sulzer.com