Mauri Products, Hull - Sulfurex

Mauri Biogas Project

This case study highlights a premier example of the creation and use of a renewable energy source and the savings that this can offer.

Background:
Heat & Power Services were already maintaining an energy saving CHP system at Mauri Products when changes in government legislation meant that effluent from the yeast plant, originally disposed of untreated into the Humber estuary, now had to be treated. To have paid a third party for the disposal would have made the whole plant uneconomic and so the company constructed a bio-waste treatment plant in which the main product from this (methane + some hydrogen sulphide) was burnt on a steam boiler to release a higher value product i.e. steam. Heat & Power Services however advised that the gas would be better burnt in a gas engine to produce electricity, steam and hot water (a 10-fold higher value product). As hydrogen sulphide is a contaminant in the biogas and would be damaging to a gas engine this required prior removal.

Further government initiatives on renewable energy meant there was a special payment rate for any electricity produced by renewable means (‘ROCS’ scheme)

Intervention:

Initially the tender issued by Mauri Products was to convert the existing engine to run on both natural gas and the bio-gas (scrubbed of hydrogen sulphide). However Heat & Power Services successfully argued that the very best course of action was to install a new bespoke CHP plant with dedicated engine and biogas treatment plant (hydrogen sulphide removal). As the projected monthly income revenue and savings from such a plant were so large, Heat & Power Services argued that with the price and delivery time on a new engine (£180,000 and ~1 year) a more profitable option would be to acquire a reconditioned engine foremost. As such Heat & Power Services rebuilt an existing Caterpillar engine in Holland and installed and commissioned it within 4 weeks for £100K. We also installed and commissioned a bio-gas treatment plant, a heat recovery system with boiler, a heat recovery system for hot water and finally heat rejection equipment. The treatment plant continues to be maintained by us alongside the CHP plant. We also designed and installed the control panel, and programmed the PLC for the bio-gas treatment plant /engine interface so as to minimise maintenance down time.

New bespoke CHP plant and dedicated upgrade biogas treatment plant and gas scrubbing


Outcome:
This efficient harnessing of renewable energy has meant huge savings to Mauri Products. The biogas (a free by-product of the waste treatment plant) generates electricity, steam and hot water, all of which is re-used by the main yeast plant. Typical availability of the CHP system is 96%. Recovered hot water is even used to heat the waste effluent that is producing the biogas! The company recovered their start-up costs in a very short space of time and continue to benefit.

Testimony: Colin Van Eck, Technical Manger at AB Mauri

Since its inception in 2006 the management and operation of the biogas caustic scrubbing process through to the operation of the CHP engine has been contract out to Heat and power Services, who initially advised us in respect of the purchase of the required capital equipment and then carried out the installation work. The caustic scrubber we use to clean up the biogas was designed by DMT specifically for our biogas, which typically consists of 65 to 70 % methane, 30 to 34 % C02 and anything between 2000 and 20 000ppm H2S, dependent on the substrate in use in our factory. The effluent leaving the scrubber is pumped across to our aeration basins where the entrainedH2S is first oxidised before going to the city sewers (direct release to the sewers would result in the H2S being released as the pH drops). The caustic usage by our scrubber has been found to be within the laid down design limits and is dependent on the H2S content of the biogas and provided the scrubber is operated in accordance with the manufactures recommendations we find no significant entrapment of C02.

To date we are happy with both the service from Heat and Power Services and the equipment we have installed, and would happily discuss the same over the phone.