Energy shortage and environment deterioration arebeing two major issues with society development. At present, a large amount of waste heat and pressure source are discharged directly, which not only waste the energy also caused damage to the environment. Kaishan screw expansion power generation technology is appeared under this background, and provide a set of solution for waste heat and waste pressure utilization.

Kaishan screw expansion power generation unit include direct expansion power generation unit and Organic Rankine Cycle (ORC) power generation unit. In order to take full advantage of waste energy, Kaishan provides high efficiency single and cascaded direct expansion power generation cycle, single and cascaded ORC power generation cycle, cascaded direct expansion and ORC power generation cycle with patent technology to achieve maximum earning for customers.

“First-class core technology and high quality manufacture” are main target for Kaishan. Core technology, experienced team group, and high quality manufacture are three important foundation of Kaishan screw expansion power generation unit. Kaishan own top-world research expert and “North America Research Center” was built at Seattle in 2009. An experienced international teamhas been established with the leader of Dr. Tang from application, design, manufacture, installation, operation and project management. The group provide quick action and good performance product from the initial heat source investigation to the final customer training.Dr. Tang patent rotor type is used in Kaishan screw expander, which bring up to 88% isentropic efficiency and reach high level. In addition, Kaishan owns screw pump, heat exchanger and system structure number of patented technology, which make screw expansion power generation system operate with high efficiency and high reliability. For unit manufacture, Kaishan have MITSUI SEIKI, DOOSAN, HOLROYD, KAPP, CARL ZEISS, and HEXAGOON first-class manufacture and measurement equipment. The test lab of screw expander and power generation system provide guarantee for unit performance.

Screw expander is a volumetric expansion machine. Usually refer to double screw expander. Kaishan screw expander is designed and optimized for gas expansion. The expander is mainly composed of shell and a pair of screw rotor. The high pressure gas or steam flow into cavity adiabatic expansion and drive rotor rotation, the gas pressure and temperature is decreased at the outlet of expander. This process can provide kinetic or power energy. The inlet steam can be saturated or two-phase, and screw expander can keep high isentropic efficiency under wide rangeof load.

At present, Kaishan screw expansion power generation unit has been widely used in industry waste heat power generation, industry waste pressure power generation, geothermal power generation, biomass power generation and other fields. By the end of 2015, About 70 related project has completed and total rated power is 110MW. Projects are mainly distributed in the iron, petrochemical, plastics, fiber, geothermal, biomass and other fields.

Industry Waste Pressure Power Generation

Industry waste pressure mainly include high-pressure process gas and saturated or superheat steam with pressure in steel and chemical factory. Currently, these gas or steam pressure is decreased to required value through pressure reducing value, which waste pressure energy. Kaishan direct expansion screw power generation unit can recover the pressure energy and convert it to electricity energy through a generator, which can bring good benefit for customer.

Direct expansion power generation unit can be divided into back pressure type unit and condensing type unit. Asynchronous or synchronous generator is used for power output. It can be divided into steam type unit or gas type unit according to working medium.

An application case is shown as follows::

Project Location:Jiangsu Chengxing Phosphorus Chemical
Heat Source:30barA & 50t/h saturated steam. 20~25t/h & 12 barA need be used for manufacture process
Project Introduction:Three stages direct expansion power generation units is used. Total rate power 5.5MW and net power 4.4MW

Industry Waste Heat Power Generation

Industry waste heat accounts for 17% - 67% of fuel consumption, but only 60% of the total waste heat resource can be recovered. Kaishan ORC screw expander power plant is suitable to recover industry waste heat directly or indirectly e.g. hot water, hot oil, steam, engine jacket water/exhausted gas and gas-turbine exhausted gas, and finally convert into electricity. According to heat resource gather mode, Kaishan ORC screw expander power plant is categorized as direct recovery ORC unit and indirect recovery ORC unit. It can also be categorized as hot water ORC, steam ORC and other ORC according to different waste heat resource type.

A Kaishan ORC screw expander power plant case is described as follows:

Project Location:Sinopec Beijing Yanshan Company
Heat Source:Gasoline, 135℃in&70℃out, mass flow rate: 125t/h
Project Introduction:A single loop ORC power plant was chosen. Gasoline is led to evaporator & preheater in order to provide heat to R245fa, produce saturated R245fa gas with high temperature & high pressure. The gas go into expander and drives the generator to deliver power. Power plant is in parallel with the original air cooled condenser from customer. If ordinary maintenance or emergency shut-down happens, gasoline is transferred to air cooled condenser for cooling.

This project is remarkable for it’s high efficient power generating based on direct heat exchange with gas oil, no auxiliary medium is involved. In addition, this power plant is designed under the requirement of anti-explosion and high reliability in petrochemical industry. The installed power of screw expander power plant used for Sinopec Beijing Yanshan Company S Zorb process is 900kW, anti-explosion grade: dIICT4. It’s estimated that the power plant could produce 4.73 million kWh net power, save 1656 ton standard coal consumption, and reduce 3934 ton CO2 emission every year. It also saves 0.6048 million kWh energy consumption annually on original air cooled condenser. Kaishan cooperated with SEG(Sinopec Engineering Group) to integrate both advantages after 《Energy Saving Services Cooperation Agreement》contractwas signed in June 2015. This project is also an outstanding and typical low grade energy recovery solution provided by KS & SEG together.

Geothermal Power Generation

Geothermal energy is continuous renewable energy. Geothermal power plant is one kind of energy transformation process, which converts underground thermal energy to mechanical energy and then convert the mechanical energy to electric energy. Kaishan first put forward “ONE WELL, ONE PLANT®” - decentralized geothermal power plant concept, and develop mature application technology and solution. As a solution customized and optimized for one well port or several close well ports, this technology will definitely maximize the energy utilization efficiency, and coupled with Kaishan efficient cascade power generation technology, the power plant thermal efficiency will be much higher.

Characteristics of “ONE WELL, ONE PLANT®” are as follows:

  Even one single production well could generate power, no waste wells, every production well could be used.
  Could be equipped near the well port, almost no energy loss, and the cost of the electrical wires is lower compared with the pipeline which feeds into the central power plant.
  Use customized and optimized solutions for different energy levels production wells, with maximized net output power and thermal efficiency.
  Kaishan Patent hybrid cycles and Cascade technologies shall be used to consume the energy from both the steam and brine.
  Short construction period, 6-7 months later, the geothermal power plant is on gird.
  Low initial investment, generate revenue quickly, and use the generated revenue to finance the new development.


Application case of Kaishan geothermal power generation is shown as follows:

Project Location:America Alaska Chena geothermal hot springs village
Heat Source:Geothermal water temperature: 82℃; Return water temperature 65℃
Project Introduction:According to the geothermal conditions, single stage ORC power plant is used in this project. The capacity is 400kW and net output power is 312kW. Geothermal hot water flow into evaporator in the ORC system directly, and then pre-heater. Hot water heat R245fa into high temperature & high pressure vapor in the heat exchanger, after that the vapor will flow into screw expander, drive the expander to output mechanical energy and then drive the generator to output electric energy to the grid.
Considering that the local temperature is low and river water is available, water cooled condenser is chosen in this application to improve the thermal efficiency.
The whole unit is modularized package design using container size, which is continent to transport.

Biomass Power Generation

Biomass power generation is a kind of renewable energy power generation of using biomass energy, which including direct combustion or gasification power generation of agriculture and forestry waste plant, garbage burning power generation, and biogas power generation. Kaishan direction expansion unit, ORC unit and cascaded unit can be used for this field.

Abiomass power plant case is listed as follows:

Project Location:The Philippine Buluan Biomass Power Plant
Heat Source:1) 226℃&30t/h saturated steam. 2) 115℃& 4.3t/h saturated steam.
Project Introduction:For heat source 1, three stages direct expansion power generation units is used with total rate power 3.11MW and net power 2.5MW; for heat source 2, an ORC unit is used with rate power 0.4MW and net power 0.25MW.